Complicated severe weather threat today, then cooler rest of the week, rain still in forecast at times

The Storm Prediction Center has again expanded the Level 2 out of 5 risk of severe weather for today to not only include all of our Alabama and Mississippi coverage counties, but now to go as far north as U.S. 64 in our Tennessee coverage counties, with areas north of there in a Level 1 of 5 risk of severe weather.  It’s a very complicated severe weather threat today, that conditionally could be significant if the right circumstances occur… but could also be lessened if widespread storms form down near the Gulf Coast.  Let’s talk about three very possibly and believable scenarios that could happen today…

Scenario 1:

The first possible scenario would be that a large cluster of widespread rain and storms forms near the Gulf Coast or in south Alabama by late morning and then lingers down there through the afternoon.  Should that occur, unstable air would be blocked from being able to move northward into the area because the low-level jet would be disrupted, and rain-cooled air from that cluster of storms could move northward into the area instead.  That may not necessarily completely kill the severe weather risk, but should that happen, that would at least lessen the risk some.

Scenario 2:

Scenario #2 would still see showers and storms form to our south.  I don’t think there is any way we can 100% completely avoid that.  HOWEVER, this scenario would have them either being much more scattered and less organized and widespread and/or they are delayed until the afternoon before they form and they end up shifting more to the east down there.  If this scenario were to play out later today, it would mean less disruption of the low-level winds and the transport of unstable air northward into the area.  This possible scenario would lead to a greater severe weather threat areawide, and quite possibly a significant threat.

Scenario 3:

Scenario #3 is kind of a hybrid of the first two, and based on current radar trends, is very possible.  It is starting to be depicted by some of the high resolution models.  This scenario would be similar to Scenario #2 above in that storms to the south near the Gulf Coast are much less widespread and scattered, and that would allow unstable air to come northward across Mississippi and Alabama.  However, this scenario would keep the showers and storms over north Mississippi and Alabama this morning hung up over the area into the midday or early afternoon hours.  That would help to reduce some of the instability in far north Alabama and far north Mississippi, but it may set up a small-scale boundary in our southern counties for storms to interact with later in the day.  Should this scenario occur, it wouldn’t necessarily kill the threat for areas north of that boundary either, but it would mean the higher tornado risk would be in our southern counties, places like: Marion, Winston, Cullman, maybe Franklin, Lawrence, and Morgan Counties of Alabama.  Should this scenario occur, these are counties I would want to pay particular attention to, since any discrete storm interacting with that small-scale boundary would have an enhanced tornado risk.

Any of these scenarios are very believable, and it will be mid to late morning before we have a good handle on which one is most likely to happen, when we see if the storms over our area this morning get hung up over us or if they break up and/or begin lifting north… and we see how soon and how widespread storms are down south of us near the Gulf Coast.

 

Regardless of which scenario plays out today, the strongest storms will have the potential to produce damaging wind gusts of 60+ mph, hail to penny or maybe quarter size, and the potential for tornadoes.  This appears, at this time, to be more of a scattered and cellular type of storm mode instead of a solid line of storms.  That means that not everybody is going to get a strong storm later today, but any of the storms that do form will have the potential for all these hazard types.  Because of the cellular type of storm mode, that means there is the potential for supercells.  That doesn’t automatically mean big tornadoes.  However, if Scenario #2 or Scenario #3 were to play out, I can’t rule out the Storm Prediction Center upgrading the risk to Level 3 for some to-be-determined part of the region for a threat of a couple of strong tornadoes.  That’s very uncertain and conditional risk, but it is a valid risk that could come to fruition if the atmosphere is able to destabilize later today.

As far as timing, that is going to be tricky today too with such a complicated forecast scenario AND this being waves of scattered cellular storms and not one solid line.  Because of this, our timeline graphic today is just going to show a general time window where we want you to be alert and pay attention to the weather.  It’s NOT going to storm during this entire time for your area, but this is the window of time where we want you to be paying attention and listening our for watches and warnings, and we want you READY to act immediately if a warning is issued for you area.

In addition to the potential for severe storms, there is an increasing concern for flooding potential as well.  Forecast rain totals over the next five days are in the widespread 2 to 3 inch range, which much of that expected today and tonight.  Locally higher amounts are very possible, especially if rain and thunderstorms get hung up over the area along that small-scale front and train across the area.  Because of this, we may have to worry about localized flooding or flash flooding today, and don’t be surprised if flash flood warnings get issued this afternoon or tonight.

The cold front associated with all this moves through later tonight into early tomorrow, bringing an end to the heavy rain and storms.  Temperatures will be going the wrong way tomorrow, with low 50s during the morning dropping into the low 40s or upper 30s by late in the day.  Clouds and showers will linger behind the front, and as another disturbances moves through tomorrow night from the northwest, lingering showers may change over to scattered snow flurries as temperatures drop into the upper 20s and lower 30s overnight.  No accumulations or travel problems are expected, but we can’t ever rule out a dusting in the grass or on cars and rooftops/porches when even flurries happen.

That moves out during the day on Friday before another disturbance brings the next chance of rain on Saturday.  We’ll have to watch temperatures then too, especially for our northeast coverage counties, but for right now, we are forecasting all rain.  After that, a warming trend starts as high pressure shifts to the east and winds become more southerly going into next week.  Shower and storm chances return next week as well, with highs back in the mid 60s.  After that, we will be watching another potent looking storm system by the middle of next week, just beyond the range of our seven day forecast period.