Scientific Forecaster Discussion
fxus65 kcys 171711 cca
Area forecast discussion...corrected
National Weather Service Cheyenne Wyoming
1011 am MST sun Nov 17 2019
issued at 1006 am MST sun Nov 17 2019
Current forecast is generally on track late this morning. High
wind criteria has been met in Wyoming zones 110 (arlington) and 116
(i-80 summit) since early this morning with peak gusts of 60-65
mph. 700/850mb cag-cpr and cag-brx gradients remain elevated
through the afternoon and evening, and high wind warnings remain
in effect for the wind-prone areas of I-80 and I-25. Per 12z
sounding and blended MOS, raised afternoon temperatures a couple
degrees east of I-25.
Short term...(today and tonight)
issued at 258 am MST sun Nov 17 2019
Some spatially limited patchy fog showing up on the latest GOES-east
nighttime microphysics across the Laramie valley but overall flow
pattern aloft should lift and transport the fog instead of
keeping it stationary. Height gradients and high-res models are
still keeping the trend for a high wind event starting later this
morning across the wind prone areas of southeastern Wyoming. Biggest
changes made in regards to the high wind warnings are the upgrade
from the watch for the Bordeaux area and adding the south Laramie
range foothills to the warning as well. Timing for the Laramie
range zones in the warning though have been extended to 5 am
Monday morning while the Arlington zone is set to expire at 8 PM
tonight. The additional timing was added in response to the
expected shift to a more favorable wind direction from the
northwest to west as a Lee surface trough moves across the Great
Plains ahead of an elevated wave disturbance. 00z namnest wind
gusts are elevated Post 2 PM today through the overnight for
Laramie range areas with gusts above 60 mph possible. The GFS also
maintains a 60 to 70 meter height for the Craig to Bordeaux line
from 8 PM tonight through 2 am Monday to warrant the extension.
Otherwise gusty winds elsewhere as temperatures climb back into
the 50 degree range today with overnight lows dropping into the
mid 30s west and low 40s over in the Panhandle. As the disturbance
drops this evening some light drizzle and flurries may be possible
from Converse through Dawes counties with little to no
Long term...(monday through saturday)
issued at 258 am MST sun Nov 17 2019
A weak shortwave with limited vorticity moves across the northern
tier of County Warning Area producing limited precipitation chances of rain and
snow ahead of a ridging feature drying things up into early
Wednesday. Above-normal temperatures early on in the week with
upper 60s possible across the High Plains on Tuesday.
Models are remaining fairly consistent of a Pacific trough
splitting with one burst of energy being advected south along the
California coast and another eastward into Montana and the northern rockies.
Winds will turn to a more upslope favored orientation with another
Canadian airmass dropping in between the split features to cool
off area temperatures as initial rain transitions over to all snow
late Wednesday through Thursday morning. With the motion of the
upper level trough leaving the region by Thursday afternoon,
precipitation accumulation will diminish in response. Depending on
the eventual wind orientation of upslope flow and available
moisture, accumulating widespread snowfall should be expected
though confidence in stating initial snowfall amounts is lacking.
High pressure ridging is expected to build into the region though
concern on the split low off the California coast moving eastward may
limit the amount of drying and perhaps even bring another round of
precipitation along the forecast area at the Colorado border. Saturday
though remains dry and sunny under the ridging pattern.
Aviation...(for the 18z tafs through 18z Monday afternoon)
issued at 936 am MST sun Nov 17 2019
VFR conditions expected for the most part with gusty west winds.
Do need to watch the northern Nebraska Panhandle as a clipper
system moves through this afternoon. Could see some lowering
ceilings and a mix of rain/snow at kcdr for a time. Overall
though...VFR looks to prevail.
issued at 143 am MST sun Nov 17 2019
High winds will be the main concern especially across the wind
prone areas in southeastern Wyoming later this morning through the
evening. Beyond the evening, models are retaining the high winds
across the central and southern portions of the Laramie range into
Monday morning. Gusts up to 65 mph possible in the High Wind
Warning zones while min relative humidity values in the upper 20 and 30 percent
range keeping fire weather concerns minimal through the week with
another round of precipitation expected Wednesday into Thursday.
Wyoming...High Wind Warning until 8 PM MST this evening for wyz110.
High Wind Warning until 5 am MST Monday for wyz116.
High Wind Warning until 5 am MST Monday for wyz106-117.