textproduct: Caribou

WHAT HAS CHANGED

- Increased high temperatures for Monday under same airmass. Temps were well above guidance for Sunday and expect this to continue for Monday.

KEY MESSAGES

1) Warmer and dry conditions continue through Tuesday, winds increase on Tuesday for a fire weather concerns.

2) Significant rainfall is possible Thursday into Friday to be beneficial for the ongoing groundwater drought.

DISCUSSION

KEY MESSAGE 1...Warmer and dry conditions continue through Tuesday, winds increase on Tuesday for a fire weather concern.

KEY MESSAGE 1 DESCRIPTION... The axis of the mean northern stream trough over the eastern U.S. slowly passes to the east through tonight. This develops into a closed low off the mid-Atlantic/New England coast on Monday, as deep layered ridging approaches from the west. At the surface, high pressure builds over the region through Monday, as a coastal low tracks well south of Long Island/Cape Cod through tonight, then well south of the Gulf of Maine on Monday. Mix of sun and clouds on Monday with high temperatures in the low to mid 60s areawide except along the Downeast coast where a weak seabreeze in the afternoon keeps coastal locations in the upper 50s. Afternoon relative humidities dip into the upper 30s to near 40 percent with 45-60 percent along the shore. Winds are thankfully light and variable so fire weather concerns are minimal.

The 500mb ridge axis will move directly overhead on Tuesday afternoon with mostly sunny skies. 500mb temperatures are forecast to range from 3 to 5 C across the forecast area, which mixed to the surface would yield temperatures in the mid to upper 60s. A modest south-southeast wind will develop, which will transport cooler maritime air inland and limit high temperatures to the 50s closer to the coast. Forecast soundings also indicate very dry air within and at the top of the mixed layer. Major adjustments were needed to the NBM dew points, especially away from the coast. The combination of preceding dry weather, relative humidity around 20 percent, and a light to modest breeze may lead to fire weather conditions Tuesday afternoon away from the coastline.

KEY MESSAGE 2...Significant rainfall is possible Thursday into Friday to be beneficial for the ongoing groundwater drought.

KEY MESSAGE 2 DESCRIPTION... Broad upper level troughing pivots over the Great Lakes into Ontario during the middle of the week. At the same time ridging will erode over Maine Tuesday night into Wednesday and move northeast to just south of Greenland, creating strong blocking which will cause the trough progression to slow and eventually become cut-off. At first some lighter rain is possible Wednesday, especially along the coast, associated with a weak onshore push of moisture. The heaviest rainfall arrives Thursday into Friday associated with a low strengthening as it moves up the coast. Some timing differences in the ensemble guidance preclude a more definitive timeframe. Ample moisture is expected to be associated with this system as PWATs will be approaching the 90th percentile for this time of year. This should lead to ample rainfall with ensemble means showing somewhere around 2 inches in some locations with a few higher end solutions showing localized areas of 3 to 4 inches. Generally thinking that some of these higher end solutions will not come to fruition as freezing levels around 6 to 7kft will favor less efficient cold rain processes and there will likely not be any elevated convection. Currently thinking there may only be minor flooding concerns, especially given the persistent drought.

Heavier PWATs move east of the area by the weekend, but unsettled weather will continue with the upper level low likely to remain overhead and cause below normal temperatures and elevated chances for cloudier skies and showers.

AVIATION /00Z MONDAY THROUGH FRIDAY/

Tonight...FEW-SCT VFR. Light and variable winds.

Monday...SCT-BKN VFR. Light and variable winds. A SSE seabreeze develops at BHB and BGR 5-10kt late morning/early afternoon.

Tuesday: VFR. Light SSE winds increasing to 10-15 kt in the afternoon.

Tuesday night to Wednesday: VFR, becoming IFR at southern terminals Tuesday night and MVFR at northern terminals Wednesday with -SHRA and -DZ possible. Patchy FG also possible at southern terminals. SSE winds 5-15 kt.

Wednesday night: Variable conditions with periods of VFR and MVFR/IFR. E/SE winds 5-15kt. -SHRA or -DZ remain possible.

Thursday: MVFR/VFR, becoming MVFR/IFR late at southern and western terminals such as BGR and GNR with uncertainty in the onset timing of RA. E winds around 10 kt with gusts to 20 kt. LLWS possible.

Thursday night: Likely IFR in rain across most terminals. E winds 5-10 kts. LLWS possible.

Friday: MVFR/IFR in rain. Some uncertainty in how quickly rain moves out which will determine how long IFR conditions hold on. E wind 5-10 kts.

MARINE

Winds generally less than 15kt through Monday night with seas 1ft or less becoming 1-2ft Monday night. Seas increase to SCA criteria on the coastal waters Tuesday evening with winds reaching criteria Wednesday night. Winds and seas remain above SCA criteria through Friday. A 20% chance of gales on the outer waters and coastal waters Thursday night. Seas peak at 6 to 11 ft on the coastal and outer waters Thursday night.

Sea surface water temperatures range from 38-42F from the Downeast coast out 60NM and east to the Hague Line including Penobscot and Passamaquoddy Bays.

CAR WATCHES/WARNINGS/ADVISORIES

ME...None. MARINE...None.