[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 161754
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT FRI OCT 16 2009

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.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 73W S OF 17N MOVING W NEAR 15 KT. THE
WAVE REMAINS EMBEDDED WITHIN AN AREA OF DEEP LAYERED MOISTURE AS
INDICATED IN THE TOTAL PRECIPITABLE WATER IMAGERY ACROSS THE
CENTRAL CARIBBEAN. VISIBLE SATELLITE IMAGERY SHOWS CYCLONIC
CURVATURE IN THE LOW-LEVEL CLOUD FIELD IN THE VICINITY OF THE
WAVE AXIS WITH SCATTERED SHOWERS AND ISOLATED TSTMS FROM 13N-17N
BETWEEN 71W-75W.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 9N13W 7N27W 8N41W 7N45W 11N59W.
A SURFACE TROUGH IS EMBEDDED WITHIN THE ITCZ ALONG 43W FROM
5N-11N. SCATTERED TO NUMEROUS MODERATE/ISOLATED STRONG
CONVECTION IS FROM 5N-11N BETWEEN 39W-47W. A SECOND SURFACE
TROUGH IS ALONG 60W APPROACHING THE LESSER ANTILLES FROM
10N-16N. SCATTERED MODERATE CONVECTION IS FROM 9N-15N BETWEEN
55W-62W. ELSEWHERE...CLUSTERS OF SCATTERED MODERATE/ISOLATED
STRONG CONVECTION ARE FROM 4N-11N BETWEEN 20W-39W. A SIMILAR
AREA OF CONVECTION IS ALONG THE W AFRICA COAST FROM 5N-9N
BETWEEN 11W-16W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER LEVEL RIDGE IS ANCHORED OVER CENTRAL MEXICO COVERING
THE SW GULF AND BAY OF CAMPECHE WHILE BROAD UPPER LEVEL
TROUGHING DIPS OVER THE N/CENTRAL AND NE GULF TO 25N. THIS
LONGWAVE TROUGHING SUPPORTS A COLD FRONT THAT AT 1500 UTC ENTERS
THE GULF OVER THE BIG BEND REGION OF FLORIDA NEAR 30N84W AND
EXTENDS SW ALONG 27N90W TO NEAR BROWNSVILLE TEXAS AND INTO NE
MEXICO AS A STATIONARY BOUNDARY TO 27N104W. SCATTERED SHOWERS
AND ISOLATED TSTMS ARE WITHIN 90 NM EITHER SIDE OF THE FRONT W
OF 90W WHILE SCATTERED SHOWERS AND TSTMS ARE WITHIN 150 NM
EITHER SIDE OF THE FRONT E OF 90W TO INLAND OVER INTERIOR
PORTIONS OF THE CENTRAL FLORIDA PENINSULA. BEHIND THE COLD
FRONT...NLY WINDS UP TO 25 KT ARE EXPECTED TO CONTINUE SPREADING
OVER THE NW AND N/CENTRAL GULF THIS AFTERNOON INTO THE EVENING.
ELSEWHERE ACROSS THE REMAINDER OF THE GULF S OF THE FRONT...
GENERALLY CLEAR SKIES WITH LIGHT WINDS ARE OBSERVED S OF 24N.

CARIBBEAN SEA...
UPPER LEVEL TROUGHING IS ANCHORED OVER PORTIONS OF CENTRAL
AMERICA AND THE NW CARIBBEAN WITH MODERATE TO STRONG SUBSIDENCE
AND DRY AIR NOTED ON WATER VAPOR IMAGERY W OF 80W. THIS UPPER
LEVEL TROUGH EXTENDS AN AXIS FROM NICARAGUA NE ALONG 15N80W TO
NEAR PUERTO RICO WITH POSSIBLE ISOLATED SHOWERS OVER JAMAICA...
HISPANIOLA...PUERTO RICO AND ADJACENT COASTAL WATERS N OF 17N
BETWEEN 66W-80W. THE REMAINDER OF THE CARIBBEAN BASIN E OF THE
TROPICAL WAVE ALONG 73W...IS UNDER THE INFLUENCE OF AN UPPER
LEVEL RIDGE S OF 17N. MOIST SWLY UPPER LEVEL FLOW E OF 70W IS
DRAWING MIDDLE TO UPPER LEVEL TROPICAL MOISTURE OVER THE SE
CARIBBEAN. THIS MOISTURE AND INSTABILITY COUPLED WITH A SURFACE
TROUGH ALONG 60W E OF THE LESSER ANTILLES...IS GENERATING
SCATTERED SHOWERS AND ISOLATED TSTMS S OF 15N E OF 67W.

ATLANTIC OCEAN...
A BROAD UPPER LEVEL LONGWAVE TROUGH IS OVER THE ERN CONUS AND
DIPS OVER THE FLORIDA PENINSULA AS WELL AS PORTIONS OF THE FAR W
ATLC. THE ASSOCIATED SURFACE STATIONARY FRONT LIES ALONG 32N
FROM 70W TO A 1005 MB LOW CENTERED OVER SE GEORGIA. LOW-LEVEL
CONVERGENCE S OF THE FRONT AS WELL AS UPPER LEVEL DIFFLUENCE E
OF THE UPPER TROUGH AXIS IS GENERATING SCATTERED SHOWERS AND
TSTMS N OF 27N W OF 68W. FURTHER E...A BROAD UPPER LEVEL RIDGE
REMAINS OVER THE CENTRAL ATLC ANCHORED NEAR 24N58W EXTENDING A
RIDGE AXIS E-W ALONG 24N BETWEEN 45W TO 80W. A CENTRAL ATLC
UPPER LEVEL TROUGH REMAINS LARGELY NORTH OF THE REGION...BUT
EXTENDS A TROUGH AXIS ALONG 32N43W TO 30N50W. THIS UPPER LEVEL
TROUGH SUPPORTS A COLD FRONT THAT ENTERS THE REGION NEAR 32N39W
CONTINUING SSW ALONG 28N42W TO 26N49W. SCATTERED SHOWERS AND
POSSIBLE ISOLATED TSTMS ARE WITHIN 90 NM EITHER SIDE OF THE
FRONT. THE ERN ATLC IS DOMINATED BY UPPER LEVEL TROUGHING
ANCHORED ON AN UPPER LOW CENTERED NEAR 26N27W. A 1014 MB LOW IS
NEAR 27N30W WITH A SURFACE TROUGH ANALYZED FROM 28N26W TO 22N28W
WELL E OF THE SURFACE LOW. ISOLATED SHOWERS ARE WITHIN 30 NM OF
THE SURFACE TROUGH AND FROM 25N-29N BETWEEN 22W-26W.

$$
HUFFMAN




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