Winter Storm Outlook

Heavy Snow for Tuesday still not a certainty in PHL

As has been the case this past season,  forecasts of snow have changed in the short term and that’s beginning to appear to be the case with the upcoming snowfall for this Tuesday in Philadelphia.  Here are the current trends–

  • The snow arrives earlier than previously predicted, now starting sometime Monday evening.
  • The NAM is much warmer than the GFS in Philadelphia with a further west track.
  • It’s  unclear whether the warmer NAM is correct.
  • Heavy rain is expected in PHL by daybreak Tuesday according to the latest NAM limiting snowfall totals ( 4 inches).  Heavy snow (15 inches) is expected if the GFS is correct in the immediate PHL area.

As a result of these trends, snowfall estimates continue to be uncertain in the Philadelphia area.

Expect further changes with this forecast.  Stay tuned.

[stbpro id=”info” caption=”Weather Tidbit”] With the switch to Daylight Saving Time, model data becomes available one hour later.  Early data previously available by 9:10 (NAM) and 10:25 -10:35 (GFS)  now become available at 10:10 (NAM) and 11:35 (GFS) eastern daylight time.

So, when you watch the 10pm and 11pm news/weather on TV, keep in mind that their forecasts cannot be based on the latest GFS model runs; it’s simply not available at broadcast time when Daylight Saving Time is in effect. [/stbpro]