[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 170530
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 AM EST FRI 17 DEC 2004

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 IS CENTERED ALONG 10N5W 7N40W 5N80W. SCATTERED MODERATE
CONVECTION FROM 3N-11N BETWEEN 15W-30W.  WIDELY SCATTERED
MODERATE CONVECTION FROM 1N-5N FROM 25W-35W. SCATTERED MODERATE
CONVECTION FROM 8N-12N BETWEEN 35W-45W.


...DISCUSSION...

GULF OF MEXICO...
A PERSISTENT LONGWAVE TROUGH REMAINS ENTRENCHED OVER THE E
UNITED STATES FROM THE E GREAT LAKES REGION SWD THROUGH N TEXAS
INTO N PORTIONS OF MEXICO. ASSOCIATED 90 KT SUBTROPICAL JET
EXTENDS ACROSS THE AREA FROM CENTRAL MEXICO TO FLORIDA.  WATER
VAPOR IMAGERY INDICATES A SERIES OF WEAK SHORTWAVE DISTURBANCES
MOVING QUICKLY EWD WITHIN THE WLY FLOW WITH THE MOST NOTABLE
LOCATED ALONG THE TEXAS/MEXICO COAST. THIS SYSTEM IS PRODUCING
WIDESPREAD CLOUDINESS AND SCATTERED SHOWERS/THUNDERSTORMS OVER
THE W GLFMEX.  THE STRONGEST/MOST NUMEROUS OF THIS ACTIVITY IS
FOCUSED WITHIN A FEW DEGREES EITHER SIDE OF A STATIONARY FRONT
FROM SW LOUISIANA TO THE COAST OF MEXICO NEAR VERACRUZ.
ASSOCIATED HIGH CLOUDINESS IS SPREADING ACROSS THE E GULF AND
FLORIDA.  ELSEWHERE...A PROGRESSIVE 1029 MB HIGH JUST OFF THE
MID-ATLANTIC COAST HAS CAUSED THE LOW LEVEL WINDS TO VEER AROUND
TO THE EAST ALLOWING A QUICK RETURN TO NEAR NORMAL TEMPERATURES
AFTER THE STRONG SURGE OF CONTINENTAL AIR EARLIER IN THE WEEK.
LEFT OVER COLD AIR STRATOCUMULUS CLOUDINESS AND SHOWERS OVER THE
W ATLC ARE NOW MOVING WESTWARD OVER FLORIDA.  THE WARMING TREND
WILL BE SHORT-LIVED AS THE E UNITED STATES TROUGH AMPLIFIES
THROUGH THE WEEKEND SENDING DOWN REINFORCING SHOTS OF COLD AIR.
THE STRONGEST OF THESE COLD SURGES WILL OCCUR SUNDAY AND
MONDAY.

CARIBBEAN...
A BROAD/FLAT MIDDLE TO UPPER LEVEL RIDGE DOMINATES THE CARIBBEAN
WITH THE RESULTING FLOW BEING PREDOMINANTLY WLY.  UPSTREAM
PACIFIC MOISTURE IS RIDING UP AND OVER THE RIDGE PRODUCING
GENERALLY DRY CONDITIONS ABOVE 500 MB. AT THE LOWER LEVELS...A
DIFFUSE STATIONARY FRONT BISECTS THE CARIBBEAN EXTENDING FROM
THE E COAST OF THE DOMINICAN REPUBLIC TO NICARAGUA. PATCHY LOW
TO MID-LEVEL CLOUDS AND ISOLATED SHOWERS REMAIN BEHIND THE FRONT
BUT THE COVERAGE HAS STEADILY DECREASED OVER THE LAST 24 HOURS
AS THE AIR MASS BECOMES INCREASINGLY MODIFIED OVER THE TROPICAL
WATERS.  E OF THE STATIONARY FRONT...A WEAK ELY DISTURBANCE
MOVING ACROSS E CARIBBEAN IS PRODUCING WIDELY SCATTERED SHOWERS
ALONG A LINE FROM TRINIDAD/TOBAGO TO PUERTO RICO.  NEAR ZONAL
FLOW WILL CONTINUE OVER THE CARIBBEAN THROUGH THE WEEKEND WITH
THE PATTERN BECOMING MORE AMPLIFIED BEGINNING LATE SUNDAY INTO
MONDAY AS A TROUGH DIGS OVER THE E UNITED STATES AND GLFMEX.

ATLANTIC...
THE FLOW OVER THE W ATLC IS BECOMING INCREASINGLY ZONAL AS A
MIDDLE TO UPPER LEVEL TROUGH JUST E OF BERMUDA LIFTS NE.  THE
ATTENDANT COLD FRONT AHEAD LIES OVER THE CENTRAL ATLC FROM
31N54W TO E HISPANIOLA BUT IS QUICKLY LOSING ITS UPPER LEVEL
SUPPORT. WIDELY SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS LIE
WITHIN 180 NM E OF THE FRONT. BEHIND THE FRONT...HIGH PRESSURE
IS MOVING RAPIDLY OFF THE E COAST PRODUCING STRONG NE FLOW AND A
LARGE FIELD OF COLD-AIR STRATOCUMULUS CLOUDS.  OVER THE E
ATLC...A STAGNANT HIGH OVER LOW TYPE PATTERN IS IN PLACE E OF
50W WITH A WELL-DEFINED RIDGE JUST N OF THE AREA ALONG 38N AND A
TROUGH TRAPPED TO THE SOUTH FROM MOROCCO SWD TO 10N50W. THIS
PATTERN IS PRODUCING VERY STABLE CONDITIONS N OF 15N.
HOWEVER...MIDDLE TO UPPER LEVEL DIFFLUENT FLOW SOUTH OF THE
UPPER TROUGH AXIS IS PRODUCING ENHANCED ITCZ ACTIVITY E OF 45W.
AT THE SURFACE...A 1035 MB STATIONARY HIGH IS LOCATED OVER THE
AZORES WITH ASSOCIATED RIDGE EXTENDING SW TO 25N55W.

$$
RHOME





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