[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 151025
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT WED APR 15 2015

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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1015 UTC.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 06N10W SW
TO 03N13W WHERE THE ITCZ BEGINS AND CONTINUES ALONG 01S24W TO
02S32W TO THE NORTHERN COAST OF BRAZIL NEAR 03S40W. ISOLATED
MODERATE TO STRONG CONVECTION AND TSTMS ARE FROM 01N TO 06N E OF
22W. SCATTERED MODERATE CONVECTION IS FROM 04S TO 06N W OF 33W.

...DISCUSSION...

GULF OF MEXICO...

A WEAK MIDDLE TO UPPER LEVEL TROUGH EXTENDING FROM KANSAS TO A
BASE OVER THE NW GULF OF MEXICO SUPPORT A 1013 MB LOW OVER NW
LOUISIANA FROM WHICH A STATIONARY FRONT EXTENDS ALONG 29N93W SW
TO 26N95W TO 23N97W. LOW-LEVEL MOISTURE ASSOCIATED WITH THE
FRONT ALONG WITH A DIFFLUENT ENVIRONMENT AT THE UPPER LEVELS
SUPPORT SCATTERED MODERATE CONVECTION AND TSTMS BETWEEN THE
FRONT AND A LINE FROM 29N84W SW TO 24N90W TO THE BAY OF CAMPECHE
NEAR 18N94W. AN UPPER RIDGE WITH AXIS ALONG THE EASTERN
SEABOARD...FLORIDA TO WESTERN CUBA...SURFACE RIDGING ANCHORED BY
A 1017 MB HIGH NEAR 28N84W AND SHALLOW DRY AIR SUPPORT FAIR
WEATHER ACROSS THE REMAINDER E-SE GULF. VARIABLE WINDS OF 5 TO
10 KT DOMINATE BASIN-WIDE...EXCEPT ON THE SW GULF AROUND THE
ENVIRONMENT OF A SURFACE TROUGH FROM 23N92W TO 17N93W. THE
STATIONARY FRONT OVER THE NW GULF WILL DISSIPATE LATER TODAY
LEAVING AN ELONGATED AREA OF LOW PRESSURE OVER THE W GULF WHILE
RIDGING WILL CONTINUE TO DOMINATE ELSEWHERE. SCATTERED SHOWERS
AND TSTMS ARE FORECAST TO CONTINUE ACROSS THE NORTHERN AND
PORTIONS OF THE W GULF THROUGH FRIDAY MORNING.

CARIBBEAN SEA...

A BROAD SURFACE RIDGE OVER THE ATLC OCEAN EXTENDS TO THE
NORTHERN CARIBBEAN WHILE LOWER PRESSURE DOMINATES ELSEWHERE S OF
14N BEING ANCHORED BY A 1009 MB LOW OVER N COLOMBIA. THIS IS
SUPPORTING A SLIGHTLY TIGHTER PRESSURE GRADIENT OVER THE CENTRAL
AND PORTIONS OF EASTERN CARIBBEAN...THUS RESULTING IN TRADES OF
20 TO 25 KT BETWEEN 67W AND 79W...THE STRONGEST ALONG THE COAST
OF COLOMBIA. ELSEWHERE TRADES OF 10 TO 15 KT DOMINATE. SSMI TPW
IMAGERY CONTINUE TO SHOW SHALLOW MOISTURE MOVING ACROSS THE
CARIBBEAN SEA...THUS SUPPORTING CLOUDINESS AND POSSIBLE ISOLATED
SHOWERS OVER THE LESSER ANTILLES...PUERTO RICO AND SOUTHERN
HISPANIOLA. SCATTERED TO ISOLATED SHOWERS ARE ON
NICARAGUA...COSTA RICA...AND NORTHERN PANAMA COASTAL WATERS.
FAIR WEATHER IS ELSEWHERE BEING SUPPORTED BY DRY AIR SUBSIDENCE
FROM ALOFT. NOT SIGNIFICANT CHANGES ARE EXPECTED DURING THE NEXT
TWO DAYS.

...HISPANIOLA...

SHALLOW MOISTURE CONTINUES TO MOVE ACROSS WESTERN AND SOUTHERN
HAITI...THUS ENHANCING CLOUDINESS WITH POSSIBLE ISOLATED SHOWERS
EXTENDING TO ADJACENT WATERS TO INCLUDE THE WINDWARD PASSAGE
WHERE A SURFACE TROUGH IS ANALYZED FROM 20N73W TO 17N75W. DEEP
LAYER DRY AIR IS OVER THE REMAINDER ISLAND AS INDICATED BY WATER
VAPOR AND SSMI TPW IMAGERY...WHICH IS SUPPORTING CLEAR SKIES AND
FAIR WEATHER. THESE CONDITIONS ARE EXPECTED TO PREVAIL THROUGH
LATER THIS MORNING WHEN A LOW LEVEL MOIST AIRMASS ENTERS THE
ISLAND TO ENHANCE SHOWERS THROUGH THU AFTERNOON.

ATLANTIC OCEAN...

A MIDDLE TO UPPER LEVEL LOW OVER THE N-NE ATLC EXTENDS AN
ELONGATED TROUGH SW OVER THE CENTRAL BASIN TO A BASE OVER THE
EASTERN CARIBBEAN AND SUPPORT A COLD FRONT FROM 30N42W TO 29N46W
WHERE IT TRANSITIONS TO STATIONARY FRONT TO 28N51W TO 29N56W.
SCATTERED MODERATE CONVECTION IS WITHIN 75 NM EITHER SIDE OF THE
FRONT N OF 28N. RECENT SCATTEROMETER DATA SHOW A WEAK TROUGH
AHEAD OF THE FRONT FROM 30N39W TO 25N38W WITH NO CONVECTION
ASSOCIATED WITH IT. SURFACE RIDGING DOMINATES ELSEWHERE
ANCHORED BY A 1030 MB HIGH NEAR 38N48W AND A 1024 MB HIGH NEAR
31N33W. THE FRONT IS FORECAST TO DISSIPATE LATER TODAY LEAVING
AN ELONGATED AREA OF LOW PRESSURE WITH SCATTERED TO ISOLATED
SHOWERS OVER THE N CENTRAL ATLC.

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

$$
NR

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