Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 231428 AFDGYX Area Forecast Discussion National Weather Service Gray ME Issued by National Weather Service CARIBOU ME 1028 AM EDT Thu Mar 23 2017 .SYNOPSIS... Very cold air remains in place across the area today, though winds will be a little lighter than they were yesterday. High pressure will move across the area tonight with a warm front crossing the area on Friday, bringing some light snow and rain. Another cold front will drop south into the area Friday night into Saturday, stalling south of New England. A wave of low pressure will move along this front on Monday, spreading some wintry precipitation into the region. A few more waves of low pressure will move through the region Tuesday and Wednesday with more chances of precipitation. && .NEAR TERM /THROUGH THIS AFTERNOON/... 1030 AM UPDATE... Adjusted the hrly temps and winds to match the latest conditions. Forecast is on track w/sunny and breezy conditions through the afternoon. ORIGINAL DISCUSSION... High pressure remains to our west, with the cold northwest wind still blowing. This wind will not be quite as strong today as it was yesterday, but it will still be noticeably gusty. Temperatures today top out in the 20s to low 30s as some gradually warmer air begins moving in from above today. Temperatures at 850 MB are expected to warm about 8C from yesterday`s 00Z sounding at Portland. Considering the temperature at Portland at the time of last night`s sounding was 18 degrees F, this 8C increase would translate to about a 14F increase in surface temperature assuming similar mixing (we will not mix as high today as we did yesterday). Using this method, we should expect a high temperature of 32F or less at Portland today. This is significant because it would be the 11th day this month that the temperature failed to rise above freezing, the most such days ever recorded in March. We are currently tied with several other years (most recently in 2014) at 10 days. && .SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/... High pressure crosses the area tonight allowing winds to go calm. We should see at least a period of good radiational cooling conditions in the evening before clouds increase from west to east later in the night. By morning, warm/moist advection aloft will be enough to begin spreading precipitation into the area from west to east ahead of an approaching warm front. Thermal profiles suggest that much of this precipitation will fall as snow ahead of the warm front. There may be a transition to rain as temperatures warm, but this will be near the time that precipitation is coming to an end anyway. With low level flow out of the south or southwest, this is not a flow that would promote cold air damming so this should mostly be a snow to rain event. It is possible that a few valley locations in the north could hold on to some low level cold air and see a brief period of ice. Overall snowfall amounts will be fairly light, generally 1 to 2 inches, with warming temperatures likely melting a good amount shortly after it falls. Precipitation should come to an end outside the mountains by Friday evening. Temperatures overnight Friday night will be fairly mild, especially by recent standards, though a cold front dropping in from the north will allow temperatures to fall back below freezing again in the northern half of the area by morning. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... Unsettled weather pattern with a series of systems with varying precipitation types will continue to dominate the long term period. Models are in better agreement in the near term for the weekend, but continue to diverge more as time progresses. The biggest thing to note is the continued chance of freezing rain from the system Sunday night into Monday, which could affect the Monday morning commute. Still a little out for the short term models to pick up on the finer detail at this time. After frontal passages on Friday...Saturday will be relatively mild with near normal temperatures. A cold airmass will build in from Canada and will cause below normal temperatures Saturday night and Sunday. The next frontal system will approach from the southwest and affect the area late Sunday night through Monday. This is were the uncertainty starts to be an issue due to the pockets of freezing rain in Southwest NH and the coastal plain late Sunday night into Monday morning. Overall the region will be dominated by rain and snow from south to north. On late Tuesday night through Wednesday, the next system will sweep through the area from the west. This is the time frame with the greatest model divergence giving the most uncertainty. Will not rule out wintry mix in our region at this point. Overall long term is based on the Super Blend guidance with minor tweaks on Sunday night into Monday to put a chance of freezing rain in the forecast. && .AVIATION /15Z THURSDAY THROUGH MONDAY/... Short Term...Expect VFR conditions today with northwest winds not as gusty as they were yesterday, generally only gusting to 20KT. These winds will become calm tonight, with increasing clouds from west to east by Friday morning. On Friday expect lowering ceilings and a period of light snow possibly transitioning to rain from west to east through the afternoon and evening. Long Term...Saturday will start out with limited MVFR in the region and then have VFR conditions through late Sunday night. From late Sunday night into next week will see areas of MVFR and IFR due to ceilings, visibility and precipitation. && .MARINE... Short Term...Winds should fall below gale force across the western Gulf of Maine by around 8AM, but freezing spray may continue a few hours longer. Winds continue to diminish tonight as high pressure moves across the waters. Long Term...Small crafts should drop off by Saturday and return again on Monday through Wednesday. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...Small Craft Advisory until noon EDT today for ANZ153. Small Craft Advisory until midnight EDT tonight for ANZ150>152- 154. && $$ SYNOPSIS...Hewitt NEAR TERM...Hewitt SHORT TERM... LONG TERM... AVIATION...Hewitt MARINE...Hewitt

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