General Weather Discussion - November, 2015

[ljbab728]

I think a new month has started.

[SoonerDave]

Hmmm...GFS may be hinting at a stormy setup on Thursday? Pretty good difference in airmasses in advance of a fairly stout storm system presently off the west coast, might be dipping down and heading this way out of the desert SW, riding the jetstream. Interesting to watch as the week unfolds, especially given that we really haven't had our fairly typical secondary fall severe season...

[SoonerDave]

GFS still suggesting a possibly stormy setup for Thursday, but timing (as always) is the issue. Looks like a dryline could set up and trigger around of storms in or around the I-35 corridor during the day/early afternoon best I can tell.

Anon, that match up what you're seeing? I'm just posting this on the basis of my very crude review of one GFS animation....so if I'm wrong, someone needs to hit me with a shovel

[Bunty]

[SoonerDave]

Just posting a quick update here...btw, I make no pretense of being any Venture or Anon here, but figure I could post a general update

The latest GFS run I saw, which I think came up just an hour or so ago, really appears to back off some on the amount of storm formation over OK over the next 24 hours. It appears to focus the storms overnight and early morning into north central Texas, and then with later redevelopment in SE Oklahoma. This is, I think, in contrast to the last run that showed formation farther north into western OK overnight, then again in the afternoon near or east of the I-44 corridor. Right now, it looks like GFS is keeping activity generally out of central OK - western storms fading out by AM drive time, and the dryline pushing out such that later formation is farther east. As Venture often has said, will be interesting to see what the *next* GFS run has to say

Took a look at what purports to be a NAM run that, at a glance, seems to be agreeing at least generally with the GFS - some storms in W/SW OK, but heavier/stronger development later in the afternoon father to the E/SE.

Think the amount of moisture and the strength of the storm system out west and really strong jetstream sure lend itself to a forecast that includes the possibility of storms anywhere ahead of the region where the dryline pushes out. Pinpointing exactly where any given storm might form is obviously a fairly volatile thing to forecast.

EDIT: Just saw where Reed Timmer is apparently putting out (or did put out yesterday) a bit of hype with "high confidence" of "supercells and tornadoes," but the NWS convective forecast for tomorrow puts at 15% risk for severe thunderstorms in a region roughly south and east of a line following I-44 from Lawton to OKC and then east along I40. Their discussion suggests supercells are possible, but they have not yet issued any mesoscale discussions nor emphasized any especially significant severe risk for tomorrow. They tend to emphasize the north Texas region as the best bet for stronger weather, which seems to match up with what I think the GFS and the NAM each showed.

[Anonymous.]

^ spot on.

SE OK could get in on some legit severe weather (damaging winds is my guess).

The rest of the state can expect showers and storms of a non-severe variety, especially in the morning Thursday.

[SoonerDave]

^ spot on.

SE OK could get in on some legit severe weather (damaging winds is my guess).

The rest of the state can expect showers and storms of a non-severe variety, especially in the morning Thursday.

Thanks, Anon

[SoonerDave]

GFS seems to be backing off even more on the intensity of activity around OK for Thursday, but continues to persist a general rain pattern around the bulk of the state tomorrow. It appears to limit stronger storms to the extreme SE corner of the state and into N. Texas from around Dallas NE into SE OK and SW Arkansas. NAM seems to push off the stormier weather even farther NE.

Those models, combined with the latest soundings showing a distinct lack of instability, all tend to diminish the notion of any broad severe weather for tomorrow. Looks like a general rain/t-storm pattern, in a couple of waves, with the stronger development potential restricted to the far SE corner of the state.

I'll be curious to see if SPC alters/reduces their slight/marginal risk areas if GFS continues its trend on the next run, particularly given that NAM seems to generally concur.

[SoonerDave]

SPC has fallen in line with the latest GFS and NAM runs, and has reduced the slight risk area to the extreme south-central part of the state along the TX border just east of I35. Most of Oklahoma is in only a marginal risk now, while the slight risk area pushes off into the DFW area. Rain and a few possibly noisy storms w/gusty winds and small hail possible in the state in advance of the dryline later in the day, but severe potential is very low. Dryline pushes thru central OK midday, so once it passes the rain /storm chances go with it.

[Anonymous.]

Storms coming up now just west of C OK.





Like SPC, should just see garden variety rain and storms, maybe a severe storm or two at one point depending on evolution.

[Bobby821]

OKC is back in the Slight Risk Area and also under 2% for a Tornado and 15% for Wind

[Bobby821]

OKC is back in the Slight Risk Area and also under 2% for a Tornado and 15% for Wind

Attachment 11753Attachment 11754Attachment 11755

[SoonerDave]

Hey Anon,

In looking at this last update from SPC, am I reading their summary correctly to say that a "wedge" of surface-based warm air has created just enough instability in advance of the front to increase the chances for slightly stronger storm development in SE/C OK up toward KS? There's quite a bit of analytical/technical terminology in there I just don't know, so I thought I'd bounce my best understanding off someone who does

[Anonymous.]

Yea basically the plan was for some of the dry air to mix out some of the moisture over C OK and primarily leave the heavy dewpoints in SE OK.

However, that never happened and most of the state right now is 65F DP or higher, some 70Fs down south. So any initiation to the west of this air mass has some solid fuel. I still think severe storms will be isolated, but the possibility is present.

[SoonerDave]

Yea basically the plan was for some of the dry air to mix out some of the moisture over C OK and primarily leave the heavy dewpoints in SE OK.

However, that never happened and most of the state right now is 65F DP or higher, some 70Fs down south. So any initiation to the west of this air mass has some solid fuel. I still think severe storms will be isolated, but the possibility is present.

Great explanation, Anon. Thanks.

So, this was an as-it-developed observation/outcome, hence the models never had any reason to consider it, correct? Is there an overarching reason why that dry-air "mixout" didn't happen as expected, or is it more of a "hey, that's just how nature played out this time" scenario?

[Anonymous.]

I think it was just the timing of the coveted double dryline we sometimes see. Usually it is more extreme, but this scenario the eastern dryline hardly moved east, and is almost indistinguishable from main line out in W OK.

Storms starting to ramp up now, heading into OKC near Tuttle, officially a severe storm at this time. Looks like some good action down near Wichita Falls.

[SoonerDave]

Looks like the potential near and east of OKC is ramping up somewhat per the ingredients Anon discussed above. SPC has issued a mesoscale discussion for the region covering the midday hours and likelihood of at least a severe t-storm watch later in the day.

Storm Prediction Center Mesoscale Discussion 1926

[Anonymous.]

TOR Watch issued for basically eastern half of OK.




Storms in SC OK are worth watching.

[turnpup]

Anyone know if we're going to get another wave besides this one sometime later today?

[Bunty]

Post deleted due to similar already posted.

[Anonymous.]

Nope, this is it in terms of significant precip.

[Anonymous.]

Sun is out just west of this development line.

[turnpup]

Thanks!

[FighttheGoodFight]

Holy crap. I went home at lunch here in Norman and ran into this mess. The rain and wind were very strong. Couldn't see about 5 feet in front of me. It passed over I35 so I bet traffic was at a stand still there.

I just pulled over into a gas station and waited it out for 10 minutes

[tfvc.org]

What happened to the cool info and graphics usually found in the top post?