It’s pretty clear to me that both the GOES-west and GOES-east are having a lot of trouble detecting lightning (GLM) in the northwest U.S. with accuracy of location or frequency due to parallax, spatial resolution, and GOES tilt sampling of storms. Below is an animation specifically over southwest Montana where the GLM displaces the FED significantly (side note: TOE was very similar for these, so FED is shown for best example), and also has trouble picking up in-cloud pulses. The ENTI is overlaid in pink to show the differences in GLM vs ENTI. If you watch closely, the first frame depicts an ENTI in-cloud lightning flash & pulse in the far southwest portion of the screen, where no GLM FED (or TOE; not shown here) was even detected. There is also some instances where the GLM places lightning pixels where the ENTI or NLDN does not show anything in the same time frame (also making it hard to verify both products).
Below is a separate example where the FED does not show what I would expect it to show for a central Wyoming storm (differentiating intensity as well as location and timing). The GOES-east is the first to detect, then the GOES-west detects thereafter. GOES-east and GOES-west did not detect at the same time in any frame. Both products are loaded as a 5min-1min update.
Now here’s a case farther south in New Mexico where a storm cell is of comparable intensity as the northern examples. The GLM detection seems more accurate than the MT case, but the last frames here show that the GLM also has trouble with keeping FED on the cell core of interest.
Interestingly enough, the TOE (shown below) does a better job here in NM with spatial coverage than it did up north in MT, but still has displacement issues comparing to ENTI and MRMS storm cores. I find that the TOE (especially with GOES-west) does a better job at recognizing the spatial extent of a flash here than the FED product did. (See above vs. below).
Now the question is, is the parallex better in the south-central U.S.? And what if we look at higher resolution products like the group centroid density GLM product? While comparing the satellite GLM, with Day-Land-Cloud-Convection RGB, and with the ENTI/GLD/NLDN strikes (overlaid in pink) in SE Missouri…..it’s clear that a forecaster should not solely rely on GLM for core lightning locations (below). -shearluck
To further confuse matters the NUCAPS forecasted SFC CAPE values for the same location and time is 400J/kg…which is closer to the observed sounding than to the NUCAPS sounding.
