Severe Storms over Central Texas.

Storms over northern Bexar and southern Comal have had hail up to golfball size reported. This is in good agreement with the MESH signature. Additionally, Prob hail for both v3 and v2 are up over 80%, so in good agreement with the algorithm.

Animation of storms with the latest OCTANE. Looks like storm top divergence can be inferred from 70 kt anvil level winds to the south and 30 knot winds to the northwest. Would equate to strong divergence aloft and indicative of a severe storm.

The 08Z Pass of NUCAPS shows a rather impressive PWAT/Moisture gradient this morning, which would likely lead to increased storm chances along the theta gradient over the Hill Country and stretching eastward into the I-35 Corridor. The gradient ranged from 1.25” over the Coastal Plains to .50” over the Edwards Plateau and western EWX CWA.

This ties in nicely with the MLCAPE available this morning.

Storms going up in a weaker shear environment with a rainbow color distribution all around the storm from the OCTANE direction window. Very interesting. You may actually be able to infer the type of storm/environmental conditions just based on OCTANE direction depending on the situation.

– Satellite Steve, StormofCentury , Bolt

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CHS OCTANE Orphan Anvils

While watching for convective initiation over the Charleston CWA, we noticed that the deepest convection over land started to produce orphan anvils; two of them during this loop. It made us curious if we could see any precursor in the OCTANE Speed Sandwich RGB to a developing orphan anvil. At the typical color bar range of 0-200, it was minimally visible, but as we shrunk the range, a precursor became more evident. The example here has a range of 0-75. Note the cell in the center of the screen. At the beginning of the loop an orangish reddish color can be seen just before the orphan anvil develops, then a more noticeable color enhancement can be seen as another anvil is about to be orphaned. From a forecaster standpoint, knowing anvils are about to be orphaned can be helpful to know that a particular cell is not likely to intensify and will probably diminish. Although orphan anvils can be seen with the OCTANE Speed Sandwich, orphan anvils still may be better seen in day cloud phase or day cloud type RGBs.

OCTANE Speed Sandwich loop of two orphan anvils developing.

– Burton Guster & Displar

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MAF Convection

Convection has been slow to initiate in W TX, but we’re finally seeing some vertical extension and greater texture in the CU field on the NE side of the mountains. LightningCast is now showing higher probabilities in this area, after several scans of sub-50% contours.

We are seeing good destabilization. The PHS MUCAPE compares quite well to the SPC mesoanalysis.

LightningCast probabilities continue to climb, and we’re finally seeing a few flashes on GLM imagery.

Our LightningCast meteograms are finally showing some higher probs in the next hour near our DSS site in Fort Stockton.

We’re now seeing more defined features in the Octane imagery, including cloud top divergence signals and cooler brightness temps, down to -63C. But our ProbSevere markers remain low.

Looking at the NUCAPS-Forecast initialization at 19z, the mid level lapse rates are lower in areas NE of the higher terrain, where convection has been a bit slower to strengthen, as compared to the storms to our SW over Mexico, where MLLRs are higher.

The new TPW imagery from NUCAPS shows well the delineation of the moist air to the E and drier air to the W.

The PHS SHiP pattern looks good, but its magnitudes appear way off, compared to the SPC meso page and how SHiP is calculated.

Hail probs are exceeding 80% now on ProbSevere, although our GLM lightning is rather low! Interesting how assumed large hail presence doesn’t necessarily equate to classic charge separation that would prompt high electrification.

21z 700-500mb comparison of SPC Meso (top) vs 21z NUCAPS-Forecast (bottom)
    – Some differences in lapse rates between the two, with NUCAPS about .5-1°C/km  lower than SPC Meso page. 

ProbSevere, Octane, and IR imagery supports warning issuances for Reeves and Pecos counties.

With the warning now out for Reeves and Jeff Davis counties, this storm continues to exhibit high hail probabilities on PSv3.

Up to 120 kts of ST divergence with the warned cell (at about 50 kft).

Interesting how ProbSevere identifies objects. There appears to be 3 separate updrafts in Pecos county, however PS is seeing one object.

– Edgar and StormofCentury

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Examination of LightningCast and OCTANE in Idaho and Oregon

Near the Idaho/Oregon border, we observed splitting cells on the afternoon of Wednesday, June 7. We believe we were able to see the first hints of this process get underway with the help of the OCTANE product. Subtle gradients were observed on the left side of the main storm prior to the ultimate cell merger. 

In the image on page 2, we see a nice comparison using LightningCast between an environment characterized by cirrus contamination vs an environment that was not contaminated. On the eastern side of the CWA that was characterized by cirrus contamination, LightningCast probabilities peaked at 50% on a storm that ultimately produced lightning. In contrast, two thunderstorms to the west (developing in a clear, cloud-free environment) both saw LightningCast values exceed 80% on two storms that ultimately produced lightning.

Above, we see perhaps the first instances of a splitting cell in progress, and OCTANE helped give us a first indication of the split (upper left in particular)

Above: LightningCast Meteogram as of 2053z, depicting a small trend upwards, albeit extremely minimal, within the next 60 minutes for some lightning impacting the American Aquarium at Hayden Beverage in Boise (DSS location).

Above: 21z PHS shows development of convection in Owyhee and Twin Falls counties (southern BOI CWA) depicted by a red box; however, the 4 Panel Situational Awareness is indicating that doesn’t seem to be the case, with mere cirrus cloud development. Perhaps the timing is off?

Above: On the other hand, PHS is doing a fairly good job depicting the convection just east of the DSS site. Currently (almost 22z), a few decent cells depicted by ProbSeverev3 (right around 15-18% probability, where MESH values are just over 0.50”)

Above: 2123z: LightningCast indicating just above 50% probability of lightning within the next hour yet the Meteogram is well below 20% for the GOES East reading. It is suspected that this is because the AWIPS readout is Plax-Corrected, whereas the Grafana Meteogram may not be?

Just after 22z, Grafana Meteogram (above) shows GOES East  ProbSevere Lightning to be 67%. This latency further aids in the belief that the Meteogram is not Plax-Corrected.

As of 2220z, downward trend displayed with regards to the Grafana Meteogram (topped at 70%, now showing 54%). This is indicative of the cells east of Boise (DSS area) initially showing signs of weakening…HOWEVER…

Things are starting to get juicy at 2224z with ProbSevere v3 showing the cell south of Idaho City has increased to 36% probability (below).

– Bolt and Harvey Specter

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Albuquerque HWT

Storms are exhibiting some decent shearing aloft over NW New Mexico when comparing to NE New Mexico. Something I might not have noticed had I not had this product as I don’t always have time to go into the SPC mesoanalysis and check various levels of shear values. The 0-8km shear values are in the 40-50 kt range, in agreement with the range of values noted on the speed shear values of OCTANE. See below.

PHS really doing a nice job of pointing out peak areas of MUCAPE and where storms will likely develop. Decent scale and resolution results in some good quality comparisons with various other products. This is over the southern ABQ CWA.

Forecast Layer Comp Refl 21Z

Forecast MUCAPE 21Z

Forecast MUCAPE 23Z – Also, noting a sharp gradient in MUCAPE values as convection strengthens over east-central New Mexico late this afternoon into the early evening hours. We will have to see how this plays out.

MUCAPE values seem a bit higher than they should be when compared with the MLCAPE values at the same times over New Mexico. I’m not exactly sure why the values are so high, but the forecast RAP values for the same time frame appear to be notably more displaced to the east and lower.

Example below from forecasted time 02Z.

The 6 hour forecast at 21z of PHS 0-6 km Bulk Shear (first image) is compared against the 21z SPC Mesoanalysis (second image). Overall, the PHS forecast did quite well over New Mexico. There is generally little to no shear across the state except for near the Four Corners in the northwest and far southeastern New Mexico. The values are reasonable in these areas as well, around 16 m/s for PHS which fits in with the over 30 knot SPC values.These differences can be noted in the convection occurring as well (seen in the SPC image). Mainly isolated cellular over central NM, but showing more organization in the areas of higher shear.

-Satellite Steve and Burton Guster

 

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Monitoring South FL Convection for the Miami Open

We’re closely monitoring for CI near the Miami Open Tennis Tournament (location noted by the Home marker). Thus far this afternoon, the deepest convection has been in the west, NE of Naples, where the Band 13 imagery shows high cloud tops with cool brightness temps (-66C), and Octane imagery shows a good divergent signal.

So far, LightningCast has focused on the convection in the western peninsula, with the maximum slowly translating inland and to the N along the inland-tracking sea breeze.

This is further confirmed by the lightning meteogram for the DSS site. Looks like they can keep playing tennis for a little bit longer!

Looking at the storm clusters back west, a NUCAPS sounding near that cell shows plenty of CAPE.

The NUCAPS-Forecast MUCAPE confirms the high CAPE invof the storms.

Let’s see what the forecast shows for our DSS event. By 02z this evening, it shows increasing CAPE invof the DSS event. They are not out of the woods yet!

However, ProbSvr3 and LightningCast continue to provide a general idea that the strongest cell remains north and west of the Miami Open, limiting any impacts during the event.

Looking at the PHS imagery, it shows continued moderate CAPE extending into SW FL invof the ongoing convection, with much lower CAPE near our DSS event.

And the projections for 00z this evening show CAPE lowering further.

20z PHS Composite Reflectivity compared to MRMS Composite Reflectivity persistently highlights a lot of noise. Understanding from a forecaster’s perspective, this can be mentally filtered out, but at the same time, remains to be a distraction from the overall product’s use.

The warned cell over Glades county weakened and merged with other convection, and accordingly, the LightningCast probs declined. But we’re seeing new vigorous convection to the WSW just north of Bonita Springs.

One interesting note. There are new cells developing in far SW FL with lightning noted on GLM, however the cirrus canopy there is too thick to allow LightningCast to detect this convection.

– Edgar and Harvey Specter

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LKN LightningCast DSS Event Evaluation

Several pop-up storms developed in the Elko forecast area Tuesday afternoon. To provide DSS for the Elko Airshow, we looked at lightning products, such as GLM and LightningCast (shown here). There were noticeable differences in northern Nevada between the GOES East CONUS and GOES West Meso Sector satellites. This provided a bit of a conundrum of which satellite would be best to use for our DSS event. However, we noticed the trends in lightning probabilities (time series shown below) were increasing for the Elko Airport area for both satellites, so we hedged on that and blended both to arrive at probabilities. In this case, Lightningcast proved to be a useful DSS tool, as lightning was observed within 5 miles of the DSS event by 2056Z.

GIF showing the difference between GOES East CONUS and GOES Meso West products over northern Nevada.

LightningCast time series trends for Elko Airport.

– Bolt and Burton Guster

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Albany and Columbia WFO for the HWT Testbed

The environment is mostly within northwest flow, so some decently sheared storm tops are noted on the OCTANE speed product, ranging from about 25 kts to 60 kts at anvil/storm top level.

The OCTANE Speed Product over eastern PA.

DSS for Twigs Craft Fair – Speculator, NY.

Increased lightning chances developing and going up over 50% now at our DSS site. This is a concern as people at the festival will likely need to take shelter soon as storms approach from the north. Lightning is possible ahead of the storm given the environment it is in and favorable synoptic setup.

GOES 16 GLM and LightningCAST near our DSS site at Speculator, NY.

Additional imagery with a zoomed-in view.

The overall storm top speeds line up fairly well with SPC Mesoanalysis between the 300mb and 500mb layer where speeds of 40-80 kts are noted over eastern PA and western Long Island, NY. Our storms have between 50-70 kts of speed at storm top, so it lines up fairly well with what the RAP mesoanalysis has. Very interesting. See the images below.

3:35pm CT: 1-min LtgCast has increased to ~90% at DSS point, with GLM showing ~1-2 flashes/5min.

Interesting feature on a storm over upstate South Carolina to the west of Columbia. Some weaker winds aloft behind the overshooting top of the storm. Additionally, cooler cloud top temperatures are noted in the overshooting top. Increase in PSv3 values are notable as well with a ramp up in severe threat. The storm was severe warned at this time.

Additionally, you can note the fairly decent divergence aloft at anvil level with the OCTANE direction product.

-Satellite Steve & Displar

 

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Severe Cell in TFX CWA

At WFO Great Falls (TFX), we made use of the Octane speed and direction imagery, plus the IR brightness and day-cloud phase distinction to evaluate a cell northeast of Iliad. This imagery helped us screen the multiple cells over the CWA so we could home in on this particular cell. Characteristics that stood out included the higher anvil speeds on this cell, the diffluent cloud top signal on the Octane direction imagery; the cooler cloud tops (around -62C), and new/robust convection noted by DCPD.

4 Panel OCTANE depiction of severe warned storm near Iliad, MT.

Meanwhile, the cell closer to the Canadian border is becoming stronger. The ProbSevereV3 is trending higher for total severe, up to 19% at 2104Z. The anvil from the storm to the south is beginning to impinge on the cell to the north and somewhat obstruct the view.

The PHS imagery showed a regional peak in MUCAPE in this area.

Looking a bit later, the total ProbSevere continues to climb. It is well above the individual probabilities, which is curious.

Storms have matured with a notable V notch of cooler cloud tops and warmer tops to the north of the notch. Based on Octane speed, there is a notable difference in speeds from the southern end of the anvil to the northern reaches with 35-40 kts increasing to 65-70 kts. PSv3 does indicate a 50% chance for severe with this storm.

Meanwhile, down in CA, northeast of Sacramento, the Octane direction product is showing an impressive divergence signal!

–  Satellite Steve and Edgar

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BRO PHS COMPdBZ comparison

Here is a comparison of the 15z  PHS Composite Forecast at 21z to the 21z MRMS Composite Reflectivity. Notice that the PHS has more widespread convection than what actually occurred. However, the PHS did forecast the translation really well (not shown here), which would aid forecasters in understanding where current convection is likely to travel.

21z MRMS Composite Reflectivity

15z PHS Composite Forecast for 21z

– Burton Guster, StormofCentury, Harvey Specter

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