textproduct: Caribou

SYNOPSIS

A closed low tracks north through the western Maritimes tonight. Canadian high pressure slowly builds in from the west Saturday through Monday, meanwhile a weak low passes well to the south Saturday night and Sunday. The high exits to the east Monday night, followed by another weak low passing to the south on Tuesday. Another low moves over the state on Wednesday.

NEAR TERM /THROUGH SATURDAY NIGHT/

Update... West to northwest flow of very cold air remains across the region at this hour. Temperatures were already ranging from 0 to 5 above zero across much of the forecast area at this hour under mainly clear skies. Current forecast remains largely on track through the overnight hours, so no major changes needed at this hour.

See updated aviation and marine sections below.

Key Message: * Frigid air remains in place through the near term, with very cold wind chills tonight to 30 below zero

Discussion: High pressure continues to build into the area, with clear skies over most of the forecast area this evening. Lingering snow showers over the far northern portion of the CWA will continue to slowly exit to the north, leading to clearing skies through the St. John Valley as well. Clear skies will persist through the night, along with breezy winds. These winds are the result of cold air rushing into the area behind the recent low pressure departure, and lows tonight may fall to around 10 below zero in the north, and around zero in the Bangor region. Coupled with the winds, wind chills could fall to 25 to 30 below zero across the north, and a Cold Weather Advisory is in place for the north tonight into early Saturday morning.

Cold air will continue to hang around through the day on Saturday with temperatures only lifting into the single digits above zero. For Saturday night, increasing cloud cover north of a shortwave that will be ducking just south of the forecast area will limit how much can radiationally cool overnight, though winds will be much lighter at that point. Still, arctic air in place will allow for temperatures to drop below zero throughout the forecast area.

SHORT TERM /SUNDAY THROUGH MONDAY/

Key Messages -Very cold airmass bringing temps well below normal Sunday through Monday.

A large upper level trof with continue NW flow should pipe down arctic air to the surface. The 925mb model temps continue to show around -22C in the north and -16C in the south. Thus, Sunday high temps should be in the single digits in the north and teens in the south. The major concern is the wind chill values for Sunday night. Models show the trof digging deeper into the state, causing colder temps to reach the coast. This coupled with the mostly clear skies and calming winds should allow for ample decoupling. Temps are expected to reach into the teens below zero in the north and single digits below zero in the south. Though WNW winds should be light, gusts up to 15 mph is expected to drop wind chills in the 20s below zero in the north and teens below zero in the south. By Monday, clearing skies and the surface ridge moving in should gradually warm temps into the single digits above zero.

LONG TERM /MONDAY NIGHT THROUGH FRIDAY/

Key Messages -Warming trend by midweek. -Strong model uncertainty for the Wednesday system.

Models favor an upper level ridge moving into New England at the beginning of the week, making for a fairly inactive pattern. Though cannot rule out a few shortwaves moving cross the region creating snow showers with minimal impact. By Wednesday, upper level models show a weak trof developing. This could develop into a closed surface low by Wednesday afternoon. GFS and Euro ensemble mean seems to favor the center of the low moving over the region. If this plays out then a mixed precip event is possible with a warming trend through the rest of the week. The Canadian ensemble mean favors a north track of the low, making for a snow event with little accumulation and cooler temps. The probabilities still give a wide enough range to give little confidence in the track of the system.

AVIATION /00Z SATURDAY THROUGH WEDNESDAY/

NEAR TERM: VFR conditions expected tonight through Saturday. W to NW wind will be gusty at times through Saturday.

Outlook for Saturday night...VFR.

SHORT TERM: Sunday...VFR. Variable winds around 5 kts.

Sun night-Mon night...VFR. NW winds 5-10 kts.

Tuesday...VFR north, VFR/MVFR south in snow showers. Light and variable winds.

Wednesday...MVFR/IFR in snow north and rain south. Variable winds 5-10 kts.

MARINE

NEAR TERM: A Small Craft Advisory is in effect through Saturday afternoon for the outer waters and for the intra coastal zone through Saturday morning. Winds/seas should generally remain below SCA levels Saturday night although a few gusts to 25 kt will still be possible early.

A Freezing Spray Advisory remains in effect from late tonight until 11 AM EST Saturday morning.

SHORT TERM: Winds should reach SCA levels Sun night to Mon morning. Then winds and seas should remain below SCA levels Mon afternoon through the rest of the period.

CAR WATCHES/WARNINGS/ADVISORIES

ME...Cold Weather Advisory until 10 AM EST Saturday for MEZ001>006- 010. MARINE...Small Craft Advisory until 4 PM EST Saturday for ANZ050-051. Freezing Spray Advisory from 1 AM to 11 AM EST Saturday for ANZ050>052. Small Craft Advisory until 10 AM EST Saturday for ANZ052.