All Sky LAP CAPE Too High?

Just prior to 20z the All Sky LAP CAPE shows 1000-1200 J/kg of CAPE across eastern ID.  However, most of this is in a cloudy or GFS layer depiction.  Looking at the GOES 16 derived CAPE, it only shows a narrow region a calculated data in eastern, ID that is about half (500-600 J/kg) of what is shown by the All Sky LAP.

All Sky LAP CAPE.

GOES 16 CAPE.

Pocatello Storms

We're currently monitoring conditions in eastern Idaho. Right now I'm using various applications to analyze and initialize current conditions. Currently AllSky is showing cape around 1000kj, and PWATS around .80 inches.



That PWAT value on the morning sounding just west of the area was close to .64". Seeing how moisture levels are lower to west I can interpolate that the moisture values are similar to what's show on allsky. The allsky 900-700mb also seems to pick up on the relatively moist area in the lower half of the atmosphere.



Looking downstream we're noticing a line of developing convection using the Day land cloud RGB. It's helpful to analyze just how high the tops of the storms are getting combined with cloud tops.
Zooming in closer I can examine the few storms that have popped up more closely. The RBG help the differentiate between the ambient cirrus clouds from the growing storms. That might not have been as easy to see using a typical visible view.



The AFA and Minimum flash area maximums are hinting at growing convection just downwind. That growth leads to me to anticipate further growth as these storms move into a more favorable environment in eastern Idaho.

EWX Mesoscale Discussion

AllSky_LAP ML CAPE Forecast as of 1930z

19z Surface analysis shows the nearly stationary effective dryline boundary draped SW to NE across the CWA from roughly Del Rio through Briggs, TX. This boundary continues to play epicenter for semi-discrete super-cellular development this afternoon, with additional cold pool driven activity likely to form over the next few hours, especially as a back door cold front begins to slide southward through south-central TX. Latest AllSkyLAP CAPE analysis shows destabilization continues southeast of the dryline, with ML CAPE values nearing 3000 J/KG in and around San Antonio as of 19z. TPW values also remain relatively high southeast of the boundary, with 1.5 to 1.75 inch readings common place. Mid to upper-level kinematics remain favorable for some supercellular structures, so we'll continue to  keep large hail, damaging winds, and an isolated tornado threat in the forecast. Best chance for seeing a tornado (even with relatively week 0-1km shear values) will likely be through 7pm tonight in a cells that can remain discrete for awhile. Flash flooding concerns will continue thanks to the abnormally high PWAT values, especially in areas that see several rounds of convection this afternoon and evening.

----------------------------------------------------------------------------------------------------Mountain Bone

Modified Sounding for RIW

Modified the RIW 12Z sounding for low 70s over around 40 in the southwest WY area, and got an MUCAPE of 655 over  A little higher than what AllSky is showing there...


...around 200 in the image above.

Charley

Derived Products Comparison

Merged TPW, image above showing an area of higher TPW, 0.5-0.6 in PIH's area, with values of 0.25-0.4 more over RIW.  AllSky product shows a little more variation, with a drier airmass, 0.15-0.25 inches moistening up over the course of a few hours, over the western border to 0.5".  Also seeing those values in the far eastern part of RIW's area.



Total Totals are ramping up over time in the AllSky product, from around 40 to a more severe 55. LI's also are going negative.  K index also going for some storm activity, getting to the mid 30s.  CAPE's are higher over PIH, but likewise rising across the region...with a similar max in the eastern RIW area.

Charley

Storms tracking toward St. Louis

A line of storms is north of St. Louis as of 630 pm CDT and is tracking southward toward an area of increased CAPE per All Sky LAP product.  This convection continues to trigger along the leading outflow.  The overall environment has limited shear so it is primarily cold pool driven.  ProbWind has consistently displayed around 65-78% since around 600 pm CDT.

TPW in a convective environment

Below is a comparison of two different TPW products (AllSkyLAP layer Precipitable water and Merged TPW Composite Sat Sfc Merged Total Precipitation Water) compared to RAP Analysis from the SPC Mesoanalyst page.

Control group: SPC Mesoanalysis Precipitable Water

The AllSkyLAP product (below) seems to do a better job at "painting the picture," however, it's reliance on the GFS model often leads to a delay in PWAT drops in areas of convection. This is highlighted the best across central IL, where RAP Analysis shows PWATs in the 1 - 1.25 inch range while the AllSkyLAP product shows values closer to the 1.5 inch range straight from GFS output.

AllSkyLAP

TPW (below) does a better job at accounting for this, at least across the central IL study area, resulting in more realistic 1.1 to 1.3 inch values.

TPW

Comparing Operational Derived Products

Total PW looks good from the operational version (minus the blacked out data, of course).  It is a little blotchy on the merged TPW (left).  A similar comparison below of the AllSky TPW and Operational product.



CAPE is a different story.



AllSky calculations are mostly in a clear airmass, as you can tell by the operational product not being blacked out.  Peak values on the right are in the 1700-1800 J/kg range, whereas points on the left peak at 2600-2800.

Charley

Another rise in mid-level moisture on AllSky Layered PW

Similar to MPX area yesterday, the 0.9-0.7 sigma level LPW product had an area ahead of the line of storms that had increasing moisture.

Similar Soundings

Modified NUCAPS sounding near ILX is pretty similar to KILX special sounding taken at 17Z!  MUCAPES both around 3000 and LI -9.
Values similar to AllSky at 18Z.




Those CAPE values near 2500 J/kg...also similar.
This similarity gives us some confidence in new forecasts, especially in clear sky regions out ahead in the AllSky data.
The forecast NUCAPS CAPE does not show much to the south of our line...and based on clear skies and warm conditions to the south would tend to lean away from this forecast.



Charley

Springfield Illinois Storms

Right now I'm analyzing the various new products to nowcast where and when storms will intensify. Currently I'm comparing ALLsky cape to the mesoanalysis from the spc. Right now the mesoanalysis is higher with cape compared to allsky. Over our area the it's cloudy so the it's taking data from the GFS.

A cell in our western counties ramped up very quickly while our computers were down. Prob severe immediately directed our eye to the cell. The probsevere lined  up with an uptick in vil values and the threat for damaging winds



I'm comparing the actual sounding to what's shown on nucaps, and allsky. Trying to see what's initializing the best. The actualy sounding shows 3000kj of cape around 17z.



Around the same time allsky shows a similar value of cape.



Here's what the modified and unmodified nucaps are showing.
I'm also looking at GLM products to see trends with convection. The combination of event density and glm minimum flash area help me to see the rapidly growing updrafts as well as cell that are producing hail. That's the case right now. My warned cell is producing penny size hail.

NUCAPS Soundings indicating much higher CAPE than All-Sky values

The All-sky CAPE product has shown a pool of lower CAPE values (1200-1300), probably a result of earlier collapsed convection. However, values of CAPE farther down in the southern IND CWA are a little higher (1800-2200), as would be expected.  More interesting is the latest modified NUCAPS pass with soundings indicating much higher CAPE values on the order of 3500-4000 in the south and 1800-3500 elsewhere in the central and northern IND area. Based on this information, I'll be expecting to see convection flaring up in the south in the next hour or so.

ILX All_Layer CAPE Comparison

Taking a look at a quick comparison example of when the model fill-in of the All_Sky CAPE product may not be the best solution. In this example, an ongoing MCS was diving south through north central IL earlier this morning before it dissipated rapidly over the central part of the state. The GFS model struggled depicting the rapid de-escalation of said storms, and attempted to stabilize much of the ILX CWA in its wake. Unfortunately, this led to quite the gradient between areas where clouds prevented in-situ satellite observations to be utilized in the All_Sky CAPE product. Taking a look at the SPC Mesoanalysis (RAP) output in image 2 for comparison, the more accurate CAPE values across eastern IL should be closer to the 2500 - 3000 J/KG range while the ALL_Sky CAPE layer (Image 1) is showing 1000 - 1500 J/KG tops. A suggested best practice to overcome this discrepancy is to  include the AllSkyLAP Layer Cloud Type Image underneath any AllSkyLAP product so you can easily depict what is sensor derived and/or model output.

---------------------------------------------------------------------------------------------------Mountain Bone

AllSky CAPE high in one place low in another

cells persisting in far western CWA has high CAPE on latest AllSky product.  However, the line of storms that moved through the middle of the CWA is now in the eastern part and into ARX's area.  Line continues to look severe, with AWOS in northwest ARX gusting to 52 knots, but CAPE not as high.

CHARLEY

All Sky LAP CAPE and NUCAPS forecast contrast

A vigorous line of storms was moving into the NW corner of the ARX CWA prior to 23z.  The All Sky LAP CAPE showed decreasing values (~1100 J/kg) heading into this region.  In contrast, the NUCAPS forecast (un-interpolated image shown) depicted values of ~3000-4000 J/kg.  Based on the initial behavior of the storms, the higher instability values in the NUCAPS appear to have better verification.

LSX Mesoscale Discussion (Mountain Bone)

Ongoing sub-severe convection continues to develop along a decayed MCS boundary. This convection is primarily located along and south of the I-70 Corridor as of 2130z, but continues to press east into a favorable environment for continued/sustained convection, characterized by modest Instability (1400 - 2000 J/KG ML CAPE) according to All-Sky LAPS derived CAPE values and near 70 degree dewpoint temperatures. Kinematics continue to be unimpressive, with the majority of the forecast area remaining in an area characterized by sub-40kt bulk shear values with little to no sfc-1km effective shear layer. A stray embedded strong to supercellular storm will remain possible this afternoon and evening as the multicell cluster continues to fill in and push east, especially with the arrival of a weak LLJ feature which may help to organize/ strengthen the area of convection by 00z/7pm CDT. PWATs (1.5 to 1.75inches) continue to increase, especially across the low to mid-levels, which could support some isolated heavy downpours which may lead to additional flooding. Primary threats: Strong winds, small hail, and flooding rains.
-----------------------------------------------------------------------------------------------------Mountain Bone

Springfield Storms

We're currently analyzing storms developing in the Springfield Missouri WFO.  Right now I'm using various tools to monitor if these storms will become severe.
Right now I'm using a combination of radar, GLM, nucaps, and the All sky products. Currently the most helpful tools on top of what I normally use are allsky and the lightning products.
The allsky cape helped to find CAPE gradients and an increase in CAPE. The northern batch of storms were pushing into an area of increasing CAPE and in return they did intensify.



While deciding whether or not to issue a warning I also looked at AFA GLM data to see if there were new flashes developing which can be indicative of growing convection. That flashes aligned with radar and increased my confidence that storms would intensify.



That lead to me issuing a severe thunderstorm warning. The prob severe data also ramped up. So I felt confident about my warning.

EAX Near-Term AFD (Mountain Bone)

A decaying MCS continues to progress northeast across the central portions of northernmost Missouri, allowing for destabilization to begin in its wake. This is especially true along and west of Interstate 35 in NW Missouri/eastern-most KS where clouds have cleared for several hours according to GOES_East Channel 2 imagery. With in-situ observations showcasing upper-60s to low 70s dewpoints at the surface across the central and eastern portions of the state, it likely won't take much in the way of surface heating to allow for convective initiation this afternoon and evening.  Based on downstream NUCAPs soundings, rather robust SFC CAPE values in the 3000 - 4000 J/KG range will likely spread northwestward with time, which should be ample to support some convection this afternoon and evening. Best (early) thoughts on initiation location this afternoon will be across the easternmost portions of the CWA along a line from Boonville to Centerville along the eastern most periphery of the nearly stalled MCS, which could provide for enough lift to get things firing by late afternoon and evening. Also keeping an eye on a downstream shortwave clearly evident in GOES_East water vapor imagery which could push an additional round of multicellular convection through late this afternoon and evening. Most likely to brush the southern and eastern portions of the CWA, which currently finds itself adjacent to a severe thunderstorm watch extending to its south and eastward.

Any storms that do form or push into the area should have plenty of moisture and instability to sustain themselves. All_Sky TPW and NUCAP soundings show a plume of 1.3 to 1.5 inch PWATT values extending north throughout the entire CWA, which also brings the concern for some additional flooding, especially across the southeastern portions of the CWA which will likely see more numerous coverage of storms. Low 0-1km and 0-6km effective shear values should limit the presence of sustained supercells, however, a strong to severe thunderstorm or two will remain possible this afternoon and evening.
-------------------------------------------------------------------------------------------------Mountain Bone

Watching to the west again

Where AllSky says LI is -8, new development on IR.

NUCAPS All Sky LAPS contrast

A modified NUCAPS sounding depicted a LI of -3 in the wake of the convection in the NW corner of the MPX CWA.  This is within an area of more cloudiness and the All Sky LAP derived product is using GFS in this area, and shows a more unstable environment with a LI of -7.