Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 210656 AFDGYX Area Forecast Discussion National Weather Service Gray ME 256 AM EDT Sat Apr 21 2018 .SYNOPSIS... Low pressure centered over Newfoundland will continue to circulate a few clouds into the area today...especially across northern and mountain sections. 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 TODAY/... At 06z...a 994 millibar surface low was centered over Newfoundland with a weak surface trough extending westward into the Gaspe Peninsula. A sprawling area of 1032 millibar High pressure extended from Hudson Bay southward across the Great Lakes. GOES imagery showed clouds and shortwave impulses pivoting around the stacked system over Newfoundland and into northern New England. For today...we`ll continue to see broken clouds across the higher terrain and over our eastern and northern Maine zones in continued cyclonic and upslope flow. Elsewhere...a few fair weather clouds will develop in response to daytime heating. The gusty westerly flow between the maritimes system and high pressure will continue before the gradient begins to relax later today. It`ll be another chilly day by late april standards as we warm into the 40s across the mountains...with upper 40s and lowers 50s for the remainder of the area. && .SHORT TERM /TONIGHT THROUGH 6 PM SUNDAY/... With the exception of a few lingering upslope clouds in the mountains...and over our northern and eastern maine zones with the upper low...skies will become mostly clear tonight. Winds will also drop off and we`ll see a cold night with overnight readings in the 20s to around 30. Sunday will be a mostly sunny day with light winds under the building surface high. Temperatures will warm into the 40s along the international border...with lower and mid 50s for the remainder of the forecast area. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... Model guidance remains consistent with ridging to the N of upper low/trof forecast to slowly churn across the Srn CONUS thru early next week. The gradual warm up will continue into early next week...with some readings in the 60s likely Mon and Tue. Multi-model consensus is a little on the cool side...mainly because the recent colder than normal wx is dragging the bias correction away from warm temps. I have added a little more MOS guidance to the blend to try and offset that effect thru Tue. By late Tue thru Wed model guidance brings in the next round of precip. That slow moving upper low lift NEwd...and with PWAT values forecast to be above normal for this time of year we should see a pretty widespread rainfall. While it will not be a warm rain...it will be mild enough for mainly rain except for the highest elevations of the forecast area. The combination of gradual snow melt in the milder temps plus rainfall will allow river flows to increase thru next week. Looking at ensemble flow guidance...that is enough to push a handful of headwater gauge locations above flood stage late in the week. So it will be something to keep an eye on. Beyond midweek the pattern remains consistent with general trofing over the Ern CONUS. With the trof axis centered to our W that could allow for some sneaky warm days in SW flow aloft...but overall not a much above normal look. It should also keep precip chances in the forecast as well on the downstream side of the trof. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... Short Term /through Sunday/...VFR. Long Term...VFR conditions expected thru Tue. Weak pressure gradient over the area Mon afternoon will likely allow for some sea breezes to develop At PSM...PWM...and RKD. Flow becomes more onshore across a wider area Tue. Continued onshore flow and increasing moisture will allow some areas of MVFR to develop ahead of an approaching upper low. MVFR/IFR possible late Tue into Wed in -RA. && .MARINE... Short Term /through Sunday/...Gusty sub-SCA westerly flow continues across the waters today before diminishing tonight under building surface high. Long Term...Ely flow developing on the N side of an approaching upper low will bring winds and seas outside the bays to around SCA thresholds. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$ NEAR TERM...Schwibs SHORT TERM...Schwibs LONG TERM...Legro

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