[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 061709
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT THU AUG 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
1630 UTC.

...TROPICAL WAVES...

A TROPICAL WAVE IS ALONG 31W S OF 17N MOVING W NEAR 15 KT. THIS
WAVE COINCIDES WITH A DEEP LAYER MOISTURE MAXIMUM OBSERVED IN
TOTAL PRECIPITABLE WATER IMAGERY. SATELLITE IMAGERY AND
SATELLITE DERIVED WINDS INDICATE LOW/MID-LEVEL CYCLONIC FLOW IN
THE VICINITY OF THE WAVE AXIS. NO CONVECTION IS CURRENTLY
ASSOCIATED WITH THIS WAVE.

A TROPICAL WAVE IS ALONG 47W/48W S OF 15N MOVING W 15-20 KT.
WAVE POSITION IS BASED ON CONTINUITY. THIS WAVE IS CURRENTLY
UNDER A DRY SAHARAN AIR LAYER INHIBITING DEEP CONVECTION ALONG
THE WAVE AXIS.

A TROPICAL WAVE IS ALONG 65W S OF 18N MOVING W NEAR 15 KT. THIS
WAVE COINCIDES WITH A DEEP LAYER MOISTURE MAXIMUM OBSERVED IN
TOTAL PRECIPITABLE WATER IMAGERY. NO DEEP CONVECTION IS
CURRENTLY ASSOCIATED WITH THIS WAVE. HOWEVER...SCATTERED SHOWERS
ARE FROM 12N-18N BETWEEN 63W-67W.

A TROPICAL WAVE IS ALONG 79W/80W S OF 20N MOVING W NEAR 15 KT.
THIS WAVE LIES IN A BROAD AREA OF DEEP LAYER MOISTURE OBSERVED
IN TOTAL PRECIPITABLE WATER IMAGERY. THIS WAVE IS UNDER A
DIFFLUENT PATTERN ALOFT ENHANCING SCATTERED MODERATE CONVECTION
FROM 9N-11N BETWEEN 77W-83W. SCATTERED SHOWERS ARE ALSO FROM
17N-23N BETWEEN 77W-82W.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 12N15W 10N23W 12N35W 9N46W 7N55W
9N61W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM
9N-14N BETWEEN 16W-24W. SCATTERED MODERATE CONVECTION IS FROM
13N-15N BETWEEN 33W-35W. A SURFACE TROUGH IS EMBEDDED IN THE
ITCZ EXTENDING FROM 16N37W TO 8N42W.SCATTERED MODERATE/ISOLATED
STRONG CONVECTION IS FROM 11N-14N BETWEEN 39W-43W...ENHANCED BY
THE SURFACE TROUGH.

...DISCUSSION...

GULF OF MEXICO...
A SURFACE TROUGH IS ACROSS THE FAR NE GULF OF MEXICO EXTENDING
FROM A SURFACE LOW NE OF THE DISCUSSION AREA TO 31N85W...AND
ACROSS THE FLORIDA PANHANDLE TO 30N89W. AN UPPER LEVEL TROUGH
ACROSS THE ERN CONUS SUPPORTS THE SURFACE TROUGH. SURFACE
CONVERGENCE NEAR THE TROUGH IS SUPPORTING SCATTERED
SHOWERS/THUNDERSTORMS FROM 28N-30N BETWEEN 84W-88W. ISOLATED
SHOWERS/THUNDERSTORMS ARE ALSO ACROSS MUCH OF THE CENTRAL GULF
FROM 23N-25N BETWEEN 86-95W DUE TO AN UPPER LEVEL DIFFLUENCE
PATTERN BETWEEN THE UPPER LEVEL TROUGH OVER THE ERN CONUS AND A
PAIR OF UPPER LEVEL RIDGES OVER THE NW GULF AND SE GULF. A
SECOND SURFACE TROUGH IS ACROSS S FLORIDA FROM 24N83W TO 28N80W.
SURFACE CONVERGENCE NEAR THIS TROUGH IS SUPPORTING SCATTERED
SHOWERS/THUNDERSTORMS ACROSS THE SE GULF AND STRAITS OF FLORIDA
FROM 23N-27N E OF 83W. EXPECT SHOWERS/THUNDERSTORMS TO CONTINUE
OVER THE SE GULF.

CARIBBEAN SEA...
AN UPPER LEVEL DIFFLUENT PATTERN IS OVER THE NW CARIBBEAN
BETWEEN AN UPPER LEVEL LOW OVER THE YUCATAN PENINSULA NEAR
21N88W AND AN UPPER LEVEL HIGH OVER THE NRN BAHAMAS NEAR 26N78W.
THIS UPPER LEVEL DIFFLUENCE IS GENERATING SCATTERED
SHOWERS/THUNDERSTORMS ACROSS THE NW CARIBBEAN FROM 19N-23N
BETWEEN 81W-88W. THIS ACTIVITY IS ALSO ENHANCED BY THE TROPICAL
WAVE ALONG 79W/80W. SCATTERED SHOWERS/THUNDERSTORMS ARE ALSO
ACROSS THE SW CARIBBEAN S OF 12N BETWEEN 77W-84W DUE TO UPPER
LEVEL DIFFLUENCE BETWEEN AN UPPER LEVEL RIDGE OVER CENTRAL
AMERICA AND AN UPPER LEVEL LOW OFF THE COAST OF COLUMBIA NEAR
13N73W. THIS ACTIVITY IS ALSO ENHANCED BY THE TROPICAL WAVE
ALONG 79W/80W. THE CENTRAL CARIBBEAN IS EXPERIENCING GENERALLY
FAIR WEATHER BETWEEN 70W-77W DUE TO DRY AIR AND SUBSIDENCE
ALOFT. IN THE ERN CARIBBEAN...A TROPICAL WAVE ALONG 65W IS
SUPPORTING SCATTERED SHOWERS FROM 12N-18N BETWEEN 63W-67W. UPPER
LEVEL DIFFLUENCE BETWEEN AN UPPER LEVEL LOW N OF PUERTO RICO
NEAR 23N67W AND AN UPPER LEVEL HIGH E OF THE LESSER ANTILLES
NEAR 16N54W ALONG WITH MOIST SWLY FLOW ALOFT ARE ALSO SUPPORTING
THIS SHOWER ACTIVITY...AS WELL AS AN AREA OF SCATTERED
SHOWERS/THUNDERSTORMS OVER THE WINDWARD ISLANDS FROM 12N-15N
BETWEEN 61W-63W. FRESH TO STRONG TRADE WINDS ARE ACROSS THE ERN
AND SW CARIBBEAN WITH THE HIGHEST WINDS NEAR THE COAST OF
COLUMBIA.

ATLANTIC OCEAN...
SCATTERED SHOWERS/THUNDERSTORMS ARE ACROSS THE NW ATLC NW OF A
LINE FROM 26N80W TO 32N73W. THIS ACTIVITY IS ENHANCED BY UPPER
LEVEL DIFFLUENCE BETWEEN AN UPPER LEVEL TROUGH OVER THE ERN
CONUS AND AN UPPER LEVEL HIGH OVER THE NRN BAHAMAS NEAR 26N78W.
NEAR THE S FLORIDA COAST THE SHOWER ACTIVITY IS ALSO ENHANCED BY
SURFACE CONVERGENCE NEAR A SURFACE TROUGH EXTENDING FROM 26N82W
TO 28N80W. A SURFACE TROUGH IS ALSO N OF HISPANIOLA EXTENDING
FROM 21N69W TO 30N67W. THIS TROUGH IS SUPPORTED BY AN UPPER
LEVEL LOW NEAR 23N67W. SCATTERED SHOWERS ARE WITHIN 150 NM
EITHER SIDE OF THE SURFACE TROUGH. ELSEWHERE ACROSS THE ATLC...A
BROAD SURFACE RIDGE DOMINATES ANCHORED BY A 1027 MB SURFACE HIGH
NEAR 34N48W BRINGING GENERALLY FAIR WEATHER ACROSS THE REMAINDER
OF THE BASIN. IN THE UPPER LEVELS...AN UPPER LEVEL HIGH IS E OF
THE LESSER ANTILLES NEAR 16N54W. AN UPPER LEVEL LOW IS NEAR
25N42W. THE REMAINDER OF THE TROPICAL ATLC IS UNDER A BROAD
UPPER LEVEL RIDGE ENHANCING CONVECTION ALONG THE ITCZ.
AREA NEAR 35N48W.

$$
WALTON





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