Lightning Increasing

A storm has quickly intensified north of the storm I had warned.  The once severe storm has quickly decreased (as shown by the ProbSevere numbers getting very low) and the warning will expire.  I'd put a special statement on the intensifying storm based on the increased ProbSevere and the lightning spikes. Here is the 4 panel I used from GLM.

I used the GOES 16 Visible imagery to see where the strongest updrafts were compared to the lightning intensity.  The overshooting tops seemed to show where the spikes were in GLM. 

-Penny Gardens

MAF - SVR issued based on increase in lightning activity

2300Z: I decided to try & get a jump on the storm east of the already warned one in eastern Jeff Davis county. GLM was my primary tool used in deciding to issue a warning based on an increasing trend I began to notice around 2230Z. between 2230 & 2250 Flash density increased from 10 to 30 & total energy from 50 to over 100. The animation below I could have issued a warning even earlier when I first noticed this increase in lightning activity but waited until I saw more of an increasing trend in prob severe. ProbHail was at 6% when I first noticed the increased lightning trend & I waited until I saw an increase to 14% & MESH increasing from 0.5" to 0.74". At the same time I noticed a cooling trend on cloud tops on the GOES 16 clean window IR which added even more confidence to the lightning data that this storm would continue to intensify. Unfortunately I fumbled around with WarnGen a bit so my warning wasn't actually out until 2051Z but I made up my mind on issuance & began the warning process around 2040Z

GLM 4 Panel animation:

Around 2300Z the storm became more obviously severe with ProbHail of 84%, ProbWind of 68%, & MESH of 1.38".  I'm not anticipating receiving any reports out of this storm given the sparse population in that part of TX but given those numbers I would certainly consider this storm a severe candidate. Taking a look only at "conventional" storm interrogation products such as 50 dBZ height for 1" hail & isothermal reflectivity at -20C I don't think I would have made a decision on warning the storm until the 2255Z scan. Shortly after 2300Z the storm even took on supercell characteristics & began a turn to the right which certainly would have resulted in a warning. GLM products & ProbHail/ProbSevere without a doubt added value to my warning decision making in this case.

Of note is how the GLM fields actually decreased towards the end of the above loop despite the storm seemingly reaching it's peak intensity. I noticed similar trends yesterday watching storms in ABQ so this may be unique to GLM & storms out west.

UPDATE (2045Z): decided to reissue on this storm given  a steady trend in high GLM Flash Density Values, Prob Hail over 60%, & MESH near 1.5". Below is a 4 panel animation of the GLM fields/ProbSevere/& a MRMS 1km RALA over the whole period I was actively watching it.

Peter Sunday

Severe CI Prob vs CI Prob in central OH

Just took a look at an area where some convection developed across central OH. The Severe CI Prob product indicated a low potential for severe TS development, which appears to have been the case. The CI Prob product indicated > 50% chance of CI for 3-4 consecutive time periods. Convection did develop in the area, which, interestingly looks like it was in an area of outflow boundary convergence (at least, it looked like that to me on the vis sat imagery I used in conjunction with the CI products).

2002Z (note the somewhat continuous, but still splotchy, areas in green, especially S of the broken line of convection):

2007Z:

2012Z:

2037Z (A few cells with reflectivity values > 50 dBZ have developed within the "area" that the CI Prob highlighted as > 50% for more than 2 consecutive time periods):

 - Thomas Bell

Updated storm warning

I took a chance and continued a severe t-storm warning for the western cell.  My teammate is tracking the eastern severe storm.  I put 60 mph winds, quarter hail & lightning as the hazards in warning text. Storm is barely moving but building southeast. After the warning was issued the hail spiked again in the ProbSevere. Again a confidence booster on that one when the numbers match why you warned.

Update: the NWS actually reissued their severe t-storm warning for 60 mins due to golf ball size hail & 60 mph winds.  On the ProbSevere the MESH only showed up to 1.4in.  NWS said 1.75in.  No reports of hail. This storm is in the middle of nowhere.

-Penny Gardens

Storms Getting Their Act Together As They Depart WFO Sterling Area

[23:00 UTC] Convective activity has really increased over the past 30 to 45 minutes as it begins to move out of the Sterling VA CWA. Convective initiation and intensification has occurred along an increasingly-concerning bowing segment that has moved into the far northern portions of the Wakefield CWA.

Radar imagery would also suggest a developing MCV in the extreme southeast portion of my CWA, most likely aiding in convective enhancement along the arcing line to the south/southwest of the MCV.

As expected, GLM flash extent density and total energy has seen a marked increase over this time period, coincident with colder IR temps (indicating stronger updraft development).

Rosie Red

GLM During A Few Severe Storm Clusters

A severe t-storm warning continues on the cell with the highest ProbSevere. Other cells are starting to develop around it, which is why GLM is showing lightning data around the severe part of the storm.  I like using the ProbSevere over the GLM for reference.  It again shows that the lightning hazard can be well outside of the severe part of the storm. 

-Penny Gardens

Severe T-storm Warning

I issued a severe t-storm warning for a cell that was developing really fast.  I noticed the NWS put out a special weather statement.  So I tried issuing a warning.  The same time I put it out for 60 mph winds & penny hail, the NWS issued one too.  The ProbSevere rapidly increased (snapshot below) & hail spike showed up on radar.  The ProbSevere definitely showed confidence that the warning was justified.

\

-Penny Gardens (PG)

MAF - Comparison of low-latency & modified NUCAPS soundings

2200Z: While waiting on convection to develop I decided to do a comparison of the low-latency NUCAPS sounding & the slower but boundary layer corrected NUCAPS sounding. I looked at a "green" sounding point just south of KMAF at the 1932Z NOAA-20 pass. For ground truth, the 19Z observation at KMAF was 82 T/58 Td.
SPC mesoanlysis values at 19Z were:
SBCAPE: 1500-2000 J/kg
MLCAPE: 1500-2000 J/kg
MUCAPE: Slightly less than 2000 J/kg

SFC-3 km Lapse rates: 8 C/km
500-700 mb lapse rates: ~6.5 C/km

The low-latency, uncorrected, NUCAPS sounding was much too cool at the surface with a satellite derived surface observation of 76 T/60 Td. However CAPE values were still in line with the SPC mesoanlysis, potentially because the mid-level lapse rates were likely too steep on the NUCAPS soundings

SBCAPE: 1768 J/kg
MLCAPE: 2036 J/kg
MUCAPE: 1680 J/kg

Sfc-3 km lapse rate: 7.7 C/km
850-500 mb 7.3 C/km

Unmodified NUCAPS sounding:

The modified NUCAPS sounding was much closer to the ob at KMAF with a NUCAPS derived sfc ob of 82 T/ 58 Td. CAPE values & lapse rate values were also closer to SPC mesoanlysis which is what you would hope for.

SBCAPE: 1841 J/kg
MLCAPE: 1657 J/kg
MUCAPE: 1841J/kg

SFC-3 km lapse rate: 8.8 C/km
850-500 mb: 7.9 C/km
700-500 mb: 6.6 C/km

Modified NUCAPS sounding:

I still continue to place much more confidence in the modified soundings vs the low-latency unmodified ones. The soundings performed much better today vs yesterday compared to mesoanalysis values (which of course are not ground truth by any means but are about as close as we can get with traditional products). Personally, I would not anticipate myself using the low-latency soundings much knowing that the more accurate modified NUCAPS soundings are only an hour or two away. However I find a great deal of value in both the corrected NUCAPS point soundings & gridded fields in analyizng the early afternoon environment.

Peter Sunday

Looking at 4 RGBs at the same time

For the sake of comparison, I loaded a 4-panel loop with the following RGBs: Air Mass, Differential Water Vapor, Day Cloud Phase Distinction and Simple Water Vapor. Doing so really slowed AWIPS-II down when they were loading, so if you try this, please be aware of this!

All 4 RGBs contain A LOT of useful information. A few examples:

1. When comparing the Air Mass and Day Cloud Phase Distinction RGBs, if there are no (or few) high clouds, low clouds can be distinguished fairly well, such as what can be seen in southern WI and southern MI in the image below.

2. High cloud is very easy to distinguish in both the Air Mass and Day Cloud Phase Distinction RGBs, especially when used in tandem. Even when thin, high cloud moves over an area of low clouds, both types of clouds are fairly easy to see, such as over northern IL below. Interestingly, the color schemes are a bit "different", with high cloud showing up as whiter in the Air Mass RGB, while high clouds are seen as a yellow-orange-red color scheme in the Day Cloud Phase Distinction RGB. That's a bit confusing, but manageable to the discerning eye.

3. Drying in the mid- and upper-levels is also very easy to see when comparing both the Differential Water Vapor and Simple Water Vapor RGBs, such as what can be seen across the western/central Great Lakes extending SW (excluding the high cloud moving across IN/IL/IA/N MO). Certainly, if one knows where low-level boundaries and other significant storm parameters/signatures are located, one could use the Water Vapor RGBs to help forecast potential convective development as drier mid-upper level air moves over those regions. This is definitely evident over OH in the image below.

 - Thomas Bell

GLM Average Flash Area (5-min/1-min Updates)

[22:00 UTC] In watching the march of convection across the Sterling CWA this afternoon, I started to take a look at GLM data a bit more closely. More specifically, started looking at GLM Average Flash Area (5-min/1-min updates) with the cluster of ongoing convection. It was noted that, in general, the more intense convection had lower Average Flash Areas than the more marginal updrafts/convection.

For example, in the below animation, towards the beginning, the more intense convection (and more robust updrafts) were in the SW part of the CWA. But as the afternoon progressed, the most intense convection actually developed in central and east-central parts of the area, with the activity in the southern part of the area a bit more marginal in nature (note in animation the yellow/light orange colors in the south (and even just outside/south of the CWA) with the darker magentas/blues more in the central part of the area (associated with strong storm activity)) for the second half of the animation.

With this, it was noted that as storms were developing/strengthening, the flash area was relatively small, but slowly spread out (increased flash area) as the storms matured and even passed maturity (began to decrease in intensity). Towards the end of the animation, the flash area seems to be decreasing across the cluster, which is supported by a more ragged appearance to the convection on KLVX 0.5 degree Z.

Fig. 1: GLM Average Flash Area for several hour period in Sterling CWA

Rosie Red