[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 010555
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT SAT OCT 01 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0545 UTC.

...SPECIAL FEATURES...

MAJOR HURRICANE OPHELIA IS CENTERED NEAR 26.2N 63.1W AT 01/0600
UTC OR ABOUT 385 MI...615 KM SSE OF BERMUDA MOVING N AT 15 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 956 MB. MAXIMUM SUSTAINED
WIND SPEED IS 105 KT WITH GUSTS TO 130 KT. SCATTERED MODERATE TO
ISOLATED STRONG CONVECTION IS FROM 25N-30N BETWEEN 60W-65W.
LITTLE CHANGE WAS MADE TO THE OFFICIAL FORECAST FOR THE FIRST 24
TO 36 HOURS AS MODEL GUIDANCE IS IN VERY GOOD AGREEMENT. SEE
LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS
MIATCMAT1/WTNT21 KNHC FOR MORE DETAILS.

TROPICAL STORM PHILIPPE IS CENTERED NEAR 24.0N 46.4W AT 01/0300
UTC OR ABOUT 1255 MI...2020 KM ESE OF BERMUDA MOVING NW AT 8 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 1004 MB. MAXIMUM SUSTAINED
WIND SPEED IS 45 KT WITH GUSTS TO 55 KT. SCATTERED MODERATE TO
ISOLATED STRONG CONVECTION IS FROM 21N-26N BETWEEN 44W-48W. SEE
LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS
MIATCMAT2/WTNT22 KNHC FOR MORE DETAILS.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST OF MAURITANIA
NEAR 17N16W TO 7N30W. THE ITCZ AXIS EXTENDS FROM THIS POINT TO
NEAR 4N42W. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS
IN THE VICINITY OF THE MONSOON TROUGH FROM 3N-11N E OF 30W.
SIMILAR ACTIVITY OF WITHIN 130 NM ON EITHER SIDE OF THE ITCZ
AXIS W OF 33W.

...DISCUSSION...

GULF OF MEXICO...
WESTERLY FLOW ALOFT COVERS THE GULF WITH A 70 KT-PLUS SUB
TROPICAL JET STREAK DEVELOPING OVER THE NE BASIN. THIS FEATURE
IS LOCATED AT THE BASE OF AN UPPER LEVEL TROUGH/CUT OFF LOW
MOVING ACROSS THE ERN CONUS. THIS SCENARIO SUPPORTS A COLD FRONT
EXTENDING WSW ACROSS THE AREA FROM N OF TAMPA BAY FLORIDA NEAR
29N83W ALONG 26N90W TO BROWNSVILLE TEXAS NEAR 26N97W. THIS FRONT
CARRIES NO SIGNIFICANT CONVECTION...ONLY A THIN CLOUD LINE ALONG
THE AXIS. THERE IS... HOWEVER...AN AVERAGE 1O DEGREE FAHRENHEIT
DROP IN DEWPOINT DEPICTING THE DRIER AIRMASS BEHIND THE
BOUNDARY. ALSO ...MARINE OBSERVATIONS FROM SHIPS AND OIL
PLATFORMS OFF THE COAST OF LOUISIANA AND MISSISSIPPI INDICATED
GUSTY NNE WINDS RANGING FROM 25-30 KT N OF 27N BETWEEN 97W-93W.
STRONG SUBSIDENCE ALOFT IS IS NOTED BEHIND THE FRONT ON WATER
VAPOR IMAGERY...LEADING TO REMARKABLE CLEAR SKIES ON NIGHT
VISION SATELLITE IMAGERY THIS EVENING. SURFACE RIDGING WILL
BUILD ACROSS THE NRN GULF AS THE FRONT CONTINUES TO EXPAND ESE
ACROSS THE AREA. ELSEWHERE...SCATTERED SHOWERS ARE OVER THE WRN
BAY OF CAMPECHE W OF 93W S OF 22N. THIS AREA OF RELATIVELY WEAK
CONVECTION IS EXPECTED TO LINGER OVER THE NEXT 24 HOURS.

CARIBBEAN SEA...
MOSTLY DRY CONDITIONS ALOFT ARE OBSERVED ON WATER VAPOR IMAGERY
E OF 82W...PROVIDING A FAIR WEATHER ENVIRONMENT ACROSS MOST OF
THE BASIN WITH 5-15 KT EASTERLY TRADE WINDS. JUST A FEW ISOLATED
MODERATE TO HEAVY SHOWERS AND POSSIBLE THUNDERSTORMS ARE MOVING
ACROSS THE WINDWARD PASSAGE N OF 18N...GENERATED BY DIVERGENCE
ALOFT ASSOCIATED TO THE BASE OF A BROAD UPPER LEVEL TROUGH
MOVING OFF THE ERN CONUS SEABOARD. THIS AREA OF CONVECTION IS
EXPECTED TO LINGER OVER THE NEXT 24 HOURS. SIMILAR ACTIVITY IS
OBSERVED ACROSS THE IMMEDIATE COASTAL WATERS OF PANAMA AND
COLOMBIA BETWEEN 75W-82W...DUE TO CLOSE PROXIMITY TO THE MONSOON
TROUGH ANALYZED FROM NRN COSTA RICA INTO NRN COLOMBIA. ALTHOUGH
THE SHOWER ACTIVITY ACROSS THE GULF OF HONDURAS AND THE COAST OF
BELIZE HAS DECREASE IN THE PAST 6-12 HOURS...COMPUTER MODELS
SUGGEST MORE CONVECTION DEVELOPING IN THIS REGION DURING THE
LATE MORNING AND EARLY AFTERNOON HOURS OF SATURDAY.

ATLANTIC OCEAN...
WATER VAPOR IMAGERY SHOWS AN UPPER LEVEL TROUGH/CUT OFF LOW
MOVING OFF THE ERN CONUS SEABOARD. THIS SYSTEM SUPPORTS A COLD
FRONT EXTENDING 30-50 NM OFF THE COAST OF THE CAROLINAS AND
GEORGIA INTO NORTHERN FLORIDA NEAR JACKSONVILLE. THE
CONVECTION...HOWEVER...IS WELL REMOVED E OF THE FRONT...N OF 20N
BETWEEN 70W-75W. SCATTERED HEAVY SHOWERS AND THUNDERSTORMS ARE
OBSERVED IN THIS REGION...BETTER ASSOCIATED WITH THE DIVERGENCE
FLOW ALOFT FROM THE UPPER LEVEL ENVIRONMENT. AN UPPER LEVEL
RIDGE OF HIGH PRESSURE DOMINATES THE N CENTRAL AND WRN ATLC.
ANOTHER UPPER TROUGH SWINGS ACROSS THE ERN N ATLC SUPPORTING A
COLD FRONT THAT ENTERS THE DISCUSSION AREA FROM 32N21W TO
26N33W. AN EARLIER ASCAT PASS WENT OVER THE FRONT INDICATING
15-20 KT NNW WINDS BEHIND THE BOUNDARY. CURRENTLY...NIGH VISION
SATELLITE IMAGERY REVEALED NO SIGNIFICANT CONVECTION OCCURRING
IN THE VICINITY OF THE FRONT DUE TO A MID-UPPER LEVEL SAHARAN
AIRMASS MOVING OFF WRN AFRICA. OTHERWISE...ASIDE T.S. PHILIPPE
AND HURCN OPHELIA...THE ATLC DISCUSSION AREA REMAINS UNDER FAIR
WEATHER PROVIDED BY A NEARLY STNRY 1030 MB HIGH CENTERED NEAR
38N45W THAT IS ASSOCIATED TO THE CENTRAL/WRN N ATLC UPPER RIDGE.

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

$$

GARCIA



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