Area Forecast Discussion
Issued by NWS Caribou, ME

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000 FXUS61 KCAR 181320 AFDCAR Area Forecast Discussion National Weather Service Caribou ME 920 AM EDT Thu May 18 2017 .SYNOPSIS... A warm and humid air mass is expected across the region today ahead of a strong cold front which will cross the area Friday. High pressure will build across the region from the west over the weekend. && .NEAR TERM /THROUGH TONIGHT/...
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9:15 AM Update...The air is warming quickly Downeast and as of 9 AM it was already 80 degrees at Bangor so warmed temps through late morning. Expect a sea breeze to limit warming by midday. Western and northern areas are mostly cloudy with high clouds while Downeast areas are clear so modified cloud cover through midday to account for this. Previous discussion... The warmest day since last September today across the CWA. A warm front has lifted north of the area and has ushered in a warm and increasingly humid air mass. The 00z KCAR sounding had a 925H temperature of 12.6C, but the KGYX sounding had a 925H temp of 25.6C, which may end up being close to the low level air mass that will be experienced across the Downeast Region this afternoon. In fact, the NAM which has been one of the warmest of the models the past couple of nights, has a 925H temp of +25C all the way north to Caribou by 21Z this afternoon. The models do continue to differ on the exact position of a frontal boundary that will remain stalled out just to the north of the area. if the NAM is correct the area remains capped late into the day with the best chance of any thunderstorms holding off until early evening across far northwest portions of the CWA. The GFS would allow the cap to be broken a bit earlier by early to mid afternoon with scattered thunderstorms across the northern third of the CWA. Have continued to side with the idea that the frontal boundary remains just north of the area with little convection until late in the day, and mainly confined to the far northwest corner of the CWA. A prefrontal trough moves across the area this evening with a strong cold front to push into northern potions of the CWA after midnight. A couple of storms in the evening across the north could be on the strong side, but the timing does not look favorable for severe weather, but that could change if the boundary ends up a bit further to the south.A much cooler air mass sweeps into northern areas by morning.
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&& .SHORT TERM /FRIDAY THROUGH SATURDAY/... Sharp cold front will be working across northern areas Friday morning and should roughly be on a Houlton to Greenville line by 12z. The front will continue to sag south across the remainder of central and down east Maine later Friday morning before moving off the down east coast by early Friday afternoon. Moderately strong cold advection can be expected as winds shift to the north with the passage of the front. A few showers may linger across the far north early Friday morning before a much drier Canadian air mass builds toward the region. Highs on friday will be coolest across the far north due to the earlier timing of the frontal passage, where highs across the St. John Valley are only expected to be in the low 50s. However, across central and down east areas, highs will still climb into the upper 60s to lower 70s before the cold advection kicks in behind the front. Canadian high pressure will continue to build toward the area Friday night with mainly clear skies expected. H85 temperatures by 12z Saturday are expected to fall to around -4c across the St. John Valley, with H925 temperatures expected to be around 0C. The only limiting factor to preclude a significant frost threat will be enough low level mixing is expected with the high center still of to our northwest. However, couldn`t rule out some patchy frost across the colder valleys of northwest Maine where winds are more likely to decouple. Lows Friday night will range from the mid to upper 30s north and around 40 down east. Saturday is shaping up as a beautiful day with plenty of sunshine expected as high pressure continues to build across from the west. highs on Saturday will be a few degrees below normal for this time of year, with mid to upper 50s north and low 60s down east. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... Saturday night will be a mainly clear and cold night with the potential for some frost across the colder valleys of the north and west. Have trimmed back superblend temperatures a few degrees as clear skies and light winds will allow for some radiational cooling. Sunday will see increasing clouds by afternoon as the high moves east. High temperatures will be milder on Sunday with highs expected to range be in the mid 60s in most areas away from the coast. Low pressure will approach Sunday night and on Monday with an increasing chance for rain by Monday. The chance for showers will continue on Tuesday. Another system will bring the chance of another steady rainfall by late next week. High temperatures are expected to range a bit below to near normal for this time of year. && .AVIATION /13Z THURSDAY THROUGH MONDAY/... NEAR TERM: VFR today. Conditions will likely lower to MVFR at the northern terminals this evening with local IFR conditions possible in any heavier showers. Isolated thunderstorms are possible this evening to the the north of KHUL, with gusty and erratic wind possible in/near thunderstorms. SHORT TERM: Mainly VFR conditions are expected through the period. Winds on Friday will be gusty from the north. && .MARINE... NEAR TERM: The wind and seas are expected to remain just below small craft advisory levels through tonight. Persistent southwest flow may allow the seas on the outer coastal waters to build to near 5 ft by tonight. Areas of dense fog are possible tonight as a warm and humid air mass over the region remains above the cold waters. SHORT TERM: Winds/seas could approach SCA levels on Friday. && .CLIMATE... Record high temperatures are possible Today. Here are the record highs for May 18th: Caribou: 85F, in 1986 Houlton: 84F, in 1986 Millinocket: 89F, in 1918 Bangor: 87F, in 1936 && .CAR WATCHES/WARNINGS/ADVISORIES... ME...None. MARINE...None. && $$ Near Term...CB/MCB Short Term...Duda Long Term...Duda Aviation...CB/Duda Marine...CB/Duda Climate...CB

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