Winter Weather Update- Monday

The next few days will be a roller-coaster weatherwise.

First,  the Tuesday through Wednesday timeframe should be nothing like this past Sunday’s icestorm.  This upcoming storm on Tuesday will be much warmer and wetter.  While precipitation may start as snow, it will quickly turnover to sleet and then rain.  Some sleet buildup, but it should not be a major concern long term.

Unlike yesterday, temperatures at the surface will rise above freezing and the entire atmospheric vertical column will be much warmer.  So a turnover to heavy rain is expected Tuesday evening and the rain should continue into Wednesday.  There should not be the extensive ice buildup we have just experienced.

Rain continues Wednesday, as the low pressure system moves through to our north, and a cold front will move through sometime later Wednesday. Timing uncertain.

Temperatures will be in the 40s on Wednesday, not likely in the  50s as had been previously thought.

Wednesday night into Thursday, the GFS has the front stalling just to our south as a wave of low pressure develops and moves along the front. The final stalled position of the front is uncertain, but the GFS is pumping out some significant snow late Wednesday into Thursday (4-8 inches) right now.   Too soon to really know at this time.    Stay tuned.

So the only really impactful event may  be Wednesday night into Thursday.

Philly Winter Weather Update

This morning’s NAM has backed off from the heavy freezing rain this evening and has the precipitation ending about midnight.   Both the NAM and the GFS have total QPF values about 0.35 inches water, with the GFS correctly predicting this morning’s earlier onset.

Both models (for PHL) keep surface temperatures at freezing, with the upper atmosphere warming by late afternoon.

So a transition from snow to sleet/freezing rain still looks correct,  with greater snow totals  north and west of Philadelphia.

Accumulations will be difficult to predict, still 1-3 inches likely, but the concern is the amount of icing will we get.  The unknown  will be the actual rise in surface temperatures, both later today and especially tomorrow morning.  The NAM keeps us at freezing, the GFS brings us just above freezing.

I would bet on the NAM here.

 

 

Winter Weather Update

Latest NAM and GFS models show light snow starting mid to late morning with a changeover to sleet and freezing rain during the late afternoon. The NAM has much heavier rain/freezing rain in the evening. Not much in the way of accumulations, but significant icing conditions possible, especially north and west of the city.

The precipitation ends after midnight.  Temperatures may remain just around freezing, making things slippery for the early Monday morning commute.

Weather… and Other Things 'Up in the Air'