Hoosier

1.5" hail in Berwyn.

Boundary in northeast IL/northwest IN has put on the brakes and even appears to have retreated north/east a bit. Will have to see if any cell can take advantage of it, though low level flow is fairly weak so it may still be tough to get a spinner.

20z outlook expresses some doubts about convective coverage in the ENH area.

Area Forecast Discussion National Weather Service Chicago/Romeoville, IL 203 PM CDT Sat Jun 1 2019 SHORT TERM... 155 PM CDT Through Tonight... An outflow/lake breeze composite boundary has pushed inland to near a Woodstock to Naperville to Wheeler line based on latest surface observations. The airmass to the east and north of this boundary has been stabilized, with dewpoints in the upper 50s and temperatures in the upper 60s. This stabilization is also demarcated by stable wave clouds on GOES-16 visible satellite imagery. Latest guidance does indicate the breezier synoptic southwesterly flow may force this boundary back east a bit through the afternoon hours, and how this modified airmass impacts the severe potential into portions of Lake (IL) and Cook counties remains a bit uncertain at this time. Recent ACARS soundings out of Midway show this stable layer is pretty robust, with a notable temperature inversion present near the surface. With additional diabatic heating, would expect at least some airmass recovery on the cool side of this boundary with baroclinicity starting to wash out a bit over the next 1 to 3 hours. If this boundary remains robust, however, it could locally mute the severe threat into Cook and Lake counties later this evening by limiting the potential for strong downdrafts and associated winds to reach the surface. The other question stems around a notable pocket of dry air now being analyzed in the 850-700 mb layer with 850 mb dewpoints under 0 C now being analyzed across portions of northwestern Illinois and into our far western counties. This could tend to work against updraft intensity--at least initially--although an axis of much higher moisture is analyzed near I-90. With surface temperatures having warmed into the 80s, dewpoints in the lower 60s, and steep mid-level lapse rates in place overhead, MLCAPE values are, nonetheless, inching past 2000 J/kg early this afternoon, especially near and west of the I-90 corridor. Mid-level winds are also increasing ahead of a small but sharp shortwave, and effective deep layer shear values are pushing north of 30-35 kts across the region (lower south of I-80, highest north). 500 mb height falls on the order of 50-60 m/12 hr have been noted spreading towards southern Wisconsin. Associated increases in forcing for ascent will be responsible for expanding showers and thunderstorms along and incoming cold front through the evening hours. All of this taken together spells a continued threat for strong to severe storms across our region this afternoon. Hi-res guidance continues to struggle with a rather wide disparity in solutions still noted this afternoon. Storms are beginning to develop across southwestern Wisconsin at this hour, near a developing weak surface low and at the leading edge of stronger ascent from the incoming shortwave. Latest thinking is that storms will continue to develop south and westward over the next hour or two, eventually nearing Winnebago, Ogle, and Lee counties towards 4 PM or so. Additional convection is also attempting to develop along the aforementioned outflow/lake breeze across southern Cook and into Lake (IN) and Porter counties. The airmass immediately ahead of this boundary is unstable and only weakly capped, so we will need to keep an eye on this area for potential storm development as well. Initial discrete/isolated activity will carry a risk for large hail (potentially up to ping pong-golf ball sized), but storms should quickly begin to congeal into line segments as robust forcing overspreads the area. As a result, the severe threat will begin to transition to mainly wind damage, with a potential for 60-70 mph wind gusts. At this time, think the main severe corridor may end up developing near and north of I-80, and particularly focusing along I-88 and I-90 where instability will be maximized. The tornado threat is low from a synoptic standpoint with minimal low-level hodograph curvature, but we will be keeping an eye on any stronger updrafts which manage to develop near this feature later this afternoon. A brief tornado spin-up or two can`t be ruled out in the vicinity of this boundary, but the main severe risk still appears to be from hail and damaging winds. Looks like a surging line of storms will move out of our south and eastern counties by mid-evening with a continued threat for strong to locally damaging wind gusts. Will be holding onto some low PoPs behind this line of storms with lingering moisture and some instability to work with, but the main severe window will come to a close by about 9-10 pm area-wide. Carlaw

I'm wondering that too. Not sure if the models get continuous input on the state of the vegetation.

The boundary that just went through Chicago *could* locally enhance the tornado threat a little for anything tracking along it later... wherever it is by then.

Yeah, the threat in northern IL looks as decent if not better than where the ENH is currently placed.

Dews coming in under guidance would temper instability some, as has been mentioned in the discussions. Haven't checked to see how the CAMs are handling dews.

Upgraded to enhanced farther south/west Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1234 PM CDT Fri May 31 2019 Valid 011200Z - 021200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM KANSAS INTO A PORTION OF THE MIDWEST... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER A PORTION OF THE SOUTHERN PLAINS... ...SUMMARY... Scattered severe storms are possible Saturday afternoon central and eastern Kansas, northern Oklahoma, Missouri, Illinois and extreme southeast Iowa. Other more isolated strong to severe storms are possible from the southern through central High Plains. Large hail and damaging wind will be the primary threats. ...Synopsis... Shortwave trough now over the northern High Plains will become absorbed within the amplifying northern stream and move southeast through the Midwest region Saturday. Cold front initially from the upper Great Lakes through western KS will move southeast, and by early evening should extend from the southern Great Lakes, northern MO into southeast CO where it will likely stall. ...Central Plains through the Midwest regions... The atmosphere from KS through the Midwest is expected to become moderately to strongly unstable Saturday afternoon with 2000-3000 J/kg MLCAPE supported by the northeast advection of low-mid 60s F dewpoints through the warm sector beneath plume of steeper (7-7.5 C/km 700-500 mb) lapse rates. Some model solutions are overdone with low-level dewpoints by several degrees, apparently due to excessive evapotranspiration, but correcting for this still supports moderate to strong instability as the surface layer warms during the afternoon. Widely scattered to scattered storms are expected to initiate along the cold front by mid afternoon as the boundary layer destabilizes and the cap weakens. Northwesterly winds will strengthen to 40+ kt at 500 mb, especially from eastern KS through central IL as height gradient increases in association with the amplifying upper trough. This will support 35-40 kt effective bulk shear. Both supercell and multicell storm modes are expected with initial discrete storms eventually consolidating into lines or clusters as they spread southeast. Damaging wind and large hail will be the main threats. ...Southern High Plains... Storms are expected to once again develop over the higher terrain of NM and southwest TX and subsequently spread east into the High Plains. Have introduced a slight risk over this region where a belt of somewhat stronger winds aloft and moderate instability will promote a parameter space sufficient for a few supercells capable of large hail and damaging wind. ...MAXIMUM RISK BY HAZARD... Tornado: 2% - Marginal Wind: 30% - Enhanced Hail: 30% - Enhanced ..Dial.. 05/31/2019

It does look slight risk worthy.

So this is cool. You can plot the SPC outlooks over a period of time by WFO/State/County. It gives the highest risk level for each day. https://mesonet.agron.iastate.edu/plotting/auto/?q=201 A lot of neat features besides the outlooks to play with in the dropdown box, too.

Early week does appear to have some potential. Just focusing on Monday for now, the warm frontal zone could get interesting. Will probably be dealing with storms early in the day though which could muddle things.

Been a tough day. The weakly forced setups are more prone to getting derailed, generally speaking.

New LOT afd is pretty pessimistic.

SPC added an ENH/30% wind area on the new outlook. Not clear to me how widespread of a wind threat will evolve so I'm gonna hold my tongue from further comment lol.

HRRR seems to be on a downward trend with the early evening development in the area though. That was my reasoning earlier for central/southern LOT cwa potentially being favored a bit... it was assuming vigorous (re)development along the warm front from around now through the next few hours but that is looking iffy.

Current

They have it as radar indicated in the warning update.

Hopefully we can get something to go nearby in the next hour or two. If not then it will be a long wait.

Area Forecast Discussion National Weather Service Chicago/Romeoville, IL 556 PM CDT Fri May 24 2019 .MESOSCALE DISCUSSION... 553 PM CDT The weather forecast over the next 12+ hours remains fairly complicated, and uncertainties abound mainly due to the weak nature of large-scale forcing for ascent. While a threat for strong to severe thunderstorms certainly exists this evening and into the nighttime hours, how this threat materializes remains tied to mainly subtle mesoscale processes and subtle waves of synoptic ascent which are both difficult to diagnose and pinpoint with much certainty. Surface analysis late this afternoon depicts a northwest to southeast arcing warm front--reinforced by this morning`s convection which laid out an outflow boundary--likely just entering portions of La Salle, Livingston, and Ford Counties. Dewpoints immediately to the south of this boundary jump into the 70s with breezy south to south-southwesterly winds, and this seems to be demarcated pretty well by an area of bubbling Cumulus and HCRs which are steadily building northward. Recent RAP soundings and SPC mesoanalysis reveal that this is a relatively high-quality warm sector, with mean mixing ratios pushing 16 g/kg and decent moisture through a fairly deep layer (up to 700 mb). An earlier tornadic supercell, which was riding along the northern extent of this warm frontal boundary, quickly dissipated a few hours ago as it approached Bloomington, likely as it encountered a pocket of warmer air aloft with 700 mb temperatures analyzed at +9 to +10C. This is indicative of lingering capping, which has thus far suppressed any additional convective initiation attempts in the warm sector. Recent GOES-16 visible satellite loops reveal some towering Cu development taking place across West Central Illinois, however, where capping is lower due to cooler temperatures aloft. Farther to our west, an additional area of bubbling cumulus has been noted across central and eastern Iowa, although recent radar trends suggest incipient updrafts are struggling to develop. Large scale forcing for ascent is not strong here, but modest mid-level height falls (20-40 m/12 hours) are noted in recent analyses nosing into far northwestern Iowa at the leading edge of a very subtle shortwave. It`s possible some lingering mesoscale subsidence is still in place across eastern Iowa in the wake of this morning`s MCS, tempering additional robust convective development at this juncture, but conditions do appear favorable for robust updraft development over the next few hours. With this all laid out, it does appear there may be two favored corridors for potential convective development over the next few hours: /1/ near and south of the incoming warm front and /2/ across eastern Iowa. All modes of severe weather would be possible across our area, including the threat for a few tornadoes. Deep layer shear in excess of 50 kts will support rotating storms and supercell structures and sizable CAPE in the hail growth zone will foster large hail development, potentially to the size of golf balls or even larger with some analogs supporting 2"+ hail not out of the question. Recent runs of the HRRR have been a bit concerning, developing robust storms near the incoming warm front and into the I-80 corridor. Locally backed surface flow would support a tornadic potential with these storms as they interact with the front and gain access to considerable streamwise vorticity. Think it looks too aggressive based on latest satellite trends, but we will need to keep our eyes peeled for development near and south of I-80 during the 8 to 11 PM time frame. The other area of convection--to our west in eastern Iowa--may attempt to develop into our western counties later this evening, likely after 10 PM or so. A tornado threat will continue here, although CAM guidance indicates some propensity for storms to congeal into clusters which may eventually deliver more of a damaging wind and hail threat as this second area of activity pushes eastward into the overnight hours. Finally, a flash flood potential does exist this evening and overnight, although the spatial breadth and magnitude of this threat still is uncertain due to the mesoscale processes involved. Current thinking is that the Flash Flood Watch captures the favored corridor well, and no immediate changes are planned. Carlaw

Full disclosure, JOT went up 4 degrees in the past hour which was the basis for my guess. I really don't know how much of a rise there will be.

Sun out here too. Might be able to pull off about a 4-7 degree rise (?) in temps as we take advantage of late day insolation before temps slowly fall.

Definite northward progress since last time I posted the map

We don't have a big convective complex ongoing, so there is really nothing to hold back the warm front from making a significant northward push from where it currently is. Question I have for later this evening is how long storms will remain surface based/near surface based. The pressure gradient is not all that strong to keep the low levels well mixed after dark... on the other hand, the airmass near/south of the warm front is quite moist to keep the amount of nocturnal cooling somewhat in check so could envision a wind/tornado threat lingering into the overnight... at least isolated.

Warm front is still pretty far south. On a more localized scale for parts of IL/WI, the E/SE flow off of a relatively cool Lake Michigan should further limit a tornado threat close to the lake.