Area Forecast Discussion
Issued by NWS Portland, ME

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071 FXUS61 KGYX 211220 AFDGYX Area Forecast Discussion National Weather Service Gray ME 720 AM EST Tue Feb 21 2017 .SYNOPSIS... High pressure will crest over the region early today before shifting offshore. A warm front will push east through the region tonight. Low pressure moving east through southern Canada will drive a cold front toward the region late Wednesday and Wednesday night. The front will cross the region on Thursday followed by high pressure Thursday night. A warm front will approach from the southwest Friday and will lift north of the area Friday night. A cold front will gradually push into the region from the west on Saturday. Low pressure will form on the front south of Long island and will move northeast through the Gulf of Maine Saturday night. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 12z update... Quick update to adjust temp/td/sky grids. High clouds will be on the increase through early afternoon...mainly in western zones. Sunshine will continue to fade behind high clouds across the remainder of the forecast area during the afternoon. No other changes planned attm. Previous discussion... High pressure will crest over the region early today and will shift offshore this afternoon. After a mostly sunny morning high clouds will filter in during the afternoon as a warm front approaches from the west. Highs will range from the mid 30s to lower 40s north and lower to mid 40s south. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/... Clouds will gradually lower and thicken tonight as the warm front pushes in from the west. Very weak over-running with this boundary will be diminishing as it moves into New England but some light spotty freezing rain or sleet may hold together long enough to make it into western zones after midnight. Models only offering chance pops for the overnight hours so will not be going with any headlines. Any areas of precip will likely be highlighted with special weather statements toward the morning commute on Wednesday. Lows overnight will generally range through the 20s to near 30 degrees. The front will wash out on Wednesday leaving the region in a warm southwesterly flow. High temperatures will push well above normal with most of the region topping out in the 40s to near 50. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... Little change to the extended based on last couple of model cycles. A fast moving Nrn stream s/wv trof is forecast to pass N of the forecast area Thu. This will send a cold front towards the forecast area...which should stall somewhere close by. NW flow over the higher terrain will help generate some rain showers...and snow at highest elevations...but little else S of the mtns. A more significant s/wv trof is forecast to lift thru the Midwest...sending strengthening low pressure into Srn Canada. Locally...the stalled front left behind from Thu will lift back N as a warm front. This may be enough for a few light showers...but widespread precip with this feature is unlikely. It looks like there is growing consensus that we remain in the warm sector...at least aloft...into early Sat. At that time both 21.00z GFS and ECMWF agree that the system will begin to entrain moisture from a remnant cut off low off the Bahamas. That will feed into a sharp cold front forecast to arrive across the area Sat night. That will be our best bet at appreciable rainfall. With high pressure sliding E into the Atlantic...temps should be cool but remain above freezing. Cold front crosses the area early Sun...with a follow up s/wv trof providing extended chances for upslope showers into Mon. && .AVIATION /12Z TUESDAY THROUGH SATURDAY/... Short Term...VFR today. Areas of MVFR ceilings developing overnight. VFR on Wednesday. Long Term...VFR prevails thru Thu at most terminals. Exception will be HIE...where a passing cold front may bring SHRA late Thu. MVFR conditions are possible there while upslope flow continues into the overnight. More widespread MVFR or lower conditions are possible Fri as a warm front lifts N thru the area. Pockets of IFR or lower are possible in deep onshore flow. This will continue into Sat...and then a strong cold front will approach from the W towards evening. Steady precip will likely only affect NH terminals prior to 00z Sun. && .MARINE... Short Term...Brief period of SCA`s may be needed for the outer waters overnight but will let the day shift make the decision on timing and extent. Long Term...Winds and seas will generally remain below SCA thresholds thru the end of the week. A sharp cold front will cross the waters over the weekend...and bring an extended period of SCA conditions to all waters. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$

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