Here we go again: severe weather outbreak possible Nov 27/28

[jkt21787]

All right, I know its way out there, but given the holiday period forthcoming, I thought it was time to begin a discussion. Unfortunately, there could another severe weather event, possibly an outbreak, coming up Sunday (November 28) into Monday (November 29).

I am using the 12z and 18z GFS as a guideline for the following information, FYI. Well, a low pressure will probably form somewhere in OK or KS early the day on Sunday, with a 500 mb shortwave trough beginning to dig across this region. The GFS deepens this low quickly as it moves northeast through KS into MO/IA by early Monday. The 500 mb trough will begin to take on a negative tilt Sunday and continue Monday as it slides east. Negative tilted troughs are notorious severe weather producers. VERY strong jet dynamics, perhaps stronger than seen with the outbreak on November 15th, will be present, with a LLJ from the SW at 50-65 knots, a 500 mb jet of 70+ knots, and an upper level jet of 110+ knots. Wind profiles indicate veering with height, a sign of directional shear, with obvious speed shear as well. Surface winds appear to back as well across the warm sector in the boundary layer especially closer to the low pressure as is often the case. This all creates a very favorable shear environment for supercell thunderstorms.

A main question here would be moisture return and instability. GFS is easily progging the warm sector to see 60+ tds, and given rather good performance with this aspect on the 15th event, I have no reason to disagree. Thus, plentiful moist air should be expected within the warm sector south of the warm front and ahead of the cold front.

The current GFS data would storm initiation in the afteroon Sunday across portions of OK, KS, TX, LA into the AR and MO ozarks, with activity spreading east Sunday evening, reaching the Mississippi River about Midnight, then through the lower OH Valley, Middle TN Valley, and AL through Monday Morning, entering GA, eastern KY area Monday Afternoon. GFS appears to show a potent squall line along the front.

Bottom line...I expect a decent and possibly significant chance of severe weather across the Southern Plains, Ozarks, and Arklatex into the MS and Western TN Valley on Sunday Afternoon into Sunday Night, possibly spreading as far north as MO and the western OH Valley. Then this threat extends east through the remainder of the OH, TN Valley on Monday, even affecting some gulf coast states (namely AL and GA). With ample mositure return expected along with very strong wind fields, at the least, a potent squall line with the potential for widespread damaging winds would be expected. With expected shear, and possbile decent instability, supercells and at least a few tornadoes couldn't be ruled out. At this time, I'm not saying this will be as big as last Tuesday's (15th) event yet.

GUT FEELINGS...I think the GFS is a little too far north and maybe a little fast with the low, perhaps a low track from OK into the Ozarks, MO and the lower OH Valley may be more favored. Also again, because of past GFS performance with these events, some slowing by about 12 hours or so may be noted in upcoming GFS runs.

I hope all in the possible threatened areas keep advised to the latest forecasts. Many NWS offices are already talking about severe potential with this system, and expect this to ramp up significantly over the holiday period if models remain this potent with this system.

CORRECTED DATES OF CONCERN IN THE TITLE..
I do want to add that if this system slows as could be the case from what GFS is showing now, the 28th would be the main day of concern.

[wxmann_91]

Certainly looks like a good event, but with the scouring of the GOM by the last front, moisture return is once again going to be the main concern. I would look at it more but I have to go soon and I've got a rehearsal next Monday.

[jkt21787]

Certainly looks like a good event, but with the scouring of the GOM by the last front, moisture return is once again going to be the main concern. I would look at it more but I have to go soon and I've got a rehearsal next Monday.

Moisture return will be the real question, but as cited before, GFS shows easy moisture return, and it did well last time, so I can't flat out disagree with it. This is my current main concern. This is a very dynamic system, much like the 15th, so I am always concerned with these setups.

I will be out of town with just intermittent internet access Thu through Sun so I may not be able to post a whole lot between then. Hopefully some if others (if not you wxmann), can keep people here up to date if I can't either.

[wxmann_91]

Hopefully some if others (if not you wxmann), can keep people here up to date if I can't either.

No prob.

The extended SPC outlook highlights a risk area centered near the Ark-La-Tx.

http://www.spc.noaa.gov/products/exper/day4-8/

[jkt21787]

Can this entire thread be deleted?

0z GFS craps this entire setup, tries to show something Tuesday from the OH Valley to TN Valley but nothing significant.

It is the GFS at its best. Well it could return next run who knows. Still don't let your guard down yet.

[Yankeegirl]

Well I am in the threat for the severe weather .... Lets wait and see.. Done this before and nothing panned put...

[gwalls]

Well, I hope it continues in the new direction it has taken. I mean, come on, after Thanksgiving, I officially switch to Christmas mode. I want cold weather!! I want snow storms, not severe storms. Reading about the snow going on up north, I'm so jealous. I think I live in the wrong part of the country!

[jhamps10]

I feel just like everyone in the gulf coast after the hurricanes this year. It seems like every week this month we have had a severe weather outbreak. And to make it worse, I am moving to St louis next week, and guess what's in the heart of the bullseye..... St. Louis! I guess I am a storm magnet.

Some good news out of this storm saga, People are really taking severe weather ANY time of year seriously now. Remember on the 15th when schools let kids out early cause of the threat.... That would have NEVER happened before November 6th. Another good thing, I was watching the 10 o'clock news, and if you live where there is a Buehler's Buy-Low supermarket( pretty much the Evansville tri-state area) You can get a digital weather radio for $29.99! At least if you can get to one. They have been flying off the shelves. A good Holiday gift for ANYONE!!!! I plan to buy one for my parents, and one for myself this week.

[simplykristi]

I will keep an eye on the weather here later today and tonight. It looks like we are in a moderate risk for severe thunderstorms.

Kristi

[wx247]

I will keep an eye on the weather here later today and tonight. It looks like we are in a moderate risk for severe thunderstorms.

Kristi

Yes Kristi. Severe weather potential looks pretty high. Tornadoes are not out of the realm of possibility. Shear parameters are impressive.

[simplykristi]

It should be an interesting late afternoon and evening around this part of the country. I hope that everyone is safe travelling to their destinations.

Kristi

[conestogo_flood]

I've never really heard of this happening... but what if there is, lets say, a massive hail storm while everyone is driving home from their Thanksgiving? The news said today is the busiest day for travelling in the USA, as everyone drives home. I'm assuming many people would be hurt? We don't get hailstorms here. Also, what if a tornado was headed for a crowded Interstate? Wouldn't that be a bad scenario if people can't get to an exit in time? Gee, I'd hold off my travelling plans today if I was in the thunderstorm risk area.

[simplykristi]

If you are caught on the interstate, you would have to get out of your car and lie flat on the ground. Do NOT seek shelter under a bridge EVER! If you are in an airport, you would head to a shelter. KCI has had to do that several times in recent years.

Kristi

[simplykristi]

As of noon, the barometric pressure here is 994.6 mb. I don't ever recall a pressure that low here.

Kristi

[wxmann_91]

Line of supercells have been crossing western AR, numerous tornadoes with damage reported.

More later.

[WindRunner]

Storm reports so far, AR should start having quite a few being reported shortly.

http://www.spc.ncep.noaa.gov/climo/
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[wxmann_91]

I am surprised there aren't more tornado reports, I have tracked a few dominant, cyclic, long-track supercells that originated in northeast Texas and southeast Oklahoma...that are now over northern Arkansas and southern Missouri...still having classic hooks (although the northern one, which produced the reported tornado in Yell County, has lined out somewhat).

[conestogo_flood]

There is 19 reports if you count them manually. The map still says 18.

[wxmann_91]

Unofficial info: the towns of Plummerville and Morrillton have been demolished, people trapped under their destroyed homes. 1 person dead in Morrillton when their car flipped.

[conestogo_flood]

What states are those located in?