[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 121731
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST WED 12 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1645 UTC.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 9N10W 2N25W 10N50W 12N70W 10N80W.
SCATTERED MODERATE CONVECTION FROM 2N-5N BETWEEN 32W-40W AND
FROM 8N-10N BETWEEN 40W-55W.  WIDELY SCATTERED MODERATE
CONVECTION ELSEWHERE ALONG ITCZ TROUGH THE CARIBBEAN.

...DISCUSSION...
GULF OF MEXICO...
THE PATTERN OVER THE GLFMEX CONTINUES TO BE DRY/TRANQUIL AS
LARGE SCALE RIDGING MAINTAINS ITS GRIP OVER THE E HALF OF THE
UNITED STATES.  HOWEVER...A DEEP LAYERED TROUGH CURRENTLY
MOVING  ACROSS THE SW UNITED STATES IS EXPECTED TO PUSH THE
RIDGE INTO THE W ATLC ALLOWING A COLD FRONT TO PENETRATE THE NW
GLFMEX TOMORROW.
AMPLE LOW LEVEL MOISTURE ALONG WITH GOOD UPPER LEVEL DYNAMICS
WILL SUPPORT INCREASING SHOWERS/THUNDERSTORMS ALONG THE FRONT
ESPECIALLY N OF 26N ON THURSDAY.  THE FRONT AND ASSOCIATED
SHOWER/THUNDERSTORM ACTIVITY WILL ADVANCE QUICKLY ACROSS THE
GLFMEX REACHING FLORIDA FRIDAY.  ELSEWHERE...A HIGH PRESSURE
RIDGE EXTENDING ACROSS CENTRAL FLORIDA AND THE GLFMEX ALONG 25N
WILL RETREAT SEWD DURING THE NEXT 48 HOURS AS THE FRONT
APPROACHES.  EXPECT STRONG RETURN FLOW OVER THE W GLFMEX INTO
TEXAS WITH STRONG NLY FLOW DEVELOPING BEHIND COLD FRONT THU.

CARIBBEAN SEA...
BROAD MIDDLE TO UPPER LEVEL RIDGE COVERS THE CARIBBEAN WITH MEAN
AXIS EXTENDING FROM VENEZUELA NW TO 17N85W.  SW TO WLY 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 HISPANIOLA TO HONDURAS.
DIVERGENT UPPER LEVEL FLOW JUST E OF NICARAGUA IS SUPPORTING AN
AREA OF SCATTERED MODERATE CONVECTION FROM 10N-15N BETWEEN
78W-85W WITH WIDELY SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS
ELSEWHERE OVER THE E CARIBBEAN ESPECIALLY WITHIN 90 NM EITHER
SIDE OF A LINE FROM TRINIDAD TO 14N80W. FURTHER W...STRONG
SUBSIDENCE AND DRY AIR COVERS THE NW CARIBBEAN.

ATLANTIC...
A BROAD/FLAT MIDDLE TO UPPER LEVEL RIDGE COVERS ALL BUT THE FAR
E ATLC WATERS WHERE A TROUGH TRAILS SWD FROM N AFRICA TO THE
CAPE VERDE ISLANDS.  A WEAK TROUGH SPLITS THE RIDGE OVER THE
CENTRAL ATLC WITH A SMALL AREA OF CYCLONIC FLOW IN AN OTHERWISE
NEAR ZONAL PATTERN.  UPSTREAM MOISTURE IS RIDING UP AND OVER A
LARGE RIDGE OVER THE E UNITED STATES LEAVING STRONG SUBSIDENCE
AND VERY DRY MIDDLE TO 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 LOW LEVELS...A WEAK ELY DISTURBANCE
NE OF THE BAHAMAS IS PRODUCING A SMALL AREA OF SCATTERED SHOWERS
FROM 24N-27N BETWEEN 68W-73W. ELSEWHERE...A 1016 MB LOW NEAR THE
AZORES TRAILS A WEAK COLD FRONT SWD ALONG 32N40W TO 31N50W WHERE
IT DEGENERATES INTO A REMNANT FRONTAL TROUGH TO 28N62W. ONLY A
FEW ISOLATED SHOWERS ACCOMPANY THIS FEATURE.  FURTHER N...A MUCH
STRONGER COLD FRONT IS PUSHING SWD OVER THE CENTRAL ATLC FROM
38N40W TO BERMUDA.  THE SUBTROPICAL RIDGE EXTENDS FROM THE
CANARY ISLANDS TO THE CENTRAL ATLC NEAR 27N40W.

$$
JR




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