[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 171747
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST WED 17 NOV 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...ITCZ...

ITCZ AXIS IS ALONG 10N10W 5N30W 6N40W 4N60W 8N80W. WIDELY
SCATTERED MODERATE CONVECTION FROM 2N-10N BETWEEN 15W-30W.
SCATTERED MODERATE CONVECTION FROM 2N-10N BETWEEN 30W-40W.

...DISCUSSION...

GULF OF MEXICO...
LARGE UPPER LEVEL CLOSED LOW OVER W TEXAS IS THE MAIN WEATHER
MAKER FOR THE GLFMEX AS DIFFLUENT UPPER LEVEL FLOW TO THE EAST
PRODUCES WIDESPREAD CLOUDINESS AND SCATTERED SHOWERS/
THUNDERSTORM OVER E TEXAS EXTENDING SEWD INTO THE NW GLFMEX
ALONG A WARM FRONT FROM GALVESTON TO 26N92W.  SUBSIDENCE AND DRY
AIR WRAPPING AROUND THE BACKSIDE OF THE UPPER LOW HAS CLEARED
OUT CONVECTION WHICH OCCURRED OVER INTERIOR MEXICO YESTERDAY.
THE UPPER LOW IS NOW LIFTING NWD AND WILL TAKE MOST OF THE
DYNAMICS/LIFT N OF THE AREA TONIGHT.  SHOWERS/THUNDERSTORMS OVER
THE NW GLFMEX SHOULD BE ON THE DECREASE AS THIS OCCURS.
ELSEWHERE...STRONG MIDDLE TO UPPER LEVEL RIDGE BISECTS THE
CENTRAL GULF ALONG 90W EXTENDING NWD WELL INTO THE CENTRAL AND E
UNITED STATES.  SUBSIDENCE ASSOCIATED WITH THIS PATTERN COVERS
THE AREA...ESPECIALLY S OF 25N...CREATING DRY CONDITIONS IN THE
MIDDLE TO UPPER LEVELS.   LOWER LEVEL MOISTURE IS ALSO ABSENT
OVER THIS REGION WITH THE ONLY WEATHER OF NOTE BEING A NARROW
BAND OF SCATTERED SHOWERS/ISOLATED THUNDERSTORMS OCCURRING ALONG
A CONVERGENCE BOUNDARY EXTENDING FROM THE FLORIDA STRAITS NW TO
THE CENTRAL GLFMEX NEAR 25N91W.  AT THE SURFACE...1030 MB HIGH
OVER THE E UNITED STATES RIDGES SWD OVER FLORIDA AND THE E
GLFMEX WITH MODERATE NE FLOW ADVECTING COOL/DRIER AIR OVER MUCH
OF FLORIDA INTO THE E GULF.

CARIBBEAN SEA...
A LARGE MIDDLE TO UPPER LEVEL TROUGH OVER THE W ATLC WATERS
PENETRATES INTO THE CENTRAL CARIBBEAN FROM HISPANIOLA TO CENTRAL
AMERICA NEAR HONDURAS/NICARAGUA.  A STRONG SUBTROPICAL JET
ACCOMPANIES THE UPPER TROUGH EXTENDING FROM THE E CARIBBEAN NEWD
INTO THE CENTRAL ATLC. UPPER LEVEL LIFT/DYNAMICS ASSOCIATED WITH
THE ENTRANCE REGION OF THE JET CONTINUES TO PRODUCE SCATTERED
SHOWERS AND WIDELY SCATTERED MODERATE CONVECTION ALONG A LOW
LEVEL TROUGH EXTENDING FROM THE WINDWARD ISLANDS NEAR MARTINIQUE
TO JUST N OF COLOMBIA NEAR 12N75W.  THE STRONGEST/MOST NUMEROUS
OF THIS ACTIVITY CURRENTLY LIES OVER THE ABC ISLANDS WHERE AN
EARLIER TRMM PASS INDICATED RAIN RATES OVER 1 INCH/HOUR.  WATER
VAPOR IMAGERY SHOWS A SHORTWAVE DISTURBANCE DROPPING SWD OVER
THE BAHAMAS WHICH WILL REINFORCE THE TROUGH AND CARVE IT A BIT
FURTHER SOUTH TODAY AND TOMORROW.  THIS EVOLUTION WILL LIKELY
MAINTAIN A BAND OF MIDDLE TO UPPER LEVEL LIFT AND ASSOCIATED
SHOWERS/THUNDERSTORMS FROM THE SW CARIBBEAN TO THE WINDWARD
ISLANDS.  ELSEWHERE OVER THE CARIBBEAN...MODERATE SUBSIDENCE AND
DRY/STABLE AIR IS PRODUCING GENERALLY FAIR WEATHER.

ATLANTIC OCEAN...
THE PERSISTENT HIGH AMPLITUDE TROUGH PATTERN REMAINS OVER THE W
ATLC WITH ATTENDANT COLD FRONT ENTERING THE AREA NEAR 32N43W SW
ALONG 20N60W INTO THE E CARIBBEAN S OF PUERTO RICO WHERE IT
BECOMES STATIONARY. STRONG SUBSIDENCE AND DRY/STABLE AIR
DOMINATES THE AREA W OF 45W WITH COLD ADVECTION W OF THE FRONT
PRODUCING A FIELD OF STRATOCUMULUS CLOUDS.  A 1030 MB SURFACE
HIGH OVER THE SE UNITED STATES IS PRODUCING MODERATE NE FLOW
OVER THE W ATLANTIC.  THE STRONGEST DYNAMICS ASSOCIATED WITH THE
UPPER TROUGH IS LOCATED N OF THE AREA LIMITING ACTIVITY ALONG
THE COLD FRONT TO WIDELY SCATTERED SHOWERS. FURTHER E...MIDDLE
TO UPPER LEVEL RIDGE EXTENDS NWD FROM A WELL-DEFINED ANTICYCLONE
OVER THE TROPICAL ATLC NEAR 13N42W TO BEYOND 33N35W.  OVER THE
FAR E ATLC...A MIDDLE TO UPPER LEVEL TROUGH EXTENDS SWD FROM THE
AZORES OVER THE CAPE VERDE ISLANDS TO 6N25W. OVER THE TROPICAL
ATLC...ITCZ CONVECTION IS MOST PRONOUNCED BETWEEN 10W-40W IN
ASSOCIATION WITH A SUBTROPICAL JET SE OF THE CAPE VERDE
ISLANDS.  THIS JET IS EXPECTED TO REMAIN OVER THE AREA DURING
THE NEXT DAY OR SO KEEPING THE E PORTION OF THE ITCZ ACTIVE.

$$
RHOME





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