[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 210539
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT THU JUL 21 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 FEATURE...

TROPICAL STORM EMILY IS CENTERED INLAND NEAR 25.0N 100.2W...OR
ABOUT 56 NM SSE OF MONTERREY MEXICO AND 156 NM WSW OF
BROWNSVILLE TEXAS...AT 21/0300 UTC MOVING W 9 KT. MAXIMUM
SUSTAINED WIND SPEED IS 45 KT WITH GUSTS TO 55 KT. ESTIMATED
MINIMUM CENTRAL PRESSURE IS 1001 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. BOTH SATELLITE AND RADAR IMAGERY CLEARLY SHOW
THE CENTER OF EMILY HAS CROSSED THE SIERRA MADRE MOUNTAINS. VERY
HEAVY RAINFALL WILL CONTINUE OVER NE MEXICO AS EMILY WINDS
DOWN...ESPECIALLY TO THE N OF THE CENTER TO THE RIO GRANDE.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN WITHIN
75 NM OF LINE 27N101W TO THE COAST OF MEXICO N OF TAMPICO NEAR
22.5N98W.

...TROPICAL WAVES...

E ATLC TROPICAL WAVE IS ALONG 26N22W THROUGH A 1011 MB LOW OVER
THE CAPE VERDE ISLANDS NEAR 15N25W TO 6N25W MOVING W 10-15 KT.
WAVE IS ACCOMPANIED BY AN EXPANSIVE CIRCULATION THAT REACHES
FROM THE ITCZ N TO JUST W OF THE CANARY ISLANDS. THE AREA IS
SURROUNDED BY A THICK PLUME OF SAHARAN DUST...REDUCING
VISIBILITIES. WAVE ITSELF HAS A WELL-DEFINED SIGNATURE
CURVATURE. DEEP TROPICAL MOISTURE IS BEING DRAWN W BEHIND THE
WAVE WITH SCATTERED MODERATE/ISOLATED STRONG CONVECTION FROM
10N-14N BETWEEN THE WAVE AXIS AND THE COAST OF AFRICA.

CENTRAL ATLC TROPICAL WAVE IS ALONG 44W/45W S OF 21N MOVING W 10
KT. WAVE HAS A WELL DEFINED SIGNATURE CURVATURE THAT IS THE
LEADING EDGE OF THE THICK PLUME OF SAHARAN DUST. WAVE IS
EMBEDDED WITHIN DRY UPPER AIR...THUS NO ASSOCIATED CONVECTION.

WEAK SE CARIBBEAN TROPICAL WAVE IS ALONG 63W S OF 13N MOVING W
10 KT. THIS IS A LOW AMPLITUDE WAVE AT THE LEADING EDGE OF DRY
UPPER AIR...SO ANY CONVECTION IS INLAND OVER VENEZUELA.

CENTRAL CARIBBEAN TROPICAL WAVE IS ALONG 25N72W THROUGH THE
WINDWARD PASSAGE INLAND OVER COLOMBIA NEAR 11N75W TO 6N75W
MOVING WNW 10 KT. SCATTERED STRONG CONVECTION CONTINUE TO FORM
TO THE E OF THE N END OF THE WAVE N OF 16N ACROSS HISPANIOLA...
THE TURKS AND CAICOS ISLANDS TO 25N W OF 67W...FORCED BY A SHARP
MID/UPPER TROUGH THAT EXTENDS FROM THE W ATLC INTO THE W
CARIBBEAN. THIS AREA WILL BE WATCHED FOR ANY SIGNS OF
DEVELOPMENT. THE STRONG CONVECTION COULD CAUSE FLASH FLOODING
OVER PARTS OF THE AREA THROUGH TONIGHT INTO THE MORNING HOURS.

...ITCZ...

ITCZ AXIS IS DISTORTED DUE TO THE E ATLC TROPICAL WAVE/LOW THEN
CENTERED ALONG 10N28W 9N40W 12N47W INLAND OVER SOUTH AMERICA
NEAR 7N58W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS
WITHIN A 45 NM RADIUS OF 6N36W. CLUSTERS OF SCATTERED MODERATE
CONVECTION DOT THE AREA FROM 5N-13N BETWEEN 45W-52W WITH A
HEAVIER CONCENTRATION FROM 7N-10N W OF 52W TO THE COAST OF SOUTH
AMERICA.

...DISCUSSION...

GULF OF MEXICO...
SHOWERS AND THUNDERSTORMS ASSOCIATED WITH TROPICAL STORM EMILY
ARE NOW INLAND OVER MEXICO JUST INTO S TEXAS. THE UPPER LEVEL
HIGH LOCATED OVER EMILY CONTINUES TO PUMP HIGH CLOUDS OVER THE W
GULF W OF 92W...BUT THIS TOO SHOULD BEGIN TO MOVE OUT OF THE
AREA AS STRONGER UPPER N TO NE DOMINATES THE GULF. THIS FLOW IS
THE RESULT OF THE APPROACHING SHARP TROUGH OVER THE W ATLC INTO
THE CARIBBEAN. THE LOW LEVEL AIR MASS IS LARGELY DRY WITH
DISSIPATING AFTERNOON THUNDERSTORMS FROM OVER FLORIDA MOVE
RAPIDLY INTO THE E GULF N OF 25N. THUNDERSTORMS CONTINUE TO
DEVELOP OVER CUBA MOVING INTO THE STRAITS OF FLORIDA AND THE
YUCATAN CHANNEL AS A RESULT OF THE UPPER TROUGH THAT EXTENDS
FROM THE W ATLC ACROSS CUBA. THE REMAINDER OF THE GULF REMAINS
SHOWER FREE. SHOWER ACTIVITY WILL AGAIN FIRE UP WHEN MOISTURE
INCREASES LATE FRI OVER THE SE GULF AHEAD OF A NEXT TROPICAL
WAVE.

CARIBBEAN...
SHARP...NARROW MID/UPPER LEVEL TROUGH EXTENDS FROM THE BAHAMAS
NEAR 28N78W ACROSS W CUBA INTO THE CARIBBEAN TO THE GULF OF
HONDURAS. THIS IS GENERATING THUNDERSTORMS THAT ARE IN THE
YUCATAN CHANNEL. THE REMAINDER OF THE CARIBBEAN IS DOMINATED BY
A MID/UPPER LEVEL HIGH CENTERED NEAR 14N76W WITH FLOW COVERING
THE CENTRAL CARIBBEAN FROM 67W-85W. DIFFLUENCE IN ASSOCIATED
WITH THE TROPICAL WAVE IS GENERATING THE CONVECTION N OF 16N
FROM 68W-74W...SEE TROPICAL WAVES ABOVE. STRONG DIFFLUENCE TO
THE W OF THE UPPER HIGH AND A WEAK SURFACE TROUGH LYING OFF THE
COAST OF NICARAGUA AND COSTA RICA IS GENERATING SCATTERED/
NUMEROUS STRONG CONVECTION WITHIN 60 NM OF LINE 14N80W-18N84W.
THIS DIFFLUENCE LIES E OF AN UPPER TROUGH OVER THE GULF OF
HONDURAS. UPPER LEVEL HIGH IS EXPECTED TO BEGIN SHIFTING NW
AFTER 24 HRS...AS WELL AS THE DEEPEST TROPICAL MOISTURE...SO
ROUNDS OF CONTINUOUS SHOWERS/TSTMS CAN BE EXPECTED OVER THE SW
CARIBBEAN THROUGH THU NIGHT...AND SHOULD EXPAND OVER THE NW
CARIBBEAN AS WELL. OVER THE FAR E CARIBBEAN...DEEP DRY AIR HAS
MOVED IN BEHIND THE CENTRAL CARIBBEAN TROPICAL WAVE TO PRODUCE
FAIR WEATHER E OF 65W...REINFORCED BY A SWATH OF UPPER LEVEL
SUBSIDENCE NOW COVERS THE LESSER ANTILLES.

ATLANTIC...
SHARP...NARROW MID/UPPER TROUGH EXTENDS FROM THE BAHAMAS NEAR
28N78W ACROSS W CUBA COVERING THE W ATLC W OF 74W. MID/UPPER
LEVEL RIDGE AXIS EXTENDS FROM THE VIRGIN ISLANDS/PUERTO RICO
NEAR 20N66W NW TO 29N70W...COUPLED WITH THE TROPICAL WAVE ARE
PROVIDING A DIFFLUENT ENVIRONMENT FOR THE STRONG CONVECTION OVER
THE AREA OF THE W ATLC S OF 25N FROM 67W-74W INCLUDING THE TURKS
AND CAICOS ISLANDS. THE REMAINDER OF THE ATLC WATERS IS RATHER
BENIGN. MID/UPPER LEVEL TROUGH EXTENDS FROM AN UPPER LOW IN THE
CENTRAL ATLC NEAR 33N42W SW TO 23N58W AND THIS HAS SERVED TO CUT
THE SUBTROPICAL RIDGE IN HALF NEAR 50W. A SURFACE TROUGH EXTENDS
FROM 21N50W SW TO 27N53W. THE E ATLC IS DOMINATED BY A STRONG
DEEP-LAYERED HIGH LOCATED NEAR 18N30W. THIS HAS PROPELLED AN
EXTENSIVE SURGE OF AFRICAN DUST OVER THE OPEN WATERS OF THE ATLC
E OF 40W. AT THE SURFACE...SUBTROPICAL RIDGE EXTENDS FROM THE E
ATLC THROUGH 32N33W TO 28N45W THEN SPLITS...A 1021 MB HIGH IS
CENTERED S OF BERMUDA NEAR 29N60W NW TO THE COAST OF THE U.S.
NEAR THE CAROLINAS.

$$
WALLACE




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