[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 010000
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT WED APR 30 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.

...SPECIAL FEATURES...

GULF OF MEXICO GALE WARNING...A TIGHT PRESSURE GRADIENT IS IN
PLACE OVER EASTERN MEXICO WITH RIDGING NOSING DOWN EAST OF THE
HIGH TERRAIN OF MEXICO WITH LOW PRESSURE TO THE WEST OVER
INTERIOR MEXICO. C-MAN STATIONS NEAR THE COAST OF VERACRUZ
MEXICO HAVE BEEN REPORTING NORTHERLY WINDS SUSTAINED AT GALE
FORCE...AND A GALE WARNING HAS BEEN ISSUED FOR THE OFFSHORE
WATERS EAST OF VERACRUZ...IN EFFECT UNTIL 06 UTC.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 07N13W TO
02N26W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM
02N26W TO THE EQUATOR NEAR 30W. ISOLATED TO WIDELY SCATTERED
MODERATE CONVECTION IS WITHIN 240 NM S OF THE MONSOON TROUGH
BETWEEN 13W AND 20W...AND ALSO WITHIN 75 NM N OF THE ITCZ
BETWEEN 39W AND 44W.

...DISCUSSION...

GULF OF MEXICO...
A VERY BROAD AND VIGOROUS MIDDLE TO UPPER LEVEL LOW IS CENTERED
OVER THE UPPER-MISSISSIPPI RIVER VALLEY THIS EVENING THAT
SUPPORTS A 1005 MB SURFACE LOW CENTERED OVER WISCONSIN...WITHIN
A SECOND 1006 MB SURFACE LOW CENTERED OVER NORTHERN INDIANA...
AND A THIRD 1008 MB SURFACE LOW OVER CENTRAL WEST VIRGINIA. A
STATIONARY FRONT EXTENDS FROM THE EASTERN LOW THROUGH CENTRAL
ALABAMA TO THE GULF COAST NEAR THE FLORIDA/ALABAMA BORDER
CONTINUING THROUGH THE CENTRAL GULF NEAR 25N92W TO EAST CENTRAL
MEXICO NEAR 21N97W. COPIOUS MOISTURE CONTINUES TO FEED OUT AHEAD
OF THE FRONT N OF 27N TO ACROSS THE FLORIDA PANHANDLE WHICH HAS
SEEN HISTORIC AND VERY DANGEROUS FLASH FLOODING OVER THE PAST 24
HOURS. ADDITIONAL CONVECTION IS STREAMING OUT EVEN MORE AHEAD OF
THE FRONT OVER NE AND CENTRAL FLORIDA WITH IMPRESSIVE FREQUENT
LIGHTNING IN BOTH OF THE AREAS OF CONVECTION.

THE GULF MARINE CONDITIONS ARE DIVIDED BY THE STATIONARY FRONT
WITH NORTH-NORTHEASTERLY WINDS WEST OF THE BOUNDARY...GENERALLY
IN THE RANGE OF 15 TO 25 KT WITH SEAS 5-8 FT...AND SOUTH-
SOUTHEASTERLY WINDS EAST OF THE BOUNDARY...GENERALLY IN THE
RANGE OF 5 TO 15 KT WITH SEAS 3-6 FT OUTSIDE OF ANY CONVECTION.
ISOLATED TO SCATTERED SHOWERS AND TSTMS ARE OCCURRING OFF THE
TEXAS COAST FROM 27N-28N BETWEEN 92W-95W. A SURFACE TROUGH IS IN
THE SW AND CENTRAL GULF JUST AHEAD OF THE FRONT WITH ADDITIONAL
CLUSTERS OF ISOLATED TO SCATTERED SHOWERS AND TSTMS S OF 22N E
OF 95W...INCLUDING OVER THE YUCATAN PENINSULA.

THE FRONT IS FORECAST TO REMAIN NEARLY STATIONARY TONIGHT...THEN
WILL BEGIN TO CREEP EASTWARD THU MORNING EXTENDING FROM N OF
TAMPA BAY FLORIDA NEAR 29N83W THROUGH THE CENTRAL GULF NEAR
25N90W TO THE EASTERN BAY OF CAMPECHE NEAR 18N93W...BECOMING
NEARLY STATIONARY AGAIN THROUGH FRI EVENING.

CARIBBEAN SEA...
NORTHWESTERLY-WESTERLY FLOW ALOFT PREVAILS OVER THE CARIBBEAN
ON THE SOUTHWESTERN PERIPHERY OF AN UPPER LEVEL TROUGH OVER THE
CENTRAL AND SOUTHWEST NORTH ATLC. WATER VAPOR IMAGERY INDICATES
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 WITH SEAS AT 8-9 FT...STRONGEST BETWEEN 71W-80W AND
ALSO IN THE GULF OF HONDURAS WHERE SEAS ARE 6-8 FT.

ELSEWHERE...LOW-LEVEL MOISTURE CONVERGENCE INCREASES ACROSS THE
SW CARIBBEAN AS A FEW ISOLATED SHOWERS AND TSTMS ARE OCCURRING S
OF 10N. THIS ACTIVITY IS LIKELY ENHANCED DUE TO THE CLOSE
PROXIMITY OF THE MONSOON TROUGH AXIS EXTENDING ALONG 09N/10N.

...HISPANIOLA...
THE TAIL END OF AN ATLC MID-UPPER LEVEL TROUGH IS JUST NORTH-
NORTHEAST OF THE ISLAND...AND AFTERNOON DAYTIME HEATING HAS
CREATED UNSTABLE CONDITIONS RESULTING IN ISOLATED SHOWERS AND
TSTMS. THE ACTIVITY IS DIMINISHING AFTER SUNSET WITH MORE STABLE
CONDITIONS.

ATLANTIC OCEAN...
OVERALL RIDGING ALOFT IS NOTED ON WATER VAPOR IMAGERY OVER THE
SOUTHWEST NORTH ATLC THAT SUPPORTS A SURFACE RIDGE EXTENDING
FROM 1032 MB HIGH PRESSURE LOCATED OVER NOVA SCOTIA EXTENDING
SOUTH-SOUTHWEST JUST W OF BERMUDA TO EAST-CENTRAL FLORIDA.
SCATTERED SHOWERS AND TSTMS IS PUSHING IN TOWARDS THE RIDGE
AHEAD OF A MID-UPPER LEVEL TROUGH IN THE GULF OF MEXICO AND AN
ATTENDANT SURFACE COLD FRONT. THE COLD FRONT IS EXPECTED TO
EMERGE OFF THE COAST BY LATE THURSDAY NIGHT INTO EARLY FRIDAY.

FARTHER EAST...A MIDDLE TO UPPER LEVEL TROUGH AXIS EXTENDS INTO
THE DISCUSSION WATERS NEAR 32N47W CONTINUING TO THE SOUTHWEST-
WEST THROUGH 26N50W TO NORTH OF THE GREATER ANTILLES. THIS
TROUGH IS SUPPORTING A SURFACE COLD FRONT ANALYZED FROM 32N41W
SOUTHWEST TO 27N46W TO 23N57W. A PRE-FRONTAL TROUGH LIES TO THE
SOUTHEAST-SOUTH OF THE COLD FRONT FROM 28N44W TO 20N54W.
SCATTERED SHOWERS AND ISOLATED TSTMS ARE OCCURRING N OF 26N
WITHIN 150 NM SE OF THE COLD FRONT. OTHERWISE...THE REMAINDER OF
THE EASTERN ATLC IS UNDER THE INFLUENCE OF A SURFACE RIDGE
ANCHORED BY A 1022 MB HIGH CENTERED E OF THE AZORES NEAR 36N19W.
THE RIDGE AXIS EXTENDS FROM THE HIGH CENTER SW THROUGH 32N28W TO
20N42W.

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

$$
LEWITSKY


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