Showers return tonight. Thunderstorms are likely over the weekend, possibly strong.
Our next storm system arrives quickly later tonight and into Thursday morning riding in along that "northwest flow" aloft bringing showers after midnight and into Friday morning.
This quick hitter exits just as swiftly with clearing in it's wake by Friday afternoon with seasonable temps in the middle 60's.
The weekend starts off on a dry note with a mixture of sun and clouds on Saturday. Temps are looking to be on the cool side with highs only returning to the upper 50's to near 60 degrees. We'll feel those warming winds arriving on Sunday as temps soar into the middle 70's, possibly into the 80's if today's data verifies.
This heating will combine with the return of low level moisture to produce instability. This is something we haven't seen much of so far this season. That combination of warmth and humidity, which results in instability, will likely result in scattered thunderstorms during the afternoon/evening on Sunday.
Could these storms be strong?
A basic measure of instability in our atmosphere is something called CAPE, which stands for Convective Available Potential Energy. These are measued in something called Joules/Kilogram... for the purpose of this weather blog, we'll just call them "units". Current data, provided by the European model below is showing numbers between 500 units for our western counties and upwards of 2,000 units for our eastern sections.
While 500 units will get a thunderstorm started, it's typically not enough to create "severe weather". However, if we get closer to that 2,000 threshold, then strong storms will certainly be possible as this represents a decent amount of instability.
Another factor that we'll be watching is the arrival of a "low level jet". This is a ribbon of fast moving air located a short distance above the surface. At about 4 to 5,000 feet in this case as shown by the GFS below.
This animated loop shows winds increasing late on Sunday and into Sunday night. This is important because sometimes thunderstorms can tap into these winds creating damaging gusts. Timing will be key here. Right now, it appears that the stronger winds will hold off until after we reach peak heating or after peak instability. If they arrive a little sooner, this could be problematic.
So what do I think?
I think we'll see thunderstorms and a few could be on the strong side late afternoon/early evening on Sunday. Nothing widespread, but something to watch for as Lilac Festival comes to a close.
Updating timing of tomorrow morning's showers and the latest on weekend storm threat on tonight's WxLIVEat945. See you then!