Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 012325 AFDGYX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAY ME 725 PM EDT WED OCT 1 2014 .SYNOPSIS... UPPER LEVEL LOW PRESSURE SLOWLY SHIFTS OFFSHORE THROUGH THURSDAY. AT THE SURFACE...HIGH PRESSURE BUILDS IN FROM THE NORTHEAST THROUGH THURSDAY AND REMAINS OVER THE AREA THROUGH FRIDAY. A COLD FRONT WILL APPROACH FROM THE WEST ON SATURDAY AND CROSSES THE REGION SATURDAY NIGHT. A WEAK RIDGE OF HIGH PRESSURE WILL BUILD IN BEHIND THE FRONT ON SUNDAY. A WEAK WARM FRONT WILL PASS TO THE NORTHWEST OF THE REGION ON MONDAY FOLLOWED BY A COLD FRONT ON TUESDAY. && .NEAR TERM /THROUGH THURSDAY/...
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UPDATE... LATEST RADAR ANIMATIONS CONTINUE TO SHOW MOST OF THE PRECIP CONFINED TO THE SOUTHERN NEW ENGLAND COASTLINE. A FEW SCATTERED SHOWERS AND PATCHY DRIZZLE IS MAKING IT ABOUT AS FAR NORTH AS PORTLAND...BUT FOR THE MOST PART...THE MESOSCALE MODELS THIS EVENING CONTINUE TO OVERDUE THE PRECIP IN SOUTHERN MAINE. HAVE ADJUSTED THE POPS...DEW POINT VALUES AND CURRENT TEMPS BASED ON LASTEST CONDITIONS. HAVE ALSO INTRODUCED PATCHY FOG...ALONG WITH THE DRIZZLE FOR FAR SOUTHERN AREAS PER CURRENT OBSERVATIONS. THE REST OF THE FORECAST PACKAGE WILL REMAIN UNCHANGED. PREV DISC... LOW PRESSURE CONTINUES TO SPIN NEAR CAPE COD THIS AFTERNOON... DIRECTING MOISTURE ONSHORE AND KEEPING SHOWERS AND DRIZZLE GOING OVER NH AND MUCH OF WESTERN MAINE. MOST OF THE RAIN SHIELD REMAINS OVER CAPE COD TO LONG ISLAND AND THE GULF OF MAINE...BUT STEADY RAIN IS FALLING OVER THE NH COAST TO CAPE ELIZABETH AND INLAND. THIS TREND WILL CONTINUE THROUGH THE EVENING AND INTO THE EARLY MORNING HOURS BEFORE THE INVERTED TROUGH FEATURE SHIFTS CLOCKWISE AND SOUTHWARD TOWARDS BOSTON. ONLY LIGHT PRECIPITATION AMOUNTS ARE EXPECTED. DRIZZLE AND FOG WILL PLAGUE PORTIONS OF THE COAST AND THE COASTAL PLAIN FOR SEVERAL MILES...AS WELL AS MOUNTAIN VALLEYS AND THE CT RIVER VALLEY OVERNIGHT. STRATUS WILL BE SLOW TO LIFT BUT WILL BEGIN TO BREAK DOWN LATE MORNING THURSDAY. THESE FEATURES WILL KEEP OVERNIGHT LOWS ON THE WARM SIDE.
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&& .SHORT TERM /THURSDAY NIGHT THROUGH 6 PM THURSDAY/... AT THE SAME TIME THE SURFACE TROUGH SHIFTS SOUTH...THE UPPER LEVEL LOW BEGINS TO SHIFT EAST AND HIGH PRESSURE BEGINS TO NUDGE INTO NEW ENGLAND FROM THE NORTH. AS A RESULT RAIN CHANCES QUICKLY TAPER OFF TO NIL AFTER THE EARLY MORNING HOURS THURSDAY. AS MENTIONED BEFORE...STRATUS WILL BEGIN TO LIFT AROUND NOON AND SKIES CLEAR FROM NORTH TO SOUTH. TEMPERATURES WARM INTO THE MID TO UPPER 60S AREAWIDE BY THURSDAY AFTERNOON. SOME COOLER AIR DOES FUNNEL IN FROM THE NORTH BY THURSDAY NIGHT INTO FRIDAY MORNING BUT WINDS WILL BE NON ZERO INTERRUPTING RADIATIONAL COOLING. IN ADDITION...OTHER FACTORS SUCH AS +11 DEGREES C AT 850MB AND CLOUDS INDICATED BY A JETSTREAK ALOFT WILL KEEP IT FROM GETTING TOO CHILLY. ALTHOUGH WE WILL SEE TEMPERATURES IN THE 40S WITH SOME UPPER 30S IN THE MOUNTAINS...NOT EXPECTING IT TO BE NEARLY AS COLD AS ONE MODEL SUITE INDICATED. && .LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/... SURFACE HIGH PRESSURE WILL BE CENTERED OVER THE CANADIAN MARITIMES WITH A RIDGE EXTENDING SOUTHWEST ALONG THE NORTHERN NEW ENGLAND COAST ON FRIDAY. A BRIEF UPPER RIDGE CROSSES THE AREA AS WELL... EXPOSING THE REGION TO SOME WARMER TEMPERATURES. IT APPEARS ONLY THE NORTHWESTERN PART OF THE AREA WILL REALLY BE ABLE TO FEEL THIS AS THE SOUTHERN AND COASTAL AREAS WILL BE UNDER THE INFLUENCE OF ONSHORE SURFACE FLOW... KEEPING TEMPERATURES COOLER. HIGHS WILL RANGE FROM THE UPPER 60S IN THE NORTHWEST TO NEAR 60 AT THE COAST. SOME FOG AND DRIZZLE MAY MOVE IN FROM THE OCEAN FRIDAY NIGHT... THOUGH MODELS OFTEN BRING THIS IN TOO OFTEN AND TOO EARLY. LARGE UPPER TROUGH WILL MOVE THROUGH THE GREAT LAKES ON SATURDAY WITH A SURFACE COLD FRONT SURGING EASTWARD ACROSS THE NORTHEAST. AN AREA OF RAIN IS EXPECTED TO FORM WITHIN THE RISING MOTION OF THE UPPER TROUGH AND ALONG AND AHEAD OF THE SURFACE FRONT... WITH THE RAIN ARRIVING IN WESTERN NEW HAMPSHIRE BY LATER IN THE DAY ON SATURDAY. THE RAIN AND SURFACE FRONT MOVE ACROSS NEW HAMPSHIRE AND MAINE SATURDAY NIGHT. EXPECT THE ENTIRE AREA TO SEE RAIN WITH THIS SYSTEM SO WENT WITH VERY HIGH POP. A LITTLE LOWER POP WAS USED IN WESTERN NEW HAMPSHIRE WHERE THERE IS STILL SOME TIMING UNCERTAINTY OVER WHETHER THE RAIN WILL FALL LATE SATURDAY OR EARLY SATURDAY NIGHT BUT OVERALL CONFIDENCE IN RAIN ACROSS THE REGION IS VERY HIGH. WITH COLDER AIR MOVING IN ALOFT WITH THE UPPER TROUGH AND WARM/MOIST AIR SURGING NORTHWARD IN THE LOW LEVELS AHEAD OF THE SURFACE FRONT... THERE WILL ALSO BE A CHANCE FOR A FEW THUNDERSTORMS EMBEDDED WITH THE RAIN. LAPSE RATES NEAR MOIST ADIABATIC COMBINED WITH STRONG LIFT COULD BE ENOUGH FOR A FEW LIGHTNING STRIKES. COOLER AND DRIER AIR MOVES IN BEHIND THE FRONT FOR SUNDAY... BUT MORE SUN AND A DOWNSLOPING WEST WIND COULD ACTUALLY WARM COASTAL AREAS UP TO THE LOW 60S... A FEW DEGREES WARMER THAN SATURDAY BEFORE THE FRONT. FROM SUNDAY THROUGH THE MIDDLE OF NEXT WEEK THE NORTHEAST WILL BE IN A SOUTHWEST FLOW AROUND THE LARGE UPPER TROUGH OVER CENTRAL CANADA. THIS WILL MEAN GRADUALLY WARMING TEMPERATURES WITH OCCASIONAL BOUTS OF RAIN SHOWERS AS MINOR WAVES PASS THROUGH THE SOUTHWESTERLY FLOW. && .AVIATION /23Z WEDNESDAY THROUGH MONDAY/... SHORT TERM...VARYING CEILINGS AND VISIBILITIES AT TIMES THROUGH NOON TOMORROW IN SHOWERS...DRIZZLE...AND FOG...FOR ALL STATIONS. LIFR TO IFR CONDITIONS ARE LIKELY IN THE 03 TO 13Z TIME FRAME. LONG TERM...VFR FRIDAY BUT COULD SEE MARINE CLOUDS AND FOG MOVE IN FRIDAY NIGHT AND SATURDAY WITH IFR OR LOWER CONDITIONS BECOMING WIDESPREAD ESPECIALLY EAST OF THE MOUNTAINS. RAIN AND POSSIBLY SOME EMBEDDED THUNDER MOVES THROUGH SATURDAY NIGHT WITH VFR CONDITIONS RETURNING FOR SUNDAY AND MONDAY. && .MARINE... SHORT TERM...EXTENDED THE SMALL CRAFT ADVISORY THROUGH THURSDAY EVENING. MAY BE ABLE TO CHANGE IT JUST TO A SMALL CRAFT FOR WAVES TOMORROW MORNING AS WINDS WILL LIKELY COME DOWN TOMORROW MORNING AS SURFACE TROUGH MOVES AWAY. LONG TERM...WINDS WILL GRADUALLY TURN FROM THE NORTHEAST TO EAST AND THEN SOUTHEAST THROUGH SATURDAY AS OFFSHORE LOW PRESSURE MOVES AWAY AND SURFACE HIGH PRESSURE OVER THE MARITIMES AND MAINE GRADUALLY SHIFTS EAST AS WELL. FLOW MAY STRENGTHEN INTO ADVISORY CRITERIA AGAIN ON SATURDAY NIGHT AHEAD OF A COLD FRONT. WAVE HEIGHTS MAY STAY NEAR OR ABOVE 5 FEET AND REQUIRE A SMALL CRAFT ADVISORY FOR ALL OR PART OF THE AREA ALL THE WAY THROUGH SUNDAY. && .GYX WATCHES/WARNINGS/ADVISORIES...
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ME...NONE. NH...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THURSDAY FOR ANZ150-152- 154.
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