[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 172336
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT TUE APR 17 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.

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

THE MONSOON TROUGH EXTENDS INLAND ACROSS WEST AFRICA INTO THE E
TROPICAL ATLC ACROSS THE COAST OF GUINEA-BISSAU NEAR 12N16W TO
5N22W...WHERE THE ITCZ AXIS CONTINUES ALONG 2N32W CROSSING THE
EQUATOR ALONG 40W TO THE COAST OF BRAZIL NEAR 2S44W. CLUSTERS OF
SCATTERED MODERATE TO STRONG CONVECTION ARE FROM 4N TO 5S
BETWEEN 27W-42W. SIMILAR CONVECTION IS S OF 6N BETWEEN THE PRIME
MERIDIAN AND 17W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER LEVEL TROUGH AXIS DIPS S FROM THE CENTRAL PLAIN STATES
TO ERN TEXAS WITH A SHORTWAVE EMBEDDED AT THE BASE OF THE UPPER
TROUGH MOVING ACROSS THE NW GULF BASIN SUPPORTING LOW PRESSURE
SYSTEM OVER S-WRN MISSISSIPPI AND ASSOCIATED COLD FRONT THAT
EXTENDS SW ACROSS THE AREA FROM THE COAST OF MISSISSIPPI NEAR
30N89W TO THE COAST OF MEXICO JUST S OF TAMPICO NEAR 21N97W.
DOPPLER RADAR IMAGERY DEPICTS SCATTERED MODERATE TO HEAVY
SHOWERS AND THUNDERSTORMS WITHIN 60 NM ON EITHER SIDE OF THE
FRONT N OF 26N...WITH ISOLATED SHOWERS AND POSSIBLE
THUNDERSTORMS IN THE VICINITY OF THE FRONTAL BOUNDARY S OF 26N.
STRONGER CONVECTION IS OVER THE ERN BAY OF CAMPECHE AND THE NRN
COASTAL WATERS OF THE YUCATAN PENINSULA S OF 23N BETWEEN
87W-94W. COMPUTER MODELS SUGGEST THE FRONT WILL LOOSE MOMENTUM
DURING THE EVENING HOURS AND DISSIPATE OVER NE GULF WATERS BY
WEDNESDAY.

CARIBBEAN SEA...
DRY AIR AND SUBSIDENCE ALOFT COVERS A GREAT PORTION OF THE
CARIBBEAN BASIN THIS EVENING...ASSOCIATED TO AN UPPER LEVEL
RIDGE OF HIGH PRESSURE CENTERED OVER COSTA RICA. A MODERATE TO
STRONG PRESSURE GRADIENT COVERS THE CARIBBEAN...SUPPORTING A
TRADEWIND FLOW IN THE RANGE OF 15-25 KT DEPICTED ON A RECENT
ASCAT SCATTEROMETER PASS. THIS FLOW IS PUSHING LOW LEVEL
MOISTURE AGAINST THE COAST OF NICARAGUA GENERATING SCATTERED
SHOWERS AND THUNDERSTORMS WITHIN 100 NM OFF THE COAST. A
DISSIPATING SHEAR AXIS REMAINS OVER THE SE BASIN EXTENDING FROM
13N63W TO 13N72W. SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS
ARE WITHIN 70-120 NM N OF THE SHEAR AXIS. OTHERWISE...SMALL
CLUSTERS OF WEAK CONVECTION ARE ELSEWHERE ACROSS THE DISCUSSION
AREA. THE PRESSURE GRADIENT IS EXPECTED TO REMAIN CONSTRICTED
THROUGH WEDNESDAY.

ATLANTIC OCEAN...
A SURFACE RIDGE ANCHORED BY A 1024 MB HIGH NEAR 30N76W DOMINATES
THE WRN ATLC WATERS W OF 65W. A DEEP OCCLUDED 1002 MB LOW IS
CENTERED NEAR 33N60W. A FORMING COLD FRONT EXPANDS S OF THE LOW
CENTER ANALYZED FROM 32N54W TO 27N59W TO 30N65W. SCATTERED WEAK
TO ISOLATED MODERATE CONVECTION IS WITHIN 50-100 NM E AND S OF
THE FRONTAL BOUNDARY. A SECONDARY FRONTAL BOUNDARY EXTENDS INTO
THE AREA AS STATIONARY ALONG 32N44W TO 20N48W...WHERE IT
DISSIPATES TO 15N58W. SCATTERED WEAK CONVECTION IS WITHIN 70 NM
ON EITHER SIDE OF THE BOUNDARY. ISOLATED WEAK CONVECTION IS
POSSIBLE WITHIN 30 NM EITHER SIDE OF THE REMAINDER OF THE FRONT.
THIS LOW PRESSURE SYSTEM IS EXPECTED TO SHIFT SSW TONIGHT AND
ENTER THE DISCUSSION AREA BY WEDNESDAY MORNING. A BROAD SURFACE
RIDGE OVERTAKES THE REMAINDER OF THE ATLC WITH FAIR WEATHER
CONDITIONS E OF 42W.

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

$$

GARCIA




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