Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 151504 AFDGYX Area Forecast Discussion National Weather Service Gray ME 1004 AM EST Mon Jan 15 2018 .SYNOPSIS... High pressure will crest over the area today. However, a weak trough may bring a few flurries or widely scattered snow showers to the New Hampshire sea coast. Low pressure will approach from the west Tuesday before crossing northern New England Tuesday night and Wednesday. Low pressure will form off the Mid Atlantic coast Thursday, but will pass well out to sea Thursday night. Canadian high pressure will build back over the region Friday. A warm front will then cross the region, bringing mild temperatures next weekend. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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950 AM Update: Generally clear skies across most of the region at this time, except where ocean clouds are flirting with the immediate coastline over southern ME and the seacoast of NH. These ocean clouds should slowly move west during the afternoon. Made a few minor tweaks to temps/dewpoints based on latest obs data. 620 AM...Seeing some clouds rolling in already in onshore flow south of Saco Bay, and streaming WSW toward the MHT area. So have adjusted sky cover higher here. Models continue to keep the snow offshore or to our south, and given the flow direction, and the dry low level air, this seems reasonable. Again, cannot rule out some snowflakes, and maybe a dusting in spots S of PSM on the coast, but overall effect will be limited to this small part of CWA. Otherwise just some tweaks to temps/sky based on current conds. Previously...Coastal low will pass well to our east today and this will allow N flow to persist through today. The flow shifts lightly east of N this afternoon and this could being some ocean effect SHSN into coastal NH. the 10-20 degree flow direction certainly favors areas S of the CWA, like Cape Ann, for accumulating snow, but wouldn`t be surprised to see a little very light snow along the immediate NH coast late today. Should see clouds increase along the York county coast this afternoon, especially from Kennebunkport south. Elsewhere look for mainly sunny skies this morning with some thickening cirrus this afternoon especially in the south and western zones. Highs will be limited to the teens in most places, but coastal areas and srn NH should top out around or a little above 20.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/... Overnight the flow will back a little and become more northerly as the low to our east tracks n of of out latitude, and this will bring an end to any ocean effect snow this evening. Models are still struggling, even at this short range to deal with several weak 500 mb waves moving through SW flow ahead of trough to our west, and how they may interact. Thinking is we see a fair amt clouds moving in overnight, although could see some breaks late and into Tue morning. Expect some cooling in the evening, but temps will likely remain stationary later in the night , bottoming out from zero to 5 above in the mountains to 10-15 above on the coast and in srn NH. On Tuesday, there may be a little lull between waves and will likely see just partly -mostly cloudy skies in the morning becoming overcast during the afternoon. Weak WAA will work into wrn zones by midday, producing some light precip, which will initially struggle to make it through the low lvl dry air. Will probably see some snow make its way into parts of NH by later in the afternoon, but bulk of snow will hold off until Tue night. Highs Tuesday will be a little warmer as flow shifts from N to SSE, and highs will generally be in the 20s. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... The deterministic model solutions are in decent agreement on the long wave pattern through the upcoming weekend. Pacific energy will break down the western CONUS ridge early in the period and eventually the downstream trough across the eastern CONUS. This will cutoff the supply of arctic air to the region and lead to temperatures rebounding above normal for much of the upcoming period. However...there are signs in the models that the western CONUS ridge may begin to rebuild towards D+10. So...this next warmup may be short lived. In the dailies...we begin the period with a upper trough axis draped across the Great Lakes and midwest on Wednesday that weakens and exits the coast by Thursday. At the surface...weak low pressure develops off the coast and tracks southeast of Cape cod on Wednesday before exiting into the maritimes by early Thursday. This system will likely bring several inches of snow to the region Tuesday night into the day on Wednesday. The best chance for a plowable snow will exist along the coastal plain. A second low develops off the Carolina coast along the trailing cold front and passes well offshore to our east late Thursday and Thursday night. Rising heights and high pressure building to our south will introduce well above normal temperatures into the region for Friday and the upcoming weekend. && .AVIATION /15Z MONDAY THROUGH FRIDAY/... Short Term...Mainly VFR into Tue. Interior NH terminals could see some MVFR in SHSN or light SN late Tuesday. Long Term... Tue Night - Wed...MVFR with areas of IFR in snow. && .MARINE... Short Term...SCA winds/seas likely to persist through tonight as coastal low passes to our east. FZ spray will be light to moderate through today at least, but warming temps and diminishing winds should put an end to it sometime tonight. Long Term... Thu - Fri...Small Craft conditions are possible. && .HYDROLOGY... All rivers but the Kennebec at AUG have fallen below flood stage, but ice jams have frozen into place in some areas, and rivers need to need to monitored as these jams could move without notice. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...Freezing Spray Advisory until 6 PM EST this evening for ANZ150>154. Small Craft Advisory until 6 AM EST Tuesday for ANZ150>152-154. && $$ is the U.S. government's official web portal to all federal, state and local government web resources and services.