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The Rains of May and the Science of Recurrence Intervals

By: Bob Henson 3:54 PM GMT on May 30, 2015



As this memorable month sloshes toward its final weekend, rainfall records have continued to accumulate across the Southern Plains. May is already the wettest month on record in the statewide averages for both Oklahoma (14.43” as of 9:30 am CDT May 30, crushing the 10.75” from October 1941) and Texas (7.54” as of May 27, beating out the ominous 6.66” from June 2004). This is a startling feat when you consider that the two states’ combined area is almost the size of Egypt. Several individual locations have also scored their wettest months on record, including Wichita Falls, TX; Oklahoma City, OK; and Colorado Springs, CO (more on these and other local records next week). The onslaught of wetness is now winding down just as May comes to a close. On the plus side, Oklahoma state climatologist Gary McManus has dubbed this wet period “the death of the Southern Plains drought,” one that had dug its claws into the region for most of the 2010s. However, the associated flooding has killed at least 25 people, with 14 missing, and damaged or destroyed many hundreds of structures.
 

Figure 1. Motorists are stranded along I-45 in north Houston on Tuesday, May 26, after overnight storms flooded the area. Image credit: Cody Duty/Houston Chronicle via AP.
 
 
When an event like this happens, it’s human nature to wonder just how unusual it is. Climate change has added urgency to such questions, but even in a constant (“stationary”) climate, precise answers on the rarity of heavy rain at a given location can be hard to come by. One of the most common strategies is to calculate the “average recurrence interval” (ARI), or the typical amount of time that would separate events of a certain magnitude when considered over a much longer time period. At heart, this is simply a different name for what was long called the return period—i.e., a “100-year flood.” The problem with the “XXX-year flood” wording is that it’s wide-open to misinterpretation. People may think that a 100-year flood won’t be followed by a similarly sized event until a century has passed, when in fact it could recur any time. (You might also describe this as a “1% probability flood,” meaning there’s a 1% chance of getting it in a given year.)



NOAA has decades of return-period estimates under its belt. From the 1950s into the 2000s, these were published as hard-copy maps (see PDFs). More recently, NOAA has undertaken a comprehensive effort called Atlas 14 that is updating the return periods (now called ARIs) and putting them into a fully digital, gridded, GIS-compatible dataset. Since we’re now well into the 21st century, the project has more than a hundred years of rain-gauge measurements to draw on, from thousands of U.S. sites. The Atlas 14 results for Texas won’t be ready until at least 2018, but the Oklahoma numbers are already online, and they provide an useful window on the rarity of the rains that befell the Sooner State this month.






Figure 2. 30-day rainfall totals for Oklahoma, valid from 10:00 am CDT April 30 through May 30. Most of the heavy rain occurred from May 5 onward. Image credit: Oklahoma Mesonet.
 
 
Take long-suffering Norman, OK, which has racked up one of the state’s highest totals for the past 30 days: 23.39” as of 10:00 am CDT Saturday, May 30. (Even higher totals can be found in southeast Oklahoma, but that region also gets more rain in a typical year, so its ARIs for this event aren’t as impressive.) For a 30-day period in Norman, the best estimate of ARIs from Atlas 14 is 500 years for a rainfall of 22.4,” and 1000 years for 24.0.” When a 90% confidence interval is employed, the 500-year range is 16.3” to 29.2”, and the 1000-year range is 16.9” to 32.0”. No matter how you slice it, this goes well beyond a once-in-a-lifetime event for Normanites when considered for the month as a whole. The 24-hour numbers for Norman are less spectacular: the biggest daily rain of the month so far, 4.67” on May 19, falls very near the 5-year ARI value of 4.66”. So it’s the full month of rain that’s much more noteworthy.
 
 

Figure 3. Maximum 24-hour rainfall totals for the Houston area during the period from 1200 GMT June 5 to 11, 2001 (top), as Tropical Storm/Depression Allison dawdled over eastern Texas, and preliminary 24-hour totals from 1200 GMT May 25 to 26, 2015 (bottom), the day that brought massive flooding to western parts of the Houston metro area. The two maps are at the same scale. The analyses are based on data from more than 450 raingauges. Image credit: Applied Weather Associates and MetStat.
 




Even though Atlas 14 data aren’t yet available for Texas, we can gain some ARI-based insight on this storm thanks to the work of Tye Parzybok. His company, MetStat, has calculated new ARIs for 6- and 24-hour rainfall under a subcontract with Applied Weather Associates for the Texas Water Development Board. MetStat produces near-real-time rainfall estimates and predictions and ARI maps for clients and the public, drawing on radar data as well as more than 20,000 North American rain guages, including many compiled through the Citizen Weather Observer Program. (See the MetStat Extreme Precipitation Blog  for writeups on recent events.)
 
Examining the rainfall in and around Houston on Monday, May 25, MetStat found 24-hour ARIs of close to 1000 years for parts of the southwest Houston area (see Figure 4 below), where the gridded analysis indicates a 24-hour maximum of 13.48”. The water then flowed downstream to produce major flooding in central Houston, where the actual rainfall was much less. During Tropical Storm Allison in June 2001, extremely heavy rains covered a much larger part of southeast Texas, with several days of downpours encompassing some truly extreme totals (see Figure 3 above). One rain gauge at Greens Bayou and Mount Houston Parkway measured a 6-hour total of 20.64” during Allison, and the MetStat gridded analysis suggests a nearby maximum as high as 20.98”.




Figure 4. A preliminary map of average recurrence intervals (ARIs) for the 24-hour rains observed in and around Houston from 7:00 am CDT May 25 to 7:00 am May 26, 2015. The map was produced using 820 rain-gauge reports and the MetStorm analysis system. The highest ARI at a given point was 932 years. Image credit: MetStat, Weather Decision Technologies, and Synoptic.




It’s the weeks-long persistence that seems to be most unusual about this month’s rain in both Texas and Oklahoma. There’s an obvious parallel with this past February, which was marked by an unprecedented month-long barrage of cold and snow in much of New England and record winter warmth in and near California. These events raise questions (beyond the scope of this blog post!) about why the steering flow across North America this year has been so prone to multiweek blocking episodes. 



And now, the caveats


ARIs play a huge role in public policy. As Parzybok notes in an EarthZine article, urban water systems are widely designed for ARI rainfalls of 1 to 10 years, while highways are generally built to reflect 10- to 25-year ARIs. While policymakers and the public need and want some kind of yardstick for extreme rain events—and ARIs are the best one we have—they’re also an imperfect tool and shouldn’t be taken as gospel. Some reasons:



It’s not surprising to have rare events over small areas. Very localized extremes may have very long recurrence intervals at a specific point. If you live in Oklahoma, the ARI for a major tornado at your house might be hundreds of years, yet dozens of twisters occur across the state in a typical spring.

Rainfall can’t be measured everywhere at once.  Outside of urban areas, century-long observation points may be separated by tens of miles, which means some huge but localized downpours may be omitted from the long-term record.



Rare events are hard to contextualize, precisely because they’re so rare.  Scientists can use certain statistical techniques to calculate ARIs of up to 200 years from a regional cluster of century-long raingauge records. Beyond that threshold, there’s a lot more uncertainty in the ARIs, as illustrated by the example above from Norman.

Our climate isn’t stationary.  Climate science tells us that a warming planet will intensify rains as well as drought impacts, due largely to the increased evaporation of water from both oceans and land. More than 15 years of observational study backs this up, showing that the heaviest precipitation events are indeed becoming more intense in many parts of the world.
 
A new analysis released on Wednesday by Climate Central highlights the increasing risk of one-day downpours, defined as the wettest 1% of all wet days at a given spot for the period 1950 through 2014. Since precipitation is so variable in time and space, the state-by-state analysis is a patchwork. Most states show increases (as high as 104% in Rhode Island), while six states show minor declines (the largest being -6% in California). Overall, if we assume that downpours at various time scales are becoming more common in most parts of the nation, then it would follow that ARIs from Atlas 14 will tend to be on the high side—i.e., in many locations, we would expect an event diagnosed with a 100-year ARI to occur a bit more often as climate change proceeds.
 
The interactive below shows how the frequency of heavy downpours is evolving over time across the nation. For more background, see the accompanying research report from Climate Central (the interactive is also available at that report site].
 
Bob Henson
 

 

Figure 5. Heavy rains soaked parts of the drought-stricken Northeast on Thursday, May 28, including Portland, Maine. Image credit: wunderphotographer Alphaholik.

Flood Extreme Weather

The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

Reader Comments

18Z shows same thing system forms in about 3 days time
moves NE crosses Cuba then Bahamas and out into Atlantic
no changes in timing intensity or track

I can say this GFS being very consistent
as well as the other models that have been showing this for a while now

anyway
lets wait till the low forms and we can go from there
Quoting 490. pablosyn:

What the Hell?



With the track lines on:

Quoting 500. Ameister12:

Andres looks like it might be making a quick run for cat. 4.

I think your right.
Quoting 500. Ameister12:

Andres looks like it might be making a quick run for cat. 4.


lol wow
I think it could go another 5mph then weaken from there
2E may just follow Andres in intensity

000
WTPZ42 KNHC 312209
TCDEP2

TROPICAL DEPRESSION TWO-E SPECIAL DISCUSSION NUMBER 1
NWS NATIONAL HURRICANE CENTER MIAMI FL EP022015
530 PM CDT SUN MAY 31 2015

Visible satellite images this afternoon indicate that deep
convection has developed over the center of the well-defined low
pressure system to the south of Zihuatanejo, Mexico. Therefore the
system qualifies as a tropical cyclone, and advisories are being
initiated at this time.

The initial motion estimate is 300/05. The depression is located
in a region of weak steering but with enough ridging in the short
term for the cyclone to drift generally west-northwestward to
northwestward through Monday. In 36-48 hours, a mid-level
ridge located west of the cyclone could impart an unusual southward
motion for a day or so. After that time, global models show
stronger ridging developing over northern Mexico and the
south-central United States, which should result in a faster
west-northwestward or northwestward motion. The official NHC track
forecast is close to the multi-model consensus (TVCE) throughout the
forecast period.

Strong northwesterly vertical wind shear associated with the
outflow of Hurricane Andres should preclude significant
intensification during the next day or two. After that time, the
shear is expected to become northeasterly and decrease
substantially, while the cyclone moves slowly in a moist
environment and over very warm waters of around 30 deg C. These
factors should lead to a faster rate intensification, perhaps
greater than what is currently forecast. The NHC intensity
forecast is closest to the SHIPS and HWRF models, which show the
most strengthening of the intensity guidance.

FORECAST POSITIONS AND MAX WINDS

INIT 31/2230Z 12.4N 103.0W 30 KT 35 MPH
12H 01/0600Z 13.1N 103.8W 30 KT 35 MPH
24H 01/1800Z 13.7N 104.5W 30 KT 35 MPH
36H 02/0600Z 13.8N 104.8W 35 KT 40 MPH
48H 02/1800Z 13.3N 104.8W 45 KT 50 MPH
72H 03/1800Z 12.3N 104.4W 60 KT 70 MPH
96H 04/1800Z 12.7N 105.1W 75 KT 85 MPH
120H 05/1800Z 15.0N 107.4W 90 KT 105 MPH

$$
Forecaster Kimberlain/Pasch
5/4/1
One of these days mankind is going to figure out that everything is corelated, that things like the 4 mile deep earthquake and the massive El Reno tornado and the pollutants that are released into the atmosphere have a much more profound effect on our everyday existence in this atmosphere and this space in time than ever imagined.
Why does mankind assume that we would have to immediately take the offensive with alien beings? They could care less. They have learned how to erase hate.
CMC would be quite interesting.
Quoting 505. ncstorm:






Quoting 498. K8eCane:

Tomorrow I have to make sure I have a xanax refill
Sometimes makes it hard to follow the blog thoughts tho
Xanax Sounds scary.....doesnt sound fit for consumption....good name for plastic explosive maybe...:)
Will El Nino Break the California Drought? The Odds Are Not Good
31 May 201, posted by Dan Satterfield

Good night with this, folks ....

(Edit: Sorry for the glitch in the link; I've fixed it now)
Quoting 510. hydrus:

Xanax Sounds scary.....doesnt sound fit for consumption....good name for plastic explosive maybe...:)



Its in the valium family. I have anxiety disorder and one of the things that trigger it is an approaching storm
Quoting 439. hydrus:

models are about worthless where formation is concerned. They do a good job once there is an actual low center.


True fifteen years ago but the NWP community has made a lot of progress with correctly simulating genesis.
Quoting 511. barbamz:

Will El Nino Break the California Drought? The Odds Are Not Good
31 May 201, posted by Dan Satterfield

Good night with this, folks ....
Year 201.......... How did you get this. I never even knew records existed back then. You learn something new everyday :)
Quoting 513. georgevandenberghe:



True fifteen years ago but the NWP community has made a lot of progress with correctly simulating genesis.


yes quite true
Quoting 508. K8eCane:
One of these days mankind is going to figure out that everything is corelated, that things like the 4 mile deep earthquake and the massive El Reno tornado and the pollutants that are released into the atmosphere have a much more profound effect on our everyday existence in this atmosphere and this space in time than ever imagined.
Why does mankind assume that we would have to immediately take the offensive with alien beings? They could care less. They have learned how to erase hate.
I can tell that xanax is kicking in. :-)
CMC/GEM

Quoting 516. sar2401:

I can tell that xanax is kicking in. :-)



BaHaHa I just cant help myself lol
Quoting 486. ncstorm:




It seems the WPC leans it's forecast far too much on the operational GFS does instead of a model blend, which is odd I think.

It's basing this forecast too heavily on low development east of Florida, while local NWS offices know not to lean on such a low confidence forecast.
Quoting 495. sar2401:

Yeah, I used to drive my family nuts when I was your age about anything having to do with weather. I wish we would have had the internet then. I would have learned a lot more about it than just reading every weather related book at the library. What are your plans for the future? Do you want to become a meteorologist?

Ofcourse I would love to become a meteorologist.
Quoting 499. wunderkidcayman:


maybe because you may not have one lol

no seriously best thing to do is wait and see wait till a low develops and see where it goes from there
Maybe it's because you don't have a...sorry, never mind. :-)

That was kind of my point. All the models we have are a big guessing game until they really have something to track.
sorry i messed up a link
Quoting 518. K8eCane:



BaHaHa I just cant help myself lol
LOL. I have to take valium every day for my Meniere's Disease. I'm so habituated to it that I don't really notice any effects...except occasionally. Then I do get a little loopy. That may explain some of my posts. :-)
Quoting 522. K8eCane:
https://s.aolcdn.com/dims-shared/dims3/WEBMAIL/th um bnail/291x167/http://dlug-assets.grvcdn.com/73/52/ c8/c4/71/1d/a8/ce/96/94/b1/db/36/8c/b9/0a-93472130 5556b27e4353e09.91921347.jpg
An AOL logo? That stuff is really getting to you today. 8-)
Quoting 394. sar2401:

It's that cutoff low or trough that's going to bring the rain to Florida and, I hope, to me. The ECMWF has been depicting this for several days, and the cutoff will drag some good moisture across the Gulf to Florida. I think whatever finally develops from the south is going to be a sideshow compared to this feature.


Yeah that's what I'm saying and I agree, it seems the GFS is suffering from convective feedback as usual. I'm not saying to throw it's solution in the trash, but even if it's solution pans out, to expect anything significantly organized the way it has depicted is not impossible, but quite low.

The GFS doesn't place enough precip emphasis over the southeast including your area and my area from the cutoff low, dispite that it develops deep moisture, divergent flow, and colder air aloft from the upper trough cutting off across the region, which should promote more rain than it's depicting. The reason why is that it insists on an organized tropical or subtropical system swinging by Florida and producing sinking air across the southeast and not quite as much moisture behind it that would counteract the impacts of the upper air system. This to me doesn't seem likely.

The ECMWF's solution looks more realistic, placing more emphasis and impacts from the cutoff low rather than this potential surface feature coming of the Caribbean.
Quoting 522. K8eCane:
sorry i messed up a link
Anything that starts with "https" won't ever work. Was it something really funny?
Quoting 520. tiggerhurricanes2001:

Ofcourse I would love to become a meteorologist.
OK, then don't do what I did. I learned enough math in high school to get by. I messed around too much in my first three years, so my senior year was taken up getting straight "A's" so I could get my GPA up enough that I could get in college - any college. I discovered two things in high school that were my downfall - fast cars and girls. In those days, you needed one to get the other. :-)
000
WTPZ41 KNHC 312039
TCDEP1

HURRICANE ANDRES DISCUSSION NUMBER 15
NWS NATIONAL HURRICANE CENTER MIAMI FL EP012015
200 PM PDT SUN MAY 31 2015

The satellite presentation of Andres has improved considerably since
this morning. The eye has become more distinct and warmed in
infrared imagery, and is now surrounded by a ring of cloud tops of
about -60C to -70C. Objective and subjective Dvorak estimates have
increased, and currently range from T5.5/102 kt to T6.1/117 kt. The
initial intensity has been raised to 110 kt for this advisory.
Beyond the observed intensity increase today, the overall intensity
forecast reasoning has not changed. The cyclone will be moving over
cooler waters during the forecast period, and should cross the 26C
isotherm in about 36 hours, which should result in weakening. More
rapid weakening forecast at 48 hours and beyond, with Andres
forecast to become a remnant low in about 4 days as the shear
increases over very cool SSTs. The new NHC intensity forecast is
higher than the previous one through 48 hours to account for the
initial intensity, and is similar after that. The official
forecast is generally close to the IVCN intensity consensus.

The hurricane has jogged to the left since this morning, with an
initial motion of 270/07. Andres should gradually turn poleward
during the next several days as a weakness develops in the
subtropical ridge around 125W. There remains a fair bit of spread
in the track guidance throughout the period. The UKMET and ECMWF
are initially to the left of the rest of the guidance for the first
12 to 24 hours, and the NHC forecast trends towards those aids given
the more westerly initial motion. Late in the period, all of the
dynamical models now show a turn toward the north and northeast, but
significant spread remains. Given that Andres should be sheared
apart by days 4 and 5, the NHC forecast shows only a slow northward
drift, in better agreement with the ECMWF and GEFS ensemble mean.
The GFS remains an outlier with a track that appears to go too far
to the northeast for such a weak system. Beyond 24 hours, the new
NHC track is similar to or a little to the right of the previous
one, adjusted for the initial position and motion, and lies
a little to the left of the multi-model consensus.

The initial 34-kt and 50-kt wind radii have been adjusted based on a
recent ASCAT pass.

Andres is only the fifth major hurricane to form in the basin in
May since reliable records began in 1970. Previous May major
hurricanes were Adolph (2001), Alma (2002), Bud (2012), and Amanda
(2014).
Now don't tease the CMC.

Quoting 523. sar2401:

LOL. I have to take valium every day for my Meniere's Disease. I'm so habituated to it that I don't really notice any effects...except occasionally. Then I do get a little loopy. That may explain some of my posts. :-)


sar that Menieres is horrible. I feel for ya. Ive had patients that have had it and it drives them nuts. Yeah, since the CMC model said a storm could be coming to this general area, i went ahead and started my xanax intervention
NAVGEM is forecasting a square storm to form in the EPAC.

Quoting 523. sar2401:

LOL. I have to take valium every day for my Meniere's Disease. I'm so habituated to it that I don't really notice any effects...except occasionally. Then I do get a little loopy. That may explain some of my posts. :-)



Another piece of the puzzle.
Given the constancy and quantity of rainfall in the area, it would be interesting to know what the effect upon aquifer levels in the southern plains will be. People have been "mining" water there for decades, resulting in ecological harm to springs-2nd order stream habitats and wetlands for years. Will groundwater levels measurably be recharged? If so, it's the silver lining to this meteorological disaster for the area.


hurricane Andres maybe a cat 4 storm soon??

Quoting 526. sar2401:

Anything that starts with "https" won't ever work. Was it something really funny?



No it was an AP article telling how some cities are 70 years overdue for a major and could get surprised this year so well, i guess you could say it was funny
Quoting 525. Jedkins01:


Yeah that's what I'm saying and I agree, it seems the GFS is suffering from convective feedback as usual. I'm not saying to throw it's solution in the trash, but even if it's solution pans out, to expect anything significantly organized the way it has depicted is not impossible, but quite low.

The GFS doesn't place enough precip emphasis over the southeast including your area and my area from the cutoff low, dispite that it develops deep moisture, divergent flow, and colder air aloft from the upper trough cutting off across the region, which should promote more rain than it's depicting. The reason why is that it insists on an organized tropical or subtropical system swinging by Florida and producing sinking air across the southeast and not quite as much moisture behind it that would counteract the impacts of the upper air system. This to me doesn't seem likely.

The ECMWF's solution looks more realistic, placing more emphasis and impacts from the cutoff low rather than this potential surface feature coming of the Caribbean.
I have yet to read one Gulf Coast NWS discussion that gives more than passing attention to the low being developed by the GFS. That cutoff low, OTOH, has a lot of them concerned. If this sets up right, we could see 3-4 days after very heavy rain, especially over Florida. It's the kind of system that really promotes training storms. Because the WPC sticks so closely to the GFS solution, I think it's actually underforecasting rain in the 4-7 day window. It appears to be going under the assumption that the GFS low will end up going east of Florida and exiting the area within 24 hours. It seems to be giving very little weight to the ECMWF solution. The WPC says exactly that in their 1125 discussion -

BASED ON THE CONSIDERATIONS FOR FEATURES OF INTEREST AND
UNCERTAINTY...WPC MEDIUM RANGE SURFACE FRONTS/PRESSURES AND 500 MB
PROGS WERE PRIMARILY BASED FROM A BLEND OF 70 PCT 00 UTC NAEFS
(GEFS/CMC) ENSEMBLE MEAN AND 30 PCT 00 UTC ECMWF ENSEMBLE MEAN.
THIS MAINTAIN GOOD WPC CONTINUITY OVERALL AS NOTED.

They seem to be more worried about continuity that accuracy in this case.
Quoting 520. tiggerhurricanes2001:


Ofcourse I would love to become a meteorologist.
Quoting 527. sar2401:

OK, then don't do what I did. I learned enough math in high school to get by. I messed around too much in my first three years, so my senior year was taken up getting straight "A's" so I could get my GPA up enough that I could get in college - any college. I discovered two things in high school that were my downfall - fast cars and girls. In those days, you needed one to get the other. :-)


agreed I personally hate with a vengeance math and it was just that I sucked at math but I was able to get some help and Study hard in my 6th form "senior year" and it helped a lot also funny enough physics was my best subject in High School have no idea why
College and University was absolutely crap for me best thing to do is to choose your College and University carefully and pick one that specialize in Met

but anyway after all the headaches and troubles and near suicide I got through it fine

Quoting 521. sar2401:

Maybe it's because you don't have a...sorry, never mind. :-)

That was kind of my point. All the models we have are a big guessing game until they really have something to track.


ah ha ha lolx1000

as I said we wait and watch wait till low develops

but in the mean time we relish in the enjoyment of the models ;)
Quoting 536. K8eCane:



No it was an AP article telling how some cities are 70 years overdue for a major and could get surprised this year so well, i guess you could say it was funny
Was it this article?

OCEAN CITY, Maryland (AP) — For millions of Americans living in hurricane zones on the Gulf and East coasts, recent decades have been quiet — maybe too quiet.
Cities like Tampa, Houston, Jacksonville and Daytona Beach historically get hit with major hurricanes every 20 to 40 years, according to meteorologists. But those same places have now gone at least 70 years — sometimes more than a century — without getting smacked by those monster storms, according to data analyses by an MIT hurricane professor and The Associated Press.
Quoting 540. sar2401:

Was it this article?

OCEAN CITY, Maryland (AP) — For millions of Americans living in hurricane zones on the Gulf and East coasts, recent decades have been quiet — maybe too quiet.
Cities like Tampa, Houston, Jacksonville and Daytona Beach historically get hit with major hurricanes every 20 to 40 years, according to meteorologists. But those same places have now gone at least 70 years — sometimes more than a century — without getting smacked by those monster storms, according to data analyses by an MIT hurricane professor and The Associated Press.




YEP!!
Quoting 539. wunderkidcayman:



but in the mean time we relish in the enjoyment of the models ;)


You may relish, but the models better ketch-up with what's going to happen.
Thats actually a good article. People shouldnt take what it says lightly
544. beell
Quoting 525. Jedkins01:



Yeah that's what I'm saying and I agree, it seems the GFS is suffering from convective feedback as usual. I'm not saying to throw it's solution in the trash, but even if it's solution pans out, to expect anything significantly organized the way it has depicted is not impossible, but quite low.

The GFS doesn't place enough precip emphasis over the southeast including your area and my area from the cutoff low, dispite that it develops deep moisture, divergent flow, and colder air aloft from the upper trough cutting off across the region, which should promote more rain than it's depicting. The reason why is that it insists on an organized tropical or subtropical system swinging by Florida and producing sinking air across the southeast and not quite as much moisture behind it that would counteract the impacts of the upper air system. This to me doesn't seem likely.

The ECMWF's solution looks more realistic, placing more emphasis and impacts from the cutoff low rather than this potential surface feature coming of the Caribbean.


I would not discount the dry, moderately deep layer, northwesterly/westerly flow (back side of the trough/cut-off) as a summertime ridge builds in from the west over TX to temper QPF precip-especially over the northeastern gulf coast and part of the west coast of FL


heavy rain and t.storm a few hours ago in east haven,conn
Quoting 541. K8eCane:



YEP!!
The idea that some place is "overdue" is a little much. The chances of a city getting hit by a hurricane doesn't change, even if a hurricane went through last month. We saw that in 2004 and 2005, where the same places did get multiple hurricanes. What is important is the lack of experience both citizens and emergency management agencies have dealing with a large hurricane and the evacuations involved in a place like Tampa. Andrew and Katrina are just far enough in the past that many have forgotten or were too young to know much about it. Emergency management agencies practice all the time but that's not a substitute for having handled an acutal hurricane. It's going to be a very big challenge to get things right when the inevitable hurricane does hit.
Quoting 544. beell:


I would not discount the dry, moderately deep layer, northwesterly/westerly flow (back side of the trough/cut-off) as a summertime ridge builds in from the west over TX to temper QPF precip-especially over the northeastern gulf coast and part of the west coast of FL
Several of the forecasters have talked about the ridge being a possible moderating factor in this event. For the sake of the people in Texas and Oklahoma, I hope so.
Link
Hurricane Season 2015 countdown. I made this myself.
Quoting 493. CybrTeddy:



A little loopy..

It's actually a zig-zag, Kyle. :)

2015 Hurricane Season Outlook coming soon.
latest from HWRF

551. beell
Quoting 547. sar2401:

Several of the forecasters have talked about the ridge being a possible moderating factor in this event. For the sake of the people in Texas and Oklahoma, I hope so.


Didn't see it mentioned here (could of missed it). There should still be a concentrated plume of tropical moisture from the Caribbean but perhaps further east/southeast than the FL panhandle/Big Bend.

Just between you and me, I'm in no hurry for a ridge to park over TX.
:)
Quoting 548. HurricaneAndre:

Link
Hurricane Season 2015 countdown. I made this myself.


cool

Quoting 549. TylerStanfield:


It's actually a zig-zag, Kyle. :)

2015 Hurricane Season Outlook coming soon.


yes Zig-Zag

553. txjac
Quoting 551. beell:



Didn't see it mentioned here (could of missed it). There should still be a concentrated plume of tropical moisture from the Caribbean but perhaps further east/southeast than the FL panhandle/Big Bend.

Just between you and me, I'm in no hurry for a ridge to park over TX.
:)



Ditto that for me
0z Best Track lists Andres at 120 knots!

EP, 01, 2015060100, , BEST, 0, 153N, 1190W, 120, 943, HU, 34, NEQ, 140, 90, 80, 100, 1007, 250, 20, 0, 0, E, 0, , 0, 0, ANDRES, D,
Quoting 554. TropicalAnalystwx13:

0z Best Track lists Andres at 120 knots!

EP, 01, 2015060100, , BEST, 0, 153N, 1190W, 120, 943, HU, 34, NEQ, 140, 90, 80, 100, 1007, 250, 20, 0, 0, E, 0, , 0, 0, ANDRES, D,


>:(
Quoting 436. sar2401:

That's what professionals in the field usually do. Unlike us, they don't have time to sit around and speculate. :-)
I bet they speculate as much as we do .... they just don't post their speculations on the NHC blog .... lol ...
Quoting 518. K8eCane:




BaHaHu I just cant help myself lol
You rang?
Quoting 550. wunderkidcayman:

latest from HWRF



Moved further west again...Hmmmmm
Quoting 557. nygiants:


Moved further west again...Hmmmmm


out of the 4 runs HWRF has on this system not much has changed
Quoting 556. BahaHurican:

I bet they speculate as much as we do .... they just don't post their speculations on the NHC blog .... lol ... You rang?



BAHA that was totally a slip of rhe fingers. What could it mean??
560. 882MB




Andres got better and surprised everyone by becoming a category 3 hurricane and we now have TD 2-E.



Read more...
Quoting 554. TropicalAnalystwx13:

0z Best Track lists Andres at 120 knots!

EP, 01, 2015060100, , BEST, 0, 153N, 1190W, 120, 943, HU, 34, NEQ, 140, 90, 80, 100, 1007, 250, 20, 0, 0, E, 0, , 0, 0, ANDRES, D,



can you send me the link of this informations? I lost my favourites pages.
Quoting 561. meteorologistkidFL:

Andres got better and surprised everyone by becoming a category 3 hurricane and we now have TD 2-E.



Read more...


actually it's cat 4 right now hahaha. 120 knots.
Quoting 562. pablosyn:



can you send me the link of this informations? I lost my favourites pages.

Link
Quoting 291. Barefootontherocks:

Re: The state of deductive reasoning in these blog comments.

1)

Okay. Where does this comment state any belief against or denial of climate change?

What the comment states is that scientists (and I'd add AGW activists) lose credibility when they blame climate change for every current extreme weather event.

2) The ability to know other bloggers' political beliefs from their comments about weather and blind squirrels is a truly remarkable gift.
;)


Climate scientists do not say any single event is the result of climate change just that the likelihood of these events increases with a shorter interval than would have been expected in the past. It's called math, look it up.
Quoting 558. wunderkidcayman:



out of the 4 runs HWRF has on this system not much has changed


Who knows, probably won't even become anything strong like it is saying.
Quoting 401. Xyrus2000:



The graph isn't correct and neither is the interpretation.

For those not familiar with the subject, the Earth is not quite a perfect black body but it's close enough to be approximated by one. If the Earth had absolutely no atmosphere at all, then the average global temperature would be around -16C. However, the current global average temperature is 14C, a difference of about 30C.

That 30C is the result of greenhouse gases. The latest estimates of contribution I could find with a quick search:

Water Vapor: 72%
CO2: 17%
Methane: 6%
Ozone: 4%
Other: 1%

What the graph and the moronic site that yoboi pulled it from is trying to say is that CO2 isn't important because water vapor makes up most of the GHG effect. What the site, and yoboi, don't understand and never will is that water vapor has an atmospheric lifetime of only a few days. It doesn't accumulate. Water vapor increasing or decreasing in the atmosphere is a reactive response to temperature changes, not a driver of them.

To drive temperature changes over the long term requires a greenhouse gas that can stay and accumulate in the atmosphere. That's CO2 (both methane and ozone have short atmospheric duration). Increase the CO2, temperatures go up. Temperatures go up, more water evaporates.

Yoboi must really think people on this site are stupid if he honestly thinks he can post trash like this and not get called out on it.




I'm afraid he does actually believe this.
The Aral sea, what happened? Natural evaporation through two tributaries, used for cotton growth through the middle soviet occupation of uzbe...i o.k.... got to tell you, this is a lake that survived through natural evap for MILLIONS of years. Sorry, the death of this inland sea is bad water magmnt. I got the same National Geographic, this is not climate, but as an example of water mngnt...water evap is real...Read the National Geo...worth it, never seen a whole sea die, but the soviets thought it would go in the 60's
Patrick is now broadcasting on his new aquos Crystal mobile device. is cool
Quoting 566. nygiants:



Who knows, probably won't even become anything strong like it is saying.


who knows, could become strong similar or even stronger than CMC/GEM
who knows

lets wait and see
Quoting 512. K8eCane:




Its in the valium family. I have anxiety disorder and one of the things that trigger it is an approaching storm
I handle everything ok except hurricanes....then i have a real problem.
Keeping an eye on the state of Arctic sea ice as we get closer to maximum melting season ...

A pattern of higher pressure has moved over the western and central Arctic over the past couple of weeks, which is conducive for sunnier conditions and more surface melting as we approach summer solstice,

Pressure in the Barent's sea has been lower, and there has been a vigorous storm in the vicinity the past 2-3 days.


Notice the big patch of open water north of Franz Josef Land islands. The melting in the vicinity of of the Barents Sea is due to anonymously warm sea water that is present, and the high winds from storms are helping to break up the ice edge and promote melting. The Barents Sea has been very warm for quite some time, according to Matishov et al, "The positive water temperature anomaly in Atlantic water masses has remained in the Barents Sea for no less than ten years ", see their paper (abstract and link to full pdf) here. About one-half of the Atlantic water that enters the Arctic Ocean comes through the Barent's sea, and with these high sea temperatures we could be looking at a lot more melting encroaching towards the central Arctic as the season progresses,
Quoting 570. wunderkidcayman:



who knows, could become strong similar or even stronger than CMC/GEM
who knows

lets wait and see


Where is this TD/TS suppose to spin up, the only area I see right now is off Nicaragua.Is that it?
I would like to visit the Aral sea however, a disaster of epic proportion, a sea that has become a dessert of toxic waste. Run now, this is more then you want
WOOOOOOOOOOOOW GFS, really?



Source: GFS of course and the twitter of my good friend Ryan Maue. :)

Gonu wants a brother.

Formed: June 1st 2007
Dissipated: June 7th 2007.
Quoting 573. stormpetrol:



Where is this TD/TS suppose to spin up, the only area I see right now is off Nicaragua.Is that it?
its sorta gonna be an open wave of energy that will eventually form a weak to mod area of low pressure somewhere
Quoting 544. beell:



I would not discount the dry, moderately deep layer, northwesterly/westerly flow (back side of the trough/cut-off) as a summertime ridge builds in from the west over TX to temper QPF precip-especially over the northeastern gulf coast and part of the west coast of FL


But the upper trough is expected to remain west of the region, and unless the ridge over Texas builds further east than any model is forecasting, there's no reason for low level dry air advection from the northwest, unless a solution of a organized low moving east of Florida actually happens, then drier air advection from the northwest could occur.

Also, that would only be through the extended, Tuesday Wednesday, and likely Thursday as well, will still be under full influence of deep moist advection and cold advection aloft and divergent flow aloft.
Quoting 573. stormpetrol:



Where is this TD/TS suppose to spin up, the only area I see right now is off Nicaragua.Is that it?

I am not going to worry about it until at least Tuesday because it will drive people crazy if people look every couple of hours to see whats happening when we all know its gunna keep changing LOL
Spectacular thunderstorms here this evening, sadly I squeezed through a gap like yesterday, only 0.19 here, probably an inch plus less than a quarter mile away.
Quoting 572. guygee:

Keeping an eye on the state of Arctic sea



forecasted sfc temps as of 11 pm est

Quoting 573. stormpetrol:



Where is this TD/TS suppose to spin up, the only area I see right now is off Nicaragua.Is that it?


in the NW Caribbean starts near Nic/Hon

its the tropical wave that currently in the SW Caribbean
Evening all. I'm not sure how I didn't know about this. Being a bookworm and a weather geek. :-)
But sounds like an interesting read. Came out in 2012

Lessons from Hurricane Ike
by Philip B. Bedient, Philip B. Bedient (Editor), James B. Blackburn Jr. (Contribution by), Shannon S. Van Zandt (Contribution by), Samuel D. Brody

Overview
If Hurricane Ike had made landfall just fifty miles down the Texas coast, the devastation and death caused by what was already one of the most destructive hurricanes in US history would have quadrupled. Ike made everyone realize just how exposed and vulnerable the Houston-Galveston area is in the face of a major storm. What is done to address this vulnerability will shape the economic, social, and environmental landscape of the region for decades to come.

In Lessons from Hurricane Ike, Philip Bedient and the research team at the Severe Storm Prediction, Education, and Evacuation from Disasters (SSPEED) Center at Rice University provide an overview of some of the research being done in the Houston-Galveston region in the aftermath of Hurricane Ike. The center was formed shortly after Hurricanes Katrina and Rita in 2005. Its research examines everything from surge and inland flooding to bridge infrastructure.

Lessons from Hurricane Ike gathers the work of some of the premier researchers in the fields of hurricane prediction and impact, summarizing it in accessible language accompanied by abundant illustrations—not just graphs and charts, but dramatic photos and informative maps. Orienting readers to the history and basic meteorology of severe storms along the coast, the book then revisits the impact of Hurricane Ike and discusses what scientists and engineers are studying as they look at flooding, storm surges, communications, emergency response, evacuation planning, transportation issues, coastal resiliency, and the future sustainability of the nation’s fourth largest metropolitan area.

Editorial Reviews
statesman.com


"Lessons from Hurricane Ike is different in that it really offers lessons, not just sensational photographs of wreckage and stories of heroism and tragedy, the usual gist of hurricane books."--statesman.com

Distinguished Professor of Atmospheric Sciences and Oceanography at TAMU - Gerald R. North

"This collection of essays summarizes the science and impacts of hurricanes impinging on the Texas Coast. The book is thoughtful, accessible, and potentially useful to the policy maker and the public alike. It is beautifully and provocatively illustrated with numerous color photographs and diagrams. The collection is up to date including the most recent deadly storms to affect Texas."--Gerald North, University Distinguished Professor of Atmospheric Sciences and Oceanography, Texas A&M University

Director, National Hurricane Center - Bill Read

"Three storms from the first decade of the new millennium, Allison, Rita, and Ike, exposed vulnerabilities to the highly developed upper Texas Gulf Coast from the impacts of tropical cyclones. Lessons from Hurricane Ike provides an excellent overview of the scientific, societal, and economic challenges facing our area as a result of Ike. This book should be read by anyone in an official capacity who desires a deeper understanding of the complexities of developing in the hurricane impact zone. Particular attention should be paid to Chapter 12, Steps to the Future, which I found very insightful in addressing the daunting task before the next 'Big One' impacts the Texas Gulf Coast."-- Bill Read, director, National Hurricane Center


Quoting 573. stormpetrol:



Where is this TD/TS suppose to spin up, the only area I see right now is off Nicaragua.Is that it?


GFS
CMC/GEM
NAVGEM
FIM NOAA
HWRF
shows it and
Euro to a big lesser extent
Quoting 581. KEEPEROFTHEGATE:


forecasted sfc temps as of 11 pm est


Forecast for tomorrow from the ECMWF,
Quoting 511. barbamz:

Will El Nino Break the California Drought? The Odds Are Not Good
31 May 201, posted by Dan Satterfield

Good night with this, folks ....


hi...this is about rainbows that are really a full circle :) but u r night-night
If he wants to rival Iselle ... I think he already surpass it.











UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 8.2.1
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 01 JUN 2015 Time : 013000 UTC
Lat : 15:14:02 N Lon : 119:06:01 W


CI# /Pressure/ Vmax
6.4 / 938.8mb/124.6kt


Final T# Adj T# Raw T#
6.4 6.5 6.5

Estimated radius of max. wind based on IR : 20 km

Center Temp : +6.9C Cloud Region Temp : -70.3C

Scene Type : EYE

Positioning Method : RING/SPIRAL COMBINATION

Ocean Basin : EAST PACIFIC
Dvorak CI > MSLP Conversion Used : ATLANTIC

Tno/CI Rules : Constraint Limits : NO LIMIT
Weakening Flag : OFF
Rapid Dissipation Flag : OFF

C/K/Z MSLP Estimate Inputs :
- Average 34 knot radii : 102km
- Environmental MSLP : 1009mb

Satellite Name : GOES15
Satellite Viewing Angle : 25.6 degrees


588. beell
Quoting 578. Jedkins01:



But the upper trough is expected to remain west of the region, and unless the ridge over Texas builds further east than any model is forecasting, there's no reason for low level dry air advection from the northwest, unless a solution of a organized low moving east of Florida actually happens, then drier air advection from the northwest could occur.

Also, that would only be through the extended, Tuesday Wednesday, and likely Thursday as well, will still be under full influence of deep moist advection and cold advection aloft and divergent flow aloft.


Just a thought, Jed.

I don't regard this mid-level system as particularly robust or cold-cored. Some convergent mid-level flow between the Texas ridge and the low itself will not help matters-especially if it tracks towards the TN Valley.

And I didn't say it would not rain-only the amounts may be tempered some along the NE gulf coast.


500 mb rh-valid Tuesday, 8PM EDT


500 mb heights, winds-Tuesday, 8PM EDT

(fixed the times and dates)
My Atlantic Hurricane Season Analysis will be out tomorrow.
But I'll go ahead and spoil the fun for you and let those who really want to read the analysis part of the blog to stop by tomorrow.

Goodnight Everyone
Quoting 588. beell:



Just a thought, Jed.

I don't regard this mid-level system as particularly robust or cold-cored. Some convergent mid-level flow between the Texas ridge and the low itself will not help matters-especially if it tracks towards the TN Valley.


500 mb rh-valid Tuesday, 8PM EDT


500 mb heights, winds-Wednesday, 2AM





You're right, but temperatures that wouldn't be considered particularly cold aloft in say the northern half of the U.S. would be relatively impressively cold aloft over a lower latitude like Florida in early June.
JeffMasters has created a new entry.
BTW guys the official Atlantic hurricane Season will start in less than 2hrs EST
and our First official in-season TWO for 2015 in less than 3 hrs EST
Quoting 586. WaterWitch11:



hi...this is about rainbows that are really a full circle :) but u r night-night
Here's the link to the Satterfield discussion of CA rains:

http://blogs.agu.org/wildwildscience/2015/05/31/w ill-el-nino-break-the-california-drought-the-odds- are-not-good/
Quoting 565. VAstorms:



Climate scientists do not say any single event is the result of climate change just that the likelihood of these events increases with a shorter interval than would have been expected in the past. It's called math, look it up.
No worry about my math skills. If all you can do is throw an insult my way, you must realize your argument is weak. In this case, not only weak but erroneous. There is no "shorter interval" connection at this point. If and when that connection is made, you will be correct. As of now, you are not. You might want to look at that link somebody left for 1900hurricane earlier today.
...........

Such great wu spirit I witnessed here today! Thank you so much for the jokes about me leaving "The Blog" to deal with mold in my home. What comes around goes around.
;)
596. vis0
Let me be the FIRST to post that my clock is 2 minutes fast...i wunder if Nature wears a wunderwatch...and set to what timezone + or 1 hrs to GMT.?