FXUS61 KBOX 282157 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 557 PM EDT THU AUG 28 2008 .SYNOPSIS... HIGH PRESSURE DOMINATES OUR WEATHER THROUGH THE END OF THIS WEEK. A COLD FRONT WILL CROSS SOUTHERN NEW ENGLAND SATURDAY NIGHT. THIS SHOULD BE FOLLOWED BY HIGH PRESSURE FROM CANADA PROVIDING DRY AND WARMING WEATHER THROUGH MIDWEEK. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... THE FORECAST AREA REMAINS UNDERNEATH A WEAK UPPER LEVEL RIDGE AND SURFACE HIGH PRESSURE. AN UPPER LEVEL LOW NEAR 40N AND 60W IS EXPECTED TO DRIFT NORTH TONIGHT. THE REMNANTS OF FAY WILL REMAIN SOUTHWEST OF THE REGION. CHANGES: YESTERDAYS GFS SIGNALS APPEAR TO HAVE BEEN SPOT ON! BKN SC NOW FLIRTING WITH CAPE COD. REVIEWING MORE DATA BUT LIKELY ADDING 35 PCT MORE CLOUD TO OUTER CAPE COD AND ACK TONIGHT...WILL BE DONE BY 615 PM. OTRW VARIABLE CIRRUS AND AC INTERIOR. SO...OVERALL A PARTLY CLOUDY FORECAST TONIGHT...BECOMING MOSTLY CLOUDY FOR A TIME ESPECIALLY ACROSS THE OUTER CAPE AND ACK. FOG PATCHES WILL BE POSSIBLE ACROSS THE INTERIOR VALLEYS. USED A BLEND OF MAV/MET MOS GUIDANCE TO DERIVE OVERNIGHT LOWS. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/... FRIDAY...925MB EAST TO NORTHEAST FLOW WILL WEAKEN AND INCREASING SUNSHINE WILL ALLOWING FOR ANY MORNING LOW CLOUDS TO DISSIPATE. OTHERWISE EXPECT A PARTLY SUNNY AND MILD DAY WITH REMAINING DIURNAL CUMULUS CLOUDS. A WEAK UPPER LEVEL RIDGE REMAINS. THE 12Z GFS TRIES TO BRING MEASURABLE PRECIPITATION DURING THE AFTERNOON...FROM THE REMNANTS OF FAY...BUT IT ALSO APPEARS TO BE SUFFERING FROM CONVECTIVE FEEDBACK ISSUES INCLUDING A SPURIOUS SHORT WAVE. CONSIDERABLE HIGH CLOUDS WILL OCCUR DUE TO CONVECTION TO THE SOUTHWEST BUT DRY CONDITIONS ARE EXPECTED AT THIS TIME. THE SREFS AND THE MAJORITY OF GFS ENSEMBLES SIGNAL DRY CONDITIONS AS WELL. FRIDAY NIGHT...THE WEAK UPPER LEVEL RIDGE BEGINS TO DISSIPATE ALLOWING THE WESTERLIES TO ADVANCE AN APPROACHING COLD FRONT FROM THE GREAT LAKES. THE BEST MOISTURE CONVERGENCE AND MECHANISMS FOR LIFT REMAIN WEST OF THE FORECAST AREA ACROSS CENTRAL AND WESTERN NEW YORK STATE IN THE VICINITY OF THE COLD FRONT. CURRENTLY HAVE MAINTAINED A SLIGHT CHANCE POP OVER EXTREME WESTERN NEW ENGLAND APPROACHING DAYBREAK SATURDAY. && .LONG TERM /SATURDAY THROUGH THURSDAY/... THE 12Z GFS AND 00Z ECMWF LOOK SIMILAR IN HANDLING THE PATTERN OVER THE USA THIS PERIOD. MAIN FEATURES ARE A WEAK COLD FRONT MOVING THROUGH NEW ENGLAND SATURDAY AND MOVING OFFSHORE EARLY SATURDAY NIGHT...AND BUILDING UPPER HIGH PRESSURE OVER THE EASTERN USA THEREAFTER. THE COLD FROPA ON SATURDAY LOOKS LIKE A MARGINAL EVENT. JET LEVEL SUPPORT TRAILS THE FRONT LATE SATURDAY NIGHT. MID LEVEL WINDS ARE FORECAST AROUND 30 KNOTS AND LOW LEVEL WINDS AT 15 KNOTS. THE BEST DYNAMICAL SUPPORT BASED ON THE 12Z RUNS WOULD BE IN NORTHERN AND WESTERN SECTIONS...BUT 4 MORE MODEL RUNS BETWEEN NOW AND THEN THE TIMING COULD SHIFT ENOUGH TO MOVE THIS FAVORED AREA. PRECIPITABLE WATER VALUES ARE EXPECTED TO CLIMB TO 1.7 INCHES WHICH MIGHT SUPPORT A FEW HEAVY SHOWERS. FOR NOW WE WILL MAINTAIN LOW END CHANCE POPS FOR SATURDAY AFTERNOON AND EARLY NIGHT. CLOSED UPPER LOW OVER THE MARITIMES WILL KEEP A COOL NORTHWEST FLOW OVER NEW ENGLAND SUNDAY WITH -12C ALOFT OVER MAINE AND NH...AND PROBABLY INTO EASTERN MASS AS WELL. THIS WOULD SUPPORT SOME DIURNAL CUMULUS DEVELOPMENT MIDDAY...THEN DIMINISHING AS THE LOW MOVES EAST. OTHERWISE THE UPPER PATTERN DIGS A TROF OVER THE WESTERN USA AND BUILDS A RIDGE OVER THE EAST. THIS MEANS GENERALLY DRY WEATHER FOR US SUNDAY THROUGH AT LEAST WEDNESDAY. 850 MB TEMPS START AROUND 11C SUNDAY AND INCREASE TO 18C WEDNESDAY...SUGGESTING HIGHS AROUND 80F SUNDAY WARMING THROUGH THE 80S THROUGH MIDWEEK. IF 850 TEMPS ACTUALLY LINGER NEAR 18C WEDNESDAY...THEN HIGHS NEAR 90F WOULD BE POSSIBLE. FOR NOW WE WILL GO ABOVE GUIDANCE BUT KEEP IT IN THE 80S. ON THURSDAY A COLD FRONT APPROACHES THROUGH THE EASTERN GREAT LAKES. LOW PRESSURE LINGERS OFF THE MARITIMES. THE GFS KEEPS US BETWEEN SYSTEMS...WARM AND DRY...WHILE THE 00Z ECMWF DRIFTS THE OCEAN STORM WEST AND BRINGS A CHANCE OF SHOWERS TO EASTERN SECTIONS. INCLINATION IS TO KEEP THE WEATHER DRY THURSDAY. COULD BE A CHANCE OF SHOWERS THURSDAY NIGHT ESPECIALLY IN NORTHERN SECTIONS...WITH THE APPROACHING COLD FRONT. && .AVIATION /22Z THURSDAY THROUGH TUESDAY/... TONIGHT...GENERALLY VFR THROUGH 06Z...EXCEPTING ACK WHERE INTERMITTENT CIGS NR 1500 FT THRU THE NIGHT. MVFR CEILINGS 2-3 THOUSAND FT DVLPG HYA BY 06Z AND MHT-BOS FOR A TIME 10Z-15Z FRI. LCL MVFR VSBYS IN GROUND FOG PATCHES ACROSS SHELTERED LOCATIONS NEAR THE INTERIOR RIVER VALLEYS AND BOGS FOR A TIME LATE TONIGHT. FRIDAY...GENERALLY VFR. MVFR CEILINGS 020-030 HND FT MAINLY KBOS HYA ACK UNTIL 15Z. LCL SEABREEZES DEVELOPING NEAR SHORE BY 15Z. FRIDAY NIGHT...GENERALLY VFR. LCL MVFR VSBYS IN GROUND FOG PATCHES ACROSS SHELTERED LOCATIONS. ISOLD SHRA AFT 09Z WESTERN TERMINALS. OUTLOOK...SATURDAY THROUGH TUESDAY... GENERALLY VFR THROUGH THE PERIOD. PATCHY MVFR/IFR IN SHOWERS/TSTMS SATURDAY AFTERNOON AND NIGHT WITH COLD FRONT PASSAGE. NORTHWEST SURFACE FLOW SUNDAY THROUGH TUESDAY. && .MARINE... TONIGHT THROUGH FRIDAY NIGHT...SOME ENE SWELL AROUND 2 FT EXPECTED FROM THE OFFSHORE LOW TONIGHT THROUGH FRIDAY...WITH SIGNIFICANT WAVE HEIGHTS OF 2 TO 4 FT. THE E SWELL COULD INCREASE TO 2 TO 4 FT FRIDAY NIGHT INTO EARLY SATURDAY. WINDS AND SEAS EXPECTED TO REMAIN BELOW SMALL CRAFT ADVISORY CRITERIA AT THIS TIME. OUTLOOK...SATURDAY THROUGH TUESDAY... LIGHT WINDS AND SEAS THROUGH MOST OF THE PERIOD. A COLD FRONT MOVING ACROSS THE WATERS SATURDAY NIGHT MAY BRING SCATTERED SHOWERS AND THUNDERSTORMS. LOW PRESSURE LINGERING SOUTH OF NOVA SCOTIA MAY SEND 4 TO 5 FOOT SWELLS TO THE WATERS EAST OF CAPE COD AND NANTUCKET MONDAY. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. NH...NONE. RI...NONE. MARINE...NONE. && $$ SYNOPSIS...WTB NEAR TERM...DRAG/STRAUSS 557 SHORT TERM...STRAUSS LONG TERM...WTB AVIATION...WTB/STRAUSS 557 MARINE...WTB/STRAUSS