Central/Western Summer Medium/Long Range Discussions

[nwburbschaser]

I'm just hoping for a good supercell to photograph tomorrow. I'll take a closer look later, but it would be really cool to get something going in the Custer State Park area.

[Ian]

You need to only look at this storm report from a 0% tornado day, not even a see text to know that in this area of the country just instability and some storms can give you a brief spinup at least... this was pop corn high based shower type stuff... so if you can get precip in the high plains this time of year, you can get severe storms. http://www.spc.noaa.gov/climo/reports/140514_rpts.html Go find that needle in a haystack, which may literally be amongst some haystacks.

The high/central/northern plains is so much prettier than the southern plains too. I'd prefer to chase in this area all the time if possible. This setup is kinda iffy but it could do something good. SREF looks better than it has all along. Storm coverage is likely to be minimal though so could be tough.. esp if it's in SW SD since the road options kinda suck.  I'm gathering a list of parks to visit after the next few days just in case.

[ZackH]

Really reaching here but looks like east southeast NM could hold some potential next Saturday and Sunday per the GFS

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[Chinook]

My outlook for Tuesday. Apparently the SPC has highlighted the area near Cheyenne and Scottsbluff for tomorrow. (Monday)

 

 

 

 

[Thunder Road]

Really reaching here but looks like east southeast NM could hold some potential next Saturday and Sunday per the GFS

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Obviously depends on where the cutoff migrates to, but yes, it would seem so.

[Derek30]

Next weekend looks pretty good for the northern Plains. GFS showing good instability up and down the Plains

[Quincy]

Looking deeper into May, there could be some localized severe leading into the weekend as the Southwest trough slowly ejects. The next notable threat IMO is across the High Plains by early next week. While the Euro is a bit more vigorous with a trough digging into the Pacific Northwest, it's still there with the Euro ensemble mean to a lesser degree. Maybe a bit similar to what Ian and team have seen/will see yesterday and today.

At least we're looking at greater moisture return and with more northward extent than what's verified so far this spring. That's good for drought-stricken areas and at least bodes better should any severe threats arise. It's not completely unheard of to see events in June, but climo says they're moving north by then with the jet.

[nrgjeff]

Thursday and Friday should feature scattered or isolated thunderstorms in the central Plains but winds will not be strong aloft. Current NWP has a boundary in Kansas but things could change; and, it may or may not be the target. One could also argue upslope farther northwest on the High Plains. When all else fails, follow the triple point.

 

Weekend has conditional potential down in Panhandle Magic Land. AMA Forecast Discussion makes good points. Should be just drifters until some jet stream level winds can come out from the Desert Southwest teardrop upper low - perhaps this weekend. Days 4-8 are all subtle set-ups, but all days have conditional potential. Probably end up with 4-5 subtle but chasable set-ups in the next 7 days. I have to like the odds that one on chasecation scores.

[HM]

The new op ECMWF is definitely quicker with the cut-off ejection. It is certainly more in-tact than the GFS. I'm still waiting for the new EPS, but the op GFS clearly was lagging the consensus. Check out the spaghetti plots at 120h-168h:

http://mp1.met.psu.edu/~fxg1/ENSHGTAVGNH_12z/ensloopmref.html#picture

Clearly, the GFS is slower than the GEFS/ECMWF. It is quite possible we'll see it pick up the pace in the coming runs, especially if the the EPS trend quicker.

[HM]

The new op ECMWF is definitely quicker with the cut-off ejection. It is certainly more in-tact than the GFS. I'm still waiting for the new EPS, but the op GFS clearly was lagging the consensus. Check out the spaghetti plots at 120h-168h:

http://mp1.met.psu.edu/~fxg1/ENSHGTAVGNH_12z/ensloopmref.html#picture

Clearly, the GFS is slower than the GEFS/ECMWF. It is quite possible we'll see it pick up the pace in the coming runs, especially if the the EPS trend quicker.

The EPS mean on the 12z run was pretty much in agreement with the ECMWF. It's even arguable that the mean is faster with the ejection but the spread is too large for that to matter at this stage. So, the GFS appears to be a slow outlier today.

[Thunder Road]

someone at GLD is excited...

 

 

 

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GOODLAND KS
316 PM MDT MON MAY 19 2014
...
OF GREATEST CONCERN FOR THE LONG TERM FORECAST IS THE CHANCES FOR
SEVERE WEATHER ON WEDNESDAY. THE STALLED FRONT SHOULD BE LOCATED
ALONG TO JUST SOUTH OF HIGHWAY 96. HIGH DEWPOINTS...IN THE MID 50S
TO NEAR 60...ARE EXPECTED TO ADVECT IN WEDNESDAY MORNING FROM THE
EAST. IN ADDITION TO THE LINGERING FRONT...A CUT OFF LOW SETS UP
OVER THE FOUR CORNERS REGION AND REMAINS THERE THROUGH THE REST OF
THE FORECAST PERIOD. THE FIRST OF A SERIES OF SHORTWAVE TROUGHS WILL
ROTATE AROUND THE CUT OFF LOW AND SWING THROUGH WEDNESDAY AFTERNOON
AND EVENING. SBCAPE OF 2000-3000 J/KG AND 850-500 MB LAPSE RATES OF
7-8 C/KM INDICATE A HIGHLY UNSTABLE ATMOSPHERE. IN ADDITION TO THE
INSTABILITY...SHEAR SHOULD BE ON THE INCREASE WITH 40-55 KTS 0-6 KM
BULK SHEAR AND 0-3 KM HELICITY AROUND 200 M2/S2 IN THE AFTERNOON...
INCREASING TO 300-400 M2/S2 DURING THE EVENING AS A LOW LEVEL JET
DEVELOPS. FAVORABLE LOOPING HODOGRAPHS...LCL READINGS OF 1500-3000
FT...SHEAR AND INSTABILITY INDICATE THAT SEVERE WEATHER CHANCES ARE
QUITE HIGH FOR WEDNESDAY AFTERNOON AND EVENING. ALL MODES OF SEVERE
WEATHER WOULD BE POSSIBLE...INCLUDING THE A CHANCE OF TORNADOES AND
HAIL TO THE SIZE OF TENNIS BALLS OR LARGER. A STRONG TORNADO CAN NOT
BE RULED OUT COMPLETELY BUT A WEAKER WIND FIELD ALOFT THAN OBSERVED
WITH LARGER SEVERE WEATHER OUTBREAKS REDUCES THE CHANCE FOR A STRONG
TORNADOES. STORMS DEVELOP ALONG TO JUST NORTH OF THE FRONT BY MID
AFTERNOON AND SPREAD NORTH ACROSS THE REGION. HEAVY RAINS ARE
POSSIBLE WITH THE STORMS SINCE STORM MOVEMENT IS QUITE SLOW...AROUND
20 KTS. AS A RESULT...FLASH FLOODING IS POSSIBLE...ESPECIALLY IF
STORMS ARE ABLE TO TRAIN OVER THE SAME LOCATIONS.

[Thunder Road]

I mean, I agree at least that Wednesday looks better than today or tomorrow.  A strong tornado?  I'll believe it when I see it.

[thewxmann]

Upslope (SE WY/NE Panhandle/NE CO) looks pretty good on Wed.

[jojo762]

someone at GLD is excited...

don't disagree with their prognosis... Threat for tornadoes appears pretty good, but very localized given the small threat area. A strong tornado definition is anywhere from EF2-EF3 which almost indefinitely could not be ruled out IMO. Especially should a discrete supercell remain going into the evening, given the parameters discussed, the low-level rotation on a few storms could be quite strong given the amount of shear and strong 0-3km SRH, as well as a strengthen LLJ. In addition DP's near 60 are pretty high for NE Colorado and NW Kansas, not overly impressive though.

[jojo762]

Does anybody know what the quietest May on record is, tornado wise? This may, given the expected relatively quite late-May, has to be very close to if not on pace to beat it...

[MCS_hunter]

Does anybody know what the quietest May on record is, tornado wise? This may, given the expected relatively quite late-May, has to be very close to if not on pace to beat it...

NWS-Norman tweeted that Oklahoma only has 1 tornado for May this year.  In 2005, OK had no tornadoes in May at all.

[Thunder Road]

don't disagree with their prognosis... Threat for tornadoes appears pretty good, but very localized given the small threat area. A strong tornado definition is anywhere from EF2-EF3 which almost indefinitely could not be ruled out IMO. Especially should a discrete supercell remain going into the evening, given the parameters discussed, the low-level rotation on a few storms could be quite strong given the amount of shear and strong 0-3km SRH, as well as a strengthen LLJ. In addition DP's near 60 are pretty high for NE Colorado and NW Kansas, not overly impressive though.

 

Yeah I just thought mentioning strong tornadoes two days out seemed bullish.  2000 CAPE in Welc County will certainly produce something fun, but I'm not sold on EF2+ just yet.

[jojo762]

Yeah I just thought mentioning strong tornadoes two days out seemed bullish. 2000 CAPE in Welc County will certainly produce something fun, but I'm not sold on EF2+ just yet.

agree... It is pretty unusual for a WFO to be optimistic this far in advance, especially for an event like this, which is not going to be a major outbreak. Likewise, given the localized parameters, am not surprised at all by their choice of rhetoric... When this comes in range of the mesoscale models we'll get a better idea of the threat I suppose... Especially the HRRR imo, since it has seemed to nail everything in the plains this year (4/27, 5/11 both were pretty spot on)

[ZackH]

Looks like sitting and hanging out in west southwest TX starting Saturday until Tuesday or so may not be a bad idea. Of course if the Euro is right, the cutoff will meander further north. No slam dunk day but I kinda like Saturday and Monday/Tuesday.

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[andyhb]

Looks like sitting and hanging out in west southwest TX starting Saturday until Tuesday or so may not be a bad idea. Of course if the Euro is right, the cutoff will meander further north. No slam dunk day but I kinda like Saturday and Monday/Tuesday.

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The general idea the Euro is suggesting intrigues me, with several days of solid LLJ response as embedded s/w disturbances rotate around the parent ULL.

[HM]

A few interesting signals this year I wanted to throw your way:

 

1. The most widespread events, with a tendency to focus away from best chasing territory so far, tend to occur with a strong MJO/KW passage through the western hemisphere. At the same time, we are in a general relative maximum in angular momentum, but seeing a notable negative tendency on threat dates (makes sense with downstream, lee-cyclones in Mid Latitude Asia-America). These events include: 2/20-21, 3/27-3/28, 4/23-4/25, 4/26-4/28. If this pattern continues, the next potential may be around 5/20 +/- a few days for the next outbreak. The weaker the low-frequency wave, the weaker the response on our winds, jet stream etc.  

 

2. Plains-only events, that were somewhat tornadic, tend to occur during the weaker KW passages across western hemisphere as the MJO progresses through the niña-phases of the IO-Indonesia regions. This happened on 3/15, 4/2, 4/12-4/14, 4/20-21. Something like this is possible as soon as 5/16 or so, +/- a few days before the more low-frequency wave arrives a bit after. This will be the harmonic wave of the more impressive MJO wave that just passed through our longitude belt.  

 

3. The quiet periods have basically the opposite conditions mentioned above. So, presumably, this next week fits perfectly with that and it really has already started for the Plains. This is when the MJO-forcing is shifting back into the eastern hemisphere, GLAAM has fallen and the mountains relax.

 

After the last MJO wave in Feb, things were generally quiet until the next wave late March on 3/27, outside of 3/15 (which was non-tornadic). Things then were still very much in winter mode. I expect a more active post-MJO outbreak period, mostly because of climo. If this wave can remain robust through the nina phases, it will exhibit a 2013 like progression again. If it just falls to the nino-dominate stuff, there will be some chase days for sure but nothing significant. Pretty much, we'll repeat those events of early-mid April as the weakened pulse pulls through.  

 

I'll update again once we get into next week and we see how everything plays out. This is a very tough year to predict any kind of severe weather LR given the set of parameters in-place. What I can safely say at this point is that the method did work to BEAT the consensus/modeling. It indicated the potential for a trough to return into the western half of the CONUS before any model suggested so. In that regard, I'm already happy with the results.

 

A KW did cross into the western hemisphere 5/15-5/19 as the low-frequency "MJO" signal moved into Indonesia. http://www.atmos.albany.edu/student/ventrice/real_time/maps/waves/global/28.gif

 

The AAM was temporarily negative but has since gained a lot of +AAM from newly initiated +MT. The AO had been very positive but now is beginning to fall. We'll see if it all comes together...

[HM]

Looks like sitting and hanging out in west southwest TX starting Saturday until Tuesday or so may not be a bad idea. Of course if the Euro is right, the cutoff will meander further north. No slam dunk day but I kinda like Saturday and Monday/Tuesday.

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There's no slam dunk yet!

 

I have a feeling an area of great interest is going to develop out of this somewhere. Too many variables to see it yet, as you know.

[Srain]

There's no slam dunk yet!

 

I have a feeling an area of great interest is going to develop out of this somewhere. Too many variables to see it yet, as you know.

If I were a betting man, I would likely set up somewhere near AMA and move as needed. I see some great potential near the dry line from MAF to DDC and on E.

[1900hurricane]

If I were a betting man, I would likely set up somewhere near AMA and move as needed. I see some great potential near the dry line from MAF to DDC and on E.

 

I'm mulling over doing this very thing. It's still early, but I'm liking the prospects of at least seeing something on a three day chase weekend.

[Quincy]

I'm mulling over doing this very thing. It's still early, but I'm liking the prospects of at least seeing something on a three day chase weekend.

Give it a shot, especially if you have the time.

I'll be making my way west starting tomorrow. (Would have already left by now if this trip wasn't pre-planned) Pretty much have freedom from Saturday through Wednesday, so I'm cautiously optimistic.

Have no specific idea where I'll be by the weekend, but am very flexible. The trends have certainly been encouraging in the vicinity of the panhandles/southern Plains, but it will be a couple more days probably before confidence on the specifics gets high enough to narrow down a target.

At the very least, plan some alternate stops in case storms don't pan out.

[Thunder Road]

I should post some pics from the LP mothership we saw yesterday, and then start retracting my "high-based crap" statement...

[Thunder Road]

Anyway, I can't pick between Chugwater/Torrington, WY and playing the Palmer Divide, but I'm leaning toward the latter.

[Ian]

I should post some pics from the LP mothership we saw yesterday, and then start retracting my "high-based crap" statement...

These are the storms I always wanted to see as a kid. Tho time for some tubes...

[Thundersnow12]

Yeah that ULL will spit out little waves Sat-Tue if the GFS is right over the dryline. Subtle slight risk days in Texas. Love those. 

[Quincy]

Yeah that ULL will spit out little waves Sat-Tue if the GFS is right over the dryline. Subtle slight risk days in Texas. Love those. 

Liking the looks of the Euro for Sun/Mon. Some similarities there and focused in on Texas to Oklahoma. Instability blows up on Tuesday, but the best kinematic support is displaced well east of the greatest CAPE. Still plenty of time for the forecast to evolve though.

 

Edit to add analog commentary.

 

The CIPS analogs show some potential. One of the better recent analog matches for Sunday is 6/16/2006. Matches up reasonably well with the Euro/GFS forecasts. A decent severe day with a few tornadoes mixed in for good measure: