African tropical wave 99L has potential to develop

By: Dr. Jeff Masters , 3:10 PM GMT on July 30, 2012

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The first African tropical wave of 2012 with a potential to develop is Invest 99L, located in the Eastern Atlantic near 9°N 36°W, midway between the Lesser Antilles Islands and the coast of Africa. Visible satellite loops show a large area of the surrounding atmosphere has a pronounced counter-clockwise spin, though there is no surface circulation. The disturbance's heavy thunderstorm activity is pretty sparse, but appears to be slowly increasing. 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 lies well to the north of 99L. WInd shear over the disturbance is a light 5 - 10 knots, and ocean temperatures are 28°C, (82°F) which is well above the 26.5°C (80°F) threshold typically needed to allow formation of a tropical depression.


Figure 1. Morning satellite image of Invest 99L.

Forecast for 99L
Wind shear is expected to remain light for the next five days, and ocean temperatures will remain near 28°C, according to the 8 am EDT run of the SHIPS model. The disturbance is at 9°N, which is close enough to the Equator that the storm will have some difficultly getting spinning. Most of the models are showing some slow development of 99L, with the storm reaching the Lesser Antilles Islands on Saturday, August 3. NHC gave 99L a 20% chance of developing into a tropical depression by Wednesday morning. I expect the storm will have trouble with dry air at times this week as it crosses the Atlantic, but I give 99L a 50% chance of eventually developing into Tropical Storm Ernesto sometime in the next ten days. 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 night. The long-range fate of 99L is uncertain, but a trough of low pressure is expected to be present over the Eastern U.S. early next week, which would be capable of turning 99L more to the northwest.

Hot in the Central U.S.
The heat in America's heartland continued on Sunday, with Wichita, KS hitting 111°F, just 3° short of their all-time hottest temperature of 114° set on 8/12/1936. Other notable highs on Sunday:

111° Coffeyville, KS
111° Winfield, KS
110° Chanute, KS
110° Parsons, KS
109° Joplin, MO (all-time record is 115° on July 14, 1954)

The low temperature in Tulsa, Oklahoma this Monday morning dropped to only 88°F. This is the all-time warmest low temperature in the city since record keeping began in 1905. The previous record warmest minimum temperature was 87°F set on August 2, 2011 and July 16, 1980. The high in Tulsa Monday - Wednesday is expected to reach 110° - 111°, close to the city's all-time hottest temperature of 115° set on August 10, 1936.

Jeff Masters

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Here is the am NCEP Caribbean discussion. Discussion as to the wave going through the Antilles right now but no mention yet as to the 20% wave:

TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
722 AM EDT TUE JUL 31 2012

PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI. TROPICAL WAVE CONTINUES PROGRESSING ACROSS THE EASTERN CARIBBEAN AND EXTENDS NOW TO THE ACROSS EXTREME EASTERN DOMINICAN REPUBLIC. WIDESPREAD PERSISTENT DEEP CONVECTION ASSOCIATED WITH THIS WAVE HAS ENHANCED VENTILATION EVEN MORE...WHICH CONTINUES VENTING DEEP CONVECTION BEHIND THE WAVE. TWO AREAS OF ORGANIZED CONVECTION HAVE DEVELOPED. ONE TO THE SOUTH OF PASAJE DE LA MONA...AND ANOTHER ACROSS SAN MAARTEN-ANGUILLA INTO THE EASTERN USVI.

MODELS CONTINUE SHOWING ACTIVE CONVECTION PERSISTING OVER THE ISLANDS THROUGH 48-60 HRS...AND SUBSIDENCE INVERSION ESTABLISHING BY THAN AT 800-825 HPA. THE UKMET HAS A DRIEST SOLUTION WITH MAXIMA IN THE ORDER OF 30-35MM/DAY FOR DAY 1...WHILE THE EUROPEAN MODEL HAS TOTALS OF 40-50MM/DAY AND THE GFS 55-65 MM/DAY. FROM THE HIGH RESOLUTION MODELS...THE HRWRF IS SHOWING MORE REASONABLE PRECIPITATION AMOUNTS THAN THE WRF-NMM...AS THE LATTER HAS A VERY WET SOLUTION WITH TOTALS APPROACHING 200MM/DAY. BASED ON MODEL TENDENCY AND CURRENT CONVECTIVE DEVELOPMENT...WE ARE LEANING TOWARDS MAXIMUM ACCUMULATIONS IN THE ORDER OF 50-75MM/DAY WITH HEAVIEST/MOST PERSISTENT CONVECTION ACROSS THE USVI AND EASTERN/SOUTHERN COASTS OF PUERTO RICO WHERE A FEW LOCATIONS COULD APPROACH OR EXCEED 100MM/DAY. CONVECTION COVERAGE WILL GRADUALLY DECREASE DURING THE DAY ON WEDNESDAY...TO LIMIT AGAIN TO SHALLOW DURING THE DAY ON THURSDAY.

CANTILLO...IDEAM (COLOMBIA)
GALVEZ...HPC (USA)


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Good morning guys, here in Dominican Republic in the north part on the country where i live, is raining heavily and a lot of thunders,
the wave is near the country right now

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Quoting weathermanwannabe:
Good Morning. Lots of tropical issues out there and not sure if this has been posted yet but here is this am's ENSO Outlook from the Aussie Met Office:

Pacific remains close to El Niño thresholds
Issued on Tuesday 31 July | Product Code IDCKGEWWOO

Most climate indicators in the tropical Pacific Ocean remain at values near the threshold of an El Niño event. Although indicators such as the Southern Oscillation Index (SOI) and trade winds are less El Niño-like than they were a month ago, ocean surface temperatures continue to show a pattern, and in some places values, typical of the development stage of an El Niño. Climate models suggest weak El Niño conditions are likely to be reached some time in late winter or spring. No climate models suggest a return to La Niña conditions.

During El Niño events, large parts of eastern Australia are typically drier than normal during winter and spring, while southern Australian daytime temperatures tend to be warmer. However, El Niño does not guarantee widespread dry conditions.

The Indian Ocean Dipole (IOD) is currently neutral. Outlooks from the Bureau’s climate model indicate neutral to weak positive IOD conditions are likely through winter and spring.

Weekly sea surface temperatures:
Warm sea-surface temperature (SST) anomalies in the central tropical Pacific have increased slightly when compared to two weeks ago. The SST anomaly map for the week ending 29 July shows warm anomalies extend along the equator east of about 170°W, reaching more than 1 °C warmer than usual in parts of the eastern tropical Pacific. Tropical SSTs in the western half of the Pacific are near average for this time of the year.

Climate Models:
Most international climate models surveyed by the Bureau predict that the equatorial Pacific Ocean is likely to remain near El Niño thresholds throughout late winter and early spring 2012. Some models continue to predict the chance of an El Niño developing before the end of the year. However, several of the surveyed models continue to exhibit a degree of spread in their forecasts, indicating that a level of uncertainty remains.



Looking like a weak to moderate El Nino going into the heart of the Atlantic Season at the moment.

Link


Thanks!
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12z Best Track.

AL, 99, 2012073112, , BEST, 0, 93N, 396W, 20, 1010, DB
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Quoting Neapolitan:
Where's Tulsa on that list? The city reached -12 on February 10. That's cold...but nowhere near -31.


I'm sorry near Tulsa. Those readings were some of the coldest in history. Doc posted this on his blog last year.
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Up to 1.0.

31/1145 UTC 9.2N 40.6W T1.0/1.0 99L -- Atlantic
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Good Morning. Lots of tropical issues out there and not sure if this has been posted yet but here is this am's ENSO Outlook from the Aussie Met Office:

Pacific remains close to El Niño thresholds
Issued on Tuesday 31 July | Product Code IDCKGEWWOO

Most climate indicators in the tropical Pacific Ocean remain at values near the threshold of an El Niño event. Although indicators such as the Southern Oscillation Index (SOI) and trade winds are less El Niño-like than they were a month ago, ocean surface temperatures continue to show a pattern, and in some places values, typical of the development stage of an El Niño. Climate models suggest weak El Niño conditions are likely to be reached some time in late winter or spring. No climate models suggest a return to La Niña conditions.

During El Niño events, large parts of eastern Australia are typically drier than normal during winter and spring, while southern Australian daytime temperatures tend to be warmer. However, El Niño does not guarantee widespread dry conditions.

The Indian Ocean Dipole (IOD) is currently neutral. Outlooks from the Bureau’s climate model indicate neutral to weak positive IOD conditions are likely through winter and spring.

Weekly sea surface temperatures:
Warm sea-surface temperature (SST) anomalies in the central tropical Pacific have increased slightly when compared to two weeks ago. The SST anomaly map for the week ending 29 July shows warm anomalies extend along the equator east of about 170°W, reaching more than 1 °C warmer than usual in parts of the eastern tropical Pacific. Tropical SSTs in the western half of the Pacific are near average for this time of the year.

Climate Models:
Most international climate models surveyed by the Bureau predict that the equatorial Pacific Ocean is likely to remain near El Niño thresholds throughout late winter and early spring 2012. Some models continue to predict the chance of an El Niño developing before the end of the year. However, several of the surveyed models continue to exhibit a degree of spread in their forecasts, indicating that a level of uncertainty remains.



Looking like a weak to moderate El Nino going into the heart of the Atlantic Season at the moment.

Link
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Quoting osuwxguynew:


Agreed. 850, 700 and 500 mb vorticity slowly strengthening and vertically stacked in a low shear, moist environment.

Good amount of convergence, though linear due to it still being imbedded in the ITCZ.

I think another night of Dmax and we might be pretty close to a TD tomorrow morning. Should see some quick flow through the eastern Caribbean which won't allow much, if any, strengthening. Then it all comes down to land interaction. Way too early to speculate...


I just ran some 925 mb models...what quick flow? Looks to be about 15 kts in about 6-7 days.

Link
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Quoting StormTracker2K:


Wrong infact this was on Doc's blog back last February.

Oklahoma Shatters All-Time Low Temperature Record
Oklahoma Shatters All-Time Low Temperature Record
Gary McManus
Associate State Climatologist
Oklahoma Climatological Survey
February 10, 2011

The Oklahoma Mesonet station at Nowata reached a low temperature of -31 degrees this morning. Pending verification procedures by NOAA%u2019s National Climatic Data Center, that mark will eclipse the previous statewide record low temperature of -27 degrees. The previous record was set at Vinita in February 1905 and at Watts in January 1930. Numerous other low-temperature records were broken this morning across the state, with several locations dropping below the previous statewide record. The National Weather Service site in Bartlesville recorded -28 degrees this morning, as did the Oklahoma Mesonet site at Pryor.

Low temperature readings from the Oklahoma Mesonet, February 10, 2011:

Site Low Temperature (F)
Nowata -31
Pryor -28
Blackwell -27
Medford -26
Marshall -25
Vinita -24
Cherokee -24
Lake Carl Blackwell -23
Inola -23
Breckinridge -23
Red Rock -23
Where's Tulsa on that list? The city reached -12 on February 10. That's cold...but nowhere near -31, and still 15 degrees 'warmer' than the city's all-time record low.
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Quoting Tropicsweatherpr:
Good morning. Impressive vorticity.



Agreed. 850, 700 and 500 mb vorticity slowly strengthening and vertically stacked in a low shear, moist environment.

Good amount of convergence, though linear due to it still being imbedded in the ITCZ.

I think another night of Dmax and we might be pretty close to a TD tomorrow morning. Should see some quick flow through the eastern Caribbean which won't allow much, if any, strengthening. Then it all comes down to land interaction. Way too early to speculate...
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Quoting Neapolitan:
The coldest it's ever been in Tulsa was -27...and that was in 1930. Source


Wrong infact this was on Doc's blog back last February.

Oklahoma Shatters All-Time Low Temperature Record
Oklahoma Shatters All-Time Low Temperature Record
Gary McManus
Associate State Climatologist
Oklahoma Climatological Survey
February 10, 2011

The Oklahoma Mesonet station at Nowata reached a low temperature of -31 degrees this morning. Pending verification procedures by NOAA’s National Climatic Data Center, that mark will eclipse the previous statewide record low temperature of -27 degrees. The previous record was set at Vinita in February 1905 and at Watts in January 1930. Numerous other low-temperature records were broken this morning across the state, with several locations dropping below the previous statewide record. The National Weather Service site in Bartlesville recorded -28 degrees this morning, as did the Oklahoma Mesonet site at Pryor.

Low temperature readings from the Oklahoma Mesonet, February 10, 2011:

Site Low Temperature (F)
Nowata -31
Pryor -28
Blackwell -27
Medford -26
Marshall -25
Vinita -24
Cherokee -24
Lake Carl Blackwell -23
Inola -23
Breckinridge -23
Red Rock -23
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Quoting LargoFl:


Nice shot of Hail Yes and Hail No
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Quoting StormTracker2K:


Just last winter they had a low one night of -31F
The coldest it's ever been in Tulsa was -27...and that was in 1930. Source

(The temperature hasn't gone subzero in Tulsa this year, and it did so only thrice last year, reaching -1, -6, and -12 in February.)
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RC015-095-109-151-311245-
ARROYO PR-MAUNABO PR-PATILLAS PR-YABUCOA PR-
819 AM AST TUE JUL 31 2012

AT 811 AM AST...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
STRONG THUNDERSTORMS OVER THESE MUNICIPALITIES. THESE AREAS OF
SHOWERS AND THUNDERSTORM ARE CAPABLE OF PRODUCING TORRENTIAL
RAIN...GUSTY WINDS UP TO 45 MPH AND FREQUENT LIGHTNING.

HEAVY RAINS MAY FLOOD LOW LYING AREAS SUCH AS DITCHES AND
UNDERPASSES. AVOID THESE AREAS AND DO NOT CROSS FLOODED ROADS AS
THEY MAY BE WASHED OUT. WATER LEVELS OF SMALL STREAMS AND RIVERS
MAY ALSO RISE...THEREFORE SEEK HIGHER GROUND IF THREATENED BY FLOOD
WATERS.

INTENSE LIGHTNING IS REPORTED WITH THIS STORM. IF OUTDOORS...STAY
AWAY FROM ISOLATED HIGH OBJECTS SUCH AS TREES. MOVE INDOORS IF
POSSIBLE. WHEN INDOORS...STAY AWAY FROM WINDOWS AND DOORS AND AVOID
USING TELEPHONES UNLESS IT IS AN EMERGENCY. TRY TO UNPLUG UNNECESSARY
ELECTRICAL APPLIANCES BEFORE THE THUNDERSTORM APPROACHES.

$$

OMS
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messed.up.sorry.meant.the.93.gert...http://en.wikip edia.org/wiki/Hurricane_Gert_(1993)
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I think some people are confused about what the % means on the nhc site. The percentage doesnt go up automatically when the system looks better unless it has a higher chance of becoming a tropical system within the next 48 hours. That is all the % means. It doesnt mean the % of it becoming something ever. If something, like dry air, ITCZ, Latitude, Shear or whatever are hindering the chances within the next 48 hours then the % wont go up.

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Quoting ProgressivePulse:
Morning All. The population of models that develop 99L has been reduced this morning. Most notably, the TVCN consensus model. Which means that the consensus of the models it uses for its forecast say no development.



GFDL nor HWRF have not been runned since Monday morning at 06z.
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Pocamocca Chris was a nice hurricane to track.Thousands of miles away from land a just a swirling away and looked really good.
Member Since: August 14, 2010 Posts: 10 Comments: 16409
Quoting StormTracker2K:


If it doesn't pull away from the ITCZ soon then it may just go south as the Euro and GFS are saying. The next 3 days are key but I also feel we have a sleeper wave near PR that people in FL better watch later this week as the wave looks really good this morning.

Could have our nerxt named system out of the mess near PR.



Morning all. And I tend to agree. Models are pretty persistent now with keeping 99l on a very southern path almost hitting South America.
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That first wave isn't in as much as a favorable environment as 99L.Maybe some gusty rain showers for some.
Member Since: August 14, 2010 Posts: 10 Comments: 16409
Morning All. The population of models that develop 99L has been reduced this morning. Most notably, the TVCN consensus model. Which means that the consensus of the models it uses for its forecast say no development.

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1741. LargoFl
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Quoting StormTracker2K:


If it doesn't pull away from the ITCZ soon then it may just go south as the Euro and GFS are saying. The next 3 days are key but I also feel we have a sleeper wave near PR that people in FL better watch later this week as the wave looks really good this morning.

Could have our nerxt named system out of the mess near PR.



If anything that wave near PR is certainly moistening the environment for others down the road. 99L looks healthy this morning too, I think we may see a 40-50% on this sometime today. Like you said though it does need to disconnect from the ITCZ, but it has been steadily organizing over the last 36 hours.



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1738. ncstorm
Quoting StormTracker2K:


That first wave near PR looks good this morning and I wonder if this area will get circled by the NHC later.




they're watching it
Member Since: August 19, 2006 Posts: 13 Comments: 14451
1737. LargoFl
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE TALLAHASSEE FL
801 AM EDT TUE JUL 31 2012

FLZ007>011-108-311300-
HOLMES FL-NORTH WALTON FL-JACKSON FL-CENTRAL WALTON FL-SOUTH WALTON
FL-WASHINGTON FL-
701 AM CDT TUE JUL 31 2012

...SIGNIFICANT WEATHER ADVISORY IN EFFECT FOR HOLMES...WESTERN
JACKSON...NORTHEASTERN WALTON AND NORTHERN WASHINGTON COUNTIES IN
THE FLORIDA PANHANDLE...

* UNTIL 800 AM CDT

AT 658 AM CDT...THE NATIONAL WEATHER SERVICE HAS DETECTED STRONG
THUNDERSTORMS ALONG A LINE EXTENDING FROM 9 MILES SOUTHEAST OF
FLORALA TO 12 MILES SOUTHEAST OF SLOCOMB...MOVING SOUTHEAST AT 25
MPH.

THESE STORMS WILL BE NEAR...
BONIFAY BY 740 AM CDT.
CHIPLEY BY 745 AM CDT.
6 MILES NORTH OF VERNON BY 800 AM CDT.

WINDS 40 TO 50 MPH ARE EXPECTED WITH THESE STORMS.

REPORT SIGNIFICANT WEATHER TO THE NATIONAL WEATHER SERVICE AT (8 5 0)
9 4 2 8 8 3 3. OR...CONTACT LAW ENFORCEMENT.

LAT...LON 3099 8637 3099 8547 3066 8522 3059 8611
TIME...MOT...LOC 1200Z 309DEG 21KT 3092 8621 3095 8550

$$
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Quoting StormTracker2K:
0Z CMC has a hurricane right on the east coast of FL.



Nogaps is near the Bahamas as well.

10 day margin of error is well over 1,000 miles,it could end up from bermuda to the gom.waaaaaay to early to speculate on a east coast hit,especially since we've already had several t-waves ride around the perphery of the ridge an into fl or the eastern gom.
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Hello Boys and Girls
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Looks like China is going to take it on the chin, although Saola has had issues over the last two days. Seems like the northern side of the storm is being sheared or is experiencing some stable, sinking air from the outflow of Damrey. I don't know if Saola will get to a major as they have her pegged for.



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Good morning.CMC has been really consistent in forming future Ernesto into a formidable system and sending it near or on to the S.E coast.JFV would be proud.
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1731. LargoFl
...........................................florid a panhandle take heed..that line of storms turned severe..better be a warning out on that storm Fast huh
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Quoting mcluvincane:
20% lol who pulls the percentage switch at the NHC? Seems a little conservative to me...


99L really needs to pull itself out of the ITCZ and concentrate its activites a little closer to a 'center' before the % chance for development increases.
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Quoting Pocamocca:
Tulsa, OK

Today: 111
Tmrw: 112
Thu: 111

Oppressive heat. Still shy of the all-time record by several degrees. We'll see if we can eclipse it.


Just last winter they had a low one night of -31F
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Quoting ncstorm:


Yeah, I said that people shouldnt sleep on the first wave..really starting to look good this morning..


That first wave near PR looks good this morning and I wonder if this area will get circled by the NHC later.
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Quoting GetReal:


August is going to get interesting....


Indeed it will
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1725. ncstorm
Quoting StormTracker2K:


If it doesn't pull away from the ITCZ soon then it may just go south as the Euro and GFS are saying. The next 3 days are key but I also feel we have a sleeper wave near PR that people in FDL better watch later this week as the wave looks really good this morning.

Could have our nerxt named system out of the mess near PR.



Yeah, I said that people shouldnt sleep on the first wave..really starting to look good this morning..
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20% lol who pulls the percentage switch at the NHC? Seems a little conservative to me...
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they.work.for.nothing..problem.is.having.power.to.r un.the.factories..
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1721. GetReal


August is going to get interesting....
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1720. LargoFl
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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.