[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 281723
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST WED JAN 28 2009

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...METEOROLOGICAL ANALYSIS...WEATHER
OBSERVATIONS...AND RADAR.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1645 UTC.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 6N7W 2N18W 1N27W 1N47W CROSSING THE
ITCZ NEAR 50W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS
WITHIN 90 NM N OF THE ITCZ FROM 20W-24W. CLUSTERS OF SCATTERED
MODERATE CONVECTION ARE WITHIN 75 NM OF LINE FROM 3N42W TO THE
ITCZ NEAR 1N35W.

...DISCUSSION...

GULF OF MEXICO...
BROAD UPPER RIDGE CONTINUES TO DOMINATE MUCH OF THE GULF
ANCHORED IN THE E PACIFIC REGION AND A DEEP LAYERED TROUGH CLIPS
THE NW GULF WITH AN ASSOCIATED STRONG COLD FRONT ENTERING THE
GULF OVER SE LOUISIANA NEAR 30N90W SW TO 26N96W THEN S INTO
MEXICO NEAR TAMPICO CONTINUING NW AS A STATIONARY BOUNDARY ALONG
THE SIERRA MADRE MOUNTAINS. A STRONG JET STREAM IS OVER THE SE
US FROM E TEXAS ACROSS THE MISSISSIPPI VALLEY THEN NE OVER
KENTUCKY AND WEST VIRGINIA. DENSE CLOUDS WITH SCATTERED SHOWERS
ARE OVER THE GULF WATERS W OF THE FRONT WHILE THE HEAVIER
ACTIVITY IS WELL INLAND OVER THE E US. THE SURFACE RIDGE
ANCHORED IN THE W ATLC IS RETREATING EASTWARD AHEAD OF THE COLD
FRONT WHILE A SECOND SURFACE RIDGE IS BUILDING OVER TEXAS
ANCHORED BY A 1026 MB HIGH NEAR DALLAS. STRONG NORTHERLY WINDS
ARE W OF THE FRONT WITH MODERATE SOUTHERLY WINDS COVER THE
REMAINDER OF THE AREA E OF THE FRONT. THE SOUTHERLY FLOW AHEAD
OF THE FRONT IS GENERATING PATCHES OF LOW CLOUDS WITH ISOLATED
SHOWERS WITHIN 120 NM E OF THE FRONT WHILE THE REMAINDER OF THE
GULF IS STILL ENJOYING CLEAR SKIES AND MILD TEMPERATURES. THE
FRONT IS EXPECTED TO CONTINUE SE ACROSS THE GULF EXITING THE
REGION FRI AFTERNOON/EVENING.

CARIBBEAN SEA...
AN UPPER LOW IS OVER THE WINDWARD PASSAGE/HAITI EXTENDING AN
UPPER TROUGH W TO NEAR THE CAYMAN ISLANDS. HOWEVER...STRONG
SUBSIDENCE AND DRY STABLE AIR ALOFT IS LIMITING ANY DEEP
SHOWERS/CONVECTION. A TIGHT SURFACE PRESSURE GRADIENT BETWEEN
THE SURFACE RIDGE OVER THE ATLC AND LOWER PRESSURE OVER THE
TROPICS CONTINUES TO PRODUCE MODERATE/STRONG EASTERLY TRADE
WINDS ACROSS THE CARIBBEAN BUT ARE EXPECTED TO DIMINISH ON FRI
AS THE COLD FRONT IN THE GULF OF MEXICO MOVES INTO THE CARIBBEAN
LATE FRI PUSHING THROUGH THE CARIBBEAN TO BE FROM PUERTO RICO TO
PANAMA LATE SUN. THESE TRADE WINDS ARE ALSO USHERING IN LOW
LEVEL CLOUDS WITH ISOLATED FAST MOVING SHOWERS ACROSS THE ENTIRE
CARIBBEAN AND BANKING LOW CLOUDS WITH SCATTERED SHOWERS ALONG
THE MOUNTAINS OF W PANAMA AND COSTA RICA.

ATLANTIC OCEAN...
TRANQUIL CONDITIONS WITH FAIR WEATHER CLOUDS COVER ALL BUT THE
FAR W ATLC WHERE PATCHES OF LOW CLOUDS WITH ISOLATED SHOWERS
HAVE MOVED OFF THE US E COAST N OF 28N E OF 78W DUE TO THE
APPROACHING FRONT IN THE GULF OF MEXICO. AN UPPER LOW IS OVER
THE WINDWARD PASSAGE/HAITI COVERS THE AREA TO OVER THE TURKS AND
CAICOS WITH NEAR ZONAL WESTERLY FLOW ALOFT COVERING THE
REMAINDER OF THE ATLC. THE ENTIRE ATLC BASIN HAS MODERATE TO
STRONG SUBSIDENCE AND DRY AIR ALOFT LIMITING ANY DEEP SHOWERS/
CONVECTION. A SURFACE RIDGE DOMINATES THE ATLC ANCHORED BY A
1029 MB HIGH NEAR 32N58W PRODUCING A TIGHT PRESSURE GRADIENT
BETWEEN THIS RIDGE OVER THE ATLC AND LOWER PRESSURE OVER THE
TROPICS RESULTING IN MODERATE/STRONG EASTERLY TRADE WINDS ACROSS
THE TROPICS.

$$
WALLACE





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