[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 121728
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT WED AUG 12 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.

...SPECIAL FEATURES...
TROPICAL DEPRESSION TWO IS CENTERED NEAR 14.3N 33.8W OR ABOUT
630 MILES...1015 KM...WEST OF THE SOUTHERNMOST CAPE VERDE
ISLANDS AT 12/1500 UTC MOVING W AT 11 KT. ESTIMATED MINIMUM
CENTRAL PRESSURE IS 1006 MB. MAXIMUM SUSTAINED WIND SPEED IS 30
KT WITH GUSTS TO 40 KT. SEE LATEST NHC FORECAST ADVISORY UNDER
AWIPS/WMO HEADERS MIATCMAT2/WTNT22 FOR MORE DETAILS. CONVECTION
REMAINS TO THE W OF THE LOW LEVEL CENTER WITH LIGHT TO MODERATE
SOUTHEASTERLY SHEAR EXPECTED FOR THE NEXT SEVERAL DAYS.
SCATTERED MODERATE/ STRONG CONVECTION IS FROM 12N-15N BETWEEN
34W-37W.

...TROPICAL WAVES...
TROPICAL WAVE IS INTRODUCED ALONG 18W S OF 17N MOVING W AT 15 KT.
SATELLITE IMAGERY AND SSMI TOTAL PRECIPITABLE WATER IMAGERY
SHOWED A WELL DEFINED WAVE OFF THE COAST OF WEST AFRICA. UPPER
AIR SOUNDINGS FROM DAKAR SENEGAL ALSO DEPICTED WAVE PASSAGE.
WIDELY SCATTERED MODERATE CONVECTION IS FROM 6N-16N BETWEEN
15W-25W.

TROPICAL WAVE IS ALONG 58W S OF 20N MOVING W 15 KT. THE WAVE IS
HAS A WELL DEFINED INVERTED-V LOW LEVEL CLOUD SIGNATURE WITH
EMBEDDED SHOWERS AND THUNDERSTORMS. AN SSMI TOTAL PRECIPITABLE
WATER MAXIMUM IS ALSO NOTED. WIDELY SCATTERED MODERATE
CONVECTION IS FROM 11N-22N BETWEEN 57W-63W.

TROPICAL WAVE IS FROM ALONG 67W S OF 21N MOVING W NEAR 12 KT. A
BAND OF DRY AIR HAS WRAPPED AROUND THE W SIDE OF THIS WAVE
INHIBITING CONVECTION W OF THE WAVE AXIS. WIDELY SCATTERED
SHOWERS ARE HOWEVER E OF THE WAVE AXIS FROM 8N-22N BETWEEN
63W-67W. SCATTERED MODERATE CONVECTION IS FROM 11N-13N BETWEEN
65W-66W.

TROPICAL WAVE IS ALONG 84W S OF 21N MOVING W 15-20 KT. THE WAVE
IS HAS A WELL DEFINED INVERTED-V LOW LEVEL CLOUD SIGNATURE WITH
EMBEDDED SHOWERS AND THUNDERSTORMS. AN SSMI TOTAL PRECIPITABLE
WATER MAXIMUM IS ALSO NOTED. WIDELY SCATTERED MODERATE
CONVECTION IS ALONG THE COAST OF NICARAGUA FROM 11N-14N BETWEEN
82W-85W. SIMILAR CONVECTION IS OVER THE NW CARIBBEAN FROM
16N-20N BETWEEN 82W-90W.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 12N16W 11N24W 14N31W 11N43W
13N56W 13N67W. BESIDES THE CONVECTION THAT WAS MENTIONED IN THE
SPECIAL FEATURES AND TROPICAL WAVE SECTIONS...SCATTERED
SHOWERS ARE FROM 7N-13N BETWEEN 40W-47W.

...DISCUSSION...

GULF OF MEXICO...
AS OF 1500 UTC...A SURFACE TROUGH IS OVER THE E GULF FROM THE
FLORIDA PANHANDLE AT 31N84W TO THE NW GULF AT 26N93W. SCATTERED
MODERATE TO ISOLATED STRONG CONVECTION IS FROM 27N-29N BETWEEN
88W-93W. 15 MINUTE LIGHTNING DATA SHOWS FREQUENT LIGHTNING S OF
LOUISIANA. ISOLATED SHOWERS ARE ALSO OVER THE N GULF N OF 25N.
HIGH PRES RIDGING IS OVER THE S GULF WITH AXIS ALONG 25N.
OUTSIDE AREAS OF CONVECTION SURFACE WINDS ARE LIGHT TO VARIABLE
ACROSS THE GULF. IN THE UPPER LEVELS...AN UPPER LEVEL TROUGH IS
OVER THE N GULF N OF 25N. AN EMBEDDED UPPER LEVEL LOW IS OVER
THE NE GULF CENTERED NEAR 26N87W. ANOTHER UPPER LEVEL LOW IS
OVER S MEXICO CENTERED AT 18N98W. SIGNIFICANT UPPER LEVEL
MOISTURE COVERS THE ENTIRE AREA. EXPECT...THE SURFACE TROUGH TO
MOVE E OVER THE NEXT 24 HOURS WITH CONTINUED CONVECTION. ALSO
EXPECT MORE SHOWERS AND THUNDERSTORMS OVER THE N GULF N OF 25N.

CARIBBEAN SEA...
THREE TROPICAL WAVES ARE AFFECTING THE CARIBBEAN SEA AND CENTRAL
AMERICA. SEE ABOVE. MODERATE TRADEWINDS ARE OVER THE AREA. IN
ADDITION...A 1008 MB LOW IS OVER E PANAMA NEAR 8N77W. SCATTERED
SHOWERS ARE NOTED ON RADAR OVER PUERTO RICO AND HISPANIOLA.
SIMILAR SHOWERS ARE OVER JAMAICA FROM 16N-19N BETWEEN 75W-80W.
IN THE UPPER LEVELS...AN UPPER LEVEL HIGH IS OVER THE W
CARIBBEAN NEAR 16N83W. AN UPPER LEVEL LOW IS N OF THE LEEWARD
ISLANDS NEAR 23N61W. STRONG SUBSIDENCE IS OVER THE CENTRAL
CARIBBEAN BETWEEN 70W-80W. EXPECT SHOWERS AND ISOLATED
THUNDERSTORMS OVER THE CARIBBEAN DUE TO THE TROPICAL WAVES OVER
THE NEXT 24 HOURS.

ATLANTIC OCEAN...
A HIGH PRES RIDGE AXIS OVER THE CENTRAL AND W ATLANTIC EXTENDS
FROM 30N45W TO 25N80W. A 1029 MB HIGH IS CENTERED NEAR THE
AZORES AT 42N25W. A RIDGE AXIS EXTENDS SW TO THE CENTRAL
ATLANTIC NEAR 30N45W. IN THE UPPER LEVELS...AN UPPER LEVEL RIDGE
IS OVER THE W ATLANTIC N OF 20N AND W OF 55W. AN UPPER LEVEL
TROUGH IS OVER THE CENTRAL AND E ATLANTIC N OF 22N BETWEEN
25W-55W. A LARGE UPPER LEVEL HIGH IS CENTERED OVER THE TROPICAL
ATLANTIC NEAR 16N47W. EXPECT THE TROPICAL WAVES AND SPECIAL
FEATURES TO BE THE DOMINATE FEATURES OVER THE NEXT 24 HOURS.

$$
MRF/RFB





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