[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 271736
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT WED JUL 27 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...SPECIAL FEATURE...

TROPICAL STORM FRANKLIN CENTERED NEAR 33.4N 69.2W...OR ABOUT 230
NM WNW OF BERMUDA...AT 27/1500 UTC MOVING NNW 5 KT. ESTIMATED
MINIMUM CENTRAL PRESSURE IS 1003 MB. MAXIMUM SUSTAINED WIND
SPEED HAS INCREASED SLIGHTLY TO 40 KT GUSTS TO 50 KT. SEE THE
LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT1/
WTNT21 KNHC FOR MORE DETAILS. NORTHERLY SHEAR OVER FRANKLIN HAS
CAUSED ALL THE DEEP CONVECTION TO BE LOCATED OVER THE SRN
PERIPHERY OF THE STORM...ABOUT 45 NM S OF THE EXPOSED LOW-LEVEL
CENTER. THE SHEAR HAS SINCE SHIFTED TO EASTERLY AND NOW THE
TSTMS ARE CREEPING UP THE SW/W SIDE OF THE SYSTEM AND BECOMING
STRONGER WITH SCATTERED MODERATE CONVECTION FROM 30N-33N BETWEEN
68W-71W. THE TSTMS ARE LIKELY TO CONTINUE PROPAGATING UP THE W
SIDE OF THE SYSTEM AS THE SHEAR BECOMES SE THEN SW OVER THE NEXT
24-48 HRS.

...TROPICAL WAVES...

EAST ATLANTIC TROPICAL WAVE ALONG 31W S OF 19N MOVING W 15-20
KT. A WEAK PRIMARILY MID-LEVEL CIRCULATION IS NOTED IN VISIBLE
IMAGERY WITH WIDELY SCATTERED SHOWERS/TSTMS FROM 10N-15N BETWEEN
31W-36W.

CENTRAL ATLANTIC TROPICAL WAVE LOCATED 830 NM E OF THE LESSER
ANTILLES ALONG 46W/47W S OF 22N MOVING W 15-20 KT. A 1013 MB LOW
IS LOCATED ALONG THE AXIS NEAR 10N47W...EMBEDDED WITHIN THE
ITCZ. VISIBLE IMAGERY SHOWS A BATCH UP DRY AIR/AFRICAN DUST N
AND W OF THE WAVE...BUT MOISTURE HAS INCREASED IN SLY FLOW INTO
THE AREA IMMEDIATELY NEAR THE WAVE AXIS. DEEP CONVECTION HAS
FORMED OVER THE NRN PERIPHERY OF THE WAVE SINCE YESTERDAY WITH
WIDELY SCATTERED MODERATE NOW FROM 16N-20N BETWEEN 42W-50W.
WIDELY SCATTERED SHOWERS/TSTMS ALSO FROM 10N-13N BETWEEN
44W-48W.

WEST CARIBBEAN TROPICAL WAVE ALONG 80W S OF 16N MOVING W NEAR 20
KT. EXCEPT FOR WIDELY SCATTERED MODERATE CONVECTION EXTENDING
FROM SRN COSTA RICA TO THE PANAMA/COLOMBIA BORDER...THE WAVE IS
VIRTUALLY INDISTINGUISHABLE DUE TO THE BRISK ELY FLOW AND DRY
AIR.

TROPICAL WAVE OVER SOUTHERN MEXICO ALONG 96W S OF 20N MOVING W
10-15 KT. ISOLATED SHOWERS/TSTMS MOVED INLAND NEAR VERACRUZ THIS
MORNING BUT HAVE SINCE DISSIPATED.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 15N16W 11N26W 17N44W...THEN ALONG
10N47W 7N54W 11N64W. WIDELY SCATTERED MODERATE CONVECTION S OF
THE AXIS FROM 6N-12N BETWEEN 17W-26W. WIDELY SCATTERED MODERATE
WITHIN 200 NM N OF THE AXIS BETWEEN 50W-58W.

...DISCUSSION...

GULF OF MEXICO...
A SHARP UPPER TROF...OBSERVED IN WATER VAPOR IMAGERY AND UPPER
AIR DATA FROM BROWNSVILLE TX AND MONTERREY MEXICO...IS MOVING
INLAND ALONG THE RIO GRANDE VALLEY AND LEAVING MOSTLY E/NE UPPER
FLOW OVER THE GULF WATERS. A SFC RIDGE EXTENDS FROM W CUBA TO
THE LOUISIANA COAST AND THE ASSOCIATED ELY FLOW TO THE S IS
BRINGING DUST OVER THE S/CNTRL AND SW GULF. VISIBILITY HAS
DROPPED TO 3-4 MILES AT HAVANA CUBA AND GENERALLY NEAR 5-6 MILES
OVER THE YUCATAN PENINSULA. A WEAK 1015 MB LOW IS CENTERED VERY
NEAR FT. MYERS FLORIDA WITH A SFC TROF EXTENDING NW OVER THE
N/CNTRL GULF. THIS FEATURE IS PRODUCING ISOLATED SHOWERS/TSTMS N
OF 26N BETWEEN 85W-93W. A COLD FRONT OVER CNTRL TEXAS AND NRN
MEXICO WILL APPROACH THE NW GULF COAST TONIGHT AND WILL INCREASE
THE CHANCE OF WIDELY SCATTERED SHOWERS/TSTMS OVER THE N GULF
WATERS THROUGH THE WEEKEND.

CARIBBEAN...
DRY AIR AND HAZY SKIES ARE THE RULE OVER THE CARIBBEAN TODAY
WITH VERY LITTLE SIGNIFICANT WEATHER TO SPEAK OF. VISIBILITIES
HAVE IMPROVED OVER THE LESSER ANTILLES NOW THAT THE MAIN SURGE
OF AFRICAN DUST HAS MOVED TO THE W...BUT SEVERAL STATIONS FROM
THE N COAST OF COLOMBIA TO HISPANIOLA...THE CAYMAN ISLANDS...AND
CUBA ARE STILL REPORTING HAZE WITH VISIBILITY DOWN TO 4-6 MILES.
A BROAD UPPER LEVEL CYCLONIC CIRCULATION IS CENTERED OVER THE NW
CARIBBEAN AND IS PULLING A LITTLE INCREASED MOISTURE FROM THE
PACIFIC OVER CNTRL AMERICA...WITH IS SUPPORTING A FEW TSTMS FROM
NICARAGUA DOWN TO PANAMA. OTHERWISE...STRONG SUBSIDENCE IS OVER
THE E CARIBBEAN AND HAS MADE THE ENVIRONMENT UNFAVORABLE FOR
SHOWERS OR TSTMS. A TRPCL WAVE IS APPROACHING THE LESSER
ANTILLES BUT THE GFS SUGGESTS THAT THE DEEPEST MOISTURE WILL
MOVE TO THE N/NW AND POSSIBLY KEEP THE HEAVIEST RAINS AWAY FROM
THE ISLANDS FOR A FEW DAYS.

WEST/CENTRAL ATLANTIC...
T.S. FRANKLIN IS N OF THE AREA BUT NLY SHEAR CONTINUES TO
DISPLACE THE ASSOCIATED CONVECTION TO THE S OF THE CENTER WITH
SCATTERED MODERATE FROM 30N-33N BETWEEN 68W-71W. A SFC TROF
EXTENDS AWAY FROM FRANKLIN ALONG 30N67W TO A 1015 MB LOW NEAR
27N73W THEN ACROSS THE N BAHAMAS TO S FLORIDA. SCATTERED TSTMS
ARE LOCATED NEAR THE LOW FROM 23N-26N BETWEEN 73W-77W SPREADING
OVER ELEUTHERA...CAT...AND GREAT EXUMA ISLANDS. THIS ACTIVITY IS
BEING ENHANCED BY AN UPPER LOW CENTERED N OF THE TURKS AND
CAICOS NEAR 24N72W. AN UPPER HIGH TO THE SE OF FRANKLIN IS
SPREADING MOISTURE S/SWWD TOWARDS THE NRN LEEWARD ISLANDS AND
THIS IS TRIGGERING SCATTERED TSTMS FROM 17N-23N BETWEEN 57W-66W
(NEAR A SFC TROF WHICH EXTENDS FROM THE VIRGIN ISLANDS NE TO
22N60W). OTHER WIDELY SCATTERED MODERATE CONVECTION IS LOCATED
FARTHER N FROM 26N-31N BETWEEN 59W-66W.

EAST ATLANTIC...
A STATIONARY UPPER LEVEL TROF LIES ALONG 30N50W 24N53W AND IS
SUPPORTING WIDELY SCATTERED SHOWERS/TSTMS FROM 29N-31N BETWEEN
49W-55W. A 1027 MB HIGH IS CENTERED NEAR 29N44W WITH THE
SUBTROPICAL RIDGE CONTINUING EWD TO JUST S OF THE CANARY
ISLANDS. AN UPPER HIGH IS CENTERED FARTHER S NEAR 17N36W WITH
RIDGE EXTENDING NW TO 30N44W...AND THIS IS KEEPING THE DEEPEST
ELY FLOW S OF ABOUT 16N. THE TRPCL WAVE LOCATED NEAR 47W IS A
RATHER DEEP FEATURE...HIGHLIGHTED BY THE INVERTED TROF NOTED IN
THE UPPER LEVELS ALONG 50W. FARTHER E...A BROAD LONGWAVE TROF
HAS DROPPED INTO THE AREA N OF 26N E OF 30W WITH A DISSIPATING
COLD FRONT EASING ACROSS THE CANARY ISLANDS...BUT GOING
VIRTUALLY UNNOTICED.

$$
BERG



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