textproduct: Caribou

WHAT HAS CHANGED

-Increased PoPs across the north on Saturday with increased confidence in numerous snow showers, and expanded the footprint of precip and QPF as the showers will be possible down through the coast

-Continued model uncertainty for storm Wednesday into Thursday.

KEY MESSAGES

1) Scattered moderate to heavy snow showers on Saturday, which may result in rapid drops in visibility and sudden deterioration in travel conditions.

2) Potential for a system to bring periods of snow throughout the region mid-week next week, which could potential make travel hazardous.

DISCUSSION

KEY MESSAGE 1... Scattered moderate to heavy snow showers on Saturday, which may result in rapid drops in visibility and sudden deterioration in travel conditions.

KEY MESSAGE 1 DESCRIPTION... A strong 500 mb vort max to the north will sink southwards over the forecast area through the day on Saturday, increasing instability for the CWA. With origins in a continental polar air mass, available moisture will be limited with the surface trough as it moves through. That said, enough moisture will exist that the instability will support convective snow showers through the day on Saturday. Snow showers are most likely and likely to be most widespread across the north, but the ingredients exist for these convective showers to extend all the way south through the coast. Some convective allowing models suggest that there could be a linear mode to some of these showers, which may increase the chance for gustier winds. That said, this feature is also positioned to come through after the pressure gradient over the area relaxes, so there will not be much mid level wind to transport to the surface, and stronger winds will be hard to come by with these showers. With all these ingredients mixed together, an isolated snow squall cannot be entirely ruled out, however chances are low for snow squalls by definition (less than 10 percent chance). However, locally moderate to heavy bursts of snow are possible in this setup, and wherever these stronger showers occur, visibility may suddenly drop, becoming hazardous to those who are out and about this weekend. Stay weather aware, and leave extra space between you and the car in front of you if driving around these convective showers Saturday into Saturday evening.

Total snowfall from these snow showers will likely be minimal, with less than an inch total new snow, however areas which see training showers and/or stronger snow showers could see just over an inch of new snow.

KEY MESSAGE 2...Potential for a system to bring periods of snow throughout the region mid-week next week, which could potential make travel hazardous.

KEY MESSAGE 2 DESCRIPTION... Low pressure system to the west quickly moves eastwards towards the region, bringing a potential for snow showers in the north, and some rain along the Downeast coast. Warm air advection early next week raises temperatures into the 30s for most of the region, which could cause some significant snow melt in places receiving rainfall. Temperatures are expected to fall below freezing quickly overnight, which could cause issues for travel Wednesday night into Thursday.

There is disagreement among the models in terms of timing for this system, with the GFS showing a stronger and faster low pressure system, and precipitation moving in by Wednesday evening. The ECMWF, however, has been doing a southerly trend and shows lower snowfall totals. There is also disagreement in model runs with precip types. NBM keeps snow in the north, a rain/snow mix in central and eastern Maine, and rain Downeast, before transitioning over to snow everywhere Wednesday night. The GFS and ICON has begun to bring in a lot more cold air Downeast, keeping all of the precipitation Wednesday into Wednesday night as snow. The rest of the models keep Downeast in the mid-to-upper 30s, however, and with warm air advection ahead of incoming cold front, leaning more towards snow in the north, rain Downeast, and a rain/snow mix line in between. Too early to get specific with snow totals. Southerly track seems to keep accumulations low in the north, and higher Downeast. A more northerly track keeps snow in eastern and northern Maine. Continue to monitor for more updates as models hopefully come into agreement soon.

AVIATION /06Z FRIDAY THROUGH TUESDAY/

VFR conditions continue across all terminals tonight under clear skies. LLWS may continue for a few more hours, and will begin to dissipate between 10 and 13z as diurnal mixing begins to return. Gusty NW winds 5 to 10 kts with gusts 20 to 25 kts will begin to decrease through the day today, becoming light and variable tonight. VFR conditions continue tonight and into the day on Saturday, though brief periods of MVFR/IFR conditions are possible through the day on Saturday in any SHSN. Winds shift SW on Saturday at around 5 kts.

Saturday night: MVFR at northern terminals as snow showers taper off. Generally VFR southern terminals. NW winds at 5-15 kts. Slight chance for LLWS late Saturday night/early Sunday morning.

Sunday - Monday: Becoming VFR throughout Sunday morning. NW winds with gusts 15kts possible Sunday. Winds shift to the S Monday, at 5-10 kts.

Monday night - Tuesday: MVFR or lower possible at northern terminals, due to snow showers. S winds at 5-10 kts.

MARINE

Winds continue to decrease across the waters this morning, having fallen below 25 kts on the intracoastals and with gusts 25 to 30 kts on the coastal waters early this morning. As winds diminish, the small craft advisory on the coastal waters will end at 10 AM this morning. Winds and seas will remain below advisory criteria tonight through the day on Saturday. Light freezing spray possible this morning.

Potential for low-end Small Craft conditions over all waters Sunday, ending overnight. Potential for another Small Craft Wednesday night into Thursday night. Light freezing spray early Sunday morning. Potential for some snow Sunday. Rain possible Tuesday and Wednesday.

CAR WATCHES/WARNINGS/ADVISORIES

ME...None. MARINE...Small Craft Advisory until 10 AM EST this morning for ANZ050- 051.