[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 120604
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0515 UTC.

...SPECIAL FEATURES...
HURRICANE HUMBERTO IS CENTERED NEAR 19.1N 29.0W AT 12/0300 UTC
OR ABOUT 345 NM NW OF THE CAPE VERDE ISLANDS MOVING N AT 11 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.
SCATTERED STRONG CONVECTION IS FROM 18N-20N BETWEEN 28W-30W.
CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION COVERS
THE REMAINDER OF THE AREA FROM 16N-23N BETWEEN 23W-32W.

TROPICAL STORM GABRIELLE WAS DOWNGRADED TO TROPICAL DEPRESSION
AT 12/0300 UTC. TROPICAL DEPRESSION GABRIELLE IS CENTERED NEAR
33.0N 67.0W AT 12/0300 UTC OR ABOUT 120 NM W-NW OF BERMUDA AND
ABOUT 520 NM S-SE OF NANTUCKET MASSACHUSETTS MOVING W-NW AT 5
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. A
SMALL AREA OF SCATTERED MODERATE CONVECTION IS WELL THE E OF THE
LOW CENTER WITHIN 30 NM OF 33N BETWEEN 64W-66W.

A BROAD AREA OF LOW PRESSURE OVER THE YUCATAN PENINSULA IS
ANALYZED AS A SURFACE TROUGH THAT  EXTENDS FROM THE S GULF OF
MEXICO NEAR 24N87W OVER THE THE YUCATAN PENINSULA ALONG 21N89W
TO A 1007 MB LOW NEAR 18N90W. ALTHOUGH SHOWERS/THUNDERSTORMS ARE
CURRENTLY DISORGANIZED SURFACE PRESSURES ARE FALLING ACROSS THIS
REGION AND THE LOW IS EXPECTED TO ENTER THE BAY OF CAMPECHE
LATER TODAY WHERE ENVIRONMENTAL CONDITIONS ARE EXPECTED TO BE
CONDUCIVE FOR DEVELOPMENT. THIS DISTURBANCE IS LIKELY TO BECOME
A TROPICAL CYCLONE DURING THE NEXT COUPLE OF DAYS AS LONG AS IT
REMAINS FAR ENOUGH OFFSHORE. THIS SYSTEM HAS A HIGH CHANCE OF
BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS. AN UPPER
TROUGH OVER THE GULF OF MEXICO AND AN UPPER RIDGE OVER THE
CARIBBEAN ARE CREATING A BROAD AREA OF INSTABILITY WITH CLUSTERS
OF SCATTERED TO HEAVY SHOWERS WITH EMBEDDED THUNDERSTORMS
COVERING THE AREA S OF 25N BETWEEN 80W-91W INCLUDING PORTIONS OF
W CUBA...THE CAYMAN ISLANDS...YUCATAN PENINSULA...AND CENTRAL
AMERICA.

...TROPICAL WAVES...

NONE.

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

THE MONSOON TROUGH EXTENDS ACROSS AFRICA TO THE COAST SENEGAL
THEN RESUMES SW OF HURRICANE HUMBERTO NEAR 14N33W TO 9N46W WHERE
THE ITCZ BEGINS AND CONTINUES ALONG 8N51W INTO SOUTH AMERICA
NEAR 6N54W. THE MONSOON TROUGH CONTINUES TO BE DISRUPTED BY
HURRICANE HUMBERTO. CLUSTERS OF SCATTERED MODERATE/ISOLATED
STRONG CONVECTION ARE FROM 6N-12N BETWEEN 14W-20W INCLUDING THE
COAST OF GUINEA AND GUINEA BISSAU. CLUSTERS OF SCATTERED
MODERATE CONVECTION ARE FROM 6N-9N BETWEEN 38W-48W. A WEAK 1009
MB LOW IS CENTERED NEAR 17N52W WITH SCATTERED MODERATE STRONG
CONVECTION WITHIN 75 NM OF THE CENTER IN THE SE QUADRANT. A
SURFACE TROUGH IS NE OF THE LEEWARD ISLANDS EXTENDING FROM
23N64W 18N62W TO 15N56W. ISOLATED SHOWERS ARE WITHIN 90 NM
EITHER SIDE OF THE TROUGH INCLUDING THE LEEWARD AND PORTION OF
THE VIRGIN ISLANDS.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER TROUGH EXTENDS OVER THE W GULF FROM AN UPPER LOW OVER
TEXAS ALONG 26N94W TO OVER THE BAY OF CAMPECHE. AN UPPER LOW IS
ALONG THE COAST OF GEORGIA AND EXTENDS AN UPPER TROUGH ACROSS
THE NE GULF N OF 26N E OF 88W. 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 OVER THE YUCATAN AND THE ASSOCIATED WEATHER ARE
DISCUSSED IN THE SPECIAL FEATURES ABOVE. IN ADDITION...SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS ARE IN THE BAY OF CAMPECHE S OF
21N BETWEEN MERIDA AND TUXPAN. REMNANT MOISTURE AND ACCOMPANYING
SURFACE TROUGH FROM THE W ATLC EXTENDS ACROSS FLORIDA FROM BOCA
RATON TO FORT MYERS TO 25N85W IN THE E GULF. SCATTERED SHOWERS/
ISOLATED THUNDERSTORMS ARE S OF THE SURFACE TROUGH E OF 85W
ACROSS FLORIDA AND THROUGH THE STRAITS OF FLORIDA. A SURFACE
RIDGE EXTENDS FROM A 1021 MB HIGH OVER WESTERN NORTH CAROLINA TO
OVER THE N GULF. SURFACE RIDGE WILL PERSIST THROUGH THU. THE
SURFACE TROUGH/LOW IN THE SPECIAL FEATURES ABOVE IS FORECAST TO
ENTER THE BAY OF CAMPECHE LATER THIS MORNING AND MOVE VERY
SLOWLY W-NW AND POSSIBLY DEVELOP INTO A TROPICAL CYCLONE.

CARIBBEAN SEA...
AN UPPER RIDGE IS ANCHORED OVER THE NW CARIBBEAN NEAR 20N83W
COVERING THE AREA W OF 77W ACROSS CUBA INTO THE SE GULF OF
MEXICO. SEE THE SPECIAL FEATURES ABOVE FOR THE ACTIVITY OVER THE
W CARIBBEAN ASSOCIATED WITH THE SURFACE TROUGH/LOW. AN UPPER LOW
DOMINATES THE REMAINDER OF THE CARIBBEAN CENTERED NEAR 15N72W.
CLUSTERS OF SCATTERED SHOWERS/ISOLATED THUNDERSTORMS DOT THE
AREA FROM 17N-20N BETWEEN 75W-79W AND FROM 11N-14N BETWEEN 60W-
70W INCLUDING THE N COAST OF COLOMBIA AND THE GULF OF VENEZUELA.
A SURFACE TROUGH DISCUSSED IN THE MONSOON TROUGH/ITCZ SECTION
ABOVE IS APPROACHING THE NE CARIBBEAN. MODERATE TO FRESH TRADE
WINDS WILL CONTINUE ACROSS THE CENTRAL AND E CARIBBEAN THROUGH
THU WHILE MODERATE SE WINDS WILL PREVAIL ACROSS THE W CARIBBEAN
BEHIND THE TROUGH OVER THE YUCATAN PENINSULA.

HISPANIOLA...
SOME ISOLATED SHOWERS ARE POSSIBLE ACROSS THE ISLAND TONIGHT BUT
LITTLE SIGN OF ANY THUNDERSTORMS OR HEAVY SHOWERS. 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 TONIGHT 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 PERIPHERY
FROM 30N75W 27N77W ACROSS FLORIDA INTO THE GULF OF MEXICO NEAR
BOCA RATON. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN
180 NM S OF THE TROUGH FROM THE BAHAMA ISLANDS TO OVER FLORIDA.
CLUSTERS OF SCATTERED SHOWERS/ISOLATED THUNDERSTORMS DOT THE
REMAINDER OF THE W ATLC N OF 27N BETWEEN 74W-80W. AN LARGE
ELONGATED UPPER LOW REMAINS IN THE E/CENTRAL ATLC CENTERED NEAR
23N44W BUT IS NOT PRODUCING ANY SIGNIFICANT WEATHER. THE
REMAINDER OF THE ATLC IS DOMINATED BY A WEAK SURFACE RIDGE
ANCHORED BY HIGHS WELL N OF THE AZORES. A WEAK PRESSURE PATTERN
WILL PREVAIL ACROSS THE MOST OF THE ATLC.

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

$$
PAW


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