[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 261746
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT MON SEP 26 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...SPECIAL FEATURES...

TROPICAL STORM PHILIPPE IS CENTERED NEAR 15.2N 34.2W AT 26/1500
UTC OR ABOUT 590 NM W OF THE CAPE VERDE ISLANDS MOVING NW AT 10
KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 997 MB. MAXIMUM
SUSTAINED WIND SPEED IS 50 KT WITH GUSTS TO 60 KT. SCATTERED
MODERATE CONVECTION REMAINS CLUSTERED NEAR THE CENTER OF
PHILIPPE FROM 10N-16N BETWEEN 31W-36W. SEE LATEST NHC FORECAST/
ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT2/WTNT22 KNHC FOR MORE
DETAILS.

THE REMNANTS OF OPHELIA WHICH ARE ANALYZED AS A 1011 MB LOW
CENTERED E-NE OF THE LEEWARD ISLANDS NEAR 18N58W. A SURFACE
TROUGH EXTENDS WESTWARD FROM THE LOW CENTER TO 16N65W MORE AS A
LOW-LEVEL CONVERGENCE BOUNDARY OF FLOW INTO THE LOW CENTER WHICH
IS PROVIDING FOCUS FOR ISOLATED SHOWERS AND TSTMS WITHIN 120 NM
S OF THE BOUNDARY. FURTHERMORE...CLOSER TO THE LOW CENTER...
SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS FROM
15N-21N BETWEEN 55W-61W. THE LOW IS FORECAST TO LINGER NE OF THE
LEEWARD ISLANDS AND SLOWLY DRIFT W-NW OVER THE NEXT FEW DAYS.

...TROPICAL WAVES...

TROPICAL WAVE IS ANALYZED FROM 11N45W TO 17N46W MOVING W AT 5-10
KT. THE WAVE CONTINUES TO EXHIBIT WEAK LOW-LEVEL CYCLONIC
TURNING IN THE VICINITY OF THE WAVE AXIS AS NOTED IN THE CLOUD
FIELD SURROUNDING THE WAVE...HOWEVER...VERY DRY AIR ALOFT DUE TO
NORTHWESTERLY UPPER LEVEL FLOW CONTINUES TO SUPPRESS ANY
SIGNIFICANT DEEP CONVECTION.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 14N17W
ALONG 11N20W TO 11N25W. WIDELY SCATTERED MODERATE CONVECTION IS
FROM 04N-09N BETWEEN 21W-26W...AND FROM 10N-16N BETWEEN 23W-26W.

...DISCUSSION...

GULF OF MEXICO...
UPPER LEVEL WESTERLY FLOW DOMINATES ACROSS THE GULF THIS
AFTERNOON BETWEEN A VIGOROUS UPPER LEVEL LOW CENTERED OVER THE
GREAT LAKES REGION AND AN ANTICYCLONIC CIRCULATION CENTERED OVER
SOUTHERN MEXICO NEAR 18N91W. WATER VAPOR IMAGERY INDICATES A DRY
AIRMASS IS IN PLACE ACROSS MUCH OF THE GULF W OF 85W. E OF 85W
ALOFT...MIDDLE TO UPPER LEVEL MOISTURE CONTINUES TO ADVECT
NORTHWARD AMID A DIFFLUENT PATTERN ALOFT SE OF THE UPPER LEVEL
LOW. THIS UPPER LEVEL PATTERN ALONG WITH A WEAK SURFACE TROUGH
ANALYZED FROM 26N84W TO 30N84W IS PROVIDING FOCUS FOR SCATTERED
SHOWERS AND TSTMS N OF 24N E OF 85W...INCLUDING PORTIONS OF THE
FLORIDA PENINSULA. THE REMAINDER OF THE GULF IS UNDER CLEAR
SKIES AND FAIR WEATHER CONDITIONS AS GENERALLY SE TO S WINDS ARE
EXPECTED TO PERSIST OVER THE WESTERN GULF THROUGH TUESDAY.

CARIBBEAN SEA...
AN UPPER LEVEL ANTICYCLONIC CIRCULATION IS CENTERED OVER
SOUTHERN MEXICO NEAR 18N91W AND IS PROVIDING MUCH OF THE WESTERN
CARIBBEAN W OF 76W WITH NORTHEASTERLY FLOW ALOFT. THIS IN TURN
IS MAINTAINING FAIR WEATHER CONDITIONS AND MOSTLY CLEAR SKIES N
OF 16N W OF 76W. S OF 16N ACROSS THE SW CARIBBEAN...A PORTION OF
THE E PACIFIC MONSOON TROUGH EXTENDS FROM NORTHERN COSTA RICA
NEAR 10N83W TO 12N74W. LOW-LEVEL CYCLONIC FLOW AND MIDDLE TO
UPPER LEVEL LIFT PROVIDED BY AN UPPER LEVEL TROUGH AXIS ALONG
14N BETWEEN 70W-80W IS GENERATING SCATTERED TO NUMEROUS SHOWERS
AND SCATTERED STRONG TSTMS FROM 10N-15N BETWEEN 73W-79W. THE
REMAINDER OF THE EASTERN CARIBBEAN FALLS UNDER THE INFLUENCE OF
THE REMNANTS OF OPHELIA WHICH ARE ANALYZED AS A 1011 MB LOW
CENTERED E-NE OF THE LEEWARD ISLANDS NEAR 18N58W AND ARE NOTED
ABOVE IN THE SPECIAL FEATURES SECTION.

ATLANTIC OCEAN...
A NARROW UPPER LEVEL RIDGE EXTENDS FROM THE NW CARIBBEAN OVER
THE FLORIDA STRAITS TO 32N76W. THIS RIDGE AXIS LIES EAST OF A
VIGOROUS UPPER LEVEL LOW CENTERED OVER THE GREAT LAKES REGION.
SOUTHWESTERLY UPPER LEVEL LOW BETWEEN THESE TWO UPPER LEVEL
FEATURES IS ADVECTING TROPICAL MOISTURE NORTHWARD ACROSS MUCH OF
THE FLORIDA PENINSULA AND FAR SW NORTH ATLC WATERS GENERATING
SCATTERED SHOWERS AND TSTMS W OF A LINE FROM 23N78W TO 32N76W.
THE REMAINDER OF THE SW NORTH ATLC IS UNDER THE INFLUENCE OF A
RIDGE ANCHORED BY A 1021 MB HIGH CENTERED NEAR BERMUDA. HOWEVER
ALOFT...AN ELONGATED UPPER LEVEL LOW IS CENTERED NEAR 25N71W AND
CONTINUES TO ADVECT TROPICAL MOISTURE NORTHWARD TO 30N BETWEEN
63W-71W. SCATTERED SHOWERS AND ISOLATED TSTMS ARE RESULTING FROM
UPPER LEVEL DIFFLUENT FLOW FROM 21N-26N BETWEEN 63W-71W. THE
ONLY REMAINING AREA OF ACTIVE WEATHER WITHIN THE OFFSHORE ZONES
IS THE REMNANTS OF OPHELIA FOCUSED AROUND A 1011 MB LOW CENTERED
NEAR 18N58W. SCATTERED SHOWERS AND ISOLATED TSTMS CONTINUE TO
REMAIN DISORGANIZED NEAR THE LOW OCCURRING FROM 15N-21N BETWEEN
53W-61W. FINALLY...AN UPPER LEVEL TROUGH AXIS DIPS INTO THE
DISCUSSION AREA ALONG 32N37W TO 25N42W TO 22N51W ACROSS THE
CENTRAL ATLC AND SUPPORTS A COLD FRONT ANALYZED FROM 32N35W
27N38W 24N46W TO 26N54W. ISOLATED SHOWERS ARE OCCURRING WITHIN
120 NM OF THE FRONT N OF 23N AND WITHIN 150 NM E OF THE FRONT N
OF 30N. PRE-FRONTAL DYNAMICS WELL EAST OF THE FRONT ARE
GENERATING SCATTERED SHOWERS AND ISOLATED TSTMS N OF 26N BETWEEN
26W-32W. THE REMAINDER OF THE EASTERN ATLC IS UNDER THE
INFLUENCE OF A SURFACE RIDGE ANCHORED BY A 1022 MB HIGH CENTERED
SE OF THE IBERIAN PENINSULA NEAR 35N13W. THE RIDGE AXIS EXTENDS
FROM THE HIGH S-SW OVER THE CANARY ISLANDS TO NORTH OF THE CAPE
VERDE ISLANDS NEAR 20N28W.

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

$$
HUFFMAN




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