Friday Night: Mostly cloudy with scattered showers. Low: 42
Saturday: Mostly Sunny. High: 60
Saturday Night: Mostly Clear. Low: 41
Sunday: Partly Cloudy. High: 55
Sunday Night: Mostly Cloudy. Low: 37
Halloween weekend will begin in a soggy fashion as light showers continue Friday night, which should cease by Saturday morning. The remainder of the weekend will remain dry as a high pressure system moves in from the west; this should be good news for any trick-or-treaters wanting to avoid being soaked. Temperatures will remain crisp with highs reaching the lower-60s on Saturday and lows in the 40s for the majority of the weekend. Winds from the northwest will usher in decreasing overnight temperatures dipping into the upper-30s on Halloween night, so it would be advisable to wear heavier clothing if participating in fall festivities on Sunday.
Forecasters: Ethridge, Millsap
Date Issued: 10/29/21 10:00AM CST
The GFS model was used in this forecast because the observed surface temperatures matched the GFS model values, although the NAM plumes had more consensus in this regard. There is a possibility of patchy fog for Friday evening; otherwise, the weekend appears to be relatively inactive.
The closed low that has been over the Midwest for the past few days will begin to move out of the area overnight Friday. This can be seen in the GFS 250mb map. After the low pushes out of the region, a ridge flows over the Middle Mississippi Valley throughout Saturday. The 250mb map shows meridional flow with northerly winds over Missouri changing to zonal flow on Sunday.
The 500mb vorticity map tells a similar story. There is quite a bit of circulation over Missouri throughout Friday as the closed low pushes out of the region. There are still some remnants of that circulation leaving the area on Saturday but things become fairly calm as the ridge pushes into the area.
The circulation over the region corresponds to the large amount of moisture that can be seen on the 700mb map. This will move out Saturday and be replaced by dry air until overnight Sunday when another smaller region of moisture moves into the forecast region. This could be attributed to increasing cloud cover at the beginning of next week.
850mb map shows the results of northerly winds on Friday and Saturday as cool air creeps down from the north. As a longwave trough to the north flattens the aforementioned ridge, CAA will not only result in lower temperatures, but should also insinuate a stable atmosphere. If this holds out, any active weather during this time is unlikely. The CAA was supported using the 12Z model sounding for KCOU, which displayed a backing wind profile.