000 FXUS61 KCAR 262131 AFDCAR AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CARIBOU ME 431 PM EST WED DEC 26 2007 .SYNOPSIS... HIGH PRESSURE WILL BUILD NORTH OF THE REGION TONIGHT. ONE LOW WILL TRACK EAST OF THE REGION THURSDAY...WHILE A SECOND LOW APPROACHES FROM THE WEST. HIGH PRESSURE WILL BUILD ACROSS THE REGION FRIDAY. ANOTHER LOW WILL CROSS THE REGION SATURDAY...WITH HIGH PRESSURE BUILDING ACROSS THE REGION SUNDAY. && .NEAR TERM /THROUGH THURSDAY/... HIGH PRESSURE WILL BUILD NORTH OF THE REGION TONIGHT. HOWEVER...CLOUDS WILL LINGER ACROSS NORTHERN AREAS KEEPING SKIES PARTLY/MOSTLY CLOUDY. ACROSS DOWNEAST AREAS...CLOUD COVER WILL INCREASE TONIGHT IN ADVANCE OF THE OCEAN LOW LIFTING OFFSHORE OF THE SOUTH NEW ENGLAND COAST. THERE IS A SLIGHT CHANCE THAT LIGHT SNOW COULD REACH THE DOWNEAST COAST LATE TONIGHT. LOW TEMPERATURES TONIGHT WILL BE DEPENDENT ON THE EXTENT OF CLOUD COVER. GENERALLY EXPECT LOW TEMPERATURES TO RANGE FROM AROUND 20 TO THE LOWER 20S NORTH...TO THE LOWER TO MID 20S DOWNEAST. THE OCEAN LOW WILL TRACK EAST OF THE GULF OF MAINE THURSDAY...WHILE A WEAKER LOW APPROACHES FROM THE GREAT LAKES. TROFFING BETWEEN THESE LOWS WILL BEGIN TO LIFT ACROSS THE REGION LATER THURSDAY. ALOFT...AN UPPER TROF WILL ALSO BEGIN CROSSING THE REGION LATER THURSDAY. MODELS INDICATE AN AREA OF 850-500 MB Q-VECTOR FORCING AND SURFACE CONVERGENCE ALONG THE TROF AXIS LIFTING ACROSS THE REGION THURSDAY. THIS SHOULD SUPPORT AN AREA OF MOSTLY SNOW EXPANDING FROM SOUTHWEST TO NORTHEAST ACROSS THE REGION DURING THURSDAY. SNOW ACCUMULATIONS THURSDAY SHOULD GENERALLY BE AN INCH OR LESS ACROSS THE REGION. BASED ON CRITICAL THICKNESSES...A RAIN/SNOW MIX IS POSSIBLE ALONG THE DOWNEAST COAST. HIGH TEMPERATURES THURSDAY WILL RANGE FROM THE MID 20S NORTH...TO AROUND 30 TO THE LOWER 30S DOWNEAST. && .SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/... LOW PRESSURE PASSES TO THE SOUTHEAST OF THE STATE AS ANOTHER WEAK LOW APPROACHES FROM THE WEST AT THE BEGINNING OF THIS PERIOD. MODELS SIGNIFICANTLY DIFFER ON THE HANDLING OF THIS SYSTEM. HAVE WILL BASE THIS PORTION OF THE FORECAST ON COMBINATION OF NAM12 AND THE GFS. GRIDS GENERATED WITH GMOS THEN MANUALLY MODIFIED. THE SKY GIRDS AND THE QPF GRIDS CREATED WITH 50/50 BLEND OF THE NAM12 AND THE GFS. FOR FRIDAY AFTERNOON INTO EVENING LOW PRESSURE MOVES TO THE NORTHEAST WITH WEAK RIDGE CROSSING THE FORECAST AREA BEFORE NEXT SYSTEM APPROACHES FROM THE SOUTHWEST. WILL USE 3 HOUR SREF FOR POPS DURING THIS TIME PERIOD WHICH BEST REELECTS THE RIDGE PASSAGE. THE REMAINING GRIDS CREATED WITH GMOS. FROM 06Z TO 12Z SUNDAY WILL CREATE GRIDS WITH GMOS. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... GFS AND ECMWF ARE IN PRETTY GOOD AGREEMENT ON THE BEGINNING OF THE NEXT PERIOD. A LOW PRESSURE SYSTEM WILL BE OVER THE CANADIAN MARITIMES WITH HIGH PRESSURE BUILDING ACROSS THE REGION. BY 12Z MONDAY THE MODELS START TO DIVERGE. GFS HAS A 998MB LOW OVER THE EASTERN GREAT LAKES WITH SECONDARY DEVELOPMENT OVER THE DELMARVA PENINSULA...THE SECONDARY LOW WILL BE CENTERED OVER SOUTHERN NEW BRUNSWICK BY 06Z ON TUESDAY. THE ECMWF PLACES THE LOW OVER ILLINOIS WITH A LOW WITH SECONDARY DEVELOPMENT DELAYED UNTIL 12Z TUESDAY...AND WILL KEEP THE SECONDARY LOW OUT TO SEA. THE CANADIAN GEM SIMILAR TO THE GFS FOR POSITIONS AND MOVEMENT OF THE SYSTEMS THROUGH THE PERIOD. AND AT THE END OF THE PERIOD THEY ARE IN AGREEMENT AGAIN AS HIGH PRESSURE RIDGES ACROSS THE REGION. GMOS HAS TAKEN A BLENDED APPROACH KEEPING THE POPS AND QPF DOWN. AT 12Z TUESDAY THE TWO MODELS ARE IN FAIRLY GOOD AGREEMENT AGAIN ON POSITION...BUT DIFFER GREATLY ON CENTRAL PRESSURE. && .AVIATION /20Z WEDNESDAY THROUGH MONDAY/... OCCASIONAL MVFR CEILINGS WILL PERSIST ACROSS THE NORTH/MOUNTAINS TONIGHT...WITH MVFR CEILINGS DEVELOPING DOWNEAST LATER TONIGHT. MVFR/IFR CEILINGS/VISIBILITIES ARE THEN EXPECTED ACROSS THE REGION THURSDAY/THURSDAY NIGHT. HIGH PRESSURE WILL BUILD ACROSS THE REGION FRIDAY...WITH MVFR CEILINGS POSSIBLY LINGERING ACROSS THE NORTH/MOUNTAINS. LOW PRESSURE IS EXPECTED TO CROSS THE REGION SATURDAY BRINGING SNOW TO NORTHERN AREAS...WITH MIXED PRECIPITATION DOWNEAST. HIGH PRESSURE IS EXPECTED TO CROSS THE REGION SUNDAY. ANOTHER LOW COULD AFFECT THE REGION MONDAY...BRINGING ANOTHER CHANCE OF SNOW. && .MARINE... NEAR TERM: SMALL CRAFT ADVISORY LEVEL WINDS/SEAS WILL DEVELOP LATER TONIGHT THEN CONTINUE THURSDAY. THUS...A SMALL CRAFT ADVISORY IS IN EFFECT FOR LATE TONIGHT THROUGH LATE THURSDAY NIGHT. VISIBILITIES WILL BEGIN TO LOWER IN DEVELOPING RAIN/SNOW LATE TONIGHT...WITH REDUCED VISIBILITIES IN RAIN/SNOW THURSDAY. SHORT TERM: FOR WINDS HAVE USED A 50/50 NAM12 GFS BLEND FROM 28/00Z THRU DAY 4 THEN GMOS TO THE END OF PERIOD. HAVE INCREASED WIND SPEEDS IN NORTHEAST FLOW THURSDAY EVENING TO ACCOUNT FOR BIAS IN NORTHEAST FLOW....OTHERWISE NO OTHER CHANGES TO MODEL BLEND WINDS OR GMOS WINDS. FOR WAVES: BASED ON SPECTRAL POINT CAR01...THERE SEEMS TO BE A SOUTHEAST SWELL GROUP AT 8-10 SECONDS AT 28TH 00Z THAT TRANSITIONS TO SOUTHWEST BY 29TH/00Z. OTHERWISE WIND WAVE PRIMARY WAVE FIELD. HAVE INITIALIZED WITH WNA AND HAVE NOT MADE ANY MODIFICATIONS. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...NONE. MARINE...SMALL CRAFT ADVISORY FROM 5 AM THURSDAY TO 1 AM EST FRIDAY FOR ANZ050>052. && $$ NEAR TERM...NORCROSS SHORT TERM...MIGNONE LONG TERM...NORTON AVIATION...NORCROSS MARINE...NORCROSS/MIGNONE