textproduct: Caribou

SYNOPSIS

High pressure will build in from the north and west and remain northwest of the state Saturday. High pressure crosses the region Sunday. Low pressure crosses the region Monday, lifting north of the region Tuesday through Wednesday.

NEAR TERM /THROUGH SATURDAY NIGHT/

7pm Update... Some spots in the north already approaching forecast overnight lows, and many spots are cooling off more rapidly than forecast, thus lowered low temperatures tonight a few degrees. Also decreased sky cover this evening, as mostly clear skies are part of the reason our temperatures are dropping readily, along with the decreasing winds.

Key Message 1) Cold and Mostly Cloudy Tonight, Chilly Saturday

Discussion...

Key Message 1... Tonight a weak storm system passes well southwest of Maine associated with a 500mb shortwave. Ridging over Maine takes place with large surface high pressure to our north. Using the NOAA Hysplit Model we see that the airmass over Maine originated from the Northwestern Passages arctic region of Nunavut, Canada 8-10 days ago. 925mb temps slightly modifying to for tonight to range between -17C north and -14C south. This will result in temperatures falling back to the single digits below zero across the north and single digits above zero south. A challenge in the forecast tonight is high clouds associated with the passing system SW of Maine. High clouds could keep temps up a degree or two but with the cold airmass in place kept with what NBM has and temperatures either side of zero. Winds thankfully relax in most locations but any breeze or stirring of the wind will cause wind chills -15F to -10F tonight.

Tomorrow will be a slightly modifying arctic airmass but as surface high pressure takes over expecting increasing sunshine. Highs will only climb once again into the low teens north, mid to upper teens from the Central Highlands to Bangor Region and 20F for the Downeast coast. N-NW winds 5-15mph may briefly gust up to 20mph at times. Wind chills around 0F across the north and 5-10F for the Downeast and Bangor region.

SHORT TERM /SUNDAY THROUGH MONDAY/

High pressure builds toward the region Sunday with mostly clear/partly cloudy skies. High pressure crosses the region Sunday night while intensifying low pressure lifting across the Great Lakes draws a warm front toward southern New England. Clouds will increase in advance of the warm front Sunday night. A light wintry mix could also begin to approach southwest portions of the forecast area late. The Great Lakes low should track toward southwest Quebec province drawing the warm front north across New England Monday, with a triple-point low then starting to develop across southern Maine late. Precipitation will expand across the entire forecast area Monday. Across central and Downeast portions of the forecast area, with low level cold air damming and warming temperatures aloft expect an early wintry mix. Warmer air will eventually be drawn northward at low levels helping erode the cold air and allowing a transition to rain across Downeast and central areas. Across northern portions of the forecast area, more uncertainty exists regarding the amount of warming aloft. This would allow a greater portion of the precipitation to remain in the form of snow across northern portions of the forecast area, though even there a wintry mix is possible later Monday. The secondary low will lift across the forecast area Monday night, though the track is still uncertain, eventually merging with the remnants of the primary low. Precipitation types and the amount of warming Monday night will be dependent on the eventual track of the secondary low. Generally expect rain across Downeast portions of the forecast area early Monday night, with snow or a wintry mix across northern and central areas. Colder air will eventually be drawn across the entire region later Monday night in the wake of the system allowing a transition back to snow. The better snow chances later Monday night will occur across northern areas, with more persistent wrap-around precipitation. Precipitation types and snow amounts with this storm are still uncertain dependent on how the event eventually evolves. High temperatures Sunday will range from the lower to mid 20s north, to the upper 20s to around 30 Downeast. Low temperatures Sunday night should occur early, then stabilize or begin to slowly warm late. Temperatures should warm through Monday. High temperatures later Monday should range from the mid 20s north, to the mid 30s interior Downeast with upper 30s to around 40 along the Downeast coast. Temperatures should remain near steady early Monday night then begin to fall late. Low temperatures later Monday night should range from the mid teens to around 20 north, to the lower to mid 20s Downeast.

LONG TERM /MONDAY NIGHT THROUGH FRIDAY/

The system vertically stacks while the upper low crosses the region Tuesday, lifting to the north Tuesday night. Expect mostly cloudy skies across the region Tuesday. Will also have a chance of snow showers across the north and mountains, slight chance Downeast. A disturbance, with uncertain timing, rotating around the upper low should cross the region Wednesday into Thursday with partly/mostly cloudy skies along with a slight chance of snow showers. Partly/mostly cloudy skies should persist Friday with still a slight chance of snow showers. Near normal, to slightly below normal, level temperatures are expected Tuesday. Below normal level temperatures are expected Wednesday through Friday.

AVIATION /00Z SATURDAY THROUGH WEDNESDAY/

NEAR TERM:

Tonight...VFR. N winds 5-10kt.

Saturday...VFR. Small (25 percent) chance of intermittent MVFR cigs from roughly 10-16z at northern terminals like PQI/CAR/FVE. N-NNW winds 5-15kt.

Saturday night...VFR SKC. NW winds 5-15kt.

SHORT TERM:

Sunday...VFR. Northwest winds 10 to 15 knots with gusts up to 20 knots, becoming northwest/west 5 to 10 knots.

Sunday night...Generally VFR. Occasional MVFR possible late. A wintry mix possible late at KBGR/KBHB. Variable winds 5 to 10 knots.

Monday...VFR/MVFR early, lowering to IFR/LIFR through the afternoon. Snow transitioning to a wintry mix north, with a wintry mix transitioning to rain Downeast. Variable winds 5 to 10 knots, becoming east/southeast 10 to 15 knots with gusts up to around 20 knots.

Monday night...IFR/LIFR. Snow, or a wintry mix transitioning to snow, north. Rain transitioning to snow Downeast. East/southeast winds 10 to 15 knots with gusts up to around 20 knots, becoming west/southwest.

Tuesday...MVFR/IFR north with a chance of snow showers. VFR/MVFR Downeast with a slight chance of snow showers. West/southwest winds 10 to 15 knots with gusts up to 20 to 25 knots.

Tuesday night through Wednesday...VFR/MVFR with a slight chance of snow showers north. VFR Downeast. Southwest winds 10 to 15 knots with gusts up to 20 to 25 knots.

MARINE

NEAR TERM: Small Craft Advisory remains in effect for the Coastal Waters out 25nm through 7PM EST this evening. N wind gusts up to 30kt possible. Tonight N wind gusts remain 15-20kt with Light Freezing Spray expected. N winds shift NW Saturday evening and once again be gusting 25-30kt over the Coastal Waters and may require another Small Craft Advisory. Light freezing spray is expected. Sea surface water temperatures from the Downeast Coast out 25nm range 43-45F including Penobscot and Passamaquoddy Bays.

SHORT TERM: Small craft advisory conditions Sunday through Monday. Gale force wind gusts then Monday night into Wednesday. A chance of rain Sunday night. Rain Monday through early Monday night, then a chance of rain and snow later Monday night. A chance of snow showers Tuesday. Light freezing spray Sunday morning.

CAR WATCHES/WARNINGS/ADVISORIES

ME...None. MARINE...None.