[Tropical] Tropical Weather Discussion

[Nashville EMWIN]

AXNT20 KNHC 242339
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT TUE 24 AUG 2004

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...WEATHER OBSERVATIONS...RADAR...AND
METEOROLOGICAL ANALYSIS.

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...SPECIAL FEATURE...
A STRONG TROPICAL WAVE IS LOCATED ABOUT 500 NM WEST OF THE
SOUTHERNMOST CAPE VERDE ISLAND ALONG 34W/35W S OF 17N MOVING
WEST 20-25 KT. 1012 MB LOW IS CENTERED ALONG THE WAVE AXIS NEAR
11N. LATEST SATELLITE IMAGERY INDICATES THAT THE TROPICAL
WAVE/LOW HAVE CONTINUED TO BECOME BETTER ORGANIZED WITH
INCREASING CONVECTION AND LOOSELY-ORGANIZED BANDING STRUCTURE
BEGINNING TO DEVELOP.  SCATTERED MODERATE CONVECTION FROM 8N-12N
BETWEEN 33W-38W. VERTICAL SHEAR AND UPPER LEVEL OUTFLOW ARE
EXPECTED TO REMAIN FAVORABLE OVER THE NEXT FEW DAYS AND A
TROPICAL DEPRESSION COULD FORM LATER TONIGHT OR WEDNESDAY AS THE
SYSTEM MOVES WESTWARD.

...TROPICAL WAVES...
TROPICAL WAVE APPROXIMATELY 300 NM E OF BARBADOS ALONG 55W S OF
18N MOVING W NEAR 20 KT. VISIBLE SATELLITE IMAGERY DEPICTS A
LOW-AMPLITUDE WAVE WITH ASSOCIATED PERTURBATION PRIMARILY WITHIN
THE ITCZ.  THIS WAVE WILL LIKELY AFFECT S PORTIONS OF THE
WINDWARD ISLANDS AND N PORTIONS OF VENEZUELA LATER TONIGHT AND
TOMORROW WITH INCREASING SHOWER/THUNDERSTORM ACTIVITY.

...ITCZ...
ITCZ AXIS EMERGES OFF THE COAST OF W AFRICA NEAR DAKAR EXTENDING
SW ALONG 11N30W 8N45W 9N55W INTO S AMERICA OVER N GUYANA TO
5N65W THEN NW OVER PANAMA ALONG 10N80W.  SCATTERED MODERATE
CONVECTION OVER THE SW CARIBBEAN AND PORTIONS OF CENTRAL AMERICA
FROM 8N-13N BETWEEN 80W-86W.

...DISCUSSION...

GULF OF MEXICO...
THE GLFMEX FEATURES STRONG MIDDLE TO UPPER LEVEL RIDGING WITH
AXIS EXTENDING FROM S TEXAS ESE TO W CUBA.  A SHORTWAVE TROUGH
OVER THE SE UNITED STATES AND FLORIDA AND PRODUCED A FAIR AMOUNT
OF AFTERNOON CONVECTION OVER FLORIDA EARLIER TODAY. THIS
ACTIVITY IS NOW WEAKENING WITH SCATTERED RESIDUAL SHOWERS
REMAINING.  FURTHER S...A RETROGRADING MID/UPPER LEVEL LOW
LOCATED OVER S MEXICO NEAR 18N101W IS TAPPING INTO SOME E
PACIFIC MOISTURE AND PRODUCING SCATTERED STRONG CONVECTION OVER
THE ISTHMUS OF TEHUANTEPEC. ELSEWHERE...MOISTURE AND DYNAMICS
ARE LIMITED WITH CONFLUENT FLOW S OF THE UPPER RIDGE AXIS
PRODUCING DRY/TRANQUIL WEATHER.  AT THE SURFACE...SUBTROPICAL
RIDGE EXTENDS ACROSS CENTRAL FLORIDA TO THE SE COAST OF TEXAS.

CARIBBEAN SEA...
MID-OCEANIC TROUGH EXTENDS FROM THE CENTRAL ATLC SWD OVER E
HISPANIOLA TO AN UPPER LOW NEAR 17N73W CONTINUING WEST TO
BELIZE.  INSTABILITY ASSOCIATED WITH THE UPPER TROUGH IS
PRODUCING ENHANCED SHOWER/THUNDERSTORM ACTIVITY OVER
CUBA...HISPANIOLA... AND PUERTO RICO. SOUTH OF THE
TROUGH...MODERATE SUBSIDENCE AND DRY AIR BLANKETS THE AREA TO
SOUTH AND CENTRAL AMERICA WHERE A MID/UPPER LEVEL RIDGE EXTENDS
FROM S MEXICO SEWD INTO COLOMBIA. DIFFLUENT FLOW ALONG THE RIDGE
AXIS COUPLED WITH THE ITCZ OVER PANAMA IS PRODUCING SCATTERED
MODERATE/ISOLATED STRONG CONVECTION FROM GUATEMALA TO PANAMA.

SUBTROPICAL ATLANTIC OCEAN...
THE SUBTROPICAL ATLC FEATURES A LARGE SCALE RIDGE-TROUGH-RIDGE
PATTERN WITH A RIDGE OVER THE W ATLC EXTENDING FROM S FLORIDA
NEWD OVER BERMUDA...MID-OCEANIC TROUGH EXTENDING FROM 30N56W TO
HISPANIOLA...AND BROAD E/W ORIENTED RIDGE OVER THE E ATLC ALONG
18N.  SIGNIFICANT CONVECTION IS PRIMARILY FOCUSED OVER THE W
HALF OF THE ATLC IN ASSOCIATION WITH A SHORTWAVE TROUGH OVER THE
SE UNITED STATES. THE SHORTWAVE TROUGH IS PRODUCING A LARGE AREA
OF CLOUDINESS AND SHOWERS/THUNDERSTORMS POLEWARD OF A LINE FROM
S FLORIDA TO BERMUDA. EARLIER SHOWERS OVER THE BAHAMAS HAVE
WEAKENED. INSTABILITY ASSOCIATED WITH THE MID-OCEANIC TROUGH IS
PRODUCING WIDELY SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS N
OF 25N BETWEEN 53W-63W.  ELSEWHERE OVER THE E ATLC...UPSTREAM
MOISTURE IS RIDING UP AND OVER THE E ATLC RIDGE LEAVING THE AREA
E OF 50W UNDER CONFLUENT FLOW AND DRY AIR.  AT THE
SURFACE...SUBTROPICAL RIDGE ENTERS THE CENTRAL ATLC ALONG 32N45W
SW TO CENTRAL FLORIDA.  WEAK LOW LEVEL TROUGH IS BETWEEN 45W-50W
N OF 20N WITH WIDELY SCATTERED SHOWERS.

TROPICAL ATLANTIC...
THE MAJOR FEATURE OVER THE TROPICAL E ATLC IS A TROPICAL
WAVE ALONG 35W.  A MID-UPPER LEVEL RIDGE POSITIONED N OF THE
WAVE ALONG 18N IS PRODUCING DEEP LAYERED ELY FLOW OVER THE
TROPICAL ATLC AND PROVIDING A FAVORABLE ENVIRONMENT FOR
DEVELOPMENT.  A NEW TROPICAL WAVE EMERGING OFF THE W COAST OF
AFRICA IS PRODUCING ENHANCED ITCZ CONVECTION E OF 20W.
ELSEWHERE...MODERATE SUBSIDENCE AND DRY AIR PREVAILS LIMITING
SIGNIFICANT ACTIVITY.

$$
RHOME







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