textproduct: Caribou

WHAT HAS CHANGED

-Updated aviation discussion.

KEY MESSAGES

1) Light snow likely across southwest and Downeast portions of the forecast area tonight into Saturday morning.

2) Increasing chances for a measurable snowfall and strong gusty winds across at least portions of Downeast Maine Monday and Monday night.

3) Snow likely, except for possibly a rain/snow mix at the coast from late Wednesday/Wednesday night, becoming a rain/snow mix or all rain across most of Eastern Maine Thursday. This could impact the Wednesday evening and Thursday morning commute.

DISCUSSION

KEY MESSAGE 1... Light snow likely across southwest and Downeast portions of the forecast area tonight into Saturday morning.

KEY MESSAGE 1 DESCRIPTION... A frontal boundary, between weakening low pressure across the Great Lakes and an intensifying ocean low exiting south of the Gulf of Maine, will remain nearly stationary tonight into Saturday. At the same time, high pressure centered across northern Quebec province will ridge southward toward the forecast area. Light overrunning snow should expand across mostly Downeast/southwest portions of the forecast area tonight. Light snow should then persist overnight, tapering to snow showers Saturday morning. Total snow accumulations across Downeast/southwest portions of the forecast area tonight into Saturday morning should generally range from 1 to 3 inches. This snow could impact travel. High pressure ridging toward the region from the north, should help minimize any potential snow accumulations across northern portions of the forecast area.

KEY MESSAGE 2... Increasing chances for a measurable snowfall and strong gusty winds across at least portions of Downeast Maine Monday and Monday night.

KEY MESSAGE 2 DESCRIPTION... 00z models have tracked the coastal low for early next week a bit closer to, but still well south of, the Gulf of Maine. As a result, the confidence of at least measurable snowfall across portions of Downeast Maine and the potential for strong gusty winds at least near the coast, has increased in the Monday/Monday night time frame.

Consensus is growing that the closed 500mb low driving this system will be south of Cape Cod/east of Cape May at 12Z Monday, track to southeast of Cape Cod by Monday evening, then to the vicinity of Eastern Nova Scotia by Tuesday morning. The associated surface low tracks south of the Gulf of Maine on Monday, then south of Nova Scotia Monday night (the question is how far south).

Two things are most certain: 1) That a tight pressure gradient between this low and a high to its northwest will produce gusty winds over the region Monday/Monday night, strongest over Coastal Downeast Maine. 2) That any precipitation will be in the form of snow, except for possibly a rain/snow mix near the immediate coast.

What is less certain is how far inland (if at all) any precipitation associated with this system will get on Monday, then as at tracks into the Maritimes Monday night, how far to the NW behind the low will its precipitation shield be. For now precipitation Monday night will most likely be limited to far SE Maine, but there is a slight chance that it could work its way up the eastern Border with Canada into Eastern Aroostook, especially near the border. At this time, all that can be said with any certainty with regard to snow fall is that the chances are increasing for measurable snowfall (so at least 0.1 inch) across at least parts of Downeast Maine.

At this time, with the winds with this system forecast to be first parallel to the coast, then offshore, there should be limited if any risk of coastal flooding and.or beach erosion with this system.

KEY MESSAGE 3... Snow likely, except for possibly a rain/snow mix at the coast from late Wednesday/Wednesday night, becoming a rain/snow mix or all rain across most of Eastern Maine Thursday. This could impact the Wednesday evening and Thursday morning commute.

KEY MESSAGE 3 DESCRIPTION... Diffluent flow aloft Wednesday afternoon/evening gives way to a northern stream shortwave during the overnight hours, followed by the main 700-500 mb northern stream trough axis crossing the areas Thursday/Thursday night. At the surface low pressure tracks into Western Quebec by Thursday morning, this low tracks to the north Thursday and northeast Thursday night, bringing its surface warm front through during the day on Thursday and cold front through Thursday night. However, there is a small chance that a secondary low develops southeast of the Maine low, preventing Maine from getting into the warm sector.

For now, expect snow to develop Wednesday afternoon, and become more widespread and possibly become moderate in intensity Wednesday night. During the day on Thursday think that coastal Downeast Maine changes to all Rain, with a rain/snow mix from Southern Aroostook down into the Bangor Region, with snow elsewhere. Precipitation then tapers off as showers Thursday night with the passage of the cold front.

For now, there is the potential for a light to moderate snow accumulation before any change over, so depending on how quickly the snow begins to fall it could impact the Wednesday evening commute, but even more likely impact the Thursday morning commute.

AVIATION /12Z FRIDAY THROUGH TUESDAY/

Across northern areas, VFR today through early Saturday. VFR/MVFR Saturday afternoon. Across Downeast areas, VFR today. MVFR/IFR, occasional LIFR, tonight with light snow. VFR/MVFR with a chance o snow showers early Saturday, then VFR. Variable winds 5 to 10 knots, becoming north/northeast today. North/northeast winds around 10 knots tonight. North winds 10 to 15 knots with gusts up to around 20 knots Saturday.

Saturday night: Becoming VFR. N wind G15-20KT and LLWS possible Saturday evening.

Sunday-Sunday night: VFR. E wind G15-20KT possible at southern terminals Sunday night.

Monday-Monday night: VFR at KFVE, with very low chance of MVFR or lower at remainder of northern terminals. Low chance at KBGR and low to moderate chance at KBHB of MVFR or lower. NE-N wind G15-25KT possible N terminals and G25-35KT likely southern terminals. Winds probably becoming NW and decreasing to G15-25KT throughout during Monday night.

Tuesday: Becoming VFR throughout. NW winds G15-25KT possible.

MARINE

Winds/seas below small craft advisory levels today. A Small Craft Advisory has been issued for much of the waters, with the exception of the intra-coastal waters, from 9 PM this evening through Saturday. On the intra-coastal waters, a Small Craft Advisory has been issued from 9 PM this evening til 5 PM Saturday. Light snow tonight. A chance of snow showers early Saturday. Light freezing spray tonight into Saturday.

SCA conditions expected on the coastal ocean waters Saturday night, so have extended the SCA through then there. For now it looks like the intra-coastal waters will experience sub-SCA conditions Saturday night. SCA conditions could linger on the coastal ocean waters on Sunday.

Gales likely on the coastal ocean waters late Sunday night into Monday night and possible on the intra-coastal waters. The gales could linger into Tuesday on the coastal ocean waters with SCA conditions probable on the intra-coastal waters.

CAR WATCHES/WARNINGS/ADVISORIES

ME...None. MARINE...Small Craft Advisory from 9 PM this evening to 5 AM EST Sunday for ANZ050-051. Small Craft Advisory from 9 PM this evening to 5 PM EST Saturday for ANZ052.