Thursday 7:15 a.m.
Here is today's Northeast video:
Blazing heat with oppressive humidity affected many areas yesterday, but there were many thunderstorms across the country as well.
Hot summer weather continues, and high heat will be the rule for several more days. Each day the incandescent sun boosts the mercury into the sizzling 90s; the nights only have time to cool to the 70s before the oven is turned back on the next morning. Though the hot weather will continue , we know it can't last forever.
One day, someday, chilly winds will issue forth from the remote frozen hinterlands of the arctic. One day, someday, bitter blusters from snow-topped, ice-encapsulated tundra will freeze our faces, whip through the cityscape canyons and twist the brittle leafless branches of our wintry world. One day, someday, a dense fog will choke the dawn and nullify noon. One day, someday, teeming torrents of rain will gurgle through the gutters, aim down the alleys, puddle the parkways, drench the drains, saturate the sewers, waterlog the lawns and fill the fields. One day, someday, a dreary gray parade of leaden clouds will smother the skies all day. One day there will be relief, but that's not today, that's not tomorrow, that's not Saturday ...but Sunday looks like the day.
So, whence comes real relief? When will the furnace fires be banked back to accommodate us with comfort? And what could bring relief? Showers splashing in the streets while thunder booms and boils in the background? A laminar layer of clouds putting a lid on the thermal liftoff? A future front from the northlands with heat-hindering zips of northerly zephyrs?
The options have appeal once a smotheringly humid and blazingly hot heat spell has ensnared us in swelter, but the fact to be faced is that sometimes there is no relief for many days. Sometimes the heat holds and a cold front folds, the showers lose their cumulus towers or sheets of clouds get ripped and torn, eradicated in the consuming dryness of a summer high pressure area. In such situations where the simmering stretches, the humidity hangs on, the perspiratory swelter prevails, cooling is but a long-sought dream, heat seems to be everywhere.
But not this time. Cooler air is making a move southeastward from central Canada through the Great Lakes, and whether or not your location is hit by one of the potentially damaging thunderstorms as the cold front approaches, a cooling trend will occur as we go through the weekend. Even though the heat will be trimmed, only the upper Great Lakes and areas eastward from upstate New York and New England will have some really clear, pleasant, low humidity days. Farther south, any reduction in humidity will be brief. In addition, a wet weather pattern may become re-established from Chicago to Philadelphia and New York City only a day or two after the relief in temperatures is experienced.
This pressure map shows the strong circulation around the storm that brought all the warm air northward... and which will force colder air eastward next.
Looking at next week, the GFS ensemble spaghetti plot of upper air winds shows how much agreement there is among members of the ensemble (same model running multiple times using slightly different starting assumptions). The maps are from next Tuesday, Nov. 25, and Thanksgiving Day, Nov. 27. There is good agreement on the first map, but a lot of spread two days later.
The location of lake-effect snow bands is tightly controlled by geography, topography and wind. From this pressure analysis, we see why the wind favored heavy snow staying south of the hardest hit Buffalo snow belts earlier today.
If this timing works out, there would be good travel weather for the Northeast Corridor on Wednesday while snow showers cross the Great Lakes and reach the northern and central Appalachians.
This map from one of my tweets yesterday (accuElliot) showed the wind direction most favorable for heavy lake-effect snow in and near Buffalo. Just a minute change in direction greatly affects the location of the heaviest snow, almost as if you were operating a fire hose. The snow is so deep (more than 4 feet in spots and deepening) that officials were considering the use of high lift equipment to extract vehicles.
It suggests rain in the I-95 corridor and snow from the mountains of West Virginia and Pennsylvania to southwestern Maine. Other models and ensemble versions will be examined this weekend as we narrow down the uncertainties associated with this fast-moving storm. Whatever the form of precipitation, you can count on another shot of cold air behind it. Lake-effect snow will be common as well.