[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 292327
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT TUE APR 29 2014

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
2315 UTC.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 07N12W TO
01N23W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM
01N20W TO THE EQUATOR NEAR 22W. SCATTERED MODERATE CONVECTION IS
WITHIN 60-90 NM EITHER SIDE OF THE MONSOON TROUGH BETWEEN 14W
AND 20W...AND WITHIN 30 NM EITHER SIDE OF THE ITCZ BETWEEN 28W
AND 31W.

...DISCUSSION...

GULF OF MEXICO...
A VERY BROAD AND VIGOROUS MIDDLE TO UPPER LEVEL LOW IS CENTERED
OVER THE MID-MISSISSIPPI RIVER VALLEY THIS EVENING SUPPORTING A
996 MB SURFACE LOW CENTERED OVER CENTRAL IOWA. THIS LOW EXTENDS
AN OCCLUDED FRONT TO A 998 MB LOW CENTERED NEAR CHICAGO ILLINOIS
WHICH EXTENDS A COLD FRONT ACROSS THE OHIO RIVER VALLEY TO THE
LOWER MISSISSIPPI VALLEY...TO OFF THE COAST OF SW LOUISIANA TO
NE MEXICO JUST S OF BROWNSVILLE TEXAS. CURRENTLY THE FRONT
REMAINS RELATIVELY VOID OF DEEP CONVECTION IN THE NW GULF...WITH
IMPRESSIVE CONVECTION AHEAD OF THE FRONT IN THE NE GULF COASTAL
WATERS EXTENDING INLAND THROUGH THE SE UNITED STATES. AN OUTFLOW
BOUNDARY...REMNANTS OF AN EARLIER SQUALL LINE WHICH HAS FALLEN
APART...EXTENDS FROM NE FLORIDA NEAR JACKSONVILLE SW INTO THE NE
GULF NEAR 28.5N86.5W.

OTHERWISE...THE REMAINDER OF THE GULF IS UNDER MOSTLY CLEAR TO
PARTLY CLOUDY SKIES S OF 27N AS SOUTH-SOUTHEAST FLOW PERSISTS IN
THE RANGE OF 10 TO 20 KT WITH WINDS VEERING SLIGHTLY SOUTH-
SOUTHWESTERLY ACROSS THE NW GULF WATERS AHEAD OF THE COLD FRONT.
NORTH-NORTHEASTERLY WINDS ARE FOLLOWING THE COLD FRONT IN THE
TEXAS AND WESTERN LOUISIANA COASTAL WATERS AND THE FRONT WILL
EXTEND FROM SOUTHERN ALABAMA TO MEXICO NEAR 21N97W WEDNESDAY
MORNING...THEN IS EXPECTED TO BECOME STATIONARY FROM THE FLORIDA
BIG BEND REGION SW TO THE BAY OF CAMPECHE THURSDAY MORNING
THROUGH THURSDAY EVENING.

CARIBBEAN SEA...
WESTERLY FLOW ALOFT PREVAILS OVER THE CARIBBEAN WITH WATER VAPOR
IMAGERY INDICATING RELATIVELY DRY AND STABLE CONDITIONS IN THE
MIDDLE TO UPPER LEVELS THIS EVENING. THIS IS RESULTING IN
RELATIVELY FAIR SKIES...HOWEVER WITH A STRONG PRESSURE IN PLACE
DUE TO A RIDGE ACROSS THE SW NORTH ATLC REGION...TRADES PERSIST
IN THE RANGE OF 15 TO 25 KT...STRONGEST BETWEEN 69W-75W AND IN
THE GULF OF HONDURAS. ELSEWHERE...LOW-LEVEL MOISTURE CONVERGENCE
INCREASES ACROSS THE SW CARIBBEAN AND CENTRAL AMERICA S OF 12-
13N AS SCATTERED SHOWERS AND TSTMS ARE OCCURRING ACROSS PANAMA
AND COSTA RICA...INCLUDING THE ADJACENT COASTAL WATERS ON BOTH
CARIBBEAN WATERS AND EASTERN PACIFIC WATERS. THIS ACTIVITY IS
LIKELY ENHANCED DUE TO THE CLOSE PROXIMITY OF THE MONSOON TROUGH
AXIS EXTENDING ALONG 09N. ADDITIONAL CONVECTION HAS BEEN FIRING
OVER THE REMAINDER OF CENTRAL AMERICA DUE TO DAYTIME HEATING
ALTHOUGH THIS CONVECTION SHOULD DIMINISH A FEW HOURS AFTER
SUNSET.

...HISPANIOLA...
WITH PEAK AFTERNOON HEATING AND INSTABILITY...A FEW ISOLATED
SHOWERS AND TSTMS HAVE DEVELOPED LATE THIS AFTERNOON INTO THE
EARLY EVENING HOURS...HOWEVER ANY ONGOING CONVECTION WILL LIKELY
GRADUALLY DIMINISH LATE THIS EVENING INTO THE OVERNIGHT HOURS.
OTHERWISE MAINLY DRY AND STABLE WESTERLY FLOW ALOFT WILL PROVIDE
FAIR CONDITIONS ACROSS THE ISLAND THROUGH THURSDAY.

ATLANTIC OCEAN...
OVERALL RIDGING ALOFT IS NOTED ON WATER VAPOR IMAGERY OVER THE
SW NORTH ATLC THAT SUPPORTS A 1021 MB HIGH CENTERED SW OF
BERMUDA NEAR 30N69W. HOWEVER...WATER VAPOR IMAGERY ALSO
INDICATES A WEAK MID-LEVEL SHORTWAVE TROUGH AND ASSOCIATED
ENERGY OVER THE BAHAMAS NEAR 24N76W. WHILE NO SURFACE-BASED
BOUNDARY OR FRONT IS IN THE VICINITY...THE MID-LEVEL ENERGY WAS
MANAGING TO GENERATE AN AREA OF SCATTERED SHOWERS AND TSTMS S OF
24N BETWEEN 73W-77W...HOWEVER THE TSTMS HAVE DISSIPATED WITH THE
ARRIVAL OF SUNSET AND MORE STABLE CONDITIONS THIS EVENING.

FARTHER EAST...A MIDDLE TO UPPER LEVEL LOW IS CENTERED NEAR
37N53W WHICH REFLECTS AT THE SURFACE AS A 1003 MB LOW CENTERED
NEAR 35N56W THAT CONTINUES TO DRIFT EAST-NORTHEAST. THE
ASSOCIATED COLD FRONT ENTERS THE DISCUSSION AREA NEAR 32N48W
EXTENDING SW TO 26N61W. A PRE-FRONTAL TROUGH HAS BECOME LESS
EVIDENT AT THE SURFACE WHILE A MID-UPPER LEVEL SHORTWAVE
CONTINUES TO SUPPORT CONVECTION APPROXIMATELY 180 NM SE OF THE
SURFACE COLD FRONT.

OTHERWISE...THE REMAINDER OF THE EASTERN ATLC IS UNDER THE
INFLUENCE OF A SURFACE RIDGE ANCHORED BY A 1023 MB HIGH CENTERED
NEAR 33N29W AND A 1024 MB HIGH CENTERED NEAR 37N19W. THE SURFACE
RIDGE AXIS EXTENDS FROM THE 1023 MB HIGH SW TO 22N50W.

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

$$
LEWITSKY

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