Using GLM

Using the minimum flash area to show where the smaller lightning strikes occur but is associated with stronger updraft with cells building faster (Yellow) to generate lightning. Larger lightning strikes occur in the stratiform area of the precipitation field where charge building is slower (Purple). This is also a good way to indicate convective mode as the system translates from individual (SuperCell) to a linear mode.

(Upper Left – ProgSvr/Ref), (Upper Right – Flash Extent Density), (Lower Left – Optical Energy), (Lower Right – Minimum Flash Area) Note the area of enhancement behind the main convective line. This is stratiform lightning strikes where the charges are slower to build vs. the convective linear line, and individual cells out in front of the storm.
Note the differences from the previous image as the Optical/FED and Minimum Flash Area has less flashes. This is due to the building of the charges.
A four panel of GR2 where reflectivity (Upper Left), and ZDR (Lower Right) depict linear striations (above melting level – 30 dBz) to show the build-up of charges in the stratiform area of the storm. A good way to use it is for IDSS and the likeability of lightning strikes developing.

Using NUCAPS (Modified vs. Unmodified). Why the CAP at mid-levels noted in Arkansas? Is this reasonable or an artifact of the program that isn’t real.

Unmodified
Modified

– wxboy65

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Utilizing NUCAPS Profiles to Analyze the Pre-Convective Environment Across West Texas

WFO Amarillo launched a 19z special sounding today in support of potential severe storms later in the evening. Meanwhile, NOAA-20 passed over WFO Amarillo at 1935z, merely 30 minutes after the observed sounding release but likely about an hour before the full observed profile was complete.

An SPC marginal risk was over west Texas (see below) for the 20z issuance with the main threats being large hail and damaging wind gusts. The 12z observed sounding from Amarillo shows a pronounced low level capping inversion with a convective temperature of around 86 degrees F. Overall, the wind profile is weak with little to no shear but just enough to support a few strong to severe storms. Mixed layer CAPE is around 1000 J/kg, but the downdraft CAPE is closer to 1200 and supports the potential for some strong to damaging wind gusts with collapsing storms and/or areas conducive to strong downward motion.

Image A: 12z Observed Sounding from AMA on June 7, 2021.

Sharppy was then utilized to compare the observed 19z sounding from Amarillo to the closest NUCAPS sounding to the office’s location. Image B contains the values for the observed sounding with the purple representing the sharppy NUCAPS sounding. Image C contains the values for the sharppy NUCAPS with the observed sounding in purple. One of the biggest differences between the soundings that plays a key role in the instability parameters is the surface temperatures. The observed sounding recorded a surface temperature of 83 degrees F, which the sharppy NUCAPS sounding recorded a surface temperature of 89 degrees F. That difference of 6 degrees fully breaks the capping inversion on the sharppy NUCAPS sounding, but the observed sounding still appears to be a few degrees shy of breaking the 750mb cap. The values such as MLCAPE are drastically different with the observed sounding showing around 1500 J/kg, while the sharppy NUCAPS sounding shows ~2500 J/kg. The observed sounding does show an increase since the 12z launch of DCAPE now around 1600 J/kg, but the sharppy NUCAPS does not relay this same increase and instead remains near 1200 J/kg.

Image B: 19z observed sounding (colored) compared to the 1935z sharppy NUCAPS sounding (purple). The values represent the observed sounding.
Image C: 1935z sharppy NUCAPS sounding (colored) compared to the 19z observed sounding (purple). The values represent the sharppy NUCAPS sounding.

So the biggest fault in the NUCAPS values being off was likely the surface temperatures being too warm. In order to validate this reasoning, the modified NUCAPS sounding for this time and location was utilized. However, since the modified soundings are calculated with NSHARP and not sharppy, the original NUCAPS from both algorithms were compared. Image D shows the NSHARP NUCAPS sounding pulled from the CAVE in awips. This can be compared to Image C, which was the NUCAPS sounding plotted with a different program called sharppy.

Looking at the profile itself, the biggest difference that stands out would be near the surface. As stated before the surface temperature on the sharppy NUCAPS sounding was 89 deg F, while the NSHARP sounding reveals a surface temperature of around 80 deg F. The NSHARP sounding temperature is lower than the observed sounding at 19z, but yet was able to mix out the capping inversion. Knowing that NUCAPS in general is not overly impressive with the boundary layer, there is a chance had there been a 12z pass, that the NUCAPS sounding wouldn’t have had such a strong inversion as the observational sounding at 12z showed. Therefore the surface temperature wouldn’t have needed to be as warm. The remainder of the parameters seem to compare pretty well between the two versions of the NUCAPS profile.

Image D: 1935z NSHARP NUCAPS sounding from CAVE.

Now, what happens if the surface temperature from observations are used to modify the NSHARP NUCAPS profile for better representation of that boundary layer. Image E represents this modified sounding where the surface temperature is now closer to 83 deg F, which is what the 19z observed sounding from the same location measured. Comparing this modified sounding to the observed, there is still the issue of the NUCAPS wiping out the inversion layer at around 750 mb. Warming the temperature was not going to bring the inversion back, so this is something that is more a failure starting with the non-modified NSHAPR NUCAPS profile. MLCAPE is still significantly different, but ignoring the inversion in the observed sounding and looking at a surface based parcel, the two soundings are pretty comparable with around 3500 J/kg of SBCAPE. Downdraft CAPE values did not change with the modified NSHARP NUCAPS sounding and this could allude to the fact that again the NUCAPS profiles lack good boundary layer details and a much smoother profile.

Overall, had Amarillo not done a 12z launch, the NUCAPS profiles were pretty comparable to the observed sounding. The biggest concern would be if the purpose was to find if there still remains a capping inversion in place that may hinder storm development. Spoiler alert, storms did develop as temperatures warmed a bit more through the afternoon and were also just a bit warmer further west along the New Mexico/Texas border. A few severe wind reports occurred with the cluster of storms, along with some small hail and maybe even a few larger hail stones of around a quarter that weren’t reported.

– Harry Potter

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Hail or No Hail- Assessing ProbSevere v2 and v3 – Monday case – 2026Z

Today was the first day of Week 2 for the Satellite HWT Experiment.  One of the main applications we are looking at this week is the new ProbSevere Model version 3.  We are able to compare this version to the one currently in use (version 2).  This is the version most operational forecasters are familiar with, and that is available in AWIPS2 and GR2 Analyst.  

The target today was convection occurring in the Shreveport, LA CWA this afternoon.  A QLCS was moving across the region from west to east, as shown below.  The reflectivity was not especially impressive, but velocity scans occasionally showed some stronger winds.

Above: A line of storms moving through Louisiana on June 7, 2021.

The image shows MRMS Vertically Integrated Ice (VII) on the left, a parameter many forecasters are familiar with and may use as perhaps a “sanity check” to see if a cell may be trending towards strong or severe.  On the right is a screenshot of the Shreveport radar (KSHV) at the 0.3 degree reflectivity slice.  Overlaid is the ProbSevere Model with ProbSevere2 and ProbSevere3 parameters both listed for comparison.  

As you can see there are a few areas of concern.  A quick glance at VII indicates there may be some strong updrafts capable of hail over the area of convection over southeastern Caddo County in northwestern Louisiana.  Looking at the output for ProbSevere2 in this same area, there is a 43% chance for hail in this area, and a 14% chance for hail according to ProbSevere3.  The new and not yet operationally available ProbSevere3 uses a newer, more highly-skilled algorithm that should theoretically better match with ground truth.  

During this time there were no hail reports in SPC’s database, severe or otherwise.  There were some areas of surface based CIN noted, and this may have suppressed stronger updrafts and thus large hail. So in this case, it appears that the newer version of ProbSevere was correct about hail not being severe.  

-Dana Scully

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Northern VA/Maryland Convective Episode on 6/3/2021

Image 1: 1943 UTC GOES East Mesosector Day Cloud Phase Distinction

The modified NUCAPS sounding from 1730 UTC revealed in excess of 2,000 J/kg of CAPE (image 2) and by 1900 UTC thunderstorms had developed in an area less shaded by high level cloud cover. Comparing this to RAP mesoanalysis data, it initially seemed too high as RAP mesoanalysis suggested closer to 1000-1500 J/kg (not shown)  and based on initial lightning activity. SBCAPE from NUCAPS was extremely high and close to 4,000 J/kg which seems very high (image 3). We did note that for some reason the NUCAPS forecast image showed CAPE being “missing” over central MD/northern VA while the CIN fill was more complete. When sampled over the “missing” data in AWIPS in the Cloud,  the readout showed actual values.

Image 2: NUCAPS Sounding near Washington D.C.
Image 3: NUCAPS CAPE and CIN forecast at 2100 UTC
Image 3: 2000 UTC 4 Panel of Day Land Cloud Phase

Initially, storms appeared to struggle with flash counts on the order of 10 to 20 flashes. Over the course of 30 to 45 minutes, lightning flash counts increased by an order of magnitude (closer to 100-150 flashes)

Closer to 2020-2030 UTC the rigor of convective elements increased and we started seeing transient echo overhang/along with some weak echo regions in tandem with an increase in both lightning activity as well as ProbSevere trends (especially ProbSevere3) as seen in Image 4. This increased our confidence in issuing our own warnings with LWX having a couple of warnings already issued.

Image 4: ProSevere Time Series just after 2000 UTC.
Image 5: LWX 0.9 Reflectivity Image near 2000 UTC
Image 6 and 7:(LEFT) ProbSevere Time Series around 20:30 UTC.  (RIGHT) 4 Panel (from top left to bottom right) of Day Land Cloud Phase Distinction, Radar+GLM FED, Day Land Cloud Convection + TOE, ProbSevere3 + GLM MFA

Closer to 21:50 UTC things became a bit more interesting from both a radar and lightning standpoint. Imagery from the KDOX radar (Central Delaware) suggested increasing mesocyclogenesis across Baltimore County (image 8) due north of Baltimore.

Image 8: 20:48Z 0.5 degree cut from KDOX indicating low level mesoscyclone.
Image 9: 4 Panel of ProbSevere, GLM FED, GLM MFA, GLM TOE at 20:45 UTC
Image10: 4 Panel of ProbSevere, GLM FED, GLM MFA, GLM TOE at 20:51 UTC

From a comparison of these images, there was certainly an indication that the updraft was increasing  as FED magnitude increased from 51 flashes/5 min to 99 flashes/5 min. MFA also became more concentrated NW of the City of Baltimore and Baltimore County as seen in images 9 and 10. WFO LWX issued a Tornado Warning around 20:51 UTC.

An animation of the TDWR at Baltimore Washington Airport (image 11) had signs of a possible low-level RFD surge (not shown) in the 0.5 degree rapid scan tilt and increasing low level rotation consistent with either a stronger surge of straight line winds or a QLCS mesovortex/tornado. Aloft, (not shown) there did appear to be healthy reflectivity aloft and the concentrated MFA may suggest that a strengthening updraft.  

Image 11: TBWI 0.5 Reflectivity and Velocity image at 20:50 UTC looking at tornado warned storm.

Image 11 from KDOX shows a loose mid-level mesocyclone with a gradual increase in ProbSevere3 with the time series. In this image, the storm was currently tornado warned by WFO LWX. At time we’d likely opt for a tornado possible warning and monitor very, very closely.

Image 12: 21:02 UTC Showing ProbSevere Time Series with KDOX 0.5 data (left panels) and GOES/GLM data (right panels) + ProbSevere

By 21:13Z The storm of interest is looking LESS favorable for tornado although prob severe tor increased significantly to closer to 20% perhaps due to an elongated zone of low level shear.

Image 13: 21:13Z KDOX Radar Imagery

Prob Severe Table Ideas:  If the tables could open in a floating tab in Awips that would be very helpful. This way you can manually dock and move the tab around in awips. This way you can quickly view the tab and keep it open until you want to just close it.  You can also rename the tab to whatever will help you keep track of the storm that it belongs to. This would get around needing to color code multiple tables etc.

A separate tab will also allow room to show additional information (beyond just prob severe).

Prob Severe jumped to nearly 80% with a fast moving bowing segment through Montgomery County.

Storm in question is the southeastern storm here.

– By Miles and Dwight Schrute

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Observations over the Sterling CWA

Looked at the modified NUCAPS sounding for and the low levels, below 700mb, were un representative (had an inversion when SPC mesoanalysis had no CINH), however the sky had roughly 80% cloud cover.

NUCAPS Base Sounding
NUCAPS Modified Sounding, Same Location as Above

Looking at the NUCAPS forecast, the holes in the output field due to the cloud cover.  The lack of data was in a bad location, preventing us from seeing the instability potential for a line of storms coming in from the west.  The gridded format was actually better to use in this case as it helped fill in the gap.

Interpolated CAPE NUCAPS Imagery

The interpolated data is easier to visualize gradients in the variables, but our experience was that some important data was filtered out by having this turned on.

The time in the lower left is 19.99z.  A key for the “all” field would be helpful to understand what I am looking at.

Having the CWA borders is handy, however having it as it’s own layer would be more helpful, and separating out the CWA borders from the state borders.

Can storm names be used to correlate the time series (F6, D3) and also have the names plotted in AWIPS for the storms I am looking at a time series of; would be more beneficial than having the lat/lon

-for example, click for a time series of one storm triggers a storm ID to show up in the time series and in AWIPS

-I click another storm and another time series shows up with the storm ID in the time series and in AWIPS allowing me to see which time series goes to which storm

If prob severe and its time series could be put into GR that would greatly improve DSS services when outside the office.  The AWIPS thin client is sloooow, so being able to have the same ability, or similar ability to interrogate storms as in the office would greatly help improve the quality of DSS when deployed.

Prob severe version three continues to look more reasonable for severe wind than version two

Noticed an increasing 5 minute trend in the minimum flash area that was reflected in the FED about 5 minutes later.  Seeing the sustained increase in one minute minimum flash area caused me to pay more attention to that storm than I did earlier due to the sustained growth

While monitoring a storm with FED and minimum flash area, the FED suddenly went down.  The same trend was not seen in the minimum flash area as easily.  Maybe the minimum flash area is more useful tool for monitoring the growth of storm while the FED is better suited for monitoring the overall trend in storm strength and sudden weakening.

Downward trends in FED for one of the storms matched what was being seen on satellite of the storm updraft becoming more ragged as it weakened due to entraining dry air.

-would be great to have lightning data such as FED plotted in a time series as well so trends are more easily seen

The stronger storm we were monitoring (same as in the screenshot below), prob severe version 3 was higher than version 2 for 15 minutes atleast.  Looking closer this was due to the hail category being higher than version two; version three was also higher than version two in the wind category, but not nearly as much.  Toward the end of our time version two was higher due to higher probabilities in the wind category.  Interesting.

We monitored this particular cell on and off throughout the afternoon and tried to gain a better understanding of the minimum flash area. We noticed a close cluster of negative strikes, which really helped as a visual aide for what the GLM was seeing. The GLM MFA was able to isolate the core of the storm really well. We combined this with ProbSevere, and watched the probabilities on this storm increase which was a further confidence booster that the storm was intensifying in addition to what was seen by GLM and ENTLN.  

– Accas and Groot

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Day 2 thoughts

NUCAPS…

Can there be a circle (or some reference) around the NUCAPS point that I am currently using for a sounding?  That way I have a reference on the map for where the sounding is that I am looking at.

Can more than two NUCAPS sounding be loaded into an AWIPS pane?  If so, would nice be able to compare soundings/environments more easily.

Having the ability to display one NUCAPS sounding when I have two loaded in Sharppy would be helpful.  Even when loading two soundings and only have one in “focus” the two soundings overwrite each other.  Can this setup be similar to AWIPS that allows us to have multiple soundings loaded and be able to turn one or both of them on when we choose?

Compared a couple NUCAPS soundings surface conditions to the obs for a couple locations and they look reasonable.

Looking at the forecast CAPE/CIN from NUCAPS, the gridded field for CIN is quite splotchy.  Bulls eyes of much higher CIN seem overdone compared to what is expected during the mid afternoon with full sun and with what the SPC mesoanalysis has.  This would make me question how accurate it is.   Looking at the forecast, there is no consistent trend with the CIN bulls eyes, which lowers my confidence in this field. The CAPE field is more uniform, though still splotchy.  The areas of higher CAPE are more consistent, giving me more confidence in this field than the CIN.  Is there a way to average out this field more to make it smoother?  If so, that would greatly increase my confidence in this parameter and my likelihood of using it in the future.

Noticed the surface based CAPE in AWIPS vs. Sharppy was quite a bit higher in Sharppy.

Compared the ML CAPE in a modified NUCAPS sounding in AWIPS and an unmodified NUCAPS sounding in Sharppy and the modified lined up much more closely with the SPC mesoanalysis page.  The the ML CAPE in the unmodified sounding in Sharppy was too low.  Surface based CAPE was actually more representative in the unmodified sounding.

As mentioned earlier, would be nice to compare more than two sounding points for NUCAPS to aid in comparing the environment more easily.

Having the NUCAPS 2m temperature and DP in F instead of C would be much more useable and easier to compare to surface observations.

Noticed the 2m temperature for the gridded NUCAPS was cooler by 5-8 C compared to the observations.  This makes me looks confidence with the CAPE and CIN plots if the surface temperatures are not accurate.  Is there a way to grid the modified NUCAPS data?  When I forecast I like to view parameters in a gridded fashion in the horizontal.  This helps me better understand what is going on with the environment.

Compared the NUCAPS 700-500mb lapse rates to those on SPC’s mesoanalysis page and found the NUCAPS was close, but on the cool side.

In our data sparse CWA, I can see these soundings as being quite useful, as long as forecasters understand the low levels (assuming below 850mb) are less likely to be representative.

Taking a look at the minimum flash area…

Difficult for me to really see any sort of trend with the 1 minute data.  Nothing really catches my eye.  The 5 minute data is much more easy to see trends.  

As mentioned yesterday, am able to see more valuable information with trends in the storm than with flash density.

 

Looking at the optical winds…

The background is a bit too dark.  Can the Lat/Lon be put below the imagery?  Having it above seems to detract from what is being displayed.  Adding state borders, cities, would add to the usability of this product, especially if these labels can be turned on and off.

I like being able to pan the image.

I can see this being handy for monitoring for LLWS for aviation, assuming there are clouds to track.  Could this data be merged with NUCAPS to plot shear and helicity?   

Changing the density of the vectors would be handy.  

Color coding the different levels and matching it to the key is easy to determine what level I am looking at.  

Could this track the speed of dust?  If so, could help determine how strong the winds are in dust storms.

Curious why the pressure levels are broken down into 200mb intervals.  Could the winds also be tied to theta levels to help with isentropic analysis?

Having contours for the winds would help limit information overload as far as what is being shown.  Being able to control the density of the number of wind vectors would help, however that could lose some data.  Contours of the wind vectors, say every 5 or 10 kts, could help summarize what the individual vectors are showing.

 

-Accas

Sampling of Sub-Severe Convection Across the Southeast

Modified NUCAPS sounding appeared to have a better handle on the environment compared to baseline NUCAPS sounding. However, it also appears it might not be totally representative of the atmosphere given the partly cloudy conditions at the time RTMA data was pulled in. The SPC mesoanalysis page suggested MLCAPE upwards of 2500 J/kg in an uncapped environment.  Using the gridded mid level lapse rate product from NUCAPS we found the data to be representative. It verified well with what was shown in the NUCAPS soundings and matched with the values suggested by the SPC Meso Analysis page.

MODIFIED SOUNDING 1927UTC – WEST HINDS COUNTY, MS
1927UTC BASELINE SOUNDING – WEST HINDS COUNTY, MS
21UTC 700-500MB LAPSE RATES

The NUCAPS mid-level lapse rates were fairly representative when compared to the SPC mesoanalysis page. This was further evidence that large hail was probably not going to be in the cards for the Jackson area today, but marginally severe wind gusts would be something to watch.

16 UTC 700-500MB NUCAPS GRIDDED LAPSE RATES, SAMPLE NEAR THE SOUNDING DATA POINT

Prob Severe version 2 vs version 3, particularly in prob severe wind:

In this event, the prob severe there was a sig wx statement and severe thunderstorm warning put out by the Huntsville office. Around that time, the prob severe was increased specifically for the prob severe wind component. The version 2 had a prob severe value of 3% while the version 3 had a 53%.  Version 3 better captured the significance of the storm with a 40 mph gust reported around the same time.  This is significant since we were also discussing how filtering lower prob severe thresholds would be useful in decluttering the operational screen. We could have missed this event if that was the case (with version 2).

Based on this experience, we can see the vast improvement in the wind component of prob severe version 3.

21:16 UTC ProbSevere Sample (note V2 versus V3 differences in sample).
Local Storm Report of a measured 41mph wind gust in Colbert County AL, just north of the contoured ProbSevere storm.
1 Minute FED overlaid with ENTLN 5 minute (1 minute update) and GM Flash Point

GLM Observation:

Saw a steady lightning jump depicted in the GLM FED correlated with a storm that NWS Huntsville issued a Severe Thunderstorm Warning on. Several mPING reports of wind damage (assuming sub-severe with no LSRs issued as of this time) which raises confidence that storms are intensifying. Perhaps the most interesting thing about this screenshot is seeing the parallax-correction in action when looking at the Flash Points.

Optical Wind:  

Still difficult to tell where you are geographically.  Suggestions to perhaps swap the lime green grid with the state outline colors.

Additionally, the time stamp gets cut off if you zoom in on the product and occasionally gets covered by the wind barbs themselves. Perhaps a floating time stamp would be better for this instance.

Time stamp for the image above.

A note about the timestamps:

The time stamps attached to the wind barbs appear to be formatted incorrectly, showing times like 21.97Z, note the actual time correctly formatted shown in the image below was actually 21:58Z.

– Groot and Dwight Schrute

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NOAA-20 Pass Ahead of Severe Convection

The San Angelo CWA was expecting severe convection in the afternoon.  There was a NOAA-20 pass over their CWA at 1927Z.  A NUCAPS Sounding in the clear air ahead of ongoing convection was chosen.  The approximate point of this sounding is shown by the white circle in the left image.  The sounding in the right image showed an environment very favorable for severe convection, including hail.  Since ongoing severe storms were heading in this direction (left image), the storms could be expected to maintain their intensity or possibly strengthen.

– Champion

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