WunderBlog Archive » Category 6™

Category 6 has moved! See the latest from Dr. Jeff Masters and Bob Henson here.

Disturbance 99L more organized; record melting in Austrian Alps

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

Hurricane Heat

The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

Reader Comments

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

Its not going to south florida.
Looking at short term intensity, the NHC has TD5 becoming a 65 MPH tropical storm before it enters the Caribbean. I'm a little surprised by this forecast considering their conservative background. Our most reliable global models all show a weak tropical storm at this point. Even the aggressive CMC, HWRF, and GFDL only show a moderate TS (40-45 knots) at this point. We'll see how that forecast turns out, personally I'm not expecting a 65 MPH tropical storm to enter the Caribbean, though it is certainly possible.



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
1503. ncstorm
the 18z Nogaps got a two fer one special going on..TD 05 heading to the east coast and another storm heading into the GOM..still running



1504. Grothar
Quoting caribbeantracker01:

do you notice the center at the location it is said to be?


Yes.
1505. Grothar
Quoting rmbjoe1954:


Grothar-

You believe the models will go northward?


Expect the next flare-up of convection to the West of the Center in the next few hours.
Severe thunderstorm warning here in Palm Beach county...... Looks pretty scary to my west...
Quoting Grothar:
Models are too far South.

Not liking the possible "Gulf Idea" gro?
lol
Quoting HurricaneDean07:

Its not going to south florida.


Actually, based on the wnw movement if it continues it will go over or just north of PR and the Islands.
1509. nigel20
Barbados Met Service

HERE 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
Quoting Grothar:


Expect the next flare-up of convection to the West of the Center in the next few hours.
It's already occurring lol
wind shear is 30kt right now on TD 5


NHC forcast track has TD5 centre passing 60miles to the N of Barbados Friday evening.

but 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?
Quoting Hurricanes305:


Actually, based on the wnw movement if it continues it will go over or just north of PR and the Islands.

"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.
Quoting Hurricanes305:


Actually, based on the wnw movement if it continues it will go over or just north of PR and the Islands.
305........Fact or a guess 305?
Quoting bajelayman2:
NHC forcast track has TD5 centre passing 60miles to the N of Barbados Friday evening.

but 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?
center relocation!
Quoting bajelayman2:
NHC forcast track has TD5 centre passing 60miles to the N of Barbados Friday evening.

but 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?

The NHC stated that theyre considering the GFS forecast, much more than the other models- at this point.
Quoting Grothar:


Expect the next flare-up of convection to the West of the Center in the next few hours.


Yea its possible it could be enough to just slightly cover the northern part of the center.
JeffMasters has created a new entry.
Quoting TropicalAnalystwx13:

"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.

It appears it has already began the bend back toward the west.
+2
Quoting stormchaser19:
the ensembles birng this to CA that meand it would be weaker to have that track right?
Listen to me everyone open this Link and turn on tropical forecast points and look at the deepest convection!!!
Quoting PalmBeachWeather:
305........Fact or a guess 305?


???
Be advised, 18Z GFS is running.

150hr 500mbar vorticity:

05L/TD/E/CX
MARK
11.95N/48.18W
Quoting TomTaylor:
Looking at short term intensity, the NHC has TD5 becoming a 65 MPH tropical storm before it enters the Caribbean. I'm a little surprised by this forecast considering their conservative background. Our most reliable global models all show a weak tropical storm at this point. Even the aggressive CMC, HWRF, and GFDL only show a moderate TS (40-45 knots) at this point. We'll see how that forecast turns out, personally I'm not expecting a 65 MPH tropical storm to enter the Caribbean, though it is certainly possible.



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


Yeah, 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
x
Not that any of it really matters cause it's all way out there...

But 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.
Quoting nofailsafe:
Be advised, 18Z GFS is running.

150hr 500mbar vorticity:




Still showing the scenario from earlier wrt the ULL enhancing the outflow pattern.
Quoting mcluvincane:
What happened to the el nino trade winds that were supposed to rip thus thing apart once it got into the Caribbean



Ummmmm...........it hasn't made it to the Caribbean yet?
Quoting ackee:
I am the huge fan of THE Ecmwf ,however this seasons it just seem like The Gfs is leading the other models by far Debby was good example of this and if the GFS forcast pan out for pre EARNESTO it would be another conformation as to which model is on top this seasons


I 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.
Quoting ProgressivePulse:


That is the T Wave by DR. NAM has been showing weak development for a couple days now. Could be a fly in the ointment per-se in eroding the western flank of the Atl-Ridge and allowing a NW to N turn in time with TD5.



Sounds good, is it viable that a weak T Wave can do that to the High?
Quoting SFLWeatherman:
all of the Computer Model all going to go up to S FL at 8PM


Why do you say that?
Quoting Articuno:
I predict this will go through Jamaica and the Western Tip of Cuba.

EDIT: Meant Western.
Quoting Articuno:
I predict this will go through Jamaica and the Western Tip of Cuba.

EDIT: Meant Western.
yes
00Z GFS has started.

500mb Vorticity

Initialization: