Forecast Discussion
000 FXUS64 KMEG 171113 AFDMEG Area Forecast Discussion National Weather Service Memphis TN 613 AM CDT Mon Jun 17 2019 .UPDATE... Updated to include 12z aviation discussion. && .PREV DISCUSSION... /issued 353 AM CDT Mon Jun 17 2019/ DISCUSSION... The upper-level cyclone over the Southern Plains will continue to track to the east today, crossing the Mid-South this evening. A cluster of thunderstorms developed in the warm advection regime downstream of this trough during the evening hours with additional development expected to our west early this morning. Scattered convection will develop this morning across the Mid-South, continuing through the afternoon and evening hours. Instability doesn`t look quite as impressive as Sunday, but will still be sufficient to support strong updrafts. Coupled with 0-6km bulk wind difference around 25 kts and there is a potential for a few organized multicells this afternoon. Like yesterday, the primary concern will be damaging wind given the mid-level dry air, steep low-level lapse rates, and precipitable water near 1.75". Storm coverage and intensity are expected to diminish bu mid evening, but we`ll maintain a potential for a few showers and thunderstorms through the overnight hours. Additional convection is expected on Tuesday, with the greatest coverage east of the MS River. We do anticipate a bit of a lull in precipitation chances Tuesday night into early Wednesday, but rain chances will increase quickly Wednesday afternoon into the overnight period as the next trough approaches from the west. Instability will increase Wednesday afternoon ahead of the trough and deep-layer shear will be sufficient to support organized convection. Storm coverage is expected to be scattered, but some strong to severe storms will be possible. In addition, rainfall amounts of 1-2" will be possible. This midweek trough is expected to be a more progressive, open wave, limiting the highest rain chances to Wednesday night and early Thursday. Rain chances will decrease from west to east on Thursday afternoon as the trough moves east and shortwave ridging builds over the region. The subtropical ridge begins to build over the Southeast on Friday, nosing poleward into the Great Lakes this weekend. During this time, a deep trough will dig over the western CONUS, eventually lifting northeast across the Northern Plains this weekend. While this ridge will normally spell the end of organized precipitation, the Mid-South will be on the northwest periphery of this ridge and any shortwave troughs moving through the flow aloft may still have an effect. Moisture/instability will be in place through the weekend, to go along with seasonally warm temperatures. This may induce diurnal convection, although subsidence aloft should begin to develop a cap. That said, 20-30% PoPs are warranted through the weekend given the uncertainty and climatology. Temperatures will generally be in the low/mid 80s through Thursday, but will return to near 90F by the weekend. Heat indices are forecast to approach 100F Friday/Saturday. Expect seasonal overnight lows in the upper 60s to mid 70s. MJ && .AVIATION... 12z TAFs VFR conditions will continue through the afternoon hours. A shortwave trof aloft will create showers and thunderstorms, with the best chances being this afternoon and evening. Winds will remain southerly and under 10 knots this afternoon, becoming lighter after sunset. TSRA should become SHRA by late in the period as upper trof moves over the region. This could also create some low clouds, but not enough confidence to include at this time. ZDM && .MEG WATCHES/WARNINGS/ADVISORIES... AR...None. MO...None. MS...None. TN...None. && $$