[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 031718
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT MON AUG 03 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 1600 UTC.

...TROPICAL WAVES...

A TROPICAL WAVE HAS BEEN ADDED TO THE 1200 UTC ANALYSIS ALONG
19W/20W S OF 18N MOVING W NEAR 15 KT. THE UPPER-AIR TIME SECTION
FROM DAKAR INDICATES THE WAVE PASSING NEAR 17.5W AROUND 0000
UTC ON  08/03. THIS WAVE COINCIDES WITH A DEEP LAYER MOISTURE
MAXIMUM ON TOTAL PRECIPITABLE WATER IMAGERY. VISIBLE SATELLITE
IMAGERY ALSO INDICATES LOW-LEVEL CYCLONIC FLOW NEAR THE VICINITY
OF THE WAVE AXIS. SCATTERED MODERATE/ISOLATED STRONG CONVECTION
IS FROM 12N-16N BETWEEN 17W-21W.

A TROPICAL WAVE EXTENDS ALONG 24N44W 18N43W 13N40W 8N40W MOVING
W NEAR 15 KT. VISIBLE SATELLITE IMAGERY INDICATES A WELL-DEFINED
INVERTED-V PATTERN IN THE LOW CLOUD STRUCTURE. THIS WAVE ALSO
COINCIDES WITH A DEEP LAYER MOISTURE MAXIMUM OBSERVED IN TOTAL
PRECIPITABLE WATER IMAGERY. A DRY SAHARAN AIR LAYER IS E OF THE
WAVE AXIS INHIBITING ANY DEEP CONVECTION.

A TROPICAL WAVE IS ALONG 62W S OF 18N MOVING W NEAR 15 KT. THE
NORTHERN PORTION OF THIS WAVE HAS FRACTURED OFF TO FORM A TROUGH
CURRENTLY W OF PUERTO RICO EXTENDING FROM 22N66W TO 18N68W. THIS
WAVE LIES W OF A DEEP LAYER MOISTURE MAXIMUM OBSERVED IN TOTAL
PRECIPITABLE WATER IMAGERY. THIS WAVE IS CURRENTLY UNDER AN AREA
OF DRY AIR AND SUBSIDENCE ALOFT LIMITED ANY DEEP CONVECTION
NEAR THE WAVE.

A TROPICAL WAVE IS ALONG 97W S OF 22N MOVING W NEAR 20 KT. THIS
WAVE IS WITHIN A BROAD AREA OF DEEP LAYER MOISTURE OBSERVED IN
TOTAL PRECIPITABLE WATER IMAGERY. THE MAJORITY OF THIS WAVE LIES
IN THE E PACIFIC...SEE THE TWDEP FOR MORE DETAILS.

...THE ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 13N15W 9N28W 12N38W 10N50W
11N62W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM
7N-11N BETWEEN 26W-31W. ISOLATED MODERATE CONVECTION IS WITHIN
100 NM EITHER SIDE OF THE AXIS BETWEEN 46W-53W.

...DISCUSSION...

THE GULF OF MEXICO...
A BROAD SURFACE RIDGE WITH AXIS ALONG 28N COVERS THE MAJORITY OF
THE GULF OF MEXICO BRINGING GENERALLY FAIR WEATHER ACROSS THE
AREA. HOWEVER...ISOLATED SHOWERS/THUNDERSTORMS ARE ACROSS THE
NRN GULF N OF 28N E OF 88W GENERATED BY UPPER LEVEL DIFFLUENCE
BETWEEN AN UPPER LEVEL RIDGE OVER THE MAJORITY OF THE GULF
CENTERED OVER SRN TEXAS NEAR 28N98W AND AN UPPER LEVEL TROUGH
OVER THE ERN CONUS. AN UPPER LEVEL TROUGH IS OVER THE SE GULF
CENTERED AROUND AN UPPER LEVEL LOW S OF MEXICO NEAR 14N95W. A
TROPICAL WAVE IS IN THE BAY OF CAMPECHE ALONG 97W...BUT NO
SHOWER ACTIVITY IS CURRENTLY ASSOCIATED WITH IT. ANTICYCLONIC
SURFACE FLOW IS PRESENT AROUND THE SURFACE RIDGE WITH WINDS
REACHING 15 KT ACROSS THE WRN GULF. EXPECT THE SURFACE RIDGE TO
PERSIST...AND A WEAK FRONTAL TROUGH WILL DIP INTO THE EXTREME NE
GULF TUE DISSIPATING BY WED.

THE CARIBBEAN SEA...
AN UPPER LEVEL TROUGH IS OVER THE NW CARIBBEAN CENTERED AROUND
AN UPPER LEVEL LOW S OF MEXICO NEAR 14N95W. UPPER LEVEL
DIFFLUENCE BETWEEN THE UPPER LEVEL TROUGH AND THE UPPER LEVEL
RIDGE OVER THE GULF OF MEXICO IS SUPPORTING ISOLATED
SHOWERS/THUNDERSTORMS OVER THE NW CARIBBEAN FROM 16N-22N BETWEEN
79W-89W. ISOLATED SHOWERS/THUNDERSTORMS ARE ALSO IN THE SW
CARIBBEAN FROM 10N-13N W OF 82W INFLUENCED BY THE PROXIMITY OF
THE E PACIFIC ITCZ. A SURFACE TROUGH IS JUST W OF PUERTO RICO
EXTENDING FROM 18N68W INTO THE ATLC. THIS TROUGH FORMED AS A
FRACTURED PORTION OF THE TROPICAL WAVE W OF THE LESSER ANTILLES
ALONG 62W. SURFACE CONVERGENCE NEAR THE TROUGH IS SUPPORTING
SOME ISOLATED SHOWERS S OF THE HISPANIOLA N OF 17N BETWEEN
68W-70W. ELSEWHERE ACROSS THE CARIBBEAN...DRY AIR AND SUBSIDENCE
ALOFT ARE SUPPORTING GENERALLY FAIR WEATHER AT THE SURFACE.
FRESH TO STRONG TRADEWINDS ARE PRESENT ACROSS MUCH OF THE
CARIBBEAN WITH THE STRONGEST WINDS NEAR THE COAST OF COLUMBIA.
EXPECT THE TROPICAL WAVE ALONG 62W TO PROPAGATE WWD ACROSS THE
CARIBBEAN.

THE ATLANTIC OCEAN...
SCATTERED SHOWERS/THUNDERSTORMS ARE OVER THE NW ATLC N OF 28N W
OF 77W DUE TO SURFACE CONVERGENCE NEAR A SURFACE TROUGH N OF THE
DISCUSSION AREA. THIS SHOWER ACTIVITY IS ALSO ENHANCED BY UPPER
LEVEL DIFFLUENCE BETWEEN THE UPPER LEVEL RIDGE OVER THE GULF OF
MEXICO AND THE UPPER LEVEL TROUGH OVER THE ERN CONUS. ISOLATED
SHOWERS/THUNDERSTORMS ARE ALSO FROM 20N-30N BETWEEN 60W-70W.
THIS ACTIVITY IS ENHANCED BY SURFACE CONVERGENCE NEAR A SURFACE
TROUGH EXTENDING FROM W OF PUERTO RICO NEAR 18N68W TO
22N66W...AND BY UPPER LEVEL DIFFLUENCE BETWEEN AN UPPER LEVEL
LOW NEAR 29N63W AND A BROAD UPPER LEVEL RIDGE COVERING THE
TROPICAL ATLC. ELSEWHERE ACROSS THE ATLC...A BROAD SURFACE RIDGE
DOMINATES ANCHORED BY A 1029 MB SURFACE HIGH NEAR 36N50W
BRINGING GENERALLY FAIR WEATHER ACROSS THE BASIN. ACROSS THE
TROPICAL ATLC...A BROAD UPPER LEVEL RIDGE COVERS THE AREA S OF
25N CENTERED NEAR 18N43W ENHANCING CONVECTION ALONG THE ITCZ.

$$
WALT0N



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