textproduct: Caribou

WHAT HAS CHANGED

- Added some more details regarding thunderstorms this afternoon/evening, with growing concern for some damaging wind gusts from the Central Highlands through Downeast Maine.

- Also made some changes to the aviation and marine discussion, primarily to discuss this threat.

KEY MESSAGES

1) Thunderstorms expected across the Central Highlands, Bangor Region, and Downeast Maine this afternoon/evening, a few could be severe.

2) Cooler through the weekend, with a chance for showers and storms again this weekend.

DISCUSSION

KEY MESSAGE 1...Thunderstorms expected across the Central Highlands, Bangor Region, and Downeast Maine this afternoon/evening, a few could be severe.

KEY MESSAGE 1 DESCRIPTION... The upper-level low that is still spinning over the Quebec/Labrador region of Canada will push a potent piece of shortwave energy and surface cold front through the region today.

The cold front, currently located just NW of the St. Lawrence River, will push into northern Maine later this morning. Winds in the upper-levels in the wake of this front will again carry some smoke into northern Maine this morning into the afternoon hours as a result of new fire development on the southeast side of the Hudson Bay. These factors should keep the threat for any storms this afternoon rather low across these areas, especially with highs here struggling to get out of the 60s.

Further south, areas from the Central Highlands through Downeast Maine will be a different story. The cold front is expected to push through these areas early this afternoon through the early evening hours. High temperatures in these areas are expected to rise into the mid 70s to low 80s (warmest near the coast), with dew points into the mid 50s to low 60s (again highest near the coast). As a result, model guidance is pretty persistent with developing around 1000-1500 J/kg of MLCAPE over this region, with that gradient NW to SE from the Highlands to Downeast Maine. As the cold front drops into this environment, thunderstorms should develop over the Central Highlands and propagate towards the coast rather quickly. Looking aloft, there is a rather impressive low-mid level wind field, with 50-70 knots of 0-6km shear. Forecast soundings are generally in agreement that low-level lapse rates will be dry adiabatic into this strong wind field, and mid-level lapse rates aren't too unimpressive either, around 6 C/km. Storms would be more low- topped today, but you wouldn't need anything super tall to bring down some 50-60 mph wind gusts today, as suggested by some of the latest high-res model guidance. At present, the Storm Prediction Center has these areas under a marginal risk for severe weather, with damaging wind gusts the primary threat.

Storms would be out quickly though, with the consensus of model guidance pushing storms into the waters by 5-6 PM at the latest.

KEY MESSAGE 2...Cooler through the weekend, with a chance for showers and storms again this weekend.

KEY MESSAGE 2 DESCRIPTION... Temperatures remain on the cooler side, staying in the 70s through the weekend with nighttime lows in the 50s. The next chance for showers and storms is this weekend as low pressure moves in from over the Great Lakes. Thinking that since the greatest forcing will arrive overnight, thunderstorms are generally less likely although can't rule out some thunder with elevated instability Saturday night.

AVIATION /06Z THURSDAY THROUGH MONDAY/

Today...VFR with a chance of an hour or two of MVFR cigs from showers and possible storms mainly BGR/GNR/BHB. If this occurs, it would last only 1-3 hours and be roughly around 17-21z. Could see some erratic wind gusts with storms, but not confident on magnitude or direction to include them in the PROB30 group at this time. Could reasonably see 40-50 knots though if storms get well established. Otherwise, W winds 10-15 kts with gusts to 25 kts, becoming NW in the afternoon. One wildcard for today is smoke. There is about a 30 percent chance of smoke mainly N of BGR being thick enough to reduce visibility to MVFR levels during the day.

Thursday Night...Mostly VFR, but could drop into the MVFR range at FVE/CAR/PQI later in the overnight hours. W/NW wind 5-10 kts.

Thursday to Saturday: Mainly VFR with possible MVFR at times mainly in the north due to either cigs or afternoon showers/storms. Best chance for afternoon storms is Thursday. W winds 10-15 kts with gusts up to 25 kts.

Friday to Friday night...VFR. W winds 10-15 kts with gusts up to 25 kts, becoming light overnight.

Saturday...VFR early then becoming MVFR in rain showers at southern terminals. SW winds 5 to 10 kts.

Saturday night to Sunday...MVFR/VFR in -shra/-tsra. Light and variable winds.

Sunday night to Monday...Becoming VFR early Sunday night. W winds 5 to 10 kts, becoming SW Monday.

MARINE

Thunderstorms are expected to approach the coastal waters later this afternoon into the evening. Wind gusts of 40 to 50 kts are possible in the strongest cells. Timing would be around 3-6 PM.

Otherwise, winds remain below SCA criteria with seas around 2-4 feet through Saturday.

Winds pick up out of the south late Saturday night and seas rise to 5-8 feet by early Sunday morning, so SCAs are likely during this timeframe. This will be short-lived however, as seas and winds decrease by Sunday afternoon/evening.

CAR WATCHES/WARNINGS/ADVISORIES

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