[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 111805
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT WED SEP 11 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...SPECIAL FEATURES...
TROPICAL STORM GABRIELLE IS CENTERED NEAR 32.5N 65.9W AT 11/1500
UTC OR ABOUT 564 NM SSE OF NANTUCKET MASSACHUSETTS. THE SYSTEM
IS NOW MOVING WEST AT 3 KT AND HAS AN ESTIMATED MINIMUM CENTRAL
PRESSURE IS 1009 MB. MAXIMUM SUSTAINED WIND SPEED IS 40 KT WITH
GUSTS TO 50 KT. SCATTERED SMALL CLUSTERS OF MODERATE CONVECTION
ARE WELL E OF THE LOW CENTER FROM 29N-34N BETWEEN 61W-66W. 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.

HURRICANE HUMBERTO IS CENTERED NEAR 16.7N 29.1W AT 11/1500 UTC
OR ABOUT 297 NM W OF THE CAPE VERDE ISLANDS AND IS MOVING N AT 8
KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 989 MB. MAXIMUM
SUSTAINED WIND SPEED IS 70 KT WITH GUSTS TO 85 KT. NUMEROUS
MODERATE/ISOLATED STRONG CONVECTION IS FROM 14N-18N BETWEEN 26W-
31W. SCATTERED MODERATE CONVECTION IS ELSEWHERE FROM 10N-23N
BETWEEN 22W-35W. 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.

A BROAD AREA OF LOW PRESSURE OVER THE NW CARIBBEAN IS PRODUCING
A LARGE AREA OF RAINSHOWERS AND THUNDERSTORMS. A SURFACE TROUGH
EXTENDS FROM 22N87W TO THE EASTERN YUCATAN PENINSULA AND BELIZE
TO THE W COAST OF HONDURAS NEAR 14N88W. THE SURFACE TROUGH
SHOULD CONTINUE MOVING ACROSS THE YUCATAN TODAY AND ENTER THE
BAY OF CAMPECHE ON THU WHEN SOME DEVELOPMENT IS POSSIBLE. THE
SHOWER ACTIVITY ASSOCIATED WITH THIS LOW SHOWS SIGNS OF
ORGANIZATION. CURRENTLY...NUMEROUS MODERATE CONVECTION AND
ISOLATED TSTMS ARE FROM 16N-21N BETWEEN 85W-90W WITH SCATTERED
MODERATE CONVECTION AND ISOLATED TSTMS BEING ELSEWHERE FROM 17N-
23N BETWEEN 79W-85W. THIS SYSTEM HAS A MEDIUM CHANCE...40
PERCENT...OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 48
HOURS. LOCALLY HEAVY RAINS AND GUSTY WINDS ARE EXPECTED OVER
BELIZE... GUATEMALA...AND THE YUCATAN PENINSULA DURING THE NEXT
DAY OR TWO.

...TROPICAL WAVES...

NONE.

...THE ITCZ/THE MONSOON TROUGH...
THE MONSOON TROUGH CONTINUES TO BE DISRUPTED BY HURRICANE
HUMBERTO. IT AXIS EXTENDS ACROSS AFRICA FROM MALI NEAR 21N02W TO
MAURITANIA NEAR 17N11W...THEN RESUMES SW OF HURRICANE HUMBERTO
FROM 08N37W TO 08N49W. THE ITCZ AXIS BEGINS NEAR 06N54W TO
GUYANA NEAR 06N58W. SCATTERED MODERATE CONVECTION IS FROM 03N-
10N BETWEEN 12W-18W. SCATTERED SHOWERS TRAILING HURRICANE
HUMBERTO ARE FROM 05N-10N BETWEEN 24W-45W.

...DISCUSSION...

GULF OF MEXICO...
AN ELONGATED UPPER-LEVEL LOW...INVERTED TROUGH IN THE MIDDLE-
LEVEL OVER THE WESTERN GULF W OF 91W SUPPORTS A SURFACE TROUGH
COLLOCATED WITHIN A REGION OF HIGH MOISTURE. THE AXIS OF THE
TROUGH IS OFFSHORE EASTERN MEXICO ALONG 25N97W TO 18N94W.
RAINSHOWERS AND ISOLATED TSTMS ARE S OF 26N W OF 92W. A MIDDLE
TO UPPER LEVEL LOW CENTERED OVER CENTRAL FLORIDA IS SUPPORTING
SHOWERS AND ISOLATED TSTMS ACROSS SOUTHERN FLORIDA WHICH EXTEND
TO THE SE GULF FROM 25N-26N E OF 85W. SURFACE RIDGING DOMINATES
THE NORTHERN GULF N OF 26N WHERE LOW TO MIDDLE LEVEL DRY AIR
SUPPORTS FAIR WEATHER THIS AFTERNOON. THE SURFACE TROUGH IN THE
SPECIAL FEATURES ABOVE IS EXPECTED TO MOVE SLOWLY W-NW ACROSS
THE YUCATAN PENINSULA TODAY AND ENTER THE BAY OF CAMPECHE ON
THU. A SURFACE LOW IS EXPECTED TO DEVELOP ALONG THE TROUGH OVER
THE SW GULF LATER IN THE WEEK THEN INTENSIFY SLOWLY THROUGH SUN
AS IT DRIFTS NW. THE LOW COULD POSSIBLY DEVELOP INTO A TROPICAL
CYCLONE.

CARIBBEAN SEA...
A BROAD AREA OF LOW PRESSURE IS OVER THE NW CARIBBEAN COLLOCATED
WITHIN A REGION OF UPPER-LEVEL DIVERGENCE AND MAXIMUM MOISTURE
AS DEPICTED IN TOTAL PRECIPITABLE WATER IMAGERY.  A SURFACE
TROUGH EXTENDS FROM 22N87W TO THE EASTERN YUCATAN PENINSULA AND
BELIZE TO THE W COAST OF HONDURAS NEAR 14N88W. NUMEROUS MODERATE
CONVECTION AND ISOLATED TSTMS ARE FROM 16N-21N BETWEEN 85W-90W.
SCATTERED MODERATE CONVECTION AND ISOLATED TSTMS ARE ELSEWHERE
FROM 17N-23N BETWEEN 79W-85W. A HIGH MOIST ENVIRONMENT IN THE SE
GULF IS COLLOCATED WITHIN AN AREA OF UPPER-LEVEL DIFFLUENCE
BETWEEN THE RIDGE OVER THE WESTERN BASIN AND A LOW CENTERED S OF
HISPANIOLA NEAR 16N69W. THIS AREA OF DIFFLUENCE IS SUPPORTING
SHOWERS AND TSTMS S OF 13N BETWEEN 75W-80W. THE UPPER-LEVEL LOW
IN THE EASTERN BASIN IS POSITIONED OVER A MODERATE MOIST
ENVIRONMENT AND SUPPORTS SCATTERED SHOWERS FROM 11N-16N BETWEEN
62W-69W. DRY AIR SUBSIDENCE OVER THE REMAINDER CENTRAL CARIBBEAN
SUPPORTS FAIR WEATHER. THE SURFACE TROUGH SHOULD CONTINUE MOVING
ACROSS THE YUCATAN TODAY AND ENTER THE BAY OF CAMPECHE ON THU
WHEN SOME DEVELOPMENT IS POSSIBLE. CLOUDINESS AND SHOWERS
ASSOCIATED WITH A BROAD AREA OF LOW PRESSURE CURRENTLY CENTERED
ABOUT 650 MILES EAST OF THE LEEWARD ISLANDS MAY START GENERATING
SHOWERS OVER THE FAR E-NE CARIBBEAN AS SOON AS TONIGHT AS IT
CONTINUES TO MOVE WESTWARD.

HISPANIOLA...
A DRY AIRMASS MOVES ACROSS THE ISLAND THIS AFTERNOON...THUS
SUPPORTING FAIR WEATHER. THESE WEATHER CONDITIONS ARE EXPECTED
TO LAST UNTIL EARLY THIS EVENING. MOISTURE WILL BE ADVECTED FROM
THE EASTERN CARIBBEAN LATE TONIGHT WHICH ALONG WITH AN UPPER-
LEVEL LOW MAY ENHANCE SHOWERS AND TSTMS THROUGHOUT THURSDAY.

ATLANTIC OCEAN...
THE PRIMARY CONCERNS FOR THE ATLC BASIN ARE TROPICAL STORM
GABRIELLE IN THE W ATLC AND HURRICANE HUMBERTO IN THE E ATLC.
SEE SPECIAL FEATURES ABOVE. AN UPPER-LEVEL LOW CENTERED OVER
CENTRAL FLORIDA SUPPORTS A SURFACE TROUGH THAT EXTENDS FROM
30N73W TO THE BAHAMAS NEAR 24N78W. SCATTERED SHOWERS ASSOCIATED
WITH THIS SURFACE AND UPPER-LEVEL FEATURES ARE FROM 26N-30N W OF
74W. AN AREA OF SIMILAR CONVECTION IS FROM 22N-24N BETWEEN 77W-
80W BEING SUPPORTED BY UPPER-LEVEL DIFFLUENCE FROM THE
AFOREMENTIONED LOW AND THE RIDGE OVER THE WESTERN CARIBBEAN. A
SURFACE TROUGH ABOUT 650 MILES EAST OF THE LEEWARD ISLANDS
EXTENDS AN AXIS FROM 20N59W TO A 1012 MB LOW NEAR 17N50W.
SCATTERED MODERATE CONVECTION IS WITHIN 150 NM SW OF THE AXIS.
THE REMAINDER OF THE ATLC IS DOMINATED BY A WEAK SURFACE RIDGE
ANCHORED BY A 1033 MB HIGH 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

$$
RAMOS


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