Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 261521 AFDGYX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAY ME 1121 AM EDT SUN JUL 26 2015 .SYNOPSIS... A WARM FRONT WILL SLOWLY CROSS THE REGION TODAY BRINGING ANOTHER ROUND OF SHOWERS. A WEAK COLD FRONT WILL PASS NORTH OF THE REGION ON MONDAY AND COULD PRODUCE A FEW SCATTERED SHOWERS OR STORMS IN THE MOUNTAINS. THIS FRONT WILL SLOWLY MOVE THROUGH NORTHERN MAINE ON TUESDAY AND THEN THROUGH CENTRAL AND SOUTHERN MAINE ON WEDNESDAY. HOT AND HUMID CONDITIONS BUILD OVER THE AREA TUESDAY THROUGH THURSDAY... EXCEPT FOR SOME MODERATE COOLING BEHIND THE COLD FRONT OVER MUCH OF MAINE. SHOWERS AND STORMS ARRIVE ON THURSDAY AHEAD OF ANOTHER COLD FRONT ARRIVING FROM THE WEST. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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11 AM UPDATE... SHOWERS AHEAD OF A WARM FRONT HAVE PETTY MUCH MOVED EAST OF THE FORECAST AREA WITH JUST A FEW STRAY CELLS LEFT MOVING THROUGH THE AREA. HAVE ADJUSTED CURRENT POPS DOWNWARD BASED ON LATEST RADAR TRENDS. TEMPERATURES HAVE BEEN SLOW TO RESPOND THIS MORNING AND HAVE BEEN ADJUSTED BACK A BIT THROUGH EARLY AFTERNOON. BREAKS IN THE OVERCAST BEGINNING TO SHOW UP IN WESTERN NEW ENGLAND AND THESE BREAKS WILL BE SHOWING UP IN THE CONNECTICUT VALLEY NEXT FEW HOURS. STILL EXPECTING SOME CONVECTION TO FIRE UP IN THE CONNECTICUT VALLEY AND SOUTHERN NEW HAMPSHIRE LATER THIS AFTERNOON AS SUNNY BREAKS BECOME MORE WIDESPREAD. NO OTHER CHANGES PLANNED ATTM. ORIGINAL DISCUSSION... MAIN CONCERN FOR THE NEXT COUPLE OF DAYS WILL BE THE CLOSED LOW THAT FORMS AND EVENTUALLY DECIDES TO STALL OVER NORTHERN MAINE. CURRENTLY AT THE SURFACE HIGH PRESSURE WAS SHIFTING TOWARDS NOVA SCOTIA. AN OCCLUDED TRIPLE POINT LOCATED JUST TO THE NORTH WAS MOVING EAST AS WELL. THE WARM FRONT ON OUR DOOR STEP HAS ALREADY TRIGGERED WARM AIR ADVECTION SHOWERS THIS MORNING. EXPECT PRECIPITATION TO BECOME HEAVIER AND MORE WIDESPREAD THIS MORNING AS THE COLD FRONT FOLLOWS SUIT. DAYTIME HEATING WILL HELP BOOST SURFACE BASED CAPE...HOWEVER FEATURES SUCH AS THE LOW LEVEL JET AND FRONTOGENESIS ARE WEAK. THIS LOOKS LIKE A WIDESPREAD RAIN EVENT WITH A FEW LIGHTNING STRIKES AND POSSIBLY SOME MINOR LOCALIZED FLOODING AS WARM RAIN CHARACTERISTICS WERE NOTED IN THIS AIRMASS. TODAY WILL BE HOTTER AND WITH DEWPOINTS COMING UP YOU WILL BE ABLE TO FEEL THE INCREASING HUMIDITY. THERE WILL BE A MODERATE RISK OF RIP CURRENTS ALONG THE BEACHES OF MAINE TODAY.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/... THE MAIN SHORT WAVE ENERGY IS FOISTED OFF WEDNESDAY MORNING BUT WE WILL SEE SOME LINGERING SHOWERS. TUESDAY WILL BE QUITE WARM WITH HIGHS IN THE 80S AND LOWER 90S. IF YOU KNOW SOMEONE WHO LIVES ALONE WITHOUT AN A/C THIS WOULD BE A GOOD TIME TO CHECK ON THEM. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... UPPER LOW CURRENTLY OVER HUDSON BAY IS FORECAST TO TRACK SOUTHEAST THROUGH QUEBEC AND THEN THE GULF OF SAINT LAWRENCE AND THE CANADIAN MARITIMES BY WEDNESDAY. AS IT DOES SO... EMBEDDED SHORTWAVE TROUGHS WILL ROTATE AROUND THE LOW PROVIDING THE LIFT NEEDED TO TRIGGER SHOWERS AND THUNDERSTORMS WITHIN THE INCREASINGLY WARM AND HUMID LOW LEVEL AIR MASS OVER NEW ENGLAND. THERE IS SOME UNCERTAINTY ON THE TIMING OF THE STRONGEST WAVE WHICH MOVES THROUGH THE REGION EITHER MONDAY NIGHT OR TUESDAY. GFS MODEL HAS THE WAVE MOVING THROUGH DURING THE DAY ON TUESDAY... TAKING MAXIMUM ADVANTAGE OF THE AFTERNOON DESTABILIZATION AND PROVIDING A GOOD CHANCE OF SHOWERS AND THUNDERSTORMS ESPECIALLY OVER EASTERN PARTS OF THE FORECAST AREA. THE NAM MODEL HOWEVER IS SIGNIFICANTLY QUICKER WITH THIS WAVE... MOVING THE LIFT EAST OF THE AREA EARLY TUESDAY MORNING. EVEN IN THE NAM SCENARIO THERE IS A SIGNIFICANT AMOUNT OF INSTABILITY (GREATER THAN 2000 CAPE NEAR AUGUSTA!) ALTHOUGH SYNOPTIC SCALE SUBSIDENCE SUPPRESSES AFTERNOON CONVECTION. SURFACE BOUNDARIES LIKE THE SEA BREEZE COULD STILL PROVIDE A FOCUS FOR THUNDERSTORMS TO DEVELOP... AND WITH THE TIMING OF THE BEST LIFT UNCERTAIN IT WAS PRUDENT TO INCLUDE A CHANCE OF THUNDERSTORMS FOR MOST OF THE COAST AND EASTERN AREAS ON TUESDAY. WIND SHEAR INCREASES AS THE DAY GOES ON AND COULD BE MARGINALLY SUPPORTIVE OF STRONGER STORMS INCLUDING SUPERCELLS. IT WILL BE A WARM DAY WITH JUST ABOUT ALL AREAS REACHING THE 80S AND SOME 90S EXPECTED IN SOUTHERN NEW HAMPSHIRE ALONG WITH SIGNIFICANT HUMIDITY. AS THE UPPER LOW TRACKS THROUGH THE CANADIAN MARITIMES ON WEDNESDAY IT WILL DRIVE A SURFACE FRONTAL BOUNDARY SOUTH THROUGH NORTHERN MAINE AND THEN SOUTHWEST THROUGH THE REST OF MAINE ON WEDNESDAY. THIS WILL HELP TEMPER THE OVERALL HEAT AND HUMIDITY THAT OTHERWISE WILL HAVE INVADED THE AREA. EXPECT MUCH OF NEW HAMPSHIRE TO STILL BE WITHIN THE WARMER AIR MASS WHILE TEMPERATURES FURTHER EAST ARE INCREASINGLY INFLUENCED BY THE COOLER AIR BEHIND THE FRONT. THE HIGH PRESSURE BEHIND THE FRONT SAGS SOUTH THROUGH EASTERN MAINE ON THURSDAY WHICH WILL SHIFT THE WINDS TO A MORE EASTERLY OR SOUTHEASTERLY DIRECTION AND CONTINUE TO PROVIDE A COOLING INFLUENCE TO MUCH OF MAINE AND EASTERN NEW HAMPSHIRE. WESTERN NEW HAMPSHIRE WILL BE PROTECTED FROM THIS MARITIME INFLUENCE BY THE MOUNTAINS... WARMING INTO THE 90S ONCE AGAIN. ALSO ON THURSDAY... THE NEXT UPPER LEVEL TROUGH AND ASSOCIATED SURFACE FRONTAL BOUNDARY WILL BE MOVING EAST THROUGH THE EASTERN GREAT LAKES AND INTO NORTHERN NEW ENGLAND. THIS WILL PROVIDE THE FOCUS FOR LIFT TO ONCE AGAIN TAKE ADVANTAGE OF THE WARM... HUMID... AND UNSTABLE AIR MASS OVER MUCH OF THE STATE OF NEW HAMPSHIRE. AS A RESULT... SHOWERS AND THUNDERSTORMS ARE EXPECTED TO FORM AGAIN IN THE AFTERNOON WITHIN THIS AIR MASS. THE BEST WIND SHEAR APPEARS TO BE FURTHER TO THE WEST BUT WE CANNOT RULE OUT A STORM OR TWO BECOMING STRONG TO SEVERE. INSTABILITY WILL BE LIMITED AND ELEVATED WITHIN THE MARITIME AIR MASS OVER MUCH OF MAINE... THUS LIMITING THE OVERALL THUNDERSTORM POTENTIAL THERE. CONTINENTAL HIGH PRESSURE BUILDS IN BEHIND THE FRONT FOR FRIDAY WITH A SLIGHTLY COOLER... BUT STILL WARM... AIR MASS. THE REST OF THE WEEK SHOULD SEE TEMPERATURES RISING INTO THE LOW TO MID 80S FOR HIGH TEMPERATURES. && .AVIATION /15Z SUNDAY THROUGH THURSDAY/... SHORT TERM...FOG AND STRATUS ONGOING THIS MORNING AND WILL IMPROVE BUT HANG AROUND FOR MUCH OF THE DAY. SHOWERS AND EMBEDDED THUNDERSTORMS WILL CAUSE MVFR CEILINGS AT LEAST LATER TODAY. LONG TERM...GENERALLY VFR EXPECTED. THERE WILL BE A CHANCE OF THUNDERSTORMS MAINLY TOWARD THE COAST ON TUESDAY. A COLD FRONT WILL BRING A MORE MARITIME AIR MASS WEDNESDAY AND THURSDAY ESPECIALLY OVER MAINE LOCATIONS. SOME LOW LEVEL STRATUS IS POSSIBLE WITHIN THIS AIR MASS. NIGHTLY FOG SHOULD BE EXPECTED AT LEBANON AND WHITEFIELD. && .MARINE... SHORT TERM...NO FLAGS ON THE WATERS. WINDS AND SEAS STAY BELOW SCA CRITERIA. A FEW THUNDERSTORMS MAY REACH THE WATERS. LONG TERM...GENERALLY LIGHT WIND FLOW EXPECTED OVER THE WATERS THROUGH THE WEEK. CONDITIONS SHOULD STAY BELOW ADVISORY LEVELS. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...NONE. NH...NONE. MARINE...NONE. && $$

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