PM- As many trick or theaters attempt to score some free candy, severe weather may hinder their efforts tonight. A round of thunderstorms and strong winds are expected to impact the eastern third of the country.
Models generally agree that a line of strengthening thunderstorms will begin to develop around 7pm EDT. This line with be from western Pennsylvania to central Georgia at the time. This line will move east and will reach Washington DC by 10pm.
The line will weaken east of DC but that is not before a chance for damaging winds, tornadoes and heavy rain. The line will bring behind it much cooler air and lowered dew-points making for a refreshing feel from the above average temperatures for many.
Models are pinpointing amounts for .5-2″ of rain with locally higher amounts possible. Even though that is not an incredible amount of rain, it will be very disruptive considering it is Halloween night.
This combined with the fact that all this rain will fall in a very short amount of time will make for localized flooding. This rain combined with the wind could make it easier for trees to come down, especially since most of them are still full of leafs.
Wind gusts are going to be 40-50mph for most. The strongest cells can see gusts topping 60mph in the line of thunderstorms.
However, closer to coastal areas, the front will be stronger. This is due to the proximity to water and the lessening terrain. Gusts for these areas could be 60 to 70mph in localized areas.
This will cause major problems with power outages likely. The actual line of thunderstorms will be greatly weakened by the time it hits the coast but heavy rain can still persist. The heavy rain and extreme winds will cause many trees to fall as the ground will be saturated.
The HREF model is aiming for a maximum of thunderstorm potential from North Carolina to southeastern Pennsylvania. Updraft helicity measured the rotation in individual thunderstorms.
The HREF is aiming for many rotating supercells with have a chance at dropping tornadoes.
The significant tornado parameter as depicted by the HREF is not off the charts but enough for tornadoes to develop. With these two graphs as well as looking at shear, I have come up with two areas where the worst severe weather will be.
I expect north central North Carolina through south central Virginia. My second area of concern is just northwest and west of Wasington D.C. through extreme southern and eastern Pennsylvania.
Severe weather to impact east coast Halloween night. Overall, be careful and monitor the forecast tonight as there is a good chance for dangerous storms to develop tonight. Especially considering tonight is Halloween many could get caught in rain and lightning in the blink of an eye. Keep up to date with the latest warnings and updates on my twitter @MikeBWeather. Have fun tonight and stay safe. -Michael Barletta