000 AXNT20 KNHC 010546 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT TUE OCT 01 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0315 UTC. ...SPECIAL FEATURES... TROPICAL STORM LAURA IS CENTERED NEAR 43.6N 48.0W AT 01/0300 UTC OR ABOUT 290 NM SE OF CAPE RACE NEWFOUNDLAND MOVING NNE AT 14 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1000 MB. MAXIMUM SUSTAINED WIND SPEED IS 45 KT WITH GUSTS TO 55 KT. PLEASE SEE THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCPAT2/WTNT32 KNHC FOR MORE DETAILS. LAURA IS BEGINNING TO SHOW SIGNS OF BECOMING EXTRATROPICAL AND WILL BE THAT IN THE NEXT 12 HOURS OR SO. LAURA SHOULD TURN MORE TO THE NE WITH AN INCREASE IN FORWARD SPEED AHEAD OF A VERY DEEP LAYERED TROUGH OVER THE E US. NO ACTIVITY REMAINS IN THE REGION ASSOCIATED WITH LAURA. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 35W S OF 18N MOVING W 10-15 KT. THE INVERTED-V CLOUD PATTERN ALONG WAVE AXIS ON THE SATELLITE IMAGERY IS NOT AS WELL DEFINED AS 24 HOURS AGO. HOWEVER...THIS WAVE REMAINS EMBEDDED WITHIN DEEP LAYERED MOISTURE AS INDICATED ON THE MIMIC TPW ANIMATION WITH TWO AREAS OF CONVECTION. SCATTERED MODERATE/STRONG CONVECTION IS FROM 4N-8N BETWEEN 30W-37W WITH CLUSTERS OF SIMILAR CONVECTION FROM 12N-17N BETWEEN 30W-39W. TROPICAL WAVE IS ALONG 47W/48W FROM 12N-21N MOVING W 5-10 KT. WELL DEFINED INVERTED-V CLOUD PATTERN IS OBSERVED ON SATELLITE IMAGERY WITH ACTIVITY BEING ENHANCED BY A CUT-OFF UPPER LOW JUST TO THE W. SCATTERED MODERATE/STRONG CONVECTION IS FROM 19N-21N BETWEEN 44W-46W. TROPICAL WAVE IS ALONG 62W/63W S OF 16N MOVING W 10-15 KT. WEAK WAVE SIGNATURE WITH CLUSTERS OF SCATTERED MODERATE CONNECTION FROM 12N-15N BETWEEN 60W-65W. ...THE ITCZ... THE ITCZ AXIS IS ANALYZED ALONG 8N12W 11N32W 9N48W 10N61W. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 4N-7N E OF 15W TO THE COAST OF W AFRICA...WITHIN 60 NM OF THE ITCZ FROM 28W-34W...AND FROM 5N-10N BETWEEN 42W-49W. ...DISCUSSION... GULF OF MEXICO... DEEP UPPER TROUGH OVER THE E US EXTENDS S OVER THE GULF WITH MODERATE/STRONG SUBSIDENCE AND DRY STABLE AIR COVERING MUCH OF THE GULF WITH THE EXCEPTION OF THE SE. A COMPLEX SURFACE BOUNDARY EXTENDS FROM A FRONT IN THE W ATLC AS A SURFACE TROUGH ACROSS S FLORIDA TO A 1011 MB LOW ALONG THE W COAST OF FLORIDA BETWEEN FORT MYERS AND NAPLES TO A DISSIPATING 1010 MB LOW NEAR 23N89W CONTINUING S TO OVER THE YUCATAN PENINSULA. THE STRONG AND MOIST SW FLOW ALOFT IS E OF THE SURFACE TROUGH PROVIDING UPPER SUPPORT FOR SCATTERED SHOWERS/ISOLATED THUNDERSTORMS OVER THE SE GULF AND THROUGH THE FLORIDA STRAITS INCLUDING S FLORIDA. SCATTERED LOW CLOUDS WITH POSSIBLE ISOLATED SHOWERS DOT THE REMAINDER OF THE S GULF S OF 25N WHILE THE N GULF IS CLOUD FREE TONIGHT. CARIBBEAN SEA... AN UPPER RIDGE IS ANCHORED IN THE W CARIBBEAN NEAR 17N84W WITH A RIDGE AXIS EXTENDING NE TO CENTRAL CUBA PROVIDING UPPER LEVEL SUPPORT FOR SCATTERED SHOWERS/ISOLATED THUNDERSTORMS NW OF LINE FROM CUBA NEAR THE ISLE OF YOUTH TO CENTRAL BELIZE. A SECOND UPPER RIDGE EXTENDS INTO THE CENTRAL CARIBBEAN N OF 15N E OF 74W ANCHORED BY AN UPPER HIGH OVER THE W ATLC. SOMEWHAT STABLE CONDITIONS AND DRYER AIR ARE BENEATH THIS RIDGE WITH ONLY SOME ISOLATED SHOWERS FROM 16N-18N BETWEEN 68W-72W. A THIRD UPPER RIDGE IS OVER THE SE CARIBBEAN ANCHORED OVER SOUTH AMERICA AND EXTENDING A RIDGE AXIS FROM VENEZUELA NEAR CARACAS ACROSS THE THE LESSER ANTILLES NEAR NEAR SAINT VINCENT ISLAND. THE ITCZ AXIS EXTENDS ACROSS THE N PORTION OF SOUTH AMERICA THEN JUST N OF PANAMA ACROSS COSTA RICA INTO THE E PACIFIC GENERATING SCATTERED MODERATE/ISOLATED STRONG CONVECTION S OF 13N TO INLAND OVER COLOMBIA AND S OF 10N TO INLAND OVER PANAMA E OF 80W. ATLANTIC OCEAN... TROPICAL STORM LAURA IS LOCATED WELL N OF THE REGION...SEE SPECIAL FEATURES ABOVE. THE DEEP UPPER TROUGH OVER THE E US AND GULF OF MEXICO CLIPS THE FAR W ATLC WITH THE ASSOCIATED COLD FRONT ENTERING THE REGION FROM A 1008 MB LOW NEAR 32N72W ALONG 28N75W TO JUST N OF THE BAHAMAS NEAR 27N79W WHERE A SURFACE TROUGH CONTINUES INTO THE GULF OF MEXICO ACROSS FLORIDA NEAR LAKE OKEECHOBEE. THE SW UPPER FLOW IS DRAWING STRONG MOIST AIR ACROSS THE AREA PROVIDING THE UPPER SUPPORT FOR SCATTERED SHOWERS/ISOLATED THUNDERSTORMS S OF 27N W OF 77W TO OVER S FLORIDA AND THROUGH THE FLORIDA STRAITS. BROAD UPPER HIGH COVERS THE REMAINDER OF THE W ATLC INTO THE CENTRAL ATLC AND S OVER THE CENTRAL CARIBBEAN CENTERED NEAR 23N70W. STRONG SUBSIDENCE AND DRY STABLE AIR COVER THE AREA S OF 27N BETWEEN 64W-74W RESULTING IN FAIR WEATHER OVER THAT AREA. A CUT-OFF UPPER LOW IS IN THE W TROPICAL ATLC NEAR 18N52W JUST TO THE W OF THE TROPICAL WAVE ALONG 47W/48W ENHANCING THE ACTIVITY ASSOCIATED WITH THAT WAVE. BROAD UPPER TROUGH COVERS THE REMAINDER OF THE ATLC N OF 23N E OF 53W WITH A WEAK EMBEDDED RIDGE ALONG 30W. HOWEVER...OTHER THAN SOME HIGH CLOUDS LITTLE IN THE WAY OF SHOWERS ARE EVIDENT. THE TYPICAL E/W UPPER RIDGE THAT DOMINATES THE TROPICAL ATLC EXTENDING ALONG 15N TO 45W. A SURFACE RIDGE EXTENDS FROM THE E ATLC THROUGH 32N29W SW TO NEAR 21N60W. THE LAST VISIBLE SATELLITE IMAGES CLEARLY SHOW AFRICAN DUST SPREADING W TO NEAR 40W WITH THE DENSEST AREA E OF 30W. $$ WALLACE