New game to defeat SDS

[Ryan Wichman]

I would be in the Nebraska Panhandle area.

 

[Andrea Griffa]

Thanks, Andrea! I must ask... What is the time of the 850 analysis?

Sure, that's the 850 anlysis, 00Z

 

[Andrea Griffa]

And the winner is: Dean Baron!

The case was the June 12th 2005 outbreak in the Tx Panhandle!

I said this was an hard case just because if one saw the anlysis maps with fronts and lows he would expect a tornadic convection just near the intersection between the dry line and the outflow boundary (with south-east wind) near Amarillo, as you can see from John Mullen's analysis. Actually the tornadic supercells developed SE of Lubbock, well south.

Hope you guys enjoyed this case. Now, who's the next?

 

[Rob H]

Here's how the HPC drew the synoptic features for 00z that day, since their web archives don't go back that far:

edit: It isn't easy to draw conventional front lines in Google Maps, so orange lines are drylines, troughs, and outflow boundaries.

 

[Jeremy Perez]

Thank you for posting this Andrea.

An area where I saw room for improvement was in my need to position a warm front from the panhandles up toward northeast KS. Originally, I saw all the convection and resulting mess of lower temps in the area and dismissed it as a bunch of cold outflow distorting the temp gradient from south to north. So instead I got so caught up in looking for the outflow boundary. Now that I've actually printed the map and drawn isotherms on it, it's obvious that it wasn't just a pool of outflow, but all the convection was indeed firing along a warm front. It's a key feature, and it would have also helped me draw my eye to the low that I missed in northeastern NM.

 

[ahaberlie]

I completely ignored the dry line potential because I wasn't sure how these storms would move along that line.. I was pretty happy about calling the severe potential in and around Oklahoma though.. I wouldn't have much to show for it but a busted windshield it seems.

Do another one!

 

[Andrea Griffa]

I completely ignored the dry line potential because I wasn't sure how these storms would move along that line.. I was pretty happy about calling the severe potential in and around Oklahoma though.. I wouldn't have much to show for it but a busted windshield it seems.

Do another one!

Here we go with another case! This time I give you one more help with SPC outlook. The surface analysis map is at 20.07 Z.


-For you guys who didn't take part to previous case you will have to draw on the map every low-pressures, boundaries and fronts, and give a comment about the synoptic situation (position of cold front,warm,dryline fronts and whatever you want): don't be afraid of being wrong. Every one will have the possibility to draw his interpretation.

- Second, draw the zone where you rate probable the developing of tornadoes (I suggest circles or triangles): in addition the name of the cities where you think that a tornado could form is welcome.

 

[John Farley]

This is my best guess of the surface analysis. I didn't continue on the other map farther east, because I think the main daytime tornado risk is on the map above. On the eastward map I didn't do, I would put the warm front near the bottom, becoming more diffuse going east.

In terms of chase targets, I think the warm front and perhaps the part of the dryline closest to the triple point low would be the place to be. In general along the dryline, the surface winds are too veered, which is why I prefer the warm front. The peach and yellow circled areas reflect where I think there is potential for DAYTIME tornadoes, with the best potential in the inner, yellow circle. My target would probably be somewhere around Pine Bluff, AR - not particularly good chase country. I think there is also tornado potential farther north and east - hence the large MOD area from SPC - but I would think that with the features where they are and the time already nearly 21Z, the potential to the east and northeast would be at night and thus of little interest to chasers, especially in that terain.

If you wanted to play slightly better terrain but perhaps a lesser chance of tornadoes, southeast Kansas might be a good target.

 

[ahaberlie]

Depends on:
destabilization
moisture advection
-seems the area in front of the surface convergence is pretty cloudy.

Where?
Anywhere in the red polygon
--I would say the southern part of it may be better, with better destabilization
--If the surface convergence is enough to overcome the lower temps further north anywhere is fair game

 

[James Gustina]

The lime green area with the little TVS in it is my target area. I'd probably pick Maud for the closest city.

The dryline is still in Central Oklahoma/Texas with backed surface winds. The surface winds veer a little bit more going into Arkansas which is why my target is NE Texas/SE Oklahoma. Storms'll have a bit more breathing room along with easier access to good inflow right from the gulf between the dryline and warm front.

The only thing that worries me is really weak convergence anywhere east of the dryline or past DFW. Guess I'll have to wait and see how this turns out

 

[Brandon Copic]

I'm not to great at surface charts, but thought I'd take a shot at it, my guess would be in North and Central Arkansas/Secondary target area would be around Northeastern Texas. I favor North of the Warm front, but to the south of it is where the best backed winds are with the dryline and that is really what pushed it, but its a pure guessing game of where I would target, I guess it'd be pure stupidity to try, but I'd target Clinton, AR as my Closest City in that General Area

 

[Bart_Comstock]

One thing important to remember when looking at the surface obs in this area is that winds between KFSM (Fort Smith, AR) and KRUE (Russleville, AR) typically experiences odd easterly winds in the Arkansas River Valley (ARV) thanks to the topography.

This happens because the ARV, which is oriented from east to west, is lined by the tall Ouachita Mtns. to the south and the tall Boston Mtns. to the north. As the southerly return flow passes up and over the Ouachitas it will stay elevated above the ARV and pass over the top of the Bostons (which line the southern slope of the Ozark Plateau). Thanks to how narrow and deep the ARV is the air near the surface will largely remain unaffected by the southerly flow.

As low pressure closes in from the west it will begin to draw air in from the east through the bottom of the valley like a straw.

West (Ft. Smith) . . . . . . . . . . . . . . . . East (Russleville)
\_______Boston_Mtns_______/
L <--_<--_<--_<--_<--_<--__ H
/ . . . . . Ouachita Mtns . . . . \​

In my graphic above the black arrows represent the direction of the winds at the Surface. Note that at the surface of the ARV floor as it moves away from the high and towards the low. Just like the drain in a bath tub all of the air in the area of higher pressure (the ridge to the east of the trough and to the east of the valley) will flow into the area of low pressure that lays just to the west of the valley.

KEY:

• Black arrows = surface flow.
• H = High pressure
• L = Low pressure
• Red lines = Boarders of the Arkansas River Valley
• Red arrows = surface flow in the Arkansas River Valley

((NOTE: The location of the low and high as well as the winds drawn on the image above are NOT meant to be a copy of the day in question in the game and are meant as just an example.))

Just thought I would point this out for those forecasting for this event.

 

[Jeff Duda]

Traditional colors are included for the major boundaries. The orange dashed line represents the surface pressure trough (this doesn't look like a single solid closed low with circular pressure contours). The black dashed line is where I believe the warm front would be had it not been displaced by convection present in parts of E OK, AR, and S MO. Without having any other data, the yellow contour represents where I'd put the SLGT risk if I were an SPC forecaster. Normally I'd see the dryline and think, "BINGO!" However, the winds are veering ahead of it, so I question how good the low level shear is over that boundary. I'll probably play the warm front near Ft. Smith, AR and maybe just south of there.

 

[Bart_Comstock]

I would be far NE Oklahoma, possibly starting out in Miami and readjusting from there. instead of marching down towards Ft. Smith. Although there will be tornadoes SE Ok the best play is on the warm front. Another target would be to just stay home in Bentonville, AR.

The Ft. Smith play is a trick. The shift in the winds there is the result of the river valley effect that I mentioned in my last post. Although this can at times be beneficial to storms (think the Ft.Smith tornado of 97) it will prove to be a trap that will only entice chasers away from the better threat.

Because of the Boston Mountains and the ongoing storms in central Arkansas I wouldn't bet on that WF making it to far north in time.

McAlaster, OK would be an okay target but, just as you will with any SE OK or Western AR target, you will be fighting for peeks here and there between the trees and on top of the hills. As the event progresses I am betting that the winds will become more favorably backed here.

As the low presses along the winds closer to the triple point will back just enough and any storm that can form along the WF near the low and ride the front will go ballistic!

Anywhere south of the OK boarder along the dryline will not work out thanks to the veered winds.

So yes, Miami, OK is my target and I will have my eyes glued to the OK/KS boarder and will be ready to jump on the first storm that is able to go up and ride that front.

 

[Andrea Griffa]

Just a monition, guys, if it can be useful: watch out for the position of the dry line that actually doesn't cross the border between Tx and Ok and stay in Tx.