[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 121802
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT THU JUN 12 2008

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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...TROPICAL WAVES...

A TROPICAL WAVE IS ADDED TO THE 1200 UTC ANALYSIS/SURFACE MAP
ALONG 18W S OF 18N BASED ON VIS SATELLITE IMAGERY AND SFC DATA.
IN ADDITION...THE SSMI-DERIVED TPW SHOWS A SURGE OF MOISTURE
PROTRUDING NORTHWARD IN THIS AREA...AND THE DAKAR VERTICAL
SOUNDING FROM THIS MORNING INDICATED THE PASSAGE OF THE WAVE
AXIS WITH AN INCREASE IN MOISTURE AND SE WINDS AT LOW LEVELS.
CLUSTERS OF MODERATE TO ISOLATED STRONG CONVECTION ARE FROM
8N-12N WEST OF 20W TO THE AFRICAN COAST.

A TROPICAL WAVE IS ALONG 53W/54W S OF 15N MOVING W NEAR 15 KT.
THE WAVE SHOWS UP VERY WELL ON THE UW-CIMSS TPW PRODUCT WITH A
NORTH-SOUTH MOISTURE MAXIMUM. THE GFS MODEL 850 MB LOW-LEVEL
VORTICITY ALSO SUPPORTS THE POSITION OF THE WAVE. SCATTERED
MODERATE CONVECTION IS W OF THE WAVE AXIS FROM 9N-12N BETWEEN
54W-59W. MOISTURE FROM THIS WAVE WILL AFFECT THE WINDWARD
ISLANDS LATE THIS AFTERNOON THROUGH FRI...SPREADING OVER THE
UK/US VIRGIN ISLANDS AND PUERTO RICO LATER.

A WEAK TROPICAL WAVE IS OVER THE UK/US VIRGIN ISLAND EXTENDING
SOUTH TO CENTRAL VENEZUELA. MOISTURE IS MAINLY BEHIND THE WAVE
AXIS AFFECTING THE WINDWARD ISLANDS WITH SCATTERED SHOWERS AND
ISOLATED TSTMS. BARBADOS REPORTED HEAVY SHOWERS AND GUSTY WINDS
OF 30 KT YESTERDAY AFTERNOON WITH THE PASSAGE OF THE WAVE. THIS
SYSTEM STILL SHOWS UP WELL ON THE UW-CIMMS TPW PRODUCT WHERE A
HIGH AMPLITUDE BULGE OF MOISTURE IS OBSERVED. THE WAVE WILL MOVE
ACROSS PUERTO RICO LATE THIS AFTERNOON AND TONIGHT INCREASING
THE CHANCES OF SHOWERS AND THUNDERSTORMS.

A TROPICAL WAVE IS OVER THE SW GULF OF MEXICO AND THE ISTHMUS OF
TEHUANTEPEC ALONG 94W S OF 24N MOVING W NEAR 10 KT. WAVE REMAINS
EMBEDDED WITHIN AN AREA OF DEEP LAYERED MOISTURE AS DEPICTED ON
THE MIMIC-TPW ANIMATION. THE WAVE IS ALSO INTERACTING WITH AN
UPPER-LEVEL LOW OVER THE CENTRAL GULF. AS A RESULT...THERE ARE
TWO AREAS OF SCATTERED TO NUMEROUS SHOWERS AND TSTMS. ONE IS
NEAR THE N END OF THE WAVE AXIS AND THE SECOND ONE IS FROM
24N-28N BETWEEN 85W-90W. THE CITY OF VERACRUZ REPORTED THIS
MORNING 5.28 INCHES OF RAIN IN 24 HOURS.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 10N14W 8N20W 3N35W 3N51W. BESIDES
THE CONVECTION ASSOCIATED WITH THE TROPICAL WAVES...SCATTRED
MODERATE CONVECTION IS NOTED WITHIN 160-200 NM N OF AXIS...AND
WITHIN 100 NM S OF AXIS FROM 32W TO 45W.

...DISCUSSION...

GULF OF MEXICO...
AS PREVIOUSLY MENTIONED...THE COMBINATION OF A TROPICAL WAVE AND
AN UPPER-LEVEL LOW CENTERED OVER THE CENTRAL GULF IS GENERATING
ABUNDANT CLOUDINESS WITH EMBEDDED SHOWERS AND TSTMS OVER A GOOD
PORTION OF THE REGION. SEE TROPICAL WAVE SECTION FOR DETAILS. A
1020 MB SFC HIGH REMAINS OVER THE W ATLANTIC NEAR 30N74W
EXTENDING A RIDGE MAINLY OVER THE EASTERN PORTION OF THE GULF.
PRES GRADIENT BETWEEN THE SFC HIGH AND THE TROPICAL WAVE IS
PRODUCING MODERATE TO FRESH SE WINDS OVER PARTS OF THE CENTRAL
AND WESTERN GULF. THESE WINDS ARE EXPECTED TO DIMINISH FRI
AFTERNOON AND EVENING. ACCORDING TO THE GFS MODEL...CLOUDINESS
AND SHOWER/TSTM ACTIVITY OVER THE GULF WILL MOVE NW TOWARD THE N
GULF STATES IN ABOUT 24 HOURS UNDER A PREVAILING SE FLOW.

CARIBBEAN...
A TROPICAL WAVE IS OVER THE E CARIBBEAN AND A SECOND AND
STRONGER ONE IS APPROACHING THE WINDWARD ISLANDS. SEE TROPICAL
WAVE SECTION. MODEL GUIDANCE SUGGESTS THAT THESE TWO TROPICAL
WAVES WILL MERGE SOMETIME FRIDAY KEEPING A GOOD SURGE OF
MOISTURE OVER THE EASTERN CARIBBEAN. ALSO...EXPECT AN INCREASE
IN WINDS AND SEAS TO ACCOMPANY THE PASSAGE OF BOTH WAVES. IN THE
MEANTIME...MODERATE TO FRESH TRADEWINDS ARE NOTED THROUGHOUT THE
BASIN WITH THE STRONGEST WINDS...AS USUAL JUST OFF THE COLOMBIAN
COAST WHERE AN EARLIER QSCAT PASS SHOWED ELY WINDS OF 25 KT.
SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS OVER THE SW
CARIBBEAN ALONG THE COASTS OF PANAMA...COSTA RICA...AND
NICARAGUA...LIKELY DUE TO THE CLOSE PROXIMITY OF THE EPAC ITCZ
AND A DIFFLUENT PATTERN ALOFT. IN THE UPPER LEVELS...MOSTLY WLY
ZONAL FLOW IS NOTED WITH A FAIR AMOUNT OF UPPER LEVEL MOISTURE
PARTICULARLY W OF 75W AND OVER THE FAR SE CARIBBEAN.

ATLANTIC...
A COUPLE OF UPPER-LEVEL LOWS PERSIST OVER THE W ATLC. ONE IS
JUST N OF THE NW BAHAMAS NEAR 28N78W...AND CONTINUES TO ENHANCE
TSTM ACTIVITY OVER THE STATE OF FLORIDA AND THE NW BAHAMAS.
SIMILAR TO YESTERDAY...MOSAIC DOPPLER RADAR FROM THE SE
INDICATES THAT STRONG TSTMS ARE FORMING OVER PARTS OF FLORIDA
BUT MAINLY ON THE EASTERN SIDE AND NEAR LAKE OKEECHOBEE. THESE
SLOW MOVING STORMS WILL BE CAPABLE OF HEAVY RAINFALL...GUSTY
WINDS AND FREQUENT LIGHTNING. THE SECOND UPPER-LEVEL LOW IS NE
OF PUERTO RICO NEAR  23N62W GENERATING SCATTERED SHOWERS AND
ISOLATED TSTMS. AT THE SFC...THE 1021 MB HIGH MENTIONED ABOVE
DOMINATES THE AREA. A FRONTAL SYSTEM HAS ENTERED THE FORECAST
AREA THROUGH THE CENTRAL ATLC AND NOW EXTENDS ALONG 31N35W
29N45W 30N58W. A BROKEN BAND OF LOW/MID CLOUDS  WITH EMBEDDED
SHOWERS IS ASSOCIATED WITH THE FRONT. BROAD UPPER-LEVEL TROUGH
OVER THE CENTRAL ATLANTIC SUPPORTS THIS FRONT. A SFC RIDGE IS
MAINLY SOUTH OF THE FRONTAL BOUNDARY COVERING THE FORECAST AREA
EAST OF 50W. NEARLY ZONAL FLOW IS OVER THE E ATLANTIC N OF 20N
AND E OF 30W. IN THE TROPICS...AN UPPER LEVEL HIGH IS CENTERED
NEAR 14N48W WITH THE ANTICYCLONIC FLOW REACHING THE SE CARIBBEAN
TO THE WEST AND THE CAPE VERDE ISLANDS TO THE EAST. THIS UPPER
FEATURE IS ASSISTING IN THE DEVELOPMENT OF SHOWERS AND TSTMS
RELATED TO THE ABOVE MENTIONED TROPICAL WAVES.

$$
GR







This weather bulletin was brought to you by:
www.nashvilleweather.net