[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 180516
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT THU JUN 18 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0445 UTC.

...TROPICAL WAVES...

A TROPICAL WAVE IS ALONG 40W/41W S OF 8N MOVING W NEAR 15 KT. THIS
WAVE COINCIDES WITH A RELATIVELY LOW AMPLITUDE MAXIMUM IN DEEP LAYER
MOISTURE BASED ON TOTAL PRECIPITABLE WATER IMAGERY. ISOLATED
MODERATE CONVECTION IS FROM 7N-9N BETWEEN 40W-43W.

A TROPICAL WAVE IS ALONG 90W/91W S OF 20N MOVING W 10-15 KT. THIS
WAVE ALSO COINCIDES WITH A MAXIMUM IN DEEP LAYER MOISTURE BASED ON
TOTAL PRECIPITABLE WATER IMAGERY. THIS WAVE IS SUPPORTING SCATTERED
MODERATE/ ISOLATED STRONG CONVECTION FROM 13N-20N BETWEEN 87W-95W
INCLUDING PORTIONS OF THE YUCATAN PENINSULA...CENTRAL AMERICA AND
INTO THE E PACIFIC WATERS. THIS CONVECTION IS BEING SUPPORTED BY
UPPER LEVEL DIFFLUENCE AROUND AN UPPER LEVEL HIGH OVER S BAY OF
CAMPECHE.

...THE ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 11N14W 7N22W 6N30W 5N38W AND INTO
THE NE COAST OF BRAZIL NEAR THE EQUATOR ALONG 49W. SCATTERED
MODERATE CONVECTION IS FROM 5N-8N BETWEEN 13W-17W. NUMEROUS
MODERATE/SCATTERED STRONG CONVECTION IS FROM 6N-11N BETWEEN 19W-22W.
SCATTERED MODERATE CONVECTION IS FROM 7N-9N BETWEEN 24W-27W AND FROM
4N-6N BETWEEN 34W-36W.

...DISCUSSION...

GULF OF MEXICO...
A SURFACE TROUGH EXTENDS UP THE FLORIDA PENINSULA FROM 26N81W TO
31N83W. LOW LEVEL CONVERGENCE ALONG WITH UPPER LEVEL DIFFLUENCE AT
THE BASE OF AN UPPER LEVEL TROUGH WITH AXIS EXTENDING FROM THE FAR W
ATLC INTO THE E GULF OF MEXICO TO NEAR 26N85W ARE SUPPORTING
SCATTERED SHOWERS AND THUNDERSTORMS ALONG THE W COAST OF FLORIDA AND
THE ADJACENT COASTAL WATERS FROM 24N-30N BETWEEN 81W-83W. A TROPICAL
WAVE OVER THE YUCATAN PENINSULA...SEE ABOVE... ALONG WITH UPPER
LEVEL DIFFLUENCE AROUND AN UPPER LEVEL HIGH NEAR 18N93W ARE
SUPPORTING SCATTERED SHOWERS AND THUNDERSTORMS OVER THE BAY OF
CAMPECHE S OF 20N BETWEEN 91W-95W. ELSEWHERE...A STATIONARY 1017 MB
HIGH NEAR 27N88W DOMINATES THE REMAINDER OF THE GULF OF MEXICO
BRINGING FAIR WEATHER ACROSS THE AREA. AN UPPER LEVEL RIDGE EXTENDS
FROM THE UPPER LEVEL HIGH OVER THE S BAY OF CAMPECHE ACROSS THE W
GULF OF MEXICO TO THE TEXAS COAST NEAR 29N96W UP TO THE UNITED
STATES GREAT PLAINS. THIS UPPER LEVEL RIDGING IS PROVIDING DRY AIR
AND SUBSIDENCE SUPPORTING THE SURFACE HIGH. ANTICYCLONIC FLOW AROUND
THE SURFACE HIGH IS AFFECTING MUCH OF THE GULF...WITH SE WINDS OF
15-20 KT OCCURRING ACROSS PORTIONS OF THE NW GULF W OF 95W. EXPECT A
SERIES OF WEAK COLD FRONTS TO MOVE THROUGH THE NE WATERS THROUGH THE
WEEKEND.

CARIBBEAN SEA...
A UPPER LEVEL TROUGH IS PRESENT OVER THE CENTRAL CARIBBEAN WITH AN
AXIS EXTENDING FROM AN UPPER LEVEL LOW N OF HISPANIOLA TO 20N71W
15N73W TO 6N76W OVER NW COLUMBIA. UPPER LEVEL NORTH-NORTHWESTERLY
FLOW BETWEEN THE UPPER LEVEL HIGH OVER THE S BAY OF CAMPECHE AND
THIS UPPER LEVEL TROUGH IS DRAWING DRY AIR AND SUBSIDENCE TO THE
CENTRAL GULF RESULTING IN GENERALLY FAIR WEATHER.
HOWEVER...ATMOSPHERIC INSTABILITY IS SUPPORTING ISOLATED
SHOWERS/POSSIBLE THUNDERSTORMS ACROSS THE NW CARIBBEAN N OF 16N W OF
77W. UPPER LEVEL DIFFLUENCE AT THE BASE OF THE UPPER LEVEL TROUGH IS
SUPPORTING SCATTERED SHOWERS AND THUNDERSTORMS IN THE S CARIBBEAN
OFF THE COAST OF PANAMA S OF 11N BETWEEN 79W-82W.

ATLANTIC OCEAN...
AN UPPER LEVEL TROUGH OVER THE SW NORTH ATLC IS ASSOCIATED WITH A
STATIONARY FRONT EXTENDING FROM N OF THE DISCUSSION AREA TO 31N81W
TO 1013 MB SURFACE LOW NEAR 32N76W CONTINUING TO 31N68W...AND A COLD
FRONT EXTENDING FROM 31N68W TO 32N64W TO NE OF THE DISCUSSION AREA.
A SHORTWAVE UPPER LEVEL TROUGH EMBEDDED IN THE AFOREMENTIONED
LONGWAVE TROUGH IS OVER THE FAR W ATLC SUPPORTING A SURFACE TROUGH
EXTENDING FROM 28N79W TO 31N75W. LOW LEVEL CONVERGENCE ASSOCIATED
WITH THE TROUGH IS SUPPORTING SCATTERED SHOWERS AND THUNDERSTORMS
WITHIN 60 NM OF THE TROUGH. ACROSS THE MAJORITY OF THE CENTRAL AND E
ATLC A BROAD SURFACE RIDGE DOMINATES ANCHORED TO A 1027 MB SURFACE
HIGH N OF THE DISCUSSION AREA NEAR 37N33W. THIS SURFACE RIDGE IS
PROVIDING FAIR WEATHER ACROSS THE REMAINDER OF THE GULF AND IS
SUPPORTED BY BROAD UPPER LEVEL RIDGING OVER THE MAJORITY OF THE
TROPICAL ATLC. HOWEVER...A DEEP LAYER LOW OVER THE E ATLC IS
ASSOCIATED WITH A 1013 MB SURFACE LOW N OF THE CANARY ISLANDS NEAR
30N18W. LOW LEVEL CONVERGENCE NEAR THIS SURFACE LOW IS SUPPORTING
ISOLATED SHOWERS N OF 31N BETWEEN 17W-20W.

$$
WALTON



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