Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 171406 AFDGYX Area Forecast Discussion National Weather Service Gray ME 906 AM EST Wed Jan 17 2018 .SYNOPSIS... Developing low pressure off the mid Atlantic coast will intensify as it moves rapidly northeast through the Gulf of Maine today. High pressure builds eastward into the region late in the week and into the weekend with a return southwest flow bringing warmer temperatures by the weekend. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 9 AM Update...Have made a few minor adjustments to PoP timing and weather for the afternoon hours based on latest trends in regional radar/sat data as well as latest mesoscale model information. Right now, the snow is light, with a break in steady accumulating snow currently ongoing across western and northernmost zones. The next weak wave is approaching from the south and should allow the radar to fill in with returns once again over the next few hours. So far we have received reports of anywhere between 2 and 5 inches of snow, so current headlines will remain unchanged through the afternoon. previously... 550 10z a 1021 millibar low was centered south of Long Island. This low continues to gradually strengthen with three hour pressure falls of between 3 and 4 millibars centered south of Cape Cod. For this ESTF update...only minor adjustments to near term grids to reflect the current mesonet in near term grids. Prev disc... At 07z...a 1023 millibar low was offshore of the DELMARVA with 3 hour pressure falls approaching three millibars noted south of Cape Cod. GOES water vapor imagery showed a shortwave impulse over the eastern Great Lakes. For today...the impulse will race east across the northeast CONUS and quickly offshore by evening. This energy will allow the offshore low to strengthen moderately as it races east-northeast across the Gulf of Maine this afternoon. UVM with shortwave and convergence with coastal front will aid in precipitation development across the area today. The models have backed off a bit on QPF...but snow ratios should still allow us to approach the 6 inch threshold across southern New Hampshire and along the Maine coastal plain with this system. THe snow will quickly wind down from west to east during the afternoon as the low and upper support quickly exit the forecast area. There is a possibility that right along the mid coast the coastal front could briefly cause the snow to mix with or change to rain early this afternoon. Otherwise this should be a straight snow event for the forecast area. The current advisory and warning areas remain the same with this package...although snow amounts were trimmed back a bit in many areas. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/... Some lingering upslope clouds and mountains now showers early...otherwise clearing tonight as the upper trough and surface low move well offshore. On Thursday...weak ridging provides a mainly sunny day. A cold front will sag southward towards the international border during the afternoon with a few clouds and perhaps a few mountain flurries. It`ll be a seasonable day with highs ranging from the mid 20s to the lower 30s across the region. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... A weak ridge of Canadian high pressure will build over the region Thursday night. This airmass will not be overly cold with only seasonably cool overnight lows mainly in the teens across the forecast area. Some clouds will move into northern New England as well, preventing significant radiational cooling. A few snow showers will be scattered about in northern areas as a fast moving short wave trough approaches the region. A warming trend will begin on Friday as a southwesterly flow develops across the Eastern United States. There will be a few snow showers within the warm air advection pattern. The atmosphere will remain relatively moisture starved however. This will limit the snow showers to the northern higher terrain. Another thaw on tap with mild temperatures expected over the weekend. Southern areas should reach into the 40s for daytime highs as a cold front remains locked just north of Maine and New Hampshire. The cold front will eventually sweep through the region by Sunday night. This will allow cool Canadian air into the region for the beginning of next week. In the meantime, model guidance suggests possibly some mixed precipitation as low pressure moves north from the Mid Atlantic region. The 00Z Euro offers the coldest solution for this next event. && .AVIATION /14Z WEDNESDAY THROUGH SUNDAY/... Short Term /through Thursday/...MVFR with areas of IFR in snow. Brief LIFR psb btw 11 and 18z in moderate to heavy snow. Aft 20z...conditions gradually improving to VFR throughout with sct MVFR in mtn -shsn. Long Term...Mainly VFR conditions across the region. Widespread ceilings and visibilities lowering in a mix of precipitation early next week as low pressure heads towards New England. && .MARINE... Short Term /through Thursday/...We`ll continue with marginal SCA seas through tonight for a combination of swell...and for wind generated waves from our passing coastal low. Long Term...Expect SCAs with a developing southwesterly flow on Saturday with possible gales along the outer waters. Gales are possible early next week with low pressure approaching from the south. && .HYDROLOGY... All rivers have now fallen below flood stage, but ice jams have frozen into place in some areas. Rivers will still need to be monitored as these jams could move without notice. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...Winter Weather Advisory until 7 PM EST this evening for MEZ012>014. Winter Storm Warning until 7 PM EST this evening for MEZ018>028. NH...Winter Weather Advisory until 4 PM EST this afternoon for NHZ003>007. Winter Storm Warning until 4 PM EST this afternoon for NHZ008>015. MARINE...Small Craft Advisory for hazardous seas until 7 AM EST Thursday for ANZ150-152-154. && $$ NEAR TERM...Ekster is the U.S. government's official web portal to all federal, state and local government web resources and services.