Disturbance 99L more organized; record melting in Austrian Alps
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
Reader Comments
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Or, they used previous events to make the decision to stay. I worked from Bay St Louis to Biloxi MS after Katrina. One of my applicants in Bay St Louis stated he intended to ride the storm out showing me a mark on the stilt/support he made after hurricane Camille at a height of 4 feet. Katrina's high water mark was in the 3rd floor of the home. Tidal surge in the area was estimated at 29 feet. The only reason he evaced was his wife threatened divorce.
Mayor Nagan said "This is the real deal". I also vividly remembering him telling people to keep axes handy, to be honest I could hardly beleive that a situation so bad would occur where you'd need an axe. Hopefully that situation won't occur again, I am pretty sure many lessons were learned, and won't be too quickly forgotten.
Live Recon Data
Not again! Which models? Which system
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
Previously it was N of PR, yesterday S of it
Looks to be moving it more north now.
been thru many canes, if you drive a vehicle make sure ya have several cans of fix-o-flat....if not be prepared to do alot of walking....
With that being said, I was very gung ho on imminent development this morning but looking at the current short-term loops, and particularly the VW loops, the wave is quickly lifting further to the North, prior to consolidation, and getting ripped apart by sheer over it's NW quadrant.
I stand corrected and volunteer to eat my crow (in the short term) at this time.....I need to learn some patience................ :)
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!
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?
I see t'storms right in the general vicinity. Not looking too bad actually.
oh crap
must be the TUTT
I think this'll finality be the kick to get El Nino rollin'.
alot of people were rescued from roof tops to get to bridge they could not walk......
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