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2018 Short to Medium Range Severe Thread


tornadohunter

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I have some optimism for Sunday.  Nice EML plume on the models and plenty of moisture leading to potentially strong instability, and perhaps just enough shear/low level turning near the warm front from IN into OH for supercells.  It looks like a shortwave might glance the region late in the day and allow stuff to develop.  Not a slam dunk setup but hey it’s getting desperate here.  

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14 hours ago, HillsdaleMIWeather said:

Newer runs are trying to push it back til Monday

umm no? That's a separate event. I'm talking west for IA and MO. The Sunday event and maybe monday?(idk it looks like garbage to me) are different setups on different days that just happen to involve the same boundary. The NAM/GFS have backed off a bit for Saturday, but still looks okay.

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Some of the soundings for sunday along the warm front are encouraging. Mid level flow is a little weaker than ideal but 40-45 kts would get the job done. Excellent turning from 0-1 with good speed shear. It looks chasable to me. 

 

2018051812_NAM_060_40.86,-88.31_severe_ml.png

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Day 3 has a marginal area from parts of MO/IA to W OH.

Quote

Day 3 Convective Outlook 
   NWS Storm Prediction Center Norman OK
   0137 AM CDT Fri May 18 2018

   Valid 201200Z - 211200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
   OF THE MIDWEST/OH VALLEY...

   ...SUMMARY...
   Strong storms may develop across portions of the Midwest and Ohio
   Valley region Sunday.

   ...Midwest/OH Valley...

   Central Plains short-wave trough is expected to induce a
   considerable amount of convection across portions of the central
   Plains/Lower MO Valley late Saturday. Remnants of this activity
   should propagate into IA/northern MO by the start of the day3
   period. While it's not entirely clear how much influence this
   activity will have on the boundary layer, in all likelihood one or
   more surface boundaries should serve as the focus for renewed
   development by early afternoon. Latest thinking is multiple
   clusters/MCS should be ongoing at the start of the period along nose
   of a pronounced LLJ. Downstream boundary-layer heating will
   contribute to destabilization that is expected to aid robust
   thunderstorm development during the afternoon. While mid-level
   heights may be somewhat ridgy, aforementioned convective influences
   should encourage potentially strong thunderstorm development.
   Hail/wind are the primary threats with convection that spreads
   toward the OH Valley.

   ..Darrow.. 05/18/2018

 

day3otlk_0730.gif

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1 hour ago, largetornado said:

Some of the soundings for sunday along the warm front are encouraging. Mid level flow is a little weaker than ideal but 40-45 kts would get the job done. Excellent turning from 0-1 with good speed shear. It looks chasable to me. 

 

 

I think that is contaminated. If you look at reflectivity(or MSLP) on the 12z NAM, you'll see that the NAM has a pretty significant looking MCS barreling down the warm front at 00z. All the soundings pulled ahead of this MCS(adjacent counties) are likely influenced by the convectively induced area of low pressure associated with the complex. This locally enhances wind profiles in the inflow region immediately in front of the MCS. The sounding I included is east of Champaign, and is probably more representative of the warm frontal environment on the NAM, which is still sufficient if you ask me.

EDIT: that large area of subsidence from 850-500mb may also key into this area being an inflow region, however I am not sure on that one.

sfcwind_mslp.us_mw.png

 

nam_2018051812_060_40.21--87.88.png

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I'll take Slight Risk for $400, maybe even ENH for say $200. Hoosier Alley Sunday forecasts have trended slightly better for chasing/enthusiast concerns. The 12Z NAM high-res radar simulation is notable at 60 hours, but in 2018 too good to be true. Still, evidence supports giving Sunday a chance.

Surface looks to have adequate 68+ dewpoints, in contrast to the Plains struggling to 65 and mixing out to 60. Upstream over the South is humid, along with soundings up to 850 mb. Forecast soundings for ILX/IND look to hold moisture for Sunday. 850 mb/LLJ is a little veered, but not enough to kill the deal in Hoosier Alley. 925 mb may be less veered. An outflow boundary would locally enhance helicity enough to overcome the LLJ orientation. 700 mb looks just right temps. GFS is backing of all the midday rain, more in line with ECMWF and its parallel. 500/200 mb forecasts remain modest shear, plenty enough for May. However that forecast has to hold up. 

I am looking for any outflow boundary to stay north of I-70 out of the jungle, preferably north of I-74. Upper jet needs to hang in there. LLJ I'd like slightly stronger and/or less veered. If things can line up, Sunday could offer a severe weather surprise for Hoosier Alley.

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I still think Sunday has potential for some supercells and perhaps a couple of tornadoes along the wf in IL and IN, but am less enthused for OH and probably can’t get as far west as I’d need to on Sunday.  Parameter space supports an eventual slight risk at least once the finer details start sorting out. 

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New day 2 now has a slight risk area from C MO to SW OH.

Quote

 Day 2 Convective Outlook 
   NWS Storm Prediction Center Norman OK
   1229 PM CDT Sat May 19 2018

   Valid 201200Z - 211200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
   THE MID-MISSISSIPPI AND LOWER OHIO VALLEYS...

   ...SUMMARY...
   Strong to severe storms may develop across portions of the Midwest
   and Ohio Valley region Sunday. Additional strong storms are possible
   across portions of central Texas.

   ...Midwest/Ohio Valley Vicinity...

   A somewhat complex forecast scenario is expected for Sunday, mainly
   due to possible impacts from overnight convection in the Day 1
   period and any ongoing storms Sunday morning. That being said, ample
   opportunity for strong to severe storms will exist along a myriad of
   surface boundaries. A cold front will be positioned along the MO/KS
   border early in the afternoon with a weak surface low over northwest
   MO. The front will then extend west to east across northern MO into
   central IL/IN/OH. Strong heating to the south of the boundary, with
   dewpoints in the mid to upper 60s, will result in strong
   destabilization across portions of the Mid-MS and lower OH Valleys.
   Midlevel lapse rates, while not impressive, will be adequate when
   coupled with strong instability for maintaining stronger updrafts.
   0-6km shear will be generally weak across the region in the absence
   of stronger deep layer forcing for ascent. However, portions of the
   region will be on the southern fringes of narrow corridor of
   stronger bulk shear located over the Great Lakes and values ranging
   from around 25-35 kt appear reasonable at this time.  All of this
   together should support storms capable of severe hail. Furthermore,
   steep low level lapse rates and weak low level flow likely will
   favor outflow dominant convection. As such, damaging winds will be
   possible with some potential for upscale growth into one or more
   bowing segments should stronger cold pools become established.

   ...Portions of Central Texas...

   Severe potential across central TX also is somewhat uncertain due to
   expected ongoing convection moving south/southeast toward the region
   at the beginning of the period. The timing of this convection and
   position of any related outflow boundary will impact where strong to
   possibly severe storms may develop during the afternoon. Warm, moist
   advection ahead of the boundary should result in scattered storm
   development. Deep layer shear will remain weak, but modestly steep
   midlevel lapse rates and moderate instability will be adequate for
   at least brief intense updrafts capable of hail. Some stronger wind
   gusts also will be possible as storms struggle to maintain
   intensity/organization.

   ...MAXIMUM RISK BY HAZARD...
   Tornado:   2%     - Marginal
   Wind:     15%     - Slight
   Hail:     15%     - Slight

   ..Leitman.. 05/19/2018

 

day2otlk_1730.gif

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57 minutes ago, cyclone77 said:

Pretty benign looking pattern for meaningful severe for the foreseeable future.  Hopefully June makes up for a very meh May.

It has been an incredibly boring storm season in my yard.  Some locations have had good storms, but there has been nothing widespread, leaving some of us with very little.

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3 hours ago, hawkeye_wx said:

It has been an incredibly boring storm season in my yard.  Some locations have had good storms, but there has been nothing widespread, leaving some of us with very little.

It's been a very strange stretch of weather from March through now.  Spring snows, and now this weird stagnant/constipated split flow BS.  Hopefully June makes up for it by featuring May flow over June instability.  That could be fun.

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New day 2 introduces a slight risk for C IN/ W OH.

Quote

Day 2 Convective Outlook 
   NWS Storm Prediction Center Norman OK
   1230 PM CDT Sun May 20 2018

   Valid 211200Z - 221200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER A PORTION OF
   THE OHIO VALLEY...

   ...SUMMARY...
   A few strong to severe thunderstorms are possible across the Ohio
   Valley as well as the southern Rockies Monday.

   ...Synopsis...

   Omega blocking pattern will persist Monday with an upper low closing
   off over CA and NV. Farther downstream a shortwave trough will crest
   the mean ridge position over the Plains and mid MS Valley region,
   and this feature will continue east through the OH Valley and Great
   Lakes. At the start of the period a quasi-stationary or warm front
   is forecast to extend from the Middle Atlantic westward to a weak
   surface low over IL. A cold front should extend southwest from the
   low through the lower MS Valley and central TX.

   ...Ohio Valley region...

   Elevated showers and storms may be ongoing over the northern portion
   of the OH Valley into the Great Lakes within zone of warm advection
   and isentropic lift north of the warm front. South of this boundary
   clouds should erode with diabatic heating and a moist surface layer
   (upper 60s F dewpoints) resulting in 1500-2000 J/kg MLCAPE during
   the afternoon. Weak convective inhibition should promote the
   development of storms along and in advance of the weak cold front as
   the boundary layer destabilizes. A belt of stronger (30-40 kt from
   700-500 mb) winds aloft will overlap the northern portion of the
   warm sector, but weak effective bulk shear an unidirectional winds
   will promote mostly multicell storm modes including bowing segments.
   An exception will be if enough destabilization can occur along warm
   front where backed low-level winds may augment low-level hodograph
   size and contribute to sufficient effective bulk shear for marginal
   supercell structures. Primary threat is expected to be strong to
   damaging wind gusts during the afternoon into the early evening, but
   a tornado or two cannot be ruled out. 

   ...Southern Rockies through Southern High Plains...

   Modest southwesterly winds aloft will become established over the
   higher terrain as upper low settles over southern CA into western
   AZ. Southeasterly low-level winds will result in low to mid 50s F
   dewpoints advecting through the High Plains beneath steep mid-level
   lapse rates contributing to a corridor of moderate instability with
   1500 J/kg MLCAPE. Storms will likely develop over the higher terrain
   during the afternoon and subsequently spread east into the High
   Plains. Multicell storm modes should be the dominant storm type,
   with some storms possibly evolving into clusters/lines as cold pools
   congeal. Moderate instability and steep lapse rates with inverted-V
   boundary layers will promote a risk for isolated downburst winds,
   but hail will also accompany the stronger storms.

   ...MAXIMUM RISK BY HAZARD...
   Tornado:   2%     - Marginal
   Wind:     15%     - Slight
   Hail:      5%     - Marginal

   ..Dial.. 05/20/2018

 

day2otlk_1730.gif

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15 hours ago, cyclone77 said:

It's been a very strange stretch of weather from March through now.  Spring snows, and now this weird stagnant/constipated split flow BS.  Hopefully June makes up for it by featuring May flow over June instability.  That could be fun.

This.   We need some 990mb systems to augment that low level jet which we have had a dearth of this spring here in the Midwest.

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Would love to have something sort of worth chasing in OH/IN/perhaps IL before I move to NJ in early July.  Pattern looks horrible through at least the rest of May.  Blah. Almost getting a 2012 vibe to the pattern with a warm but very quiet look coming up. 

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1 hour ago, Hoosier said:

This season as a whole is sorta reminiscent of some of those paltry 1980s years.

I found this graph/chart interesting. It is only active tornado days in Kansas, but with there seems to be a clear oscillation in activity in the limited data set we have.

unknown.png?width=938&height=677

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2 hours ago, OHweather said:

Would love to have something sort of worth chasing in OH/IN/perhaps IL before I move to NJ in early July.  Pattern looks horrible through at least the rest of May.  Blah. Almost getting a 2012 vibe to the pattern with a warm but very quiet look coming up. 

Yes, this stubborn pattern has got to go.  If we can get some decent shear tomorrow maybe we can get something to sneak in before you leave!  

Good luck to you.  Hope you'll still post your thoughts around here from time to time.  Always enjoyed your insight!:thumbsup:

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EF0 confirmed from last night just south of Wilmington OH.

Quote

US National Weather Service Wilmington OH

19 mins ·

NWS storm survey team in Brown County determined that an EF0 tornado touched down north of Mount Orab and was on the ground for approximately one mile. More specific details will follow later today when the team returns and prepares their more detailed report.

 

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On 5/21/2018 at 12:32 AM, Jackstraw said:

Yes, this stubborn pattern has got to go.  If we can get some decent shear tomorrow maybe we can get something to sneak in before you leave!  

Good luck to you.  Hope you'll still post your thoughts around here from time to time.  Always enjoyed your insight!:thumbsup:

This spring for severe weather sucks. Crappy trough in central and east throughout March and much of April straight to a huge pattern flip with jet stream way north. Similar to may 2012 for sure

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Most of Ohio in a slight risk now for today.

Quote

 Day 1 Convective Outlook 
   NWS Storm Prediction Center Norman OK
   1128 AM CDT Tue May 22 2018

   Valid 221630Z - 231200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE
   UPPER OHIO VALLEY AND THE MID-ATLANTIC REGION...

   ...SUMMARY...
   Isolated strong to severe thunderstorms are forecast mainly this
   afternoon and evening across parts of the Mid-Atlantic States and
   Ohio Valley, as well as over portions of the High Plains and
   north-central Rockies.

   ...Upper Ohio Valley...
   Visible imagery indicates thinning cloud cover over Indiana and much
   of Ohio which will permit stronger diabatic heating and air mass
   destabilization to occur this afternoon, in advance of a
   southeastward moving cold front located from extreme northwest Ohio
   into southwest Indiana.  The decrease in cloud cover will spread
   into western Pennsylvania with time and contribute to a gradual
   increase in heating.  MLCAPE is expected to reach 1000-1500 J/kg,
   with greater instability expected with westward extent. 

   Short bands of mainly shallow convection are developing along/ahead
   of the front from northwest Ohio into east central Indiana.
   Updrafts within this activity are expected to strengthen with
   several bands of northeast-southwest oriented thunderstorms forming
   by early-mid afternoon.  The storms will be located on the southern
   edge of stronger westerly winds aloft, including the right entrance
   region of an upper level jet, resulting in deep layer shear of 30-40
   kt that will enhance storm organization and intensity.  Stronger
   cells will be capable of producing damaging wind gusts with isolated
   hail also possible mainly with any storms that are able to develop
   transient updraft rotation.  The activity will spread eastward and
   southeastward through the evening hours before storms gradually
   weaken as boundary layer cooling and low-level stabilization occurs.


   ...Mid-Atlantic Region...
   More extensive cloud cover over Pennsylvania and northern West
   Virginia with fewer cloud to the south is creating a differential
   heating zone along the southern edge of the thicker clouds.
   Stronger heating to the south will enhance destabilization in
   advance of storms beginning to develop over southern West Virginia
   at this time.  VAD winds at RLX and LWX exhibit westerly winds of
   30-40 kt above 4 km which will provide sufficient shear to support
   organized multi-cell storms and possibly an isolated supercell or
   two.  Storms are expected to develop eastward this afternoon with
   potential for localized damaging wind gusts although isolated hail
   will also be possible with stronger storms.

   ...Eastern New Mexico and West Texas...
   Low-level moisture persists as far west as the upper Rio Grande
   Valley of New Mexico in the wake of widespread storms on Monday.  A
   few strong storms are expected to develop this afternoon and
   evening, initially over the mountains of central New Mexico, with
   the activity spreading eastward with time.  Other storms will
   develop over southwest Texas as well.  The region is on the edge of
   stronger southwest winds aloft associated with the upper low that is
   beginning to lift northeastward over the southern Great Basin.  A
   few stronger cells capable of producing hail and strong wind gusts
   will be possible.

   ......North-central Rockies to middle Missouri Valley...
   The Great Basin/southwest states-central upper low is beginning to
   move northeastward, with a lead shortwave trough currently lifting
   across northern Arizona expected to overspread the central
   Rockies/Wyoming through the afternoon into tonight. Orographic lift,
   increasing dynamic forcing for ascent coupled with adequate moisture
   will allow for the development and intensification of storms this
   afternoon initially across parts of Utah/western Colorado into
   interior Wyoming where locally severe storms will be possible. As
   forcing for ascent spreads northeastward by late afternoon, a
   somewhat more moist and unstable environment across central/eastern
   Wyoming could allow for more organized/sustained storm modes with
   hail/severe wind gusts possible as storms spread east-northeastward.

   Over the Plains, a nocturnally increasing low-level jet may help
   sustain storms into South Dakota and western/northern Nebraska this
   evening, in addition to an increase in storms farther east toward
   the Missouri River late in the evening/overnight with some hail
   possible.

   ..Weiss/Wendt/Elliott.. 05/22/2018

 

day1otlk_1630.gif

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Watch possible.

Quote

 Mesoscale Discussion 0489
   NWS Storm Prediction Center Norman OK
   1157 AM CDT Tue May 22 2018

   Areas affected...Eastern Indiana...Ohio...Far Northwest Pennsylvania

   Concerning...Severe potential...Watch possible

   Valid 221657Z - 221930Z

   Probability of Watch Issuance...60 percent

   SUMMARY...A severe threat appears likely to develop this afternoon
   from eastern Indiana east-northeastward across Ohio into far
   northwest Pennsylvania. Wind damage and isolated large hail are
   expected to be the primary threats. Weather watch issuance will need
   to be considered as storms increase in coverage and intensity.

   DISCUSSION...Latest surface analysis shows a cold front located from
   northwest Ohio southwestward into west-central Indiana. Surface
   dewpoints along and just ahead of the front are in the upper 60s to
   near 70 F. Surface temperatures are now in the 75 to 80 F range and
   the RAP is analyzing a corridor of moderate instability with MLCAPE
   of 1000 to 1500 J/k across eastern Indiana and western Ohio.
   Thunderstorms have developed over the last hour along the front near
   the strongest instability. Thunderstorms will continue to expand in
   coverage as low-level convergence increases along the front and as a
   shortwave trough moves from west to east across the region. In
   addition to the instability, regional WSR-88D VWPs show moderate
   deep-layer shear. For example, the Cleveland VWP has 0-6 km shear
   near 30 kt with unidirectional winds from the west-southwest. This
   wind profile should support a potential for damaging wind gusts with
   multicells especially as low-level lapse rates steepen over the next
   few hours. Cells that have rotation may also be capable of producing
   isolated large hail.

   ..Broyles/Weiss.. 05/22/2018

 

mcd0489.gif

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14 minutes ago, snowlover2 said:

T-storm watch until 9pm for SE IN/extreme N KY/most of Ohio.

I hope you guys score. We have had four days of slight risk or better in 2018 in NE IN and have nothing to show for it. Three out of the four times, I questioned SPC for including our area when guidance didn't look great to begin with.

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2 hours ago, IWXwx said:

I hope you guys score. We have had four days of slight risk or better in 2018 in NE IN and have nothing to show for it. Three out of the four times, I questioned SPC for including our area when guidance didn't look great to begin with.

This has become increasingly frustrating from a media perspective. I've stopped using the terms "marginal," "slight," etc altogether because they don't mean much to a viewer to begin with, especially when we have numerous slight days with, as you said, nothing to show for it. 

Looks like the next 7 days at least will be zzzzz. What an odd and eerily quiet spring it has been!

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