EWP Blog

Jasper county multicellular storms should increase during recent scans with the hail algorithm showing a max of 1″.  MESH should less than 1″.  Convection is about to merge with the ongoing activity along the coast and will likely pull in rain-cooled air within the next 15 minutes.  It is likely the Jasper storms will weaken as they track ESE and no impacts are expected.  Nunez

3DVAR helicity, total wind and comp. updrafts fields support the ongoing convection over southern Colleton county.  Interestingly, the simulated radar reflectivity agree with the HRRR for increasing convection on the southwest flank of the Colleton county storm, and latest total wind hint at a minor disturbance over Jasper county.  Nunez

21Z HRRR 2hr projects that the newest convection south of the severe storm is expected to increase in strength and should organize into scattered coverage across Effingham and Bryan counties.   FYI, the more recent HRRR runs (1-2hr) no longer captured on the ongoing convection in Colleton county.  Nunez

3D VAR Composite Updraft seems to be relatively helpful in confirming the strength of a storm.  However, with some quick pulse storms, the 3D VAR data seemed to lag behind a little.  In the series of images below you can see that the best Updraft strength noted at 22Z (upper right panel of 3rd image) seems to better match radar data from 2154Z (1st image below) rather than 2159Z (2nd image below).  So there seems to be a slight lag with 3D VAR data catching the stronger updrafts in pulse storms, but that’s probably to be expected with this type of storm.

2154Z:

2159Z:

2200Z:

AMS

At 2215z…strong storm was located over Camden County.  3DVAR products indicates updraft maximum values around 13 m/s with an updraft helicity near 33 m/s2.  Visible satellite imagery (second image) is also showing a broad area of higher clouds…possible overshooting top…over Camden County.  Visible satellite image is verifying the updraft information.  AMS/Hovis

19Z HRRR 2hr field indicated that thunderstorm coverage would increase from isolated to scattered along the advancing cold front.  This coverage is expected to remain scattered as it tracks toward the coast.  Nunez

Total wind picked up a weak perturbation on the wind field between 2025Z and 2050Z.  By 2050Z, helicity signature developed in conjunction with the strengthening updrafts/stronger reflectively.  Nunez

At 2032z…storm was pushing offshore from St Johns County in Fl.  The CTC product indicated strong cooling rates approaching -20 DegC/15 minutes associated with that storm.  There was a short period of time when we did not receive any products.  However…the radar showed a stronger storm with increased lightning activity by 2112z.  AMS/Hovis