[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 300003
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT THU MAR 29 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
2345 UTC.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS WRN AFRICA TO THE COAST
LIBERIA AT 7N10W AND CONTINUES SW TO 2N18W...WHERE LOW LEVEL
WINDS SUGGEST THE ITCZ THEN CONTINUES ALONG 1N THEN DIPS S OF
THE EQUATOR NEAR 38W AND CONTINUES TO THE COAST OF BRAZIL AT
2S45W. SCATTERED MODERATE CONVECTION IS WITHIN 60 NM N OF THE
ITCZ AXIS BETWEEN 23W-27W.

...DISCUSSION...

GULF OF MEXICO...
ALOFT...A FLATTENING UPPER RIDGE E OF 91W IS GRADUALLY SLIDING
EWD IN RESPONSE TO A RATHER VIGOROUS SHORTWAVE TROUGH OVER ERN
TEXAS. BOTH NWS RADAR DISPLAYS AND SATELLITE IMAGERY FROM DURING
THE AFTERNOON AND EARLY EVENING HOURS HAVE BEEN VIVIDLY SHOWING
CONVECTIVE ACTIVITY IN ASSOCIATION WITH A MESO-SCALE CONVECTIVE
VORTEX (MCV) NOW OVER NE TEXAS THAT EARLIER DEVELOPED AHEAD OF
THE SHORTWAVE TROUGH. THE CONVECTIVE ACTIVITY IS MOVING NEWD
ALONG THE TEXAS AND SW LOUISIANA COASTS AS WELL AS WITHIN 70-80
NM OFFSHORE THOSE COASTS. HOWEVER...THIS ACTIVITY APPEARS TO BE
UNDERGOING A WEAKENING TREND WITHIN THE PAST FEW HOURS N OF 27N
BETWEEN 92W-96W...BUT QUICKLY DEVELOPING S OF 27N W OF 95W TO
INLAND THE TEXAS COAST. UPPER LEVEL MOISTURE FROM THIS ACTIVITY
AS SEEN ON IN THE FORM OF SCATTERED TO BROKEN HIGH LEVEL CLOUDS
AS SEEN ON WATER VAPOR IMAGERY IS ADVECTING EWD ACROSS MOST OF
THE WRN AND CENTRAL GULF. A SURFACE TROUGH ALONG 88W N OF 28N
ALSO TRIGGERED OFF SCATTERED SHOWER AND TSTM ACTIVITY DURING THE
DAY...HOWEVER THIS ACTIVITY IS RAPIDLY DISSIPATING. DEBRIS
BLOW-OFF HIGH LEVEL MOISTURE FROM THIS ACTIVITY IN THE FORM OF
BROKEN HIGH CLOUDS IS SPREADING EWD ACROSS THE ERN SECTION OF
THE GULF N OF 26N E OF 88W. BROKEN HIGH LEVEL CLOUDS DUE TO AN
ERN PACIFIC JET STREAM BRANCH THAT STRENGTHS OVER CENTRAL MEXICO
ARE S OF 26N.

AT THE SURFACE...A WEAK 1016 MB HIGH CENTER IS OVER THE NE
GULF AT 28.5N85W WITH A RIDGE WSW TO CENTRAL TEXAS. A MOIST SE
SURFACE WIND FLOW AROUND THE SRN PERIPHERY OF THE RIDGE
CONSISTS OF 10-15 KT WINDS. SCATTERED CUMULUS CLOUDS WITH
ISOLATED SHOWERS ARE ARE MOVING NW AND N OVER MUCH OF THE
CENTRAL AND ERN PORTIONS OF THE GULF...AND OVER PARTS OF THE
STRAITS OF FLORIDA. ASIDE FROM THE HIGH LEVEL CLOUDS...S OF 26N
SOME PATCHES OF MOSTLY CLEAR SKIES ARE NOTED IN BETWEEN THE
CLOUDS. EXPECT THE SURFACE TROUGH IN THE NE GULF TO MOVE NW AND
DISSIPATE WITH SURFACE RIDGING REMAINING ACROSS THE AREA.

CARIBBEAN SEA...
ALOFT...MAINLY SW FLOW UNDER MODERATE CONDITIONS COVERS MUCH OF
THE WRN AND CENTRAL SECTIONS OF THE SEA. THE ASSOCIATED RATHER
TRANQUIL ATMOSPHERIC CONDITIONS ARE CONTINUING...AND ARE
EXPECTED TO CHANGE LITTLE THROUGH THE NEXT 48 HRS.

A LIGHT SURFACE PRES GRADIENT EXISTS THROUGHOUT INDUCING NE-E
TRADE WINDS OF 15-20 KT. WITH THIS WIND FLOW...SCATTERED LOW
CLOUDS WITH ISOLATED SHOWERS MOVING WWD ARE SEEN PRIMARILY S OF
17N. SMALL PATCHES OF BROKEN LOW CLOUDS WITH ISOLATED SHOWERS
ARE MOVING NWD ACROSS THE NW CARIBBEAN...AND THROUGH THE YUCATAN
CHANNEL INTO THE FAR SRN GULF OF MEXICO. A STRONGER PRES
GRADIENT S OF 15N BETWEEN 68W AND 78W IS RESULTING IN NE-E 20-25
KT WINDS THERE. THE RESULTANT LOW-LEVEL SPEED CONVERGENCE ALONG
THE COASTS OF COSTA RICA AND PANAMA IS BRINGING ISOLATED SHOWERS
TO THOSE PARTICULAR COAST LINES. THE NRN CARIBBEAN ISLANDS
INCLUDING PUERTO RICO AND HISPANIOLA ARE OBSERVED TO HAVE
SCATTERED SHOWERS AND FEW TSTMS AS OF EARLY THIS EVENING DUE
TO PRIMARILY RESIDUAL MOISTURE LEFT OVER FROM THE TAIL END
OF A CENTRAL ATLC COLD FRONT. THE COMBINATION OF THIS MOISTURE
WITH EARLIER AFTERNOON HEATING HELPED FIRE OFF THIS ACTIVITY. AS
THE EVENING HOURS BECOME PROLONGED THIS ACTIVITY WILL THEN
SLOWLY DIMINISH.

CLEAR SKIES ARE EVIDENT S OF 14N BETWEEN 65W AND 77W...AND
ARE EXPECTED TO CONTINUE INTO THROUGH THE NEXT 24-48 HRS.

ATLANTIC OCEAN...
RATHER BROAD UPPER LEVEL FLOW IS OBSERVED OVER MUCH OF THE
BASIN W OF ABOUT 39W AS THE GULF OF MEXICO UPPER RIDGE
SLIDES FURTHER E. SATELLITE WATER VAPOR IMAGERY SHOWS ABUNDANT
MODERATE SUBSIDENCE MAINTAINING RATHER STABLE CONDITIONS ACROSS
THE WRN ATLC. AT THE SURFACE...A 1020 MB HIGH IS ANALYZED AT
26N67W. THIS HIGH IS FORECAST TO DISSIPATE IN 24 HRS. IN THE
CENTRAL ATLC AREA...AN UPPER LEVEL TROUGH EXTENDS INTO THE
DISCUSSION AREA AT 32N42W AND REACHES SE TO NEAR 26N40W. IT
SUPPORTS A COLD FRONT THAT ENTERS THE AREA THROUGH 32N37W...AND
REACHES TO 24N44W AND TO 18N51W WHERE IT TRANSITIONS TO A
DISSIPATING FRONT TO JUST E OF THE LEEWARD ISLANDS. SCATTERED TO
NUMEROUS SHOWERS AND ISOLATED WEAK TSTMS ARE WITHIN 120-200 NM
E OF THE FRONT N OF 26N...AND WITHIN 30 NM OF THE FRONT
ELSEWHERE. AN UPPER LEVEL SHORTWAVE RIDGE IS NOTED TO THE E OF
THE UPPER TROUGH COVERING THE ERN ATLC REGION WITH A MEAN AXIS
ALONG 29W/30W. IT SUPPORTS A 1023 MB SURFACE HIGH AT 31N26W
WITH A RIDGE SW TO 24N37W. IT IS PROVIDING FAIR CONDITIONS
ACROSS THE REMAINDER OF THE ATLC ELSEWHERE E OF THE COLD
FRONT AND N OF 12N. THE HIGH IS FORECAST TO MOVE SE AND
WEAKEN OVER THE NEXT 24 HRS.

OVER THE FAR ERN ATLC...AN UPPER LEVEL TROUGH IS JUST ALONG THE
COAST OF AFRICA FROM 5N TO 22N...WHILE MID TO UPPER LEVEL RIDGING
IS TO ITS SE. VERY DEEP TROPICAL MOISTURE TO THE SE OF THE TROUGH
...AND UNDER THE RIDGE IS PRODUCING VERY LARGE CLUSTERS OF
NUMEROUS STRONG TYPE CONVECTION S OF THE AFRICA JUST SE OF THE
DISCUSSION AREA.

OVER THE TROPICAL ATLC...BROAD UPPER LEVEL RIDGING IS PRESENT S
OF 23N BETWEEN THE FAR ERN ATLC TROUGH AND 71W. STRONG WLY WINDS
ALOFT WITH JET STREAM BRANCH ALONG THE NORTHERN CREST OF THIS
RIDGE ARE TRANSPORTING MAINLY BROKEN HIGH CIRRUS CLOUDS EWD
FROM THE ERN CARIBBEAN SEA AND TO AS FAR E AS 24N FROM 14N TO
18N.

LAST VISIBLE SATELLITE IMAGERY ALONG WITH GOES-R DUST
ENHANCEMENTS REVEALED THAT AN AREA OF AFRICAN DUST OVER
SOME AREAS OF THE E ATLC AND TO THE AFRICAN COAST.

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

$$
AGUIRRE








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