U.S. Severe Weather Forecast (Convective Outlook)

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Day Three

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Storm Prediction Center ac 030746 


Day 3 convective outlook corr 1 
National Weather Service Storm Prediction Center Norman OK 
0246 am CDT Thursday Sep 03 2015 


Valid 051200z - 061200z 


..there is a marginal risk of severe thunderstorms over a portion of the northern 
plains into the upper MS valley... 


Corrected for outlook graphic 


... 
A few strong to severe storms will be possible over a portion of the 
northern plains into the upper Mississippi Valley Saturday afternoon 
and evening. 


... 


Upper low over the northwestern U.S. Is forecast to move through the northern 
rockies during the day Saturday...reaching the northern High Plains very 
late Saturday night and early Sunday morning. Ahead of this feature 
another in a series of low-amplitude shortwave troughs will move 
northeastward through the northern plains and upper MS valley region. By 12z 
Saturday a cold front should extend from northwestern Minnesota then southwestward as a 
stationary front through southern ND or northern South Dakota and westward to a surface low over 
northern Wyoming. A cold front will extend from this low southwestward into the Great 
Basin area. Primary surface low is forecast to consolidate and deepen 
over southeastern Montana later Saturday in response to forcing accompanying the 
primary upper trough. The attendant Pacific cold front will reach 
the western Dakotas late Saturday night. 




..ern Dakotas through western and northern Minnesota.... 


A moist warm sector will be in place early Saturday from the eastern 
Dakotas into Minnesota where middle-upper 60s dewpoints will reside. Some 
thunderstorms will probably be ongoing within zone of isentropic 
ascent especially north of the front from northern ND and on nose of low level jet 
across portions of Minnesota. Warm sector is expected to become moderately 
unstable...but boundary-layer destabilization could possibly be 
limited by areas of widespread clouds during the day. Potential will 
exist for storms to intensify in vicinity of stalled front from eastern 
South Dakota into southeastern ND during the afternoon with additional activity 
possibly developing along warm conveyor belt into Minnesota during the 
evening. A modest middle-level jet accompanying the lead shortwave 
trough will contribute 30-40 knots effective shear supportive of 
organized storms with a threat for mainly damaging wind and large 
hail. An upgrade to slight risk will probably be needed in later 
outlooks for a portion of this region...but primary uncertainty at 
this time is evolution and extent of early storms. 


..cntrl through eastern Montana... 


Some threat for severe storms may evolve over eastern Montana into northestern Wyoming 
Saturday evening where Ely Post-frontal flow will result in higher 
dewpoints and at least modest instability in this region. Storms may 
develop along eastward advancing cold front and north of stationary front 
with a threat for hail and strong wind gusts. 


.Dial.. 09/03/2015