Currently: A "quasistationary" boundary extended from near Lake Huron to along the Long Island Sound. This boundary will be the focal point for uncertainty regarding temperatures for a good chunk of this forecasting period. One fortunate thing for us this time is there is dry high pressure, rather than maritime high pressure, north of this front- for now. So we get nice dry weather instead of low clouds and drizzle.
Tonight: Not much going on and generally mostly clear skies. Model guidance is tightly clustered, so there is no reason to diverge. Lows should generally range 50-55.
Tomorrow: A weak frontal boundary could trigger some showers and thunderstorms later in the day. This time around, it does appear most of the state will be warm-sectored. However, the question this time will be whether or not there is enough moisture that everyone gets storms or if it's just widely-scattered stuff. For now, given trends in modeling, I think south of the Merritt Parkway should see more solid precipitation, with less as you head north (unless you head about 200 miles north of our forecast area, but that's not pertinent to this discussion). As for temperatures, the 18Z GFS numerical guidance has come in quite a bit cooler than the 12Z, and that looks to be about correct, given increasing clouds and arriving precipitation. High temperatures should be generally in the 70-75 degree range.
Tomorrow Night/Saturday: No precipitation should fall during this period (aside from leftovers from Friday afternoon's possible storms). However, a bit of a wrinkle has arrived in the Saturday forecast. The NAM model is showing deep marine layer that actually penetrates into much of interior New England in the form of low clouds and much lower temperatures. As I have mentioned before, the NAM does have a tendency to overdo this. However, the GFS also has a tendency to completely ignore this when it does, in fact, exist. Therefore, with low confidence, I have gone for a compromise, so Saturday's highs should be in the upper 60s.
Long Term (Sunday and beyond): Temperatures: For the most part, the GFS extended range temperature guidance has been fairly accepted, with the exception of a few tweaks here and there, except for Monday and Tuesday when I've lowered GFS temperatures by a few degrees. The GFS is running significantly warmer than all other guidance. It should also be noted that this isn't the highest confidence forecast in history. It isn't a case of a cut-and-dry Bermuda Ridge pumping heat into the area. Yes, the Bermuda Ridge is there, but so is an extension of the ridge into Nova Scotia, which would imply the potential for backdoor cold fronts. So, while I am going mostly warm in the long term, it should be noted that it is low-confidence, and if any adjustments are needed, they would probably be in a downward direction. Now, for the aforementioned temperatures: Sunday: 70-75, Monday: upper 70s, Tuesday: near or just above 70 Wednesday: similar with temperatures near 70 for highs, and Thursday: mid to upper 70s.
As for sensible weather in the long term, right now it is my belief that the best chances for showers and thunderstorms in the long term are later Sunday and later Wednesday as a couple cold fronts move through. A typical late spring pattern....
Looking out into the longer range, a lot of the longer range model guidance says we regress back into a trough in the east, which would result in a cooler, wetter pattern returning. While this is a departure from some recent guidance (and this usually lowers confidence), it is also a repeat of the pattern we've been in, so this does increase confidence a bit. All in all, I'd rate confidence in that happening at a moderate level.
Now, let's look at the Friday and Sunday systems in graphical format. (The Wednesday potential system is a ways out yet and can be discussed more in depth in future AFDs).
That's all for now! Have a great week!