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The MRMS MESH algorithm predicted a maximum hail size of 1.34 inches with a thunderstorm across far southwestern Harnett County on the 1930z image. A report of quarter sized hail was received with this storm at 1937z to the southwest of Pineview, NC.
I compared the MR/MS MESH to the legacy SCIT hail algorithm. MESH values were lower. Perhaps this is an improvement over the high bias inherent in the old algorithm…or maybe just a result of differing resolutions. Quarter-sized (1.00 in.) hail was reported with this storm.
HIRSCH
The UAH-CI algorithm displayed two areas with high strength of signal values (64 and 92) across southern Cumberland and western Sampson counties on the 1702z image. These cells intensified quickly into two thunderstorms and a report of penny sized hail was received from the eastern storm at 1823z, more than an hour after the algorithm first detected these thunderstorms.
The CIMSS-CTC algorithm showed cloud top cooling rates of between -10 to -15 C/15min on several images with a thunderstorm developing across Sampson county in North Carolina. The CTC first appeared on the 1715z image and continued to highlight this cell through the 1815z image. As the algorithm continued to show moderate cooling rates with the cell the radar presentation became more impressive and a three body scatter spike developed with the cell. A report of penny sized hail was received with this cell 1823z 5 miles WSW of Newton Grove, NC.
Forecasters are beginning the day in NC/SC region, specifically starting in the Raleigh and Wilmington CWA’s. Storms were already going as we initialized in the area, but are expected to grow in strength and coverage over the next couple of hours. All the products and algorithms seem to working well over the region (only lacking total lightning coverage by an LMA, though this region may have coverage in future years!). Multiple storms have already been flagged by the UW-CIMSS Cloud-top-cooling product with min values as low as -26 to -27C and warnings may be issued shortly by the forecasters as they get settled in the new operations/CWAs.
We’re still watching the other SPC slight risk area for later this afternoon and early evening. It is likely we will make a switch (for at least one of the teams) to the central plains (likely Hastings/Omaha CWAs) if we start to see a CI signal. Like yesterday the high-res models seem to want to initiate convection along the front by 2100 UTC, though moisture continues to be an issue over the region with dewpoints in NE CO in the upper 30s to mid 40’s increasing to only the mid 50’s over central KS/NE. Unlike yesterday over the Dakotas where a thick cirrus shield covered the region, skies are pretty clear over KS with a bit more cloud coverage behind the front in central NE. If and when storms develop, steep lapse rates and deep layer shear point to the likelihood of supercells with large hail and damaging wind (especially with the large dewpt depressions).
-Kristin Calhoun, Week 3 Coordinator
We will be operating a 1-9 pm shift tomorrow. Although the cap will probably be an issue earlier in the afternoon, we expect supercell thunderstorms to form by early evening across the south-central Neb & northern KS.
Another consideration are the data limitations after 9pm. Since we share supercomputer time with the NSSL-WRF, 3DVAR calculations end at 9 pm.
-Kristin Calhoun, Week 3 Coordinator
It’s becoming increasingly evident that 3D-VAR’s maximum composite updraft and max divergence above 8km can be utilized as a good “head’s up” display of the largest storms on the scope. This can be seen in the image below.
As described in this blog a few hours ago, storms developed S of Pecos due to ongoing diabatic heating in an environment modestly supportive for strong/isolated severe pulsating storms. Thunderstorms rapidly grouped in a loosley organized convective cluster, which gradually approached the NM boarder during the following hours. At 2300 Z, both IR showed the peak of activity/organization of that cluster with a constant weakening trend thereafter. However, the synthetic one caused a rapid decay of that cluster until 0100Z, whereas real time IR data still indicated a large cluster with cloud top temperatures of below -50 degree celsius at that time. Also, lightning activity was still present at 0100Z with that cluster although a rapid decline was also noticed until 0130 Z. So peak strength was captured well with a too fast decline of the cluster’s strength thereafter.
The synthetic IR did also an outstanding job in highlighting the area of initiation (both timing and the region…not shown).
Helge
Refer to the northern-most storm in the below images. Between 0045 and 0100 UTC, explosive thunderstorm growth occurred southwest of BIS, rapidly becoming severe as evidenced by 50-60+ dbz well above the -20 and -30C heights and mid-level rotation per BIS SRM. 3D-VAR products such as maximum composite updraft speed and max divergence above 8km picked up on this explosive thunderstorm growth, as shown in the 4 images below.
MR/MS MESH showed up to 2.76 inches with the stronger of these two cells. The cell to the southeast produced golf-ball sized hail, per spotter reports. This would lead me to believe that the stronger cell is no doubt producing large hail and I would feel confident issuing a strongly-worded SVR.
HIRSCH
