Grand Isle, ME 04746 Weather

What has changed

- 8 PM Update with the issuance of the 00z TAFs. Slight increase in PoPs over the next couple of hours based on current radar observations and trends.

- Increased chances of showers this evening and tonight.

Key messages

1) Generally dry weather through early next week. Drought conditions will worsen.

Discussion

KEY MESSAGE 1: Generally dry weather through early next week. Drought conditions will worsen.

KEY MESSAGE 1 DESCRIPTION: This evening cold air advection from the exiting cold front will rapidly increase. With gradually clearing skies and NW flow, any rain showers leftover will likely switch to snow showers. High pressure returns through the weekend, keeping the pattern dry. Models are slowing a low pressure system to our west, now show the cold front to cross the region sometime late week. Upper air model soundings indicate a very dry boundary layer, which any precip will need to fight against to make it to the ground. Overall, no improvement to drought conditions are expected with these showers.

Deep layered ridging builds in Sunday through at least Wednesday and possibly into Thursday. There is some question if a northern stream shortwave passing over the top of the ridge will bring some rain to the Crown of Maine from Monday night into Tuesday night as it passes, along with a weak surface warm front. Even if there is rain, it should be less than 1/4" with no impact to the drought. Especially noting that stream flows and groundwater levels remain below to well below normal across a large portion of the region.

The main impact of the ridging building in will be a gradual moderation of temperatures with continued dry weather. Highs increase from the low to mid 50s on Sunday to mid 50s to mid 60s on Monday. Depending on the extent of cloud cover/moisture associated with the passing northern stream shortwave Monday night/Tuesday. Tuesday could end up cooler than Monday, but temperatures then increase into Thursday to levels close to those forecast for Monday.

There is still quite a bit of uncertainty as to how fast the deep layered ridge exits to the east late this week. This will ultimately determine when the next storm system impacts the region. Given the highly amplified nature of the flow, the slower solutions make more sense overall. So it would not be surprising if the chances of rain on Friday end up getting pushed back into the weekend. Given this uncertainty, it is to soon to specify what if any impact this system could have on the region.

Fortunately winds are expected to remain relatively light and minimum relative humidities generally above 45% through this time frame, so there are minimal if any fire weather concerns through the end of the work week.

Aviation

Tonight: Mainly VFR conditions with possible brief MVFR in the north in rain showers early. NW winds 5 to 15 kts with a few gusts up to 25 kts.

Saturday-Saturday night: VFR conditions for all terminals. NW winds 5-10 kt.

Sunday-Monday: VFR. WSW winds G15-20KT possible Sunday and again Monday afternoon.

Monday night-Tuesday: Chance of MVFR in any rain at northern terminals, otherwise VFR.

Tuesday night-Wednesday: VFR.

Marine

A Small Craft Advisory has been issued for this afternoon into Saturday afternoon. Winds for the intercoastal and coastal waters are expected to reach 25-30 kt through this period with seas 1-4 ft. Over the waters 25-60nm a few NW gusts tonight into Sat AM may approach 35kt but prolonged Gales are not expected at this time. Seas 4-6 ft.

For the coastal waters, other than possibly some gusts to around 25 kt on the coastal ocean waters Sunday night, sustained winds of 15 kt or less and seas of 4 ft or less are forecast Sunday- Wednesday. For the outer waters sustained winds of 20 kt or less and seas of 5 ft or less are forecast during the same time frame.

Watches, warnings and advisories

ME: None. MARINE: Small Craft Advisory until 2 PM EDT Saturday for ANZ050>052.