[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 160000
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT MON AUG 15 2011

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS OF
SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST FROM THE
EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED ON SATELLITE
IMAGERY...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL
ANALYSIS.

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 2345 UTC.

...SPECIAL FEATURE...

THE CENTER OF TROPICAL STORM GERT AT 15/2100 UTC WAS NEAR 33.2N
62.7W. GERT IS MOVING NNE 12 KT. THE ESTIMATED MINIMUM
CENTRAL PRESSURE IS 1002 MB. THE MAXIMUM SUSTAINED WIND SPEEDS
ARE 50 KT WITH GUSTS TO 60 KT. PUBLIC ADVISORIES ON TROPICAL
STORM GERT ARE ISSUED UNDER WMO HEADER WTNT32 KNHC AND UNDER
AWIPS HEADER MIATCPAT2. FORECAST/ADVISORIES ON TROPICAL STORM
GERT ARE ISSUED UNDER WMO HEADER WTNT22 KNHC AND UNDER AWIPS
HEADER MIATCMAT2. SCATTERED HEAVY SHOWERS AND THUNDERSTORMS ARE
LOCATED WITHIN 70 NM OF THE STORM CENTER.

...TROPICAL WAVES...

TROPICAL WAVE IS IN THE FAR EAST TROPICAL ATLC EXTENDING FROM
19N20W TO 11N20W MOVING W 5-10 KT. SATELLITE IMAGERY SHOWS
CLEAR CUT CYCLONIC LOW-LEVEL FLOW AROUND THE WAVE AXIS CONFIRMED
BY AN EARLIER ASCAT PASS FROM THIS MORNING. TOTAL PRECIPITABLE
WATER IMAGERY INDICATES THAT A SURGE OF DEEP LAYER MOISTURE IS
MOVING OFF THE AFRICAN COAST IN ASSOCIATION WITH THE WAVE.
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ARE WITHIN 80-140
NM ON EITHER SIDE OF THE AXIS S OF 15N.

TROPICAL WAVE IS APPROACHING THE LESSER ANTILLES...ANALYZED FROM
18N60W TO A 1010 MB LOW NEAR 13N60W MOVING W NEAR 20 KT. THIS
SYSTEM IS EMBEDDED IN A DEEP LAYER MOISTURE NOTICED ON TOTAL
PRECIPITABLE WATER IMAGERY. LARGE CLUSTERS OF STRONG CONVECTION
ARE ALREADY IMPACTING THE LESSER ANTILLES FROM 12N-18N BETWEEN
55W-67W.

...THE ITCZ/THE MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS W OF A TROPICAL WAVE FROM 11N23W
ALONG 10N31W TO 11N42W. NO ITCZ IS OBSERVED AT THE MOMENT.
SCATTERED HEAVY SHOWERS AND THUNDERSTORMS ARE MOSTLY S OF THE
MONSOON TROUGH FROM 5N-11N BETWEEN 17W-42W.

...DISCUSSION...

GULF OF MEXICO...
A LONGWAVE UPPER LEVEL TROUGH MOVING ACROSS THE ERN AND SE CONUS
SWINGS INTO THE NRN GULF WITH STRONG SUBSIDENCE BEHIND IT
NOTICED ON WATER VAPOR IMAGERY. THE UPPER TROUGH SUPPORTS A
FRONTAL BOUNDARY THAT ENTERS THE NE GULF AS A COLD FRONT
ANALYZED FROM THE NORTHERN FLORIDA PENINSULA NEAR 30N84W TO
28N87W INTO LOUISIANA ALONG 29N90W. DESPITE THE LOCATION OF THE
FRONT...WIDELY SCATTERED SHOWERS AND THUNDERSTORMS ARE FOUND
WELL S OF THE FRONT...FROM 24N-27N E OF 90W...DUE TO THE
GREATEST LIFT AND INSTABILITY PROVIDED BY THE UPPER TROUGH. A
CONSIDERABLE DROP IN DEW POINTS AND RAPIDLY DISSIPATING CLOUDS
ARE OBSERVED BEHIND THE FRONT. WEAK SURFACE RIDGING WITH
ISOLATED WEAK SHOWERS ARE ACROSS THE REMAINDER OF THE DISCUSSION
AREA...WITH RIDGING CENTERED OFF THE EASTERN TEXAS COAST AROUND
A 1014 MB HIGH NEAR 29N94W. EXPECT THE FRONTAL BOUNDARY IN THE
NE GULF TO DIP DOWN A LITTLE FARTHER S BEFORE BECOMING
STATIONARY.

CARIBBEAN SEA...
A LARGE CLUSTER OF HEAVY SHOWERS AND THUNDERSTORMS IS IN THE
EASTERN CARIBBEAN E OF 67W...ASSOCIATED TO A LOW PRESSURE
SYSTEM/TROPICAL WAVE E OF THE LESSER ANTILLES. THE ISLANDS IN
THIS AREA SHOULD EXPECT SHOWER ACTIVITY TO CONTINUE OVER THE
NEXT 24 HOURS AS THE WAVE CROSSES INTO THE CARIBBEAN BASIN.
SIMILAR ACTIVITY IS IN THE SW CARIBBEAN S OF 13N W OF 75W...
ASSOCIATED WITH THE MONSOON TROUGH EXTENDING ACROSS COSTA RICA
TO NORTHERN COLOMBIA. SIMILAR CONVECTION IS OVER THE COASTAL
WATERS OF EASTERN CUBA AND NRN JAMAICA N OF 18N BETWEEN
75W-80W...ASSOCIATED TO A SURFACE TROUGH ANALYZED FROM 23N72W TO
19N77W. THE REMAINDER OF THE BASIN IS INFLUENCED BY DRY
SUBSIDENT AIR ALOFT SUPPORTING MOSTLY FAIR WEATHER ACROSS THE NW
AND CENTRAL CARIBBEAN WITH 5-15 KT ELY TRADE WINDS. EXPECT MORE
CONVECTION TO DEVELOP ACROSS THE WATERS NEAR CENTRAL CUBA AND
NRN OF JAMAICA AS THE SURFACE TROUGH DRIFTS WNW.

ATLANTIC OCEAN...
ALTHOUGH T.S. GERT IS N OF 32N OUT OF THE ATLC DISCUSSION
AREA...IT CONTINUES TO BE A SPECIAL FEATURE DISCUSSED ABOVE. A
LONGWAVE UPPER LEVEL TROUGH MOVING OFF THE ERN AND SE CONUS
SEABOARD SUPPORTS A COLD FRONT N OF THE AREA. HOWEVER...THE
CONVECTION ASSOCIATED TO THIS SYSTEM IS ACROSS MUCH OF THE FAR
WEST ATLC N OF 25N W OF 70W...DUE TO THE GREATEST MID-UPPER
LEVEL LIFT AND INSTABILITY PROVIDED BY THE UPPER TROUGH. THE
COLD FRONT WILL ENTER THE W ATLC TONIGHT. A SURFACE TROUGH IS
MOVING ACROSS THE SE BAHAMAS AND EASTERN CUBA FROM 23N72W TO
19N77W GENERATING SCATTERED HEAVY SHOWERS AND THUNDERSTORMS
WITHIN 60 NM ON EITHER SIDE OF THE AXIS. EXPECT MORE CONVECTION
TO DEVELOP ACROSS THE WATERS NEAR CENTRAL CUBA AND CENTRAL
BAHAMAS AS THE SURFACE TROUGH DRIFTS WNW. BROAD SURFACE RIDGING
DOMINATES THE REMAINDER OF THE ATLC...ANCHORED BY A 1021 MB HIGH
S OF THE AZORES NEAR 33N25W. A BROAD AREA OF AFRICAN DUST
EXTENDS E OF 40W TO THE COAST OF AFRICA.

FOR ADDITIONAL INFORMATION PLEASE VISIT
HTTP://WWW.HURRICANES.GOV/MARINE

$$

GARCIA


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