Severe Weather to Impact Millions Today

A pair of upper level disturbances will led to severe weather in multiple parts of the US today.  The most significant threat is for tornadoes in the Great Plains as an upper atmosphere low lifts out of the Rockies.  In the Northeast a warm front has lifted just south of New England which has led to periods of rain in Southern New England, snow in Northern New England.  As result of such cold air aloft the biggest threat in Philadelphia and surrounding areas is hail.  Here is the Storm Prediction Center threat graphic

SPC Day 1 thunderstorm outlook (valid through Tuesday 8 am EST)

Here is the surface analysis as of 8 AM EST

WPC surface analysis 8 AM EST

That stationary boundary is a clear divided of where the warm and cold air is in the lower 48.  Anyone in New England right now knows what I mean.

US 2 m temps 10 AM EST (image Weatherbell)

So by 2 PM the warm front will halt its progress north.  A wave of low pressure will slide south of New England leading to heavy rain until about 2 PM.  The good news for New England is that high pressure will take over and led to seasonable weather through the weekend.  All storm will slide south out to sea while temperatures remain around 60.  As the afternoon goes in in the Plains more thunderstorms will erupt.

WPC surface forecast 2 PM

Here is the simulated radar for 6 PM EST/5 PM CST.  It looks like some super cells will begin to erupt by this time in Oklahoma and Kansas.  A strong complex of wind, hail, lightning and rain will move along the cold front through Missouri, Illinois, Indiana, Kentucky at the same time.

14z HRRR simulated radar 6 PM EST (image weatherbell)

This lines up well with the SPC tornado threat area

SPC Day 1 tornado outlook

I'm not sold on Nebraska as it may not get warm enough but it will be close.  Central Kansas and West of Oklahoma City are my best bets to chase today.  This whole area moves east for tomorrow but the tornado threat will be less than it is today.  I'll let this play out and summarize the event tomorrow.

-Zack Green