Friday, February 24, 2023

 

 Current Conditions at Sanborn Field

 
 
 
Friday Night: Overcast Clouds with a chance for mixed drizzle and freezing drizzle Low: 30



 
Saturday: Partly Cloudy. High: 52




 
Saturday Night: Overcast Clouds. Low: 42





Sunday
: Overcast Clouds. High: 61



 

  

Sunday Night
: Overcast Clouds with rainfall. Low: 52

 

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Discussion: 

A slight chance for freezing drizzle may freeze elevated surfaces on Friday night. Temperatures will warm up afterwards until a strong low pressure system arrives, bringing around 0.5"-1" of rain into the region Sunday night into Monday morning.

-Sausen

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Forecasters: Sausen, Thomas, McGuire

Date Issued: 2/24/2023 5:00 PM CST

Technical Discussion:
 
 

Drizzle, with the potential for some very light freezing precip, is expected tonight, and significant rainfall totals along with a chance for some rumbles of thunder will occur Sunday night into Monday morning.
For this forecast, we chose the GFS as it handled the placement of the surface low off the coast of California marginally better than the NAM.
A mid to upper level trough with a slight negative tilt is forecasted to make its’ way across the forecast area tonight. Current radar is already showing scattered precip over NW MO, slowly migrating southeast.Weak but present vertical velocity aligned with the plume of near surface moisture should be sufficient to produce scattered drizzle, though the precipitation type is in question. GFS soundings show a very significant dry layer close to the surface that takes its’ time to erode, though the 700-850mb level is quite moist by the start of the evening. The DGZ looks to remain quite dry, however surface temps should be hovering around freezing. Have gone with mix of drizzle and freezing drizzle for tonight, with precip chances ending before sunrise tomorrow.
Could see some light rain around 03z Sunday, as temps look to stay uniformly above freezing far up into the 700mb layer associated with a second weak shortwave trough, though it’s unlikely that we’ll see more than a trace, as the moisture content is mostly concentrated in the upper levels, with very weak forcing for ascent associated with the shortwave.
The main problem of the forecast period is the looming low pressure system, currently centered over California at the surface. A weak shortwave is progged to follow just out ahead of it, separating some of the Gulf moisture away from the larger low. 700mb WAA is present in conjunction with the shortwave, pushing surface temps up into the 60’s on Sunday. With a moist surface to 850mb layer, widespread low level clouds and light rainfall seem likely until the evening as mid level moisture surges in with the main system. Widespread cloudiness during the day will severely limit destabilization, though the GFS shows MUCAPE values of around 300-400 j/kg, so cannot rule out a rumble of thunder or two Sunday evening.
Going into Sunday night, PWAT values increase significantly, topping out at about 1.3 inches by midnight. With building 700mb vertical velocity overnight, significant rainfall is possible. Looking at NBM QPF outputs, have gone with a higher end precip amount for the period.

Thomas

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