Saturday, February 9, 2013

Thunderstorms Sunday, then precip in cold air Tuesday

A large trough is developing over the central U.S. as an upper level pattern shift takes place.  Low pressure will move out of the Front Range tonight into the Northern Plains by Sunday evening, dragging a cold front into the Mid-South during the afternoon.  Though dewpoints are only in the 30s this afternoon in a coolish airmass, continued southerly flow overnight and increasing and gusty south wind tomorrow will usher in a warmer and more moisture-laden airmass.  This will set the stage for thunderstorms during the day Sunday.

With the surface low passing well to the northwest of the area, a widespread severe weather outbreak is not expected, however there could be enough instability to bring a few strong storms during the afternoon (see video below).  The most likely area for severe storms, as depicted within the green outline is over the Lower Mississippi Valley.

Mid-afternoon satellite and radar composite shows clouds streaming into the area ahead of the next trough. The area outlined in green has a Slight Risk of severe weather on Sunday as a cold front moves through.
Storms will be ongoing in the morning over eastern TX and will move across the region with an enhanced risk of severe storms during the day.  The northern end of a likely line of storms could be close to the metro, though the meat of the system will affect southern AR and MS where a high wind and tornado threat exists especially in northern LA and central MS during the late morning and afternoon hours.

Probability of severe weather on Sunday.  The metro has about a 15% chance of  severe storms, but a much higher  chance of general thunderstorms.  The black hatched area has the best chance of significant severe weather.
The main threats with any storms on Sunday here in the metro will be an isolated high wind and large hail threat between 11am-2pm (info updated Sun at 7am), though thunder is possible as early as the morning hours.  In addition, rain and storms could drop an inch or more of rain in the Memphis area before precipitation moves out Sunday evening.

Animation of atmospheric instability (represented as Convective Available Potential Energy, or CAPE) from Saturday morning through Sunday night. A modest amount of unstable air will be available tomorrow afternoon as storms move through the area, though the most unstable air remains south of the metro across the Lower MS Valley.

One additional brief note: the cold front that moves through tomorrow will stall out to our south early in the week. An upper-level wave will move through late Tuesday, bringing a chance of post-frontal precipitation.  Though upper-level temperatures may support a mix of rain and snow, temps near the surface may be a touch too warm for snow at the ground. The best chance for any light snow will north of the metro on Tuesday night. We'll let you know if anything changes! will nowcast throughout the day Sunday via our social channels, bringing you the latest information on any local threats.  Also be sure to download our mobile app for the latest radar, current conditions, and any severe weather alerts that may be issued via StormWatch+.  Links to all of our offerings are below.

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