000
AXNT20 KNHC 172355
TWDAT 

TROPICAL WEATHER DISCUSSION     
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT THU APR 17 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 2315 UTC.

...THE ITCZ...

ITCZ AXIS IS CENTERED ALONG 6N10W 3N23W 1N33W CROSSING THE 
EQUATOR NEAR 37W TO 1S49W. WIDELY SCATTERED MODERATE CONVECTION 
IS WITHIN 240 NM N OF THE AXIS W OF 30W AND WITHIN 180 NM N OF 
THE AXIS BETWEEN 18W-20W.

...DISCUSSION...

THE GULF OF MEXICO...
MID-UPPER LEVEL RIDGING EXTENDS NWD FROM THE CARIBBEAN ACROSS 
THE MIDDLE GULF PRODUCING A MODESTLY SUBSIDENT ENVIRONMENT. THE 
AIR ALOFT IS DRIEST OVER THE FAR E WATERS AND FLORIDA DUE 
TO CONFLUENCE BETWEEN THEN RIDGE AND A LARGE CUT OFF LOW OVER 
THE WRN ATLC. AT THE SFC...A 1025 MB HIGH IS SITUATED OVER S 
GEORGIA PROVIDING E/SE 10-15 KT WINDS ACROSS THE E AND CENTRAL 
GULF. THE FLOW BECOMES SE TO S AND INCREASES TO 20-25 KT OVER 
THE NW CORNER IN RESPONSE TO A STORM SYSTEM OVER THE S CENTRAL 
PLAINS. THIS LOW PRES SYSTEM WILL DRAG A COLD FRONT INTO THE 
REGION TOMORROW. HOWEVER...THIS FRONT WILL WEAKEN FAIRLY QUICKLY 
AS ITS UPPER SUPPORT PULLS NE TOWARDS THE GREAT LAKES. VISIBLE 
IMAGERY SHOWS SEVERAL BROKEN LOW-LEVEL CLOUDS LINES N OF 23N W 
OF 87W AND S OF 24N E OF 87W...BUT THERE ARE LIKELY ONLY 
ISOLATED SHOWERS EMBEDDED.   

THE CARIBBEAN SEA...
THE BASE OF AN UPPER TROUGH...ASSOCIATED WITH THE LARGE CUT OFF 
OVER THE W ATLC...EXTENDS THROUGH THE SE BAHAMAS AND WINDWARD 
PASSAGE. THIS TROUGH IS SUPPORTING A WEAKENING FRONT ANALYZED 
FROM THE DOMINICAN REPUBLIC TO 17N77W. MUCH OF THE NRN HALF OF 
HISPANIOLA IS SOCKED IN WITH CLOUDS AND LIGHTNING DATA IS 
DETECTING A FEW TSTMS...LIKELY ENHANCED BY TOPOGRAPHY AND 
MESOSCALE MECHANISMS. LOW CLOUDS AND EMBEDDED ISOLATED SHOWERS 
ARE MOVING TOWARD THE GULF OF HONDURAS FROM 15N-19N BETWEEN 
81W-85W. SIMILAR CLOUDS/SHOWERS ARE OVER THE FAR SW PORTION S OF 
11N W OF 81W. BOTH OF THESE PATCHES ARE BEING POOLED INTO THIS 
REGION BY THE SYNOPTIC NE FLOW AND THEN ENHANCED BY LOW-LEVEL 
CONVERGENCE NEAR THE CENTRAL AMERICA COAST. TRADE WINDS HAVE 
INCREASED TODAY TO 20-25 KT ACROSS MUCH OF THE REGION BETWEEN 
68W-80W AND WILL REMAIN STRONG TOMORROW AND SAT AS HIGH PRES 
BUILDS N OF THE REGION.

THE ATLANTIC OCEAN...
A LARGE CUT OFF VERTICALLY STACKED LOW PRES SYSTEM HAS BEEN 
MEANDERING OFF THE MID-ATLANTIC COASTLINE. THE SFC CENTER IS 
ANALYZED 998 MB NEAR 36N68W. THIS FEATURE IS PRODUCING NLY STORM 
FORCE WINDS AND VERY HAZARDOUS SEA CONDITIONS TO ITS W OFF 
THE CAROLINA COASTLINE. A TRAILING TROUGH EXTENDS SW FROM THE 
LOW TO THE NW BAHAMAS. HOWEVER...UNLIKE LAST NIGHT THERE IS 
LITTLE SHOWER/TSTM ACTIVITY ALONG IT DUE TO THE LARGE AREA OF 
DRY MID-UPPER LEVEL AIR W OF 65W. AN ASSOCIATED WEAKENING NEARLY 
STALLED FRONT ENTERS THE AREA NEAR 32N61W THRU 26N63W TO 19N70W. 
UPPER DIFFLUENCE AND LOW-LEVEL CONVERGENCE ARE ENHANCING 
SCATTERED TSTMS NEAR THE HISPANIOLA COAST S OF 20N BETWEEN 
68W-70W AND SCATTERED SHOWERS ELSEWHERE WITHIN 240 NM E OF THE 
FRONT. 

THE REMAINDER OF THE ATLC BASIN IS RATHER TRANQUIL THANKS TO A 
SPRAWLING DEEP LAYER HIGH PRES SYSTEM CENTERED OVER THE CENTRAL 
ATLC. THE SFC CENTER...ANALYZED 1031 MB NEAR 33N43W...IS 
PRODUCING N 20-25 KT WINDS NEAR THE COAST OF AFRICA FROM 20N-24N 
AND MAINLY 15-20 KT NE/E WINDS ACROSS THE REMAINDER OF THE 
TROPICS. AN UPPER LOW IS SPINNING NEAR 16N29W AND AN UPPER 
TROUGH IS ALONG 49W...BUT BOTH OF THESE FEATURES ARE ONLY 
PRODUCING SOME PATCHY MID-HIGH LEVEL CLOUDS. WLY FLOW ALOFT LIES 
OVER THE DEEP TROPICS ALSO SPREADING PATCHY HIGH LEVEL CLOUDS.

$$
CANGIALOSI