Thursday, March 5, 2020


Thursday Night - Mostly clear. Low: 28-32
Friday - Sunny. High: 50-54  
Friday Night - Mostly clear. Low: 30-34   
Saturday - Mostly sunny. High: 58-62
Sunday - Partly cloudy. High: 64-68

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A cold front passed through the area this afternoon, which has brought in northerly winds. These north winds will deliver colder air for the overnight hours. Tonight, temperatures should drop slightly below freezing. A high pressure system will build in behind the cold front, bringing mostly sunny skies and tranquil weather Friday through Saturday. Friday will be slightly cooler, with a high in the low 50s. Warmer air will arrive Saturday into Sunday as the high pressure system moves east and winds become southerly. 
Forecasters: Dowell, Vanderpool,  Ritter
Issued:  5:00pm: March 5, 2020

Technical Discussion (The nerdy stuff we are discussing in class)

This shift has elected to go with the 12z 0.25-degree GFS due to A) recommendations from the WPC (which gives weight to the 12z GFS/UKMET/ECMWF blend), and B) that model's good handle on the evolving upper air pattern over the central United States, particularly with respect to a cyclone in the upper Midwest. For temperature concerns, 15z SREF and 12z HREF were also consulted. Additionally, the 12z GEFS was used to assist in temperature and sky condition forecasting.

Working from the top-down, 250-mb flow over the CONUS revealed a longwave protruding from southern Ontario all the way down to northern Texas. 500-mb heights and absolute vorticity analysis also displayed this feature, with a well-defined vorticity maximum plunging southward over the central and upper Midwest. The 700-mb and 850-mb layers, however, indicated little in the way of moisture or vertical motion to support inclement weather for Missouri. In the short term, this translates into relatively clear skies and quiet weather in mid-Missouri. WPC surface analysis (18z this afternoon) shows a prominent surface low centered over northern Wisconsin. This surface low will continue to track eastward and, nestled beneath a neutrally-titled trough at 250-mb and 500-mb, should maintain its strength (if not undergo mild cyclolysis) over the next 24 hours. As for surface features in Missouri, a cold FROPA in Columbia occurred shortly after 15z, courtesy of the surface low to our north.

For tonight, cold air advection (CAA) will continue behind the surface cold front. The air is not very cold, however, being primarily from a maritime polar origin. Therefore, even with strong CAA and clear skies, temperatures should not dip much below 30.

On Friday, CAA will continue as a surface high builds into the Midwest. This surface high will ensure that any moisture is scoured from the column, leading to cooler conditions and sunny skies. Temperatures should be in near 50, with ensemble model solutions favoring maximum temperatures on the order of 49 - 52 degrees. Fire weather should not be as big of a concern for Friday, owing to much lighter winds. Still, outdoor burning is not advisable, as area vegetation remains extremely dry.

For the weekend, a warm-up will commence as the surface high moves off to the east. This will allow return flow on the backside to advect significant warm air into the region. Current thinking is that Saturday should see highs in the upper 50s to lower 60s. This shift has decided upon a temperature range of 58 - 62 degrees, primarily based upon ensemble model output and GFS MOS guidance indicating highs around 60. However, if warm air advection is stronger than currently anticipated, future shifts may need to look at increasing forecast highs.

The local area will experience similar conditions Sunday, though the warm air mass will be even more deeply entrenched over Missouri. With continuing WAA and partly to mostly sunny skies, temperatures should have no problem making the mid to upper-60s. Our next concern for precip begins Sunday afternoon and evening, with the deterministic GFS solution indicating stout (40 - 50 kt) southwesterly flow at 850-mb and increasing PWATs on the order of 1 - 1.25 inches. With a disturbance approaching the Midwest late in the forecast period, this should yield rain in mid-Missouri beginning Sunday night.

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