[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 251052
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT MON JUL 25 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 FEATURES...

TROPICAL STORM GERT WAS DOWNGRADED TO TROPICAL DEPRESSION AT
25/0900 UTC AND IS CENTERED NEAR 22.4N 99.1W AT 25/0900 UTC
MOVING W AT 10 KT. MAXIMUM SUSTAINED WIND SPEED IS 30 KT WITH
GUSTS TO 40 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1007 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. CONVECTION IS
MOSTLY OVER THE SIERRA MADRE MOUNTAINS WITH A BAND OVER
SCATTERED MODERATE/STRONG CONVECTION WITHIN 45 NM OF LINE FROM
21N95W TO INLAND OVER MEXICO NEAR 23.5N98W. HEAVY RAINS WILL
CONTINUE OVER THE AREA FOR AT LEAST THE NEXT 24 HOURS. THIS AREA
WAS HIT PREVIOUSLY BY EMILY...THUS COULD PRODUCE FLOODING OVER
THE MOUNTAINOUS TERRAIN.

TROPICAL STORM FRANKLIN IS CENTERED NEAR 30.8N 70.3W AT 25/0900
UTC MOVING ENE AT 4 KT. MAXIMUM SUSTAINED WIND SPEED IS 35 KT
WITH GUSTS TO 45 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1008
MB. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS
MIATCMAT1/WTNT21 KNHC FOR MORE DETAILS. FRANKLIN REMAINS UNDER
STRONG NW SHEAR...WITH AN EXPOSED THE LOW LEVEL CENTER AND IS
NOW BACK ON A MORE EASTERLY TRACK AFTER STALLING YESTERDAY.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN A 75 NM
RADIUS OF 30N69W WITH HEAVY SHOWERS/ISOLATED THUNDERSTORMS
EXTENDING WITHIN 90 NM OF LINE FROM 29N67W TO OVER BERMUDA NEAR
33N65W.

...TROPICAL WAVES...

E ATLC TROPICAL WAVE IS ALONG 28W/29W S OF 20N WITH A 1014 MB
LOW ALONG THE WAVE NEAR 14N...MOVING W 10-15 KT. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS W OF THE WAVE AXIS WITHIN
45/60 NM OF LINE 15N29W-12N32W.

CENTRAL ATLC TROPICAL WAVE REMAINS TILTED FROM 21N53W ALONG
15N58W TO 9N62W MOVING W 10-15 KT. WELL-DEFINED...PERSISTENT
BROAD CURVATURE IS OBSERVED ON INFRARED SATELLITE IMAGERY. WAVE
REMAINS EMBEDDED IN A BROAD AREA OF AFRICAN DUST AND COUPLED
WITH DRY AIR ARE LIMITING DEEP CONVECTION...THUS ONLY LOW LEVEL
ISOLATED THUNDERSTORMS ARE E OF THE WAVE AXIS FROM 14N-18N
BETWEEN 50W-54W.

W CARIBBEAN TROPICAL WAVE IS ALONG 84W/85W S OF 20N MOVING W
10-15 KT. WAVE CONTINUES AT THE LEADING EDGE OF THE AFRICAN DUST
SURGE...THUS ONLY SCATTERED LOW LEVEL SCATTERED SHOWERS ARE S OF
18N FROM 82W-87W INCLUDING PORTIONS OF NICARAGUA AND HONDURAS.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS INLAND AND
WITHIN 60 NM ALONG THE COAST OF COSTA RICA.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 14N16W 15N27W...THEN ALONG 11N30W
8N33W 8N41W 13N50W 12N62W. SCATTERED MODERATE/STRONG CONVECTION
IS MOVING OFF W AFRICA FROM 13N-16N E OF 19W WEAKENING TO
SCATTERED MODERATE/ISOLATED STRONG CONVECTION COVERS THE AREA
FROM 10N-15N E OF 20W TO THE COAST. CLUSTERS OF SCATTERED
MODERATE TO ISOLATED STRONG CONVECTION ARE S OF 11N TO THE
EQUATOR FROM 31W-44W.

...DISCUSSION...

GULF OF MEXICO...
MID/UPPER HIGH IS LOCATED JUST INLAND OVER E MEXICO NEAR 23N99W
WITH A RIDGE AXIS EXTENDING N OVER E TEXAS. THIS IS NOW LEAVING
THE NW GULF CLEARING. THE INVERTED UPPER TROUGH EXTENDS FROM THE
THE YUCATAN PENINSULA INTO THE CENTRAL  ALONG 88W. A SECOND
MID/UPPER RIDGE AXIS EXTENDS FROM A BROAD UPPER HIGH OVER NW
SOUTH CAROLINA S ALONG THE W COAST OF FLORIDA TO OVER W CUBA. A
SURFACE TROUGH EXTENDING FROM NEAR T.S. FRANKLIN CROSSES CENTRAL
FLORIDA NEAR LAKE OKEECHOBEE TO 29N86W AND IS GENERATING
ISOLATED SHOWERS/THUNDERSTORMS OVER THE NE GULF N OF 25N E OF
89W. ALSO AT THE SURFACE...A WEAK 1018 MB HIGH IS OVER THE NORTH
CENTRAL GULF NEAR 27N89W.

CARIBBEAN...
WATER VAPOR IMAGERY SHOWS VERY LITTLE DEEP MOISTURE OVER THE
CARIBBEAN ESPECIALLY E OF 80W. SCATTERED MODERATE/ISOLATED
STRONG CONVECTION IS INLAND AND WITHIN 60 NM ALONG THE COAST OF
COLOMBIA AND PANAMA S OF 10N E OF 78W. DRY AIR WITH SUSPENDED
AFRICAN DUST HAS MOVED INTO THE W CARIBBEAN ESSENTIALLY
PRECLUDING THE DEVELOPMENT OF DEEP CONVECTION. THE DUST CAN
PRODUCE HAZY SKIES OVER THE AREA AS IT CONTINUES MARCH WEST. AT
THE UPPER LEVELS...A MID/UPPER LEVEL TROUGH SPLITS THE CARIBBEAN
FROM A WEAK UPPER LOW N OF HISPANIOLA NEAR 20N69W SW TO THE
COAST OF CENTRAL AMERICA NEAR THE NICARAGUA/COSTA RICA BORDER.
MID/UPPER HIGH JUST E OF THE LESSER ANTILLES NEAR 13N60W IS
GIVING THE E CARIBBEAN S FLOW AND ADVECTING TROPICAL MOISTURE
OVER THE SE CARIBBEAN...PRODUCING SCATTERED THUNDERSTORMS
WITHIN 60 NM OF 12N FROM 63W-69W INCLUDING THE ABC ISLANDS.

ATLANTIC...
THE W ATLC IS DOMINATED BY SHARP UPPER LEVEL FEATURES WHILE THE
REMAINDER OF THE ATLC WATERS REMAIN RATHER BENIGN. MID/UPPER
TROUGH EXTENDS ACROSS BERMUDA SW ALONG 26N72W TO THE BAHAMAS
NEAR 23N76W. A MID/UPPER LEVEL RIDGE N OF THE REGION IS
PRODUCING NW SHEAR OVER T.S. FRANKLIN AND PUSHING THE UPPER
TROUGH FURTHER SE. NARROW MID/UPPER LEVEL RIDGE EXTENDS FROM E
CUBA ACROSS THE S BAHAMAS NE JUST SW OF FRANKLIN TO BEYOND
32N53W. DIFFLUENCE TO THE NW OF THE UPPER RIDGE IS AIDING IN THE
CONVECTION ASSOCIATED WITH THE STORM. MID/UPPER LEVEL TROUGH
EXTENDS FROM THE W ATLC NEAR 24N63W THROUGH THE UPPER LOW N OF
HISPANIOLA INTO THE CARIBBEAN. A SECOND WEAK MID/UPPER LOW IS
CENTERED TO THE E NEAR 25N54W PRODUCING SCATTERED SHOWERS/
ISOLATED THUNDERSTORMS WITHIN 75 NM OF 27N FROM 56W-60W.
MID/UPPER LEVEL HIGH IS IN THE NORTH CENTRAL ATLC NEAR 31N40W
WITH A BROAD UPPER RIDGE AXIS EXTENDING FROM OFF THE COAST OF
AFRICA NEAR 17N WNW TO 20N38W. AT THE SURFACE...SUBTROPICAL
RIDGE EXTENDS ACROSS THE ATLC FROM THE CANARY ISLANDS TO 60W
ALONG 29N/30W WITH A 1022 MB HIGH NEAR 30N40W. THIS SCENARIO
COUPLED WITH THE AFRICAN DUST/DRY AIR IS GIVING THE ATLC WATERS
E OF 60W FAIR WEATHER.

$$
WALLACE



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