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 doabarrelroll:
I wonder how may people realize that Katrina was not a Cat 5 at landfall... I know it wa sa flood event but most people assume it was a Cat 5

Patrap usually calls it cat 4--actually was cat 3--but the SS category does not match the surge it generated.
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Quoting washingtonian115:
Can you just stop all ready?.Does every post have to be bold or say WOW at the end?.

YES. WOW!


;)
Member Since: August 3, 2008 Posts: 16 Comments: 5880
Quoting washingtonian115:
Can you just stop all ready?.Does every post have to be bold or say WOW at the end?.
but thats jasoniscoolman for ya
Member Since: July 15, 2006 Posts: 170 Comments: 53544
Quoting jcpoulard:
Did we notice the BLOB south of DR it increase in size since this morning and wind shear is very low in this area. Any developement ?



No.
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Quoting catastropheadjuster:


Hydrus, Hey how are ya? I was wondering from all the reading I been doing on the blog for the past few weeks or more, a lot of folks been saying anything that get in the Caribbean will be torn apart, is that still true? I think they where saying the upper level winds where like 15-30 or something like that. Plus with El nino isn't it cooler waters? I may have it all wrong I don't know. I mean some where saying it's gonna be a quite season, i know it only takes one to make it a bad season.

Sheri
There are still questions about what conditions will be like when 99L reaches the Eastern Caribbean. Here is the 120 hour chart of areas that should be favorable for development. 99L will be near these regions. It will be entering water that is a little warmer than it is over now also.
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Did we notice the BLOB south of DR it increase in size since this morning and wind shear is very low in this area. Any developement ?

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Quoting yoboi:


it's not really off topic it's called being prepared for a hurricane, and if talking about being prepared saves someones life then i think it's well worth it...

Right, I'm not arguing that. I was specifically talking about "what if the levees held"... that comment, at this time of year, cannot go anyplace good.
Member Since: August 3, 2008 Posts: 16 Comments: 5880
Quoting AllStar17:


Agree. In fact, you could argue it should already be classified a TD IMO.


Agreed. I think it is a TC right now, but you know how the NHC does things.
Member Since: July 15, 2006 Posts: 17 Comments: 10209
Quoting Pocamocca:

I've spoken to many who just "assume" it was a cat 5 during landfall. They were surprised to hear it did what it did at cat 3.

Yep. Many people in the Houston area thought Ike was a cat 4. And it was a Cat 2. But the NWS and NHC was VERY clear about Ike's impacts, and were not only precise, but accurate. (same thing happened with Katrina). Just tells you how important it is to listen to the authorities in those type of situations.
Member Since: August 3, 2008 Posts: 16 Comments: 5880
476. yoboi
Quoting jeffs713:
Re: The Katrina talk... I think we're starting to get off-topic. LargoFL is right, and we should stop now, before it gets out of hand.


it's not really off topic it's called being prepared for a hurricane, and if talking about being prepared saves someones life then i think it's well worth it...
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Quoting ilovehurricanes13:
Atlantic. WInd shear over the disturbance has increased some since Tuesday, and is now at the moderate level, 10 - 15 knots thanks Jeff Masters i was right about the wind shear!!
Can you just stop all ready?.Does every post have to be bold or say WOW at the end?.
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Quoting MississippiWx:
80 or 90% at TWO.



Agree. In fact, you could argue it should already be classified a TD IMO.
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Quoting MississippiWx:


Lol.

You caught my mistake before I fixed it. XD
Member Since: July 6, 2010 Posts: 113 Comments: 31895
80 or 90% at TWO.

Member Since: July 15, 2006 Posts: 17 Comments: 10209
Looks like Ernesto wants to be a pest.
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This nrl site has windsat data from earlier today (won't hot link)

http://www.nrl.navy.mil/WindSat/data/wind/display Image.php?img=wndmi_fws_d20120801_lon305E_316E_lat 5N_15N_x868_900_y332_352.wspd.dec.png&className=de scending&mapDate=20120801

Still can't get the NOAA manati site to work
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Re: The Katrina talk... I think we're starting to get off-topic. LargoFL is right, and we should stop now, before it gets out of hand.
Member Since: August 3, 2008 Posts: 16 Comments: 5880
That huge ULL at 45W-28N is in control of the synoptic environment near the wave and contributing to the sheer over the system; that is one large and powerful low and there is not enough separation between it and 99L at the moment.

VW Loop:

Link
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Member Since: June 26, 2012 Posts: 0 Comments: 297
Thats what I said could happen if this remains defined through the Caribbean...

The system could hit the NW CARB under favorable conditions and slow down significantly.
Member Since: June 9, 2007 Posts: 4 Comments: 15880
GFS 12Z at 138 hrs - organizing well south of Cuba
Member Since: June 26, 2012 Posts: 0 Comments: 297
before anyone gets too excited or scared I am sure everyone in this chatroom knows that even before a system is named, computers will go all over the place.

Even when a named system has formed factoring in steering currents, wind patters, ULL's, highs, troughs, etc... even changes paths several times

who knows what is going to happen. It is always a wait and see aproach with tropical systems.
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Quoting IFuSAYso:


NOLA had +/- 3 feet of surge. What if the levies held?
..easy folks, please stop ok
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Quoting TropicalAnalystwx13:
12Z GFS has a ballooning anticyclone in the anticyclone by 126 hours out.


Lol.
Member Since: July 15, 2006 Posts: 17 Comments: 10209
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Quoting 69Viking:


Exactly! Funny how people said they didn't have the means of leaving but after the Hurricane hit the bridge was full of people walke out to get away from the flood waters. Why couldn't they walk out before the storm hit, I know I would have!


NOLA had +/- 3 feet of surge. What if the levies held?
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GFS is stronger (for once) on this run.
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451. yoboi
Quoting 69Viking:


Exactly! Funny how people said they didn't have the means of leaving but after the Hurricane hit the bridge was full of people walke out to get away from the flood waters. Why couldn't they walk out before the storm hit, I know I would have!



alot of people were rescued from roof tops to get to bridge they could not walk......
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Quoting sunlinepr:
Saola appears to me much stronger than just a Category 2 right now.
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1005 mb. south of Jamaica.

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The MJO looks to finally pay us(and the east Pacific) a visit by August 7th. Though the GFS ensembles seem to break it down too fast(which I'm inclined to doubt). The blue Hires GFS appears to have the better track record from the past 1-2 weeks.

I think this'll finality be the kick to get El Nino rollin'.

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Quoting ilovehurricanes13:
wind shear is killing the invest 99L I SEE THE CENTER WITH no t.storms
Give it time...
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Quoting TropicalAnalystwx13:
12Z GFS has a ballooning anticyclone in the Yucatan Channel by 126 hours out.


must be the TUTT
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Quoting Chiggy:
12Z GFS @ 114 hrs - South of Cayman Island!

oh crap
Member Since: June 13, 2009 Posts: 2 Comments: 11774
Quoting ilovehurricanes13:
wind shear is killing the invest 99L I SEE THE CENTER WITH no t.storms


I see t'storms right in the general vicinity. Not looking too bad actually.
Member Since: September 2, 2006 Posts: 110 Comments: 6876
Quoting tropicfreak:


Waters are as hot as a jacuzzi, especially in the NW Caribbean and GOM! A little cooler as you head into the central and eastern Caribbean. Anyone have a TCHP map?


Member Since: July 6, 2010 Posts: 113 Comments: 31895
Quoting catastropheadjuster:


Hydrus, Hey how are ya? I was wondering from all the reading I been doing on the blog for the past few weeks or more, a lot of folks been saying anything that get in the Caribbean will be torn apart, is that still true? I think they where saying the upper level winds where like 15-30 or something like that. Plus with El nino isn't it cooler waters? I may have it all wrong I don't know. I mean some where saying it's gonna be a quite season, i know it only takes one to make it a bad season.

Sheri


Waters are as hot as a jacuzzi, especially in the NW Caribbean and GOM! A little cooler as you head into the central and eastern Caribbean. Anyone have a TCHP map?

Member Since: September 2, 2006 Posts: 110 Comments: 6876
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12Z GFS has a ballooning anticyclone in the Yucatan Channel by 126 hours out.
Member Since: July 6, 2010 Posts: 113 Comments: 31895

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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.