Area Forecast Discussion
Issued by NWS Caribou, ME
Issued by NWS Caribou, ME
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210 FXUS61 KCAR 271051 AFDCAR Area Forecast Discussion National Weather Service Caribou ME 651 AM EDT Thu Jun 27 2024 .SYNOPSIS... A cold front will cross the region today while low pressure moves along the front early this morning. 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/... 645 am update...The steady rain with the first shortwave is exiting the region in the next couple of hours as expected. Clouds will linger and limit instability. Still might see a thunderstorm or two develop Downeast later in the afternoon and have maintained isolated coverage in forecast. Previous discussion... An initial shortwave is quickly moving through the area early this morning with a slug of locally heavy rain and isolated thunderstorms. The upper level trough axis remains in the Great Lakes region early this morning. Cyclogenesis is currently occurring along the stalled frontal boundary in the forecast area. This surface low will quickly eject in the Maritimes this morning, but the frontal boundary will remain across the area this afternoon. The upper level trough will propagate towards the area today while the stalled frontal boundary acts as a trigger for scattered showers and isolated thunderstorms. 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. Highs today will reach the mid 70s ahead of the front. These temps will occur pretty close to the coast with the southwest flow preventing a strong onshore flow. Further north in Aroostook County, highs will only be in the upper 60s due to cloud cover and cold air advection behind the front. 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 /12Z THURSDAY THROUGH MONDAY/... NEAR TERM: A period of IFR vis and cigs is likely early this morning as locally heavy rain moves across the area. MVFR cigs are expected to hang on through the morning. These cigs will lift to VFR at BGR and BHB first...and then further north during the afternoon. Isolated thunderstorms are possible early this morning from BGR southward to the coast. Isolated thunderstorms return this afternoon into the early evening. Another period of MVFR in showers is forecast for CAR and FVE later this evening while the remainder of the area stays VFR through the night. 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: Longer period south swell has prompted a Small Craft Advisory into early this morning for Eastport to Schoodic Point, but expect seas to diminish this morning and do not anticipate extending the advisory past expiration at 6 am. The south swell will continue to slowly diminish today into tonight. Southwest winds under 15 kt continue today, but shift to northwest tonight. 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...MCW Short Term...LaFlash Long Term...LaFlash Aviation...MCW/LaFlash Marine...MCW/LaFlash