[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 180550
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT WED APR 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0515 UTC.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE E TROPICAL
ATLC NEAR 8N13W TO 3N18W WHERE THE ITCZ AXIS CONTINUES S OF THE
EQUATOR NEAR 24W. CLUSTERS OF SCATTERED MODERATE/STRONG
CONVECTION ARE FROM 7N TO JUST S OF THE EQUATOR E OF 11W TO
ACROSS THE PRIME MERIDIAN AND FROM 2N TO S OF THE EQUATOR
BETWEEN 27W-33W. SMALL CLUSTERS OF SCATTERED MODERATE/ISOLATED
STRONG CONVECTION ARE WITHIN 90 NM N OF THE ITCZ/MONSOON TROF
BETWEEN 14W-24W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER TROUGH DIPS S OVER THE MISSISSIPPI VALLEY INTO THE N
GULF N OF 28N SUPPORTING A COLD FRONT AT 18/0300 UTC EXTENDS
INTO THE GULF ALONG THE FLORIDA/ALABAMA BORDER 28N89W 23N93W TO
THE COAST OF S MEXICO NEAR 18N93W. SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS ARE WITHIN 200 NM E OF THE FRONT N OF 25N WITH
ISOLATED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS WITHIN 200
NM E OF THE REMAINDER OF THE FRONT. A BROAD UPPER RIDGE EXTENDS
FROM OVER CENTRAL AMERICA THROUGH THE YUCATAN CHANNEL ACROSS NE
FLORIDA INTO THE FAR W ATLC. A SURFACE RIDGE REMAINS ANCHORED IN
THE W ATLC EXTENDING INTO THE E GULF TO THE FRONT. STRONG
SUBSIDENCE AND DRY STABLE AIR ARE DOMINATING THE GULF W OF THE
FRONT AS A SURFACE RIDGE BUILD S OVER THE W GULF GIVING THE AREA
W OF THE FRONT MOSTLY CLEAR SKIS TONIGHT. A SURFACE TROUGH IS
OVER THE THE YUCATAN PENINSULA EXTENDING FROM 22N89W OVER S
MEXICO TO NEAR 16N91W. SCATTERED SHOWERS/THUNDERSTORMS ARE
INLAND OVER THE YUCATAN PENINSULA. COLD FRONT WILL SLOWLY WEAKEN
AND BECOME STATIONARY AS IT REACHES FROM THE W FLORIDA PANHANDLE
TO THE E BAY OF CAMPECHE WED. A WEAK LOW PRESSURE WILL FORM
ALONG THE FRONT AND TRACK NE THROUGH WED NIGHT PULLING THE
WEAKENING FRONTAL TROUGH TO THE E BEFORE DISSIPATING OVER NE
GULF THU. W ATLC SURFACE RIDGE WILL AGAIN EXTEND W INTO GULF
LATE THU THROUGH LATE FRI. A STRONG COLD FRONT IS FORECAST TO
ENTER THE NW GULF SAT FOLLOWED BY STRONG OFFSHORE FLOW.

CARIBBEAN SEA...
THE UPPER RIDGE OVER THE E GULF OF MEXICO IS ANCHORED OVER COSTA
RICA COVERING THE W CARIBBEAN WITH A WEAK UPPER TROUGH OVER THE
E CARIBBEAN WITH THE AXIS ALONG 67W. A RELATIVELY TIGHT PRESSURE
GRADIENT IS BEGINNING TO RELAX AS THE W ATLC SURFACE RIDGE
WEAKENS TO JUST OVER THE GREATER ANTILLES THUS WEAKENING THE
TRADE WINDS SOMEWHAT. REMNANT LOW LEVEL MOISTURE WITH SCATTERED
SHOWERS ARE WITHIN 120 NM OF A LINE FROM 17N60W ACROSS THE
LEEWARD ISLANDS TO 11N81W. THE TRADE WINDS CONTINUE TO BANK LOW
CLOUDS WITH SCATTERED SHOWERS AND POSSIBLE ISOLATED
THUNDERSTORMS INLAND AND WITHIN 120 NM ALONG THE COAST OF COSTA
RICA AND NICARAGUA. A SURFACE TROUGH OVER THE W YUCATAN
PENINSULA IS GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS
OVER THE PENINSULA AND INTO THE FAR NW CARIBBEAN WITHIN 60 NM
ALONG THE COAST N OF 17N. SURFACE RIDGE OVER W ATLC WILL
CONTINUE TO WEAKEN THROUGH THU DIMINISHING THE TRADE WINDS.

ATLANTIC OCEAN...
THE UPPER RIDGE OVER THE E GULF OF MEXICO AND THE W CARIBBEAN
COVERS THE W ATLC W OF 70W. A SURFACE RIDGE DOMINATES THE W ATLC
W OF 70W AND ANCHORED BY A 1023 MB HIGH NEAR 30N75W. A BROAD
UPPER TROUGH REMAINS OVER THE CENTRAL ATLC N OF 20N BETWEEN
45W-70W SUPPORTING A NEWLY DEVELOPED COLD FRONT THAT ENTERS THE
AREA NEAR 32N54W ALONG 27N57W 26N63W TO 29N66W. SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS ARE N OF 27N BETWEEN 51W-59W. THE
PRECEDING FRONT IS NOW STATIONARY ENTERING THE REGION NEAR
32N44W ALONG 24N46W TO 22N48W WHERE IT BECOMES A SURFACE TROUGH
ALONG 19N52W TO 15N56W. ISOLATED SHOWERS ARE POSSIBLE WITHIN 90
NM EITHER SIDE OF THE STATIONARY FRONT/SURFACE TROUGH. A SMALL
UPPER LOW IS OVER THE FAR E ATLC ALONG THE COAST OF WESTERN
SAHARA NEAR 25N15W WITH A BROAD E/W UPPER RIDGE DOMINATING THE
TROPICAL ATLC. A LARGE SURFACE RIDGE DOMINATES THE E ATLC N OF
10N E OF 40W ANCHORED BY A 1035 MB HIGH OVER THE AZORES. THIS IS
LEAVING THE REMAINDER OF THE ATLC WITH FAIR WEATHER TONIGHT. W
ATLC SURFACE RIDGE WILL REMAIN NEARLY STATIONARY AND WEAKEN
THROUGH THU AS A WEAK FRONT MOVES INTO THE FAR NW PORTION. THE
FRONT WILL THEN LIFT BACK N AS A WARM FRONT LATE THU INTO LATE
FRI AS STRONGER RIDGE BUILDS FROM NEAR BERMUDA TO CENTRAL
FLORIDA FRI AND SAT. THE CENTRAL ATLC COLD FRONT WILL MOVE
SLOWLY E AS THE SURFACE LOW MOVES S INTO THE DISCUSSION AREA
WED. THE FRONT WILL THEN DISSIPATE WED NIGHT THROUGH FRI BEFORE
THE LOW MOVES NE OUT OF THE AREA.

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

$$
PAW




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