Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 111711 AFDGYX Area Forecast Discussion National Weather Service Gray ME 1211 PM EST Tue Dec 11 2018 .SYNOPSIS... High pressure will crest across the area today before sliding offshore. A weak disturbance will cross the area tonight and early Wednesday accompanied by clouds and scattered mainly mountain snow showers. High pressure then builds across the area late Wednesday through Friday. Low pressure passes to our south Saturday,, and could bring some light rain to southern areas, with snow or rain showers in the mountains. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... noon update... Quiet day across the area although the lower clouds are hanging on over the midcoast. 9am update... Just minor changes mostly in cloud cover where a few clouds are still present across the area. 550 AM...For this ESTF update I made adjustments to near term grids to reflect the current mesonet as well as low cloud developing over extreme southeast New Hampshire and southwest Maine. Prev disc... At 07z...a 1024 millibar high was centered over northern New England. GOES infrared imagery showed clear skies at moment across the forecast area under the building surface high. The clear skies, light winds, and dry atmosphere were allowing temperatures to tumble across the area. Subzero readings were commonplace for the mountains with single numbers and lower teens above zero elsewhere. Upstream of New England...GOES water vapor imagery showed a strong shortwave and associated 1010 millibar surface low over the upper Great Lakes. For today...the high will crest across the area this morning before retreating offshore. A sunny but cold start with temperatures rebounding to the 20s and lower 30s by afternoon. Clouds will arrive late today across northern and western areas ahead of the Great Lakes disturbance. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/... The shortwave and weak surface low cross the region tonight accompanied by a band of clouds. The system is moisture starved and any snow shower activity and light accumulations should be confined to the higher terrain with its passage. One caveat is the available short range model suite points to a weak surface low and trough forming somewhere near the Maine mid coast region early tonight. This weak feature could produce a few snow showers and light accumulation along the immediate Maine mid coast and islands overnight. By Wednesday...any lingering clouds quickly exit the region as high pressure builds in from the north and west. Highs will be in the 20s and lower 30s...but a gusty northwest wind will make it feel a good 5 to 10 degrees colder. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... I don`t have a lot of confidence in the long range models, beyond Friday at least, as they will be dealing with several weak closed systems at 500 MB that become separated from the stronger nrn stream flow. Still, the overall trend across NOAM of the coldest receding toward the Arctic and Siberia still holds, which will mean a warming trend for the most part beginning Friday and possibly extending into at least early next week. While we may not get significantly above normal, it does look like we stay normal to above thru this period. Still, we start off cold Wed night. Should see good rad cooling especially in inland valleys, although there may be enough N flow to prevent full scale rad cooling closer to the coast. Lows will like range from -10 to zero in the mtns, single digits most other inland areas, to around 10 above near the coast and in urban areas of srn NH. Thu should be our last below normal day day for a while, with mainly sunny skies. Light winds will prevent much mixing however and highs will range from the mid 20s to low 30s N-S. Will likely see some mid to high clouds move in for Thu night as WAA begins aloft, and lows will generally be in the 10-20 range. The flow shifts to SW on Friday and will like see a lot of cirrus, but not enough to block the sun completely, so p/sunny sounds good. Highs will range from the mid 30s N to low 40s in the S. By FRiday night, will see 500 MB closed low over the deep south, with a deepening trough trough in the nrn stream diving SE across the great lakes. The interaction of these two system will determine whether we get precip and how much. The 00Z op GFS soln of bringing the closed low poleward to our west and then having sit over the NE CONUS seems to favor the closed low a little too much as the dominant system, given the strong nrn stream flow, so leaning toward the 00Z Euro at this point, which does not phase with closed low, but give it a little tug northward and elongates a bit. This should be enough to pull some warmth and moisture northward and allow for some mid lvl interaction between the systems, produce some light precip late Fri night into Saturday. Mostly this will be rain in srn NH and along the ME coast, but could start as a bit snow further inland, although there should be enough warm air that it turns to rain in all but the far nrn zones. But, here, the QPF is lowers, and precip may only amt to a few showers. Highs Sat will be in the mid 30s to mid 40s N to S. Leaning toward the Euro for the rest of the forecast, which will move precip out by Sat night, with fair conds Sun-Mon and highs in the low 30s to low 40s, which is normal or slightly above. && .AVIATION /17Z TUESDAY THROUGH SATURDAY/... Short Term /Through Wednesday/...Mainly VFR. Sct MVFR between 04 and 10z Wed in mtn -shsn. Lcl MVFR possible Between 02z and 08z Wed vcnty of KRKD in -shsn. Gusty northerly sfc wind to 25 kt developing during the day Wed. Long Term...VFR Wed night through Fri. Some flight restrictions expected late Fri night into Sat in low clouds and light rain. && .MARINE... Short Term /Through Wednesday/...Quiet into tonight under high pressure with winds and seas below SCA thresholds. Gusty NW winds develop Wednesday as an ocean low passes well to our east. SCA wind gusts and seas are likely to develop outside the bays at that time. Long Term...Wind diminish Wed evening, and should stay below SCA levels through Sat, although SCA, and possibly gales may be needed Sat night or Sunday. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$ SYNOPSIS... NEAR TERM...Curtis SHORT TERM... LONG TERM... AVIATION... MARINE... is the U.S. government's official web portal to all federal, state and local government web resources and services.