Friday, 11:15 a.m.
The debate rages over a weekend "snow or no" storm in the Northeast. While the final answer is not yet etched in stone, rest assured there will be a storm, and it will become quite powerful as it ends up over Nova Scotia late Sunday. Just as importantly, it will be the start of a very active period in the weather. Take a look at the upper-level forecast for Monday evening:
On the right, we see the big storm over Newfoundland. In the middle of the country, we see another strong upper-level trough over the Plains and Midwest. And on the left, approaching the Northwest coast, still another strong upper level trough digging southeastward from the Gulf of Mexico. One after another after another.
With regard to the first system, there are still all sorts of things that can happen. We are certain there will be two features to track. The first will cross the Appalachians this afternoon with a developing area of rain and wet snow that will go to mainly snow early tonight. As that feature slides northeastward from Virginia into Maryland and across southeastern Pennsylvania and Jersey, a similar thing will happen. The boundary layer temperatures are warm enough so that as the precipitation begins, it will be more rain than snow. Then, as the column cools with continued precipitation, it'll allow falling snowflakes to reach the ground. This could yield a light but problematic 1- to maybe 3-inch accumulation later tonight into tomorrow morning as it streaks across southeastern New York and into southern New England.
Then it gets even more interesting. The second piece of this puzzle will dive from the eastern Rockies and central Plains this afternoon into the base of the deepening upper-level trough late tonight into tomorrow morning over Alabama, Georgia and Florida. Again, boundary layer issues over the Southeast should mean the early breakout of precipitation over Georgia into the Carolinas will be rain, but it is quite easy to see how it then turns to snow in some areas later tomorrow before the trough shifts off the coast tomorrow night.
Low pressure will then steadily deepen over the Gulf stream Saturday night. Remember, the overall net effect of this entire trough will be to bring very cold air into the East. At the same time, the air over the East ahead of it is pretty mild today. Once this all gets mixed up off the coast, it will happen over very tepid Gulf stream waters, just as we saw one week ago. That means the storm will form and will intensify. The real questions will be how it tracks and how far west the snow shield associated with it can come.
Look at the regional Canadian model for Sunday morning:
I mentioned earlier in the week the one thing this storm was going to lack is an overrunning high in front of it. It's still not there, as you can see from the image above, which tells me it will be tough to get the snow far inland. In fact, in the final analysis, it is quite conceivable the lead feature produces more snow in the interior mid-Atlantic into parts of southern New England and that parts of the Carolinas wind up with more snow tomorrow afternoon than places over central and especially western New England tomorrow night and Sunday.
I'm leaving the door open for eastern New England, especially Maine, to get a decent snow out of this. There are just too many reasons for places such as Boston and Portland to cash in on that developing coastal storm, but there will definitely be much more for places like Eastport, Caribou, St. John and Fredericton.
Storm number two will come into the Plains late Sunday with two low centers:
The first impulse will bring showers through Vancouver into British Columbia tomorrow, reaching Washington in the afternoon and leading to some snow showers late in the day and at night across the interior Northwest to western Montana and northwestern Wyoming tomorrow night.
The broad southerly flow ahead of this trough will allow rapid warming to take place on the Plains this weekend, and that could mean rain all the way up to Chicago Monday afternoon after a cold weekend for the Windy City. In fact, snow will be limited with this particular storm, affecting parts of the northern Plains and Midwest into the Great Lakes. I also think there will be enough resistance to the arrival of warmer air into the Northeast to allow some snow and ice to fall across parts of northeastern Pennsylvania and upstate New York into interior New England Monday night into Tuesday. The bigger concern will be that of severe weather from eastern Texas, Louisiana and Arkansas late Monday, then across the lower Mississippi Valley into the Tennessee Valley and Deep South Monday night and Tuesday.
Even as that storm is running through the Northeast and mid-Atlantic states, still another will be spreading more wet weather into the Northwest. It may not be the most powerful of storms, but it will rain, and on Tuesday, that rain will be moving into central California and even parts of southern California.
This storm will have impacts coast to coast. Look at the upper-level chart for Wednesday evening:
One bowling ball will roll through the Northeast, while another rolls into the Southwest. And this latter bowling ball will roll a strike through the southern Plains, then across the South later next week, with more rain and strong to severe thunderstorms. This time around, however, the storm track won't be into the Upper Midwest, but more across the Plains toward the lower Great Lakes, and I'm almost certain a secondary low will form in the mid-Atlantic on Friday.
That has important ramifications for the Northeast should it happen. It may mean more snow for parts of the northern mid-Atlantic into New England, as well as parts of the Great Lakes and Ohio Valley.
I'm still waiting to see just when this early spring is coming. I'm not seeing much evidence of it right now!
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