Sorry for late issuance today. I was waiting for NWS info, then decided to wait a little longer because the 18Z NAM run was so wonky I wanted to see the incoming GFS to make sure it was just a typical wonky 18Z NAM run.
Currently: High pressure anchored to our S tonight is beginning to pull away. Low pressure is organizing along the Gulf Coast. That's our storm and will become our main wx player.
Tonight: Guidance generally accepted. High clouds streaming into the area should put something of a lid on radiational cooling. But since they're thin clouds, temps will still be able to drop. Look for lows around 40 degrees.
Tomorrow: Light rain should arrive during the afternoon hours everywhere. This is indirectly related to our storm, as it is overrunning moisture ahead of the storm. I went 3-5 deg blo guidance due to clouds, rain, and developing onshore flow. Temps won't rise all that much and highs of 40-45 will probably be achieved before noon.
Now some notes regarding the upcoming storm: First, precip begins as rain everywhere and becomes heavy at times. Cold air fliters in from N to S and precip will change to snow. Coastal areas likely see some snowflakes too, but little if any accum. Accumulations are restricted to N CT, esp N of I 84. General thinking is 1-4" for most places, with 3-6" in the furthest N. A few locations in the NW Hills over 1000' elevation could see higher (signfiicant) accumulations. A snow map will likely be issued later tonight or tomorrow. The NWS for now has issued Winter Storm Watches for the MA counties to the N of the CT border. This makes sense, given higher confidence in reaching 6" accumulations in those areas. Depending on what model guidance looks like, watches could be expanded S in the AM.
There still isn't a great model consensus on the storm. Part of the reason is because our wx is going to depend heavily on how much interaction there is between the two jet streams. More phasing would be a heftier storm. However, a lot more phasing would result in a track so far to the west that the only snow would be over the Catskills and Poconos. Less phasing would shunt most of the precip to our S & E. This would likely end any snow threat, since no precip would fall where the air is cold enough. For snow weenies who want to see the most snow possible, a slightly stronger phase would be good, but not too much.
As for wind, winds could gust to 45-50 MPH. A more phased storm would result in stronger winds, while a less phased storm results in less winds. Wind advisories may be needed for much of the area.
As usual, my fcst will take a middle ground approach. NBM temp guidance appears totally lost for Sat and is not being used at all. It is showing widespread 50s across the state, which is ridiculous. I went at least 5 deg blo this guidance and that may not be cold enough. Precip begins to change to snow by mid afternoon along I 84. NW Hills could see flakes mix in by noon, as well as parts of far NE CT. Precip ends Sat night between 9 PM and midnight from SW To NE. Coastal Ct sections may see a few snow flakes or sleet pellets mix in a couple hrs before precip ends, but little if any accums are expected.
For Sunday, a chilly day, but no pcpn expected. Guidance highs around 40 degrees generally accepted. This could be too warm, depending if certain areas have fresh snowpack.
Mon-Tue: A small period of interest. There is a coastal law on all models, but it is out to sea. Saturday's storm trended a bit faster today and that allowed for a significant Westward push for this coastal low. Verbatim, it is still out to sea, but overrunning moisture on the ECMWF and new GFS now reaches the Delmarva Peninsula. Due to the short spacing between storms, we may not know until either Sat night's 00Z cycle or Sunday's 12Z cycle as to where this storm will go. It is something to keep an eye on. If we do get anything during that time frame, it would be all snow all the way to the coast, as the air mass is sufficiently cold. For now, no pcpn will be mentioned in the fcst, but it is a growing period of interest. As for temps, guidance was generally accepted, and I went w/highs near 40 both days, but Tue is prob the cooler of the two days.
Wed-Thu: Fair with gradually moderating temps. Guidance temps accepted. Expect highs of 40-45 Wed and mid to upper 40s Thu.
I spent too much time on the upcoming storm to really look much into the long range. Additionally, models have been flipping wildly from run to run, so there isn't much reason to comment right now.
Now, let's take a graphical look at systems that could affect the area in the coming week. I'll show the Sat storm and then I'll show the offshore storm early next week. The map below is Saturday afternoon. By that point, it is probably snowing from about I 84 on north, or is at least mixing with snow.