[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 221058
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT FRI JUL 22 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1015 UTC.

...SPECIAL FEATURE...

TROPICAL STORM FRANKLIN IS CENTERED NEAR 26.7N 77.3W OVER THE N
PORTION OF GREAT ABACO ISLAND...OR ABOUT 83 NM NE OF FREEPORT ON
GREAT BAHAMA ISLAND...AT 22/0900 UTC MOVING NW AT 10 KT. MAXIMUM
SUSTAINED WIND SPEED IS 40 KT WITH GUSTS TO 50 KT. ESTIMATED
MINIMUM CENTRAL PRESSURE IS 1009 MB. SEE LATEST NHC FORECAST/
ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT1/WTNT21 KNHC AND THE
PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS MIATCPAT1/WTNT31 KNHC
FOR MORE DETAILS. FRANKLIN REMAINS A RELATIVELY SMALL SYSTEM
WITH A SOMEWHAT RAGGED APPEARANCE ON SATELLITE IMAGERY.
SCATTERED MODERATE TO SCATTERED STRONG CONVECTION COVERS THE
AREA FROM 23N-28N BETWEEN 74.5W-78.5W BUT DOES NOT INCLUDE
ANDROS ISLAND. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS DOT THE
REMAINDER OF THE THE BAHAMA ISLAND CHAIN AND W TO THE COAST OF
FLORIDA.

...TROPICAL WAVES...

E ATLC TROPICAL WAVE IS FROM 25N32W 16N36W TO 9N36W MOVING W
15-20 KT. THE BROAD LOW HAS NOW DISSIPATED. WAVE REMAINS
EMBEDDED WITHIN A LARGE AREA OF SAHARAN DUST THAT COVERS THE
ATLC WATERS S OF 26N FROM 27W-58W. THIS AND THE ASSOCIATED DRY
AIR HAS SQUELCHED ANY CONVECTION NEAR THE WAVE EXCEPT SE OF THE
ITCZ AXIS.

CENTRAL ATLC TROPICAL WAVE IS FROM 22N53W 13N58W 6N59W MOVING W
15-20 KT. THE CLASSIC INVERTED-V SIGNATURE CONTINUES TO BE
MAINTAINED WITH THIS WAVE AND IS ALONG THE LEADING EDGE OF THE
STRONG DUST SURGE TO THE E. SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS ARE W OF THE WAVE AXIS WITHIN 90/120 NM OF LINE
20N55W TO OVER THE WINDWARD ISLANDS NEAR 13N61W. WIDESPREAD DEEP
CONVECTION IS NOT EXPECTED TO AFFECT THE LESSER ANTILLES AS THE
WAVE PASSES LATER TODAY.

WEAK TROPICAL WAVE OVER THE S CARIBBEAN ALONG 71W S OF 14N
MOVING W 10 KT. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE
MOVING TOWARD THE ABC ISLANDS S OF 13N TO THE WINDWARD ISLANDS.

STRONG W CARIBBEAN TROPICAL WAVE EXTENDS FROM W CUBA NEAR 23N83W
INLAND OVER CENTRAL HONDURAS/W NICARAGUA NEAR 15N86W INTO THE E
PACIFIC REGION MOVING W NEAR 20 KT. WAVE IS BENEATH A MID/UPPER
LEVEL HIGH CENTERED OVER W CUBA. DIFFLUENCE ASSOCIATED WITH THE
UPPER HIGH IS GENERATING SCATTERED STRONG CONVECTION COVERING
THE GULF OF HONDURAS S OF 19N TO THE HONDURAN COASTLINE.
CLUSTERS OF SCATTERED MODERATE/STRONG CONVECTION ARE WITHIN
60/75 NM OF LINE FROM THE COAST OF COLOMBIA AND OVER PANAMA NEAR
8N77W 11N82W TO 17N84W. ALL OF THE ABOVE CONVECTION IS BEING
DRAWN NW AROUND AN UPPER LEVEL LOW JUST N OF THE BAY OF CAMPECHE
IN THE S GULF OF MEXICO.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 11N15W 15N28W 9N46W 11N62W.
SCATTERED MODERATE/STRONG CONVECTION IS WITHIN 75 NM OF LINE
12N28W-8N36W. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG
CONVECTION ARE FROM 7N-10N BETWEEN 24W-31W AND WITHIN 120 NM OF
THE AXIS FROM 44W-55W. CLUSTERS OF SCATTERED MODERATE CONVECTION
ARE WITHIN 90 NM ALONG THE COAST OF AFRICA FROM 6N-11N.

...DISCUSSION...

GULF OF MEXICO...
SHARP MID/UPPER TROUGH EXTENDS FROM NE FLORIDA SW TO AN UPPER
LOW OVER THE BAY OF CAMPECHE NEAR 20N94W TO OVER S MEXICO. THIS
IS DRAWING SCATTERED THUNDERSTORMS THAT ARE DEVELOPING IN THE NW
GULF N THROUGH THE YUCATAN CHANNEL. AN UPPER HIGH OVER W CUBA IS
ADVECTING TROPICAL MOISTURE N OVER THE SE GULF WITH ACCOMPANYING
SCATTERED SHOWERS/THUNDERSTORMS INTO THE STRAITS OF FLORIDA. THE
REMAINDER OF THE GULF IS MOSTLY CLOUD AND SHOWER FREE. THIS
SITUATION IS BEGINNING TO CHANGE FOR THE WEEKEND AS THE TROPICAL
WAVE IN THE W CARIBBEAN MOVES ACROSS THE YUCATAN AND THE S GULF
ON TODAY AND SAT.

CARIBBEAN...
SEE TROPICAL WAVES FOR THE LARGE AREA OF CONVECTION OVER THE W
CARIBBEAN. ELSEWHERE...NE UPPER LEVEL FLOW OVER THE E CARIBBEAN
IS ADVECTING STRONG SUBSIDENCE OVER THE AREA TO E OF THE LESSER
ANTILLES AND IS PRODUCING PLEASANT WEATHER E OF 78W EXCEPT THE
SHOWERS/THUNDERSTORMS MOVING ACROSS THE LESSER ANTILLES
ASSOCIATED WITH THE TROPICAL WAVE JUST TO THE E.

ATLANTIC...
TROPICAL STORM FRANKLIN IS THE PRIMARY FOCUS FOR THE ATLC WATERS
THIS MORNING. THE N BAHAMAS ARE OVERLAID BY A RATHER SMALL UPPER
LEVEL HIGH NEAR FRANKLIN WITH A RIDGE EXTENDING NE TO A SECOND
UPPER HIGH NEAR 32N69W WHICH IS KEEPING MOST OF THE CLOUDINESS
CONFINED TO W OF 70W. UPPER LEVEL MID-OCEANIC TROUGH SNAKES
ACROSS THE AREA FROM A DEEP LAYERED LOW N OF THE REGION THROUGH
32N40W TO A MID/UPPER LEVEL LOW NEAR 24N57W TO 20N68W AND IS
PRODUCING ENOUGH SUBSIDENCE OVER THE AREA TO KEEP THE REGION E
OF 70W MAINLY CLEAR. A FEW MID/HIGH CLOUDS WITH SCATTERED
SHOWERS ARE SKIRTING THE AREA N OF 27N BETWEEN 57W-64W AS A
SHORTWAVE MOVES QUICKLY E ACROSS THE NW ATLC. WIDESPREAD DUST
COVERS A GOOD PORTION OF THE ATLC...ESSENTIALLY EVERYWHERE N OF
THE ITCZ TO 27N FROM W OF THE CAPE VERDE ISLANDS NEAR 27W TO
58W. A STRONG UPPER LEVEL HIGH IS CENTERED NW OF THE CAPE VERDE
ISLANDS NEAR 22N36W AND IS CAPPING THE ENVIRONMENT TO KEEP THE
DUST TRAPPED IN THE LOW/MID LEVELS. AT THE SURFACE...SUBTROPICAL
RIDGE REMAINS ANCHORED OVER THE ATLC EXTENDING FROM A 1028 MB
HIGH IN THE NE ATLC THROUGH 32N37W SW TO A 1021 MB HIGH IN THE
CENTRAL/WESTERN ATLC NEAR 26N59W TO 25N68W.

$$
WALLACE



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