Currently: The cold front that will herald our rapid wx change was currently stretching from the Lehigh Valley to Eastern NY state. Temps will fall very rapidly behind that front.
Tonight: Temps fall rapidly behind the cold front. Guidance is in pretty good agreement w/overall thermals. No reason to bicker w/guidance on temps at that range. Low temps generally in the mid 20s, except maybe upper 20s along the SE coast.
Tomorrow: Morning sun leads to increasing clouds. An area of light pcpn, mainly snow, could break out during the day near the Mason-Dixon line. However, dry air from the high pressure sys overhead should allow that snow to break apart before it gets near our area. Once again, guidance is an excellent agreement and generally accepted. Highs should be in the mid to upper 30s throughout the state.
...A WINTER STORM WATCH HAS BEEN ISSUED BY THE 3 NWS OFFICES THAT SERVE OUR STATE FOR EVERYWHERE EXCEPT THE IMMEDIATE S COAST...
Here's where the winter wx occurs. Pcpn probably arrives in our area around midnight, give or take a few hrs. Initially, all levels are cold enough to support snow. However, a transition to other forms of pcpn will migrate S to N as the event continues. Snow should accumulate an inch or two along the immediate SE coast before changing to other ptypes. As one migrates N thru the state, accums will be higher, with up to 6" possible in the NW and NE parts of the state, esp over 1000 feet. Most areas will see somewhere between 2 and 5 inches of snow.
After we change over, we do not change directly to rain, as the mid-levels of the atmosphere warm before the sfc. We will change to sleet probably everywhere, then freezing rain at least in the southern half of the state. The exact timing of these changeovers is uncertain right now. The later the changeover to freezing rain the better, as that is by far the most dangerous winter p-type. My thinking is that we do make a complete changeover to rain along the immediate S coast, up to about the Merritt Pkwy. N of there, temps may very well stay below freezing for the duration. Even in areas that do change to rain, most of the pcpn may be done before we changeover. I went several deg under guidance for temps, and have highs of 30-35. These systems have a tendency to keep cold air in at the sfc longer than progged.
Stay tuned for our snowmap highlighting this system.
Long Term (The weekend and beyond): Generally below to much below norm temps are expected during this time, w/Clipper systems/Arctic fronts producing occasional bursts of snow.
For Sat: A cold day behind our departing sys. Went a bit below guidance on temps, w/some snowcover and fresh cold air advection. Highs generally around freezing. Winds gusting to 30-35 MPH will make it feel even colder!
For Sun: Temps moderate, as high press moves overhead. Guidance temps generally accepted. Highs generally around 40, except low 40s along the I 91 corridor. An Arctic front approaches Sun night. This front looks similar to the one last Sat and could produce snow squalls again. This time, with the nighttime passage, temps could be lower and we won't have to deal w/sun angle, so we could see more widespread brief accums.
For Mon: Bitter cold, esp for the time of yr, behind the fropa. Went a bit below guidance w/fresh cold air advection. Highs only in the mid to upper 20s. Wind gusts up to 30 MPH will make it feel even colder!
For Tue: An Alberta Clipper sys approaches. This sys has trended stronger and further S w/last model runs. So there could be minor accumulations up to an inch or two w/this, as it has the potential to produce a burst of steady snow. Also, because of this trend, I went well below temp guidance, and I have highs generally in the mid 30s.
For Wed: Clearing skies but still cold. I feel there's one more good shot of cold air advection behind the sys that is not being modeled well right now. For this reason, I took a big risk at this range and totally ignored temp guidance. My temp fcst is based on thermal profiles, using a top-down approach. Highs should be 30-35 across the state.
The long range does not look all that atypical for the time of yr. Highly variable conditions day to day, esp regarding temps, will lead to high uncertainty with the actual fcst. There is the potential for a very warm day like today at times, but there is also the potential for more winter storms, if a storm lines up at the right time w/a burst of cold air. Stay tuned!
A couple of production notes: I did not add any graphics today, since my cohorts will likely be working on a map. I may add a quick line or two update to this later today or tomorrow, as NWS headlines and model runs change (if I have the time)!
Take care and see all next week!