SPC's convective outlook for Tuesday.

in Breaking News, General, Severe Weather

Weekly Forecast: Tornadoes, Flooding, and Damaging Winds

I have not done a weekly forecast like this in a long time, but since many of you have expressed interest in reading a weekly forecast, I have decided to do one. Please understand that these forecasts will improve over time, and I apologize in advance if I did not cover your area in this first outlook. It’s hard for one forecaster to cover the entire United States, but I did my best to hit the high points.

Short-range Forecast (Sunday evening through Wednesday morning): 

Sunday evening: A strong mid and upper-level trough will be moving from the Rockies and pushing south into the Southern Plains by tonight. At the surface, a low pressure system is going to continue to strengthen as it moves east over the Southern Plains tonight and will eventually move northeastward from the Southern Plains tomorrow. Storms should really begin to fire later this afternoon and early evening over the Oklahoma and Texas panhandles and continue to develop and push eastward ahead of the associated cold front into Oklahoma and northern Texas and eventually Arkansas into the late evening/early morning hours, which will continue through the morning hours.

There is going to be a window of opportunity for isolated tornadoes to develop later tonight going into the early morning hours in northern Texas including the Dallas area, portions of eastern Oklahoma, and extreme western portions of Arkansas. Especially if discrete storms develop ahead of the main area of convection, this could lead to some trouble, so this needs to be watched. The severe weather threats that I am more confident will occur are flooding and damaging winds. Flood watches have already been issued for portions of eastern Oklahoma, southeastern Kansas, and western Arkansas, since these areas could get several inches of rain in a short amount of time. Even regions around the watch area need to also monitor the flooding situation.

Projected radar for early Monday morning from the HRRR model.

Projected radar for early Monday morning from the HRRR model.

Monday and Monday evening: As the surface low pressure system moves northeast and the trough becomes more amplified and moves eastward, the severe weather threat will continue to be a problem on Monday and Tuesday out ahead of the associated cold front. I’m currently keeping a close watch on the lower and mid Mississippi River Valley region, where environmental conditions could become favorable for tornadoes. Although CAPE values (instability) will not be impressively high, high deep-level wind shear will be plenty sufficient with this system to produce an environment that is favorable for discrete supercells to develop and produce tornadoes. In fact, a couple of these tornadoes may be strong. The Storm Prediction Center is considering upgrading some regions to a moderate risk in their next outlook. The region that really needs to watch the tornado threat on Monday will be eastern Arkansas, northern Louisiana, northern half of Mississippi, western Tennessee, and southeastern Missouri. Please note that tornadoes will not be the only threat, but that damaging winds will also be a big threat as a squall line will likely move through all of the mentioned regions.

Flooding will also be an issue in many of these regions on Monday, including Arkansas, Mississippi, Alabama, Tennessee, and Kentucky, and flood watches could definitely be issued for many of these areas later on.

SPC's latest convective outlook for Monday.

SPC’s latest convective outlook for Monday.

Tuesday and Tuesday evening: Tuesday gets a little more difficult to forecast, and I’ll explain why. The mid and upper level system will continue to race eastward, pushing the severe weather threat into eastern Alabama, Georgia, Florida panhandle, Upstate and Midlands South Carolina, eastern Tennessee, and western portions of North Carolina. Most of these regions will likely experience strong winds due the a squall line that will be pushing through the area. Where things get a little more uncertain is the tornado threat, and because I feel that there could at least be isolated tornadoes on Tuesday, I wanted to mention it so that you all aren’t caught off guard if this occurs. This is an example of a low CAPE/high shear setup, meaning that the environment may not be particularly unstable but the high shear environment may compensate for the lack of instability. I have seen cases where this region can get several tornado touchdowns due to this kind of setup, and the people living there be caught off-guard by it. I would not even be surprised if a tornado or two occurred within the squall line of storms that moves through the area. So the area I am watching most closely is Georgia, Upstate South Carolina, and the Southern Appalachians. It could really go either way, so I just wanted to mention it.

Even if no tornadoes occur that day, the damaging wind and flooding threat will be in place over most of these areas. Flooding rains is a danger that is often overlooked by forecasters and the general public.

SPC's latest convective outlook for Tuesday.

SPC’s latest convective outlook for Tuesday.

Conclusion: I’m going to go ahead and end this article since it is already getting a little long. Again, I know that there are regions that I left out that I will try to include in future weekly forecasts. This weekly outlook was completely about the expected severe weather, but on weeks when we don’t have any big weather events occurring, I should be able to extend this outlook to 5 to 7 days and cover more regions.

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