Area Forecast Discussion
Issued by NWS Portland, ME

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028 FXUS61 KGYX 290145 AAB AFDGYX Area Forecast Discussion...UPDATED National Weather Service Gray ME 945 PM EDT Wed Sep 28 2016 .SYNOPSIS... Canadian high pressure will continue to build into the region from the north through Thursday. The high will remain parked to our north while low pressure over the midwest drifts slowly north and east. Moisture from this system may spread into southern areas Friday. The best chance of rain will be this weekend when a large upper level low pressure system over the Great Lakes lifts to the north, and may spread rain into New England. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
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Update...Some minor tweaks to sky and temp grids to account for latest observational trends. Areas of clouds persist at this hour...mainly aided by upslope Ely flow. But drier air continues to feed in from the NE and dewpoints are beginning to fall. Some scattering out of clouds has already occurred across coastal Wrn ME and parts of Srn NH. Clouds should continue to erode gradually thru the night. Temps were adjusted the most in the near term under the clear areas...where radiational cooling has sped up the temp drop. Previous discussion...A strong ridge of high pressure to the north and east of Maine in the Canadian Maritimes will continue to funnel down dry air in the lower levels of the atmosphere tonight. Meanwhile, low pressure over the Ohio River Valley will remain relatively stationary through the night. This will allow for varying amounts of cloudiness with the driest air over eastern sections and the deepest moisture over far southern portions of the forecast area. Areas that do remain mainly clear overnight, mainly over northern and eastern locations may have the potential for some patchy fog under light winds. With some cold air advection from the northeast, as well as differentiating cloud cover, expect a wide range in overnight lows tonight. 30s will be the rule in the mountains with 40s elsewhere.
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&& .SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/... The surface low pressure system associated with a large upper level low will gradually shift east, with a coastal low along the Carolinas by late Thursday night. Mesoscale models suggest dry conditions Thursday along with sunshine for the northern 2/3 of the forecast area. Thereafter, clouds begin to re-advance northward as a northeasterly flow gradually veers to the east with time. Mesoscale models suggest some moisture beginning to reach coastal locations by late Thursday night. Will introduce low chance pops for late in the period. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... High impact weather: None Overview: The forecast period begins with a cut off low over the south eastern United States which lingers through early next week before being reabsorbed into the main flow. As is often the case with cutoffs, confidence is generally low as to when the low will dissolve as a number of high amplitude ridges remain in place across the northern hemisphere preventing forward progression in the pattern. The good news is that despite the variability in the low center through the weekend, northern new england will remain on the periphery of the system allowing for just a chance for showers and storms. Friday:The cut off low to our south will keep clouds and a chance of showers across southern New England and as far north as the southern portion of New Hampshire. Saturday: Clouds and showers will creep northward through the day on Saturday as the upper level low cuts off. Along the coast, onshore flow may result is some fog/drizzle/low stratus. Sunday: Inland locations will see an improvement in conditions on Sunday as high pressure nudging in from New Brunswick keeps the showers at bay everywhere except the4 immediate coastline where onshore flow continues. Monday - Tuesday: By the start of next week the cut off low tries to get absorbed back into the hemispheric flow. Here the uncertainty increases with deterministic and ensemble members showing a wide split in the timing and strength. With low confidence have opted to go with a blend for the extended... with a chance of showers through out the time period. Expect we will see a period of precipitation as the disturbance moves over us and off to the east but timing is hard to pin down at this point. Wednesday and beyond: Tropical season is still in full swing so a sideways glace at the tropics is always appropriate however the high amplitude flow, large ensemble spreads, and low predictability of the atmosphere in general means that any of the potential tropical systems depicted in deterministic guidance for late next week should be taken with a healthy dose of skepticism. && .AVIATION /02Z THURSDAY THROUGH MONDAY/... Short Term...Variable conditions through Thursday with VFR conditions over central and mountain areas with mainly MVFR conditions over southernmost areas. Some overnight and early morning valley fog til 13z will allow for lcl IFR conditions. Long Term... Conditions will being with VFR on Friday. Coastal sites PWM/RKD/PSM will see ceilings return to IFR by early morning Saturday and stay below 1000ft through the day with periods of drizzle in onshore flow. intermittent IFR will continue along the4 coast through Sunday. Sunday afternoon showers will move inland and north bringing MVFR to LEB and HIE. && .MARINE... Short Term...Strengthening Northeast flow will bring SCA conditions outside the bays through Thursday. Long Term... Generally light flow with weak high pressure over the region through the weekend will keep winds and seas below SCA. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...Small Craft Advisory until 9 PM EDT Thursday for ANZ150-152- 154. && $$ NEAR TERM...Legro is the U.S. government's official web portal to all federal, state and local government web resources and services.