[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 070530
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT FRI OCT 07 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
0345 UTC.

...SPECIAL FEATURES...

A 1013 MB LOW IS E OF THE WINDWARD ISLANDS NEAR 10N44W ALONG A
TROPICAL WAVE S OF 17N MOVING W 10 KT. MID LEVEL LOW IS
ILL-DEFINED TONIGHT BUT SURFACE OBSERVATIONS INDICATE THERE IS
AT LEAST A BROAD SURFACE LOW. THERE ARE NO BANDING FEATURES ON
SATELLITE TO SUGGEST DEVELOPMENT AND THE UPPER-LEVEL WINDS DO
NOT APPEAR FAVORABLE FOR FURTHER ORGANIZATION AT THIS TIME.
SCATTERED SHOWERS WITH EMBEDDED THUNDERSTORMS ARE W OF THE LOW
FROM 10N-15N BETWEEN 44W-48W.

A 1012 MB LOW IS NE OF THE LEEWARD ISLANDS NEAR 22N55.5W IN THE
CENTRAL ATLC MOVING W 5-10 KT. A SURFACE TROUGH EXTENDS FROM THE
SURFACE LOW ALONG 17N56W THEN W ACROSS GUADELOUPE INTO THE E
CARIBBEAN TO 15N65W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS
ARE S OF THE SURFACE TROUGH WITHIN 120/150 NM OF LINE 14N63W
ACROSS THE LESSER ANTILLES TO 17N50W. THE UPPER LOW ASSOCIATED
WITH THIS SURFACE LOW HAS BEEN MOVING ACROSS THE CENTRAL ATLC
OVER THE PAST SEVERAL DAYS WITH THE SURFACE LOW FORMING OVER THE
PAST 24 HOURS. DRY UPPER AIR HAS BEEN INDUCED INTO THE UPPER
SYSTEM LEAVING THE SURFACE LOW LITTLE TO WORK WITH. THE SYSTEM
BEING EMBEDDED WITH A DEEP-LAYERED LOW PRESSURE SYSTEM TROPICAL
DEVELOPMENT IS NOT EXPECTED. COMPUTER MODELS SUGGEST THAT THE
UPPER LOW WILL DROP MORE TO THE SOUTH AND POSSIBLY ALLOW THE
SURFACE LOW TO DEEPEN IN THE NEXT FEW DAYS AS RIDGING BUILDS IN
THE UPPER LEVELS.

...TROPICAL WAVES...

CARIBBEAN TROPICAL WAVE IS ALONG 67W/68W S OF 17N MOVING W 5-10
KT. WAVE IS BENEATH STRONG N FLOW FROM AN UPPER RIDGE...THUS
MASKING THE SATELLITE SIGNATURE AND NO ASSOCIATED SHOWERS OR
CONVECTION.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 13N16W 10N30W 13N38W THEN
ILL-DEFINED ACROSS THE REMAINDER OF THE ATLC. CLUSTERS OF
SCATTERED MODERATE TO ISOLATED STRONG CONVECTION ARE WITHIN
90/120 NM OF THE AXIS E OF 38W TO THE COAST OF AFRICA.

...DISCUSSION...

GULF OF MEXICO...
A DEEP LAYERED TROUGH IS MOVING ACROSS THE CENTRAL U.S.
INTRODUCING THE FIRST MAJOR COLD FRONT IN THE GULF THIS SEASON.
THIS STRONG COLD FRONT EXTENDS ACROSS E LOUISIANA TO THE COAST
CONTINUING ALONG THE TEXAS COAST TO NEAR CORPUS CHRISTI THEN W
INTO N MEXICO. DEW POINTS ACROSS TEXAS HAVE ALREADY DROPPED INTO
THE 40'S F WITH SURFACE TEMPERATURES RANGING FROM HIGH 70'S
ALONG THE COAST TO LOW 40'S OVER THE NW. A 1003 MB SURFACE
LOW...REMNANTS OF TAMMY...HAS MOVED OFF THE COAST ALABAMA AND IS
CENTERED NEAR 29N87W. A SECOND 1003 MB SURFACE LOW IS MOVING
OVER W CUBA NEAR 23N83W. AT THE UPPER LEVELS...AN UPPER TROUGH
COVERS THE GULF EXTENDING FROM AN UPPER LOW NEAR THE ALABAMA
COAST S TO 18N. THIS IS DRAWING DRY CONTINENTAL AIR OVER MOST OF
THE GULF N OF 21N W OF 85W. THIS IS CAUSING UNSETTLED WEATHER
EXTENDING FROM S MEXICO ACROSS THE YUCATAN CHANNEL THROUGH CUBA
THEN N ACROSS FLORIDA WITH SCATTERED SHOWERS/THUNDERSTORMS.

CARIBBEAN...
AN UPPER RIDGE DOMINATES THE CARIBBEAN WITH A HIGH OVER THE
CAYMAN ISLANDS AND A BROAD RIDGE EXTENDING SW TO NEAR THE ABC
ISLANDS. A NARROW UPPER RIDGE ALSO FROM THE HIGH OVER THE
CAYMANS EXTENDS WSW ACROSS CENTRAL AMERICA IN THE GULF OF
HONDURAS. THIS SCENARIO IS GENERATING CLUSTERS OF SCATTERED
MODERATE TO NUMEROUS STRONG CONVECTION ACROSS THE NW CARIBBEAN
NW OF A LINE FROM E CUBA NEAR 20N75W TO NICARAGUA NEAR 13N84W.
THE BROAD UPPER TROUGH IN THE W/CENTRAL ATLC EXTENDS OVER THE E
CARIBBEAN N OF 12N E OF 65W. SHOWERS/THUNDERSTORMS OVER THE
LESSER ANTILLES IS BEING GENERATED BY THE SURFACE TROUGH/LOW IN
THE SPECIAL FEATURES. ISOLATED THUNDERSTORMS ARE OVER THE
CENTRAL CARIBBEAN N OF 14N FROM 68W-75W TO INLAND OVER
HISPANIOLA.

ATLANTIC...
A SHARP UPPER LEVEL RIDGE EXTENDS OVER THE W ATLC FROM AN UPPER
HIGH JUST N OF THE WINDWARD PASSAGE TO INLAND OVER THE E U.S.
THRU THE CAROLINAS AND IS SPREADING HIGH LEVEL CIRRUS CLOUDS
ACROSS MOST OF THE AREA W OF 60W. DIFFLUENCE OVER FLORIDA AND
THE BAHAMAS IS GENERATING SCATTERED SHOWERS/THUNDERSTORMS MOVING
N OVER THE AREA W OF 75W. IN THE W/CENTRAL ATLC...BROAD UPPER
TROUGH COVERS THE AREA N OF 12N FROM 47W-65W. AN EMBEDDED
CUT-OFF UPPER LOW IS CENTERED NEAR 21N55W...ASSOCIATED WITH THE
1012 MB LOW IN THE SPECIAL FEATURES. CLUSTERS OF SCATTERED
MODERATE/ISOLATED STRONG CONVECTION ARE TIED TO THE UPPER
LOW...FROM 21N-29N BETWEEN 50W-57W. BROAD UPPER HIGH IS IN THE
S/CENTRAL ATLC NEAR 12N35W WITH A SHARP RIDGE AXIS EXTENDING NNW
TO 30N45W. UPPER DIFFLUENCE IS GENERATING SCATTERED MODERATE/
STRONG CONVECTION WITHIN 90 TO 120 NM OF LINE FROM 15N39W TO
23N45W. SCATTERED SHOWERS/THUNDERSTORMS ARE ALSO FROM 17N-29N
BETWEEN 43W-50W. OVER THE E ATLC...A DEEP LAYERED LOW IS N OF
THE REGION WITH AN UPPER TROUGH DIPPING S TO 24N FROM THE CANARY
ISLANDS TO 32W. ASSOCIATED SURFACE TROUGH EXTENDS INTO THE
REGION NEAR 32N19W SW TO 26N28W. SHOWERS/THUNDERSTORMS ARE N OF
THE CANARY ISLANDS E OF 20W. THE AFRICA DUST SURGE IS MOVING
INTO THE E/CENTRAL ATLC E OF THE CAPE VERDE ISLANDS.

$$
WALLACE


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