Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 170238 AFDGYX Area Forecast Discussion National Weather Service Gray ME 938 PM EST Mon Jan 16 2017 .SYNOPSIS... A ridge of high pressure will bring fair weather through Tuesday morning. Low pressure moves out of the Great Lakes late tuesday then redevelops off the mid Atlantic coast by early Wednesday. This system will bring snow, with some mixed precipitation to the area before exiting the region late Wednesday. High pressure will then build in for the remainder of the week, with above normal temperatures expected. A weak low pressure system may affect the region this weekend. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... 930 pm update: High clouds continue spilling across southern NH and extreme southwest ME otherwise mostly clear conditions elsewhere. Latest mesonet data shows temp forecast on track with only minor tweaks. No other changes needed. 655 pm update: High clouds have spilled into southern NH and southwest ME ahead of the approaching system so minor adjustments to cloud forecast otherwise based on latest input of mesonet data no other changes needed at this time. Previous Discussion: At 19z...a 1032 millibar high pressure ridge was draped along the coastal plain from the DELMARVA through New England. a 1003 millibar low was over Quebec with an associated warm front bringing a few clouds from international border through northern Maine. For tonight...a trailing cold front with the passing Quebec low will drop into northern areas with a few clouds. Otherwise...a mainly clear and cold night under the surface ridge. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY/... Concerning the arrival of the late Tuesday storm system...the split flow regime is proving to be problematic as models are having a tough time with interaction of northern and southern stream energy and exactly how much phasing will ultimately occur. Warmer air will try to sneak in initially before the secondary low takes over and draws colder air back southward. Any mixing with sleet or rain will help to hold down snow totals over extreme southern New Hampshire as well as along the southwest Maine coast. Models do hint at cold air damming and just inland on the cold side of where the coastal front ultimately sets up we`ll see potentially higher snow totals as well. A model blend yields the highest QPF from southern New Hampshire into adjacent southwest Maine with amounts dropping off quickly further north and east. The potential exists for a band of 6 inch snows from southern New Hampshire into extreme southwest Maine and have opted for a winter storm watch from the lakes region southward in New Hampshire and adjacent southwest interior Maine. The coast will likely see more mix and lower snow totals and have opted to not issue a watch there for now. We`ll see some sun early ahead of the system with highs rebounding to the upper 20s to mid 30s during the afternoon. Snow arrives over far southern and western sections towards dusk and may start as rain or a mix of rain and snow where boundary layer temperatures are several degrees above freezing. For Tuesday night...steadier precipitation spreads north and east across the remainder of the region. With the exception of extreme southern New Hampshire as well as near the coast...we should be could enough for snow. Southern sections will see a mix going to snow in many locations as the secondary low develops over the mid atlantic region and draws colder air back into the area. Precipitation will quickly taper off to snow showers by Wednesday afternoon as the low slides well offshore to our south. However...the lingering onshore flow and a surface trough could provide some light drizzle or freezing drizzle for a time after the steadier precipitation ends. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... Low pressure departs on Wednesday night but another quickly approaching short wave trough may bring scattered snow showers, especially to the mountains, and this may continue through Thursday morning. High pressure then moves in Thursday afternoon through Friday night. Another weak system then looks to affect the region during the day on Saturday with rain or snow showers. Thereafter an even more amplified/blocky upper air pattern looks to take shape across the U.S. which will lead to lower confidence here in terms in sensible weather. However, there is some early model and ensemble consensus for the potential for a significant precipitation event early next week. && .AVIATION /03Z TUESDAY THROUGH SATURDAY/... Short Term /through Wednesday/...VFR, then lowering to IFR aft 22z Tue in SN/IP/RA. Some -FZRA is psb over SW NH Tue night. On Wed...conditions gradually improving to MVFR by afternoon. Long Term...MVFR to VFR Wednesday night into Thursday morning in snow showers. VFR Thursday afternoon through Friday. Some MVFR may reappear on Saturday in light snow and rain. && .MARINE... Short Term /through Wednesday/...Winds have diminished below SCA conditions over all but the eastern most outer waters. Have dropped the SCA`s except for the eastern outer waters where the SCA will continue until 05z at which time winds should diminish. Previous Discussion: SCA continues for outer waters through evening as SW flow surges briefly to around 25 kt and pushes seas up to 5 ft. We drop briefly below SCA late tonight and Tuesday before NE flow increases seas and winds outside the bays to small craft for Tuesday night and Wednesday. Long Term...Small craft conditions will gradually begin to subside Wednesday night and continue subsiding Thursday. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...Winter Storm Watch from Tuesday evening through Wednesday afternoon for MEZ018-019. NH...Winter Storm Watch from Tuesday evening through Wednesday afternoon for NHZ005>013-015. MARINE...Small Craft Advisory until midnight EST tonight for ANZ150. && $$

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