[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 130511
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 AM EST THU 13 JAN 2005

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA... GULF OF MEXICO...CARIBBEAN SEA...NORTHEASTERN
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
0445 UTC.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 7N10W 2N24W 6N44W 7N60W. SCATTERED
CLUSTERS OF SCATTERED MODERATE CONVECTION ARE FROM EQ-5N BETWEEN
16W-38W.

...DISCUSSION...
GULF OF MEXICO...
THE DRY/TRANQUIL PATTERN OVER THE GULF IS BEGINNING TO GIVE WAY
TO A DEEP LAYERED TROUGH CURRENTLY MOVING ACROSS TEXAS INTO THE
NW GULF AND INTO THE SE UNITED STATES AND WILL CONTINUE TO PUSH
THE RIDGE CURRENTLY OVER THE E GULF INTO THE W ATLC ALLOWING A
COLD FRONT TO PENETRATE THE NW GULF LATER TODAY. AMPLE DEEP
LAYERED MOISTURE ALONG WITH GOOD UPPER LEVEL DYNAMICS WILL
SUPPORT INCREASING SHOWERS/THUNDERSTORMS AHEAD OF THE FRONT
ESPECIALLY N OF 26N TODAY. THE FRONT AND ASSOCIATED SHOWER/
THUNDERSTORM ACTIVITY WILL ADVANCE QUICKLY ACROSS THE GULF
REACHING FLORIDA BY FRIDAY. ELSEWHERE...A HIGH PRESSURE RIDGE
EXTENDING FROM THE YUCATAN CHANNEL ACROSS CENTRAL FLORIDA INTO
GEORGIA WILL RETREAT E DURING THE NEXT 48 HOURS AS THE TROUGH/
FRONT APPROACHES.

CARIBBEAN SEA...
BROAD MID/UPPER LEVEL RIDGE COVERS THE CARIBBEAN WITH MEAN AXIS
EXTENDING FROM VENEZUELA NW TO 20N75W. SW TO W FLOW AROUND THE
N PERIPHERY OF THE RIDGE IS ADVECTING UPPER LEVEL TROPICAL
MOISTURE FROM THE E PACIFIC ACROSS CENTRAL AMERICA AND THE
CARIBBEAN E OF A LINE FROM E CUBA TO HONDURAS. DIVERGENT UPPER
LEVEL FLOW JUST E OF NICARAGUA IS SUPPORTING AN AREA OF
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS FROM 12N-16N BETWEEN
78W-84W. STRONG SUBSIDENCE AND DRY AIR COVERS THE NW CARIBBEAN N
OF A LINE FROM 20N78W TO 16N86W.

ATLANTIC...
A BROAD/FLAT MID/UPPER LEVEL RIDGE COVERS ALL BUT THE FAR E ATLC
WHERE A TROUGH EXTENDS S FROM THE CANARY ISLANDS TO THE CAPE
VERDE ISLANDS. A NEAR ZONAL PATTERN EXISTS BETWEEN 40W-80W.
UPSTREAM MOISTURE IS RIDING UP AND OVER A LARGE RIDGE OVER THE E
UNITED STATES LEAVING STRONG SUBSIDENCE AND VERY DRY MID/UPPER
LEVEL AIR OVER THE ATLC N OF 20N. THIS PATTERN IS PRODUCING
UNUSUALLY TRANQUIL WEATHER AND A NOTICEABLE ABSENCE OF
SIGNIFICANT CLOUDINESS OVER THE ENTIRE SUBTROPICAL ATLC. AT THE
SURFACE...HIGH PRESSURE DOMINATES THE ATLC N OF 20N WITH A
WEAKNESS IN THE FORM OF A SURFACE TROUGH EXTENDING OVER THE
CENTRAL ATLC FROM A COLD FRONT N OF THE REGION THROUGH 32N35W SW
TO 28N45W. ONLY ISOLATED SHOWERS ARE POSSIBLE WITHIN 45 NM OF
THE SURFACE TROUGH DUE TO THE DRY STABLE AIR ACROSS THE REGION.

$$
WALLACE


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