[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 182354
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT FRI MAY 18 2012

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...

A TROPICAL WAVE IS CURRENTLY JUST OFFSHORE OF W AFRICA FROM
16N-7N ALONG 21W MOVING W NEAR 15 KTS. THE WAVE LIES WITHIN AN
AREA OF ENHANCED MOISTURE EVIDENT IN TOTAL PRECIPITABLE WATER
IMAGERY. THIS IS ALSO EVIDENT IN GOES-R DUST ENHANCEMENTS WHICH
SHOW THE AREA OF DUST PUSHED TO THE N AND W OF THE WAVE AXIS.
THIS DRY AIR SURROUNDING THE WAVE WILL LIKELY DIMINISH
CONVECTION AS IT MOVES ACROSS THE ATLC. CURRENTLY SCATTERED
MODERATE CONVECTION IS FROM 4N-8N BETWEEN 23W-25W. NUMEROUS
STRONG CONVECTION IS ACROSS W AFRICA FROM 10N-14N BETWEEN
8W-17W...BARELY EMERGING OVER WATER.



...THE ITCZ/THE MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS W AFRICA TO THE COAST OF
GUINEA NEAR 11N15W. THE ITCZ BEGINS ON THE W OF SIDE OF THE
TROPICAL WAVE AND EXTENDS ALONG 7N23W TO THE BRAZIL COAST AT
2N51W. BESIDES CONVECTION NEAR THE TROPICAL WAVE...NO DEEP
CONVECTION IS ASSOCIATED WITH THE ITCZ ELSEWHERE.

...DISCUSSION...

THE GULF OF MEXICO...
A WEAK PRESSURE GRADIENT IS ACROSS THE GULF OF MEXICO TONIGHT
SUPPORTING LIGHT WINDS. THE WIND PATTERN INDICATES VERY WEAK
SURFACE RIDGING EXTENDS FROM A HIGH PRESSURE CENTER TO THE N
NEAR THE GREAT LAKES REGION. DRY AIR ALOFT IN MAINLY ZONAL WLY
FLOW IS HELPING MAINTAIN FAIR CONDITIONS WITH MOSTLY CLEAR SKIES
ACROSS THE MAJORITY OF THE BASIN. HOWEVER...A SURFACE TROUGH
EXTENDS FROM THE NW CARIBBEAN INTO THE SE GULF TO NEAR 23N87W
SUPPORTING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ACROSS CUBA
AND THE FLORIDA STRAITS. SCATTERED SHOWERS/THUNDERSTORMS ARE
ALSO ACROSS MUCH OF S FLORIDA. EXPECT WEAK SURFACE RIDGING TO
REMAIN OVER THE NRN GULF WITH SURFACE TROUGHING TO CONTINUE TO
EXTEND FROM THE WRN CARIBBEAN INTO THE SE GULF SUPPORTING
SHOWERS/THUNDERSTORMS ACROSS THIS AREA.

THE CARIBBEAN SEA...
MOIST CONDITIONS CONTINUE TO COVER MUCH OF THE YUCATAN
PENINSULA...NRN CENTRAL AMERICA...AND THE NW CARIBBEAN
ASSOCIATED WITH A WEAK 1009 MB SURFACE LOW NEAR 17N87W AND A
SURFACE TROUGH EXTENDING FROM THE LOW CENTER TO 24N85W...AS OF
2100 UTC. STRONG SHOWERS/THUNDERSTORMS ARE OVER PORTIONS OF SW
HONDURAS...NW NICARAGUA...AND ERN EL SALVADOR WITH SCATTERED
SHOWERS/THUNDERSTORMS TO THE E FROM 13N-18N BETWEEN 81W-86W. A
FEW ISOLATED SHOWERS/THUNDERSTORMS COVER THE REMAINDER OF THE NW
CARIBBEAN INCLUDING MUCH OF CUBA. SCATTERED
SHOWERS/THUNDERSTORMS ARE ALSO ACROSS HISPANIOLA LIKELY
ASSOCIATED WITH DAYTIME HEATING. STRONG SHOWERS/THUNDERSTORMS
COVER PORTIONS OF COSTA RICA AND PANAMA ASSOCIATED WITH THE E
PACIFIC MONSOON TROUGH TO THE W. THE REMAINDER OF THE BASIN IS
UNDER MOSTLY FAIR CONDITIONS DUE TO DRY AIR ALOFT BETWEEN AN
UPPER LEVEL RIDGE CENTERED OVER HONDURAS...AND AN UPPER LEVEL
TROUGH E OF THE LESSER ANTILLES. TRADEWIND FLOW OF 15-20 KTS IS
PRESENT ACROSS MUCH OF THE BASIN. EXPECT BROAD LOW PRESSURE TO
REMAIN OVER THE NW CARIBBEAN WITH MOIST CONDITIONS TO REMAIN
OVER THAT AREA.

THE ATLANTIC OCEAN...
AN UPPER LEVEL TROUGH OVER THE NE CONUS AND W ATLC SUPPORTS A
WEAK 1011 MB SURFACE LOW NEAR 32N76W...AS OF 2100 UTC. A COLD
FRONT EXTENDS FROM THE LOW CENTER TO THE FLORIDA COAST ALONG
29N77W 28N81W. SCATTERED SHOWERS/THUNDERSTORMS ARE NEAR THE WRN
EXTENT OF THE FRONT OVER FLORIDA. THE REMAINDER OF THE ACTIVITY
IS FARTHER E NEAR THE STRONGEST AREA OF DIFFLUENCE ALOFT.
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE FROM THE BAHAMAS TO
N OF THE DISCUSSION AREA BETWEEN 67W-73W. AN UPPER LEVEL RIDGE
EXTENDS FROM THE CARIBBEAN ACROSS HISPANIOLA TO NEAR 39N50W
SUPPORTING A BROAD SURFACE RIDGE ACROSS THE CENTRAL AND ERN ATLC
ANCHORED BY A 1034 MB HIGH NEAR 40N39W. OVER THE ERN ATLC...AN
UPPER LEVEL TROUGH EXTENDS FROM E OF THE LESSER ANTILLES NEAR
11N59W TO 29N46W CONTINUING TOWARDS THE AZORES ISLANDS AT
38N26W. AN UPPER LEVEL RIDGE COVERS THE TROPICAL E ATLC CENTERED
NEAR 13N30W. THE LAST VISIBLE SATELLITE IMAGES OF THE DAY ALONG
WITH GOES-R DUST ENHANCEMENTS INDICATE THAT A LARGE AREA OF DUST
EXTENDS FROM THE COAST OF AFRICA AROUND THE TROPICAL WAVE IN THE
E ATLC AND CONTINUING TO 45W.

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

$$
WALTON





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