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Tim from Springfield (IL)

March 26-28 Severe Threat

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25 minutes ago, Chicago Storm said:

Gave the NAM credit too soon...

18z run came in much slower, but still has the best environment across SE IA and W IL during late afternoon into the evening.

3km is laughably slower, with initiation at the KS/MO border at 18z.

Yea not sure I buy this thing slowly that much with initiation that west. Pretty drastic shift. Hrrr makes more sense with timing. I could see a somewhat slower trend and possibly more west of hrrr but nothing like the nam's 

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Forecast sounding near the projected warm front in IA tomorrow from the NAM nest.  Obv this is a difficult-to-believe forecast sounding, but it has to be the most incredible kinematic environment I have ever ever seen.  100+ kt of 0-6 km shear, combined with 500+ J/kg of 0-1 km SRH??? 48 kts of 0-1 km SR flow?  Totally unreal.

 

 

GG.png

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A bit earlier than I was expecting for svr storms this Friday evening.  Patches of clear sky along the I-44 corridor in MO.

Mesoscale Discussion 0238
   NWS Storm Prediction Center Norman OK
   0345 PM CDT Fri Mar 27 2020

   Areas affected...Far northeast Oklahoma...far northern
   Arkasnas...and southwest Missiouri

   Concerning...Severe potential...Watch possible 

   Valid 272045Z - 272245Z

   Probability of Watch Issuance...40 percent

   SUMMARY...Elevated convection is gradually increasing in coverage
   across northeast OK and the AR/MO border. This activity will move
   into southwest MO in the coming hours and will pose a threat for
   large hail as well as gusty winds. Trends will be monitored and a
   watch is possible.

   DISCUSSION...Recent radar trends show gradual new thunderstorm
   development across northeast OK and along the AR/MO border. These
   storms are entering an environment with 50-60 knots of effective
   bulk shear and MUCAPE on the order of 2000-3000 J/kg per SPC RAP
   Mesosanalysis - though these storms are likely being influenced by
   roughly 500-1000 J/kg of CAPE from around the 700 mb level where the
   convection is rooted. This environment has already produced 1-1.75
   inch hail within the past hour, so will to continue to support a
   large hail risk with the strongest storms for the coming 1-2 hours.
   Additionally, 6-7 C/km low level lapse rates will continue to
   support a risk for strong winds. 

   Although the environment is supportive of convective development,
   storm longevity is uncertain and it remains unclear whether these
   storms will be able to become rooted in the boundary layer, which
   would prolong the severe risk. Trends will continue to be monitored
   and a watch may be needed if it becomes clear that storms are
   becoming surface-based.
 

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ILX wanted no part of discussing it, here's DVN disco

 

Quote
Saturday morning...The MO warm front starts to retreat northward
possibly into the southern CWA by late morning, but still hindered
in progression by east-northeast 10-20 MPH post frontal LLVl flow.
As the sfc low deepens toward 990 MB and rolls to near Omaha by
noon, see a scenario where we still have to deal with sctrd
elevated storms north of the warm front for much of Sat morning,
and a lingering chance for hail and localized heavy downpours.
Then the attention turns to...

Saturday afternoon...Closed upper low deepening close to 540 dam over
northwest IA by evening, but models still don`t suggest it to
negatively tilt. Still a dynamic synoptic scale scenario as 150 KT
upper jet rounds the bend and "exit region noses" right acrs the DVN
CWA by late afternoon. Much will depend on the northward extent the
warm front makes it to allow portion of warm moist sector with low
to mid 60 sfc DPTs to skirt acrs the southeast half or more of the
fcst area(how far northwest will it make it?), and timing of
southwest LLVL flow surge from approaching dry slot with dry-line
like effects on it`s advancing edge, to fuel a developing line of
broken generally north to south oriented storm cells/supercells
somewhere acrs the CWA. How far east this occurs, how far north the
warm front makes it, all questions and lingering uncertainty. Deep
mainly southwest speed shear profiles of 70-90+ KTs are troubling,
but back LLVLs for tornadic or funnel development to the sfc may not
be there except when encountering the warm front or other
discontinuity boundaries. With such strong flow profiles,the storms
will be very fast moving over 50 KTs and thus short residence
windows when encountering boundaries. This may make for more short-
lived tornadoes, as opposed to long trackers.

If there are too many cells in a broken line, see the scenario where
community outflow boundaries merge and act as inflow interrupters,
decreasing more lengthy severe threats. But more discrete and
separated cells will still be trouble, it not for a tornado still
able to produce damaging wind gusts and large hail with rear dry
slot interaction. One other question, looking at fcst vertical
profiles and soundings there appears some lack of more robust CAPE
and depth to fuel such high shear profiles. Have scene another
similar scenario several years ago in a high risk window where the
shear was too much/not enough deep CAPE and tore storms apart before
they could better organize. Many questions and uncertainty ongoing,
but still have to respect the rare Moderate risk in portions of our
area tomorrow. Trusted old fashion 12z run MCS tool with it`s
tornadic shear profile is targeting SPC`s Moderate bullseye really
well, but wonder if a bit more southeast adjustment may be warranted
in later updates.

High temps well up in the 60s to mid 70s possible in heart of the
afternoon dry slot-warm sector, and as for rainfall, the afternoon
cells will look to be scattered and very fast moving limiting
dumping too much rain in a spot for a period of time despite ongoing
high PWATs of 1 to 1.4 inches. The heavier rain threat may be in the
north half of the CWA Sat morning with storm clusters still north of
the retreating(or trying to retreat) warm front. Over all, tonight
and Sat 24 hour rainfall amounts now look to be lower, with
widespread 0.50 to 1 inch amounts by 00z Sunday, some areas less.
But the high PWATs also support a few localized swaths of 1-2 inches
acrs areas that can get in on repeat thunderstorm clusters, such as
along a temporary stalled warm front scenario late tonight into Sat
morning.

Behind passing storms, southwest dry slot winds may gust close to
advisory level late afternoon into early evening.


.LONG TERM...(Saturday Night through next Friday)
ISSUED AT 330 PM CDT Fri Mar 27 2020

Key Messages:

1. Severe thunderstorms should be ending across the area at the
beginning of the period.

2. Wind gusts to 50 mph could be possible Saturday night into
Sunday.

3. There are additional chances for precip late in the period.

Discussion:

Ongoing severe thunderstorms are likely at the beginning of the
period.  Most of these storms will likely be in the eastern CWA and
exiting.  Supercells are expected with all potential threats of
severe weather.

On the backside of this system, strong advection of pressure
gradient will lead to winds sustained 25 to 35 mph with gusts as
high as 50 mph.  Expect this to peak sometime in the morning before
waning off by the afternoon.  We will likely need a wind advisory
for these winds.

After this period, expect temperatures in the 40s with rather quiet
weather.  Into next week, model momentum fields vary much and thus
lead to low confidence in possible systems.  As such, we have a
period of extended pops in the long term forecast.  As we get closer
to the event, expect the actual window for pops to get smaller.

&&

 

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The hailers mean business this Friday evening.

BULLETIN - EAS ACTIVATION REQUESTED  
SEVERE THUNDERSTORM WARNING  
NATIONAL WEATHER SERVICE TULSA OK  
357 PM CDT FRI MAR 27 2020  
  
THE NATIONAL WEATHER SERVICE IN TULSA HAS ISSUED A  
  
* SEVERE THUNDERSTORM WARNING FOR...  
  SOUTHEASTERN CRAIG COUNTY IN NORTHEASTERN OKLAHOMA...  
  NORTHERN DELAWARE COUNTY IN NORTHEASTERN OKLAHOMA...  
  SOUTHEASTERN OTTAWA COUNTY IN NORTHEASTERN OKLAHOMA...  
  NORTHEASTERN MAYES COUNTY IN NORTHEASTERN OKLAHOMA...  
  
* UNTIL 430 PM CDT.  
  
* AT 357 PM CDT, A SEVERE THUNDERSTORM WAS LOCATED OVER CHEROKEE  
  STATE PARK, MOVING NORTHEAST AT 80 MPH.  
  
  HAZARD...TENNIS BALL SIZE HAIL.  
  
  SOURCE...RADAR INDICATED.  
  
  IMPACT...PEOPLE AND ANIMALS OUTDOORS WILL BE INJURED. EXPECT   
           DAMAGE TO ROOFS, SIDING, WINDOWS, AND VEHICLES.  
  
* LOCATIONS IN OR NEAR THE PATH INCLUDE...  
  JAY...                            GROVE...  
  LANGLEY...                        BERNICE...  
  KETCHUM...                        SPAVINAW...  
  DISNEY...                         BIG CABIN...  
  PENSACOLA...                      HOOT OWL...  
  HONEY CREEK STATE PARK...         CHEROKEE STATE PARK...  
  BERNICE STATE PARK...             SPAVINAW STATE PARK...  
  CLEORA...                         CHLOETA...  
  STRANG...                         DISNEY LITTLE BLUE STATE PARK...  
  ZENA...                             
  
THIS INCLUDES INTERSTATE 44 BETWEEN MILE MARKERS 274 AND 276.  
   
PRECAUTIONARY/PREPAREDNESS ACTIONS...  
  
THIS IS A DANGEROUS STORM. PREPARE IMMEDIATELY FOR LARGE DESTRUCTIVE  
HAIL CAPABLE OF PRODUCING SIGNIFICANT DAMAGE. PEOPLE OUTSIDE SHOULD  
MOVE TO SHELTER INSIDE A STRONG BUILDING,  AND STAY AWAY FROM  
WINDOWS.  
  
  

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28 minutes ago, Indystorm said:

The hailers mean business this Friday evening.

BULLETIN - EAS ACTIVATION REQUESTED  
SEVERE THUNDERSTORM WARNING  
NATIONAL WEATHER SERVICE TULSA OK  
357 PM CDT FRI MAR 27 2020  
  
THE NATIONAL WEATHER SERVICE IN TULSA HAS ISSUED A  
  
* SEVERE THUNDERSTORM WARNING FOR...  
  SOUTHEASTERN CRAIG COUNTY IN NORTHEASTERN OKLAHOMA...  
  NORTHERN DELAWARE COUNTY IN NORTHEASTERN OKLAHOMA...  
  SOUTHEASTERN OTTAWA COUNTY IN NORTHEASTERN OKLAHOMA...  
  NORTHEASTERN MAYES COUNTY IN NORTHEASTERN OKLAHOMA...  
  
* UNTIL 430 PM CDT.  
  
* AT 357 PM CDT, A SEVERE THUNDERSTORM WAS LOCATED OVER CHEROKEE  
  STATE PARK, MOVING NORTHEAST AT 80 MPH.  
  
  HAZARD...TENNIS BALL SIZE HAIL.  
  
  SOURCE...RADAR INDICATED.  
  
  IMPACT...PEOPLE AND ANIMALS OUTDOORS WILL BE INJURED. EXPECT   
           DAMAGE TO ROOFS, SIDING, WINDOWS, AND VEHICLES.  
  
* LOCATIONS IN OR NEAR THE PATH INCLUDE...  
  JAY...                            GROVE...  
  LANGLEY...                        BERNICE...  
  KETCHUM...                        SPAVINAW...  
  DISNEY...                         BIG CABIN...  
  PENSACOLA...                      HOOT OWL...  
  HONEY CREEK STATE PARK...         CHEROKEE STATE PARK...  
  BERNICE STATE PARK...             SPAVINAW STATE PARK...  
  CLEORA...                         CHLOETA...  
  STRANG...                         DISNEY LITTLE BLUE STATE PARK...  
  ZENA...                             
  
THIS INCLUDES INTERSTATE 44 BETWEEN MILE MARKERS 274 AND 276.  
   
PRECAUTIONARY/PREPAREDNESS ACTIONS...  
  
THIS IS A DANGEROUS STORM. PREPARE IMMEDIATELY FOR LARGE DESTRUCTIVE  
HAIL CAPABLE OF PRODUCING SIGNIFICANT DAMAGE. PEOPLE OUTSIDE SHOULD  
MOVE TO SHELTER INSIDE A STRONG BUILDING,  AND STAY AWAY FROM  
WINDOWS.  
  
  

Yep

hailer.JPG

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My parents house wasnt even under a marginal risk in southwest missouri today, and they got golfball sized hail. 

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It's seriously embarrassing what ILX does. They always refer to SPC discussion. Like do your own analysis. DVN was uncharacteristically conservative. LOT great as always. Not sure what the other offices aren't seeing

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27 minutes ago, StormChaser4Life said:

It's seriously embarrassing what ILX does. They always refer to SPC discussion. Like do your own analysis. DVN was uncharacteristically conservative. LOT great as always. Not sure what the other offices aren't seeing

I mean, you could always try and go work for them then.

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40 minutes ago, StormChaser4Life said:

It's seriously embarrassing what ILX does. They always refer to SPC discussion. Like do your own analysis. DVN was uncharacteristically conservative. LOT great as always. Not sure what the other offices aren't seeing

I don't know anything behind ILX's discussion, but from my own experience, if I agree with SPC I'm going to refer you to it. It saves me time and allows me to focus on other things that need to be done. Now, if I disagree, I might spend more time discussing it. Either way some people are more verbose than others. (There was a time when AFDs had a 30 line limit, max.)

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SPC just updated the day 1 outlook to expand the slight risk farther south in IL/IN and to add a hatched hail area.

Quote

DAY 1 CONVECTIVE OUTLOOK AMEND 1  
NWS STORM PREDICTION CENTER NORMAN OK  
0600 PM CDT FRI MAR 27 2020  
 
VALID 272000Z - 281200Z  

 
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM EASTERN  
KANSAS INTO A PORTION OF THE MIDWEST...  
 
AMENDED TO EXPAND SLGT RISK CATEGORY FARTHER SOUTH INTO THE MO, IL  
AND IN FOR LARGE HAIL  
   
..SUMMARY
 
 
SEVERE THUNDERSTORMS WITH MAINLY LARGE HAIL WILL CONTINUE FROM  
SOUTHERN MISSOURI INTO SOUTHERN ILLINOIS AND INDIANA THIS EVENING.  
OTHERWISE, SEVERE THUNDERSTORMS CAPABLE OF MAINLY LARGE HAIL REMAIN  
POSSIBLE TONIGHT FROM EASTERN KANSAS ACROSS PARTS OF THE MIDWEST.  
   
..DISCUSSION
 
 
PRIMARY CHANGE TO THIS AMENDMENT HAS BEEN TO EXPAND THE SLGT RISK  
CATEGORY FARTHER SOUTH INTO SOUTHERN MO, SOUTHERN IL AND IN TO  
REFLECT EXPECTED EASTWARD DEVELOPMENT OF A CLUSTER OF SUPERCELLS  
THAT HAS A HISTORY OF PRODUCING VERY LARGE HAIL.  
 
..DIAL.. 03/27/2020  

swody1_categorical.png

swody1_hailprob.png

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Think I'm gonna cover the car windows tonight.  Been a little concerned since this morning about some hailers coming through in the wee hours early tomorrow as that warm front approaches. :weenie:

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There has been a subtle trend from a model consensus of slightly slower/southwest. I think northern (possibly central) Missouri may be in play here more so than areas north of DVN.

The HRRR is not backing down. In terms of warm sector moisture quality, the latest HRRR brings 67F dews to I-70 in Missouri by 15z. Assuming that warm sector is largely undisrupted, the result is impressive low-level moisture and instability for such a kinematic environment. 

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1 hour ago, andyhb said:

I mean, you could always try and go work for them then.

No need for your sarcasm. Just saying given the parameters I am seeing and the potential I don't think they're hitting the tornado potential as hard as they should. Yes there is bust potential as with any setup but I can name more positive than negative aspects with this. These storms will be in some populated areas, more so than any setup so far this year and I just hope people understand the potential of this to produce strong to potentially violent tornadoes. I'm not saying I'm better than any NWS forecaster but I do think they been quite conservative and that concerns me. 

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6 minutes ago, StormChaser4Life said:

No need for your sarcasm. Just saying given the parameters I am seeing and the potential I don't think they're hitting the tornado potential as hard as they should. Yes there is bust potential as with any setup but I can name more positive than negative aspects with this. These storms will be in some populated areas, more so than any setup so far this year and I just hope people understand the potential of this to produce strong to potentially violent tornadoes. I'm not saying I'm better than any NWS forecaster but I do think they been quite conservative and that concerns me. 

This is just conjecture on my part, but I always think it is better to err on the conservative side and then ramp up than vice versa.  I always think of "day of" outlooks as being the most helpful,so I will be waiting for the day one outlook later tonight.  True, with all the attention on Covid 19 I would want the media to make sure people in the affected areas are aware of the danger.  In fact, when a situation looks promising I usually have a little game of asking myself....Ok, what could go wrong with this?

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31 minutes ago, Quincy said:

There has been a subtle trend from a model consensus of slightly slower/southwest. I think northern (possibly central) Missouri may be in play here more so than areas north of DVN.

The HRRR is not backing down. In terms of warm sector moisture quality, the latest HRRR brings 67F dews to I-70 in Missouri by 15z. Assuming that warm sector is largely undisrupted, the result is impressive low-level moisture and instability for such a kinematic environment. 

Definitely noticing that on the nams. My question is if that was right, would they start producing right away or further east? Winds are more backed east. Curious to see if hrrr caves towards that or holds firm

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18z NAM valid at 00z Sunday has the triple point southwest of 12z ECMWF, 18z GFS too quick and east as usual, and 18z HRRR is to the northeast. HRRR generally agrees with ECMWF's triple point location earlier at 18z, but has the warm front farther north and the southern portion of the cold front in Missouri southward further east. HRRR looks like it's being too quick and northeast with the system by 00z. Feels like the ECMWF is a happy medium right now, but anything can happen.

Problem with Missouri being in play for tornadoes are the mainly linear hodographs. Doesn't mean there can't be tornadoes, but makes the storm mode messy with storm split interactions. I've even seen some forecast hodographs in northeast Missouri and southeast Iowa with a s-shaped wind profile in the 0-2 km layer. Those locations are in the 10% hatched for tornadoes, but I'm not all that confident about that. Waiting on the 00z updates now.

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2 hours ago, StormChaser4Life said:

It's seriously embarrassing what ILX does. They always refer to SPC discussion. Like do your own analysis. DVN was uncharacteristically conservative. LOT great as always. Not sure what the other offices aren't seeing

IMO, even the wording of both the local area forecast for Sangamon County and their point-and-click for my location (Chatham, IL) both make it appear that ILX doesn't seem impressed about this storm threat, at least for this area.  

Their current Sangamon County forecast for tomorrow: "Warmer. Rain showers and thunderstorms."  No mention of severe yet.  Point and click only shows the generic "showers and thunderstorms" with no severe mention either.  That doesn't sound like "enhanced/moderate risk for severe" to me. 

It was worse earlier today: "Rain showers and some thunderstorms."  That especially doesn't scream "severe" to me; more like a "few showers with a rumble of thunder or two."

Either ILX's forecasting is a joke, or they're seeing something for this area that we and the other models/NWS offices are not.

I'm sure tomorrow's morning ILX HWO will have the "conference call for emergency managers" statement at the end of the outlook, for sometime late in the morning for areas in at least the Enhanced risk.  Maybe even some of the Slight areas too.

Also, how much stock does anyone on here take in local TV weathercast "Futurecast radars."  None of the ones I've seen on the three major newscasts in the Springfield/Decatur/Champaign market at 6PM seemed to put much activity (other than a few isolated cells) in the current MDT/hatched TOR area.  It looked as if they wanted to get more isolated storms going roughly along and east of a STL-LaSalle line, with some intensifying and expanding in size.  Not impressed with what I saw on local news tonight, even though they were emphasizing SPC's moderate risk prediction.

 

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25 minutes ago, twistingtornado said:

18z NAM valid at 00z Sunday has the triple point southwest of 12z ECMWF, 18z GFS too quick and east as usual, and 18z HRRR is to the northeast. HRRR generally agrees with ECMWF's triple point location earlier at 18z, but has the warm front farther north and the southern portion of the cold front in Missouri southward further east. HRRR looks like it's being too quick and northeast with the system by 00z. Feels like the ECMWF is a happy medium right now, but anything can happen.

Problem with Missouri being in play for tornadoes are the mainly linear hodographs. Doesn't mean there can't be tornadoes, but makes the storm mode messy with storm split interactions. I've even seen some forecast hodographs in northeast Missouri and southeast Iowa with a s-shaped wind profile in the 0-2 km layer. Those locations are in the 10% hatched for tornadoes, but I'm not all that confident about that. Waiting on the 00z updates now.

Yea that was my concern. Directional shear not as good west so storms could struggle till they got more east but would they get too messy before getting to the better environment? Plus MO is just not chasing friendly so definitely prefer the threat further east. I do agree HRRR is probably too fast but NAM seems too slow. 0z HRRR running now. Let the fun begin

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HRRR still a high end event with what looks like two lines of convection....

 

2nd over eastern/northeast IA at triple point and develops a spoke into central IL again after a first round

 

 

 

 

 

 

 

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2 minutes ago, Hoosier said:

00z HRRR doesn't look like it's going to be in the excessively slow camp.

There may be a slight SW nudge, but if I’m looking at the data correctly, it looks like the occlusion process is slower/delayed. 

Testing this image embed:

NEXLABdpdt-20Z-20200328_HRRRMW_sfc_theta

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Those UH tracks on the 0Z HRRR are gnarly. They're also expanding at a rate of 65 mph.

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