textproduct: Caribou

WHAT HAS CHANGED

- Key message added for potential frost Tuesday night. The frost/freeze program starts over Bangor and Downeast zones on Monday.

KEY MESSAGES

1) Rain for southeastern areas tonight will transition to numerous showers and isolated thunderstorms across most of the area Sunday.

2) Dry conditions are expected Tuesday and Wednesday, giving the region a break from frequent rainfall.

3) Potential for frost over the Downeast region Tuesday night, which could impact sensitive crops.

DISCUSSION

KEY MESSAGE 1...Rain for southeastern areas tonight will transition to numerous showers and isolated thunderstorms across most of the area Sunday.

KEY MESSAGE 1 DESCRIPTION... A broad and slow moving upper level trough over the Hudson Bay extending south towards the Great Lakes will continue to provide unsettled weather and direct waves of subtropical moisture northward towards Maine. The first wave tonight will be from the merger of the polar and subtropical jets over the Mid- Atlantic, which is currently producing a broad area of rain from West Virginia into southern Maine. Precipitation will overspread the area this evening, mainly affecting areas along and southeast of interstate 95. Precipitation amounts up to a half inch are possible through Sunday morning over these areas.

Meanwhile, a stronger shortwave trough will be rounding the base of the longwave trough over the northern Great Lakes into western Quebec, forcing a stronger area of low pressure to deepen and direct a cold front towards the area on Sunday. This will be more convective and showery compared to the overnight precipitation, and will also be located more over the north in general. CAPE is forecast to be limited to a few hundred joules. Although mid-level lapse rates are not as favorable as when small hail was observed in stronger convective showers this past Thursday and Friday, there is still potential for small hail due to the low freezing levels and CAPE/convective air parcels reaching the -20C level. Similarly, some of the stronger cells could produce lightning strikes, so isolated thunderstorms are forecast across much of the area away from the Downeast marine layer.

Patchy fog is also possible, especially Sunday night to the south and east of interstate 95 as winds diminish and soil moisture remains elevated from recent rain and ongoing showers. Most fog should move to the east by Monday morning, but some impact to the Monday morning commute is possible, especially across coastal Washington county. The continued wet weather pattern will lead to continued mitigation of the long term drought.

KEY MESSAGE 2...Dry conditions are expected Tuesday and Wednesday, giving the region a break from frequent rainfall.

KEY MESSAGE 2 DESCRIPTION... Slight ridging pattern builds in at the surface, with a mid- level shortwave moving through on Tuesday. Ridging helps to clear out skies, with a potential for some breezy and dry conditions during the day. This will be a break from repeated rainfall the past week throughout the region, especially with growing season upon us. Skies become partially cloudy by Tuesday afternoon. Dry conditions persist through Wednesday, as high pressure moves east over the region. Daytime highs in the low-to-mid 50s in the north, and mid-to-upper 50s Downeast on both Tuesday and Wednesday. Overnight lows Tuesday in the 30s.

KEY MESSAGE 3...Potential for frost over the Downeast region Tuesday night, which could impact sensitive crops.

KEY MESSAGE 3 DESCRIPTION... Partially cloudy skies with cool overhead air mass results in a chilly Tuesday night, with low temperatures reaching just above freezing, causing a potential for some frost development. Frost can impact any crops recently planted, so plan accordingly to protect agriculture.

AVIATION /18Z SATURDAY THROUGH THURSDAY/

Through tonight... VFR this evening, lowering to MVFR/IFR with -RA and -SHRA. LIFR is possible, mainly late tonight and at terminals along and S/E of a line extending from GNR to MLT to HUL. LLWS is also forecast over these areas tonight. South winds 5 to 10 kts with gusts 15 to 20 kts.

Sunday... MVFR/IFR with some VFR possible at northern and western terminals later in the day.

Sunday Night... VFR at northern and western terminals, MVFR/IFR for terminals southeast of I-95. For terminals along I-95 such as KBGR, KMLT, and KHUL, confidence is lower because of uncertainty in the NW edge of lower clouds. Light and variable winds.

Monday - Monday night...MVFR/VFR. Chance of rain showers at all terminals during the afternoon into evening periods. W winds 5-10kt, shifting NW overnight.

Tuesday - Tuesday night...VFR, slight chance of MVFR ceilings during the afternoon at northern terms. NW winds 5-15kt, with gusts to 20kt possible during the afternoon. Winds shift W and relax overnight.

Wednesday - Wednesday night...VFR during the day. MVFR overnight as showers begin to move in, south to north. W/SW winds 5-15kt. Shift S/SE overnight.

Thursday...MVFR with rain showers. S winds at 5-10 kts. Wind gusts 15-20 kts possible during the afternoon.

MARINE

Winds and seas will increase to advisory thresholds over all coastal waters this evening with gusts to around 25 kts and seas up to 6 feet. Winds and seas decrease below advisory levels Sunday afternoon into Sunday evening. Similar conditions are expected over the 25 to 60NM waters where marine wind/wave advisories are not issued by policy.

Winds generally stay below Small Craft criteria early next week. Outer waters do have 5ft seas for a period during the day on Monday, but fall below 5ft by Tuesday. Rain on Monday, and again Wednesday night. Winds NW Monday, shifting SW during the day, and back to NW by evening. Winds shift W by Tuesday.

CAR WATCHES/WARNINGS/ADVISORIES

ME...None. MARINE...Small Craft Advisory from 8 PM this evening to 11 PM EDT Sunday for ANZ050. Small Craft Advisory from 8 PM this evening to 8 PM EDT Sunday for ANZ051. Small Craft Advisory from 8 PM this evening to 2 PM EDT Sunday for ANZ052.