Area Forecast Discussion
Issued by NWS Portland, ME

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943 FXUS61 KGYX 221604 AAB AFDGYX Area Forecast Discussion...UPDATED National Weather Service Gray ME 1204 PM EDT Sun Apr 22 2018 .SYNOPSIS... High pressure centered over the Great Lakes will build east into the region today...then stick around through Tuesday with fair weather and seasonable temperatures before exiting into the maritimes. By mid week, unsettled weather returns with the approach of our next storm system. && .NEAR TERM /THROUGH TONIGHT/... 1205 PM Update...Few changes to the forecast on this very pretty Spring day. Sunny skies and low dew points are allowing for temperatures to climb into the mid to upper 50s on the coastal plain and southern NH. Have adjusted highs up in certain places by just a couple degrees. 614 AM...For this ESTF update only minor adjustments to near term grids to reflect the current mesonet. Prev Disc... At 06z...a 1031 millibar high was centered over the Great Lakes. GOES imagery showed widely scattered clouds across the area pivoting around a decaying storm system centered northeast of Newfoundland. For today...the building surface high and rising heights bring a mostly sunny and mild day with a diminishing northwest flow to round out the weekend. Highs will range from the upper 40s and lower 50s across the mountains...to mid 50s to lower 60s elsewhere. && .SHORT TERM /MONDAY/... Clear and cool tonight under the building surface high and I undercut machine temperatures a bit in the dry airmass. On Monday...the high will be centered to our south. After a chilly start...temperatures will rebound to the mid 50s to lower 60s under the strong late April sunshine. The light synoptic flow will give up the ghost by afternoon in favor of a strong seabreeze with the mercury dropping off during the afternoon near the coast. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... The trend in model guidance has been to slow the advance of upper low pressure...allowing for one more dry and mostly clear day Tue. H8 temps around +5C will support widespread 60s across much of the forecast area. But all good things must come to an end...and so will our warming trend by Wed. Upper low pressure will lift into the Northeast as it is picked up by a trof digging across the central CONUS. SEly LLJ will develop and help transport PWAT values around 2 standard deviations above normal towards the forecast area. The 22.00z GFS and CMC feature a stronger interaction with the approaching trof...and thus higher QPF across the forecast area...while the 22.00z ECMWF keeps forcing more separate and lighter QPF amounts. ECMWF EPS shows nearly half of the members on the more robust side of QPF...giving some support to the North American solutions. That being said...this will be lighter than the last QPF event for the region. It will be worth keeping an eye on the headwaters though...as the gradual warm up and around an inch of QPF will bring some river forecast points to near flood stage. Ensemble river guidance using the NAEFS QPF does bring several points...including on the Saco...Swift...and Pemi...to a 30 to 50 percent chance of flooding. So I will continue to mention the threat in the HWO. Beyond the midweek system...Ern CONUS trofing looks to hang around. This will mean unsettled wx continues as we will be on the downstream side of the trof...but the pattern will also not be overly cold either. && .AVIATION /13Z SUNDAY THROUGH THURSDAY/... Short Term /through Monday/...VFR. Long Term...VFR conditions prevail thru early Wed. Developing onshore flow will see lowering CIGs by Wed afternoon...and precip moving in from the SW. Areas of MVFR/IFR are likely in RA thru early Thu. IFR CIGs will be most likely near the coast...but rainfall will be fairly widespread across the area. && .MARINE... Short Term /through Monday/...Quiet on the waters with winds and seas below SCA under building surface high. For Monday mid day and afternoon...developing seabreeze along the coast will bring gusts to 20 kt and briefly building seas. Long Term...Persistent Sly flow by Tue may allow seas outside the bays to build to 5 ft. As flow becomes more Ely and LLJ increases into Wed and Thu...more widespread SCA conditions are likely with gusts to 25 kts and seas over 5 ft. && .FIRE WEATHER... Winds gusting to the 15-25 mph range along with low dew points will bring marginal meteorological fire weather conditions to a few spots in New Hampshire and Maine this afternoon. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$ NEAR TERM...Hanes SHORT TERM...Schwibs

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