Saturday, July 26, 2014

A hot weekend, but another round of below normal temps is moving in!

The well below normal temperatures we've experienced for much of the month has resulted in this weekend's "normal" July weather feeling rather uncomfortable. Seems to be pretty easy to acclimate to cooler weather and take for granted the lack of 90 degree days. Then when a couple of days, such as this weekend, send the mercury into the mid 90s with heat indices very near Heat Advisory criteria, we realize just how fortunate we have been!

High pressure ridging into the area at the surface and aloft has resulted in a significant rise in the humidity levels and above normal high temperatures today, which will continue tomorrow. Be sure to take your Memphis summer heat safety precautions again tomorrow! However, the ridge retreats as yet another cold front pushes through, pushed to the Gulf coast by another building upper-level trough over the eastern U.S. This trough will bring below normal temperatures back into the Mid-South for the last week of summer vacation for many youngsters. Though not as cool as the last round, highs in the 80s, lows in the 60s, and dewpoints below average will once again bring a taste of early fall to the area.

The mid-level weather map (18,000') on Tuesday evening features a large trough over the eastern U.S. and huge ridge over the west. This has been the dominant pattern in July, which is very unusual for mid-summer and results in cooler than normal weather under the trough.

The cold front will move through Sunday night, but since most of the dynamics and cooler air aloft stay just to our north, a widespread severe weather outbreak will not occur. In fact, despite the low level moisture ahead of the front, the chances for rain are even fairly slim and confined to the evening hours on Sunday. Because the front will be pushing into a hot and humid airmass though, any storms that do form could bring strong wind gusts and brief heavy rain will also be a threat, in addition to lightning, Sunday evening. The best chances of severe weather will remain well to our north and east, especially in the upper Ohio River Valley where significant severe weather is possible. Here's our complete MWN Forecast for the upcoming week.

Severe weather will be likely in the Upper Ohio Valley, but is unlikely in the Memphis metro, outside of a stray thunderstorm with gusty wind and dangerous lightning.

Looking into early August, NOAA's 8-14 day outlook (covering August 3-9) indicates a high probability of below average temperatures continuing (see below). Note that the darker shades of blue do NOT mean colder, rather a higher probability of below normal temps. Here's to our good fortune from July continuing into August. (By the way, at this point, we also believe that the probability of reaching 100 this summer is very low. It's been 2 years this Wednesday since our last 100 degree reading.)

Temperature outlook for August 3-9 indicating a high probability of below normal temps in the dark blue shaded areas.

Erik Proseus
MWN Meteorologist

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