000 AXNT20 KNHC 171036 AAA TWDAT TROPICAL WEATHER DISCUSSION...UPDATE ON HURRICANE DEAN NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT FRI AUG 17 2007 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1015 UTC. ...SPECIAL FEATURES... HURRICANE DEAN IS CENTERED NEAR 14.3N 60.9W AT 17/0900 UTC OR IN THE ST. LUCIA CHANNEL BETWEEN ST.LUCIA AND MARTINIQUE MOVING W AT 21 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 976 MB. MAXIMUM SUSTAINED WIND SPEED IS 85 KT WITH GUSTS TO 105 KT...MAKING DEAN A CATEGORY TWO HURRICANE. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC OR THE INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS MIATCPAT4/WTNT34 FOR MORE DETAILS. DEAN CONTINUES TO MOVE RATHER QUICKLY ALONG THE SOUTHERN PERIPHERY OF A DEEP LAYERED RIDGE. DEAN IS EXPECTED TO CONTINUE TO SLOWLY STRENGTHEN AS IT CONTINUES THROUGH THE LESSER ANTILLES AND ACROSS THE CENTRAL CARIBBEAN. HEAVY SHOWERS AND EMBEDDED THUNDERSTORMS COVER THE LESSER ANTILLES FROM GRENADA TO THE VIRGIN ISLANDS. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 12N-18N BETWEEN 58W-64W WITH CLUSTERS OF SIMILAR CONVECTION COVERING A BROADER AREA FROM 11N-19N BETWEEN 54W-67W. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 28W S OF 20N MOVING W 15-20 KT. A 1007 MB LOW HAS DEVELOPED ALONG THE WAVE NEAR 14N. OTHERWISE A BROAD LOW/MID LEVEL ROTATION IS OBSERVED WITH NO ASSOCIATED DEE CONVECTION. ISOLATED THUNDERSTORMS ARE FROM 11N-12N BETWEEN 27W-32W. TROPICAL WAVE IS ALONG 40W/41W S OF 20N MOVING W 15-20 KT. BROAD LOW/MID LEVEL SLIGHTLY TILTED CURVATURE REMAINS MOSTLY TO THE W OF THE WAVE AXIS. SCATTERED SHOWERS/THUNDERSTORMS ARE FROM 10N-13N BETWEEN 39W-45W. TROPICAL WAVE OVER THE CENTRAL CARIBBEAN IS ALONG 74W S OF 20N MOVING W NEAR 20 KT. WEAK BUT WELL DEFINED LOW LEVEL INVERTED-V CURVATURE IS IN THE CENTRAL CARIBBEAN. NO ASSOCIATED DEEP CONVECTION WITH SOME SCATTERED SHOWERS N OF 15N TO OVER JAMAICA FROM 74W-78W. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 15N16W 15N25W 12N31W 10N44W 12N55W BECOMING DISTORTED DUE TO HURRICANE DEAN. SEE SPECIAL FEATURES ABOVE. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 120 NM OF A LINE FROM 11N17W TO 7N31W AND WITHIN 90 NM OF LINE FROM 6N36W TO 5N40W. CLUSTERS OF SIMILAR CONVECTION ARE FROM 9N-13N E OF 17W TO THE COAST OF AFRICA AND WITHIN 120 NM OF LINE FROM 6N43W TO 11N55W. DISCUSSION... GULF OF MEXICO... AN UPPER LEVEL RIDGE FROM THE UPPER HIGH NEAR T.D. ERIN MOVING ACROSS S/CENTRAL TEXAS EXTENDS S OVER E MEXICO COVERING THE W GULF AND INDUCING A WEAK INVERTED TROUGH ACROSS THE CENTRAL GULF. THE DENSE CLOUD COVER OF 6 HOURS AGO IS BEGINNING TO CLEAR WITH THINNING MID/HIGH CLOUDS REMAINING OVER THE AREA. SOME SCATTERED SHOWERS/THUNDERSTORMS ARE WITHIN 90/120 NM ALONG THE COAST OF TEXAS AND MEXICO INTO THE BAY OF CAMPECHE. LARGE UPPER LOW IN THE W ATLC EXTENDS ACROSS FLORIDA GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WITHIN 75 NM OFF THE W COAST OF FLORIDA FROM 24N-29N BETWEEN THE FLORIDA COAST AND 86W. THE SURFACE RIDGE FROM THE ATLC EXTENDS ACROSS FLORIDA AND OVER THE E GULF GIVING THE REMAINDER OF THE GULF MOSTLY CLEAR SKIES THIS MORNING. CARIBBEAN SEA... THE LARGE UPPER LOW EXTENDS S ACROSS CUBA AND HAITI INTO THE NW CARIBBEAN N OF 13N W OF 73W TO OVER THE YUCATAN PENINSULA GENERATING SCATTERED CLUSTERS OF SHOWERS/ISOLATED THUNDERSTORMS N OF 17N TO OVER CUBA BETWEEN 75W-82W AND WITHIN 120 NM ALONG THE COAST OF N NICARAGUA N OF 13N AND HONDURAS E OF 87W. THE MAIN CONCERN THIS MORNING IS HURRICANE DEAN AS IT MOVES THROUGH THE LESSER ANTILLES BETWEEN ST. LUCIA AND MARTINIQUE...SEE SPECIAL FEATURES ABOVE. THE ITCZ ENTERS THE E PACIFIC REGION OVER PANAMA AND COSTA RICA PRODUCING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS TO THE SW CARIBBEAN S OF 11N FROM W COAST OF COLOMBIA TO THE COAST OF COSTA RICA. THE REMAINDER OF THE AREA REMAINS RATHER CLEAR THIS MORNING BUT CONDITIONS WILL CONTINUE TO DETERIORATE AS HURRICANE DEAN CROSSES THE AREA DURING NEXT FEW DAYS. ATLANTIC OCEAN... LARGE UPPER LOW IS CENTERED IN THE W ATLC OVER THE N BAHAMA ISLANDS NEAR 27N77W COVERING THE AREA W OF 71W ACROSS FLORIDA AND INTO THE NW CARIBBEAN. ALTHOUGH THE W ATLC IS COVERED WITH MOSTLY DRY NEAR STABLE AIR IT IS ABLE TO PRODUCE SCATTERED SHOWERS/ISOLATED THUNDERSTORMS FROM CUBA TO OVER THE BAHAMA ISLANDS SW OF A LINE FROM 23N72W TO 27N77W. AN UPPER HIGH IS TO THE E NEAR 24N62W AND AN UPPER LOW IS NEAR 27N49W BUT BOTH ARE RATHER BENIGN UPPER FEATURES. BROAD UPPER RIDGE EXTENDS E/W FROM OFF AFRICA TO NEAR 40W WITH THE AXIS ALONG 20W/21W. DRY STABLE AIR DOMINATES THE ATLC WITH THE EXCEPTION OF HURRICANE DEAN. A BROAD SURFACE RIDGE ALSO DOMINATES THE ATLC INTO THE E GULF OF MEXICO ANCHORED BY A PAIR OF 1030 MB HIGHS...ONE JUST W OF THE AZORES AND THE SECOND JUST NE OF THE AZORES GIVING THE ATLC FAIR WEATHER AND MODERATE TRADE WINDS E OF 50W. $$ WALLACE