[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 222348
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT MON OCT 22 2012

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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2245 UTC.

...SPECIAL FEATURES...

TROPICAL DEPRESSION EIGHTEEN IS NOW TROPICAL STORM SANDY. AS OF
23/0000 UTC...SANDY IS CENTERED NEAR 12.7N 78.7W...OR ABOUT 335
NM SSW OF KINGSTON JAMAICA. THE STORM IS MOMENTARILY STATIONARY
WITH A 24 HOUR POSITION JUST SLIGHTLY TO THE NORTH. MINIMUM
CENTRAL PRESSURE IS 998 MB. MAXIMUM SUSTAINED WIND SPEEDS ARE 40
KT WITH GUSTS TO 50 KT. A TROPICAL STORM WATCH HAS BEEN PLACED
FOR JAMAICA AND HAITI. SEE LATEST NHC INTERMEDIATE PUBLIC
ADVISORY UNDER AWIPS/WMO HEADERS MIATCPAT3/WTNT33 KNHC AND THE
FULL FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT3/WTNT23
KNHC FOR MORE DETAILS. SCATTERED MODERATE/STRONG CONVECTION IS
ACROSS THE SW CARIBBEAN FROM 10N-13N BETWEEN 76W-83W...FROM
13N-16N BETWEEN 72W-79W. ACTIVITY ALSO SPREADS FARTHER NORTH AND
EAST ACROSS HISPANIOLA AND EASTERN CUBA.

TROPICAL DEPRESSION NINETEEN HAS FORMED AS OF 22/2100 UTC. T.D.
19 IS CENTERED NEAR 22.3N 51.7W...OR ABOUT 650 NM ENE OF THE
LEEWARD ISLANDS. THE SYSTEM IS MOVING N AT 6 KT. MINIMUM CENTRAL
PRESSURE IS 1006. MAXIMUM SUSTAINED WIND SPEED IS 30 KT WITH
GUSTS TO 40 KT. SEE LATEST NHC PUBLIC ADVISORY UNDER AWIPS/WMO
HEADERS MIATCPAT4/WTNT34 KNHC AND THE FORECAST/ADVISORY UNDER
AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS.
SCATTERED MODERATE/STRONG CONVECTION IS FROM 21N-25N BETWEEN
47W-52W. ISOLATED MODERATE CONVECTION IS FROM 20N-23N BETWEEN
51W-53W.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 17N24W TO 10N25W MOVING W AT 10-15 KT.
THE WAVE LIES JUST WEST OF AN AREA OF MAXIMUM MOISTURE PRESENT
IN TOTAL PRECIPITABLE WATER IMAGERY. ONLY ISOLATED MODERATE
CONVECTION IS FROM 8N-12N BETWEEN 21W-24W...AND FROM 12N-14N
BETWEEN 28W-30W.

TROPICAL WAVE IS ALONG 16N37W TO 10N37W MOVING W AT 5-10 KT. THE
WAVE COINCIDES WITH A NARROW SURGE IN DEEP LAYER MOISTURE
PRESENT IN TOTAL PRECIPITABLE WATER IMAGERY. A CLUSTER OF
SCATTERED STRONG CONVECTION IS JUST EAST OF THE WAVE EMBEDDED
WITHIN THE MONSOON TROUGH FROM 8N-11N BETWEEN 33W-36W.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS WEST AFRICA TO THE COAST OF
SIERRA LEONE AT 9N13W CONTINUING ALONG 9N20W 10N31W 10N43W. THE
ITCZ BEGINS AT 10N43W AND CONTINUES ALONG 10N50W 8N54W.
SCATTERED MODERATE/STRONG CONVECTION IS FROM 3N-7N BETWEEN
17W-19W...AND FROM 7N-9N BETWEEN 42W-47W.

...DISCUSSION...

GULF OF MEXICO...
SURFACE RIDGING CONTINUES TO DOMINATE THE GULF OF MEXICO TONIGHT
ANCHORED BY A 1023 MB HIGH OVER NORTH CAROLINA. ANTI-CYCLONIC
FLOW OF 10-15 KT IS AROUND THE RIDGE EXCEPT FOR SOME STRONGER
WINDS UP TO 15 KT ACROSS THE SE GULF AND ALONG THE SOUTHERN
TEXAS COAST. CLEAR SKIES ARE PRESENT OVER THE MAJORITY OF THE
AREA WITH A FEW LOW-LEVEL CLOUDS AND POSSIBLE SHOWERS ACROSS THE
FAR SE GULF AND THE FAR SW GULF ALONG THE MEXICAN COAST.
ALOFT...AN UPPER LEVEL RIDGE COVERS THE EASTERN CONUS INTO THE
GULF OF MEXICO SUPPORTING THE SURFACE RIDGE. AN UPPER LEVEL
TROUGH STILL EXTENDS DOWN THE FLORIDA PENINSULA INTO THE NW
CARIBBEAN. DRY AIR AND SUBSIDENCE ALSO COVER THE BASIN HELPING
SUPPORT THE FAIR WEATHER. SURFACE RIDGING IS EXPECTED TO REMAIN
ACROSS THE GULF FOR THE NEXT SEVERAL DAYS PROVIDING GENERALLY
FAIR CONDITIONS.

CARIBBEAN SEA...
WHAT IS NOW TROPICAL STORM SANDY DOMINATES THE WEATHER PATTERN
IN THE CARIBBEAN PROVIDING ABUNDANT MOISTURE TO A GOOD PORTION
OF THE AREA. SEE SPECIAL FEATURES FOR MORE DETAILS.
SHOWERS/THUNDERSTORMS COVER MUCH OF THE SW CARIBBEAN AND INTO
THE CENTRAL AND EASTERN CARIBBEAN. SIMILAR ACTIVITY ALSO COVERS
MUCH OF CENTRAL AMERICA LIKELY ASSOCIATED WITH THE MONSOON
TROUGH THAT EXTENDS ACROSS SOUTHERN NICARAGUA TOWARD SANDY.
SCATTERED SHOWERS/THUNDERSTORMS ARE ALSO OVER HISPANIOLA AND
WILL LIKELY SPREAD INTO EASTERN CUBA AND JAMAICA SOON. AS THE
SYSTEM GRADUALLY MOVES NORTHWARD OVER THE NEXT FEW DAYS...HEAVY
ACTIVITY IS LIKELY OVER THESE ISLANDS AND POSE THE RISK FOR
FLOODING AND MUDSLIDES ESPECIALLY IN HIGH TERRAIN. ALOFT...AN
UPPER LEVEL TROUGH EXTENDS FROM THE FLORIDA PENINSULA TO NORTH
OF HONDURAS. DRY AIR IS SINKING SOUTH AROUND THE WEST SIDE OF
THE TROUGH PROVIDING FAIR CONDITIONS OVER THE FAR NW CARIBBEAN.
AN UPPER LEVEL RIDGE COVERS THE REMAINDER OF THE BASIN WITH AXIS
ALONG 70W. DRY AIR IS ALSO WRAPPING AROUND THE FAR EASTERN SIDE
OF THE UPPER RIDGE PROVIDING FAIR WEATHER OVER THE FAR EASTERN
CARIBBEAN INCLUDING THE LESSER ANTILLES. T.S. SANDY WILL
CONTINUE TO DOMINATE THE CARIBBEAN FOR THE NEXT COUPLE OF DAYS.

ATLANTIC OCEAN...
AN UPPER LEVEL RIDGE OVER THE EASTERN CONUS IS HELPING SUPPORT
SURFACE RIDGING AND FAIR WEATHER DOWN THE EASTERN SEABOARD WHICH
CONTINUES INTO THE WEST ATLC. AN UPPER LEVEL TROUGH ALONG 60W
SUPPORTS A COLD FRONT THAT ENTERS THE DISCUSSION AREA NEAR
32N59W TO 27N63W WHERE IT TRANSITIONS INTO A DISSIPATING
STATIONARY FRONT TO 26N69W AND THEN INTO A SHEAR AXIS TO THE
CENTRAL BAHAMAS NEAR 24N77W. SCATTERED SHOWERS/THUNDERSTORMS
COVER MUCH OF THE BAHAMAS TO CUBA. POSSIBLE SHOWERS ARE ALONG
THE FRONTAL BOUNDARY ELSEWHERE. IN THE CENTRAL ATLC...NEWLY
FORMED T.D. NINETEEN IS SUPPORTING AN AREA OF
SHOWERS/THUNDERSTORMS TO THE NE OF THE CENTER. AN UPPER LEVEL
TROUGH IS WEST OF THE SYSTEM WITH AXIS ALONG 54W. AN UPPER LEVEL
RIDGE TO THE EAST ALONG 44W AND CONTINUING TO NEAR 12N30W IN THE
TROPICAL ATLC SUPPORTS WEAK SURFACE RIDGING TO THE NE OF T.D.
NINETEEN. HOWEVER...A LARGE LOW PRESSURE SYSTEM DOMINATES THE NE
ATLC SUPPORTED BY AN UPPER LEVEL LOW NEAR THE AZORES ISLANDS. NO
ACTIVE WEATHER IS ASSOCIATED WITH THE SYSTEM IN THE DISCUSSION
AREA. A WEAK SURFACE TROUGH IS ANALYZED ALONG 23N34W TO
19N36W...BUT IS NOT SUPPORTING ANY SHOWERS ACTIVITY.

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

$$
WALTON




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