[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 170548
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT WED APR 17 2013

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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0515 UTC.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 12N16W TO
05N23W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM
05N23W TO 01N32W. ISOLATED MODERATE CONVECTION IS FROM 01N-05N
BETWEEN 22W-29W.

...DISCUSSION...

GULF OF MEXICO...
A MIDDLE TO UPPER LEVEL RIDGE IS NOTED ON WATER VAPOR IMAGERY
WITH AXIS ALONG 86W THAT CONTINUES TO SUPPORT SURFACE RIDGING
AND PRIMARILY EAST-SOUTHEASTERLY WINDS IN THE RANGE OF 10 TO 20
KT EAST OF 90W AND 15 TO 25 KT WEST OF 90W. AN UPPER LEVEL
TROUGH AXIS EXTENDS FROM OVER SE TEXAS NEAR 29N98W TO A BASE
OVER SOUTHERN MEXICO NEAR 17N95W. WHILE THIS REMAINS AN UPPER
LEVEL FEATURE...THE TROUGHING IS ENHANCING CLOUDINESS OVER THE
WESTERN GULF N OF 20N W OF 90W. THE SURFACE RIDGE IS EXPECTED TO
PERSIST THROUGH LATE THURSDAY WHEN INTO EARLY FRIDAY THE NEXT
COLD FRONT IS FORECAST TO EMERGE OFF THE TEXAS AND LOUISIANA
COAST. WINDS WILL SHIFT NORTH-NORTHEASTERLY WEST OF THE FRONT AS
IT MOVES EASTWARD OVER THE UPCOMING WEEKEND.

CARIBBEAN SEA...
AN UPPER LEVEL ANTICYCLONIC CIRCULATION IS CENTERED OVER THE SW
CARIBBEAN NEAR 11N79W THAT IS PROVIDING MOSTLY WEST-
NORTHWESTERLY FLOW ALOFT OVER MUCH OF THE BASIN. WATER VAPOR
IMAGERY INDICATES THAT DRY AIR AND OVERALL SUBSIDENCE CONTINUES
TO PROVIDE TRANQUIL CONDITIONS WITH THE EXCEPTION OF AN AREA OF
WIDELY SCATTERED SHOWERS OCCURRING IN THE VICINITY OF THE LESSER
ANTILLES FROM 14N-20N BETWEEN 57W-63W. OTHERWISE...TRADES
PERSIST IN THE RANGE OF 10 TO 20 KT WITH THE HIGHEST WINDS
ANTICIPATED S OF 15N BETWEEN 68W-78W...AND IN CLOSE PROXIMITY TO
THE COAST OF COLOMBIA. THIS OVERALL SYNOPTIC PATTERN IS EXPECTED
TO CONTINUE THROUGH EARLY THURSDAY AND INTO THE WEEKEND WITH
TRADES GRADUALLY INCREASING E OF 80W BY EARLY FRIDAY DUE TO AN
INCREASED PRESSURE GRADIENT AND HIGH PRESSURE RIDGE ANCHORED
OVER THE SW NORTH ATLC REGION.

ATLANTIC OCEAN...
AS MIDDLE TO UPPER LEVEL RIDGING BUILDS EASTWARD FROM THE GULF
OF MEXICO INTO THE SW NORTH ATLC...DRY AND SUBSIDENT NORTHWEST
FLOW DOMINATES THIS EVENING HOWEVER...AN AREA OF WEAK LOW
PRESSURE EXISTS ALONG 30N WITH TWO DIFFERENT 1019 MB LOW
CENTERS...ONE NEAR 30N75W AND THE OTHER NEAR 30N68W. THESE LOWS
ARE CONNECTED BY WAY OF A STATIONARY FRONT WITH POSSIBLE
ISOLATED LOW-TOPPED SHOWERS OCCURRING N OF 30N BETWEEN 62W-78W.
FARTHER EAST...LONGWAVE TROUGHING IS NOTED ON WATER VAPOR
IMAGERY BETWEEN 35W-65W WITH AXIS EXTENDING FROM 37N45W TO A
BASE NEAR 20N67W. THIS TROUGHING SUPPORTS A COLD FRONT ANALYZED
FROM 32N36W TO 28N50W TO 29N60W AND INTO THE EASTERN-MOST 1019
MB LOW NEAR 30N68W. ISOLATED SHOWERS ARE OCCURRING WITHIN 90 NM
EITHER SIDE OF THE COLD FRONT AND N OF 24N BETWEEN 50W-67W. THE
REMAINDER OF THE EASTERN ATLC SOUTH AND EAST OF THE COLD FRONT
IS UNDER THE INFLUENCE OF A WEAKENING AND NARROW SURFACE RIDGE
ANCHORED BY A 1022 MB HIGH CENTERED NEAR 29N33W.

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

$$
HUFFMAN


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