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While the storm looked strong to possibly severe on radar, the trends in the ProbSevere Time Series were indicating a downward trend/weakening. Thus, I chose to held off on issuing a SVR. The storm did ultimately weaken, as the ProbSevere Time Series was indicating. Note, in the image, the warned storm on the right has lower probs, but was stronger in earlier scans and had produced severe hail.
As we were wrapping up the work for the day, an updraft rapidly grew over part of the CWA we were in. I went back and looked at NUCAPS FCAST CAPE data that I had originally discounted as discussed in a previous blog post. While it appeared at the time that the NUCAPS FCAST CAPE values weren’t viable from a forecast perspective, turns out this storm fired off the edge of the CAPE gradient that the NUCAPS FCAST represented better than the RPM13.
This was my first exposure to NUCAPS FCAST this week as it wasn’t available….it’s worth a second look. It’s also an indication that you need to work hard and diligently through the end of the shift!
-icafunnel
Ok, last post….honesty time.
I didn’t make this a secret in my application that I had been out of meteorology for about 4 years between 2014-2018. During that time, GOES-16 launched. As I returned to broadcasting, I didn’t adequately spin-up on the new capabilities of this new generation of satellites. I was aware of the spatial and temporal resolution improvements of course – what meteorologist – currently working in or out of the field, didn’t get excited about 1 minute imagery?
However, I wasn’t aware of some of the RGB combinations that I’ve been exposed to here at the HWT. The features that can be picked out by applying coordinating colortables to multiple channel views is simply astounding. I’ve used the simple water vapor, day cloud phase distinction, day convection, differential water vapor RGBs this week….I’ll be making a phone call to my broadcast weather vendor. I know I’ll need to get some other broadcasters on board with me to lead a charge, but count me in. Until then, I’ll be livin on the CIRA RMMB Slider site!
Color (RGB) Me A Fan!
-icafunnel
A quick comparison at 21Z reveals that Merged TPW Composite is running about .3 inches lower than Blended Total PW.
Today we were tasked with the LIX CWA (New Orleans/Slidell, LA), and the NUCAPS sounding went overhead at 1824Z. Luckily there was a special sounding out of the LCH (Lake Charles, LA) office at 1700Z so there was at least a loose chance to compare the data. So, let’s do just that! First the LCH sounding…
Shows a relatively unstable atmosphere with decent lapse rates in the mid-levels. And now the nearest good-value NUCAPS sounding (taken just north of Vermilion Bay)…
The two soundings aren’t an exact comparison, they aren’t in the same location or taken at the same time, but synoptically it should be a pretty similar environment ahead of the broken line of storms moving into the area. The biggest problem comes in the boundary layer with values that are way off. The profiles were showing a 2m value of 76/70 when in the observed sounding it was 82/75. Given that the sounding was taken earlier in the day, it’s troublesome that the temps were much higher than the NUCAPS sounding. Unfortunately, modified soundings were not available on this day and given the unmodified soundings inability to correctly analyze the boundary layer, it makes trusting any surface derived data near-impossible. The only application I can see for these soundings are to analyze the upper-level synoptic environment (i.e., upper-level lapse rates, relative humidities, etc.) For this, you can compare some values… 850-500 Lapse Rate was 6.1 C/km in the NUCAPS sounding it was 6.7 C/km, some variability is expected and it’s not too bad but the difference is worthy of caution. In the gridded product somehow the Lapse Rate was 6.48 C/km, much better given the expected variability but I’m not sure these values are different. Are the gridded data not derived from the soundings or vice versa? Mid-level RH in our LCH sounding is 90%, yet in our NUCAPS sounding it’s 79%. I’d expect these values to be a bit closer given the strengths of NUCAPS, but it’s close enough to perhaps chalk up to differences in space and time.
Afterwards, I saw that LIX also had a Special Sounding that could be comparable, I’ll leave the comparisons below…
#ProtectAndDissipate
Since things were kinda boring over HGX today I had to look for things to blog about. Here is something interesting that I noticed with the Vis/IR Sandwich RGB. At the beginning of the loop the RGB didn’t show any IR brightness temperatures. As the TCU continued to develop we saw pixels of IR brightness temperatures starting to show up indicating cold cloud tops and the potential for glaciation to start. Low and behold, if we continue to watch the loop, more pixels start showing up…and a few minutes later both GLM and ground based networks picked up on a couple of CGs. As the thunderstorm developed, cloud tops cooled and more pixels started getting displayed we began to see more lightning. This was something that I didn’t expect the RGB to pick up on and potentially helpful for situational awareness and IDSS in the west where most lightning tends to come from single cell thunderstorms. If you are able to pick up on these ahead of time you may be able to some lead time before lightning occurs.
Update…it happened again, pixels starting being displayed and then lightning occurred within a couple of minutes. If this generally hold true for single cell thunderstorms this would be awesome for outdoor IDSS.
Well, the convection is trying. And dying. Case in point, the full life cycle of a pair of storms across the northern suburubs of Houston. Thoughts below:
You are looking at the 1-minute Mesoscale Sector scan with GLM Flash Extent Density, the Vaisala GLD dataset, and ProbSevere overlays. Some things to look at:
ProbSevere struggled when the storms were most intense by merging two individual storm objects, splitting them apart, then re-merging back into one object. Trends were a mess because of this.
GLM lightning activity ceased a full 10 minutes before ProbSevere dissipated the tracking associated with the cells. However, it continued to show flashes taking place for 7-minutes after the last CG was detected in the GLD data. Good use for IDSS to let people know that cloud-to-ground strikes are still possible.
The storms initially were moving northwest along a boundary then deviated to the northeast as they strengthened. As soon as the moved off the boundary…bye bye!
-Dusty
Despite a concerning hook-ish appearance on radar, I chose to hold off issuing a TOR due to the lack of persistent/significant Az Shear values.
Knowing that the NUCAPS FCAST information was in today for the first time this week, I decided to do some analysis of the fields. Initial thoughts are that the missing blocks of data (not sure if that is typical – more visible in the CAPE field in top image – similar data holes observed in LCL, LFC and EL) make it hard to have confidence in it at first glance.
CAPE (Top Image)
NUCAPS FCAST CAPE data isn’t good in the pre-storm environment along the LA coast. RAP13 initialization is overlayed for comparison. RAP13 values are 2500-3500+ and much more representating thatn the NUCAPS values that in some cases are less than 500 ahead of the line.
CINH (Lower Image)
While these values appear to be more closely representative compared to the RAP13, the inability of the product to adequately represent the boundary layer at times during the week don’t provide me much confidence for these surface based stability parameters.
-icafunnel
Here is an example of a long lived supercell where the trends are very important to monitor. Notice the uptick in Prob TOR but then backed off. AZShear has been impressive for several volume scans. Prob TOR trends kept me from issuing a TOR warning, and provides some security in not issuing a warning along with other products. As a side note, it would be nice to sample some sort of maximum wind gust product, much like we get from MESH with the estimated max hail size.
ZDR_Arcophile
