textproduct: Caribou

WHAT HAS CHANGED

- Confidence has increased on convective snow showers today and tonight.

KEY MESSAGES

1) Heavy snow showers possible this morning through tonight, mainly in northern Maine. This may create slippery road conditions.

2) Unseasonably cold temperatures expected tonight and Tuesday night.

3) Low RHs expected Tuesday and Wednesday which may lead to increased fire weather concerns.

DISCUSSION

KEY MESSAGE 1...Heavy snow showers possible this morning through tonight, mainly in northern Maine. This may create slippery road conditions.

KEY MESSAGE 1 DESCRIPTION... As the cold front exits to the east today. Instability will increase. Though winds will be breezy today, snow squall are not a concern. However, scattered to isolated snow showers are expected. Due to the high CAPE, steep lapse rates, and negative potential temp, heavy convective snow showers are likely to develop mainly north of the Bangor Region.

By tonight, lingering instability due to the exiting shortwave energy coupled with the NW winds will likely produce Laurentian plumes. The high res models and deterministic models show good agreement on convective shower development tonight. Again, the low wind speeds will not meet snow squall criteria, but heavy snow showers in a short period of time is possible.

KEY MESSAGE 2...Unseasonably cold temperatures expected tonight and Tuesday night.

KEY MESSAGE 2 DESCRIPTION... A cold airmass will begin filling in behind the departing cold front as high pressure builds in from the west. Temperatures are currently expected to be about 10 to 15 degrees below normal. The coldest night will be Tuesday night with single digit readings common across northern areas, with some areas in the North Woods region possibly approaching 0 degrees in the normally coldest valley locations. Expect temperatures in the teens across interior Downeast areas, with upper teens to around 20 along the Downeast coast.

KEY MESSAGE 3...Low RHs expected Tuesday and Wednesday which may lead to increased fire weather concerns.

KEY MESSAGE 3 DESCRIPTION... Low RHs, breezy winds, and mostly sunny skies may lead to some increased fire weather concerns Tuesday and Wednesday with the greatest risk Wednesday.

On Tuesday, high pressure building in from the west will result in subsidence across the area with a mix of sun and clouds allowing for mixing up to 800mb. With ample dry air aloft, this is likely to result in dry conditions near the surface with RH around 30%, especially in the Bangor region and Upper Penobscot Valley. Questions still remain as to just how low RHs will drop depending on if a weak clipper moving just offshore brings any precipitation to southern areas. In this case, light snow and clouds may prevent significant fire weather concerns.

High pressure slides to the south of Maine Wednesday resulting in W/SW flow across the area under a strong subsidence inversion with ample dry air aloft. Deep mixing up to 800mb combined with mostly sunny skies, especially further south, should contribute to very low RHs, likely below 30%. Winds will not be near Red Flag criteria but will still be breezy with gusts up to 15 to 20 mph.

AVIATION /07Z MONDAY THROUGH FRIDAY/

Today...Mainly VFR with brief MVFR in north terminals due to snow showers. VFR for south terminals. W winds 10-15 kts with gusts up to 25 kts.

Tonight...Mainly VFR with brief MVFR in north terminals due to snow showers. VFR for south terminals. NW winds 5-10 kts.

Tuesday...VFR for north terminals. Mainly VFR with brief MVFR in south terminals due to snow. NW winds 5-10 kts.

Tuesday night...Occasional MVFR possible early with a slight chance of snow showers. Otherwise, VFR. Northwest/west winds 5 to 10 knots, becoming west/southwest.

Wednesday through Thursday...VFR. West/southwest winds 10 to 15 knots with gusts up to 20 knots Wednesday. South/southwest winds 5 to 10 knots Wednesday night. South winds 10 to 15 knots with gusts up to around 20 knots Thursday.

Thursday night...VFR/MVFR north. VFR Downeast. South winds around 10 knots.

Friday...VFR/MVFR north with a chance of showers. Across Downeast areas, a slight chance of showers and MVFR late. Otherwise, VFR. South winds 10 to 15 knots with gusts up to 20 knots.

MARINE

A Small Craft Advisory remains for all waters through this afternoon before conditions drop below SCA levels through Tuesday.

Small craft advisory conditions Tuesday night. Conditions below small craft advisory levels Wednesday/Wednesday night. A chance of snow early Tuesday night.

CAR WATCHES/WARNINGS/ADVISORIES

ME...None. MARINE...Small Craft Advisory until 2 PM EDT this afternoon for ANZ050>052.