6/11/04 FCST: Central Plains

[Tony Laubach]

Last time I did this, we had a record day, so I figured I'd shoot for it again..

NWS in Wichita made mention of a potential storm setup late in the week (Thurs/Fri). I opted to create this topic for the Friday as the HWO makes mention going from Thursday night into Friday night. If the week progresses to keep this true and shifts it more towards Thursday (or Saturday), other threads can be started (or I'll change this one) to go with forecast adjustments..

If I were to make a preliminary target this far out (and I have to after my last two trips down this way), I would say someplace along Hwy 160 between Medicine Lodge and Harper, KS.

Here's the segment of the HWO out of Wichita from 5:16 this evening..

SIGNIFICANT THUNDERSTORMS, POTENTIALLY SEVERE, ARE POSSIBLE FROM THURSDAY NIGHT THRU FRIDAY NIGHT, AS ANOTHER COLD FRONT AND DRYLINE MOVE ACROSS THE REGION. WHILE CONSIDERABLE UNCERTAINTY EXISTS IN THE TIMING, MAGNITUDE AND THREAT, ALL CONCERNED PARTIES SHOULD BE ATTENTIVE TO SUBSEQUENT OUTLOOKS.

If this starts to verify as the week goes on, look for me to once again return to the scene of the crime(s) for another bout in Kansas...

 

[Jeff Snyder]

The last look of the GFS I had showed an atypical June trough coming out of the western US... The system has the strength and depth of what we usually see in early May. Strong negative tilt upper trough with excellent diffluence in the plains. A nice low-level jet is progged to be in place several days ahead of this -- starting in the Mon/Tues timeframe -- giving ample time to transport moisture-laden air across the plains.. I have a hunch that there will be a trend to shift the forecast trough position northward with time as climatology would favor central / northern plains. The again, early May was all but climatologically-correct with a July-like ridge across the central US, locking the upper jet into Canada. Whatever the case, the GFS has done a pretty good job, consistency-wise, with this system thus far... So far this season, when the GFS shows good run-to-run consistency regarding a strong system, it tends to verify pretty well. So, this will be something to keep an eye on. It's VERY early to start talking about anything other than the large-scale synoptic pattern... I mean, a couple of days ago it looked like today would be a decent chase day in the souther plains... lo and behond, that forecast didn't pan out at all...

 

[Jon Miller]

ETA is showing band of 3000 cape from western Iowa down into n. Ok. 65 to 70 dew pts and -6 LI. Winds don't appear to be the best - so whats everbody's progs on whats going to happen & where on Friday ? I'm currently favoring western Iowa near the frontal boundary.

 

[Mike Hollingshead]

Western IA for sure. Will be worth watching for any outflow boundaries into IA furher. Directional shear ain't very good, but nice speed shear. Very strong instability with an excellent coupled jet atop it. Just seems like to me sometimes when you get these strong coupled jets with strong divergence aloft you don't need as much low level directional shear...especially with such instability. Looks like two potential big days for sure. As with most any setup morning convection could be a problem.

 

[Gabe Garfield]

Mike, a word of warning after getting (partially) hosed on May 29th:

Although the best speed shear was in Oklahoma on the 29th (which is where I chased), the best storms were in Kansas because of the better directional shear (00z OUN sounding). Despite having nearly 50 kt of 500 mb flow in C. Oklahoma, the supercell that formed in western Oklahoma was an HP. However, an awesome classic supercell formed in somewhat weaker 500 mb flow. Never underestimate the importance of low level shear (a la May 12).

By that logic, I think somewhere E and NE of the triple point would be a great place to target.

Gabe

 

[Mike Hollingshead]

Yeah I agree Gabe, but this is for Friday. All we have for Friday is the speed shear, unless we can get an ofb in IA or somewhere to help....or you are up in n MN or Canada.

 

[Gabe Garfield]

Mike, just noticed that. Sorry...LOL

Gabe

 

[Mike Hollingshead]

Move any targets half a state east. 12z eta is a bit quicker. Impressed by this second day cape it's spitting out on Friday. You'd think it'd be rather contaminated, but I guess this ain't always the case. Northeast IA might be a nice play.

 

[BMcMillan]

00Z ETA is showing a nice backed southeast flow developing into central and north central Iowa towards the dryline, with 3000+ CAPE overhead by mid afternoon, if skies can clear out after overnight convection. It is sure is nice to have a day where a decent storm threat exists close to home. Good luck to anyone venturing out tomorrow- I hope Iowa treats you well...

 

[Amos Magliocco]

I just glanced through the ETA and this setup looks formidable. Powerful negatively titled system crashing into a highly juiced airmass with strong 0-1km shear and adequate deep layer shear. I don't know if the dryline is aggressive enough to be a player in this one, but the warm front might suffice. Very dynamic setup.

Flies in the ointment include a nocturnal MCS which could leave clouds and debris and limit daytime heating. But with CAPE values progged over 4000 j/kg, if we're short a a thousand joules or so we can afford it, right? LOL.

Des Moines is stocking up on Dr. Pepper:

http://iwin.nws.noaa.gov/iwin/ia/special.html

 

[Ryan Pfannkuch]

I'm somewhat surprised at the lack of discussion concerning the IA/MN threat for this afternoon as satellite is showing an increasingly interesting situation developing over the NW quadrant of Iowa right now as a wf lifts north and a dryline moves in from the west. SPC is going MDT risk on the new Day 1.

Sig TOR parameter is up to 3 now in the Sac City IA area and that area will likely drift northeast with time. My main concern right now for the short term is the cap as 700mb temps of 11C+ cover a good chunk of IA but that should diminish as the afternoon goes on. Also low-level flow isn't all that spectacular, but I think this area definitely merits some attention.

 

[Larry J. Kosch]

Medium Risk Considered

NWS is having a mesoscale discussion about upgrading the SLIGHT risk in MN and IA to MEDIUM:

AREAS AFFECTED...NRN IA...SRN MN...AND FAR SWRN WI

CONCERNING...OUTLOOK UPGRADE VALID 111510Z - 111645Z

AN UPGRADE TO A MODERATE RISK OF SEVERE THUNDERSTORMS IS PLANNED ON THE 1630Z DAY 1 OUTLOOK ACROSS NRN IA...SRN MN...AND SWRN WI.

Keep Watching!! 8) LJK.

Update: It's official. MEDIUM risk for IA, MN and WI. 8) LJK.

 

[Craig Maire II]

Waterloo Iowa

I'm in CedarFalls Iowa right now at the local public Library, knew they would upgrade us to a moderate risk!! I'm ready to chase/spot as soon as these suckers decide to show there "faces"!!


HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE LA CROSSE WI
1215 PM CDT FRI JUN 11 2004

IAZ008>011-018-019-029-030-MNZ086-087-094-095-WIZ054-061-121100-
ALLAMAKEE-CHICKASAW-CLAYTON-CRAWFORD-DODGE-FAYETTE-FILLMORE-FLOYD-
GRANT-HOWARD-MITCHELL-MOWER-OLMSTED-WINNESHIEK-
1215 PM CDT FRI JUN 11 2004

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PARTS OF SOUTHEAST
MINNESOTA...NORTHEAST IOWA...AND SOUTHWEST WISCONSIN.

.DAY ONE...THIS AFTERNOON AND TONIGHT

A FRONTAL BOUNDARY JUST SOUTH OF THE AREA WILL SHIFT BACK NORTH AS A
WARM FRONT THIS AFTERNOON. THIS WILL ALLOW INSTABILITY TO INCREASE
AND CREATE A FAVORABLE WIND PROFILE FOR THE DEVELOPMENT OF SEVERE
WEATHER. THUNDERSTORMS ARE MOST LIKELY TO DEVELOP ACROSS SOUTHERN
MINNESOTA AND NORTHERN IOWA BETWEEN 4 AND 6 PM...AND THEN MOVE EAST.

THE MAIN THREAT FROM THESE STORMS INITIALLY WILL BE LARGE HAIL AND
VERY HEAVY RAIN. BUT A FEW STORMS ALONG THE WARM FRONT MAY BECOME
TORNADIC. THIS WILL HAVE TO BE MONITORED CLOSELY. THE STORMS WILL
BECOME MORE OF A DAMAGING WIND THREAT AS THEY MATURE AND SHIFT EAST.
THE SPEED OF THE STORMS MAY PRODUCE A QUICK INCH OF RAIN BUT
WIDESPREAD FLASH FLOODING IS NOT EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

ON SATURDAY NIGHT AND SUNDAY...A LOW PRESSURE SYSTEM WILL MOVE EAST
THROUGH THE REGION. THUNDERSTORMS ARE EXPECTED TO REDEVELOP ACROSS
IOWA AND MAY SHIFT NORTH AND EAST. ADDITIONAL RAINFALL OF UP TO AN
INCH MAY MOVE ACROSS THE AREA WITH A SMALL SEVERE WEATHER RISK.
THE STRONGER STORMS AND HEAVIER RAIN ARE EXPECTED TO REMAIN SOUTH OF
THE AREA.

ANOTHER LOW PRESSURE SYSTEM WILL MOVE EAST THROUGH THE REGION ON
MONDAY. THIS SYSTEM WILL PROVIDE YET ANOTHER ROUND OF RAIN TO
THE REGION POSSIBLY FURTHER AGGRAVATING THE FLOODING SITUATION ACROSS
THE REGION.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL BE NEEDED BETWEEN 4 PM AND 10 PM TONIGHT.
TORNADO WATCHES WILL BE ISSUED MID AFTERNOON SO SPOTTERS SHOULD
PREPARE FROM THAT POINT ON AND MONITOR LOCAL CONDITIONS CLOSELY.
WHEN STORMS APPROACH YOUR AREA...DEPLOY SPOTTERS AHEAD OF TIME.
ASSUME YOU WILL BE NEEDED TONIGHT.

RAINFALL REPORTS AND FLOODING CONDITIONS ARE ALSO NEEDED.




Craig Maire II

 

[Craig Maire II]

Possible development??

Using the DMX weather radar at 12:28pm cdt I am seeing 2 echoe returns at 20 dbz in northwest Iowa... :shock:

 

[Larry J. Kosch]

Early Storms

I was able to barely see in the GOES-12 visible SAT a thin line of clouds poking up thru the cloud clutter that's covering the state of IA. And NWS radar is barely picking up some return signals east of Sioux City or west of Storm Lake.

Too early yet for anything to develop. Wait for a WW posting. 8) LJK.