Currently: Litchfield County remains in a svr tstorm watch. Convective parameters are more unstable up there, so any thunderstorms in the NW Hills could be strong to severe. Otherwise, the cold front responsible for producing these thunderstorms is still way out near Sandusky, Ohio, so storm chances will be ongoing tonight.
Tonight: A slow moving cold front approaches. Over the far Western portions of the area, thunderstorms should probably wind down by around 9PM. However, it may take another 12 hours for scattered storms to wind down in far Eastern CT. All this having been said, overall coverage will diminish once one gets East of I 91 and hits a more stable marine air mass. As far as temperatures, expect lows to be within a few degrees of 55.
Tomorrow: A really nice day, and with Saturday looking a little better (we'll get to that later), these two days may be the only two totally rain free days of the forecast period, with Thursday the more sure thing, at least west of I 91. East of I 91, a few morning showers clear out, then it turns fairly nice. Temperatures will be pretty uniform- no sea breezes with a westerly breeze- in the mid to upper 70s.
Tomorrow Night/Friday: More uncertainty as we head into Friday. First tomorrow night should be fair, with as good radiational cooling conditions as one could ever expect for early June. Then, on Friday, most models had been dry, now models are ejecting a strong upper level low into New England (the GFS is actually showing snow and sleet mixing with rain in Montreal). What this now means for us is that numerous showers and thunderstorms will develop Friday afternoon and night. With upper level temperatures crashing and the freezing level falling to only 8,000 feet, any heavier showers could produce small hail. If they do, temperatures would drop rapidly under hail cores. This all also means that Friday should turn out to be a good 5-8 degrees cooler than what we were originally expecting, with highs only around 70.
Long Term: The weekend and beyond: We might be able to salvage a nice day Saturday, as most guidance is now showing the area to be between systems. With full sunshine, I've gone a few degrees warmer than guidance, with highs expected to be 70-75. It should also be noted that a few areas in the NW Hills and sheltered valleys along the CT River could reach the 30s Friday night/Saturday AM!
Now for Sunday... in actuality, 2/3 or so of the day could be OK, as showers and thunderstorms ahead of the next system may not make it into the area until mid afternoon and beyond. The thinking is showers and storms start from 4 to 8 across the state from west to east. There's also a pretty good chance of thunderstorms, once again mostly west of I 91. Guidance temperatures pretty much accepted- low 70s.
Beyond Sunday, the confidence in overall weather each day generally decreases. Trying to time each system as it approaches the area is an exercise in futility, as there will be multiple waves progressing along a stalled frontal system. All that is accurate to say is, after perhaps a brief break Monday morning, expect periods of rain and thunderstorms until at least Thursday morning. Temperatures will also be tough to predict as small movements of the frontal boundary could make for some tricky forecasts. I will only say two things regarding temperatures. First of all, the latest GFS tries to blast a warm front through the area on Monday, with temperatures soaring into the 80s across most of the state. While that is a possibility, I'm not ready to bite on that yet, given the hesitancy for warm fronts to push north this season. My second temperature note... if some of the guidance is correct in having a coastal low in place with near record (for the time of year) strength high pressure to the north in Canada, and a banana like high building into the High Plains, we may see the coldest maximum temperatures ever recorded in June sometime in the middle of next week... stay tuned!
Long Range: Really no big changes in the long range. A general ridge in the west, trough in the east pattern will remain in place, which means generally below normal temperatures and above normal precipitation. That does not mean that it will rain every day, nor does it mean that every day will feature below normal temperatures, but the majority of the time will be cooler than normal, and it will probably rain (at least a little) on more days than not.
Model note (to other forecasters): PLEASE do not use the GFS for QPF forecasting. I know it is never a notoriously good model in this field, but it has been just abysmal regarding QPF lately and often doesn't even have a clue until the precipitation is literally going to start in less than an hour. So whatever methods you use to forecast, stay away from the GFS' QPF algorithm.
Anyway, let's take a look at some of the systems to affect our region. With so much going on, I don't really know where to start, but from a timing perspective, we'll first look at the system slated to affect the region on Friday.
Finally, let's take a look at late Sunday, which could be the beginning of a long-duration rainy period. Check out how precipitation is just beginning to move into the SW 1/2 of the state and check out how much of the country is raining. Now if I tell you that this is slow-moving, you'll know why it's going to take a long time to get out of here!