textproduct: Caribou

WHAT HAS CHANGED

-Raised high temperatures a little today in Northern Maine, and expanded the heat advisory north to Caribou. Also raised high temperatures a little in the north for Friday, and extended the heat advisory for Southern Aroostook and Northern Penobscot into Friday.

-Raised nighttime lows for rest of tonight and Thursday night a couple degrees.

-Chances for rain on Saturday increase. Isolated thunderstorms, however, stay only a slight chance.

KEY MESSAGES

1) Hot temperatures and high humidity through Friday will lead to hazardous heat, with little reprieve each night.

2) Thunderstorms remain possible this evening through Saturday. A conditional threat for severe storms exists.

DISCUSSION

KEY MESSAGE 1...Hot temperatures and high humidity through Friday will lead to hazardous heat, with little reprieve each night.

KEY MESSAGE 1 DESCRIPTION... An exceptionally mild start to the day today inland from the immediate coast, with readings mostly 70-75F. Caribou's low temperature ended up being 74F. If this holds this upcoming evening (about a 75 percent chance it will), it would set a new all-time (for any day of the year) record high minimum temperature. The existing record is 73F.

For today (Thursday), kept high temperatures close to the same in southern portions of the area, but raised temperatures a bit in the north and expanded the heat advisory north to Caribou. This adjustment was based on a few factors. For one, there will be a favorable west breeze which tends to maximize warming potential east of the North Woods highlands thanks to slight downsloping and lack of marine influence. Secondly, yesterday ended up getting about 3F warmer than NBM had forecast in the north, and see no reason the same won't happen today. And thirdly, there should be abundant sunshine, as high clouds presently over the area should move out by mid-morning.

For highs today, we are expecting low to mid 90s through the area. This will be just a little warmer than yesterday except along the coast, where it will be much warmer than yesterday thanks to more of a shore-parallel WSW wind rather than onshore S wind. This shore-parallel wind will limit the cooling influence of the Gulf of Maine. Dewpoints today will remain quite high, with low to mid 70s this morning, then 65-70F in the afternoon. The drop in the afternoon dewpoints thanks to deep mixing should just barely save the majority of places from reaching the extreme heat criteria of 105F.

A very mild night again Thursday night with lows generally 70-75F. In fact, Caribou could be in jeopardy of setting an all-time (any day of the year) record high minimum temperature. The record to beat is 73F. As of 250am, the low in Caribou is 76F and we could stay above 73F the rest of the night, plus it's doubtful it'll drop below 73F by midnight tonight. Something to watch.

Hot again Friday, though ever so slightly not quite as hot as Thursday north of Bangor. That said, trended high temperatures up a touch in the north. Along the coast, Friday should actually be the warmest day, with highs in the mid 90s all the way to the immediate coast. The decent westerly breeze with a slight offshore component will limit and cooling influence from the Gulf of Maine. Still quite muggy, but dewpoints falling into the mid 60s in the afternoon should keep most places at heat advisory criteria rather than extreme heat criteria.

Temperatures and humidity will be lower Saturday behind a cold front. Even still, heat indices will reach the upper 80s and possibly low 90s over the Bangor and Downeast regions which, while below advisory criteria, still warrants concerns over heat risk during the holiday weekend. Heat indices fall a bit more into Sunday.

KEY MESSAGE 2...Thunderstorms remain possible this evening through Saturday. A conditional threat for severe storms exists.

KEY MESSAGE 2 DESCRIPTION... We have miraculously dodged any severe thunderstorms over the past few days. There has been a lot of thunderstorm activity to both our north and to our southwest, showcasing the volatility of the airmass over the region. This setup with hot, humid air on the north edge of an upper level ridge is typically a very good setup for severe storms here, but we have just barely been capped so far and lacking the slightest trigger to ignite storms. For today into this evening, we have a slight chance of storms in the forecast. Odds favor the cap persisting for most areas, but if the cap breaks either over our area or a bit to our west and storms move in, severe storms are possible. But feel that this is unlikely and the vast majority of places will stay dry. The instability (CAPE) in last night's 0z sounding from Caribou had 2877 J/kg, which is the 2nd highest for any 0z sounding on record for Caribou. But there was also a little convective inhibition (CIN), meaning all that was wasted with no trigger to ignite storms.

For late Friday, the best threat of storms seems to be in the north ahead of an approaching cold front, which could actually provide a trigger finally from some storms. Can't rule out a severe storm or two with winds being the main threat, but the instability by Friday won't be as great as it has been or as great as Thursday. That said, the instability that we do have will have a better chance at actually being realized and having a trigger.

Cold front moves through the region Saturday, which could provide some lift for isolated thunderstorms. Kept thunderstorm potential at a slight chance, as mid-level lapse rates and shear are mediocre. Increasing trend in some of the regional models for some rain showers along the front, but not anticipating anything more than a few isolated storms Saturday afternoon.

AVIATION /09Z THURSDAY THROUGH MONDAY/

Today...Very likely remaining VFR through the day today. Can't totally rule out a late afternoon storm, but if they do occur, they will be very isolated. W wind up to 10 kts.

Tonight...Mainly VFR, though can't rule out an isolated evening storm or late night patchy fog. W/SW wind 5 kts.

Friday...Mainly VFR. Chance of storms in the afternoon mainly Aroostook County. W wind increasing to 10-15 kts in the afternoon.

Friday night-Saturday...Mainly VFR, becoming MVFR in light rain showers, and a potential for isolated thunderstorms Saturday afternoon. W winds gusting to 15-20KT possible Friday night into Saturday, becoming NW Saturday evening.

Saturday night-Sunday...Mainly VFR with light NW winds around 5KT.

Monday...Mainly VFR. Light and variable winds.

MARINE

Conditions below SCA criteria through Monday. Seas generally around 2-4ft through Monday. Some fog in the waters this morning, but diminishing later today and staying mostly free of fog into the weekend. W/SW winds through Friday night, shifting NW by Saturday night, shifting S by Sunday.

CAR WATCHES/WARNINGS/ADVISORIES

ME...Heat Advisory from 11 AM this morning to 8 PM EDT this evening for MEZ002. Heat Advisory from 11 AM this morning to 8 PM EDT Friday for MEZ005-006-011-015>017-029>032. MARINE...None.