EWP Blog

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

3DVAR total wind and updrafts did a great job picking up the strong-severe winds over Berkeley county.  Total wind increased at 1945z through 2000Z while updrafts continued to strengthen.  Between 2005-2010Z, updrafts weakened while the total winds depicted stronger winds descending; helicity was 50+m/s .  Nunez

Two images are shown here.  On the left, a line of storms extends along the South Carolina coast and into portions of southern Georgia at 2014Z. Earlier at 1945Z, on the right, the UAH Convective Initiation product showed 3 areas of 60%.  Initiation was predicted along and just ahead of an outflow boundary, and just off the coast oriented west southwest to east northeast.  The product performed very well, with around 30 minutes of lead team for the updrafts that exhibited +35dBZ.

Cloud to cloud lightning was observed in a very weak storm in Osceola County.  pGLM flash rates are observed in the upper right and lower left images depicting the cloud to cloud lightning.  Cloud to ground lightning was not observed with this storm as depicted by the absence of strikes in the lower right panel.  This data proves that this weak storm had an updraft strong enough to produce cloud to cloud lightning but not cloud to ground lightning.

I feel that adding cloud to cloud lightning data will really help storm warnings, fire weather applications, aviation forecasts, etc. if added as a baseline product for WFOs because we’re obviously missing a lot of lightning data not only in weak convection as this example shows but in strong/severe storms as well.

AMS/Hovis

Storm that prompted the Beaufort/Charleston/Colleton counties warning showed near 40kt as the gust front advanced east.  Interestingly, the 3DVAR depicted a total wind field that simulated the potential of winds descending behind the advancing storm.  This field is a great asset especially if the warning forecaster encounters radar limitations during the warning processes.  nunez

updrafts have been weak across the line of thunderstorms.  We are monitoring an isolated storm over eastern Jasper county that was approaching severe strength.  MESH trends:  max 1″ center occurred for one scan while the trend was less 3/4″.  Legacy hail algorithm:  consistent max values at 1″ with one 2″ estimate.  nunez

Nearcast data shows favorable conditions for convective initiation and maintenance through mid afternoon.  The first 2 images of nearcast at 19Z and 20Z show good theta-e values (yellows) at 780 mb (upper left) with a slightly cooler drier environment aloft (greens) at 500 mb (lower left).  Bright greens over central and eastern portions of JAX area support a favorable convective environment.   This analysis combined with soundings and other environment data are supportive of small hail with storms early this afternoon.

19Z:

20Z:

In the later 2 images below at 21Z and 22Z, the environment becomes less favorable for convection as we can see less of a threat of convection as the brighter yellows at 780 mb (upper left) begin to move off shore (a cold front enters the area).  Also at 500 mb (lower left), brighter yellows are observed moving into JAX central and eastern portions of the area indicating more warm/moist mid levels which would be less supportive of small hail and more supportive of heavy rainers given the environment conditions.  The theta-e difference (lower right) depicts most unstable/moist environment (bright greens) moving off shore as well.

21Z:

22Z:

AMS/Hovis

Around 1832z…cloud top cooling product showed strong cloud top cooling for two successive scans in the area of some showers moving across Berrien County in Southeast Georgia.  The showers  rapidly intensified with JAX composite reflectivity showing 55-60 dBZ by 1849z and 60-65 dBZ storm by 1904z.  Hovis/AMS

HRRR output painted the merging of the ongoing line of non-severe storms and new initiation ahead of this line.  CI and CTC showed an evidence of early convective initiation though lead time near 30 minutes.  nunez