Day 4-8 Outlook

Day 4-8 Convective Outlook  
NWS Storm Prediction Center Norman OK
0319 AM CDT Thu Oct 22 2020

Valid 251200Z - 301200Z

...DISCUSSION...
...Sunday/Day 4 to Tuesday/Day 6...
On Sunday, the medium-range models have west-southwesterly mid-level
flow across most of the United States. A cold and dry air mass is
forecast to be in place across much of the northern and central U.S.

The moist sector should be confined to the Gulf Coast States where
isolated thunderstorms could develop Sunday afternoon. Weak
instability should limit a severe threat.

On Monday, the models are forecasting a subtle shortwave trough to
move northeastward from the mid Mississippi Valley into the Ohio and
Tennessee Valleys. Thunderstorm development will be possible ahead
of this feature Monday afternoon. However, instability is forecast
to be weak on Monday suggesting a limited severe weather risk.

On Tuesday, an upper-level low is forecast to move across the Desert
Southwest. Southwest mid-level flow should be located across the
southern and eastern states. In spite of a moist air mass across the
Southeast, instability is forecast to remain weak during the day.
Although some thunderstorm development could occur from the Arklatex
into the central Gulf Coast States, any severe threat is expected to
remain marginal.

...Wednesday/Day 7 and Thursday/Day 8...
The medium-range models move an upper-level low across the southern
High Plains on Wednesday and into the Red River Valley and Arklatex
from Thursday into Thursday night. Thunderstorm development will be
possible each day to the east of the upper-level low near the
northwestern edge of the moist sector. Although instability is
forecast to be weak ahead of the upper-level low, a marginal severe
threat can not be ruled out each day. The risk for hail and strong
gusty winds would be maximized in the Arklatex on Wednesday and in
the Southeast on Thursday. However, predictability this far out in
the forecast period remains quite low.

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