Tuesday, August 5, 2014

A shift in the weather pattern means higher rain chances for the Mid-South

We were quite spoiled for most of July as Memphis experienced its sixth coolest July on record, but the start of August is bringing more typical summer heat that looks to stick around for a while. As we head into tomorrow, humidity will begin to rise. With temps reaching the mid 90s, heat index values will be near 100 in the afternoon. If working outdoors, practice heat safety by taking frequent breaks and drinking plenty of water. It would also be a good idea to check on the elderly and those with breathing disorders as air quality will suffer as well. Be sure to also keep plenty of water accessible for outdoor pets.

As we near the end of the week, increased cloud cover will keep temperatures closer to 90, however humidity values will go up with dew points reaching 70. It will feel quite muggy! Perhaps the most important point of this blog is the increased rain and thunderstorm chances due to a slight pattern shift in the upper atmosphere. This shift, in which the wind aloft will blow from the northwest (called "northwest flow"), will lessen the cap on the atmosphere, allowing storms to form more easily.

Surface dew points and near surface winds early Thursday morning.
CAPE, a measure of unstable air, early Thursday morning. Values above 2000 will easily support t'storms.
The Weather Prediction Center's forecast of surface fronts late Thursday evening. Note the front across northern portions of the Mid-South.
With a stalled frontal boundary near the region and northwest flow in place, storm systems sparked by upper level disturbances could bring multiple rounds of rain and storms over the region. These systems (called "mesoscale convective systems" or MCS's) are difficult to predict days in advance, but often times in the summer they will set-up along weak boundaries and move great distances. We'll be close enough to a front to possibly be in line for these systems, with air that is plenty unstable to support them.

Due to the uncertain nature of these MCS's, predicting any severe weather associated with them is difficult, but strong wind and possibly small hail is not uncommon as they pass through. For now, no severe weather is predicted for the Mid-South, due mainly to uncertainty in exact timing and track of any storm complexes. However, much of the region could get welcome rain over the next week, as the abundance of June precipitation has evaporated and soil and vegetation are beginning to dry out.

Stay tuned to our social media feeds, website, and mobile apps for the latest on the effects of the upcoming weather pattern shift over the region. Links can be found below.

William Churchill, MWN Social Media Intern
Erik Proseus, MWN Meteorologist

Follow MWN on Facebook, Twitter, and Google+
Visit MemphisWeather.net on the web or m.memphisweather.net on your mobile phone.
Download our iPhone or Android apps, featuring StormWatch+ severe weather alerts!

No comments: