[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 092313
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST SUN DEC 09 2012

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...WEATHER OBSERVATIONS...RADAR...AND
METEOROLOGICAL ANALYSIS.

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 2230 UTC.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS ACROSS WEST AFRICA TO THE COAST OF
GUINEA NEAR 10N15W CONTINUING TO 9N17W WHERE IT TRANSITIONS INTO
THE ITCZ ALONG 6N24W 4N34W 7N47W. SCATTERED MODERATE/ISOLATED
STRONG CONVECTION IS FROM 4N-7N BETWEEN 23W-36W. SIMILAR
ACTIVITY IS FROM 7N-9N BETWEEN 45W-50W. CONVECTION CONTINUES
FARTHER WEST...BUT IS ASSOCIATED WITH A SURFACE TROUGH AS WELL
AS AN UPPER LEVEL TROUGH. THIS CONVECTION WILL BE DISCUSSED IN
THE ATLC SECTION.

...DISCUSSION...

THE GULF OF MEXICO...
MAINLY SOUTHWEST-WEST FLOW ALOFT COVERS THE GULF OF MEXICO
AROUND AN UPPER LEVEL RIDGE WITH AXIS EXTENDING FROM THE NW
CARIBBEAN TO JUST EAST OF FLORIDA. WATER VAPOR IMAGERY INDICATES
THAT DRY AIR COVERS THE MAJORITY OF THE AREA...WHICH IS HELPING
PROVIDE FAIR CONDITIONS AT THE SURFACE. WEAK SURFACE RIDGING
ALSO CONTINUES TO SIT OVER THE BASIN PROVIDING LIGHT
ANTI-CYCLONIC FLOW OVER THE EASTERN GULF...AND SLIGHTLY STRONGER
RETURN FLOW ACROSS THE WESTERN GULF REACHING UP TO 15-20 KT. THE
SURFACE RIDGE IS EXPECTED TO WEAKEN FURTHER AND DISSIPATE AS A
COLD FRONT ENTERS THE NW GULF EARLY MONDAY ACCOMPANIED BY
SHOWERS/THUNDERSTORMS AND STRONG WINDS NEAR THE AXIS.

THE CARIBBEAN SEA...
AN UPPER LEVEL RIDGE COVERS THE WESTERN TWO-THIRDS OF THE
CARIBBEAN WITH AXIS FROM PANAMA TO CENTRAL CUBA. WATER VAPOR
IMAGERY INDICATES THAT DRY AIR SPREAD ACROSS THE MAJORITY OF THE
BASIN...WHICH IS PROVIDING FAIR CONDITIONS THROUGHOUT.
HOWEVER...A SURFACE TROUGH IS ANALYZED IN THE NW CARIBBEAN ALONG
86W FROM 17N-20N SUPPORTING SCATTERED SHOWERS FROM 19N-22N
BETWEEN 85W-87W. SHOWERS/THUNDERSTORMS ARE ALSO FARTHER EAST
FROM 17N-20N BETWEEN 80W-82W LIKELY DUE TO CONVERGING WIND
SPEEDS. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE ALSO IN THE
SW CARIBBEAN FROM 10N-13N BETWEEN 79W-83W ASSOCIATED WITH THE
MONSOON TROUGH THAT EXTENDS FROM SOUTHERN COSTA RICA TO NORTHERN
COLOMBIA. THE ONLY OTHER SHOWER ACTIVITY IS ANOTHER SMALL AREA
OF SCATTERED SHOWERS/ISOLATED THUNDERSTORMS NORTH OF VENEZUELA
FROM 12N-14N BETWEEN 67W-70W. THIS ACTIVITY MAY BE ENHANCED BY
THE TAIL END OF AN UPPER TROUGH EXTENDING FROM THE CENTRAL ATLC.
TRADEWIND FLOW OF 20-25 KT IS PRESENT ACROSS THE EASTERN AND
CENTRAL CARIBBEAN...AND IS EXPECTED TO PERSIST THROUGHOUT MUCH
OF THE WEEK. SHOWERS/THUNDERSTORMS WILL BE MOST LIKELY OVER THE
WESTERN CARIBBEAN.

THE ATLANTIC OCEAN...
A WEAK SURFACE TROUGH IS OVER THE FAR WESTERN ATLC ALONG 33N80W
TO 29N81W SUPPORTING SCATTERED SHOWERS UP TO 250 NM TO THE EAST
AND ALSO EXTENDING SOUTHWARD. THE REMAINDER OF THE SW NORTH ATLC
IS DOMINATED BY SURFACE RIDGING AROUND A 1026 MB HIGH NEAR
32N55W. THE RIDGE IS SUPPORTED BY AN UPPER LEVEL RIDGE EXTENDING
FROM THE CARIBBEAN INTO THE W ATLC ALONG 79W. THE SURFACE RIDGE
DOMINATES A GOOD PORTION OF THE CENTRAL ATLC AS WELL. FARTHER
EAST...AN UPPER LEVEL TROUGH EXTENDS FROM WEST OF THE AZORES
ISLANDS TO THE EASTERN CARIBBEAN ALONG 40N33W 23N47W 14N63W. THE
UPPER TROUGH SUPPORTS A DISSIPATING STATIONARY FRONT ALONG
30N29W 21N34W WHERE IT TRANSITIONS INTO A SHEAR AXIS TO NEAR
15N52W. ISOLATED SHOWERS ARE WITHIN 60 NM OF THE FRONT...WITH
SCATTERED SHOWERS WITHIN 150 NM OF THE SHEAR AXIS. A SURFACE
TROUGH IS WEST OF THE FRONT ALONG 32N34W 27N36W 25N45W. POSSIBLE
ISOLATED SHOWERS ARE ALONG THE AXIS. FINALLY...THE UPPER TROUGH
ALSO SUPPORTS A SURFACE TROUGH NEAR THE ITCZ REGION WITH AXIS
ALONG 14N56W 9N59W. SCATTERED SHOWERS/POSSIBLE THUNDERSTORMS ARE
FROM 7N-15N BETWEEN 50W-56W. UPPER LEVEL RIDGING COVERS THE
REMAINDER OF THE TROPICAL AND EASTERN ATLC.

FOR ADDITIONAL INFORMATION PLEASE VISIT
HTTP://WWW.HURRICANES.GOV/MARINE

$$
WALTON




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