[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 230551
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 AM EST SUN 23 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
0515 UTC.

...ITCZ...

ITCZ AXIS EMERGES OFF THE CONTINENT OF AFRICA NEAR 5N9W 3N34W
8N42W 5N52W.  ISOLATED MODERATE WITHIN 60 NM OF AXIS W OF 47W
AND WITHIN 45 NM OF AXIS BETWEEN 11W-29W.

...DISCUSSION...

GULF OF MEXICO...
COLD FRONT IS SWEEPING THRU THE NW GULF AND EXTENDS FROM NE
MEXICO THRU THE CENTRAL GULF NEAR 28N90W INTO THE FLORIDA
PANHANDLE JUST E OF TALLAHASSEE.  THIS FRONT IS PART OF THE
STRONG NOR'EASTER SE OF NEW YORK BRINGING FAST COOLING TO THE
AREA.  STRONG GALE FORCE WINDS ARE RIPPING BEHIND THE FRONT OVER
GULF WATERS WITH SEVERAL BUOYS REPORTING AT LEAST 30 KT.  SEE
OFFSHORE WATERS FORECAST UNDER AWIPS/WMO HEADER MIAOFFNT4/FZNT24
KNHC FOR MORE DETAILS.  NARROW LINE OF SHOWERS/ISOLATED TSTMS IS
WITHIN 30 NM OF THE FRONT WITH DRAMATIC CHANGES BEHIND THE FRONT
AS THE TEMPERATURE IN TALLAHASSEE FELL 10 DEGREES IN ONE HOUR
ALONG WITH A DROP IN DEWPOINT OF 27 DEGREES!  FRONT SHOULD SURGE
THRU THE REST OF THE GULF BY LATE SUN BRINGING MAYBE THE COLDEST
NIGHT OF THE SEASON MON FOR LOUISIANA EASTWARD THRU S FLORIDA.
MOST OF THE UPPER LEVEL LIFT/DYNAMICS WILL SKIRT JUST N OF THE
AREA WITH ENOUGH LOW LEVEL MOISTURE POOLING TO SUPPORT WIDELY
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ALONG THE FRONTAL
BOUNDARY ESPECIALLY OVER THE SE GULF AND FLORIDA STRAITS. GIVEN
THE STRENGTH OF THE ANTICIPATED COLD AIR ADVECTION WITH THIS
FRONT...EXPECT WIDESPREAD COLD AIR STRATOCUMULUS CLOUDINESS
BEHIND FRONT.

CARIBBEAN SEA...
WEAK MIDDLE/UPPER LEVEL TROUGH LIES FROM HISPANIOLA TO NICARAGUA
WITH LITTLE SENSIBLE WEATHER IMPACTS.  MOST OF THE CARIBBEAN IS
DOMINATED BY DEEP-LEVEL DRY AIR WITH DEWPOINTS STILL IN THE 60W
ACROSS MUCH OF THE GREATER ANTILLES.  MOISTURE RETURNS CLOSER TO
AVERAGE S OF 16N BETWEEN 65W-75W WITH WIDELY SCATTERED SHOWERS
AND A FEW TSTMS PRESENT ALONG WITH THE DISSIPATED TAIL END OF
THE FRONT THAT CAME THRU A FEW DAYS.  THIS ACTIVITY IS EXPECTED
TO BE GRADUALLY DRAWN NW DURING THE NEXT 48 HOURS AHEAD OF A
COLD FRONT WHICH WILL BE MOVING INTO THE NW CARIBBEAN SUN
NIGHT.  WHILE SHOWER ACTIVITY ALONG THE FRONT ITSELF WILL BE
LIMITED TO A NARROW BAND OF WIDELY SCATTERED SHOWERS...
INCREASING LIFT/DYNAMICS AHEAD OF AN AMPLIFYING MIDDLE TO UPPER
LEVEL TROUGH OVER THE W ATLC SHOULD PRODUCE SCATTERED SHOWERS
AND THUNDERSTORMS FROM THE SW CARIBBEAN NEWD OVER
HISPANIOLA/PUERTO RICO LATE SUN INTO TUE.

ATLANTIC...
CONDITIONS ARE ACTUALLY RATHER QUIET FOR MOST OF THE AREA WITH
NEAR ZONAL FLOW DOMINATING THE W TWO-THIRDS OF THE ATLC IN
BETWEEN ONE TROUGH LIFTING N OF THE AREA OVER THE CENTRAL ATLC
WHILE ANOTHER IS AMPLIFYING OVER THE E UNITED STATES. CONVECTION
IS MINIMAL EVEN IN THE ITCZ.  MIDDLE TO UPPER LEVEL SUPPORT IS
MINISCULE ALONG A SURFACE COLD FRONT OVER THE CENTRAL ATLC FROM
32N42W TO 25N60W THEN STATIONARY TO 25N70W SHIFTING NW AS A WEAK
WARM FRONT TO 31N73W. ISOLATED SHOWERS AND SCATTERED LOW CLOUDS
ACCOMPANY THE FRONTAL BOUNDARY IN THE ABSENCE OF UPPER LEVEL
SUPPORT.  THE ENTIRE ATLC FRONT WILL BEGIN WASHING OUT TODAY AS
A MUCH STRONGER FRONT PUSHES OFF THE SE UNITED STATES COAST.
THIS NEW FRONT WILL PRODUCE VERY STRONG WINDS NEAR GALE FORCE
OVER THE W ATLC AND USHER IN ONE OF THE COLDEST AIRMASSES THUS
FAR THIS SEASON. THE STRONGEST UPPER LEVEL DYNAMICS/LIFT WILL
CLIP THE N PORTION...N OF 25N...OF THE AREA ALLOWING SCATTERED
SHOWERS/TSTMS TO DEVELOP ALONG THE FRONT OVERNIGHT AND SUNDAY.
THE UPPER TROUGH THEN AMPLIFIES WELL S OF 25N LATE SUN AND
MONDAY ALLOWING SHOWERS/THUNDERSTORMS TO DEVELOP ALONG THE
ENTIRE FRONT WHICH WILL EXTEND FROM APPROXIMATELY 32N52W TO
HISPANIOLA MON AFTERNOON.  OVER THE CENTRAL ATLC...MIDDLE TO
UPPER LEVEL RIDGING WILL BUILD NWD AHEAD OF W ATLC AMPLIFYING
TROUGH WITH MEAN AXIS ALONG 40W BY MONDAY.  THIS BUILDING RIDGE
SHOULD FORCE MOST OF THE UPSTREAM MOISTURE N OF THE AREA LEAVING
THE CENTRAL ATLC UNDER DRY/TRANQUIL CONDITIONS THROUGH THE NEXT
48 HOURS.  OVER THE E ATLC...A WEAK UPPER TROUGH W OF THE CANARY
ISLANDS IS PRODUCING ISOLATED SHOWERS ALONG A TROUGH STRETCHING
FROM 32N32W TO 21N39W WHERE IT WEAKENS TO 16N50W.  E OF THE
FRONT...EARLIER VISIBLE SATELLITE IMAGERY CONTINUES TO SHOW DUST
AND VERY DRY AIR MOVING OFF THE CONTINENT OF AFRICA SE OF A LINE
FROM THE CANARY ISLANDS TO 5N45W.

$$
BLAKE


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