[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 152331
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT FRI 15 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2245 UTC.

...TROPICAL WAVES...
TROPICAL WAVE IS ALONG 59W S OF 15N MOVING W 10 KT. WAVE HAS
SLOWED OVER THE PAST SEVERAL HOURS AS IT APPROACHES THE ISLANDS
OF THE CARIBBEAN. SCATTERED SHOWERS ARE WITHIN 60 NM OF LINE
FROM 12N57W ACROSS THE WINDWARD ISLANDS TO 13N63W.

TROPICAL WAVE IN THE W CARIBBEAN IS ALONG 88W S OF 17N MOVING W
10 KT. THIS WAVE IS BENEATH A MID/UPPER LEVEL HIGH WHICH IS
DISTORTING THE WAVE AXIS ON SATELLITE IMAGERY.

...ITCZ...
ITCZ IS CENTERED ALONG 15N10W 10N19W 9N36W 11N50W 11N57W 12N63W.
NUMEROUS STRONG CONVECTION IS MOVING OFF THE COAST OF SIERRA
LEONE AND S GUINEA WITHIN 60 NM ALONG THE COAST FROM 7.5N-10N.
SCATTERED MODERATE/STRONG CONVECTION IS WITHIN 90 NM OF 17W FROM
3N-8N. BROAD AREA OF SCATTERED MODERATE/ISOLATED STRONG
CONVECTION ACROSS THE REMAINDER OF THE TROPICS IS DUE TO UPPER
LEVEL CONDITIONS SEE BELOW.

...DISCUSSION...
N GULF OF MEXICO AND NW ATLANTIC...
BROAD DEEP LAYERED TROUGH COVERS THE E UNITED STATES INTO THE
GULF OF MEXICO N OF 25N THEN INTO THE W ATLC N OF 22N W OF 75W.
THE MAIN UPPER LOW IS WELL N OF THE REGION OVER THE GREAT LAKES.
THIS IS BRINGING STRONG SUBSIDENCE WITH MUCH DRIER AND COOLER
AIR TO ALL OF THE SE UNITED STATES AND N GULF. THE ASSOCIATED
COLD FRONT EXTENDS INTO THE W ATLC NEAR 32N77W SW ACROSS CENTRAL
FLORIDA NEAR LAKE OKEECHOBEE TO 23N93W THEN S INTO THE BAY OF
CAMPECHE TO 18N94W THE CONTINUES NW BECOMING STATIONARY ALONG
THE MOUNTAINS OF MEXICO. BEHIND THIS FRONT DEW POINTS HAVE
ALREADY DROPPED INTO THE 40 TO 50 DEG F RANGE ACROSS THE N GULF
AS OF 15/2100 UTC. PRE-FRONTAL TROUGH EXTENDS FROM THE W ATLC
NEAR 31N75W THROUGH THE STRAITS OF FLORIDA NEAR 24N82W TO OVER
THE YUCATAN PENINSULA NEAR 20N90W. SCATTERED MODERATE/STRONG
CONVECTION IS ASSOCIATED WITH THE TROUGH EXTENDS WITHIN 90/120
NM OF LINE FROM THE BAHAMAS NEAR 25N78W ACROSS CUBA TO OVER THE
YUCATAN PENINSULA NEAR 19N90W. JETSTREAM WITH WINDS OF 90 TO 100
KT EXTENDS FROM THE E GULF NEAR 26N84W ACROSS FLORIDA INTO THE W
ATLC ALONG 28N78W TO BEYOND 32N74W.

W CARIBBEAN SEA AND REMAINDER OF W ATLANTIC...
BROAD MID/UPPER LEVEL HIGH REMAINS OVER THE N GUATEMALA NEAR
18N90W WITH ANTICYCLONIC FLOW COVERING THE S GULF OF MEXICO S OF
21N AND THE CARIBBEAN W OF 65W. IN THE W ATLC...A RIDGE AXIS
EXTENDS FROM E CUBA NEAR 21N76W NE TO BEYOND 32N69W. THIS FLOW
IS ENHANCING THE CONVECTION ALONG THE PRE-FRONTAL TROUGH
DESCRIBED ABOVE. DIVERGENCE ALOFT OVER THE W ATLC IS PRODUCING
CLOUDINESS WITH SCATTERED SHOWERS/ISOLATED THUNDERSTORMS N OF
25N FROM 68W-77W. ALTHOUGH MODERATE SUBSIDENCE/UPPER LEVEL DRY
AIR COVERS MOST OF THE CARIBBEAN...DIURNAL THUNDERSTORMS ARE
OVER E CUBA...HISPANIOLA...JAMAICA..AND CENTRAL AMERICA WITH THE
STRONGEST STORMS ARE OVER PANAMA AND COSTA RICA. THIS
ANTICYCLONIC FLOW IS ALSO DEVELOPING SCATTERED SHOWERS/
THUNDERSTORMS OVER THE SW CARIBBEAN S OF 14N W OF 78W.

CENTRAL ATLANTIC/E CARIBBEAN SEA AND THE W TROPICAL ATLANTIC...
DEEP LAYERED TROUGH COVERS THE AREA N OF 8N FROM 46W-65W. THE
AXIS EXTENDS FROM A MID/UPPER LOW NEAR 31N25W S TO 8N58W. AREA
IS DOMINATED BY MODERATE SUBSIDENCE AND DRY AIR AT ALL LAYERS
EXCEPT IN THE IMMEDIATE VICINITY OF THE ASSOCIATED COLD FRONT.
FRONTAL SYSTEM EXTENDS FROM A SURFACE 1010 MB LOW CENTERED NEAR
30N47W WITH AN OCCLUDED FRONT NW TO A TRIPLE POINT 1008 MB LOW
NEAR 30N41W THEN A COLD FRONT EXTENDS S TO 18N51W THEN W TO
17N57W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 60
NM OF LINE 18N51W-17N56W.

E SUBTROPICAL AND TROPICAL ATLANTIC...
BROAD MID/UPPER LEVEL RIDGE COVERS THE TROPICAL ATLC S OF 17N
FROM 20W-46W WITH A MID/UPPER LEVEL RIDGE AXIS EXTENDING NE FROM
17N42W TO BEYOND 32N31W. DIVERGENCE ALOFT IS PRODUCING
CLOUDINESS WITH SCATTERED SHOWERS/ISOLATED THUNDERSTORMS N OF
24N FROM 24W-38W AND OVER THE CENTRAL TROPICAL ATLC FROM 5N-15N
BETWEEN 35W-52W. A MID/UPPER LEVEL TROUGH COVERS THE FAR NE ATLC
N OF 17N E OF 24W WITH AN UPPER LEVEL LOW OVER THE CANARY
ISLANDS. THIS BEING AN UPPER LEVEL LOW IT IS NOT PRODUCING ANY
SIGNIFICANT WEATHER.

$$
WALLACE



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