Noon Update: Strong Storms Possible Later Today
The thinking is still in line with what we have been saying:
A surface low is over the Oklahoma Panhandle. It will move eastward to southern Kentucky by this evening. A frontal boundary is situated over South Central Alabama. It will move northward this morning as a warm front in response to the surface low. South of the warm front, dew points will be in the 60s, rising into the upper 60s in many spots by afternoon.
A strengthening upper-level trough and strong jet stream level winds will swing eastward today and tonight, enhancing lift for storms. A strong low-level jet (5,000) feet or 850 mb) of 45-50 knots will spread across Mississippi and into Alabama this afternoon. These strong low-level southwesterly winds, along with strong westerly winds running 70 knots at 500 mb, or 18,000 feet, will provide sufficient deep layer wind shear, which will favor supercell thunderstorms this afternoon over North Alabama. This deep layer shear will overspread the rest of North and Central Alabama into the evening hours.
There will be plenty of instability, with CAPE values running over 2,000 joules/kg. This will support powerful thunderstorm updrafts. Strong thunderstorms will start forming over southern Tennessee by early afternoon and will continue developing into North Alabama by mid-afternoon. These storms may affect the Huntsville area as well as other parts of the Tennessee Valley.
A line of storms will form over northern Mississippi by late afternoon, spreading into Northwest Alabama by 2-4 p.m. CDT. These storms will quickly intensify over West Alabama, reaching the I-59 Corridor between 5-8 p.m. CDT, and then down to the I-85 corridor by 11PM CDT.
Storms that form just ahead of the main line will encounter the most favorable instability and shear combination, which would make them especially dangerous. It remains to be seen whether that can happen, with a strong capping inversion potentially helping to keep a lid on the atmosphere. Instability values will drop after sunset as we lose the heating of the day, and hopefully storms will lose some of their punch as they progress eastward.
Storms will have the potential to produce very large hail, as large as two inches or greater in diameter. Damaging straight line winds will be a threat as well. Tornadoes will also be possible, including the possibility of a few strong tornadoes, especially for areas in the enhanced threat area across North Alabama. For us in South Alabama, the threats still exist, but will be less.
As we head into the heart of our spring severe weather season, it is important to plan ahead and always be prepared:
*Be sure you can hear warnings if needed. NEVER rely on an outdoor warning siren; if that is your main way of hearing warnings, you have little hope of hearing them indoors. Have a NOAA Weather Radio in your home or business, and a good app designed for warnings on your smart phone.
*Know the safe place in your home. Small room, lowest floor, away from windows, and near the center of the house. If you live in a mobile home, you have to leave and go to a shelter or site built structure.
*In your safe place, be sure you have a helmet for everyone to wear (not just children)… it is also good for everyone to have a portable air horn, and be sure and wear hard sole shoes.
HELLO SPRING: Tomorrow is the first day of spring as the vernal equinox occurs at 11:15 AM CDT. The weather will be a breezy and a mix of sun and clouds, and there is a chance for lingering showers wrapping around the backside of the low as it departs the Southeast. Those showers should be out of the area by the evening. Afternoon highs will be in the upper 60s, while overnight lows will be in the upper 30s to the mid-40s.
REST OF WEEK: Mainly sunny and drier for the remainder of the work week, and temperatures will be just below normal for Wednesday and Thursday. Afternoon highs will be in the upper 50s to the mid-60s for those days with a good supply of sunshine. Low will be well down into the 30s and we could certainly see some frosty conditions at times early in the mornings. Friday will feature a mix of sun and clouds with slightly warmer temperatures, as highs reaching the lower 60s to the upper 60s.
WEEKEND SNEAK PEEK: Warmer temperatures and the threat for rain and storms will be back in the forecast. At this time, it doesn’t look like a severe weather potential. Both Saturday and Sunday will feature highs in the 70s and lower in the 50s.
Stay safe and have a great day!
Ryan
