textproduct: Caribou

WHAT HAS CHANGED

- Increasing confidence in the threat for strong to severe storms on Tuesday

KEY MESSAGES

1) Severe thunderstorms are possible over north/central areas Tuesday, continuing into Tuesday evening areawide.

2) Very warm to hot temperatures Monday to Wednesday. The highest heat indices of the period should be Tuesday and over the Bangor region, with heat indices to 95 possible.

DISCUSSION

KEY MESSAGE 1...Severe thunderstorms are possible over north/central areas Tuesday, continuing into Tuesday evening areawide.

KEY MESSAGE 1 DESCRIPTION... A lot of ingredients exist Tuesday for as high-end of a severe weather episode as we ever see in our area. Feel that somewhere from our area over to Vermont has a good shot at getting damaging storms, but just where in this area, and exactly when, are very much in question thanks to lingering uncertainty in the timing and amplitude of the approaching upper level shortwave trough.

The ingredients that we are speaking of are very high CAPE, strong wind shear with the shear being mostly speed shear, and fairly steep to steep mid-level lapse rates. The largest threat appears to be damaging winds from any clusters or lines of storms, though the threat of hail or an isolated tornado does exist too. For now have added gusty winds to the forecast with the storms, but may have to ramp that up. With the strong W/NW winds aloft, storm motion should be sufficient to limit the flash flooding threat. Feel that the forcing with the upcoming shortwave trough is sufficient to break any cap, which has prevented storm development in some recent setups when we were concerned we might get severe storms.

KEY MESSAGE 2...Very warm to hot temperatures Monday to Wednesday. The highest heat indices of the period should be Tuesday and over the Bangor region, with heat indices to 95 possible.

KEY MESSAGE 2 DESCRIPTION... A stretch of above to much above average temperatures Monday to Wednesday. Monday will quickly warm into the 80s over most of the area, but the development of afternoon scattered showers and building cloud cover will cap temperatures early, keeping highs in the low to mid 80s before it cools off through the rest of the afternoon. Tuesday will be the warmest day for most areas just ahead of the approaching system. Still some uncertainty in high temperatures depending on cloud cover, but generally looking for mid 80s north and near the coast, with some low to mid 90s in between. The warmest area appears to be the general Bangor/Lincoln/Dover- Foxcroft region, where, thanks to muggy air, heat indices have a 50-70 percent chance of topping 95F (our heat advisory criteria). Heading into Wednesday, temperatures are looking a bit cooler in the north behind a cold front, though Downeast will still be very warm with mid 80s to around 90. Dewpoints will be down a bit though, and don't anticipate as high of heat indices as Tuesday. It will be breezy each day Monday to Wednesday, which should help make it feel a bit more comfortable for those who venture outdoors.

AVIATION /18Z SUNDAY THROUGH FRIDAY/

Tonight - Monday night...VFR conditions continue across all terminals. Winds shift S tonight then increase to 10 to 15 kts out of the SW Monday afternoon with gusts to 20 kts. Monday night SW winds diminish to 5 to 10 kts.

Tuesday-Tuesday night...Mainly VFR south, MVFR/IFR north Tuesday PM in showers and possible strong to severe TS. The threat could continue into the overnight hours especially for BGR/BHB. SW winds 10-15 kts, becoming W Tue night.

Wednesday...Mainly VFR with possible MVFR/IFR north in afternoon showers and TS. W winds 10-15 kts with gust up to 25 kts.

Wednesday night-Friday...Mainly VFR. Possible MVFR north. W/NW winds 10-15 kts.

MARINE

Calm conditions will continue tonight into the day on Monday. Winds will gradually increase with gusts approaching 25 kts Monday night, but cold waters will keep the boundary layer stable and conditions will likely remain below small craft advisory criteria through Monday night. Seas will gradually approach 5 kts late Monday night. Winds and seas are expected to increase Tuesday to around 25 kts with seas 4-8 ft. Winds decrease to 15 kts or less late Tuesday night and remain fairly light through Friday. Seas are a bit slower to come down, with seas down to 2-4 ft by late Wednesday, with these lower seas continuing into Friday.

CAR WATCHES/WARNINGS/ADVISORIES

ME...Beach Hazards Statement until 8 PM EDT this evening for MEZ029- 030. MARINE...None.