About Jeff Masters
Cat 6 lead authors: WU cofounder Dr. Jeff Masters (right), who flew w/NOAA Hurricane Hunters 1986-1990, & WU meteorologist Bob Henson, @bhensonweather
By: Dr. Jeff Masters , 2:02 PM GMT on August 01, 2012
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
The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.
Cat 6 lead authors: WU cofounder Dr. Jeff Masters (right), who flew w/NOAA Hurricane Hunters 1986-1990, & WU meteorologist Bob Henson, @bhensonweather
1536. nofailsafe
3:33 AM GMT on August 02, 2012500mb Vorticity
Initialization:
1534. seer2012
12:38 AM GMT on August 02, 20121533. HurricaneHunterJoe
12:19 AM GMT on August 02, 2012Why do you say that?
1532. HurricaneHunterJoe
12:11 AM GMT on August 02, 2012Sounds good, is it viable that a weak T Wave can do that to the High?
1531. HurricaneHunterJoe
11:53 PM GMT on August 01, 2012I remember about a week ago looking at the extended GFS and it had a TS/Minimal Hurricane in close proximity to the SW Florida coast. Like it did with Debby,it had Debby at long ranges and then lost it,only to have it return to the location it was in before. Not saying it is going to happen again,but food for thought.
1530. HurricaneHunterJoe
11:40 PM GMT on August 01, 2012Ummmmm...........it hasn't made it to the Caribbean yet?
1529. DataNerd
11:34 PM GMT on August 01, 2012Still showing the scenario from earlier wrt the ULL enhancing the outflow pattern.
1528. StormJunkie
10:49 PM GMT on August 01, 2012But GFS has it slamming the Yuc Pen and also shows a large system in the middle of the Atlantic at the end of the run.
1527. TomTaylor
10:35 PM GMT on August 01, 20121526. stormchaser19
10:28 PM GMT on August 01, 2012Yeah, and the GFS is develops the system but when is getting out of carribean,the HWRF is my guiadence rigth now...and i think will have a shot about 12-24 hours before reaches the windward island, right now the shear in the north is stopping any intensification
1525. KEEPEROFTHEGATE (Mod)
10:28 PM GMT on August 01, 2012MARK
11.95N/48.18W
1524. nofailsafe
10:27 PM GMT on August 01, 2012150hr 500mbar vorticity:
1523. Hurricanes305
10:25 PM GMT on August 01, 2012???
1522. caribbeantracker01
10:24 PM GMT on August 01, 20121521. allancalderini
10:23 PM GMT on August 01, 20121520. HurricaneDean07
10:23 PM GMT on August 01, 2012It appears it has already began the bend back toward the west.
+2
1519. WunderAlertBot (Admin)
10:23 PM GMT on August 01, 20121518. Hurricanes305
10:21 PM GMT on August 01, 2012Yea its possible it could be enough to just slightly cover the northern part of the center.
1517. HurricaneDean07
10:21 PM GMT on August 01, 2012The NHC stated that theyre considering the GFS forecast, much more than the other models- at this point.
1516. caribbeantracker01
10:21 PM GMT on August 01, 20121515. PalmBeachWeather
10:20 PM GMT on August 01, 20121514. Stormchaser121
10:20 PM GMT on August 01, 20121513. TropicalAnalystwx13
10:19 PM GMT on August 01, 2012"Actually", it is expected to turn back towards the west tonight if it hasn't already. It should end up in the West Caribbean in 5 days.
1512. bajelayman2
10:18 PM GMT on August 01, 2012but the GFS has the centre passing bang on the South coast of Barbados.
While the NHC has a great track record in the past several years, I would not discount the GFS.
However, as strengthening occurs and it pulls from ITCZ, it naturally will rise, so the NHC must have taken that inot account.
Question is, does the GFS see something that the rest do not?
1511. Tazmanian
10:18 PM GMT on August 01, 20121510. TomTaylor
10:18 PM GMT on August 01, 20121509. nigel20
10:18 PM GMT on August 01, 2012HERE IS ADVISORY #1 FOR BARBADOS ON TROPICAL DEPRESSION #5
Issued by
The Barbados Meteorological Services
at 5:00 p.m on Wednesday, 1st August, 2012.
THE LOW PRESSURE CENTER IN THE MID-ATLANTIC HAS STRENGTHENED TO TROPICAL DEPRESSION #5.
��A TROPICAL STORM-WATCH IS NOW IN EFFECT FOR BARBADOS.
A TROPICAL STORM WATCH MEANS THAT TROPICAL STORM CONDITIONS ARE LIKELY TO AFFECT THE ISLAND, IN THIS CASE WITHIN 36 hours.
AT 5:00 PM AST...2100 UTC... THE CENTER OF TROPICAL DEPRESSION #5 WAS LOCATED NEAR LATITUDE 12.2 NORTH...LONGITUDE 49.0 WEST OR ABOUT 700 MILES...1130 KM TO EAST-SOUTHEAST OF BARBADOS.
THE DEPRESSION IS MOVING TOWARD THE WEST-NORTHWEST AT NEAR 18 MPH...30 KM/HR...
ON THIS PRESENT TRACK THE CENTER OF THE SYSTEM IS EXPECTED TO PASS JUST NORTH OF BARBADOS EARLY ON FRIDAY MORNING...AND MOVE ACROSS THE CENTRAL LESEER ANTILLES LATE FRIDAY EVENING.
MAXIMUM SUSTAINED WINDS ARE NEAR 35 MPH...55KM/HR...WITH HIGHER GUSTS. SOME STRENGTHENING IS FORECAST DURING THE NEXT 48 HOURS.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 1008 MB...29.77 INCHES.
HAZARDS AFFECTING LAND
REGARDLESS OF THE FACT THAT THE STRONGEST WINDS ASSOCIATED WITH THE SYSTEM ARE EXPECTED TO OCCUR NORTH OF THE CENTER WE STILL ANTICIPATE SIGNIFICANT RAINFALL AND SQUALLY CONDITIONS ACROSS BARBADOS.
SEAS...ABOVE-NORMAL SWELLS WILL RESULT BY AS MUCH AS 9 TO 12 FEET ABOVE NORMAL TIDE LEVELS MAINLY ALONG THE EASTERN COAST OF BARBADOS.
REPEATING THE 5:00 PM POSITION...12.2 N..49.0 W.
MOVEMENT TOWARD...WEST-NORTHWEST NEAR 18 MPH.
MAXIMUM SUSTAINED WINDS... 35 MPH.
MINIMUM CENTRAL PRESSURE... 1008 MB.
THE NEXT ADVISORY WILL BE ISSUED AT 5:00 A.M TOMORROW.
H.LOVELL
Director (Ag) B.M.S
Meteorologist: Hampden Lovell
1508. Hurricanes305
10:18 PM GMT on August 01, 2012Actually, based on the wnw movement if it continues it will go over or just north of PR and the Islands.
1507. HurricaneDean07
10:18 PM GMT on August 01, 2012Not liking the possible "Gulf Idea" gro?
lol
1506. PalmBeachWeather
10:17 PM GMT on August 01, 20121505. Grothar
10:17 PM GMT on August 01, 2012Expect the next flare-up of convection to the West of the Center in the next few hours.
1504. Grothar
10:15 PM GMT on August 01, 2012Yes.
1503. ncstorm
10:15 PM GMT on August 01, 20121502. TomTaylor
10:15 PM GMT on August 01, 2012INIT 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
1501. HurricaneDean07
10:14 PM GMT on August 01, 2012Its not going to south florida.
1500. rmbjoe1954
10:14 PM GMT on August 01, 2012Grothar-
You believe the models will go northward?
1499. stormchaser19
10:13 PM GMT on August 01, 20121498. TomTaylor
10:13 PM GMT on August 01, 20121497. KEEPEROFTHEGATE (Mod)
10:12 PM GMT on August 01, 2012do you think they will listen to people like us
naw but they will learn
1496. caribbeantracker01
10:11 PM GMT on August 01, 2012do you notice the center at the location it is said to be?
1495. Articuno
10:11 PM GMT on August 01, 2012EDIT: Meant Western.
1494. washingtonian115
10:11 PM GMT on August 01, 20121493. gulfbreeze
10:10 PM GMT on August 01, 20121492. Grothar
10:10 PM GMT on August 01, 20121491. MississippiWx
10:10 PM GMT on August 01, 20121490. Bluestorm5
10:08 PM GMT on August 01, 20121489. MississippiWx
10:08 PM GMT on August 01, 2012Lack of divergence is probably part of its issue, but you can see the appearance is elongated to the northeast now. It didn't have that appearance this morning. Outflow from convection in front of the storm is also imparting a bit of shear. Believe it's going to have these hurdles until it hits the islands at least. Slow strengthening is a good call until that point.
1488. Stormchaser2007
10:06 PM GMT on August 01, 2012Looks like the usual bunch of B.S-casters are out this evening.
I'll be back when it's bed time for the kiddies.
1487. DataNerd
10:05 PM GMT on August 01, 2012I would tend to agree with this. Watched the 06 season very carefully myself as 2005 had really traumatized alot of us on the gulf coast.
That season was a nightmare, so we were very concerned in early 06, but as the shear pattern became more well developed and there was a lack of african waves, we calmed down.
Differences here:
1. High pressure system pattern is far stronger and more well established over the U.S. mainland.
2. Pattern favors low trade wind based shear over the Carribean despite it being an el nino year.
3. SSTs are warmer.
4. ITCZ/African waves are more active by far.
So its similar but not exactly the same. 2006 was quite tame.
1486. Tropicsweatherpr
10:05 PM GMT on August 01, 2012Remember that is Dmin time.