000
AXNT20 KNHC 171034
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT TUE JUN 17 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1115 UTC.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 34W S OF 12N MOVING W NEAR 15-20 KT. A 
WELL DEFINED LOW/MID LEVEL CYCLONIC CIRCULATION REMAINS ALONG 
THE WAVE NEAR 8N. LOW LEVEL SATELLITE DERIVED WINDS AND 850 MB 
VORTICITY SUPPORT THE POSITION OF THE WAVE AXIS. SCATTERED 
MODERATE CONVECTION IS MAINLY WITHIN 140 NM W OF THE WAVE AXIS 
FROM 7N-11N. MOISTURE FROM THIS TROPICAL WAVE IS FORECAST BY THE 
COMPUTER MODELS TO REACH THE LESSER ANTILLES ON THU. 

A WEAK TROPICAL WAVE IS ALONG 50W S OF 15N MOVING W NEAR 20 KT. 
THE WAVE SHOWS SOME INVERTED-V CLOUD PATTERN AND CONVECTION IS 
CONFINED TO THE ITCZ. THE SAHARAN AIR LAYER FROM CIMSS INDICATES 
THAT THE WAVE IS AT THE LEADING EDGE OF A EXTENSIVE AREA OF 
AFRICAN DUST. 

TROPICAL WAVE IS OVER CENTRAL AMERICA ALONG 85W/86W S OF 21N 
MOVING W AT 10-15 KT. THE WAVE IS EMBEDDED IN AN AREA OF DEEP 
LAYERED MOISTURE AS DEPICTED ON THE TPW PRODUCT. THIS FEATURE IS 
ONLY GENERATING ISOLATED SHOWERS AND TSTMS OVER HONDURAS AND 
NICARAGUA.  

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 9N13W 6N22W 7N31W 6N41W 7N59W. 
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 120 NM N 
OF AXIS E OF 22W TO THE AFRICAN COAST. SIMILAR CONVECTION IS 
FOUND WITHIN 130 NM N OF AXIS BETWEEN 50W-58W. CLUSTERS OF 
SCATTERED MODERATE CONVECTION ARE NEAR 7N37W...AND NEAR 6N40W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER-LEVEL TROUGH EXTENDS FROM N FLORIDA TO THE SW PORTION 
OF THE GULF WHILE A BROAD UPPER RIDGE REMAINS ANCHORED OVER 
NORTH/CENTRAL MEXICO COVERING THE NW CORNER OF THE GULF WITH 
MODERATE TO STRONG SUBSIDENCE. SW UPPER LEVEL WINDS AHEAD OF THE 
TROUGH ARE HELPING TO INDUCE SCATTERED SHOWERS AND TSTMS OVER SE 
MEXICO AND THE GULF OF TEHUANTEPEC...AND ARE EXPECTED TO SUPPORT 
CONVECTION OVER SOUTH FLORIDA THIS AFTERNOON WHERE HEAVY 
RAINFALL ARE POSSIBLE...PARTICULARLY ALONG THE EAST COAST METRO 
AREAS. AT THE SURFACE...A WEAK RIDGE...WITH A 1015 MB HIGH NEAR 
27N92W REMAINS IN CONTROL OF THE WEATHER PATTERN ACROSS THE GULF 
GIVING THE AREA MAINLY LIGHT WINDS. THE EXCEPTION IS THE WESTERN 
GULF WHERE SE TO S WINDS OF 10-15 KT ARE NOTED. THE RIDGE IS 
EXPECTED TO PERSIST DURING THE NEXT SEVERAL DAYS WITH A WEAK 
COLD FRONT ENTERING THE NE PORTION OF THE GULF LATE WED. A 
NARROW LINE OF SHOWERS WITH EMBEDDED TSTMS IS NEAR THE LOUISIANA 
COAST...LIKELY DUE TO A DIFFLUENT PATTERN ALOFT. MOSTLY FAIR 
WEATHER IS NOTED OVER THE REMAINDER OF THE GULF UNDER THE 
INFLUENCE OF THE RIDGE. 
 
CARIBBEAN...
A BROAD UPPER RIDGE DOMINATES THE CARIBBEAN ANCHORED ON A HIGH 
LOCATED NEAR CABO GRACIAS A DIOS NICARAGUA. SWLY WINDS BETWEEN 
THIS HIGH AND THE UPPER TROUGH THAT LIES ACROSS THE GULF OF 
MEXICO ARE TRANSPORTING ABUNDANT UPPER LEVEL MOISTURE FROM THE 
EPAC THROUGH CENTRAL AMERICA INTO THE NW CARIBBEAN...CUBA AND 
THE BAHAMAS. UPPER DIFFLUENCE ASSOCIATED WITH THESE WINDS ARE 
SUPPORTING THE DEVELOPMENT OF SOME CONVECTIVE ACTIVITY OVER THE 
CAYMAN ISLANDS...CUBA AND THE BAHAMAS. LIGHTNING DATA REVEALS 
THAT TSTMS ARE MORE CONCENTRATED OVER THE NW BAHAMAS. A TROPICAL 
WAVE IS MOVING WWD OVER CENTRAL AMERICA. SEE TROPICAL WAVE 
SECTION FOR DETAILS. BROAD UPPER RIDGE FROM THE TROPICAL ATLC 
COVERS THE E CARIBBEAN WITH STRONG SUBSIDENCE AND DRY AIR. THE 
COMBINATION OF A SFC HIGH BUILDING N OF AREA AND THE PRESENCE OF 
THE COLOMBIAN LOW IS PRODUCING STRONG TRADE WINDS OF 20-30 KT 
ACROSS THE CENTRAL CARIBBEAN.   

ATLANTIC...
NEARLY ZONAL FLOW DOMINATES THE W AND CENTRAL ATLC WITH A PAIR 
OF SHORT-WAVE TROUGH ALONG 67W/68W N OF 22N...AND ALONG OF 55W N 
OF 27N. A DEEP LAYERED TROUGH LOCATED N OF AREA SUPPORTS A COLD 
FRONT THAT CLIPS THE FORECAST REGION NEAR 31N40W THEN CONTINUES 
AS A TROUGH TO 25N50W. SCATTERED SHOWERS ARE ASSOCIATED WITH THE 
TROUGH. AN UPPER-LEVEL LOW IS OVER THE E ATLC NEAR 28N22W. A 
TROUGH EXTENDS FROM THIS LOW INTO THE TROPICS NEAR 14N30W. BROAD 
UPPER E/W RIDGE DOMINATES THE TROPICS S OF 20N AND WEST OF 35W 
TO OVER THE E CARIBBEAN. A BROAD BUT WEAK SURFACE RIDGE COVERS 
THE ENTIRE FORECAST AREA WITH A COUPLE OF HIGH CENTERS. ONE OF 
1021 MB IS NEAR 28N51W. THE SECOND ONE IS NEAR 30N34W WITH 1024 
MB. THIS SYSTEM WILL REMAIN NEARLY STATIONARY DURING THE NEXT 24 
HOURS. PRES GRADIENT BETWEEN THIS HIGH AND LOWER PRES OVER 
AFRICA WILL CONTINUE TO PRODUCE MODERATE TO FRESH NLY WINDS 
MAINLY N OF 18N AND E OF 25W.    

$$
GR/CW