[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 200555
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL.
205 AM EDT WED JUL 20 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
0445 UTC.

...SPECIAL FEATURE...

HURRICANE EMILY IS CENTERED NEAR 24.5N 96.8W...OR ABOUT 100
MILES SSE OF MATAMOROS MEXICO AND 105 MILES SE OF BROWNSVILLE
TEXAS... AT 20/0600 UTC MOVING WNW 7 KT. MAXIMUM SUSTAINED WIND
SPEED IS 110 KT WITH GUSTS TO 135 KT...MAKING EMILY A CATEGORY 3
HURRICANE ON THE SAFFIR-SIMPSON SCALE. ESTIMATED MINIMUM CENTRAL
PRESSURE REPORTED BY AIR FORCE RECONNAISSANCE IS 943 MB. SEE THE
LATEST FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS
MIATCMAT5/WTNT25 KNHC AND THE PUBLIC ADVISORY UNDER AWIPS/WMO
HEADERS MIATCPAT5/WTNT35 KNHC FOR MORE DETAILS. EMILY CONTINUES
TO STRENGTHENED ALTHOUGH NOT AS RAPIDLY AS EARLIER AND COULD
POSSIBLY BECOME A CATEGORY 4 BEFORE MAKING LANDFALL. SATELLITE
REPRESENTATION NOW SHOWS AN EYE OF ABOUT 15 NM. EMILY IS
EXPECTED TO MAKE LANDFALL DURING THE NIGHT/EARLY MORNING HOURS.
SCATTERED STRONG CONVECTION IS WITHIN 45 NM OF THE CENTER IN THE
NORTHERN SEMICIRCLE. SCATTERED MODERATE/ISOLATED STRONG
CONVECTION COVERS THE REMAINDER OF THE AREA FROM 22N-27N W OF
94.5W TO INLAND OVER NE MEXICO AND EXTREME SE TEXAS. OUTER
RAINBANDS COVER THE W GULF S OF 28N W OF 92W.

...TROPICAL WAVES...

EAST ATLANTIC TROPICAL WAVE IS ALONG 38W S OF 20N MOVING W 10
KT. CLEARLY DEFINED SHARP INVERTED-V SIGNATURE IN THE LOW LEVEL
CLOUDS IS OBSERVED ON INFRARED SATELLITE IMAGERY. WAVE HAS BEEN
OVERTAKEN BY A SURGE OF DRY SAHARAN AIR AND SUSPENDED DUST WHICH
IS MAKING THE ENVIRONMENT VERY UNFAVORABLE FOR ANY DEEP
CONVECTION.

TROPICAL WAVE E OF THE LESSER ANTILLES IS ALONG 57W/58W S OF 16N
MOVING W 10 KT. THIS HAS BEEN A WEAK WAVE AS IT HAS CROSSED THE
ATLC AND UNFORTUNATELY IS BEING OVERSHADOWED BY THE STRONG SE
FLOW FEEDING INTO THE TROPICAL WAVE IN THE E CARIBBEAN...AS WELL
AS A PREVIOUS SURGE OF DRY AIR/DUST. SHOWER ACTIVITY HAS GREATLY
REDUCED IN THE PAST 24 HOURS WITH ANY SHOWERS CONFINED S OF THE
ITCZ AXIS.

E CARIBBEAN TROPICAL IS ALONG 68W/69W S OF 22N MOVING W 10-15
KT. WAVE CONTINUES TO INTERACT WITH A LARGE AND STRONG UPPER LOW
CURRENTLY LOCATED JUST W OF JAMAICA. STRONG DIFFLUENCE E OF THE
UPPER LOW IS GENERATING SCATTERED STRONG CONVECTION E OF THE
WAVE AXIS FROM 16N-22N BETWEEN 60W-68W  AND SCATTERED
SHOWERS/THUNDERSTORMS W OF THE WAVE AXIS FROM 17N-24N BETWEEN
68W-74W.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 14N16W 9N24W 13N36W...THEN ALONG
11N39W 10N47W 9N53W 9N57W. SCATTERED MODERATE/ISOLATED STRONG
CONVECTION IS MOVING OFF AFRICA WITHIN 90 NM ALONG THE COAST
FROM 8.5N-12.5N. CLUSTERS OF SCATTERED MODERATE CONVECTION ARE
FROM 5N-10N BETWEEN 20W-36W AND BETWEEN 50W-55W.

...DISCUSSION...

GULF OF MEXICO...
HURRICANE EMILY CONTINUES TO DOMINATE THE FOCUS OVER THE GULF OF
MEXICO...MAKING LANDFALL DURING THE NIGHT/EARLY MORNING HOURS.
UPPER LEVEL OUTFLOW FROM EMILY COVERS THE W GULF S OF 33N W OF
89W. ELSEWHERE... A SECOND MID/UPPER HIGH IS OVER CENTRAL
GEORGIA NEAR 33N84W WITH A RIDGE AXIS EXTENDING NE INTO THE W
ATLC. THIS COUPLED WITH THE UPPER TROUGH OVER THE W ATLC/
CARIBBEAN IS GIVING THE E GULF NE UPPER FLOW. DRY AIR IS
BEGINNING TO FILTER ACROSS FLORIDA INTO THE E GULF AND WILL
MARCH ACROSS THE GULF TODAY INTO THU IN THE WAKE OF EMILY...
BEFORE A TROPICAL WAVE APPROACHES THE FLORIDA STRAITS AND S
FLORIDA THU NIGHT WITH AN INCREASED CHANCE OF SHOWERS/
THUNDERSTORMS. SCATTERED THUNDERSTORMS FROM A SURFACE TROUGH IN
THE W ATLC HAVE MOVED ACROSS THE N BAHAMAS INTO THE STRAITS OF
FLORIDA AND OVER S FLORIDA S OF 26N E OF 85W.

CARIBBEAN...
THE UPPER MID-OCEANIC TROUGH HAS SPLIT OVER THE PAST 24 HOURS
DEVELOPING A CUT-OFF UPPER LOW IN THE W CARIBBEAN JUST W OF
JAMAICA AND IS INTERACTING WITH A TROPICAL WAVE TO PRODUCE A
LARGE AREA OF CONVECTION/SHOWER ACTIVITY N OF 15N BETWEEN
60W-75W. THE UPPER LOW ITSELF HAS ENOUGH DRY AIR TO PRODUCE
FAIRLY BENIGN WEATHER OVER THE CENTRAL CARIBBEAN INCLUDING
JAMAICA AND CUBA. FARTHER SW...A TROPICAL SQUALL LINE IS NOW
PROPAGATED N FROM THE NICARAGUAN COAST TO THE COLOMBIAN COAST
WITH NUMEROUS STRONG CONVECTION WITHIN 45 NM OF LINE
10.5N77.5W-12N81W AND CLUSTERS OF SCATTERED MODERATE/STRONG
CONVECTION COVERING THE REMAINDER OF THE AREA S OF 14N W OF 75W
AND SCATTERED MODERATE/ISOLATED STRONG CONVECTION WITHIN 45 NM
ALONG THE REMAINDER OF THE NICARAGUAN COAST TO 85W ON THE
HONDURAN COAST. DEEP TROPICAL MOISTURE WILL REMAIN ESTABLISHED
OVER THIS AREA TO MAINTAIN SCATTERED CONVECTION FOR REMAINDER OF
THE WORK WEEK. OVER THE E CARIBBEAN...A MID/UPPER HIGH IS
CENTERED NEAR 14N64W WITH AN AMPLIFYING RIDGE AXIS EXTENDING N
INTO THE CENTRAL/WESTERN ATLC NEAR 25N. THE DIFFLUENCE
ASSOCIATED WITH THIS RIDGE IS ENHANCING THE CONVECTION OVER THE
NE CARIBBEAN.

ATLANTIC...
MID/UPPER RIDGE THAT EXTENDS FROM COVER THE SE UNITED STATES
INTO THE NW ATLC GIVING THE AREA N OF THE BAHAMAS NE FLOW AND
DRY AIR. THE UPPER MID-OCEANIC TROUGH THAT FORMED THE CUT-OFF
LOW IN THE CARIBBEAN EXTENDS FROM AN UPPER LOW IN THE CENTRAL
ATLC NEAR 34N45W WSW ALONG 30N59W 28N72W TO THE CENTRAL BAHAMAS
NEAR 25N76W. A SURFACE TROUGH...REELECTION OF THE UPPER...TROUGH
EXTENDS FROM 30N71W TO THE EXTREME N BAHAMA ISLANDS NEAR 26N77W.
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS MOVING INTO THE GULF
ARE BEING GENERATED BY THIS FEATURE. DIFFLUENCE ASSOCIATED WITH
MID/UPPER RIDGE EXTENDING FROM THE E CARIBBEAN COVER THE AREA S
OF 24N FROM 60W-74W. OVER THE E ATLC...BROAD MID/UPPER RIDGE
COVERS THE AREA E OF 36W WITH THE UPPER HIGH LOCATED JUST NE OF
THE CAPE VERDE ISLANDS NEAR 19N27W. THIS UPPER FLOW IS
RESPONSIBLE FOR THE LATEST SURGE OF AFRICAN DUST OBSERVED ON
VISIBLE SATELLITE IMAGERY LATE YESTERDAY...THUS SUPPRESSING
CONVECTION OVER THE E ATLC. AT THE SURFACE...BROAD SUBTROPICAL
RIDGE DOMINATES THE ATLC WATERS N OF 22N FROM THE CANARY ISLANDS
TO 60W WITH A 1023 MB HIGH LOCATED NEAR 28N55W. IN ADDITION...A
1008 MB LOW THAT MOVED OFF THE COAST OF AFRICA YESTERDAY IS
LOCATED OFF THE COAST OF MAURITANIA NEAR 19N18W AND A WEAK
SURFACE TROUGH EXTENDING SW TO S OF THE CAPE VERDE ISLANDS NEAR
14N24W.

$$
WALLACE


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