textproduct: Caribou

WHAT HAS CHANGED

- Issued a Winter Storm Watch for Downeast Maine and the Bangor Region from Monday AM through Tuesday AM. Due to increased confidence in an impactful winter storm.

- Raised snowfall totals along the Maine/New Brunswick border into Aroostook County for the storm but remain below headline criteria.

- Lowered snow to liquid ratios across the entire CWA for the storm due to a strong low level jet.

KEY MESSAGES

1) A winter storm is likely Monday into Monday night. Strong, gusty winds with snow is expected with the highest totals and strongest winds over Downeast Maine. Blowing snow also likely.

2) A clipper system is possible Wednesday night into Thursday. Snow may mix with or change to rain in southern areas on Thursday. This has the potential to impact travel, especially during the Thursday morning commute.

DISCUSSION

KEY MESSAGE 1...A winter storm is likely Monday into Monday night. Strong, gusty winds with snow is expected with the highest totals and strongest winds over Downeast Maine. Blowing snow also likely.

KEY MESSAGE 1 DESCRIPTION... A strong low pressure system is expected to develop over the Southeastern US Sunday morning and strengthen while moving northeast along the Atlantic seaboard. The storm will become occluded off the Mid-Atlantic coast and reach a maximum intensity south of Cape Cod Monday afternoon. Latest ECMWF, ECMWF AI, GEFS and GFS have the storm passing just SE of The Benchmark (40N, 70W) while the NAM and Canadian have it inside or over the Benchmark. The storm will pass south of the area along the outer edge of the Gulf of Maine Monday to Monday night with the potential for a potent band of heavy snow over the Downeast region. Looking at the ensembles members, there is still some uncertainty on track but most of the members are well within the mean and track is starting to be nailed down. This storm looks to pass over or just slightly outside The Benchmark resulting in Downeast seeing the greatest potential of Winter Storm criteria snowfall. Typically NAM and Canadian modeling struggle with occluded deep storm system tracks off New England but a closer track to our area will mean greater snow amounts and stronger winds. Opted to keep the trend favoring a impactful event for Downeast Maine and into the Bangor Region with lesser amounts north and west.

There is high confidence that the greatest impacts regardless of storm track will be Downeast Monday into Monday night. Current guidance supports snow totals in excess of 6 inches across much of Downeast Maine and Bangor Region with the highest totals along the coast. Snow totals have the highest probability of >10 inches in Downeast Maine from Bar Harbor to Machias, Eastport and north to Baileyville, chances are 70-85%. Snow to liquid ratios are expected to remain above 10:1 as a result of a sufficiently cold vertical column which will support dry, fluffy snow. However, significantly reduced SLRs from the NBM as a strong easterly low level jet just below the DGZ may contribute to significant crystal breakup. Opted to go with a 10-12:1 ratio across much of the area with 13-14:1 in Northern Maine.

Gusty winds are also expected with this storm as strong 850mb flow has the potential to mix down to the surface resulting in gusts up to 45 mph. Cannot rule out some gusts up to 50mph along the Downeast shoreline and MDI with NBM QMD probabilities >60 percent for MDI of gusts up to 50mph. This is likely to result in visibility reductions and blowing snow. Cannot rule out a chance of blizzard conditions with the greatest risk along coastal Downeast where snow rates and winds will be highest. However, this will greatly depend on storm track with a closer system track favoring an increased chance of blizzard conditions and a farther offshore system track favoring a lower chance. Regardless, falling and blowing snow is likely to result in hazardous travel conditions.

Put all of this together opted to hoist a Winter Storm Watch from Monday AM to Tuesday AM. Heavy snow and blowing snow possible. Total snow accumulations greater than 6 inches possible, the highest totals will be in Downeast Maine. Winds could gust as high as 45 mph. Visibilities may drop below one quarter mile due to falling and blowing snow. Whiteout conditions are possible and may make travel treacherous and potentially life-threatening. Travel could be very difficult. The hazardous conditions could impact the Monday morning and evening commutes.

KEY MESSAGE 2...A clipper system is possible Wednesday night into Thursday. Snow may mix with or change to rain in southern areas on Thursday. This has the potential to impact travel, especially during the Thursday morning commute.

KEY MESSAGE 2 DESCRIPTION... An upper-level disturbance moving east from over central Canada will result in the development of a modest low pressure system over the Great Lakes region. Models generally show the low tracking through or just north of our area sometime Wednesday night through early Thursday. Ensembles show considerable uncertainty in low track and timing so cannot yet be definitive on how impactful the storm will be but likely will not be as impactful as the Monday-Monday night storm.

The best chance for accumulating snowfall will be in northern areas whereas more southern areas may see a rain/snow mix or a turn to rain depending on how far inland warm air reaches. Generally expecting limited travel impacts, mostly in the north.

AVIATION /00Z SUNDAY THROUGH THURSDAY/

Tonight...VFR across all terminals. N wind around 5 kt.

Sunday...VFR across all terminals. Winds light and variable.

Sunday night...VFR all sites, possibly dropping to MVFR across southern sites late at night. NE wind around 5 kt north and 5 to 10 kt increasing to 15 kt over the south, with gusts up to 25 kt possible at BHB toward Monday morning.

Monday...VFR, becoming MVFR across the north. MVFR, becoming IFR, and possibly LIFR mid afternoon, over the south. -SN at southern terms potentially +SN late day. Increasing NE wind 10 to 15 kt over the north and 15 to 25 kt over the south with possible gusts to 45 kt at BGR/BHB. LLWS likely all terms. BLSN possible late day at southern terms.

Monday night...MVFR, possibly dropping to IFR north and IFR, possibly LIFR, south. Improvement to MVFR late. SN and +SN possible at southern terms. -SN northern terms. N/NW wind 10 to 15 kt north and 15 to 25 kt over the south with gusts up to around 45 kts early at BGR/BHB. Winds shifting overnight to the N-NW. LLWS likely all terms. BLSN possible at southern terms.

Tuesday...MVFR, becoming VFR all sites. NW wind 10 to 15 kt with gusts up to 25kt possible. DRSN/BLSN possible.

Tuesday night...VFR. W wind around 5 kt.

Wednesday...VFR, possibly dropping to MVFR north. SW wind around 5 kt.

Wednesday night...Deteriorating to MVFR, IFR also possible. S/SE wind around 5 kts.

Thursday...MVFR/IFR possible. SW winds 5-15kt. -SN north and RA/SN possible south.

MARINE

7 PM Update: Winds will continue to gust to around 25 kts on the coastal waters for a few more hours, before dropping below small craft advisory levels overnight.

Previous Discussion: Winds will be below SCA Sunday, then increase to SCA then a strong gale Sunday night as powerful low pressure tracks toward the Southern Gulf of Maine. Seas up to 4 ft tonight, 3 ft Sunday, then building up to 8 ft by late Sunday night.

E-NE Winds will rapidly increase to Gales and potentially Storms Monday AM across the Coastal Waters. Intra-Coastal waters will hit Gale conditions. Increased confidence in wind gusts reaching 55-60kt across the Coastal Waters during Monday Afternoon into the evening then relaxing back to Gale conditions into Tuesday AM.

Will continue the Storm Watch for the Coastal Waters from Monday morning through late Monday night. For the Storm Watch, northeast winds 35 to 45 kt with gusts up to 60 kt and seas 11 to 16 ft possible. Gale Watch during the same timeframe for the Intra-Coastal Waters. North winds 25 to 35 kt with a few gusts up to 50 kt and seas 6 to 11 ft possible.

We anticipate extremely hazardous seas during the Monday into Tuesday AM timeframe. Seas could capsize or damage vessels and reduce visibility. Mariners should prepare to remain in port, alter course, and/or secure the vessel for severe conditions. Additionally, snow will be falling and be heavy at times reducing visibility less than 1/2nm. Cannot rule out light freezing spray during the nighttime hours.

Beyond into mid week...SCA conditions on Tuesday PM relaxing below SCA for Wed. Another round of SCA conditions late week.

CAR WATCHES/WARNINGS/ADVISORIES

ME...Winter Storm Watch from Monday morning through late Monday night for MEZ015>017-029-030-032. MARINE...Small Craft Advisory until 5 AM EST Sunday for ANZ050-051. Storm Watch from Monday morning through late Monday night for ANZ050-051. Gale Watch from Monday morning through late Monday night for ANZ052.