[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 011140
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1015 UTC.

...SPECIAL FEATURES...

MAJOR HURRICANE OPHELIA IS CENTERED NEAR 28.6N 63.0W AT 01/1200
UTC OR ABOUT 240 NM SSE OF BERMUDA MOVING N AT 15 KT. ESTIMATED
MINIMUM CENTRAL PRESSURE IS 952 MB. MAXIMUM SUSTAINED WIND SPEED
IS 105 KT WITH GUSTS TO 130 KT. SCATTERED MODERATE TO ISOLATED
STRONG CONVECTION IS FROM 26N-31N BETWEEN 59W-65W. OPHELIA IS
FORECAST TO CONTINUE MOVING NORTHWARD FOR THE NEXT 12 HOURS OR
SO...AND THEN GRADUALLY TURN TOWARD THE NORTHEAST AND ACCELERATE
UNDER THE INFLUENCE OF SOUTHWESTERLY FLOW AHEAD OF THE UPPER
TROUGH MOVING OFF THE ERN CONUS SEABOARD. SEE THE LATEST NHC
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT1/WTNT21 KNHC
FOR MORE DETAILS.

TROPICAL STORM PHILIPPE IS CENTERED NEAR 24.3N 47.4W AT 01/0900
UTC OR ABOUT 1190 MI...1920 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-27N BETWEEN 44W-49W. THE
TROPICAL STORM IS STILL MOVING NORTHWESTWARD AT ABOUT 8 KT.
PHILIPPE IS FORECAST TO GRADUALLY TURN TOWARD THE WEST DURING THE
NEXT FEW DAYS AS IT MOVES TO THE SOUTH OF A STRONG SUBTROPICAL
RIDGE. 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 ERN CENTRAL 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 28N83W ALONG 25N90W TO BROWNSVILLE TEXAS NEAR 26N97W. THIS
FRONT CARRIES NO SIGNIFICANT CONVECTION...ONLY A THIN CLOUD LINE
CAN BE TRACKED ALONG THE AXIS. THERE IS...HOWEVER...AN AVERAGE
2O 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 MORNING. 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 BETWEEN 74W-76W...GENERATED
BY DIVERGENCE ALOFT ASSOCIATED TO THE RIGHT-REAR QUADRANT OF AN
JET STREAK EMBEDDED IN THE BROAD UPPER LEVEL TROUGH THAT IS
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 GULF OF HONDURAS AND THE COAST OF BELIZE S
OF 19N W OF 85W DUE TO CONVERGING FLOW AND ELEVATED VALUES OF
MOISTURE NOTED ON TOTAL PRECIPITABLE WATER PRODUCT. ISOLATED
WEAK CONVECTION IS ALSO 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. COMPUTER MODELS SUGGEST MORE CONVECTION DEVELOPING IN
THIS REGION DURING THE LATE MORNING AND EARLY AFTERNOON HOURS.

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 60-90 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 69W-75W. SCATTERED HEAVY SHOWERS AND THUNDERSTORMS ARE
OBSERVED IN THIS REGION...BETTER ASSOCIATED TO THE DIVERGENCE
FLOW ALOFT FROM THE RIGHT-REAR QUADRANT OF A JET STREAK EMBEDDED
IN THE UPPER LEVEL ENVIRONMENT. AN UPPER LEVEL RIDGE OF HIGH
PRESSURE DOMINATES THE N CENTRAL AND WRN N ATLC. ANOTHER UPPER
TROUGH SWINGS ACROSS THE ERN N ATLC SUPPORTING A COLD FRONT THAT
ENTERS THE DISCUSSION AREA FROM 32N19 TO 26N28W. AN EARLIER
ASCAT PASS WENT OVER THE FRONT INDICATING 15-20 KT NNW WINDS
BEHIND THE BOUNDARY. THE FIRST VISIBLE PICTURES OF THE DAY
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 37N45W THAT IS
ASSOCIATED TO THE CENTRAL/WRN N ATLC UPPER RIDGE MENTIONED ABOVE.

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

$$
GARCIA




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