Currently: Two main features on the map this afternoon: A stationary front straddling basically Interstate 90. Along and S of that front is the focal point for t-storms. TD Cristobal near the Mexico/Guatemala border, expected to move back N into the GOMEX could impact our wx further down the road.
Before I begin the actual discussion, I wanted to start with a quick modeling note, directed at my fellow meteorologists, professional forecasters, cohorts on this site, etc. I have been using the NBM guidance as a replacement for unreliable MOS products. And while it is better, esp with temps, it has its flaws, such as almost always underdoing wind, and always underdoing pcpn in the xtndd range. There is a new NBM product, the experimental products (scroll further down in the text prods menu). I have been tinkering w/it and I really like what I see. Those two biases are gone. I do not know the official reason or how these algorithms are officially calculated, but my best guess is that the older NBM versions incorporated too much of the "bad" ens prods. For example, when using ens-based guidance, you are genly supposed to delete the outliers. I have a feeling the old NBM did not do that, while the new NBM does that better. Now on to the disco:
So, starting out with the rest of today.... we can probably get away with keeping the rest of the day dry, as it appears any convection should hold off until later tonight. But I can't totally rule out a sprinkle here or there, as the air mass is still conditionally unstable. High temps probably won't get as high as the warmest guidance numbers. It seems like so far this late spring into summer, nature has found any was possible to temper high temps, whether it's a band of clouds that coincides with max heating, a sudden onshore breeze for an hr or two, a freak sprinkle, nature has seemed to laugh at us and keep temps down any way possible each day. This is a product of the pattern and I will not ignore it until I see clearly that the pattern has broken.
Now for tonight, the highest chance of storms should be centered around midnight, give or take a few hours. Since the storms will be moving SW-NE and exhibiting a weakening trend, the highest chance of storms should be across SW CT. As far as temps, guidance is in very good agreement, so I don't see any reason to make any chgs. Look for lows in the low 60s.
Tomorrow: With the frontal boundary still in the area, it would be hard to forecast a completely dry day tomorrow. That said, once again, the highest chance of storms will be the further S you go. It will be warm and humid once again, and there should be more clouds than today. Therefore, guidance looks quite a bit too warm and I will be subtracting at least 5 degs from it. There is a chc of tstorms at just about any time, but the best chc looks to be late in the day into the eve. As for temps, look for highs to be in the mid 70s.
Tomorrow night/Sat: We'll gradually dry out the atmosphere, but there is still the chance for showers and thunderstorms on Saturday until the actual cold front goes through. Once again, areas further south will have better chances of thunderstorms, and activity should be concentrated on late day and early evening. As for temps, I will go a couple deg warmer than guidance, since there should be more sun on Sat and a good warm surge ahead of the cold front. Look for highs in the low to mid 80s.
Long Term (Sun-Thu): The first half of the long term period is sunny and pleasantly warm. As they used to say in the old days of wx forecasting "Wx nil" translated- no weather. I generally went close to guidance for temps, but a couple degrees higher on Tuesday, as I think modeling is not capturing the warm surge well yet. (High press moves offshore and sets up return flow of warmer air). So look for highs in the mid 70s Sun and Mon and then approaching 80 Tue.
The forecast for Wednesday and Thursday becomes a lot more complicated. A strong cold front will approach from the west. At about the same time, whatever is left of Cristobal will probably become absorbed into the cold front. Whether this just enhances rainfall or actually produces its own storm w/heavy rain and high winds is yet to be determined. The 12Z GFS is completely dry and is being ignored for several reasons. First, it is the only run to do that in many runs. Second, nearly all other op guidance and ens guidance disagrees with it. Finally, it moves Cristobal back into the mtns of Guatemala and Honduras and destroys the sys. It is the only op model that still insists on doing so, so it is being ignored for the time being.
Assuming that Wednesday is mostly dry and any rain holds off until nighttime, guidance temperatures look Ok and will be accepted for now. So expect highs in the upper 70s. For Thu's temps, if I assume it will be raining most of the time, I'll go a couple degs lower than guidance. So I'll call for highs of 70-75.
Looking into the long range, I again have to ignore the GFS. The NBM, ensembles, and basically all other operational models disagree with what the 12Z GFS is spitting out, which would be a warm to hot and dry pattern. For some reason, the GFS likes to "run very hot" every day at 12Z, while most of the other runs never do that. It hasn't been right yet. I think some of today's flaws could be tied to what it does with Cristobal in the short term. At any rate, most other guidance shows a trough in the east, with a pattern that favors below to much below norm temps and even potential east coast storminess. NBM showing another high QPF event Jun 12-13, so the GFS is going to be ignored until it proves itself right.
Now, let's take a look at some systems to affect the area in the coming days. Due to the unsettled weather in the short term, combined with uncertainty in the long term, we'll stick with the t-storm chances for tonight and tomorrow. First, let's look at this map, which is valid tonite at midnite. Vry hvy rain is over NE NJ and SE NY, but you can already see how it is dying as it enters CT. This is why chcs are so much higher over SW CT than NE CT.