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WeatherMonger

May 14 - 22 Tornado Outbreak Sequence

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Posted (edited)

SPC has delineated an area across TX, OK and Kansas for Friday with mention of a separate threat further north and a conditional risk for Saturday dependent on convective debris

 

 

59092374_day6prob(3).gif.7f75bbc925389263e296590579841a17.gif

 

Quote

   Day 4-8 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0240 AM CDT Sun May 12 2019

   Valid 151200Z - 201200Z

   ...DISCUSSION...
   On Wed/D4-Thur/D5, an upper ridge will move east across the Plains,
   as a large upper trough develops across the West, with upper low
   over the Great Basin. By Fri/D6 into Sat/D7, severe weather appears
   likely across parts of the central and southern Plains, as mid to
   possibly upper 60s F dewpoints return north aided by a southerly
   low-level jet. The ECMWF ensemble has reasonably low spread, and has
   a deeper solution with the trough compared to the GFS ensemble
   members. In either case, the threat for severe weather is likely to
   increase on Fri/D6 into Sat/D7, and 15% probabilities have been
   introduced for Fri/D6. Increasing flow aloft with a substantial
   low-level jet and moisture should support supercells along the
   dryline Fri afternoon and evening. Predictability related to the
   previous day's storms, as well as increased model spread, will
   preclude a Sat/D7 area farther east.

   Severe storms are possible as well on Fri/D6 across parts of the
   northern Plains, from the Dakotas into Minnesota with an MCS pattern
   in a warm advection regime. However, predictability for this
   scenario is low at this time.

   ..Jewell.. 05/12/2019

 

 

Edited by ClicheVortex2014

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7 minutes ago, WeatherMonger said:

Timmer going all out on this set up

Screenshot_20190512-113551_Facebook.thumb.jpg.611751436514e3a7ea9475a7b97e6c6b.jpg

 

That's impressive for anyone to say something like that a week out. 

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Bet nothing decent for the Great Lakes...severe weather nonexistant for northern Ohio this year. Out west looks promising 

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5 hours ago, snowlover2 said:

That's impressive for anyone to say something like that a week out. 

I saw that tweet too. He’s very knowledgeable and pretty well respected but he does like to overhype... hence why he’s the center of a meme calling everything a wedge. I haven’t looked at model data for a few days so he may be justified. Dunno.

By the way my laptop is broken again so I can’t contribute like I usually do

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Started explaining what was wrong with my laptop and it started working again. 

Just looked at the 12z runs.... holy crap. Now let's see what changes.

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Still seems basically the same path for bad storms.  Here in northern Indiana I've heard it thunder 2 times during the whole spring season. Plenty of rain but all the bad stuff stays south.  Not that I'm complaining though.

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You know you have a strong system when there's widespread precip in the west and snow in the mountains in the middle of May.

Si2ZIWD.png

QJNQXCx.png

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255152805_day5prob(3).gif.5271047ea40873cc1336d8ae80ad4ae0.gif

 

1410652685_day6prob(4).gif.796a764461d918e77321d3836af7b130.gif

 

Quote

Day 4-8 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0246 AM CDT Mon May 13 2019

   Valid 161200Z - 211200Z

   ...DISCUSSION...
   On Thursday/D4, an upper ridge will be in place across the central
   U.S. with a large upper trough across the West. Meanwhile, northwest
   flow will exist across the Great Lakes with a low amplitude wave
   moving quickly from northern MN toward PA by Friday/D5 morning. A
   cold front will accompany this wave, with lift focused from MN into
   IA, northern IL/IN and OH. Substantial westerly winds at 850 mb will
   transport theta-e across IA and IL toward the front, with a corridor
   of strong to possibly severe thunderstorms from IA across southern
   WI and northern IL during the late afternoon and evening. Damaging
   winds would be most likely. A this time predictability is too low to
   denote an MCS corridor, but a Slight Risk is possible in later
   updates.

   Also on Thursday/D4, moisture and instability will spread west
   across NE and southern SD, as the leading height falls with the
   western trough approach the High Plains. Isolated severe hail and
   wind is possible over parts of eastern WY, western NE, and southwest
   SD during the late afternoon and evening.

   On Friday/D5, strong southwest flow aloft will spread into the
   Plains, with the strongest winds from NM into west TX. Low pressure
   is forecast across northeast CO into NE during the day, with a
   dryline extending southward into west TX. Widespread mid 60s F
   dewpoints will be in place ahead of the dryline, and northward to
   the warm front from eastern SD into IA. Moderate to strong
   instability will develop over the warm sector, with wind profiles
   supporting supercells producing very large hail and a few tornadoes.
   Clusters of storms, or an MCS, is also possible overnight mainly
   over northwest TX into western OK.

   For Saturday/D6, significant differences exist regarding the
   shortwave trough, with the new ECMWF showing a compact,
   negative-tilt shortwave from northwest TX across OK and into KS.
   Meanwhile, the GFS based members show a less amplified solution,
   with the main threat area farther east. Either solution will support
   severe weather, whether more of a squall line producing damaging
   winds, or a mixed mode threat including supercells and tornadoes. As
   such, have introduced 15% severe probs for Saturday, mainly across
   OK and TX.

   For Sunday/D7, a moist, unstable air mass is most likely to exist
   over eastern TX and into AR and possibly MO. Much of this area will
   be behind the departing upper trough, thus predictability is quite
   low. 

   On Monday/D8, models show a broad area of cyclonic flow aloft again
   across the West, with some manner of trough amplification possible
   into the Plains. Predictability is low, however, substantial
   low-level moisture will be available for any wave that emerges into
   the Plains, including into Tuesday/D9, with bouts of severe weather
   possible from the Plains to the Midwest.

   ..Jewell.. 05/13/2019

 

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Posted (edited)

More interested in the period immediately after the thread dates. Not sure if one of you will start new threads for each system, or if we'll have a general thread for the outbreak sequence. 12z GFS depicts a high end severe threat across NE/KS/IA/MO during the evening hours of Monday 05/20. ECMWF agrees on low placement. Could also see some significant activity around Day 12 (05/22-24) in the central Great Plains. Will be interesting to watch!

Edited by PGM

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12z Euro shows an MCS developing around the N IL/N IN/S WI area Thursday evening and dropping southeast through much of Ohio.  SPC mentioned in the above 4-8 day outlook that a slight risk area may be needed and should be interesting where they put it when the new day 3 comes out overnight.

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00z GFS for day 10 was one for the books. Wow. Couldn't share last night because the site went down

RUTQqs0.png

 

SW OH

C4z530W.png

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EHI looks really impressive in the Plains but the LCL looks a bit high on GFS.

rtavK5p.png

 

Central KS

H37RRH4.png

 

Western OK

sr5nzKI.png

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Days 4-8 all have a risk, day 4 with a large enhanced risk.

 

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day8prob.gif.cfe4bad715a66959a526069c299070ca.gif

 

Quote

Day 4-8 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0347 AM CDT Tue May 14 2019

   Valid 171200Z - 221200Z

   ...DISCUSSION...
   An active stretch for severe weather will occur during the entire
   D4-8 period, mainly over the central and southern Plains.

   ...Friday/D4...
   Increasing southwesterly winds aloft will spread eastward across the
   High Plains Friday as a large upper trough progresses east across
   the Rockies, with low pressure centered over the CO/NE/KS border
   region. A broad area of at least mid 60s F dewpoints will envelope
   much of the central and southern Plains, as well as much of the
   MS/TN/OH Valleys. Cooling temperatures aloft combined with heating
   along a dryline will result in 2000-2500 J/kg MUCAPE, on average,
   near the dryline, from central NE into west TX Friday afternoon.
   Strong heating west of the dryline will result in a narrow, but
   expansive north-south zone of supercell potential, with very large
   hail and tornadoes possible.

   ...Saturday/D5 into Sunday/D6...
   The leading wave is expected to eject in a negative tilt fashion
   over TX/OK/KS, with backing winds and rapid cooling aloft. While
   areas of ongoing storms may exist over northwest TX and OK Saturday
   morning, there will be a marked increase in storm coverage during
   the day, with a severe threat as far north as NE and IA. Widespread
   moisture (although likely weaker instability) will be sufficient for
   severe storms capable of damaging winds and a few tornadoes.
   Upgraded probabilities are possible in later outlooks as
   predictability increases.

   This upper wave will continue to progress northeastward toward the
   middle MS Valley on Sunday, with strong cooling aloft and impressive
   shear profiles. The slower ECMWF solution is preferred, suggesting a
   severe threat across parts of MO, IL and perhaps AR where it will be
   most unstable, although southern areas will see rising heights
   behind the wave. Details are difficult to assess at this point but
   damaging winds appear likely, along with a tornado or two.

   ...Monday/D7 into Tuesday/D8...
   An extensive mid/upper jet streak within a broad area of cyclonic
   flow aloft will nose eastward across the southwestern states and
   into the southern Plains on Monday/D7. Some model differences do
   exist regarding how amplified the trough will be, however, there
   will clearly be a substantial risk of severe weather over much of
   the central and southern Plains, as very strong wind shear develops
   with ample low-level moisture nearby and spreading north. Again,
   supercells producing very large hail and tornadoes are possible.
   Upgraded probabilities are possible in later outlooks as
   predictability increases.

   Models suggest that a large portion of the upper trough energy will
   eject across the Plains on Tuesday/D8, with both the ECMWF and GFS
   deterministic models showing a 100kt 500 mb jet streak, anywhere
   from the OK/TX Panhandles into MO. Regardless of timing, a large
   area of strong wind shear with the upper trough, with substantial
   moisture in place, will lead to severe weather. It is too early for
   details but all modes of severe appear possible once again. Upgraded
   probabilities are possible in later outlooks as predictability
   increases.

   Strong southwest flow aloft is forecast to remain over the Plains
   even beyond D8, suggesting a continued threat of severe.

   ..Jewell.. 05/14/2019

 

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Not sure I have ever seen a Day 4-8 SPC outlook like that. Each daily discussion pretty much ends with "further upgrades are possible".

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2 hours ago, WeatherMonger said:

Not sure I have ever seen a Day 4-8 SPC outlook like that. Each daily discussion pretty much ends with "further upgrades are possible".

Yeah this has to be a first. Don't think I've ever seen each day of the 4-8 day outlook with a risk area outlined.

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Posted (edited)

I did see a tweet somewhere that this is the first time since 15% risks were introduced (in 2014. Has it really been that long?) on D4-8 that all 5 days had an outlook.

Edited by weathermanmidwest

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This is insane, GFS is on crack with 0-3km EHI I’ve never seen is so widespread with so many days having high values

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3 hours ago, weathermanmidwest said:

I did see a tweet somewhere that this is the first time since 15% risks were introduced (in 2014. Has it really been that long?) on D4-8 that all 5 days had an outlook.

First time in spc history for all 5 days

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Went ahead and made today the start as there is a marginal risk daily leading up to the main event. Probably won't get much attention from the sounds of the weekend threats.

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