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severe weather

SPC issues a moderate risk for tornadoes


After yesterday’s mostly-failed setup in which tornadoes were more scarce than expected in the Deep South, much higher instability today will likely result in stronger discrete storms that can mature enough to become tornadic. The SPC is targeting the 00z-04z time frame as the most dangerous as the low-level jet picks up, meaning nighttime tornadoes will be a big concern.


The Deep South is no stranger to these after-dark tornado setups, and I agree with the SPC’s forecast. With moisture and energy available right next door in the Gulf of Mexico, all you need is a proper storm system to move through to create a tornado threat. The winds associated with this system are fairly strong, and now the CAPE/shear combo is balanced enough where supercells can more reliably become organized enough to produce tornadoes. There are already multiple classic-looking supercells in Louisiana that are tornado-warned, and it looks like the southern Mississippi Valley will be in for a long night.

First severe threat of 2013 in the Mid-Atlantic

While the severe weather outbreak will be more focused on the southern states, I did this write-up just for folks in the Mid-Atlantic.

A widespread strong to severe wind event appears to be unfolding over the eastern half of the U.S. Tuesday into Wednesday, with isolated tornadoes also a threat, which is mostly across parts of the Southeast. The Mid-Atlantic has some opportunity for both on Wednesday, with the main threat obviously being a line of strong to severe winds.

We will be battling marginal lapse rates and pre-frontal clouds/rain, as we normally do in these early year setups. Very strong winds aloft (50-60 kt jet at 925mb!) suggests any sort of convection will bring down strong to severe level winds. With the strong forcing associated with the cold front, I don’t see much of a problem getting those winds to the surface. The only issue would be if a stable layer at the surface can linger ahead of the front, but that appears to be just a minor problem as the lift from the front should overcome the stable layer (if there is indeed a stable layer).

With dewpoints climbing into the lower 60s ahead of the front, we should be able to see a fairly strong frontal passage with widespread strong to severe winds. The main thing I’m watching now is the potential of a secondary low formation, which the NAM has (though that can’t be relied upon at this point). The Euro also develops a secondary low, but it comes later and further north than the NAM. If this secondary low develops before the front comes through, and if it’s far enough south, it will be able to back the winds more at the surface and would provide a greater risk for tornadoes in the Mid-Atlantic.

Active week for severe weather in the Plains

Severe weather is expected every day this week in the Plains as several shortwaves work into the central U.S. and the large-scale trough pushes eastward. While some days could have problems with instability and capping, the wind profile will be at least somewhat favorable for rotating storms and severe weather in the Plains.

Here’s the SPC maps highlighting the greatest severe weather risk areas through Saturday, with the threat expected to continue into early next week.

April 3, 2012 Texas tornado videos

U.S. Tornadoes owner/co-author Ian and I have been compiling tornado footage from the outbreak in Texas today. We’re still adding to it, but so far we’ve found 16 videos!

You can view them on the U.S. Tornadoes blog:

It might take a few seconds to load due to pulling in the video previews from YouTube.

Here’s one of the videos out of Kennedale, Texas:

Tornado Outbreak ongoing in the Midwest and Southeast

Multiple violent tornadoes are tracking across the Midwest to Southeast today as this High Risk event gets underway.

CLICK HERE for an animated GIF of the long-track debris ball in southern Indiana (image size 3.28 MB).

Here’s the latest SPC outlook:

UPDATE (6:45pm): Another long-lived debris ball went through West Liberty, KY. CLICK HERE for the radar loop (another large image).

UPDATE (7:45pm): Yet another long-lived debris ball… this one went through Salyersville, KY. CLICK HERE for large image goodness.

Mid-Atlantic Discussion – Feb 29, 2012

We end the last day of meteorological winter not with snow, but with severe as storms threaten the region for the second time within a week.

Currently, there are two tornado watches active in the region… one that extends into most of WV, and another that encompasses extreme southeastern WV and most of western VA.

Both watches are set to expire during the first half of the evening. The main concern with these storms is damaging wind, with isolated tornadoes possible and a low risk of severe hail. The main cluster of storms is moving through WV/VA now, but another cluster of storms is expected in the same areas in the early evening. Both of these clusters are expected to weaken as they get east of the mountains in the northern areas, but a risk for severe will continue into the overnight hours in southern VA and NC.

Mid-Atlantic Discussion – Feb 24, 2012

I can’t believe I haven’t done one of these since August… been too long.

The first real chance for severe weather in the Mid-Atlantic this year has arrived! Tomorrow’s looking increasingly promising for at least some severe wind threat in addition to an isolated tornado or two and maybe some hail. Strong post-frontal winds and brush fires are also risks with this system.

The latest models have been pushing out CAPE values of 500-1000 J/kg in parts of the Mid-Atlantic from DC down to eastern NC tomorrow afternoon, which isn’t much, but for February it’s not too shabby. The low-level jet will also be roaring in southern VA and eastern NC, which strong thunderstorms could mix down to the surface. There is enough directional shear in the low-levels for a tornado threat in southeast VA and eastern NC, which is where I plan to storm chase.

Behind the front, dropping dewpoints and strong winds gusting to 50-60+ mph will bring a risk for brush fires to the region as well, especially in the areas that were north of the recent snowfall from last Sunday.

All of this will be going on during the afternoon and evening hours tomorrow, though winds will remain somewhat gusty going into Saturday.

Here’s the latest forecast from the SPC (click the image for their discussion):