[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 040557
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT SUN OCT 04 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0515 UTC.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 34W S OF 15N MOVING W NEAR 15 KT.
EMBEDDED WITHIN THE ITCZ...A BROAD SWATH OF DEEP LAYER MOISTURE
SURROUNDS THE WAVE FROM 5N-14N BETWEEN 32W-41W AS OBSERVED IN
THE TOTAL PRECIPITABLE WATER IMAGERY. LOW-LEVEL CYCLONIC TURNING
IS NOTED PRIMARILY W OF THE WAVE AXIS ON SATELLITE IMAGERY AND
IS ENHANCING SCATTERED STRONG CONVECTION FROM 9N-15N BETWEEN
33W-40W.

TROPICAL WAVE IS ALONG 51W S OF 15N MOVING W NEAR 15 KT. RATHER
WELL DEFINED ON SATELLITE IMAGERY...THIS WAVE EXHIBITS A MAXIMUM
IN 850 MB RELATIVE VORTICITY IN THE CIMSS WAVETRAK MODEL
GUIDANCE IN THE VICINITY OF THE WAVE AXIS NEAR 10N. CLUSTERS OF
SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE FROM 10N-16N
BETWEEN 46W-54W.

TROPICAL WAVE IS ALONG 75W S OF 19N MOVING W NEAR 10 KT. WEAK
CYCLONIC CURVATURE IS NOTED IN THE LOW-LEVEL CLOUD FIELD OVER
THE CENTRAL CARIBBEAN. THE WAVE ALSO LIES BENEATH UPPER LEVEL
TROUGHING BETWEEN 72W-78W. SCATTERED MODERATE CONVECTION IS FROM
12N-16N BETWEEN 70W-80W AND IS LIKELY ENHANCED BY THE UPPER
LEVEL TROUGH.


...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 8N13W 11N33W 10N36W 9N50W 9N52W
8N61W. ASIDE FROM THE CONVECTION ASSOCIATED WITH THE TROPICAL
WAVES...SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM
4N-10N BETWEEN 38W-49W.

...DISCUSSION...

GULF OF MEXICO...
A STATIONARY FRONT EXTENDS ACROSS ALONG THE NRN GULF COAST FROM
TALLAHASSEE TO NEW ORLEANS AND INTO SRN TEXAS NEAR GALVESTON.
MOSTLY SELY WINDS OF UP TO 15 KT ARE OBSERVED OVER MUCH OF THE
CENTRAL AND WRN GULF THIS EVENING. THIS MOIST LOW-LEVEL SLY FLOW
ALONG WITH LOW-LEVEL CONVERGENCE NEAR THE FRONTAL BOUNDARY IS
GENERATING SCATTERED SHOWERS AND ISOLATED TSTMS N OF 27N W OF
90W. THIS ACTIVITY IS BEING ENHANCED BY ANTICYCLONIC FLOW AND
UPPER LEVEL DIFFLUENCE FOUND ACROSS MUCH OF THE GULF AS AN UPPER
LEVEL HIGH IS CENTERED NEAR 21N98W. ELSEWHERE...THE GULF REMAINS
RATHER TRANQUIL AS THE NLY FLOW REGIME ALOFT KEEPS STABLE
ATMOSPHERIC CONDITIONS OVER THE GULF S OF 27N.

CARIBBEAN SEA...
AN UPPER LEVEL TROUGH COVERS THE CENTRAL CARIBBEAN FOCUSED ON AN
UPPER LOW CENTERED NEAR 16N75W. COMBINED WITH THE UPPER LEVEL
RIDGE LOCATED OVER THE GULF OF MEXICO...NLY WINDS ALOFT ARE
PROVIDING DRY STABLE AIR N OF 16N W OF 78W. THE UPPER LEVEL
TROUGHING COUPLED WITH THE TROPICAL WAVE ALONG 75W ARE
GENERATING CLUSTERS OF SCATTERED SHOWERS AND ISOLATED TSTMS S OF
16N BETWEEN 72W-82W. E OF THE UPPER LEVEL TROUGH...A LARGE AREA
OF MOIST SWLY FLOW AND UPPER LEVEL DIFFLUENCE ARE NOTED ON WATER
VAPOR IMAGERY WHICH IS GENERATING ISOLATED SHOWERS E OF 74W
COVERING MUCH OF THE ERN CARIBBEAN AND LESSER ANTILLES.

ATLANTIC OCEAN...
AN UPPER LEVEL TROUGH EXTENDS OVER THE W ATLC WATERS WITH AXIS
ALONG 74W. THIS TROUGHING EXTENDS SWD INTO THE CENTRAL CARIBBEAN
TROUGH ACROSS ERN CUBA...THE WINDWARD PASSAGE AND HISPANIOLA. E
OF THE UPPER LEVEL TROUGH AXIS...A LARGE AREA OF UPPER
DIFFLUENCE IS NOTED ON WATER VAPOR IMAGERY N OF 22N BETWEEN
64W-74W. ISOLATED SHOWERS ARE FOUND OVER THIS AREA...WITH
SCATTERED SHOWERS FOUND MAINLY N OF 27N BETWEEN 65W-74W WHERE
THE UPPER LEVEL FORCING IS STRONGEST. FARTHER TO THE E...A
WEAKNESS IN THE CENTRAL ATLC SUBTROPICAL RIDGE IS NOTED BY A
SURFACE TROUGH THAT EXTENDS FROM 30N50W TO 25N54W. SUPPORTED
ALOFT BY A SHORTWAVE UPPER LEVEL TROUGH...MOST OF THE SCATTERED
SHOWERS AND TSTMS BEING GENERATING ARE E OF THE SURFACE TROUGH
FROM 24N-29N BETWEEN 42W-49W. THE UPPER LEVEL TROUGH EXTENDS SW
FROM 24N50W TO E OF THE LESSER ANTILLES AND SUPPORTS ANOTHER
SURFACE TROUGH EXTENDING FROM 21N57W TO 14N59W. SCATTERED
SHOWERS ARE FOUND WITHIN 120 NM EITHER SIDE OF THE SURFACE
TROUGH. ELSEWHERE OVER THE REMAINDER OF THE ERN ATLC...UPPER
LEVEL ZONAL FLOW IS NOTED ON WATER VAPOR IMAGERY N OF 24N E OF
45W. EMBEDDED WITH THIS FLOW ALOFT IS A SURFACE TROUGH ANALYZED
FROM 31N22W TO 28N35W. CLUSTERS OF SCATTERED SHOWERS AND
ISOLATED TSTMS ARE OCCURRING WITHIN 90 NM EITHER SIDE OF THE
SURFACE TROUGH. THE TYPICAL E/W UPPER RIDGE DOMINATES MUCH OF
THE TROPICS WITH THE AXIS EXTENDING ALONG 15N TO 50W ENHANCING
THE CONVECTION ASSOCIATED WITH THE TROPICAL WAVES AND THE ITCZ.

$$
HUFFMAN





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