[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 061131
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1045 UTC.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 8N10W 6N30W 5N40W 8N50W 6N80W
5N80W.  SCATTERED MODERATE CONVECTION FROM 3N-9N BETWEEN 20W-27W
AND FROM 1N-6N BETWEEN 30W-37W. WIDELY SCATTERED MODERATE
CONVECTION FROM 8N-13N BETWEEN 27W-36W.

...DISCUSSION...

GULF OF MEXICO...
BROAD MIDDLE TO UPPER LEVEL RIDGE DOMINATES THE GLFMEX KEEPING
UNSETTLED WEATHER N OF THE AREA AND PRODUCING DRY/TRANQUIL
CONDITIONS. A STRONG 150 KT SUBTROPICAL JET LIES ALONG THE N
PERIPHERY OF THE RIDGE EXTENDING FROM NW MEXICO INTO THE S
UNITED STATES. THE JET IS ACCOMPANIED BY COPIOUS PACIFIC
MOISTURE PRODUCING HIGH CLOUDINESS OVER 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 NOW BUILDING 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 MOVING THROUGH THE SW
UNITED STATES AND FORECAST TO EMERGE OFF THE SE TEXAS COAST
EARLY TUES.  HOWEVER...THE ASSOCIATED MIDDLE TO UPPER LEVEL
TROUGH WILL ONLY SKIRT THE AREA AS IT LIFTS QUICKLY NEWD THROUGH
THE CENTRAL UNITED STATES MON NIGHT AND TUE.  THIS WILL CONFINE
THE BEST DYNAMICS/LIFT OVER THE SE UNITED STATES AND PRODUCE
ONLY SCATTERED SHOWERS AND A FEW ISOLATED THUNDERSTORMS
PRIMARILY N OF 27N.  LACKING UPPER SUPPORT...THE FRONT WILL NOT
MAKE MUCH SWD PROGRESS BECOMING STATIONARY ACROSS THE N GULF BY
MID-WEEK.

CARIBBEAN SEA...
A WEAK 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 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 AND NICARAGUA WHERE LOW LEVEL CONFLUENT FLOW AND
MOISTURE IS MOST PREVALENT. THIS ACTIVITY IS EXPECTED TO SPREAD
QUICKLY WESTWARD OVER CENTRAL AMERICA TODAY  WITH INCREASING
CLOUDINESS AND SHOWERS/THUNDERSTORMS.  ACTIVITY WILL BE MOST
NUMEROUS ALONG WINDWARD FACING SLOPES OF CENTRAL AMERICA AS
BUILDING HIGH PRESSURE OVER THE W ATLC PRODUCES INCREASING
TRADES.  THE UPPER TROUGH IS FORECAST TO SPLIT OVER THE NEXT 24
HOURS WITH A PIECE OF UPPER ENERGY RETROGRADING OVER CENTRAL
AMERICA WHILE THE E PORTION AMPLIFIES SWD.  THIS PATTERN WOULD
FAVOR INCREASING CLOUDINESS AND SHOWERS OVER THE E CARIBBEAN
ESPECIALLY TUE AND WED AS A SHORTWAVE DROPS SWD FROM THE W ATLC.

ATLANTIC OCEAN...
THE W HALF OF THE ATLC FEATURES ZONAL FLOW WITH A SHORTWAVE
TROUGH RACING THROUGH THE AREA BETWEEN 60W-65W.  THE SHORTWAVE
FEATURE IS MOISTURE STARVED AND IS ONLY PRODUCING WIDELY
SCATTERED SHOWERS WITHIN 60 NM EITHER SIDE OF A WEAKENING
STATIONARY FRONT ALONG 32N50W 26N65W 28N72W.  SE OF THE
FRONT...THE REMNANT LOW FROM OTTO CONTINUE TO DRIFT WEST NEAR
26N53W ACCOMPANIED BY AN AREA OF SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS N OF 20N BETWEEN 50W-60W. OVER THE E ATLC...AN
UPPER LEVEL LOW CUTOFF FROM THE WLY FLOW IS DRIFTING SW NEAR
20N36W.  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 29N41W 17N35W. CONVERGENT LOWER
LEVEL FLOW ASSOCIATED WITH STRONG TRADES E OF THE TROUGH IS
SUPPORTING AN AREA OF CLOUDINESS AND WIDESPREAD
SHOWERS/THUNDERSTORMS FROM THE ITCZ NWD TO 25N BETWEEN THE CAPE
VERDE ISLANDS AND 35W.  ELSEWHERE...A 50-70 KT SUBTROPICAL JET
EXTENDS FROM 13N40W NEWD INTO AFRICA OVER MAURITANIA.  DIVERGENT
UPPER LEVEL FLOW ASSOCIATED WITH THE JET IS PRODUCING ENHANCED
ITCZ CONVECTION FROM 20W-40W.

$$
RHOME



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