[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 031800
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT MON OCT 03 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...

OPHELIA BECOMES A POST-TROPICAL CYCLONE AND THE LAST ADVISORY
IS ISSUED AT 03/1500 UTC. AT THIS TIME...OPHELIA IS CENTERED
NEAR 48.1N 52.0W OR ABOUT 95 NM...175 KM NNE OF CAPE RACE
NEWFOUNDLAND MOVING E-NE OR 60 DEGREES AT 32 KT. ESTIMATED
MINIMUM CENTRAL PRESSURE IS 996 MB. MAXIMUM SUSTAINED WIND SPEED
IS 50 KT WITH GUSTS TO 60 KT. SEE LATEST NHC FORECAST/ADVISORY
UNDER AWIPS/WMO HEADERS MIATCMAT1/WTNT21 KNHC FOR MORE DETAILS.

THE 1248 UTC ASCAT PASS HELPED TO RE-LOCATED THE CENTER OF
PHILIPPE AND ALSO PROVIDED OBSERVATIONS OF MAXIMUM WINDS NEAR
NEAR 55 KT. AT 03/1500 UTC...TROPICAL STORM PHILIPPE IS CENTERED
NEAR 24.8N 55.8W MOVING W-SW AT 10 KT. ESTIMATED MINIMUM CENTRAL
PRESSURE IS 998 MB. MAXIMUM SUSTAINED WIND SPEED IS 55 KT WITH
GUSTS TO 65 KT. NOW...THE CENTER OF PHILIPPE IS ONCE AGAIN NEAR
THE DEEPEST CONVECTION. THE CYCLONE HAS BEEN ABLE TO MAINTAIN
ITS INTENSITY...AND EVEN STRENGTHEN DESPITE THE HOSTILE
CONDITIONS. SEE LATEST NHC FORECAST/ ADVISORY UNDER AWIPS/WMO
HEADERS MIATCMAT2/WTNT22 KNHC FOR MORE DETAILS.

...TROPICAL WAVES...

TROPICAL WAVE IS ANALYZED ALONG 31W FROM 08N TO 17N MOVING W AT
10-15 KT. VISIBLE METEOSAT-9 SATELLITE IMAGERY INDICATES SOME
CYCLONIC TURNING OF THE LOW-LEVEL CLOUDS WHERE THE WAVE MEETS
THE ITCZ AXIS. IN ADDITION...THE 1112 UTC ASCAT PASS CONFIRMS
THE PRESENCE OF THE WAVE WITH E TO SE WINDS E OF THE AXIS AND NE
WINDS W OF THE WAVE AXIS. THIS SYSTEM COINCIDES WITH A SURGE OF
MOISTURE OBSERVED IN THE TOTAL PRECIPITABLE WATER.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR DAKAR
SENEGAL TO 14N20W. THE INTERTROPICAL CONVERGENCE ZONE AXIS
CONTINUES FROM 14N20W TO 13N29W TO 07N45W TO 06N57W. SCATTERED
MODERATE TO ISOLATED STRONG CONVECTION IS MORE CONCENTRATED NEAR
THE INTERSECTION OF THE WAVE AND THE ITCZ AXIS AND COVERS THE
AREA FROM 07N TO 12N BETWEEN 28W AND 33W. SCATTERED MODERATE
CONVECTION IS ALSO NOTED S OF THE ITCZ TO 10N BETWEEN 22W AND
25W. SIMILAR CONVECTION IS WITHIN 60 NM EITHER SIDE OF THE ITCZ
AXIS FROM 34W TO 46W.

...DISCUSSION...

GULF OF MEXICO...
HIGH PRES CENTERED OVER ARKANSAS EXTENDS A RIDGE OVER MOST OF
THE GULF REGION. ANOTHER 1021 MB HIGH PRES IS OVER MEXICO NEAR
22N98W. THE HIGH PRES N OF THE AREA IS FORECAST TO STRENGTHEN ON
TUE WITH NE WINDS GRADUALLY INCREASING OVER THE SE PORTION OF
THE GULF. THE PRES GRADIENT WILL FURTHER TIGHTEN RESULTING IN NE
WINDS OF 20 TO 25 KT COVERING THE ENTIRE EASTERN HALF OF THE
GULF BY THU NIGHT. VISIBLE SATELLITE IMAGERY SHOWS SCATTERED TO
BROKEN STRATOCUMULUS CLOUDS ASSOCIATED WITH THE ADVECTION OF
COOLER AIR OVER WARM WATERS. ALOFT...THE GULF IS UNDER THE
INFLUENCE OF A DEEP LAYER TROUGH THAT EXTENDS FROM AN UPPER
LEVEL LOW CENTERED OVER THE MID-ATLC AND NORTHEASTERN U.S. TO
THE EASTERN PORTION OF THE BAY OF CAMPECHE. MODERATE TO STRONG
SUBSIDENCE DOMINATES THE ENTIRE REGION WITH THE EXCEPTION OF THE
EASTERN PORTION OF THE BAY OF CAMPECHE WHERE THE BASE OF THE
AFOREMENTIONED TROUGH IS GENERATING A FEW SHOWERS AND TSTMS.

CARIBBEAN SEA...
A LARGE AREA OF SHOWERS AND TSTMS IS OVER THE NW CARIBBEAN VERY
CLOSE TO THE CAYMAN ISLANDS WHERE TSTMS AND GUSTY WINDS HAVE
BEEN REPORTED. THIS CONVECTIVE ACTIVITY IS ASSOCIATED WITH A
SURFACE TROUGH THAT EXTENDS ALONG 83W FROM 15N TO THE ISLE OF
YOUTH CUBA. THIS TROUGH IS EMBEDDED WITHIN AN AREA OF DEEP
LAYERED MOISTURE AS DEPICTED ON THE TWD ANIMATION. COMPUTER
MODEL HAS THIS MOISTURE DRIFTING WWD OVER THE NEXT COUPLE OF
DAYS. A STATIONARY FRONT STRETCHES ACROSS WESTERN CUBA AND THE
FAR NW CARIBBEAN ALONG 20N87W 17N88W. SOME SHOWERS ARE ALSO
ALONG THE FRONTAL BOUNDARY. IT IS NORMAL FOR THIS TIME OF THE
YEAR TO SEE THIS TYPE OF WEATHER PATTERN ACROSS THE NW
CARIBBEAN. EASTERLY TRADES IN THE 15-20 KT RANGE DOMINATE THE E
AND S CENTRAL CARIBBEAN...HIGHER NEAR THE COAST OF COLOMBIA
WHERE FEW SHIP OBSERVATIONS AND AN EARLIER ASCAT PASS SHOWED
WINDS OF 20-25 KT. ALOFT...AN UPPER LEVEL RIDGE AXIS EXTENDS
FROM NORTHERN CENTRAL AMERICA TO NEAR JAMAICA. NORTH OF THE
RIDGE AXIS...MOIST AND UNSTABLE SOUTHWESTERLY FLOW ALOFT
DOMINATES. UPPER DIFFLUENCE ASSOCIATED WITH THIS RIDGE IS
HELPING TO INDUCE THE AREA OF NUMEROUS SHOWERS AND SCATTERED
TSTMS OVER MUCH OF THE NW CARIBBEAN N OF 15N W OF 80W. SCATTERED
SHOWERS AND TSTMS ARE NOTED OVER THE SW CARIBBEAN JUST N OF THE
MONSOON TROUGH WHICH CROSSES PANAMA TO A 1010 MB LOW PRES NEAR
11N76W.

ATLANTIC OCEAN...
A STATIONARY FRONT ENTERS THE AREA NEAR 31N66W THE CONTINUES SW
THROUGH WESTERN CUBA INTO THE NW CARIBBEAN. SCATTERED SHOWERS
AND ISOLATED TSTMS ARE ALONG THE FRONTAL BOUNDARY WHICH IS
SUPPORTED BY THE ABOVE MENTIONED UPPER-LEVEL LOW/TROUGH. THE
FRONT IS FORECAST TO MEANDER OVER THE SW N ATLC AND GRADUALLY
DISSIPATE. FURTHER EAST...IS TROPICAL STORM PHILIPPE FORECAST TO
MOVE ON A WEST-SOUTHWEST TRACK FOLLOWED BY A TURN TOWARD THE
WEST-NORTHWEST WITH A DECREASE IN FORWARD SPEED AS HIGH PRES N
OF THE TROPICAL CYCLONE WEAKENS. THIS HIGH PRES IS CURRENTLY
SITUATED NEAR 39N46W AND HAS A RIDGE TO THE SW TO THE NE
CARIBBEAN AND ANOTHER RIDGE TO THE SE TO NEAR 21N36W. PHILIPPE
IS IN BETWEEN THESE RIDGES. THE REMNANTS OF THE FRONT ARE
EXPECTED TO MERGE WITH TROPICAL CYCLONE PHILIPPE BY LATE WED.
A LOW PRES SYSTEM IS OVER THE AZORES WITH A TROUGH EXTENDING SSW
INTO THE FORECAST AREA ALONG 31N28W 24N31W. A STRONG UPPER-LEVEL
LOW LOCATED NEAR 34N27W WITH A TROUGH EXTENDING SW TO THE
WINDWARD ISLANDS SUPPORTS THE SURFACE LOW PRES/TROUGH. NEAR THE
BASE OF THIS TROUGH THERE ARE SOME SHOWERS OVER THE WINDWARD
ISLANDS AND REGIONAL WATERS. AN UPPER-LEVEL RIDGE IS ALONG THE
WEST COAST OF AFRICA.

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

$$
GR





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