Thursday, 11:50 a.m.
The not-so-dull roar you hear these days is growing as the prospect of snow next week in parts of the Northeast and mid-Atlantic steadily grows. In Wednesday's post, 'Could Snow Not Be Far Off for the Interior Northeast,' I brought up the idea of snow falling anytime from Tuesday night to Friday over parts of the Northeast. That prospect has not grown smaller but has instead become larger.
Before I get to how that will all play out, let's deal with how we might get there. Today, a cold front is marching into and through the Northeast and mid-Atlantic states, accompanied by clouds and some rain. Behind the front, chilly air is pouring across the Great Lakes and Ohio Valley and will reach the East Coast tonight.
Once the front passes, the weather will be rather tranquil for a period of time. In fact, precipitation will be lacking. Looking at the 12z Nov. 7 GFS model forecast of total precipitation from tomorrow morning through Sunday evening, there's not much to talk about anywhere in the country!
That being said, one important feature can be tracked right across the country. It's a storm bringing gusty winds and rain through the Northwest:
My triathlon coach Lindsey, who lives in Sidney, lamented to me earlier about the pouring rain she was experiencing this morning from this storm! I, of course, was quick to point out that it beats snow in my book, which I might be facing by this very time next week!
Anyway, this storm will move through the Northwest this afternoon and reorganize over southern Alberta and southern Saskatchewan later tonight. There will be some snow and rain associated with it in northernmost sections of Montana overnight, with mainly a few rain showers farther south outside of the mountains.
As the storm tracks farther downstream tomorrow and tomorrow night, it will try to pull milder air out across the Rockies onto the Plains, and with some degree of success. Here is a peek at the 6z Nov. 7 GFS ensemble forecast of projected temperature anomalies tomorrow:
By the end of the day Saturday, this weak storm will be passing by the northern Great Lakes. The 12z Nov. 7 NAM models surface forecast Saturday evening:
Cooler air will bleed southward behind the storm and its attendant cold front into the northern Plains and Midwest on Saturday, then across the Great Lakes toward the Northeast Saturday night and Sunday. If you examine that image a little more closely, you might notice a feature back in the northern sections of Manitoba and Saskatchewan back to northern British Columbia. A weak low is forming in northern Saskatchewan, with a cold front attached to it. This feature will track east-southeastward Saturday night and Sunday. In the process it pulls a cold front south and southeast, moving into North Dakota and northern Minnesota later Sunday.
Building in behind the front will be a strong high pressure area, one with pretty cold air. In fact, look at the 6z GFS ensemble forecast of temperatures for Monday:
The front will move through the Northeast and into the mid-Atlantic states later Monday and Monday night and should move off the coast Tuesday. With a large surface high building into the Midwest, the stage is set for the coldest press of air so far this season into the Midwest, the Great Lakes and the Ohio Valley to upstate New York and New England.
How does this lead to a potential snowfall? Well, another disturbance will dig down the southwest flank of the upper-level trough sliding into the Northeast early next week. That disturbance will bring some moisture up and over the low-level cold air drilling in from the north, setting the stage for overrunning precipitation. Much of it could well be in the form of snow, even though it initially may not be terribly heavy due to a lack of deep moisture. However, that may be just the first shot of precipitation. And this may be somewhat earlier than I had expected yesterday, tied to the back side of the advancing cold front and potentially impacting areas from Pennsylvania down into West Virginia, western Virginia and perhaps even northwestern North Carolina!
My hunch is that there will be another feature involved in this whole thing come Wednesday. That would then cause low pressure to develop along the baroclinic zone along the East Coast sometime Wednesday. What is far less certain is WHERE that storm forms and where it goes. If you look at the 0z European model, it forms near the coast and is kept there by an upper-level low to its west. In contrast, the GFS keeps the upper-level trough open, thereby forcing the storm development farther offshore on Wednesday. This would pretty much spare the northern mid-Atlantic and New England of any appreciable cold. Instead, it would simply be cold for a couple of days, then by next weekend it's getting warmer.
It will be fascinating to see how this all unfolds in the coming days, but one thing is certain. Winter may be much closer to us than anyone wants to believe!
Summer has ended astronomically, but from a meteorological standpoint, there's plenty more warm weather heading into October from the Plains to the East.
Two strong cold fronts will charge across the country in the next week, eventually taking out the current hot and humid air mass from the Plains to the East Coast.
Over the next three days, hot and humid air will expand across the Mississippi Valley all the way to the East Coast. This will be followed by even more heat and humidity leading into the weekend.
Hermine will head across the Florida Panhandle late tonight, then cut across the coastal Carolinas and become a headache for the mid-Atlantic and southern New England over the Labor Day weekend. It will be followed by a heat wave later next week.
The heat and humidity will be erased from much of the East later this week, but warmth will spread from the Plains eastward over the weekend. The tropics could still play an important role in the weather along the Eastern Seaboard this weekend.
A dominant ridge will keep it hot from the Ohio Valley to the East into next week, while the disturbance north of Cuba is slow to develop as it approaches the southeastern Gulf of Mexico.