- Day Three
acus03 kwns 030747
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
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.