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Indystorm

April 11 Severe aspects

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While winter lovers salivate over the prospects for major snow in MN, IA, and WI strong t storms are possible over central and southern IL and IN.  Just look at the baroclinic zone in the center of those two states from the April 4 18z GFS for next Thursday.  FV3 also has a powerful low pressure  and Euro is also in the works.  Indpls tv mets are already mentioning this situation as something to watch.  As always best take now is that a powerful storm could be in the works with precip and track and timing to be narrowed further as we get closer.  Ohio Valley and mid south need to watch this develop as well.

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I'm concerned about moisture on the 10th and concerned about veering in the warm sector on the 11th. Unless moisture markedly increases on the 10th or the low occludes slower, I cant see this amounting much more than a decent QLCS.

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IND AFD for this April 5 says a modest gradient with the warm front will be in our area Wed.-Thursday of this upcoming week. Will have to continue to watch parameters as the week unfolds, especially from central regions southward.  Very good lapse rates will be present for storms. Today's 18z GFS shows a strong WF with 70's just south of Indy with dews around 60 for Thursday.  Chicago is at 32 degrees.  Kinda hard to believe.

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I weep for the potential of the system depicted on the 06Z GFS if not for the pesky lead system that keeps winds northerly over the western Gulf through 12Z Wednesday.

Still worth watching how things evolve. I've made the mistake of writing off early season systems too quickly due to marginal/JIT moisture return and been burned (barely glimpsing an after dark tornado on March 15, 2016 after turning my back on the storm, sitting out February 28, 2017, also didn't take April 9, 2015 as seriously as I might have if it were in late April or May even though I don't recall moisture being a concern that day).

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12Z GFS now forecasts another Plains mega-bomb with 975mb over western NE by 00z Thursday, however winds are still northwesterly over all but the far western Gulf. :axe:

Plenty of moisture however for epic snows on the north side wherever it's cold enough, if those totals are anywhere close to accurate the ongoing flooding problems aren't going anywhere anytime soon.

By 00Z Friday things are looking rather interesting over northern IL. Rochelle redemption for me? Too soon to tell. That is if I can even dig my car out of the snow in time to go chase. :D

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18z GFS Saturday continues the trend for concern for svr wx for IN especially this coming Thursday afternoon and evening with many parameters quite favorable.  Moisture slowly increasing.

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Hmm, not sure about this one.  Moisture return looks iffy.  Wind fields aren't lacking for getting severe weather.  I think there will be some severe weather but thinking a run of the mill episode as it looks now.  Will be watching to see if moisture can trend better.

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Yes, lack of adequate low level moisture is definitely the fly in the ointment for this upcoming episode as is a traditional concern this far north.  6-8 inches of rain in parts of Louisiana and Texas from the current system down there this Sunday.

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If moisture does not fully materialize one can hope for some sort of low top episode just east of the surface low. Little far out to forecast those details. However right now shear looks good.

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Yeah, I'd say I'm more interested in the northern zone of the warm sector than anything farther south.

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15% on the 4-8 day SPC outlook for IL/IN/KY.  Theta-E coming up some on the models along with a little increase in moisture.  

day4prob.gif?1554747216427

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Quad Cities, Dubuque, Rockford, Chi-town area east to Michiana look good at present on 12z NAM for possible tornadic action later on Thursday if moisture arrives and shear holds in future runs.  Same with 18z run this Monday. I-80 corridor just south bears watching as well depending on where the baroclinic zone finally sets up.

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So far NAM and GFS are pretty insistent on southern WI getting into the warm sector with this...a far cry from the 30s with snow that was forecast for us as of a few days ago. Still they do seem to have a tendency to underestimate the Lake Michigan warm front blocker.

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Leaning against chasing northern IL on Thursday at this point. I would if the somewhat marginal moisture were the only issue, but despite the deep low and a >110kt jet at 500mb, it looks like all the shear will be speed shear so we'll end up with racing bands of storms. Even right ahead of the triple point, hodos on NAM forecast soundings are nearly straight-line. I'm also not seeing the steep lapse rates needed to overcome the sub-optimal moisture for a nice low-topped outbreak like early December, April 2004, etc. Better conditions at this time look to be further east along the warm front over IN/possibly SW MI.

Still, it's a northern Illinois warm frontal setup so will continue to monitor, like the ones I mentioned those often don't look that great until the day of.

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Yeah Hodo's looking a little better over my way on the NAM's.  It's still wait and see but I'm itching so bad to chase might go ahead and take a half day off lol.

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11 minutes ago, Jackstraw said:

Yeah Hodo's looking a little better over my way on the NAM's.  It's still wait and see but I'm itching so bad to chase might go ahead and take a half day off lol.

Yeah, NAMs keep incrementally increasing the moisture and threat here in IN especially.  I'm going to spotter training this evening in Greenfield so I hope to get a met's opinion on this.

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18z nam and nam 3km both bring better moisture. I think question of warm sector activity comes down to sunshine. Right now, simulated IR is cloudy for most of the day. 

B22678D1-E842-4FE1-81FA-3D1DC59A27F2.png

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Nice to see a bit more moisture being progged.  As was mentioned earlier, directional shear definitely lacking overall except right on the warm front.  Speed shear looks tremendous though.  

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Thursday looks like a marginal day around here.

As mentioned by many, quality moisture is lacking, among other things.

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16 minutes ago, Hoosier said:

Nice to see a bit more moisture being progged.  As was mentioned earlier, directional shear definitely lacking overall except right on the warm front.  Speed shear looks tremendous though.  

Sounding from near Danville, IL. Directional shear not terrible, but could be better. 

5A7A9A3A-A747-436B-B1B0-2DD7326AA3D3.png

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1 hour ago, Chicago Storm said:

Thursday looks like a marginal day around here.

As mentioned by many, quality moisture is lacking, among other things.

I'm skeptical that the warm front is even going to get through all of northeast IL in time.  

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28 minutes ago, Hoosier said:

I'm skeptical that the warm front is even going to get through all of northeast IL in time.  

I'm skeptical on a lot with this system but hey it's something to break this lackluster beginning to Spring so far lol.:weenie:

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13 hours ago, Jackstraw said:

I'm skeptical on a lot with this system but hey it's something to break this lackluster beginning to Spring so far lol.:weenie:

Can’t believe I’m taking a day off tomorrow. Warm sector has virtually no chance of activity and LCLs are around 850....

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No real significant changes on the new day 2 outlook

 

Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1230 PM CDT Wed Apr 10 2019

   Valid 111200Z - 121200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
   EASTERN IL INTO WESTERN IN...

   ...SUMMARY...
   Scattered thunderstorms capable of isolated damaging wind gusts and
   perhaps a tornado or two will be possible from portions of the Upper
   Midwest into the Ohio Valley and Lower Great Lakes on Thursday.

   ...Synopsis...
   A strong and well developed cyclone centered over KS/NE Thursday
   morning will move northeastward to southern MN through the period. A
   deep (likely sub 990 mb) surface low along the KS/NE border is
   forecast to occlude and slowly fill as it develops northeastward in
   tandem with the mid/upper-level cyclone. A warm front extending
   eastward from this low will shift northward across parts of the
   Upper Midwest and OH Valleys into the lower Great Lakes region by
   Thursday evening, while a cold front sweeps eastward over much of
   the lower/mid MS Valley by Thursday night.

   ...Upper Midwest into the OH Valley and Lower Great Lakes...
   Scattered thunderstorms will probably be ongoing at the start of the
   period across parts of IA and southern MN at the start of the period
   in a zone of strong low-level warm air advection. In the wake of
   this morning activity, weak destabilization should occur across
   parts of central/eastern IA into southern WI as the warm front
   shifts northward. Very strong flow will be present in the mid/upper
   levels as a 100+ kt south-southwesterly at 500 mb overspreads this
   region. Additional low-topped convective development will probably
   occur by early afternoon along/just ahead of the eastward-moving
   cold front, and most guidance suggests thunderstorms quickly grow
   upscale into a small line. Isolated strong to locally damaging winds
   appear to be the main threat as the strong flow becomes mixed to the
   surface. A tornado or two may also be possible as storms cross the
   warm front and encounter greater low-level SRH before eventually
   become elevated. However, low-level moisture will remain limited
   across this region. For now, confidence in a predominately discrete
   storm mode remains too low across central/eastern IA into southern
   WI to include higher severe probabilities.

   Thunderstorms posing mainly an isolated damaging wind threat should
   develop along the length of the cold front by late Thursday
   afternoon from eastern MO into western IL. Relatively greater
   moisture (potentially upper 50s to around 60 surface dewpoints) is
   forecast to be present across parts of eastern IL into western IN,
   and even though storms may not reach this area until late Thursday
   evening, an isolated wind risk should persist given the strength of
   the low/mid-level flow. Have therefore made no changes to the Slight
   risk for damaging winds across this region. This severe threat
   should eventually wane with eastward extent across the OH Valley
   late in the period as low-level moisture becomes increasingly
   meager.

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

   ..Gleason.. 04/10/2019

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HRRR has some very nice warming in the warm sector tomorrow.  Problem is it comes at the expense of dews mixing out. 

There's a middle ground of temps being bit lower/dews a bit higher which wouldn't be such an instability killer like the above scenario. 

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17 hours ago, Hoosier said:

I'm skeptical that the warm front is even going to get through all of northeast IL in time.  

I was a few days ago, since it usually gets held up around I-80 in most cases.

However, it looks like there is significant support for it to make it to at least the IL/WI border during the afternoon.

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1 hour ago, Hoosier said:

HRRR has some very nice warming in the warm sector tomorrow.  Problem is it comes at the expense of dews mixing out. 

There's a middle ground of temps being bit lower/dews a bit higher which wouldn't be such an instability killer like the above scenario. 

FWIW, the HRRR is currently underdoing dew points in kansas by 3-4 degrees. Id probably add 2-3 degrees to the HRRR dewpoints for tomorrow. 

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