textproduct: Caribou

WHAT HAS CHANGED

- No significant changes.

KEY MESSAGES

1) Isolated thunderstorms possible across northwest areas Thursday afternoon. Isolated/scattered showers and thunderstorms possible regionwide Thursday night.

2) Thunderstorms are possible Friday afternoon and evening, some of which may be strong with gusty winds and small hail.

DISCUSSION

KEY MESSAGE 1...Isolated thunderstorms possible across northwest areas Thursday afternoon. Isolated/scattered showers and thunderstorms possible regionwide Thursday night.

KEY MESSAGE 1 DESCRIPTION... Thunderstorms will develop across Quebec province Thursday afternoon in advance of an approaching cold front. These thunderstorms could begin to reach northwest portions of the forecast area Thursday afternoon. The remnants of these showers and thunderstorms will then cross the region Thursday night.

KEY MESSAGE 2...Thunderstorms are possible Friday afternoon and evening, some of which may be strong with gusty winds and small hail.

KEY MESSAGE 2 DESCRIPTION... A cold front crosses the area Friday on the leading edge of a full latitude trough pushing into the region, with the added support of a northern stream shortwave pushing through the trough around that time. Current guidance shows that the cold front is expected to be just off to our west on Friday morning and reach central Maine by early afternoon as convection develops along and ahead of it. This should focus the area of thunderstorms towards central Maine, eastern Aroostook, and far interior Downeast. Current model guidance shows the potential for some strong to possibly severe storms with instability of up to 1500 J/kg and deep-layer shear around 30 kts driven by elongated, straight hodographs. Mid-level lapse rates are also relatively favorable which is typically a limiting factor for our severe threat. While severe potential exists there are still some outstanding questions that could modify the threat. First, how much cloud cover will be left over from showers and storms the night before? This could change our low-level thermodynamics and instability profile. Second, where exactly will the cold front be during the afternoon? This will determine where storms set up. Third, how far inland will the marine layer penetrate? The further north the marine layer penetrates, the lower the storm risk along the coast.

AVIATION /18Z WEDNESDAY THROUGH MONDAY/

This afternoon...VFR. Northwest/west winds 5 to 10 knots, becoming variable.

Tonight...Variable conditions with any fog late. Otherwise, VFR. Light and variable winds.

Thursday...Variable conditions with any fog early. Otherwise, VFR. Isolated showers/thunderstorms possible across northwest areas late. South winds around 10 knots, increasing to 10 to 15 knots with gusts up to 20 to 25 knots.

Thursday night...Isolated/scattered showers and thunderstorms. Areas of fog developing. Otherwise, VFR early lowering to IFR/LIFR. South winds 10 to 15 knots with gusts up to around 20 knots. Low level wind shear possible.

Friday...MVFR/IFR in showers and thunderstorms. S winds 5-10 kts with gusts up to 20 kts possible.

Friday night...Improving to VFR early. NW winds around 5 kts.

Saturday...VFR. W/NW winds 5-10kt.

Saturday night...VFR. Light and variable winds.

Sunday...VFR, possibly MVFR/IFR in afternoon showers and thunderstorms at northern terminals. SW winds 5 to 10 kts.

Sunday night...MVFR with a chance of rain showers. Northwest/west winds 5 to 10 knots.

Monday...VFR/MVFR. Variable winds 5 to 10 knots.

MARINE

Winds/seas below small craft advisory levels tonight through Sunday. Seas 2 to 4 ft. Areas of fog tonight through Thursday night. Patchy fog returns briefly early Friday night. Isolated/scattered showers Thursday night. Thunderstorms possible Friday.

CAR WATCHES/WARNINGS/ADVISORIES

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