Wednesday Afternoon Tropical Weather Discussion

AXNT20 KNHC 111759
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT WED JUN 11 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 NEW TROPICAL WAVE WILL BE ADDED TO THE 1800 UTC SFC MAP ALONG
45W S OF 12N BASED ON SATELLITE PICTURES AND THE SSMI-DERIVED
TPW THAT SHOWS A PEAK OF MOISTURE IN THIS AREA. IN ADDITION...
850 MB SATELLITE DERIVED VORTICITY ALSO SUPPORTS THE POSITION OF
THE WAVE. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS
WITHIN 180 NM EITHER SIDE OF WAVE AXIS FROM 5N-10N.

A TROPICAL WAVE IS ALONG 57W S OF 17N MOVING W 10-15 KT. A TINY
1012 MB SFC LOW HAS DEVELOPED ALONG THE WAVE AXIS NEAR 10N. SAT
IMAGERY SHOWS A CLUSTER OF MODERATE TO ISOLATED STRONG
CONVECTION ON THE WEST SIDE OF THE LOW WITH LINES OF LOW LEVEL
CLOUDS SPINNING AROUND. THIS SYSTEM SHOWS UP VERY WELL ON THE
UW-CIMMS TPW PRODUCT WHERE A BULGE OF MOISTURE IS OBSERVED. THE
WIND SHIFT ASSOCIATED WITH THIS FEATURE IS CLEARLY DEFINED ON
SFC DATA. MOISTURE ASSOCIATED WITH THIS TROPICAL WAVE AND ITS
SFC LOW WILL AFFECT THE WINDWARD ISLANDS THIS AFTERNOON THROUGH
AT LEAST THU. DEVELOPMENT IS NOT EXPECTED BEFORE THE SYSTEM
MOVES INTO VENEZUELA OVERNIGHT.

A TROPICAL WAVE IS OVER THE YUCATAN PENINSULA AND GUATEMALA. IT
AXIS IS ALONG 90W/91W S OF 24N MOVING W NEAR 15 KT. WAVE REMAINS
EMBEDDED WITHIN AN AREA OF DEEP LAYERED MOISTURE AS DEPICTED ON
THE MIMIC-TPW ANIMATION. SCATTERED SHOWERS AND TSTMS ARE JUST
BEHIND OF THE WAVE AXIS. THIS ACTIVITY AFFECTED CANCUN AND
COZUMEL A FEW HOURS AGO.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 10N14W 5N30W 10N54W 10N59W 9N62W.
THERE ARE SOME SIGNS THAT A NEW TROPICAL WAVE EMERGED FROM
AFRICA EARLY THIS MORNING. SATELLITE IMAGERY SHOWS AN AREA OF
MODERATE TO ISOLATED STRONG CONVECTION COVERING FROM 4N-10N
BETWEEN 16W-22W. CURRENTLY...LOW LEVEL SATELLITE DERIVED WIND
INDICATES SOME WIND SHIFT AROUND 20W. WILL WAIT FOR THE 1800 UTC
DATA TO HAVE BETTER INDICATIONS. THE REMAINDER OF THE CONVECTION
ALONG THE ITCZ IS MAINLY ASSOCIATED WITH THE TROPICAL WAVES
AFOREMENTIONED.

...DISCUSSION...

GULF OF MEXICO...
AS OF 1500 UTC...A 1020 MB SFC HIGH IS CENTERED OVER THE W
ATLANTIC NEAR 29N71W EXTENDING A RIDGE OVER MOST OF THE GULF
REGION. UNDER THIS PATTERN...LIGHT TO MODERATE SE WINDS
DOMINATES THE AREA...BUT WINDS ARE EXPECTED TO INCREASE LATE
TODAY THROUGH FRI ACROSS THE WESTERN GULF IN RESPONSE TO A
DEVELOPING LOW PRES SYSTEM OVER CENTRAL PLAINS. SFC PRESSURES
ARE LOWER OVER THE BAY OF CAMPECHE...AND A SFC TROUGH IS
ANALYZED THERE. SCATTERED SHOWERS AND TSTMS ARE OVER THE YUCATAN
PENINSULA AND COASTAL WATERS ASSOCIATED WITH THE N END OF A
TROPICAL WAVE MOVING WWD ACROSS THE AREA. SIMILAR CONVECTIVE
ACTIVITY IS NEAR 26N86W WITH LIGHTNING DATA INDICATING SCATTERED
TSTMS. ALL THIS ACTIVITY IS BEING ENHANCED BY A SHORT WAVE
TROUGH ALOFT LOCATED OVER THE SE GULF AND THE YUCATAN PENINSULA.

CARIBBEAN...
HIGH PRES N OF THE AREA IS PRODUCING LIGHT TO MODERATE TRADE
WINDS ACROSS THE BASIN. A QSCAT PASS FROM THIS MORNING INDICATED
E WINDS OF 15-20 KT...OCCASIONALLY 25 KT JUST OFF THE COLOMBIAN
COAST. SIMILAR WIND SPEEDS ARE ALSO FOUND W OF 85W BEHIND THE
TROPICAL WAVE LOCATED OVER THE YUCATAN PENINSULA. A SFC TROUGH
IS ANALYZED JUST OFF THE ATLANTIC COAST OF NICARAGUA WHERE THERE
IS SOME SHOWER/TSTM ACTIVITY...LIKELY RELATED TO THE LOW LEVEL
WIND/SPEED CONVERGENCE. THE TROPICAL WAVE ALONG 57W IS FORECAST
TO REACH THE E CARIBBEAN EARLY THU. SEE ABOVE FOR DETAILS. IN
THE UPPER LEVELS...MOSTLY WLY ZONAL FLOW PREVAILS WITH A FAIR
AMOUNT OF UPPER LEVEL MOISTURE. A NARROW BAND OF TRANSVERSE HIGH
CLOUDS EXTENDS FROM WEST TO EAST ALONG 14N/15N FROM CABO GRACIAS
A DIOS ALL THE WAY TO BEYOND THE LESSER ANTILLES.

ATLANTIC...
TWO UPPER-LEVEL LOWS ARE OVER THE W ATLC. ONE IS MEANDERING JUST
E OF THE NE COAST OF FLORIDA NEAR 30N80W...AND CONTINUES TO
ENHANCE TSTM ACTIVITY OVER THE STATE OF FLORIDA AND THE NW
BAHAMAS. MOSAIC DOPPLER RADAR FROM THE SE...INDICATES THAT THE
STRONGEST TSTMS ARE OVER SE AND NORTHERN PORTIONS OF FLORIDA.
THESE SLOW MOVING STORMS WILL BE CAPABLE PRIMARILY OF HEAVY
RAINFALL AND FREQUENT LIGHTNING. THE SECOND UPPER-LEVEL LOW IS N
OF THE VIRGIN ISLANDS NEAR 21N65W. CYCLONIC FLOW AROUND THIS LOW
IS HELPING TO INDUCE SOME SHOWER/TSTM ACTIVITY OVER PUERTO
RICO...THE UK/US VIRGIN ISLANDS AND THE SURROUNDING COASTAL
WATERS. AT THE SFC...THE 1020 MB HIGH PREVIOUSLY MENTIONED
DOMINATES THE AREA. A COLD FRONT EXTENDING E-W ALONG 31N CLIPS
THE CENTRAL ATLC. A BROKEN BAND OF LOW/MID CLOUDS IS AHEAD OF
THE FRONT N OF 28N BETWEEN 40W AND 60W. A BROAD UPPER-LEVEL
TROUGH OVER THE CENTRAL ATLANTIC SUPPORTS THIS FRONT. A SFC
RIDGE ANCHORED ON A HIGH SITUATED WELL N OF THE AREA IS IN
CONTROL OF THE WEATHER PATTERN OVER THE E ATLC. ZONAL FLOW IS
OVER THE E ATLANTIC N OF 20N AND E OF 30W. IN THE TROPICS... AN
UPPER LEVEL HIGH IS CENTERED NEAR 11N40W WITH THE ANTICYCLONIC
FLOW REACHING THE WINDWARD ISLANDS. THIS UPPER FEATURE IS
ASSISTING IN THE DEVELOPMENT OF SHOWERS AND TSTMS RELATED TO THE
ABOVE MENTIONED TROPICAL WAVES. AN INVERTED TROUGH LIES JUST
SOUTH OF THE CAPE VERDE ISLANDS.

$$
GR


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