Wednesday, 11:55 a.m.
The first half of winter is about over. The official halfway point of astronomical winter is Monday - 45 days in from the winter solstice and another 45 to the vernal equinox. Given how cold it has been so far this winter, especially from the northern Plains to the East Coast, that may seem like it's a long, long way away. I'll give my annual countdown to spring out late this week or early next week to break down that ramp up to spring!
January will go down as decidedly cold for most of the country from the northern Plains to the Southeast. The core of that cold has been centered on the Midwest and Great Lakes into the Ohio Valley, with most places running 7 to 9 degrees below average. If you factor in the storm of the past 36 hours that brought ice and snow from parts of Texas across the Gulf Coast region into the Southeast and coastal mid-Atlantic states, we're about ready to close the month with a pretty decent snow cover:
That storm is gone, but the cold remains. High pressure now stretches from Texas to the Tennessee and Ohio valleys, and tonight the surface high will stretch from Virginia to Alabama. Underneath that high, ideal radiational cooling conditions will prevail - clear skies, dry, cold air mass, no wind and, in many, many places, some fresh snow on the ground. That means another frigid night tonight with lows in the teens throughout the interior South and some single-digit lows from central and eastern Tennessee and northeastern Alabama to parts of the Carolinas and points north. It might be a little too soon to make such a bold statement like this, but it could well be the coldest night for the rest of the winter season across the South and up into the East. That should NOT be taken as it won't get cold again! It simply means to see temperatures this low in the absolutes may be very hard to do.
With the surface high sliding to the East Coast on Friday, it will keep the East relatively quiet, with one caveat. The disturbance rolling by the the Dakotas this afternoon is pulling some snow out of Montana, and it will streak across parts of the Dakotas into southern Minnesota tonight, then across northern Iowa, northern Illinois and Wisconsin into Michigan tomorrow. There could be a few inches of snow in these area, and arctic air will again be pulled south into Montana and the Dakotas tomorrow and into the Midwest and Great Lakes tomorrow night.
As this feature darts eastward tomorrow night, the moisture associated with it will begin to dissipate, with a little snow in northern Ohio and a few snow showers across upstate New York and northern Pennsylvania. South and east of there, there will be little or no precipitation of any kind on Friday. Instead, milder air will be pulled into the mid-Atlantic and southern New England.
Meanwhile, it has finally turned a little wet in the West! The long-term upper-level ridge that had kept it very dry for quite some time has finally broken down, and there will be some rain at times the rest of today across northern California into Oregon and western Washington, with some snow in eastern Washington. That moisture is spreading into Idaho and northern Utah as well as western Wyoming and Montana.
A couple of disturbances will break through what's left of the upper-level ridge and cut across the Rockies tomorrow and Friday, eventually causing low pressure to form in the lee of the Rockies on Friday. Some moisture will streak across the central Plains toward the Ohio Valley Friday and Friday night, with part of it being snow and ice, but part of it rain for a change as the cold air begins to retreat Friday night.
By the end of Saturday, an actual low pressure area will be cutting across the Ohio Valley toward the eastern Great Lakes. Here's the 12z NAM surface forecast for Saturday evening:
That implies a nice little surge of mild air into the Ohio Valley and mid-Atlantic states Saturday afternoon, and if there's any sunshine, some 50-degree readings are not out of the question as far north as Washington, D.C.
In contrast, it will snow north and west of the track of the storm, and that is likely to include portions of Nebraska and Kansas into northern Missouri, southern Iowa, northern Illinois and Michigan. It could also include upstate New York and New England late Saturday and Saturday night into early Sunday.
Sunday looks to be relatively mild in southern New England and the mid-Atlantic states, as the arctic air behind this front will only seep into these areas later in the day and at night.
That then gets us to Monday, the halfway point of winter, and the break is over. By then, it will be plenty cold across the northern and eastern Rockies, the central and northern Plains and the Midwest into the Great Lakes and Ohio Valley, thanks to high pressure building into the Midwest. With the western ridge gone, more disturbances will roll inland through the West and across the central and southern Rockies. This will set the stage for a cold and storm start to the second half of winter, with at least three separate storms to track next week.
Fifty days is really a long way off until spring!
A building upper-level ridge of high pressure in the West will promote hot, dry weather in the Northwest, while a downstream trough brings cooling through the Midwest into the Great Lakes and Ohio Valley.
A pattern more typical of late July and early August is shaping up around the country, one with heat and humidity, but with fewer incidents of severe thunderstorms and flooding.
There will be plenty of heat and humidity from the southern Plains to the East Coast this week while much cooler air prevails for a time over the Northwest to the northern Plains.
Severe thunderstorms raked across the Midwest and Ohio Valley in the past 24 hours, with more on the way this afternoon. The pattern will repeat itself over the next week.