Monday, June 20, 2011

Midday Severe Weather Update

As expected, on the midday update, the SPC extended the enhanced risk of severe weather southward from portions of central & eastern Kansas to central Oklahoma for this afternoon & evening (as indicated by the red shaded area on the image above).

Strong to severe thunderstorms are already forming on the High Plains, and a Tornado Watch with enhanced wording ("This is a particularly dangerous situation with the threat of damaging tornadoes...") was just issued for portions of Nebraska and northwest/northcentral Kansas, valid until 8pm CDT:

Thunderstorms are expected to develop & quickly intensify across the watch area this afternoon and  track further toward the East/Northeast by evening.  Very large hail, damaging winds and strong tornadoes are possible in this region.  This threat of significant severe weather will shift Eastward into adjacent portions of eastern Nebraska and western through central Iowa later this evening.  Additional watches will be required for this region later this afternoon and/or evening.

Further Southward, thunderstorms are expected to form along the dryline in central & eastern Kansas by mid to late afternoon, and spread Eastward into the evening.  Very large hail, a threat of significant damaging winds, and a few tornadoes are possible in this region.  The greatest tornado threat in this region would likely occur prior to sunset, with the primary threat being significant damaging winds thereafter.

Significant wind damage possible in black hatched areas.

Isolated to scattered thunderstorms are also expected to form across central Oklahoma and part of extreme northwest Texas, along the dryline.  This activity is likely to develop by late afternoon into early evening.  While very large hail & significant damaging winds are the highest threats in this region, an isolated tornado or two cannot be ruled out, particularly during the first few hours of development.  This activity will move East/Northeast and could affect portions of Northeast and/or East-Central Oklahoma later this evening.

If you live in any of the areas specified in the paragraphs above, please continue to pay very close attention to the weather this afternoon & evening.  Be prepared to seek shelter if threatening weather approaches your area.  

If you live further to the East of the above mentioned areas (i.e., eastern Iowa, Missouri, and adjacent regions), be aware that one or more organized complexes of thunderstorms are likely to traverse Eastward during the overnight hours. Stay tuned for later information as this threat becomes more clear.  Damaging winds would likely be the greatest threat in these areas overnight.


The Planet Pink said...

Ugh, we had such a nice long break from the severe weather. :-(. So it's sounding like mostly wind and hail on the agenda for Tulsa tonight? I'm hopeful anyway...

Rob In Texas said...

Yes, at this point I think that's the main concern. The winds could be particularly fierce if you end up being in the right (or wrong) place at the right (or wrong) time. Will be interesting to see if this thing "lines-out" to your West, or if the storms remain more isolated to scattered in nature. At least we'll be able to see things form to your West and move that way... shouldn't develop right over your head or anything like that the way it looks right now...

Very large tornado on the ground right now just North of Hill City, KS - right exactly where I was a few weeks ago. Must have driven that road North-South 100 times that day... oh well... hopefully it stays out in the open, could get interesting though as it moves into southcentral Nebraska with some populated cities eventually in its path (assuming it stays on the ground that long - which it could).

The Planet Pink said...

Typically the isolated storms are the more tornadic ones, correct? And a squall line has the high wind threat? We live in a new subdivision with only scrawny baby trees, so I don't worry too much about high wind as long as we're home and away from windows. Now if I had a giant oak looming in my backyard I might feel differently! Will these storms be slow movers? Just wondering if they'll get in the area before nightfall.

Hoping and praying anything that forms stays rural!

Rob In Texas said...

You are correct that, in general, isolated supercell storms have higher tornado potential and less damaging wind potential - usually - but today the tables are turned a little bit. The temperature profile in the atmosphere is such that damaging "downburst" winds are possible with just about any storm that forms, regardless of configuration.

I was mainly referring to the 'line vs. isolated to scattered' question mainly to determine whether the entire area would be impacted, or just isolated spots if the storms remain more individual in nature. That remains to be seen at this time. The computer models are starting to want to make this a solid line before it gets to Tulsa, but we'll have to see what happens over the next 2-3 hours.

I would think the Tulsa area would be impacted (whether on a widespread or isolated basis) toward the 7 o'clock hour. Once the storms get going, they'll start moving at a pretty good clip, especially if its a line producing strong outflow winds.

The Planet Pink said...

Thanks so much Rob. I'll be watching closely, we might head out to the mall this evening to wait this one out, if it doesn't get too late before it arrives.