Scientific Forecaster Discussion
fxus65 kcys 101147
Area forecast discussion
National Weather Service Cheyenne Wyoming
447 am MST Tue Dec 10 2019
Short term...(today and tonight)
issued at 405 am MST Tue Dec 10 2019
Initial concerns early on this morning was increasing height
gradients at the 850mb via the latest GFS run for early morning
high winds across the wind prone areas in southeast Wyoming given the packing
vorticity and Omega fields. Highest wind gusts thus far this
morning peaking around 53 mph at Cooper Cove along I-80. Have
decided given that the height gradient drops around 12z to monitor
for further developments and hold off on immediate headlines
besides the high wind watch issued for later this
afternoon/evening and through Wednesday.
Height gradients at 850 mb for both the NAM and GFS along with
model soundings showing solutions of strong winds aloft with
favorable direction for high winds across The Gap areas tonight.
GFS particularly showing for the Craig, Colorado to Bordeaux of 60+
meter gradients as a zonal flow pattern sets in ahead of a
shortwave moving on shore from the Pacific. Blended winds to the
nbm and GFS to accommodate initial watch issuance though some
additional adjustment using the hrrr likely will aid once the hrrr
reaches out into the watch timeframe as it has handled the early
morning winds quite well.
Otherwise light snow showers over the Laramie, Wyoming and Kimball, NE
County lines have diminished from earlier kcys radar returns will
some light dusting to little accumulation possible prior to
sunrise. Temperatures a bit cooler than normal with highs from the
mid 20s in Carbon County to near 40 at ktor and kbff.
Long term...(wednesday through monday)
issued at 405 am MST Tue Dec 10 2019
High wind watches continue through the Wednesday period with wind
gusts up to 65 mph possible across The Gap wind areas along I-80
and I-25. Prolonged windy period continues into Thursday and
Friday as height gradients increase for Karl and kbrx with 60
meters and upper 80s meters respectively giving rise to likely
include watches for these areas in later forecast updates. Strong
winds of over 50 knots just above the surface being reflected
adequately by the GFS and NAM for these sites.
Seasonably warmer temperatures with upper 40s and possibly low 50s
over the High Plains into the weekend ahead of the next main
precipitation maker. Limited moisture and forcing with next low
late Wednesday may produce some Western Mountain snow though
accumulations should remain fairly light.
A departing Colorado low into the Central Plains along with strong upper
level jet flow of 80 to 120 kts with overarching 500mb trough
brings next round of precipitation and snow. GFS and Euro in
fairly good agreement along the Wyoming-Colorado border in terms of total quantitative precipitation forecast
though the Euro a bit more widespread of lower qpfs over the
northern forecast area of over 0.1" of precip. Another system
moves in through later in the weekend with fairly higher values in
the GFS over the Sierra Madre and Snowy Range area though higher
qpfs still stay constrained in both models across central and
Aviation...(for the 12z tafs through 12z Wednesday morning)
issued at 447 am MST Tue Dec 10 2019
Low clouds continue to sit over most area terminals this morning
with VFR conditions as ceilings have remained between 5 and 8 kft.
Isolated light snow showers have developed between kcys and ksny,
but will slowly diminish over the next few hours. Clearing skies
are expected by late-morning across most terminals with only few
to scattered upper level clouds remaining through the forecast period.
Winds will increase for southeast Wyoming terminals this afternoon, especially
near krwl where gusts to 30 kts out of the west will be possible.
issued at 240 am MST Tue Dec 10 2019
Next several days are expected to be breezy with higher
likelihood of high wind potential through The Gap wind areas today
through Friday. Relative humidity values and areas of lingering snowpack should
keep fire potential concerns at a minimum. Another round of
snowfall expected initially over the mountains Thursday afternoon
spreading out into the High Plains while temperatures remain near
Wyoming...high wind watch from this afternoon through Wednesday afternoon