[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 202339
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST MON NOV 20 2006

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHEASTERN
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...WEATHER OBSERVATIONS...RADAR...
AND METEOROLOGICAL ANALYSIS.

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 8N13W 5N30W 4N40W 2N51W. SCATTERED
MODERATE CONVECTION IS WITHIN 150-180 NM EITHER SIDE OF THE AXIS
EAST OF 32W. SCATTERED SHOWERS AND ISOLATED TSTMS ARE ELSEWHERE.

...DISCUSSION...
THE GULF OF MEXICO...
A STRONG UPPER LEVEL TROUGH OVER THE EASTERN U.S. CONTINUES TO
DIG SW INTO THE NW GULF AND NE MEXICO. SWLY FLOW AHEAD OF THIS
TROUGH IS ADVECTING A PLUME OF UPPER LEVEL MOISTURE FROM A
TROPICAL SYSTEM IN THE EPAC ACROSS THE BAY OF CAMPECHE AND THE
YUCATAN PENINSULA INTO THE SE GULF AND SOUTH-CENTRAL FLORIDA.
VERY DRY/STABLE AIR ALOFT IS BEHIND THE TROUGH. COLD AIR
STRATOCUMULUS CLOUDS COVERS MUCH OF THE GULF...BUT PARTICULARLY
THE EASTERN HALF. A STRONG 1032 MB SURFACE HIGH PRES LOCATED
OVER NE TEXAS DOMINATES THE ENTIRE GULF. THE BIG STORY IS THE
UNSEASONABLY COLD/DRY AIR AND INCREASING NLY WINDS DUE TO THE
THE TIGHTENED PRES GRAD BETWEEN THIS STRONG HIGH PRESSURE AND A
DEVELOPING STRONG LOW PRESSURE AREA OFF THE GEORGIA/CAROLINAS
COASTS. 20-25 KT NLY WINDS ARE ALREADY BLOWING ACROSS THE
GULF... ADVECTING COLD/DRY AIR INTO THE REGION. THIS COLD AIR
ALOFT ALONG WITH NLY FLOW AT THE SFC WILL CONTINUE TO PRODUCE
UNSEASONABLE COOL WEATHER ACROSS THE CENTRAL-EAST GULF AND THE
FLORIDA PENINSULA OVER THE NEXT FEW DAYS. BREEZY AND CHILLY
CONDITIONS ARE EXPECTED ACROSS THE SE U.S. WITH TEMPERATURES
RUNNING 10-15 DEGREES BELOW SEASONAL NORMALS.


THE CARIBBEAN SEA...
A RIDGE DOMINATES MOST OF THE BASIN ANCHORED BY AN UPPER HIGH
LOCATED OVER NORTHERN COLOMBIA. SWLY WINDS AHEAD OF THE STRONG
UPPER TROUGH THAT LIES ACROSS THE GULF OF MEXICO ARE INVADING
THE NW CORNER OF THE REGION. DRY AIR/MODERATE SUBSIDENCE
DOMINATES THE E CARIBBEAN. A LARGE AREA OF MODERATE/ISOLATED
STRONG CONVECTION EXISTS OVER THE CARIBBEAN SEA FROM 12N21N
BETWEEN 73W-78W. THIS CONVECTIVE ACTIVITY IS ASSOCIATED WITH A
1010 MB SURFACE LOW LOCATED NEAR 16N80W AND A SFC TROUGH THAT
EXTENDS NE FROM THE LOW ACROSS EASTERN CUBA/BAHAMAS INTO THE W
ATLC. ANOTHER TROUGH EXTENDS SOUTH FROM THE SAME LOW TO WESTERN
PANAMA WHERE CLUSTERS OF MODERATE/ISOLATED STRONG CONVECTION ARE
ALSO SEEN. THIS UNSETTLED WEATHER IS AFFECTING EASTERN CUBA AND
PARTS OF HISPANIOLA AND JAMAICA. QUIKSCAT PASS INDICATED A
PRONOUNCED WIND SHIFT WITH NLY 20-25 KT WINDS W OF THE TROUGH
AXIS AND LIGHTER E TO NE WINDS E OF THE AXIS. MODERATE ELY TRADE
WINDS ARE OFF THE VENEZUELAN COAST. A BAND OF DEEP TROPICAL
MOISTURE WILL PERSIST FROM COSTA RICA AND PANAMA TO EASTERN
CUBA/BAHAMAS DURING THE NEXT 24-48 HOURS. LATEST GFS MODEL RUN
SUGGESTS THAT WINDS OVER THE WRN CARIBBEAN WILL SHARPLY INCREASE
25-30 KT LATE TONIGHT THROUGH LATE WED.

THE ATLANTIC OCEAN...
AN AMPLIFIED PATTERN LIES ACROSS THE ATLC OCEAN. A REINFORCING
COLD FRONT...ASSOCIATED WITH THE STRONG UPPER TROUGH OVER THE
EASTERN U.S AND THE GULF OF MEXICO ENTERS THE AREA NEAR 31N78W
THEN CONTINUES SW ACROSS THE WESTERN BAHAMAS/CUBA. NWLY WINDS
ARE INCREASING BEHIND THIS FRONTAL BOUNDARY. THIS WINDS ARE
EXPECTED TO REACH GALE FORCE LATE TONIGHT OR TOMORROW. A LARGE
TITLED RIDGE COVERS THE AREA BETWEEN 55W-75W. A SURFACE TROUGH
EXTENDS FROM EASTERN CUBA TO 31N64W. CLOUDINESS WITH EMBEDDED
SHOWERS AND TSTMS ARE BETWEEN THIS TROUGH AND THE COLD FRONT
MENTIONED ABOVE...COVERING THE WESTERN ATLANTIC MAINLY W OF 70W.
ANOTHER SFC TROUGH LIES ALONG 31N47W 22N54W. A WEAK LOW PRES
SYSTEM REMAINS ALONG THIS TROUGH NEAR 26N52W WITH ONLY ISOLATED
SHOWERS. THIS SFC FEATURE IS ASSOCIATED WITH A SMALL UPPER LOW
NEAR 26N50W. A NARROW UPPER RIDGE EXTENDS NORTH FROM THE TROPICS
ALONG 40W. THE REMAINDER OF THE ATLC...E OF 35W...IS DOMINATED
BY A LARGE CUT OFF LOW CENTERED NEAR 26N22W. SCATTERED MODERATE
CONVECTION IS MAINLY ON THE N SIDE OF THE LOW FROM 26N-30W
BETWEEN 18W-24W. A SFC TROUGH...REFLECTION OF THIS UPPER LOW
RUNS FROM 20N25W TO 31N20W. AT THE SFC...A 1033 MB HIGH CENTERED
OVER THE AZORES EXTENDS A RIDGE ACROSS THE E-CENTRAL ATLC.

$$
GR





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