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2022 Short/Medium Range Severe Weather Discussion


Chicago Storm
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  • 2 weeks later...

Bigger threat is outside of region, but...

 

   SPC AC 291730

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1230 PM CDT Tue Mar 29 2022

   Valid 301200Z - 311200Z

   ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
   LOUISIANA...EASTERN ARKANSAS...MISSISSIPPI...WESTERN
   TENNESSEE...ALABAMA...AND THE WESTERN FLORIDA PANHANDLE...

   ...SUMMARY...
   A regional outbreak of severe thunderstorms is expected on Wednesday
   across the Lower Mississippi Valley and Southeast. All severe
   hazards are possible, including widespread damaging winds, some over
   75 mph, and several tornadoes, some of which could be strong (EF2+).

   ...Synopsis...
   A shortwave trough will eject from the southern Plains across the
   lower/mid MS Valley on Wednesday while acquiring a negative tilt. An
   80-100+ kt south-southwesterly mid-level jet will accompany the
   shortwave trough passage. Low-level southerly flow is also expected
   to be very strong, with 50-70+ kt winds forecast at 850 mb. The
   primary surface low should be located over IA at the start of the
   period, with a cold front extending southward from this low across
   the central/southern Plains. A secondary surface low in closer
   proximity to the shortwave trough is forecast to develop from
   eastern OK to the Mid-South vicinity by Wednesday evening.

   At least low to mid 60s surface dewpoints are expected to return
   northward across the lower MS Valley and Southeast ahead of the
   secondary surface low, with the surface warm sector becoming
   increasingly pinched off with northward extent into the mid MS and
   OH Valleys. With strong forcing for ascent associated with the
   shortwave trough overspreading the warm sector through the day,
   thunderstorms will develop and move east-northeastward ahead of the
   cold front while posing a threat for both widespread damaging winds
   and several tornadoes.

   ...Lower Mississippi Valley into the Southeast...
   A line of convection aided by strong low-level warm advection will
   likely be ongoing at the start of the period from the Ozarks
   southward across AR to east TX. This activity should continue to
   pose a threat for at least isolated damaging winds and tornadoes as
   it moves eastward Wednesday morning. Fairly widespread cloud cover
   ahead of the line and modest mid-level lapse rates should temper the
   degree of destabilization to some extent. Still, the increasing
   low-level moisture in tandem with filtered diurnal heating are
   expected to aid in sufficient boundary-layer destabilization to
   support surface-based storms. MLCAPE around 500-1000 J/kg should
   develop ahead of the line across LA into MS and surrounding areas by
   early Wednesday afternoon.

   This QLCS should strengthen Wednesday afternoon as it moves across
   northeastern LA, eastern AR, southeastern MO, and into much of the
   lower MS Valley and Mid-South. Aided by strengthening low/mid-level
   flow, increasing low-level and deep-layer shear will both become
   very strong, supporting updraft organization. With a primarily
   linear storm mode expected, widespread severe/damaging winds appear
   likely. The presence of a 50-70+ kt south-southwesterly low-level
   jet, and even stronger flow up to 75 kt at 700 mb, should enhance
   the prospects for significant severe wind gusts of 75+ mph at the
   surface within the most intense portions of the line Wednesday
   afternoon and evening. Very favorable low-level shear and
   elongated/sickle-shaped hodographs in the boundary layer will likely
   also support low-level rotation with embedded mesovorticies within
   the QLCS. Several tornadoes should occur across the lower MS Valley
   and Southeast in this regime, with circulations moving quickly
   east-northeastward.

   The potential for supercells to develop ahead of the line, or
   perhaps embedded within the line with southward extent, remains
   unclear. Any cells that can form ahead of the line would be favored
   to produce tornadoes, but the quick eastward progression of the QCLS
   may limit this possibility. Still, some guidance suggests the
   southern part of the line may become more broken with time Wednesday
   afternoon/evening. If this occurs, then a threat for embedded
   supercells capable of producing multiple strong (EF2+) tornadoes
   would exist. At this point, the greatest tornado potential may focus
   along southern portions of the line in MS/AL where a semi-discrete
   mode seems more plausible. Regardless, a continued threat for both
   damaging winds and tornadoes will likely persist Wednesday evening
   and overnight as convection spreads from the lower MS Valley into
   the TN Valley and Deep South. Thunderstorms should eventually weaken
   with eastward extent early Thursday morning as they outpace the
   low-level moisture return and encounter a less favorable
   thermodynamic environment.

   ...Mid Mississippi Valley into the Ohio Valley...
   Less low-level moisture and weaker instability are forecast across
   the mid MS Valley and OH Valley compared to locations farther south.
   However, enough boundary-layer instability should be present for the
   line of storms to produce scattered to perhaps numerous damaging
   winds as it moves eastward given the strength of the low-level flow.
   A few tornadoes may also occur with favorable low-level shear also
   present. The lack of stronger instability precludes greater severe
   probabilities across this region at this time.

   ..Gleason.. 03/29/2022

 

day2otlk_20220329_1730_prt.gif

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Bumping the short range severe thread for early-mid next week. Particularly Tuesday-Wednesday, not quite short range, but not really medium-long range either.

Anyway, on the 00z operational runs (the extent of my model analysis), both the Euro and GEM featured an intriguing I-80ish warm front scenario on Tuesday afternoon-evening in IA, IL and IN, with well into 60s and 70s surface temps, low-mid 60s Td near and south of the front. (ECMWF actually indicates front near/north of I-88 valid 18z Tuesday but then reinforced south to traditional I-80 and south during peak heating).

Meanwhile, the UKMET holds a rather volatile looking setup back to Wednesday afternoon and evening. On everyone's favorite GFS, the timing was out of whack, but large scale pieces pattern wise are there for severe weather potential.

Importantly to the setup, a reservoir of very steep 7.0 to 8C/km (or higher on some guidance) 700-500 mb lapse rates are currently favored to be advected northeastward and in place for the warm frontal zone/warm sector. This suggests that modeled 2000-2500+ J/kg ML/SB CAPE forecasts are not outlandish.

Lots of questions still on evolution of the trough ejecting out of the west and the track, strength, and timing of the main surface low that emerges out of this. For this reason, Wednesday certainly has potential, but is very contingent upon multiple favorable factors coming together.

Tuesday on the other hand has had recent support from the ECMWF and GEM for the warm frontal zone (possibly weak secondary low for a time) to be draped across roughly the I-80 corridor at peak heating paired with solid southerly surface flow south of the front, a decent LLJ, and brisk west-southwest mid-level (500 mb) flow of 40-60 kt, for roughly 35-55 kt of deep layer bulk shear, favorable for supercells.

One of the key elements of uncertainty on Tuesday is sufficient forcing for ascent, as modest height rises are progged, so subtle vort lobes from 700 to 500 mb may be needed, though the capping doesn't appear too prohibitive. Finally, getting just enough lift isn't a bad thing when it comes to potential warm front setups for chasing/spotting interests, to keep activity discrete. It'll be interesting to see if this possible Tuesday PM scenario holds as we get closer.

While a substantial severe weather episode is far from a high confidence proposition at this lead time, would be surprised if there's no instances of severe weather in the western half of the subforum between Monday night and Wednesday PM. At the least, the EML points toward threat for elevated hailers north of the surface front.











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8 hours ago, RCNYILWX said:

Bumping the short range severe thread for early-mid next week. Particularly Tuesday-Wednesday, not quite short range, but not really medium-long range either.

Anyway, on the 00z operational runs (the extent of my model analysis), both the Euro and GEM featured an intriguing I-80ish warm front scenario on Tuesday afternoon-evening in IA, IL and IN, with well into 60s and 70s surface temps, low-mid 60s Td near and south of the front. (ECMWF actually indicates front near/north of I-88 valid 18z Tuesday but then reinforced south to traditional I-80 and south during peak heating).

Meanwhile, the UKMET holds a rather volatile looking setup back to Wednesday afternoon and evening. On everyone's favorite GFS, the timing was out of whack, but large scale pieces pattern wise are there for severe weather potential.

Importantly to the setup, a reservoir of very steep 7.0 to 8C/km (or higher on some guidance) 700-500 mb lapse rates are currently favored to be advected northeastward and in place for the warm frontal zone/warm sector. This suggests that modeled 2000-2500+ J/kg ML/SB CAPE forecasts are not outlandish.

Lots of questions still on evolution of the trough ejecting out of the west and the track, strength, and timing of the main surface low that emerges out of this. For this reason, Wednesday certainly has potential, but is very contingent upon multiple favorable factors coming together.

Tuesday on the other hand has had recent support from the ECMWF and GEM for the warm frontal zone (possibly weak secondary low for a time) to be draped across roughly the I-80 corridor at peak heating paired with solid southerly surface flow south of the front, a decent LLJ, and brisk west-southwest mid-level (500 mb) flow of 40-60 kt, for roughly 35-55 kt of deep layer bulk shear, favorable for supercells.

One of the key elements of uncertainty on Tuesday is sufficient forcing for ascent, as modest height rises are progged, so subtle vort lobes from 700 to 500 mb may be needed, though the capping doesn't appear too prohibitive. Finally, getting just enough lift isn't a bad thing when it comes to potential warm front setups for chasing/spotting interests, to keep activity discrete. It'll be interesting to see if this possible Tuesday PM scenario holds as we get closer.

While a substantial severe weather episode is far from a high confidence proposition at this lead time, would be surprised if there's no instances of severe weather in the western half of the subforum between Monday night and Wednesday PM. At the least, the EML points toward threat for elevated hailers north of the surface front.










 

Been watching that timeframe.  It has potential as you outlined.  I feel like that Sunday-Monday system is a factor in this as well.  Not that it will really produce severe wx in the sub, but it helps to get the process of moisture return underway into the region.

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ECMWF is hinting at a strong MCS rolling east out of Iowa Tuesday evening.  It would follow the northern edge of a nice EML plume coinciding with warm sector dews in the lower 60s.  There's decent mid-level lapse rates with the first wave on Monday too, but the problem is the dewpoints are only low to mid 50s with that one due to the last cold front completely scouring the GOM.  How this first wave plays out will effect where the warm front ends up being Tuesday evening though.

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1 hour ago, frostfern said:

ECMWF is hinting at a strong MCS rolling east out of Iowa Tuesday evening.  It would follow the northern edge of a nice EML plume coinciding with warm sector dews in the lower 60s.  There's decent mid-level lapse rates with the first wave on Monday too, but the problem is the dewpoints are only low to mid 50s with that one due to the last cold front completely scouring the GOM.  How this first wave plays out will effect where the warm front ends up being Tuesday evening though.

it's not MCS season in these parts. I don't discount a fractured squall line. Check back in after memorial day...maybe.

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If I'm not mistaken, the western half of LOT being in the day 5 outlook for Wednesday is the first time any part of LOT has been in a day 4-8 outlook in April since April 9, 2015. Seems fitting that the day 5 inclusion would come on the 7 year anniversary of Rochelle-Fairdale.

With the exception of the GFS being a fast outlier still on Wednesday, the ECMWF depiction, supported by the GEM and UKMET, certainly warrants the large 15% area all the way up to the upper MS Valley on the day 5.

The deep layer bulk shear magnitude and low level wind profile are supportive of supercells and tornadoes, but shear vector orientation is too close to parallel to the cold front due to the meridional mid and upper flow.

That plus the strength of the synoptic forcing Wednesday evening may yield initial supercells and tornado threat west of the MS River transitioning to a squall line (with QLCS tornado threat) with eastward extent. I think the day 5 outlook depiction is reasonable, as the timing on the non GFS consensus is a bit late for the eastern half of LOT. It's not a slam dunk severe weather outbreak, but it's a solid setup for this region by recent April standards. Certainly still time for changes for better, or for worse.

The potential warm front setup on Tuesday looks a little less favorable than my initial post, with later arriving moisture and decreasing forcing with southward extent, making breaking the cap more uncertain. If any storm can go Tuesday evening, would still have a tornado threat. Otherwise, most of the convection Tuesday PM will likely be elevated north of the warm front, with the steep mid-level lapse rates potentially supporting a severe hail threat if large enough MUCAPE materializes given favorable deep layer shear.





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I think we’re going to need a dedicated thread for Wednesday soon enough. If that trough deamplifies any further from current progs, you’re going to see a scenario where the upper forcing is spread across a very large warm sector (from the Lower MS Valley to Upper Midwest) with favorable moisture and shear profiles for supercells and tornadoes. To me, it has the potential of a large scale outbreak, especially if the NAM/UK/Euro blend are on the right track.

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On 4/8/2022 at 1:41 PM, Hoosier said:

Been watching that timeframe.  It has potential as you outlined.  I feel like that Sunday-Monday system is a factor in this as well.  Not that it will really produce severe wx in the sub, but it helps to get the process of moisture return underway into the region.

Anything that primes the pump before a possible svr wx scenario is concerning to me.  And as I have mentioned before since the  April 20, 2004 Utica Illinois tornado warm fronts draping the area raise my suspicion.

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  • 2 weeks later...
8 hours ago, Chicago Storm said:


You’re not missing anything at least.

Tomorrow is as marginal as it gets. Activity from Friday might end up being better.

We already had some fun here back in March, so I'm good with getting skipped over to be sure.  I will say though it's amazing how many events seem to blow up in the west half of Iowa only to crap the bed by the time it reaches the Mississippi.  Seems like most of our meaningful severe doesn't come from the big synoptic systems which seem to skip over us, and more from the ROF summer MCS type events.  Probably why long-track strong to violent tors pretty much never happen in the DVN cwa, which is a good thing.  This area does quite well though with bird fart QLCS one scan wonders.  Good stat padders, and keeps the DVN survey crew busy lol.

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We already had some fun here back in March, so I'm good with getting skipped over to be sure.  I will say though it's amazing how many events seem to blow up in the west half of Iowa only to crap the bed by the time it reaches the Mississippi.  Seems like most of our meaningful severe doesn't come from the big synoptic systems which seem to skip over us, and more from the ROF summer MCS type events.  Probably why long-track strong to violent tors pretty much never happen in the DVN cwa, which is a good thing.  This area does quite well though with bird fart QLCS one scan wonders.  Good stat padders, and keeps the DVN survey crew busy lol.

Very good points.

Kind of interesting how that works, but my guess it has to do with timing of systems ejecting out from the Inter-Mountain West and into the Plains. Such as, if the Mountainous region in the West was further east, maybe that would have a chain reaction effect for bigger synoptic events in your area.
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It's at the end of its range but 06 NAM raised my eyebrows a bit for Saturday, although SPC placed their Day 4 risk area much further south. I'm loath to ask off so I can chase Friday after I took 4/13 off so I could get some sleep after marathoning 5 hours to Ft. Dodge after working 3A-noon Tuesday 4/12, only to miss the Gilmore City tornado by a few minutes/miles.

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On 4/27/2022 at 9:58 AM, CheeselandSkies said:

12Z run holds serve and goes out to 00Z Sunday...not the ideal setup but looks like good mid/upper diffluence and lapse rates over the warm sector...SPC gonna need to come north/possibly east (into IN) quite a bit with the Day 4 risk area if that verifies.

They did come north/east.  Probably still not quite far enough though.

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  • Chicago Storm changed the title to 2022 Short/Medium Range Severe Weather Discussion

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