Well, the warmth will begin attacking the cold here at the surface by this time tomorrow night.
The culprit is a strong upper air system leaving the desert southwest and a building area of high pressure off the Southeastern United States Coast.
Both of these systems will act together to erode the very cold air we have been seeing here in the Middle Atlantic States. As their is no NAO Blocking this storm will come right up at us in front of the next Arctic push and bring a rainstorm to the Delaware Valley with even some minor stream flooding possible. As the NAO is Positive their is nothing to lock in the cold we have been having and deflect the storm south or spawn secondary development at the coast to the disappointment of snow lovers in the Northern Middle Atlantic.
Take a look below as the warm air invades from the Southwest! There will likely be enough mixing of the Upper Atmosphere to get our temps near or just past 60 degrees here on Wednesday into Wednesday Night it is not out of the question to get some rare January Thunderstorms very late Wednesday Night or Thursday at the very least some heavy downpours. It appears we have over an one to two inch of liquid type of event and it is most likely all rain.
The Warming will however come at a price Monday in the form of some snow changing to sleet then freezing rain for a time especially Philadelphia North and West.
While we will warm up this week the warmth will be brief as more cold air will rush down from Central and Eastern Canada by weeks end behind a fairly strong cold front on Thursday.
Warm air over the top of very cold grounds is a recipe for Freezing rain though on Monday at this point it looks to be after the Morning Rush Hour but we shall see. There could always be a bit of freezing drizzle get in early which could set up for a very tricky commute Monday.
10m Freezing line is south of Wilmington Delaware and the Mason Dixon Line so we do have to watch for some snow, sleet, then freezing rain with freezing rain being the biggest threat!
I would think at this point Winter Weather Advisories may be needed for Monday Morning especially Northeastern Maryland, Northern Delaware, Western and Central New Jersey points north and west.
School Closing Meter is at 30% mainly because of timing which appears to be after the morning commute but freezing drizzle can be sneaky if it gets in here earlier.
Kevin, I gather from your post and my rudementry model reading skills that this storm its timing and ptype will be very hard to pin down and vary greattly across even a small area on 50 miles N to S. I was trinig to plan staffing levels a day early which does not look to be too feasible rigght now.
I concur. I am placing clipper+ snow from this storm affecting the Delaware Valley in the category of only slightly more believable than back end snow which by the way is only slightly more believable than Manti Te'os girlfriend. Oh wait she wasn't real........
The euro shows the clipper around the 2nd as well.
Gfs also shows another chance at snow around the. 5th - 7th, so winter isn't done as of yet, still 2 chances within the next 10 days of some snow. I refuse to get suckered into another clipper+ though, well see what happens with it during the week.
The 00Z GFS comes a little more in line with the NAM in so far as it is a little slower in eroding the cold air, it still predicts just rain, but the warming at the surface is slightly slower, if we can get better agreement tomorrow we will be able to forecast this with more certainty. If not we'll throw out all the models and just see who can forecast this right based on hard data and climatology.
00z GGEM shows a very nice clipper on the 1st-2nd of feb. digs deep into the tn valley and then ne right south of New Jersey. Right now shows a 3-6" snowfall. It's 6 days away. Gonna be another long week if this shows up on the other models, this amped. Gfs has it, but 1-3" at best.
Very defined right in that time frame +PNA. Hopefully it stays this way. Could be a very nice trough for this to dig in and grab some southern moisture only time will tell, keep an eye out for feb 1-3.. Could be another 2-4" 3-5" snowfall coming. Setup looks nice for something bigger, but I'm not gonna worry about that at all until I see this on the gfs and euro. The gfs still has that god forsaken storm sitting in the GoA ruining any chance of a big storm around here.
The NAM is showing a period of snow before the changeover on Monday and looking it over I can see why, but I think it is a little slow with the 500mb and 700mb temperatures, which may reflect that it is also too slow in warming the surface, which for a layman would be a logical conclusion, but knowing how air that has been cold for days, and is so dense, it lends credibility to the thinking that the cold air is the surface will be slower to erode then forecast, as usual and the air at the mid levels will warm a little quicker then forecast meaning the precipitation starts as freezing rain and stays that way for a while. The NAM seems to cut the precipitation off right when it would've gone to all rain. That solution would be the worst case scenario for commuters and would not be a bad hypothesis at this point, this will be an interesting forecast tomorrow for sure.