Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0327 AM CST Wed Nov 18 2020 Valid 211200Z - 261200Z ...DISCUSSION... A more progressive and active weather pattern will emerge over the CONUS during the Day 4-8 time period. A series of mid/upper troughs will migrate from west to east across the country, bringing chances for thunderstorm activity to parts of the southern/central Plains eastward to the Mid-Atlantic. The first trough will shift eastward from the Plains to the Atlantic coast Day 4/Sat through Day 7/Tue. The second trough will dig across the western states beginning late Day 5/Sun and emerge over the Plains on Day 7/Tue. Strong surface high pressure over the eastern U.S. initially will preclude much in the way of strong Gulf return flow over the south-central and southeast states. Given limited moisture and a pattern more typical of anafrontal precipitation, severe thunderstorms are not expected, though some isolated thunderstorm activity could be embedded in periods of moderate to heavy rain from the central/southern Plains to the Midwest through Day 5/Sun and into the Northeast on Day 6/Mon. Another round of rain and thunderstorms is expected to develop over the central/southern Plains as the second upper trough ejects eastward across the Rockies around Day 7/Tue. Forecast guidance varies in the timing and intensity of this system, so confidence is low in the later parts of the forecast period, though some thunderstorm potential is expected to spread eastward across much of the eastern portions of the CONUS. Depending on low level moisture and degree of destabilization that could occur, some low-end strong to severe thunderstorm potential could unfold across the Southeast by the middle of next week, but uncertainty is too great to include probabilities at this time.
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