Chase Case #12

OK...so here's the case. I didn't pull out a vintage one here because I was afraid you wouldn't like the lack of surface plots (none past 1998 on the Vortex site). Anyways, you wake up in the morning and find the following information at your disposal. In addition, while parusing the data, SPC issues a weather watch at about 730 AM. Here is the text...

THE STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

CENTRAL AND SOUTHERN IOWA
NORTHEAST KANSAS
NORTHERN AND WESTERN MISSOURI
SOUTHEAST NEBRASKA

EFFECTIVE THIS MORNING AND AFTERNOON FROM 730 AM UNTIL 100 PM.

HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70
MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE SEVERE THUNDERSTORM WATCH AREA IS ALONG AND 100 STATUTE
MILES EITHER SIDE OF A LINE FROM 25 MILES WEST OF LEAVENWORTH
KANSAS TO 45 MILES NORTHEAST OF DES MOINES IOWA.

REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS
ARE FAVORABLE FOR SEVERE THUNDERSTORMS IN AND CLOSE TO THE
WATCH AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT
FOR THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER
STATEMENTS AND POSSIBLE WARNINGS. SEVERE THUNDERSTORMS CAN
AND OCCASIONALLY DO PRODUCE TORNADOES.

DISCUSSION...POST FRONTAL CONVECTION EXPECTED TO INCREASE IN
COVERAGE OVER THE NEXT SEVERAL HOURS AS STRONG COLD FRONT
CONTINUES TO UNDERCUT PLUME OF VERY MOIST/UNSTABLE BUT
CAPPED INFLOW ORIGINATING OVER THE SRN PLAINS. WHILE STORMS
SHOULD SHOW AN ELY OR ENELY MOTION...OVERALL CLUSTER/BAND OF
STRONGEST ACTIVITY EXPECTED TO MOVE MORE ESE OR SE WITH TIME.
PRIMARY THREAT WILL BE LARGE HAIL.

...CORFIDI

DONT BE CHEAP AND GOOGLE THE TEXT. IM NOT SURE YOU WOULD GET A RESULT BUT ITS NO FUN THAT WAY.

At relatively the same time they issue the 1300Z Day 1 Convective Outlook. It features an expansive Slight Risk area from Northern Wisconsin back down into the Arklatex region and also extending east from the Mississippi River Valley into Indiana, Kentucky, Tennessee and Northwest Georgia. Good luck trying to pull a target out of that :)

12Z 850 millibar plot (SPC format)
12Z 300 millibar plot (SPC format)
12Z 500 millibar plot (SPC format)
12Z Whole Atmos Storm Relative Helicity
12Z Surface Lifted Index
12Z Central and East Central CONUS radar
12Z National IR Satellite
12Z Central and East-Central CONUS surface plot

Good luck!

...Alex Lamers...
 
I like the NE-EC KS/NW-WC MO area it seems to have a good combination of instability/shear plus an approaching upper-level trof (if I'm even reading the charts right which is always in doubt). The LI and helicity bullseyes in central KS/OK are ironclad capped and/or will be post-fropa by the time of peak heating. I'm kinda iffy on the cap in my area too...I'll probably have a no-storms bust but I think if anything could form in that area it would be severe and possibly tornadic.

At 12Z I'd probably want to be somewhere along or east of the KS/MO border south of Kansas City awaiting the 18Z data. The sattelite data urges me a bit further east into a nice sun-shiny area.

12Z Target: Benton County, MO
 
I respect the cloud trail extending down into northern OK as a trough indicator. While the the dynamics are pretty further north, the advancing cold air is going to clean their clock before too long.

I'm looking for a target with a decent wind profile ahead of the trof, not too far north, and at the leading nose of the mid-upper 60s dews. A little right rear exit divergence in the late afternoon wouldn't hurt, either.

That place is .............. Springfield, MO.
 
I'm starting in Emporia, Kansas until I figure out whether these are just morning clouds or stuff that will hang around all day.
 
I would be favoring the Lamoni IA area right now, but still need some more data before committing too far. I will park it here on I-35 at the Leon IA Highway 2 exit and await more data.
 
I will start in Coffeyville, Kansas and wait for the 18Z data. This also allows me to go north, south, east, west easily if needed (unless I am off by hundreds of miles as usual :lol:).
 
UPDATE: 1630Z

You managed to stop at a truck stop with wifi access wherever you were. Lucky you! You managed to get a hold of the following information...

:arrow: The new 1630Z Outlook is out. Still a broad Slight Risk for portions of the following states...WI, IA, IL, IN, MO, KY, TN, AL, MS, LA, TX, AR and clipping small portions of MN, KS and OK.

:arrow: You managed to get a hold of a surface plot with analyzed fronts per your buddy who decided to skip the chase because he was running out of gas money to split :D Surface plot (click here)

:arrow: Updated IR Satellite Imagery! Click here!

:arrow: Radar image with approximated weather watch locations Click here!

:arrow: Oh yeah there was another watch issued and here's bits and pieces of that...

THE STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

FAR SOUTHEAST IOWA
CENTRAL AND EASTERN ILLINOIS
NORTHEAST AND EAST CENTRAL MISSOURI

EFFECTIVE THIS MORNING AND AFTERNOON FROM 1015 AM UNTIL 300 PM.

HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70
MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE SEVERE THUNDERSTORM WATCH AREA IS ALONG AND 110 STATUTE MILES
EITHER SIDE OF A LINE FROM 35 MILES SOUTHEAST OF COLUMBIA MISSOURI
TO 30 MILES NORTHWEST OF PEORIA ILLINOIS.

DISCUSSION...PRIMARILY ELEVATED CONVECTION WILL CONTINUE DEVELOPING
ESEWD ACROSS WW THROUGH THE MID AFTERNOON. LARGE HAIL WILL BE
PRIMARY THREAT...THOUGH SHEAR WILL BE SUPPORTIVE OF SUPERCELLS. IF
STORMS CAN BECOME ROOTED NEARER BOUNDARY LAYER LATER TODAY ALONG
COLD FRONT...WIND DAMAGE THREAT WOULD INCREASE.

...EVANS

:arrow: In case it helps here's an excerpt from a SWOMCD issued at 16Z for the watch areas and the convective outlook...

SPC MESOSCALE DISCUSSION FOR SE IA/ERN MO/WRN IL
CONCERNING...SEVERE THUNDERSTORM WATCH

NEW STRONG/SEVERE THUNDERSTORMS WILL LIKELY DEVELOP SOUTHEASTWARD
ACROSS THE MIDDLE MISSISSIPPI RIVER VALLEY INTO EARLY AFTENROON.
NEW WW WILL LIKELY BE NEEDED.

AS VIGOROUS COLD UPPER TROUGH OVER THE NORTHERN PLAINS CONTINUES
EASTWARD TOWARD THE UPPER MISSISSIPPI VALLEY...MODELS SUGGEST
STRONGEST UPWARD VERTICAL MOTION FIELD WILL REMAIN ALONG/NORTHEAST
OF WARM FRONT NOW OVER THE LOWER MISSOURI BOUNDARY. BAROCLINIC
ZONE IS GENERALLY ORIENTED NORTH/SOUTH ACROSS WESTERN MISSOURI...
AND WILL DEVELOP EASTWARD INTO THE VICINITY OF THE MISSISSISSIPPI
RIVER BY 18Z...PROVIDING FOCUS FOR MOST INTENSE CONVECTIVE
DEVELOPMENT. LARGE HAIL APPEARS LIKELY TO REMAIN PRIMARY SEVERE
THREAT...ASSOCIATED WITH VERY STEEP MID-LEVEL LAPSE RATES ON FRINGE
OF ELEVATED MIXED LAYER ADVECTING NORTHEASTWARD FROM THE SOUTHERN
HIGH PLAINS. HOWEVER...RAPID SURFACE HEATING OF DRIER AIR MASS ON
COOLER SIDE OF FRONT MAY PROVIDE MORE FAVORABLE ENVIRONMENT FOR
DOWDRAFTS REACHING SURFACE...AND DEVELOPMENT OF SURFACE COLD POOL.

..KERR..

VERY STRONG SHORTWAVE TROUGH AND ASSOCIATED SURFACE COLD FRONT WILL
RAPIDLY MOVE EWD ACROSS THE GREAT LAKES/MID MS VALLEY REGION AND
INTO THE APPALACHIANS...WITH WRN END OF FRONT MOVING RAPIDLY SWD
INTO TX/LOWER MS RIVER VALLEY THROUGH THE PERIOD. COLD FRONT WAS
CURRENTLY MOVING INTO WRN WI/NRN MO/AMD CENTRAL OK...WITH WEAK LOW
CENTER NOW INTO CENTRAL MO.

...

SURFACE-BASED INSTABILITY ATTM REMAINS CONFINED SOUTH OF OUTFLOW
BOUNDARY FROM LEADING CONVECTION...WHICH EXTENDS FROM MIDDLE TN
INTO S-CENTRAL MO. WRN END OF THIS OUTFLOW MAY LIFT NWD AND
SUPPORT MODERATE INSTABILITY AHEAD OF COLD FRONT NWD INTO E-CENTRAL
MO AND SRN IL BY LATE THIS AFTERNOON.

...

A WIND DAMAGE THREAT WILL ALSO
INCREASE LATER TODAY INTO ERN MO AND IL/WRN KY AS COLD FRONT AND
STRONG VERTICAL MOTION SHIFTS RAPIDLY EWD. OTHERWISE...WIDESPREAD
AND SLIGHTLY ELEVATED CONVECTION WILL CONTINUE TO OVERSPREAD THE
WARM SECTOR NORTH OF THE MID MS VALLEY ACROSS THE WRN/SRN GREAT
LAKES REGION.

...

...LOWER TO MID MS VALLEY REGION SWWD INTO TX...
CONVECTION ACROSS THIS REGION SHOULD HOLD OFF UNTIL LATE TODAY AND
CONTINUE OVERNIGHT...AS FRONT UNDERCUTS WEAK CAPPING DUE TO
MODERATE TO STRONG HEATING LATE THIS AFTERNOON. THIS SHOULD
SUPPORT NEAR SURFACE-BASED DEVELOPMENT WITH A THREAT OF SEVERE
WIND/HAIL ALONG THE FRONT INTO AR AND WRN KY/TN LATER TODAY

Hopefully this will get people movin close to their final target locations. Some afternoon data will be released tomorrow.

...Alex Lamers...
 
Hmmmm...I think I underestimated the movement of that low/frontal system. My area has become socked in by clouds, and the sfc winds have veered to SW. I also see what looks like a CU "hotspot" on the IR image in south-central MO invof that warm front.

1630Z: Packing up and pushing SE toward Texas County, MO. Warm front should be pushing through shortly with backed SFC winds and decent warm sector sfc based instability. I've never chased MO for real so no comment on that infamous Ozark terrain...
 
I'm heading toward 50Km South of S. Louis MO along the interstate and I wait for 18Z data.(Edited- I don't like that warm front to the North)
 
I panic - I am out of position, and these cool northwest winds are no good! I take off east out of Emporia as I have underestimated frontal motion and the development of this warm frontal boundary. I am now trying to get to Jefferson City, Missouri, with an eye on needing to potentially be even farther east.
 
I got to this one kind of late........I guess maybe I just slept in too late this day lol.

Assuming I woke up around noon and seen this data, I would like to head to Springfield Illinois. Lots of interstate options from there too if I need them. Although it looks pretty good in the Springfield area later in the afternoon.
 
I have been watching the morning elevated hailers and have now decided to head southeast between Springfield IL and St.Louis where it looks as thought the surface low position will be later this afternoon. I was a bit concerned that things may cap off quickly south of the warm front. So I'll be holding now near Litchfield IL...a spot where supercells notoriously like to blow up on warm front days. I used to live in STL area so am very familiar with the chase area so that helps too.
 
I'm still in Little Rock, looking for a Waffle House. I'm gonna get a double waffle, a double cheeseburger, and a side of bacon. After I eat, I'm gonna hang around and wait. I'm willing to take a chance on surface-based convection, rather than race north into the WW for elevated stuff.
 
As I suspected, the surface front is screaming ese at 25 or 30kts. The satellite shows the surface front through OKC and the developing squall line out ahead trailing down to somewhere east of Shawnee.

It could be an early show along I-40 in eastern OK/western AR but you're either lucky or in the trees, and I probably can't get there in time. I'm going to shoot for the triple-point where the squall-line impulse hits the lollygagging warm front. I'm going to ride US60 east, stopping frequently for data, so the "target" is a little vague; however I'll pick Poplar Bluff, MO at about 2330Z.
 
Well its 1830Z and unfortunately there's not too much additional data available (I can't really find any profilers or special soundings or anything) so here's the updated data that you found at your recent stop.

:arrow: A new radar image with updated watch boxes. A new watch was issued for NE Illinois and E Wisconsin but since nobody is in that area I won't post the text.

:arrow: A new IR satellite image.

:arrow: A new surface map but no analyzed fronts this time.

:arrow: Convergence/Wind barb surface plots for the Upper Midwest and the Southern Plains.

:arrow: Temperature advection/Streamline surface plots for the Upper Midwest and the Southern Plains.

:arrow: A couple of new SWOMCDs discussing potential supercells. Here they are (excerpts) in order of issuance...

CONVECTIVE TRENDS ARE BEING MONITORED. WW WILL LIKELY BE NEEDED
LATER THIS AFTERNOON.

SHARP THERMAL GRADIENT WAS EVIDENT IN 17Z SURFACE ANALYSIS...ALONG
BOUNDARY ENHANCED BY MORNING CONVECTIVE ACTIVITY. THIS EXTENDS
FROM SOUTHEAST MISSOURI...WEST OF CAPE GIRARDEAU...INTO PARTS OF
SOUTHERN MIDDLE TENNESSEE...SOUTH OF NASHVILLE. BOUNDARY WILL
BEGIN TO SHIFT EASTWARD INTO THE LOWER OHIO VALLEY AS 30 TO 40 KT
WEST SOUTHWESTERLY LOW-LEVEL JET DEVELOPS ACROSS THIS REGION

18Z SURFACE DATA INDICATE STRONGEST 2 HOUR PRESSURE FALLS ARE NEAR/
JUST NORTH OF THE ST. LOUIS MO AREA...WHERE RAPID NEW CONVECTIVE
DEVELOPMENT APPEARS POSSIBLE WITHIN THE NEXT COUPLE OF HOURS. MID-
LEVEL CAP WILL LIKELY BREAK BENEATH INCREASINGLY DIFLUENT UPPER
FLOW ON TAIL END OF UPPER MISSISSIPPI VALLEY SHORT WAVE TROUGH.
VERTICAL SHEAR PROFILES ARE SUFFICIENT FOR SUPERCELLS...AND
DAMAGING WIND GUSTS WILL BECOME LARGER THREAT...IN ADDITION TO
POSSIBILITY OF VERY LARGE HAIL...WITH INCREASINGLY SURFACE-BASED
ACTIVITY.

:arrow: Your friend at a local NWS office in the middle of all this tells you there hasn't been a conference call on a new watch yet, but does tell you that the outlook forecaster at SPC is becoming increasingly concerned about the unfolding situation and is weighing upgrading portions of his Slight Risk area to a Moderate Risk at 20Z.

Good luck! Next plethora of info will be either when substantial severe reports come in or at 00Z if nothing happens by then 8) So now would be the time to make your final moves!

...Alex Lamers...
 
Well. 70/59 is not ideal for surface-based instability but there is no need to break the cap by insolation as the front is going to be more than enough to trigger convection. I look for the front to fill in pretty quickly with intense convection so i am going to sit tight here in Carbondale, Illinois
 
I don't know the geography of the area very well as far as whether or not it is conducive for chasing, but I am very attracted to the outflow boundary from west of Cape Girardeau eastward to near Nashville. I would be headed for the area just west of Paducah, expecting that the boundary will advect northeastward with time. Any storms that fire along this boundary will likely be able to utilize the increase shear near the outflow boundary. Also there appears to be a little more juice available for storms in this area verses those farther north due to morning contamination.
 
Well, at 1830Z I'm probably still en route to Texas County, MO because I set up way too far west early in the day, but hopefully I still have a couple hours. Once I get there I'll probably stick around unless the winds veer SW (they are already showing signs of doing so in SC MO) and can head in whatever direction necessary from there. I do like the low LCLs (69/63) along the MS River and the warm front is pretty obviously in there somewhere (81/70 near the MO/AR border).

If I'd stayed home today I would have definitely seen a storm...albiet a crappy, linear one.
 
Mmmmm...I keep on moving southward along I 55 till Sikeston where I've got a road option to go westward and I wait for convection that breaks the cap. I hope that cells will be somewhat isolated.
Nice chase to all guys :wink:
 
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