Central/Western Summer Medium/Long Range Discussions

[andyhb]

I don't really agree with this. Dew points late afternoon yesterday over W OK ahead of the dryline looked to be 52-56 F, on average. The NAM and GFS had advertised mid-upper 60s from 36 hours out, perhaps declining to 60-63 F by Saturday evening's runs. Even the ECMWF was 5-7 F too moist in the short range.

 

Looking farther E and NE, the situation wasn't much better. All models were in agreement on solid mid-upper 60s dew points throughout the E half of KS through the afternoon, but they mixed out to the upper 50s to low 60s.

 

It still wouldn't have mattered with 20-30 degree T/Td spreads (upper 80s/low 90s temps) whether they were 5-7 degrees higher or not.

 

At that time anyway (mid afternoon), the low level shear down there wasn't much to write home about either.

[brettjrob]

It still wouldn't have mattered with 20-30 degree T/Td spreads (upper 80s/low 90s temps) whether they were 5-7 degrees higher or not.

 

I agree, for the most part, but I'm mainly talking about the implications for future setups -- at least, unless/until evapotranspiration improves.

[Chicago Storm]

It still wouldn't have mattered with 20-30 degree T/Td spreads (upper 80s/low 90s temps) whether they were 5-7 degrees higher or not.

That's not the point.

[andyhb]

That's not the point.

 

I probably should've mentioned that I was looking at progs for 00z, not mid afternoon.

[Ian]

I'll lock in the 0z GFS and roll the dice lol.

[andyhb]

I'll lock in the 0z GFS and roll the dice lol.

 

Well for now there's some much needed rain (and heavy at that) coming to the moisture source/trajectory regions across S TX.

[andyhb]

What's happening towards the end of the 00z Euro run is pretty impressive looking, especially for this time of year. As HM mentioned on the previous page, it almost appears that the N Pac pattern is taking on a winter/cold season look. The pattern in the west is relatively low amplitude and that's really what you look for when trying to sort out the potential for a multi day event. You can see a series of strong shortwaves rotating through the flow in the Gulf of Alaska.

 

The question about the precedent pattern remains, but it looks like things are going to become a bit more volatile as we pass into the second half of the month.

[HM]

The new 12z ECMWF took a big step toward 1986's evolution with how it handles the PNA-EPO sector. All of the older runs and the latest opGFS, cut the Alaskan pipeline underneath the N PAC block, building a "ridge-bridge" across North America. This traps the low across the Southwest. The ECMWF scenario would promise a more robust phasing/entry into Plains toward 25th.

[Ian]

Mixed feelings on the current look. On one hand days and days of SW flow isn't a bad thing. On the other the trough gets a bit buried for a while. Not sure the moisture and shear will be able to overcome capping on some days at least.  One plus is it's an ideal flow at least initially for upslope if there is enough moisture.  Will be interesting. 

[Quincy]

Another analog showing up (at least centered on day 8 via CPC) is May 5, 2007. The 12z reanalysis from 5/5/2007 has some similarities to the 192hr Euro forecast from 12z today. That early May 2007 outbreak was fairly significant.

 

So, most data points toward at least the possibility of a low-end severe threat early next week, perhaps on Monday. Beyond that, there is a fair model consensus that a second and perhaps more significant severe threat may unfold by late next week or next weekend. (as HM eluded to with the 1986 comparison)

 

Regardless of the exact evolution, I think most can agree that this is encouraging:

[Ian]

2007 is #5 tornado day (calendar day wise at least) since 1950. I'd take it. Could skip the events on the 4th or keep it over fields. 

[HM]

The situation is just as complicated, tropical forcing-wise, with the models this week as they were last week. The true low-frequency signal has entered the IO while the next CCKW is already in the western Pac. As anticipated, this was supposed to come by mid-May through Dateline and ultimately be the impetus for this threat window. When the tropical forcing develops this sort of wave 2 pattern in the higher frequency spectrum, the RMMs usually go incoherent. While the models are showing the effects of the CCKW in the Mid Latitudes nicely and predicting its passage through the western hemisphere at appropriate time, they are losing the MJO-low frequency signal. How this may alter the future model runs is anyone's guess.

[Derek30]

Might be some Dakotas action next week at some point

[andyhb]

Latest mid range progs aren't looking so great for the trough next week.

[Ian]

It's complex for a better look than a ridge. I dunno if it's necessarily gotten any better or worse today. The idea of some bigger event is certainly more muddled with the majority burying the trough and degrading it rather than 'potentially' ejecting it nicely at the end or after the end of the run.  Still days of SW flow.. plenty of concerns in that but hard to see how you get shut out for the whole stretch and hard to turn away from a trough in that area for higher potential at this range.

[Ian]

I'm still interested in Sunday but maybe I'm just out of it. SPC didn't even mention Monday in the morning d4-8 tho Sunday is certainly marginal and would be easy to not happen.  As is, most models still get things pretty workable by 0z and have stuff pop either in SD or NE. One of those days has to do something in the high plains heh.

[Thunder Road]

I'm more interested in gambling farther south - maybe (as a rough guess) somewhere along I-70 in KS?  Unless it's really good, High Plains/upslope doesn't do it for me.  It's usually high-based and splitty.  I'd rather chance it at seeing better structure farther south (daylight tornado threat is pretty low will how high bases will be initially but there's plenty of low/mid-level turning for structure) than mess around with general thunderstorm activity up there.  But that's just me.

 

And having said that, we'll cap bust Monday and you'll score up in SD, haha.

[Thunder Road]

TOP:

 

 

Deeper moisture along a warm front setup near
the Kansas and Nebraska border will keep chances for thunderstorms
in Monday and again on Tuesday evening. Models differ on precip
coverage at this time, however a slow, deepening trough off the
southwest conus will spell for a more unsettled pattern through at
least mid week.

 

DDC:

 

 

Surface based
instability will increase slowly by Sunday and into early to mid
next week as low level moisture and surface temperatures gradually
increase. But due to the aforementioned frontal incursion through
the Gulf of Mexico, the moistening will be slow. Given the warm
mid level temperatures developing by early to mid next week, any
thunderstorms would likely be isolated. There is some disagreement
in the models as to the progressiveness of the western United
Stated upper level trough, with the ECMWF being more closed off
and the GEM/GFS being more progressive. Thunderstorm chances may
improve by mid to late next week depending on the evolution of the
upper level system and presence/location of any surface
boundaries/fronts.

 

No TS/SHRA mention from ICT after Sunday

 

GID:

 

 

HAZARDS: TSTMS WILL BECOME POSSIBLE SUN AND LASTING INTO AT LEAST

WED. THE POTENTIAL FOR SEVERE TSTMS WILL EXIST...BUT NARROWING IT
DOWN TO A PARTICULAR DAY IS NOT POSSIBLE THIS FAR OUT IN THIS
UPCOMING SITUATION.

...

RAIN CHANCES SUN AND BEYOND WILL BE DRIVEN BY SUBTLE SHORTWAVE TROFS
THAT ARE NEARLY IMPOSSIBLE TO LOCATE AND TIME THIS FAR OUT.
DEWPOINTS IN THE 50S TO NEAR 60 WILL ADVECT INTO THE FCST AREA SUN-
MON...UNDERNEATH AN EML THAT WILL ALSO OVERTAKE THE AREA. THIS
COMBINED WITH MORE RIDGING ALOFT THAN PREVIOUSLY EXPECTED WILL KEEP
THE ATMOSPHERE MOSTLY CAPPED. NOW THE FRONTS NEARBY COULD AID IN
MESOSCALE LIFT. ONCE THE FRONT BECOMES STATIONARY OVER KS...THE LOW-
LEVEL JET /LLJ/ IMPINGING UPON THE FRONT COULD RESULT IN ELEVATED
TSTM CLUSTERS. IT IS JUST TOO EARLY TO DETERMINE WHEN AND WHERE.

 

LBF:

 

 

SATURDAY NIGHT THROUGH WEDNESDAY...EARLIER MODEL INDICATIONS OF A
STRONG CAP DEVELOPING AT OR AROUND 700MB APPEAR MUCH LESS CERTAIN
WITH THE MORNING MODEL RUNS. IT WOULD APPEAR A MUCH DEEPER LEAD
H700MB LOW MOVING THROUGH THE NRN PLAINS SUNDAY THROUGH TUESDAY
WOULD LOWER HEIGHTS AT THAT LEVEL AND KEEP THE CAP WEAK. THIS IS
REFLECTED IN THE QPF FIELDS OF THE GFS AND ECM. THE GEM SHOWS THIS
DISTURBANCE MORE COMPACT AND NOT AFFECTING H700MB TEMPERATURES.
PARTS OF SRN NEB COULD REMAIN CAPPED AT 9C-12C WHILE THE NORTH IS
NOT AT 6C-9C. ADDITIONALLY...LOW PRESSURE SETTING UP ACROSS THE CNTL
HIGH PLAINS OF ERN COLO/WRN KS MONDAY AND BEYOND WOULD DIRECT WARM
AIR NORTH TOWARD A STATIONARY FRONT WHICH COULD EASILY SET UP ACROSS
SRN NEB AS SHOWN BY EASTERLY H850MB WINDS IN THE MODELS.

THE FORECAST IS FOR ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS
EACH DAY. THE SEVERE WEATHER PARAMETERS INDICATE A FAVORABLE BALANCE
OF CAPE AND SHEAR TO SUPPORT SEVERE STORM DEVELOPMENT SUNDAY THROUGH
TUESDAY AND PERHAPS WEDNESDAY DEPENDING ON THE LOCATION OF A
STATIONARY FRONT THE MODELS DEVELOP.

 

CYS:

 

 

SUNDAY-MONDAY:
THE UPPER LEVEL RIDGE IS EXPECTED TO CONTINUE BUILDING OVER THE
REGION AS THE UPPER LEVEL TROF IN THE PACIFIC NORTHWEST DIGS
SOUTH. THIS WILL ALLOW FOR MORE SUBSIDENCE TO BUILD OVER THE AREA
SUNDAY INTO MONDAY WHICH WILL ALLOW FOR A NICE WARMUP. GEFS IS
SHOWING 700MB STANDARDIZED ANOMALIES CLIMBING TO 1.5 TO 2
STANDARD DEVIATIONS ABOVE NORMAL IN THE SOUTHERN NEBRASKA
PANHANDLE. WE HAVE BUMPED UP HIGHS A BIT TO REFLECT THIS.

TUESDAY-WEDNESDAY:
THE MODELS ARE STARTING TO INDICATE THE UPPER LEVEL TROF BUILDING
INTO THE ROCKIES WHICH WILL CERTAINLY BE WORTH WATCHING. IF THIS
TROF CAN BUILD INTO THE AREA...WE MAY SEE BETTER CHANCES OF
PRECIPITATION MOVING INTO THE PICTURE NEXT WEEK ALONG WITH COOLER
TEMPERATURES.

 

 

UNR:

 

 

AN UPPER TROUGH/CUT OFF LOW IS PROGGED TO DEVELOP EARLY
NEXT WEEK OVER THE FAR WRN CONUS. UPPER FLOW WOULD THEN BECOME MORE
SWRLY WITH WARM AND MOIST AIR ADVECTING IN FROM THE S/SE. THIS WILL
BRING INCREASING CHANCES FOR THUNDERSTORMS FOR THE FIRST HALF OF
NEXT WEEK ALONG WITH NEAR TO SLIGHTLY ABOVE AVERAGE TEMPERATURES.

[Thunder Road]

What's wrong with it?

 

Is this not a splitting supercell (if not just plain linear mode) hodo (NE WY, 0z Tue)?  

 

Is this not a high-base sounding? Is there not veering from the sfc to roughly 550 mb?  (same time, Salina, KS)  Flow at 500 and above is annoying weak, but still...

 

 

I mean sure you can get something nice out of a right-splitter - sometimes - but not always.  Even when it is, it's usually short-lived.

 

Sure, you can get Goshen (which was a few days before our '09 trip started), and I was out there for 6/7/12, but this is no 6/7/12.

 

Rather than carrying your superiority complex from the other subforum over here, care to actually address where I'm wrong?

[andyhb]

There's so much that's incorrect in this post it's not even funny.

 

For someone who basically said the third week of May last year would amount to nothing, then proceeded to exude this same dickish attitude towards anyone who asked you to back up your thoughts...and then proceeded to see multiple tornadoes including an EF5, where exactly do you get off?

[MidwestChaser]

He's not going to answer you; he throws these bombs into threads, then runs away. See the damage survey from Arkansas thread.

[Ian]

I'm more interested in gambling farther south - maybe (as a rough guess) somewhere along I-70 in KS?  Unless it's really good, High Plains/upslope doesn't do it for me.  It's usually high-based and splitty.  I'd rather chance it at seeing better structure farther south (daylight tornado threat is pretty low will how high bases will be initially but there's plenty of low/mid-level turning for structure) than mess around with general thunderstorm activity up there.  But that's just me.

 

And having said that, we'll cap bust Monday and you'll score up in SD, haha.

I won't even admit to how closely I've followed this since it came on the 384 GFS but not really sold on anything still heh.  If there is any play on Sunday it seems it would be in western SD/NE area and has seemed that way for many days now. Lots of questions there number one being moisture closely followed by will the trough start to edge in quick enough.

 

After that it's kinda muddled from here IMO. Seems it would definitely be a step south but not sure how far.

 

It's a pattern ripe for a few fun days I think at least.. late last week it looked awful so at this point it seems really positive.

[nwburbschaser]

I won't even admit to how closely I've followed this since it came on the 384 GFS but not really sold on anything still heh.  If there is any play on Sunday it seems it would be in western SD/NE area and has seemed that way for many days now. Lots of questions there number one being moisture closely followed by will the trough start to edge in quick enough.

 

After that it's kinda muddled from here IMO. Seems it would definitely be a step south but not sure how far.

 

It's a pattern ripe for a few fun days I think at least.. late last week it looked awful so at this point it seems really positive.

I remember HM mentioning that models were going to have some trouble in the medium range, but I'm not sure if that was in reference to the threat last weekend or just this timeframe as a whole. The threat this past Sunday was looking very mediocre until about 96 hours out so I'm holding out hope still.  

[Thunder Road]

I won't even admit to how closely I've followed this since it came on the 384 GFS but not really sold on anything still heh.  If there is any play on Sunday it seems it would be in western SD/NE area and has seemed that way for many days now. Lots of questions there number one being moisture closely followed by will the trough start to edge in quick enough.

 

After that it's kinda muddled from here IMO. Seems it would definitely be a step south but not sure how far.

 

It's a pattern ripe for a few fun days I think at least.. late last week it looked awful so at this point it seems really positive.

 

I thought about leaving Friday night and flying out there for Sunday, but it doesn't look worth the exhaustion.  We'll meander out Sat and Sun and be ready for chasing Monday.

[Ian]

I remember HM mentioning that models were going to have some trouble in the medium range, but I'm not sure if that was in reference to the threat last weekend or just this timeframe as a whole. The threat this past Sunday was looking very mediocre until about 96 hours out so I'm holding out hope still.  

We've liked blocked up patterns lately on the whole but often the models seem to overdo it at range at least through casual observation.  In this case there seems to be some consensus the trough could get cutoff and buried and wither while spitting out pieces of itself.  Not sure that's necessarily the worst thing ever unless it's too far west and such.  Plus certain areas like KS seem tough plays at times with dry air pushes and cap issues, and winds directionally iffy here and there at least.

 

The one positive is it lets moisture build.  There have been a few long range runs that basically redid what just happened as well.. and letting moisture build seems preferable.

[Ian]

I thought about leaving Friday night and flying out there for Sunday, but it doesn't look worth the exhaustion.  We'll meander out Sat and Sun and be ready for chasing Monday.

Yeah, could just be showers.   I think it's either that or sit in a hotel room somewhere on Sunday so if it looks even see textish it's probably worth a go.

[Chicago Storm]

What's wrong with it?

 

Is this not a splitting supercell (if not just plain linear mode) hodo (NE WY, 0z Tue)?  

 

Is this not a high-base sounding? Is there not veering from the sfc to roughly 550 mb?  (same time, Salina, KS)  Flow at 500 and above is annoying weak, but still...

 

I mean sure you can get something nice out of a right-splitter - sometimes - but not always.  Even when it is, it's usually short-lived.

 

Sure, you can get Goshen (which was a few days before our '09 trip started), and I was out there for 6/7/12, but this is no 6/7/12.

 

Rather than carrying your superiority complex from the other subforum over here, care to actually address where I'm wrong?

No matter where you chase (Out of areas that have a decent shot) next week early on (Sun-Tue) you're likely to have high bases.

 

Then add in that structure will likely be good as well up north (As it generally is), and there will likely be more than just "general thunderstorm activity"...

[Thunder Road]

No matter where you chase (Out of areas that have a decent shot) next week early on (Sun-Tue) you're likely to have high bases.

 

Then add in that structure will likely be good as well up north (As it generally is), and there will likely be more than just "general thunderstorm activity"...

 

On your first point, thanks for backing up what I said, I guess.  I mentioned high LCLs at both places...

 

And I disagree.  As I've said, you can get good structure in upslope flow at times, but with a completely straight hodo, you're going to be dealing with repeated splits and I've played that game the last five years already, so I'm optimistic for something better farther south, moisture/capping issues aside.

 

And note that I've already ruled out Sunday because I won't be there until Monday.

[Thunder Road]

And actually, LCLs are much lower up in SD on Mon than down in KS, but I was saying that in general, that's what I've experienced.

[LocoAko]

I'm more interested in gambling farther south - maybe (as a rough guess) somewhere along I-70 in KS?  Unless it's really good, High Plains/upslope doesn't do it for me.  It's usually high-based and splitty.  I'd rather chance it at seeing better structure farther south (daylight tornado threat is pretty low will how high bases will be initially but there's plenty of low/mid-level turning for structure) than mess around with general thunderstorm activity up there.  But that's just me.

 

And having said that, we'll cap bust Monday and you'll score up in SD, haha.

From a photography/structure standpoint, I like High Plains days (not that the southern High Plains have had jack recently...). In my experience, and keeping in mind I'm still relatively new at this, while you're not gonna get wedges with high bases they're often way crisper and photogenic than hazy, muddled low-base stuff... I'd almost go so far as to say I prefer to chase that stuff. Nothing frustrates me more than low-based, hazy HP wallclouds-on-the-ground. Splitting storms are another issue, but some of the most photogenic storms I've seen (see: avatar) were on split days... so while anecdotal, I don't necessarily see reason for your doubt and pessimism. That said, if you're all (and only) about tornadoes, I hear you.