[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 211759
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST WED NOV 21 2007

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN
SECTIONS OF SOUTH AMERICA...AND THE ATLANTIC OCEAN TO THE
AFRICAN COAST FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION
IS BASED ON SATELLITE IMAGERY...METEOROLOGICAL ANALYSIS...
WEATHER OBSERVATIONS...AND RADAR.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...TROPICAL WAVES...
TROPICAL WAVE IS ALONG 83W/84W S OF 19N MOVING W 10 KT. SOME
SUBTLE CYCLONIC TURNING IS NOTED IN THE LOW CLOUD FIELD JUST N
OF THE NE COAST OF HONDURAS. SCATTERED SHOWERS AND ISOLATED
TSTMS ARE GENERALLY WITHIN 60 NM EITHER SIDE OF THE AXIS.

TROPICAL WAVE WAS ALONG 97W S OF 19N MOVING W 10 KT. THIS WAVE
WAS DROPPED FROM THE INTERMEDIATE 21/1500 UTC MAP DUE TO THE
LACK OF SUPPORT IN SATELLITE AND SFC OBSERVATIONS. THE MIMIC TPW
PRODUCT SHOWS A LOW AMPLITUDE MOISTURE SURGE...POSSIBLY
ASSOCIATED WITH THE WAVE...ROUNDING THE RIDGING OVER THE GULF
AND NOW MOVING N/NW ALONG THE COAST OF NE MEXICO.
REGARDLESS...THE FEATURE IS INSIGNIFICANT AND DOES NOT APPEAR TO
BE GENERATING SIGNIFICANT WEATHER.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 5N9W 5N35W 4N52W. ISOLATED CLUSTERS
OF MODERATE CONVECTION ARE WITHIN 150 NM N AND 90 NM S OF THE
AXIS BETWEEN 25W-45W.

DISCUSSION...

GULF OF MEXICO...
A SFC RIDGE EXTENDS W/SW ACROSS THE GULF FROM A 1024 MB HIGH
CENTERED JUST OFFSHORE NORTH FLORIDA IN THE WRN ATLC. THIS IS
PRODUCING MOSTLY MODERATE SE/S RETURN FLOW ACROSS THE
BASIN...WHICH IS EXPECTED TO PERSIST UNTIL TONIGHT. A
COLD FRONT WILL ALLOW NLY WINDS TO INCREASE ESPECIALLY OVER THE
NW PORTION ON THANKSGIVING. A SMALL AREA OF SCATTERED SHOWERS
WITH POSSIBLE EMBEDDED ISOLATED TSTMS IS OVER THE MIDDLE GULF N
OF 24N BETWEEN 85W-90W. THERE ALSO APPEARS TO BE SOME LOW LEVEL
CYCLONIC TURNING IN THIS REGION...ESPECIALLY FROM 24N-27N
BETWEEN 86W-89W. ALOFT...AN UPPER RIDGE DOMINATES...EXTENDING NW
FROM THE NW CARIBBEAN TO THE NORTH CENTRAL GULF COAST.

CARIBBEAN SEA...
HIGH PRES JUST E OF NRN FLORIDA IS PRODUCING MODERATE TO FRESH
ELY TRADES OVER MUCH OF THE CARIBBEAN TODAY. THE ONLY DEEP
CONVECTION CURRENTLY OVER THE BASIN IS OVER THE WRN PORTION
ALONG THE COAST OF CENTRAL AMERICA...PARTLY ASSOCIATED WITH THE
TROPICAL WAVE ALONG 83W/84W AS DESCRIBED ABOVE. THIS ACTIVITY IS
ALSO BEING SUPPORTED BY UPPER DIFFLUENCE AROUND AN UPPER RIDGE
AXIS OVER THE AREA. A WEAKENING COLD FRONT IS AFFECTING THE
LEEWARD ISLANDS EXTENDING W TO NEAR ERN HISPANIOLA....PRODUCING
BROKEN UP PATCHES OF MOSTLY LOW TOPPED SHOWERS OVER THE AREA.
VERY DRY MID TO UPPER AIR IS FILTERING INTO THE FAR NRN
CARIBBEAN BEHIND THE ASSOCIATED UPPER TROUGH MOSTLY N OF THE
AREA. MODERATE TO FRESH TRADES EXPECTED TO PERSIST OVER THE NEXT
FEW DAYS.

ATLANTIC OCEAN...
A 1024 MB HIGH NEAR 29N76W...OR JUST OFFSHORE NRN FLORIDA...IS
DOMINATING THE WRN ATLC. THIS IS PRODUCING FAIR WEATHER AND
LIGHT WINDS JUST OFFSHORE NORTH AND CENTRAL FLORIDA AND N OF THE
BAHAMAS. THE HIGH IS BUILDING SE BEHIND A COLD FRONT THAT ENTERS
THE AREA NEAR 32N47W AND CONTINUES SW ALONG 23N52W TO THE N
COAST OF DOMINICAN REPUBLIC. FRESH TO STRONG MOSTLY WLY WINDS
ASSOCIATED WITH THE FRONT ARE GENERALLY N OF 26N BETWEEN
42W-66W. MODERATE N/NE WINDS ARE ELSEWHERE BEHIND THE FRONT TO
THE COAST OF S FLORIDA. SCATTERED SHOWERS ARE GENERALLY WITHIN
120 NM AHEAD OF THE FRONT...THOUGH THE DEEPEST CONVECTION WITH
ISOLATED TSTMS IS N OF 25N BETWEEN 39W-50W. THE FRONT IS
ASSOCIATED WITH A WELL DEFINED DEEP LAYER LOW N OF THE AREA NEAR
36N54W. ANOTHER COLD FRONT IS JUST N OF THE NE PORTION OF THE
AREA...BUT IS GENERATING ISOLATED SHOWERS WITH POSSIBLE EMBEDDED
TSTMS OVER THE AREA N OF 27N BETWEEN 14W-21W...SOME OF WHICH ARE
AFFECTING THE CANARY ISLANDS. THE REMAINDER OF THE E ATLC SFC
PATTERN IS DOMINATED BY A 1021 MB HIGH NEAR 23N32W. A SFC TROUGH
IS EMBEDDED IN THE SW PORTION OF THE ASSOCIATED RIDGE ALONG 44N
FROM 7N-16N. THIS TROUGH HAS SHOWED UP WELL IN RECENT
SCATTEROMETER PASSES...AND IS GENERATING ISOLATED SHOWER
ACTIVITY WITHIN 120 NM OF THE AXIS. A WLY JET IS SPREADING
TROPICAL MOISTURE EWD OVER THE AREA FROM 10N-20N E OF
37W...INCLUDING OVER THE CAPE VERDE ISLANDS.

$$
WILLIS


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