So obviously there’s a lot of conflicting information about the storm for Sunday afternoon on through Monday. What to believe? What to trust? Fair questions for all, but I say don’t rush.
Look, there is a reason why I’m not putting snow maps out yet and it’s because the fact is that we are not in a time period where we can get all the data together. I am far more confident this morning on the threat for a significant winter storm for the region than I have been the past few days, and this has nothing to do with model trends, twists, and turns. However, it doesn’t hurt I have one of the best medium range models remaining consistent and the GFS caving in. Glass Joe at it’s best!
The factors going into this developing pattern that make me rather confident of a significant snowfall for the Philadelphia and New York City metropolitan area is a combination of various factors going into this storm. One, the ridge over the central Rockies is starting to develop this morning. Two, the upper disturbance over the Southwest is just as strong as advertised. Three, the powerful upper low over the northwestern Atlantic is setting up the blocking needed to slow the pattern down to allow for phasing.
Now the wild cards here is the nature of the phasing. The question I have this morning is if we are dealing with a phase of two disturbances or three. The slower, more powerful solutions on the ECMWF the past few days suggested that all three disturbance would phase, leading to the monster storm that was showing up on the model. That solution is still physically possible, but I don’t like to advertise historic events unless I have concrete proof, like actually being able to observe the position of that third disturbance over the western Great Lakes on Saturday night. However, I do like the idea of the disturbance over the Upper Mid West and the disturbance over the Gulf Coast phasing, interacting, and producing a storm that will track from North Carolina coastal waters towards the 40N/70W bench mark. Given all the data in front of me, I think this is going to end up being the most realistic solution. The one factor that would push this whole storm east is if the phasing on Saturday night is delayed. The phasing of the Sub Tropical and Polar disturbances have to happen on Saturday night or this storm is over the Atlantic. Remember, physics dictates the weather, not model trends.
So my forecast is as follows. For today on through Saturday I expect tranquil conditions for the entire region with high pressure taking hold. Temperatures will range below normal still with lows in the lower to mid 20’s and highs in the mid to upper 30’s.
On Sunday I expect increasing clouds in the morning followed by developing snow showers in the afternoon. Steady snow should move in from south to north on Sunday afternoon into the evening hours. I expect the worst of the storm to be Sunday evening on through Monday morning. The Monday morning rush hour is not going to be pretty. Unless the third disturbance phases earlier than expected, I am expecting the storm to move at a slow and steady clip. The only way this storm stalls is if the third disturbance phases with the other two on Sunday morning. The heaviest snowfall amounts will be along the coast with what I’m expecting to be an all snow event for the region. Another feature is very strong winds that will have a significant impact on travel conditions. I won’t be putting out snowfall totals until tomorrow as a preliminary map.
Weather conditions quiet down for Tuesday and Wednesday with clearing skies and temperatures remain below normal in the upper 10’s to lower 20’s for lows and upper 20’s to mid 30’s for highs. I stayed below MOS guidance to take into consideration of fresh snow pack.
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