textproduct: Caribou

WHAT HAS CHANGED

-Confidence has increased in higher snow amounts and the track of the system.

-Winter Storm Warnings have been issued for the southern Penobscot, all of Hancock, and central and coastal Washington counties

-Winter Weather Advisory has been extended north into northern Penobscot, northern Piscataquis, northern Somerset, and all of Aroostook counties

KEY MESSAGES

1) Snow will overspread the region tonight with impacts to the Wednesday morning and evening commute expected.

2) Heavy snow showers possible across mostly northern areas Saturday.

3) Significant uncertainty regarding possible low pressure early next week.

DISCUSSION

KEY MESSAGE 1...Snow will overspread the region tonight with impacts to the Wednesday morning and evening commute expected.

KEY MESSAGE 1 DESCRIPTION... Confidence in the winter storms has greatly increased with the addition of the CAMS models into the forecast. The low pressure system will track across northern New York, pushing snow from west to east this evening. By tonight, the low will deepen causing it to pick up speed as ii move SE towards the Gulf of Maine. After midnight, the low will be over the waters. The deterministic and the ensemble models are in good agreement with more northerly track of the center of the low moving just south of the Downeast coast. The time period between midnight and Wednesday morning will be the period of higher snow total across the region with localized 0.5 inches per hour snow rate. This is due to the surface trof developing off the low.

By Wednesday, the system will shift to a ENE track moving south of Nova Scotia. However, the trof will still hang over the region. The concern is with the initial onshore flow that more moisture will pipe into the system causing more snow bands and higher snow amounts in the upslope of the higher terrain. By the afternoon and evening the trof will rotate across the region, pulling the snow bands across the north then wrap around to the south, while Washington county will see stagnant flow.

By Wednesday night, the system will start to clear out leaving behind snow showers that will develop in the north and possibly intensify with the north flow across the higher terrain.

KEY MESSAGE 2... Heavy snow showers possible across mostly northern areas Saturday.

KEY MESSAGE 2 DESCRIPTION... An upper level disturbance will cross the region Saturday. Steep low level lapse rates could accompany the disturbance which could support locally heavy snow showers which could reduce visibilities and impact travel. The best chance of snow showers should occur across northern areas.

KEY MESSAGE 3... Significant uncertainty regarding possible low pressure early next week.

KEY MESSAGE 3 DESCRIPTION... Low pressure should develop along the coast of the Carolinas early next week then track northeast. However, significant uncertainty with track still exists. Any possible impacts across the region will depend on the eventual track.

AVIATION /18Z TUESDAY THROUGH SUNDAY/

VFR across all terminals this evening and early tonight. By midnight cigs drop to MVFR/IFR and vsby to IFR/LIFR in snow. These conditions will continue through Wednesday. By Wednesday night, conditions will improve to MVFR/VFR cigs and vsby. Light and variable winds tonight and Wednesday morning. Then NNE winds 5-10 kts Wednesday afternoon to night.

Thursday...VFR/MVFR with a chance of snow showers north. Across Downeast areas, VFR/MVFR with a slight chance of snow showers early then VFR. North/northwest winds 10 to 15 knots with gusts up to 20 to 25 knots.

Thursday night through Friday night...VFR. Northwest/west winds 10 to 15 knots with gusts up to around 20 knots Thursday night and Friday. West/southwest winds 5 to 10 knots Friday night.

Saturday and Saturday night...Variable conditions with any snow showers. Otherwise, VFR/MVFR. West/southwest winds 10 to 15 knots Saturday. West/southwest winds 5 to 10 knots Saturday night.

Sunday...VFR/MVFR with a slight chance of snow showers. Variable winds 5 to 10 knots.

MARINE

Winds will increase tonight with the approaching system with wind reaching near SCA, but gust around 25 kts should be few. Winds decrease Wednesday, but then increase Wednesday night to SCA levels.

Wind gusts could approach gale levels Thursday into Thursday night. Small craft advisory conditions are then expected Friday into Friday night. A slight chance of snow showers Thursday. Light freezing spray Thursday into Friday night.

CAR WATCHES/WARNINGS/ADVISORIES

ME...Winter Weather Advisory from 7 PM this evening to 7 PM EST Wednesday for MEZ001>006-010-011-031-032. Winter Storm Warning from 7 PM this evening to 7 PM EST Wednesday for MEZ015>017-029-030. MARINE...None.