Tag: All-Sky LAP

AllSky & TPW Check

Posted in Live Blogs, News on by Michael.

Did a quick check of the merged TPW and AllSky products and as previously advertised/anticipated, the convection has been riding right along the gradient of the higher instability, but there is some discrepancy as to whether it’s right in the heart of the higher PWATs or along the leading edge, depending on if you’re looking at the AllSky or TPW, respectively. Noticed quite a bit of a latency in the availability of these products (up to an hour), which wouldn’t be good in an operational setting. Compared the values of the TPW and AllSky PWAT with the RAP, and the AllSky matched up much closer to the RAP. However, with the amount of cloud cover in the region (for obvious reasons), the GFS is the predominant data type (basically a model-to-model comparison). Either way, the general idea/trend is helpful if serving as a mesoanalyst in an operational environment.

~Gritty

(CAPE)

(AllSky PWATs)

(Merged TPW)

TAE Mesoanalysis #1

Posted in Live Blogs, Mesoscale Discussions on by Kristin C.

Forcing and storms remain well to the west of our CWA, but the atmosphere is becoming primed for strong to severe storms later this afternoon. LAPS All Sky retrievals show that ML instability has been steadily building, reaching roughly 500 J/kg along the Gulf coast.An 8 hour loop shows how the instability has built and gives more confidence that instability will continue to build ahead of the storms to our west. We did feel that LAPS CAPE seemed a bit underdone given the intensity of the downstream of the convection, so we took a look at the latest NUCAPS retrievals. We examined the point in the extreme SE of our CWA.The boundary layer on the unadjusted sounding required some adjustment to match the nearest obs, but overall, seemed to capture the general profile well. I was initially skeptical about the warm nose just above 700mb, but a similar feature was evident on the 12z sounding from TAE. This feature may have an impact on storm intensity and potential hazards, and it would be particularly helpful to see how this feature changes over time. Sandor Clegane

AllSky Indices

Posted in Live Blogs on by Michael.

Of the indices below, there is some utility in these products, although did not find the Total Totals Index to be of much use considering there were warned storms with verification within HGX’s CWA. The K Index seemed to be the most useful, with the Lifted Index product showing the storms once again riding along a gradient.

~Gritty

The Evolution of an Intensifying Cluster

Posted in Live Blogs, Mesoscale Discussions on by Michael.

Storms in the EWX CWA early in the shift were generally remaining sub-severe, with what looked to be heavy rain as the dominant threat. The first two loops (below), the storms were riding right along the gradient of the PWATs and CAPE. (continues below)

As the cluster of storms reached the eastern edge of a greater area of instability (below), the concern then turned to how much of the instability would be tapped into and how storms would react, with the thought that they’d likely become more robust. (continues below)

Attention was then turned to how the GLM was observing the evolution of the stronger cluster of storms within the northeastern portion of the CWA. I created a four-panel display, with MFA overlaid onto the mesosector visby imagery (upper left, below), clean IR with TOE overlaid (upper right; I had blinking enabled to capture the highest fJ, but is unseen in this GIF), Event Density with Group Centroid Density overlaid (bottom right, below), and FED with Flash Centroid Density overlaid (bottom right, below). It was fascinating to watch how the lightning unfolded with this particular cluster, and the MFA in particular immediately drew my eye to the storms moving toward the FWD CWA border. The smaller flashes began to blossom and expand out, which then had me look at the TOE and density products. The density products ramped up, but what I found the most interesting is that the MFA seemed to give me that initial clue that this storm was in fact tapping into some of the higher instability and allowing for the updraft(s) to intensify.

I then proceeded to take a look at the MRMS LL AzShear product (below), wistfully wishing I could look at the single radar version of this product. Sure enough, a clear signature developed, highlighting the amplifying wind within this cluster.

Last but not least, looking at ProbSevere, the ProbWind product picked up well on this signature, highlighted below.

Conclusion: I’m continuing to see some promise that there’s something to look deeper into with respect to these additional lightning products, particularly the MFA when used in combination of something like the Event or Flash Extend Density products. There seemed to be a good correlation with the TOE, as anticipated, but I’m still unsure about its utility as a stand-alone product. As for the Average Flash Area, I didn’t even pull it up given the limited amount of screen space I had and what I saw yesterday, with the AFA in particular not giving me hope of being able to gather good info/lead time in comparison to the MFA.

~Gritty

Side note: Had some excellent conversation with the GLM expert in the room and as we were talking and analyzing some of these products, it was noticed that there was quite an extensive channel, lightning that shot out well to the north of this cluster of focus. These GLM products could provide beneficial information when providing DSS to partners, such as letting partners and the public know not to go back outside just because there’s either light rain or the storm had already passed.

HGX Mesoanalysis

Posted in Live Blogs, Mesoscale Discussions on by Michael.

Storms are approaching the HGX CWA. GOES-16 imagery shows amply cumulus development across much of the CWA. With temps in the upper 70s and dew points in the upper 60, I expect there to be ample instability in this environment.All Sky LAPS retrievals indicate ML CAPE just shy of 1000 J/kg, but with this environment, I would expect instability to be higher. The modified NUCAPS shows a profile more in line with what I would expect to see. In this profile, the surface dew points were close to what surface obs show, but the surface temp did need to be adjusted up a bit. This sounding, coupled with analyzed deep layer shear, leads me to think severe weather is a possibility in this area.Sandor Clegane

Waiting on convection – diagnosis and investigation of products

Posted in Forecaster Thoughts, Mesoscale Discussions on by Kristin C.

Corpus Christi —

In investigating the environment we’ve deemed the convection to be more or less dependent on synoptic forcing via the cold front dropping southeast.

A

In A, plotted is Total Precipitable Water along with SPC Convective Outlook and analyzed fronts. A couple of things can be noted: TPW is very high under the Slight Risk, and it is displayed very nicely with good resolution contained within the gradient. This is a good example without going into too much detail about how our environment is primed for severe weather. However, NUCAPS Gridded Data has not come into our area as of 20z. This makes it hard to test the product and how it captures the boundary layer. 

Now, we wait.

B

As we wait for the cold front to drop SE, our attention is focused on convection happening in NE Mexico (pictured in B). These cells popped up right along the CAPE boundary between values of 300 j/kg to 1500 j/kg.

C

As can be seen in C, the GLM has indicated these storms contain lightning, thus they are intensifying in nature. We will now be monitoring the hail threat.

 

-lakeeffect

All-Sky Gradients & New Storm Development

Posted in Forecaster Thoughts, Mesoscale Discussions on by Kristin C.

Today was a great example for how the improved resolution from All-Sky LAP allowed us to hone in on exactly where new storm development will occur.  Convection across Mexico developed where the front sagged south along the moisture/CAPE gradient. While in this case the CIRA Merged TPW showed the same gradient, the resolution was still better with All-Sky. Baseline blended TPW as well as satellite derived TPW/CAPE were useless due to either being overly smoothed, or not displaying in cloudy areas. Great diagnostic tool.

— FLGatorDon

AllSkyLAP CAPE – Trends

Posted in News on by Kristin C.

Noticed the trend of AllSkyLAP – CAPE was interesting – and bucked the trend of the GFS background.

2157 UTC:  LAP seemed to have a good handle on higher CAPE trends at this timeframe with over 1000 J/kg in a wide area – which seemed to match convective trends.

2227 UTC:  LAP reduced CAPE over much of the area – even in areas that did not see storms.  Skies were generally were generally partly/mostly cloudy – but the trend appeared to reduce values too quickly.

2258 UTC:  LAP CAPE appeared boost again somewhat – but still less than the GFS CAPE.  These sort of “bouncy” CAPE trends will be examined the remainder of the week – to see if this trend continues.

 

 

Revisiting the AllSky Products

Posted in Live Blogs on by Michael.

Went back to do a broader-scale mesoanalysis and noticed right away that storms are initiating right along the southwestern extent of a moisture/instability gradient, and following a SW to NE gradient between two areas of higher PWATs/CAPE, as depicted on the middle image below (reflectivity overlaid on AllSky CAPE). Just focusing on the trend aspect of these products is very useful in determining where storms may continue to develop and roll. I attempted to look at the merged TPW product, but unfortunately, the data I have is almost an hour old by the time of these screenshots, and the lower resolution isn’t as easy to work with in comparison. It’s possible the values of the TPW product may be closer to reality, but gravitating more toward the tendencies of the current state of the atmosphere found in the AllSky products seem to be more useful for this purpose.

~Gritty