[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 271756
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT TUE SEP 27 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 15.8N 35.3W AT 27/1500
UTC OR ABOUT 650 NM W OF THE CAPE VERDE ISLANDS MOVING NW AT 4
KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1003 MB. MAXIMUM
SUSTAINED WIND SPEED IS 40 KT WITH GUSTS TO 50 KT. SCATTERED
MODERATE CONVECTION REMAINS SHEARED TO THE EAST OF PHILIPPE FROM
15N-18N BETWEEN 31W-34W. SEE LATEST NHC FORECAST/ADVISORY UNDER
AWIPS/WMO HEADERS MIATCMAT2/WTNT22 KNHC FOR MORE DETAILS.

THE REMNANTS OF OPHELIA ARE ANALYZED AS A 1010 MB LOW CENTERED
E-NE OF THE LEEWARD ISLANDS NEAR 18N60W. DEEP CONVECTION
CONTINUES TO SUSTAIN ITSELF SOUTH AND SOUTHEAST OF THE LOW
CENTER BENEATH A MIDDLE TO UPPER LEVEL RIDGE CENTERED NEAR
18N58W. SCATTERED TO NUMEROUS MODERATE AND ISOLATED STRONG
CONVECTION IS FROM 14N-20N BETWEEN 56W-62W. THE LOW IS FORECAST
TO LINGER NE OF THE LEEWARD ISLANDS AND SLOWLY DRIFT W-NW OVER
THE NEXT FEW DAYS. LOCALLY HEAVY RAINFALL IS EXPECTED OVER
PORTIONS OF THE NORTHERN LEEWARD ISLANDS THROUGH WEDNESDAY.

...TROPICAL WAVES...

TROPICAL WAVE IS ANALYZED FROM 03N22W TO 10N21W MOVING W AT 10
KT. EXAMINING A METEOSAT-9 HOVMOLLER DIAGRAM FROM THE PAST FEW
DAYS AND LOW-LEVEL STREAMLINE MODEL DATA...ENERGY ASSOCIATED
WITH THE WAVE CONTINUES TO SHOW CYCLONIC TURNING OF THE
LOW-LEVEL CLOUD FIELD BETWEEN 19W-24W. NO SIGNIFICANT DEEP
CONVECTION IS OBSERVED ON SATELLITE IMAGERY IN THE VICINITY OF
THE WAVE AXIS.

TROPICAL WAVE PREVIOUSLY ANALYZED ALONG 48W HAS SHOWED
SIGNIFICANT WEAKENING OVER THE PAST 24-48 HOURS AND ANY REMNANT
ENERGY CONTINUES TO DRIFT SLOWLY WESTWARD. A SURFACE TROUGH
REMAINS ANALYZED FROM 14N46W TO 10N51W INDICATING CONVERGENCE OF
LOW-LEVEL MOISTURE GENERATING ISOLATED SHOWERS FROM 12N-15N
BETWEEN 44W-49W.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 13N17W TO
10N19W. NO SIGNIFICANT CONVECTION IS NOTED ALONG THIS FEATURE.

...DISCUSSION...

GULF OF MEXICO...
UPPER LEVEL WESTERLY FLOW DOMINATES ACROSS THE GULF THIS
AFTERNOON BETWEEN AN UPPER LEVEL LOW CENTERED OVER THE GREAT
LAKES REGION AND AN ANTICYCLONIC CIRCULATION CENTERED OVER
SOUTHERN MEXICO NEAR 18N91W. WATER VAPOR IMAGERY INDICATES A
MODERATELY DRY AIRMASS IS IN PLACE ACROSS MUCH OF THE GULF N OF
23N. AT THE SURFACE...A RIDGE EXTENDS FROM THE SW NORTH ATLC
WATERS TO A 1015 MB HIGH CENTERED NEAR 25N87W. A WEAKNESS WITHIN
THE RIDGE...ANALYZED AS A SURFACE TROUGH FROM 25N82W TO
30N83W...IS PROVIDING A SUBTLE WIND SHIFT NOTED IN AN EARLY
MORNING WINDSAT PASS WHERE WINDS REMAIN GENERALLY LIGHT. FARTHER
SW OVER THE SW GULF WATERS...A SURFACE TROUGH EXTENDS ALONG
22N91W TO 19N94W AND ALONG WITH AN UPPER LEVEL DIFFLUENT
ENVIRONMENT ALOFT IS GENERATING SCATTERED SHOWERS AND ISOLATED
TSTMS S OF 22N BETWEEN 90W-95W. THE REMAINDER OF THE GULF IS
EXPERIENCING CLEAR SKIES AND FAIR WEATHER CONDITIONS AS THE HIGH
AND ASSOCIATED RIDGE IS FORECAST TO REMAIN QUASI-STATIONARY OVER
THE CENTRAL GULF THROUGH THURSDAY.

CARIBBEAN SEA...
AN UPPER LEVEL ANTICYCLONIC CIRCULATION IS CENTERED OVER
SOUTHERN MEXICO NEAR 18N91W AND IS PROVIDING MUCH OF THE WESTERN
AND CENTRAL CARIBBEAN W OF 67W WITH NORTHEAST TO EASTERLY FLOW
ALOFT. THIS IN TURN IS MAINTAINING MOSTLY FAIR WEATHER
CONDITIONS AND CLEAR SKIES...HOWEVER...GIVEN AN UPPER LEVEL
DIFFLUENT ENVIRONMENT AND AREAS OF TRADEWIND CONVERGENCE...
ISOLATED SHOWERS ARE OCCURRING FROM 14N-18N BETWEEN 71W-84W.
ALSO...THE MONSOON TROUGH AXIS EXTENDS FROM CENTRAL NICARAGUA
NEAR 13N85W TO 13N77W. LOW-LEVEL CYCLONIC FLOW AND MIDDLE TO
UPPER LEVEL LIFT PROVIDED BY A WEAK UPPER LEVEL LOW CENTERED
NEAR 12N84W ARE GENERATING SCATTERED SHOWERS AND ISOLATED TSTMS
FROM 08N-14N BETWEEN 80W-84W. THE REMAINDER OF THE EASTERN
CARIBBEAN FALLS UNDER THE INFLUENCE OF THE REMNANTS OF OPHELIA
WHICH ARE ANALYZED AS A 1010 MB LOW CENTERED E-NE OF THE LEEWARD
ISLANDS NEAR 18N60W AND IS NOTED ABOVE IN THE SPECIAL FEATURES
SECTION. RADAR IMAGERY FROM GUADELOUPE INDICATES THAT
PRECIPITATION REMAINS WITHIN 60-90 NM TO THE EAST OF THE LESSER
ANTILLES...AND GIVEN THE SLOW MOVEMENT W-NW OVER THE NEXT 24-36
HOURS...LOCALLY HEAVY RAINFALL IS EXPECTED OVER THE LEEWARD
ISLANDS THROUGH WEDNESDAY.

ATLANTIC OCEAN...
A NARROW UPPER LEVEL RIDGE EXTENDS FROM EASTERN CUBA OVER THE SE
BAHAMAS TO 34N72W. THIS RIDGE AXIS LIES EAST OF AN UPPER LEVEL
LOW CENTERED OVER THE GREAT LAKES REGION. SOUTHWESTERLY UPPER
LEVEL FLOW BETWEEN THESE TWO UPPER LEVEL FEATURES IS PROVIDING
FOR AN UPPER LEVEL DIFFLUENT ENVIRONMENT WHICH IS GENERATING
SCATTERED SHOWERS AND ISOLATED TSTMS WITHIN A NARROW CORRIDOR OF
THE SW NORTH ATLC WATERS FROM 22N TO BEYOND 32N BETWEEN 74W-80W.
EAST OF THE UPPER LEVEL RIDGE...AN UPPER LEVEL TROUGH AXIS IS
FROM 29N69W TO 18N65W AND EVEN THOUGH A RIDGE DOMINATES AT THE
SURFACE...MIDDLE TO UPPER LEVEL DYNAMICS EAST OF THE UPPER LEVEL
TROUGH AXIS IS GENERATING ISOLATED SHOWERS AND TSTMS FROM
20N-29N BETWEEN 65W-69W. THE ONLY REMAINING AREA OF ACTIVE
WEATHER WITHIN THE OFFSHORE ZONES IS THE REMNANTS OF OPHELIA
FOCUSED AROUND A 1010 MB LOW CENTERED NEAR 18N60W. SCATTERED TO
NUMEROUS SHOWERS AND SCATTERED STRONG TSTMS ARE OCCURRING
14N-20N BETWEEN 56W-62W. FINALLY...AN UPPER LEVEL TROUGH AXIS
DIPS INTO THE DISCUSSION AREA ALONG 32N30W TO 23N36W TO 17N49W
ACROSS THE EASTERN AND CENTRAL ATLC THAT SUPPORTS WEAK SURFACE
TROUGHING N OF 22N BETWEEN 40W-50W. ISOLATED SHOWERS ARE
OCCURRING EAST OF THIS AREA N OF 27N BETWEEN 25W-37W. THE
REMAINDER OF THE EASTERN ATLC IS UNDER THE INFLUENCE OF A
SURFACE RIDGE AXIS EXTENDING FROM A WESTERN EUROPEAN HIGH ACROSS
THE IBERIAN PENINSULA TO THE CANARY AND MADEIRA ISLANDS TO THE
CAPE VERDE ISLANDS.

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

$$
HUFFMAN




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