Central/Western Summer Medium/Long Range Discussions

[JoMo]

Might want to move to this thread for the upcoming threat(s):

 

http://www.americanwx.com/bb/index.php/topic/39995-april-14-17th-severe-weather/

[andyhb]

Might want to move to this thread for the upcoming threat(s):

 

http://www.americanwx.com/bb/index.php/topic/39995-april-14-17th-severe-weather/

 

Yeah, agreed.

[OKpowdah]

Moving on ... early next week gets active again ... with yet another cold front punching southward. 

DAY 4-8 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0359 AM CDT FRI APR 19 2013
   
   VALID 221200Z - 271200Z
   
   ...DISCUSSION...
   BROAD CYCLONIC UPPER FLOW WILL PREVAIL THROUGH THE EARLY/MIDDLE PART
   OF NEXT WEEK...WITH AN EXTENSIVE UPPER TROUGH GRADUALLY SHIFTING
   EASTWARD OVER THE CENTRAL/EASTERN CONUS THROUGH DAYS 6-7.
   
   ON DAY 4/MONDAY...CURRENT THINKING IS THAT SOME SEVERE TSTMS MAY BE
   POSSIBLE ACROSS PORTIONS OF THE SOUTH-CENTRAL PLAINS /POTENTIALLY
   INCLUDING PARTS OF KS-OK-FAR NORTHWEST TX/...MOST LIKELY FOCUSED
   ALONG A SOUTHEASTWARD MOVING COLD FRONT AND/OR DRYLINE DURING THE
   AFTERNOON/EVENING. WHILE ORGANIZED STORM MODES MIGHT BE
   POSSIBLE...ANTICIPATED MODEST NATURE OF MOISTURE RETURN /GIVEN
   RECENT FRONTAL PASSAGE AND ADVANCEMENT IN THE GULF OF MEXICO/
   CURRENTLY LIMITS CONFIDENCE IN A WIDESPREAD SEVERE EVENT.
   
   INTO DAY 5/TUESDAY...THE AFOREMENTIONED COLD FRONT WILL CONTINUE TO
   ADVANCE EAST-SOUTHEASTWARD ACROSS THE ARKLATEX AND TOWARD THE MS
   RIVER VALLEY...AS THE CENTRAL CONUS UPPER TROUGH LIKELY AMPLIFIES.
   AT LEAST SOME SEVERE POTENTIAL SEEMS PROBABLE ACROSS PORTIONS OF THE
   ARKLATEX TO LOWER/PERHAPS MIDDLE MS VALLEY. HOWEVER...THE MAGNITUDE
   OF THE OVERALL RISK IS A BIT UNCERTAIN GIVEN THAT THE STRONGEST
   FORCING/VERTICAL SHEAR MAY TEND TO LAG THE FRONT /ARKLATEX TO LOWER
   MS VALLEY/...AND GIVEN THAT MOISTURE RETURN MAY BE MARGINAL
   NORTHEASTWARD INTO THE OZARKS/MIDDLE MS VALLEY VICINITIES.
   
   FOR DAY 6/WEDNESDAY...EARLY INDICATIONS ARE THAT TSTMS/SOME POSSIBLY
   SEVERE MAY CONTINUE INTO THE GULF COAST REGION ALONG THE COLD
   FRONT...BUT AN APPRECIABLE SEVERE RISK IS NOT CURRENTLY EXPECTED.
   
   ..GUYER.. 04/19/2013

In the longer term ... some legitimate interest in the end of next week, when both the ECMWF and GFS have a cut off disturbance meander into the SW US. 

[OKpowdah]

 5% area covering most of OK into SE KS and SW MO for Monday:

   DAY 3 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0230 AM CDT SAT APR 20 2013
   
   VALID 221200Z - 231200Z
   
   ...NO SVR TSTM AREAS FORECAST...
   
   ...SYNOPSIS...
   AMPLIFIED LONGWAVE PATTERN WILL REMAIN OVER THE CONUS THROUGH
   MONDAY...WITH AN AMPLIFYING/POSITIVE TILT UPPER TROUGH CENTERED OVER
   THE NORTH-CENTRAL CONUS. CONVECTIVE POTENTIAL WILL GENERALLY BE TIED
   TO A SOUTHEASTWARD MOVING COLD FRONT ACROSS THE CENTRAL CONUS. 
   
   ...SOUTH-CENTRAL PLAINS TO OZARKS/LOWER MO VALLEY...
   AS MENTIONED...CONVECTIVE POTENTIAL WILL GENERALLY BE TIED TO A
   CENTRAL CONUS UPPER TROUGH/SOUTHEASTWARD ADVANCING COLD FRONT.
   MODIFIED MOISTURE WILL RETURN NORTHWARD INTO THE REGION THROUGH THE
   FIRST PART OF MONDAY...BUT NONETHELESS...OVERALL MOISTURE CONTENT IS
   EXPECTED TO REMAIN RELATIVELY MODEST WITH SURFACE DEWPOINTS LIMITED
   TO THE 50S/PERHAPS LOWER 60S F ACROSS THE SOUTH-CENTRAL PLAINS AHEAD
   OF THE FRONT. 
   
   INITIALLY...ELEVATED/MODEST INTENSITY TSTMS WILL LIKELY OCCUR ACROSS
   THE LOWER MO VALLEY/MIDWEST VICINITY NEAR THE COLD FRONT. INTO THE
   AFTERNOON...SUBSEQUENT SURFACE BASED TSTM DEVELOPMENT COULD OCCUR BY
   MID/LATE AFTERNOON FARTHER SOUTHWEST NEAR A SURFACE TRIPLE
   POINT...WHICH MAY BE LOCATED ACROSS WESTERN OK OR IMMEDIATELY
   ADJACENT PORTIONS OF SOUTHERN KS/TX PANHANDLE. OF HIGHER CONFIDENCE
   WILL BE FOR TSTMS...SOME SEVERE...TO INCREASE NEAR/PERHAPS
   IMMEDIATELY BEHIND THE SOUTHEASTWARD ADVANCING COLD FRONT INTO
   MONDAY EVENING. 
   
   OVERALL...AT LEAST SOME POTENTIAL FOR SEVERE HAIL WILL EXIST
   ESPECIALLY MONDAY AFTERNOON/EVENING GIVEN SUFFICIENT
   INSTABILITY/FAVORABLE VERTICAL SHEAR. FURTHERMORE...CURRENT THINKING
   IS THAT A SLIGHT RISK COULD VERY WELL BE NECESSARY IN SUBSEQUENT
   OUTLOOKS AS DETAILS BECOME CLEARER INTO THE DAY 2 OR DAY 1 TIME
   FRAME.
   
   ..GUYER.. 04/20/2013

[andyhb]

On the plus side, the drought has certainly taken a hit over the past six weeks...

[Ian]

problem is, still a lot worse than last year at this pt.

[BowMeHunter]

problem is, still a lot worse than last year at this pt.

 

 

still in a lot better shape this yr going forward..   who knows what the next months bring though..  another,  Tippy, Sonoran heat ridge fetish this late spring/early summer will wreck the little progress fast.

[brettjrob]

problem is, still a lot worse than last year at this pt.

 

Agreed. Fundamentally, there's not much positive to hang our hats on right now. The only thing staving off depression is the inherent unpredictability beyond 10-14 days and the fact that the typical peak of chase season is still 30-45 days out. If May and June are even remotely comparable to last year, this will probably be the darkest period for Plains chasing since the late 80s.

[Ian]

Agreed. Fundamentally, there's not much positive to hang our hats on right now. The only thing staving off depression is the inherent unpredictability beyond 10-14 days and the fact that the typical peak of chase season is still 30-45 days out. If May and June are even remotely comparable to last year, this will probably be the darkest period for Plains chasing since the late 80s.

CPC for May is kinda not so great tho good news is they've not had a fantastic run of late. My worry has been it will flip from winter hanging on straight to some ugly ridge over the drought area. But the pattern has certainly not been the same this year and there's reason to think we'd hold a fairly tight gradient of warm to cool somewhere in the country the next 4-8 weeks or so at least. The general pattern makes me think it might be a decent high plains and like central to northern plains and midwest type of year tho the drought puts a lot of question in that. 

 

My g/f is going to make me go on vacation with her next year which means I prob won't get to go chasing, so things should right themselves then if not prior.

[andyhb]

Agreed. Fundamentally, there's not much positive to hang our hats on right now. The only thing staving off depression is the inherent unpredictability beyond 10-14 days and the fact that the typical peak of chase season is still 30-45 days out. If May and June are even remotely comparable to last year, this will probably be the darkest period for Plains chasing since the late 80s.

 

Alright let's take a step back here for a minute, one thing I do not see is a massive death ridge and/or omega block showing up to discombobulate anything that tries to eject out of the Rockies, that alone is a step up from last year.

[brettjrob]

Alright let's take a step back here for a minute, one thing I do not see is a massive death ridge and/or omega block showing up to discombobulate anything that tries to eject out of the Rockies, that alone is a step up from last year.

I'm not implying at all that it will be like last year. It was purely hypothetical, and a statement about how bad the run from 2012 into the first third of 2013 has been.

 

That said, the medium range modeling has been consistently... unpleasant looking into the foreseeable future. Stagnant upper flow and a tendency toward western ridging/eastern troughing whenever amplification occurs. Thankfully, as I said, the real meat of the the Plains season is still beyond that foreseeable range.

[OKpowdah]

Something also to keep in mind through the coming weeks ... very large extent of anomalous snow cover over the northern Plains into southern Canada.

 

[Stebo]

Something also to keep in mind through the coming weeks ... very large extent of anomalous snow cover over the northern Plains into southern Canada.

 

2013110.png

 

Yes and unless we get a massive warm up sometime soon, which is not in the foreseeable future, the gradient should remain for The Plains and The Midwest. Also if the Gulf can go untouched there will be ample moisture feeding Northward into the gradient, all you'd need at that point is a modest system thrown into the mix to theoretically get a decent output.

 

Obviously it is in la-la land but the GFS has been advertizing higher amounts of instability over the Southern Plains in about a week from now. The moisture/instability will certainly be there.

[OKpowdah]

Couple of days to watch this week: tomorrow and Friday.

 

Tomorrow is yet another cold front passage by the late evening, but if the cap breaks early, could see some convection fire along the dryline in western OK. Not working with much upper level forcing, and BL moisture is pretty lacking. The 0-3km wind profiles are not bad at all. Maybe a few high base supercells in W OK with beautiful structure and all. Would be pretty cool. Then probably a solid overnight MCS with the cold front.

[Ian]

Euro ens mean pattern signals are pretty awful into early May. Higher than normal heights in the Plains, lower than normal heights in the Gulf.

[OKpowdah]

MD up in NW OK. Great convergence along the dryline with cu field developing

 

 

[andyhb]

Euro ens mean pattern signals are pretty awful into early May. Higher than normal heights in the Plains, lower than normal heights in the Gulf.

 

Yeah I'm hoping a lot of chasers didn't schedule their "appointments" during this timeframe.

[brettjrob]

Yeah I'm hoping a lot of chasers didn't schedule their "appointments" during this timeframe.

 

The first 20 days of May have been essentially useless the past two years. Looking more and more like we'll make it three for at least the first week to 10 days.

[baroclinic_instability]

MD up in NW OK. Great convergence along the dryline with cu field developing

 

Oklahoma.vis.gif

 

current.THTE.grad.png

Nice batch of DMC up there. NW flow convection is such a forecast headache in the plains...especially the high plains. We had a lot of trouble in LBF with NW flow DMC popping off the Black Hills and the local convergence near/around it in the mid summer.

[baroclinic_instability]

Becoming a familiar sight this spring.

 

[andyhb]

Becoming a familiar sight this spring.

 

Gotta say I thought the cold would help the severe threats this year (i.e. some enhancement of the baroclinic zones), but it's turning out to be the polar (pun intended) opposite of last year, still yielding problematic results.

[AgeeWx]

Gotta say I thought the cold would help the severe threats this year (i.e. some enhancement of the baroclinic zones), but it's turning out to be the polar (pun intended) opposite of last year, still yielding problematic results.

 

 

I've always been under the impression that highly baroclinic systems this early in the year never seemed to produce the widespread severe events that they do later in the spring and summer where the cold fronts generated weren't dominated so much by the strength and placement of the Polar Jet.

 

Then again last year the baroclinity wasn't generated so much due to snow pack as it might have been so far this Spring.

[andyhb]

I've always been under the impression that highly baroclinic systems this early in the year never seemed to produce the widespread severe events that they do later in the spring and summer where the cold fronts generated weren't dominated so much by the strength and placement of the Polar Jet.

 

Then again last year the baroclinity wasn't generated so much due to snow pack as it might have been so far this Spring.

 

It depends, an extra shot of cold air can tighten the baroclinic zone so any sfc cyclone traveling along it can rapidly deepen potentially (but generally this is most favorable once leeside cyclogenesis has taken place, at least from my observations).

 

However, this year, the CAD/anafrontal setup to the leeside of the Rockies so far has been suppressing cyclogenesis and undercutting storms that have tried to develop in the warm sector.

[Ian]

The first 20 days of May have been essentially useless the past two years. Looking more and more like we'll make it three for at least the first week to 10 days.

The long term blocking pattern mixed with the drought not very friendly overall. At least by late May ther is usually fairly regular junk.

I've seen 2002 and 2009 swirling in various posts (not tornado related) in the last few days. That would be a disaster.

[brettjrob]

The long term blocking pattern mixed with the drought not very friendly overall. At least by late May ther is usually fairly regular junk.

I've seen 2002 and 2009 swirling in various posts (not tornado related) in the last few days. That would be a disaster.

 

There's a private operational met who graduated from OU (also a big chaser) that does some long-term forecasting, and has shown some skill with his spring predictions over the years I've followed. Sad to say, he's been pushing 2002 since back in the winter, and so far he looks prophetic. That was a putrid year with the main problem being incessant frontal intrusions.

 

Oh, and just to cheer everyone up further: I got a look at the long-range ECMWF last week, and it was simply abysmal all the way through May. Like, not one semblance of a good pattern the whole time. Haven't followed it at all in the past so have no idea whether there's any skill whatsoever in the 20+ day range.

 

Basically, as I said the other day: the only thing positive right now is long-range uncertainty. :-/

[Stebo]

There's a private operational met who graduated from OU (also a big chaser) that does some long-term forecasting, and has shown some skill with his spring predictions over the years I've followed. Sad to say, he's been pushing 2002 since back in the winter, and so far he looks prophetic. That was a putrid year with the main problem being incessant frontal intrusions.

 

Oh, and just to cheer everyone up further: I got a look at the long-range ECMWF last week, and it was simply abysmal all the way through May. Like, not one semblance of a good pattern the whole time. Haven't followed it at all in the past so have no idea whether there's any skill whatsoever in the 20+ day range.

 

Basically, as I said the other day: the only thing positive right now is long-range uncertainty. :-/

 

I assume you mean the Euro weeklies, if so they have been hit or miss all year so I would take it for a grain of salt.

[brettjrob]

I assume you mean the Euro weeklies, if so they have been hit or miss all year so I would take it for a grain of salt.

 

Yeah, whatever is on the AccuWeather Pro site. I believe it was the weeklies, as in released once a week. Glad to hear they've struggled recently, then.

 

Even 2009 had a decent period late, primarily early to mid June. A lot of the setups underperformed, sometimes for mesoscale reasons, but at least it goes to show you can still break back into an active pattern after the jet stream retreats to the Arctic Circle for most of May.

[Stebo]

Yeah, whatever is on the AccuWeather Pro site. I believe it was the weeklies, as in released once a week. Glad to hear they've struggled recently, then.

 

Even 2009 had a decent period late, primarily early to mid June. A lot of the setups underperformed, sometimes for mesoscale reasons, but at least it goes to show you can still break back into an active pattern after the jet stream retreats to the Arctic Circle for most of May.

 

I don't expect the jet to retreat that quickly, there is a ton of cold air/snow across Canada right now. Too many are looking at the long range GFS and the Euro weeklies and believing them to be gospel. Sure things look subpar right now, but what is not to say that things could/would change. Maybe I am being overtly optimistic, but just think it is way to early to write off this season as being terrible. I mean busting out bad year analogs with things only being in the 3rd week of April is a bit misguided.

[Ian]

There's a private operational met who graduated from OU (also a big chaser) that does some long-term forecasting, and has shown some skill with his spring predictions over the years I've followed. Sad to say, he's been pushing 2002 since back in the winter, and so far he looks prophetic. That was a putrid year with the main problem being incessant frontal intrusions.

 

Oh, and just to cheer everyone up further: I got a look at the long-range ECMWF last week, and it was simply abysmal all the way through May. Like, not one semblance of a good pattern the whole time. Haven't followed it at all in the past so have no idea whether there's any skill whatsoever in the 20+ day range.

 

Basically, as I said the other day: the only thing positive right now is long-range uncertainty. :-/

 

I don't have access to the weeklies that go way out but I have access to the mean which goes to 360.... I'll just say it tends to smooth the long range pattern out way more than you usually end up seeing and is often wrong. There are stretches where it looks like nothing happens that end up having decent storms.  Overall I don't have much faith in any long range models.. the problem there is that ridges tend to be modeled much better than specific synoptic systems so if it's showing up consistently it's likely to be a problem. 

 

I've worried all along we'd just flip a switch and go back to a drought dominated pattern.. I still think it's premature to say that will happen but I wouldn't be shocked.  The snow up north is probably still helpful there even if it's screwed things up lately, but it is almost May.. won't take too long to melt it off.

 

Then again I see others tossing around analogs that are good "late" like 1997. I wish I knew more how to identify them better myself.. tho I did see similarities to 2002 on my own but I'll just assume I don't know what I'm looking at there. 

[AgeeWx]

I don't have access to the weeklies that go way out but I have access to the mean which goes to 360.... I'll just say it tends to smooth the long range pattern out way more than you usually end up seeing and is often wrong. There are stretches where it looks like nothing happens that end up having decent storms.  Overall I don't have much faith in any long range models.. the problem there is that ridges tend to be modeled much better than specific synoptic systems so if it's showing up consistently it's likely to be a problem. 

 

I've worried all along we'd just flip a switch and go back to a drought dominated pattern.. I still think it's premature to say that will happen but I wouldn't be shocked.  The snow up north is probably still helpful there even if it's screwed things up lately, but it is almost May.. won't take too long to melt it off.

 

Then again I see others tossing around analogs that are good "late" like 1997. I wish I knew more how to identify them better myself.. tho I did see similarities to 2002 on my own but I'll just assume I don't know what I'm looking at there. 

 

 

All of the tenured professors up here who were around for the Red River Flood of 1997 claim that, at least in the synoptic sense, this year resembles 1997.  I don't know how late the snow pack stuck around back then but I know that up here we went from a late Spring with a mid-April freeze to SW flow aloft and daytime highs jumped from mid 30s to lower 70s in the span of about 8 days.