Thursday, October 22, 2020

 

 

 

Current Conditions at Sanborn Field





Thursday Night -
Becoming cloudy. Showers and thunderstorms likely after midnight. Low: 54-58

Friday -
Cloudy. Showers tapering off in the afternoon. Temperatures falling during the day. High: 50-54

Friday Night -
Becoming mostly clear. Low: 32-36

Saturday -
Mostly clear. High: 48-52

Sunday -
Cloudy. Rain likely after noon. High: 50-54
 
 
                          
 
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Discussion: 
After an unusually hot October Thursday, a cold front will pass through during the night dropping the temperatures and bringing storms that will last into Friday. After the front has passed, the skies will clear up Friday afternoon, and we will see considerably cooler temperatures than the day prior. Friday night skies will stay clear, with temperatures reaching near freezing. Saturday's forecast sees clear skies and seasonal temperatures. Sunday will see more clouds in the morning and precipitation towards the afternoon. Temperatures throughout the weekend hang out around the low 50's.
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Forecaster: Nixon, Cochran, Travis
Issued:  5 PM CDT 22 October 2020
 
Technical Discussion (The nerdy stuff we are discussing in class)

The main focus of this period is the big drop we will see in temperatures associated with a cold front moving in Thursday night. Due to an internet outage across the Mizzou campus on Thursday, went with a blend of the 00z GFS and 00z NAM. Used GEFS and SREF ensembles for temperature and QPF. 

Friday night, GFS and NAM plots of 500-hPa heights and vorticity an upper-level shortwave propagates down from the Upper Midwest. Southwesterly flow in the lower levels has already begun advecting plenty of moisture into the area ahead of the approaching system. Both models agree that the timing of cold fropa will occur close to 09z Friday morning. With it will come showers and thunderstorms as both models' soundings have moderate elevated instability setting up overnight. The NAM is more aggressive with instability showing close to 1500 J/kg of CAPE near the time of fropa. The GFS shows less with only ~600 J/kg. Regardless, both models depict more than enough instability for late October to support elevated convection. Due to the elevated nature of said convection, likely will stay below severe limits, but if the NAM has its way, locally strong storms could be possible. Consensus between the models breaks down in terms of timing of precip arrival. The GFS is quicker to achieve full saturation of the column closer to 03z while the NAM holds precip off until fropa occurs between 06z and 09z.

Showers linger into Friday afternoon with both model soundings' indicating precip will subside around or after 18z. By Friday evening, model soundings show a drying of the column as skies clear close to sunset. Friday night into Saturday will be chilly as it will be the first clear night post cold fropa. Ensemble members hint that temps could potentially fall into the lower 30s, but GFS and NAM plots of 850-hPa temperature show the 0C isotherm staying well to the north of central Missouri. 

Saturday sees much more seasonable weather for late October. Surface high pressure builds in behind Friday morning's cold front. Skies will remain clear save for possible few high cirrus clouds. Low-level, post frontal flow will stay out of the north and will keep our temperatures cooler in the upper 40s/lower 50s. Clouds move back in Saturday night ahead of a weak surface low-pressure system moving NE from the Central Plains. Low-level flow shifts out of the south allowing our temperatures Sunday to potentially get slightly warmer than Saturday. Moisture moves in as well as GFS soundings depict a saturating of the lowest 400 hectopascals. Expect showers to develop by Sunday after 18z and continuing into Sunday night.

Friday's shifts should look closely at how updated model guidance has changed from the outdated guidance we used due to the internet outage.

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