Area Forecast Discussion
Issued by NWS Caribou, ME

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000 FXUS61 KCAR 180517 AFDCAR Area Forecast Discussion National Weather Service Caribou ME 1217 AM EST Sat Nov 18 2017 .SYNOPSIS... Low pressure will continue to exit across the Canadian Maritimes overnight as high pressure builds across from the west. The high will move east on Saturday. Another low will track toward the area Saturday night through Sunday. && .NEAR TERM /THROUGH TODAY/...
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1215 AM update...No significant changes needed with this update. Stratocumulus deck is hanging tough across northeastern Aroostook County at this hour and will likely linger for the next few hours. Have adjusted the sky cover forecast accordingly. Otherwise the forecast is in good shape and no other changes were needed. Previous discussion...Surface and upper level low pressure will continue to exit through the Canadian maritimes overnight to be replaced by surface and upper level ridging by Saturday morning. The gusty northwest winds will continue into this evening as a tight pressure gradient remains in place across the area. However, the wind will begin to subside toward daybreak Saturday as the gradient weakens and the high builds across from the west. Expect mainly cloudy skies this evening to give way to partial clearing overnight. Lows tonight will generally range from the mid teens to around 20 across the north and lower 20s across central and downeast. After a mainly sunny start to the day, Saturday will see increasing high and mid clouds by afternoon in advance of the next low tracking toward the region from the west. However, it will remain dry as any precipitation associated with the next system holds off until after dark Saturday. Highs on Saturday will range from the mid to upper 30s north and lower 40s central and down east.
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&& .SHORT TERM /TONIGHT THROUGH MONDAY/... Precipitation will spread from SW to NE over Sat night. Depending on how cold the lowest levels get Sat PM and early overnight hours, overrunning warm air could lead to some early snow and then mixed precip overnight. Any mixing would be mainly north of a Greenville-Houlton line between 00z and 06z Sun, with all rain expected by daybreak Sun. As of now, the NAM appears to be the strongest on mixed precip potential, but the GFS is not too much warmer, so it seemed prudent to include the mix potential. Gusty S-SE`ly winds will pump warmer air into the CWA after 12am Sun, and pretty widespread rain is expected into Sun afternoon as low pressure moves NE down the St. Lawrence Valley. There is some disagreement on the path of the main low and whether or not a coastal low will develop, and for now the forecast reflects the main low passing just north of the state Sun afternoon with no significant coastal low development. As the low passes to the north, rainfall will diminish from S to N Sun eve, with just some lingering snow showers expected across the Crown of Maine and western North Woods through early Mon morning. Regarding possible headlines in the short term, at this point am not convinced of the need for any wind headlines. Typical parameters we look for to get advisory level winds for Downeast are not met later Sun or Sun night. That said, will need to watch for high winds in the Central Highlands and Quebec border (mainly zones 3, 4, and 10) behind the cold front. A Gale Watch seems quite likely, once the current marine headlines expire. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... Weak ridging likely to bring dry weather Mon night into Tue morning. A weak shortwave moving through Canada may push a front across the area Tue night or Wed AM. There will likely be some rain/snow showers with this front across the north and west zones, but kept POPs to low- end Chance for now due to disagreements on timing and also uncertainty on the coverage. Expecting a break in the weather Wed into Thu. All models point to the potential for a trough and associated surface low crossing the area Fri and Fri night, though there are significant disagreements on how deep the trough will be and the strength of the surface low and coverage of precip. Did lean toward the stronger CMC/ECMWF solution, but kept POPs to Chance or less for now. && .AVIATION /05Z SATURDAY THROUGH WEDNESDAY/... NEAR TERM: MVFR ceilings late this afternoon will give way to VFR and decreasing clouds overnight. Northwest winds will gust up to 35 kt this evening and then diminish overnight. Light winds and VFR conditions can be expected on Saturday. SHORT TERM: VFR conditions Sat eve will quickly deteriorate to IFR and even LIFR conditions late Sat night into Sun AM, with these reduced conditions expected to continue into early Sat afternoon. Improvement back to MVFR or VFR conditions are expected later Sun eve into Sun night, though local IFR conditions are possible in any lingering snow showers for KPQI to KFVE through 12z Mon. VFR conditions then expected Mon and Tue, with another round of rain and/or snow showers Tue night into Wed AM bringing possible MVFR or IFR conditions. && .MARINE... NEAR TERM: Small craft adv conditions are expected the remainder of the night. Winds/seas will remain below small craft advisory levels early Saturday before increasing by later Saturday afternoon. SHORT TERM: Borderline SCA criteria onshore winds are expected Sat night into early Sun AM, with gale force gusts expected later Sun morning into Sun night as winds shift SW-W`ly. Winds will decrease some during the day Mon, but likely to remain well above SCA criteria. Seas initially 3-6 ft Sat eve will build to 10-14 ft for offshore waters Sun afternoon through Sun night. Seas will decrease some Mon as winds turn offshore, but remain 5-9 ft further from the coast. && .CAR WATCHES/WARNINGS/ADVISORIES...
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ME...None. MARINE...Small Craft Advisory until 4 AM EST early this morning for ANZ050>052.
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