Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 271702 AFDGYX Area Forecast Discussion National Weather Service Gray ME 102 PM EDT Mon Mar 27 2017 .SYNOPSIS... Low pressure will track across southern New England later today before exiting the coast this evening. This disturbance will produce rain and a light wintry mix across portions of the interior through late today. A cold front will push through the region late Tuesday and Tuesday night resulting in upslope showers and northwesterly flow Wednesday into Thurday. A weak ridge will build into the region on Thursday and remain through Friday. The next storm will approach the region on Friday night bringing widespread precipitation for Friday into Saturday. && .NEAR TERM /UNTIL 7 PM THIS EVENING/...
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1255 PM...For this ESTF update trimmed back advisory area over southern and western sections while I extended it for a few hours over central interior Maine. This reflects current observational and radar trends as well as short term high resolution model output. Prev disc... 852 AM...For this ESTF update I dropped the freezing rain advisory for the Manchester and route 101 corridor as mesonet shows surface temperatures have warmed several degrees above freezing. Elsewhere...the various winter weather advisory headlines remain. The 14z expiration area has been delayed until 15z as we continue to see temperatures slow to warm above freezing and some pockets of light freezing rain are likely. I ingested the current mesonet into near term grids as well for this update. Prev Disc... 620 AM...Precip beginning to work in from the west, mostly in the form of FZRA or RA, at least across NH. For the most part, temps across NH are within a degree or two of freezing, and will likely not change much until the sun has been up for a couple hours, so will hold onto advisories as they are. In ME, seeing dome UP reports, which may be PL, but again in interior parts of the coastal plain, except for the eastern zones, temps right around freezing /although above along the coast from Casco Bay south/, and similar thinking applies here, that temps will hold where they are for a few more hours. Further inland in ME towards the moutnains and foothills, temps are in the upper 20s, and p-type will be a mixed bag this morning before transition to freezing rain, or rain by afternoon in some spots. Previously...Forecast still somewhat problematic as to p-type today, but it looks like we will see some wintry precip, especially freezing rain across all but SW coastal zones through the morning commute. Td depression did lower with first round of precip overnight, so wet bulb when the second round of precip come thru will not be as significant, but temps all hovering right around 32F in all but far nrn and interior ern zones, where they are in the upper 20s. Only changes to WSW was to end central NH and interior coastal ME zones at 18Z as temps should be above freezing by midday. Once precip begins in srn and coastal Maine, it should begin to mix down warmer temps from aloft, so in the areas any FZRA should end with a couple hours of precip onset. In the NE zones, mixed precip will produce some SN/PL/FZRA accumulations, but should transition to mostly freezing rain this afternoon. Here we could see one to tenths of icing thru the day. Precip will end from SW to NE during the late afternoon and early evening. Highs will range from the low 30s in the N to around 40 in the south.
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&& .SHORT TERM /7 PM THIS EVENING THROUGH 6 PM TUESDAY/... For tonight, the sfc low over the gulf of ME shifts eastward and flow turns to the NNW, which should allow drying aloft and end the precip. Sfc winds will remain light, so expect some clouds and some fog to continue. Temps will fall back a few degrees, but should remain above freezing in many spots outside of the mountains. On Tuesday, we will see a low pass to out north and one pass to our south, and this should pull a cold front across the areas later in the day, which will bring a chance of showers. It looks like enough of a SW flow will develop ahead of this front to mix down warmer air across the entire CWA, with temps rising into the upper 30s in the north to around 50 in the south. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... Typically the long wave pattern serves as a starting point to drive the forecast. What is notable in this extended period is the lack of any high amplitude long wave pattern. All of North American remains under mainly zonal flow with a series of very quick moving waves pushing through. A few of the waves try to form a cut off low over the southwest US but overall we see a very progressive pattern. While the lack of a strong pattern will keep both the very cold and very warm air at bay putting us happily near seasonal norms, the quick progression leads to very low predictability as any small change in the short waves create a large change the the forecast. Tuesday night begins with a cold front pushing through with scattered showers and northwesterly flow following. Upslope showers will continue through the day on Wednesday. A ridge builds in for Thursday and into Friday. High temperatures will be in the 40s with mostly clear skies and calm winds. The next low pressure system will develop near Chicago on Thursday night and move northeastward bringing precipitation into our area by late Friday. Precipitation will continue through Friday night and into Saturday. There is still quite a bit of uncertainty with some options keeping the low center to our north up the St. Lawrence valley and some allowing it to redevelop off the coast and moving through the gulf of Maine. These options mean that precipitation type is still uncertain as we wait to see which side of the warmer air we are on. For the moment have stuck with a blend and rain/snow, although some sleet or freezing drizzle is possible overnight. Sunday into Monday another ridge builds in returning us to seasonable temperatures and sunny skies. && .AVIATION /18Z MONDAY THROUGH SATURDAY/... Short Term...Conditions deteriorate to IFR toward daybreak with FZRA at all but coastal terminals through at least the first part of this morning. IFR will likely persist through tonight will some improvement to MVFR on Tue, perhaps some VFR at KMHT/KCON. Long Term... Wednesday will see upslope showers in the mountains resulting in possible MVFR for HIE through B80. High pressure builds in Thursday and Friday. Friday night into Saturday low pressure will move through bringing rain and widespread IFR conditions. && .MARINE... Short Term...Dropped SCA from CAsco Bay, but otherwise will see E-NE flow picks up this morning as low passes to our south and intensifies. Winds diminish this evening, but seas stay up overnight. Long Term... Small Craft conditions are likely Thursday as northwesterly flow moves over the waters in the wake of the cold frontal passage. && .GYX WATCHES/WARNINGS/ADVISORIES...
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ME...Winter Weather Advisory until 5 PM EDT this afternoon for MEZ007>009-012>014. Freezing Rain Advisory until 4 PM EDT this afternoon for MEZ019>022. NH...Winter Weather Advisory until 5 PM EDT this afternoon for NHZ001-002. MARINE...Small Craft Advisory until 6 AM EDT Tuesday for ANZ150>152-154.
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