south side DDC

Looking at southern half of DDC's CWA expecting CI here first along the dryline. Moderate instability exists east of the dryline with deep layer shear sufficient for supercells. Low level winds are veered more than I would like for tornado threat so expect large hail to be the primary threat. Storms are expected to be more isolated as you go south along the dryline further removed from the better forcing. - S Coulomb

Week 1 Day 1 Wrap Up

Yesterday our forecasters operated in Cheyenne, WY and Lubbock, TX CWAs. Weather was pretty quiet but feedback from the forecasters is provided below:

ABI and All-Sky LAP
1 minute imagery helped track individual cu field development under thin cirrus

Cloud phase didn’t help any more just the Vis to analyze initiation

CAPE and LI seemed underdone by about half compared to mesoanalysis

All-Sky LAP seemed to bring values down in the LUB CWA closer to mesoanalysis than what the GFS had which seemed overdone

There was an upward trend in CAPE throughout the day which seemed useful as the day wore on and reports started coming in.

Doesn’t seem to add value but did perform well

Satellite derived CAPE and other products will be useful for off the East coast where mesoanalysis cut off at the coast

A lot of cloud cover caused the layered PW to not be too helpful

GLM

Forecasters really just need to know where the lightning flashes are

Need to be able to see the trend in the color tables to be able to see the cores and to see the increases and decreases better

Open to many suggestions on color tables that would be helpful for forecasters

Having different color curves for the different products would probably be more useful to to pull out the highlights of each product

Want a product that is 5 minute cumulative with 1 minute updates

Just the 1 minute data makes it hard to see the trends than having a 5 minute cumulative with a 1 minute update

NUCAPS

Issues with gridded products coming in the full way so they didn’t see much use

Modified NUCAPS adjustment way overdid the boundary layer moisture with height

NUCAPS seemed to be too cool in the mid levels and the tropopause was too low

30 minutes to an hour latency for the point soundings would be ideal

Anything over an hour would probably not be looked at and seen as out of date

The modified and unmodified were the same and didn’t make any modifications

Modified should at the very least update the surface temperature and dew point to match the RTMA

ProbSevere

Might be useful to display both the all hazards and tornado at the same time to be able to capture the tornado probabilities if they jump up

Interested to see if the probabilities are more calibrated than previous versions

In LUB the storm had a hail spike and ProbSevere went up to ~55% which with both of those prompted a warning

Want to be able to have all the hazards in one pane but still be able to easily distinguish between the severe hazards

Lines would probably need to be in different colors than the all hazards ProbSevere

Possibly would be good to toggle through with a key on the keyboard

CI

The GOES West CI over Cheyenne seemed to do better probably due to look angle

In LUB the CI didn’t seem to work too well under a pretty thick cirrus deck where you could see the cu developing in the visible imagery but not really any cooling in the IR

There were some pretty big jumps and then decreases back down

Week 1 Day 2 Operations

Today we will be operating in the Dodge City, KS, Hastings, NE, and Wichita, KS CWAs.

Michael Bowlan

ProbSevere in Lubbock Warning Decision

The first warning decision in the Lubbock CWA was based in large part on the  increase of ProbSevere to above 50% in combination with a three-body scatter spike. The storm decreased in intensity thereafter, and no severe reports were received during that warning period.

- Bucky

first impressions of GLM prods

The color scale for the Flash Area product should emphasize the smaller flash sizes. It rather has the gradient at the high end (~8000 km2) where diagnosis of severe updrafts would be done in the continuous blue color. The total energy product shows very large values (in excess of 1000) with very low flash rates (1-2 flashes/min) which sounds counter intuitive.

Convective Initiation in Lubbock

Given the cirrus cloud cover today, the CI algorithm was unable to provide information in the Lubbock area today where convection developed. Referring to IR data, the cirrus cover was confirmed thick enough to block the signal below. However, convective initiation could be seen in the raw visible imagery.

Figure 1: CI and VIS

- Bucky

Nice Example of ProbSevere Lead Time

Instability had increased in Hall county over the last hour with CAPE near 2500J/Kg, LI -6 to -7 and mid level lapse rate -7.5 to 8.  Ended up with a report of hail to 1.5" (unofficial) at 2314Z.

ProbHail jumped from 29% to over 70% in one update at 2242Z, and remained above 70% for the over thirty minutes leading up to the report.

-Forrest

Lubbock, Texas Severe Hail with ProbSevere

The weather this afternoon was quiet for much of the operations period, but in the afternoon thunderstorms developed along the dryline in the Lubbock, Texas WFO.  Initially storms pulsed (strengthened but then subsequently weakened) with ProbHail values in the 50-60% range.  Figure 1 below shows progression of a weak thunderstorm that slowly strengthened between 2226 and 2238 UTC (ProbSevere values ~20-35%) and then rapidly strengthened from 2240 - 2256 UTC (ProbHail and ProbWind values both first exceeded 80% at 2256 UTC).

Figure 1.  MRMS Composite Reflectivity and ProbSevere (All Hazards) 2226-2312 UTC 30 April 2018.  

The storm continued to strengthen with ProbSevere values in excess of 90%.  At 2313 UTC (1 minute after the final frame of the animation) 1.5" hail was reported by a trained spotter.  This example shows how ProbSevere can provide lead-time ahead of severe hazards (ProbSevere exceeded 80% 19 minutes before the first severe hail report)--which can increase forecaster confidence and lead-time in issuing severe thunderstorm warnings.

-J. Sieglaff

NE CO supercell - ProbSvr

ProbSvr performed reasonably well on this isolated storm despite somewhat unfavorable environment with 73T/37Td ahead of storm as it moved across far NE CO.  The 75% prob hail contour appeared about a scan ahead (2242 UTC) of when I would have seriously considered a warning, it peaked at 93% when the storm was at its most intense. - S. Coulomb.

NUCAPS Sounding in Lubbock

A (green) NUCAPS sounding was analyzed ahead of the dry line in the east-central portion of the CWA (Fig 1).

FIgure 1: NUCAPS sounding availability. Hand represents NUCAPS point discussed in this blog post.

The NUCAPS sounding selected indicates CAPE well above what was analyzed from other data sources. SBCAPE is over 4000 j/kg, MLCAPE around 5400, and MUCAPE around 6900.  All three CAPES are around or below 3000 j/kg based on SPC mesoanalysis and hi res model data. Some reasons for the too high of CAPE in the NUCAPS profile, based on comparison with SPC mesoanlysis and other nWP data: 1) the well-mixed layer was unrealistic, moistening too fast vertically and lowering the LCL, 2) the profile was too cold in areas, including around 700 mb. Adjusting for these reasons made for more realistic NUCAPS values. Figure 2 shows the unmodified "modified sounding", while figure 3 shows the modified "modified sounding". The modified "modified sounding" shows thermodynamic fields closer in line with what was likely reality, though probably still slightly high.

Figure 2: Modified NUCAPS (not modified by user)

Figure 3: Modified NUCAPS (Further modified by user)

- Bucky