[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 161743
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST SUN NOV 16 2008

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS
OF SOUTH AMERICA...AND 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.

...THE ITCZ...
THE ITCZ AXIS IS ANALYZED ALONG 7N10W 5N22W 7N36W 11N49W 10N61W.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 3N-9N
BETWEEN 16W-25W. SCATTERED MODERATE CONVECTION IS FROM 3N-5N
BETWEEN 26W-37W. SCATTERED MODERATE CONVECTION IS ALSO FROM
7N-11N BETWEEN 43W-49W.

...DISCUSSION...

GULF OF MEXICO...
A BROAD UPPER LEVEL TROUGH OVER THE EASTERN HALF OF THE CONUS
EXTENDS INTO THE GULF...WITH WESTERLY FLOW ALOFT AND DEEP LAYER
DRY AIR COVERING MUCH OF THE GULF REGION. ALSO...THE GULF REGION
IS IN THE WAKE OF A SURFACE COLD FRONT THAT EXTENDS FROM THE SW
ATLC INTO THE NW CARIBBEAN...WITH A MODIFIED CONTINENTAL POLAR
AIRMASS IN PLACE ACROSS THE GULF REGION. AS A RESULT...
TEMPERATURES ALONG THE N GULF COAST THIS AFTERNOON ARE BELOW
SEASONAL AVERAGES. THIS RELATIVELY COOLER AND DRIER AIRMASS IS
BEING SUPPORTED BY SURFACE HIGH PRESSURE OVER SE TEXAS...WITH A
SURFACE RIDGE EXTENDING INTO THE W GULF. AS THE COOLER AIR IS
BEING ADVECTED OVER THE RELATIVELY WARMER GULF WATERS...WEAK LOW
LEVEL INSTABILITY IS SUPPORTING STRATOCUMULUS CLOUD DEVELOPMENT
ACROSS THE GULF. HOWEVER...SUBSIDENCE AND STABLE ATMOSPHERIC
CONDITIONS HIGHER IN THE ATMOSPHERE ARE INHIBITING DEEP
CONVECTION ACROSS THE GULF REGION. ADDITIONALLY...STRONG N TO NE
SURFACE WINDS ARE BLOWING THROUGH THE ISTHMUS OF TEHUANTEPEC
RESULTING IN STORM FORCE WINDS IN THE E PACIFIC REGION.

CARIBBEAN SEA...
ACROSS THE NW CARIBBEAN...A COLD FRONT IS MOVING TO THE
SOUTHEAST...AND EXTENDS FROM W CUBA NEAR 23N81W TO 21N85W TO
20N88W. HOWEVER...THE MAJORITY OF THE UPPER LEVEL ENERGY THAT
HAS BEEN SUPPORTING THIS COLD FRONT IS NOW WELL TO THE NORTH OF
THE FRONT. AS A RESULT...THE TEMPERATURE AND DEWPOINT CONTRAST
ACROSS THE FRONT IS WEAKENING SOMEWHAT. HOWEVER...LOW LEVEL
CONVERGENCE AND MOISTURE ARE SUFFICIENT TO SUPPORT INCREASED
CLOUDINESS AND ISOLATED SHOWERS WITHIN 60 NM EITHER SIDE OF THE
SURFACE COLD FRONT. ALSO...AN UPPER HIGH IS OVER THE W CARIBBEAN
AND IS CENTERED NEAR 17N82W...WITH AN UPPER RIDGE AXIS EXTENDING
FROM THE UPPER HIGH TO E CUBA NEAR 21N77W TO THE SW ATLC. OVER
THE E CARIBBEAN...AN UPPER LEVEL TROUGH IS PRESENT...WHICH
EXTENDS FROM NW COLOMBIA NEAR 10N75W TO 16N71W TO THE DOMINICAN
REPUBLIC NEAR 19N70W. WEAK INSTABILITY IN THE VICINITY OF THIS
UPPER TROUGH...COMBINED WITH GREATER DEEP MOISTURE OVER THE E
CARIBBEAN...IS SUPPORTING SCATTERED SHOWERS AND THUNDERSTORMS S
OF 14N E OF 69W INCLUDING PORTIONS OF THE WINDWARD ISLANDS...
WITH ISOLATED SHOWERS AND THUNDERSTORMS ELSEWHERE E OF 79W. THE
ACTIVITY IN THE SE CARIBBEAN IS BEING FURTHER ENHANCED BY LOW
LEVEL CONVERGENCE NEAR A SURFACE TROUGH THAT HAS BEEN ADDED TO
THE 16/1200 UTC SURFACE ANALYSIS BASED ON CYCLONIC CURVATURE
NOTED IN THE NEARBY SURFACE WIND OBSERVATIONS. THE SURFACE
TROUGH EXTENDS FROM 15N66W TO 12N66W TO N VENEZUELA NEAR 9N65W.

ATLANTIC OCEAN...
A BROAD UPPER TROUGH OVER THE E HALF OF THE CONUS IS AFFECTING
THE W ATLC...WHICH IS SUPPORTING A SURFACE COLD FRONT THAT
EXTENDS FROM W CUBA NEAR 23N81W TO THE BAHAMAS NEAR 25N77W TO
32N72W TO NE OF THE DISCUSSION AREA. ISOLATED SHOWERS AND
THUNDERSTORMS ARE OCCURRING WITHIN 60 NM EITHER SIDE OF THE COLD
FRONT...WITH THE COVERAGE BEING LIMITED AS THE STRONGEST UPPER
LEVEL ENERGY MOVES NORTH OF THE DISCUSSION AREA. IN THE WAKE OF
THE COLD FRONT...A MODIFIED CONTINENTAL POLAR AIRMASS IS IN
PLACE...WITH TEMPERATURES BELOW SEASONAL AVERAGES ACROSS THE
FLORIDA PENINSULA. THIS RELATIVELY COOLER AND DRIER AIRMASS IS
BEING REINFORCED BY A SURFACE COLD FRONT THAT EXTENDS FROM THE N
FLORIDA PENINSULA NEAR 30N82W TO 31N80W TO 32N79W TO NE OF THE
DISCUSSION AREA. FARTHER TO THE E...A SURFACE RIDGE IS N OF 20N
BETWEEN 46W-63W...WHICH IS BEING SUPPORTED BY AN UPPER LEVEL
RIDGE WITH AN AXIS EXTENDING FROM E CUBA NEAR 21N77W TO 26N66W
TO 32N62W TO N OF THE DISCUSSION AREA. TO THE E...A SURFACE
TROUGH EXTENDS FROM A 1006 MB SURFACE LOW NEAR 34N32W TO 28N33W
TO 23N38W. LOW LEVEL CONVERGENCE NEAR THE SURFACE TROUGH AND
SURFACE LOW IS SUPPORTING SCATTERED SHOWERS N OF 26N BETWEEN
27W-34W. THIS ACTIVITY IS BEING ENHANCED BY UPPER LEVEL
DIFFLUENCE BETWEEN AN UPPER TROUGH OVER THE CENTRAL ATLC AND AN
UPPER RIDGE OVER THE NE ATLC. FARTHER TO THE S...AN UPPER RIDGE
IS S OF 16N BETWEEN THE AFRICAN COAST AND 43W. UPPER LEVEL
DIVERGENCE IN THE VICINITY OF THIS UPPER RIDGE IS ENHANCING THE
CONVECTION ASSOCIATED WITH THE ITCZ.

$$
COHEN



This weather bulletin was brought to you by:
www.nashvilleweather.net