Area Forecast Discussion
Issued by NWS Portland, ME

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125 FXUS61 KGYX 201407 AAB AFDGYX Area Forecast Discussion...UPDATED National Weather Service Gray ME 1007 AM EDT Fri Apr 20 2018 .SYNOPSIS... Low pressure centered southeast of Nova Scotia will drag several weak troughs across the area through early Saturday. The circulation around this system will produce cool weather today and tonight along with a few rain and snow showers...especially across the higher terrain. On Saturday...we`ll see some lingering clouds mainly across the higher terrain. By Sunday...high pressure and sunny weather arrives along with the start of a gradual warming trend. By mid week...unsettled weather returns with the approach of our next storm system. && .NEAR TERM /THROUGH TONIGHT/... 1005 AM Update...Insolation this morning is allowing stronger winds to mix to the surface...with locations currently gusting into the teens and 20s. Some locations will be closer to 30 mph, especially along the coast, later this afternoon. Downsloping had helped skies over the coastal plain clear out for a while, but cold air stratus/stratocumulus clouds are already popping up in weak instability due to cold pool aloft. Widely scattered showers will mainly affect the mountains and the Mid Coast region through the day...with sprinkles or flurries possible elsewhere. 614 AM...Minor ESTF update to reflect current radar trends as well as the latest mesonet in near term grids. Prev disc... At 06z...an 998 millibar low was centered southeast of Nova Scotia with a surface trough extending into northern Maine. GOES water vapor imagery showed an associated upper low over eastern New England. NWS Doppler Radar mosaic showed several areas of light return with a more significant area of echoes noted across our favored upslope areas of Northern New Hampshire into western Maine. For today...several weak surface troughs and associated impulses will pivot around this system as it slides further east. The cool cyclonic flow should result in mainly cloudy skies with some lingering upslope snow and rain showers for the higher terrain. Temperatures will recover into the 40s and lower 50s...but the northwest breeze will make it feel a bit cooler as our below normal temperatures continue. && .SHORT TERM /SATURDAY/... Some lingering clouds tonight over the higher terrain as well as over our eastern and northern Maine zones...with skies becoming mainly clear elsewhere. There will be some lingering snow showers across the higher terrain as well. Lows will range from the upper 20s to mid 30s. On Saturday...we continue with the cool cyclonic flow with one last impulse to pivot across the area during the day. This should keep broken clouds across the higher terrain as well as over our northern and eastern Maine zones...with skies averaging partly sunny for the remainder. There will be a bit less wind on Saturday along with temperatures several degrees higher than today...so tomorrow offers some slight improvement over today as we begin the weekend. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... There is some good news on the horizon as we start off the extended period. A progressive ridge aloft will build towards the region this weekend. As that ridge moves Ewd...building ridging ahead of an upper low temporarily cut off from the Nrn stream will replace it. That will give us several days of mostly clear skies...dry wx...and near to above normal temps. Given how below normal this month has been so far...this will seem awfully mild for what is in actuality to be expected this time of year. Aside from the desire to get out and enjoy the wx...the biggest impact will be snow melt in the headwaters. The warm up is marginal enough that snow melt should be gradual...and river rises fairly typical. But considering flows are already high from recent rain...it will be worth keeping an eye on for flooding concerns. The aforementioned upper low catches up with us by the middle of next week...sometime Wed or Thu. The 20.00z GFS and ECMWF have some timing difference...with the GFS on the faster side. The CMC leans in favor of the ECMWF...but given the tendency for modeling to handle cut offs poorly I am not willing to bite one way or the other just yet. For now the multi-model consensus is for likely PoP Wed night...and that seems a reasonable compromise. I prefer to keep the likely wording in the forecast as well...since it will rain sometime in that period...with exact timing TBD. Beyond the late week ensemble model guidance continues to favor Ern CONUS trofing...so the search for true warm wx continues. && .AVIATION /14Z FRIDAY THROUGH TUESDAY/... Short Term /through Saturday/...VFR with sct MVFR in mtn -shra/-shsn with isold IFR in -shsn. Improving to VFR throughout aft 12z Sat. Long Term...High pressure builds over the forecast area Sun into early next week. VFR conditions will prevail with light winds...which will likely allow for sea breezes to form. Enough background gradient flow is likely Sun to keep sea breeze very near the coast...but Mon and Tue winds are more likely to become SEly at PSM and PWM...and Sly at RKD. && .MARINE... Short Term /through Saturday/...Gusty westerly flow will persist through the period but should remain just below SCA even outside the bays. Long Term...High pressure in control of the coastal waters...and generally light winds and small seas. Low pressure developing over the Mid Atlantic midweek will allow flow to become more Ely and help build seas above 5 ft outside of the bays. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$ NEAR TERM...Hanes SHORT TERM...Schwibs

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