Friday, October 25, 2019

Friday Night - Partly Cloudy. Low: 41-45

  Saturday - Overcast. Showers. High: 49-53

Saturday Night - Overcast. Low: 38-42

Sunday - Partly Cloudy. High: 61-65

Monday - Overcast. High: 52-56

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This upcoming weekend we expect overcast skies. Showers are expected Saturday afternoon due to the passage of a low pressure system. Temperature will drop into Saturday night as this system passes through. We expect Sunday to warm up before temperature begin dropping again on Monday due to another incoming low pressure system.
Forecasters: Balkissoon, Taylor, Heaven, Travis
Issued:  5:00pm; October 25,  2019

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

Friday night we remain under the influence an upper level jet. This jet will begin pushing out of the area as a low pressure system approaches from the south-west.  We come under the influence of another jet streak associated with a long wave approaching from north-west into Missouri around Sunday 15Z to Monday 21Z.  

From the GFS 500-hPa height and absolute vorticity map, associated with the low pressure system on Saturday, we see regions of increasing circulation as expected with the counter-clockwise curvature in wind flow and the S-N movement of air which makes the effects from CO force increase (since Absolute Vorticity = Shear + Curvature + CO force).  

Looking at a map of GFS 700-hPa heights RH and omega, high percentages of RH starts increasing from 9Z on Saturday and reaches its maximum around 18Z.  We expect rainfall during this time because there is also upward vertical motion of 12 microbars per second.   Also, from the 1000-500 hPa thickness, as expected with the associated low pressure systems, there were steeper thickness gradients.  

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