Entries in Storm Structure (17)

Sunday
May202012

Tornado Warned Storm Okeechobee-Martin Counties

Hard to believe how active the Florida storms have been lately, and yesterday afternoon put on yet again another interesting show. The storm of the day, at least for me, was the tornado warned cell in southeastern Okeechobee County.

Looking NNE - Developing wall cloud with strong rotation along US 411.

The storm first initiated in the northern part of the county and slowly tracked southeastward. At the same time, a large multi-complex of thunderstorms was ongoing over Palm Beach County, and this area of weather produced a large stout outflow boundary that shot off to the northwest over the lake and western Martin County.

As the cell moved into the Okeechobee City region, it still looked liner and "outflow'ish", but I could see just to the east a new flat base developing on the leading edge of the older core. So, I relocated southeast down U.S. 411 to near the waterway lock (S-191) on the rim of the lake and a few miles to the north of 15A.

I watched as the cell continued southeastward, and beginning to interact with the strong outflow boundary coming in from the east-southeast. This is where the storm structure took a drastic change over just a few minutes, with a wall cloud developing with rotation just north of my location.

In the picture above, I'm looking north-northeast into the area of strong rotation, with a rain/hail curtains wrapping in behind and to my left. Lightning was intense, and my surface winds quickly shifted from the east to northwest about the time of this photo. Also, I could hear the tones coming from the radio that The National Weather Service in Melbourne had just issued a tornado warning on this storm.

AT 328 PM EDT...NATIONAL WEATHER SERVICE METEOROLOGISTS DETECTED A SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO NEAR FOUR SEASONS ESTATES...MOVING SOUTHEAST AT 10  MPH. - NWS MLB

I continued to shoot off pictures (should have shot video too, ugh) while the rotation tightened a little more. I could hear and see the heavy core coming in from behind and packed up once again to relocated down the highway. I drove southeast again down U.S. 411 keeping close eyes of the wall cloud and  my road network. When I got down to 15A, the storm looked like it was struggling again with outflow winds overtaking the weakening inflow. Also, more rain had developed to the southeast of the cell and that likely was disrupting the inflow as well at this point.

Radar imagesDoppler Radar base velocity and reflectivity images via "RadarScope" on the iPad3.

The cell continued to try and maintain it's rotation but was having a very hard time, and it was losing its structure almost as fast as it developed 15 minutes earlier. Thankfully, the storm never produced a tornado on the ground, and I was very impressed on how fast the NWS in Melbourne issued the warning while I was watching the storm structure unfold in front of me.

Friday
May182012

FL Storms Stronger and More Isolated Today - Photos

Another Florida Afternoon Local Storm-chase.

Today brought more strong to low-end severe storms to south and central Florida. Unlike the last few days, storms were a little more isolated as drier air moved into the region, but with stronger surface heating under full sun, it wasn't long before cell's began to develop with some becoming severe.

The east coast sea-breeze boundary was more defined compared to the last few afternoon's, and penetrated further inland interacting with the lake breeze boundaries setting off the first storms of the day. These initial thunderstorms produced outflow boundaries tracking northwestward over western Palm Beach and Martin counties and converged with the west coast boundary.

This impressive convergence developed more robust convection into eastern Glades County, and this is where I first got on my cell of the day. It took a little while for the storm to become more surface-based, but once it got rooted it took off.

I chased the storm into Okeechobee and western St Lucie Counties, where it become more organized, and at times showed some signs of low-level rotation as it tracked east-northeastward, but would get undercut shortly after. The lightning was very intense, and I had only a few small opportunities to get out and roll video and shoot photos. Once the storm became more outflow dominate nearing the county line, it began producing some strong straight-line winds as I tried to stay ahead.

I finished off with a round of sunset shelf-cloud structure shots before packing it in for the day and heading home. I can't believe how active the rainy season has started off this year for the Sunshine State, have enjoyed it over the hot and dry weather of April.  

Thursday
May102012

Impressive Rain-Foot Storm Structure Martin Co FL

Earlier this afternoon thunderstorms developed over Glades County and we're tracking eastward across Central Lake Okeechobee. When the cluster of thunderstorms reached the extreme western portions of Martin County lake waters, the storms began interacting with the east coast Seabreeze boundary that was moving slowing southwestward.

I anticipated this about an hour earlier and made my way out to Port Mayaca, which is located in Western Martin County on the eastern shore of Lake Okeechobee. I watched as the storms continued eastward and intensified with a significant increase in lightning and storm structure. The National Weather Service in Melbourne, FL issued a severe thunderstorm warning for Western Martin County and I'm glad they did, as you can see in the photograph above an impressive rain-foot was developing and indicates a good chance severe straight-line winds are at the surface.