An Arctic front has slipped through the region and the winds throughout most of the Mid-Atlantic region have now shifted to a northwesterly direction (latest National Weather Service observations: http://www.wrh.noaa.gov/mesowest/gmap.php?zoom=7&extents=37.422526,-79.650879,42.472097,-70.532227&density=1/). This subtle change to the winds in speed and direction will not cause a dramatic temperature change around here as did the same frontal passage earlier in the week across the Rockies and Northern Plains, but it will set off a chain of events that will lead to a sustained “colder-than-normal” weather pattern here in the Mid-Atlantic region. Temperatures tonight will drop well down into the 30’s across the region and, as a second push of Arctic air arrives on Thursday, be held primarily in the 40’s for highs tomorrow afternoon. Once this cold pattern sets up, it’ll be tough to dislodge and it looks like it’ll stick around through much of the remainder of November.
As far as snow chances are concerned, the first threat for snow shower activity around here will come later tomorrow night into early Friday as an area of moisture rides up the coastline at the same time even colder air pushes in from the northwest. Another and more important storm is possible early next week as an area of deep moisture will likely move to the northeast from the Gulf of Mexico. Odds favor rain in the I-95 corridor, but this situation will be closely monitored over the next few days. Another Arctic blast will follow this next storm in the Tuesday/Wednesday time frame and this next shot will likely be even colder than this initial cold air outbreak.
Elsewhere, temperatures this morning were pretty incredible from the Pacific Northwest to the southern reaches of Texas with widespread record or near record lows (blue circled areas on plot; courtesy coolwx.com). Temperature departures from normal in parts of the Northern Rockies earlier today were in excess of 40 degrees. Perhaps the most impressive temperature reading was in Casper, Wyoming where an all-time November low temperature record was set at -26°F shattering the old record of -20°F set in 1947 (and we’re not even at the midway point for November).