High Plains Drifter

Target: Mankato, KS by ~4pm

Good morning! Didn’t get a whole heck of a lotta sleep last night… getting everything ready to set out for the chase. Stacie got here about 12:30am, and in a couple hours Jay will be arriving. It appears everything is on track for a decent supercell setup in north-central Kansas. The target appears to be along the Hwy 36 corridor between Smith Center and Belleville. WSW flow at 500mb of 40-50 kts will spread over the remnant Pacific cold front "acting dryline" promoting very healthy deep layer shear. Low level moisture will be marginal at best for tornadoes, but given the shear environment, it is certainly possible to get a tornado especially between 7 and 9pm when the 0-1km shear ramps up significantly.

As it stands now, after today’s chase… we are looking at two down days. Wednesday we will likely drive to Rapid City and Thursday will be a leisure day around the Black Hills. Low level moisture will likely increase enough for decent storms on Friday. One hell of a cap will be in place south of the Dakotas with widespread near-100°F heat expected from western Nebraska into the TX-OK Panhandles. In this situation, it’s best to be near the 700mb baroclinic zone… which will be well into the Dakotas Friday and even into the weekend.

It’s Monday morning, the day before Day 1. I met up with Matt Crowther and Jim Leonard last night here in Dodge as they set out for their trip. It looks like they’ll head into Colorado today to try and catch anything off the Palmer Divide towards early evening when some of the good upper flow comes out. Last night was rather interesting. We ate at Montana Mikes and we all got a free dinner thanks to a car accident near 14th and Wiatt Earp. One (or more?) of the involved parties ran into a power pole and took out the power along West Wiatt Earp, so the power went out for a good half hour to 45 minutes before our food came out. Fortunately, we timed it just about perfectly as they must have just finished cooking our food before the power went out. The salmon was still good, even though we all ate our supper in the dark… well not pitch black, but you get the idea. We then headed to my work (NWS-DDC) to look at some new 00z model stuff.

Jay, Stacie, and I will probably reunite with Jim, Matt, and Jim’s friend from Florida (they are all chasing in Jim’s van) on Tuesday. Below is my last installment of the “dart-board”. The last dot is now in north-central KS. I think there may be a decent “tail-end Charlie” play in this area Tuesday. Jay will be driving down from Lawrence very early Tuesday morning and will leave his car here in Dodge for the two weeks we are out. Stacie will be arriving late this evening.

Looks like after Tuesday, we’ll be down Wednesday and Thursday (not chasing), but setting up in the Dakotas (likely Rapid City) for late-week/early weekend activity. The 850-700mb baroclinic zone will be up here, along with the best mid-upper winds, so this is where we’ll be. There are growing signals that towards late weekend into early next week…. once Jon, Rob, and Mitch come out (They’ll be joining us on Saturday), we’ll begin to shift our focus south I think… the ECMWF shows some decent 500-200mb flow shifting into the southwest as another deep trough (hopefully) evolves eastward into the intermountain west. This would probably result in increased southwesterly flow all across the High Plains. Early next week (like around the 30-31??) could be interesting — a wide open Gulf with very good looking trajectories originating from the deep tropics…allowing for very good moisture. We’ll see. The 29-31 of May is a historic hot time anyway, so there’s hope there.

• Day 1, Tue 5/23=N. Central KS (photogenic supercells?)
• Day 2, Wed 5/24=Travel to Rapid City (down day it appears)
• Day 3, Thu 5/25=Sightseeing? (looks like a down day, not much moisture yet?)
• Day 4, Fri 5/26=Southern Dakotas (looks better for chasing)
• Day 5-7, Sat 5/27 to Mon 5/29=Trending a bit farther southwest each day into the central High Plains as new trough emerges in the west??? Very preliminary. Climo would support this).

Well… all along it certainly appeared that there would be a significant chunk of that big Pacific trough would eject northeast into the Plains. The question was when it would eject…and exactly where and how strong. It appears we finally have enough consensus in the models to say that the “when” will be Tuesday (the 23rd) and the “where” will be somewhere in Nebraska.

Given this faster scenario…and the fact that Wednesday (our original start day) looks marginal at best in western Iowa along with Thursday being down, it appears… I decided to take Tuesday off work and have Stacie and Jay meet me here in Dodge earlier so we can make Tuesday a chase day.

Anyway, the updated dartboard is below.. I changed the Day 1 to May 23 and the icon on the dartboard for May 23 is a blue circle instead of a star to represent this change in Day 1.

The scenario I’m playing in my head now is..

• Day 1, Tue May 23=Nebraska (photogenic supercells?)
• Day 2, Wed May 24=Western Iowa (early afternoon under cold pool aloft?)
• Day 3, Thu May 25=Travel to Dakotas (down day?)
• Day 4, Fri May 26=Somewhere in the Dakotas (marginal supercell chase day?)
• Day 5 and beyond…. ?? (Wayyy too unclear)

The 24th may very well be a “Day 2 Setup” day. It’s still 5 days out, but the new GFS including Ensembles, Canadian, and ECMWF model suggest that the lead system of interest will rapidly eject northeast into the Rockies and substantially weaken as it hits the ridge. This would put the central plains in a weak-modest short-wave northwest flow behind the system with a front well to the south. Should this pan out, then there won’t be any chasing Wednesday. I don’t want to chase south on Wednesday, because it would just be a one-day deal…. then a haul clear up north where the Day 6-8 progs are showing very nice flow coming across the northern Rockies into the northern High Plains. It will take awhile before adequate moisture makes it up into northern Nebraska/Dakotas… but this is clearly where the best mid-upper flow will be for supercells. So, at this point, from what I see in today’s GFS… The “dart” will be Rapid City… and the Firehouse Brewery …a logistical target only for Thurs-Fri setup. Subject to change of course……. stay tuned!

GFS 500mb:

GFS Surface:

Canadian Model:

Here’s the updated dart-board. The red star means it’s a Day-2 positioning destination, and not really a chase-day target based on the GFS. More later!

Well the 00z and 12z runs of the GFS today show a similar pattern, which offers a little hope in terms of maybe some consistency beginning to show up for the 24th… that is until you look at the 18z run. The “off hour” runs of the NCEP models are usually quite suspect since they do not have the benefit of RAOB data (which are 12z and 00z). Anyway, both the 00z and 12z runs today (the 18th) show a nice shortwave trough over the northern Rockies entering the northern High Plains with a discrepency in timing.

GFS 500mb:

GFS Surface:

Here is today’s 12z GFS Ensemble graphic of 500mb heights and precipitation… Great uncertainty exists over the northern plains and midwest where it looks more like spaghetti. In looking at the 0.50″ QPF contour, it looks like there’s a storm track across the northern plains and midwest. There’s a huge timing issue… but keep in mind, this is still a day 6.5 forecast!!:

The 12z Canadian global model (not shown) also supports a storm system over the northern Rockies ejecting from the large Pacific trough. The problem is, it is about a day faster than the GFS…. which, if more correct, Wednesday the 24th could either be a) a down day, or b) much farther south along the front in the Central Plains.

The upshot is… who knows! That’s the key… it’s 6 days out, and the models continue to be all over the place… but this is expected…. we won’t be able to get reliable signals for a chase target “region” (or if we’ll be chasing at all the first day) until about 108 to 120 hours… if we are lucky… and more realistically 72 hours. But, to continue the game, the “GFS Deterministic dart” for today will be in the same general area as before:

Well, still a ton of uncertainty about the evolution of the Pacific trough. In fact, all 4 of today’s GFS runs from 00z to 18z are markedly different from each other. Evan all four of todays GFS Ensemble suite of members show a lot of difference (below)….

This means very low uncertainty for sure! I think there is a continued signal, though, that Wednesday the 24th will indeed be a chase day… and most likely north of 40°N latitude (i.e. north of the KS-NEB line).

GFS 500mb:

GFS Surface:

Not shown, but the 18z GFS valid May 25/00z shows the storm system over the Northern Rockies…with nice 40-50kt west to west-southwest flow across much of the northern plains… even as far south as southern Kansas. I honestly do not know where to place today’s “GFS Deterministic” chase target dart… A compromise between the 12z and 00z run suggests northern KS into northern Nebraska… so I’ll shift today’s dart a little farther southeast I think This is fun! I think…

The GFS Ensembles today… in conjunction with the 12z ECMWF and the 12z Canadian suggest an increasing probability of a scenario where the southern-most jet streak at the base of the very deep Pacific trough will eject northeastward into the intermountain-west/northern Rockies early next week. After this wave moves northeast… subsequent jet maximas will continue to move into the west it appears… re-orienting the trough as it slowly shifts east. This scenario could indeed significantly break down the very amplified “destructive” ridge over the Plains.

GFS Ensemble forecast from today’s 12z run:

There is still a lot of uncertainty in how this first wave moves into the west… and it may indeed be a slower evolution than the models show…especially the GFS and its ensemble members. It’s good to the the ECMWF show a significant height fall situation over the west promoting downstream west-southwesterly flow into the Northern Plains. It’s looking more and more like we will indeed have a couple chase days right away in the northern plains…albeit with somewhat limited moisture I would imagine. It looks like a good chaseable pattern beginning to evolve in the Day +7 progs with a little more congruence among the ECMWF, Canadian, and GFS (and ensembles).

Here’s today’s GFS runs:

GFS 500mb:

GFS Surface:

And to continue the game, here is today’s “GFS Deterministic dart”…. it’s really close to yesterday’s actually:

The daily interrogation of the deterministic “control” run of the GFS in the 7 to 10 time frame is a good exercise of just how volatile the numerical models are at prediction in this time frame when it comes to trying to narrow down a chase “region” within our chasing domain — it really cannot be done. But it’s still fun, isn’t it? The whole anticipation “as the models turn”. Below is the new 5/15 run of the GFS. Look how different this deterministic GFS run is from the day before:

GFS 500mb:

GFS Surface:

The GFS now suggests that a significant “chunk” of the “off the west coast” deep trough will eject northeastward into the Rockies…supporting fairly robust development on the northern high plains. Should this verifiy verbatim, it most certainly looks like Dakotas chasing. The ECMWF and Canadian models (not shown), are much less impressive with such a scenario… with mean ridging continuing to be rather amplified over the Rockies…but enough flow atop the ridge over the far northern high plains… like Montana into the northern Dakotas for organized severe wx.

A much better way to try to draw “signal” out of the 7-10 day range is to use the ensemble approach. Below is a 4-panel of the GFS Ensemble forecast from the 5/15 12z run of 500mb height (570dam), 850mb Temp (20C), mean sea level pressure (1000mb), and Precip (0.25″):

Interpreting this 4-panel above… there’s a signal that something of significance may cut underneath the ridge…or “riding atop” the ridge, significantly squashing it inducing more westerly flow farther south (versus little flow at all near the ridge axis). The dark black isopleths on the ensemble 4-panel represent a mean of all the members.

So now it’s time to hit the dart board. A “consensus” of the two 5/15 GFS runs suggests the best chasing in South Dakota somewhere… so that’s where I’ll put today’s dart for Day 1 of the chase trip.

Welcome to the Chase Trip 2006 Blog! My chase vacation runs from May 24 through June 8. This year, I’ll be storm chasing with Jay Antle for our 9th year. Along with us will be Stacie Hanes, forecaster from the Fort Worth NWS office, from May 24-30. Jon Smith, my long-time friend from the grade school days, will also be with us — along with with Mitch Daszewski and Rob Mitchell. This will be the first time all of us have chased together in about 3 years. Jon, Rob, and Mitch will be out from May 27 to June 4, and will likely hook up with me, Jay, and Stacie out in the field somewhere.

It will continue to be a very quiet chase pattern through the next week….with some glimmer of hope that the pattern will become more favorable for chaseable storms around the time that Day 1 arrives. I always like to speculate/guess where our first day of the trip will be based on extended model trends. It’s within 10 days of Day 1 now, so I’ll keep a "dart-board" on hand here to keep track of how the GFS does for May 24th

A large scale upper ridge will dominate the western CONUS up through probably the beginning of our trip. How strong the ridge is, where exactly the axis will be…etc, etc…is considered to be "white noise" at this point, but there seems to be a continued signal that the longwave pattern will be of northwest flow even through mid-next week…according to the deterministic GFS. Below are two 2-panel charts from today’s GFS 00z and 12z runs:

GFS 500mb:

GFS Surface:

both the 12z and 00z run support a northwest flow scenario with a decent surface high somewhere centered over the northern plains or midwest. A consensus between the two runs would suggest an upslope play probably in the OK-TX Panhandles region. This is a 10-day prog, so it’s bound to change, and it usually does. Below is the May 24 (Day 1) dart-board, which I will update daily based on the new GFS 00 and 12z runs Not exactly scientific, but we’ll see just how good (or bad) the GFS really is