Active Weather Ahead… Quick Midday Tuesday Update – 12:15pm #alwx @wvua23
January 17, 2017 Leave a comment
Good Tuesday midday! I’m carefully watching 2 storm systems that will impact our weather this week and into the weekend. The first round of heavy rain and storms will arrive Thursday evening, ending Thursday night. The second round of heavy rain and storms will arrive sometime Saturday night into the day on Sunday.
Above is a simulated radar off the RPM, which is a high resolution computer model. A vigorous shortwave trough will swing eastward across the southern Mississippi River Valley, sparking the development of a weak surface low and providing lots of uplift to enhance a risk of heavy rain and storms. Instability will be lacking with this event, but there will be enough wind shear, uplift and instability combination over west Alabama for a small chance of storms becoming strong and possibly a severe storm or two. The main time frame would be 5pm Thursday through 2am Friday. Gusty winds would be the main risk, but an isolated spin-up tornado isn’t out of the question. Given the expected widespread heavy rain, the severe weather risk should remain really low.
Our next system to watch arrives over the weekend. This one is much more impressive given the uplift, wind shear and available instability. Above is a look at the 500mb vorticity. This shows a very deep upper air trough axis becoming negatively tilted. The energy with this system is impressive.
A deep surface low will develop over Texas and move northeast into the Arkansas and Tennessee. This should place central and west Alabama in the prime location for strong to severe storms, but all of this could easily change. The placement and strength of the surface low could change, increasing or decreasing the risk. I have seen a few model runs track the low right across central Alabama, which would limit the risk for the northern half of the state. There is also a possibility of widespread coastal storms, which would block the inflow of unstable air into central and west Alabama. I think there is a fair chance storms on the coast limit the risk, but there is no doubt this one needs to be watched carefully. Keep checking back for more updates as we get closer to the weekend and as forecast confidence increases. This could easily turn into a heavy rain event with some storms or it could become a serious severe weather threat. For now, there is too much inconsistency in our data to lay out a specific threat.
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WVUA Chief Meteorologist