000 AXNT20 KNHC 121750 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT SAT AUG 12 2006 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...WEATHER OBSERVATIONS...RADAR... AND METEOROLOGICAL ANALYSIS. BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1715 UTC. ...TROPICAL WAVES... TROPICAL WAVE IS JUST OFF THE W COAST OF AFRICA ALONG 18W S OF 20N MOVING W NEAR 10 KT. THE 12/1100 UTC DAKAR SOUNDING SUGGESTS THAT THE WAVE HAS MOVED THROUGH AT LEAST BETWEEN 850MB AND 600MB WHERE ESE/SE FLOW WAS OBSERVED. LIGHT N/NW FLOW WAS REPORTED AT THE SURFACE THOUGH...BUT THIS MAY BE MORE DUE TO LOCAL/DIURNAL EFFECTS. LOW CLOUD MOTIONS REVEAL SOME CYCLONIC CURVATURE ABOUT THE ANALYZED AXIS...BUT OVERALL IT IS DIFFICULT TO LOCATE WITH THE QUASI STATIONARY MONSOON TROUGH NEARBY. NONETHELESS...HAVE PLACED THE AXIS SLIGHTLY W OF THE 0600 UTC POSITION DUE TO THE DAKAR SOUNDING. A SMALL PATCH OF MODERATE CONVECTION LIES JUST W OF THE AXIS FROM 11N TO 14N BETWEEN 18W AND 20W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS MOVING THROUGH WRN SENEGAL AND ADJACENT ATLC WATERS FROM 13N TO 16N BETWEEN 16W AND 18W. TROPICAL WAVE IN THE ATLANTIC OCEAN...ABOUT 500NM E OF THE LESSER ANTILLES...IS ALONG 52W S OF 19N MOVING W 10 TO 15 KT. THIS WAVE CONTINUES TO SHOW A WELL DEFINED INVERTED V PATTERN. CONVECTION REMAINS LIMITED NEAR THE WAVE. SCATTERED MODERATE CONVECTION DOES LIE W OF THE WAVE FROM 12N TO 17N BETWEEN 53W AND 57W...BUT THIS MAY BE MORE ASSOCIATED WITH THE FLOW AROUND THE MID TO UPPER HIGH JUST TO THE NW OF THE WAVE. A 1011MB SURFACE LOW HAS BEEN ADDED ALONG THIS WAVE NEAR 12N52W DUE TO THE LOW CLOUD SWIRL EVIDENT IN THIS AFTERNOONS VISIBLE IMAGERY AND SOME REFLECTION OF THIS EVIDENT IN THIS MORNINGS QUIKSCAT PASS. TROPICAL WAVE IN THE CARIBBEAN IS ALONG 75W/76W S OF 21N MOVING W NEAR 15 KT. SURFACE WINDS IN THE VICINITY DO SHOW SOME CYCLONIC TURNING ABOUT THE AXIS...BUT DEEP CONVECTION NEAR THE WAVE N OF 12N REMAINS AT A MINIMUM. THIS PORTION OF THE WAVE LIES UNDERNEATH A FAIRLY DRY UPPER LOW WHICH IS LIKELY HELPING TO SUPPRESS/DECOUPLE ANY LOW LEVEL INSTABILITY. A FEW SMALL CLUSTERS OF SCATTERED MODERATE CONVECTION ARE SEEN W OF THE WAVE JUST OFF THE COAST OF COSTA RICA AND PANAMA. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 12N19W 9N33W 12N50W 12N54W 10N62W TO INLAND OVER SOUTH AMERICA NEAR 10N73W. CLUSTERS OF SCATTERED MODERATE CONVECTION ARE WITHIN 250 NM N OF EITHER SIDE OF THE AXIS FROM 28W-44W AND FROM 10N-15N BETWEEN 53W-63W. ONLY ISOLATED SHOWERS AND TSTMS DOT THE REMAINING ITCZ AREA. ...DISCUSSION... GULF OF MEXICO... THE UPPER LEVEL LOW COVERING THE W GULF CENTERED CONTINUES TO MOVE FURTHER INLAND ALONG THE TEXAS/MEXICO BORDER JUST W OF BROWNSVILLE. MID TO UPPER LEVEL ANTICYCLONE IS SEEN SPINNING JUST OFF THE ATLC COAST OF NORTH/CENTRAL FLORIDA THAT EXTENDS W INTO THE EASTERN GULF. UPPER DIFFLUENT AIR BETWEEN THESE FEATURES...ALONG WITH LOW LEVEL CONFLUENCE BETWEEN THE ATLC SFC RIDGE EXTENDING INTO THE GULF AND THE PLEASANT HIGH THAT BROUGHT COOLER AIR INTO THE MID ATLC STATES...IS PRODUCING ISOLATED SHOWERS AND TSTMS IN THE NRN GULF/GULF COASTAL REGION FROM 27N TO 31N BETWEEN 84W AND 96W. OVERALL THOUGH THE GULF REMAINS FAIRLY QUIET...WITH WEAK HIGH PRESSURE DOMINATING AT THE SURFACE AND WINDS GENERALLY LIGHT. THE STRONGEST WINDS IN THE GULF THIS AFTERNOON ARE IN THE WSW GULF FROM THE SE AT 15KT...DUE TO THE INTERACTION OF THE WRN PORTION OF THE ATLC HIGH WITH LOWER PRESSURE OVER MEXICO. ATLC SURFACE RIDGE AXIS EXPECTED TO SHIFT SOUTH OVER THE NEXT COUPLE OF DAYS AHEAD OF FRONT CURRENTLY DRAPED THROUGH GEORGIA...WITH PREFRONTAL MOISTURE INCREASING SHOWER/TSTM CHANCES ESPECIALLY IN THE NE/E GULF. CARIBBEAN SEA... UPPER TROUGHING DOMINATES MUCH OF THE WEST AND CENTRAL CARIBBEAN THIS AFTERNOON...WITH TWO DISTINCT MID TO UPPER LEVEL LOW CENTERS SEEN ON WV IMAGERY. ONE LIES JUST S OF JAMAICA NEAR 16N77W WITH THE OTHER IN THE SW ATLC/N OF HISPANIOLA NEAR 21N70W. INSTABILITY AROUND THE BASE OF THIS UPPER TROUGH SEEMS TO BE SPARKING ISOLATED SHOWERS/TSTMS IN THE NW CARIBBEAN BETWEEN JAMAICA AND BELIZE. MID TO UPPER LEVEL ANTICYCLONIC FLOW AND DRY AIR CONTINUES TO AFFECT MUCH OF THE ERN CARIBBEAN...THOUGH A FEW SHOWERS AND TSTMS ARE MOVING E TO W ALONG THE SRN PERIPHERY OF THE UPPER HIGH IN THE SE CARIBBEAN...JUST N OF THE VENEZUELAN COAST. ASIDE FROM THE TROPICAL WAVE ALONG 76W THE SW PORTION OF THE ATLC HIGH CONTINUES TO EXTEND INTO THE CARIBBEAN PRODUCING 15 TO 25 KT TRADE WINDS. SIMILAR CONDITIONS EXPECTED AT THE SURFACE OVER THE NEXT COUPLE OF DAYS. ATLANTIC OCEAN... AN UPPER HIGH IS LOCATED JUST EAST OF NORTH/CENTRAL FLORIDA THIS AFTERNOON...WITH THE AXIS GENERALLY ALONG 28N EXTENDING E OUT TO NEAR 55W. SURFACE COLD FRONT IS EXTENDING E FROM GEORGIA/S CAROLINA. PATCHES OF SCATTERED MODERATE CONVECTION ARE SEEN S OF THIS FRONT FROM 28N TO 32N BETWEEN 55W AND 78W...MOVING W TO E ALONG THE NRN PERIPHERY OF THE UPPER HIGH/SRN PERIPHERY OF THE UPPER TROUGH CENTERED NEAR THE CANADIAN MARITIMES. OTHERWISE IN THE WRN ATLC...AN UPPER LOW IS CENTERED JUST NORTH OF HISPANIOLA WITH AN UPPER HIGH ENE OF THE LEEWARD ISLANDS NEAR 19N56W. ANOTHER UPPER LOW NEAR 27N37W IS GENERATING A COUPLE OF SMALL SHOWERS AND TSTMS. THE ERN ATLC CONTINUES TO BE DOMINATED BY THE UPPER HIGH EXTENDING W FROM AFRICA. SURFACE HIGH CENTERS ARE ANALYZED NEAR 25N47W AND NEAR 28N28W AT 1021MB AND 1020MB RESPECTIVELY. MAIN FOCUS OVER THE NEXT 24 TO 48HRS WILL BE SHOWERS/TSTMS ASSOCIATED WITH THE SURFACE FRONT SAGGING SOUTH INTO FLORIDA AND THE ADJACENT ATLC WATERS...ALONG WITH TRACKING THE TWO TROPICAL WAVES ALONG 52W AND 18W. $$ WILLIS