Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Cheyenne Wyoming
345 am MDT sun may 24 2015
Short term...(today through tuesday)
issued at 240 am MDT sun may 24 2015
Today...just as the models have predicted...showers and a few
thunderstorms have moved to our northern counties. Models showing
the slow moving upper trough moving slowly northeast to east central
Wyoming by late this afternoon...with the deepest moisture and best
upward vertical motion across our northern and western counties this
afternoon...thus the inherited Flash Flood Watch looks in good shape.
Will see scattered to numerous showers today due to the proximity of
the upper trough...plenty of low and middle level moisture and decent
low level convergence noted over our counties this afternoon.
Tonight...our upper trough finally opens up. Despite nearly saturated
atmosphere column...not much upward vertical motion prognosticated...though
still expect scattered showers except over far southeast Wyoming
where rain shadowing effect will be most pronounced.
Monday...although the upper trough axis moves east of our counties...
there will still be enough residual low and middle level moisture...
along with differential heating and instability to produce
scattered to numerous showers and isolated late day thunderstorms.
Monday night...with ridging aloft...despite the abundance of low and
level moisture...will see is0lated to scattered afternoon and
evening showers...and isolated thunderstorms closer to Cheyenne.
Tuesday...next shortwave trough aloft moves into western Wyoming in
the afternoon...with a low level convergence axis setting up over
our western counties...and thus with adequate moisture...have kept
our scattered to numerous showers and isolated thunderstorms west of
a Douglas to Cheyenne line.
Long term...(monday through saturday)
issued at 345 am MDT sun may 24 2015
No appreciable inconsistencies noted with the 00z medium range model
solutions during the past 24 hours. The progressive amplified large
scale flow will continue with one upper trough tracking east across
the Midwest/Great Lakes and the other over the intermountain west.
Upper ridge between the troughs over the High Plains will likewise
translate east across the Great Plains and MS valley. The surface
pattern will be relatively weak with mainly light/variable winds.
There will be the presence of a Lee surface trough over the High
Plains early in the period which will gradually slide east into
the central Great Plains late in the week. Forcing mechanisms for
convection will be the surface trough as well as low level upslope
flow and lift from the passage of the upper trough. The upshot is
continued chances for showers and isolated afternoon/evening thunderstorms
through the week. The models hint at some drying next weekend...with
isolated showers confined to the mountains. Temperatures will finally
moderate to more seasonal levels Wednesday and Thursday with highs
in the 60s and lower 70s. Temperatures cool slightly Friday and
Saturday from the influence of the upper trough...then rebound Sunday
with the return of an upper ridge pattern.
Aviation...(for the 06z tafs through 06z Sunday night)
issued at 315 am MDT sun may 24 2015
Terminal conditions will vary from MVFR to LIFR east of the Laramie
range this morning. The mountains will be obscured. VFR to occasional
MVFR conditions will prevail with passing rain showers north and west of
the Laramie range. Surface winds will vary from easterly over
western NE to westerly across southeast Wyoming as low pressure lifts
northward across the region. Isolated thunderstorms and rain will once again develop
this afternoon...therefore kept thunderstorms in the vicinity wording in the tafs.
issued at 240 am MDT sun may 24 2015
No concerns due to recent rains and wet ground...along with
relatively light winds.
issued at 330 am MDT sun may 24 2015
Current and forecast rainfall from showers during the next 24
hours will average between 0.25 and 0.50 inches...with locally
heavier amounts possible with thunderstorms. Runoff from this
rainfall will maintain high water levels along the Laramie river
at Laramie and near Fort Laramie through early next week. Refer
to the latest river and flood statements for specific information.
Wyoming...Flash Flood Watch through this afternoon for wyz101-103>105-109.