Scientific Forecaster Discussion
000 FXUS64 KMEG 221138 AFDMEG Area Forecast Discussion National Weather Service Memphis TN 538 AM CST Fri Nov 22 2019 .UPDATE... Updated to include 12Z Aviation Discussion. && .PREV DISCUSSION... /issued 422 AM CST Fri Nov 22 2019/ DISCUSSION... The latest surface analysis places a cold front from Cleveland, OH back through Dyersburg, TN and back through Little Rock, AR. A surface low was analyzed along the front near the ArkLaTex at this hour. Temperatures north of the front are in the lower 50s with low to mid 60s south of the front. The latest KNQA radar scan shows moderate showers along and north of the front, with an area of thunderstorms moving along I-40 in eastern Arkansas. Widespread showers and thunderstorms are expected through late morning across much of the Mid-South as the cold front slowly sags southward. The front is expected to stall over north Mississippi by this afternoon, with a lull in shower activity expected across much of the area. The aforementioned surface low, currently over ArkLaTex, will lift through the area this afternoon and into this evening. This will bring another round of showers and thunderstorms to the area through the overnight hours. The main upper level low over the Four Corners is expected to eject quickly across the Lower Mississippi Valley overnight and help push the front south of the Mid-South by early Saturday morning. A few post-frontal showers will be possible through late Saturday morning, mainly along the Tennessee River. Behind this system, the westerlies will remain progressive. Surface high pressure will build in briefly for Sunday and Monday, before a quick moving system arrives Tuesday night. Temperatures will moderate some during this period, with upper 50s to lower 60s expected on Monday and Tuesday. A stout shortwave will cross the Rockies early Tuesday and eject across the Central Plains during the morning hours. At the surface, a maturing low pressure system is expected to form near Oklahoma and lift northeast towards Saint Louis during the afternoon hours. This will allow a modified warm sector to move into north Mississippi, and maybe as far north as west Tennessee, Tuesday night. A quick-moving cold front is then expected to swing through Tuesday night and into early Wednesday morning. Luckily, the best dynamics will actually reside to our north, negating the potential for any severe weather. About half an inch is expected with the quick-moving system. Behind the front, dry conditions will briefly return as the subtropical ridge builds in on Wednesday. Thanksgiving is still a bit of a toss-up at the moment, as models are struggling with resolving shortwaves rotating around the ridge. Either way, the pattern looks to remain wet and unsettled in the extended period. AC3 && .AVIATION... 12Z TAFs Lower ceilings due to low stratus will remain a challenge in this TAF set as the atmosphere will remain saturated along a weakening and nearly stationary boundary across the Lower Mississippi Valley. This is expected to result in mainly IFR conditions today and potentially deteriorating to LIFR conditions by tonight. The first round of rain with perhaps an embedded elevated thunderstorm will depart this morning. There may be a break in activity later this morning into early afternoon before a second round of rain with perhaps an elevated thunderstorm moves through the region later this afternoon into tonight. The best potential for VCTS will be at TUP and confidence is too low to include in other TAF sites at this time. NNE winds between 6-11 kts anticipated at sites except at TUP where S winds are expected to become ESE winds between 5-7 kts this afternoon. CJC && .MEG WATCHES/WARNINGS/ADVISORIES... AR...None. MO...None.