[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 201734
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT TUE MAY 20 2008

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN
SECTIONS OF SOUTH AMERICA...AND THE 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
1715 UTC.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 48W S OF 11N MOVING W 15 KT. VISIBLE
IMAGERY SHOWS LOW-MID LEVEL CYCLONIC TURNING FOCUSED ALONG THE
AXIS NEAR 6N. SCATTERED SHOWERS AND TSTMS COVER A FAIRLY LARGE
420 NM AREA EITHER SIDE OF THE AXIS FROM 3N-7N...ENHANCED BY A
LARGE AMPLITUDE UPPER TROUGH.

TROPICAL WAVE IS ADJUSTED W ALONG 73W S OF 13N ESTIMATED TO BE
MOVING W 10-15 KT. THIS ADJUSTMENT WAS BASED ON A WESTWARD
MOISTURE SURGE EVIDENT ON THE MIMIC TPW ANIMATION AND FITS WELL
WITH LONG TERM CONTINUITY. REGARDLESS OF THE EXACT LOCATION...
THE WAVE REMAINS WEAK AND IS PRODUCING LITTLE WEATHER INLAND
OVER SOUTH AMERICA.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 8N13W 5N23W 3N35W 5N45W 4N52W.
SCATTERED MODERATE CONVECTION IS WITHIN 150 NM N AND 300 NM S OF
THE AXIS BETWEEN 33W-39W. A LOW-LATITUDE TROPICAL WAVE HAS
LIKELY JUST MOVED OFF THE COAST OF W AFRICA AND IS ENHANCING
SCATTERED MODERATE ISOLATED STRONG CONVECTION FROM 6N-9N BETWEEN
16W-20W. THIS FEATURE WILL BE ADDED TO THE SFC ANALYSIS SOON.

...DISCUSSION...

GULF OF MEXICO...
STRONG SW TO W FLOW ALOFT LIES OVER THE REGION MOISTENING THE
MID AND UPPER LEVELS. THIS UPPER REGIME IN COMBINATION WITH A
LINGERING SFC TROUGH FROM N FLORIDA TO 26N87W IS TRIGGERING
SCATTERED SHOWERS AND TSTMS WITHIN 90 NM S OF THE BOUNDARY E OF
84W...AS NOTED IN LIGHTNING DATA. ELSEWHERE AT THE SFC...RIDGING
FROM THE CENTRAL ATLC EXTENDS INTO THE AREA PROVIDING MAINLY
LIGHT S TO SW WINDS...EXCEPT W TO NW N OF THE AFOREMENTIONED SFC
TROUGH. OVERALL...LITTLE CHANGE IS EXPECTED THROUGH TOMORROW AS
THE UPPER FLOW REMAINS STRONG OUT OF THE SW/W KEEPING THE REGION
FAIRLY MOIST.

CARIBBEAN SEA...
ACTIVE WEATHER LIES OVER THE SW WATERS. IR IMAGERY AND LIGHTNING
DATA INDICATE SCATTERED SHOWERS AND TSTMS DEEPENING AND
EXPANDING OVER THE PAST FEW HOURS FROM 11N-14N BETWEEN 76W-82W.
THE FORCING FOR THIS ACTIVITY INCLUDES A 1010 MB SFC LOW JUST
OFF THE COAST OF SE NICARAGUA AND AN UPPER DIFFLUENT PATTERN ON
THE S SIDE OF A BROAD UPPER RIDGE. NWP MODELS SHOW THIS LOW...OR
ITS ASSOCIATED VORTICITY...MOVING INLAND OVER THE NEXT 24 HOURS.
OTHERWISE...A SUBSIDENT ENVIRONMENT IS IN PLACE ASSOCIATED WITH
A BROAD MID-LEVEL RIDGE CENTERED ROUGHLY NEAR 15N65W...ALLOWING
FAIR WEATHER TO DOMINATE. ELY TRADES OF 20-25 KT ARE BLOWING
OVER THE S CARIB AND THIS IS EXPECTED TO CHANGE LITTLE OVER THE
NEXT 24 HOURS.

ATLANTIC OCEAN...
STRONG WLY FLOW ALOFT...ON THE N SIDE OF BROAD CARIBBEAN
RIDGING...LIES OVER MUCH OF THE W ATLC. THIS FLOW COUPLED WITH A
SHEARED LOW-LEVEL BOUNDARY IS PRODUCING SCATTERED SHOWERS AND
TSTMS WITHIN 240 NM S OF A FRONT ALONG 38N54W 33N66W 34N71W.
OTHERWISE...MAINLY DRY STABLE AIR IS ASSOCIATED WITH THE RIDGE
ALLOWING TRANQUIL WEATHER TO CONTINUE. A LARGE SCALE TROUGH LIES
TO THE E OF THE RIDGE WITH THE AXIS EXTENDING FROM 32N28W TO AN
EMBEDDED UPPER LOW NEAR 26N35W AND WELL SW INTO THE DEEP TROPICS
NEAR 6N51W. SCATTERED SHOWERS AND TSTMS LIE TO THE E OF THE AXIS
FROM 5N-9N BETWEEN 41W-46W LIKELY ENHANCED BY A TROPICAL WAVE IN
THE AREA. UPPER SW FLOW E OF THE AXIS IS TRANSPORTING HIGH LEVEL
MOISTURE ACROSS MUCH OF THE E ATLC...BUT NONE OF IT SEEMS TO BE
SIGNIFICANT. AN UPPER HIGH IS LOCATED OVER W AFRICA NEAR 13N11W
WITH CONVECTION BEING MAINTAINED ON ITS SW PERIPHERY WITHIN THE
ITCZ.

AT THE SFC...A 1023 MB HIGH LOCATED S OF THE AZORES NEAR 32N28W
DOMINATES THE PATTERN. THERE IS A WEAK TROUGH ALONG 44W FROM
27N-31N...BUT THIS IS FAIRLY BENIGN. THIS PATTERN IS PRODUCING
MAINLY 15-20 KT NE/E TRADES ACROSS THE TROPICS AND SIMILAR
MAGNITUDE OR LIGHTER WINDS OVER THE SUBTROPICS.

$$
CANGIALOSI/BELL




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