[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 121143
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT THU SEP 12 2013

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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1015 UTC.

...SPECIAL FEATURES...
HURRICANE HUMBERTO IS CENTERED NEAR 20.5N 28.7W AT 12/0900 UTC
OR ABOUT 382 NM NW OF THE CAPE VERDE ISLANDS MOVING N AT 12 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 982 MB. MAXIMUM SUSTAINED
WIND SPEED IS 75 KT WITH GUSTS TO 90 KT. SEE LATEST NHC
INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS
MIATCPAT4/WTNT34 KNHC AND THE FULL FORECAST/ADVISORY UNDER
AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS.
CLUSTERS OF SCATTERED MODERATE/STRONG CONVECTION COVER THE
AREA FROM 19N-24N BETWEEN 26W-30W.

TROPICAL DEPRESSION GABRIELLE IS CENTERED NEAR 33.5N 67.7W AT
12/0900 UTC OR ABOUT 165 NM W-NW OF BERMUDA AND ABOUT 480 NM S-
SE OF NANTUCKET MASSACHUSETTS MOVING NW AT 6 KT. ESTIMATED
MINIMUM CENTRAL PRESSURE IS 1010 MB. MAXIMUM SUSTAINED WIND
SPEED IS 30 KT WITH GUSTS TO 40 KT. SEE LATEST NHC INTERMEDIATE
PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS MIATCPAT2/WTNT32 KNHC
AND THE FULL FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS
MIATCMAT2/WTNT22 KNHC FOR MORE DETAILS. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION REDEVELOPED CLOSE TO THE
CENTER OVER THE PAST FEW HOURS FROM 32N-35W BETWEEN 64W-67W.

A BROAD AREA OF LOW PRESSURE OVER THE YUCATAN PENINSULA AND THE
BAY OF CAMPECHE IS ANALYZED AS A SURFACE TROUGH THAT AT 12/0900
UTC EXTENDS FROM THE GULF OF MEXICO NEAR 25N90W ALONG 21N91W TO
A 1005 MB LOW IN THE BAY OF CAMPECHE NEAR 19N92W. IT APPEARS THE
LOW HAS REDEVELOPED W OF WHERE IT WAS LOCATED PREVIOUSLY. THE
SHOWERS/THUNDERSTORMS HAVE INCREASED DURING THE PAST FEW HOURS
AS SURFACE PRESSURES CONTINUE TO FALL. AN UPPER TROUGH OVER THE
GULF OF MEXICO AND AN UPPER RIDGE OVER THE CARIBBEAN ARE
CREATING A BROAD AREA OF INSTABILITY WITH SCATTERED/HEAVY
SHOWERS AND SCATTERED THUNDERSTORMS S OF 21N ACROSS THE BAY OF
CAMPECHE. CLUSTERS OF SCATTERED TO HEAVY SHOWERS WITH EMBEDDED
THUNDERSTORMS COVER THE AREA S OF 25N BETWEEN 80W-91W INCLUDING
PORTIONS OF W CUBA...YUCATAN PENINSULA...CENTRAL AMERICA...AND
THE SW CARIBBEAN. ENVIRONMENTAL CONDITIONS APPEAR TO BE
FAVORABLE FOR DEVELOPMENT AND THIS DISTURBANCE HAS A HIGH
CHANCE...60 PERCENT...OF BECOMING A TROPICAL CYCLONE DURING THE
NEXT 48 HOURS. THIS SYSTEM IS FORECAST TO MOVE VERY SLOWLY
ACROSS THE SOUTHERN GULF OF MEXICO PRODUCING LOCALLY HEAVY RAINS
OVER A LARGE PART OF EASTERN MEXICO DURING THE NEXT SEVERAL
DAYS.  THESE RAINS COULD CAUSE LIFE-THREATENING FLASH FLOODS AND
MUD SLIDES.

...TROPICAL WAVES...

NONE.

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

THE MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE E TROPICAL
ATLC NEAR 12N16W TO 11N21W THEN RESUMES SW OF HURRICANE HUMBERTO
NEAR 15N34W TO 11N48W WHERE THE ITCZ BEGINS AND CONTINUES INTO
SOUTH AMERICA NEAR 9N61W. THE MONSOON TROUGH CONTINUES TO BE
DISRUPTED BY HURRICANE HUMBERTO. CLUSTERS OF SCATTERED MODERATE/
ISOLATED STRONG CONVECTION ARE FROM 6N-12N E OF 22W TO THE COAST
OF W AFRICA. CLUSTERS OF SCATTERED MODERATE CONVECTION ARE FROM
10N-17N BETWEEN 26W-30W AND FROM 6N-10N BETWEEN 34W-50W. A 1007
MB LOW IS CENTERED NEAR 16N53W WITH SCATTERED MODERATE/STRONG
CONVECTION WITHIN 90 NM E OF THE CENTER.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER TROUGH EXTENDS OVER THE W GULF FROM AN UPPER LOW ALONG
THE COAST OF TEXAS NEAR GALVESTON ALONG 25N94W TO OVER THE W BAY
OF CAMPECHE NEAR TUXPAN. AN UPPER LOW IS ALONG THE COAST OF
GEORGIA AND EXTENDS AN UPPER TROUGH ACROSS THE NE GULF N OF 27N
E OF 87W. A SURFACE TROUGH EXTENDS FROM THE W ATLC ALONG THE
BASE OF THE UPPER LOW ACROSS FLORIDA BETWEEN WEST PALM BEACH TO
JUST S OF FORT MYERS THEN INTO THE GULF TO 26N85W. SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 150 NM S OF THE
SURFACE TROUGH E OF 85W ACROSS FLORIDA AND THROUGH THE STRAITS
OF FLORIDA. SIMILAR ACTIVITY IS N OF THE SURFACE TROUGH WITHIN
30 NM OF LINE FROM FORT MYERS TO 29N85W. AN UPPER RIDGE ANCHORED
OVER THE W CARIBBEAN COVERS THE REMAINDER OF THE SE GULF. THIS
IS CREATING A VERY DIFFLUENT ENVIRONMENT MAINLY FOR THE S GULF.
THE SURFACE TROUGH AND LOW IN THE CENTRAL GULF AND BAY OF
CAMPECHE WITH THE ASSOCIATED WEATHER ARE DISCUSSED IN THE
SPECIAL FEATURES ABOVE. A SURFACE RIDGE EXTENDS OVER THE N GULF
ANCHORED BY A SERIES OF WEAK HIGHS OVER THE SE CONUS. SURFACE
RIDGE WILL PERSIST THROUGH TONIGHT. THE SURFACE TROUGH/LOW IN
THE SPECIAL FEATURES ABOVE IS FORECAST TO MOVE VERY SLOWLY W-NW
AND POSSIBLY DEVELOP INTO A TROPICAL CYCLONE.

CARIBBEAN SEA...
SEE THE SPECIAL FEATURES ABOVE FOR THE ACTIVITY OVER THE W
CARIBBEAN ASSOCIATED WITH THE SURFACE TROUGH/LOW IN THE BAY OF
CAMPECHE. AN UPPER RIDGE IS ANCHORED OVER THE NW CARIBBEAN IN
THE GULF OF HONDURAS COVERING THE AREA W OF 78W ACROSS CUBA INTO
THE SE GULF OF MEXICO. AN UPPER LOW DOMINATES THE REMAINDER OF
THE CARIBBEAN CENTERED NEAR 16N73W. SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS ARE S OF 14N TO INLAND OVER COLOMBIA BETWEEN 70W-
76W. A SURFACE TROUGH IS APPROACHING THE LEEWARD ISLANDS AND IS
DISCUSSED IN THE ATLC SECTION BELOW. MODERATE TO FRESH TRADE
WINDS WILL CONTINUE ACROSS THE CENTRAL AND E CARIBBEAN THROUGH
TODAY WHILE MODERATE SE WINDS WILL PREVAIL ACROSS THE W
CARIBBEAN.

HISPANIOLA...
HISPANIOLA IS UNDER MOSTLY CLEAR SKIES THIS MORNING. HOWEVER...
ISOLATED SHOWERS COULD STILL FORM ESPECIALLY OVER THE S PORTION
OF THE DOMINICAN REPUBLIC. THE UPPER TROUGH CURRENTLY COVERING
THE CARIBBEAN WILL SHIFT W. SOUTHERLY SURFACE FLOW WILL THEN
DOMINATE THE ISLAND BY FRI MORNING. THE WEAK SURFACE TROUGH
CURRENTLY E OF THE LEEWARD ISLANDS WILL CONTINUE W CROSSING THE
ISLAND ON SAT. THIS COULD INCREASE THE CHANCES OF HEAVIER
SHOWERS AND THUNDERSTORMS TO HISPANIOLA LATE FRI INTO SAT.
AFTERNOON HEATING COULD STILL BRING POTENTIAL SCATTERED
THUNDERSTORMS THROUGH THE REMAINDER OF THE WEEKEND.

ATLANTIC OCEAN...
THE PRIMARY CONCERNS FOR THE ATLC BASIN THIS MORNING ARE
TROPICAL DEPRESSION GABRIELLE IN THE W ATLC AND HURRICANE
HUMBERTO IN THE E ATLC. SEE SPECIAL FEATURES ABOVE. AN UPPER LOW
IS CENTERED ALONG THE COAST OF GEORGIA WITH AN UPPER TROUGH
COVERING THE W ATLC N OF 27N W OF 75W. A SURFACE TROUGH IS ALONG
THE S PERIPHERY OF THE UPPER TROUGH FROM 32N75W 28N77W ACROSS
FLORIDA INTO THE GULF OF MEXICO NEAR WEST PALM BEACH. SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 90 NM OF LINE FROM
OVER FLORIDA NEAR FORT LAUDERDALE CROSSING THE SURFACE TROUGH
NEAR 28N77W TO BEYOND 32N76W. CLUSTERS OF SCATTERED SHOWERS/
ISOLATED THUNDERSTORMS DOT THE AREA FROM 27N-30N BETWEEN 64W-
70W. A SHORTWAVE UPPER TROUGH IS DEVELOPING OVER THE LEEWARD
ISLANDS FROM 19N64W TO 11N59W SUPPORTING A SURFACE TROUGH THAT
IS APPROACHING THE LEEWARD ISLANDS EXTENDING FROM 24N65W 18N62W
TO 15N54W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE FROM 13N-
16N BETWEEN 53W-62W INCLUDING THE ISLANDS BETWEEN DOMINICA AND
SAINT LUCIA. ISOLATED SHOWERS ARE WITHIN 90/120 NM EITHER SIDE
OF THE TROUGH INCLUDING THE LEEWARD AND VIRGIN ISLANDS. A WEAK
PRESSURE PATTERN WILL PREVAIL ACROSS THE MOST OF THE ATLC.

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

$$
PAW/NR


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