000 AXNT20 KNHC 222346 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT WED OCT 22 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...TROPICAL WAVES... A TROPICAL WAVE IS ALONG 25W S OF 14N MOVING W NEAR 5-10 KT. THIS WAVE CONTINUES TO REMAIN WEAK AND EMBEDDED WITHIN THE ITCZ. NO ORGANIZED SHOWERS OR DEEP CONVECTION ASSOCIATED WITH THE WAVE. A TROPICAL WAVE IS ALONG 52W/53W S OF 21N MOVING W NEAR 10 KT. THE SSMI-TPW PRODUCT FROM CIMSS INDICATES A NORTHWARD SURGE OF MOISTURE ALONG THE WAVE AXIS. THE WAVE IS BENEATH A SHARP UPPER-LEVEL TROUGH WITH AXIS ALONG 51W. MOST OF THE CONVECTIVE ACTIVITY APPEARS TO BE ASSOCIATED WITH THIS UPPER FEATURE WHILE ONLY A FEW SHOWERS ARE ALONG THE WAVE AXIS. A TROPICAL WAVE IS ALONG 80W S OF 17N MOVING W NEAR 10-15 KT. THE WAVE IS EMBEDDED WITHIN STRONG EASTERLY SURFACE FLOW ACROSS THE CARIBBEAN. CONVECTION ASSOCIATED WITH THIS WAVE IS DYING DOWN OVER THE SW CARIBBEAN. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 9N13W 10N23W 8N35W 12N51W 9N61W. CLUSTERS OF SCATTERED MODERATE CONVECTION ARE APPROACHING THE WEST COAST OF AFRICA THROUGH SIERRA LEONE AND GUINEA. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS WITHIN 30 NM EITHER SIDE OF AXIS BETWEEN 39W-45W. SIMILAR CONVECTION IS FOUND FROM 9N-14N BETWEEN 45W-50W. ...DISCUSSION... GULF OF MEXICO... A BROAD UPPER-LEVEL HIGH CENTERED OVER THE CARIBBEAN SEA NEAR 16N79W EXTENDS WEAK RIDGING ACROSS THE ENTIRE GULF REGION AND THE FLORIDA PENINSULA PRODUCING SW TO W UPPER-LEVEL FLOW. A SHORT-WAVE TROUGH CURRENTLY OVER THE FAR WEST GULF NEAR THE AREA OF TAMPICO WILL MOVE MAINLY EWD ACROSS THE SOUTH-CENTRAL GULF TONIGHT AND TOMORROW. UPPER DIFFLUENCE BETWEEN THIS TWO UPPER-LEVEL FEATURES IS SUPPORTING A LARGE AREA OF CLOUDINESS WITH EMBEDDED SHOWERS AND ISOLATED TSTMS OVER THE SE PORTION OF THE GULF...SOUTH-CENTRAL FLORIDA AND THE KEYS...AND WESTERN CUBA WHERE LOCALLY HEAVY RAIN MAY OCCUR. AT THE SURFACE...A TROUGH IS ANALYZED FROM A 1012 MB SFC LOW OVER BELIZE NWD THROUGH THE YUCATAN PENINSULA AND THE SE PORTION OF THE GULF ALONG 23N87W 25W83W. ANOTHER SURFACE TROUGH EXTENDS FROM A 1011 MB SFC LOW NEAR 23N95W TO 28N96W. VIS SAT IMAGERY REVEALS A SWIRL OF LOW CLOUDS ASSOCIATED WITH THIS LOW PRES CENTER. ANOTHER SWIRL OF LOW CLOUDS IS SPINNING OVER THE CENTRAL GULF NEAR 25N89W LIKELY ASSOCIATED WITH A NEW SFC LOW FORECAST BY THE GFS COMPUTER MODEL TO DEVELOP OVER THE NORTH-CENTRAL GULF IN ABOUT 12-24 HOURS. A COLD FRONT IS ALSO FORECAST TO ENTER THE NW GULF WATERS BY EARLY THURSDAY BRINGING MODERATE TO STRONG NORTHERLY WINDS IN WAKE OF THE FRONT. WINDS ARE ALSO EXPECTED TO INCREASE ACROSS THE NE CORNER OF THE GULF BY THU DUE TO A TIGHT PRES GRADIENT BETWEEN A STRONG SURFACE HIGH ALONG THE EASTERN SEABOARD AND THE LOW PRES OVER THE N-CENTRAL GULF. CARIBBEAN SEA... A 1010 MB SURFACE LOW PRESSURE IS CENTERED OVER THE NRN BELIZE COAST NEAR 18N88W WITH A SURFACE TROUGH EXTENDING NWD ACROSS THE ERN YUCATAN PENINSULA INTO THE SE GULF OF MEXICO. SCATTERED MODERATE CONVECTION COVERS MUCH OF THE NW CARIBBEAN PARTICULARLY WITHIN 150 NM NE OF LINE FROM 21N87W TO 16N81W. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION CONTINUES TO DEVELOP OVER PARTS OF CENTRAL AMERICA BUT MAINLY OVER NICARAGUA AND HONDURAS. THIS LOW IS EXPECTED TO MOVE N-NW TONIGHT AND THU AND WILL MERGE WITH THE COLD FRONT FORECAST TO ENTER THE NW GULF OF MEXICO EARLY THURSDAY. AN UPPER-LEVEL HIGH CENTERED JUST SW OF JAMAICA DOMINATES THE ENTIRE CARIBBEAN SEA AND IS HELPING TO INDUCE THE CONVECTIVE ACTIVITY OVER THE NW CARIBBEAN. MODERATE TRADE WINDS OF 15 TO 20 KT ARE BLOWING ACROSS THE BASIN. A PAIR OF CLUSTERS WITH MODERATE/ISOLATED STRONG CONVECTION ARE AFFECTING WESTERN VENEZUELA AND NORTHERN COLOMBIA. SCATTERED SHOWERS AND ISOLATED TSTMS ARE BETWEEN THE SRN WINDWARD ISLANDS AND THE ABC ISLANDS. THIS ACTIVITY APPEARS TO BE THE RESULT OF A DIFFLUENT PATTERN ALOFT ASSOCIATED WITH THE AFOREMENTIONED UPPER-LEVEL RIDGE. ATLANTIC OCEAN... A RIDGE/TROUGH/RIDGE/TROUGH PATTERN DOMINATES THE ENTIRE FORECAST AREA. THE BROAD UPPER-LEVEL HIGH CENTERED OVER THE CARIBBEAN SEA EXTENDS A RIDGE NWD ACROSS THE BAHAMAS INTO THE W ATLC. ABUNDANT CLOUDINESS AND ISOLATED SHOWERS ARE ACROSS THE NRN BAHAMAS AS DEEP TROPICAL MOISTURE STREAMS EAST FROM THE SURFACE TROUGH ACROSS THE SE GULF OF MEXICO. AN UPPER-LEVEL LOW REMAINS OVER THE CENTRAL ATLC NEAR 26N52W. THIS LOW HAS A TROUGH EXTENDING MAINLY SWD INTO THE DEEP TROPICS. UPPER DIFFLUENCE BETWEEN THIS TROUGH AND A WEAK RIDGE TO THE EAST CENTERED NEAR 27N42W IS GENERATING A WIDE BAND OF MULTILAYERED CLOUDS WITH EMBEDDED SHOWERS AND ISOLATED TSTMS BETWEEN 42W-49W ALL THE WAY NORTH OF THE ITCZ AXIS. PATCHES OF LOW-LEVEL CLOUDS AND MODERATE TRADE WINDS ARE OBSERVED OVER THE E ATLC LARGELY IN PART TO A SURFACE RIDGE COVERING THE E ATLC E OF 40W. A BROAD UPPER-LEVEL TROUGH WITH AXIS JUST WEST OF THE THE CANARY AND CAPE VERDE ISLANDS DOMINATES THE E ATLC. THE BASE OF THIS TROUGH REACHES 12N AND IS SUPPORTING A COLD FRONT OVER MOROCCO. $$ GR