[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 261046
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT MON SEP 26 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.

...TROPICAL WAVES...

CENTRAL ATLC TROPICAL WAVE IS ALONG 40W S OF 20N MOVING W 10 KT.
ELONGATED LOW LEVEL CIRCULATION IS CENTERED ROUGHLY NEAR 13N.
WAVE IS BENEATH S UPPER FLOW AROUND AN UPPER HIGH LOCATED TO THE
E OF THE WAVE AND AN UPPER TROUGH TO THE W OF THE WAVE. THIS IS
GENERATING ENOUGH DIFFLUENCE FOR SCATTERED SHOWERS/THUNDERSTORMS
FROM 13N-19N BETWEEN 37W-44W.

E CARIBBEAN TROPICAL WAVE IS ALONG 71W S OF 20N MOVING W 15 KT.
WAVE IS BENEATH E TO SE UPPER FLOW AT THE BASE OF AN UPPER HIGH
SO SATELLITE SIGNATURE IS NON-EXISTENT. SCATTERED MODERATE/
STRONG CONVECTION IS FROM 12N-17N BETWEEN 68W-74W INCLUDING THE
ABC ISLANDS.

W CARIBBEAN TROPICAL WAVE IS ALONG 82W S OF 20N MOVING W 15 KT.
WAVE IS BENEATH NE UPPER FLOW FROM THE RIDGE ANCHORED IN THE
GULF OF MEXICO. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE
FROM 14N-20N BETWEEN 81W-85W.

...ITCZ...

ITCZ IS CENTERED ALONG 12N14W 8N25W 15N38W THEN ALONG 12N42W
6N56W. SCATTERED MODERATE/STRONG CONVECTION IS MOVING OFF AFRICA
WITHIN 120 NM OF THE ITCZ AXIS E OF 18W AND WITHIN 150/180 NM OF
THE AXIS FROM 24W-30W. SCATTERED MODERATE/ISOLATED STRONG
CONVECTION IS FROM 5N-9N BETWEEN 9W-17W INCLUDING THE COAST OF
AFRICA...WITHIN 90 NM S OF THE AXIS FROM 31W-34W.

...DISCUSSION...

THE GULF OF MEXICO...
A BROAD UPPER HIGH IS LOCATED OFF THE LOUISIANA COAST NEAR
29N93W GIVING THE UPPER LEVELS NE TO E FLOW. STRONG SUBSIDENCE
AND DRY AIR DOMINATE THE N GULF WHILE THE S GULF IS MOISTURE
LADENED. HOWEVER THE LOWER LEVELS ARE RELATIVELY DRY OVER THE S
SO ISOLATED THUNDERSTORMS ARE FOUND IN THE BAY OF CAMPECHE S OF
22N. AT THE SURFACE...S TO SE FLOW DOMINATES THE GULF WITH A
RIDGE EXTENDING FROM THE W ATLC ACROSS NE FLORIDA TO THE CENTRAL
GULF NEAR 26N90W. STRONG SHORTWAVE TROUGH...REMNANTS OF
RITA...IS MOVING ACROSS ALABAMA INTO GEORGIA GENERATING A LINE
OF SHOWERS/THUNDERSTORMS WITHIN 60 NM OF LINE THROUGH 33N86W TO
ALONG THE N GULF COAST NEAR 30N87W. SURFACE TROUGHING IS
EXPECTED TO DEVELOP OVER THE N GULF...NOT RELATED TO RITA...ON
TUE BRINGING WITH IT INCREASE CHANCES OF SHOWERS/THUNDERSTORMS.

CARIBBEAN...
THE AREA IS SPLIT BETWEEN THE UPPER RIDGE OF THE GULF EXTENDING
OVER THE NW CARIBBEAN AND AND UPPER RIDGE IN THE CENTRAL ATLC
OVER THE E TWO THIRDS OF THE CARIBBEAN. BETWEEN IS A CUT-OFF
UPPER LOW LOCATED JUST N OF CUBA NEAR 23N78W WITH AN INDUCED
TROUGH EXTENDING SW ACROSS CUBA TO THE TIP OF NICARAGUA/
HONDURAS. TROPICAL MOISTURE IS ABUNDANT OVER THE CARIBBEAN
GENERATING CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG
CONVECTION AS WELL AS SCATTERED MODERATE/STRONG CONVECTION
ASSOCIATED WITH THE TROPICAL WAVE OVER THE E CARIBBEAN.
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS COVER THE REMAINDER OF
THE AREA TO OVER THE LESSER ANTILLES. DEEP-LAYERED MOISTURE WILL
REMAIN QUITE PREVALENT ACROSS THE AREA OVER THE NEXT 5 DAYS
MOVING INTO THE W CARIBBEAN BY MIDWEEK AND SHOULD BE ABLE TO
SUPPORT AREAS OF SHOWERS/THUNDERSTORMS FOR MOST OF THE UPCOMING
WEEK.

ATLANTIC...
BROAD UPPER RIDGE FROM THE GULF OF MEXICO EXTENDS ACROSS FLORIDA
INTO THE NW ATLC. UPPER TROUGH EXTENDS FROM 30N75W ACROSS THE
BAHAMAS TO THE CUT-OFF UPPER LOW JUST N OF CUBA NEAR 23N78W. THE
UPPER LEVELS ARE RELATIVELY DRY WITH LOW LEVEL ISOLATED SHOWERS
ON THE W SIDE OF THE UPPER TROUGH COVERING THE N BAHAMA ISLANDS
ACROSS THE STRAITS OF FLORIDA S OF 26N FROM 77W-81W. DEEP
LAYERED TROUGH IS IN THE N/CENTRAL ATLC WITH THE UPPER TROUGH
AXIS EXTENDING THROUGH 32N60W SW TO 25N64W. A DOUBLE BARREL 1006
MB LOWS ARE ALONG THE N PORTION OF THE REGION NEAR 33.5N53W AND
31N55.5W WITH A SURFACE TROUGH EXTENDING SW THROUGH 32N53W
26N56W TO 26N67W. SCATTERED SHOWERS/THUNDERSTORMS ARE WITHIN 60
NM OF LINE FROM 25N55W TOP BEYOND 32N52W. AN UPPER HIGH IS S OF
THE DEEP LAYERED TROUGH CENTERED NEAR 20N63W AND DIPS S INTO THE
CARIBBEAN. TO THE E IS AN UPPER TROUGH THAT EXTENDS FROM AN
UPPER LOW S OF THE AZORES THROUGH 32N32W ALONG 25N44W TO AN
UPPER LOW TO THE W OF A TROPICAL WAVE NEAR 17N48W INTO THE DEEP
TROPICS NEAR 9N53W. THIS IS DRYING OUT THE AREA W OF THE
TROPICAL WAVE AND THE W TROPICAL ITCZ. AN UPPER HIGH IS E OF THE
SAME TROPICAL WAVE NEAR 22N28W WITH A SHARP RIDGE EXTENDING N TO
31N21W AND SW TO 5N38W. THIS IS ADVECTING TROPICAL MOISTURE N
ACROSS THE TROPICAL WAVE AND KEEPING THE ITCZ AND ASSOCIATED
CONVECTION S OF THE ITCZ AXIS OVER THE E TROPICAL ATLC.
AN UPPER LOW IS MOVING S OF THE CAPE VERDE ISLANDS NEAR 13N25W
DISRUPTING THE RIDGE JUST TO THE W. AN UPPER TROUGH IS DIGGING
SW ALONG THE COAST OF MAURITANIA AND WESTERN SAHARA TO NEAR
24N16W. DRY AFRICAN LOW LEVEL AIR IS OVER THE E ATLC S OF 22N E
OF THE CAPE VERDE ISLANDS. AT THE SURFACE...THE SUBTROPICAL
RIDGE IS BROKEN BETWEEN THE W AND E ATLC...THE W EXTENDING FROM
A HIGH SE OF NEWFOUNDLAND ALONG THE E COAST OF THE US ACROSS NE
FLORIDA NEAR 30N82W INTO THE GULF OF MEXICO AND THE E FROM A
HIGH JUST SE OF THE AZORES THROUGH 32N34W TO 20N50W.

$$
WALLACE



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