[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 252344
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT TUE SEP 25 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
2315 UTC.

...SPECIAL FEATURES...

TROPICAL STORM NADINE IS CENTERED NEAR 31.7N 30.4W AT 25/2100
UTC OR ABOUT 415 NM SSW OF THE AZORES MOVING WSW AT 4 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 997 MB. MAXIMUM SUSTAINED
WIND SPEED IS 40 KT WITH GUSTS TO 50 KT. ISOLATED MODERATE
CONVECTION IS WITHIN 120 NM OF THE CENTER. SEE LATEST NHC
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC
FOR MORE DETAILS.

...TROPICAL WAVES...

TROPICAL WAVE EXTENDS FROM 12N71W TO 18N67W MOVING W AT 10 KT.
THE WAVE HAS COME INTO BETTER ALIGNMENT WITH A 700 MB TROUGH
OVER THE CENTRAL CARIBBEAN THE PAST 24 HOURS AND IS EXPECTED TO
MOVE WESTWARD ON THE SOUTHERN PERIPHERY OF A MID-LEVEL RIDGE
ANCHORED OVER THE SW NORTH ATLC NEAR 26N71W. PLENTY OF LOW TO
MIDDLE LEVEL MOISTURE ACCOMPANIES THE WAVE WITH TOTAL
PRECIPITABLE WATER IMAGERY INDICATING ELEVATED VALUES FROM
10N-17N BETWEEN 65W-75W. THE RESULT IS SCATTERED MODERATE
CONVECTION OCCURRING OVER A LARGE AREA OF THE EASTERN AND
CENTRAL CARIBBEAN FROM 12N-20N BETWEEN 63W-73W.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 14N17W TO
10N23W TO 09N29W TO 11N39W. THE INTERTROPICAL CONVERGENCE ZONE
AXIS EXTENDS FROM 11N39W TO 13N44W TO 12N51W. SCATTERED MODERATE
CONVECTION IS FROM 11N-18N BETWEEN 13W-18W. ISOLATED MODERATE
CONVECTION IS FROM 04N-07N BETWEEN 21W-26W...AND FROM 11N-16N
BETWEEN 20W-23W.

...DISCUSSION...

GULF OF MEXICO...
WATER VAPOR IMAGERY INDICATES AN UPPER LEVEL SHORTWAVE TROUGH IS
OVER THE NE GULF WITH AXIS EXTENDING FROM 30N81W TO A BASE NEAR
23N90W. EAST OF THIS UPPER LEVEL TROUGH AXIS...UPPER LEVEL
DIFFLUENCE IS MAXIMIZED OVER THE SE GULF AND FLORIDA PENINSULA
DUE TO MOIST SOUTHWESTERLY FLOW BETWEEN THE TROUGH AND AN UPPER
ANTICYCLONIC CIRCULATION CENTERED OVER THE SW NORTH ATLC NEAR
25N72W. THE WEAK UPPER LEVEL TROUGHING CONTINUES TO PROVIDE LIFE
SUPPORT TO A DISSIPATING STATIONARY FRONT ANALYZED FROM THE
FLORIDA STRAITS NEAR 24N80W TO NORTH OF THE YUCATAN PENINSULA
NEAR 22N90W. WHILE LOW-LEVEL MOISTURE CONVERGENCE REMAINS
FOCUSED IN THE VICINITY OF THE FRONT...THE AMPLE DIFFLUENCE EAST
OF THE TROUGH AXIS IS GENERATING AN AREA OF SCATTERED SHOWERS
AND TSTMS SE OF A LINE FROM THE TAMPA BAY REGION NEAR 28N83W TO
23N90W. VERY LITTLE CHANGE IS EXPECTED THROUGH EARLY THURSDAY AS
THE MIDDLE TO UPPER LEVEL TROUGH REMAINS NEARLY STATIONARY
ACROSS THE EASTERN GULF. A SURFACE TROUGH IS ALSO ANALYZED
ACROSS THE SW GULF FROM 17N93W TO 22N96W AND IS A FOCUS FOR
WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS OCCURRING OVER THE
SW GULF S OF 22N W OF 90W. ELSEWHERE THE REMAINDER OF THE GULF
IS UNDER MOSTLY CLEAR SKIES THIS EVENING N OF 22N W OF 86W AS
VERY DRY AND SUBSIDENT AIR...EVIDENT ON WATER VAPOR IMAGERY...IS
IN PLACE ACROSS THE NW AND NORTH-CENTRAL GULF THIS EVENING. A
RIDGE OF HIGH PRESSURE EXTENDS SOUTHWESTWARD FROM A 1023 MB HIGH
CENTERED OVER CENTRAL GEORGIA NEAR 33N83W AND WILL CONTINUE TO
PROVIDE MUCH OF THE GULF WITH E TO SE WINDS IN THE RANGE OF 10
TO 20 KT OVER THE NEXT FEW DAYS.

CARIBBEAN SEA...
UPPER LEVEL RIDGING EXTENDS OVER THE NW CARIBBEAN BETWEEN TWO
UPPER LEVEL TROUGHS...ONE OVER THE EASTERN GULF OF MEXICO AND
THE OTHER OVER THE CENTRAL CARIBBEAN WITH AXIS FROM OVER
HISPANIOLA TO 10N77W. UPPER LEVEL DIFFLUENCE IS MAXIMIZED OVER
MUCH OF THE NW CARIBBEAN AND THIS SYNOPTIC SETUP IS GENERATING
SCATTERED SHOWERS AND ISOLATED TSTMS NW OF A LINE FROM EASTERN
CUBA NEAR 20N76W TO THE CENTRAL COAST OF NICARAGUA NEAR 13N84W.
THE MOST INTENSE CONVECTIVE ACTIVITY IS ACROSS WESTERN CUBA THIS
EVENING IN CLOSE PROXIMITY TO A DISSIPATING STATIONARY FRONT
ANALYZED ACROSS THE FLORIDA STRAITS AND PORTIONS OF THE GULF OF
MEXICO WATERS N OF THE YUCATAN CHANNEL. FARTHER EAST...A
TROPICAL WAVE ALONG 69W IN TANDEM WITH A 700 MB TROUGH AND THE
UPPER LEVEL TROUGHING MENTIONED ABOVE OVER THE CENTRAL
CARIBBEAN...IS GENERATING A LARGE AREA OF SCATTERED SHOWERS AND
ISOLATED TSTMS FROM 12N-20N BETWEEN 63W-73W. SOME OF THIS
ACTIVITY SPREADS SOUTHWARD OVER INLAND PORTIONS OF NORTHERN
COLOMBIA AND VENEZUELA THIS EVENING. OTHERWISE...EASTERLY TRADES
WILL DOMINATE OVER THE NEXT FEW DAYS WITH A BRIEF REPRIEVE BELOW
20 KT BEYOND EARLY THURSDAY.

ATLANTIC OCEAN...
MOIST SOUTHWESTERLY FLOW DOMINATES ACROSS THE SW NORTH ATLC
BETWEEN AN UPPER LEVEL TROUGH OVER THE EASTERN GULF OF MEXICO
AND AN UPPER LEVEL ANTICYCLONIC CIRCULATION CENTERED NEAR
25N72W. WHILE MUCH OF THE MIDDLE TO UPPER LEVEL MOISTURE REMAINS
AS MOSTLY BROKEN TO OVERCAST CLOUDINESS...A WEAKENING STATIONARY
FRONT IS ANALYZED FROM 32N68W TO 28N74W TO THE FLORIDA STRAITS
NEAR 24N80W AND IS PROVIDING FOCUS FOR WIDELY SCATTERED SHOWERS
AND ISOLATED TSTMS WITHIN 120 NM EITHER SIDE OF THE FRONT.
HIGHEST CONCENTRATION OF CONVECTIVE ACTIVITY REMAINS OVER THE
FLORIDA STRAITS AND WITHIN AN AREA FROM 28N-31N BETWEEN 66W-72W.
FARTHER EAST...AN UPPER LEVEL LOW IS CENTERED NEAR 23N57W AND TO
THE EAST OF THIS UPPER LEVEL LOW A SURFACE TROUGH IS ANALYZED
FROM 20N52W TO 24N48W. TOGETHER THESE TWO FEATURES ARE
GENERATING AN AREA OF WIDELY SCATTERED SHOWERS AND ISOLATED
TSTMS FROM 20N-25N BETWEEN 47W-57W. ELSEWHERE OVER THE REMAINDER
OF THE CENTRAL ATLC...A SURFACE RIDGE IS IN PLACE N OF 25N
BETWEEN 35W-65W ANCHORED BY A 1028 MB HIGH CENTERED NORTH OF THE
DISCUSSION AREA NEAR 42N43W. FINALLY...TROPICAL STORM NADINE
CONTINUES TO SPIN NEAR THE DISCUSSION AREA BORDER WITH CYCLONIC
WIND INFLUENCE REACHING SOUTHWARD TO 25N BETWEEN 24W-35W.
OTHERWISE...A SURFACE RIDGE AXIS EXTENDS FROM THE CANARY ISLANDS
TO A 1016 MB HIGH CENTERED NEAR 21N34W.

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

$$
HUFFMAN




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