Area Forecast Discussion
Issued by NWS Portland, ME

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KGYX 200054 AFDGYX Area Forecast Discussion National Weather Service Gray ME 754 PM EST Fri Jan 19 2018 .SYNOPSIS... A weak ridge of high pressure will build into the region today with temperatures a bit warmer than yesterday. A milder flow and above normal temperatures follow for the upcoming weekend. A storm system moving into the Great Lakes will bring wintry precipitation Monday into Tuesday with temperatures warming. A cold front Tuesday night brings colder air back into the region. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
-- Changed Discussion --
700 PM Update... Sharp temperature inversion over the region this evening keeping low level moisture trapped over the area and will be slow to clear overnight. Increasing southwesterly boundary layer winds beginning to push this moisture out of southwest New England and this trend will continue through midnight and the early morning hours with clearing from southwest to northeast. High clouds pushing into the region from the northwest will be around overnight and through the first half of Saturday. Some light returns on radar showing up across southern Quebec in weak over-running with surface obs showing scattered snow showers. HRRR bringing a brief period of snow showers through northern zones after midnight which may produce a quick dusting in places but nothing too impactful. Have made a few tweaks to temps/tds but temps showing little change and should be steady or slowly rising overnight. No other changes to current forecast attm. Prev Disc... Weak short wave that brought snow showers to the north earlier today has moved offshore and will be replaced with milder WNW flow aloft. Cloudy skies prevail this afternoon with 20s and 30s across the region. Warmer temperatures are in place to the SW over PA and NJ where stronger southerly winds were in place in the vicinity of a forming surface trough. To the north, low pressure was traversing through Ontario Province...and this may trigger a few light snow showers along the international border overnight. Weak short wave that brought snow showers to the north earlier today has moved offshore and will be replaced with milder WNW flow aloft. Overnight lows will drop into the lower 20s north to mid 20s south before rising as a non-diurnal temperature trend is expected with warm air advection regime building in.
-- End Changed Discussion --
&& .SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...
-- Changed Discussion --
The morning will be followed by a weak cold front and modest cold air advection. Nevertheless, expect some melting to occur with readings in the 30s in the north to the mid 40s/near 50 in the south. There will be a continued threat for scattered snow showers in the mountains. This will mainly be across the northwest facing upslope regions of the higher terrain. Saturday night colder air will filter in to the north with temperatures dropping into the teens...elsewhere we`ll see lows in the 20s.
-- End Changed Discussion --
&& .LONG TERM /SUNDAY THROUGH FRIDAY/...
-- Changed Discussion --
Other than the overall theme of milder than normal in the extended...focus is mainly on next precip event. Trof is forecast to move onshore across the Wrn CONUS by tomorrow and track across the country with broad Sly flow ahead of it. At the same time high pressure is forecast to build across Quebec just ahead of the approaching storm. This general evolution is supported by ensemble guidance...with differences in positioning but consistent timing. The high pressure building in N of the approaching low, and positioning off to the NE is favorable for colder surface temps than currently forecast by NWP. I continued the trend of undercutting guidance for the Tue high temp with non-diurnal trend of slow warming Mon night. This brings a mixed bag of precip into play...especially Tue. Snow, becoming sleet, freezing rain, and even rain is all on the table. That being said. regional RAOBs have not yet had a chance to sample this wave over the Pacific, and that may change model guidance Sat and especially Sat evening. The GEFS and ECMWF EPS remain at odds regarding the location of that high pressure...which will be critical to ptype forecasts. Clustering of ensemble members hints that a S/WV trof that amplifies sooner over the Wrn CONUS tends to favor the colder solutions by the time it reaches the Northeast...possibly due to WAA processes having maxed out well to our W rather than nearby. So for I see no reason to deviate significantly from the previous forecast...which seemed reasonable. Beyond that event, high pressure builds back in with return flow gradually moderating temps upward thru the end of the week.
-- End Changed Discussion --
&& .AVIATION /01Z SATURDAY THROUGH WEDNESDAY/... Short Term...Mainly VFR conditions across the region, however northernmost regions such as HIE and HIE will likely have a period of MVFR conditions in lower stratus and -SHSN. Gusty SW winds will develop Saturday. Long Term...Generally VFR conditions set to prevail to end the weekend. High pressure will build N of the area while the next storm system approaches from the W. High is well positioned to keep cooler solutions in play...but widespread IFR conditions are looking fairly likely. All ptypes are a possibility...with SN at the onset Mon night...transitioning from SW to NE. Some coastal terminals...even as far N as MHT...may change to RA before tapering off Tue afternoon/evening. Will have to monitor LLWS as well...with light to NE surface winds...and SW flow aloft across Srn parts of the forecast area. Wly flow dominates Wed...with MVFR clouds and SHSN in the mtns near HIE lingering. && .MARINE... Short Term...Winds and seas will increase late tonight and Saturday. There will be a period of SCAs, especially out over the outer waters. Winds may approach gales, but we will only see 2-3 hours of them over the far outer waters. Therefore feel SCAs were more appropriate. Long Term...Winds and seas will increase ahead of the next approaching storm system Mon night into Tue. Gale force wind gusts are possible outside the bays...with SCA conditions likely continuing into the end of the week. && .HYDROLOGY... Several points along area rivers remain at high water levels...including the Kennebec River at Augusta. Please see the Flood Potential Outlook (ESFGYX) for more information about the flooding threat. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...Small Craft Advisory from 6 AM to 6 PM EST Saturday for ANZ153. Small Craft Advisory from 1 AM to 6 PM EST Saturday for ANZ150>152-154. && $$

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.