Category: GLM

Sampling of Sub-Severe Convection Across the Southeast

Posted in GLM, News, NUCAPS, Optical Flow Winds, ProbSevere on by Kevin Thiel.

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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GLM Flash Point Product

Posted in GLM, News on by Kevin Thiel.

The GLM Flash Point is a unique addition to the GLM suite of products.  It’s parallax corrected, which is nice.  But the points seem to tell you less data per minute than the FED.  In this example there are eight points for the Sterling/Irion County storm.  However, you need to mouse over each point to get more data (flash duration and area).  By comparison, the FED quickly tells you this is an electrically active storm.  In a warning environment, with limited screen space, and where every second counts, the FED tells you a lot more very quickly than the Flash Points.

– Champion

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Mesoanalysis summary for E CO

Posted in GLM, News, ProbSevere on by Kevin Thiel.

Looking at a surface map there looks to be a boundary, possibly a weak warm front, over E CO that storms are firing off of.  A similar feature can also be seen in the satellite data taken at the same time.

Lightning:

The FED did not give as much information about the growth stage of the updrafts as the flash minimum area did.  Also noticed the VII trend resembled a similar trend as the flash minimum area did.

The flash minimum area is also a good way to help catch the eye of what updrafts are strengthening, especially if the trend of low flash minimums persists.  Great tool to use at first glance of which storms need to be watched and which don’t.

-Dwight Schrute and Accas

Saw several examples of the flash density for lightning either muting out or not showing the trend the flash minimum area was showing.  In the past I have been using the flash minimum area to help me see trends in the lightning, but am now seeing that I should be using the flash minimum area instead if I want to see trends in lightning activity.  I use the lightning trends to help me know if the storm is rapidly intensifying or suddenly weakening and possibly about to generate a severe downdraft.  Being able to see these sorts of trends better can also help communicate a potential threat for storm intensification or severe wind development to those in the path of the storm.

-Accas

Area of coverage greater for the  minimum flash vs extent density.

MRMS and Satellite indicating glaciation (the small updraft in the center of the satellite picture). Lightning expected, but only seen potentially with the minimum flash area product and not with the flash extent density product. Until one scan later (shown below).

Next time stamp, we can see increased minimum flash area lightning over the new updraft and a pixel from the flash extent density. So the minimum flash area would likely be the best bet for using the tool with decision support services in mind due to its higher sensitivity.

-Dwight Schrute

This was a scenario where we were baffled by how little lightning was being shown from both the minimum flash area and flash extent density products. We asked why so little lightning compared to how much ice is in the storm, combined with MESH indicating a 2” hail stone.  The lightning with this maturing storm was not being sampled well.

-Dwight Schrute

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Tall cell in western GGW’s area

Posted in GLM, GOESR on by Brandon Smith.

Strong updraft in western GGW showed the red colors going over to greens…likely the updraft getting into the warmer stratosphere.

Day cloud phase distinction loop over the area shows a continued strong updraft with gravity waves radiating outward.

Quite a bit of flashes in that cell in GGW.

Charley

Stronger Core

Posted in GLM, GOESR, NMDA, ProbSevere on by Brandon Smith.

Continuing the SVR downstream, as yet another strong core pops up.  Colder cloud on IR and now prob severe is starting to jump up.  Blue color showing ProbHail and ProbWind in the 30s.

Cell also showing more signs of organization in the SRM…better chances for hail.

Also getting a pickup from the DMD (latency issue still for NMDA).

Charley

Pocatello Storms

Posted in AllSky, CPTI, GLM, GOESR, Live Blogs, NUCAPS, ProbSevere on by Michael Bowlan.

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 intensification as these storms move into a more favorable environment in eastern Idaho.

As storms begin to intensify probsever eis picking up on the strongest activity. Probsevere began to ramp up for the cell just south pf Pocatella. That combined with traditional radar methods lead me to issues a warning for that cell.

A similar situation unfolded with a south just south of CWA that I debated on warning. The probsevere values did show and uptick. Eventually the storm fell apart as it pushed into southern Idaho.

We’re watching a few cells in the southern half of the viewing area.  As NUCAPS comes in I’m comparing it the allsky cape. The allsky cape is around 1100kj.

The modified sounding is putting out about 700kj of ml cape. While the nonmodified is much lower down to 500kj.

We don’t have a midday sounding to see which one is initializing the best. For what it’s worth. The rap cape output is around 500kj.

The TPW was close to the observed pwats as well. It was outputting about .65″.

The FED has been fairly low this afternoon which isn’t typical for what I have been usually see. However, the AFA and the MFA are higher indicative of growing updrafts. I’m thinking the FED might be lower because of potential hail in the updraft.

The cell pushing out of Freemont county Idaho continues to intensify as it pushed into Montana. Both the MD, and NMDA were picking up on a high meso that was clearly seen on SRM.

 

The CPTI was showing high probabilities as well.  I still wasn’t as concerned about a tornado threat due to how high the base of the storm was. It was interesting to see though.

The forecast cape and cin values came in from the NUCAPS,  but it wasn’t usable for my area because their was a lot of missing data.

The actual Pocatella office issued a warning for Freemont county. Using typical radar methods the storm didn’t look like it warranted a severe thunderstorm warning, but satellite and MFA showed new convection was still firing up. Right after looking at satellite there was a report of a 54mph wind gusts.

 

Lightning over the Mountains

Posted in GLM, Live Blogs on by Michael Bowlan.

Having the different lightning products from GLM as well as data from ENTLN allows you to pick out which cells have started producing lightning.  One flash up in northern WY on this image, the dot in the upper left, did show up in the FED data a couple minutes later.

Charley

Western Wyoming Cell Developing

Posted in GLM, Live Blogs on by Michael Bowlan.

IR imagery showing a taller/colder cell in western Wyoming.  KRIW radar just switched from VCP 35 to 12.  Peak Z aloft now only around 30.  Lightning data, below, shows relatively low FED, but higher TOE, with peak values in the 300’s, similar to some of the storms we saw yesterday.

One other thing to note in these, is the relatively low FED and number of ENTLN/NLDN flashes.  That doesn’t mesh with the brightness of the TOE.

Charley