2017 Spring/Summer Severe Wx Thread

[Niko]

More thunderstorms developing in my area late tonight. Some could be potentially severe!

[Jaycee]

Clocked 2.5" of rain through LNK last night. Looks like it was a narrow band, Omaha didn't get nearly as much. This was much needed as it's been unbearably hot and the drought conditions from the north are trying to creep in. This should help keep it out!

[NEJeremy]

Clocked 2.5" of rain through LNK last night. Looks like it was a narrow band, Omaha didn't get nearly as much. This was much needed as it's been unbearably hot and the drought conditions from the north are trying to creep in. This should help keep it out!

The NWS showed over 6" fell in York.   We only had about .4" at my place in Omaha.

[Niko]

Got drenched earlier this morning again, but things have quieted down quite a bit, thankfully. Its been cloudy, very humid and warm all day. In other words, disgusting feel to the air outside. Feels like I am in Miami.

[Niko]

Next shot of thunderstorms I believe arrive this upcoming Sunday. No storms to speak of IMBY for the next couple of days. We need to let the soil dry up a bit.

[hlcater]

With another relatively impressive heat dome setting up across the plains, models have been hinting at more chances for severe weather over the coming week. In particular, Wednesday has my attention with the GFS continuously advertising some strong MCS potential during the afternoon over portions of MN and N IA over the past several runs. High amounts of instability and an overlapping 80kt 300mb jet could support some severe chances. Still too early to mention much of anything other than that as run to run variability remains high. 

[Tom]

Finally!  Direct hit...storms out here are a bit more wild than back home.  Pack way more gusty winds with the open terrain.  Dust got picked up out ahead of the storm as well.

 

 

 

Severe Thunderstorm WarningSevere Thunderstorm Warning
AZC013-170500-
/O.NEW.KPSR.SV.W.0024.170717T0435Z-170717T0500Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Phoenix AZ
935 PM MST SUN JUL 16 2017

The National Weather Service in Phoenix has issued a

* Severe Thunderstorm Warning for...
Maricopa County in south central Arizona...

* Until 1000 PM MST

* At 934 PM MST, a severe thunderstorm was located over Fountain
Hills, moving south at 35 mph.

HAZARD...60 mph wind gusts.

SOURCE...Radar indicated.

IMPACT...Expect damage to roofs, siding, and trees.

[Tom]

This storm complex has grown in intensity and coverage as it crosses the entire valley. Nearly every neighborhood is getting hit by this line of storms. I haven't seen an electric storm like this one in a while. Just beautiful to see at night.

[Tom]

WSI's model showing a big ticket severe wx day on Wed...

 

 

 

 

SPC only with a Slight Risk thus far...

 

http://www.spc.noaa.gov/products/outlook/day2otlk_0600.gif?1500304216085

[Tom]

I'm worried about real flooding concerns this week across the Ag Belt; centered across IA...high rez GFS has been doing a good job on the overall placement of these convective systems.

 

 

 

 

Nice post by @MDClark....using the MJO analog...

 

 

 

[bud2380]

Iowa has been very interesting this summer.  Some spots are getting too much rain and many others have not had enough.  If I got 5" in the next week as the GFS suggests, that would be very welcome.  But other places even nearby that could be troubling.  I'm hoping I get at least 2-3" out of this.  

[bud2380]

WPC shows the rain staying in northern Iowa or into MN & WI.  The south half of the state that needs it, stays relatively dry

 

http://www.wpc.ncep.noaa.gov/qpf/p168i.gif?1500309520

[bud2380]

12z GFS now in agreement with WPC.  Shows the ring of fire, consistently firing over southern MN.  Forecasting the MCS systems that far out though is extremely difficult.  Hopefully we get one or 2 that meanders further south than models are currently showing.

 

 

http://maps1.pivotalweather.com/maps/models/gfs/2017071712/144/qpf_acc.us_mw.png

[Tom]

I remember the models were wrong on the placement of the heavy rain event that hit N IL last week as they were forecasting it to be across MSN/MKE region.  It ended up being farther south by about 100-150 miles.  I think the same situation will happen again this week.

[Tom]

12z GFS now in agreement with WPC.  Shows the ring of fire, consistently firing over southern MN.  Forecasting the MCS systems that far out though is extremely difficult.  Hopefully we get one or 2 that meanders further south than models are currently showing.

 

 

http://maps1.pivotalweather.com/maps/models/gfs/2017071712/144/qpf_acc.us_mw.png

 

Ya, this is becoming a seriously strong signal for training storms and may become too much of a "good thing"...

[Hawkeye]

The euro also has all the rain north of me, with southern Iowa getting nothing over the next week.  As others have said, sometimes models can underestimate the southward push of storms.  One big MCS with a good south push can affect the rest of the active period.

[Tom]

The euro also has all the rain north of me, with southern Iowa getting nothing over the next week.  As others have said, sometimes models can underestimate the southward push of storms.  One big MCS with a good south push can affect the rest of the active period.

Agreed, FWIW, the Euro hasn't been the best handling the convective placement of these events 2-3 days out.  In fact, its been the GFS PARA and high rez NAM.

[GDR]

?

[NEJeremy]

That slight risk is for Tuesday. Right now SPC only has marginal risk for Wednesday. However, there are some sky high indicies for Wednesday!

 

WSI's model showing a big ticket severe wx day on Wed...

 

 

 

 

SPC only with a Slight Risk thus far...

 

http://www.spc.noaa.gov/products/outlook/day2otlk_0600.gif?1500304216085

 

[Tom]

Flood Advisories out for the same areas in S WI as they were for last week's event...hmmm, let's see how it plays out...

[Niko]

Scattered storms increasing this week in SEMI. As of now, it looks in the "Marginal" category.

[Tom]

Not a good scenario for N IL if these storms materialize...

 

http://www.weather.gov/images/lot/wxstory/Tab3FileL.png

[Tom]

GFS higher rez showing some insane qpf totals in S MN...

 

[NEJeremy]

It's very rare to see a hodograph like this! This is tomorrow near the SD/ND border. Those SRH and shear numbers are INSANE!

[St Paul Storm]

SPC contemplating upgrading some of the enhanced risk area today to moderate. Most of the CAMs are showing a massive MCS rolling through early this evening with widespread wind damage. This may steer just south of the twin cities but we should see something out of this.

[Hawkeye]

Recent runs of the HRRR have actually shifted most of the heavy stuff north and east of the Twin Cities, with very little activity in the enhanced severe area.

[St Paul Storm]

From MPX:

The activity over northern South Dakota is showing little signs of

weakening this morning. Cloud tops have not warmed and there have

been significant severe wind gusts over 75 mph already, meaning

that cluster is beginning to become rooted at the surface.

Therefore, confidence is quickly increasing that this may be the

main show this afternoon. There are generally two ways this could

go.

 

1.) The morning convection over SD does end up weakening. The

RAP/HRRR/NAM continues to favor this solution. In that case, the

threat would shift north with the warm front and end up being a

later event as the LLJ ramps up this evening. Storms would track

along or north of I-94 from mid to late evening.

 

2.) The now much more likely solution per latest trends favors

the NMM/ARW/GFS/ECMWF bringing that line in SD southeastward into

southwest MN by early to mid afternoon. Those models were a little

too far north and a couple hours slow. With the warm front and

instability gradient draped across the southwest corner of MN,

this would likely track along the MN River and south of the metro.

The line would likely maintain its intensity and bring the

potential for widespread wind damage across southern MN. This

severe MCS would clear southern MN by evening leaving uncertainty

with the position of the warm front, but could allow for

additional thunderstorm development this evening somewhere south

of I-94. If these storms don`t grow upscale into an MCS, we could

have training convection with repeated development on the west

end. Excessive rainfall/flash flooding threat would increase

accordingly.

[bud2380]

http://www.spc.noaa.gov/products/md/md1347.html

 

 

DISCUSSION...A cluster of thunderstorms continues moving south and
east across eastern SD around 50 kt and has been producing severe
wind gusts, some significant, the last few hours. Latest radar
trends show indications of a mesoscale convective vortex/bookend
vortex developing over western Kingsbury County that is likely
contributing to the uptick in convective intensity/coverage.
Although a capping inversion remains across the region, and the main
lifting associated with the right-entrance region of the upper jet
streak is lifting farther north away from the east-southeastward
propagating system, rapid destabilization along/south of the warm
front amidst low-mid 70s surface dewpoints is ongoing. Moreover, a
significant cold pool is developing -- a 7-mb pressure jump was
noted at KHON -- that should allow for continuation and
intensification of the system in the next few hours. Given the
expected movement of the current system into MN by 18z, and the
potential for new convective development farther east along the warm
front in IA, a Watch downstream of the current Watch is likely.

[St Paul Storm]

Wow the models really messed up on today's convection. Total bust so far.

[bud2380]

there are currently several Severe t storm warnings and I saw a tornado warning.  Not sure I'd call that a bust.  I assume you are referring to your specific location? 

[Hawkeye]

Yeah, some of the models totally missed the SD MCS holding together all day.

 

The eastward movement earlier this afternoon likely took the Wat/CR/IC corridor out of the path.  Far northeast Iowa should get nailed.

[Tom]

NE IA/S WI/N IL...watch likely soon...

 

http://www.spc.noaa.gov/products/md/mcd1354.gif

[Niko]

No storms here. Sunny with patchy clouds and very humid. DP's are in the low 70s. Unbearable to be outside.

[Tom]

HRRR showing a couple rounds of storms for N IL...first batch by Midnight, second around rush hour tomorrow morning...

 

http://www.tropicaltidbits.com/analysis/models/hrrr/2017071921/hrrr_apcpn_ncus_18.png

[St Paul Storm]

there are currently several Severe t storm warnings and I saw a tornado warning. Not sure I'd call that a bust. I assume you are referring to your specific location?

 

That MCS that formed in SD this morning wasn't predicted to survive and ultimately be the main show today. And it really changed how things played out this afternoon. That's all I'm saying. In terms of warnings, it's been quite a show. In fact, I see 2 more tornado warnings for Rockford and Janesville. That is one hell of a bow structure at the moment.

[BrianJK]

Derecho moving into the area. Also, the training of storms that the models depicted looks to be starting to materialize in SE MN

[St Paul Storm]

Killer light show looking south. Sipping a beer on the deck while watching the best lightning display I've seen in a while. Looks like the line is bumping a bit north. Gonna be a close call whether or not it storms here. The line that has formed in MN looks like it's trying to latch onto the backside of that derecho in IL.

[Tom]

Uh oh, not again...

 

 

 

http://www.weather.gov/images/lot/wxstory/Tab3FileL.png

[Tom]

06z High Rez Nam posing a flooding threat for the same areas that got hit last night...may be some room for a shift south...

 

http://www.tropicaltidbits.com/analysis/models/nam3km/2017072006/nam3km_apcpn_ncus_20.png

[Tom]

Here were the storm reports from yesterday's strong Derecho event...

 

http://www.spc.noaa.gov/climo/reports/yesterday.gif