MWN Blog: On the Fourth of July, keep an eye to the sky!

Wednesday, July 4, 2018

On the Fourth of July, keep an eye to the sky!

Happy Independence Day!

The Fourth of July will likely feature a few strokes of bright light and loud booms that are not man-made today. An upper level disturbance moving through the region from east to west (yes, sneaking up from behind, "Crazy Ivan"-style) today that will likely result in widely scattered storms forming this afternoon into the evening.

With a very hot and humid airmass in place (heat indices will reach 105° this afternoon), and some moderate wind aloft to boot, a few of these storms could become strong to possibly severe. The primary threats with any storm that forms will be dangerous lightning, strong wind, and localized downpours. With the impulse continuing through the region into the evening, it's quite possible that the threat continues later into the evening than it usually does in the summer, which means we'll all need to keep one eye on the sky for this evening's fireworks displays around town. (Note that despite the possibility of strong storms, not everyone will see rain today.)

The latest high-resolution models seem to point to a potential threat during the afternoon hours, then a lull early this evening, followed by another threat after 9-10pm. We won't get that fancy with timing - just be prepared the rest of the day and be ready to seek shelter if you hear thunder. We also recommend you take our MemphisWeather.net mobile app with you and have StormWatch+ activated in-app to warn you if severe weather threatens while you are out and about.

Besides the severe weather threat that some of us might face, we'll all be affected by the heat. Temperatures in the mid 90s and heat indices of 105°+ means you'll need the sunscreen, water, and some occasional shade. A Heat Advisory is in effect for the entire metro, which is triggered as heat indices are expected to be 105+.

Thursday brings another summery day with similar temperature and humidity levels as today. The storm threat appears to be slightly lower with no clear instigator in the atmosphere to trigger development, but a 20% chance of rain is in the forecast because... summer.

Friday into the weekend

By Friday, the pattern starts to change a bit. A cold front (don't get too excited just yet) will seep into the northern reaches of the Mid-South, resulting in enhanced rain and storm chances, particularly in the afternoon. Heat indices will still climb above 100 as humidity tends to "pool" ahead of these fronts, making it even stickier despite ever-so-slightly cooler temperatures. The scattered storm chances continue into Friday night as the front drops closer to I-40.

By Saturday morning, there's a decent chance that the cold front slips just to our south. If it does, humidity levels will drop a bit and storm chances should push to the south as well. Saturday has the potential to be the best looking day of the forecast with highs only in the upper 80s, a north breeze, and dewpoints dropping into the tolerable range. Still can't rule out a thunderstorm, mainly over north MS. We'll be keeping a close eye on the front's progress, as sometimes the models over-promise and under-deliver when it comes to summertime fronts this far south. Here's hoping...

The front, wherever it ends up, will weaken and wash out Sunday into Monday. That means the return of summertime scattered storms and less acceptable humidity levels. Fortunately, at least for now, it appears that high temperatures early next week will be closer to seasonal levels (90-93° for highs), or a bit cooler than we have had most days over the past week. For our complete forecast, check the app or click here.

Erik Proseus
MWN Meteorologist

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