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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Did the blog die?
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test
Member Since: February 11, 2012 Posts: 0 Comments: 9760
Quoting KEEPEROFTHEGATE:
a storm as the moon goes full


Higher tides or strange drunken ritual?
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1233. Patrap
Everyone recovered from the Server re-boot?
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What the heck?
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...
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test
Member Since: February 11, 2012 Posts: 0 Comments: 9760
Wow! WU crash! Don't worry I left my spear AtHome. :p
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1227. Bubu77
Moi qui suis en Martinique heureusement que j'ai de l'eau et des lampes à gaz chez moi !!

Trajectoire franchement mauvaise !!

Je craint plus la pluie et les inondations que le vent !!

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Hi Everyone,
I guess I will be lurking a little more now we have something to watch.

Oh no... the possibility of another Ernesto... bummer
He was quite the media circus and then flop back in 2006.





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And... the blog faceplants.
Member Since: August 3, 2008 Posts: 16 Comments: 5891
:)
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THIS IS A DANGEROUS STORM
a track to the Caribbean and then into the gulf of Mexico....
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reboot?
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Quoting ProgressivePulse:
Interesting.

A hurricane stands a much greater chance of being picked up by the trough. So much for our struggling 99L.


You mean TD 5
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THIS IS A DANGEROUS STORM
a track to the Caribbean and then into the gulf of Mexico....
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NHC forecasts TD5 to be a hurricane at 120 hours...


Going to make an updated forecast graphic, NHC and I have the exact same track but they are stronger in the latter half of the period.
Member Since: March 16, 2012 Posts: 127 Comments: 7972
Quoting CybrTeddy:
NHC is forecasting TD5 to become a Hurricane at the end of the forecast period.

About time we get a good Caribbean cruiser, haven't seen one since 2007. Though the idea of a intensifying Category 1 hurricane going through all that TCHP makes me shutter.


I like the intentional misspelling! Double entendre.
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TROPICAL DEPRESSION FIVE DISCUSSION NUMBER 1
NWS NATIONAL HURRICANE CENTER MIAMI FL AL052012
500 PM AST WED AUG 01 2012

DURING THE DAY...VISIBLE SATELLITE IMAGES SHOWED THAT THE LOW-LEVEL
CIRCULATION OF THE LOW PRESSURE SYSTEM TO THE EAST OF
THE WINDWARD ISLANDS HAS BECOME BETTER DEFINED. DEEP CONVECTION
HAS PULSED A BIT...AND IS SOMEWHAT LACKING OVER THE NORTHERN PART
OF THE CIRCULATION. HOWEVER THE SYSTEM HAS NOW ACQUIRED SUFFICIENT
ORGANIZATION TO BE CLASSIFIED AS A TROPICAL DEPRESSION. THE
INITIAL WIND SPEED IS SET AT 30 KT IN ACCORDANCE WITH DVORAK
ESTIMATES FROM TAFB AND SAB. FORECASTING INTENSITY CHANGE IS
ALWAYS A CHALLENGE...AND IS PARTICULARLY TRUE IN THIS CASE.
MODERATE VERTICAL SHEAR...ASSOCIATED WITH A LARGE UPPER-LEVEL LOW
TO THE NORTH OF THE DEPRESSION...IS LIKELY TO AFFECT THE SYSTEM FOR
THE NEXT COUPLE OF DAYS. THUS ONLY SLOW STRENGTHENING IS
ANTICIPATED DURING THE FIRST HALF OF THE FORECAST PERIOD. LATER
ON...THE INTENSITY FORECAST UNCERTAINTY INCREASES. OUR BEST TWO
GLOBAL MODELS ARE AT ODDS AS TO HOW THE SYSTEM WILL EVOLVE AS IT
MOVES OVER THE CARIBBEAN. THE GFS FORECASTS THE UPPER-LEVEL
ENVIRONMENT TO BECOME QUITE CONDUCIVE FOR STRENGTHENING BY THE END
OF THE FORECAST PERIOD...WHEREAS THE ECMWF MODEL SHOWS THE SYSTEM
DEGENERATING INTO A TROPICAL WAVE. THE OFFICIAL FORECAST LEANS
TOWARD TO THE GFS...BUT TIME WILL TELL.

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



FORECAST POSITIONS AND MAX WINDS

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

$$
FORECASTER PASCH/BLAKE
Member Since: July 6, 2010 Posts: 113 Comments: 32877
1214. KEEPEROFTHEGATE (Mod)
looks like the doc will have to do an update
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Kman, keep an eye on TD5 as it's taking the southern route thru the Caribbean.
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The untimate track will shift at some point in the future but this initial one gives me the shudders....Threading the needle towards the Yucatan Channel, and intensifying into a Cat 1 hurriane South of Cuba gives it a lot of room to peak later on down the road if conditions are right.
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Quoting floridaboy14:
reminds me of a dean track. when was the last time we had a cape verde storm enter the carribean? 2007 :O
This isn't classic Cape Verde storm, but it did came from Africa.
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Hurricane over the southern Jamaican coast: impressive.

Waiting on the discussion right now.
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1209. 19N81W
looks like it did finally start that WNW turn...perhaps it will miss the wcarib after all!
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Well I guess we have our answer to the tradewind
effects on TD-5. Projected to attain Hurricane Status
just S. Of Jamaica on Monday.
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1207. ackee
I see the NHC has Hurricane SOUTH of jamaica by monday
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Kman, keep an eye on TD5 as it's taking the southern route thru the Caribbean.
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If TD5 becomes a hurricane and hit Jamaica, media will have a field day since two of the best track stars in Olympics Usain Bolt and Yohan Blake is supposed to runs in couple of events later this week and next week.
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1203. HadesGodWyvern (Mod)
wow!

four cyclones in the world.. That sure is different for once.
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Interesting.

A hurricane stands a much greater chance of being picked up by the trough. So much for our struggling 99L.
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1201. KEEPEROFTHEGATE (Mod)
Quoting Patrap:
keeeper, safe...and scores a run.
a storm as the moon goes full
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Quoting nrtiwlnvragn:
me too I was thinking the same thing.
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Quoting katadman:


Sorry, Mississippi, but you would still rank a distant second to Floodman. Respectfully. lol

I have to give you +1 for that.
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1198. Grothar
Quoting TropicalAnalystwx13:

Yeah...I highly doubt that.


You realize I am making a note of this entry> :)
Member Since: July 17, 2009 Posts: 71 Comments: 27211
Quoting Grothar:


HA. Been there.

But the spear worked. $4,500 below MSRP on a new model with a whopping 8 miles on it.
(then we doubled the price of our trade in... mwahahaha)
Member Since: August 3, 2008 Posts: 16 Comments: 5891
Quoting MississippiWx:


LOL. You still haven't heard of one doing it because I'm not sure I fall under the expert or well-respected blogger category. If you had a smarta## category, I'd be tops.


Sorry, Mississippi, but you would still rank a distant second to Floodman. Respectfully. lol
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Quoting TropicalAnalystwx13:
reminds me of a dean track. when was the last time we had a cape verde storm enter the carribean? 2007 :O
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Just a reminder to everyone to keep it as civil as possible from here on out and to stay on topic. With the TWC crew on board now, and more lurkers and other info seekers who will rely on some of the information posted on here, we don't want to tarnish the hard work Dr. Master's has done with this forum, or, give TWC a reason to eliminate comments on here in the future because of inappropriate comments.

Over and Out.................
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Quoting TropicalAnalystwx13:

Following the consensus pretty closely, it looks like.
Member Since: August 3, 2008 Posts: 16 Comments: 5891
1191. Patrap
keeeper, safe...and scores a run.
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NHC HAS OFFICALLY DECLARED TD5! WAIT AT 5PM EST FOR MORE!


CZC MIATCPAT5 ALL
TTAA00 KNHC DDHHMM

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

...TROPICAL DEPRESSION FORMS IN THE TROPICAL ATLANTIC EAST OF THE
WINDWARD ISLANDS...


SUMMARY OF 500 PM AST...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...12.2N 49.0W
ABOUT 810 MI...1305 KM E OF THE WINDWARD ISLANDS
MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H
PRESENT MOVEMENT...WNW OR 285 DEGREES AT 18 MPH...30 KM/H
MINIMUM CENTRAL PRESSURE...1008 MB...29.77 INCHES


WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY...

THE GOVERNMENT OF BARBADOS HAS ISSUED A TROPICAL STORM WATCH FOR
BARBADOS...ST. VINCENT AND THE GRENADINES...AND DOMINICA.

THE GOVERNMENT OF ST. LUCIA HAS ISSUED A TROPICAL STORM WATCH FOR
ST. LUCIA.

THE GOVERNMENT OF FRANCE HAS ISSUED A TROPICAL STORM WATCH FOR
MARTINIQUE AND GUADELOUPE.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT...

A TROPICAL STORM WATCH IS IN EFFECT FOR...
* BARBADOS...ST. VINCENT AND THE GRENADINES...AND DOMINICA
* ST. LUCIA
* MARTINIQUE AND GUADELOUPE

INTERESTS ELSEWHERE IN THE LESSER ANTILLES SHOULD MONITOR THE
PROGRESS OF THIS SYSTEM.

A TROPICAL STORM WATCH MEANS THAT TROPICAL STORM CONDITIONS ARE
POSSIBLE WITHIN THE WATCH AREA...GENERALLY WITHIN 48 HOURS.

FOR STORM INFORMATION SPECIFIC TO YOUR AREA...PLEASE MONITOR
PRODUCTS ISSUED BY YOUR NATIONAL METEOROLOGICAL SERVICE.


DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
AT 500 PM AST...2100 UTC...THE CENTER OF TROPICAL DEPRESSION FIVE
WAS LOCATED NEAR LATITUDE 12.2 NORTH...LONGITUDE 49.0 WEST. THE
DEPRESSION IS MOVING TOWARD THE WEST-NORTHWEST NEAR 18 MPH...30
KM/H...AND A WEST-NORTHWESTWARD TO WESTWARD MOTION AT ABOUT THE SAME
FORWARD SPEED IS EXPECTED OVER THE NEXT 48 HOURS. ON THE FORECAST
TRACK...THE CENTER OF THE TROPICAL CYCLONE SHOULD BE NEAR THE
WINDWARD ISLANDS ON FRIDAY.

MAXIMUM SUSTAINED WINDS ARE NEAR 35 MPH...55 KM/H...WITH HIGHER
GUSTS. SOME STRENGTHENING IS FORECAST DURING THE NEXT 48 HOURS...
AND THE DEPRESSION COULD BECOME A TROPICAL STORM TONIGHT OR ON
THURSDAY.

ESTIMATED MINIMUM CENTRAL PRESSURE IS 1008 MB...29.77 INCHES.


HAZARDS AFFECTING LAND
----------------------
WIND...TROPICAL STORM CONDITIONS ARE POSSIBLE WITHIN THE WATCH AREA
ON FRIDAY.


NEXT ADVISORY
-------------
NEXT INTERMEDIATE ADVISORY...800 PM AST.
NEXT COMPLETE ADVISORY...1100 PM AST.

$$
FORECASTER PASCH

NNNN


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Jamaica prepare for a hurricane.
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1188. Grothar
Quoting jeffs713:

My spear is currently being sharpened. Had to use it too much yesterday with #$Q^%^#%$^# car salesmen.


HA. Been there.
Member Since: July 17, 2009 Posts: 71 Comments: 27211
Can someone post the advisory for me please, I missed the last 6 or 7.
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1186. KEEPEROFTHEGATE (Mod)
X
Member Since: July 15, 2006 Posts: 178 Comments: 56141

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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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