There’s been a lot of talk about heavy thunderstorms Tuesday afternoon as a front moves through. The models do show the front moving through early evening, with showers and thunderstorms between 4 and 7 PM. However, several models tonight have anything heavy moving through to the south of the immediate Philadelphia area.
Indeed, the models are not that impressive with many severe storm parameters in our area. Severe storm parameters such as helicity and shear are not that high, especially with the latest HIRESW model. Precipitable water values are not that high. Available convective potential energy (CAPE) is moderately high, but it takes more than high CAPE to get severe storms. We’ve seen much more impressive setups in past weeks and months.
As always, it’s best to keep an eye to the sky, but I think the heaviest storm activity will pass to our south between 4 and 7 PM.
Last night’s HIRESW-ARW-MEM2 came through, accurately forecasting the showers that moved through around 12 – 2 PM.
Here’s last night’s HIRESW—
Last night’s HIRESW-ARW-MEM2 forecast for 2PM Sunday. (Click on image for a larger view.)
Here’s the current radar at 1:39 PM—
NEXRAD radar 1:39 PM Sunday. Courtesy of weathertap.com (Click on image for a larger view.)
That’s about as good as model forecasts get.
There’s been uncertainty regarding the shower/thundershower potential on Sunday. High humidity, heat and instability suggests that some showers and thundershowers are likely during the day.
Tonight’s models just becoming available have the greatest dynamics just south of Philadelphia and the majority of the models keep the showers just south of our area.
The exception is the HIRESW-MEM2, which continues to forecast showers and thundershowers further north into our immediate PHL area, from 11 AM through 3 PM. As someone who looks at the models as my daily crossword puzzle(s), the HIRESW-MEM2 has been particularly impressive this summer in predicting these sort of convective storms. So, I’m betting on its forecast for Sunday.
The models have more consensus about another period of showers/thundershowers around 10 PM Sunday evening, as another wave moves through.
