000 AXNT20 KNHC 172314 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT SAT MAR 17 2007 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHEASTERN 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 2245 UTC. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 9N12W 3N22W CROSSING THE EQUATOR NEAR 37W INTO NE BRAZIL NEAR 3S44W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 90/120 NM OF THE AXIS FROM 16W-20W. SMALL CLUSTERS OF SIMILAR CONVECTION ARE FROM 3N TO THE COAST OF AFRICA E OF 3W TO THE PRIME MERIDIAN. ...DISCUSSION... GULF OF MEXICO... BROAD UPPER LEVEL TROUGH COVERS THE ENTIRE E US AND THE GULF OF MEXICO EXTENDING INTO THE W ATLC. THE ASSOCIATED FRONT IS IN THE W ATLC AND THE CARIBBEAN LEAVING THE GULF WITH MODERATE/STRONG WINDS ROTATING AROUND A 1026 MB HIGH LOCATED ALONG THE COAST OF LOUISIANA. ALSO IN THE WAKE OF THE RECENT FRONTAL PASSAGE IS STRONG SUBSIDENCE AND DRY AIR AT ALL LEVELS GIVING THE GULF RELATIVELY CLEAR SKIES AND COOLER TEMPERATURES. THE ONLY EXCEPTION IS SCATTERED COLD AIR STRATOCUMULUS CLOUDS DOTTING THE GULF S OF 26N. THE CENTER OF THE SURFACE HIGH IS EXPECTED TO SHIFT EASTWARD OVER THE NEXT COUPLE OF DAYS...BUT HIGH PRESSURE RIDGE WILL REMAIN IN CONTROL OF THE GULF THROUGH TUE. CARIBBEAN... THE COLD FRONT THAT PUSHED INTO THE CARIBBEAN EARLIER NOW EXTENDS FROM THE W ATLC ACROSS CENTRAL CUBA NEAR 22N78W TO THE GULF OF HONDURAS NEAR 17N86W ASSOCIATED WITH THE UPPER LEVEL TROUGH THAT COVERS THE GULF OF MEXICO AND INTO THE W ATLC. STRONG SUBSIDENCE AND DRY AIR AT ALL LEVELS IS BEHIND THE FRONT LEAVING THE AREA W OF THE FRONT CLEAR WITH COOLER TEMPERATURES. TO THE E OF THE FRONT IS A REMNANT FRONTAL BOUNDARY/SURFACE TROUGH THAT EXTENDS FROM SW HAITI ALONG 16N79W TO THE COAST OF NICARAGUA NEAR 14N83W. LOW LEVEL CONVERGENCE IS DEVELOPING SCATTERED SHOWERS WITHIN 90 NM OF THE SURFACE TROUGH INCLUDING JAMAICA. THE REMAINDER OF THE CARIBBEAN IS DOMINATED BY A BROAD UPPER RIDGE ANCHORED ALONG THE COAST OF SOUTH AMERICA NEAR 7N58W AND EXTENDS ACROSS THE TROPICAL ATLC TO 30W. THIS IS ADVECTING TROPICAL MOISTURE ACROSS THE E CARIBBEAN WITH THE STRONG CONVECTION DEVELOPING OVER COLOMBIA AND ALONG THE IMMEDIATE COASTAL WATERS. ATLANTIC... BROAD UPPER TROUGH THAT COVERS E US AND THE GULF OF MEXICO EXTENDS OVER THE W ATLC TO 70W WITH THE ASSOCIATED COLD FRONT ENTERING THE AREA NEAR 32N71W CONTINUING ACROSS THE CENTRAL BAHAMAS INTO THE CARIBBEAN ACROSS CENTRAL CUBA NEAR 22N78W. A REMNANT FRONTAL BOUNDARY/SURFACE TROUGH EXTENDS FROM 27N69W TO 23N60W. BROKEN/OVERCAST CLOUDS WITH EMBEDDED RAIN/ISOLATED THUNDERSTORMS ARE E OF THE FRONT AND WITHIN 350 NM N OF SURFACE TROUGH. SCATTERED SHOWERS DOT THE REMAINDER OF THE AREA S OF THE SURFACE TROUGH TO OVER THE GREATER ANTILLES. IN THE WAKE OF THE COLD FRONT...STRONG SUBSIDENCE AND DRY AIR AT ALL LEVELS DOMINATE THE AREA WITH ONLY BROKEN COLD AIR STRATOCUMULUS CLOUDS. A DEEP LAYERED LOW IS N OF THE REGION WITH THE UPPER TROUGH EXTENDING JUST INTO THE CENTRAL ATLC N OF 28N FROM 40W-55W. A SURFACE TROUGH EXTENDS INTO THE REGION THROUGH 32N42W SW TO 24N50W WITH ONLY LOW LEVEL CLOUDS WITH POSSIBLE ISOLATED SHOWERS WITHIN 120 NM OF THE TROUGH. WELL DEFINED UPPER LOW IS OVER THE E ATLC JUST N OF THE CANARY ISLANDS COVERING THE E ATLC N OF 22N E OF 32W. HOWEVER...THERE IS NO LONGER A SURFACE REFLECTION. A SURFACE RIDGE EXTENDS FROM A 1042 MB HIGH JUST N OF THE AZORES THROUGH 32N34W TO 17N42W. THE TROPICAL ATLC IS DOMINATED BY A BROAD UPPER RIDGE THAT EXTENDS S OF 20N W OF 30W TO OVER THE CARIBBEAN. $$ WALLACE