Area Forecast Discussion
Issued by NWS Portland, ME

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272 FXUS61 KGYX 081203 AFDGYX Area Forecast Discussion National Weather Service Gray ME 703 AM EST Thu Dec 8 2016 .SYNOPSIS... A slow moving broad upper trough over the Great Lakes will move through southern Canada today and Friday, spreading snow showers into the mountains as it approaches. Ahead of this broad upper trough, a weak cold front will cross the area later today and then followed by an arctic cold front through the region on Friday bringing gusty northwest winds and much colder temperatures that will continue through the weekend. The next potential storm system will approach late Sunday night and Monday. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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7am update: Patchy fog continues so will extend it for another hour or so before it dissipates due to mixing. Rest of forecast unchanged based on latest ingested mesonet data. Previous Discussion: Areas of early morning fog will dissipate by 12z. Otherwise a general westerly flow develops today as an upper trof over the Great Lakes approaches. This will spread orographically induced snow showers in the mountains with some light accumulations expected. Elsewhere in the downsloping areas just some clouds can be expected. Used a blend of models for max temps which should range from the 30s to lower 40s.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/... Tonight and Friday the snow showers will continue in the mountains with additional accumulations expected in the more favored exposed mountain areas to the northwest flow. Elsewhere downsloping will continue with partly cloudy skies although a few stray flurries may try to reach southern areas. The broad upper trof moves thru the region Friday and exits to the east by later in the day. It will drag an arctic cold front thru the area in the afternoon so northwest winds will become gusty and temps will be colder especially later in the afternoon. Total snow accumulations in the mountains thru Friday will range from 2-5 inches. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... Cold northwest flow will be the rule Friday night and Saturday with wind chill values in the single digits at most locations, with those readings below zero in the mountains. Upslope snow showers will continue in the Whites Friday night. High pressure moves in Saturday night with very cold low temperatures expected. The 00z deterministic runs of the GFS and ECMWF are in better agreement with the progression of short wave troughs and resultant winter weather potential Sunday and Monday. Overall, the consensus is generally for a weak short wave passage late Sunday. With limited moisture and forcing for ascent, we aren`t expecting much in the way of precipitation Sunday afternoon and evening - perhaps a period of very light snow or flurries. Another dampening short wave trough is expected to approach later Sunday night and Monday allowing to relatively weak low pressure to pass to the south of New England. The latest 00z runs of the ECMWF and GFS generally concur with how things will pan out through Monday with a period of accumulating snow, mainly across the southern half of the CWA. However, it is worth noting that uncertainty remains high as many GFS and ECMWF ensemble members show considerable spread in low pressure timing and track. Therefore, we expect continued bouncing around in upcoming deterministic runs over the next day or two until the strength, track, and speed of short wave troughs can be better resolved and agreed upon. For example, the 00z deterministic GFS dries us out Tuesday, but the ECMWF has another short wave trough approaching with a good shot of snow...while the GFS builds ridging. The bottom line is a low confidence forecast for the Monday- Wednesday timeframe as far as any wintry weather impacts go. && .AVIATION /12Z THURSDAY THROUGH MONDAY/... Short Term...Variable conditions from VFR to IFR in areas of fog thru 12z this morning. After 12z VFR conditions except MVFR conditions in the mountains in scattered snow showers thru Fri. Long Term...VFR conditions are expected Friday night through Saturday night. Periods of MVFR conditions possible late Sunday and Sunday evening in some very light snow. IFR conditions will then be possible on Monday in Snow. && .MARINE... Short Term...A cold front will cross the waters this afternoon and in its wake increasing west SCA winds can be expected that will continue into Friday. During the day Friday the west to northwest flow will increase further and may reach Gale force winds as an upper trof moves thru the region, thus a Gale watch remains in effect for during the day Friday into Friday night. Long Term...Gale watch remains in effect for Friday night for potential NW gales. SCA conditions then continue through Saturday and subside for Sunday and Monday. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...Gale Watch from Friday morning through late Friday night for ANZ150-152-154. Small Craft Advisory from 3 PM this afternoon to 10 AM EST Friday for ANZ150>152-154. && $$

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