[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 111801
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST THU 11 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.

...SPECIAL FEATURES...
A BROAD AREA OF LOW PRESSURE ASSOCIATED WITH A SURFACE TROUGH IN
THE CARIBBEAN SEA FROM THE ABC ISLANDS TO ABOUT ANTIGUA IS BEING
MONITORED FOR SIGNS OF ORGANIZATION.  VERTICAL WIND SHEAR IS
RELATIVELY UNFAVORABLE WITH DEVELOPMENT APPEARING LESS LIKELY
THAN YESTERDAY.  REGARDLESS OF DEVELOPMENT...LOCALLY HEAVY
RAINFALL AND FLOODING WITH POSSIBLE MUDSLIDES ARE LIKELY OVER
THE VIRGIN AND LEEWARD ISLANDS DURING TODAY AND TONIGHT AS THE
AREA OF DISTURBED WEATHER GRADUALLY LIFTS NE.

NON-TROPICAL 1003 MB LOW IS SEVERAL HUNDRED MILES SSW OF THE
AZORES.  HOWEVER CONVECTION HAS BEEN INCREASING NEAR THE LOW AND
WATER TEMPERATURES REMAIN CONSIDERABLY ABOVE AVERAGE IN THAT
AREA.  ANY SIGNS OF BAROCLINICITY ARE FADING WITH NO FRONTS
ATTACHED TO THE LOW AND THE AREA IS BECOMING MORE SEPARATE FROM
A LARGER AREA OF LOW/MID CLOUDS.  THERE IS THE POTENTIAL FOR
SUBTROPICAL/TROPICAL DEVELOPMENT IN THE NEXT 36 HOURS.

...TROPICAL WAVES...
WEAK TROPICAL WAVE OVER THE CENTRAL CARIBBEAN PREVIOUSLY ALONG
77W IS NO LONGER A SIGNIFICANT WEATHER FEATURE IN THE ATLC.

...ITCZ...
ITCZ AXIS IS ALONG 10N13W 4N33W 4N53W.  ITCZ IS NOT WELL-DEFINED
W OF 40W.  WIDELY SCATTERED MODERATE IS FROM 4N-9N BETWEEN
19W-32W.

...DISCUSSION...
GULF OF MEXICO...
ZONAL FLOW ALOFT EXTENDS OVER THE REGION WITH SOME UPPER ENERGY
ASSISTING WIDELY SCATTERED TSTMS THRU THE GULF INTO THE FLORIDA
PANHANDLE WITHIN 75 NM OF LINE 25N87.5W 31N85W.  MOST OF THE
REGION HAS RATHER DRY CONDITIONS IN THE MID/UPPER LEVELS WITH
LITTLE SIGNIFICANT RAIN.  GENERAL ELY FLOW IS THRU THE E GULF
COURTESY OF A REINFORCING BACKDOOR SURGE OF COOLER AIR A COUPLE
OF DAYS AGO.  A NEW COLD FRONT HAS EMERGED BARELY INTO THE NW
GULF WITH ANY SHOWERS WELL AHEAD OF THE BOUNDARY.  THIS FRONT
SHOULD SLIDE THRU THE AREA AND BE INTO THE FLORIDA PANHANDLE BY
THIS TIME TOMORROW.  UPPER CONDITIONS LOOK FAVORABLE FOR ONLY
WIDELY SCATTERED SHOWERS ALONG THE FRONT.

CARIBBEAN SEA...
RATHER DEEP MID/UPPER TROUGH CONTINUES SAGGING SE THRU THE
CARIBBEAN.. DRYING THINGS OUT SLOWLY FROM W TO E.  TROF AXIS IS
FROM THE WINDWARD PASSAGE TO OFFSHORE OF SRN NICARAGUA.
ELONGATED AREA OF LOW PRESSURE/SURFACE TROUGH REMAINS OVER THE E
CARIBBEAN WITH WLY WINDS OBSERVED IN SUCH LOW LATITUDE ISLANDS
AS THE ABC CHAIN.  DEEP-LAYERED LIFT ALONG WITH PLENTY OF
MOISTURE/CONVERGENCE IS LEADING TO WIDELY SCATTERED MODERATE
CONVECTION S OF 15N BETWEEN 61W-65W.  OTHER SHOWERS ARE OVER THE
LESSER ANTILLES WITH SCATTERED ACTIVITY NEAR AND WITHIN 90 NM N
OF PUERTO RICO.  MORE DETAILS ARE IN THE SPECIAL FEATURES
SECTION ABOVE.   THE HEAVY RAIN THREAT SEEMS TO BE SHIFTING INTO
THE E CARIBBEAN WITH MORE RAIN POSSIBLE AS A COLD FRONT JUST N
OF THE AREA MAKES ITS WAY INTO THE REGION... SETTING UP
CONVERGENCE BOUNDARIES FOR LOCALLY HEAVY RAIN ESPECIALLY IN
MOUNTAINOUS TERRAIN THAT FAVORS A NE FETCH.

ATLANTIC...
THE AREA W OF 60W IS COVERED BY BROKEN LOW/MID CLOUDS...
BECOMING MORE SCATTERED NEAR THE BAHAMAS AND FLORIDA.  THESE
CLOUDS ARE DUE TO COLD AIR BEHIND A FRONT WHICH HAS PENETRATED
THE TROPICS FROM 31N51W TO JUST N OF PUERTO RICO NEAR 19.5N66W
ALONG THE N COAST OF HISPANIOLA DISSIPATING OVER THE WINDWARD
PASSAGE.  WIDELY SCATTERED SHOWERS ARE BEHIND THE FRONT WITHIN
120 NM AS WELL AS PLENTY OF CLOUD COVER.  THIS DEEP NON-TROPICAL
CYCLONE-RELATED TSTM ACTIVITY IS DUE TO A SHARP MID/UPPER LEVEL
TROUGH FROM E OF BERMUDA SW TO NW HAITI.  STRONG JET IS ON THE E
SIDE OF THE TROUGH AND...COUPLED WITH THE DEEP MOISTURE/LIFT IN
THE AREA...IS CAUSING SCATTERED SHOWERS FROM 20N-29N BETWEEN
51W-60W.  ILL-DEFINED SURFACE TROUGH EXTENDS FROM THE NE LEEWARD
ISLANDS NE TO 23N53W...ALSO ASSISTING SHOWER DEVELOPMENT.
AMPLIFIED PATTERN CONTINUES OVER THE CENTRAL ATLC WITH MID/UPPER
RIDGING FROM NE VENEZUELA THRU THE ATLC TO 32N44W.  TYPICAL
MOIST CONDITIONS ARE ON THE NW SIDE OF THE RIDGE WHILE
SIGNIFICANT DRYING IS ON THE SE SIDE.  NON-TROPICAL LOW IS NEAR
30N33W THOUGH IT HAS THE POTENTIAL FOR FURTHER DEVELOPMENT...SEE
THE SPECIAL FEATURES SECTION.  LOW DRAGS A TROUGH WELL S INTO
THE TROPICAL ATLC ALONG 20N37W TO 5N45W.  VERY DRY AIR ALOFT IS
PRESENT NEAR AND W OF THE TROUGH AXIS.. KILLING OFF ANY
SIGNIFICANT ITCZ CONVECTION W OF 40W.  HOWEVER THIS DEEP TROUGH
ENHANCES SHOWER ACTIVITY IN THE E ATLC ITCZ WITH WIDESPREAD
CLOUDINESS FROM 5N-20N E OF 30W.  TROUGH IS ACTUALLY FIRING A
COUPLE TSTMS NEAR 17N28W NW OF THE CAPE VERDES.

$$
BLAKE


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