Category Archives: Updates

SATURDAY FORECAST UPDATE- NO SNOW

The evolution of the storm that had been predicted to bring snow to Philadelphia continues.  Lets’s cut to the chase- there’s no snow for Philadelphia on Saturday. Here’s the current model forecast:

The cold front is expected to move through before 8 AM on Saturday morning.  Depending upon your model of choice, either light rain showers (GFS), or close to zero precip (NAM) falls before 8 AM.  Temperatures too warm for snow during the precipitation before daybreak; after the front passes, it will be unseasonably cold for April on Saturday, but dry.

So Saturday is dry after 8 AM.

The front sinks further south and low pressure develops much further south than had been forecast earlier in the week.  Any snow will be much further south than our area.

GFS Forecast
GFS Forecast Saturday night 2 AM

Depending  on the sharpness of the upper air flow, the low pressure may track as a coastal storm that brushes south Jersey Saturday night (GFS) or misses our area entirely (NAM) Saturday night.   It will likely miss us, since I favor the NAM in these situations.

 

SATURDAY FORECAST UPDATE

As mentioned earlier this morning, things have changed considerably with the model forecast for Saturday. The low pressure that was expected to slowly move along a sinking frontal boundary, with heavy precip over-running the front now appears to move more quickly- the precipitation moves through quickly and the low doesn’t intensify until it’s further to our south.

As a result, there’s not enough cold air in the mid levels to support snow around PHL until after the precip moves through.   Also, there won’t be enough heavy precip to cause enough dynamic cooling.

The timing has changed.  Most of the precip occurs before sunrise and ends before noon.  Most of the precip will be rain.  There may be a brief period of rain mixed with snow around daybreak, but will likely change back to all rain maybe mixed with sleet early morning before ending by noon.  There should be little to no accumulation in Philadelphia and the immediate surrounding areas.  

Anything that falls will quickly melt.

I’ll keep an eye on any further changes.

BTW, there’s a chance of rain showers/ flurries early tomorrow (Friday) morning.

CHANGE IN SNOW FORECAST

The 2 AM runs of the GFS and NAM show almost no snow for Philadelphia and north.   – The precipitation develops mostly to our south.

Thermal profiles in our area are too warm for snow for much of the time, so we will get mostly rain.     There may be a brief changeover to snow before ending but accumulations look minimal at this time.

Will continue to watch this.

STORM UPDATE 5:30 PM

Well, I said if it were January, I’d be predicting 8-10 inches. The March sun angle did little to reduce accumulations at this high precipitation rate.

So I may have underestimated totals.

In the far northwest suburbs, considerable snow accumulation has occurred. Nearer Philadelphia and adjacent NJ, there’s been quite a range, significantly lower in some cases.

Current radar is impressive, but upper air analysis shows dryer air moving in above 22,000 feet (in brown)

Courtesy of weathertap.com
Drying in upper atmosphere moving in (brown shade)

A few more inches of snow possible north and west, but the high precipitation rates should start diminishing around Philadelphia soon, as the dry air rotates in.  Some snow still likely until after midnight.

Official snow reports can be found here.