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 TomTaylor:
Shear is part of it. TPW also shows a fair amount of dry air to the north and ahead of the depression. That same ULL causing the shear is also preventing significant outflow or divergence to the NW which can be seen on water vapor loops.


Remember that is Dmin time.
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1485. nigel20
05L

Saola
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If you make the assumption that the four record pace storms earlier this year were just a coincidence, then this season is pretty much on pace with 2006.

That year the number 4 storm (Chris) lasted from July 31 - August 5th. Debby didn't form for another three weeks... the only difference is that we're one storm up right now due to the record start, but otherwise they're pretty similar so far and in the final season forecast.
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Seeing a turn back to the west in the last 3 frames of the floater visible loop.

Not really meaningful cept it puts us under the convection.
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Quoting MississippiWx:
There have been very few if any outflow boundaries shooting away from TD5. Makes me think the asymmetrical appearance is due to shear after all.
Shear is part of it. TPW also shows a fair amount of dry air to the north and ahead of the depression. That same ULL causing the shear is also preventing significant outflow or divergence to the NW which can be seen on water vapor loops.
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It at 12.2N
Quoting RussianWinter:


Whoa, does that mean that center is going under convection?
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Quoting RussianWinter:


Whoa, does that mean that center is going under convection?



Thats what it looks like at this time yes.
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I say TD5 COC is right now located at 12.3N 49.2W
Member Since: June 13, 2009 Posts: 2 Comments: 10999
Quoting KEEPEROFTHEGATE:
05L/TD/E/CX
MARK
11.95N/48.18W


Whoa, does that mean that center is going under convection?
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Quoting MississippiWx:
There have been very few if any outflow boundaries shooting away from TD5. Makes me think the asymmetrical appearance is due to shear after all.



Mostly due to forward motion. Its moving pretty fast right now and that is disrupting the mid level circulation.

New convective burst to the east of the COC looks nice however, its not all that cold but it is a pretty robust tstorm complex.
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Is anybody missing Thursday day forecast from their forecast page? I sure am... look here: http://classic.wunderground.com/US/TN/Knoxville/K TYS.html
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WHY!! lol jk
Quoting PalmBeachWeather:
SFL....... Calm down
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Quoting wxchaser97:
But that could cause havoc and destruction for others.


Sometimes, sacrifices have to be made.

The moisture from a large hurricane could bring enough rain to to save the crops and that alone may offset the cost from the disaster.



Or there could be too much rain and that won't be good either..
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Another stick'in poll...
Member Since: August 14, 2010 Posts: 10 Comments: 16406
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There have been very few if any outflow boundaries shooting away from TD5. Makes me think the asymmetrical appearance is due to shear after all.
Member Since: July 15, 2006 Posts: 17 Comments: 10159
Quoting SFLWeatherman:
Q. TD 5 go to S FL how big will it be??
A. TD
B. TS
c. CAT 1
D. CAT 2
E. CAT 3
F. CAT 4
G. CAT 5
H. CAT 6 lol jk


B)STRONG
Member Since: June 20, 2012 Posts: 0 Comments: 2150
Quoting MississippiWx:
A lot of the models still open TD5 back into a wave once in the Eastern Caribbean. It will be interesting to watch and see if that happens or if it can strengthen enough to prohibit any deterioration of the center.



Well thats in response to shear, both GFDL and HWREF really want to drop the system at this point but in all honesty I disagree with that.

I am still biased toward the GFS, it seems to have a really quite reasonable forecast scenerio at this point both in terms of shear interaction and in terms of track, and it squares well with alot of the dynamical models.


It all squares well with what I am physically seeing in terms of ULL/Shear, Trough development over the continental US, and the existing ridging setup we are working within.

NHC seems to think so too they are pretty close to it.
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Quoting SFLWeatherman:
Q. TD 5 go to S FL how big will it be??
A. TD
B. TS
c. CAT 1
D. CAT 2
E. CAT 3
F. CAT 4
G. CAT 5
H. CAT 6 lol jk
SFL....... Calm down
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1465. KEEPEROFTHEGATE (Mod)
05L/TD/E/CX
MARK
11.95N/48.18W
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Quoting PalmBeachWeather:
Carolina....Most are just "Following the Leader" They have no idea, but it kinda looks intelligent.NOT


Haha thanks for the reply. I kind of get that impression around here sometimes.... unfortunately that makes it awfully confusing for an admitted amateur (or really just a 'weather enthusiast'- me) who is just trying to learn. Either way, this looks like it'll be an interesting storm to follow and I look forward to hearing everyones opinions on when where how and why..... since this one isnt heading my way I'll just sit back and enjoy the show (and wish everyone in its path safety!)
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But the GFS is going up BIG time!!!
Quoting PalmBeachWeather:
SFL.....Remember this....Not all models are reliable... Most of the ones you are looking at are what I stated... Learn the models and which ones you need to look at.
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Quoting SFLWeatherman:
Q. TD 5 go to S FL how big will it be??
A. TD
B. TS
c. CAT 1
D. CAT 2
E. CAT 3
F. CAT 4
G. CAT 5
H. CAT 6 lol jk




TS.


Shear and land interaction.
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A lot of the models still open TD5 back into a wave once in the Eastern Caribbean. It will be interesting to watch and see if that happens or if it can strengthen enough to prohibit any deterioration of the center.
Member Since: July 15, 2006 Posts: 17 Comments: 10159
all of the Computer Model all going to go up to S FL at 8PM
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Q. TD 5 go to S FL how big will it be??
A. TD
B. TS
c. CAT 1
D. CAT 2
E. CAT 3
F. CAT 4
G. CAT 5
H. CAT 6 lol jk
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Twitter:

wunderground Trop. Depression Five is headed toward the Caribbean, Gulf/Florida interests should monitor: wxug.us/dfgd
Read more at http://www.wunderground.com/tropical/#cK1I7Vbj8jYl zIs4.99
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Quoting SFLWeatherman:
all of the Computer Model all going to up to S FL at 8PM
SFL.....Remember this....Not all models are reliable... Most of the ones you are looking at are what I stated... Learn the models and which ones you need to look at.
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Quoting wxchaser97:
I agree with that statement, my track/intensity forecast isn't as off as I thought it might be.




An interesting note on that, at the end of the forecast period I found this for 850-200mb shear on the GFS:


Link


What this shows is a ULL to the northwest of the system, moving west. But the ULL would be in a such a position that it would actual be enhancing the outflow pattern of the system, which is shown to be quite broad on the GFS by this point it time.


That given the location the COC would be in at that time would be conducive for RI.

But that is at the end of the fcast period and it is of course just one model, although I think perhaps ngps and CMC are too overzealous in their prediction of the strength of the trough currently moving off the east coast.
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The NHC does NOT "choose" a width for the forecast cone....


Definition of the NHC Track Forecast Cone:

The cone represents the probable track of the center of a tropical cyclone, and is formed by enclosing the area swept out by a set of circles (not shown) along the forecast track (at 12, 24, 36 hours, etc). The size of each circle is set so that two-thirds of historical official forecast errors over a 5-year sample fall within the circle. The circle radii defining the cones in 2011 for the Atlantic and eastern North Pacific basins are given in the table seen at:


http://www.nhc.noaa.gov/aboutcone.shtml
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I will see everyone in the am. Figures that August would start out with a potential bang in the first week; some of the research papers have been talking about potential GW impacts on hurricane season and the timing of the CV canes. I hope this is not a harbringer of what we might expect in future seasons (an early start to the Cape Verde season)......

Stay safe and pay close attention to the NHC advisories for our friends in the Caribbean which may issue between now and tomorrow morning............WW.
Member Since: August 8, 2006 Posts: 0 Comments: 8782
Ernesto do you have to do this to us :(?.I'm still waiting on Isaac.
Member Since: August 14, 2010 Posts: 10 Comments: 16406
1451. nigel20
Quoting TropicalAnalystwx13:

Mother Nature knew it was their special day and wanted to send them a gift.

The South African president, Jacob Gedleyihlekisa Zuma may have the cancel is trip to Jamaica depending on the track and intensity of TD5.
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all of the Computer Model all going to go up to S FL at 8PM
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Tonight's model runs should have a good grasp on starting location/intensity and provide a better forecast since the system is a TD now.
Member Since: March 16, 2012 Posts: 127 Comments: 7927
Quoting SFLWeatherman:
Q. TD 5 go to S FL how big will it be??
A. TD
B. TS
c. CAT 1
D. CAT 2
E. CAT 3
F. CAT 4
G. CAT 5
H. CAT 6 lol jk


E, maybe even F... lol H!
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Quoting wxchaser97:
Last bits of visible light on TD5.


the center is relocating
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Quoting CarolinaHurricanes87:


The problem with that is... intensity of a storm influences its track. If they are completely unsure about intensity, I don't know how they can be so confident in its track. I am surprised they didn't take a conservative route and at least make the cone a bit wider.

For days several people have been saying anything that enters the Caribbean is going to die... the NHC forecast seems to show that they believe otherwise.

Why do people think this storm will die in the Caribbean, OR, what has changed so that TD 5 is no longer expected to weaken/die there?

The strong trade winds that we're originally forecast to rip any circulation TD #5 had once it entered the Caribbean Sea have failed to materialize because the tropical wave ahead of the storm disrupted the flow.
Member Since: July 6, 2010 Posts: 113 Comments: 31438
West Boynton and Delray Beach getting hammered.... I am on the coast but getting very dark here.
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Quoting DocBen:


I like it so far ... hoping it will go through the Yucatan Chennel and head through TX to Kansas. This is what it will take to put a dent in our drought.


We aint taking a major hit on the chin just for you guys getting drought relief, El Nino this winter will take care of that
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GFS already wrong on its initial frame has it at 1012 mb and not closed
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Quoting DocBen:


I like it so far ... hoping it will go through the Yucatan Chennel and head through TX to Kansas. This is what it will take to put a dent in our drought.
But that could cause havoc and destruction for others.
Member Since: March 16, 2012 Posts: 127 Comments: 7927
Q. TD 5 go to S FL how big will it be??
A. TD
B. TS
c. CAT 1
D. CAT 2
E. CAT 3
F. CAT 4
G. CAT 5
H. CAT 6 lol jk
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Last bits of visible light on TD5.
Member Since: March 16, 2012 Posts: 127 Comments: 7927
Quoting CarolinaHurricanes87:


The problem with that is... intensity of a storm influences its track. If they are completely unsure about intensity, I don't know how they can be so confident in its track. I am surprised they didn't take a conservative route and at least make the cone a bit wider.

For days several people have been saying anything that enters the Caribbean is going to die... the NHC forecast seems to show that they believe otherwise.

Why do people think this storm will die in the Caribbean, OR, what has changed so that TD 5 is no longer expected to weaken/die there?
Carolina....Most are just "Following the Leader" They have no idea, but it kinda looks intelligent.NOT
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1437. DocBen
Quoting nigel20:
Good evening everyone...i see that we now have TD5. I'm not liking this track at all...it may/should change.


I like it so far ... hoping it will go through the Yucatan Chennel and head through TX to Kansas. This is what it will take to put a dent in our drought.
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Quoting Patrap:
Plan of the Day


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.



II. PACIFIC REQUIREMENTS

1. NEGATIVE RECONNAISSANCE REQUIREMENTS.

2. OUTLOOK FOR SUCCEEDING DAY.....NEGATIVE.


Boy I tell ya this they want to keep a close "Eye" on this one don't they....
Quoting MississippiWx:
Hey, StormTracker. I figured you would like this. From the NWS Mobile, AL office:

THE WEAKNESS BETWEEN THE UPPER RIDGE OVER TEXAS AND THE UPPER RIDGE
OVER THE WEST ATLANTIC WILL CONTINUE THROUGH AT LEAST EARLY NEXT
WEEK...WITH GUIDANCE ATTEMPTING TO STRENGTHEN THE RIDGE BY THE MIDDLE
OF NEXT WEEK. THERE IS A LOT OF UNCERTAINTY REGARDING HOW STRONG THE
RIDGE WILL BUILD IN AS THE AFOREMENTIONED WEAKNESS HAS BEEN A
PERSISTENT FEATURE OVER OUR AREA OVER THE LAST SEVERAL WEEKS.
DID NOT
DEVIATE FROM THE PREVIOUS FORECAST...WHICH SHOWS LITTLE CHANGE IN
TEMPS AND CONTINUED 30-40 POPS EACH DAY.

TROPICAL DEPRESSION FIVE HAS DEVELOPED EAST OF THE WINDWARD ISLANDS
AND IS FORECAST TO MOVE WEST INTO THE CENTRAL CARIBBEAN BY MONDAY.
THIS SYSTEM WILL CERTAINLY HAVE NO IMPACT OVER US THROUGH THE NEXT 7
DAYS...BUT WILL BEAR WATCHING AS IT APPROACHES THE YUCATAN BY THE
MIDDLE-END OF NEXT WEEK. THE ULTIMATE DIRECTION OF THE SYSTEM WILL
HINGE ON HOW MUCH HEIGHTS BUILD OVER THE CENTRAL GULF/SE STATE LATE
NEXT WEEK.
PLENTY OF TIME TO MONITOR. 34/JFB
and I "Donot" like the way they say Yucatan by Mid to late next week :o(
just Saying>>>>

Taco :o)
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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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