Wherefore art thou Convection?

Two hours in and we are STILLLLLL waiting for convection to fire in the KHGX CWA.  Front is stalled across the northern quarter of the CWA and the sea breeze has pushed inland from the southeast.  Come on storms...really?



O.K., why no convection?  KLCH launched a sounding at 17Z which looked like this from GOES-E (why this is important in a bit):


Congrats to Lake Charles getting a special sounding off before those storms arrived!  This is what the lowest half of the sounding looked like with boundary layer conditions guessed from the near the center of Houston's CWA at KTME (Houston Executive Airport):


No Cap, ~2500 J/KG MLCAPE, surface moisture isn't mixing out too much....so, where are the storms?

Let's take a look at a NUCAPS sounding taken from this point almost an hour after the KLCH sounding:


I know you are going to ask...why not the next closest dot further west?  Well, it is on the edge of the instrument swath and that has a whole host of problems.  Second thing is that the soundings along the edge looked...wonky...compared to the next row further east.  The sounding at that point, again modifying the surface conditions for KTME (88/75 T/Td):


Things that make you go; hmmmm.  Using the MLCAPE profile, the NUCAPS sounding shows that there probably is a residual EML behind the departing storms that the KLCH didn't capture ahead of the storms.  That may be just enough to keep the atmosphere capped and storms at bay.  There isn't much of a cap, so hope continues we will get convection over the KHGX CWA.

NUCAPS sounding profiles - thumbs up for helping figure out what is going on.  And get more polar orbiters up and going so we can have more than two soundings per day...preferably on different orbital inclinations for better spatial coverage. Please?

-Dusty

Prob Severe Combines Discrete Cells

Here is a prime example of two warned storms with distinct updrafts that were combined due to their close proximity to each other. As opposed to being slow to recognize splitting cells, ProbSevere actually took two established discrete cells with separate updrafts and combined them.



ZDR_Arcophile

MRMS and ProbSevere - SAD Match made in the EWP

Wanting a good way to keep up on the environment while also monitoring for storm development?  Give this combo a tryout (and note, I totally stole this from another EWP participant this week.  Why?  Because it works!)



Top left: MRMS Reflectivity at Lowest Altitude (RALA), Reflectivity at -20C, ProbSevere All

Top right: MRMS Maximum EstimatedSize of Hail (MESH), MRMS 60 Minute Hail Tracks (50%             Alpha), ProbHail

Bottom left: MRMS Vertically Integrated Liquid (VIL), MRMS Vertically Integrated Ice (VII,                    100%), ProbWind

Bottom Right: MRMS 0-2km Merged Azimuth Shear, MRMS 0-2km Rotation Tracks 60-minute          accumulation (35% Alpha), ProbTor

The nice thing with this display is that you can quickly sample any of the objects to get details on what is going on with any given storm to keep situational awareness.



Yeah, that's a lot of text on the 4-panel but each one is specific to the threat in the pane and the ProbSevere (top left) is a bit of everything mixed in.  So far, it has worked with all convective modes we've seen so far in the Testbed.

-Dusty

GLM Minimum Flash Area Indicates Convective Weakening

GLM Minimum Flash Area indicating potential weakening in convection. Larger area/extent is likely due to lightning along the anvil, and less localized/shorter distance also indicates potentially weaker updraft. Reflectivity in this example also confirms weakening of the convection.

All Sky CAPE dropout between time steps

I would like to be able to load ALL-Sky LAP Data Type and CAPE on top of radar data. An unfortunate annoyance is that if the time stamp is too far from the radar product time stamp, the All-Sky products completely disappear,  and in fact, if too far away, it won't load at all. I would like the ability for the latest All-Sky products to display, despite the time lags between the the two. In other words, I would rather have the latest "old" data from All-Sky rather than display nothing.



ZDR_Arcophile

Downward Trend in ProbSevere Time Series & GLM Results in Warning Cancellation

A noted downward trend in the ProbSevere Time series along with a downward trend in the GLM products (not pictured) resulted in this warning forecaster to cancel a SVR for Kerr County early. This early cancellation may not have occurred had these products not been available, potentially leading to areas being unnecessarily warned for a longer amount of time.

Comparison of ATPW and Blended TPW

I was finally able to take a look the ATPW (top left) and compare it with the operational blended TPW (top right). My first impression was that both products show similar large scale patterns with a large plume of moisture extending from the Gulf of Mexico into the Ohio River Valley. The ATPW also tends to show a little more detail in the moisture field compared to the blended TPW.

At 15Z ATPW shows an area of lower moisture over the Texas Gulf coast which is sort of fills in by 17Z, likely due to upstream moisture being advected into the area. In contrast, this moisture is continuously present in the blended TPW. ATPW generally had PWATs around 1.5 in, while the blended TPW had PWATs around 1.7-1.8 in. In contrast, 12Z RAOBs along the coast had PWATs that ranged from 1.6 inches at KBRO to around 1.8 at KLCH. These values seems to match better with the blended TPW product. I suspect that the upstream convection over Louisiana and lingering clouds over the coast impacted the ATPW that was corrected in the blended TPW.

HWT Issues SVR 3-Min Before Field Office Does Due to GLM & ProbSevere Data

A strengthening thunderstorm in Val Verde County was noted by Prob Severe and GLM data. The Average Flash Area and Minimum Flash Area values quickly increased in the area of a strengthening updraft across Val Verde County. The combination of these factors, along with a noted uptick in ProbSevere  data, prompted the HWT warning forecaster to issue a SVR for Val Verde County at 1:25pm CDT with WFO EWX issuing a SVR for Val Verde at 1:28pm CDT.

ProbSevere Time Series Used to Hold off on Warning Issuance

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 (middle image compared to bottom image), as the ProbSevere Time Series was indicating.

Tornadoes in northern Louisiana

With a QLCS moving through yesterday, many local storm reports (LSRs) were delayed. The time series below show how ProbTor (Figure 1) and the other ProbSevere products (Figure 2) performed with respect to official NWS warnings and reports. Several forecasters at HWT this week have noted that they look for jumps in ProbSevere and ProbTor to help identify threats and provide confidence in their warnings. For the storm segment below, there was a jump in ProbWind about 8 minutes before the first tornado report ("widespread damage" reported) and a jump in ProbTor 4 minutes prior to the tornado. Increases in lightning activity and 0-2km AzShear helped jump the probabilities.

Figure 1: ProbTor time series for a tornadic storm. The jump in ProbTor was due to a sharp increase in 0-2km AzShear and and increase in ENI lightning density.

Figure 2: ProbSevere products time series compared to NWS warnings and LSRs.