[Tropical] Tropical Weather Discussion

[EMWIN Server]

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





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