Weather Blog: Heavy rain, severe storms

Weather Blog: Heavy rain, severe storms

MONTGOMERY, AL (WSFA) - The simplicity of this morning's forecast is something to appreciate. It's one of those times where we realize we must enjoy it while it lasts. Our forecast becomes immensely more complicated over the next 48 hours. Periods of heavy rain and strong/severe thunderstorms could be a player in our forecast Thursday into Friday. But it's not that simple. There are many complicating factors that could swing things one way or the other. And THAT is why I'm enjoying this morning just a little more than usual...

TODAY: Sunshine is being filtered by a thin layer of clouds overhead, a layer that should gradually thicken as the day wears on. A developing storm system to our west is still in the process of getting going. For us today, it's just a cloud issue. No rain expected during the daytime hours. Highs should climb into the upper 70s ballpark.

OVERNIGHT: Lows will be very mild for this time of year, likely not falling out of the 60s. Showers and thunderstorms will begin to overspread western Alabama after midnight as spread eastward from there. Not a soaker of a night at all, the the first waves of rain will work in overnight.

THURSDAY'S MESS: Boy...where to start with this one? Model's advertise an initial wave of rain and storms working west to east early Thursday. That could make for a wet commute for some, but I don't envision a completely covered radar.

Much of Thursday's severe weather risk stems from this morning batch of rain, which we do not anticipate will be severe. Our attention will be focused on what happens AFTER that first round of rain. There is evidence to support breaks in the rain/clouds developing into the afternoon.

This element is critically important to the whole forecast. If those breaks develop, we'll be in severe weather model. If those breaks do not develop, instability will be hampered and really limit our concern. Models ramp up instability values west of Alabama into the afternoon, likely the product of anticipated breaks of sunshine. We remain somewhat hesitant to advertise anything more than an isolated severe weather threat at this juncture given the questions around just how much juice we can establish behind that first wave of rain.

The SPC has upgraded the Slight risk to an Enhanced risk for much of Mississippi and western Alabama where the odds appear greatest for sufficient instability to redevelop. Understand...we are not saying our severe weather threat isn't worth paying attention to here. It's entirely possible that Enhanced risk will need to be expanded eastward into our viewing area. But that prospect is hinging heavily on rain/storms to our west that have yet to develop. If that initial waves moves in and out quickly, our concern level goes up.

Damaging winds and isolated tornadoes will be possible if we can establish enough energy.

So what about timing? The first wave of early rain/storms is expected to remain below severe criteria. The main window of concern would begin into the early afternoon and perhaps linger into the overnight.

FRIDAY: The frontal boundary never quite pushes completely through, so we're back in rain and storm mode Friday. We're back in a Slight risk area Friday. Bands of heavy rain will continue to be a possibility, adding to the threat of flooding that we'll already be paying attention to. The GFS is quick to get rid of the rain late Friday, but the European and especially NAM generate another ripple along the front and keep us wet through Friday night and even early Saturday. Rainfall totals will be robust, in the 2-4" range on a general level with pockets higher than that a distinct possibility.

BOTTOM LINE: Remember back to late December when we had that whole south Alabama flooding episode? That event featured an extended period of isolated strong/severe storms that transitioned more into a flooding issue later in the life cycle. I'm certainly not comparing this forecast to that one, rather simply pointing out similarities. We'll need to be aware of the potential for severe storms both Thursday into Friday...but not discount the heavy rain and flooding element of this. While widespread flooding is not anticipated, bands of training thunderstorms have the potential to create localized pockets of substantial rainfall totals outside our 2-4" window. Fortunately, the area of real estate affected in that circumstance tends to be rather small. But it's not to be ignored. Slow moving/stalled boundaries with rich moisture (like this) have a tendency to cause flooding issues in this part of the world.

So, yeah. I'm enjoying this filtered sunshine a little more than usual :)

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