Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 272351 AFDGYX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAY ME 651 PM EST FRI FEB 27 2015 .SYNOPSIS... HIGH PRESSURE WILL BUILD IN FROM THE WEST TONIGHT THROUGH SATURDAY AND WILL SHIFT OFFSHORE SOUTH OF NEW ENGLAND ON SUNDAY. A WEAK AREA OF LOW PRESSURE WILL MOVE IN FROM THE WEST SUNDAY NIGHT AND WILL QUICKLY SHIFT EAST OF THE REGION ON MONDAY. HIGH PRESSURE WILL BUILD IN FROM THE WEST MONDAY NIGHT AND WILL CREST OVER THE REGION ON TUESDAY BEFORE MOVING OFFSHORE. LOW PRESSURE WILL MOVE NORTHEAST OUT OF THE SOUTHERN GREAT LAKES TUESDAY NIGHT AND WILL PASS NORTHWEST OF THE REGION ON WEDNESDAY AND WEDNESDAY NIGHT. && .NEAR TERM /TONIGHT/... 7PM UPDATE... HAVE MADE A FEW MINOR ADJUSTMENTS TO OVERNIGHT LOW TEMPERATURES. COMPARED TO THIS MORNING TEMPERATURES JUST ABOUT EVERYWHERE SHOULD BE A FEW DEGREES COLDER. IN GOOD RADIATIONAL COOLING CONDITIONS THERE IS ALWAYS HIGH BUST POTENTIAL IN THE FORECAST AS LOCAL COOL SPOTS CAN DROP VERY QUICKLY. ONLY ADJUSTMENTS WITH THIS UPDATE WERE TO BRING TYPICAL COOL SPOT WISCASSET DOWN A FEW DEGREES. ALSO DROPPED SOUTHWEST NEW HAMPSHIRE BY A FEW DEGREES TO BRING THEM COLDER THAN THEY WERE THIS MORNING AND MORE IN LINE WITH FORECASTS FROM NEIGHBORING OFFICES. SHOULD SEE TEMPERATURES FALL BELOW ZERO THERE AS WELL AS MOST OF THE FORECAST AREA TONIGHT. ORIGINAL DISCUSSION... SPRAWLING HIGH PRESSURE IS CENTERED OVER THE MID MISSISSIPPI VALLEY THIS AFTERNOON...BRANCHING TOWARDS NEW ENGLAND TO THE EAST. WEAK COLD FRONT IS EXITING THE COAST AT THIS HOUR AS WELL. THIS BOUNDARY IS MORE PERCEPTIBLE ALOFT...WITH SLIGHTLY COOLER AIR MOVING IN. AT THE SURFACE IT IS MOSTLY A NW WIND...WHICH COMBINED WITH SUNNY SKIES IS ALLOWING SOME DOWNSLOPE WARMING WELL INTO THE 20S NEAR THE COAST. SURFACE RIDGE AXIS SETTLES OVERHEAD TONIGHT HOWEVER...AND SKIES REMAIN CLEAR. CONDITIONS LOOK FAVORABLE FOR DECOUPLING OF THE BOUNDARY LAYER. SUCH A SMALL SCALE PROCESS IS ALWAYS QUITE DIFFICULT TO FORECAST...BUT GENERALLY LEANED TOWARDS THE COLDER MET GUIDANCE AND LOWERED THE USUAL COLD SPOTS A COUPLE MORE DEGREES. && .SHORT TERM /SATURDAY AND SATURDAY NIGHT/... HIGH PRESSURE REMAINS IN CONTROL SATURDAY...WITH SKIES REMAINING MOSTLY SUNNY. GUIDANCE HAS STRUGGLED THE LAST FEW DAYS WITH SUNSHINE...KEEPING MAX TEMPERATURES ON THE COLD SIDE. BLENDED MAV/MET WITH CMC-REGIONAL AND NAM12 2 M TEMPERATURES FOR MAX TEMPERATURES...THEN RAISED A COUPLE DEGREES TO OVERCOME THAT COOL BIAS. TEMPERATURES WARM ALOFT SATURDAY NIGHT...SO NOT EXPECTING MIN TEMPERATURES QUITE AS COLD AS TONIGHT. INITIALLY SURFACE RIDGE AXIS REMAINS ALIGNED QUITE FAVORABLY FOR THE AREA...SO A QUICK DROP IN TEMPERATURES IN LIKELY. AS RIDGE AXIS SLOWLY SINKS SOUTH...THE COMBINATION OF SLIGHT MIXING AND WARMING ALOFT SHOULD LEVEL TEMPERATURES OFF. && .LONG TERM /SUNDAY THROUGH FRIDAY/... A BROAD AREA OF WARM AIR ADVECTION WILL ENTER THE REGION SUNDAY NIGHT AS AN UPPER LEVEL TROUGH APPROACHES FROM THE NORTHWEST. THIS WILL ALLOW LIGHT SNOW TO DEVELOP ACROSS THE REGION SUNDAY EVENING. THIS SYSTEM IS PROGRESSIVE...WHICH WILL ALLOW ACCUMULATIONS TO BE IN THE 2 TO 3 INCH RANGE. DRIER AIR WILL BE USHERED INTO THE REGION ON STRONG NORTHWEST WINDS ON MONDAY...HOWEVER THERE MAY BE A STRAY FLURRY LEFTOVER. HIGH PRESSURE WILL BUILD EAST...CRESTING OVER NEW ENGLAND ON TUESDAY. THE STORM TRACK HAS CHANGED...ALLOWING THE NEXT SYSTEM TO POTENTIALLY PASS TO OUR WEST TUESDAY NIGHT INTO WEDNESDAY. SUFFICIENTLY ENOUGH COLD AIR IN PLACE TUESDAY NIGHT TO ALLOW FOR MOSTLY SNOW ACROSS MAINE AND NEW HAMPSHIRE. HOWEVER...WARM AIR EVENTUALLY MAKES IT IN ALOFT TO CHANGE MUCH OF THE PRECIPITATION OVER TO A PERIOD OF RAIN OR RAIN AND SNOW MIX BEFORE IT ENDS. A FEW LEFTOVER RAIN SHOWERS ARE POSSIBLE WEDNESDAY BEHIND A COLD FRONT THAT WILL EVENTUALLY CHANGE OVER TO SNOW SHOWERS BY THURSDAY. ANOTHER BRIEF SHOT OF VERY COLD AIR IS LIKELY TOWARDS THE END OF THE WEEK. && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/... SHORT TERM...VFR CONDITIONS WILL PREVAIL THRU SUNDAY MORNING. LONG TERM...AREAS OF IFR CONDITIONS IN SNOW SUNDAY NIGHT. SNOW TO MIX WILL LEAD TO IFR CONDITIONS TUESDAY NIGHT INTO EARLY WEDNESDAY. && .MARINE... SHORT TERM...WINDS AND SEAS WILL REMAIN BELOW SCA THRESHOLDS THRU SUNDAY MORNING. BITTERLY COLD TEMPERATURES TONIGHT WILL LEAD TO MODERATE FREEZING SPRAY NORTH OF CAPE ELIZABETH...AND ADVISORY IS IN EFFECT THRU 12Z SATURDAY. LONG TERM...WINDS SHOULD INCREASE TO SCAS MONDAY NIGHT BEHIND DEPARTING AND STRENGTHENING SURFACE LOW PRESSURE SYSTEM OVER THE MARITIMES. GUSTY WINDS NEXT THURSDAY NIGHT AND FRIDAY AS WELL OUT OF THE WEST. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...NONE. NH...NONE. MARINE...FREEZING SPRAY ADVISORY FROM MIDNIGHT TONIGHT TO 7 AM EST SATURDAY FOR ANZ150>152. && $$ NEAR TERM UPDATE...KIMBLE SHORT TERM...LEGRO LONG TERM...CANNON AVIATION...CANNON/LEGRO MARINE...CANNON/LEGRO

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