000 AXNT20 KNHC 202320 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 705 PM EST WED DEC 20 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... METEOROLOGICAL ANALYSIS...WEATHER OBSERVATIONS...AND RADAR. BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2300 UTC. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 6N10W 4N48W 3N53W. SCATTERED MODERATE CONVECTION FROM 2N TO 5N BETWEEN 38W AND 47W. ...DISCUSSION... GULF OF MEXICO... SHORT WAVE TROUGH IS ENTERING THE WESTERN GULF OF MEXICO W OF 93W...ROUNDING THE BASE OF A STRONG UPPER LOW PRES SYSTEM CENTERED OVER ERN COLORADO. COPIOUS MID AND UPPER LEVEL MOISTURE CONTINUES TO STREAM FROM S TO N AHEAD OF THE TROUGH BETWEEN 87W AND 94W. AN UPPER LEVEL RIDGE CENTERED OVER S FLORIDA REMAINS IN PLACE OVER THE ERN GULF...AND MAINTAINING GENERALLY DRY AND STABLE CONDITIONS IN THE MID AND UPPER LEVELS E OF 87W. AT THE SURFACE...A COLD FRONT IS MOVING E TOWARD THE TEXAS COAST...AND SHOULD PUSH INTO THE WESTERN GULF WATERS LATE TONIGHT. BUOYS AND SHIP OBSERVATIONS REPORT MODERATE TO FRESH E TO SE WINDS E OF 90W ON THE PERIPHERY OF HIGH PRES CENTERED OVER THE MID ATLC STATES. MODERATE TO FRESH SLY WINDS ARE EVIDENT W OF 90W AHEAD OF A 1008 MB LOW PRES CENTER OVER NE MEXICO. MOIST SWLY FLOW AHEAD OF THE SHORT WAVE IS RIDING OVER WEDGE OF HIGH PRES OVER SE UNITED STATES...PROVIDING ENOUGH ISENTROPIC LIFT TO ALLOW SCATTERED SHOWERS AND A FEW THUNDERSTORMS OVER MISSISSIPPI DELTA AREA AND ADJACENT COASTAL WATERS N OF 27N. THE FRONT WILL STALL OVER THE CENTRAL GULF ON FRI...FOLLOWED BY A STRONGER REINFORCING SHOT THIS WEEKEND IN RESPONSE TO ANOTHER SHORT WAVE TROUGH PUSHING DOWN THE FRONT RANGE OF THE ROCKIES. ALTHOUGH THERE IS STILL SOME UNCERTAINTY IN TIMING AND INTENSITY...THE STRONGER PUNCH BRING GALE FORCE WINDS TO GULF WATERS THIS WEEKEND. CARIBBEAN SEA... AN UPPER LEVEL LOW PRES SYSTEM IS CENTERED NEAR 19N80W...JUST W OF JAMAICA. UPPER LEVEL DIFFLUENCE IS PROMOTING SCATTERED CONVECTION BETWEEN JAMAICA AND HAITI AND TO A LESSER EXTENT OVER EASTERN CUBA AND THE WINDWARD PASSAGE. DRY MID AND UPPER AIR CONTINUES TO ADVECT SWD ON THE W SIDE OF THE UPPER LOW...KEEPING GENERALLY STABLE CONDITIONS OVER THE REMAIN OF THE CARIBBEAN BASIN...WITH SWLY UPPER FLOW PREVAILING ACROSS THE BASIN S OF THE LOW. SURFACE OBSERVATIONS SHOW GENERALLY LIGHT TO MODERATE ELY FLOW ACROSS THE CARIBBEAN...AT THE BASE OF HIGH PRES TO THE N. THIS FLOW WILL INCREASE AS HIGH PRES BUILDS TO THE N OVER THE NEXT COUPLE OF DAYS. MEANWHILE THE UPPER LOW WILL OPEN INTO A TROUGH AND SHIFT NE OF HISPANIOLA BY THIS WEEKEND...AS UPPER RIDGE BUILDS OVER THE WESTERN GULF. ATLANTIC OCEAN... UPPER LOW REMAINS CENTERED W OF CAPE VERDE ISLANDS NEAR 28N23W WITH ASSOCIATED 1016 MB SURFACE LOW REMAINING STATIONARY AND WEAKENING. W OF THIS...DEEP LAYER RIDGE WITH 1023 MB SURFACE PRES IS CENTERED NEAR 31N39W. AN UPPER TROUGH EXTENDS FROM 27N64W TO THE SOUTHERN BAHAMAS NEAR 23N72W. SOME EVIDENCE OF A SURFACE REFLECTION OF THIS EXTENDING FROM 22N67W TO 28N56W. SCATTERED MODERATE CONVECTION IS EVIDENT WITHIN 180 NM SE OF THE SURFACE TROUGH. N OF THIS...SATELLITE IMAGERY AND SHIP OBSERVATIONS SHOW NLY SURGE WITH AN APPROACHING COLD FRONT EXTENDING FROM 30N59W TO 29N71W THEN BECOMING STATIONARY TO THE GEORGIA COAST. FRESH TO STRONG N TO NE WINDS FOLLOW BEHIND THE FRONT...BUT WILL DIMINISH THIS WEEKEND AHEAD OF ANOTHER FRONT EMERGING OFF THE COAST. MEANWHILE...MODERATE TO FRESH ELY SURFACE FLOW PERSISTS OVER THE TROPICAL ATLC S OF 20N...AT THE BASE OF THE RIDGE OVER THE CENTRAL ATLC. THIS WILL DIMINISH BRIEFLY ON THU AS THE RIDGE WEAKENS AHEAD OF THE COLD FRONT PUSHING E...BUT WILL INCREASE AGAIN FRI INTO THE WEEKEND AS HIGH PRES STRENGTHENS. FURTHER S...UPPER RIDGE CENTERED NEAR 4N41W IS ENHANCING SCATTERED CONVECTION ALONG THE ITCZ W OF 38W. $$ CHRISTENSEN