It’s been an active afternoon and now evening of severe weather over the Central Plains and the threat only increases tomorrow with Wednesday for me, being the big day. If you check out last night’s video I explain and show you the upper chart explaining why.

An upper disturbance running from the Four Corners up into Kansas and Nebraska today has been the trigger for today’s storm’s but during Tuesday a larger area of upper level energy will race through the Central Plains as the western trough deepens, the atmosphere cools aloft while heat and humidity build at the surface.

Remember it’s as the lapse rate increases (measure of temp with height), the atmosphere is more primed for thunderstorm production, however the deepening western trough  also increases the SW’erly jet, draws air in from surrounding areas, warm, moist/cool, dry at the surface and these flows changing direction with height (known as directional shear) is what creates the spin for these storms to transition into dangerous supercells.

Here’s the SPC (Storm Prediction Center’s ‘risk area’ today.

Tuesday

Wednesday

While there’s a tornado risk this evening and also tomorrow, I believe the dynamics are more in place and merging Wednesday. We could see an outbreak of tornadoes begin tomorrow but peak on Wednesday. It wouldn’t surprise me if we see upwards of 30 to 40 tornadoes over the next 48 hours.

Here’s the CAPE values for Wednesday.

45 hours

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48 hours

Plenty of juice to fuel the storm’s Wednesday all the way up to the Dakotas, Minnesota and Wisconsin as well as points further south.

As well as the severe thunderstorm risk, there is also an ongoing flood risk as we see big time rains over the heartland with a focus over Iowa.

Here’s the latest QPF printing an additional 4 or 5 inches of rain over the next 72 hours, with continued focus on Iowa. Locally we may see 6 to 8 inches in some spots.

Here’s the next 7 days.

While the trough gets carved out in the West, so the ridge pumps heat from the Southern Plains up into the Ohio Valley and by Thursday, the Big Cities from DC up to Boston shall be flirting with 90 degrees.

The GFS shows DC and Baltimore within 90 degree air but not Philly, NYC or Boston but I think there’s enough SW surface flow and sunshine with temperatures to comfortably hit 90 in all the major cities Friday, if not Thursday. Thursday will be close, 90 for DC-Baltimore but Philly, NYC and Boston may get close, perhaps 88 or 89.

Here’s the ECMWF upper chart for Thursday.

850 temperatures are warmer by Friday over the Mid-Atlantic.

We could see 2, perhaps three days of between 88-92 in the Big Cities before the trough digging into the Upper Midwest begins to chop down heights further east.

This year has been a very progressive pattern and when looking out over the next few weeks, there is little sign of any lockdown summer pattern. In other words I think we see a first half to June where warmth comes in and 2-4 days later, it’s gone as a trough is always quick to follow.

By next Tuesday the trough is back in the Northeast and that means a return to 70s, possibly low 80s.

Here’s a look at the CFSv2 over the next 4 weeks.

Week 1-2

Week 3-4

Notice the model has the East cooler than normal in weeks 3 and 4 which takes us all the way to June 23.

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