textproduct: Caribou

WHAT HAS CHANGED

- Updated aviation discussion for the 12z TAFs. Reduced coverage of fog and removed mention in key message 1 based on satellite/obs this morning and the expectation that remaining fog will lift and dissipate shortly.

- Decreased thunderstorm probs slightly Friday due to concerns about persistent rain and cloud cover limiting heating.

KEY MESSAGES

1) Showers and thunderstorms develop today, mostly this afternoon. The most extensive showers and thunderstorms are expected across northern and central areas. Small hail is possible with any thunderstorms.

2) Unsettled weather through the weekend with showers and thunderstorms each day, mostly in the afternoon.

DISCUSSION

KEY MESSAGE 1...Showers and thunderstorms develop today, mostly this afternoon. The most extensive showers and thunderstorms are expected across northern and central areas. Small hail is possible with any thunderstorms.

KEY MESSAGE 1 DESCRIPTION... At the surface, low pressure will exit across the Maritimes today with a trof extending back across the forecast area. Aloft, an upper low will cross northern areas today. Diurnal heating, along with the surface trof and cold pool aloft with the upper low, will help support developing showers and thunderstorms later this morning into the afternoon. The most extensive showers and thunderstorms will occur across northern and central portions of the forecast area. With the cold pool aloft, small hail could accompany any thunderstorms. Showers and thunderstorms then diminish early tonight with the loss of diurnal heating and exiting upper low. Another chance of mostly afternoon showers and thunderstorms will occur tomorrow.

KEY MESSAGE 2...Unsettled weather through the weekend with showers and thunderstorms each day, mostly in the afternoon.

KEY MESSAGE 2 DESCRIPTION... Low pressure over the Great Lakes region Thursday will move east Thursday night through early Friday towards Maine with a cold front passing through the area late Friday. The approaching low pressure should favor the development of rain showers and thunderstorms Thursday and Friday with the greatest chance for storms Friday. Strong lift ahead of the approaching cold front should aid in storm development but models show rain and clouds Thursday night persisting into early Friday which could limit heating and instability. Additionally, the southerly flow may favor more stable conditions Downeast as the marine layer is advected inland. Thus, opted to decrease thunder probs slightly. There is still disagreement in the models as to how strong the low pressure will be and when the cold front passes so will have to monitor trends to see how storm risk changes. Weak waves of low pressure approaching the area this weekend should favor showers and storms through Sunday. Shear is generally modest each day so not expecting significant storms but a few strong multicells are possible.

AVIATION /12Z WEDNESDAY THROUGH SUNDAY/

Today: MVFR at northern terminals this morning with IFR briefly possible prior to 13-14z at PQI and HUL. Ceilings lift to VFR late this morning and early afternoon while -SHRA and scattered TSRA develop. TSRA may produce small hail and briefly lower flight categories. VFR with less coverage of -SHRA at southern terminals including KBGR and KBHB. Variable winds 5 to 10 knots, becoming northwest/west around 10 knots.

Tonight: Mainly VFR with -SHRA early. MVFR/IFR possible in patchy low clouds and fog, especially late. Light northwest/west winds.

Thursday: Variable conditions with any fog early. Otherwise, VFR early. VFR/MVFR during the afternoon with a chance of showers and thunderstorms. Northwest/west winds 5 to 10 knots, becoming variable.

Thursday night: VFR/MVFR early, then MVFR/IFR occasional LIFR. Showers likely along with a chance of thunderstorms. Southeast/east winds 5 to 10 knots.

Friday-Saturday: VFR, except for MVFR or lower possible in any showers and possible thunderstorms, mainly at northern terminals and mostly in the afternoon. Winds generally 5 to 10 kts out of the S Thursday-Friday, becoming NW Saturday. Light and variable winds each night.

Sunday: MVFR in rain showers and possible afternoon thunderstorms. NNW winds 5-10 kts.

MARINE

Winds/seas below small craft advisory levels today through Sunday. Patchy fog this morning and tonight into Thursday morning.

CAR WATCHES/WARNINGS/ADVISORIES

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