Area Forecast Discussion
Issued by NWS Caribou, ME
Issued by NWS Caribou, ME
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139 FXUS61 KCAR 262215 AFDCAR Area Forecast Discussion National Weather Service Caribou ME 615 PM EDT Wed Jun 26 2024 .SYNOPSIS... A cold front will cross the region tonight through Thursday while low pressure moves along the front. 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 THURSDAY/... 6:15 PM Update: Isolated showers, mainly across parts of Aroostook County should dissipate over the next hour or two with the loss of daytime heating. A widespread rain is still expected to develop later tonight, mainly after midnight as a cold front moves into the area and low pressure develops along the front. Other than removing thunder for this evening, no significant changes are planned at this time. Previous discussion: A cold front will begin to cross the region tonight. A disturbance approaching from the west will help support the development of surface low pressure along the front. The front will slow across the region overnight into Thursday while the surface low moves along the front. The cold front will then slowly settle south across the forecast area later Thursday in the wake of the low. Isolated/scattered showers, possibly an isolated thunderstorm, will occur early tonight. Rain will then develop overnight with the surface low and approaching upper level disturbance. Rain will persist early Thursday. Isolated thunderstorms are also possible with the rain overnight into Thursday morning. Patchy fog is also expected overnight into Thursday morning. Precipitation will then taper to showers in the wake of the exiting low Thursday afternoon. An upper level trof approaches later Thursday with cooling temperatures aloft supporting steepening lapse rates. Increased instability with the steepening lapse rates, along with the cold front, will also support the possibility of isolated thunderstorms Thursday afternoon along with the showers. The heaviest rains are expected across Downeast areas overnight into Thursday morning. Rainfall totals overnight through Thursday are generally expected to range from up to around an inch Downeast, with a half to three quarters of an inch across northern areas. However, locally heavier totals are possible. Low temperatures tonight will range from the upper 50s to around 60 across the forecast area. High temperatures Thursday will range from the upper 60s to around 70 north, to around 70 to the lower 70s Downeast. && .SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/... Thursday night, the main upper level trough behind the cold front will drop south, bringing cooler temperatures across the region. 850 hPa temperatures will drop to an unseasonably cool 2 to 4 degrees Celsius, and surface temperatures will also drop accordingly. A batch of post-frontal showers is possible late Thursday night ahead of the upper level trough, but these are expected to mostly be confined to the northern portion of the forecast area, where the greatest instability remains. On Friday, ridging will move in, bringing quiet weather and a slight warming for the temperatures aloft. This will keep the lows Friday night from falling quite as low as Thursday night, but overnight temperatures will still be unseasonably cool. On Saturday, a warm front will approach, bringing southwest flow and increasing humidity. Some showers may pop up ahead of the front, but the bulk of the precip is not expected until Saturday night. The main atmospheric change expected on Saturday will be a moistening of the air column, with PWATS increasing to above an inch during the day. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... Saturday night, the warm front will cross the area, raising mid-level temperatures significantly and continuing to increase PWATs. On Sunday, this will transition to a more showery regime as the cold front approaches. Timing of frontal passage is unclear due to differences between the models, but this should happen late Sunday evening. The complexity in this system is with the potential for thunderstorms and heavy rainfall. On Saturday night, it appears that a few elevated thunderstorms are possible, but with the overall warming of the mid-layers behind the warm front they do not look widespread. On Sunday, thunderstorms could be both more widespread and more severe. CAPE values will be on the increase in the warm, moist air mass ahead of the front, combined with an increase in bulk shear as well with the pre-frontal jet. The potential for heavy rainfall also exists both Saturday and Sunday, with Sunday looking slightly better ahead of the warm front. This system overall does not have a long residence time, so widespread rainfall amounts appear to be on the order of 0.5 to 0.75 inches across the forecast area. However, with a deep warm cloud layer and the potential for training, localized heavy precip cannot be ruled out. These details will have to be resolved further as we get closer in time and the event moves into the range of the CAMs. The rest of the forecast looks pretty quiet as ridging moves overhead early next week, with no notable temperature anomalies. && .AVIATION /22Z WEDNESDAY THROUGH MONDAY/... NEAR TERM: VFR/MVFR early tonight with isolated to scattered showers and isolated thunderstorms, lowering to IFR/LIFR, overnight with developing rain with isolated thunderstorms also possible. Rain possibly heavy at times late tonight Downeast. IFR/LIFR with rain and isolated thunderstorms Thursday morning. VFR/MVFR, occasional LIFR, with showers and isolated thunderstorms Thursday afternoon. Patchy fog overnight into Thursday morning. Southwest/west winds 10 to 15 knots early tonight, becoming variable 5 to 10 knots overnight. Variable winds 5 to 10 knots Thursday. SHORT TERM: Thursday night 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.* Add discussion here. && .MARINE... NEAR TERM: Winds/seas generally below small craft advisory levels tonight through Thursday. However, seas could approach small craft advisory levels along the outer edge of the waters tonight into Thursday morning. Isolated showers this evening. Rain developing along with isolated thunderstorms overnight which will persist into Thursday morning. Showers along with isolated thunderstorms Thursday afternoon. Patchy fog overnight and Thursday. 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...CB/Norcross Short Term...LF Long Term...LF Aviation...CB/Norcross/LF Marine...CB/Norcross/LF