[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 171049
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1015 UTC.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE E TROPICAL
ATLC NEAR 9N13W TO 5N19W WHERE THE ITCZ AXIS CONTINUES ALONG
2N26W TO 1N35W THEN S OF THE EQUATOR NEAR 40W. CLUSTERS OF
SCATTERED MODERATE/STRONG CONVECTION ARE FROM 5N TO JUST S OF
THE EQUATOR E OF 15W TO ACROSS THE PRIME MERIDIAN AND FROM 4N TO
THE EQUATOR BETWEEN 17W-35W. SCATTERED MODERATE/ISOLATED STRONG
CONVECTION IS WITHIN 75 NM ALONG THE EQUATOR BETWEEN 35W-43W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER TROUGH DIPS S FROM THE CENTRAL PLAIN STATES TO OVER
TEXAS TO OVER THE NW GULF WITH A SHORTWAVE TROUGH ALONG 91W N OF
28N. THE BROAD UPPER TROUGH IS SUPPORTING A COLD FRONT AT
17/0900 UTC EXTENDS INTO THE GULF OVER W LOUISIANA NEAR 30N93W
ALONG 28N96W ACROSS TEXAS NEAR BROWNSVILLE AND INTO NE MEXICO.
SCATTERED TO HEAVY SHOWERS WITH SCATTERED TO NUMEROUS
THUNDERSTORMS ARE E OF THE FRONT AND W OF A LINE FROM THE N GULF
COAST NEAR 29N30W 24N91W 22N96W TO 20N97W. AN UPPER RIDGE
EXTENDS FROM THE E PACIFIC REGION ACROSS THE YUCATAN PENINSULA
TO ACROSS THE FLORIDA PENINSULA INTO THE FAR W ATLC. A SURFACE
RIDGE ANCHORED IN THE W ATLC EXTENDS ALONG THE N GULF COAST TO
THE FRONT GIVING THE NE GULF SE 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 25N90W TO OVER
S MEXICO NEAR CIUDAD DEL CARMEN. CLUSTERS OF SCATTERED SHOWERS/
ISOLATED THUNDERSTORMS ARE OVER THE NE GULF N OF 24N E OF 90W
LEAVING THE REMAINDER OF THE GULF WITH MOSTLY CLEAR SKIES THIS
MORNING. THE FRONT IS EXPECTED TO STALL ALONG 90W THEN SHIFT NE
TONIGHT AND DISSIPATE OVER NE GULF WATER WED. W ATLC SURFACE
RIDGE ALONG 31N WILL EXTEND W INTO GULF LATE THU THROUGH LATE
FRI. THE NEXT STRONG COLD FRONT WILL ENTER THE NW GULF SAT.

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 70W. A RELATIVELY TIGHT PRESSURE GRADIENT COVERS THE
CARIBBEAN. THE SURFACE RIDGE OVER THE W ATLC EXTENDS S ACROSS
THE GREATER ANTILLES TO OVER THE N CARIBBEAN N OF 19N AND IS
GENERATING FRESH TO STRONG EASTERLY TRADE WINDS ACROSS THE
BASIN. A WEAKENING SHEAR AXIS REMAINS OVER THE E CARIBBEAN
EXTENDING FROM THE CENTRAL ATLC FRONT OVER MARTINIQUE IN THE
LESSER ANTILLES TO NEAR 14N68W GENERATING SCATTERED SHOWERS AND
POSSIBLE ISOLATED THUNDERSTORMS WITHIN 60 NM EITHER SIDE OF THE
SHEAR AXIS. A BAND OF LOW LEVEL MOISTURE WITH SCATTERED SHOWERS
AND POSSIBLE ISOLATED THUNDERSTORMS IS WITHIN 45/60 NM OF A LINE
FROM SW HAITI TO NEAR 17N81W INCLUDING JAMAICA. A SECOND BAND OF
LOW LEVEL MOISTURE WITH SCATTERED SHOWERS IS STREAMING W FROM
THE SHEAR AXIS WITHIN 45 NM OF LINE FROM 14N69W TO 13N82W. THE
TRADE WINDS ARE BANKING LOW CLOUDS WITH SCATTERED SHOWERS AND
POSSIBLE ISOLATED THUNDERSTORMS INLAND AND WITHIN 60 NM ALONG
THE COAST OF W PANAMA AND COSTA RICA S OF 11N W OF 81W.
DISSIPATING STATIONARY FRONT WILL BECOME DIFFUSE LATER TODAY.
OTHERWISE W ATLC SURFACE RIDGE WILL MAINTAIN STRONG TRADE WINDS
BUT WILL DIMINISH THROUGH WED.

ATLANTIC OCEAN...
A SURFACE RIDGE DOMINATES THE W ATLC N OF 19N W OF 65W AND
ANCHORED BY A 1025 MB HIGH NEAR 30N73W. A BROAD UPPER TROUGH
REMAINS OVER THE CENTRAL ATLC N OF 23N BETWEEN 40W-70W
SUPPORTING A COLD FRONT THAT ENTERS THE AREA NEAR 32N45W TO
27N45W WHERE IT BECOMES STATIONARY ALONG 23N46W TO 19N51W WHERE
IT DISSIPATES TO 16N58W THEN BECOMES A SHEAR AXIS ENTERING THE
CARIBBEAN OVER MARTINIQUE. SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS ARE WITHIN 120 NM E OF THE FRONT N OF 27N AND
SCATTERED SHOWERS WITHIN 60 NM E OF THE FRONT N OF 23N. ISOLATED
SHOWERS ARE POSSIBLE WITHIN 45 NM EITHER SIDE OF THE REMAINDER
OF THE FRONT/SHEAR AXIS. A SMALL UPPER LOW IS OVER THE E ATLC
NEAR 25N17W. A LARGE SURFACE RIDGE DOMINATES THE E ATLC N OF 15N
E OF 40W ANCHORED WELL N OF THE AZORES. THIS IS LEAVING THE
REMAINDER OF THE ATLC WITH FAIR WEATHER THIS MORNING. W ATLC
SURFACE RIDGE WILL WEAKEN. A SURFACE TROUGH WILL MOVE S OVER THE
W/CENTRAL ATLC LATER TODAY. A SECOND COLD FRONT WILL APPROACH
THE W ATLC THU. A SURFACE RIDGE WILL REBUILD AND EXTEND FROM
BERMUDA TO CENTRAL FLORIDA FRI AND SAT.

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

$$
PAW




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