[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 042351
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST FRI DEC 04 2015

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
2345 UTC.

...ITCZ/MONSOON TROUGH...
THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 02N AND THE
PRIME MERIDIAN TO 05N14W TO 04N20W TO 05N30W TO THE COAST OF
BRAZIL NEAR 01N45W. SCATTERED MODERATE CONVECTION IS FROM THE
EQUATOR TO 03N BETWEEN 05W-15W...AND FROM 02N-08N BETWEEN 13W-
19W.

...DISCUSSION...

GULF OF MEXICO...
UPPER LEVEL SOUTHWESTERLY FLOW ALOFT IS COUPLED WITH MID-LEVEL
ENERGY ASSOCIATED WITH A SHORTWAVE TROUGH AXIS EXTENDING OVER NE
FLORIDA SW TO OVER EAST-CENTRAL MEXICO AS OF 04/2100 UTC. THESE
CONDITIONS ARE SUPPORTING A SURFACE STATIONARY FRONT MEANDERING
FROM THE SW TIP OF THE FLORIDA PENINSULA JUST N OF THE MIDDLE
KEYS TO JUST N OF THE WESTERN TIP OF CUBA NEAR 23N85W. A
CARIBBEAN SURFACE TROUGH STRETCHES FROM A 1015 MB LOW NEAR
17N86W NE TO THE STRAITS OF FLORIDA NEAR 23.5N83W. THE
COMBINATION OF THE FRONT SERVING AS A FOCUSING MECHANISM FOR
SURFACE CONVERGENCE...ALONG WITH DEEP MIDDLE AND UPPER LEVEL
MOISTURE IN SW FLOW IS BRINGING AREAS OF RAIN WITH EMBEDDED
SCATTERED TO SHOWERS AND TSTMS WHICH ARE CONFINED TO THE FAR SE
PORTION OF THE GULF AND S FLORIDA BETWEEN THE MIDDLE LEVEL
TROUGH AXIS AND THE FRONTAL BOUNDARY. MOST MIDDLE TO UPPER LEVEL
CLEARING IS NOTED ON WATER VAPOR IMAGERY ACROSS THE REMAINDER OF
THE GULF EARLY THIS EVENING. MAINLY FRESH TO STRONG N-NE WINDS
PREVAIL TO NW OF THE FRONTAL BOUNDARY ACROSS THE SE HALF OF THE
BASIN...WITH LIGHTER WINDS IN THE MODERATE BREEZE RANGE ACROSS
THE NW HALF OF THE GULF TO THE TEXAS COAST. THE FRONT WILL BE
SLOW TO SLIDE GRADUALLY EASTWARD THROUGH SATURDAY EXTENDING FROM
THE STRAITS OF FLORIDA TO THE YUCATAN PENINSULA. A NEW COLD
FRONT IS FORECAST TO ENTER THE NW GULF SUN MORNING...SWEEPING
ACROSS THE BASIN THROUGH SUN EVENING.

CARIBBEAN SEA...
UPPER LEVEL RIDGING IS NOTED ON WATER VAPOR IMAGERY OVER THE
WESTERN CARIBBEAN WITH THE AXIS ANCHORED NEAR 12N82W EXTENDING N-
NE TO BEYOND CENTRAL CUBA NEAR 22N79W. UPPER LEVEL DIFFLUENCE
ASSOCIATED WITH THE RIDGING ALOFT IN TANDEM WITH A WEAK 1015 MB
SURFACE LOW AT 17N86W NE TO THE STRAITS OF FLORIDA NEAR 23.5N83W
AS OF 04/2100 UTC CONTINUES TO PROVIDE THE FOCUS FOR SCATTERED
SHOWERS AND TSTMS ACROSS THE NW CARIBBEAN N OF 18N BETWEEN 78W-
82W...AS WELL AS FROM 15N TO 18N BETWEEN 82W-84W. THIS AREA HAS
EXPERIENCED PERSISTENT SURFACE TROUGHING ACROSS THE NW CARIBBEAN
DURING THE PAST SEVERAL DAYS AS A FRONTAL BOUNDARY CONTINUES TO
DRIFT ACROSS THE SE GULF OF MEXICO. FRESH NORTHERLY FLOW IS
NOTED W OF THE SURFACE TROUGH AXIS UP ALONG AND OFFSHORE OF THE
EASTERN COAST OF THE YUCATAN PENINSULA. ELSEWHERE...AN UPPER
LEVEL LOW IS CENTERED OVER THE DOMINICAN REPUBLIC NEAR 15.5N70W
WITH A RELATED TROUGH EXTENDING SSW TO 15N71W TO JUST N OF THE
COAST OF COLOMBIA NEAR 13N72W. MIDDLE TO UPPER LEVEL MOISTURE
ADVECTION IS OCCURRING ON SOUTHWESTERLY WINDS E OF THE TROUGH
AXIS ALONG 70W-72W. SCATTERED SHOWERS AND ISOLATED TSTMS NOTED E
OF THE TROUGH FROM 11N-17N. WITH THE DEEP MOISTURE IN PLACE E OF
THE TROUGH CHANGING LITTLE THROUGH THE NEXT 48 HOURS...AND
COMBINING WITH THE PREVAILING TRADES...EXPECT THE SHOWER AND
TSTM ACTIVITY TO LAST THROUGH THE NEXT 48 HOURS OR SO.
OTHERWISE...FRESH TO STRONG TRADES PREVAIL ACROSS MOST OF THE
BASIN...EXCEPT W OF 80WAND E OF THE SURFACE TROUGH AXIS WHERE
BROAD GENTLE CYCLONIC FLOW WILL PREVAIL.

...HISPANIOLA...
THE AFOREMENTIONED UPPER LEVEL LOW OVER THE DOMINICAN REPUBLIC
NEAR 15.5N70W CONTINUES TO PROVIDE FOR AMPLE LOW-LEVEL MOISTURE
MAINLY E OF 70W-71W WITH DRIER AND MORE STABLE AIR IN PLACE W OF
71W. MODEL GUIDANCE SUGGESTS THAT THE UPPER LOW WILL SLOWLY
DRIFT EASTWARD AND WEAKEN TO A TROUGH BY SUN EVENING AS UPPER
LEVEL RIDGING SETTLES IN WITH A DRYING TREND SPREADING
EASTWARD IN ITS WAKE.

ATLANTIC OCEAN...
UPPER LEVEL TROUGHING EXTENDS FROM OVER THE CANADIAN MARITIMES
SW TO OVER THE U.S. MID-ATLANTIC REGION WITH SHORTWAVE TROUGHING
AND VERY DRY AND STABLE AIR PREVAILING OVER THE CAROLINAS SW TO
THE CENTRAL GULF OF MEXICO. AS OF 04/2100 UTC THE TROUGHING
SUPPORTS A COLD FRONT ANALYZED FROM NEAR 31N63W SW TO A WEAK
1018 MB SURFACE LOW AT 28N77W...THEN STRADDLES THE SE FLORIDA
COAST AS A STATIONARY FRONT AND SW TO JUST N OF THE FLORIDA
KEYS. A JET STREAM BRANCH STRETCHES FROM THE SW GULF OF MEXICO
NE TO ACROSS S FLORIDA...AND NE TO N OF THE AREA NEAR 32N65W.
RIPPLES OF SHORTWAVE ENERGY ALONG THE JET STREAM ARE FLOWING NE
IN THE VICINITY OF THE FRONT WHICH ARE RESULTING IN WIDESPREAD
AREAS OF RAIN WITH EMBEDDED SCATTERED SHOWERS AND TSTMS OBSERVED
FROM 26N-31N BETWEEN 70W-77W...AND ALSO S OF 28N W OF 77W TO
JUST SE OF THE S FLORIDA COAST. SIMILAR ACTIVITY WITH POSSIBLE
GUSTY WINDS IS VERY ACTIVE ACROSS THE STRAITS OF FLORIDA EARLY
THIS EVENING. THE INTERACTION BETWEEN THE FRONT AND STRONG HIGH
PRESSURE TO ITS N WILL BRING FRESH TO NEAR GALE FORCE NE-E WINDS
OVER THE WATERS TO THE N OF THE FRONT INTO SUN BEFORE
DIMINISHING. THE COLD FRONT PORTION OF THE BOUNDARY WILL REACH
FROM NEAR 32N65W TO NEAR 28N73W BY SUN EVENING. OTHERWISE...
SURFACE HIGH PRESSURE PREVAILS ACROSS THE REMAINDER OF THE
CENTRAL AND EASTERN ATLC ANCHORED BY A 1033 MB HIGH CENTERED
SW OF THE AZORES NEAR 37N29W.

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

$$
LEWITSKY
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