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Next 12 Hours

Forecast data from the National Digital Forecast Database.

5 Day Forecast

• Wednesday
• 
• High: 61 °
• Low: 43 °
• T-Storms

• Thursday
• 
• High: 55 °
• Low: 36 °
• T-Storms

• Friday
• 
• High: 54 °
• Low: 43 °
• T-Storms

• Saturday
• 
• High: 70 °
• Low: 43 °
• Chance of T-Storms

• Sunday
• 
• High: 61 °
• Low: 37 °
• Partly Cloudy

Area forecast discussion for western South Dakota and northeastern Wyoming 
National Weather Service Rapid City South Dakota 
325 am MDT Wednesday may 23 2012 


Discussion...water vapor shows long wave trough covering the western 
Continental U.S....with next upstream short wave moving eastward across Idaho. Surface 
analysis places cold front from southeastern ND through central Nebraska. Much 
cooler air currently filtering into the County warning forecast area. 


Today...mostly cloudy and cooler conditions expected in wake of 
cold front. Short wave currently over Idaho will advance eastward today 
and bring an increasing chance for precipitation to our western zones this 
afternoon. Not a lot of instability so expecting more showers than 
thunderstorms. Precipitation chances will increase further tonight primarily 
across our western/southern zones as 700mb low attempts to cut off near the 
Black Hills. 


Thursday and Friday...unsettled and cool pattern will continue 
across the region. Precipitation chances will remain rather high on 
Thursday with cyclonic flow aloft and steep low/middle level lapse 
rates to the south of an upper low tracking eastward along the Canadian/ND 
border. Thunderstorms chances again look suppressed given minimal cape 
values. A short wave Ridge Crossing the region may bring a break 
to the precipitation chances Thursday night/early Friday...but a strong 
upper wave will overrun increasing Ely boundary layer flow on 
Friday and Friday night and is expected to bring more widespread 
precipitation to the area. 


Extended...a significant upper trough will remain west and north of 
the area during the weekend. Southwesterly flow aloft will bring a 
series of upper level disturbances through the area...with chances 
for showers and a few thunderstorms for the weekend. Mainly dry 
conditions are expected on Monday...with showers and thunderstorms 
returning for the middle of next week. Temperatures will generally 
be near or slightly below average over the weekend...with a warmup 
to near or slightly above average temperatures early next week. 


&& 


Aviation...12z tafs 
mainly VFR conditions are expected today. Rain showers and some 
isolated thunderstorms will increase in coverage this afternoon and 
evening. Conditions will deteriorate to MVFR/IFR this evening over 
northeast Wyoming and southwestern South Dakota as rain showers 
become more widespread. 


&& 


Unr watches/warnings/advisories... 
South Dakota...none. 
Wyoming...none. 
&& 


$$ 


Short term...Johnson 
long term....15 
aviation...15