[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 201725
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST THU 20 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 5N9W 3N23W 4N30W 5N45W 4N52W.
SCATTERED MODERATE CONVECTION FROM 5N-8N BETWEEN 31W-35W.
WIDELY SCATTERED MODERATE WITHIN 45 NM OF ITCZ AXIS FROM 26W-31W.

...DISCUSSION...

GULF OF MEXICO...W AND CENTRAL ATLANTIC...
PERSISTENT TROUGH REMAINS OVER THE W ATLC ALONG ABOUT 70W WITH A
SHORTWAVE ALONG 73W CAUSING THE SOUTHERN END TO BECOME A BIT
SHARPER THAN RECENT DAYS.  THE BROAD TROUGH CONTROLS THE E GULF
ALL THE WAY TO 50W WITH GENERALLY DRY AIR PRESENT IN THE
MID/UPPER LEVELS.  A NEW SURGE OF COOLER/DRIER AIR IS BEHIND A
COLD FRONT FROM 32N71W TO JUST S OF CAPE CANAVERAL WITH BROKEN
LOW CLOUDS AND A FEW SHOWERS BEHIND THE FRONT...EVEN ACROSS THE
NE GULF N OF 26N E OF 90W.  S OF THE FRONT.. PARTLY CLOUDY SKIES
ABOUND UNTIL REACHING THE FRONTAL SYSTEM IN THE CENTRAL ATLC.
COLD FRONT ENTERS THE AREA NEAR 32N49W INTO A WEAK 101MB LOW
NEAR 21N55W DISSIPATING SW JUST S OF GUADELOUPE.  WIDELY
SCATTERED SHOWERS ARE WITHIN 180 NM OF FRONT ALONG WITH ISOLATED
TSTMS N OF 26N DUE TO A WEAKENING UPPER LEVEL SHORTWAVE A COUPLE
OF DEGREES W OF THE FRONT.  BROKEN LOW CLOUDS/ISOLATED SHOWERS
ARE ALSO S OF 22N BETWEEN E CUBA AND 62W... AN EFFECT OF THE
INCREASINGLY UNSTABLE COOL AIRMASS BEING MODIFIED OVER WARMER
TROPICAL WATERS.  THE NEXT FRONT IS FORECAST TO MOVE INTO THE
AREA LATE SAT WHICH COULD BRING THE COLDEST AIR TO S FLORIDA
SINCE LATE DEC.

CARIBBEAN SEA...
MID-LATITUDE HAS MODIFIED AND OVERSPREAD MUCH OF THE CARIBBEAN W
OF THE DISSIPATING COLD FRONT FROM NEAR GUADELOUPE TO JUST N OF
THE ABC ISLANDS.  NEARLY OVERCAST LOW CLOUDS WITH WIDELY
SCATTERED SHOWERS ARE BETWEEN THE FRONT AND 70W S OF PUERTO
RICO.  THE ISLAND SHOULD EXPERIENCE WETTER-THAN-AVERAGE WEATHER
FOR THE NEXT FEW DAYS UNTIL SLIGHTLY DRIER AIR MIGRATES FROM THE
N.  NORTH TO NE WINDS COVER THE WESTERN PART OF THE CARIBBEAN
WITH OROGRAPHIC CLOUDINESS ALONG THE HIGH TERRAIN OF COSTA RICA
PANAMA AND W HONDURAS.  THE TERRAIN-INDUCED CLOUDINESS SHOULD
DIMINISH OVER THE NEXT COUPLE OF DAYS AS WINDS SHIFT TO THE NE
AND SLACKEN.  OTHERWISE PARTLY CLOUDY SKIES AND ISOLATED SHOWERS
ARE IN THE W CARIBBEAN AND SE OF THE FRONT IN THE E CARIBBEAN
WITH LIGHT WINDS ESPECIALLY S OF 13N E OF 66W.  IN THE UPPER
LEVELS... THE NORTHERN CARIBBEAN IS BEING NICKED BY THE
MID-LATITUDE TROUGH IN THE W ATLC WITH GENERALLY ZONAL FLOW
OTHERWISE.

E ATLANTIC AND TROPICAL ATLANTIC...
DISSIPATING 1011 MB LOW IS NEAR 30N38W WITH LITTLE INFLUENCE ON
THE WEATHER AS ONLY PARTLY CLOUDY SKIES ARE NEAR THE CENTER.
THE SYSTEM HAS LOST ITS UPPER SUPPORT AS TROUGHING HAS SLID TO
THE E ALONG 23N27W TO 31N33W.  LIFT/DIVERGENCE AHEAD OF THIS
TROUGH IS ENHANCING WIDELY SCATTERED MODERATE CONVECTION N OF
26N BETWEEN 25W-29W.  FARTHER S IN THE TROPICS.... EXPANDING
UPPER RIDGING IS ALONG 5W FROM 38W TO NE S AMERICA.  THE ITCZ IS
VERY ACTIVE E OF 38W WITH UPPER DIFFLUENCE NOTED.  MID/UPPER DRY
AIR LIES BETWEEN 11N-25N FROM 30W-60W WITH GENERALLY FAIR SKIES
EXCEPT NEAR THE FRONTAL SYSTEMS.  WEAK SURFACE TROUGH IS ALONG
57W/58W BETWEEN 8N-16N WITH ISOLATED SHOWERS WITHIN 60 NM OF THE
AXIS.  THE REMNANTS OF A FRONTAL SYSTEM IN THE E ATLC ARE STILL
PRODUCING ISOLATED SHOWERS IN THE CAPE VERDES BETWEEN 22W-28W.

$$
BLAKE


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