A few interesting storms across WFO DMX this afternoon.  Several were severe, with one storm producing hail and quite a bit of damage in and just S-SE of Waterloo.  In this post, however, we will focus on a storm that was a little closer to the radar that did not as of yet produce any severe reports.  Let’s look at a 4-panel of 3DVAR data:

We are interested in the storm that moved from southern Marion County into and through Mahaska County.  Notice the Max Updraft and Vorticity Tracks (lower panels).  These fields stay fairly constant over time along the path of the storm.  This storm did develop some weak low to mid level rotation.  Not the updraft helicity values in the top right that peaked near 100m2/s2 indicative of this.–Gordon Strassberg for WFO DMX.

Thunderstorms continue to build rapidly to the SW along the cold front with initiation underway around 2145 Z over NE Kansas. It is amazing how well the OUN WRF captured the initiation:

Timing was excellent with placement just slightly off to the south. This model forecast would have helped forecasters a lot to pinpoint area of initiation well ahead.

Helge

Severe convection currently evolves along the cold front over C Iowa with Cld top cooling product showing impressive cooling rates below -65 K/15 min e.g. over Warren and Polk counties.

Helge

A weak tropical low moved from Cuba to the NE during the daytime hours and was forecast to affect far SE Florida. Comparing SimSat and real IR/WV data, significant differences can be seen especially regarding the cirrus canopy. The main reason for the differences may be the much stronger development of this depression than expected 21 h ago. NHC also increased probs to 40 %, indicating a consolidating system. This evolution may have resulted in a better defined depression’s center with stronger convective development. Therefore those products may have to be used carefully for tropical lows, which reveal stronger intensification rates compared to what models forecast.

Helge

Westward moving sea breeze front helped to spark sporadic showers/thunderstorms during the afternoon hours. We captured the interaction of an already ongoing weak shower, as front moved in from the east.

The southern parts of Nassau and Charlton county and Baker county were monitored. At 1932Z an increase in cloud top cooling was noticed and 8 min later, CI product also had probabilities of 70 % plus for this area. At the same time, a cooling rate of roughly -15K/15 min was detected. Rapid development occurred thereafter with 50 dBz and more seen in the JAX radar side at 1947 Z, which gave a good lead time for focusing on the potential hot-spot over NE Florida. The storm was a pulsating one with rapid weakening thereafter.

Helge

We’re currently monitoring the rapidly inland moving see breeze front over NE Florida with enhanced TCU present along the convergence zone, whereas the west coast see breeze has trouble to move inland within dominant easterly wind regime. Both convergence zones enter an area over N-C Florida where slightly lower dewpoints (lower to mid 60s) are present. With ongoing diabatic heating, cap continues to weaken or has already vanished with isolated initiation possible over N-C Florida in the following hours but ongoing large-scale weak subsidence seems to delay initiation a bit. HRRR quite aggressive with initiation mainly along the western sea breeze front with RUC also showing sporadic storms over N-C Florida. Overall set-up is not impressive and favors only the development of a few thunderstorms. Moderate CAPE and weak shear environment may result in a few strong and slow moving storms.

Neither CI nor Cld top cooling products showing robust signs for initiation … mainly over C Florida. Both products however show more vivid activity offshore over the Atlantic, where mid-levels remain a bit cooler.

Helge