[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 190001
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT WED MAY 18 2011

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.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 57W/58W S OF 13N TO INLAND OVER SOUTH
AMERICA DRIFTING W AT LESS THAN 10 KT. WAVE IS EMBEDDED IN A
NARROW AREA OF MOISTURE AS DEPICTED ON THE TOTAL PRECIPITABLE
WATER IMAGERY. SCATTERED MODERATE CONVECTION IS WITHIN 90/120 NM
E OF THE WAVE AXIS S OF 9N.

...THE ITCZ...

ITCZ AXIS IS ANALYZED ALONG 7N10W 4N14W 4N34W 1N50W. SCATTERED/
NUMEROUS STRONG CONVECTION IS WITHIN 150 NM S OF THE ITCZ
BETWEEN 9W-11W AND WITHIN 120 NM N OF THE ITCZ BETWEEN 20W-23W.
CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE
FROM THE ITCZ TO 8N BETWEEN 20W-24W AND FROM 3N-6N BETWEEN
32W-35W. SCATTERED MODERATE CONVECTION IS FROM 1N-4N BETWEEN
13W-16W.

...DISCUSSION...

GULF OF MEXICO...
BROAD UPPER TROUGH COVERS THE E GULF N OF 24N E OF 90W
SUPPORTING A DISSIPATING COLD FRONT THAT EXTENDS FROM THE W ATLC
AT 18/1800 UTC ACROSS CENTRAL FLORIDA BETWEEN VERO BEACH TO JUST
N OF FORT MYERS INTO THE GULF OF MEXICO TO 27N88W. A PRE-FRONTAL
SURFACE TROUGH EXTENDS AT 18-1800 UTC THROUGH THE STRAITS OF
FLORIDA NEAR THE N TIP OF ANDROS ISLAND ALONG THE N COAST OF
CUBA TO 23N84W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE S
OF THE SURFACE TROUGH TO INLAND OVER CUBA. BROAD LOW AMPLITUDE
UPPER RIDGE COVERS THE REMAINDER OF THE GULF WITH DRY STABLE AIR
ALOFT COVERING THE GULF S OF 27N LIMITING SHOWER ACTIVITY. LOW
LEVEL MOISTURE REMAINS OVER THE FAR W GULF AND THE SE SURFACE
FLOW IS BANKING LOW LEVEL CLOUDS MAINLY OVER THE NW GULF N OF
25N W OF 94W. SMOKE IS OBSERVED ON VISIBLE SATELLITE IMAGERY W
OF LINE FROM NW YUCATAN PENINSULA TO CENTRAL LOUISIANA AND NOAA
SSD FIRE PRODUCTS INDICATE NUMEROUS FIRES OVER S MEXICO. A
SURFACE RIDGE IS BUILDING N OF THE FRONT ANCHORED BY A WEAK 1013
MB HIGH JUST OFF THE COAST OF PENSACOLA FLORIDA LEAVING THE NE
GULF UNDER CLEAR SKIES THIS EVENING. HIGH PRESSURE OVER THE NE
GULF WILL DRIFT E ON THU THROUGH FRI NIGHT THEN E OF THE AREA
SAT. SE RETURN FLOW OVER THE W GULF WILL PREVAIL THROUGH MON.

CARIBBEAN SEA...
A SHORTWAVE UPPER TROUGH EXTENDS FROM THE DOMINICAN REPUBLIC
NEAR 19N70W TO THE GULF OF VENEZUELA SUPPORTING A SURFACE TROUGH
THAT EXTENDS FROM 17N70W 14N71W TO 12N70W WITH SCATTERED SHOWERS
AND POSSIBLE ISOLATED THUNDERSTORMS FROM 12N-18N BETWEEN
66W-73W. A WEAKER SURFACE TROUGH IS OVER THE NE CARIBBEAN
EXTENDING ALONG 64W FROM 15N THROUGH THE VIRGIN ISLANDS TO 19N
WITH ISOLATED SHOWERS WITHIN 60 NM EITHER SIDE OF THE TROUGH
AXIS. A BROAD LOW AMPLITUDE UPPER RIDGE COVERS THE W CARIBBEAN W
OF 75W AND WITH DRY STABLE AIR ALOFT WHICH IS LEAVING THE
CARIBBEAN W OF 75W UNDER MOSTLY CLEAR SKIES THIS EVENING. THE
CENTRAL CARIBBEAN SURFACE TROUGH WILL REMAIN NEAR STATIONARY
THROUGH THU THEN MOVE W AND DISSIPATES IN THE W CARIBBEAN THU
NIGHT. TROPICAL WAVE E OF THE WINDWARD ISLANDS WILL MOVE INTO
THE E CARIBBEAN ON THU AND A WEAK LOW PRESSURE WILL DEVELOP
ALONG THE WAVE WHEN IT REACHES THE SW CARIBBEAN OVER THE WEEKEND.

THE ATLANTIC OCEAN...
AN UPPER TROUGH EXTENDS FROM THE GREAT LAKES REGION INTO THE W
ATLC NEAR THE NORTH/SOUTH CAROLINA BORDER THEN S TO THE BAHAMA
ISLANDS SUPPORTING A COLD FRONT THAT AT 18/1800 UTC ENTERS THE
DISCUSSION AREA NEAR 32N76W ALONG 29N78W OVER CENTRAL FLORIDA
INTO THE GULF OF MEXICO NEAR VERO BEACH THEN DISSIPATING INTO
THE GULF OF MEXICO. A PRE-FRONTAL SURFACE TROUGH EXTENDS THROUGH
32N73W ALONG 28N75W ACROSS THE BAHAMAS AND INTO THE STRAITS OF
FLORIDA NEAR THE N TIP OF ANDROS ISLAND. SCATTERED SHOWERS/
THUNDERSTORMS ARE WITHIN 150 NM E OF THE SURFACE TROUGH FROM
25N-29N AND WITHIN 120 NM SE OF THE TROUGH S OF 24N TO INLAND
OVER CUBA. A WEAKENING SURFACE TROUGH IS JUST E OF THE TURKS AND
CAICOS EXTENDING FROM 23N70W TO THE N COAST OF HISPANIOLA NEAR
THE HAITI/DOMINICAN REPUBLIC BORDER. AN UPPER RIDGE IS OVER THE
W/CENTRAL ATLC EXTENDING FROM THE W TROPICAL ATLC E OF THE
LESSER ANTILLES ALONG 55W TO 20N THEN NNW TO BEYOND 32N60W
PROVIDING DIFFLUENT FLOW ALOFT TO ENHANCE PATCHES OF SCATTERED
SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS FROM 21N-30N BETWEEN
57W-69W. AN UPPER TROUGH IN THE CENTRAL ATLC EXTENDS THROUGH
32N45W TO 20N40W SUPPORTING A REMNANT SURFACE TROUGH THAT
EXTENDS THROUGH 32N46W TO 26N50W WITH ISOLATED SHOWERS WITHIN 90
NM EITHER SIDE OF THE SURFACE TROUGH. THIS SURFACE TROUGH SPLITS
A BROAD SURFACE RIDGE THAT COVERS THE ATLC N OF 20N BETWEEN SW
AFRICA AND 70W. W ATLC FRONT WILL MOVE E TONIGHT AND DISSIPATE
ON THU. SURFACE RIDGE WILL GRADUALLY BUILD E ALONG 30N ON THU
AND WEAKENS AS IT DRIFTS S OVER THE WEEKEND.

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

$$
PAW




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