A very intense day of severe storms is behind us after widespread heavy rain, damaging winds & a few tornadoes. Despite temperatures (& therefore instability) that were only marginally favorable for severe storms, very strong wind fields & extremely favorable dynamics (upper level disturbance/"energy") combined to produce a significant severe storm outbreak Fri. morning. into the early afternoon. One
supercell thunderstorm in particular proved to be very damaging beginning in the Big Bend of Florida & dropping an EF-2 tornado in Taylor Co. about 8:35am...this cell then moved east/northeast & spawned the EF-2 tornado in & near Lake City in Columbia Co. & also likely produced a tornado in Northern Baker Co. just east of Taylor crossing the Ga. border just into extreme Southern Charlton Co. Our Jax N.W.S. reports a 9:45am touchdown with a track 1/2 mi. long & 1/4 mi. wide. Other tornadoes occurred in Brantley Co., GA...5 mi. N/NE of St. George in extreme Southeast Nassau Co....& a waterspout was observed just east of King Bay Base, Camden Co. GA.
The
EF scale is detailed in the table below (from NOAA):
Enhanced F Scale for Tornado Damage
An update to the the original F-scale by a team of meteorologists and wind engineers, to be implemented in the U.S. on 1 February 2007.
| FUJITA SCALE |
DERIVED EF SCALE |
OPERATIONAL EF SCALE |
| F Number |
Fastest 1/4-mile (mph) |
3 Second Gust (mph) |
EF Number |
3 Second Gust (mph) |
EF Number |
3 Second Gust (mph) |
| 0 |
40-72 |
45-78 |
0 |
65-85 |
0 |
65-85 |
| 1 |
73-112 |
79-117 |
1 |
86-109 |
1 |
86-110 |
| 2 |
113-157 |
118-161 |
2 |
110-137 |
2 |
111-135 |
| 3 |
158-207 |
162-209 |
3 |
138-167 |
3 |
136-165 |
| 4 |
208-260 |
210-261 |
4 |
168-199 |
4 |
166-200 |
| 5 |
261-318 |
262-317 |
5 |
200-234 |
5 |
Over 200 |
*** IMPORTANT NOTE ABOUT ENHANCED F-SCALE WINDS: The Enhanced F-scale still is a set of wind estimates (not measurements) based on damage.
Its uses three-second gusts estimated at the point of damage based on a
judgment of 8 levels of damage to the 28 indicators listed below. These
estimates vary with height and exposure. Important: The 3
second gust is not the same wind as in standard surface observations.
Standard measurements are taken by weather stations in open exposures,
using a directly measured, "one minute mile" speed.
Our Jacksonville National Weather Service along with Jamie Warriner & Michelle Jacobs in our First Alert Weather Center are to commended for early & timely warnings.
Rain will move away from the area later Fri. night & will be followed by a very windy Sat. with northwest winds of 15-30 mph but gusts of 40+ mph. Temperatures will be unseasonably chilly with a light inland freeze late Sat. night/early Sun.
The severe storms, heavy rain, high winds & cold temps. are courtesy a deepening low pressure system that will move north/northeast between the Appalachians & East Coast through Sat. with
wide-ranging impacts. Flooding rains will spread into Southern New England while heavy snow extends from the deep south -- parts of Louisiana, Mississippi & Alabama through the Tennessee & Ohio Valley into the interior Northeast & into Southeast Canada.
And the active weather pattern looks like it'll continue for some time with several potentially significant weather systems to traverse the U.S. the next 1-2 weeks. Such active & relatively cold end of the winter/early spring weather patterns are typical during moderate to strong La Nina's.
Earth Gauge:
Climate Fact: Parasite
Populations
From the time of its discovery in
the 1940's until about 1990, a single-celled marine parasite (Perkinsus marinus) was rarely spotted
north of the Chesapeake
Bay. Perkinsus marinus is best known for
causing large-scale die-offs of the commercially important Eastern Oyster (Crassostrea virginica). Since 1992,
however, outbreaks of the parasite have been occurring as far as 310 miles north
of the Bay. The winter water temperature off of the East Coast is an important
predictor of the parasite’s success. If the winter water temperature falls below
37.4 degrees Fahrenheit, the parasite does not reproduce as readily and its
numbers become limited. Since the 1960’s, this temperature has been increasing,
and years when it drops below the 37.4 degree threshold have become rarer. Also
during this period, the parasite’s range has expanded to the
north.
(Sources: Cook, T et al (1998) “The
Relationship Between Increasing Sea-surface Temperature and the Northward Spread
of Perkinsus
marinus (Dermo)
Disease Epizootics in Oysters.” Estuarine Coastal and Shelf Science 46(4):
587-597 and Blander, K.M. 2007. “Global fish production and climate change.”
Proceedings of the
National Academy of Sciences 104(50): 19709-19714.)
Northern Alabama's winter bird populations
are changing. This change includes and influx of birds that have
traditionally wintered in Florida and the Gulf
Coast.
