[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 132313
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT MON JUL 13 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.

...TROPICAL WAVES...

A TROPICAL WAVE IS ALONG 29W S OF 16N MOVING W NEAR 15 KT. A
BROAD AREA OF LOW-LEVEL CYCLONIC TURNING IS APPARENT ON
SATELLITE IMAGERY. THE WAVE ALSO COINCIDES WITH A LOW
AMPLITUDE DEEP LAYER MOISTURE MAXIMUM OBSERVED ON TOTAL
PRECIPITABLE WATER IMAGERY. CONVECTION IS MAINLY CONFINED TO THE
ITCZ. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION
ARE FROM 8N-12N BETWEEN 25W-35W.

A TROPICAL WAVE IS E OF THE LESSER ANTILLES EXTENDING FROM
18N55W TO 5N49W MOVING W 15-20 KT. THIS WAVE HAS BECOME
INCREASINGLY TILTED NW-SE BY THE NE WIND SURGE E OF THE AXIS
OVER THE N PORTIONS OF THE WAVE AXIS. A WELL DEFINED INVERTED V
PATTERN IS EVIDENT IN THE LOW-LEVEL CLOUDS SEEN ON SATELLITE
IMAGERY. THE WAVE ALSO COINCIDES WITH A WELL AMPLIFIED MOISTURE
MAXIMUM OBSERVED ON TOTAL PRECIPITABLE WATER IMAGERY. SCATTERED
SHOWERS/POSSIBLE THUNDERSTORMS ARE ALONG THE WAVE AXIS FROM
7N-17N BETWEEN 48W-56W. THIS SHOWER ACTIVITY IS BEING ENHANCED
BY UPPER LEVEL DIFFLUENCE NEAR A SHORTWAVE UPPER LEVEL TROUGH.
GFS APPEARS TO HAVE A GOOD HANDLE ON THIS FEATURE AND SHOWS IT
MOVING INTO THE LESSER ANTILLES TOMORROW WITH THE N PART LIKELY
FRACTURING.

A TROPICAL WAVE IS ALONG 90W MOVING W NEAR 15 KT. THE WAVE
POSITION IS MAINLY BASED ON A MOISTURE MAXIMUM IN TOTAL
PRECIPITABLE WATER AS LITTLE SIGNATURE IS APPARENT IN SATELLITE
IMAGERY OR OBSERVATIONS. CLUSTERS OF SCATTERED MODERATE
CONVECTION ARE OVER THE YUCATAN PENINSULA FROM 18N-21N BETWEEN
88W-92W...AND OVER SOUTHERN GUATEMALA FROM 13N-16N BETWEEN
90W-93W.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 13N16W 10N23W 11N29W 8N35W 9N50W
TO THE S AMERICA COAST NEAR 6N58W. BESIDES THE CONVECTION
MENTIONED IN THE TROPICAL WAVE SECTION...SCATTERED MODERATE TO
ISOLATED STRONG CONVECTION IS FROM 10N-15N BETWEEN 16W-20W.
SCATTERED MODERATE CONVECTION IS FROM 7N-9N BETWEEN 37W-41W.

...DISCUSSION...

GULF OF MEXICO...
A 1018 MB HIGH IS OVER THE CENTRAL GULF OF MEXICO NEAR 27N88W. A
RIDGE AXIS CONTINUES W TO THE S TEXAS COAST NEAR 27N97W.
SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS INLAND FROM
N FLORIDA TO LOUISIANA N OF 29. ISOLATED MODERATE CONVECTION IS
ALSO OVER THE SOUTHERN BAY OF CAMPECHE S OF 19N. MOST OF THE
REMAINDER OF THE GULF HAS FAIR TO PARTLY CLOUDY SKIES WITH 5-10
KT ANTICYCLONIC WINDS. IN THE UPPER LEVELS...A LARGE HIGH IS
CENTERED OVER E TEXAS PRODUCING PREDOMINATELY N AND E UPPER
LEVEL FLOW OVER THE GULF. AN UPPER LEVEL LOW IS ALSO CENTERED
OVER S MEXICO NEAR 21N105W MOVING W. STRONG SUBSIDENCE IS NOTED
OVER TEXAS AND THE CENTRAL GULF FROM 23N-27N. UPPER LEVEL
MOISTURE IS OVER THE NE GULF...THE YUCATAN PENINSULA... AND THE
BAY OF CAMPECHE. EXPECT...CONTINUED CONVECTION OVER THE NE GULF
AND THE BAY OF CAMPECHE OVER THE NEXT 24 HOURS.

CARIBBEAN SEA...
A TROPICAL WAVE OVER CENTRAL AMERICA IS THE MAIN WEATHER FEATURE
IN THE REGION. SEE ABOVE. STRONG TRADEWINDS TOGETHER WITH UPPER
LEVEL DIFFLUENCE FROM AN UPPER LEVEL LOW CENTERED OVER THE
SOUTHERN BAHAMAS IS PRODUCING SCATTERED MODERATE CONVECTION OVER
THE HIGHER ELEVATIONS OF HISPANIOLA...JAMAICA...AND CUBA. IN THE
UPPER LEVELS...ZONAL FLOW PREVAILS. EXPECT...THE TROPICAL WAVE
TO MOVE W OF CENTRAL AMERICA OVER THE NEXT 24 HOURS. EXPECT
HOWEVER...FOR MORE CONVECTION OVER CUBA...AND ADDITIONAL
CONVECTION OVER THE SW CARIBBEAN.

ATLANTIC OCEAN...
A SURFACE TROUGH IS OVER THE W ATLANTIC N OF PUERTO RICO ALONG
28N64W 18N67W. SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ARE
WITHIN 90 NM OF THE TROUGH AXIS. A DISSIPATING COLD FRONT IS
OVER THE CENTRAL ATLANTIC ALONG 31N32W 27N36W 26N40W. SCATTERED
SHOWERS ARE WITHIN 30 NM E OF FRONT. IN THE UPPER LEVELS...AN
UPPER LEVEL LOW IS CENTERED OVER THE S BAHAMAS NEAR 24N72W.
ANOTHER UPPER LEVEL LOW IS OVER THE CENTRAL ATLANTIC NEAR
25N55W. AN UPPER LEVEL HIGH IS OVER THE E ATLANTIC NEAR 26N32W.
EXPECT... CONVECTION OVER THE NEXT 24 HOURS WITH THE ATLANTIC
TROPICAL WAVES...AND SURFACE TROUGH.

$$
FORMOSA





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