Flood watch in effect beginning Thursday

Submitted by Danny Hinson

Nassau County Emergency Management DirectorEmergency Management Logo

The following report was provided to NCEM by Al Sandrick meteorologist for the National Weather Service office in Jacksonville.

Tropical Disturbance 91L

5 June 2013, Noon update

“6 inches of rain over 18 hours most of our area can handle even with the saturated conditions, but if that same 6 inches comes down in 4 to 8 hours that is likely to cause problems.”

The disturbance remains very sheared and disorganized in the south central Gulf of Mexico north of the Yucatan Peninsula.  The National Hurricane Center is giving it a 50 percentchance of developing into a Depression or Subtropical Depression/Storm over the next 48 hours, but that is not the main concern. Whether it receives a name or not the main impacts for the northeast Florida and southeast Georgia area will not really change.

Rainfall/Flooding: As indicated above the system is sheared with the heaviest rainfall to the south and east of the surface center. The low center looks like it will track into the big bend area on Thursday and Thursday night and offshore around Savannah on Friday morning, bear in mind that is based on some of the more reliable models but it is possible the center could track further west. In either case that still brings heavy rainfall across the area Thursday and Thursday Night. Currently we expect the main rainfall axis to stretch from the Cedar Key Area northeast into Jacksonville with general rainfall totals of 4 to 6 inches Thursday through Friday morning. Locally higher amounts are possible and flooding of normally flood prone urbanized areasA lot will depend upon the rain rates as the main moisture feed comes in off the Gulf. 6 inches of rain over 18 hours most of our area can handle even with the saturated conditions, but if that same 6 inches comes down in 4 to 8 hours that is likely to cause problems. A flood watch is in effect for Thursday into mid-morning on Friday. If the system moves rapidly, as the more reliable models want to do, we may cancel that early. If the core of the storm tracks further westward we may have to expand that watch to the north and west.

Tornadoes: There is going to be a decent amount of wind shear with this system tomorrow and tomorrow night and it wouldn’t be out of the question to see isolated tornado touchdowns. The good news is the shear is low enough that they should be lower end events (EF-0 to EF-1).

Winds: Honestly in this type of a situation we expect any winds to be concentrated in maritime areas. So even if it were to receive a name (Andrea) any tropical storm force/sub-tropical storm force winds (39 mph) would be over the coastal waters. There might be some wind gusts in the higher structures in downtown Jacksonville but let me emphasize that should it be a tropical storm or subtropical storm, at this time, we do not anticipate strong winds over land areas.

Please continue to monitor our webpage for updated Web Video Briefings through the event (click on the headline banner). www.weather.gov/jax

June 5, 2013 2:31 p.m.

 

Al Sandrik