textproduct: Caribou

WHAT HAS CHANGED

* 6:59AM UPDATE...Have made adjustments to the POPs to follow KCBW and Canadian radar trends over the CWA. Increased POPs for chance snow showers in Downeast areas due to recent increasing echos off the KCBW and KGYX radars. Across Northern Maine where a solid area of snow is falling expecting to fill in more and become moderate at times this morning as surface cyclogenesis increases with a low tracking from Maine into New Brunswick. This will allow for increased surface lift and deformation banding features to setup over Northern Maine. Will continue Winter Weather Advisory across Northern Maine for widespread 3-5 inches. SPS issued for Downeast Maine where flash freeze in progress with temperatures rapidly falling below freezing. 12z TAF Aviation update below...

* Increased the probability for snow Saturday afternoon and Saturday evening.

* Increased the probability for snow Downeast Sunday evening.

KEY MESSAGES

1) Rapidly increasing potential of heavier snow this morning through midday in Northern Maine. Gusty winds will lead to blowing/drifting snow in the north today will increase the hazardous travel conditions.

2) Flash freeze conditions this morning in Downeast Maine and Bangor Region, freezing up any standing water on untreated surfaces. Could make AM commute hazardous.

3) Generally light snowfall expected Saturday afternoon through Saturday evening with locally hazardous travel conditions possible.

4) Continued low chance of an impactful winter storm, especially Downeast areas later Sunday into early Monday, which could result in locally hazardous travel.

DISCUSSION

KEY MESSAGE 1... Rapidly increasing potential of heavier snow this morning through midday in Northern Maine. Gusty winds will lead to blowing/drifting snow in the north today will increase the hazardous travel conditions.

KEY MESSAGE 1 DESCRIPTION... This is an extremely challenging forecast this morning with rapidly changing model guidance with significant agreement. 500mb low remains back across Vermont and New Hampshire slowly drifting east this morning. Upper level divergence is increasing over Eastern Maine and giving way to pressure falls across southwest Maine suggesting surface cyclogenesis is taking place. Significant swing in model guidance over the last several hours shows very good agreement of a blossoming area of light to moderate precipitation to develop over the Moosehead Region and eventually tracking northeast. It is Northern Maine that the greatest concern of higher snowfall potential. Overnight the hi-res CAMs including RRFS and HRRR show a significant burst of snow to develop over the next several hours. This has now appeared solidly in the ECMWF and GFS operational and ensemble means. Additionally looking at the ECMWF/GFS ensemble low locations nearly all are in favorable position and strengthening to produce significant boost in snowfall.

Given these trends have made significant changes to POPs and QPF but likely to make more changes this morning to account for this rapidly changing forecast. Bottom line be prepared for accumulating snow that will require plows and make for slippery travel in Northern Maine this morning. Hi-Res CAMs and global models show the precip tapering SW to NE late morning into mid afternoon. Have bumped snow totals in Northern and Northeast Aroostook County to a widespread 3-5 inches with 1-3 inches for the rest of Northern Maine and 1-2 inches for Moosehead Region. Have added wording to the HWO for Northern Maine with hazardous travel conditions expected but will monitor trends for potential winter weather headlines.

Lastly, winds will increase today as the surface low deepens in New Brunswick and expecting areawide NW winds 10-15mph and gusting 25-35mph with potential for higher gusts in the higher terrain and open fields. Given the current snowpack is mostly frozen solid from the warm up and refreeze nearly all the new fluffy snow on this surface will be picked up and blown around. Expecting the potential for localized whiteouts and significant drifting of the snow to cause slippery travel conditions. This will mainly impact typical open agricultural areas of Aroostook County, Northern Penobscot County and portions of Route 6 between Shirley and Greenville in open areas on the higher terrain.

KEY MESSAGE 2... Flash freeze conditions this morning in Downeast Maine and Bangor Region, freezing up any standing water on untreated surfaces. Could make AM commute hazardous.

KEY MESSAGE 2 DESCRIPTION... As of 1AM EST the cold front extends along I-95 from Houlton to Lincoln and nearing the Bangor area. North and Northwest of this front temperatures have fallen 10-15 degrees in the last several hours refreezing any leftover standing water. This has made conditions slippery across much of Northern Maine and Moosehead Lake Region. This front will continue pushing SE over the next several hours and expect temperatures to rapidly fall with FROPA. South of the front temperatures are in the upper 30s to near 40F but temperatures behind the front are in the teens and low 20s. Given the light winds and even fog ahead of the front expecting a lot of moisture on untreated roadways and surfaces to rapidly freeze. Expecting patchy to areas of black ice to develop this morning leading up to the AM commute. Expecting potentially dangerous driving conditions along I-95, The Airline and Route 1 corridors. Expect the entire CWA to be below freezing by 8AM EST with the last locations including Whiting to Eastport and Lubec region.

KEY MESSAGE 3... Generally light snowfall expected Saturday afternoon through Saturday evening with locally hazardous travel conditions expected.

KEY MESSAGE 3 DESCRIPTION... A weak area of low pressure tracks northeast from the Great Lakes region on Saturday. Another weak area of low pressure will then track across the Downeast region Saturday afternoon, then exit through the Canadian Maritime Provinces Saturday night.

There is enough consensus in the guidance and ensemble data to support an increase in the probability of snow Saturday afternoon through Saturday evening. This will be a quick moving system and snowfall amounts are expected to be generally on the light side. Appears as if a general 1 to 3 inch snowfall is in store for much of the region from Saturday afternoon through Saturday evening. Along the coast, the snow may mix with rain with generally an inch or less expected. With light snowfall rates and no strong wind expected with this system, impacts are expected to be minimal, other than the possibility for locally slick travel conditions. At this point, the snow is expected to begin between 10 AM and 12 PM along the I-95 corridor from Houlton to the Bangor region. Expected snow start times north of Houlton up through the St. John Valley are between 12 PM and 2 PM. The snow is expected to taper off in the Bangor region after 7 PM but and between 9 PM and Midnight to the north.

Key Message 4... Continued low chance of an impactful winter storm, especially Downeast areas later Sunday into early Monday, which could result in locally hazardous travel.

KEY MESSAGE 4 DESCRIPTION... Low pressure is expected to move northeast across the western atlantic during Sunday and then track across, or to the south of Nova Scotia, Sunday night through early Monday. However, the AI GFS, as well as some ensemble solutions do show a more westward track. If these solutions were to verify, a potential impactful winter storm, with accumulating snow and wind for portions of the forecast area, could be expected. Regardless, whether a more westward track is realized, felt confident enough to increase probability of snow for portions of Downeast Maine, especially central and coastal Washington county, which would likely see at least some measurable snowfall Sunday evening.

AVIATION /12Z FRIDAY THROUGH TUESDAY/

12z TAF UPDATE...Continuing IFR brief LIFR across northern terms with -SN into the afternoon. Expecting a return to VFR this evening for all northern terms. MVFR becoming VFR at southern terms. NW winds 10-15kt with gusts up to 20-30kt. LLWS likely at all terms this afternoon into the evening.

Previous Discussion... Northern Terms Today...IFR/LIFR with -SN likely. Becoming MVFR cigs this afternoon. VCSH and BLSN/DRSN may reduce vsby briefly. NW winds increasing this AM 10-15kt gusting 20-30kt. LLWS possible at HUL later this afternoon.

Southern Terms Today...MVFR/IFR cigs this AM becoming VFR. NW winds increasing this AM to 10-15kt gusting 20-30kt.

All terms tonight...VFR cigs with many sites briefly going SKC. W-NW winds 5-15kt.

Saturday...VFR early, then MVFR or lower in developing snow.

Saturday night...MVFR or lower in snow, then improving to VFR/MVFR late.

Sunday...MVFR possible. Chance of snow.

Sunday night...MVFR or lower possible. Chance of snow, especially eastern terminals.

Monday...MVFR or lower possible early, then VFR.

Tuesday...MVFR. Chance snow showers. Gusty NW possible.

MARINE

Conditions are worsening this early morning and expecting wind shifts to the W in the next 1-3hrs. Gale Warning in effect from 5AM this morning till 5PM EST this evening for the Coastal Waters out 25nm. W winds 20-30kt with gusts up to 40kt and seas 7-10ft. Small Craft Advisory in effect for the Intra- Coastal Waters till 7PM EST this evening. W winds 15-25kt with gusts up to 30kt and seas 3-6ft. Any remaining rain over the far eastern waters this morning may reduce vsby less than 3nm at times. This morning after the wind shift light freezing spray is likely as temperatures rapidly fall. Sea surface water temperatures range from 38-42F from the Downeast Coast out 25nm and east to the Hague Line including Penobscot and Passamaquoddy Bays. Tonight expecting winds to rapidly drop below 15kt over the waters but seas will remain elevated likely requiring a Small Craft Advisory.

Small craft advisory level conditions are expected through the weekend, mainly across the outer waters. In fact, small craft advisory conditions look to persist through much of the early to mid part of next week.

CAR WATCHES/WARNINGS/ADVISORIES

ME...Winter Weather Advisory until 4 PM EST this afternoon for MEZ001-002. MARINE...Gale Warning until 5 PM EST this afternoon for ANZ050-051. Small Craft Advisory until 7 PM EST this evening for ANZ052.