Area Forecast Discussion
Issued by NWS Caribou, ME
Issued by NWS Caribou, ME
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069 FXUS61 KCAR 122323 AFDCAR Area Forecast Discussion National Weather Service Caribou ME 723 PM EDT Sun May 12 2024 .SYNOPSIS... High pressure remains across the region tonight, then exits across the Maritimes Monday. A storm system approaches from the west Monday night and Tuesday, crosses the region Wednesday, then exits across the Maritimes Thursday. High pressure builds in Friday. && .NEAR TERM /THROUGH MONDAY/... 7:23 PM Update: Update to the aviation section below for the issuance of the 00z Tafs. Previous discussions: Water vapor satellite shows a mid level low centered along the NH coast early this evening. The low is expected to slowly move east tonight and should be along or near the southern coast of Nova Scotia by Monday morning. Moisture rotating around the low is producing a few showers in southern Maine, but nothing showing up on area radar across northern and eastern Maine. Visible satellite pictures and web cameras show a fair amount of cumulus across the area. As we lose the daytime heating this cumulus is expected to gradually break up and dissipate tonight. The low levels of the atmosphere are quite dry with dew points well down into the 20s across northern areas, and there is the potential that if the clouds fully clear that valleys could get down to around freezing. Will hold off on any adjustments to the temperatures with this update, but may need to lower them a bit in the northern valleys and will monitor the trends this evening. No changes are planned to the forecast at this time other than refreshing with the latest observations. Previous discussion from 3:20 PM: A 500 mb trof slides east through the Gulf of Maine toward Nova Scotia overnight. At the surface, high pressure extending from the Canadian Maritimes to the mid atlantic, will move east. Expect partly cloudy and dry weather tonight along with light wind. Lows tonight will range from the mid to upper 30s north, to near 40 for Bangor and Downeast. The fair weather pattern continues through most of the day on Monday. The 500 mb trof axis continues to slide east through the Canadian Maritimes and this allows ridging to build in later in the day. Surface high will continue to drift out into the western atlantic with light southerly flow in place across the region. Expect a dry day with partly sunny skies and highs in the mid to upper 60s away from the coast. && .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/... Upr lvl ridge axis will be over the CWA Mon evening with longwave trof extending from James Bay down into the srn Plains. Trof will creep eastward Monday night with a tendency to flatten the ridge/shove it into ern Canada which allows return flow to kick in, leading to an increase in dewpoints along with showers moving in a after midnight. Warm advection with the approach of a warm front will bring fog to western and coastal regions late Monday night and with fog and cloudy skies mins will be above normal in the middle 40s by Tuesday morning. Warm front will lift through on Tuesday with chances for rain increasing in the afternoon. Warm advection will be competing with showers and rain with highs topping out just below normal. Rainfall amounts on Tuesday will range from a few hundredths of an inch right along the coast to around 0.25 inches over portions of the North Woods. Waves of low pressure will ride up along quasi-stationary boundary on Tuesday night and highest rainfall totals are dependent on where boundary sets up. 12z GFS has it setting up along the coast while NAM/CMC/EC keep it fairly stationary over nrn zones. Given this uncertainty have mentioned likely rain across the north early and slowly dropping toward the coast late with amounts on average around 0.20 inches. For Wednesday have continued with idea of cooler temps acrs the northwest with rain likely south of this area. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... By Wednesday night CWA will still be in upr lvl trof axis as stronger wave looks to be in the vicinity of the waters. This will result in showers becoming more scattered acrs the north overnight with still a good chance for showers over southern areas. During the day will see precip very slowly wind down from north to south with temps well above normal, close to 70 in the St. John Valley to near 60 along the coast with more of an along-shore wind remaining. Depending on which model you look at, Thursday night Friday could be dry or maybe a shower or two. EC/CMC and their ensembles indicate H5 ridge will be over CWA while GFS and it/s ensemble indicates s/wv approaching from the west and this may be enough to kick off afternoon showers with diurnal heating, especially with temps in the lower 70s hitting convective temperatures. For this reason have went with NBM pops and a slight chance for showers Friday afternoon. Active pattern looks to continue into next weekend with chances for showers along with above normal temperatures, mainly due to warmer low temperatures. && .AVIATION /00Z MONDAY THROUGH FRIDAY/... NEAR TERM: High confidence VFR at the Aroostook County terminals through Monday, although there is a very small chance of late night/early morning fog patches at KPQI or KHUL, but chance is too low to mention in the 00z Tafs. Medium to high confidence of VFR at KBGR and KBHB through Monday. Small chance (less than 15%) of patchy fog or low cloud late tonight/early Monday morning, but looking at upstream satellite pictures and latest guidance it would indicate that the chance is too low to mention in the 00z Tafs. Light and variable wind tonight will become south and increase to 5 to 10 knots Monday afternoon, except 10 to 15 knots at KBHB owing to the development of a sea breeze. SHORT TERM: Monday night...VFR early becoming MVFR after midnight in light showers and possible IFR late over Downeast terminals in patchy fog. S 5-15kts. Tuesday-Wednesday night...MVFR/IFR in rain and patchy/areas of fog at times. S 5-15kts with gust to near 25kts on Tuesday, then S 5-10kts Tuesday night/Wednesday becoming N 5-10kts late Wednesday night over Aroostook terminals. Thursday-Friday...Mainly VFR with ocnl MVFR cigs. NNE 5-10kts Aroostook terminals, ESE 5-10kts Downeast Thursday/Thursday evening, then ESE 5-15kts Friday. && .MARINE... NEAR TERM: Winds/seas remain below SCA levels through Monday. SHORT TERM: Winds approach SCA levels over the outer waters Tuesday and Tuesday night before diminishing below 20kts through the end of the week. Seas approach 5ft Tuesday into Wednesday morning before dropping under SCA levels through Thursday morning. Seas may approach SCA levels again Thursday into Friday morning. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...None. MARINE...None. && $$ Near Term...CB/TWD Short Term...Buster Long Term...Buster Aviation...CB/TWD/Buster Marine...CB/TWD/Buster