Central/Western Medium-Long Range Discussion

[thewxmann]

Accuweather seems to like Spring 1983, 1987, 1998, 2007 for analog years based on this:

 

http://www.accuweather.com/en/weather-video/video-traditional-and-hybrid-el-nino-patterns-used-through-spring/97649985001

 

2007 x2

1987 x2

1983 x2

1998 x1

 

Hmm 1987 vs. 2007/1998. Lots of range there for the chase season.

[brettjrob]

Hmm 1987 vs. 2007/1998. Lots of range there for the chase season.

 

Between the analogs and medium-long range guidance, it looks like potentially another season with southern stream disturbances undercutting broad ridging at higher latitudes (not exactly newsworthy coming out of a strong Nino). That happened a lot last year, too. 1987 and 2007 don't look all that different from each other in terms of mean springtime height anomalies, illustrating how relatively unpredictable details can make such a difference in the severe weather season.

[andyhb]

If I were a chaser/living in OK/KS/N TX, I'd be keeping an eye on next Monday with the Euro's idea of a strong lee cyclone developing in response to that negatively tilted shortwave trough ejection. Healthy EML overspreads the dryline leading to a pretty wide axis of moderate destabilization along with great directional shear in the lowest 3 km (12z run via 180 hrs).

[Chinook]

Looks like severe season for central Oklahoma just started with a severe thunderstorm watch issued tonight, and a recent wind gust to 58mph.

[raindancewx]

My research suggests that it is very rare for snowy Decembers in the SW to continue into snowy Januaries - we may get a bunch of little storms, but I think we're kind of due for a quiet period around maybe Jan 20 - Feb 20 before the action resumes with impressively strong/cold storms plowing way south in the West again until maybe May 20. My idea for this winter has always been cold/wet in the NW in the fall, that cold/wet area moves south and east in Dec and early January. The east bakes until late January, then they have one month of winter. After the east has it's one month of winter we get two-three months of cold (often snowy, but not always) spring storms. Could still be completely wrong, but we'll have to see.

 

Main differences from last year are the warmer AMO and cooler PDO, and the El Nino will likely be weakening, not strengthening in the Spring.

 

This still looks on track, assuming the March pattern comes in as advertised after March 7th.

[Superstorm93]

Maybe some more action next week. 

 

 

[andyhb]

Euro + EPS + Euro parallel (and the UK now that it has gotten in range) have been consistently hitting this potential for several days now. A lead shortwave trough ejection and strong lee cyclogenesis looks to occur March 7th (Monday) leading to a strong southerly LLJ of 40-50+ kts encouraging BL dewpoints to rise into the lower 60s across OK and KS ahead of a very sharp dryline. While this moisture may seem rather meager, keep in mind we're also looking at EML-assisted mid level lapse rates of 7.5-8+ C/km with this event, so that should be enough for moderate destabilization assuming some decent insolation (may need to watch for moisture mixing if it turns out to not be overly deep). This will also lead to a rapidly moistening BL further south for the next day.

 

On day 2, the primary upper impulse looks to eject towards the Rio Grande Valley as the low level jet strengthens in excess of 55 kts across E TX, the Arklatex and LA. While the flow does appear to be a bit meridional, there is certainly enough of an upper level jet component ejecting ahead of the trough to encourage storm development out ahead within a potentially very unstable warm sector (strong low level shear as well with backed SSE/SE surface winds underneath the aforementioned LLJ). If this setup turned out to be just a bit less amplified and/or meridional, we'd be talking some serious potential given the amount of instability that looks like it could be present (still think there is quite a bit of potential how it sits now). We'll see what happens as it is still a week out.

 

Definitely looks like the first more significant threat may be on the way with more possible afterwards given GWO progression through at least phases 8-1 and a shift towards a +EPO (Gulf of Alaska trough) through the first two weeks of March. CFSv2 chiclet chart has been lighting up March for the better part of a month now, so this definitely seems to have some legs. Quite a contrast to the past 3 Marches.

[Chinook]

It seems like Monday and Tuesday may be slight risk days. Currently the SPC is discussing these days but there are no 15% highlighted areas on the extended outlook maps. The GFS shows medium instability, 1000-2000 J/kg, through parts of the southern Plains, Monday afternoon. As for dynamics, there is a weaker shortwave near Goodland KS, and a strong 500mb jet moving in through northern Mexico into Texas on Tuesday.

[brettjrob]

Definitely looks like the first more significant threat may be on the way with more possible afterwards given GWO progression through at least phases 8-1 and a shift towards a +EPO (Gulf of Alaska trough) through the first two weeks of March. CFSv2 chiclet chart has been lighting up March for the better part of a month now, so this definitely seems to have some legs. Quite a contrast to the past 3 Marches.

 

That's for damn sure. Was just commenting on this earlier. After 2013-2015, anything besides full-fledged winter east of the Rockies feels like a godsend. I'm not even worried about whether this upcoming system is a big severe weather producer - just moisture, rain, warmth, and a continued favorable pattern will suffice.

 

Sunday or Monday may at least offer the customary first surface-based supercells on the Plains to kick the season off, as things stand.

[jdrenken]

More and more indications are that this month is going to be wild. #organicforecasting and #bsr has been on point to the threat!

[raindancewx]

There are bowling ball lows...and then are bowling ball lows. Crazy -

[mayjawintastawm]

That one would be a gutter ball. I don't think I've seen one at quite that low a latitude. Need some bumpers on the lanes.

Why does it look to me like the ridge wants to build right back on top of it?

[Superstorm93]

Looks like we're going to be busy again soon..

 

 

 

..DISCUSSION...
MODELS HAVE TRENDED TOWARD REASONABLE AGREEMENT REGARDING EVOLUTION
OF SYNOPTIC PATTERN DAYS 4-6...BEYOND WHICH PREDICTABILITY IS LOW.
THE THREAT FOR SEVERE STORMS IS EXPECTED TO INCREASE OVER THE CNTRL
THROUGH SRN PLAINS DAY 5 AND THE SRN PLAINS AND LOWER MS VALLEY DAY
6. MODELS HAVE BEEN PERSISTENT INDICATING THAT INITIAL PROGRESSIVE
LOW-AMPLITUDE REGIME ON DAY 4 WILL TRANSITION TO A HIGH-AMPLITUDE
PATTERN AS A SYNOPTIC TROUGH AMPLIFIES OVER THE SWRN U.S. AND NRN
MEXICO DAYS 5-6.

SUNDAY /DAY 4/ MODIFIED CP AIR WILL RETURN NWD EAST OF LEE TROUGH
WITH DRYLINE BECOMING ESTABLISHED OVER THE CNTRL-SRN HIGH PLAINS. A
FEW THUNDERSTORMS MAY OCCUR IN ASSOCIATION WITH WEAK LOW-AMPLITUDE
SHORTWAVE TROUGH ACROSS THE CNTRL AND SRN PLAINS...BUT THE DRYLINE
IS EXPECTED TO REMAIN CAPPED.

MONDAY /DAY 5/ MODIFIED CP AIR WILL CONTINUE TO ADVECT NWD ALONG A
STRENGTHENING LLJ...BUT WILL REMAIN LESS THAN OPTIMAL OVER MUCH OF
PLAINS. DESPITE SOMEWHAT LIMITED MOISTURE RETURN...COLD AIR ALOFT
AND EWD ADVECTION OF EML PLUME WILL RESULT IN CORRIDOR OF MODERATE
INSTABILITY. THERE WILL LIKELY BE SOME LOW CLOUDS AND A FEW AREAS OF
PRECIPITATION ALONG MOIST AXIS...BUT CLOUDS SHOULD MIX OUT FROM THE
WEST AHEAD OF THE DRYLINE RESULTING IN A NARROW ZONE OF SFC HEATING.
A SIGNIFICANT SHORTWAVE TROUGH IS FORECAST TO EJECT NEWD THROUGH THE
CNTRL PLAINS MONDAY AND WILL INCREASE POTENTIAL FOR THUNDERSTORM
INITIATION ALONG SHARPENING DRYLINE. THUNDERSTORM COVERAGE SHOULD
REMAIN ISOLATED...BUT VERTICAL SHEAR WILL SUPPORT SUPERCELLS WITH
ANY STORMS THAT INITIATE.

OTHER SEVERE STORMS MAY DEVELOP ACROSS SWRN TX MONDAY NIGHT IN
ASSOCIATION WITH AN EJECTING SRN-STREAM SHORTWAVE TROUGH.

TUESDAY /DAY 6/ QUALITY OF MOISTURE WILL INCREASE IN WARM SECTOR
FROM ERN TX/OK INTO THE LOWER-MID MS VALLEY SOUTH OF A SW-NE
ORIENTED BAROCLINIC ZONE...AND SOME SEVERE STORMS WILL LIKELY
DEVELOP AS FORCING ASSOCIATED WITH SRN STREAM SHORTWAVE TROUGH
OVERTAKES WARM SECTOR. FLOW WILL BECOME INCREASINGLY
MERIDIONAL...AND STORMS SHOULD EVENTUALLY EVOLVE INTO AN MCS AS THEY
DEVELOP THROUGH ERN TX AND THE MS VALLEY REGION.

..DIAL.. 03/03/2016

 

[Quincy]

Things are really looking up for the rest of March. The best analogs I can find (from the past 20 years) are 2006 and 2009. I'm not so sure that we see a higher-end event (like 2006), but I would expect the Plains and Middle Mississippi Valley (possibly Ohio Valley) to remain more active than usual for this early in the season. This fits the expected pattern and the outcome of mid-late March in those years.

 

The Euro weeklies show western troughing/Southeast ridging more or less continuing through March. The GEFS out to day 16 has had a similar signal too.

 

While it may not play a critical role, the lack of a drought in the southern Plains/lower Mississippi Valley doesn't hurt things either. A ton of moisture is likely from eastern OK/TX into the Mississippi Valley through next week. 

 

Trends continue to suggest better than seasonable moisture return, so if our storm track stays north, severe threats will pop up from time to time.

 

Another interesting note is that the strong El Niño analogs don't necessarily work too well in comparison to the longer-range ensemble forecasts...

[jdrenken]

Food for thought...this forecast was made on February 15th for next week's precipitable water amounts via the #rrwt, or Recurring Rossby Wave Train, found here..

[raindancewx]

I'm going to put this here - we can see how well it verifies.

 

[nwburbschaser]

The GFS and Euro both have a decent look in the day 9-10 range. This one has my attention and it should be something to keep an eye on as we get closer.

Quincy mentioned good moisture return a few days ago and it looks like that will still be true for any potential system during the upcoming time period. We'll see how this evolves after the cut off moves through this week.

[andyhb]

Not sure I've ever seen a signal this strong from the CFSv2 SCP chart for 3 days in a row...especially this early in the season.

 

 

Pulled a sounding off the 12z Euro at SGF at 180s and it was pretty incredible. Very steep mid level lapse rates (SBCAPE near 2000 J/kg) with SRH in excess of 650 m²/s² and just a huge sickle shaped hodograph. Hopefully we get some more agreement among guidance for this period in the coming days, because it looks like it could shape up to be a more significant event assuming even rather marginal moisture return (given the impressive thermodynamics aloft).

[jojo762]

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.

[the ghost of leroy]

Not sure I've ever seen a signal this strong from the CFSv2 SCP chart for 3 days in a row...especially this early in the season.

 

 

Pulled a sounding off the 12z Euro at SGF at 180s and it was pretty incredible. Very steep mid level lapse rates (SBCAPE near 2000 J/kg) with SRH in excess of 650 m²/s² and just a huge sickle shaped hodograph. Hopefully we get some more agreement among guidance for this period in the coming days, because it looks like it could shape up to be a more significant event assuming even rather marginal moisture return (given the impressive thermodynamics aloft).

 

Can I have a link to wherever you generated that plot?

[jdrenken]

Can I have a link to wherever you generated that plot?

 

Look here

[jdrenken]

When Organic Forecasting Sees The Future Months In Advance

[Chinook]

The extended range forecast out to 2 weeks in the future looks quite cool for the Midwest. The Day-3 (Easter Sunday) forecast as well as Wed March 30 look like possible severe weather setups. Otherwise the severe weather may be very close to the Gulf of Mexico or there may be none at all for 3-4 days in a row.

[jdrenken]

SOI Drop and More Organic Forecasting Support

[nrgjeff]

In addition to climo improving for severe after April 15, a couple other reasons to be optimistic are noted. Pacific upstream situation should favor a transition to warmer zonal flow in the US, at first. Some of the weekly models hint a West trough later in April. Need to avoid the tear drop trash and get some real open troughs. Time will tell.

[Paulie21]

ERTAF continues to predict "Above Average" tornado activity for the period of 4/17 to 4/23 despite the progged barotropic nature of the upper levels. AAM begins going negative and in the favorable zone for western troughing. Chiclets look pretty variable during this time becoming more active going into May...FWIW of course, since the CFS becomes worse than climo beyond 18 days..

[Quincy]

ERTAF continues to predict "Above Average" tornado activity for the period of 4/17 to 4/23 despite the progged barotropic nature of the upper levels. AAM begins going negative and in the favorable zone for western troughing. Chiclets look pretty variable during this time becoming more active going into May...FWIW of course, since the CFS becomes worse than climo beyond 18 days..

CFS has showed an overall dearth of potential for the same time-frame over the past few runs. This seems to line up with most medium-range guidance.

 

Although the pattern isn't 0% supportive of severe, it's looking fairly likely that tornado activity will remain below average for the next 1-2 weeks. The weeklies will be out in a few hours, but the EPS/GEFS show little optimism through day 15. 

[andyhb]

*sigh*

[Quincy]

*sigh*

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.

[jojo762]

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.