Tuesday, 11:30 a.m.
I must admit that coming up with a theme today to write about was challenging. It's not that I had a mental block to writing, but rather I was struggling with trying to hang the pattern for the next couple of weeks on one or two main points. There will be big storms, but there will be little ones, too. There will be some warmups, but there's still plenty of cold air in the pattern. Some will get snow, and a few potentially a lot of snow. Others will have to contend with rain, and still others locally severe weather. And yet at the same time there are a lot of places that are very dry, and don't look to be getting wet any time soon. How do you put all of that under one big umbrella? Not very easily!
And that's when I stepped back and tried to look simply at the big picture, and the best that I could come up with is that we're on a bumpy road as we try to exit winter and enter spring. The computer forecasts continue to change almost every day it seems, and that just adds to the challenge! It makes daily forecasts hard, and longer-range forecasts that much more so!
So, then, why the idea of it being a bumpy road? I go back to the Sudden Stratospheric Warming (SSW) event of early January. From all that I've been able to read on the subject, once the cold air that is released on one of these events shows up, we can typically expect it to be on the playing field to one degree or another for at least a month, and probably six weeks or so. Using that as a time reference, it would carry us deep into the month of February before we might enter some form of new weather regime.
And there's plenty of evidence to support the notion there's more cold air around for a while. The real questions deal with how strong any cold outbreak might be, where it would be focused and how long it might last? Then, of course, you have to tackle the intervening warmups. Will they be one day? Two? Three? More? Widespread? Targeted only for certain areas? What might enhance the warmup? Restrict it? Add in the concern for storminess and the interplay between warm versus cold, and you can begin to see how it might be a defeating task!
My task, then, is to boil it down and make it as simple as possible by starting with the things I feel most confident of and going from there. So here goes:
1) Low pressure will cross the South and pass off the mid-Atlantic coast tomorrow night. As opposed to last week's blockbuster storm that buried the Northeast, this one appears to be modeled better by the NAM and GFS. Hey, every dog has its day, right? Now, as storms go, this one will pale in comparison to the Friday-Saturday blizzard of 2013. That said, we've already seen upwards of a half a foot of snow in the Texas Panhandle, and there will be that much or more in parts of Oklahoma will all is said and done tonight. There won't be that much downstream in the mid-Atlantic and southern New England for the most part, as the air will be a little warmer to begin with, which will allow some of the precipitation to start as rain. In addition, there simply will be less moisture in the areas where it is mainly so. Look at the 12z NAM 48-hour precipitation guesstimate:
By Thursday morning, the storm is pulling away from southeastern New England.
2) The jet stream will buckle late this week into the weekend. Here are the GFS ensemble height anomalies Friday afternoon:
I chose a broader perspective because you then get to see how many of these areas of orange/red (much higher-than-average heights, generally warmer-than-normal weather) and blue (lower-than-normal heights, areas of storminess and generally below-normal temperatures) there are scattered all around the Northern Hemisphere! That big ridge you see poking its nose up through the Northwest into British Columbia and Alberta will help induce a nice response downstream. It will force the next series of disturbances to dig farther south and carve out a mean long wave trough over the Mississippi Valley Friday, then into the East this weekend:
This, in turn, will draw arctic cold right back into the pattern. It will give a glancing blow to the northern and eastern Rockies, but it will get pretty cold in the northern and central Plains into the Midwest. By Saturday, that cold air will be drilling across the Gulf Coast into Florida and could mean frost in the northern reaches of the state Sunday morning and Monday morning, perhaps as far south as the citrus groves. With the normals there rising quite a bit these days, that will represent a large temperature departure. Look at the latest image for Sunday:
3) The weekend storm will pull cold into the South and East but will also pull it through. For the day I will gloss over the details of that weekend storm, as the models have not yet established a consensus on it. If there's a trend, it would be to keep the storm largely offshore. There's still room for it, though, so let's not dismiss it yet.
Anyway, the cold comes in. And it's impressive, too, as I showed with the anomalies above. However, it does not stay! Look at the projected upper-level height field by Monday night:
As has been the case most of the winter season, the trough is 'in and out.' Why? There's no downstream blocking in the North Atlantic. Without it, the upper-level flow remains progressive, so the cold will be moderated fairly quickly in most places early next week. Of course, that Northwest ridge is also wiped out, and resurfaces farther out in the North Pacific, with another healthy upper-level feature rolling into the region. In between, we find another one rolling into the Midwest and Great Lakes.
And therein lies the crux of the problem. There's plenty of cold air to be had, and any one disturbance will be able to tap into it to some degree and turn a mild day much colder within 24 hours. These storms will have some snow associated with them. Today, it's Oklahoma and the Texas Panhandle. Tomorrow and tomorrow night, the central Appalachians to southern New England. The one coming into the northern Plains and Upper Midwest late tomorrow will have some snow with it for parts of North Dakota to Wisconsin and eventually Michigan. The weekend storm? We'll see.
And as this disturbance comes through the Rockies, there will be some snow for parts of Idaho, Montana, Wyoming and Colorado. There will be still another storm early next week, with snow likely north of it in parts of the Great Lakes and maybe the interior Northeast.
Severe weather? Yes, some of that, too. Watch out this afternoon and tonight from northeastern Texas across the lower Mississippi Valley into southern Alabama, and perhaps to part of the Carolinas. There may be a lull in that sort of thing going into the weekend, but rest assured that early week storm will have some with it, potentially a lot more.
Such is the bumpy road ahead. Sort of like one of the roads I rode on yesterday on a tease for spring. It was chip sealed last summer, but the rough winter with lots of nuisance events and all of the plowing and salting has turned this one particular road into a veritable washboard. Never was I so glad to be off a road as I was yesterday on that particular road!
The record warmth of recent days will be replaced by a much colder air mass following a cold front moving from the Ohio Valley to the East. Rain will change to snow in the higher ground of upstate New York and northern New England.
Nicole crossed Bermuda Thursday morning as a major hurricane. Two storms will blast the Northwest with high winds and heavy rains in the next 72 hours, forcing warmer air out into the nation's midsection.
Matthew is a dangerous hurricane bearing down on the east coast of Florida. While it ravages Florida and parts of the Southeast into the weekend, it will spare the Northeast of its fury.
Major Hurricane Matthew is now a significant threat to the entire Eastern Seaboard Thursday through the weekend with with potentially destructive winds and excessive rains.
Heavy rain will soak drought-stricken areas of the mid-Atlantic over the next couple of days. Focus will then shift to Matthew and its potential to impact the Eastern Seaboard with more heavy rain later next week.
Summer has ended astronomically, but from a meteorological standpoint, there's plenty more warm weather heading into October from the Plains to the East.