[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 170545
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 AM 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 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 2N21W WHERE THE ITCZ AXIS CONTINUES S OF THE
EQUATOR NEAR 30W. CLUSTERS OF SCATTERED MODERATE/STRONG
CONVECTION ARE FROM 5N TO S OF THE EQUATOR E OF 20W TO ACROSS
THE PRIME MERIDIAN AND FROM 4N TO THE EQUATOR BETWEEN 30W-44W.
SCATTERED MODERATE CONVECTION IS FROM 6N-10N BETWEEN 46-50W.

...DISCUSSION...

GULF OF MEXICO...
A STRONG UPPER TROUGH DIPS S FROM THE CENTRAL PLAIN STATES TO
OVER TEXES CLIPPING THE FAR NW GULF SUPPORTING A COLD FRONT AT
17/0300 UTC ALONG THE TEXAS COAST FROM THE LOUISIANA BORDER TO
CORPUS CHRISTI WITH A SQUALL LINE EXTENDING INTO THE GULF WATERS
FROM S MISSISSIPPI NEAR 31N89W ALONG 27N94W INTO NE MEXICO NEAR
25N98W GENERATING SCATTERED TO HEAVY SHOWERS WITH SCATTERED TO
NUMEROUS THUNDERSTORMS WITHIN 45 NM E AND 90/120 NM W OF THE
SQUALL LINE. AN UPPER RIDGE EXTENDS FROM THE E PACIFIC REGION
ACROSS THE YUCATAN PENINSULA TO THE BIG BEND AREA OF FLORIDA. A
SURFACE RIDGE ANCHORED IN THE W ATLC EXTENDS ALONG THE N GULF
COAST TO THE ALABAMA/MISSISSIPPI BORDER GIVING THE NE GULF SW
RETURN FLOW. STRONG SUBSIDENCE AND DRY STABLE AIR DOMINATES THE
S AND NE GULF. HOWEVER A SURFACE TROUGH IS OVER THE S GULF
EXTENDING FROM 25N88W TO OVER S MEXICO NEAR CIUDAD DEL CARMEN
GENERATING CLUSTERS OF SCATTERED SHOWERS/ISOLATED THUNDERSTORMS
S OF 27N TO INLAND OVER THE YUCATAN PENINSULA BETWEEN 85W-90W
LEAVING THE REMAINDER OF THE GULF WITH CLEAR SKIES TONIGHT. THE
COLD FRONT WILL EXTEND FROM THE MISSISSIPPI DELTA TO NE MEXICO
ON TUE AND FROM THE FLORIDA PANHANDLE TO THE CENTRAL WATERS WED
MOVING OUT OF GULF ON THU. REMNANTS OF THE FRONT WILL DISSIPATE
OVER N FLORIDA THU NIGHT AND FRI AS AN E TO W RIDGE BUILDS
ACROSS THE N GULF COAST.

CARIBBEAN SEA...
THE UPPER RIDGE OVER THE E GULF OF MEXICO COVERS THE W CARIBBEAN
WITH A WEAK UPPER TROUGH OVER THE E CARIBBEAN WITH THE AXIS
ALONG 71W. A RELATIVELY TIGHT PRESSURE GRADIENT COVERS THE
CARIBBEAN AS THE SURFACE RIDGE OVER THE W ATLC EXTENDS S ACROSS
THE GREATER ANTILLES TO OVER THE N CARIBBEAN N OF 18N AND IS
GENERATING FRESH TO STRONG EASTERLY TRADE WINDS ACROSS THE
BASIN. A SHEAR AXIS REMAINS OVER THE E CARIBBEAN EXTENDING FROM
THE CENTRAL ATLC FRONT BETWEEN DOMINICA AND MARTINIQUE IN THE
LESSER ANTILLES TO NEAR 15N72W GENERATING SCATTERED SHOWERS AND
POSSIBLE ISOLATED THUNDERSTORMS WITHIN 60/75 NM EITHER SIDE OF
THE SHEAR AXIS. A BAND OF LOW LEVEL MOISTURE WITH SCATTERED
SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS IS WITHIN 60/75 NM
OF A LINE FROM SW HAITI ALONG 18N80W TO THE YUCATAN PENINSULA
NEAR 21N87W INCLUDING JAMAICA. A SECOND BAND OF LOW LEVEL
MOISTURE WITH SCATTERED SHOWERS AND POSSIBLE ISOLATED
THUNDERSTORMS IS STREAMING W FROM THE SHEAR AXIS WITHIN 60/75 NM
14N72W TO 13N79W THEN SPREADING ACROSS THE SW CARIBBEAN S OF 13N
BETWEEN 77W-84W. THE SHEAR AXIS WILL BECOME DIFFUSE ON TUE.
OTHERWISE W ATLC SURFACE RIDGE WILL MAINTAIN TRADE WINDS THROUGH
TUE THEN DIMINISHING FROM THE N WED THROUGH FRI.

ATLANTIC OCEAN...
A SURFACE RIDGE DOMINATES THE W ATLC N OF 18N W OF 60W AND
ANCHORED BY A 1026 MB HIGH NEAR 30N72W. A BROAD UPPER TROUGH
REMAINS OVER THE CENTRAL ATLC N OF 20N BETWEEN 40W-75W
SUPPORTING A COLD FRONT THAT ENTERS THE AREA NEAR 32N45W ALONG
21N46W TO 17N54W WHERE IT BECOMES A SHEAR AXIS ENTERING THE
CARIBBEAN BETWEEN DOMINICA AND MARTINIQUE. SCATTERED SHOWERS
WITH POSSIBLE ISOLATED THUNDERSTORMS ARE WITHIN 150 NM E OF THE
FRONT N OF 27N WITH ISOLATED SHOWERS WITHIN 45 NM EITHER SIDE OF
THE REMAINDER OF THE FRONT/SHEAR AXIS. A SMALL UPPER LOW IS OVER
THE E ATLC NEAR 25N18W. A LARGE SURFACE RIDGE DOMINATES THE E
ATLC N OF 15N E OF 40W ANCHORED BY A 1036 MB HIGH OVER THE
AZORES. THIS IS LEAVING THE REMAINDER OF THE ATLC WITH FAIR
WEATHER TONIGHT. SURFACE RIDGE OVER THE W ATLC WILL WEAKEN
ALLOWING A COLD FRONT TO PASS THROUGH THE AREA ON TUE. A SECOND
COLD FRONT WILL STALL AND DISSIPATE OVER THE FAR NW WATERS THU.
A SURFACE RIDGE WILL EXTEND FROM BERMUDA TO CENTRAL FLORIDA ON
FRI AND SAT.

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

$$
PAW






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