Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0355 AM CDT Sun Oct 18 2020 Valid 211200Z - 261200Z ...DISCUSSION... ...Wednesday/Day 4 and Thursday/Day 5... On Wednesday, the medium-range models are in reasonable agreement, with an upper-level trough in the western U.S. and west-southwesterly mid-level flow in the central and eastern U.S. The models are forecasting an axis of low-level moisture to be located in the Arklatex and mid Mississippi Valley. Isolated thunderstorms may form along the northern edge of the moist sector from the central Plains into the mid Mississippi Valley Wednesday afternoon and evening but weak instability is expected to keep any severe threat marginal. On Thursday, the models move an upper-level trough into the Rockies as southwest mid-level flow becomes established in the north-central states. At the surface, a cold front is forecast to move southeastward into the central Plains and upper Mississippi Valley. Thunderstorms could develop Thursday afternoon and evening along the front. However, weak instability should again keep any severe threat marginal. ...Friday/Day 6 to Sunday/Day 8... The models continue in reasonable agreement from Friday to Saturday, moving the cold front southeastward across the eastern third of the nation. Thunderstorms will be possible along and ahead of the front from the Ozarks into the mid Mississippi Valley on Friday and in the Southeast on Saturday. Weak instability should again keep any severe threat marginal. On Sunday, an upper-level trough is forecast to move eastward across the southwestern states with southwest mid-level flow located in the southern Plains. Thunderstorms will be possible in the southern and central Plains Sunday into Sunday night but the models have varying degrees of instability ahead of the system. Due to significant model spread, predictability remains quite low for Sunday.
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