The latest mild surge of air in the Eastern Region pushed most temperatures well into the 50s Sunday afternoon. And, it looks like we’ll manage to squeeze two more warm days out of this pattern — and, of course, we mean “warm by early-December’s standards.” Assuming the guidance is “on the right track”, most temperatures during each of the next two days will be in the 60s.
The current surface map is showing a ridge of high pressure located off the Northeast and mid-Atlantic coasts, and that has been ushering in the mild air on a south to southwest wind during the past 24 hours. A slow-moving front that is pushing across the Great Lakes, the Midwest and much of the Lower Mississippi River Valley should not reach the Eastern Seaboard until Tuesday evening. One of the things that is “slowing down” the progress of this front is a wave of low pressure which is developing along it. This feature may lead to some flooding from Arkansas to southern Indiana during the next 12-24 hours. Many of the global models also insist that a SECOND WAVE of low pressure will develop along this front Tuesday night and Wednesday. A vigorous parcel of jet stream energy is being forecasted to move across the southern Plains and into the Tennessee Valley within the next 60 hours (or, by 7 p.m. Wednesday), which will aid in “spinning up” the second wave of low pressure. Previous model runs (prior to last evening) were pushing a shield of precipitation through the mid-Atlantic states on Thursday, or an area that included much of eastern Pennsylvania, Maryland, Delaware, New Jersey and southeastern New York — but it is now showing a “flatter-looking” wave moving across Virginia and the Carolinas. Conversely, Sunday night’s 00z runs of the both N.A.M./W.R.F. and the European was still showing this kind of a wetter solution for the coastal plain, and in areas as far north as southern New England on Wednesday and Wednesday night. So, we’re going to allow for this rain in our forecasts on Wednesday AT ANY TIME (previously, we only had it during in the morning) and most temperatures will probably be no higher than the 40s. That rain, which will probably last into Wednesday night, could mix with or even change to wet snow before ending late — primarily in the higher elevations located north and west of the I-95 corridor.