000 AXNT20 KNHC 181751 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT SAT AUG 18 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1715 UTC. ...SPECIAL FEATURE... EXTREMELY DANGEROUS HURRICANE DEAN THREATENS HAITI...JAMAICA AND THE CAYMAN ISLANDS FIRST...AND AFTERWARD THE YUCATAN PENINSULA. AT 18/1800 UTC...THE CENTER OF HURRICANE DEAN WAS LOCATED NEAR LATITUDE 15.9 NORTH...LONGITUDE 69.4 WEST OR ABOUT 505 MILES EAST-SOUTHEAST OF KINGSTON JAMAICA AND ABOUT 175 MILES SOUTH OF SANTO DOMINGO IN THE DOMINICAN REPUBLIC. DEAN IS MOVING TOWARD THE WEST-NORTHWEST NEAR 15 KT. MAXIMUM SUSTAINED WINDS REMAIN NEAR 130 KT WITH HIGHER GUSTS. DEAN IS A MAJOR HURRICANE CATEGORY FOUR ON THE SAFFIR-SIMPSON SCALE. THE ESTIMATED MINIMUM CENTRAL PRESSURE REPORTED BY AN AIR FORCE HURRICANE HUNTER PLANE IS 930 MB. ALL INTERESTS IN THE CARIBBEAN SEA AND THE GULF OF MEXICO SHOULD CLOSELY MONITOR THE PROGRESS OF THIS POWERFUL HURRICANE. PLEASE SEE THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC OR THE LATEST PUBLIC ADVISORY UNDER MIATCPAT4/WTNT34 KNHC FOR MORE DETAILS INCLUDING THE MOST RECENT WATCH AND WARNING INFORMATION. FOR STORM INFORMATION SPECIFIC TO YOUR AREA... INCLUDING POSSIBLE INLAND WATCHES AND WARNINGS...PLEASE MONITOR PRODUCTS ISSUED BY YOUR LOCAL WEATHER OFFICE. NUMEROUS MODERATE TO STRONG CONVECTION IS WITHIN 180 NM OF CENTER. ...TROPICAL WAVES... TROPICAL WAVE IS MOVING THROUGH THE E ATLC ALONG 36W SOUTH OF 20N MOVING W AT 10 TO 15 KT. THIS WAVE CONTINUES TO EXHIBIT A BROAD ENVELOPE OF CYCLONIC TURNING WITH CLUSTERS OF MODERATE CONVECTION ON THE SOUTHERN END OF THE WAVE AXIS FROM 5N-11N BETWEEN 32W-40W. THE HOVMOLLER DIAGRAM CLEARLY SHOWS THE WESTWARD PROPAGATION OF THIS CONVECTIVE ACTIVITY. A TROPICAL WAVE IS ALONG 48W/49W SOUTH OF 20N. THIS WAVE IS MOVING W NEAR 15 KT. THE UW-CIMSS SSMI-DERIVED TOTAL PRECIPITABLE WATER SHOWS UP WELL A BROAD AREA OF CYCLONIC TURNING NEAR 11N. SCATTERED MODERATE CONVECTION IS FROM 10N-12N BETWEEN 49W-52W. THIS LARGE TROPICAL WAVE WILL ENTER THE TROPICAL N ATLC WATERS SUN THEN MOVE INTO THE E CARIBBEAN MON. TROPICAL WAVE IS ALONG 84W SOUTH OF 20N MOVING WEST NEAR 20 KT. AN INVERTED V PATTERN REMAINS EVIDENT WITH THIS WAVE. THERE IS A CLUSTER OD MODERATE CONVECTION OVER THE GULF OF HONDURAS ASSOCIATED WITH THE WAVE. MOISTURE FROM THIS WAVE SHOULD AFFECT BELIZE AND THE YUCATAN PENINSULA THIS AFTERNOON AND TONIGHT. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 13N17W 12N25W 14N35W 12N42W 8N58W. OUTSIDE OF THE CONVECTION ALREADY DESCRIBED WITH THE TROPICAL WAVES AND HURRICANE DEAN...DEEP CONVECTION IS MINIMAL NEAR THE ITCZ. DISCUSSION... THE GULF OF MEXICO... HIGH PRES RIDGE ALONG THE N GULF WATERS DOMINATES THE REGION KEEPING WEATHER CONDITIONS PRETTY QUIET...BUT BIG CHANGES ARE IN STORE FOR THE GULF NEXT WEEK AS HURRICANE DEAN MOVES IN TUE AND WED. AN UPPER LOW OVER FLORIDA IS GENERATING SCATTERED SHOWERS AND TSTMS OVER THE SE CORNER OF THE GULF AND THE FLORIDA KEYS. SIMILAR ACTIVITY IS SEEN NEAR THE LOUISIANA/TEXAS BORDER AND ADJACENT COASTAL WATERS. SURFACE WINDS OVER MOST OF THE GULF OF MEXICO ARE FROM THE E TO SE AT 15 KT. A SFC TROUGH IS ANALYZED OVER THE SW PORTION OF THE GULF...INCLUDING THE BAY OF CAMPECHE. THE TROUGH RUNS FROM 22N96W TO 18N94W. SCATTERED SHOWERS ARE RELATED TO THE TROUGH NEAR 21N96W. ALOFT...AN UPPER HIGH OVER NW MEXICO IS PRODUCING A NELY WIND FLOW MAINLY WEST OF 86W. THESE WINDS ARE TRANSPORTING SOME UPPER LEVEL MOISTURE ACROSS THE AREA. CYCLONIC FLOW COVERS THE REMAINDER OF THE GULF ASSOCIATED WITH THE AFOREMENTIONED UPPER LOW. THE CARIBBEAN SEA... ALL THE ATTENTION REMAINS FOCUSED ON THE FIRST MAJOR HURRICANE OF THE SEASON NAMED DEAN. IT WILL CONTINUE TO HAVE SIGNIFICANT IMPACTS ON THE CARIBBEAN SEA OVER THE NEXT SEVERAL DAYS. FLUCTUATIONS IN ITS INTENSITY ARE EXPECTED REACHING THE PEAK OVER THE NW CARIBBEAN WHERE THE OCEAN HEAT CONTENT IS VERY HIGH. DEAN COULD BECOME A CATEGORY FIVE HURRICANE AT ANY TIME BEFORE IT REACHES THE YUCATAN PENINSULA LATE MONDAY OR EARLY TUESDAY. THIS TROPICAL CYCLONE IS STEERED BY A HIGH OVER THE WESTERN ATLANTIC AND A LOW OVER FLORIDA THAT IS FORECAST TO MOVE WWD INTO THE GULF OF MEXICO SUN. A RAIN BAND ASSOCIATED WITH DEAN IS OVER PUERTO RICO APPROACHING DOMINICAN REPUBLIC. SAN JUAN REPORTED HEAVY RAIN AND GUSTY WINDS OF NEAR 30 KT DURING THE LAST FEW HOURS. DIFFLUENCE ALOFT IS ENHANCING SCATTERED SHOWERS AND TSTMS OVER THE SW CARIBBEAN. THIS ACTIVITY IS SPREADING OVER NICARAGUA AND COSTA RICA. IN THE UPPER LEVELS...A TROUGH EXTENDS FROM THE ABOVE MENTIONED UPPER LOW ACROSS WESTERN CUBA AND THE NW CARIBBEAN TO NEAR 16N83W. AN UPPER LEVEL HIGH IS OVER THE SW CARIBBEAN. IMPRESSIVE UPPER LEVEL OUTFLOW IN ALL QUADRANTS IS NOTED WITH HURRICANE DEAN E OF 73W. THE ATLANTIC OCEAN... AS IS TYPICAL FOR THIS TIME OF THE YEAR...THE AZORES-BERMUDAS HIGH DOMINATES THE ATLANTIC OCEAN WITH A 1032 MB CENTER NEAR 39N31W. THIS FEATURE IS PRODUCING WIDESPREAD FAIR WEATHER AND MODERATE TRADE WINDS E OF 60W. WINDS ARE A LITTLE STRONGER BETWEEN THIS HIGH AND THE LARGE TROPICAL WAVE LOCATED ALONG 48W/49W REACHING 25 KT. IN THE UPPER LEVELS...AN UPPER LOW IS SPINNING NEAR S FLORIDA. LIFT AHEAD OF THIS FEATURE IS SUPPORTING SCATTERED SHOWERS AND TSTMS OVER THE BAHAMAS AND ADJACENT WATERS S OF 28N W OF 75W. THE RISK FOR A FEW SEVERE TSTMS REMAINS OVER SOUTH FLORIDA DUE TO THE PRESENCE OF THIS UPPER LOW. AN UPPER RIDGING IS TO THE E OF THE UPPER LOW WHICH IS STEERING DEAN WNW. ANOTHER UPPER LOW IS NEAR 27N52W MOVING W. LIGHTNING DATA HAS BEEN DEPICTING A FEW ISOLATED TSTMS ASSOCIATED WITH THIS FEATURE MAINLY ON THE WEST SIDE. UPPER RIDGING EXTENDING W FROM AFRICA GENERALLY DOMINATES THE ERN ATLC. $$ GR