Area Forecast Discussion
Issued by NWS Portland, ME

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316 FXUS61 KGYX 010200 AFDGYX Area Forecast Discussion National Weather Service Gray ME 900 PM EST Tue Feb 28 2017 .SYNOPSIS... A warm front will approach from the south and west tonight. Warm weather builds on Wednesday as the front lifts through the region. Temperatures will be near record warm levels before a cold front moves across the area Wednesday night. Showers and thunderstorms will be possible as the front moves through. Colder air rushes in behind the front Thursday morning and lasts through the weekend. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... 855 pm update: Radar showing some very light precipitation aloft but so far none reaching the ground. Lower levels continue to moisten up on developing ssely flow. POPS forecast for the rest of the night looks good. Low stratus now forming to our south and over southeast NH and will gradually spread north and west over the next few hours with developing areas of drizzle and fog expected. After inputting latest mesonet data only minor adjustments to near term temps were needed. 540 am update: Input latest mesonet data and made some minor adjustments to near term temps. Also adjusted pops for next few hours slowing down eastward progress of rain. Attm radar shows an area of echoes across NH but the precipitation is all aloft as the overrunning moisture is moving into very dry low levels. Over the next few hours this will change as lower levels gradually moisten up. Previous discussion: Areas of light rain will advance eastward ahead of an approaching warm front tonight. Initially the airmass will remain dry as the moisture moves in late this afternoon and this evening. This dew point depression will allow for a slight delay in the onset of precipitation. Low dew points in northern areas may allow the precipitation to begin as a period of rain and snow mixture. There may also be pockets of light freezing rain in north-central New Hampshire overnight. The overall potential and areal coverage is small. With this low confidence, a freezing rain advisory has not been issued, however this region will need to be monitored tonight. Patchy drizzle and fog is expected to develop overnight over southern areas as winds arrive off the Gulf of Maine. Created a non-diurnal curve. Temperatures will gradually drop through midnight with the aid of low surface dew points, then steady off or perhaps slowly rise late tonight. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/... The warmth builds on Wednesday as a warm front crosses the region. H850 temperatures will approach +6C to +10C across the region on wind fields approaching 50 kts by late in the day. This will allow temperatures to climb into the 50s across much of the region, with low 60s over southern New Hampshire. Any significant breaks in the cloud cover could yield even warmer, potentially record breaking readings. Height falls and the approach of a strong cold front late in the day Wednesday and Wednesday evening may allow for the development of thunderstorms in our increasingly unstable and high shear environment. With such strong wind fields in place, a few of the storms have the potential to produce damaging winds over far southern New Hampshire. This is in good agreement with the current SPC day two outlook Strong gusty winds continue to be a potential issue over southern New Hampshire Wednesday evening. Thereafter, all areas will begin to have gusty westerly winds in a strong cold air advection and increasing pressure gradient as the surface low intensifies and begins to move east of New England. && .LONG TERM /THURSDAY THROUGH TUESDAY/... Progressive and deep upper trof with its associated cold front exits into the Maritimes Thursday with downsloping colder northwest winds in its wake. Scattered snow showers are possible in the mountains otherwise partly to mostly sunny skies expected elsewhere. The cold northwest flow will continue into the weekend with continued advection of colder temps each day. By Saturday high temps will be averaging well below normal with highs only reaching the single number and lower teens in the mountains to lower 20s over southern areas. By late in the weekend the coldest pocket of arctic air moves off to the east. On Monday a return lower level southerly flow will begin to develop possible causing some light overrunning snow or mixed precipitation to develop across the area. Used superblend for this extended forecast cycle with little reason for any deviation. && .AVIATION /02Z WEDNESDAY THROUGH SUNDAY/... Short Term...Conditions will be lowering to IFR and locally LIFR conditions tonight into Wednesday morning with patchy drizzle and fog, mainly over southern areas. Conditions will be slow to improve Wednesday afternoon. Some LLWS expected with increasing winds aloft. A strong cold front will cross the region Wednesday evening with a wind shift to the west and drying conditions downwind of the mountains. Long Term...SYNOPSIS... NEAR TERM...Marine SHORT TERM...Marine LONG TERM... AVIATION... MARINE... HYDROLOGY... Mainly VFR conditions. A gusty northwest flow will continue Thursday and into the weekend. && .MARINE... Short Term...Will continue with a gale watch for Wednesday night into Thursday. Highest winds will likely be associated with the cold air advection and increasing westerly gradient on Thursday. Long Term...A strong northwest flow will persist Thursday into Thursday night behind the cold front...thus Gale Watches continue into Thursday evening. The northwest flow will continue through the weekend. Another round of Gale force winds are possible Saturday into Saturday night as a reinforcing shot of arctic air behind a secondary arctic cold front moves across the waters. && .HYDROLOGY... There are currently no problems noted on the rivers as ice movement from a few days ago has largely stopped. But continued warm weather especially on Wednesday could get things flowing again and will raise the possibility for more ice jam related flooding. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...Gale Watch from Wednesday evening through Thursday evening for ANZ150>154. && $$

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