Winter Storm Outlook

WINTER WEATHER UPDATE- MOSTLY RAIN FOR PHL

The last night’s 06Z  data has become available- both the NAM and GFS models have increased the QPF values to an average of about 0.50 inches water.

This morning’s NAM data also becoming available- the trend is for heavier QPF, and warmer atmosphere!

The NAM has increased the average temperature of the mid-level of the atmosphere to a level that is too warm for snow formation for much of the storm in Philadelphia and immediate northwest areas, as depicted by this map.  (Lower levels of the atmosphere (except at ground level) are at or below freezing, allowing sleet at times.)

Areas south of the red line- mostly rain, maybe some sleet.

Here’s the current best forecast-

Precipitation starts between 4-6 PM today, possibly as light snow or a mix of rain, sleet and snow.

A changeover to rain and rain-mixed with sleet will occur early.  Much of what falls will be rain and possibly some sleet;  at times, some snow may mix in at peak intensity if dynamic cooling occurs.   This event will be mostly wet, not white, in the area depicted south of the red line  in the inset map.

Precipitation may changeover to a brief period of light snow before ending about 2 PM.

Accumulations- zero to a coating, mostly on grassy surfaces.