There may be sun out right now, but the models are consistently showing snow to begin in PHL by 1 PM today. Latest NAM model has been consistent in cranking out a QPF of > 0.80 inches of water, with about 0.40 inches falling as snow. I’m still going with 4-7 inches of snow in PHL before a changeover to sleet and freezing rain.
The trend has been for an extended period of cold air at the surface to remain in place, even if the upper atmosphere warms a bit.
The changeover to sleet and rain will tamp down final snow totals however extended period of surface temperatures below freezing will likely cause extensive icing, especially north and west of Philadelphia. Driving later this afternoon and this evening may be very difficult. Large storm snow totals sound impressive, but this sort of snow to ice mix can be more dangerous.
I don’t think this is going to be a storm where the rain washes the snow and ice away.
Latest NAM model data suggests at least 4-7 inches of snow, starting about noon and continuing into the evening before a changeover to sleet and freezing rain later Saturday night. Higher amounts possible north and west. Freezing rain may be extensive.
The trend is for more precipitation and prolonged colder temperatures, even in Philadelphia. The latest NAM also suggests that the anticipated warmup late Saturday night and Sunday may not get as warm as previously thought.
While there’s been less advance coverage and hype about this storm, tomorrow’s weather has the potential to be one of the more significant snow and ice ‘events’ of this winter.
[#PAwx] The latest models are out and both the NAM and GFS have snow for Philadelphia, starting about 1 PM and continuing through the afternoon and early evening. As much as 4-6 inches possible during the afternoon before a changeover to sleet and possibly freezing rain early evening on Saturday. An eventual changeover to rain around midnight is expected.
The models often predict warming of the lower atmosphere to occur more rapidly than actually occurs. As a result, a period of freezing rain may occur early evening and areas to the north and west may have an extended period of icy conditions.
For whatever reason, the usual hype from the TV forecasters hasn’t yet occurred with this storm, but this heavy snow changing to extended freezing rain is more of an ‘event’ than other recent snows. I guess because it will change to rain, the big snow totals aren’t as sensational. The last time this was glossed over, it was incorrectly labeled a ‘freak ice storm’ instead of a bad forecast.
This sort of weather Saturday afternoon and early evening really is something to keep an eye on since driving can be difficult and the possibility of extended icy conditions is real.
Latest NAM suggests the possibility of some significant snow for Saturday afternoon before changing to sleet and freezing rain Saturday evening. Ground temperatures have been very cold and snow covered for a long period. The potential for prolonged icing exists.
As had happened in the “freak” ice storm in January, the models may be too quick in predicting the ground to warmup . So very difficult driving conditions possible late Saturday afternoon. Stay tuned.