GLM data; options and visualizations

We are asking forecasters to examine a variety of GLM products in their environment for a variety of uses including situational awareness, decision-support services, and storm interrogation and nowcasting.

Based on forecaster feedback from week 1, we offer these both at 1-min and 5-min (w/a 1-min update).  The 5-min product was recommended strongly by the forecasters in week 1 to help visualize trends.  I've included 60-min loops of both below to illustrate the difference.

1-min accumulations/averaging:

One-hour loop of 1-min accumulations of GLM data over eastern SD, southern MN, and northern IA ending at 2101 UTC on 8 May 2018.  Top left: event density.  Top right: Flash Extent Density. Bottom Left: Total Energy.  Bottom Right: Average Flash area.

5-min accumulations/averaging:

One-hour loop of 5-min accumulations of GLM data (w/1-min updates) over eastern SD, southern MN, and northern IA ending at 2051 UTC on 8 May 2018.  Top left: event density.  Top right: Flash Extent Density. Bottom Left: Total Energy.  Bottom Right: Average Flash area.

It does appear the 5-min accumulations are better for SAD displays and loops such as the ones shown above.

-Kristin Calhoun

GLM vs Ground Network Lightning Detection

Convection beginning to fire off along remnant outflow boundary from earlier storms across northern Iowa. Monitoring the GLM lightning data and the cloud to ground sensor networks to see we there would be an appreciable time difference between the first cloud flashes observed versus the first cloud to ground strikes. GLM first picked up cloud flashes around 2019Z in Hancock County while the first appreciable CG strikes occurred around 2040Z. GLM shows to be beneficial in highlighting areas of convective initiation before cloud to ground sensors.

- Jack Swigert

Waiting for Convective Initiation in Iowa

Overnight storms continue across northern Iowa. This activity has left an outflow boundary to the south straddling northwestern counties of the CWA. Modest theta-e advection ahead of approaching vort lobe moving out of the Dakotas with temps climbing into the low to mid 80s and dewpoints in upper 40s to mid 50s. Expecting convection to fire up later this afternoon around max heating along the remnant outflow/frontal boundary in northern/western Iowa. Strong winds primary threat with steep lapse rates and DCAPE values 800-1000 J/kg. As of 1900Z, GOES Convective Initiation prob 0-2 hours only showing 10-20%. Tongue of instability nosing quickly into western Iowa as well as evident via AllSkyLAP Layer CAPE of 1000-1600 J/kg.

- Jack Swigert

Week 2; Day 2

We begin day 2 in the DMX (Des Moines, IA and FSD (Sioux Falls, SD) region.  Some convection is still in place associated with an overnight MCS that propagated across South Dakota and into MN and northern IA.  CG lightning (3-5 flashes per min) is still associated with this system, but overall convection in the area currently remains sub-severe.

Additionally, calibration and testing for the EXIS system for GOES-16 is ongoing today (May 8- May 11).  We are told this may cause some false alarms in the GLM, but it appears the Level 2 -Lightning Flash Clustering Algorithm (LFCA) data stopped at 1723 UTC and has not restarted.  We are hopeful it will resume, but remain unsure to when...

-Kristin Calhoun

Week 2-Day1 MK GLM Total Energy & All Sky-Lap

Forecasting along side a meteorologist known as "supercell," our focus today was potential severe storm development over Rapid City South Dakota. This group of storms prompted us to issue 4 severe thunderstorm warnings with the main threat expectation of hail.

Using the Severe Storm Probability Index and GLM we noticed the higher threat for hail was consistent from morning and midday through the event that produced severe storm activity in western South Dakota. 

GLM Lightning Total Energy Data also corresponded well with the late afternoon early evening storm warning that we issued. The two ALL -Sky Lap products performing well with our prediction efforts are CAPE and Precipitable Water.

Downdraft Cape in the NUCAPS data was not appearing using NUCAPS (this product was likely not useful for this event however). Theta-E lapse Rate showed weakening through middle and eastern South Dakota, however the last warned stormed intensified in this area of weakening along with a significant increase in echo tops, and mid/upper level moisture. 

Discussion of using other products with the NUCAPS gridded data ensued later as using the 1.37 Cirrus NIR channel or the RGB Day Cloud Convection may assist visualization of the storm environment where NUCAPS shows no reports due to cloud cover (nature of the top down real data collection)
mk

CWA TomClemmonsBYZ 05-07-2018

A weak upper-level disturbance moving across northern central and northeast Wyoming south central and southeast Montana will help provide weak synoptic scale lift. Steeping lapse rates and increase CAPE into the afternoon will help the further development of thunderstorms. Dry low levels will enhance an isolated threat of strong thunderstorm outflow winds if storms become strong and or form an organized line of thunderstorms. Mid to upper level jet between 30-50 kts.

ProbSevere did well on alerting the forecaster to the strongest storm of the day, and which storm to pay closer attention to.

ProbSevere Upper Left Showing the Strongest Storm in Pink Polygon

As shown the ProbSevere is showing a strong to severe storm with ProbHail trend up with each consecutive volume scan. This image was captured right before the warning was issued. Mesh was estimating 1.51 inch hail. Also notice the lower right panel at nearly 21kft and the 50 to 60 dbz echos at this altitude.

Another graphic that was used was to look at the radar refl. between -10 and -20 degree C layer and determine if there was radar returns in this temperature layer over 50 dbz.



GOES All-Sky LAP Products:

A 4 panel was created to show the K Index, the Parcel Lifted Index, and the CAPE, with a 0.5 Refl panel. The panels showed the storms were moving east into increasing instability.

A 4 panel was created to show the All-Sky Lap Products PW layers Sfc-900mb, 900mb-700mb, 700mb-300mb, and 0.5 Refl. This image shows that the storms were moving into increasing 900mb-700mb moisture.

Rapid City's Mesoanalysis/Analysis/Warning Operations

Noticing a gradient in instability within the UNR forecast area. Will put image in showing this.  It is comparable to the NAM12 gradient in instability.  Did notice that the Layer precipitable H20 also has a gradient in moisture spreading into the eastern half of the forecaster area but especially to the east over Aberdeen.

 Would expect additional increase in intensity as storms that area already developing across the northeastern sector of Wyoming. Am noticing that the highest Prob products (severe, hail, and wind) are coinciding with the strongest updrafts within the storms located over Billings area (2102Z).  Did look at a few NUCAPEs soundings which show a pronounced dry layer from 700mb-sfc. In a NUCAPEs sounding, I do like the readout but would like to see where the cloud layer is, instability, PWATs, etc.; displayed on that readout so that when we move mouse over individual points we can instantly see that data (rather than having to click on each individual point.  Will try to insert an image to better describe.

The GOES R GLM data is challenging to understand given how far northwest in the CONUS this is.  Seeing a lot of parallax. So, not sure its too useful for this office until GOES-S becomes operational.  Loaded ENTLN and NLDN into a procedure to compare with the GLM data and garner a better picture of lightning. 

The UAH CI product had lapses in time or late between 2032-2100Z data. It was affecting my procedures that had both satellite and UAH CI data.

Noticed that core of storm in western portion of UNR CWA had a distinct reflectivity gradient while Prob hail was decreasing. So, it could be that the hail was descending from the core. Given the dry air layer in the environment, it may be more of a microburst than hail impact with this storm. Went ahead and issued a severe for 60 MPH and nickel sized hail. Prob Severe, prob hail, and prob wind then increased on the next couple of scans attendant with the storms moving over the gradient in instability at 2206Z.

Prob Hail was actually higher than Prob Wind at times which was a little surprising given the prevailing environment but may be because the storms were a little more elevated.  As additional storms moved into the "gradient of highest CAPE" in UNRs northern area the Prob Severe and Prob Hail increased.  I do like the cursor readouts with the Prob Severe/hail that include CAPE within the hail growth zone and MESH.

Some other notes: I think it would be helpful to have Near Storm Environment Cursor Readout to compare what we are seeing in NUCAPs, GOES- All-Sky LAP products for hail and wind environments.

Did notice that the warnings we are issuing are in all caps and don't have the tags on them (tornado/hail/wind) at the bottom. Perhaps to make it more high fidelity, it may be useful to have that as well.

The area was loud while other HWT participants (another project) came into our area and were talking for an hour or two about everything but the project.

V/R
Supercell

Editing NUCAPS Sounding

19Z NUCAPS sounding available for far SE Montana but no 22Z available around peak heating. If wanting to see how much the atmosphere has destabilized in the three hour window, I edited the sounding to match surface obs.

19Z NUCAPS sounding.

Looking at nearby surface obs around 22Z, which were lacking, and the SPC surface mesoanalysis, I edited the 19Z in the lowest levels based on nearby obs 79 temp and 46 dewpoint.

Edited 19Z NUCAPS sounding to match 22Z

While not dramatic, there was a noticeable increase in CAPE values during the 19Z to 22Z window. This was also noted on the AllSkyLAP Layer CAPE loop over the same time window.

As of 22Z Monday storm initiation had not occurred over far SE Montana. but earlier convection north and west was working into the region as vort max continues to trek across Montana. To be seen is new initiation develops over the region.

- Jack Swigert

ProbHail Overestimating Severe Hail in Montana.

MRMS Composite Reflectivity over southeast Montana on Monday afternoon 2022 to 2136Z with ProbHail overlaid. Convection firing off near the Billings area with individual cells displaying high ProbHail values of 50 to 80 percent in the initial and mature phase of development. This was due to MESH values of 1" to 1.7". Issued 3 warnings for hail size of 1" but storm reports of only 0.25" to 0.88" were received before the storms weakened as they worked east of the Billings area.

- Jack Swigert

HWT 2018: Week 2, day 1: BYZ & UNR

As we get the ball rolling on week 2, the weather takes us further northwest -- Billings, MT and Rapid City, SD.  The forecasters are currently setting up and getting familiar with the variety of GOES and JPSS products available to them. 

Initial outlook for today is not very exciting for those in search of severe weather.

There is a decent chance for severe weather associated with and ahead of the short wave moving through Montana and across South Dakota later today.  Unfortunately, much of this may occur at or after we end operations for the day.

Currently, small storms with some lightning are ongoing in central and southern Montana and a small field of Cu is developing in western South Dakota.

30-min of GOES-16 VIS (ch. 2, 5-min update) and GLM Total Energy (5 min-summation, updating every min).

For day 1, however, the goals for the forecasters are primarily to get acquainted with the variety of products available and begin building AWIPSII procedures they will be able to incorporate throughout the week. Hopefully, we will see a wider variety of severe weather as the week continues.

-Kristin Calhoun
Week 2 Coordinator
GLM Science Lead