[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 232359
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST MON FEB 23 2009

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...METEOROLOGICAL ANALYSIS...WEATHER
OBSERVATIONS...AND RADAR.

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...ITCZ...
ITCZ AXIS CENTERED ALONG 07N11W TO S OF EQUATOR AT 00N22W.  NO
SIGNIFICANT CONVECTION ALONG ITCZ.  SCATTERED MODERATE ISOLATED
STRONG CONVECTION S OF 05N W OF 40W LIE JUST N OF ITCZ AS IT
NEARS NE COAST OF BRAZIL.

...DISCUSSION...
GULF OF MEXICO...
SHARP DEEP LAYER TROUGH FROM STRAITS OF FLORIDA TO YUCATAN
PENINSULA CONTINUES THROUGH BAY OF CAMPECHE INTO E PAC.  VERY
DRY AIR MASS DUE TO MODERATE TO STRONG SUBSIDENCE ACROSS ENTIRE
GULF NW OF TROUGH AXIS EXCEPT SOME MOISTURE ALOFT ALONG COASTAL
STATES.  TROUGH LIKELY TO LOSE IDENTITY S OF 25N WITHIN NEXT 48
HRS AS UPSTREAM RIDGE NOW OVER CENTRAL MEXICO MAKE ITS WAY INTO
BASIN...POSSIBLY MERGING WITH CARIBBEAN RIDGE ANCHORED OVER
VENEZUELA.  JET CORE 95 KT SHOULD MOVE OUT OF GULF WITHIN NEXT
24 HRS.

ASSOCIATED COLD FRONT NOW OFF GULF WATERS PROMPT QUICK DROP IN
NE WINDS AND SEAS BECOME UNDER 8 FT.  PATCHES OF SCATTERED TO
OCCASIONALLY BROKEN LOW LEVEL CLOUDS MOSTLY S OF 25N DOT BASIN
WITH ISOLATED SHOWERS.  OTHERWISE...FAIR WEATHER PRESENT WITH
STABLE ATMOSPHERIC CONDITIONS AND RELATIVELY COOLER AND DRIER
AIRMASS ACROSS GULF.

CARIBBEAN SEA...
BROAD WELL ANCHORED MID-UPPER LEVEL ANTICYCLONE OVER CENTRAL
VENEZUELA MAINTAINS VERY DRY AIR MASS ACROSS ENTIRE CARIBBEAN
WITH LITTLE OR NO SIGNIFICANT CONVECTION NOTED.  ONLY SMALL
PATCHES OF SCATTERED TO BROKEN LOW CLOUDS OBSERVED MAINLY ACROSS
CENTRAL CARIBBEAN FLOWING IN THE TRADE WINDS.

TIGHT SURFACE PRESSURE GRADIENT RESULTING IN STRONG TRADE WINDS
ACROSS ENTIRE CARIBBEAN OUGHT TO DIMINISH WITHIN NEXT 24-36 HRS
AS COLD FRONT OVER SW N ATLC APPROACHES GREATER ANTILLES EASING
SUCH GRADIENT.  PREVIOUS GALE EVENT ALONG COAST OF COLOMBIA
ALLOWED TO EXPIRE AS WINDS CONTINUE TO DIMINISH.  MOISTURE
CONVERGENCE ALONG EASTERN COAST OF NICARAGUA AND GULF OF
HONDURAS PROMPT BROKEN LOW CLOUDS AND ISOLATED SHOWERS.

ATLANTIC OCEAN...
DEEP TROUGH OVER SW N ATLC EXTEND FROM 32N75W TO 27N80W
EXPECTED TO COLLAPSE S OF 25N AS CARIBBEAN RIDGE FORCES IT TO
SHIFT NE.  ASSOCIATED COLD FRONT OFF FLORIDA E COAST SHOULD
MERGE WITH PREVIOUS...NOW STATIONARY...FRONT FROM 31N62W TO
23N79W.  NEW FRONTAL BOUNDARY LOSE STEAM S OF 25N AS UPPER
SUPPORT LIFTS NE.  PLENTY OF MOISTURE ADVECTED BY UPPER TROUGH
LIKELY TO MAINTAIN AREA UNDER BROKEN TO OVERCAST MID TO UPPER
LEVEL CLOUDINESS ALONG FRONTAL BOUNDARY THROUGH THU.

CENTRAL ATLC MID-UPPER LEVEL RIDGE HAS ABUNDANT AMOUNTS OF
MOISTURE AVAILABLE N OF 28N E OF 65W BUT LITTLE UPLIFTING
MECHANISM DUE TO SURFACE HIGH PRESSURE 1030 MB WITH RIDGE
EXTENDING SW TO LESSER ANTILLES.

COMPLEX DUAL VORTEX CYCLONIC FLOW OVER CANARY ISLANDS HAS UPPER
LEVEL TROUGH EXTEND SW TO 12N40W TO JUST E OF TRINIDAD.
MODERATE TO STRONG SUBSIDENCE ALOFT WITHIN 5 DEGREES NW OF AXIS
KEEPS ATLC WATERS CONVECTION FREE WHILE 80 KT JET CORE ADVECTS
PLENTY OF MOISTURE INTO WESTERN AFRICA.

$$
WALLY BARNES


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