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March 29-31st Severe Potential


Chicago Storm

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Next potential looks to be just before the close of March. Timing issues are pretty significant at this point, with the GFS being much faster than the ECMWF.

The GFS would pretty much be a one day potential, which doesn't look all that great for the Mississippi Valley area. On the other hand, the ECMWF is likely a two day event on Wednesday and Thursday, with Wednesday having the most potential and likely the highest ceiling for any Plains severe day this year to date.

I'll leave it at that for now...

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Stratus on the Euro looks potentially crippling. Also the LLJ axis is pretty veered and is outrunning the best instability.

I'm not even worried about the cloud cover issues at this point, probably the least of my concerns.

LLJ is an issue...But 850's don't look too bad across KS/NE.

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CIPS analogs strongly favors NE OK/S MO for severe weather on Wednesday. 90% probability for 1 severe report in NW AR/SW MO. Some very well-known events in the package.

 

Note the highest matches aren't all that impressive though. I really don't think Wednesday is going to be that great especially if the timing is faster, there are just too many issues with junk convection/cloud cover and also veering of the low level winds.

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Note the highest matches aren't all that impressive though. I really don't think Wednesday is going to be that great especially if the timing is faster, there are just too many issues with junk convection/cloud cover and also veering of the low level winds.

Well... Leap Day 2012 and March 12, 2006 were some pretty big events. But I'd rather see more analogs that support severe weather than having one major event mixed among some modest/non-event events.

 

But yeah, debris clouds could really throw a wrench in any analog

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The GFS continues to be on the faster side, compared to the slower NAM and ECMWF. The overall threat on it would be much lower and further east.

The NAM looks quite good, especially in KS, with the ECMWF to a lesser degree. The NAM however is likely too high with DP's, as it has been for most events so far this season.

Sounding from the NAM for 0z out of E. KS...

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SGF and TSA don't sound concerned about debris clouds or remnant showers

 

.LONG TERM...(Tuesday Night through Monday)
Issued at 315 PM CDT Mon Mar 28 2016

An upper level low and associate surface low will spread northeast
across the Plains Tuesday night then into southern Minnesota
Wednesday evening. As the system tracks east, large scale lift
will start to develop across Oklahoma and Arkansas early Wednesday
morning and spread north into the Missouri Ozarks and
southeastern Kansas Wednesday morning into the early afternoon
hours. The lift will produce showers and thunderstorms which will
likely be scattered in nature at any given time but with lift
continue to spread north across the area the decent coverage in
rain will occur as scattered storms redevelop through out the
morning into the early afternoon hours. There may be the
potential for hail with a few of the stronger storms in the
morning/early afternoon, but the overall severe risk with this
activity will be low.

The morning/early afternoon storms will spread off to the east and
should see a break in activity during the mid to late afternoon
hours. As the surface low spreads northeast a dry line will spread
east across Kansas late Wednesday afternoon into early Wednesday
evening. Clearing is expected to occur ahead of the dry line and
behind the convection expected early in the day. This clearing
will allow instability to increase late in the day with
additional storms expected to develop along the dry line as it
spreads east into extreme southeastern Kansas and western Missouri
late Wednesday afternoon into the evening hours. Deep layer shear
will be strong with this system and will allow organized updrafts
and the potential for severe weather to occur. Will maintain the
elevated severe weather risk for areas generally along and west of
Highway 65. Storms will continue to spread east across the eastern
Ozarks Wednesday night as the cold front over takes the dry line.
If line segments can develop a severe risk will occur into the
overnight hours and will keep a limit risk for severe storms for
areas generally east of Highway 65 Wednesday night. The showers
and thunderstorms associated with this system should push off to
the east by Thursday morning as the system tracks off to the
northeast.

 

 

 

.DISCUSSION...

After a freeze this morning where FYV set a record low...temps
have rebounded nicely will full insolation. Though not as cool as
last night...our area will still be in close enough proximity to
the surface high with mostly clear skies to allow for temps to
drop off into the 30s and 40s tonight.

South winds increase on Tuesday beneath shortwave ridging aloft
downstream from a large upper low/trough over the western CONUS.
The moisture return should be strong enough to avoid Red Flag
conditions based on current forecast...however there will be an
elevated fire danger across NE OK.

The numerical guidance is now in good agreement in ejecting the
western CONUS upper low/trough across the Plains midweek. Warm
advection storms will likely sweep across portions of the forecast
area early Wednesday in the warm conveyor ahead of the system. By
afternoon...a dryline and cold front will extend S and SW
respectively from a surface low near the mid MO valley. There
should be at least a glancing blow of QG forcing from the
wave...and upper diffluence between the polar and subtropical
jets. Thus...odds are there will be storms east of the
dryline/front Wed afternoon. A combination of moderate instability
and strong vertical shear in the base of the ejecting upper trough
will yield elevated severe storm potential...with all severe modes
possible from rotating storms.

 

 

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At least Wednesday looks like a decent day. GFS has trended somewhat closer to the NAM as far as timing with the dryline/frontal position, and moisture return as well. But the GFS continues to maintain the idea that lingering morning convection will ruin things for later on (like Andy has brought up several times). NAM is still advertising much higher instability (since it does not show as much lingering morning convection), a better wind profile, and higher quality moisture return. All of which have been things it has overdone recently. A blend between the GFS/NAM seems like the best bet at this point to me.

 

Best case scenario to me is for a broken line of severe storms with a variety of storm-modes (supercells/clusters) from E KS into E OK and down into TX in the late afternoon into the evening. As far as a tornado threat goes, we probably are not looking at much of anything, veered low-level winds in the plains almost never bodes well for tornado potential. With that said, if the wind profile the NAM is showing were realized, we could see a somewhat decent tornado threat.

 

IF things do not just change dramatically between now and Wednesday, I would bet on a 5% TOR, 15-30% Hail, and 15% dmgg wind.

 

EDIT: The breadth of the warm-sector could be a concern too.

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0z NAM was still on the slower side and the most robust in 0z guidance. The ECMWF also stayed on the slower side, but is not as impressive as the NAM.

On the other end, the GFS stuck with its faster and much less impressive solution.

We're also getting into range of hi-res guidance...The NMM and ARW are in the middle ground between the faster (GFS) and slower (NAM/ECMWF) sets of guidance.

0z NAM in E. KS...

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The same caveat being held by FWD down here in the Metroplex, extensive cloud cover in the afternoon. They keep mentioning though that if any breaks develop, explosive development is possible along the dryline with a fairly unstable atmosphere and favorable shear profiles to keep cells breathing for a while. 

 

Just a wait and see.

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Wednesday might be a good day to keep it simple and target just east of the surface low in northeast Kansas. Warm front should make it as far north as Iowa, but nah. Morning rain in western Missouri should add an outflow boundary to work with in eastern Kansas. I favor the OFB intersection with dry line. Eastern Kansas should have more instability than points farther north. Moisture return may be impacted by rain farther south, and lingering clouds could delay instability. Still deep layer shear should be adequate though not robust; and, low level shear is forecast to improve somewhat late day. Finally the dry line will not be impacted by the cold front, a nice change. Watch storm motions, esp if they go into the KC Metro. While this is not a travel set-up in my opinion, it is probably a local chase day.

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That forecast 65 degree dewpoint is over done a bit. Might be looking at something closer to 60. If that even. Going to take a lot of moisture advection to get a DP from 30 to 65 in about 24-30 hours. Suppose the 50+ knot overnight LLJ will do the job.

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12z ECMWF is still on the slower side of guidance. It's actually the furthest west with the dry line at 0z. And as like the past few days, the GFS continues to be much faster and with a lower overall threat.

One issue that is showing up more and more is activity across the Arklatex expanding northward into OK/SE. KS/MO during the day now, which could hinder and threat outside of near the SLP.

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00z 4km WRF from SPC looks quite concerning along the I-35 corridor in OK. I definitely haven't bought in just yet, and I haven't taken this threat very seriously at all over the past week. If this turns out to be a significant day, it might be one of the most surprising "anti-busts" I've seen.

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SWODY1 with an enhanced risk ago the Red River on east into the Arklatex, for mostly activity through the day, and especially tomorrow night... With 10% hatched tor in place.

Mentioned concerns of veering 850's in OK and moisture/bouncy issues in NE/KS seems to be preventing any higher probs across those areas.

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A little over an hour out from DSM, trying to figure out if I want to play the triple point feature in NE/IA or the dry line in KS.

In recent years similar setups have yielded overperforming triple points and underperforming dryline setups.  I'd hang tight as long as you can because if the wind fields can get sorted I think there will be opportunities along the I35 corridor...otherwise, I go triple point if I'm you.

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