Monday, February 4, 2019

Tonight -Cloudy. Freezing drizzle possible. Low: 26-30

Tuesday - Clouds remain. Freezing rain possible in the morning transitioning to rain after noon. High: 38-42

Tuesday Night - Cloudy. Rain likely with thunder possible. Temperatures rising overnight. Low: 36-40

Wednesday - Clouds persist. Drizzle possible in the morning. High: 52-56

Thursday- Clouds continue to persist with rain showers. High: 44-48

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Columbia will pay for the beautiful weekend as persistent clouds and several chances for precipitation will likely occur. A cold front will pass through later today and the springlike temperatures will drop back down to near freezing. Monday night into Tuesday morning freezing drizzle is possible, but no accumulations or impacts are expected. Freezing drizzle will transition to rain by noon on Tuesday. Tuesday night will see steady showers with a few rumbles of thunder possible. On Wednesday, drizzle lingers in the morning and grey skies persist throughout the day. Going into Thursday, we will see drizzle turning into rain showers during the morning.
Forecasters: Danaher, Brown, and Hirsch
Issued: 4:30 p.m., February 4, 2019

Technical Discussion (The nerdy stuff we are discussing in class!) 
This past weekend's tranquil weather will come to an end quickly this morning, with an active weather pattern taking shape for this week. Per WPC analysis, a cold front extended from near Kansas City to just northwest of Kirksville at 12Z. IR imagery from GOES-13 confirms this, with a sharp temperature gradient appearing in the vicinity of the front. Associated with this front is a large area of cloud cover, also confirmed by satellite imagery, which has already begun to spread over our area. With the passage of the cold front today, temperatures will drop sharply into the upper-30s by sunset. As for precipitation, this forecast does not anticipate anything during the day today due to very little divergence at 250-hPa, no lift in the lower levels of the atmosphere, and little moisture throughout the column (with the exception of the lowest 100 hPa).

Heading into the rest of the period, 06Z GFS shows a substantial 250-hPa jet exceeding 130 kts ramping up over the SW CONUS. As the jet propagates toward and then over Missouri, divergence aloft will increase. A large vort max will move toward our area, but it will not make it to Missouri before the end of this period. The bottom line is that there will be upper level support for precip beginning Tuesday morning and continuing through the end of the period. Therefore, what determines whether or not there will be precip is the moisture profile and lift. For tonight and Tuesday, moisture profiles from GFS SKEW-T's are not that impressive, with a substantial dry layer from 250 to 900 hPa during this time. Lift is practically non-existent as well. Because of this, both the GFS and SREF have no QPF tonight and Tuesday. Therefore, we are expecting low level cloud cover tonight and Tuesday and a low likelihood for light precip. However, it should be noted that the GFS has a very shallow cold layer near the surface from 06Z-15Z Tuesday morning, and some SREF members produce FZRA as the p-type, so there may be some freezing drizzle or light freezing rain if any precip does indeed fall.

By  00Z Wednesday, 250-hPa divergence strengthens. Skew-T's also show a thoroughly moist column with plenty of lift. QPF from both the GFS and SREF increase at this time. Also, there will be some instability present (~100 J/kg CAPE), so there may be some thunder, especially between 00Z and 12Z Wednesday. Therefore, we went with rain and some thunder through about 18Z Wednesday.

Temperatures will be difficult to pin down from 00Z Tuesday on. With SW flow continuing, near average temperatures can be expected Tuesday. With a warm front pushing through overnight Tuesday, temperatures will rise throughout the night, and lead to a warm Wednesday.

Due to the differences between the GFS and NAM for Thursday, we chose to lean more towards the GFS. The GFS sounding continues to show a backing wind profile as temperatures continue to stay cold throughout the day. Lift becomes very noticeable during the 15z run of the GFS which gives the potential for rain showers in the morning. Overall, it is still very unclear what will happen Thursday onward due to a large discrepancy in model solutions.

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