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A stagnant pattern remains in place keeping warm and dry conditions through the end of the week.
St. Louis (LSX) — the National Weather Service forecast in plain English · Plaincast
Plaincast
What the forecast actually says — NWS Area Forecast Discussions, decoded into plain English.
Revised in 5 passages since the 2:29 AM discussion. See every revision.
Short Term
A slow moving upper-level ridge remains over the central CONUS keeping dry and seasonably warm conditions in the Mid-Mississippi Valley through the weekend and into Monday. As a result, very little change in the weather day-to-day is expected. The only change is the presence of some upper-level clouds. The stubborn ridge continues to drive high temperatures into the mid to upper 70s, with some areas possibly exceeding 80 on Sunday depending on the thickness of the clouds. Dry air will allow for radiative cooling overnight keeping low temperatures in the upper 40s to low 50s, with the 40s predominately being in the river valleys and southeastern MO and southwestern IL. This is due to the presence of fewer clouds in that region, which will allow for more efficient radiative cooling overnight.
Long Term
Over the western CONUS, a deep upper-level trough is present and is expected to propagate to the northeast toward the north-central CONUS and into the Midwest during the middle of the week. Guidance is in good consensus that as the trough tracks northeast it will reduce the amplitude of the ridge over the region. The current forecasted track of the trough will cause the associated cold front to stay well to the north of the region, resulting in dry and seasonably warm conditions in the region continuing through the entire week. High temperatures will remain in the 70s each day.
Earlier guidance had indicated a potential pattern change at the end of the week, but latest model trends indicate stronger confidence that the ridge remains in place through the end of the week. Yesterday, the the blend-of-models forecast and LREF guidances continued to hint at the possibility of a cold front coming at the end of the week with IQRs of 10-15 degrees for Thursday and Friday, but latest runs have IQRs of 5-10 degrees by raising the 25th percentile from being in the 60s to being in the low 70s. At the same time, this model trend has also decreased the chance of rain at the end of the week down to 10-30 percent on Friday while increasing the chances the following weekend ahead of the potential cold front.
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Data from the National Weather Service. Translated by Claude. About · For developers & agents · Subscribe: RSS feed for this office · Source on GitHub