[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 240556
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT SUN JUL 24 2005

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHEASTERN SECTIONS
OF SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST FROM
THE EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED ON
SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND
METEOROLOGICAL ANALYSIS.

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0515 UTC.

...SPECIAL FEATURES...

TROPICAL DEPRESSION SEVEN IS UPGRADED TO TROPICAL STORM GERT AND
IS CENTERED NEAR 19.8N 94.7W AT 24/0600 UTC MOVING WNW AT 9 KT.
MAXIMUM SUSTAINED WIND SPEED IS 35 KT WITH GUSTS TO 45 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 1009 MB. SEE LATEST NHC
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT2/WTNT22 KNHC
AND THE PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS MIATCPAT2/WTNT32
KNHC FOR MORE DETAILS. NOAA RECONNAISSANCE AIRCRAFT FOUND A
WELL-DEFINED CIRCULATION WITH INCREASED WINDS. CONVECTION
ASSOCIATED WITH T.S. GERT HAS INCREASED OVER THE PAST FEW HOURS
WITH SCATTERED MODERATE/STRONG CONVECTION COVERING THE AREA OFF
THE COAST OF MEXICO WITHIN 90 NM OF LINE FROM 24N96W INTO THE W
BAY OF CAMPECHE ALONG 20N95W TO 19.5N92W. ALTHOUGH SOME
ORGANIZATION HAS OCCURRED IT IS UNLIKELY THAT GERT WILL MAKE
HURRICANE BEFORE LANDFALL ALONG THE CENTRAL MEXICAN COAST LATE
SUN NIGHT/MOD MORNING.

TROPICAL STORM FRANKLIN IS CENTERED NEAR 30.3N 72.9W AT 24/0300
UTC MOVING ENE AT 10 KT. MAXIMUM SUSTAINED WIND SPEED IS 55 KT
WITH GUSTS TO 65 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1003
MB. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS
MIATCMAT1/WTNT21 KNHC FOR MORE DETAILS. SATELLITE IMAGES
INDICATE THAT THE LOW AND MID LEVEL CENTERS ARE BECOMING
DETACHED WITH THE LOW LEVEL CENTER TO THE NE. SHEAR HAS
INCREASED FROM AN UPPER TROUGH MOVING INTO THE AREA...THUS
FRANKLIN IS NOT FORECAST TO STRENGTHEN BUT IN FACT HAS ALL READY
BEGUN TO WEAKEN. CONVECTION IS DISPLACED TO THE S WITH SCATTERED
MODERATE/STRONG CONVECTION WITHIN 75 NM OF LINE FROM CLOSE TO
CENTER NEAR 30N73W S ALONG 27N74W THEN NW TO 30N78W. THE
FORECAST TRACK TAKES FRANKLIN JUST N OF BERMUDA ON MON INTO TUE.

...TROPICAL WAVES...

FAR E ATLC TROPICAL WAVE IS ALONG 22W S OF 16N MOVING W 10-15
KT. BROAD MID LEVEL TURNING IS OBSERVED ON INFRARED SATELLITE
IMAGERY. CONVECTION IS CONFINED TO WITH THE ITCZ.

CENTRAL ATLC TROPICAL WAVE IS FROM 22N45W THROUGH A 1011 MB LOW
NEAR 11N48W TO 6N48W MOVING W 15-20 KT. WELL-DEFINED...
PERSISTENT BROAD CURVATURE IS OBSERVED ON INFRARED SATELLITE
IMAGERY. WAVE REMAINS EMBEDDED BROAD AREA OF AFRICAN DUST
COUPLED WITH DRY AIR ARE LIMITING DEEP CONVECTION.

CENTRAL CARIBBEAN TROPICAL WAVE IS ALONG 74W S OF 20N MOVING W
15-20 KT. WAVE WAS ADJUSTED DUE TO UPPER AIR DATA AND LOW LEVEL
CLOUD CURVATURE ON SATELLITE IMAGERY. THIS WAVE MARKS THE
LEADING EDGE OF THE AFRICAN DUST SURGE...BUT THE CONCENTRATIONS
APPEAR THINER AS IT MOVES ACROSS THE CARIBBEAN. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS OVER N COLOMBIA WITH
SCATTERED SHOWERS ALONG THE N COAST OF COLOMBIA AND WITHIN 60 NM
ALONG THE COAST OF HAITI.

SW CARIBBEAN TROPICAL WAVE IS ALONG 81W S OF 15N MOVING W 15-20
KT. THE WAVE CONTINUES TO HAVE A POOR SIGNATURE BUT IS STILL
TRIGGERING SCATTERED THUNDERSTORMS WITHIN 45 NM OF LINE 11N78W
13N81W TO THE COAST OF NICARAGUA NEAR 12N84W.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 16N16W 10N26W 10N37W 14N46W...THEN
ALONG 9N50W 11N58W 9N64W. SCATTERED MODERATE/STRONG CONVECTION
IS WITHIN 200 NM S OF THE AXIS FROM 28W-32W. CLUSTERS OF
SCATTERED MODERATE TO ISOLATED STRONG CONVECTION ARE ARE WITHIN
350 NM S OF THE AXIS E OF 33W TO THE COAST OF AFRICA. SCATTERED
MODERATE CONVECTION IS WELL S OF THE AXIS FROM 1N-7N BETWEEN
38W-43W.

...DISCUSSION...

GULF OF MEXICO...
MID/UPPER HIGH IS LOCATED OVER THE SW GULF NE OF T.D. SEVEN NEAR
21N92W WITH A RIDGE EXTENDING N ALONG THE COAST OF MEXICO TO
INLAND OVER TEXAS GIVING THE NW GULF CLEAR WEATHER. MID/UPPER
LOW OVER S FLORIDA NEAR 26N81W COVERING THE E GULF INTO THE W
ATLC. DIFFLUENCE OVER THE N GULF COAST IS GENERATING SCATTERED
THUNDERSTORMS N OF 27N E OF 89W WITH THE LARGEST AREA OVER THE
FLORIDA PANHANDLE NEAR PENSACOLA. AT THE SURFACE...A WEAK 1019
MB HIGH IS OVER THE NORTH CENTRAL GULF NEAR 18N89W. THE UPPER
HIGH IS STEERING T.D. SEVEN TOWARD CENTRAL MEXICO.

CARIBBEAN...
WATER VAPOR IMAGERY SHOWS VERY LITTLE DEEP MOISTURE OVER THE
CARIBBEAN AT THE MOMENT WITH ONLY SHOWERS/CONVECTION ASSOCIATED
WITH THE TROPICAL WAVES. DRY AIR WITH SUSPENDED AFRICAN DUST
MOVED INTO THE CENTRAL CARIBBEAN ESSENTIALLY PRECLUDING THE
DEVELOPMENT OF DEEP CONVECTION. THE DUST CAN PRODUCE HAZY SKIES
OVER THE AREA AS IT CONTINUES MARCHING WEST.

ATLANTIC...
MID/UPPER LOW IS OVER S FLORIDA NEAR 26N81W COVERING THE W ATLC
W OF 77W INTO THE GULF OF MEXICO. A MID/UPPER LEVEL HIGH IS
CENTERED S OF FRANKLIN 29N72W WITH RIDGE EXTENDING E TO 27N64W.
ANTICYCLONIC FLOW COVERS THE AREA N OF 21N FROM 64W-77W. THIS
HIGH/RIDGE BUTTS UP AGAINST THE NARROWING MID-OCEANIC TROUGH
WHICH LIES ALONG 30N47W TO A WEAK UPPER LOW NEAR 24N57W TO A
SECOND UPPER LOW N OF HISPANIOLA NEAR 20N69W. SURFACE TROUGH
LIES ALONG 31N56W TO 26N60W AND IS PRODUCING SCATTERED SHOWERS/
ISOLATED THUNDERSTORMS WITHIN 90/120 NM OF LINE 27N60W TO
32N51W...BUT THE NE SHEAR IS PROHIBITING ANY ORGANIZED ACTIVITY.
BROAD MID/UPPER LEVEL HIGH IS SITUATED E OF THE LESSER ANTILLES
NEAR 15N58W AND IS PRODUCING STRONG SUBSIDENCE OVER THE AREA AND
COUPLED WITH THE DRY AIR/AFRICAN DUST ESSENTIALLY HAVE CAPPED
THE ENVIRONMENT OVER THE TROPICAL ATLC TO THE CNTRL CARIBBEAN
MOSTLY SHOWER FREE. THE BACK END OF THE MOST CONCENTRATED DUST
IS NEAR 38W BUT ANOTHER AREA OF DUST HAS MOVED OFF AFRICA
LINGERING N OF THE CAPE VERDE ISLANDS. FARTHER S...DEEP EASTERLY
FLOW EXTENDS ACROSS THE E/CNTRL ATLC S OF 16N WITH JUST ENOUGH
UPPER DIFFLUENCE CENTERED OVER THE ITCZ TO SUPPORT CONVECTION E
OF 35W.

$$
WALLACE


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