textproduct: Caribou

WHAT HAS CHANGED

- Changed precipitation to stratiform for tonight into Sunday AM due to the overrunning warm front setup.

- Added isolated thunder across the coastal waters and far Downeast later tonight on the NE forward side of the coastal low pressure system.

KEY MESSAGES

1) Widespread rain tonight into Monday will help ease ongoing drought conditions in some areas. Rain may be heavy at times tonight into Sunday, especially across Downeast Maine.

2) Upper level low pressure keeps the chance of showers going into midweek, especially across Northern Maine.

DISCUSSION

KEY MESSAGE 1...Widespread rain tonight into Monday will help ease ongoing drought conditions in some areas. Rain may be heavy at times tonight into Sunday, especially across Downeast Maine.

KEY MESSAGE 1 DESCRIPTION... A surface low pressure system developing off the Mid Atlantic coast this morning will progress north today into the Gulf of Maine. As a warm front lifts north ahead of the low expecting overrunning rainfall to develop into the region late this afternoon into tonight. The CAMs are starting to hone in on the best path of the steady rain and a good timing. Expect rain to begin along the coast late afternoon into the evening and push NNE through tonight. The question for tonight will be how much rainfall will occur, especially for areas in the north. Unfortunately, there remains significant differences in the ensembles as of this update. Models do agree the PWATs tonight with this surge of moisture on the warm front increases to 1.3-1.8 inches which is 140-180% of normal. Potential exists for 0.5-1 inch of rain tonight in Washington County with significantly less rainfall north and west. However, confidence in low to moderate on where the heaviest rain will be. Any rainfall will be helpful to ongoing drought conditions given that we will be in a cloudy cool pattern for the next couple days. This will allow for rainfall to get into the soils, unlikely to help streamflows which are significantly below normal.

After midnight, the center of the low will be over Downeast and becomes absorbed by the approaching occluded front from the west and a vertically stacked low pressure system. The low centered over the Great Lakes will progress E over New England. By Sunday, expect widespread showers continuing throughout the day. Modeled PWATs increase to 1.8-2.2 inches since we will be within a warm sector and significant moisture advection from the tropical Atlantic. Given the 160-180% of normal PWATs (95-99th percentile) and showers may produce heavy at time rainfall. Showers will be more convective during the day so uncertain where the beneficial rainfall will occur. Then throughout Sunday night, the low becomes stationary over Quebec as it rotates the moisture through the state. By Monday, the low begins to gradually move north which will decrease rain chances throughout the day. However, best chance of showers and thunderstorms will be in the northern 1/2 of the CWA closer to the vertically stacked low in Quebec.

KEY MESSAGE 2...Upper level low pressure keeps the chance of showers going into midweek, especially across Northern Maine.

KEY MESSAGE 2 DESCRIPTION... There remains blocking in the North Atlantic (-NAO) into the end of August. Upper level low pressure to our north in Quebec continues to slowly drift east towards the Maritimes. Partly to mostly sunny skies with cool pool aloft on Tuesday will lead to significant cu build up especially in the northern 2/3rd of the CWA. Expecting some daytime instability, around 500j/kg of SBCAPE, so widespread showers and some thunderstorms are expected to develop. Very little if any showers expected south of The Airline (Route 9). The upper level low north of the Gaspe Peninsula on Wednesday will reduce the precip chances to just northern Maine and mostly dry elsewhere with highs getting to 2-5 degrees above normal for this time of year.

AVIATION /06Z SATURDAY THROUGH WEDNESDAY/

Rest of Tonight (Through 12z)...VFR. BCFG or low ground FG may reduce vsby at PQI, HUL. Low confidence in vsby reductions at CAR and FVE along with BGR and BHB. Winds light and variable.

Today...Mainly VFR with high cigs. Late this afternoon BHB/BGR becoming MVFR with increasing cigs. VCSH/RA develops from S to N late day. E-SE winds 5-10kt.

Tonight: Becoming IFR or lower at all terminals in rain. E-SE winds G15-20KT possible.

Sunday-Monday: IFR or lower likely. Slight chance for thunderstorms Sunday night and again Monday afternoon. S-SW winds G15-20KT possible Monday.

Monday night-Wednesday: MVFR or lower likely at northern terminals. MVFR possible at KBGR, with VFR likely at KBHB. LLWS possible Monday night. W-NW winds G15-20KT possible Wednesday.

MARINE

Winds generally below 20 kt through Saturday night, though east winds approach 25 kt over 25-60NM waters Saturday afternoon/evening. Seas build to 2-4 ft with highest seas over the waters from 25-60nm Saturday evening. Patchy fog and rain may reduce visibilities to 1-3NM.

Slight chance of winds or seas reaching 25 kts/5 ft Monday- Tuesday. Fog likely the next few nights. A chance for thunderstorms on Sunday and Monday.

CAR WATCHES/WARNINGS/ADVISORIES

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