James Spann: Showers for Alabama Friday, storms Saturday

HIGH CLOUDS: High cirrus clouds have moved over Alabama this afternoon ahead of a complex storm system developing west of the state. Temperatures are mostly in the low to mid 60s, and the clouds become thicker and lower tonight.

Friday will be a breezy, mild day with a high around 70; showers are possible by afternoon. But the main action will be well to the west, where severe thunderstorms will break out over parts of Texas, Oklahoma, Louisiana and Arkansas. The Storm Prediction Center now has the I-20 corridor from Tyler, Texas, to Shreveport and Monroe, Louisiana, in a moderate risk (level 4 of 5); a significant severe weather event is likely there.

SEVERE STORMS IN ALABAMA SATURDAY: New data continues to show a potent severe weather setup for much of Alabama Saturday. The incoming system will feature strong wind fields; the low-level jet (5,000 feet off the ground) will be in the 50- to 90-knot range, which will make for high storm relative helicity values (veering of the wind with height in relation to storm motion). The SPC has about the southern two-thirds of the state (south of a line from Vernon to Birmingham to Talladega to Opelika) in an enhanced risk (level 3 of 5), while a slight risk (level 2 of 5) extends north to the Tennessee state line.

Please don’t get too hung up on the risk categories or colors; all of Alabama has a risk of severe thunderstorms Saturday. With all of the media attention focused on Saturday, I know some people suffer from anxiety and worry. Even on a significant severe weather day, odds of any one spot being affected by a tornado are relatively small. Simply be prepared and we will get through the day together just fine.

TIMING: The main window for severe storms over the western side of the state will come from 10 a.m. until 4 p.m.; for the central counties the window is from noon to 6 p.m., and for east Alabama 2 p.m. until 8 p.m. This will be a generally daytime event.

THREATS: A line of storms will sweep through the state Saturday with potential for damaging winds and a few embedded tornadoes. Any discrete cells that form east of the line will be capable of producing a few tornadoes as well. Based on the forecast parameters, a few strong tornadoes (EF2 or higher) can’t be ruled out. Also, some hail is possible with the heavier thunderstorms. Away from thunderstorms, pressure gradient winds will be fairly robust during the day Saturday; expect a south wind averaging 15-30 mph with gusts possible to 40 mph. A wind advisory has been issued for much of Alabama Saturday.

RAIN: Rain amounts Friday night and Saturday should be around 2 inches for much of Alabama; some flooding is possible. Seven-day rain totals, through Thursday of next week, are in the 4- to 5-inch range over north Alabama, with 3-4 inches for the southern counties as more rain is likely next week.

CALL TO ACTION: Everyone will need a good, reliable way of getting severe weather warnings Saturday if they are needed. Be sure wireless emergency alerts are enabled on your phone, and download the free ABC 33/40 weather app as well. Have a NOAA Weather Radio in your home and business. Never rely on an outdoor siren.

Identify the safe place in your home. In a site-built home, it is a small room on the lowest floor, near the center of the home and away from windows. Be sure everybody in the family knows where that safe place is, and in that room you need helmets for everyone in your family. We also recommend having a portable air horn for everyone, as well as hard-soled shoes. If you live in a mobile home, you cannot stay there if you are in a tornado warning polygon. Know the location of the nearest shelter or site-built structure that is available.

Is a tornado threat in January unusual? Not really. Alabama has experienced 139 tornadoes during the month of January since 1950. Tornadoes can happen during any month in our state, but the most active period is between November and May.

Do I need to cancel my event Saturday? I’m getting many questions about both indoor and outdoor events. All of them involve a different set of circumstances, and there is no way we can make that decision. Just keep an eye on these discussions; you will have the information you need to make an informed decision.

Sunday will be dry with a mix of sun and clouds; the high will be in the mid 60s.

NEXT WEEK: Moist air returns, and we will have a cloudy sky with periods of rain Monday through Wednesday. No severe storms are expected, and highs will be in the 60s as mild air continues to cover the state. Cooler and drier air returns Thursday and Friday with highs back in the 50s, at seasonal averages for Alabama.

ON THIS DATE IN 2006: With cold air sweeping in from the Himalayas, New Delhi reported frost for the first time in 70 years with a low temperature of 32.3 degrees. The cold prompted officials to order all schools to close for three days.

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For more weather news and information from James Spann and his team, visit AlabamaWx.

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