[Tropical] Tropical Weather Discussion

[Nashville EMWIN]

AXNT20 KNHC 232300
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT MON 23 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
2245 UTC.

...TROPICAL WAVES...
TROPICAL WAVE PREVIOUSLY ALONG 27W IS REPOSITIONED A BIT FARTHER
E ALONG 25W/26W S OF 17N MOVING W 10 KT.  SATELLITE PICTURES
INDICATE A BROAD 1010 MB LOW HAS FORMED ALONG THE WAVE NEAR
10.5N.  TSTM ACTIVITY HAS BEEN INCREASING IN THE PAST FEW HOURS
WITH SOME EVIDENCE OF BANDING FEATURES FORMING.  COMPUTER MODELS
CONTINUE TO PINPOINT THIS WAVE AS THE NEXT FEATURE WITH
POTENTIAL FOR TROPICAL CYCLONE DEVELOPMENT.  WIDELY SCATTERED
MODERATE FROM 9N-12N BETWEEN 25W-31W.

TROPICAL WAVE PREVIOUSLY ALONG 43W IS REPOSITIONED W TO 48W S OF
16N MOVING W 20 KT.  THIS IS A CONFUSING WAVE WITH ONE PIECE
APPARENTLY BREAKING OFF TO FORM A CENTRAL ATLC TROUGH ALONG
ABOUT 39W WHILE ANOTHER FEATURE CAN BE TRACKED IN THE ITCZ.
COMPUTER MODELS INDICATE THE SOUTHERN PORTION OF THE WAVE...
DENOTED BY THE INCREASE IN ITCZ CONVECTION... WILL MOVE INTO THE
WINDWARD ISLANDS WED WITH ENHANCED RAIN SHOWERS.

W CARIBBEAN TROPICAL WAVE IS ALONG 86W S OF 20N MOVING W 20 KT.
ANOTHER WET DAY TODAY FOR CENTRAL AMERICA WITH A LARGE AREA OF
WIDELY SCATTERED SHOWERS/TSTMS OVER N COSTA RICA N THRU HONDURAS.

...ITCZ...
ITCZ IS CENTERED ALONG 9N14W 6N26W 10N37W 10N47W 6N57W.  WIDELY
SCATTERED MODERATE FROM 7N-9.5N BETWEEN 32W-36W.  ISOLATED
MODERATE WITHIN 60 NM OF AXIS E OF 16W.

...DISCUSSION...
GULF OF MEXICO...
WHILE A COUPLE OF TROPICAL CYCLONES HAVE FORMED IN THE EPAC...
ALL IS QUIET FOR NOW OVER THE WHOLE AREA.  THIS COULDN'T BE MORE
TRUE IN THE GULF WITH YET ANOTHER DAY OF DEEP-LAYERED HIGH
PRESSURE THRU THE CENTRAL GULF WITH AXIS FROM BROWNSVILLE TO
TAMPA.  TSTMS ARE FORMING ALONG THE SEABREEZE IN THE NORTHERN
AND E GULF COAST STATES WITH NLY WIND CARRYING THE CIRRUS DEBRIS
CLOUDS OVER GULF WATER.  UPPER TROUGH IS ALONG THE E COAST OF
THE USA FROM N CAROLINA TO NE FLORIDA... ENHANCING TSTM
DEVELOPMENT IN CENTRAL FLORIDA.  THIS TROUGH IS FORECAST TO DIG
A BIT... LIKELY INCREASING RAIN CHANCES FOR THE E COAST OF
FLORIDA TOMORROW.  AN UPPER TROUGH IS IN THE BAY OF CAMPECHE
WITH HIGHER MOISTURE VALUES E OF 94W ASSISTING DIURNAL TSTMS.

CARIBBEAN SEA...
UPPER RIDGING IS IN CONTROL W OF 80W S OF 19N WITH A DIFFLUENT
ENVIRONMENT COMBINED WITH A TROPICAL WAVE CAUSING A WET DAY OVER
CENTRAL AMERICA.  THE REST OF THE AREA IS UNDER THE INFLUENCE OF
A STRONG MID-OCEANIC TROUGH ENTERING THE AREA IN THE NE LEEWARD
ISLANDS ACROSS THE GREATER ANTILLES INTO A CLOSED UPPER LOW NEAR
E CUBA.  W TO NW FLOW ON THE S SIDE OF THE TROUGH IS CAUSING
HIGH SHEAR CONDITIONS FOR THE CARIBBEAN WITH MOISTURE VERY
SPARSE IN THE MID/UPPER LEVELS E OF 70W.  LITTLE CHANGE IS
LIKELY FOR THE NEXT COUPLE DAYS AS THE UPPER TROUGH SETTLES OVER
THE CENTRAL CARIBBEAN.

SUBTROPICAL ATLANTIC OCEAN AND TROPICAL ATLANTIC W OF 50W...
THE WEATHER REMAINS MOSTLY QUIET IN THIS AREA WITH SPECKLES OF
SHOWER ACTIVITY PRESENT.. MOST NUMEROUS IN THE BAHAMAS.  UPPER
RIDGING EXTENDS FROM CENTRAL FLORIDA ENE TO BERMUDA WITH DRY
AIR/SUBSIDENCE S OF THE RIDGE AXIS TO 26N KEEPING THINGS CALM.
1020 MB SURFACE HIGH IS NEAR 27N69W S OF THE UPPER RIDGE AXIS.
THE MID-OCEANIC TROUGH HAS TAKEN UP RESIDENCE IN THE CENTRAL
ATLC WITH TWO BIG UPPER LOWS NEAR 34N53W AND 24N57W COMPRISING
THE TROUGH CONTINUING INTO THE LEEWARD ISLANDS.  THIS FEATURE IS
RATHER DEEP WITH SOME SURFACE REFLECTION AS A WEAK TROUGH IS
PRESENT ALONG 60W N OF 18N.  ISOLATED MODERATE IS N OF 23N
BETWEEN 50W-55W ASSOCIATED WITH LIFT/INSTABILITY ASSOCIATED WITH
THE MID-OCEANIC TROUGH.   CYCLONIC FLOW FROM THE MID-OCEANIC
STRETCHES ALL THE WAY INTO THE DEEP TROPICS WITH MOSTLY S TO SW
FLOW IN THE TROPICAL ATLC AND VERY DRY AIR ALOFT.

SUBTROPICAL ATLANTIC OCEAN E OF 50W....
BENIGN WEATHER IN THE E ATLC WITH AN UPPER HIGH NEAR 27N41W
KEEPING THINGS DRY.  OTHERWISE A WEAKENING UPPER TROUGH ALONG
34N N OF 21N SEPARATES THE AFOREMENTIONED HIGH WITH BROAD
ANTICYCLONIC FLOW IN THE E ATLC.  THE REMNANTS OF DANIELLE ARE N
OF THE AREA NEAR 33N44W WITH OCCASIONAL TSTMS NEAR THE CENTER
BUT SHEAR KEEPS THE SYSTEM FROM FURTHER DEVELOPMENT.

TROPICAL ATLANTIC E OF 50W...
MODERATE/STRONG SUBSIDENCE IS THE RULE W OF 40W KEEPING A LID ON
ANY SIGNIFICANT CONVECTION.  INCREASING MOISTURE IS PRESENT
FARTHER E IN ASSOCIATION WITH A STRONG TROPICAL WAVE W OF THE
CAPE VERDES.   MID/UPPER HIGH IS NEAR 20N34W WITH ELY WINDS AND
RELATIVELY LIGHT SHEAR E OF 40W.  UPPER DIVERGENCE CONTINUES TO
ENHANCE THE CAPE VERDE WAVE WITH CONSIDERABLY MORE TSTM ACTIVITY
TONIGHT THAN LAST NIGHT AT THIS TIME.

$$
BLAKE


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