[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 242351
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT MON AUG 24 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...SPECIAL FEATURES...

TROPICAL WAVE EXTENDS FROM 10N57W ALONG 18N58W TO 24N61W MOVING
W NEAR 20 KT. THIS TROPICAL WAVE CONTINUES TO INTERACT WITH AN
NORTH-SOUTH ELONGATED UPPER LEVEL LOW CENTERED NEAR 25N65W THAT
STRETCHES UPPER LEVEL TROUGHING SWD ACROSS THE NE CARIBBEAN SEA.
DEEP LAYER MOISTURE COINCIDES WITH THE WAVE AXIS AND PAIRED WITH
MOIST S-SW UPPER LEVEL FLOW AND UPPER DIFFLUENCE LOCATED EAST OF
THE TROUGH AXIS IS GENERATING SCATTERED MODERATE/ISOLATED STRONG
CONVECTION FROM 16N-24N BETWEEN 55W-63W.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 30W S OF 20N MOVING W NEAR 15 KT.
SATELLITE IMAGERY DEPICTS AN INVERTED-V CLOUD SIGNATURE AND THE
CIMSS WAVETRAK GUIDANCE INDICATES LOW TO MIDDLE LEVEL CYCLONIC
FLOW IN THE VICINITY OF THE WAVE AXIS. THIS WAVE ALSO COINCIDES
WITH A DEEP LAYER MOISTURE MAXIMUM OBSERVED IN THE TOTAL
PRECIPITABLE WATER IMAGERY. SCATTERED SHOWERS ARE NOTED COVERING
THE AREA FROM 10N-21N BETWEEN 26W-34W.

TROPICAL WAVE IS ALONG 78W S OF 17N MOVING W NEAR 18 KT. THIS
WAVE HAS BEEN REPOSITIONED A FEW DEGREES WEST FROM THE PREVIOUS
ANALYSIS AND BETTER COINCIDES WITH A DEEP LAYER MOISTURE MAXIMUM
OBSERVED IN THE TOTAL PRECIPITABLE WATER IMAGERY ACROSS THE SW
CARIBBEAN. THE CIMSS WAVETRAK GUIDANCE INDICATES A BROAD AREA OF
LOW PRESSURE AND ASSOCIATED LOW TO MIDDLE LEVEL ATMOSPHERIC
INSTABILITY AND LIFT WHICH IS GENERATING SCATTERED MODERATE/
ISOLATED STRONG CONVECTION MOVING W LOCATED FROM 8N-16N BETWEEN
78W-85W.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 10N14W 16N27W 14N32W 7N47W
11N56W 11N59W 9N65W. CLUSTERS OF SCATTERED MODERATE/ISOLATED
STRONG CONVECTION ARE ALONG THE W AFRICA COAST FROM 11N-15N
BETWEEN 13W-19W. A SMALLER AREA OF SCATTERED MODERATE CONVECTION
IS OVER THE NRN CAPE VERDE ISLANDS FROM 16N-18N BETWEEN 22W-26W.
ELSEWHERE...SCATTERED SHOWERS ARE WITHIN 120 NM EITHER SIDE OF
THE AXIS BETWEEN 34W-42W LOCATED SE OF THE TROPICAL WAVE ALONG
30W.

...DISCUSSION...

GULF OF MEXICO...
AS OF 2100 UTC...A STATIONARY FRONT IS OVER THE CENTRAL FLORIDA
PENINSULA FROM ORLANDO TO NEAR SARASOTA CONTINUING SW INTO THE
SE GULF ALONG 25N85W 23N90W TO 24N95W. THIS FRONTAL BOUNDARY IS
SUPPORTED BY AN UPPER LEVEL TROUGH ACROSS THE SE CONUS WITH AXIS
EXTENDING FROM CENTRAL ALABAMA TO 26N97W IN THE NW GULF.
SCATTERED SHOWERS AND ISOLATED TSTMS ARE OCCURRING OVER THE SRN
FLORIDA PENINSULA AND ALSO WITHIN 60 NM OF THE STATIONARY FRONT
TO 90W. A MORE WIDESPREAD AREA OF SIMILAR CONVECTION IS S OF 24N
W OF 92W OVER THE SW GULF AND WRN BAY OF CAMPECHE. THIS AREA IS
FURTHER AIDED BY AN UPPER LEVEL RIDGE AXIS PROVIDING UPPER LEVEL
DIFFLUENCE OVER THE YUCATAN PENINSULA AND BAY OF CAMPECHE. NORTH
OF THE FRONTAL BOUNDARY...A MUCH DRIER AIRMASS IS IN PLACE
ACROSS THE NRN GULF WHICH IS PROMOTING SUBSIDENCE...SINKING AIR
AND MOSTLY FAIR WEATHER CONDITIONS.

CARIBBEAN SEA...
A BROAD UPPER LEVEL RIDGE DOMINATES THE CARIBBEAN W OF 71W WITH
THE ANTICYCLONIC CIRCULATION CENTERED S OF CENTRAL CUBA NEAR
20N79W. UPPER LEVEL DIFFLUENCE ON MOIST SWLY FLOW ALOFT BETWEEN
THIS RIDGE AND THE UPPER LEVEL TROUGHING OVER THE WRN GULF OF
MEXICO IS SUPPORTING SCATTERED SHOWERS AND TSTMS ACROSS THE
YUCATAN PENINSULA AND PORTIONS OF WRN CUBA. ON THE SRN PERIPHERY
OF THE UPPER LEVEL RIDGE...UPPER LEVEL DIFFLUENCE IS ENHANCING
THE CONVECTION ASSOCIATED WITH THE TROPICAL WAVE OVER THE SW
CARIBBEAN ALONG 78W. AS THE TROPICAL WAVE CONTINUES TRACKING
WWD...EXPECT INCREASED SHOWER AND TSTM ACTIVITY OVER CENTRAL
AMERICA DURING THE NEXT 24-36 HOURS. CURRENTLY THIS ACTIVITY IS
FOUND S OF 16N W OF 78W INCLUDING PORTIONS OF PANAMA...COSTA
RICA AND NICARAGUA. FARTHER TO THE E...UPPER LEVEL TROUGHING
EXTENDS FROM THE CENTRAL ATLC OVER THE NE CARIBBEAN. MOIST SWLY
FLOW ALOFT ALONG WITH THE APPROACHING TROPICAL WAVE
APPROXIMATELY 200 NM E OF THE LESSER ANTILLES IS GENERATING
SCATTERED SHOWERS AND ISOLATED TSTMS NE OF A LINE FROM SAINT
LUCIA TO SW HISPANIOLA.

ATLANTIC OCEAN...
A STATIONARY FRONT EXTENDS OVER THE SW NORTH ATLC TO NEAR
TITUSVILLE FLORIDA AND ACROSS THE CENTRAL FLORIDA PENINSULA INTO
THE GULF OF MEXICO. A PRE-FRONTAL TROUGH IS ANALYZED FROM 31N78W
TO 25N83W. SCATTERED SHOWERS AND ISOLATED TSTMS ACCOMPANY THIS
FRONTAL BOUNDARY AND ARE WITHIN 150 NM E OF THE FRONT...
INCLUDING A PORTION OF THE SE FLORIDA PENINSULA AND FLORIDA
KEYS. THIS ACTIVITY IS PRIMARILY SUPPORTED ALOFT BY AN UPPER
LEVEL TROUGH ACROSS THE SE CONUS AND THE ASSOCIATED UPPER LEVEL
DIFFLUENCE LOCATED E OF THE TROUGH AXIS TO 74W. FARTHER TO THE E
OVER THE REMAINDER OF THE SW NORTH ATLC AND INTO THE CENTRAL
ATLC...A TROPICAL WAVE IS POSITIONED FROM 10N57W TO 24N61W WITH
AN UPPER LEVEL LOW LOCATED NW OF THE WAVE AXIS NEAR 25N65W.
THESE TWO FEATURES ARE INTERACTING AND ENHANCING A LARGE AREA OF
RATHER UNORGANIZED CONVECTION FROM 16N-24N BETWEEN 55W-63W. THE
REMAINDER OF THE CENTRAL AND ERN ATLC IS DOMINATED BY A SURFACE
RIDGE ANCHORED BY A 1026 MB HIGH CENTERED NEAR 34N52W. THIS
SURFACE RIDGE IS PROVIDING THE BASIN E OF 50W WITH NE TRADES OF
UP TO 25 KT.

$$
HUFFMAN



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