Area Forecast Discussion
Issued by NWS Caribou, ME

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000 FXUS61 KCAR 240111 AFDCAR Area Forecast Discussion National Weather Service Caribou ME 911 PM EDT Fri Mar 23 2018 .SYNOPSIS... High pressure builds this evening. An upper level low from northern Quebec will cross the region on Saturday. High pressure will build from the north on Sunday and crest over the area Monday into Tuesday. && .NEAR TERM /THROUGH SATURDAY/... 9:11 pm update: Mid and high clouds cover the area this evening. No significant weather is expected until Saturday when an upper low and surface trough will combine to generate snow showers. Made some adjustments to the hourly weather elements based on the 9 pm observations and satellite pictures, but nothing major as the ongoing forecast has everything well at hand. Previous discussion... For tonight, lows will drop to the upper teens north and mid to upper 20s in southern zones. Temperatures could go lower if high clouds are thinner than expected as winds will be fairly light. It is the high clouds that prompted mention of cloudiness in tonight`s forecasts. For Saturday, an inverted trough will team up with a vort max rotating around an upper low and create widespread afternoon snow showers for the entire forecast area. There`s good moisture convergence with the inverted trough...which will sweep from NE to SW across the area Saturday afternoon. Low level lapse rates will be fairly steep...especially in southern zones and there`s decent amounts of SBCAPE...for March in Maine...resulting in snow showers that could top out near H650. With the cold air aloft, the dendritic growth zone will be within these the -20C isotherm will be in the area of 8 to 9 thousand feet. The low -20C also raises the question as to whether a stray thunderstorm could develop. The snow squall parameter is flashing some of the higher numbers in quite some time. Between slow storm movements and decent PW numbers, it`s not inconceivable that a quick 2-3 inches could fall out of these snow showers...especially in the western mountains where upslope will be a factor. This means drastically reduced visibility for motorists and road conditions that could quickly deteriorate. Like summer convection, model QPF for tomorrow is not necessarily representative of what can happen at various locations. The timing of the inverted trough passage with afternoon heating is also favorable. Have bumped up pops to likely for portions of the area. Although boundary layer temperatures will be above freezing by late morning, the air aloft is so cold that precip should be in the form of snow or small graupel...with the latter more prevalent further south. && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/... Some snow showers may be ongoing at the start of the period, especially over central and western parts of the CWA. However, most models quickly clear things out by midnight. The GFS and Euro both hint at some lingering showers for Downeast and perhaps Bangor metro late night into the early morning hours Sunday, but mesoscale guidance and the global CMC showed this, so POPs were capped at slight chance at most. Skies should quickly clear from north to south during the day Sunday as the trough moves away to the south and high pressure builds in from the north. Monday will be a very nice day, with abundant sunshine and near normal temps, though it may be a bit breezy for Downeast and the Bangor region. If anything, I am concerned that my highs for Monday may be a bit on the low side given the expected sunshine, but the N to NE flow may help keep temps down a bit. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... Beautiful weather will continue to start the long-term, with Tue and Wed both being fairly warm with lighter breezes than Sun and Mon. Abundant sunshine will continue through Tuesday, but clouds may start to work in from the west during the day Wed ahead of the next system. This system, a weak front pushing through eastern North America associated with a weak shortwave 500mb trough, may bring some rain and snow showers to teh CWA Wed night into early Thu morning. Both the GFS and ECMWF show precip largely clearing the CWA by 12z, but the CMC was about 12hrs behind on timing. The POP forecast was definitely weighted toward the GFS/ECMWF solution at this time. The next system then looks to come in quickly for Fri & Fri night. There, of course, remain some differences on timing and track for this potential system, but there is good agreement among the synoptic models on the overall theme of a broader 500mb trough pushing into eastern North America accompanied by a surface low. Limited POPs to high-end chance at this point, given that it is Day 8, but if agreement continues among the models, future shifts should consider increasing to likely POPs. && .AVIATION /01Z SATURDAY THROUGH WEDNESDAY/... NEAR TERM: VFR tonight. Saturday will be mostly MVFR cigs tempo IFR...or even snow showers. SHORT TERM: Sites should quickly recover to VFR conditions Sat night into Sunday AM, but can`t rule out brief MVFR CIGs for KBGR or KBHB Sun AM if a stray snow or rain shower moves across the area. Otherwise, Sun through Tue look to feature clear skies, though KBHB may have some gusty NE winds Sun and Mon. Some higher clouds may work in across the area Wed AM, with MVFR cloud decks expected by the afternoon and evening, with an isolated rain shower not out of the question. && .MARINE... NEAR TERM: No advisories are expected during this period with light winds until late Saturday. Snow showers are possible Saturday afternoon and a few locally heavier showers are possible. SHORT TERM: Winds look to quickly come up to SCA levels Sat night and will remain there through Mon morning. Gusts may briefly touch gale force Sun morning. After consultation with GYX, decision was made to delay any marine headlines until the overnight shift. && .CLIMATE... A total of 33" of snow has been observed at Bangor, Maine so far this month. Through 3/22, this ranked as the 6th snowiest March to date at Bangor. The 8-14 day and weeks 3 & 4 outlooks from the Climate Prediction Center favor below average temperatures and above average precipitation for northern and eastern Maine. You can check their latest outlooks at && .CAR WATCHES/WARNINGS/ADVISORIES... ME...None. MARINE...None. && $$ Near Term...CB/MCW Short Term...Kredensor Long Term...Kredensor Aviation...CB/MCW/Kredensor Marine...CB/MCW/Kredensor Climate...CB is the U.S. government's official web portal to all federal, state and local government web resources and services.