jojo762

Tulsa sure seems interested in the time period discussed above... "

Our area will remain in the jet stream flow at the base of broad
cyclonic flow over the western 2/3rds of the nation going into
next week. A pair of fast moving waves embedded in this flow will
bring thunderstorm potential to our area. The first wave will
affect the region mainly Sunday night. What is different this
morning compared to yesterday is the expected northward expansion
of the warm sector in the wake of the weekend cold. The latest
ECMWF suggests the warm front will lift north to around the Red
River, leaving our area in the favorable warm advection/elevated
storm region. Our area should be in the warm sector for the second
wave Tuesday. The best chances for storms will be with the front
late Tuesday/Tuesday night, though some potential exists during
the day ahead of the boundary. The setup will be favorable for all
modes of severe weather. The forecast could change, considering
this is still 6 days out. Stay tuned to the latest updates as we
get closer to the event."

57 minutes ago, bjc0303 said:

If the system can slow ~24 hours, maybe. The dynamics of the system look really impressive on both 06z deterministic GFS and 00z Euro. Large area of backed surface winds in the warm sector, along the dry line, etc. Transport of EML supporting steep lapse rates. Everything will be in place - except perhaps moisture.

 

Gonna be interesting to watch. Don't get strong dynamics like that in S plains too often per year.

Sure don't, at a glance it's a pretty incredible system for this time of year... If we get DPs around 60, somewhere, along with a slower system, things could really start popping with the current progged wind field. Something to watch, at least. 

The system late next week (thurs/Friday?) looks to be interesting if we can get some decent moisture return after the Sunday/Monday system...

That southern stream wave ejecting this upcoming Tuesday bears watching for the southern Plains and perhaps one last kick at the can for the chasers there. The last three runs of the Euro have shown a setup that looks conducive to tornadic supercells in KS and N OK with a moderate LLJ and a respectable, sub-1000 mb surface low along with 40-50 kt 500 mb flow (the latest run also increased the instability). I am really a fan of these kinds of lower amplitude waves that tend to not force major height rises to the east and create conditions favorable for VBV profiles.

The GFS is faster and less favorable, although it appears to be a progressive outlier among the full suite and even its ensemble mean to some degree.

SEVERE WEATHER STATEMENT

NATIONAL WEATHER SERVICE RAPID CITY SD

728 PM MDT FRI MAY 20 2016

SDC033-103-210145-

/O.CON.KUNR.SV.W.0008.000000T0000Z-160521T0145Z/

CUSTER SD-PENNINGTON SD-

728 PM MDT FRI MAY 20 2016

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 745 PM MDT

FOR NORTH CENTRAL CUSTER AND SOUTHWESTERN PENNINGTON COUNTIES...

AT 728 PM MDT...SEVERE THUNDERSTORMS WERE LOCATED ALONG A LINE

EXTENDING FROM CUSTER STATE PARK TO KEYSTONE...AND ARE NEARLY

STATIONARY.

 

THESE ARE VERY DANGEROUS STORMS.

HAZARD...BASEBALL SIZE HAIL AND MANY INCHES OF ACCUMULATED HAIL.

SOURCE...LAW ENFORCEMENT. SEVERAL INCHES OF HAIL HAS ACCUMULATED IN

         THE KEYSTONE AND IRON MOUNTAIN AREA.

The UNR LSR indicates that 8 inches of hail had accumulated. Holy cow.    

0416 PM HAIL 3 S KEYSTONE 43.85N 103.42W

05/20/2016 E1.75 INCH CUSTER SD LAW ENFORCEMENT

8 INCHES OF HAIL ACCUMULATED. MOTORISTS STRANDED ON

IRON MOUNTAIN ROAD. SNOW PLOWS HAVE BEEN CALLED OUT TO

CLEAR ROADS.

DDC AFD from this afternoon is pretty optimisitc about next week/this weekend, they appear to favor the ECMWF quite a bit... 

 

 

Saturday...12z ECMWF displays continuity forecasting the ridge
axis to pass SW KS Saturday morning, with lee side cyclogenesis
commencing in the afternoon. Forcing for ascent will still be well
west of SW KS, with a 556 dm upper low near San Francisco, with
jet support still in the Great Basin. Still, dryline evolution
should begin Saturday afternoon, and included isolated pops for
isolated supercells in the western zones as ECMWF suggests.

Sunday...Concern increasing for significant severe weather
potential. ECMWF swings an intense upper low/shortwave to Utah
by 7 pm, then into NW Colorado Sunday evening. Dryline will
strengthen further with strong cyclogenesis in NE Colorado.
Scattered supercells look plausible on this dryline Sunday
afternoon and evening. Large hail is likely, per climatology.
Convection expected to continue to some extent Sunday night, as
upper low intensifies to 550 dm near Cheyenne Monday morning.
Possibly a retreating dryline Sunday evening with very strong
forcing for ascent, and this scenario will be watched closely over
the coming days.

Monday...12z ECWMF intensifies upper low further to 544 dm in
Black Hills South Dakota, with an intense dryslot overspreading
western Kansas. Windy and much warmer, at least mid 80s. Severe
weather will likely threaten the eastern zones on the dryline
Monday afternoon.

It's convectively contaminated.

yeah. some cluster just northwest of it. lol

Tomorrow (5/17) already has an Enhanced Risk for Central Texas. Some crazy 3km EHI figures showing up on the NAM 4K at 00z.

22 0-3KM EHI... 22 STP.    One of the craziest soundings i've ever seen, even from the 4NAM. This obviously won't happen, but its hilarious to look at.

12z GFS is basically suggesting a potential outbreak over a large area of the central/S Plains on Monday. Thing that really gets my attention is how broad the LLJ axis is, with 40-50 kt H85 flow covering much of OK, KS and N TX ahead of the dryline. The low amplitude nature of the shortwave trough was another red flag. Looked at some soundings basically from I-20 north to I-70 and my eyes just about popped out of my head.

 

Euro isn't as enthused, showing a more disjointed trough ejection with weaker wind fields overall, but still plenty of CAPE. Finding it interesting that 5/9 produces majorly (anniversary of last year's CO, KS and Cisco tornadoes) and now 5/16 may try to do it as well (Elmer).

Perhaps the best thing about the 12Z GFS was that the LLVL wind field is pretty impressive as early as 18Z, and by 00Z it is even better... Not liking the look it has had for several runs including 12Z of keeping lingering convection across much of the warm sector. Oddly, it appears to have little to no effect on instability or moisture.

Still very little model consistency though in where the best threat area would be.

While there are still many things to work out, such as moisture quality, timing, etc, late this weekend/early next week continues to look interesting basing purely off of pattern recognition. Something positive is that both the GFS and Euro have started trending toward a less amplified trough (which would result in less meridonial flow) than what they showed a few days ago...That'll all come down to how far east exactly is the EC trough though.

In the past, they only did 30%, so it's not completely unprecedented.

I know that. I was talking about since they updated the Day 4-8. Like I said, I do not think I have seen a 30% since they made it to where there are two probability-categories in D4-8 (15%/30%).

So they did go with the 30% contour. I think since they updated the D4-8 to include two probability contours, this might be the first 30%?

Change that to Tuesday and Thursday-Sunday and I agree.

That low level inversion is not realistic (happens time and time again with the GFS), and it's likely cooling the boundary layer too fast.

Yeah. This 00Z run of the GFS is the best one yet as far as the parameterized environment goes--pretty insane across the board with everything, nuts to see widespread 6+ 0-1KM EHI's, and widespread 500+ 0-3K SRH. Still feel the trough is a bit too slow tho, and there is a pretty substantial amount of CIN. It's funny because last year, we could hardly get any events with an EML to hold things off, then this year on the first possible big event, we get a big time cap. But feel free to correct me if I'm wrong on those.

Isn't Mike Morgan the one who makes all sorts of extreme (and less than helpful) statements on live TV while covering tornadoes???

Seems like both major models are in pretty good agreement. Wouldn't be surprised for the SPC to go 30% tomorrow, especially if it is Broyles issuing the outlook. Unless something changes dramatically in the modeling.

Popping 6/24/03, 5/3/99 and 4/26/91 in SARS on the same sounding? Not bad.

How's the euro look compared to the GFS?

Mike Morgan from KFOR already giving a 6 of 10 on the tornado threat for Tuesday. Lol

There we go, SPC pulled the trigger for D7, Tuesday (4/26), mentioning "A SEVERE WEATHER EVENT WITH TORNADOES...LARGE HAIL AND WIND

DAMAGE WILL BE POSSIBLE."

FWIW, OUN already mentioning possibility of strong/severe thunderstorms in their "Next Seven Days" graphic for Sunday/Monday (4/24,4/25). DDC also mentioning possibility of severe wx in their AFD-- pretty rare for WFOs to mention severe that far out.

Things seem to be shaping up for a more favorable look later next week into the following one with multi-model/ensemble consensus of a western trough (and currently a rather progressive regime) setting up shop. Would have to think there would be one or more setups in the Plains if that ends up coming to pass, perhaps even on the more robust end assuming seasonable moisture return (which doesn't look to be out of the question). Not a huge fan of the Hudson Bay troughing that persists, but otherwise things are certainly looking more active for the tail-end of April.

Agreed... Not to be overly specific given that it is still a week away, but next weekend-- more so sunday than saturday-- has looked pretty  interesting for several days now on the GFS across the Central/Southern Plains.

Weeklies essentially show CONUS riding from the last week of April, right through the end of the run. Bright side, maybe it will be wrong again, but on the realistic side, I am becoming increasingly skeptical about any significant pattern change for the better in terms of severe potential.

Looks very boring for a while... Of course that could change in a jiffy. 

The environment next tuesday across the Eastern plains and Arklatex, into missouri, as depicted on the last few renditions of the GFS is pretty incredible. As far as thermodynamics go, MUCAPE values shoot up to 2000-3500+J/KG, however, there does not appear to be much turning with height, shear wise, but decent speed shear. Biggest question with this would be the strongly veered low level flow, and the fact that the CF does not appear to come through until late tuesday night, before then, there appears to be an ill defined warm front across TX/OK, as well as a somewhat better defined dryline. Lots to be figured out between now and then though, at least is something worth watching.