FXUS61 KCAR 310439 AFDCAR Area Forecast Discussion National Weather Service Caribou ME 1139 PM EST Mon Jan 30 2023 .SYNOPSIS... Weak low pressure will cross the Gulf of Maine overnight. High pressure builds across the region later Tuesday into Wednesday night. Low pressure crosses the region Thursday then exits across the Maritimes Friday drawing a strong Arctic cold front across the region. High pressure builds toward the region Saturday. && .NEAR TERM /THROUGH TUESDAY/... 11:35 PM Update...Light snow covers the entire area so increased pops, and made snow light snow over the north. Snow should taper off later in the overnight period as this weak shortwave passes to our east. Temps looks good this hour. Previous discussion: A weak area of low pressure will track across the Gulf of Maine tonight, with a trof extending north to another weak low crossing northern Maine. An upper level disturbance will also begin to cross the region overnight. Expect light snow across the region tonight, tapering to snow showers late. Snow accumulations will generally range from 1 to 2 inches across most of the region, though localized accumulations up to 3 inches are possible across both northern and Downeast areas. Isolated/scattered snow showers could linger early Tuesday with the exiting systems. Cloud cover will then decrease during the afternoon with building high pressure. Low temperatures tonight will generally range through the single digits above zero north, to the upper teens to around 20 interior Downeast with lower 20s along the Downeast coast. High temperatures Tuesday will range from around 10 to around 15 north, to the lower to mid 20s interior Downeast with mid 20s along the Downeast coast. && .SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/... For Tuesday night, all elements appear to be in place for the coldest night of the season across most of the area. H925 temps will be near -20C with a 1028mb surface high ridging into the CWA. This should lead to calm winds, clear skies and a very steep and shallow radiation inversion. As such, most guidance appears too optimistic and have leaned towards a much colder solution than our previous forecast package. With the warm winter to date, bias-corrected and MOS guidance continues to look way too high. The surface high remains in place Wednesday with winds shifting more southwesterly ahead of another arctic boundary to the north. Given the cold air mass in place, little modification will occur and highs will still be in the mid teens north and lower 20s for Bangor and Downeast. Wednesday night presents another opportunity for strong radiational cooling and steep shallow inversion as winds move towards calm again. Once again, guidance seems too warm. The reinforcing arctic boundary to the north will stall as a much more powerful arctic front organizes in northern Ontario and Quebec on Thursday. Thursday will be a bit milder as a warm front sweeps through with near seasonable temps. Snow showers will be possible in North Woods, mostly in the afternoon. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... ***Record Arctic Outbreak Friday and Saturday*** The severity of the cold air descending on northern and eastern Maine on Friday and Saturday cannot be overemphasized. It's outside of model climate norms. The coldest air currently in the Northern Hemisphere will be moving over the area Friday and Saturday as measured by 925mb temps. 850mb temps may be the coldest since 1982. We expect wind chills to drop as low as 45 to 55 below zero across the area later Friday night. As a reference, Caribou has not measured a wind chill of 50 below (F) or colder since 1988. -54F is the coldest ever recorded. The grand ensemble model averages were predicting minus 49F wind chills at Caribou and even the 95th percentile was at minus 40F (on the warm side of statistical outcomes). Wind chill advisories and warnings will be needed by Friday morning and will continue through Saturday. Confidence is very high on this event. The wind chills will create extremely hazardous conditions for anyone exposed to the cold. Frostbite can occur in just 5 minutes at these wind chills. While the wind gusts will top out around 45 mph and do not suggest a lot of power outages, any power outages could be particularly impactful given the cold. Besides the brutal cold, the other threat will be blowing snow, mostly in Aroostook County. There is a fresh coating of powdery snow that will be blown around by winds gusting to 40 mph. In addition, low level instability and St Lawrence streamers will add snow showers to the equation on Friday. The warm winter to date and strength of this cold air advection should maximize transport of St Lawrence moisture southward into Aroostook County. The net result will be white-outs in the open agricultural areas of Aroostook County for key roads such as US Route 1 and 1A. This will be the first widespread blowing snow event of the winter. It will develop Friday and continue Friday night. Travel could be extremely hazardous in Aroostook County. The arctic front crosses the area early Friday morning. Highs on Friday will occur before daybreak for much of the area. By Saturday, highs will remain below zero except on the coast where low single digits may be realized. These will be record low high temperatures. Bitterly cold subzero temps renew Saturday evening as winds finally decrease, but do not believe there will be a lot of radiational cooling due to a return flow and increasing high clouds. Light warm frontal snow seems likely for Sunday with moderating temperatures as a clipper moves through the area. Expect another arctic front Monday, but the magnitude of cold air will not be anything like Friday and Saturday, but do expect another round of subzero temps in northern zones by Monday night. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... NEAR TERM: Across northern areas, MVFR/IFR with occasional LIFR through early morning with light snow, then MVFR late with snow tapering to snow showers. VFR/MVFR Tuesday morning with isolated to scattered snow showers. VFR Tuesday afternoon. Across Downeast areas, VFR/MVFR with snow developing. MVFR/IFR, occasional LIFR, overnight with light snow. VFR/MVFR Tuesday morning with isolated to scattered snow showers. VFR Tuesday afternoon. Variable winds 5 to 10 knots tonight. West/northwest winds around 10 knots, increasing to 10 to 20 knots with gusts up to around 25 knots Tuesday. SHORT TERM: Tuesday night into Thursday morning...Predominantly VFR with light winds. Thursday afternoon...VFR tempo IFR in snowshowers north of GNR and HUL. Thursday night...Chance of MVFR cigs and tempo IFR in snowshowers, mostly north of HUL and GNR. Friday and Friday night...Tempo IFR in snowshowers and blowing snow north of HUL. Mostly VFR for BGR and BHB. Northwest winds gusting to 35 kt. Saturday...Tempo IFR in blowing snow for FVE and CAR. Otherwise predominantly VFR. Northwest winds gusting to 30 kt. && .MARINE... NEAR TERM: Winds/seas below small craft advisory levels tonight. A Small Craft Advisory is then in effect starting Tuesday morning. Snow tonight. Scattered snow showers Tuesday morning. Light freezing spray Tuesday afternoon. SHORT TERM: SCA conditions continue Tuesday night with light freezing spray. SCA conditions return Thursday afternoon and ramp up into a strong gale for Thursday night into late Saturday. Moderate to heavy freezing spray can be expected Friday through Saturday with an advisory or warning likely. && .CLIMATE... The coldest air mass so far this winter is expected at the end of the week. Although record low temperatures do not look likely at this time due to wind, record low high temperatures are possible across the area on Saturday. Here are the forecast highs on Saturday, 2/5 along with the record low highs: Caribou: -8F, record -4F, in 1963 Houlton: -7F, record -2F, in 1963 Millinocket: -7F, record 0F, in 1963 Bangor: -2, record +4, in 1963 It has been over 5 years since Bangor has had a day where the high temperature failed to reach zero. The last sub-zero high was -1F on January 6, 2018. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...None. MARINE...Small Craft Advisory from 10 AM Tuesday to 1 AM EST Wednesday for ANZ050>052. && $$ Near Term...CB/Norcross/Bloomer Short Term...MCW Long Term...MCW Aviation...CB/Norcross/MCW Marine...CB/Norcross/MCW Climate...CB