[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 060518
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 AM EST MON 06 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 AXIS IS CENTERED ALONG 10N10W 7N20W 6N30W 6N40W 4N45W
10N70W 5N80W.  SCATTERED MODERATE/ISOLATED STRONG FROM 3N-8N
BETWEEN 18W-30W. SCATTERED MODERATE CONVECTION FROM 1N-5N
BETWEEN 30W-40W. WIDELY SCATTERED MODERATE CONVECTION FROM
7N-12N BETWEEN 26W-33W.  SIMILAR ACTIVITY FROM 5N-8N BETWEEN
40W-47W.

...DISCUSSION...

GULF OF MEXICO...
BROAD MIDDLE TO UPPER LEVEL RIDGE DOMINATES THE GLFMEX PRODUCING
DRY/TRANQUIL WEATHER.  A STRONG 130 KT SUBTROPICAL JET LIES
ALONG THE N PERIPHERY OF THE RIDGE OVER NW MEXICO AND THE S
UNITED STATES PUMPING SIGNIFICANT PACIFIC MOISTURE EWD. OVERCAST
HIGH CLOUDINESS ACCOMPANIES THIS MOISTURE SURGE AFFECTING THE N
HALF OF THE GLFMEX.  AT THE SURFACE...THE WARM FRONT WHICH
AFFECTED THE GLFMEX OVER THE WEEKEND HAS LIFTED N OF THE AREA
AND HIGH PRESSURE IS BEGINNING TO BUILD IN ITS WAKE FROM THE W
ATLC ACROSS CENTRAL FLORIDA.  MODERATE RETURN FLOW HAS DEVELOPED
ACROSS THE GULF AHEAD OF THE NEXT COLD FRONT WHICH IS FORECAST
TO EMERGE OFF THE SE TEXAS COAST LATE MONDAY INTO TUES.
HOWEVER...THIS FRONT WILL NOT MAKE MUCH SWD PROGRESS BECOMING
STATIONARY OVER THE N GULF BY MID-WEEK.  MOST OF THE
DYNAMICS/LIFT WITH THE FRONT WILL SKIRT JUST N OF THE AREA BUT
LOW LEVEL MOISTURE POOLING WILL ALLOW WIDELY SCATTERED SHOWERS
AND A FEW ISOLATED THUNDERSTORMS PRIMARILY N OF 27N.

CARIBBEAN SEA...
A WEAK MIDDLE TO UPPER LEVEL TROUGH BISECTS THE CARIBBEAN FROM
THE MONA PASSAGE SW TO COSTA RICA. MUCH OF THE AREA IS COVERED
BY EXTREMELY DRY/STABLE MIDDLE TO UPPER LEVEL AIR ESPECIALLY
WEST OF THE TROUGH WHERE STRONG SUBSIDENCE PREVAILS.
HOWEVER...THERE IS JUST ENOUGH LOW LEVEL MOISTURE AND
INSTABILITY ASSOCIATED WITH UPPER TROUGH TO PRODUCE SCATTERED
SHALLOW TOPPED SHOWERS OVER THE CENTRAL CARIBBEAN WITH A SMALL
AREA OF DEEP CONVECTION OVER THE SW CARIBBEAN WHERE LOW LEVEL
CONFLUENT FLOW AND MOISTURE IS MOST PREVALENT. THIS AREA OF
MOISTURE IS EXPECTED TO SPREAD OVER CENTRAL AMERICA TODAY AND
TUES WITH INCREASING SHOWERS/THUNDERSTORMS.  AT THE
SURFACE...MODERATE TO STRONG EASTERLY TRADES DOMINATE THE ENTIRE
CARIBBEAN BASIN IN ASSOCIATION WITH A TIGHTENING PRESSURE
GRADIENT AS HIGH PRESSURE BUILDS OVER THE W ATLC.  THE UPPER
TROUGH IS FORECAST TO SPLIT OVER THE NEXT 24 HOURS THEN GET
REINFORCED OVER THE E CARIBBEAN TUE AND WED.  THIS PATTERN WOULD
FAVOR INCREASING CLOUDINESS AND SHOWERS OVER THE E CARIBBEAN.

ATLANTIC OCEAN...
THE W HALF OF THE ATLC FEATURES ZONAL FLOW WITH A SHORTWAVE
TROUGH RACING THROUGH THE AREA ALONG 65W.  THE SHORTWAVE FEATURE
IS MOISTURE STARVED AND IS ONLY PRODUCING WIDELY SCATTERED
SHOWERS WITHIN 100 NM EITHER SIDE OF A WEAKENING STATIONARY
FRONT FROM 31N51W TO THE CENTRAL BAHAMAS.  SE OF THE FRONT...THE
REMNANTS OF OTTO CONTINUE TO DRIFT SWD NEAR 25N52W ACCOMPANIED
BY A SMALL AREA OF SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS.
OVER THE E ATLC...AN UPPER LEVEL LOW CUTOFF FROM THE WLY FLOW IS
DRIFTING SW NEAR 31N36W.  WATER VAPOR IMAGERY SHOWS AN AREA OF
STRONG SUBSIDENCE AND DRY/STABLE MIDDLE TO UPPER LEVEL AIR ON
THE CONFLUENT SIDE OF THE UPPER LOW EXTENDING TO 55W. A WEAK
SURFACE TROUGH HAS FORMED UNDER THE UPPER LOW ALONG 27N39W
17N35W. CONVERGENT LOWER LEVEL FLOW E OF THE TROUGH IS
SUPPORTING AN AREA OF CLOUDINESS AND WIDESPREAD
SHOWERS/THUNDERSTORMS TO 20W FROM THE ITCZ NWD TO 25N.
ELSEWHERE...A 50-70 KT SUBTROPICAL JET EXTENDS FROM 13N40W NEWD
INTO AFRICA OVER MAURITANIA.  DIVERGENT FLOW ASSOCIATED WITH THE
JET IS PRODUCING ENHANCED ITCZ CONVECTION FROM 15W-40W.
ASSOCIATED MIDDLE TO UPPER MOISTURE AND CLOUDINESS IS RIDING UP
AND OVER A BROAD RIDGE ALONG 25W INTO W AFRICA.  THE OVERALL
PATTERN OVER THE ATLC WILL BE PROGRESSIVE DURING THE NEXT
SEVERAL DAYS WITH AFOREMENTIONED W ATLC SHORTWAVE TROUGH
AMPLIFYING SEWD INTO THE CENTRAL ATLC.

$$
RHOME


WWWW
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