[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 170001
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST FRI NOV 16 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...
A TROPICAL WAVE IS ALONG 54W SOUTH OF 17N MOVING WEST 10-15 KT.
SOME CYCLONIC TURNING IS STILL NOTED ALONG THE WAVE AXIS NEAR
10N. THE CIMSS 850 MB VORTICITY PRODUCT PROVIDES GOOD SUPPORT
FOR THE WAVE POSITION INDICATED. SHOWER ACTIVITY ASSOCIATED WITH
THIS SYSTEM HAS SLIGHTLY DIMINISHED THIS EVENING. WIDELY
SCATTERED MODERATE CONVECTION IS MOSTLY E OF OF THE WAVE AXIS
FROM 8N-12N BETWEEN 50W-55W.

A TROPICAL WAVE IS ALONG 75W SOUTH OF 20N MOVING WEST 10-15 KT.
A BROAD INVERTED-V LOW CLOUD PATTERN IS NOTED IN THE CARIBBEAN.
THIS WAVE SHOWS UP WELL IN THE LOW LEVEL SATELLITE DERIVED WINDS
AND 850 MB VORTICITY PRODUCTS FROM CIMSS. THIS FEATURE IS
GENERATING SCATTERED SHOWERS AND TSTMS OVER NORTHERN COLOMBIA
AND ACROSS THE CENTRAL CARIBBEAN MAINLY FROM 14N-18N BETWEEN
74W-77W.

...THE ITCZ...
THE ITCZ AXIS IS CENTERED ALONG 9N13W 6N30W 9N50W 9N62W. OTHER
THAN THE CONVECTION MENTIONED IN THE TROPICAL WAVE SECTION...
CLUSTERS OF MODERATE TO ISOLATED STRONG CONVECTION ARE WITHIN
50-60 NM EITHER SIDE OF AXIS BETWEEN 38W-48W. SIMILAR CONVECTION
IS NEAR 4N18W.

DISCUSSION...

THE GULF OF MEXICO...
A COLD AND DRY AIR MASS COVERS MOST OF THE GULF THIS EVENING
WITH A 1021 MB HIGH CENTERED OVER THE NE PORTION NEAR 30N87W.
FAIR SKIES ARE OVER THE NRN GULF WATERS WITH BROKEN COLD AIR
STRATOCUMULUS CLOUDS S OF 27N. THE LEADING EDGE OF THIS COLD AIR
MASS IS A COLD FRONT EXTENDING ACROSS CENTRAL CUBA AND THE
YUCATAN PENINSULA INTO THE BAY OF CAMPECHE. AS OF 2100 UTC...A
SFC TROUGH IS ANALYZED OVER THE SW PORTION OF THE GULF INCLUDING
THE BAY OF CAMPECHE. THE POSITION OF THIS TROUGH IS BASED ON SFC
OBSERVATIONS...AN EARLIER ASCAT PASS AND SATELLITE IMAGERY THAT
INDICATES PATCHES OF LOW/MID CLOUDS OVER THE SW GULF. THESE
CLOUDS ARE BANKING UP AGAINST THE SIERRA MADRE MOUNTAINS...
PARTICULARLY BETWEEN TAMPICO AND VERACRUZ. THE MIMIC-TPW PRODUCT
SHOWS VERY WELL THE COLD/DRY AIR GRIPPING MOST OF THE AREA AS
WELL AS SOME INCREASE IN MOISTURE ACROSS THE NW PART OF THE GULF
DUE TO THE RETURN FLOW AND THE PRESENCE OF THE ABOVE MENTIONED
TROUGH. WITH THE COLD AIR IN PLACE ACROSS THE SE U.S. FREEZE
WARNINGS HAVE BEEN ISSUED FOR PARTS OF SOUTH GEORGIA AND NORTH
FLORIDA. HIGH PRES OVER THE NORTH GULF COAST WILL SLOWLY SHIFT
EAST AND WEAKEN THROUGH SUNDAY. ALOFT...AN UPPER RIDGE WITH
MODERATE TO STRONG SUBSIDENCE DOMINATES THE ENTIRE GULF.

THE CARIBBEAN SEA...
A FAST MOVING COLD FRONT ENTERED THE NW CARIBBEAN THIS MORNING.
AS OF 2100 UTC...THE FRONT EXTENDS ACROSS THE CENTRAL BAHAMAS
AND CENTRAL CUBA TROUGH THE NW CARIBBEAN ALONG 21N85W INTO THE
YUCATAN PENINSULA. THE FRONT IS MOSTLY DRY WITH A VERY THIN LINE
OF SCATTERED SHOWERS WITHIN 30 NM OF THE FRONT. PATCHES OF
LOW/MID CLOUDS WITH LIGHT RAIN ARE OVER PARTS OF THE YUCATAN
PENINSULA...BELIZE AND NORTHERN HONDURAS. THE FRONT IS FORECAST
TO DISSIPATE TONIGHT. TRADE WINDS ARE EXPECTED TO INCREASE
DURING THE UPCOMING WEEKEND AS HIGH PRES OVER THE N GULF WATERS
MOVES EWD ACROSS THE W ATLC. A TROPICAL WAVE IS OVER THE CENTRAL
CARIBBEAN. SEE ABOVE. NELY WINDS AHEAD OF THE WAVE AXIS ARE
TRANSPORTING LOW LEVEL MOISTURE ACROSS THE SW CARIBBEAN INTO
NICARAGUA AND COSTA RICA. CLUSTERS OF MODERATE TO ISOLATED
STRONG CONVECTION ARE OVER THE EAST SECTOR OF DOMINICAN REPUBLIC
INCLUDING SANTO DOMINGO AND PARTS OF PUERTO RICO. A DIFFLUENT
PATTERN ALOFT BETWEEN A DEEP LAYERED TROUGH OVER THE W ATLC...
WHICH IS SUPPORTING THE AFOREMENTIONED COLD FRONT...AND A RIDGE
OVER THE CENTRAL ATLC IS ENHANCING THIS ACTIVITY. IN THE UPPER
LEVELS...A BROAD RIDGE IS OVER THE ENTIRE CARIBBEAN SEA WITH A
GOOD AMOUNT OF MOISTURE S OF 18N AND W OF 80W.

THE ATLANTIC OCEAN...
THE ABOVE MENTIONED COLD FRONT CROSS JUST SE OF BERMUDAS AND
ENTERS THE FORECAST AREA NEAR 31N64W THEN CONTINUES SW THROUGH
THE CENTRAL BAHAMAS/CUBA. BROKEN TO OVERCAST COLD AIR
STRATOCUMULUS CLOUDS ARE BEHIND THE FRONT WITH 15-20 KT NLY
WINDS. AN AREA OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION
IS WELL E OF THE FRONT COVERING FROM 21N-31N BETWEEN 55W-62W
MOSTLY DUE TO THE UPPER LEVEL DIFFLUENCE PREVIOUSLY MENTIONED IN
THE CARIBBEAN SECTION. A PRE-FRONTAL TROUGH MAY BE ADDED TO THE
0000 UTC MAP FROM DOMINICAN REPUBLIC ALL THE WAY NE TO 31N60W TO
TAKE IN ACCOUNT THIS CONVECTIVE ACTIVITY. ANOTHER COLD FRONT IS
OVER THE E ATLC AND EXTENDS FROM A 1007 MB LOW LOCATED JUST WEST
OF THE MADEIRA ISLANDS ALONG 26N27W TO 24N38W. SCATTERED SHOWERS
ARE WITHIN 60 NM OF THE FRONT. AN AREA OF SCATTERED MODERATE
CONVECTION IS BEHIND THE FRONT FROM 24N-27N BETWEEN 31W-35W
AGAIN DUE TO UPPER LEVEL DIFFLUENCE. BETWEEN COLD FRONTS...
THERE IS A RIDGE ANCHORED ON A 1030 MB HIGH LOCATED WELL N OF
THE AREA. IN THE UPPER LEVELS...A TROUGH/RIDGE/TROUGH PATTERN
DOMINATES THE REGION.

$$
GR






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