Daily Archives: Wednesday, June 3, 2020 10:35 pm

Philadelphia Area Weather Forecasts

LET’S TRY FORECASTING AGAIN

[su_note note_color=”#ffffff”]Updated Thu 08:05 AM — Last night’s models continue with the same timing of the thunderstorms Thursday evening.  Some early scattered activity possible about 5 PM, but the main thunderstorm complex is predicted for 10 PM -12 midnight. [/su_note]

[su_note note_color=”#ffffff”]Updated Thu 07:20 AM — Last night’s models continue with the same timing of the thunderstorms Thursday evening.  Some early scattered activity possible about 6 PM, but the main thunderstorm complex is predicted for 10 PM -12 midnight [/su_note]

So, no forecaster and no model had predicted the bow-echo storms at noon today. The high temperature never reached the highly advertised 90°+ that had been predicted.

Last night’s models as well as the early morning HRRR model were particularly misleading; they certainly led me astray.   Had I only stayed with last evening’s forecast…

Let’s move forward.

Thursday’s expected storms are forecast to occur between 6 PM and midnight, with mid to late evening (9-midnight) most likely. Heaviest rain and dynamics stay to our south.

Commentary

NO MODEL GOT THIS RIGHT TODAY

No model got this right today.  And I look at all of them. The bow-echo that formed had been predicted to occur up near Allentown.

Radar 12:06 PM—

Radar 12:06 PM

 

So how bad were the models?

Here’s the 10 AM HRRR model forecast  for 12:00 PM, (two hours before the storms hit) —

10 AM HRRR model run  forecast for 12 noon

 

Here’s the 11 AM HRRR model forecast for 12:00PM—

11 AM HRRR model run simulated radar forecast for 12 noon.

So even one hour before the storms hit, the high resolution model didn’t forecast this bow echo line of storms.  Wow!

 

Weather Updates

CHANGE IN FORECAST

The model runs done at 2 AM (06 UTC) show some large changes in the forecast.

I’ve put the posts earlier this week under the title “Forecast Uncertainty” because there’s been a disconnect between the GFS model (and also the Canadian model) and the higher resolution models (NAM, NAMNEST, HIRESW, and HIREF.)

Last night, the higher resolution models changed their tune.

In essence, they now lean towards the GFS model which has been most consistent about having most of the energy move to our far north and east earlier in the afternoon, with a second line moving mostly to our south.

The earlier line looks to stay north of Trenton.

The immediate PHL area will get some thunderstorms, but they don’t look to be too severe. Most likely timing is 5-6 PM. 

This morning’s most recent HRRR also has become less impressive with the storms in our area.

Could things change again with this morning’s models?  Yes.  But what had looked to be a very stormy 8 hours now appears to be run of the mill late afternoon thunderstorms.

It’s always more prudent for a forecaster to maintain a forecast that’s more dire, “just in case”, but you’re here to get the real scoop, not the hype.