736 FXUS64 KMEG 111731 AFDMEG Area Forecast Discussion National Weather Service Memphis TN 1231 PM CDT Fri Sep 11 2020 .UPDATE... Aviation Update Below && PREV DISCUSSION... /issued 353 AM CDT Fri Sep 11 2020/ DISCUSSION... A slow-moving cut-off low continues to trek eastward across the Central Rockies early this morning but a 593 dam ridge centered near the confluence of the MS and OH Rivers will keep this wave west of the Great Lakes through tomorrow. A persistent, subtropical moisture tap is streaming poleward across the Southern Plains, arcing northeast around the ridge into the northern OH Valley. Another slug of deeper, more tropical moisture is moving west along the southern periphery of the ridge near the northeast Gulf Coast. The Mid-South is currently sandwiched between these two areas of anomalous moisture with current precipitable water in the range of 1.25 inches. At the surface, a cold front extends southward from a weak surface cyclone over the Ozarks with a quasistationary front running roughly parallel to the OH River into the Mid-Atlantic States. We've experienced hot and dry weather across the Mid-South for the better part of a week, but the pattern is finally changing. The subtropical ridge will shift eastward off the Carolina coast and the bowling ball low over the Rockies will be replaced by a broad upper-level ridge. As the Southeast ridge moves east this weekend, the moisture currently to our southeast will wrap around its western flank, pushing precipitable water north of 2.1 inches by midday Saturday. We'll begin to see this uptick in moisture today and it will be reflected in isolated to scattered convection this afternoon, mainly across north MS, extending into the TN Valley portion of west TN. Temperatures will again be above normal, with highs near 90F, and increasing humidity will result in heat indices in the mid/upper 90s. The increase in moisture tomorrow, combined with falling mid-level heights will result in scattered convection by midday. Rain chances will be in the 40-50% across much of the CWA given the uncapped thermal profile with ~2000 J/kg of MLCAPE. Deep-layer shear will remain weak at less than 20 kts, so convective elements will generally remain unorganized. Heavy downpours and perhaps some gusty winds due to precip loading will be the primary concerns. A cold front will move across the Mid-South on Sunday, bringing drier air to areas north of I-40. Those locations in north MS will probably not see as much influence from this air mass, hanging on to dewpoints in the 70s. We do expect this front to end our run of above normal temperatures, if only bringing them down to climatology Sunday and Monday. Rain chances will persist across much of the area Sunday through Tuesday, favoring areas south of I-40 with in the deeper moisture. A potential tropical system will be moving into the northern Gulf by early/mid next week. This is expected to reinforce the high precipitable water air mass by midweek, enhancing rain chances once again across the Mid-South. Confidence on how this system will evolve beyond early next week is low, but it could provide further rain chances through the end of next week. The good news is that temperatures do look to be trending to a few degrees below normal by late next week. MJ && .AVIATION... 18Z TAF VFR conditions at all TAF sites. Fog looks to develop in the morning hours at MKL and JBR so MVFR conditions can be expected. Held off on the mention of fog at TUP but will monitor. Winds generally easterly 2-7kts and by end of TAF cycle look to shift more SW. Some models have some showers developing across the area tomorrow however I did not include any mention in the TAF this cycle as confidence was too low. Will monitor and make adjustments at next cycle. SMW && .MEG WATCHES/WARNINGS/ADVISORIES... AR...None. MO...None. MS...None. TN...None. && $$