Dr. Jeff Masters' WunderBlog

African tropical wave 99L has potential to develop

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

+49

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

Categories: Hurricane

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1801. 19N81W 1:18 PM GMT on July 31, 2012
if 99l is that sensitive to shear its not going to do much in the caribbean which is where it is coming....sure could use some rain though! Member Since: August 24, 2008 Posts: 0 Comments: 332

1802. washingtonian115 1:19 PM GMT on July 31, 2012
IMO 99L may be a moderate to strong tropical storm when it reaches the islands.If it runs into the caribbean then expect it to get torn apart from shear.It may make a come back in the gulf if the circulation is still in tact.If 99L goes north of the caribbean and makes an exit near P.R then expect a much more stronger system that could either A.Go out to see(hoping that happens)B.Skirt the S.E coast or C...Make landfall some where along the coast. Member Since: August 14, 2010 Posts: 5 Comments: 10637

1803. HadesGodWyvern 1:19 PM GMT on July 31, 2012
Japan Meteorological Agency Tropical Cyclone Advisory #37 SEVERE TROPICAL STORM DAMREY (1210) 21:00 PM JST July 31 2012 ============================================= SUBJECT: Category Two Typhoon In Sea South Of Japan At 12:00 PM UTC, Severe Tropical Storm Damrey (975 hPa) located at 28.9N 137.2E has 10 minute sustained winds of 55 knots with gusts of 80 knots. The cyclone is reported as moving west at 15 knots. Dvorak Intensity: T3.5 Storm Force Winds ==================== 40 NM from the center Gale Force Winds ================= 300 NM from the center in northeast quadrant 180 NM from the center in southwest quadrant Forecast and Intensity ========================== 24 HRS: 30.7N 129.4E - 55 knots (CAT 2/Severe Tropical Storm) - southwest city of Makurazaki 48 HRS: 33.3N 124.3E - 50 knots (CAT 2/Severe Tropical Storm) - Yellow Sea 72 HRS: 38.0N 120.6E - 45 knots (CAT 1/Tropical Storm) - Bohai Sea Japan Meteorological Agency Tropical Cyclone Advisory #37 SEVERE TROPICAL STORM SAOLA (1209) 21:00 PM JST July 31 2012 ============================================= SUBJECT: Category Two Typhoon South Of Okinawa At 12:00 PM UTC, Severe Tropical Storm Saola (970 hPa) located at 21.6N 123.8E has 10 minute sustained winds of 60 knots with gusts of 85 knots. The cyclone is reported as almost stationary. Dvorak Intensity: T3.5 Storm Force Winds ================= 40 NM from the center Gale Force Winds ================ 400 NM from the center Forecast and Intensity ========================== 24 HRS: 23.2N 123.1E - 75 knots (CAT 3/Strong Typhoon) - southwest of Ishigaki Island 48 HRS: 25.4N 122.0E - 80 knots (CAT 3/Strong Typhoon) - East China Sea 72 HRS: 28.2N 119.1E - 70 knots (CAT 3/Strong Typhoon) - Overland China Member Since: May 24, 2006 Posts: 43 Comments: 36686

1804. LargoFl 1:19 PM GMT on July 31, 2012
BULLETIN - EAS ACTIVATION REQUESTED SEVERE THUNDERSTORM WARNING NATIONAL WEATHER SERVICE TALLAHASSEE FL 735 AM CDT TUE JUL 31 2012 THE NATIONAL WEATHER SERVICE IN TALLAHASSEE HAS ISSUED A * SEVERE THUNDERSTORM WARNING FOR... SOUTHERN HOLMES COUNTY IN THE PANHANDLE OF FLORIDA... CENTRAL WALTON COUNTY IN THE PANHANDLE OF FLORIDA... WASHINGTON COUNTY IN THE PANHANDLE OF FLORIDA... * UNTIL 815 AM CDT * AT 730 AM CDT...THE NATIONAL WEATHER SERVICE HAS DETECTED A LINE OF SEVERE THUNDERSTORMS CAPABLE OF PRODUCING DAMAGING WINDS IN EXCESS OF 60 MPH. THESE STORMS WERE LOCATED ALONG A LINE EXTENDING FROM 6 MILES WEST OF DE FUNIAK SPRINGS TO 6 MILES NORTH OF VERNON...MOVING SOUTH AT 25 MPH. * OTHER LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO DE FUNIAK SPRINGS...PLEASANT RIDGE...WAUSAU...RED BAY...LIVE OAK...HOLMES VALLEY...NEW HOPE...FREEPORT...BRUCE...EBRO AND CRYSTAL LAKE. PRECAUTIONARY/PREPAREDNESS ACTIONS... THIS IS A DANGEROUS STORM. IF YOU ARE IN ITS PATH...PREPARE IMMEDIATELY. PEOPLE OUTSIDE SHOULD MOVE INSIDE A STRONG BUILDING BUT AWAY FROM WINDOWS. CONTINUOUS CLOUD TO GROUND LIGHTNING IS OCCURRING WITH THIS STORM. LIGHTNING IS ONE OF NATURES NUMBER ONE KILLERS. REMEMBER...IF YOU CAN HEAR THUNDER...YOU ARE CLOSE ENOUGH TO BE STRUCK BY LIGHTNING. LAT...LON 3078 8561 3044 8550 3043 8617 3045 8617 3047 8623 3043 8625 3046 8624 3048 8627 3079 8634 TIME...MOT...LOC 1234Z 347DEG 21KT 3070 8621 3069 8569 Member Since: August 6, 2011 Posts: 0 Comments: 22426

1805. StormJunkie 1:19 PM GMT on July 31, 2012
Quoting Pocamocca: Junkie ~ You buying some of these models taking it straight up to Summerville, SC? No way, I'm not convinced it will every make it out of the Carib. May pretty much stay on a western path the whole way. Member Since: August 17, 2005 Posts: 26 Comments: 15218

1806. StormTracker2K 1:20 PM GMT on July 31, 2012
PR is getting pounded this morning. Member Since: October 26, 2011 Posts: 0 Comments: 2651

1808. LargoFl 1:22 PM GMT on July 31, 2012
.................................for you folks in Panama city, this first line of severe storms is just the beginning, a huge rain maker is following that first line..going to be a very interesting day up there for severe weather...now im wondering WHAT..is going to happen when this gets into the gulf with those 86 degree water temps. Member Since: August 6, 2011 Posts: 0 Comments: 22426

1809. Tropicsweatherpr 1:23 PM GMT on July 31, 2012
FLOOD ADVISORY NATIONAL WEATHER SERVICE SAN JUAN PR 852 AM AST TUE JUL 31 2012 PRC015-025-035-041-057-069-077-085-095-103-109-12 3-129-151-311545- /O.NEW.TJSJ.FA.Y.0289.120731T1252Z-120731T1545Z/ /00000.N.ER.000000T0000Z.000000T0000Z.000000T0000 Z.OO/ ARROYO PR-CAGUAS PR-CAYEY PR-CIDRA PR-GUAYAMA PR-NAGUABO PR-JUNCOS PR-LAS PIEDRAS PR-MAUNABO PR-PATILLAS PR-SALINAS PR-SAN LORENZO PR-YABUCOA PR-HUMACAO PR- 852 AM AST TUE JUL 31 2012 THE NATIONAL WEATHER SERVICE IN SAN JUAN HAS ISSUED AN * URBAN AND SMALL STREAM FLOOD ADVISORY FOR MINOR FLOODING OF POOR DRAINAGE AREAS IN FOR THE FOLLOWING MUNICIPALITIES... IN PUERTO RICO ARROYO...CAGUAS...CAYEY...CIDRA...GUAYAMA...NAGUAB O...JUNCOS... LAS PIEDRAS...MAUNABO...PATILLAS...SALINAS...SAN LORENZO... YABUCOA AND HUMACAO * UNTIL 1145 AM AST * AT 848 AM AST...DOPPLER RADAR ESTIMATED VERY HEAVY RAIN IN THE ADVISORY AREA AND MORE MOVING IN FROM THE SOUTHEAST. ADDITIONAL RAINFALL AMOUNTS OF ONE TO TWO INCHES ARE POSSIBLE IN THE ADVISORY AREA. MOST FLOOD DEATHS OCCUR IN AUTOMOBILES. NEVER DRIVE YOUR VEHICLE INTO AREAS WHERE THE WATER COVERS THE ROADWAY. FLOOD WATERS ARE USUALLY DEEPER THAN THEY APPEAR. JUST ONE FOOT OF FLOWING WATER IS POWERFUL ENOUGH TO SWEEP VEHICLES OFF THE ROAD. WHEN ENCOUNTERING FLOODED ROADS MAKE THE SMART CHOICE...TURN AROUND...DONT DROWN. && LAT...LON 1807 6621 1819 6615 1813 6577 1811 6577 1797 6591 1796 6597 1797 6602 1795 6604 1796 6608 1793 6614 $$ SNELL Member Since: April 29, 2009 Posts: 64 Comments: 8160

1810. StormTracker2K 1:24 PM GMT on July 31, 2012
Quoting Pocamocca: I'm thinking the same. It should find it's final resting place somewhere in the Caribbean. Looks that way but we really have to watch and see if it can intesify some before reaching the islands because it does then 99L would turn more WNW. Basically between now and Friday is going to be key on where 99L ends up as for right now it looks like Central America. Member Since: October 26, 2011 Posts: 0 Comments: 2651

1811. unknowncomic 1:24 PM GMT on July 31, 2012
Quite a blob coming down Alabama. Member Since: August 2, 2011 Posts: 0 Comments: 466

1812. kwgirl 1:24 PM GMT on July 31, 2012
Good morning all. I see the debate is still running concerning 99L. It looks more spread out to me this A.M. but I am only looking at a little snapshot. The blob by PR appears to have some rotation. Or is that just the shearing that makes it appear that way? Either way, it appears the blob is producing some heavy rains. Everyone have a great day today. Member Since: March 28, 2008 Posts: 0 Comments: 1530

1813. LargoFl 1:25 PM GMT on July 31, 2012
BULLETIN - EAS ACTIVATION REQUESTED SEVERE THUNDERSTORM WARNING NATIONAL WEATHER SERVICE MOBILE AL 754 AM CDT TUE JUL 31 2012 THE NATIONAL WEATHER SERVICE IN MOBILE HAS ISSUED A * SEVERE THUNDERSTORM WARNING FOR... NORTHEASTERN BUTLER COUNTY IN SOUTH CENTRAL ALABAMA... NORTHERN CRENSHAW COUNTY IN SOUTH CENTRAL ALABAMA... * UNTIL 900 AM CDT * AT 749 AM CDT...A LINE OF SEVERE THUNDERSTORMS CAPABLE OF PRODUCING QUARTER SIZE HAIL AND DAMAGING WINDS OVER 60 MPH WERE LOCATED ALONG A LINE EXTENDING FROM GREENVILLE TO 16 MILES NORTH OF LUVERNE...AND MOVING SOUTH AT 45 MPH. * LOCATIONS IMPACTED INCLUDE... RUTLEDGE... PETREY... LUVERNE... I65 AND AL 185... I65 AND AL 10... GREENVILLE... THIS INCLUDES INTERSTATE 65 BETWEEN MILE MARKERS 126 AND 139. LAT...LON 3183 8618 3181 8620 3179 8618 3165 8620 3166 8664 3197 8672 3197 8641 3202 8641 3204 8630 3197 8629 3197 8619 3196 8618 3190 8617 TIME...MOT...LOC 1254Z 344DEG 39KT 3178 8662 3188 8635 Member Since: August 6, 2011 Posts: 0 Comments: 22426

1814. WunderAlertBot (Admin) 1:26 PM GMT on July 31, 2012
JeffMasters has created a new entry.

1815. LargoFl 1:27 PM GMT on July 31, 2012
Member Since: August 6, 2011 Posts: 0 Comments: 22426

1816. GeoffreyWPB 1:29 PM GMT on July 31, 2012
Member Since: September 10, 2007 Posts: 0 Comments: 9122

1818. GetReal 1:34 PM GMT on July 31, 2012
Latest 13z run of the MOD has shifted east towards the Alabama coast on day thirteen. Very similar to an Ivan type track. Weak minimal TS trough the eastern and central Caribbean, and finally exploding into a strong hurricane just west of Jamaica. (flag on) Member Since: July 4, 2005 Posts: 204 Comments: 8196

1819. Grothar 1:40 PM GMT on July 31, 2012
Member Since: July 17, 2009 Posts: 56 Comments: 19527

1820. ncstorm 2:40 PM GMT on August 01, 2012
Quoting GTcooliebai: Euro 144 hrs. out: GFS 144 hrs. out: Euro is faster than the GFS, but both heading in a general westward path. the models are trending more north.. Member Since: August 19, 2006 Posts: 7 Comments: 8418

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