HillsdaleMIWeather Posted November 4, 2017 Share Posted November 4, 2017 Day 2 Enhanced, 30% is the same, 15$ has been trimmed Link to comment Share on other sites More sharing options...
Hoosier Posted November 4, 2017 Share Posted November 4, 2017 text... Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 0100 AM CDT Sat Nov 04 2017 Valid 051200Z - 061200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF IL/IN AND NORTHWESTERN OH... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE MID MS VALLEY INTO THE OH VALLEY AND LOWER GREAT LAKES... ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SURROUNDING THE SLIGHT RISK... ...SUMMARY... Scattered severe thunderstorms capable of producing large hail, damaging winds, and a few tornadoes may occur across parts of the Lower Great Lakes, Midwest, and Ohio Valley regions on Sunday. ...Synopsis... A split flow pattern aloft will continue over much of the western/central CONUS on Sunday, with modest 500 mb height falls (around 30 dm per 12 hours) forecast to occur across the mid/upper MS Valley into the Great Lakes region. A strong southern-stream mid/upper-level jet will provide large-scale lift and should encourage convective development across parts of the lower Great Lakes, OH Valley, and mid MS Valley by Sunday afternoon. An elevated mixed layer with steep mid-level lapse rates (around 7-8 C/km in the 700-500-mb layer) originating from the central/southern Plains will overspread these regions through Sunday evening. At the surface, a broad and moist warm sector will be in place across east TX into the lower MS Valley, extending northward into the mid MS Valley, OH Valley, and Lower Great Lakes to the south of a warm front. Surface dewpoints reaching into at least the low to mid 60s should be common throughout the warm sector Sunday afternoon. A weak surface low is forecast to develop northeastward along a warm/cold frontal triple point from the vicinity of eastern KS/western MO early Sunday to northern IN/southern lower MI by Sunday evening. A trailing cold front will progress southeastward parts of the mid MS and OH Valleys through the day, likely accelerating late in the period. ...Lower Great Lakes/Midwest into the OH and Mid MS Valleys... Strong effective shear of 40-55 kt associated with the southern-stream mid/upper-level jet will likely be present along/south of the front mentioned above. Supercell thunderstorms may be favored with initial development along the warm front or within the open warm sector to the east/northeast of the surface low. Given the steep mid-level lapse rates and moist low-level airmass that will be present, MLCAPE may increase to around 1500-2000 J/kg by late Sunday afternoon, even with only modest diurnal heating forecast. Scattered large hail, some of which may be significant, could occur with initial supercell development, particularly across parts of central/eastern IL into western/central IN where buoyancy is expected to be greatest. The tornado potential should be maximized along the warm front through Sunday afternoon as long as the convective mode remains at least semi-discrete. Here, low-level winds should be backed to a more southerly direction, locally enhancing low-level helicity and updraft rotation. Eventual upscale growth into one or more bowing line segments may occur from late Sunday afternoon into the evening as the cold front begins to accelerate southeastward, and the primary severe threat should eventually transition to damaging winds. The accelerating cold front may tend to undercut ongoing convection by Sunday night, and with decreasing instability due to the loss of diurnal heating, the overall severe threat should gradually wane with eastward/southward extent late in the period. 00Z GFS/NAM and 12Z ECMWF are in better agreement with the placement of the surface warm front Sunday afternoon, which increases confidence in the northern extent of appreciable surface-based thunderstorm potential and corresponding severe risk. The gradient of severe thunderstorm probabilities has therefore been tightened across far eastern IA/northern IL and southern/central Lower MI. The potential remains for early-day elevated convection across parts of IL/IN/OH owing to a strong southwesterly low-level jet. But this activity, if it develops, will likely remain isolated and should not substantially impact/delay destabilization of the warm sector across this region. ..Gleason.. 11/04/2017 Link to comment Share on other sites More sharing options...
Quincy Posted November 4, 2017 Share Posted November 4, 2017 Can't really disagree with SPC much here. Even if tornado potential may be limited, wind fields and mid-level lapse rates suggest large to very large hail will be possible, supporting the enhanced risk. Link to comment Share on other sites More sharing options...
IllinoisWedges Posted November 4, 2017 Author Share Posted November 4, 2017 03z SREF FWIW Link to comment Share on other sites More sharing options...
Tim from Springfield (IL) Posted November 4, 2017 Share Posted November 4, 2017 Latest HWO from ILX linked below. ILX will also be having a conference call concerning tomorrow's severe threat at 2PM this afternoon (it seems like they do almost anytime there's a hatched and/or a Moderate risk anywhere in their CWA): https://forecast.weather.gov/product.php?site=ilx&product=HWO&issuedby=ilx Link to comment Share on other sites More sharing options...
Indystorm Posted November 4, 2017 Share Posted November 4, 2017 12z NAM seems to be holding the WF farther south as it has previously done. More of central and southern IL and IN now in play for severe. Only 49 degrees here at 11am and cloudy. Marion IL is 63/61. The strength of the system will be paramount in deciding how far north that front goes on Sunday. Link to comment Share on other sites More sharing options...
nwohweather Posted November 4, 2017 Share Posted November 4, 2017 I understand the pessimism but this airmass, combined with great lapse rates, LCLs and helicities show a ton of promise for tomorrow. Very conditional threat, but if that warm sector can get going we're gonna have a dicey day Link to comment Share on other sites More sharing options...
Hoosier Posted November 4, 2017 Share Posted November 4, 2017 1 hour ago, Indystorm said: 12z NAM seems to be holding the WF farther south as it has previously done. More of central and southern IL and IN now in play for severe. Only 49 degrees here at 11am and cloudy. Marion IL is 63/61. The strength of the system will be paramount in deciding how far north that front goes on Sunday. I would think the probabilities may be trimmed on the northern edge on the upcoming outlook. Link to comment Share on other sites More sharing options...
Stebo Posted November 4, 2017 Share Posted November 4, 2017 3 minutes ago, Hoosier said: I would think the probabilities may be trimmed on the northern edge on the upcoming outlook. Guarantee they are, I would pull them out of every MI county except Lenawee and Monroe Counties. Problem is now too many small ripples coming through so an initial small surface reflection comes through around 15z essentially closing the door to the north and not allowing the main low to lift the front. In other words this potential is finding anything and everything to limit it. Link to comment Share on other sites More sharing options...
Chicago Storm Posted November 4, 2017 Share Posted November 4, 2017 Looks really meh now outside of that narrow corridor in IL/IN/OH. Definitely not chase worthy anymore either. SPC definitely has some significant adjusting to do. Question is will they adjust, or just ride and die foolishly. Link to comment Share on other sites More sharing options...
Chambana Posted November 4, 2017 Share Posted November 4, 2017 Also looks like GFS trended towards NAM solution for tomorrow, on orientation of the front. HRRR looks pretty nasty in SPC outlined area for tomorrow as well. Things could get dicey. Hail is probably the biggest threat at this point. Link to comment Share on other sites More sharing options...
Hoosier Posted November 4, 2017 Share Posted November 4, 2017 Somewhere around LAF looks like a decent place to be. Still a bit tempting to go there with it being a Sunday, my familiarity with that entire area, and potential lack of additional severe wx setups in the area for months, but just looks a bit too iffy. Link to comment Share on other sites More sharing options...
Indystorm Posted November 4, 2017 Share Posted November 4, 2017 Being a Sunday I am too busy tomorrow to consider chasing. I agree the Lafayette/Kokomo area looks good, but follow wherever that warm front sets up as you well know for greatest chance of backing winds and any tor potential. Though I agree with Chambana that hail seems to be the biggest threat right now. Link to comment Share on other sites More sharing options...
Jackstraw Posted November 4, 2017 Share Posted November 4, 2017 Think I'm going to head over to Frankfort and work from there if everything pans out. Most of the fields are in so should have good visibility. The other half and I were going to Kokomo tomorrow anyway so I've talked her into going on her first chase with me. I know some big hailers and lightning will scare her more than than any spin ups so it could get interesting for us.. My windshields still broke in my chaser beater from a chase back in the spring lol. Hopefully my new camera mount won't fail me this time! Link to comment Share on other sites More sharing options...
IllinoisWedges Posted November 4, 2017 Author Share Posted November 4, 2017 Was just about to count myself out, but the 18x NAM came in with a pretty volatile environment. Bleh. Link to comment Share on other sites More sharing options...
Hoosier Posted November 4, 2017 Share Posted November 4, 2017 22 minutes ago, IllinoisWedges said: Was just about to count myself out, but the 18x NAM came in with a pretty volatile environment. Bleh. I don't know if there's ever been a sounding more unstable than this in Indiana in November lol Link to comment Share on other sites More sharing options...
HillsdaleMIWeather Posted November 4, 2017 Share Posted November 4, 2017 18Z NAM threw a damn curve ball, got the warm sector way further north . Still doesn't get the higher instability much further north, but it's a start Link to comment Share on other sites More sharing options...
Hoosier Posted November 4, 2017 Share Posted November 4, 2017 Even with a pretty pathetic surface low and likely a limited tornado count, the CAPE/shear parameters and rich low level moisture would support the possibility of a strong tornado, particularly the longer that cellular mode can be maintained. Link to comment Share on other sites More sharing options...
andyhb Posted November 4, 2017 Share Posted November 4, 2017 Oh NAM, the things you do to us sometimes. I should say I'm somewhat intrigued by how bullish the SREF has been with this. 15z run is popping a max of 75 on the STI around I-70 at 00z. I would like to see more support for pre-frontal convection though given the rather iffy shear vectors (forcing along/behind the front), and in general more support for the kind of shear profiles the 18z NAM is indicating, most other guidance isn't quite that impressive. Link to comment Share on other sites More sharing options...
Quincy Posted November 4, 2017 Share Posted November 4, 2017 4 minutes ago, Hoosier said: Even with a pretty pathetic surface low and likely a limited tornado count, the CAPE/shear parameters and rich low level moisture would support the possibility of a strong tornado, particularly the longer that cellular mode can be maintained. Very large hail is a big concern and a moderate risk for hail would not surprise me. Even the slightly less unstable HRRRX shows a CAPE/shear parameter space that would support very efficient hail growth. Very uncommon for this time of year. Some soundings I pulled showed 700-500mb lapse rates steeper than 8 C/km. Link to comment Share on other sites More sharing options...
Jim Martin Posted November 4, 2017 Share Posted November 4, 2017 1 minute ago, Quincy said: Very large hail is a big concern and a moderate risk for hail would not surprise me. Even the slightly less unstable HRRRX shows a CAPE/shear parameter space that would support very efficient hail growth. Very uncommon for this time of year. Some soundings I pulled showed 700-500mb lapse rates steeper than 8 C/km. Could the potential moderate risk stretch into Northwest Ohio as well tomorrow? Link to comment Share on other sites More sharing options...
andyhb Posted November 4, 2017 Share Posted November 4, 2017 The CWASP parameter off the 18z NAM on the CIPS model page is popping a value of 90 (very high) at 21z in a similar area to the SREF max. Info on this parameter: http://www.spc.noaa.gov/exper/mesoanalysis/help/help_cwasp.html Max value you can actually achieve on this is a 99 since it's an aggregate of 33 parameters on a scale from 0-3. Link to comment Share on other sites More sharing options...
nwohweather Posted November 4, 2017 Share Posted November 4, 2017 Makes a potential chase tomorrow very iffy. Usually don't deal with the big hail in this part of this country. I will say this, Quincy nailed it. Might not see a proliferation of twisters, but definitely wouldn't be shocked to see a couple strong ones and maybe 10. Happened like that last August, had a free day from work and liked the environment, didn't expect to be chasing a half mile wide tornado in NW Ohio Link to comment Share on other sites More sharing options...
HillsdaleMIWeather Posted November 4, 2017 Share Posted November 4, 2017 35 minutes ago, nwohweather said: Makes a potential chase tomorrow very iffy. Usually don't deal with the big hail in this part of this country. I will say this, Quincy nailed it. Might not see a proliferation of twisters, but definitely wouldn't be shocked to see a couple strong ones and maybe 10. Happened like that last August, had a free day from work and liked the environment, didn't expect to be chasing a half mile wide tornado in NW Ohio I know how you feel, I'm begrudgingly chasing tomorrow since I have to drive down near Fort Wayne to get something tomorrow. Hoping my windshield doesn't get busted. Link to comment Share on other sites More sharing options...
Indystorm Posted November 4, 2017 Share Posted November 4, 2017 So 18z NAM throws a curve ball and increases potential for svr storms from what was exprected. Going to be a nowcast situation along the wf I think. Link to comment Share on other sites More sharing options...
Indystorm Posted November 4, 2017 Share Posted November 4, 2017 4 hours ago, Jackstraw said: Think I'm going to head over to Frankfort and work from there if everything pans out. Most of the fields are in so should have good visibility. The other half and I were going to Kokomo tomorrow anyway so I've talked her into going on her first chase with me. I know some big hailers and lightning will scare her more than than any spin ups so it could get interesting for us.. My windshields still broke in my chaser beater from a chase back in the spring lol. Hopefully my new camera mount won't fail me this time! Good luck on your chase tomorrow with your wife going along. Sometimes fall rather than spring events can yield surprises. I will be watching models and radar carefully. Link to comment Share on other sites More sharing options...
Jackstraw Posted November 4, 2017 Share Posted November 4, 2017 4 minutes ago, Indystorm said: Good luck on your chase tomorrow with your wife going along. Sometimes fall rather than spring events can yield surprises. I will be watching models and radar carefully. Thanks! The good 'ol in the fall you don't chase 'em , they chase you in Indiana kinda surprises! Still some sorting out as everyone's pointed out but if we get a mini outbreak, and we can get lucky, hopefully we can get some good pics and video...... if I can control the potential localized panic lol. Link to comment Share on other sites More sharing options...
IWXwx Posted November 5, 2017 Share Posted November 5, 2017 Unfortunately, in my position with EMA, I won't be able to chase since there's still a slight possibility of severe hitting in the FWA and just south area. I would love to be able do a little chase. Good luck Jack and the others that are going out. I'll just be waiting for them to come to me here in Huntington County. Link to comment Share on other sites More sharing options...
Jim Martin Posted November 5, 2017 Share Posted November 5, 2017 0z NAM seems to shifted a tad further south. Low pressure area in North Central Indiana at 18z Sunday. Link to comment Share on other sites More sharing options...
Jim Martin Posted November 5, 2017 Share Posted November 5, 2017 0z 3k NAM showing potential for an active warm front tomorrow afternoon. Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.