textproduct: Caribou

WHAT HAS CHANGED

- Slight chance for some thunderstorms over the Downeast region Monday evening

- Confidence increasing in significant rain areawide late Tuesday to Wednesday evening.

KEY MESSAGES

1) A slight chance of thunderstorms Monday afternoon and Tuesday afternoon.

2) Significant rain Tuesday night through Wednesday evening, with another round of rain possible Thursday night and Friday. The rain will provide continued improvement to drought conditions, and is not expected to lead to flooding.

DISCUSSION

KEY MESSAGE 1...A slight chance of thunderstorms Monday afternoon and Tuesday afternoon.

KEY MESSAGE 1 DESCRIPTION...As low pressure system departs this evening near Nova Scotia, brief period of ridging builds in from the west on Monday. This ridging bring a brief period of clearing, from west to east during the morning. CAMs models are indicating some instability parameters, such as 100-500 J/kg of CAPE, 100-300 SRH, low and mid level lapse rates around 7-8 C/km. Sounding analysis indicates decent low-level shear as well, hinting at an inverted V sounding, with a dry surface. Majority of instability is located in the Bangor, Upper Penobscot Valley, and Downeast regions. Not anticipating anything major, but could see some gusty winds and hear some thunder rumbles. Storms anticipated Monday afternoon through late evening.

Again on Tuesday afternoon/early evening, we are looking at a slight chance of thunderstorms. For Tuesday, with a cold front and upper level trough approaching from the west. It will be a warm and breezy day, with highs in the low to mid 70s inland. The greatest risk of storms will be in the western portions of the area, mainly north/west of I-95. Decent instability with CAPE probably over 500 J/kg in places, and reasonable wind shear, mostly directional. Can't rule out a couple storms having some decent wind gusts. But putting it into perspective, this is a very small risk, but worth mentioning since we haven't really had any thunderstorm activity yet this season. Even if we don't get any thunderstorm development, we are likely to see significant rain moving in Tuesday night into northern areas (see key message 2 below).

KEY MESSAGE 2...Significant rain Tuesday night through Wednesday evening, with another round of rain possible Thursday night and Friday. The rain will provide continued improvement to drought conditions, and is not expected to lead to flooding.

KEY MESSAGE 2 DESCRIPTION... Period of unsettled weather throughout the upcoming week, bringing rain showers throughout the region. Rain continues over the east and Downeast region tonight, with far Downeast region seeing an additional quarter of an inch of rain accumulation tonight. On Monday, another round of showers are possible in the Bangor, Upper Penobscost Valley, and Downeast regions. Precipitation totals will be light, but could be locally higher values up to a tenth of an inch in areas that convective storms develop. Based on flash flood guidance and soil moisture levels, neither of these systems are anticipated to cause any flooding concerns.

The cold front mentioned in key message 1 moves into Northern Maine Tuesday night, then creeps southeast through the area Wednesday into Wednesday evening. Moist southwest flow aloft will allow for significant rain focused around the position of the slow-moving cold front. Although slow-moving, the front does appear to be moving enough to where there won't be enough rain for flooding anywhere. Earlier in the Tuesday night-Wednesday evening period, the heavier rain will be over Northern Maine, while in the latter part of this period, the focus shifts more Downeast. There is a bit of uncertainty in timing of the start/end of the rain, but not too bad. Storm total rainfall from late Tuesday through Wednesday night looks to be roughly in the neighborhood of an inch. Most areas should get at least 0.5 inch, and some places could get as much as about 1.75 inches.

Late Wednesday night and Thursday, we may get a bit of a break in the significant rain, though we can't rule out some showers still being around.

Heading into Thursday night and Friday, a new low pressure develops offshore and passes south/east of the area. Many models have it getting close enough to bring another shot of rain to much of the area. However, many other solutions keep us dry with the system passing too far south. There is a slightly greater chance of rain (60 percent) than having no rain (40 percent). There is a 30-50 percent chance of exceeding 0.25 inch of rain, with the highest chances Downeast, closer to the low pressure track.

AVIATION /18Z SUNDAY THROUGH FRIDAY/

This evening - Tonight...MVFR with low cloud ceilings and rain showers at all terminals. Ceilings begin to lift by tonight, returning to VFR by tonight. Winds from the N, shifting to the WNW tonight, blowing 10-15 kts at northern terminals, and gusting 20-25kts at southern terminals.

Monday - Monday Night...VFR in the morning, becoming MVFR at northern terminals due to scattered rain showers. MVFR most likely at KHUL, KBGR, and KBHB. Slight chance for thunderstorms at KBGR and KBHB Monday evening. VFR Monday night. Winds W/SW Monday, gusting to 25kts. Becoming S Monday night.

Tuesday...Generally VFR, with local MVFR possible in the afternoon with any showers or storms, mainly in the north. S wind gusting 25-30 kts in the afternoon.

Tuesday Night - Wednesday Night...Becoming MVFR/IFR most places Tuesday night, and remaining MVFR/IFR into Wednesday evening, then perhaps improving to VFR late Wednesday night. S wind 10-15 kts shifting to the NW later Wednesday night.

Thursday...VFR with possible MVFR. W wind 5-10 kts.

Thursday Night and Friday...Low confidence. MVFR/IFR possible if a system tracks close enough to bring rain, but VFR also possible if the system stays offshore. NW wind around 10 kts.

MARINE

Small Craft conditions over outer waters begin this evening, and persist into Tuesday. Small craft conditions over intra-coastal waters this evening, and improve by Monday morning. Gale conditions over outermost waters tonight. Seas up to 5 ft for intra-coastal waters, and 8 ft over outer-waters Monday night. Rain expected this evening, and again Monday evening. Winds from the N this evening, shifting SW Monday, shifting S/SW Monday night.

Gale force S winds likely Tuesday night into Wednesday, with a 75 percent chance for outer waters, although the chance is only about 25 percent for the intra-coastal waters. Seas around 10 ft for all but the intra-coastals. Significantly decreases winds/seas Thursday, with a possible increase Friday depending on the track of a low pressure system.

CAR WATCHES/WARNINGS/ADVISORIES

ME...None. MARINE...Small Craft Advisory until 8 AM EDT Tuesday for ANZ050-051. Small Craft Advisory from 11 PM this evening to 6 AM EDT Monday for ANZ052. Gale Warning from 11 PM this evening to 6 AM EDT Monday for ANZ080-081.