[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 180011 CCA
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST SAT NOV 17 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...TROPICAL WAVES...
TROPICAL WAVE IS OVER THE WINDWARD ISLANDS ALONG 61W/62W S OF
16N MOVING W AT 15 KT. CONVECTION ASSOCIATED WITH THE WAVE HAS
DIMINISHED DURING THE LAST FEW HOURS. THIS FEATURE IS GENERATING
SCATTERED SHOWERS AND ISOLATED TSTMS MAINLY SOUTH OF GUADALOUPE.

TROPICAL WAVE IS IN THE CENTRAL CARIBBEAN ALONG 78W S OF 17N
MOVING W 10-15 KT. CONVECTION IS MOSTLY W OF THE WAVE AXIS.
NELY WINDS AHEAD OF THE WAVE AXIS ARE TRANSPORTING LOW LEVEL
MOISTURE ACROSS THE SW CARIBBEAN INTO CENTRAL AMERICA. SCATTERED
MODERATE CONVECTION IS WEST OF 80W TO THE COAST OF NICARAGUA AND
OVER PARTS OF PANAMA.

...THE ITCZ...
THE ITCZ IS PRETTY ACTIVE THIS EVENING. IT AXIS IS CENTERED
ALONG 7N12W 5N30W 8N50W 10N61W. SCATTERED MODERATE/ISOLATED
STRONG CONVECTION IS WITHIN 160 NM N OF AXIS BETWEEN 36W-43W...
AND WITHIN 100 NM N OF AXIS BETWEEN 45W-52W. SIMILAR CONVECTION
IS FOUND FROM 8N-12N BETWEEN 55W-60W. A CLUSTER OF MODERATE TO
STRONG CONVECTION IS JUST MOVING OUT OF THE AFRICA COAST THROUGH
SIERRA LEONE.

DISCUSSION...

THE GULF OF MEXICO...
THE HIGH PRESSURE THAT BROUGHT IN THE COOL AND DRY AIR MASS IS
SHIFTING EAST INTO THE ATLC. AS OF 2100 UTC...A 1022 MB HIGH IS
CENTERED OVER THE W ATLC NEAR 31N76W WITH RIDGE ENVELOPING THE
STATE OF FLORIDA AND THE GULF. FAIR SKIES ARE OVER THE NE GULF
OF MEXICO WITH SCATTERED TO BROKEN COLD AIR STRATOCUMULUS CLOUDS
ELSEWHERE. LOW LEVEL RETURN FLOW ON THE WESTERN SIDE OF THE HIGH
IS ENHANCING SOME CLOUDINESS WITH EMBEDDED SHOWERS AND TSTMS
ALONG THE TEXAS COAST. THIS ACTIVITY IS AHEAD OF A MID/UPPER
LEVEL TROUGH MOVING ACROSS TEXAS AND N-CENTRAL MEXICO...AND A
SFC TROUGH. SWLY WINDS AHEAD OF THE UPPER TROUGH ARE DRAWING A
BAND OF MOISTURE NORTHWARD ACROSS N-CENTRAL MEXICO...TEXAS AND
THE SE OF U.S.. THE SFC TROUGH IS FORECAST TO MOVE OVER THE NW
GULF WATERS ON SUNDAY. SOUTH WINDS AHEAD OF THE TROUGH WILL
SLIGHTLY INCREASE TONIGHT. AN UPPER-LEVEL RIDGE CONTINUES TO
DOMINATE MOST OF THE GULF WITH DRY AIR/SUBSIDENCE.

THE CARIBBEAN SEA...
THE FAST MOVING COLD FRONT THAT SWEPT ACROSS THE GULF AND THE NW
CARIBBEAN DURING THE PREVIOUS TWO DAYS IS NOW NEARLY STATIONARY
EXTENDING FROM THE EASTERN TIP OF CUBA TO THE COAST OF BELIZE.
THE FRONT IS GRADUALLY LOSING ITS IDENTITY ACROSS THE AREA BUT
IS STILL GENERATING SOME PATCHES OF LOW/MID CLOUDS OVER BELIZE
AND NORTHERN GUATEMALA. NE WINDS OF 15-20 KT ARE NOTED BEHIND
THE FRONT. THERE ARE ALSO TWO TROPICAL WAVES MOVING WWD ACROSS
THE BASIN. A BROAD UPPER-LEVEL RIDGE DOMINATES THE ENTIRE
CARIBBEAN. UPPER DIFFLUENCE BETWEEN THIS RIDGE AN UPPER TROUGH
MOVING EWD ACROSS THE W-CENTRAL ATLC CONTINUES TO SUPPORT THE
DEVELOPMENT OF SCATTERED SHOWERS AND TSTMS OVER HISPANIOLA AND
WITHIN 140 NM NORTH OF THE ABC ISLANDS. AS WAS PREDICTED BY THE
COMPUTER MODELS...TRADE WINDS HAVE INCREASE ACROSS THE CENTRAL
CARIBBEAN...MAINLY JUST OFFSHORE THE COLOMBIAN COAST. ELY WINDS
ARE EXPECTED TO BE IN THE 25 TO 30 KT RANGE TONIGHT THROUGH SUN
NIGHT.

THE ATLANTIC OCEAN...
A COLD FRONT ENTERS THE FORECAST AREA NEAR 31N55W THEN CONTINUES
SW TO THE SE BAHAMAS AND THE EASTERN TIP OF CUBA WHERE IT
BECOMES NEARLY STATIONARY. POCKETS OF COLD AIR STRATOCUMULUS
CLOUDS ARE BEHIND THE FRONT WHILE SCATTERED MODERATE CONVECTION
REMAINS WELL AHEAD OF THE FRONT AFFECTING FROM 25N-31N BETWEEN
50W AND THE FRONT IT SELF. ANOTHER COLD FRONT IS OVER THE E
ATLANTIC APPROACHING THE MADEIRA/CANARY ISLANDS AND EXTENDS
ALONG 31N18W 25N25W 23N40W. A REINFORCING COLD FRONT IS FURTHER
NW WITHIN 240 NM OF THE MAIN FRONT WHICH IS GENERATING A
CLUSTER OF MODERATE TO STRONG CONVECTION JUST SW OF THE MADEIRA
ISLANDS. IN THE UPPER LEVELS...A TROUGH/RIDGE/TROUGH PATTERN
DOMINATES THE DISCUSSION AREA. MOSTLY WLY FLOW IS OVER THE
TROPICAL ATLANTIC...PARTICULARLY S OF 20N AND E OF 50W. THE
UPPER-LEVEL RIDGE THAT DOMINATES THE CARIBBEAN SEA EXTENDS
EASTWARD ACROSS THE LEEWARD ISLANDS INTO THE TROPICAL NORTH
ATLANTIC.

$$
GR





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