[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 070539
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT THU 07 OCT 2004

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHEASTERN
SECTIONS OF SOUTH AMERICA...AND ATLC 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.

...TROPICAL WAVES...

TROPICAL WAVE ABOUT 440 NM WSW OF THE CAPE VERDE ISLANDS IS
ALONG 31W S OF 13N MOVING W 10-15 KT. WAVE IS LOW AMPLITUDE AT
THE BASE OF A MID/UPPER TROUGH WHICH IS PRODUCING WESTERLY
SHEAR. THIS IS PREVENTING ANY FURTHER DEVELOPMENT AND NO
ASSOCIATED DEEP CONVECTION.

TROPICAL WAVE LOCATED ABOUT 650 NM E OF BARBADOS ALONG 48W/49W S
OF 17N MOVING W 10-15 KT. WAVE IS LOW AMPLITUDE WITH LITTLE
WESTERLY SHEAR. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG
CONVECTION ARE FROM 10N-16N BETWEEN 42W-49W.

TROPICAL WAVE REMAINS ALONG 58W/59W S OF 20N DRIFTING WEST. LOW
LEVEL CIRCULATION IS OBSERVED ALONG THE WAVE NEAR 16N. THIS WAVE
CONTINUES TO INTERACT WITH A MID/UPPER LEVEL TROUGH TO THE W AND
RIDGE TO THE E WHICH MAKES THE AXIS PLACEMENT DIFFICULT TO
DETERMINE. LARGE CLUSTERS OF SCATTERED MODERATE/STRONG
CONVECTION ARE FROM 10N-25N BETWEEN 50W-58W.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 17N10W 7N20W 7N38W 12N46W THEN IS
DISTORTED BY THE MID/UPPER LEVEL TROUGH OVER THE CARIBBEAN AND
THE INDUCED RIDGE TO E. CLUSTERS OF SCATTERED MODERATE/ISOLATED
STRONG CONVECTION ARE WITHIN 150/180 NM OF LINE FROM INLAND OVER
AFRICA OFF THE COAST NEAR GUINEA-BISSAU AT 13N16W TO 7N25W AND
WITHIN 75 NM OF LINE 6N34W-9N42W.

...DISCUSSION...

GULF OF MEXICO...
A 1010 MB LOW REMAINS OFF THE COAST OF MEXICO NEAR 21N96W ALONG
A STATIONARY SURFACE TROUGH WHICH IS ALSO OFF THE MEXICAN
COAST FOR THE PAST 2 DAYS. SATELLITE IMAGERY HAS SUGGESTED THAT
A LOW/MID LEVEL CIRCULATION BECOME BETTER DEFINED YESTERDAY AND
WIDESPREAD THUNDERSTORMS CONTINUE OVER MUCH OF THE NW GULF.
SCATTERED STRONG CONVECTION IS WITHIN 90 NM OF LINE FROM 24N93W
TO THE COAST OF THE YUCATAN PENINSULA IN THE BAY OF CAMPECHE
NEAR 19N91W. FARTHER N...A WEAK STATIONARY FRONT EXTENDS ACROSS
CENTRAL FLORIDA TO COASTAL LOUISIANA AS STRONG A HIGH BUILDS IN
FROM THE N OVER THE E COAST OF THE UNITED STATES. A BROAD UPPER
LEVEL HIGH IS CENTERED OVER THE YUCATAN PENINSULA NEAR N
GUATEMALA/BELIZE WITH A RIDGE THAT EXTENDS N OVER THE
MISSISSIPPI VALLEY INTO CANADA. THIS IS BRINGING ABUNDANT
MOISTURE FROM THE W GULF SHOWERS/THUNDERSTORMS E ACROSS THE E
GULF OVER FLORIDA INTO THE W ATLC INCLUDING THE N BAHAMAS. THIS
SCENARIO WILL CONTINUE THROUGH THE WEEKEND AS THE SURFACE LOW
MOVES N AND INTERACTS WITH THE STATIONARY FRONTAL BOUNDARY.

CARIBBEAN...
THE DOMINANT FEATURE OVER THE AREA CONTINUES TO BE THE LARGE
MID/UPPER LEVEL TROUGH WHICH EXTENDS FROM THE S AMERICAN COAST N
OVER THE CENTRAL ATLC BETWEEN THE LEEWARD ISLANDS AND THE W
CARIBBEAN E OF 75W. THE MAIN TROUGH AXIS EXTENDS ACROSS
HISPANIOLA SW TO THE GUAJIRA PENINSULA OF COLOMBIA. STRONG
SUBSIDENCE BEHIND THIS AXIS IS PRODUCING MOSTLY DRY CONDITIONS
FOR THE CENTRAL CARIBBEAN WITH THE EXCEPTION OF A FEW LOW LEVEL
ISOLATED SHOWERS. ELSEWHERE...UPPER LEVEL RIDGING AND MORE
ABUNDANT MOISTURE OVER CENTRAL AMERICA HAS PRODUCED SCATTERED
MODERATE/STRONG CONVECTION INLAND OVER THE YUCATAN PENINSULA
GUATEMALA...HONDURAS AND EL SALVADOR MOSTLY ALONG THE W COAST OF
CENTRAL AMERICA AND IN THE E PACIFIC REGION. SW FLOW ON THE E
SIDE OF THE UPPER TROUGH IS BRINGING HIGH LEVEL CLOUDINESS
ACROSS THE LEEWARD/WINDWARD ISLANDS BUT THE STRONGEST CONVECTION
REMAINS WELL TO THE E OVER THE TROPICAL ATLC...OR E OF AN
APPROACHING TROPICAL WAVE.

SUBTROPICAL ATLANTIC...
A MID/UPPER LEVEL TROUGH IS PUSHING OFF THE MID-ATLC COAST OF
THE UNITED STATES WITH A COLD FRONT ENTERING THE W ATLC NEAR
32N66W EXTENDING SW TO 28N70W CONTINUING W AS A STATIONARY FRONT
ACROSS CENTRAL FLORIDA. THE FRONT IS BRINGING IN GENERALLY DRY
AIR MASS EXTENDING N OF PUERTO RICO AND HISPANIOLA WITH ONLY LOW
CLOUDS WITH ISOLATED SHOWERS ALONG THE FRONTAL BOUNDARY.
HOWEVER...STRONG UPPER LEVEL RIDGING IS BUILDING OVER THE
CENTRAL ATLC TO THE E OF THE DEEP TROUGH EXTENDING TO OVER THE
CARIBBEAN. THIS IS PUMPING A GOOD AMOUNT OF MOISTURE N INTO THE
SUBTROPICS. A WEAK SURFACE TROUGH IS EMBEDDED BENEATH THIS FLOW
FROM 22N59W 30N54W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE
FROM 20N-30W BETWEEN 47W-61W. FARTHER E...A BROAD MID/UPPER
TROUGH COVERS MUCH OF THE AREA E OF 35W. STRONG SURFACE RIDGING
EXTENDS ALONG 32N42W SE TO THE CANARY ISLANDS. MODERATE
SUBSIDENCE IN THE MID/UPPER LEVELS IS KEEPING THE AREA MOSTLY
DRY.

TROPICAL ATLANTIC...
STRONG UPPER LEVEL RIDGING IS E OF THE LESSER ANTILLES FROM 15N
N INTO THE SUBTROPICS...WITH FAIRLY SOLID WESTERLY FLOW
STREAMING E/SE S OF 15N. UPPER LEVEL DIVERGENCE HAS FORMED WHERE
THESE TWO FLOWS HAVE SPLIT...FOCUSING THUNDERSTORM ACTIVITY TO
THE E OF THE TROPICAL WAVE APPROACHING THE ISLANDS. E OF 40W...
BROAD CYCLONIC/WESTERLY FLOW EXTENDS S TO THE LATITUDE OF THE
CAPE VERDE ISLANDS...THUS CREATING A NARROW RIDGE AXIS ALONG
10N.

$$
WALLACE


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