Disturbance 99L more organized; record melting in Austrian Alps

By: Dr. Jeff Masters , 2:02 PM GMT on August 01, 2012

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A tropical wave (Invest 99L) near 11°N 47°W, about 1000 miles east of the Lesser Antilles Islands, is showing increasing organization, and has the potential to develop into a tropical depression today or tomorrow as it moves westward at 15 - 20 mph. Visible satellite loops show that the disturbance now has two respectable low-level spiral bands, one to the north and one to the south, and a moderate amount of heavy thunderstorms near the center. The thunderstorm activity has not changed much in intensity this morning. A well-defined surface circulation is not evident on satellite images, but last night's 8:30 pm EDT pass from the ASCAT satellite showed a broad, elongated center with light winds had formed. Water vapor satellite loops show that 99L has a reasonably moist environment, and the latest Saharan air layer analysis shows that the dry air from the Sahara is not present in large quantities over the central tropical Atlantic. WInd shear over the disturbance has increased some since Tuesday, and is now at the moderate level, 10 - 15 knots. Ocean temperatures are 28°C, (82°F) which is about 0.5°C above average for this time of year.


Figure 1. Morning satellite image of Invest 99L.


Figure 2. Vertical instability over the tropical Atlantic in 2012 (blue line) compared to average (black line.) The instability is plotted in °C, as a difference in temperature from near the surface to the upper atmosphere. Thunderstorms grow much more readily when vertical instability is high. Instability has been lower than average, due to an unusual amount of dry, sinking air in the atmosphere, reducing the potential for tropical storm formation. Image credit: NOAA/NESDIS/CIRA.

Forecast for 99L
Wind shear is expected to remain light to moderate, 5 - 15 knots, through Friday, ocean temperatures will remain near 28°C, and mid-level moisture will be a moderate 60 - 70%, according to the 8 am EDT run of the SHIPS model. The disturbance has gained a bit of latitude and is now at 11°N, which will help it leverage the Earth's spin more to acquire its own spin. These conditions are probably sufficient for 99L to become Tropical Depression Five, with Thursday being the most likely day for this to happen. However, the reliable computer models are not very eager to develop 99L, and none show it becoming a hurricane over the next five days. This is probably because the atmosphere over the tropical Atlantic is unusually stable for this time of year (Figure 2), with large-scale areas of dry, sinking air present. Climatologically, we see very few Cape Verdes-type hurricanes forming near the Lesser Antilles Islands this early in August, and I expect 99L will struggle at times over the next few days. This is particularly likely if 99L goes north of 13°N, where a band a high wind shear of 20 - 40 knots associated with the subtropical jet stream lies. At 8 am Wednesday, NHC gave 99L a 60% chance of developing into a tropical depression by Friday morning. Residents and visitors to the Lesser Antilles Islands should anticipate heavy rains and strong winds from 99L beginning to affect the islands as early as Friday morning. The long-range fate of 99L next week is uncertain, but a track west to west-northwest through the Caribbean is the most popular solution from the models.


Figure 3. Typhoon Saola (bottom) and Typhoon Damrey (top) perform a pincer maneuver on Shanghai, China in this MODIS photo from NASA's Terra satellite taken at 02 UTC August 1, 2012. Image credit: NASA.

Two typhoons headed towards China
In the Western Pacific, typhoon season is in full swing with two typhoons headed towards China. The more dangerous of the two is Category 2 Typhoon Saola, which is predicted to skirt the northern coast of Taiwan and hit mainland China 300 miles south of Shanghai on Friday as a Category 3 typhoon. Typhoon Damrey, a Category 1 storm located just south of Japan, is expected to hit China about 150 miles north of Shanghai on Thursday at Category 1 strength.

Extreme heat in Oklahoma
The withering heat in America's heartland continued on Tuesday, with the prize for most ridiculous heat a 113° temperature recorded in Chandler, Oklahoma. A close second: Tulsa hit 112°, just 3° below the city's all-time high of 115° set on August 10, 1936. The low temperature in Tulsa was 88° Tuesday morning, tying the record for warmest low temperature in city history set just the previous day. Six locations in Oklahoma hit 112° or hotter Tuesday, and the forecast calls for highs near 112° again today over portions of Oklahoma.

Extreme dryness in the Central U.S.
A few final tallies for July precipitation are in, and several U.S. cities in the heart of the drought region set new records for driest July:

Joplin, MO: 0.00" (ties record set in 1946)
Springfield, MO: 0.32" (previous record 0.33" in 1953)
Sioux Falls, SD: 0.24" (previous record, 0.24" in 1947, normal is 3.09")

Record early snow melt in the Austrian Alps
One of the longest meteorological data records at high altitude comes from Sonnblick, Austria, on a mountaintop in the Alps with an elevation of 3106 meters (10,200 feet.) The observatory typically sees maximum snow depths of 3 - 4 meters (10 - 13 feet) during winter. According to weather records researcher Maximiliano Herrera, the snow had never completely melted at Sonnblick until the summer of 1992. Complete snow melt did not happen again until August 12, 2003, and has happened an average of once every two years since then--but always in September. Yesterday, on July 31, the snow completely melted at Sonnblick, the earliest melting since record keeping began in 1886. It's been an exceptionally hot summer in Austria, which experienced its 6th warmest June since record keeping began in 1767. Sonnblick Observatory recorded its all-time warmest temperature of 15.3°C (60°F) on June 30. Vienna hit 37.7°C (100°F) that day--the hottest temperature ever measured in June in Austria. Note that the two mountains in the Alps with long climate records, Saentis in Switzerland and Zugspitze in Germany, beat their records for earliest melting last year in 2011 (Saentis beat the previous record of 2003, and Zugspitze tied the record set in 2003.)


Figure 4. The Sonnblick Observatory in Austria on April 26, 2010. Image credit: Michael Staudinger.

Jeff Masters

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Quoting kmanislander:


Lots of time to worry about the track. The real problem though is that if it gets to the central Caribbean the only way out from there will likely bring a lot of damage for somewhere given the very high TCHP. Worst case it passes South of us and goes through that area off to the WNW and NW between us and the Yucatan. CAT 5 territory there if the upper levels are good.

If this makes it to the West Caribbean like forecast, I don't see anything less than a Category 2 out of it.
Member Since: July 6, 2010 Posts: 112 Comments: 31314
1385. Patrap
Bain and Blackstone group, this next line is for you.

With the Heart of Cane season coming, feel free to Bump up portlight.org coffers as we could use the infusion after the Spring Henrysville and Harrisburg Nadoes.

I mean, you know, you can write it off as were a 501C3 org.

Have a Nice cocktail Hour.

Pfffth
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Quoting CosmicEvents:
That's one very skinny cone 4-5 days out. The NHC is pretty certain on track here...the uncertainty is intensity, as always.


If he stays above 15mph, it's gonna be a narrow cone unless a center refix jumps around when developing
Member Since: July 14, 2008 Posts: 1 Comments: 9628
1383. EricSFL
Quoting ncstorm:
My local Meterologist said we still need to watch the wave over PR as well..

As JB would say..never say never..

Joe Bastardi or Justin Beiber?
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Quoting StormTracker2K:
Time to pop open a cold BEER and get ready for the Olympics tonight. I hear the US had another good day.
Already got my drink of choice and relaxed in my chair
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Quoting weathermanwannabe:
1316. TomTaylor 5:09 PM EDT on August 01, 2012

Good anylysis on the ULL to the North as noted in the NHC discussion; the separation between it and pre-Ernesto may not be as much of an issue once the storm gets into the Western Caribbean hence the intensity increase at that point with the current official forecast.
Yeah I didn't really bother going into detail about the conditions over the central to western Caribbean because the models diverge significantly. The ECMWF has the ULL follow the storm further west, inflicting considerable shear until it passes Haiti, whereas the GFS keeps the ULL further east and less amplified into the deep tropics. The difference between the two models probably largely explains why we see such drastic differences in intensity. It's amazing to see such a big disagreement between the models over just such a short period of time. This shows how poorly our models handle the upper level environment and why our intensity forecasts are often so poor.
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1380. Patrap
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1379. Patrap
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That's one very skinny cone 4-5 days out. The NHC is pretty certain on track here...the uncertainty is intensity, as always.
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Quoting pottery:
Good afternoon all.
So Storm05 now, August 1st.
Pretty good going so far in 2012.

I am a little surprised to see the northward shift from West so early to be honest.
Who is the Crow Supplier here, anyhow? I need to talk to him/her.

Good to see that no real wind-development as it crosses the Islands. TropStorm winds can be bad enough in Islands that grow bananas, higher than that is real bad stuff.
Hoping the rains are not too heavy on the steep hillsides.......


Pottery & Kman~ How you all doing? So I know it's early but what's your opinion of the tropical wave? Is the winds in the Caribbean to high for it to make it?

sheri
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1376. nigel20
Good evening everyone...i see that we now have TD5. I'm not liking this track at all...it may/should change.
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Quoting Bluestorm5:
Anyone remembers Tropical Depression Six's forecast in 2007? Well, that became 175 mph Category 5 Hurricane Felix a few days later... All I'm saying is alot can changes in the next few days, so just relax and enjoy the ride.


Look at what that storm became:
Member Since: March 16, 2012 Posts: 127 Comments: 7927
Quoting ackee:
I think the GFS soultion is similar to the NHC track the Ecmwf weakens it to an open wave


Ah ok. I can never tell the intensities on those models. :)
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Quoting kmanislander:


I Posted this much earlier today and the steering still holds. The weakness which is easily seen in the ridge has allowed the system to lift and track more to the WNW. I expect the track to flatten out much later tonight as the easterly flow strengthens to the West of the weakness.



Nice graphic. Does everyone see the weakness by the yucatan? Yeah, bar any major changes, he's gonna thread the needle into the Gulf.

As I stated earlier...the track will not be a problem. Intensity forecast will be a challenge.
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Quoting TropicalAnalystwx13:

With higher-than-average forecast confidence on the track they do.

"THE COMPUTER MODELS ARE IN
GOOD AGREEMENT...AND THE NHC TRACK FORECAST IS NOT FAR FROM THE
MODEL CONSENSUS."


Lots of time to worry about the track. The real problem though is that if it gets to the central Caribbean the only way out from there will likely bring a lot of damage for somewhere given the very high TCHP. Worst case it passes South of us and goes through that area off to the WNW and NW between us and the Yucatan. CAT 5 territory there if the upper levels are good.
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1371. pottery
Quoting kmanislander:


I Posted this much earlier today and the steering still holds. The weakness which is easily seen in the ridge has allowed the system to lift and track more to the WNW. I expect the track to flatten out much later tonight as the easterly flow strengthens to the West of the weakness.


Thanks. I was looking at that earlier as well.
Thats why I was a little surprised to see the north-of-west continuing on the Model Track.
Still early days for this one, and the intensity modelling statement sounds vague....
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My forecast graphic for TD5, NOT OFFICIAL
Member Since: March 16, 2012 Posts: 127 Comments: 7927
1369. ncstorm
Quoting stormchaser19:

the NHC got in trouble before going with the consensus of the models..we shall see
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What worries me about this is,it could peek in the central gulf...That will be bad news along the gulf coast...
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Top analog for the 8 day forecast 500mb pattern is August 26th, 2009.



However, another top analog is from August 14th, 1951. This is the best tropical cyclone analog I could find for this pattern and match it with near the location of TD5. This is Major Hurricane Charlie and you can see it has a very similar path to the 12z GFS for TD5.

Member Since: July 15, 2006 Posts: 17 Comments: 10159
The GFS folks were probably high-fiving after Debby; if this forecast pans out, and the model continues to do well, Champagne might be next and some additional grant monies and appropriations in the future for the lab.............Not trying to diminish the possible consequences if they are right with this one as well.
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Quoting kmanislander:


Afternoon to you as well my friend. Yes, I am updating my check list as we type. Long range track forecasts rarely pan out as initially expected though so I am not jumping the gun on anything here for a few days.

With higher-than-average forecast confidence on the track they do.

"THE COMPUTER MODELS ARE IN
GOOD AGREEMENT...AND THE NHC TRACK FORECAST IS NOT FAR FROM THE
MODEL CONSENSUS."
Member Since: July 6, 2010 Posts: 112 Comments: 31314
1364. ackee
Quoting AtHomeInTX:


They looked pretty similar to me except at the end?
I think the GFS soultion is similar to the NHC track the Ecmwf weakens it to an open wave
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Anyone remembers Tropical Depression Six's forecast in 2007? Well, that became 175 mph Category 5 Hurricane Felix a few days later... All I'm saying is alot can changes in the next few days, so just relax and enjoy the ride.

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Quoting pottery:
Good afternoon all.
So Storm05 now, August 1st.
Pretty good going so far in 2012.

I am a little surprised to see the northward shift from West so early to be honest.
Who is the Crow Supplier here, anyhow? I need to talk to him/her.

Good to see that no real wind-development as it crosses the Islands. TropStorm winds can be bad enough in Islands that grow bananas, higher than that is real bad stuff.
Hoping the rains are not too heavy on the steep hillsides.......


I Posted this much earlier today and the steering still holds. The weakness which is easily seen in the ridge has allowed the system to lift and track more to the WNW. I expect the track to flatten out much later tonight as the easterly flow strengthens to the West of the weakness.

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1361. ncstorm
My local Meterologist said we still need to watch the wave over PR as well..

As JB would say..never say never..
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Quoting RussianWinter:


A three isn't out of option yet.


My guess would be it will peak out at Cat 2. But I think the track will be easier to figure out with this one...the intensity forecast will be the problem.
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Quoting VAbeachhurricanes:


shocker


He's that guy.
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1358. Patrap
Quoting kmanislander:


Afternoon to you as well my friend. Yes, I am updating my check list as we type. Long range track forecasts rarely pan out as initially expected though so I am not jumping the gun on anything here for a few days.


Indeed K, best to be in the Bulls eye 3-4 days out,than 1 fo sho'
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Quoting wunderkidcayman:
I theing the only thing the cone id going to do is to move further and further west


shocker
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Quoting wunderkidcayman:
GFS


Hey, we've been talkin about ya, don't soil your pants just yet. A category one hurricane is livable.
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I theing the only thing the cone id going to do is to move further and further west
Member Since: June 13, 2009 Posts: 2 Comments: 10852
1354. ackee
I am the huge fan of THE Ecmwf ,however this seasons it just seem like The Gfs is leading the other models by far Debby was good example of this and if the GFS forcast pan out for pre EARNESTO it would be another conformation as to which model is on top this seasons
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Quoting wunderkidcayman:
GFS
Agree.
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AFTER DEBBY, I CHOOSE THE GFS!
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Time to pop open a cold BEER and get ready for the Olympics tonight. I hear the US had another good day.
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1350. pottery
Good afternoon all.
So Storm05 now, August 1st.
Pretty good going so far in 2012.

I am a little surprised to see the northward shift from West so early to be honest.
Who is the Crow Supplier here, anyhow? I need to talk to him/her.

Good to see that no real wind-development as it crosses the Islands. TropStorm winds can be bad enough in Islands that grow bananas, higher than that is real bad stuff.
Hoping the rains are not too heavy on the steep hillsides.......
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Quoting Patrap:


Check the Vintages, and the Ice, you know da drill well Kman.

Afternoon.


Afternoon to you as well my friend. Yes, I am updating my check list as we type. Long range track forecasts rarely pan out as initially expected though so I am not jumping the gun on anything here for a few days.
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Quoting tennisgirl08:
Wow. TD 5. It is still a little early in August to have a major cat 4-5 hurricane... there is some dry air to deal with in the Caribbean and not enough instability. The track is most concerning at this point.


A three isn't out of option yet.
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Quoting Patrap:
Were only a few days away from the Mars entry or the 7 minutes of Terror.

Should be a Wild Ride down for the Spacecraft


Hope it goes well,very intricate moves required.
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Quoting RitaEvac:


That aint good


No, not good at all.
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GFS
Member Since: June 13, 2009 Posts: 2 Comments: 10852
1344. 7544
watch the cone keep shifting north still have plenty of time for the us to watch this one but its going to be very tricky one on where it ends up imo its goin to change several more times
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Quoting stormchaser19:
000
WTNT45 KNHC 012044
TCDAT5

TROPICAL DEPRESSION FIVE DISCUSSION NUMBER 1
NWS NATIONAL HURRICANE CENTER MIAMI FL AL052012
500 PM AST WED AUG 01 2012

DURING THE DAY...VISIBLE SATELLITE IMAGES SHOWED THAT THE LOW-LEVEL
CIRCULATION OF THE LOW PRESSURE SYSTEM TO THE EAST OF
THE WINDWARD ISLANDS HAS BECOME BETTER DEFINED. DEEP CONVECTION
HAS PULSED A BIT...AND IS SOMEWHAT LACKING OVER THE NORTHERN PART
OF THE CIRCULATION. HOWEVER THE SYSTEM HAS NOW ACQUIRED SUFFICIENT
ORGANIZATION TO BE CLASSIFIED AS A TROPICAL DEPRESSION. THE
INITIAL WIND SPEED IS SET AT 30 KT IN ACCORDANCE WITH DVORAK
ESTIMATES FROM TAFB AND SAB. FORECASTING INTENSITY CHANGE IS
ALWAYS A CHALLENGE...AND IS PARTICULARLY TRUE IN THIS CASE.
MODERATE VERTICAL SHEAR...ASSOCIATED WITH A LARGE UPPER-LEVEL LOW
TO THE NORTH OF THE DEPRESSION...IS LIKELY TO AFFECT THE SYSTEM FOR

THE NEXT COUPLE OF DAYS. THUS ONLY SLOW STRENGTHENING IS
ANTICIPATED DURING THE FIRST HALF OF THE FORECAST PERIOD. LATER
ON...THE INTENSITY FORECAST UNCERTAINTY INCREASES. OUR BEST TWO
GLOBAL MODELS ARE AT ODDS AS TO HOW THE SYSTEM WILL EVOLVE AS IT

MOVES OVER THE CARIBBEAN. THE GFS FORECASTS THE UPPER-LEVEL
ENVIRONMENT TO BECOME QUITE CONDUCIVE FOR STRENGTHENING BY THE END
OF THE FORECAST PERIOD...WHEREAS THE ECMWF MODEL SHOWS THE SYSTEM
DEGENERATING INTO A TROPICAL WAVE. THE OFFICIAL FORECAST LEANS
TOWARD TO THE GFS...BUT TIME WILL TELL.


THE INITIAL MOTION IS A SOMEWHAT UNCERTAIN 285/16. GLOBAL MODELS
DEPICT A STRONG MID-TROPOSPHERIC ANTICYCLONE TO THE NORTH OF THE
TROPICAL CYCLONE FOR THE NEXT SEVERAL DAYS. THIS STEERING PATTERN
SHOULD CAUSE A WEST-NORTHWESTWARD TO WESTWARD MOTION AT ABOUT THE
SAME SPEED THROUGH MUCH OF THE FORECAST PERIOD. A WEAKNESS OVER
THE GULF OF MEXICO COULD CAUSE SOME SLOWING AND BIT OF A
NORTHWESTWARD TURN LATE IN THE PERIOD. THE COMPUTER MODELS ARE IN
GOOD AGREEMENT...AND THE NHC TRACK FORECAST IS NOT FAR FROM THE
MODEL CONSENSUS.



FORECAST POSITIONS AND MAX WINDS

INIT 01/2100Z 12.2N 49.0W 30 KT 35 MPH
12H 02/0600Z 12.7N 51.3W 40 KT 45 MPH
24H 02/1800Z 13.3N 54.5W 45 KT 50 MPH
36H 03/0600Z 13.8N 57.7W 50 KT 60 MPH
48H 03/1800Z 14.4N 60.9W 55 KT 65 MPH
72H 04/1800Z 15.5N 67.0W 55 KT 65 MPH
96H 05/1800Z 16.5N 73.0W 60 KT 70 MPH
120H 06/1800Z 17.5N 78.0W 65 KT 75 MPH

$$
FORECASTER PASCH/BLAKE

This is a special System, even the noaa has lot uncertain in the intensity.......with this system everything can happen
Again euro vrs GFS who will win?I think the gfs.
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Quoting RitaEvac:


That aint good


Eh, some parts could use the rain. The only thing that wouldn't be good is if Ern became a MASSIVE storm, but I don't see that happening right now since it's a bit on the slim side.
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1341. Patrap
05L Long Floater - Water Vapor Imagery Loop
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Wow. TD 5. It is still a little early in August to have a major cat 4-5 hurricane... there is some dry air to deal with in the Caribbean and not enough instability. The track is most concerning at this point.
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WE GOT THE FORECAST TRACK DOWN I THINK
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Quoting RitaEvac:


That aint good


No sir, that ain't good at all.
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Quoting Patrap:
What a big thunderstorm but it will likely not be anything.
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1316. TomTaylor 5:09 PM EDT on August 01, 2012

Good anylysis on the ULL to the North as noted in the NHC discussion; the separation between it and pre-Ernesto may not be as much of an issue once the storm gets into the Western Caribbean hence the intensity increase at that point with the current official forecast.
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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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