Forecast Discussion
486 FXUS64 KMEG 190540 AFDMEG Area Forecast Discussion National Weather Service Memphis TN 1140 PM CST Mon Nov 18 2019 .UPDATE... Updated to include 06Z Aviation Discussion. && .PREV DISCUSSION... /issued 657 PM CST Mon Nov 18 2019/ UPDATE... A broad trough sits over the eastern CONUS this evening with northwesterly flow aloft over the Plains providing an active storm track across the Mid-South. A shortwave trough is moving across the region this evening and will provide large scale ascent through the overnight hours. This lift will be enhanced by the indirect thermal circulation associated with the left exit region of an approaching 120 kt jet streak on the backside of the trough. An abundance of mid-level cloud cover is already in place across the CWA, but the sub-cloud layer remains relatively dry with surface dewpoints in the mid 30s to near 40F. We anticipate a few showers tonight, but it may still take a few hours to adequately saturate the air mass. Coverage will remain limited and QPF light, so no change was made in to the first period, slight chance PoPs. Other changes were minor but included increasing wind speeds slightly on Tuesday and cloud cover tonight. Any showers that develop tonight are expected to move east of the CWA before sunrise. MJ PREV DISCUSSION... /issued 331 PM CST Mon Nov 18 2019/ DISCUSSION... Currently...The next upper level disturbance is sliding toward the area in the NW flow aloft. Mid and high clouds are on the advance across the region. Temps are in the mid 50s across the Mid-South this afternoon or about 5 degrees below normal. Winds are light NW east of the MS River and gradually backing toward the SW as the next upper disturbance approaches. Tonight through Wednesday...Upper level disturbance will slide through the area overnight. SREF ensemble members are spitting out some light showers as the disturbance moves through. Some places may pick up a hundredth of an inch...most will not. Clouds will help keep temps a little warmer with lows in the lower 40s. Tuesday and Wednesday will be really nice days with plenty of sun and warmer temps with highs in the 60s. Wednesday night through Saturday...A wet period is in store for the Mid-South. A cold front will push toward the area by Thursday then stall over northern sections Thursday night into early Friday before pushing through the region Friday night as an upper low over the SW US ejects eastward. Right now it looks like 1.5 to 2 inches of rainfall is possible with this event. Severe weather potential is very low. Some thunder is possible late Thursday night into Friday as some elevated instability moves over the area. There is some discrepancy on how quickly this system exits the region. 12z runs are a little faster and as a result Saturday...and perhaps even Friday evening...are looking drier so have lowered pops some from the previous forecast. Cooler air will push in for the weekend with highs in the 50s. Sunday and Monday...Dry and cool with highs in the 50s. SJM && .AVIATION... /06Z TAFs/ VFR conditions expected to prevail through the period. SW winds overnight will veer NW with passage of a shortwave trough. LLWS remains a possibility at MEM over the next couple of hours with W winds around 2000 ft up to 35 kts. NW winds between 8-11 kts will become light/calm by Tuesday evening. CJC && .MEG WATCHES/WARNINGS/ADVISORIES... AR...None. MO...None. MS...None. TN...None. && $$