Area Forecast Discussion
Issued by NWS Caribou, ME
Issued by NWS Caribou, ME
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365 FXUS61 KCAR 271509 AFDCAR Area Forecast Discussion National Weather Service Caribou ME 1109 AM EDT Thu Jun 27 2024 .SYNOPSIS... Low pressure will exit across the Maritimes this afternoon drawing a cold front across the region. High pressure will cross the region Friday. A cold front will approach later Saturday, then cross the region Sunday. High pressure will build toward the region Monday. && .NEAR TERM /THROUGH TONIGHT/... Update... Low pressure will exit across the Maritimes through the afternoon, drawing a cold front south across the forecast area. An upper level trof will also approach, from the west, later this afternoon. The steady rain has now exited across the Maritimes with the surface low. Expect scattered/numerous showers across northern areas through the afternoon, with scattered showers Downeast. Temperatures will cool aloft through the afternoon with the approaching upper level trof, leading to steepening lapse rates. Increased instability with the steepening lapse rates, along with the cold front, will also support the possibility of isolated thunderstorms this afternoon into the evening. High temperatures today will range from the mid 60s to around 70 north, to around 70 to the mid 70s Downeast. Have updated to adjust for current conditions along with expected afternoon temperatures, clouds and shower/thunderstorm chances. Previous Discussion... An upper level trough will propagate towards the area today. A powerful upper jet precedes the upper trough this afternoon. This means strong deep layer shear for storm organization. However, instability remains in short supply due to residual cloud cover left from the disturbance this morning. A cap near H6 will have to be overcome to generate enough CAPE for thunderstorms. This has a chance of happening Downeast this afternoon with the front as cooler air aloft arrives with the upper trough. Any storms would be where dew points remain in the 60s ahead of the front. Among the models advertising instability, and not all CAMS are, Downeast appears the most likely to have any strong thunderstorms. Given the shear, SBCAPE values of just 1000 J/kg or less could be troublesome. Low freezing levels make small hail a possible threat if sufficient CAPE can be realized. A separate area with the threat of late afternoon and evening thunderstorms will be in northern Aroostook County as the upper level trough brings steeper mid level lapse rates. CAPE is nominal for thunderstorms and no severe storms can be anticipated in northern Aroostook County. The cold air with the upper trough will drop the freezing level towards H8, so small hail or graupel is possible. Showers will linger in northern Aroostook County well into the night. Cold advection will drop lows tonight to as low as the upper 30s in portions of the North Woods. Elsewhere, upper 40s to lower 50s are forecast. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... High pressure returns to the region on Friday. This will bring clear skies and cool temps in the upper 60s. By Friday night, the warm front from the approaching low pressure system should stretch across the north. This will increase clouds throughout the night, as well as keep temps from falling past the low 50s. By Saturday, the warm front should stretch across Quebec and NB well to the north, putting the region in the S flow of the front. By later in the afternoon, rain showers should enter from the west and spread east throughout the evening and into Saturday night. Temps should be much closer to normal. By Saturday night, rain is expected to spread across the entire region, with most of the rainfall from the system coming during the night. Patchy fog is expected to develop with the rain. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... The low pressure system to the north is expected to swing a cold front through the region on Sunday. Models are in better agreement with the timing of the cold front, with the front exiting Sunday night. The concern for Sunday afternoon will be the thunderstorm potential. The CAPE environment is expected to set up ahead of the front with a thin band of >1000 J/kg across Downeast. The Euro shows the CAPE spreading further north. The bulk shear is expected to be the driving force of the thunderstorms with a moist column to produce heavy rainfall. Better details will come with the system moving into range of the CAMS. High pressure should move in for the rest of the week, making for inactive weather and temps slightly above normal. && .AVIATION /15Z THURSDAY THROUGH MONDAY/... NEAR TERM: IFR possible along the Downeast coast through late morning. Otherwise, expect generally VFR/MVFR this afternoon into the evening with scattered to numerous showers. Variable conditions with any isolated thunderstorms this afternoon into the evening. Otherwise, VFR tonight. Variable winds 5 to 10 knots, becoming west/northwest today. West/northwest winds around 10 knots tonight. SHORT TERM: Friday through Saturday...VFR. Northwest winds on Friday at 5 to 10 will become southerly on Saturday at 10 to 15 kt. Saturday night into early Sunday morning...IFR cigs and tempo IFR vis in rain. Isolated embedded thunderstorms. LLWS likely. South winds 10 to 20 kt. Sunday...IFR becoming MVFR tempo VFR. Afternoon thunderstorms likely. Southwest winds 10 to 15 kt becoming NW late afternoon. Sunday night and Monday...Conditions rapidly improving to VFR. NW winds 10 to 15 kts. && .MARINE... NEAR TERM: Winds/seas below small craft advisory levels this afternoon through tonight. Scattered showers into the evening. Isolated afternoon thunderstorms are also possible. Patchy fog also persists into the evening. SHORT TERM: Winds increasing to high end SCA Saturday through Sunday. Seas building to 6 feet by Sunday, subsiding by early Monday. Potential for fog Thursday night and again Saturday night into Sunday. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...None. MARINE...None. && $$ Near Term...Norcross/MCW Short Term...LaFlash Long Term...LaFlash Aviation...Norcross/LaFlash Marine...Norcross/LaFlash