000 AGXX40 KNHC 201834 MIMATS MARINE WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 230 PM EST THU DEC 20 2007 MARINE WEATHER DISCUSSION FOR GULF OF MEXICO...CARIBBEAN SEA AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W. GULF OF MEXICO... QUICK CHANGES ARE PRESENTLY TAKING PLACE ACROSS THE GULF. STRONG SLY FLOW HAS SET-UP OVER W GULF TO 95W AS BOTH QUIKSCAT AND BUOY DATA ARE NOW SHOWING SE-S WINDS IN THE 20-25 KT RANGE N OF 23N. WINDS ELSEWHERE ARE E-SE 15 KT. THIS IS ALL AHEAD OF FRONTAL SYSTEM MOVING OFF THE TEXAS COAST WITH ATLC HIGH PRES RIDGING W ALONG 30N INTO THE GULF. SEAS ARE 4-6 FT W OF 94W AND 3-5 FT E OF 94W. THE STRONG SLY FLOW WILL RAPIDLY SHIFT E ACROSS THE GULF THROUGH FRI AS A SHORTWAVE TROUGH MOVING THROUGH E TEXAS CRANKS OUT A SURFACE LOW OVER THE NRN GULF TONIGHT AND MOVES E TOWARDS N FLORIDA ON FRI...AND E INTO THE FAR NW ATLC WATERS ON FRI DRAGGING THE COLD FRONT THROUGH THE GULF AND TO E OF THE AREA LATE FRO NIGHT. THE MAIN EMPHASIS IN WINDS WILL BE WITH RESPECT WITH THE LOW SINCE THE COLD FRONT WILL BE RATHER WEAK. WINDS BEHIND THE LOW WILL SHIFT TO NW 15-20 KT THROUGH FRI...THEN QUICKLY COME BACK DOWN TO N-NE 10-15 KT LATE FRI AND EARLY SAT OVER THE NE PART...E TO SE 10-15 KT OVER THE MIDDLE PART AND SE INCREASING RETURN FLOW OVER THE GULF THROUGHOUT SAT. WITH REGARDS TO TIMING OF NEXT FRONT TO MOVE OFF THE TEXAS COAST...MODELS DIFFER TO SOME RESPECT ON THIS. GFS/NOGAPS AND UKMET SIMILAR IN DEPICTING FRONT TO ENTER THE NE GULF LATE SAT. OTHER GLOBAL MODELS AND THE NAM ARE SIMILAR IN SHOWING A FASTER ENTRY TIME OF FRONT INTO THE GULF. FOR THIS PACKAGE WILL LEAN TOWARDS THE SLOWER SOLN FOR INITIAL COLD FRONT TIMING INTO THE GULF. MODELS THEN AGREES THAT FRONT REACHES FROM THE FLORIDA PANHANDLE TO E BAY OF CAMPECHE SUN AFTERNOON...AND EXITS THE GULF SUN NIGHT. WINDS BEHIND THIS FRONT ARE EXPECTED TO BE NW-N 20-30 KT OVER THE W GULF AND 15-20 KT ELSEWHERE BEHIND THE FRONT. NWW3 HAS SEAS BUILDING UP TO 11 FT OVER THE SW GULF DURING SUN...AND TO 6 FT ELSEWHERE. WINDS THEN BECOME NE-E 15-20 KT OVER THE GULF N OF ABOUT 25N MON AND 10-15 KT S OF 25N...THEN VEER ONCE AGAIN AND INCREASE IN RETURN SLY FLOW LATE MON INTO TUE OVER THE FAR W GULF AS THE NEXT FRONTAL SYSTEM AND POSSIBLE ATTENDANT LOW (A FEW OF THE GLOBAL MODELS HINT AT THIS) MOVE TO THE TEXAS COAST...AND HIGH PRES N OF THE AREA SLIDES E TO OFFSHORE THE MID-ATLC COAST. WINDS WILL BE SE-S GENERALLY 15-20 KT OVER THE N CNTRL GULF E OF 90W AND SE-S 10-15 KT ELSEWHERE EXCEPT 10-15 KT BEHIND THE FRONT. SW N ATLANTIC... WEAKENING FRONTAL TROUGH EARLIER ANALYZED OVER THE FAR E PORTION OF THE AREA DISSIPATED THIS MORNING. A WEAK TROUGH ALONG 67W FROM 23N-29N IS MOVING W 15 KT. A QUIKSCAT PASS FROM AROUND 1000 UTC THIS MORNING SHOWED NE-E 20 KT WINDS WITHIN 180 NM E OF THE TROUGH. WINDS ACROSS THE REMAINDER OF THIS ZONE ARE GENERALLY E-SE 10-15 KT WITH SEAS IN THE 3-5 FT RANGE...EXCEPT 5-7 FT IN RESIDUAL NE SWELL E OF 70W. THE TAIL-END OF A COLD FRONT FROM 31N75W TO 31N80W WILL WEAKEN AS REACHES THE FAR NE PART BY LATE TONIGHT. LIGHT N-NE WINDS ARE BEHIND THIS FRONT. WINDS WILL VEER TO THE S AND INCREASE OVER THE FAR NW CORNER BEGINNING TONIGHT IN ADVANCE OF THE AFOREMENTIONED GULF LOW PRES. THESE WINDS WILL INCREASE TO 20-25 KT FRI AS THE LOW QUICKLY EMERGES OFF THE NE FLORIDA COAST AND TRACKS TO A PSN NEAR 30N78W BY FRI AFTERNOON...AND TO NEAR 30N75W BY LATE FRI NIGHT. MODELS AGREES THAT SUCH A SCENARIO TAKES PLACE...AND THAT A TIGHT PRES GRADIENT IS CREATED BETWEEN THE LOW AND HIGH PRES N OF AREA TO PRODUCE STRONG NE-E WINDS IN THE RANGE OF 25-30 KT N OF THE LOW. BASED ON LATEST MODEL WIND GUIDANCE IT DOES NOT APPEAR THAT GALE CONDITIONS WILL OCCUR S OF 31N IN ASSOCIATION WITH LOW...WILL MENTION FOR NOW GUSTY WITH THE FORECAST WINDS...AND WILL WATCH FOR GALE FORCE WINDS IN UPDATED MODEL RUNS AND SEE HOW THE ENSEMBLE CONTINUE TO DERIVE THIS SITUATION IN ORDER TO DETERMINE IF THESE WINDS NEED TO BE BUMP UP TO GALE FORCE IN FUTURE NT3 PACKAGES. OFF COURSE A DEEPER LOW OVER THE NRN WATERS AND/OR STRONGER HIGH PRES TO THE N MAY EASILY LEAD TO GALE CONDITIONS FOR THIS PART OF THE AREA. THE LOW THEN MOVES ESE AND WEAKENS SAT AND SAT NIGHT OVER THE FAR E SECTION OF THE AREA AS WHILE THE STRONG RIDGE TO THE N ALSO SHIFTS E. WINDS OVER THE REMAINDER OF THE AREA WILL BECOMES SE-S 10-15 KT...EXCEPT SE 15-20 KT E OF THE LOW AND NW-N 15-20 KT W OF THE LOW FRI. WINDS BECOME LIGHT SE-S S OF LOW SAT E OF BAHAMAS...AND LIGHT NW-N S OF LOW SAT W OF BAHAMAS. BY SUN WINDS WILL BE E 20-25 KT N OF 26N E OF 77W AND E 15-20 KT N OF 26N W OF 77W. WINDS WILL BE LIGHT E-SE E OF BAHAMAS AND VARIABLE 5-10 KT W OF BAHAMAS. A COLD FRONT MOVES INTO THE NW PART LATE SUN INTO MON WITH WINDS VEERING TO THE SE 20-25 KT AHEAD OF IT AND BECOMING NW-N 15-20 KT BEHIND IT. WAVEWATCH MODEL FORECAST SEAS 8-12 FT WITH THE SE 20-25 KT WINDS SUN THROUGH EARLY MON...AND SEAS TO 8 FT BEHIND FRONT. FRONT REACHES FROM 31N70W TO NW BAHAMAS BY MON AFTERNOON...AND WEAKENS FROM 31N66W TO NEAR SE BAHAMAS LATE MON. WINDS BECOME LIGHT E-SE THROUGHOUT TUE...AND LIGHT N-NE FAR NE PART TUE. CARIBBEAN AND TROPICAL N ATLC... A BROKEN QUIKSCAT PASS FROM NEAR 1000 UTC THIS MORNING REVEALED NE WINDS OF 15-20 KT OVER MUCH OF THE CARIBBEAN CONFINED TO S OF 16N W OF 70W...AND OVER THE TROPICAL N ATLC S OF 16N. ELSEWHERE NE-E WINDS OF 10-15 KT ARE NOTED IN THE QUIKSCAT PASS AS WELL AS IN THE NOAA BUOY REPORTS. THESE CONDITIONS ARE EXPECTED TO CHANGE LITTLE THROUGH EARLY SUN...THEN INCREASE OVER THE REMAINDER OF THE E CARIBBEAN AND TROPICAL NH ATLC LATER SUN THROUGH TUE AS HIGH PRES N OF THE REGION MOVES S SOME ALLOWING FOR THE PRES GRADIENT TO TIGHTEN. FAVORABLE TRAJECTORY OF NE WINDS MAY FAVOR SOME FUNNELING IN THE ATLC PASSAGES...MORE LIKELY...SUN AND MON SO WILL KEEP WORDING IN THE FCST. WARNINGS... ATLANTIC... NONE. CARIBBEAN... NONE. GULF OF MEXICO... NONE. FORECASTER AGUIRRE