[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 162326
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST TUE 16 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...ITCZ...

ITCZ AXIS IS ALONG 10N10W 5N50W 7N65W 10N80W.  SCATTERED
MODERATE TO ISOLATED STRONG CONVECTION IS OFF THE COAST OF W
AFRICA FROM 3N-8N BETWEEN 13W-25W.  WIDELY SCATTERED MODERATE
CONVECTION IS FROM 1N-7N BETWEEN 28W-40W.  SCATTERED MODERATE TO
ISOLATED STRONG CONVECTION IS ALONG THE COAST OF VENEZUELA AND N
COLOMBIA FROM 8N-13N BETWEEN 65W-74W.

...DISCUSSION...

GULF OF MEXICO...
LARGE UPPER LEVEL CLOSED LOW OVER NW MEXICO IS THE MAIN WEATHER
MAKER FOR THE GLFMEX AS DIFFLUENT UPPER LEVEL FLOW TO THE EAST
PRODUCES WIDESPREAD CLOUDINESS AND SCATTERED SHOWERS/
THUNDERSTORM N OF 22N W OF 90W. SIMILAR ACTIVITY IS ALSO NOTED
OVER INTERIOR MEXICO ALONG THE E SLOPES OF THE SIERRA MADRE
ORIENTALS BETWEEN 100W-105W.  THIS ACTIVITY EXTENDS NWD AND
BECOMES INCREASINGLY NUMEROUS OVER W PORTIONS OF TEXAS.  THE
UPPER LOW IS FLANKED ON THE WESTERN SIDE BY A 70-90 KT NLY JET
INDICATING THE TROUGH WILL UNDERGO AMPLIFICATION AND BECOME
NEGATIVELY TILTED DURING THE NEXT 24 HOURS.  AS THIS EVOLUTION
OCCURS...MIDDLE TO UPPER LEVEL DYNAMICS/LIFT WILL INCREASE AND
SLIDE EWD INTO CENTRAL TEXAS AND THE NW GLFMEX. THIS PATTERN
WILL SUPPORT INCREASING SHOWERS/THUNDERSTORMS EXTENDING FROM
TEXAS SWD INTO THE NW GLFMEX...MAINLY N OF 25N.  SHIFTING
EWD...STRONG MIDDLE TO UPPER LEVEL RIDGE BISECTS THE CENTRAL
GULF ALONG 90W EXTENDING NWD WELL INTO THE CENTRAL UNITED
STATES.  UPSTREAM DYNAMICS AND MOISTURE IS RIDING UP AND OVER
THE RIDGE LEAVING SUBSIDENCE AND DRY AIR OVER THE E GLFMEX AND
FLORIDA.  LOWER LEVEL MOISTURE IS ALSO ABSENT OVER THIS REGION
AND THE PRESENCE OF STRATOCUMULUS CLOUDS IN SATELLITE IMAGERY
INDICATES COLD ADVECTION AND STABLE CONDITIONS.  ON THE
SURFACE... EASTERLY FLOW COVERS THE ENTIRE GULF OF MEXICO WITH
15-20 KT WINDS N OF 23N.  SCATTERED MODERATE TO STRONG
CONVECTION IS OFF THE COAST OF TEXAS FROM 25N-28N BETWEEN
93W-95W...AND FROM 28N-32N BETWEEN 95W-97W.

CARIBBEAN SEA...
A LARGE MIDDLE TO UPPER LEVEL TROUGH OVER THE W ATLC PENETRATES
WELL INTO THE CENTRAL CARIBBEAN FROM THE MONA PASSAGE TO CENTRAL
AMERICA NEAR THE COSTA RICA/PANAMA BORDER.  ASSOCIATED CONFLUENT
FLOW ON THE BACKSIDE OF THE TROUGH...W OF THE TROUGH AXIS...IS
PRODUCING STRONG MIDDLE TO UPPER LEVEL SUBSIDENCE AND VERY DRY
AIR.  THIS PATTERN IS EFFECTIVELY CAPPING SIGNIFICANT
CLOUDS/CONVECTION.  ATTENDANT COLD FRONT ENTERS THE AREA THROUGH
THE WINDWARD PASSAGE BECOMING STATIONARY AS IT MAKES ITS WAY
ACROSS THE NW CARIBBEAN TO HONDURAS.  STRONG HIGH PRESSURE
BEHIND THE FRONT CONTINUES TO PRODUCE BRISK NE FLOW AND COLD
ADVECTION.  OVER THE E CARIBBEAN...MIDDLE TO UPPER LEVEL
DIFFLUENT FLOW IS TRIGGERING SCATTERED SHOWERS/THUNDERSTORMS
PRIMARY ALONG A LOW LEVEL TROUGH EXTENDING ACROSS THE WINDWARD
ISLANDS NEAR ST. LUCIA TO JUST OFF THE COAST OF N COLOMBIA NEAR
12N72W.  THE UPPER TROUGH OVER THE CENTRAL ATLC AND CARIBBEAN
WILL CONTINUE TO BE REINFORCED DURING THE NEXT FEW DAYS BY
SHORTWAVES DROPPING SWD FROM THE E UNITED STATES.  THIS SHOULD
MAINTAIN A BAND OF MIDDLE TO UPPER LEVEL LIFT AND ASSOCIATED
SHOWERS/THUNDERSTORMS FROM THE SW CARIBBEAN TO THE WINDWARD
ISLANDS.  THIS ACTIVITY MAY BECOME MORE NUMEROUS/STRONG TOWARD
THE END OF THE WEEK AS A STRONG SUBTROPICAL JET FORMS OVER THE
CENTRAL ATLC.

ATLANTIC OCEAN...
THE PERSISTENT HIGH AMPLITUDE TROUGH PATTERN REMAINS OVER THE W
ATLC WITH AXIS CURRENTLY EXTENDING FROM 32N65W SWD INTO THE
CARIBBEAN NEAR THE MONA PASSAGE. THE ATTENDANT COLD FRONT ENTERS
THE AREA NEAR 32N48W SW ALONG 26N53W TO THE N COAST OF PUERTO
RICO WHERE IT BECOMES STATIONARY ACROSS HISPANIOLA AND JAMAICA
TO HONDURAS NEAR 16N84W. STRONG SUBSIDENCE AND DRY NW FLOW
BEHIND THE UPPER TROUGH CONTINUES TO AFFECT THE AREA  W OF THE
FRONT ALL THE WAY TO THE E UNITED STATES COAST WITH ASSOCIATED
STABLE CONDITIONS LIMITING CLOUDS TO COLD AIR STRATOCUMULUS.  A
1031 MB SURFACE HIGH OVER THE SE UNITED STATES IS BUILDING IN
BEHIND THE COLD FRONT PRODUCING STRONG NE FLOW OVER THE W
ATLANTIC.  MIDDLE TO UPPER LEVEL DYNAMICS WITH THE UPPER TROUGH
IS WELL AHEAD OF THE COLD FRONT PRODUCING AN AREA OF CONVECTION
OVER THE CENTRAL ATLC NE OF A 1001 SURFACE LOW NEAR 26N48W.
WIDELY SCATTERED MODERATE CONVECTION IS ALSO NOTED WITHIN 300 NM
AHEAD OF A TRAILING TROUGH EXTENDING SW TO THE WINDWARD ISLANDS
NEAR 14N.  OVER THE CENTRAL AND E ATLC...MIDDLE TO UPPER LEVEL
RIDGE EXTENDS NWD FROM A WELL-DEFINED ANTICYCLONE OVER THE
TROPICAL ATLC NEAR 10N48W TO BEYOND 32N40W.  A TROUGH EXTENDS
SWD FROM 32N20W TO A BASE NEAR 10N30W OFF THE COAST OF W AFRICA.
OVER THE TROPICAL ATLC...ITCZ CONVECTION IS MOST PRONOUNCED
BETWEEN 10W-30W 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.

$$
FORMOSA


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