Musings and forecasts of Andalusian weather and climate, from a veteran meteorologist.
By: esteban9, 7:56 AM GMT on February 28, 2010
The aftermath of the "perfect storm" is related here. To be sure, the storm was not good, as its effects caused 3 deaths and power cuts to 135 thousand people; I noticed a gust to 100 km/hour at Vigo. But it didn't seem as bad as one would have been led to believe by the press. It's best to be prepared of course, but I think that the dramatic phrase borrowed from the movie should be reserved for more catastrophic events. The borrasca was given a name, however, Xynthia. I'm not sure if I like this practice, either, but perhaps it is just my prejudices acting up.
The strong winds arrived late to Andalucia yesterday, with one 40 knot gust at Seville. There was very little rain with the storm in the south, which also surprised me somewhat. This occurrence was a relief to the water resource managers, who have to make decisions about releasing water from the dams (which continues at numerous sites).
This dry period will end today, as a band of light precipitation moves into the western part of Iberia this afternoon. Mean areal precipitation should be on the order of 2 mm with this minor wave. A more powerful cyclone looms for Tuesday. The models subsequently develop a "double barrel" low pressure pattern with this event that, if it verifies, would give eastern Andalucia a significant dose of precipitation, particularly on Wednesday. We shall see if this (relatively) dry part of the region gets "treated" like the western half has in February.
Updated: 8:01 AM GMT on February 28, 2010
By: esteban9, 7:56 AM GMT on February 27, 2010
Imagine my surprise upon waking this morning and not hearing the trees rustling from the forecast high winds. What happened?
Well, the rapidly deepening cyclone is still out there, with its center west of the southern coast of Portugal. Apparently, this storm is much more compact than shown by the models, so its tight pressure gradient doesn't extend into Spain yet. It is not surprising that some characteristic like this would be poorly forecast by the models, since they are deficient in handling rapidly deepening storms (cyclogenesis). Only now has the wind field begun to respond, with 20 knot southeasterlies at Jerez de la Frontera. Everywhere else has light winds, including Faro at only 9 knots! There is a well organized north-south band of precipitation across southern Portugal and points south, however.
What does all this mean? I believe that the cyclone is moving faster than progged; given that along with its more compact size, Andalucia will escape most of its effects. The mountains of the westernmost provinces, Sierra Morena and Sierra de Aracena, will see some high winds, 50 knot gusts or more, along with the best chances of showers. Elsewhere in the west it will just be another windy day; eastern Andalucia will be relatively quiet. So it's just time to sit back and see how the storm plays out elsewhere in Spain and see if AEMET's continued orange and red alerts are verified.
The models bring in band of precipitation tomorrow afternoon with a weak wave entering from the west. So enjoy the unexpected (partly cloudy) sunshine today. I guess that the lesson is (again) that the models must be questioned the most when significant weather is developing (just when one needs them the most). Lesson noted.
One additional note, since I couldn't get the data yesterday, about our hydrologic situation. Here is the precipitation map in the Guadalquivir basin for Thursday. Widespread, not insignificant amounts fell in the headwaters areas, east of Cordoba. This didn't help the situation, although the river level as a whole has declined in the last couple days. It sure didn't appear so in Seville yesterday, as the river has recently exceeded its banks in many places, with a very fast flow in the middle. It feels odd, as a "newbie" to the area, to have documented this historic event (worst in 40-60 years) before its inception.
Updated: 8:11 AM GMT on February 27, 2010
By: esteban9, 1:20 PM GMT on February 26, 2010
By: esteban9, 7:39 AM GMT on February 26, 2010
The warm front has been delayed a bit, so precipitation was light last night. Unfortunately, I was unable to get yesterday's total precipitation maps from either HIDROSUR or SAIH Guadalquivir. The front should traverse Andalucia in the next 12 hours, so look for continued light-moderate but widespread precipitation today. Lots of deep moisture on the Gibraltar sounding from 0000 UTC, so any kind of lifting mechanism like the front should trigger precipitation.
An interesting story this morning from El Pais. It quotes the Agencia Andaluza del Agua as saying that the south has received an (average) of 610 mm since December 15, making it the wettest such period since 1963. This has caused the major river in the community, the Guadalquivir, to rise sufficiently to cause flooding in six municipalities and force evacuation of 600 houses. The article goes on to call tomorrow's event a "perfect storm" or "meteorological bomb," bringing winds of over 120 km/hour to much of the peninsula (AEMET has over 2/3 of it under at least yellow alert). This wording suggests that the UKMO's forecast of a rapidly deepening cyclone was correct. So what is UKMO showing today?
Well, they have backed off a bit and come toward the models with only a 968 central pressure. Nevertheless, while the models continue to argue for a shallower low, now several are progging its path INLAND, directly over Galicia. The UKMO maintains its earlier path, just skirting that province to the west. If the inland track is correct, damaging winds will penetrate much further east, into the heart of Spain. In any event, either the stronger UKMO cyclone OR the more inland one of the models will produce hurricane-force winds along the northern coasts and in the mountains ("six of one, a half dozen of the other").
Although a lesser story than the wind across the entire country, a concern for the south is of course any additional rain tomorrow. The models all concur that most of the precipitation will again fall to our north and west. True enough, but I believe that this is an under-forecast for our region. The UKMO progs depict a vigorous cold front to the south of the cyclone, which moves through the south tomorrow afternoon. Given the intensity of the rapid cyclogenesis and abundant moisture already in place, this front should be more than adequate to generate significant rain tomorrow. These rains will be on top of those that will occur today, again causing hydrologic headaches for the region. And another significant wave is progged for Sunday. Same story, different day!
Updated: 8:37 AM GMT on February 26, 2010
By: esteban9, 4:23 PM GMT on February 25, 2010
OK, rainfall rates have not been on the light side as anticipated, particularly in Cadiz and western Malaga provinces, where precip is widespread and moderate at this time. This is going to exacerbate the hydrologic problem downstream from those mountainous areas, particularly if more rain follows up tonight in the same areas, with the approaching warm front. Look out again along the Guadalhorce, Guadalete, Guadiaro, and Barbate rivers for more flooding.
By: esteban9, 10:45 AM GMT on February 25, 2010
I came across this summary of the rainfall this February in Seville (written yesterday, in Spanish). It says that only 2 mm of rain are necessary to break the record for wettest February ever, which occurred in 1978, with 166 mm. No doubt the rain that will occur over the next 24 hours will provide us with the wettest February in 32 years. Compare also the long-term mean February Seville precip of 55 mm. And as you know, December and January were also exceedingly wet...when it's over, this winter will be one to remember for decades to come. (Climatologically, Seville has a secondary maximum of precip in April - second only to December).
And of course, Seville has not been alone in this story. The wettest village in Spain is (surprisingly to many) Grazalema, in the mountains on the border of Malaga and Cadiz provinces. The long-term average precip there is 2153 mm. Although no doubt this area has been inundated with rain too, it seems like the maxima have been occurring further south this year, in Los Alcornocales mountains of eastern Cadiz province. For example, the precipitation since about mid-December at Sierra de la Luna, just west of Algeciras, has been 1853 mm...a stunning amount over two and a half months!
One other thing I wanted to show...related to the most devastating impact of this winter's rain...is the horrific flood event on the Portuguese island of Madeira. Here is the enhanced infrared satellite picture during the time of this disaster. This image shows the temperature of cloud tops. If you click the image to zoom it, Madeira is visible as the small island outlined in black, about 7 1/2 degrees longitude west of the central Moroccan coastline. Note the spots of red in the image directly over the island. These spots show very cold (about -70C), high-elevation clouds, which is the signature of deep thunderstorms. Also note the long "train" of clouds feeding into the area from the southwest. I believe that these phenomena contributed to the heavy rainfall, combining with the unique geography surrounding Funchal to devastate that city with flooding and mudslides. From the pictures and terrain data I've seen of the city, it has several deep canyons to its north that funneled the heavy rain down into the city. A rare event, to be sure, but it shows how topography can act in concert with weather to cause a catastrophe.
Updated: 10:49 AM GMT on February 25, 2010
By: esteban9, 8:36 AM GMT on February 25, 2010
Light showers are developing in western Andalucia at press time; behind it is a heavy precip band draped across northern Portugal. Newer models persist in their solution that our area will escape the brunt of the precipitation today, as that will occur to the north and west. The UKMO surface analysis is also consistent, however, in dragging a cold front across the area today. This front does not have much upper level support or moisture...the Gibraltar sounding (there was one, yay!) shows shallow (to 700m) moisture and little instability. Therefore I'd expect bands of rain moving from west to east today, with light accumulations. These elements will affect mostly the western and northern provinces.
The models are beginning to reach consensus on the warm front I mentioned yesterday and, alas, they show it moving across Andalucia from the south beginning overnight (the earlier optimism about fair weather tomorrow has faded). So what the coasts miss in precip today, they may make up overnight. The warm front will continue its trek across the remainder of the region tomorrow, but again the models are predicting light amounts. There is some uncertainty about this, however; see the following discussion.
The parent cyclone of this warm front, moving out of the southwest, continues to be a concern. As I mentioned yesterday, there is a distinct disparity between the UKMO surface prog (a mix of human and computer model analysis) and the computer models. The former once again shows a very deep (964 millibars) cyclone west of Lisbon by midday Saturday. And again, even the most "bullish" computer model is showing a much weaker cyclone, by 12 millibars! I expressed doubt about the UKMO solution yesterday but, if they're wrong, they're being consistent! I am waffling in my position today, however, not only because of this consistency, but because I looked again at yesterday's model runs vs today's. Yesterday's models forecast the current cyclone (west of Galicia) as too weak. If this under-forecasting is a trend, then one should lean toward the UKMO solution. Unfortunately, there is no online discussion from the UKMO as to their thinking behind their surface progs.
The bottom line is that, if the UKMO is correct about the approaching cyclone, then its warm frontal precipitation tomorrow and overall impacts on Saturday will be much more intense than the computer models suggest. Again, this means that Portugal, the Costa de la Luz, and western Andalucia will be hit hard with winds and rain on Saturday (the rain should be short-lived, however, so it will hopefully not severely impact our precarious hydrologic situation). See yesterday's blog for a link to the UKMO solution, which hasn't changed much. Even so, the focus of Saturday's storm will be (mercifully for our region) the northwest quadrant of Iberia on Saturday afternoon and evening. I wouldn't want to be in Galicia or north central Spain during that period, as confidence is high that we'll see widespread wind damage in these areas.
It should be very interesting to see how Saturday's temporal develops. As to its impacts on Andalucia, I think I'll have to see the "whites of its eyes" tomorrow before committing to a more certain forecast. I guess I'm not ready to play poker with the UKMO just yet, given my short experience with western European weather in comparison with theirs!
Updated: 8:40 AM GMT on February 25, 2010
By: esteban9, 9:05 AM GMT on February 24, 2010
The aforementioned ridging looks on target today, with small pressure gradients (less wind) and a nearly clear radar scope across Andalucia. A few showers may pop up, especially over the high terrain, as there is a little lingering instability. The coverage of these showers will be substantially less than yesterday, however.
The certainty in the forecast disappears tomorrow, however, as rain of some magnitude returns. The models are variable in the amount of rain, leaning toward the light side, at least in comparison to what we saw last week. The focus of wind and rain will be in the northwest quadrant of Iberia, for sure. Nevertheless, the UKMO surface progs analyze dual cold fronts traversing Andalucia during daylight hours tomorrow, so accompanying north-south aligned bands of showers seem to be a good bet.
After these features clear out tomorrow night, Friday is shaping up to be another fair day similar to today. Well, apparently it's a lot to ask for two CONSECUTIVE fine days!
The window of calm shuts abruptly Friday night, with the arrival of a warm front from a storm moving in from the southwest. The models depict little precipitation accompanying this front through the south, preferring instead to predict this rain in the northwest of Iberia. But the models also show the low to our west rapidly deepening, especially the GFS. But no model has the explosive cyclogenesis of the UKMO surface prog for midday Saturday. It shows a 963 millibar central pressure a little west of Lisbon! I'm not sure what the UKMO is thinking but, if this were to verify, western Andalucia and especially the Costa de La Luz would be blasted with high winds. Given that the last storm that came through the area on a southwest trajectory, on 15 February, was not nearly this powerful, I will tend toward the more conservative model solution for now. This reasoning is buttressed by the fact that Saturday's storm appears NOT to deliver a direct hit on Andalucia like the one on the 15th (progs show a cyclone center track along the Portuguese coast instead). Nevertheless, this storm warrants vigilance, and at the very least, I expect more precipitation with the warm frontal passage than advertised by the models.
In the mean time, carpe diem in the warm sunny conditions!
Updated: 9:13 AM GMT on February 24, 2010
By: esteban9, 9:43 AM GMT on February 23, 2010
Showers and thunderstorms peppered the region yesterday, with significant convection along the Guadalquivir river and in the mountainous headwaters of the Rio Guadalete (see yesterday's basin precipitation map). The latter area also saw heavy rain before dawn. This is again contributing to the flooding flows downstream on the Guadalete, east of Cadiz. The Barbate reservoir is 108% of capacity this morning. Here is the reservoir water release situation in the Guadalquivir as of this morning. I interpreted this map incorrectly in an earlier blog, thinking that the controlled releases (designated by red tags) was more serious than the blue tags ("Por Aliviadero de labio fijo"). One would think that red would be used for the more serious situation, but not so. The blue tags signify where water is being released to avoid spilling over the top of the dam! There are many such dams in this condition, according to the map.
No sounding again last night from Gibraltar, but given the active radar screen, I expect that an unstable atmosphere persists over Andalucia today. As surface heating increases this afternoon, showers and thunderstorms should again plague the region, in spite of the models advertising a decrease in precipitation during the day.
The models are, however, maintaining their prognoses of a brief ridging of high pressure tomorrow and a concomitant drying out. But things return to "normal" midday Thursday as the persistent cyclone north of Iberia drags a cold front across Andalucia during the day, in a similar pattern to the last couple days. Another wave arrives Friday, but a more serious storm is looming on the horizon for Saturday through Sunday. A look ahead to Tuesday through Thursday of NEXT week shows high pressure, dry and sunny conditions, per the GFS and CMC ensembles. Since this is a week away, however, confidence is low for this first "extended" break (two days?) of fair weather. But for those of you tired of the rain, a ray of hope perhaps...
By: esteban9, 9:14 AM GMT on February 22, 2010
An organized rainband passed through the western provinces this morning, and its southern part is pounding the Straits area with heavy convection (squall line). There are high rainfall rates (30-40 mm/hour) indicated by radar within this squall over the headwaters of the Rio Barbate and Rio Guadalete; as mentioned in yesterday's blog, these are rivers that are already producing major flooding downstream. So the new rain will likely aggravate these problems.
Today's models are portraying little change over yesterday's situation. More rainbands are progged to rapidly traverse Iberia from west to east today. It's hard to pinpoint any particular area in Andalucia that will be hit hardest with rain, but my guess based on this morning's convection (lightning data) that it will be the Straits area again. The 0000 UTC Gibraltar sounding shows a significant increase of instability over the previous (1200 UTC yesterday) sounding, with cloud buoyancy to at least 7 km altitude. Therefore, thunderstorms could occur anywhere in the region and likely won't be confined to the coastal areas.
The models again are indicating continued unsettled weather tomorrow, with some drying out on Wednesday, when the pesky cyclone to the northwest of Iberia begins its wane and move to the east. This will cause some surface ridging (high pressure) over Andalucia and a cessation of significant precipitation. As mentioned yesterday, the low that fills in behind will generate another band of precip late Thursday, but this low is progged to move out more quickly than its predecessor; moreover, its impacts appear to be more focused on northern Spain, only producing one burst of lesser amounts in the south. But again, as we cannot shake the long-wave cyclonic upper air pattern, another stronger cyclone is depicted behind that one, generating more rain Saturday night into Sunday (so much for the window of fair weather this weekend). As is common at this early stage, however, the strength and position of this storm shows some variation between (CMC, GFS and NOGAPS) models, so we should wait a couple days to see if they reach greater consensus.
By: esteban9, 12:43 PM GMT on February 21, 2010
Although not on the mainland, Portugal's Madeira island suffered greatly from the overnight storm - see this article. At least 38 dead and 100 injured from the horrific flooding. This island is a bit north of the Canaries. A testament to the power of the storm.
Back on the peninsula, problems with excess water continue. The main highway (AP-4) and railroad between Sevilla and Cadiz have been cut by flooding. The airport in Jerez was also closed. All of this in spite of less rain yesterday. The reasons owe mainly to too much water already on the ground - the aforementioned link states that the flooding was exacerbated by releases from Bornos dam. The state of alert remains high all along the Barbate river in Cadiz province.
Updated: 1:08 PM GMT on February 21, 2010
By: esteban9, 9:39 AM GMT on February 21, 2010
Yesterday's models were correct in downplaying precipitation with the first front this morning. The heaviest precipitation from the radar loops was in the lower Guadalquivir river basin and along the coast of Granada and Almeria provinces. But these patches of rain moved through quickly and didn't produce much accumulation. Looking at the current satellite loop, however, the region is not out of the woods today. A vigorous, well-organized band of convection is lashing Galicia and Portugal at present, and this should move into western Andalucia shortly. The Portuguese radars have sensed some cells within this band with rainfall rates up to 40-50 mm/hour, in the southern third of the country.
Most of the models forecast spotty and weak precipitation today. And the 0000 UTC Gibraltar sounding showed low-level stability (between 1.5 and 3 km elevation). But it also indicated very strong warm air advection at these levels, so the stability is likely gone now. Therefore, given this and the existent convective band over Portugal, I anticipate bands of thunderstorms with heavy rainfall rates passing through this afternoon. The models, as expected, do not capture these small-scale convective features well.
The next confluence of the models on an organized precipitation "spoke" south of the deepening western "barrel" of the cyclone is for tomorrow morning. The extent and intensity of this precipitation area doesn't appear any greater than this morning's. As described yesterday, however, this pattern of short wave "spokes" is progged to persist through Wednesday, when the cyclone to the northwest of Iberia finally fills (weakens) and moves northeast. Alas, another cyclone fills in behind it, giving a new threat of rain on Thursday. The "long wave" pattern in the upper air is such that the northeast Atlantic is in a semi-permanent trough, with the polar jet stream unusually far south. All of which means that Spain will not receive an extended period of quiet weather for some time (but MAYBE a brief respite this weekend). Bad news for the "snowbirds" who've tried to escape here from more northerly latitudes! Well, I've read that this has been the wettest winter in 40-60 years for parts of Andalucia, so I suppose it's "our time in the barrel."
By: esteban9, 9:24 AM GMT on February 20, 2010
OK, well, the models appear to have stabilized around yesterday's solution, which is the set up of a quasi-stationary "double-barreled" surface low pressure pattern to the northwest of Iberia. This places Andalucia in an area of very strong westerly, onshore flow. This means that the north Atlantic is "open for business" in terms of moisture availability within this flow. Embedded in this flow are waves that strike the peninsula every 6-12 hours with doses of significant precipitation. This is progged to occur until the first extended break in the pattern, on Wednesday! The first wave that comes in tonight, associated with an occluded front, does not look as potent as the models were portraying a couple days ago, as its precipitation pattern breaks up and weakens after it makes landfall. However, with a negative tilt and strong pressure gradient, winds still look as potent as ever. As mentioned before, the western part of the peninsula (Portugal and Galicia) will bear the brunt of these winds. But Andalucia will also have its share of very strong winds.
So, all in all, the main impact of this "wave train" will be the ACCUMULATED impact of the precipitation through the entire period (about 72 hours). Again, reservoirs are already full and several continue to make controlled releases (the red stations on this map). As would be expected with such small-scale waves, there is much more diversity in the models' precipitation forecasts. By Wednesday mid-day, the GFS shows maxima (around Cadiz/Western Malaga provinces) in the 70-80 mm range, while the CMC is more bullish, with maxima over 100 mm in that same area and around the Sierra de Aracena, north of Sevilla.
Well, if you're tired of the rain, get out today and enjoy the little sunshine we have left!
By: esteban9, 10:03 AM GMT on February 19, 2010
Yesterday's storm, as anticipated, did not bring widespread precip to Andalucia. As evident from the Guadalquivir precip map from yesterday, a small area just east of Cadiz had up to 100 mm, but this is downstream from the reservoirs along the Guadalete so didn't impact them. However, there was again significant rain in the Sierra de Alcornocales, but not as much as with earlier storms (40-60 mm). So, coupled with a "breather" from precipitation today and tomorrow, the area will see some relaxation of the severe hydrologic conditions. This will be needed, however, to brace for Sunday's storm. Also, winds today won't be as strong as I thought, although AEMET has placed the entire Costa del Sol under yellow alert for winds and costeros, and Almeria province is orange (important risk) for such winds.
A quick look at the models shows that they are now bringing in Sunday's storm 6-12 hours earlier, with arrival of the leading cold front around midnight Saturday. The storm still looks potent, causing high winds for the Costa de la Luz and Straits initially. The precipitation amounts don't look as great as midweek's flood-producing event; however, now the models are showing "follow up" waves behind the initial cyclone that could dump significant additional amounts on Monday and Tuesday next week. Since these are new "twists" in the prognoses, I'll wait until tomorrow to view the latest model trends and comment further. Now I'll go out and enjoy this window of sunshine!
By: esteban9, 9:43 AM GMT on February 18, 2010
Looking at the next temporal that is arriving just now from the south, perhaps the main impact this time will be wind. The cyclone, as stated yesterday, is moving quickly through the region and will weaken overnight as another cyclone near the south coast of France gains most of the upper-level support. This storm's rainfall should be over by daybreak tomorrow. That said, the models are forecasting maximum amounts between 30 and 40 mm near Sevilla by that time. Nothing to sneeze at, given the current hydrologic conditions. Actual maxima, I suspect, will be in the usual area of the Sierra de Alcornocales and Grazalema. This continues the concern for flooding in the Guadalete river basin.
I have the "gut" feeling that the greatest impacts of this storm will be wind. Although the models keep the highest winds to the south and west of Andalucia, just a slight error in cyclone position prediction could bring these winds to the coast and inland. AEMET has issued yellow risk alerts for costeros (wind-driven coastal waves) and maximum gusts of 80 km/hr for today and tomorrow along the Costa de la Luz and the Straits. Perhaps this should be upgraded to orange alert level. The strongest winds should be behind the cyclone as it makes its exit, tomorrow morning. These winds will be westerly and should also buffet the Sierra de Alcornocales.
Sunday's storm continues to look like the big, bad dog. Take a look at these historical charts from the middle of the big flood event around Christmas 2009 - the jet stream at 300 mb and the surface pressure pattern across the North Atlantic. Compare them to the same charts - jet and surface pressure - as forecast by the GFS model for mid-day on Sunday. Do you see some similarities? Of course, much will depend on where the surface low sets up, but models have consistently depicted it with a 976 millibar central pressure and a very intense cold front and pressure gradient ahead of it. This would give the worst of both worlds - heavy rain AND gale-force (if not hurricane-force) winds.
If the above scenario occurs Sunday, only one good thing could be said about being in Andalucia - it won't get the worst of it, Portugal will. Small consolation, however, if the heavy rain aggravates what will no doubt be an antecedent serious hydrologic problem.
Updated: 9:49 AM GMT on February 18, 2010
By: esteban9, 10:02 AM GMT on February 17, 2010
Pics courtesy Sur newspaper in Malaga.
By: esteban9, 9:36 AM GMT on February 17, 2010
Thankfully, there was much less precip along the Costa del Sol yesterday, as showers were much more widespread (maximum 6.9 mm at Sierra de Luna, just west of Algeciras). However, repeated lines of showers crossed to the north of the Guadalquivir river, between Cordoba and Sevilla, the result of which is shown by this map. The maximum in this area was 55 mm, a significant amount considering antecedent and anticipated precipitation. Also, a secondary maximum is evident in the mountains near Ubrique, feeding tributaries of the Guadalete river of Cadiz province.
Early this morning, a small patch of cloud and rain, with some imbedded thunderstorms, passed through the central and eastern sections of Andalucia. As of this writing, the southeast is finally catching up, with rain covering nearly the entire province of Almeria. This won't last long though. Again, no sounding from Gibraltar at 0000 UTC, making vertical stability and moisture assessment more difficult. But from the looks of the Seville radar, there is enough instability today to support at least widespread showers. These should decrease in coverage through the afternoon.
The next "temporal," due to arrive tomorrow morning, is the big concern. As mentioned earlier, this cyclone's track is much further south than its predecessors. It is progged to arrive from the southwest, as it skirts the Moroccan coast and enters the Straits. This means that the system should have a rich moisture supply. Unlike the predecessors, however, there is some divergence of opinion in the models as to where the bulk of associated precipitation will fall - to the north or south of the cyclone center. If north, then Andalucia will again bear the brunt of the storm. If south, Morocco will be lashed. All models agree, however, that this cyclone will transit the area more quickly than the last, which will make for reduced total accumulations. This good news must be tempered by the fact that, as previously blogged, another storm moves in Sunday morning. The models continue to portray this as the most powerful storm of all. But there is considerable disparity in the surface cyclone position at this forecast horizon (4-5 days), we will be on the lookout for changes.
Updated: 9:39 AM GMT on February 17, 2010
By: esteban9, 1:13 PM GMT on February 16, 2010
Here's a story (in Spanish) on the flooding to the north and west of Malaga, including three reservoirs already releasing water from the spillways...
By: esteban9, 10:11 AM GMT on February 16, 2010
It appears that today, while not precipitation-free by any means, will see a decrease in amounts toward afternoon, as showers become more widespread. This trend will be especially pronounced in the western provinces. The eastern Provinces, particularly Malaga, will continue to be a concern with more rain, however, as the "bullseye" of maximum amounts shifts southward to Morocco. Lots of convection/thunderstorms around still, as there was last night in that area. The abbreviated (to 2.7 km only) Gibraltar sounding from 0000 UTC still shows very warm, moist air and strong southwest flow at low levels.
This small piece of good news, alas, will be short lived as I've been saying for several days. In fact, the outlook for tomorrow and Wednesday shows the next storm moving in about 12 hours earlier than anticipated yesterday. This storm continues the trend for a track further and further south than its predecessor.
To heap on more misery, the cold front ahead of another cyclone is progged to slam Iberia on Sunday. The central pressure of this cyclone is forecast by the GFS to have a central pressure of 970 mb at 7 AM Sunday, the deepest and most intense low this year. Once again, the CMC and GFS models are tracking well with each other, with the latter's six-day precip accumulation (ending Monday 1 AM) forecast here. Keep in mind that these amounts are on top of what's already fallen since 1 AM this morning. Note that the maximum isohyets are again in Cadiz and Malaga provinces, but a second bullseye of > 100 mm in west-central Spain. Since there is greater uncertainty in the models for that more distant forecast horizon, this will have to be monitored, since the maxima span the Guadalquivir basin, which is becoming an increasing concern. The current Guadalquivir reservoir status by province shows average fills approaching or above 100% capacity in Huelva, Sevilla, and Ciudad Real provinces.
As an aside, data from the Sevilla radar started to come in shortly after yesterday's first blog...thanks AEMET. Also, I've linked several model forecast charts from Weather Online; many thanks go to them.
By: esteban9, 8:11 AM GMT on February 16, 2010
The SAIH Gualdalquivir precip map may be found here. The HIDROSUR precipitation accumulation map for today (to about 9 A.M.) shows that the western part of Malaga province, centered on the mountains north of Marbella, was hit hard overnight (this is the area that yesterday's weather models were targeting). In reaction, AEMET has posted an orange (important) risk for the Sol and Guadalhorce basins of Malaga province.
Forecast for further precipitation shortly.
By: esteban9, 2:35 PM GMT on February 15, 2010
From stations reported by the Sistema Automático de Información Hidrológica (SAIH) de las Cuencas del Guadalquivir, rain totals since midnight have ranged from 20-25 mm in Sevilla and Cadiz provinces, to generally around 7 mm in the Jaen-Granada area. Along the Costa del Sol, Hidrosur reports several sites with amounts near or exceeding 80 mm in the Sierra de Alcornocales (north of Algeciras), since midnight. See the site key numbers on the map and then match with the site numbers in the dropdown list titled "Estaciones donde se ha registrado lluvia en las últimas 24-48 horas." An isohyetal map, created about 1600 today, is here.
This map, like most of the Spanish usage, uses liters per square meter. This is the same as mm, which I normally cite.
Updated: 3:35 PM GMT on February 15, 2010
By: esteban9, 9:38 AM GMT on February 15, 2010
Looking at the GFS over the entire north Atlantic, one sees progged a 100-160 knot polar jet at 300 mb (30.000 feet) extending from the southeast U.S. all the way across the Atlantic to Northwest Africa, during nearly the entire forecast period (today through next Monday). Although I'm not that experienced with European weather, this seems like an extraordinary pattern and corroborates a very stormy forecast through the week.
I forgot to mention that this is not welcome news for all the carnavales going on in Spain, particularly the big one in Cadiz...hopefully there were a lot of attendees yesterday. Next "break" in the rain MIGHT be Wednesday, but if it materializes at all, it'll be a brief window.
By: esteban9, 8:54 AM GMT on February 15, 2010
As advertised, the precipitation began a little after 10 PM local last night in the western provinces and has continued unabated there through the morning. In the east (Granada), it began around 2 AM. It appears that all provinces of Andalucia have precip at this time, although only Almeria's radar data has been available via the AEMET site (Malaga and Sevilla are missing data).
The infrared (IR) satellite imagery looks impressive, as deep (cold-topped) convective clouds continue to stream from the southwest into the region. The "warm conveyor belt" of continuous precipitation has been replaced by broken but more intense, large convective elements. This is also evident on the Portuguese radars. So today's precipitation will have some breaks, but those periods with thunderstorms and rain will have higher rainfall rates.
The UK Met Office (UKMO) surface analysis and progs show a deep (986 mb) closed surface cyclone whose center remains off the west coast of Iberia until noon tomorrow (when it is in the Lisbon area). This means that, like yesterday's forecast, Andalucia will continue to be in the warm moist airflow, with a succession of warm or stationary/occluded fronts rotating into the area like spokes on a wheel. Therefore there will be no shortage of lifting mechanisms for the abundant moisture. AEMET has upgraded their alerts from yellow to orange ("imporant risk") for Ronda, Sol y Guadalhorce areas in Malaga province. I think Cadiz province should be upgraded in risk as well.
Along with the radar outage, there was no sounding data from Gibraltar at 0000 UTC last night. The old adage amongst those responsible for making forecasts/warnings is that when things go wrong (as they will per "Murphy's Law"), bad things happen (a kind of corollary to Murphy's Law). Hopefully this bit of pessimism won't hold in this case, but again, it's time for heightened awareness. Alas, this is even more the case, as the models are showing another short wave breaking under the upper ridge from next Sunday through Tuesday 21st through 23rd). As I hinted at in yesterday's blog, this may become a long-fused hydrologic event, with major rivers and reservoirs under threat because of repeated (every 1-2 days) shots of rain. As opposed to flash flooding, caused by high rainfall RATES.
Update this evening perhaps.
Updated: 8:55 AM GMT on February 15, 2010
By: esteban9, 11:34 AM GMT on February 14, 2010
The weather models are all coming together in predicting an extended, heavy precipitation event, beginning this evening. An initial dose will last through Tuesday, with another one coming in Thursday. A major low-level closed cyclone will be supported, unlike last week's storms, with a strong upper-level jet streak. The cyclone will be slow moving and Andalucia will be in the warm, moist airstream ahead of the low for a prolonged period. Being a warmer airmass, there will be more moisture available than last week's storms.
To illustrate the initial hydrologic conditions, see this representation of the fill of Andalucian reservoirs, averaged by province (courtesy Agencia Andaluz de Agua). Note that the western provinces have partcicularly high percentages (Porcentage on the map) of capacity (although Jaen province is also extremely high). Of course, this does not reflect the smaller rivers and streams, particularly in mountainous terrain, which respond very quickly to high rainfall rates. Now, look at the following weather model predictions of accumulated precipitation in mm, through Friday morning (0700 local) - the GFS and the CMC. If we assume the rain starts late this evening, the period represents about 4 days of accumulation. Note the highest amounts in both models are in the Marbella/Sierra de Alcornocales areas, with a whopping 173 mm over the Marbella area on the GFS, and 138 mm on the CMC!
Compare these figures for the period of record rains and flooding in Andalucia, 21-26 December 2009. Ronda and Malaga, which both endured flooding, received about 230 mm in 4 days and 80 mm in one day, respectively. So, if the current model precipitation verifies, we could see flooding, perhaps not as severe as in December, but consider this. The December event was near the beginning of this season's rain, when the soil was still relatively dry (some areas in drought). Now, the soil has seen prolonged rainfall and is near saturation.
As I said yesterday, this storm bears close watching. AEMET has hoisted yellow alerts for heavy rain (40 mm in 12 hours) for the western provinces tomorrow and Tuesday. Perhaps if the 2nd storm follows closely on the heels of the first one (Thursday as forecast), the latter half of the week may hold the greater flooding threat.
By: esteban9, 10:19 AM GMT on February 13, 2010
As predicted, the rain yesterday was much more intense than Wednesday's storm. However, unlike I anticipated, there was much more precip in western Andalucia than on the Costa del Sol. The reason why is a bit of a puzzle for me at the moment. Storm total amounts in mm:
Seems like Algeciras/Gibraltar have been hit the hardest overall this winter, and this storm was true to form. It's also confirmed by AEMET's Valores Climatológicos Normales (climatic norms), which has Tarifa topping the list of Andalucian sites at 603 mm annual average precip. If you're wondering how this winter stacks up against climatology, consider that Sevilla's average precip for December-January-February is 214 mm; it's had 499 mm through today (and two more weeks left in February)! The average for the ENTIRE year is 534 mm!
Looking ahead, there's no relief for those weary of clouds and rain. The next system moves in late tomorrow (Sunday evening) and persists through Wednesday. This storm may make this week's two events look like a walk in the park. The models have Andalucia in the warm sector of a well-developed cyclone moving in from the southwest, lingering for at least 48 hours. Beware the possibility of training echoes and flooding, especially given the near-saturated soil from recent rains. This one will have to be watched very closely.
By: esteban9, 9:22 AM GMT on February 12, 2010
The initial setup in the surface pattern is similar to Wednesday's event, with a wave moving in from Portugal at this time. Northwest-southeast bands of precip seen on radar, moving northeast. These bands, along with the IR temps on satellite, are more intense than Wednesday's. This is consonant with greater upper-level support (short wave) for vertical motion this time. This upper wave is progged to become a lobe on the closed low now in the central Med.
So, I expect greater precipitation rates this time, with more organized precip bands. The models all forecast the short wave to sag southward, however, supporting the surface wave/stationary front to set up a little south of the Costa del Sol. The key to forecasting this storm is "how far south will this front set up"? If it remains draped along the coast through tomorrow, there could be a prolonged precip event there. If it moves further south, then the coast will be somewhat spared a long-lasting event. My feeling, based on prior events, is the former. As I stated in one of my earliest blogs, the Straits area seems to promote baroclinicity at low levels and support of these quasi-stationary fronts.
In any event, look for the coast to bear the brunt this time, unlike Wednesday. That said, however, there is much more cold air to the north side of the front and the precip that does fall inland will be snow in some of the higher mountains. Although the GIB sounding showed a 2400 m freezing level, this will lower significantly. AEMET is saying down to 600 m today, which will affect a lot of the higher terrain. Good news for the Sierra Nevada!
Vamos a ver!
By: esteban9, 12:10 PM GMT on February 11, 2010
Some totals from yesterday's storm in mm:
Jaen 8.9 and 6.1 after midnight (today)
So, with the exception of Jaen, the prediction of light-moderate accumulations (< 10 mm) was accurate. There was a dearth of precip on the Costa del Sol, but a lot more inland.
Another upper short wave propagates under eastern Atlantic high-amplitude ridge and gives us a brief shot of rain tomorrow evening. Similar in magnitude to yesterday's amount, at first glance.
Updated: 12:20 PM GMT on February 11, 2010
By: esteban9, 8:17 AM GMT on February 10, 2010
Looks like the models are maintaining good agreement on this "lower tropospheric" storm. The 00 UTC Gibraltar sounding shows moisture to only 800 mb, but 1.5 cm precipitable water. The UKMO surface analyses are indeed showing a wave on the front, with a triple point moving across Andalucia today. Stationary front draped across the province from west to east, indicating that this event will last through the day. Given the lack of upper level forcing (ridging, as mentioned yesterday), it looks like rainfall rates will only be light to moderate. Both the NAE and GFS are showing Andalucia in the left exit region of a healthy (100-120 knots at 300 mb) jet streak, however, so upper forcing won't be non-existent. It'll be interesting to see if any areas get much more than 10 mm accumulation, which is about the maximum the models are forecasting.
PS the NAE is the UK MetOffice, North Atlantic European Model, with higher resolution - 0.18° x 0.28°. Compare with that of the GFS, with next highest resolution 0.5° x 0.5°.
By: esteban9, 9:22 AM GMT on February 09, 2010
The UKMO and NOGAPS have the precipitation continuing through the afternoon, suggestive of a wave developing. The other models (NAE, GFS, CMC) have the rain petering out by 18Z. In my experience for North America, the UKMO and NOGAPS were problematic...so we'll see if this wave happens and redeems these models, at least in this instance!
By: esteban9, 2:46 PM GMT on February 08, 2010
For Wednesday, centered on about 12 UTC - Looked at the Canadian (CMC), GFS ensembles and the others' diagnostic solutions (UKMO, NOGAPS), and they all seem to be in agreement that the upper air (500 mb) pattern shows Andalucia downstream of a short wave ridge. At the surface there's also agreement that the area will have what I describe as a little more than a "weakness" in the surface pressure field, i.e., a little troughing. The interesting part is that this troughing is associated with a fairly pronounced "bullseye" of precipitation (up to 10 mm per 6 hours in Western Andalucia & Portugal).
So it'll be interesting to see if the low levels can generate this much precip w/o much upper dynamics. Perhaps a wave forming, as I mentioned in my last post. We shall see...stay tuned!
By: esteban9, 7:30 AM GMT on February 08, 2010
It's probably also a function of where the upper jet has been traversing, but I've noticed a real tendency for the lingering cold/stationary/warm fronts around the Straits of Gibraltar and Costa del Sol area. Must be a real boost to baroclinity, cold land/warm water. As alluded to in the frontal type progression above, if the boundary hangs in this area long enough, a wave inevitably forms on it and gives the coast a 2nd bath (after the cold frontal passage). Most interesting, but I guess not surprising. Some very unique geography there.
By: esteban9, 12:58 PM GMT on February 07, 2010
Just a note on my habitual forecast technique.
In winter, I normally use the forecast funnel, going from very large (global) to large (synoptic) to mesoscale processes in my the sequence of "data I look at." This is a good systematic way to proceed. Also, I look at observations before model data. Particularly for Spain, this means the satellite pictures. There aren't a lot of data over the oceans, although satellite retrieval techniques are getting better. Therefore one is apt to be led astray by models that are not initialized well for the lack of data.
Just an aside - I notice that the GFS model has been about 6-12 hours too fast in bringing in short waves in the southern branch of the jet stream, which has brought us so much rain this year. I don't know if this is a typical bias in this region or not, as I haven't been looking at it for long enough.
By: esteban9, 9:49 AM GMT on February 07, 2010
Welcome to the inaugural entry of my weather blog, focused on the weather and climate of Andalucía!
As a caveat, I must say that I have been in Spain only since Fall 2008 and so, with only a year and a half experience here, I'm a student of the country's weather. As any forecaster will tell you, one must really spend some time looking at day-to-day weather patterns to get a sufficient feel to even attempt an accurate forecast. Meteorology is very much a geo-science - one must not only be familiar with the climate but also the underlying terrain and how it affects the atmosphere, even at the smallest scales. So, to become "intimate" with the weather at a particular spot (let alone region), one must watch the weather closely and look for patterns that are heavily influenced by topography (for example, mountain-valley circulations, land-water interactions, etc.)
Nonetheless, as a professional meteorologist of 30 years, I can say this with certainty. Spain is the 2nd most mountainous country in Europe (after Switzerland) AND it is a peninsula, surrounded by the sea. These two factors alone will make for some fascinating weather! Of course, as a whole across Spain, most of this "interesting" weather occurs in the cool season (October through May), when the jet stream sags southward to our latitudes, pushing the Azores anticyclone (high pressure) southward, away from the Iberian peninsula. If I had to compare to the climate of any place I've lived (and I've lived in quite a few), I'd say coastal California. However, the ocean offshore of California is dominated by a cold current, and this is definitely not the case in Andalucía! The warmer water means more evaporation and moisture available for storms - all one needs is a little trigger (for rising motion) and atmospheric instability and BOOM!
I can attest to the "interesting" nature of the weather here, based only on my short duration of residence! Snow in Sevilla, hurricane-force winds in the coastal mountains, a tornado ripping through the bus station in Málaga, torrential rains and flooding all across the province; I could go on if memory served me better at the moment. I have to say the most surprising aspect for me has been the torrential rains. Back in Tennessee, where I worked for the U.S. National Weather Service, we called such rains "toad stranglers."
Well, I look forward to posting my musings here in the future, and hopefully I'll catch the eye of some "compañeros del tiempo," enough perhaps to elicit some comments. Oh, and "weather geeks" always welcome here!
The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.