Area Forecast Discussion
Issued by NWS Caribou, ME

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000 FXUS61 KCAR 120421 AFDCAR Area Forecast Discussion National Weather Service Caribou ME 1221 AM EDT Sat Aug 12 2017 .SYNOPSIS... Low pressure will track northwest of the region Saturday. A cold front will cross the region Sunday, followed by high pressure on Monday. && .NEAR TERM /THROUGH TODAY/...
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Update 12:20 AM: Have adjusted wind, temperature, and dew point based on latest observations. Previous discussion... Showers and thunderstorms have wound down this afternoon as the upper level shortwave has lifted out of the region. Still seeing a few showers out there, and the latest mesoanalysis from SPC shows MUCAPE of 500-1000 J/kg across much of the area. Therefore expect thunderstorms will still be possible into early evening, and one or two may get strong enough to produce some small hail and heavy rain this afternoon. Otherwise, expect we`ll see a brief period of dry weather once the sunsets, but more showers will move in from the west later tonight as another shortwave swings by overhead. This activity will continue into the morning hours on Saturday, then precipitation will wane over much of the region as the upper support moves away. The exception will be the far western areas where showers and thunderstorms will be possible through the afternoon hours due to an approaching upper trough. Tonight`s lows will be on the muggy side, mainly in the mid and upper 50s. Saturday will be on the cooler side owing to the morning showers and plenty of cloud cover.
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&& .SHORT TERM /TONIGHT THROUGH MONDAY/... Sunday could be an active convective day. Saturday night will see some low clouds and fog develop w/a sse flow setting up. A warm front is forecast to lift n as low pres moves into Quebec. There appears to be enough forcing in the mid levels to set off some showers and possibly a couple of tstms. There does appear to be some elevated instability as noted by the NAM and to an extend the GFS to allow for some storms. Confidence attm is low and therefore, decided to go w/a slight chance for tstms even to the coast w/the elevated instability. Lapse rates do look to be in the range to allow for updraft potential. As the low pres center moves across Quebec it will bring a cold front across the region. The atmosphere looks like it does have some time to destabilize by late morning into the afternoon to allow for some convection. Strong upper support along w/some cooling aloft could allow for organized convection and lapse rates support this potential(6.5 c/km). SPC has kept the region in a Marginal Risk for a few storms to become severe. Since this is day 2 and there is still sufficient time to assess this potential, will let the later shifts take another look at things. Afternoon temps for Sunday will warm well into the 70s and hit around 80 for the Central Highlands and Downeast. The cold front is slated to be off the coast by Sunday evening w/clearing taking place. Winds are forecast to drop off as high pres is set to ridge into the region overnight. Despite the light w wind, decided to carry some patchy fog especially for areas that get the rainfall. Monday looks to be a dry day and comfortable as high pres briefly ridges over the region. Decided on a blend of the guidance for Monday`s daytime temps showing reading near normal for August. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... Somewhat unsettled into mid week. A potent system rolling out of the midwest is shown by the long range guidance to affect the CWA Tuesday into Wednesday with showers and tstms. The GFS and ECMWF both point to some llvl warming ahead of the apchg cold front on Tuesday along with some cooling aloft. This looks like it could be enough to support tstm activity both Tuesday and again on Wednesday. Decided to add the mention of tstms for both of these days. The upper system is forecast to move away from the region by Thursday allowing for a drier high pres to move across the region. && .AVIATION /04Z SATURDAY THROUGH WEDNESDAY/... NEAR TERM: VFR conditions will be short-lived this evening as another round of showers moves in toward 06z tonight and continues through 15z Saturday. MVFR conditions will be likely in rain. Patchy fog is also expected 04z-13z Saturday, with IFR possible. Conditions will gradually improve from west to east after 15z Saturday as showers come to an end. Expect all sites to return to VFR by 20z or so. SHORT TERM: VFR going to MVFR and possibly IFR overnight Saturday night into Sunday morning especially from KHUL down to KBGR and KBHB. Conditions are expected to go to VFR by mid morning w/some showers and tstms expected by Sunday afternoon into the evening. This would bring conditions down briefly to IFR and perhaps IFR. Improvement by Monday as drier air works its way into the region w/VFR. More showers and tstms for Tuesday w/conditions down at times to MVFR and IFR. && .MARINE... NEAR TERM: No headlines will be needed over the waters through the first half of the weekend as both winds and seas will remain below Small Craft levels. SHORT TERM: No headlines anticipated for this term. Light sse winds(10 kts) Saturday night into Sunday w/fog being a nuisance to mariners along w/a few tstms. Winds and seas could be higher in the tstms. SSW winds out ahead of the cold front on Sunday will bring winds up to 10-15 kts w/seas around 3 ft. Winds turning to the wnw later Sunday night into Monday will knock seas back to around 2 ft. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...None. MARINE...None. && $$ Near Term...Mignone

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