308 FXUS64 KMEG 171126 AFDMEG Area Forecast Discussion National Weather Service Memphis TN 626 AM CDT Sat Mar 17 2018 .UPDATE... Updated for the 12Z Aviation Discussion && .PREV DISCUSSION... /issued 352 AM CDT Sat Mar 17 2018/ DISCUSSION... An occluding cyclone over IA/MO will continue to move east this morning. Dry air is wrapping around the southern periphery of the circulation between the cyclone and subtropical jet. A cluster of storms developed this evening just north of the CWA along the quasi-stationary front and have just about moved across the Tennessee River. Synoptic scale forcing for ascent interacting with the low-level jet will continue to support scattered showers and thunderstorms through sunrise, mainly south of I-40, but this convection is expected to be east of the area by sunrise. A stray shower or storm cannot be ruled out today over north MS as a surface trough moves across the area, but with large scale ascent shifting east, there really isn't much support. Temperatures will be rather warm today with highs in the 70s across most of the Mid- South. Winds will be shifting from the west today and eventually from the north this evening as a cold front moves across the area. This boundary is expected to hang up near the southern boundary of the forecast area tonight and may trigger a few overnight showers or thunderstorms, mainly south of a Clarksdale-Houston line. This front is forecast to gradually lift back to the north on Sunday as a warm front. Showers, and a few thunderstorms, are expected to increase from southwest to northeast during the afternoon, with rain chances increasing further Sunday night as a shortwave trough approaches. Instability/shear will be increase Sunday night downstream of this wave and will be supportive of widespread showers and scattered thunderstorms during the period. A few storms could be severe Sunday night and early Monday, with the greatest potential for severe weather south of I-40. Rain chances should begin to taper from west to east on Monday night as another cold front moves through the Mid-South. However, low rain chances will hang around through Tuesday as a trailing shortwave trough moves across the region. Cool temperatures aloft may support a few showers, although no QPF of consequence is anticipated. Dry weather will prevail during the midweek period as shortwave ridging builds over the central CONUS. Below normal temperatures are expected midweek in the wake of the Monday night cold front. Highs will be in 50s Tuesday and Wednesday, gradually moderating as we move later into the week. Overnight lows will be in the 30s across most of the area Tuesday night and Wednesday night. Some areas will likely experience another freeze. Medium range models diverge significantly by the end of next week. Both the GFS and ECMWF indicate the central CONUS ridge shifting east but the GFS weakens this ridge much more quickly and brings a fast-moving shortwave trough across the area by Friday night. The ECMWF maintains the ridge and keeps the mean trough in place over the Rockies with the lead shortwave trough lifting well north of the area. There is poor agreement in the synoptic pattern by Saturday with the ECMWF developing a Rex Block over the Plains. Low PoPs were included Thursday night through Friday night, but look to increase over the weekend. Will wait for more agreement amongst the model solutions before raising PoPs too quickly. Johnson && .AVIATION... 12Z TAF cycle A few thunderstorms are currently over Monroe County in Mississippi and should be out of the region soon. Low clouds cover the forecast area this morning and will gradually lift leaving VFR conditions starting this afternoon and continuing through the remainder of the forecast period. Winds will be mainly from the west at around 10 knots by later this morning then shift to the north at around 5 knots tonight. ARS && .MEG WATCHES/WARNINGS/ADVISORIES... AR...None. MO...None. MS...None. TN...None. && $$