[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 111040
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
705 AM EST WED DEC 11 2013

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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1015 UTC.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH AXIS EXTENDS ACROSS AFRICA INTO THE EAST
TROPICAL ATLC NEAR 09N13W TO 09N17W. THE ITCZ AXIS EXTENDS FROM
09N17W TO 05N30W TO 09N47W TO 09N61W. SCATTERED MODERATE
CONVECTION IS FROM 05N-10N BETWEEN 29W-46W. SIMILAR CONVECTION
IS WITHIN AN AREA ENCLOSED BY A LINE FROM 19N19W TO 10N35W AND A
LINE EXTENDING FROM 14N17W TO 10N23W. ISOLATED SHOWERS ARE FROM
07N-11N BETWEEN 56W-61W.

...DISCUSSION...

GULF OF MEXICO...
A BROAD MIDDLE TO UPPER LEVEL TROUGH WITH AXIS EXTENDING FROM
MAINE SW TO CENTRAL FLORIDA SUPPORTS A COLD FRONT ANALYZED FROM
WESTERN-CENTRAL FLORIDA NEAR 26N82W SW TO 24N88W TO THE BAY OF
CAMPECHE NEAR 18N93W. A 1031 MB HIGH CENTERED IN THE LOWER
MISSISSIPPI VALLEY NEAR 33N90W EXTENDS A RIDGE AXIS INTO THE
GULF AND SUPPLIES NORTHEASTERLY WIND FLOW UP TO 20 KT E OF 95W.
HOWEVER...A TIGHT PRESSURE GRADIENT BEHIND THE COLD FRONT IN THE
SW GULF SUPPORT NEAR GALE FORCE WINDS. SSMI TPW IMAGERY DEPICT
DRY AIR OVER THE BASIN AT THE LOWER LEVELS WHICH IS SUSTAINING
FAIR WEATHER. TONIGHT OR NEAR 12/0000 UTC...THE COLD FRONT IS
FORECAST TO EXTEND FROM EVERGLADES CITY FLORIDA TO THE CENTRAL-
SOUTHERN GULF WHILE THE PORTION OF THE FRONTAL BOUNDARY OVER THE
SW GULF IS EXPECTED TO STALL. WITHIN THE FOLLOWING 24
HOURS...THE COMPLETE FRONTAL BOUNDARY IS EXPECTED TO BECOME
STATIONARY WHILE IT SLOWLY DISSIPATE. HIGH PRESSURE AND
NORTHEASTERLY WIND FLOW ARE EXPECTED TO CONTINUE ACROSS THE GULF
THROUGHOUT FRIDAY MORNING.

CARIBBEAN SEA...
A MIDDLE-LEVEL INVERTED TROUGH WEST OF 70W CONTINUES TO SUPPORT
A SURFACE TROUGH ANALYZED FROM 21N85W TO 15N86W. LOW-LEVEL
MOISTURE CONVERGENCE IN THE NW BASIN AS WELL AS UPPER-LEVEL
DIVERGENCE SUPPORT SCATTERED MODERATE CONVECTION AND ISOLATED
TSTMS FROM 10N-18N BETWEEN 78W-81W AND FROM 16N-21N WEST OF 82W.
ALOFT AND ACROSS THE REMAINDER BASIN WESTERLY WIND FLOW AND DRY
AIR SUBSIDENCE DOMINATE. NORTHEASTERLY-EASTERLY WIND FLOW
ASSOCIATED WITH A SURFACE RIDGE ANCHORED BY A 1026 MB HIGH IN
THE CENTRAL ATLC ADVECTS VERY DRY AIR TO THE EASTERN AND CENTRAL
BASIN WHICH ALONG WITH MIDDLE-LEVEL DRY AIR SUBSIDENCE SUPPORT
FAIR WEATHER. RAINSHOWERS HAVE BEEN REPORTED OVER THE SOUTHERN
WINDWARD ISLANDS BEING ENHANCED BY PROXIMITY TO THE ITCZ AXIS.
OTHERWISE...A RELATIVELY TIGHT PRESSURE GRADIENT OVER THE
CENTRAL-EASTERN BASIN SUPPORTS 20-25 KT WINDS EXPECTED TO
PERSIST THROUGHOUT FRI MORNING. THE SURFACE TROUGH WILL CONTINUE
A WESTWARD TRACK AND IS FORECAST TO MOVE ACROSS THE YUCATAN
PENINSULA AND NORTHERN CENTRAL AMERICA LATER TODAY GENERATING
SHOWERS TO THIS REGION AND ADJACENT WATERS. WINDS OF 20-25 KT
ARE EXPECTED FOR THE NW BASIN BY THU NIGHT IN ASSOCIATION TO THE
SURFACE RIDGE CURRENTLY ACROSS THE GULF.

HISPANIOLA...
FAIR WEATHER DOMINATES ACROSS THE ISLAND BEING SUPPORTED BY DRY
AIR SUBSIDENCE FROM THE MIDDLE LEVELS AND DRY AIR ADVECTION FROM
THE NORTH-CENTRAL ATLC AS DEPICTED IN SSMI TPW IMAGERY. FAIR
WEATHER IS EXPECTED TO PERSIST THROUGHOUT FRI MORNING AS MIDDLE
TO LOWER LEVEL DRY AIR WILL CONTINUE TO MOVE ACROSS THE ISLAND.
HOWEVER...AFTERNOON/EARLY EVENING SHOWERS ARE LIKELY WITHIN THAT
TIME PERIOD.

ATLANTIC OCEAN...
A BROAD MIDDLE TO UPPER LEVEL TROUGH WITH AXIS EXTENDING FROM
MAINE SW TO CENTRAL FLORIDA SUPPORTS A COLD FRONT ANALYZED FROM
30N72W SW TO EASTERN-CENTRAL FLORIDA NEAR 27N80W. VERY DRY AIR
ACROSS THE SW NORTH ATLC AND CENTRAL ATLC HINDERS CONVECTION AT
THE TIME. FARTHER EAST OVER THE CENTRAL ATLC...A 1026 MB HIGH IS
NEAR 32N41W WHICH IS EXPECTED TO DRIFT SE OVER THE NEXT 24 HOURS
MAINTAINING FAIR WEATHER CONDITIONS. A MIDDLE TO UPPER LEVEL
TROUGH ACROSS THE EASTERN ATLC SUPPORTS A COLD FRONT ANALYZED
FROM 30N19W TO 24N25W TO 21N32W WHERE IT TRANSITIONS TO A
DISSIPATING COLD FRONT TO 19N39W. FARTHER EAST...THE SAME TROUGH
ALOFT SUPPORTS A SURFACE TROUGH EXTENDING ALONG 30N14W TO
24N18W. SCATTERED SHOWERS AND TSTMS ASSOCIATED WITH THIS LOW
PRESSURE SYSTEM ARE N OF 24N BETWEEN 14W-19W.

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

$$
NR


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