I'm going to quickly recap what happened with the tornado Wednesday and then we'll talk about sevrer weather chances for Friday.
This is straight from the NWS.
A storm damage team from the National Weather Service Office in Jackson, Kentucky has confirmed an EF-2 tornado in Morgan County. Touchdown occurred about 6 miles southwest of West Liberty near the Grassy Creek community. The tornado track was not continuous, but instead made several touchdowns and liftoffs before dissipating near the community of Malone. Winds were estimated to around 120 mph. Several structures were damaged along the path of the tornado, with the most extreme damage occurring to a residential structure in the Malone area.
EVENT DATE: FEBRUARY 29 2012 EVENT TYPE: EF-2 TORNADO ESTIMATED PEAK WINDS: 120 MPH INJURIES/FATALITIES: 0 EVENT START TIME/LOCATION: 142 PM EST AT 37.87438N/83.37141W EVENT END TIME/LOCATION: 150 PM EST AT 37.87548N/83.25559W DAMAGE PATH LENGTH: 6 MILES DAMAGE WIDTH: 400 YARDS
Now we could see another chance of storms like this one on Friday. The latest from the Storm Prediction Center has most of Kentucky falling in the Moderate Risk Category. Through the years when we start seeing severe weather I like to rmind everyone about what each of the three risk areas means.
Risk areas come in five varieties and are based on the expected number and intensity of severe thunderstorm reports over an area:
The SEE TEXT label appears only on the graphic map. Although there is no cateogorical line drawn for the labeled area, you should read the text of the outlook discussion to be aware of the potential for a threat to develop, if environmental conditions come together. As a rule, the "SEE TEXT" is used on Days 1-3 for areas where severe weather may be possible, but enough forecast uncertainty exists (variability in model guidance, capping, moisture return, or other such factors) to not issue a risk area. Note that the SPC severe thunderstorms outlooks are not meant to cover every single possibility of a severe thunderstorm -- otherwise, severe and general thunder outlooks would often be the same.
A SLGT risk implies that well-organized severe thunderstorms are expected but in relatively small numbers/coverage, or a small chance of a more significant severe event. Not all severe storm events will be covered with a SLGT risk, especially during the summer when short-lived, "pulse-type" severe storms are relatively common during the afternoon.
A MDT risk implies a greater concentration of severe thunderstorms, and in most situations, greater magnitude of severe weather and greater forecaster confidence compared to a SLGT risk. A MDT risk is usually reserved for days with substantial severe storm coverage, or an enhanced chance for a significant severe storm outbreak. Typical MDT risk days include multiple tornadic supercells with very large hail, or intense squall lines with widespread damaging winds.
The HIGH risk implies that a major severe weather outbreak is expected, with large coverage of severe weather and the likelihood of extreme severe (i.e., violent tornadoes or very damaging convective wind events). The HIGH risk category is reserved for the most extreme events with the least forecast uncertainty, and is only used a few times each year.
The outlook categories are related to the specific tornado, damaging wind, and large hail probability forecast graphics on Day 1, and the total severe storm probabilities for the Day 2 and Day 3 outlooks.
In addition to the severe risk areas, general thunderstorms (non-severe) are outlined, but with no label on the graphic map. Within this area, a 10% or greater probability of thunderstorm occurrence is forecast.
Here's the current outlook for severe weather on Friday.
The most specific Convective Outlooks are those issued during the Day 1 period. Accordingly, the SPC forecasters have the most information available to them to differentiate the threats of the individual severe weather hazards. During this period, the SPC produces probabilistic outlooks for each primary severe weather hazard (tornadoes, damaging wind, and large hail) separately. By producing separate forecasts for tornadoes, damaging wind, and large hail, the user is given substantially more information upon which to make decisions than in the categorical (slight, moderate, high) outlook. In addition to the probabilities for separate types of severe weather occurring, areas are shown where there is a 10% or greater chance of significant severe weather. Significant severe weather is defined as F2 or greater tornadoes, damaging winds with speeds greater than 65 knots, or large hail 2" or greater in diameter. If the forecaster believes that there is less than a 10% chance of significant severe weather occurring in the outlook area, then the hatched area will not appear on the graphics.
Probabilistic Outlooks are issued for the Day 2/3 period as well. Since many of the specific details of severe weather forecasting can only be determined hours ahead of time, rather than several days, the severe weather probabilities for the Day 2 and Day 3 Outlooks represent the probability of any severe weather hazard (large hail, damaging wind, or tornadoes) occurring (rather than producing individual forecasts for each hazard). Areas where there is a 10% or greater probability of significant severe weather events (again, defined as 2" or larger hail, 65 knot or stronger winds, and F2 or stronger tornadoes) are also indicated on the graphics, when forecast.
I'll have another update late tonight or early Friday morning!