P
PowderProject
Well-known member
Short term...today through tuesday night
storm system sagging south through the pacnw with the cold front
getting ready to enter far nrn mt. System should move into nw
wyoming after 06z with a period of decent snowfall expected as the
baroclinic boundary hooks up with brief right entrance region jet
streak dynamics. Speed of the system should hinder most of the nw
mtns from getting advisory amounts but a few areas will likely see
low end advisory amounts of 5-7 inches. The combination of the
baroclinic boundary...cold front and right entrance region jet
streak dynamics may also impact the big horns and the lower
elevations of the johnson county late tonight and monday morning.
Have decided to issue a winter wx advisory for the big horns for
this combination. Heavier amounts will likely be on the favored
north facing slopes of the nrn part of the range and possibly our
favored south end of the range where snow showers may train.
As for the lower elevations...debated adding the buffalo area into
an advisory for tonight but uncertainty on amounts and begin time
close to the next package issuance allowed us to give the next
crew one more look. Early thoughts were for 2 inches around
buffalo with strong north winds. Jet streak could be the player to
push this into the advisory criteria...especially when combined
with the sustained north winds around 20kts. Since most of this
will occur after 09-10z...we still have time to issue this early
monday morning. Further south...upslope still looks fairly
impressive around casper and lander with 6-9 hours of decent omega
and 9-12 hours of solid upslope. Right rear quad of the jet streak
could also provide an early shot of snow at the beginning of the
event. Have edged lander and casper amounts up a little bit more
so the next crew can easily hoist an advisory...which appears to
be a reasonable certainty. The green mtns and rattlesnake ranges
should also see amounts ranging from 2 to 4 inches. And of course
the east slope of the winds will be getting good snow with near
whiteout conditions on south pass when the cold front comes
through and strong ne winds get cranking. By early evening...the
cold front will arrive in the red desert with strong ne winds and
widespread light snowfall. Snowfall amounts in the red
desert...i80 corridor will likely only be an inch or two but strong
ne winds could hamper travel at times.
The system should begin clearing from north to south monday night
leaving tuesday dry and chilly. Lowered temps on tuesday a few
more degrees east of the divide as temps will struggle to get out
of the 20s. Moderation should occur wednesday as mid level temps
recover and winds start to blow again. In fact...the cody
foothills will likely respond as early tuesday with winds
increasing tuesday night. No mtn wave signature but plenty of mtn
top winds to mix down. Overnight lows will moderate where these
winds develop...ie cod and cpr and some east slope mtns sites.
Long term...wednesday through sunday
..major change to much colder and snowy weather next weekend...
Confidence higher this morning on development of possible major
winter storm over much of the area next weekend...likely impacting
any travel and possibly laying down significant snow cover across
west and central wyoming (on top of any remaining snowfall from
monday storm) that will suppress temperatures well through the limited
daylight hours of winter. Money is also on a white christmas for
most of the area.
Leading up to this scenario the pattern will basically exhibit
typical "warm before the storm" in northwest flow wednesday and
thursday as persistent ridge over the west coast begins to
retrograde out into the eastern pacific and amplify. This shift
should act to flatten the flow over the northern tier of the u.s.
And keep most of the area breezy to windy and seasonably
mild...again temperatures will be highly dependent on any snow
cover remaining from monday storm. Weak isentropic upglide will
remain over the north through this period where chances of light
snow/light accumulations will remain.
H5 cold pool coming off of eastern siberia this morning will
traverse the bering sea into the gulf of alaska by thursday and
spill down into western canada friday...also pulling back some
more cold air from the backside of hudson bay low. This pool of
cold air then spills down front side of amplified ridge over
eastern pacific into the northwest u.s. Saturday...carving out a
deep trough over the interior west sunday. The ecmwf...though
slower run to run...more consistent with overall scenario than gfs
and forecast continues to be weighted toward its solution. Initial
weak front from clipper system backs across the northeast half of
the cwa thursday night and friday with chances of snow increasing
behind the this front. Stronger arctic front to begin to push
south across wyoming saturday as upper trough takes shape to the
west. Baroclinic region aloft over front should result in setup of
initial heavier snowbands across the area under regenerating
baroclinic leaf. Warm conveyor belt precipitation sets up saturday
night and sunday across the area over arctic airmass which would
bring significant snowfall with low water-to-snow ratios. Main
trend run-to- run of both models has been to slow down the
evolution of this pattern although ecmwf and gfs coming into a bit
better agreement on how it takes shape.
storm system sagging south through the pacnw with the cold front
getting ready to enter far nrn mt. System should move into nw
wyoming after 06z with a period of decent snowfall expected as the
baroclinic boundary hooks up with brief right entrance region jet
streak dynamics. Speed of the system should hinder most of the nw
mtns from getting advisory amounts but a few areas will likely see
low end advisory amounts of 5-7 inches. The combination of the
baroclinic boundary...cold front and right entrance region jet
streak dynamics may also impact the big horns and the lower
elevations of the johnson county late tonight and monday morning.
Have decided to issue a winter wx advisory for the big horns for
this combination. Heavier amounts will likely be on the favored
north facing slopes of the nrn part of the range and possibly our
favored south end of the range where snow showers may train.
As for the lower elevations...debated adding the buffalo area into
an advisory for tonight but uncertainty on amounts and begin time
close to the next package issuance allowed us to give the next
crew one more look. Early thoughts were for 2 inches around
buffalo with strong north winds. Jet streak could be the player to
push this into the advisory criteria...especially when combined
with the sustained north winds around 20kts. Since most of this
will occur after 09-10z...we still have time to issue this early
monday morning. Further south...upslope still looks fairly
impressive around casper and lander with 6-9 hours of decent omega
and 9-12 hours of solid upslope. Right rear quad of the jet streak
could also provide an early shot of snow at the beginning of the
event. Have edged lander and casper amounts up a little bit more
so the next crew can easily hoist an advisory...which appears to
be a reasonable certainty. The green mtns and rattlesnake ranges
should also see amounts ranging from 2 to 4 inches. And of course
the east slope of the winds will be getting good snow with near
whiteout conditions on south pass when the cold front comes
through and strong ne winds get cranking. By early evening...the
cold front will arrive in the red desert with strong ne winds and
widespread light snowfall. Snowfall amounts in the red
desert...i80 corridor will likely only be an inch or two but strong
ne winds could hamper travel at times.
The system should begin clearing from north to south monday night
leaving tuesday dry and chilly. Lowered temps on tuesday a few
more degrees east of the divide as temps will struggle to get out
of the 20s. Moderation should occur wednesday as mid level temps
recover and winds start to blow again. In fact...the cody
foothills will likely respond as early tuesday with winds
increasing tuesday night. No mtn wave signature but plenty of mtn
top winds to mix down. Overnight lows will moderate where these
winds develop...ie cod and cpr and some east slope mtns sites.
Long term...wednesday through sunday
..major change to much colder and snowy weather next weekend...
Confidence higher this morning on development of possible major
winter storm over much of the area next weekend...likely impacting
any travel and possibly laying down significant snow cover across
west and central wyoming (on top of any remaining snowfall from
monday storm) that will suppress temperatures well through the limited
daylight hours of winter. Money is also on a white christmas for
most of the area.
Leading up to this scenario the pattern will basically exhibit
typical "warm before the storm" in northwest flow wednesday and
thursday as persistent ridge over the west coast begins to
retrograde out into the eastern pacific and amplify. This shift
should act to flatten the flow over the northern tier of the u.s.
And keep most of the area breezy to windy and seasonably
mild...again temperatures will be highly dependent on any snow
cover remaining from monday storm. Weak isentropic upglide will
remain over the north through this period where chances of light
snow/light accumulations will remain.
H5 cold pool coming off of eastern siberia this morning will
traverse the bering sea into the gulf of alaska by thursday and
spill down into western canada friday...also pulling back some
more cold air from the backside of hudson bay low. This pool of
cold air then spills down front side of amplified ridge over
eastern pacific into the northwest u.s. Saturday...carving out a
deep trough over the interior west sunday. The ecmwf...though
slower run to run...more consistent with overall scenario than gfs
and forecast continues to be weighted toward its solution. Initial
weak front from clipper system backs across the northeast half of
the cwa thursday night and friday with chances of snow increasing
behind the this front. Stronger arctic front to begin to push
south across wyoming saturday as upper trough takes shape to the
west. Baroclinic region aloft over front should result in setup of
initial heavier snowbands across the area under regenerating
baroclinic leaf. Warm conveyor belt precipitation sets up saturday
night and sunday across the area over arctic airmass which would
bring significant snowfall with low water-to-snow ratios. Main
trend run-to- run of both models has been to slow down the
evolution of this pattern although ecmwf and gfs coming into a bit
better agreement on how it takes shape.
