[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 130527
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT THU AUG 13 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
0500 UTC.

...SPECIAL FEATURES...
TROPICAL DEPRESSION TWO IS CENTERED NEAR 14.0N 36.3W OR ABOUT
800 MILES...1285 KM...WEST OF THE SOUTHERNMOST CAPE VERDE
ISLANDS AT 13/0300 UTC MOVING W AT 12 KT. ESTIMATED MINIMUM
CENTRAL PRESSURE IS 1006 MB. MAXIMUM SUSTAINED WIND SPEED IS 30
KT WITH GUSTS TO 40 KT. WWD MOTION IS EXPECTED TO CONTINUE OVER
THE NEXT FEW DAYS. THE DEPRESSION APPEARS TO BE WEAKENING AT
THIS TIME AS LITTLE DEEP CONVECTION IS CURRENTLY NOTED NEAR THE
SYSTEM...BUT IT STILL HAS THE POTENTIAL TO BECOME A TROPICAL
STORM IN A DAY OR TWO. SEE LATEST NHC FORECAST ADVISORY UNDER
AWIPS/WMO HEADERS MIATCMAT2/WTNT22 FOR MORE DETAILS.

...TROPICAL WAVES...
A TROPICAL WAVE IS APPROACHING THE CAPE VERDE ISLANDS EXTENDING
FROM 17N22W TO 6N19W MOVING W NEAR 15 KT. CURRENT SATELLITE
IMAGERY INDICATES LOW-LEVEL CYCLONIC TURNING NEAR 12N. THE WAVE
ALSO COINCIDES WITH A DEEP LAYER MOISTURE MAXIMUM OBSERVED IN
TOTAL PRECIPITABLE WATER IMAGERY. SCATTERED MODERATE/ISOLATED
STRONG CONVECTION IS W OF THE WAVE AXIS FROM 9N-13N BETWEEN
21W-25W.

A TROPICAL WAVE EXTENDS FROM 20N67W TO 11N64W AFFECTING PUERTO
RICO AND THE LEEWARD ISLANDS MOVING W 15-20 KT. THIS WAVE HAS
BEEN RELOCATED FARTHER W THAN ITS CURRENT MOTION SUGGESTS FROM
ITS PREVIOUS LOCATION. THIS IS BASED ON RECENT QUIKSCAT DATA
FROM 2220 UTC INDICATING LOW LEVEL CYCLONIC TURNING ALONG
64W...UPPER AIR TIME SECTIONS FROM SAN JUAN INDICATING A SURGE
IN RELATIVE HUMIDITY AS THE WAVE APPROACHES...AS WELL AS
INCREASED WIND SPEEDS BEHIND THE WAVE. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS FROM 17N-22N BETWEEN
62W-68W.

A TROPICAL WAVE IS ALONG 73W S OF 21N MOVING W NEAR 20 KT.
CURRENT POSITION IS BASED ON CONTINUITY. THE WAVE DIRECTLY UNDER
AN UPPER LEVEL LOW CENTERED NEAR 20N73W WHICH IS PROVIDING
SUBSIDENCE ALOFT LIMITING CONVECTION NEAR THE WAVE. ISOLATED
SHOWERS ARE NOTED OVER WRN HISPANIOLA.

A TROPICAL WAVE IS ALONG 86W/87W S OF 21N MOVING W NEAR 20 KT.
THE WAVE COINCIDES WITH A DEEP LAYER MOISTURE MAXIMUM OBSERVED
IN TOTAL PRECIPITABLE WATER IMAGERY. ISOLATED MODERATE
CONVECTION IS FROM 14N-17N BETWEEN 86W-89W.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 12N16W 11N25W 13N37W 10N47W
13N60W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM
8N-15N BETWEEN 14W-17W. SCATTERED MODERATE CONVECTION IS FROM
6N-8N BETWEEN 26W-28W...AND FROM 9N-10N BETWEEN 36W-40W.

...DISCUSSION...

GULF OF MEXICO...
A SURFACE TROUGH IS ACROSS THE GULF OF MEXICO FROM A 1013 MB LOW
N OF FLORIDA NEAR 31N82W EXTENDING ALONG 27N87W 26N95W. THE
TROUGH IS SUPPORTED BY AN UPPER LEVEL TROUGH ACROSS THE ERN
CONUS...AND A SHORT WAVE UPPER LEVEL TROUGH EXTENDING FROM NRN
FLORIDA NEAR 30N82W TO 25N87W. UPPER LEVEL DIFFLUENCE ALONG WITH
SURFACE CONVERGENCE NEAR THE SURFACE TROUGH ARE SUPPORTING
ISOLATED SHOWERS/THUNDERSTORMS ACROSS MUCH OF THE CENTRAL GULF
WITH 100 NM EITHER SIDE OF THE TROUGH AXIS. A LARGE CLUSTER OF
SCATTERED SHOWERS/THUNDERSTORMS ARE IN THE FAR NW GULF N OF 27N
W OF 93W. THIS ACTIVITY IS SUPPORTED BY A STATIONARY FRONT N OF
THE AREA EXTENDING ACROSS LOUISIANA AND ERN TEXAS...AS WELL AS
UPPER LEVEL DIFFLUENCE BETWEEN THE UPPER LEVEL TROUGH OVER THE
ERN GULF AND AN UPPER LEVEL RIDGE OVER TEXAS AND NRN MEXICO.
SCATTERED SHOWERS/THUNDERSTORMS ARE ACROSS THE BAY OF CAMPECHE S
OF 20N BETWEEN 90W-95W SUPPORTED BY UPPER LEVEL DIFFLUENCE
BETWEEN AN UPPER LEVEL RIDGE CENTERED E OF THE YUCATAN PENINSULA
NEAR 18N86W AND AN UPPER LEVEL TROUGH CENTERED S OF MEXICO NEAR
16N101W. EXPECT THE SURFACE TROUGH TO REMAIN ACROSS THE CENTRAL
GULF...AND A TROPICAL WAVE E OF THE YUCATAN PENINSULA TO REACH
THE SW GULF LATER TODAY.


CARIBBEAN SEA...
THREE TROPICAL WAVES ARE AFFECTING THE CARIBBEAN SEA AND CENTRAL
AMERICA...SEE ABOVE. ISOLATED SHOWERS/THUNDERSTORMS ARE ACROSS
CUBA AND THE ADJACENT WATERS DUE TO UPPER LEVEL DIFFLUENCE
BETWEEN THE SHORTWAVE UPPER LEVEL TROUGH OVER THE ERN GULF AND
AN UPPER LEVEL HIGH E OF THE YUCATAN PENINSULA NEAR 18N86W.
STRONG SUBSIDENCE ALOFT IS OVER THE CENTRAL CARIBBEAN INFLUENCED
BY CONVERGENCE NEAR AN UPPER LEVEL LOW CENTERED OVER HISPANIOLA
NEAR 20N73W...INHIBITING CONVECTION NEAR THE TROPICAL WAVE ALONG
73W. UPPER LEVEL DIFFLUENCE BETWEEN THE UPPER LEVEL LOW AND AN
UPPER LEVEL RIDGE E OF 65W IS SUPPORTING CONVECTION NEAR THE
TROPICAL WAVE IN THE ERN CARIBBEAN. MODERATE TO FRESH TRADEWINDS
ARE OVER MUCH OF THE BASIN...BECOMING STRONG NEAR THE COAST OF
COLUMBIA.  EXPECT SHOWERS/ISOLATED THUNDERSTORMS OVER THE
CARIBBEAN DUE TO THE TROPICAL WAVES OVER THE NEXT 24 HOURS.

ATLANTIC OCEAN...
SCATTERED SHOWERS/THUNDERSTORMS ARE ACROSS THE FAR W ATLC N OF
27N W OF 78W DUE TO SURFACE CONVERGENCE AHEAD OF A STATIONARY
FRONT N OF THE DISCUSSION AREA EXTENDING FROM A 1013 MB SURFACE
LOW N OF FLORIDA NEAR 31N82W. UPPER LEVEL DIFFLUENCE BETWEEN AN
UPPER LEVEL TROUGH W OF 78W AND AN UPPER LEVEL RIDGE CENTERED
NEAR 32N68W IS ALSO SUPPORTING THE SHOWER ACTIVITY. SCATTERED
SHOWERS/THUNDERSTORMS ARE N OF THE LEEWARD ISLANDS AND PUERTO
RICO ASSOCIATED WITH A TROPICAL WAVE IN THE ERN CARIBBEAN...SEE
ABOVE. A SURFACE TROUGH EXTENDS FROM 28N74W TO 30N64W SUPPORTING
A FEW ISOLATED SHOWERS ALONG THE TROUGH AXIS NEAR 30N64W.
ISOLATED SHOWERS/THUNDERSTORMS ARE FROM 27N-32N BETWEEN 49W-55W
DUE TO UPPER LEVEL DIFFLUENCE BETWEEN THE UPPER LEVEL HIGH NEAR
32N68W AND AN UPPER LEVEL LOW NEAR 28N44W. ELSEWHERE ACROSS THE
ATLC...A BROAD SURFACE RIDGE DOMINATES ANCHORED BY A 1027 MB
HIGH NEAR 38N26W. A BROAD UPPER LEVEL RIDGE DOMINATES THE ERN
ATLC E OF 37W.

$$
WALTON





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