[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 211051
TWDAT

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

...SPECIAL FEATURE...

TROPICAL STORM EMILY WAS DOWNGRADED TO TROPICAL DEPRESSION AT
21/0900 UTC. EMILY IS CENTERED INLAND NEAR 25.0N 101.1W MOVING W
9 KT. MAXIMUM SUSTAINED WIND SPEED IS 30 KT WITH GUSTS TO 40 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 1004 MB. SEE THE LATEST
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT5/WTNT25 KNHC
FOR MORE DETAILS. EMILY IS FINALLY LOSING ITS PUNCH AS IT
CROSSES OVER THE SIERRA MADRE MOUNTAINS. RAINFALL AMOUNTS HAVE
REDUCED AS THE DEEP CONVECTION IS DYING OUT. SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS CONTINUE OVER NE MEXICO WITH
ISOLATED SHOWERS OVER THE NW GULF.

...TROPICAL WAVES...

E ATLC TROPICAL WAVE IS ALONG 26N22W THROUGH A 1011 MB LOW W OF
THE CAPE VERDE ISLANDS NEAR 14N27W TO 7N26W 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
11N-15N BETWEEN 18W-22W.

CENTRAL ATLC TROPICAL WAVE IS ALONG 45W/46W 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 64W/65W S OF 13N MOVING
W 10-15 KT. THIS IS A LOW AMPLITUDE WAVE AT THE LEADING EDGE OF
DRY UPPER AIR...THUS NO ASSOCIATED CONVECTION.

CENTRAL CARIBBEAN TROPICAL WAVE IS ALONG 26N72W OVER E CUBA NEAR
20N75W TO INLAND OVER COLOMBIA NEAR 6N76W MOVING NW NEAR 10 KT.
SCATTERED STRONG CONVECTION IS OVER THE CENTRAL BAHAMAS WITHIN A
90 NM RADIUS OF 23.5N73W. SCATTERED MODERATE/ISOLATED STRONG
CONVECTION CONTINUES TO FORM TO THE E OF THE N END OF THE WAVE N
OF 16N ACROSS HISPANIOLA...THE TURKS AND CAICOS ISLANDS TO 27N
BETWEEN 67W-76W...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.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 15N16W TO THE CAPE VERDE ISLANDS...
THEN DISTORTED DUE TO THE E ATLC TROPICAL WAVE/LOW CONTINUING
ALONG 10N28W 9N40W INLAND OVER SOUTH AMERICA NEAR 7N60W.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 75 NM OF
9N FROM 55W TO 63W. CLUSTERS OF SIMILAR CONVECTION DOT THE
REMAINDER OF THE AREA WITHIN 200 NM OF THE AXIS.

...DISCUSSION...

GULF OF MEXICO...
SHOWERS AND THUNDERSTORMS ASSOCIATED WITH TROPICAL STORM EMILY
ARE NOW INLAND OVER MEXICO. THE UPPER LEVEL HIGH LOCATED OVER
EMILY CONTINUES TO PUMP HIGH CLOUDS OVER THE W GULF W OF
95W...BUT WILL CONTINUE TO MOVE OUT OF THE AREA AS STRONGER
UPPER N TO NE FLOW 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
AFTERNOON THUNDERSTORMS POSSIBLE FROM OVER S FLORIDA INTO THE
STRAITS OF FLORIDA AND CUBA AS THE UPPER TROUGH MOVES OVER THE
REMAINDER OF THE BAHAMAS. WIDESPREAD SHOWER ACTIVITY WILL AGAIN
FIRE UP WHEN MOISTURE INCREASES OVER THE SE GULF AHEAD OF A NEXT
TROPICAL WAVE.

CARIBBEAN...
SHARP...NARROW MID/UPPER LEVEL TROUGH EXTENDS FROM THE N BAHAMAS
NEAR 27N78W ACROSS THE STRAITS OF FLORIDA TO OVER THE YUCATAN
CHANNEL AND PENINSULA. THE REMAINDER OF THE CARIBBEAN IS
DOMINATED BY A MID/UPPER LEVEL HIGH CENTERED NEAR 14N77W WITH
FLOW COVERING THE CENTRAL CARIBBEAN FROM 68W-87W. DIFFLUENCE IN
ASSOCIATED WITH THE TROPICAL WAVE IS GENERATING THE CONVECTION N
OF 16N FROM 67W-76W...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 90/120 NM OF LINE
12.5N80W-16N82W AND SCATTERED MODERATE/ISOLATED STRONG
CONVECTION WITHIN 120 NM OF LINE 16N82W-19N86W. UPPER LEVEL HIGH
IS DRIFTING WESTWARD. OVER THE FAR E CARIBBEAN...DEEP DRY AIR
HAS MOVED IN BEHIND THE CENTRAL CARIBBEAN TROPICAL WAVE TO
PRODUCE FAIR WEATHER E OF 66W...REINFORCED BY A SWATH OF UPPER
LEVEL SUBSIDENCE OVER THE LESSER ANTILLES.

ATLANTIC...
SHARP...NARROW MID/UPPER TROUGH EXTENDS FROM THE N BAHAMAS NEAR
27N78W ACROSS THE STRAITS OF FLORIDA TO OVER THE YUCATAN CHANNEL
AND PENINSULA. MID/UPPER LEVEL RIDGE AXIS EXTENDS FROM PUERTO
RICO NEAR 20N68W NW TO 29N72W...COUPLED WITH THE TROPICAL WAVE
ARE PROVIDING A DIFFLUENT ENVIRONMENT FOR THE STRONG CONVECTION
OVER THE AREA OF THE W ATLC S OF 27N FROM 67W-76W. THE REMAINDER
OF THE ATLC WATERS IS RATHER BENIGN. MID/UPPER LEVEL TROUGH
EXTENDS FROM AN UPPER LOW IN THE CENTRAL ATLC NEAR 34N41W SW TO
21N56W AND THIS HAS SERVED TO CUT THE SUBTROPICAL RIDGE IN HALF
NEAR 50W. A SURFACE TROUGH EXTENDS FROM 32N49W SW TO 27N52W. THE
E ATLC IS DOMINATED BY A STRONG DEEP-LAYERED HIGH LOCATED NEAR
17N32W. THIS HAS PROPELLED AN EXTENSIVE SURGE OF AFRICAN DUST
OVER THE OPEN WATERS OF THE ATLC E OF 47W. AT THE SURFACE...
SUBTROPICAL RIDGE EXTENDS FROM THE E ATLC THROUGH 32N33W TO
26N47W THEN SPLITS...IN THE W ATLC FROM 25N55W THROUGH A 1021 MB
HIGH IS CENTERED SW OF BERMUDA NEAR 29N69W W TO THE NE COAST OF
FLORIDA.

$$
WALLACE





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