Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 171033 AAA AFDGYX AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE GRAY ME 633 AM EDT SUN AUG 17 2014 .SYNOPSIS... WEAK LOW PRESSURE AND AN ASSOCIATED FRONT WILL CROSS THE AREA THIS MORNING. HIGH PRESSURE BUILDS IN TONIGHT AND MONDAY. A WEAK RIDGE OF HIGH PRESSURE WILL REMAIN ACROSS THE REGION TUESDAY AND WEDNESDAY BUT WILL SLOWLY SHIFT EAST THURSDAY AND FRIDAY AS LOW PRESSURE APPROACHES FROM THE WEST. && .NEAR TERM /THROUGH TONIGHT/...
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UPDATE...TROF CONTINUES TO PROGRESS ACROSS THE AREA ATTM. WIND SHIFT IS NOTED ACROSS NY STATE...FROM A KMSS...KART...KSYR...TO KBGM LINE. UNTIL WIND SHIFT REACHES CWFA SHRA WILL REMAIN IN THE FORECAST. HAVE TRIED TO TIME POP BASED ON THIS EXPECTED MOTION AND CURRENT RADAR TRENDS. KMWN HAS SHIFTED AROUND TO WLY WINDS...SO CLOUDS DOWNWIND OF THE MTNS SHOULD BEGIN TO ERODE...THOUGH LLVL CLOUDS MAY LINGER UNTIL WIND SHIFT AS WELL. PREVIOUS DISCUSSION...S/WV TROF AND ATTENDANT COLD FNT ARE CROSSING THE AREA THIS MORNING. WIDESPREAD SHOWERS ARE AHEAD OF THE FEATURES...HOWEVER MUCH OF THE PCPN IS HAVING TROUBLE REACHING THE GROUND. TROF AXIS WILL CROSS THE AREA SOON...WITH WLY FLOW TAKING OVER IN ITS WAKE. THIS WILL BRING AN END TO SIGNIFICANT SHOWER ACTIVITY FOR MUCH OF THE AREA. DOWNSLOPE FLOW WILL ALSO START TO ERODE CLOUD COVER FOR THE COASTAL PLAIN AND SRN NH. DOWNSLOPING WILL ALSO KEEP THE SERN ZONES WARMER TODAY...DESPITE THE CAA ONGOING. WLY FLOW WILL BE BREEZY AT TIME DURING THE DAY. TO THE W OF THE MTNS...UPSLOPE FLOW WILL CONTINUE CLOUDS AND SOME SHRA INTO TONIGHT.
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&& .SHORT TERM /MONDAY THROUGH MONDAY NIGHT/... WLY FLOW WILL CONTINUE OVERNIGHT...WITH CLOUDS REMAINING WINDWARD OF THE MTNS. WE/LL BE LOSING MOISTURE...SO ANY SHRA SHOULD BEGIN TO DISSIPATE. GRADIENT SHOULD REMAIN ENOUGH THAT WIDESPREAD VALLEY FOG ISN/T AN ISSUE. BY MON HIGH PRES BUILDS IN...WITH SKIES CLEARING FOR THE REMAINDER OF THE CWFA. DESPITE THE MOSTLY SUNNY SKIES...THE LOSS OF THE DOWNSLOPE FLOW SHOULD RESULT IN A SLIGHTLY COOLER AFTERNOON MON THAN TODAY. EXCEPTION MAY BE IN THE NORTH COUNTRY...WHERE SIGNIFICANT CLOUDINESS TODAY WILL LEAD TO COOLER TEMPS TODAY THAN MON. && .LONG TERM /TUESDAY THROUGH SATURDAY/... LOW PRESSURE REMAINS OVER THE MARITIMES AS A WEAK AREA OF HIGH PRESSURE SETTLES OVER NRN NEW ENGLAND MONDAY NGT THRU WEDNESDAY GIVING US FAIR WX WITH SEASONABLY COOL TEMPS AND COMFORTABLE HUMIDITY LEVELS. AN UPPER LVL TROF SLIDES EASTWARD STAYING JUST TO OUR S WHILE AN UPPER LVL RIDGE BUILDS SE FROM CANADA. AT THE SFC LOW PRESSURE UNDER THE UPPER LVL TROF TRACKS TO OUR S...MOVING OFFSHORE WEDNESDAY NGT AND THURSDAY AS HIGH PRESSURE ASSOCIATED WITH THE UPPER LVL RIDGE TRIES TO MAINTAIN ITSELF OVER NRN NEW ENGLAND. THIS WILL LIKELY KEEP US DRY...BUT IF THE LOW TRACKS FURTHER N THEN IT COULD SPREAD SOME PRCP NWD INTO THE FCST AREA. THE UPPER LVL TROF MOVES OUT TO SEA THEN CUTS OFF INTO AN UPPER LVL CUTOFF LOW WHILE THE SFC LOW MOVES OUT TO SEA THURSDAY NGT AND FRIDAY ALLOWING THE UPPER LVL RIDGE AND SFC HIGH TO BUILD INTO THE NE...GIVING US MORE FAIR WX. THE UPPER LVL RIDGE AND SFC HIGH HOLD ON THRU SATURDAY WHILE THE UPPER LVL CUTOFF STAYS JUST TO OUR E. FAIR WX SHOULD CONT... BUT IF THE UPPER LVL CUTOFF DRIFTS FURTHER BACK TO THE W THEN IT COULD SPREAD SOME PRCP WESTWARD INTO THE FCST AREA. USED A BLEND OF VARIOUS MODELS...HPC GUIDANCE...PREVIOUS FCST FOR PERSISTENCE AND CLIMATOLOGY FOR THE LONG TERM FCST. && .AVIATION /12Z SUNDAY THROUGH THURSDAY/... SHORT TERM...COLD FNT CROSSING THE AREA WILL CONTINUE TO SPREAD SCT SHRA THRU MID MORNING. SHRA ARE VERY LIGHT...WITH GENERALLY P6SM VSBYS. CIGS MAY BRIEFLY DROP TO MVFR...BUT WLY FLOW DEVELOPING WILL HELP TO CLEAR CLOUD COVER OUT QUICKLY THIS MORNING. UPSLOPE FLOW NW OF THE MTNS WILL KEEP CLOUDS GOING THRU TONIGHT...BUT SHOULD REMAIN VFR. LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...MAINLY VFR WX THRU THE LONG TERM FCST PERIOD. && .MARINE... SHORT TERM...WINDS AND SEAS WILL REMAIN BELOW SCA THRESHOLDS. LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...HIGH PRESSURE KEEPS WINDS AND SEAS BELOW SCA LEVELS THRU THE LONG TERM FCST PERIOD. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...NONE. NH...NONE. MARINE...NONE. && $$ NEAR TERM...LEGRO

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