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 StormTracker2K:



Weakness across the eastern gulf. TVCN and UKMET seem like a good bet to me. By the way that is a pretty decent trough on coming down the eastern US.


Where is there a weakness?? I see the nose of a strong 500mb ridge over North FL extending into the Northern Gulf. It doesn't matter because this is way out in time, but as of now there is no weakness....thus the GFS and the Euro not curving it into the Eastern Gulf.
Member Since: July 15, 2006 Posts: 17 Comments: 10159
i hate how the NHC is so conservative. there is a chance this could be a moderate tropical storm when it gets to the islands.. they need to call this a td at 5 in my opinion so people at the islands take notice
Member Since: July 25, 2011 Posts: 0 Comments: 1102
Quoting MississippiWx:
Alberto:



99L:



Come on, now. We can't have a double standard just because this isn't on the US's doorstep. NHC should classify at 5PM.


I disagree, we can have a double standard. It's important to get warnings out in time for people to react when landfall is less than 48 hours, 99L is days away from any land, no reason to rush classification until you are 100% sure.
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Quoting Chiggy:


TVCN is NOT a model, rather it's an Average of at least 2 of GHMI, EGRI, NGPI, HWFI, GFSI, GFNI, EMXI. YOu can find more info here:
http://www.nhc.noaa.gov/modelsummary.shtml


TVCN is a model that the NHC uses.

Member Since: October 26, 2011 Posts: 0 Comments: 2651
Quoting 954FtLCane:


you have posted the same post, or something very similar to it, like 5 times. we get what you want. right now it is going wnw not W or WSW. Until the NHC says otherwise it is going WNW

not what I want its whats goin to happen I didn't say anything about WSW so then what in the world did WSW do to you for you to bring it up

I am just making sure that peole know that this WNW movement is not going to stick arourd for a long time so yes WNW FOR NOW
Member Since: June 13, 2009 Posts: 2 Comments: 10891
For the first time today, it appears that the center is underneath the cloud canopy.

Member Since: July 15, 2006 Posts: 17 Comments: 10159
Quoting MississippiWx:


That's really not a very big trough, especially when you're talking about a system down in the Caribbean with a large Bermuda high nosing in between them.



Weakness across the eastern gulf. TVCN and UKMET seem like a good bet to me. By the way that is a pretty decent trough on coming down the eastern US.
Member Since: October 26, 2011 Posts: 0 Comments: 2651
1029. ryang
I have a question. How early in advance do TS watches/warnings have to be posted?
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Quoting TropicalAnalystwx13:
Looks like we are not getting a renumber at 5 PM EDT. Maybe 11 PM EDT?



Or they wait for recon.
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Quoting TropicalAnalystwx13:
Looks like we are not getting a renumber at 5 PM EDT. Maybe 11 PM EDT?



Still an hour before the advisory. Hope 99L doesn't find its groove tonight because the islands will have very little notice if the NHC is really going to wait until their precious plane gets in there tomorrow.
Member Since: July 15, 2006 Posts: 17 Comments: 10159
1026. Chiggy
Quoting StormTracker2K:


How do not see this? That's a big trough my friend and you will continue to most likely see further shifts north on the model runs. infact the TVCN model bends 99L nnw into C Cuba in 5 days. Seems very reseasonable to me.



TVCN is NOT a model, rather it's an Average of at least 2 of GHMI, EGRI, NGPI, HWFI, GFSI, GFNI, EMXI. YOu can find more info here:
http://www.nhc.noaa.gov/modelsummary.shtml
Member Since: June 26, 2012 Posts: 0 Comments: 297
1025. A4Guy
Quoting flsky:

For new folks, the XTRP "model" just shows the direction that the storm was moving when the model map was created. It's not an official model.


...and TVCN is the model consensus - it's not its own model either, I believe. The "consensus" being the average of the other Dynamic models.
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TD any moment now.
Book it.
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edited for clarity.
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Quoting LargoFl:
...............................remember this morning, almost all of these models put it going into the gulf?...now look closely, is that 2 now making a turn over cuba


That's what I've been thinking all day...a more north shift in a couple days.
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1022. nigel20
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Quoting wunderkidcayman:
99L should be moving back to the W or N or due W or S of due WNW soon this WNW movement is not a definite movement


arrrggggg,,,,,,, really? lol....you have posted the same post, or something very similar to it, like 5 times. we get what you want. right now it is going wnw not W or WSW. Until the NHC says otherwise it is going WNW
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1020. ryang
Quoting MAweatherboy1:
99L is probably very close to TD status if it isn't there already, but you know the NHC... No way they renumber this by 5PM and honestly I doubt they do it at 11PM either... Probably 5AM tomorrow morning... They may want to see how it survives another DMIN.


I agree with this.
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Looks like we are not getting a renumber at 5 PM EDT. Maybe 11 PM EDT?

Member Since: July 6, 2010 Posts: 113 Comments: 31409
Quoting Bluestorm5:
Thanks!
Your welcome!
Member Since: March 16, 2012 Posts: 127 Comments: 7927
Quoting MississippiWx:


That's really not a very big trough, especially when you're talking about a system down in the Caribbean with a large Bermuda high nosing in between them.
the bermuda high would be weakened by that trough. i dont think florida will be impacted but who knows. on that run instead of moving due WEST into mexico ERNESTO should start pulling NW before moving back wnw as the ridge rebuilds. the Euro model shows a landfall in Texas
Member Since: July 25, 2011 Posts: 0 Comments: 1102
99L is probably very close to TD status if it isn't there already, but you know the NHC... No way they renumber this by 5PM and honestly I doubt they do it at 11PM either... Probably 5AM tomorrow morning... They may want to see how it survives another DMIN.
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Quoting wxchaser97:

Where they post renumbers
Thanks!
Member Since: August 1, 2011 Posts: 28 Comments: 7896
1013. LargoFl
Quoting LostTomorrows:
Ok, all ye who are busy with 99L, can someone tell me what they think of that rather tropical looking system off the coast of Maine? It's been looking like it wants to make some noise.
..here you go...............A quick moving low pressure system has brought rain to some parts of Maine and New Hampshire during the overnight hours. The good news is that this ocean storm is a heading on out of here this morning, and we will start to see some partial clearing from west to east through the day. Temperatures will also warm nicely once we clear out the clouds. The biggest change over the next couple days will be the return of some muggy weather. That continues right through the upcoming weekend.
Member Since: August 6, 2011 Posts: 4 Comments: 36826
1012. 7544
models shifting back north to fl again for now anyway
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Quoting StormTracker2K:


How do not see this? That's a big trough my friend and you will continue to most likely see further shifts north on the model runs. infact the TVCN model bends 99L nnw into C Cuba in 5 days. Seems very reseasonable to me.



That's really not a very big trough, especially when you're talking about a system down in the Caribbean with a large Bermuda high nosing in between them.
Member Since: July 15, 2006 Posts: 17 Comments: 10159
99L should be moving back to the W or N or due W or S of due WNW soon this WNW movement is not a definite movement
Member Since: June 13, 2009 Posts: 2 Comments: 10891
1009. flsky
Quoting hurricanejunky:
Models look to have shifted back north somewhat...


For new folks, the XTRP "model" just shows the direction that the storm was moving when the model map was created. It's not an official model.
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Quoting Bluestorm5:
Where do they post the new numbers?

Where they post renumbers
Member Since: March 16, 2012 Posts: 127 Comments: 7927
Quoting MAweatherboy1:
Good afternoon everyone! What's been happening with 99L today??
Afternoon, 99L is almost a TD, still no consensus among the models, and the gfs is making 99L stronger on some of its runs.
Member Since: March 16, 2012 Posts: 127 Comments: 7927
Quoting MiamiHurricanes09:
If a renumber occurs, it'll happen within the next 15 minutes.
Where do they post the new numbers?
Member Since: August 1, 2011 Posts: 28 Comments: 7896
Quoting jeffs713:
I just don't see the CMC's solution. It is an outlier track-wise, and I don't see enough of a weakness early enough to pull it north of the Islands for that kind of a track. Later on, yes, but 2-3 days from now, not so much.


How do not see this? That's a big trough my friend and you will continue to most likely see further shifts north on the model runs. infact the TVCN model bends 99L nnw into C Cuba in 5 days. Seems very reseasonable to me.

Member Since: October 26, 2011 Posts: 0 Comments: 2651
1004. 7544
Quoting LargoFl:
..I still say we need to watch that wave down by PR


agree its starting to fire up and thats where 99l could head too
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Well the models look like they got something for everyone. Should be an interesting week or two around here. Less there be a shearing experience.
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1002. LargoFl
Member Since: August 6, 2011 Posts: 4 Comments: 36826
Ok, all ye who are busy with 99L, can someone tell me what they think of that rather tropical looking system off the coast of Maine? It's been looking like it wants to make some noise.
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Quoting MississippiWx:
Alberto:



99L:



Come on, now. We can't have a double standard just because this isn't on the US's doorstep. NHC should classify at 5PM.


Still time, but I'm beginning to think they are going to wait even another forecast package when there is really no use.
Member Since: July 15, 2006 Posts: 17 Comments: 10159
If a renumber occurs, it'll happen within the next 15 minutes.
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I'm back everyone
Member Since: March 16, 2012 Posts: 127 Comments: 7927
997. flsky
Quoting Chicklit:
I'm late on this as I was caught by surprise by a storm that just came through here. But it's worth posting again anyway:

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...SPECIAL FEATURE...

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 15N45W 13N47W...
TO A 1009 MB LOW PRESSURE CENTER THAT IS NEAR 11N47W.
NUMEROUS STRONG CONVECTIVE PRECIPITATION IS FROM 10N TO 12N BETWEEN 47W AND 51W.

BROKEN TO OVERCAST MULTILAYERED CLOUDS AND OTHER POSSIBLE RAINSHOWERS COVER THE AREA ELSEWHERE FROM 6N TO 16N BETWEEN 43W AND 52W.

ENVIRONMENTAL CONDITIONS ARE CONDUCIVE FOR TROPICAL CYCLONE FORMATION. IT IS POSSIBLE THAT THIS LOW PRESSURE CENTER MAY BECOME A TROPICAL DEPRESSION LATER TODAY OR TONIGHT.

THIS SYSTEM HAS A HIGH CHANCE OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS AS IT MOVES WEST-NORTHWESTWARD 17 KT.

ANYONE WHO LIVES IN THE WINDWARD ISLANDS AND/OR WHO HAS INTERESTS IN THE WINDWARD ISLANDS SHOULD MONITOR THE PROGRESS OF THIS SYSTEM.

99L's gaining in latitude and attitude for the time being.

A great storm! Cooled things down, lots of thunder and lightning - who could ask for more out of a CFL afternoon!
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Quoting MAweatherboy1:
Good afternoon everyone! What's been happening with 99L today??
Almost Tropical Depression. Couple of models taking it to Gulf of Mexico.
Member Since: August 1, 2011 Posts: 28 Comments: 7896
000
NOUS42 KNHC 011453
REPRPD
WEATHER RECONNAISSANCE FLIGHTS

CARCAH, NATIONAL HURRICANE CENTER, MIAMI, FL.

1100 AM EDT WED 01 AUGUST 2012

SUBJECT: TROPICAL CYCLONE PLAN OF THE DAY (TCPOD)

VALID 02/1100Z TO 03/1100Z AUGUST 2012

TCPOD NUMBER.....12-075



1. SUSPECT AREA.....APPROACHING THE LESSER ANTILLES

FLIGHT ONE -TEAL 70-

A. 02/1800Z

B. AFXXX 01BBA INVEST

C. 02/1530Z

D. 12.4N 54.4W

E. 02/1730Z TO 02/2030Z

F. SFC TO 10,000 FT



FLIGHT TWO -TEAL 72-

A. 03/0600, 1200Z

B. AFXXX 0205A CYCLONE

C. 03/0400Z

D. 13.0N 57.5W

E. 03/0530Z TO 03/1200Z

F. SFC TO 10,000 FT



2. OUTLOOK FOR SUCCEEDING DAY: CONTINUE 6-HRLY FIXED.
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Quoting MississippiWx:
Alberto:



99L:



Come on, now. We can't have a double standard just because this isn't on the US's doorstep. NHC should classify at 5PM.

No renumber yet...
Member Since: July 6, 2010 Posts: 113 Comments: 31409
Alberto:



99L:



Come on, now. We can't have a double standard just because this isn't on the US's doorstep. NHC should classify at 5PM.
Member Since: July 15, 2006 Posts: 17 Comments: 10159
992. ryang
99L should start to turn more westerly soon.

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Hey all, do you think?...

that trough coming off the eastern U.S. will pull 99L north alittle?

and

the PR wave will make a path (so to speak) of favorable conditions for potential Ernesto to grow and of north of todays GFS and EURO model predictions?


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Good afternoon everyone! What's been happening with 99L today??
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Models look to have shifted back north somewhat...

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Quoting Stormchaser2007:


In addition to what SouthDade said, it also did detach from the ITCZ today.
Quoting SouthDadeFish:
I'm not sure that it has really turned to the North that much, but rather that bend is a reflection of estimating the center too far to the South over the past 24-36 hours.

Both of these are true. Maybe I'm just paranoid the CMC would have actually been right for once, lol.
Member Since: July 6, 2010 Posts: 113 Comments: 31409
Member Since: August 6, 2011 Posts: 4 Comments: 36826
Quoting LargoFl:
..I still say we need to watch that wave down by PR
Agree, with you skirting Puerto Rico, or over, then towards the Mona Canal and eastern,DR, very flat lands , wont do any harm to the circulation.
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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.