Area Forecast Discussion
Issued by NWS Portland, ME

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522 FXUS61 KGYX 291347 AFDGYX Area Forecast Discussion National Weather Service Gray ME 947 AM EDT Wed Mar 29 2017 .SYNOPSIS... Behind a departing low pressure system, a northwesterly flow will introduce cooler and drier air into the region today. High pressure will build into the region for Thursday. Low pressure will then approach the region for late Friday into Saturday with snow and mixed precipitation likely for the region. Canadian high pressure will then build into the region on Sunday. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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945 AM Update...A few minor adjustments, mainly to PoPs and temperatures for today. Mostly dry weather is expected outside of nwly upslope regions in the mountains. However, for the next hour, a very narrow convergence band of rain showers across Franklin, Androscoggin, and Cumberland Counties should persist for a little bit, then dissipate. Otherwise, we raised snow amounts a little bit for Fri night-Sat, but a full perusal of the 12z data is needed to assess trends with the upcoming storm. 730am... minor update to current conditions. Fog has lifted along all but the immediate coast. 5am... just an adjustment to the rain as the showers are now almost off shore. Fog is beginning to dissipate along the Vermont border as the low moves out. As of 3am, very damp and foggy conditions across Maine and New Hampshire. Temperatures are in the mid 30s across the region with dewpoints similar. With most of the region still covered in snow this relatively warmer air has resulted in patches of dense fog. This fog will dissipate in the early morning with the morning sun and developing drier flow. A low center moving northeast through the Gulf of Maine today will bring showers to coastal Maine and New Hampshire through mid morning. As the rain departs northwesterly flow will develop brining drier conditions. Clouds will slowly clear in the south. In the mountains a few upslope showers will develop.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/... High pressure will build in for tonight and Thursday. High temperatures will return to the mid 40s south to upper 30s north with mostly sunny skies and light winds. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... Still some uncertainty with upcoming storm system at the end of this week in terms of snowfall projections. Canadian high pressure will remain entrenched over the forecast area on Thursday. It will gradually retreat to the north and east on Friday as low pressure exits the Ohio Valley. 00Z operational model suite and ensemble members are in better agreement tonight bringing low pressure to the New Jersey coastline Friday night where it will undergo only some modest intensification. Nevertheless, prolonged period of northeast flow and warm air advection pattern aloft may very well allow for steady precipitation Friday into Saturday. Model QPF does vary however with the Euro being the wettest at this time. Boundary layer temperatures may be an issue over southern areas are they often are in the late March and early April time frame. Used ptpye from wet bulb for the initial portion of the forecast. As the system departs on its easterly track late Saturday, a plowable snowfall is possible, mainly over interior locations away from the shoreline. Canadian high pressure will then reassert itself on Sunday as more cold air and near or slightly below normal temperatures advect into the region. This sets the stage for another possible repeat with low pressure passing by to our south during the middle of next week. Temperatures initially look a little warmer for this second event. && .AVIATION /14Z WEDNESDAY THROUGH SUNDAY/...
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Short Term...Generally MVFR through New Hampshire and towards the northwest of Maine. The low bringing all this moisture will move off shore today and expect conditions to improve to MVFR region wide by mid morning. Conditions will continue to improve into Thursday with just a chance for MVFR ceilings in snow showers near the international border. Long Term...IFR conditions developing Friday with area of LIFR over southern areas possible. These conditions will continue into Saturday as low pressure passes by to our south. Conditions improve to VFR on Sunday.
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&& .MARINE... Short Term... Generally calm waters currently. Expect winds to pick up this afternoon under northwesterly flow as the current low departs. A Small Craft Advisory has been issued beginning late this afternoon and extending through the overnight hours. There isn`t really an upper level jet to mix down any strong winds but cold advection should be enough to reach SCA even in the bays. Long Term...SCA conditions may occur Friday night into Saturday as low pressure passes by to our south. SCA conditions possible once again midweek, next week as yet another area of low pressure passes by to our south. && .TIDES/COASTAL FLOODING... A very high astronomical tide will occur early Friday morning with 11.1` expected in Portland at around 06Z. Onshore winds and seas will just be beginning to develop at this time. Northeast flow will be more pronounced during the Saturday afternoon high tide which is lower at 10.3`. Expect about a 0.5 to 1.0 storm surge at that time which would bring the storm tide to around 11.0 feet or so. With waves running 5 feet or so at the time, splash-over nomograms suggest to only expect little in the way of issues along the coastline. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...Small Craft Advisory from 5 PM this afternoon to 8 PM EDT Thursday for ANZ150>154. && $$ NEAR TERM...Ekster

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