Subtle Pattern Changes Ahead

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This past week has certainly shown the challenge of trying to forecast showers in the Southeast US. Subtle changes in the pattern often result in shower development that was not completely expected. Such was the case overnight with the small cluster of showers currently moving through East Central Alabama. The Birmingham airport picked up about 6 tenths of an inch of rain from those. Forecasting the coverage of storms from day to day remains a challenge.

Patchy fog had developed overnight in spots especially those locations where rain fell yesterday afternoon and early this morning. Fog may be dense in spots, but I do expect to see the fog burn off between 9 and 10 am.

So today looks to be a little more typical of summertime with the heat of the afternoon the main driving force in producing scattered showers. Highs will be in the range from about 88 to 91. For beach goers, summer showers will occur along the Gulf Coast with highs generally around 90. Expect about 5 to 7 hours of sunshine.

The northwesterly flow pattern continues today and into Monday, but the next significant disturbance seen in a cluster of storms over Southeast Kansas is forecast to weaken as it progresses east and southeast in that northwest flow. By Monday and into Tuesday, the upper ridge to our west nudges a bit eastward shutting down the northwesterly flow as the upper flow goes more zonal for the southeastern US. This should keep the disturbances riding through the flow to our north along a boundary that sticks around the Ohio River Valley and Mid-Mississippi River Valley area. So for us we will be primarily seeing daily shower chances as a result of daily heating. Another way to say it is a fairly typical summertime pattern of daily shower chances. While the flow appears to go more zonal, we will still need to be watchful for those mesoscale convective systems (MCSs) that may progress across Tennessee. While they will likely stay to our north, these systems also lay down additional boundaries which can be an additional focus for thunderstorm development.

By the end of the week, there is a strong wave moving through the Great Lakes, but the GFS is not showing much change to the pattern for the Southeast as the upper ridge becomes elongated west to east and holds in place. This suggests that while we won’t see any extreme heat we should see highs more into the lower 90s and less in the upper 80s.

Much of the heavier precipitation over the next five days will be concentrated in an east to west band running through the Ohio River Valley. This would be the favored track for any large clusters of thunderstorms that occur as they trek eastward. SPC has no slight risk area today, and for Day 2 we see a slight risk in the upper Midwest centered on Southwest South Dakota.

NHC has stopped issuing advisories again on the remnants of Dorian which briefly became a depression yesterday.

Looking for the trends for week 2, or voodoo country, we see the pattern remains as it has for the last month or so with a trough in the east and ridge in the west. And this pattern continues to undulate between a strong trough and a weaker trough, so again, no excessive heat showing up.

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Thanks for tuning into the Weather Xtreme Video. James Spann returns with the next edition bright and early Monday morning. You can catch my forecast this evening at 5 and 10 pm on ABC 3340 as I will be filling in for Ashley Brand. Enjoy the day and Godspeed.

-Brian-