[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 061752
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT TUE OCT 06 2009

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS
OF SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST
FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED
ON SATELLITE IMAGERY...METEOROLOGICAL ANALYSIS...WEATHER
OBSERVATIONS...AND RADAR.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 39W S OF 20N MOVING W 10-15 KT. LOW
AMPLITUDE WAVE MOSTLY EMBEDDED WITHIN THE ITCZ AND EMBEDDED
WITHIN A BROAD AREA OF DEEP LAYER MOISTURE AS OBSERVED IN TOTAL
PRECIPITABLE WATER IMAGERY. SATELLITE DERIVED WINDS INDICATE
LOW-LEVEL CYCLONIC CURVATURE IN THE VICINITY OF THE WAVE AXIS.
CLUSTERS OF SCATTERED MODERATE TO ISOLATED STRONG CONVECTION ARE
FROM 5N-11N BETWEEN 34W-47W.

TROPICAL WAVE IS FROM 20N59W THROUGH A 1012 MB LOW NEAR 17N52W
TO 13N55W MOVING NW 15-20 KT. WELL DEFINED LOW LEVEL SWIRL IS
EXPOSED TO THE WEST OF THE CONVECTION DUE TO WESTERLY SHEAR.
SCATTERED STRONG CONVECTION IS WITHIN 45 NM OF LINE FROM 16N51W
TO 18N52W WITH SCATTERED MODERATE/ISOLATED STRONG CONVECTION
COVERING THE REMAINDER OF THE AREA FROM 14N-20N BETWEEN 48W-52W.

TROPICAL WAVE IS ALONG 61W/62W S OF 14N MOVING W NEAR 10 KT.
VERY LOW AMPLITUDE WAVE MOVING INLAND OVER VENEZUELA. WAVE IS
GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS S OF 11N TO
INLAND OVER VENEZUELA BETWEEN 60W-64W INCLUDING THE ISLAND OF
TRINIDAD. ISOLATED SHOWERS AND POSSIBLE THUNDERSTORMS ARE FROM
11N-14N BETWEEN 61W-66W INCLUDING THE WINDWARD ISLANDS.

TROPICAL WAVE IS ALONG 88W S OF 19N MOVING W NEAR 15 KT. WAVE IS
WELL DEFINED IN THE LOW CLOUD FIELD OVER THE GULF OF HONDURAS
BUT IS NOT PRODUCING ANY SHOWER ACTIVITY IN THE CARIBBEAN.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 10N11W 6N27W 7N47W 11N55W. ITCZ
IS BEING DISTORTED BY THE TROPICAL WAVE OVER THE WINDWARD
ISLANDS AND THE WAVE WITH THE 1012 MB LOW. CLUSTERS OF SCATTERED
MODERATE/ISOLATED STRONG CONVECTION ARE WITHIN 125 NM EITHER
SIDE OF THE ITCZ FROM 16W-22W.

...DISCUSSION...

GULF OF MEXICO...
A BROAD UPPER RIDGE ANCHORED OVER E MEXICO CONTINUES TO DOMINATE
THE GULF EXTENDING AN AXIS BETWEEN BROWNSVILLE TEXAS AND TUXPAN
MEXICO ACROSS THE GULF TO THE STRAITS OF FLORIDA. A QUASI-
STATIONARY FRONT REMAINS INLAND OVER THE N GULF COAST STATES
GENERATING ISOLATED SHOWERS OVER THE NE GULF N OF 27N E OF 86W
ACROSS NE FLORIDA. A WEAK 1016 MB HIGH IS ANCHORED OFF THE
FLORIDA COAST NEAR 27N84W GIVING THE REMAINDER OF THE GULF FAIR
WEATHER AND MOSTLY CLEAR SKIES THIS AFTERNOON.

CARIBBEAN SEA...
BROAD UPPER RIDGE THAT COVERS THE GULF EXTENDS OVER THE NW
CARIBBEAN AND A SECOND UPPER RIDGE COVERS THE E CARIBBEAN
ANCHORED OVER NW VENZUELA. A SHARP NARROW UPPER TROUGH EXTENDS
THROUGH THE CENTRAL ATLC ACROSS HISPANIOLA TO OVER JAMAICA THEN
S TO COSTA RICA SPLITTING THE TWO UPPER RIDGES. THE UPPER
RIDGE/WESTERN PORTION OF THE UPPER TROUGH IS USHERING IN DRY
STABLE AIR OVER THE W CARIBBEAN GIVING THE AREA W OF THE TROUGH
MOSTLY CLEAR SKIES. THE UPPER TROUGH COUPLED WITH THE ITCZ THAT
CROSSES THE SW CARIBBEAN FROM COLOMBIA TO THE COSTA RICA/
NICARAGUA BORDER ARE GENERATING SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS S OF 13N W OF 80W TO THE CENTRAL AMERICAN COAST.
FRESH TO STRONG EASTERLY TRADE WINDS COVER MOST OF THE CARIBBEAN
AND COULD BE USHERING IN ISOLATED LOW LEVEL FAST MOVING SHOWERS
ACROSS THE THE AREA.

ATLANTIC OCEAN...
THE BROAD UPPER RIDGE THAT COVERS THE GULF OF MEXICO NARROWS AS
IT EXTENDS INTO THE W ATLC THROUGH THE STRAITS OF FLORIDA ALONG
25N70W TO BEYOND 32N55W ENHANCING ISOLATED SHOWERS WITHIN 150 NM
OF LINE FROM THE N BAHAMA ISLANDS NEAR 26N78W 28N63W TO BEYOND
32N55W. A NARROW UPPER TROUGH ENTERS THE REGION FROM AN UPPER
LOW NEAR 32N41W ALONG 26N54W INTO THE CARIBBEAN ACROSS
HISPANIOLA. A DEEP LAYERED TROUGH COVERS THE E ATLC WITH THE
UPPER TROUGH EXTENDING S TO 24N E OF 30W SUPPORTING A COLD FRONT
THAT EXTENDS TO 31N24W AND CONTINUES AS A SURFACE TROUGH ALONG
29N36W TO 31N48W. ISOLATED SHOWERS ARE POSSIBLE WITHIN 90 NM SE
OF THE FRONT/TROUGH E OF 33W. THE E/W UPPER RIDGE CONTINUES TO
DOMINATE THE TROPICS ANCHORED NEAR 14N35W ENHANCING THE
CONVECTION ASSOCIATED WITH THE TROPICAL WAVES. WEAK SURFACE
RIDGE CUTS A SWATH ACROSS THE REGION MOSTLY BETWEEN 20N-30N WITH
A 1019 MB HIGH IN THE W ATLC NEAR BERMUDA AND A 1021 MB HIGH
NEAR 23N36W.

$$
WALLACE





This weather bulletin was brought to you by:
www.nashvilleweather.net