Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/09/21
Area Forecast Discussion
National Weather Service La Crosse WI
804 PM CST Wed Dec 8 2021
.UPDATE...
Issued at 750 PM CST Wed Dec 8 2021
Main update to the next 12-18 hours was to add a *slight* chance
of freezing rain to the forecast for northeast Iowa early Thursday
morning and a wintry mix of sleet as far north as La Crosse.
Near-term CAMs and HREF progs have been steadily increasing in
PoP values and coverage this evening with the next wave of modest
isentropic ascent ahead of an approaching H850-700 wave. While PoP
values have been increasing, forecast profiles from these same
models reveal a notable wedge of dry sub-700mb air in place
coincident with the passage of the best forcing. A +3 to +5 C
warm nose scoots into northeast Iowa after 06Z with dewpoint
depressions in this region of 10-13 C. Saturation takes place
aloft and any precipitate that does manage to reach the surface
between 11-15Z will likely experience the full warm nose temps
versus the wet bulb values typically used in top-down p-type
calculations. Therefore subbed in the RAP MaxTAloft values into
the grids for a short time window from 10-15Z before increased
precip loading pushes the airmass back to the wet bulb temp.
That all being said, this window for freezing precip is quite
narrow and likely much, if not all, of the melted snow will
evaporate before it reaches the subfreezing surface. Therefore,
kept PoPs low and did not increase the messaging for this event
outside of the grid edits and HWO update.
The >0 C warm nose extends as far north as La Crosse and therefore
also added a brief period of wintry mix in the morning before the
warm nose collapses and changes the p-type back to snow.
&&
.SHORT TERM...(Tonight through Thursday)
Issued at 230 PM CST Wed Dec 8 2021
Our next sensible weather system is set to arrive tomorrow morning
as a shortwave trough currently near the Arizona/Utah border moves
northeast overnight. As the pressure gradient tightens overnight,
southeast winds increase to 10-18 knots with gusts up to 25 knots in
southeastern Minnesota. Saturation continues to look more favorable
as the shortwave arrives, with light snow beginning around 6-7AM and
spreading northeast across the forecast area.
As seen in various model soundings, ice aloft decreases from west to
east near the trailing edge of the precipitation. Heading into the
afternoon, precipitation could become mixed as it exits the
Mississippi River valley. Snow is again favored in central Wisconsin
before undergoing a similar transition to mixed precip as it moves
out of the forecast area. This is especially evident in Taylor and
Clark counties where freezing drizzle is most favorable as the low
pressure center moves off to the northeast.
While many in the forecast area could see flurries of snow tomorrow,
its impacts are not expected to be very noticeable. Low QPF and near-
average snow ratios lead to snow totals of less than a half inch for
most. Areas along and north of I-94 could see closer to an inch.
.LONG TERM...(Thursday night through Wednesday)
Issued at 230 PM CST Wed Dec 8 2021
Focus remains on expected winter storm to finish the week. So far
this system has shown few surprises with a relatively consistent
look to it as the date draws closer. While details are not all there
yet, confidence continues to grow based on various datasets.
As stated previously, numerous factors expected to favor this event.
Dynamic mid level trough sweeps out of the southwest Friday with
impressive moisture and warm air advection. Quasi-geostropic /QG/
forcing is strong and deep, with deformation axis still tracking
across our service area.
Speaking of track, run to run look at model blends showing some
slight shifts. GEFS members showing good overall consistency in
general track, which helps confidence, but some cluster members show
slight adjustment back northwest a bit. This shift would bump higher
totals that way, but also adjust the mixed precipitation zone I will
discuss later.
Amounts still remain a bit in question as well. Probabilities of 6"
or more have increased in blends due to some ensemble members
showing higher QPF. Plumes still have larger range based on this
variety that could be related to speed and intensity of overall
system. Still prefer idea of a more progressive system which may
lower threat for larger amounts but we will see. Consensus of model
blends and interagency data fields, has moved heavy snow axis
slightly higher and slightly northwest from previous forecast.
Given dynamics, warm air aloft will still impact precipitation types
in southern areas. This boundary between all snow, a mix, or liquid,
could vary amounts in that range. Could also see a convective nature
to precipitation in that area with a wintry mix and/or sleet at
times. Back in the colder air and main deformation axis, snowfall
rates could be relatively high at times /2"+ per hour/ with this
being one of the biggest impacts to travel. This is especially true
for Friday evening commute and peak travel time. While there will be
some wind threat with drifting, does not appear to be a major
contributor to impact.
Overall it appears current watch has good placement but will bump a
tier north based on forecast adjustment. Multitude of data still
points towards eventual Winter Storm Warning with heavy snow as the
main contributor.
This system is lacking an arctic airmass behind it and just about as
fast as it moves through, upper ridging and warm up replace it
starting Sunday. In fact Sunday has potential to be a good snowfall
clean up day which should lessen any lingering impacts relatively
quickly.
Airmass warmup next week still on track, but will obviously be
moderated by fresh snowpack. Even so could see 40s across much of
the area with possibility of some 50s where snow depth erodes or is
clear.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 547 PM CST Wed Dec 8 2021
A shortwave trough will move through the region from Thursday
morning into the early afternoon. This system will produce a
3-hour window of light snow. This snow will likely occur at
KRST 09.14z through 09.17z and KLSE from 09.15z through 09.18z.
Snow amounts will likely only amount to a few tenths of an inch.
When this snow is occurring, both the ceilings and visibilities
will become MVFR. In addition, there will likely be low level wind
shear at KLSE from 09.10z through 09.15z.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...Winter Storm Watch from Friday afternoon through late Friday
night for WIZ017-029-032>034-041>044-053>055.
MN...Winter Storm Watch from Friday afternoon through late Friday
night for MNZ079-086>088-094>096.
IA...Winter Storm Watch from Friday afternoon through late Friday
night for IAZ008>011-018-019.
&&
$$
UPDATE...Skow
SHORT TERM...KAA/DB
LONG TERM...Shea
AVIATION...Boyne
Area Forecast Discussion
National Weather Service Duluth MN
944 PM CST Wed Dec 8 2021
.UPDATE...
Issued at 944 PM CST Wed Dec 8 2021
There are are a couple of challenges in the forecast with the
first snowfall along portions of the North Shore, particularly
coastal Cook County. The second issue is a winter storm that may
affect portions of northwest Wisconsin Friday into Saturday
morning.
We didn`t make any significant changes to the going forecast along
the North Shore. Some light snow was falling there as of late
evening and light accumulation is expected tonight. As better
lift arrives late tonight into Thursday morning, snowfall rates
should be on the increase along the North Shore. The HREF
continues to indicate snowfall through early Thursday evening of 6
to 8 inches. There will be good fetch across the lake with
southerly low level flow and initially good delta-T values into
the early morning hours. However, there is warming occurring due
to the southerly winds. Taking a look at RAP soundings over/near
the North Shore reveals a low inversion and a rather deep layer
above the surface with temperatures at or warmer than -10C
indicating riming of the snow could be a factor despite the
potential for more convective lake processes occurring. Given the
limiting factors, we`ll stick with the Winter Weather Advisory for
now. We did mention the potential for some local accumulations of
7 or 8 inches and snowfall rates near an inch per hour Thursday
morning into early afternoon in the advisory.
As for winter storm on Friday into Saturday morning. We opted to
not issue a Winter Storm Watch this evening for portions of
northwest Wisconsin. The latest NAM has come in further north but
we`d like to see the GFS and ECMWF to check their trends before
making any decisions. The NAM can suffer from having it`s
precipitation too far north. This storm definitely bears close
watch as heavy snowfall will be possible.
&&
.DISCUSSION...(This evening through Tuesday)
Issued at 325 PM CST Wed Dec 8 2021
Summary: Light to moderate snow moving in for tomorrow morning. A
quick break during the day on Friday before accumulating snow
returns to the region late Friday into the first half of the
weekend. A somewhat questionable temperatures increase mid next
week.
An upper level trough will move into the region early tomorrow
morning. Model soundings indicate a dry layer below 700mb for
mainly the western portion of the CWA. This will need to saturate
prior to any snowfall reaches the ground. As the upper trough
swings eastward the dry layer appears to saturate by mid-morning
tomorrow for the CWA so expect snow to start developing around
noon. Should also note rimming is present below 700mb once it
saturates which will lower snow ratios. Due the limited moisture
initially as the wave moves into the region, the areas in the
western half of the CWA will get a half to near one inch. A lake-
effect pattern does set up prior to the trough moving through,
therefore higher QPF values will be in the Arrowhead as winds will
be out of the south bringing in some moisture off the lake. Due
to that expect snow to start there much earlier Thursday morning
along with much higher snowfall amounts of 3 to 5 inches with
locally higher amounts. QPF was in question for after 12Z along
the higher terrain for southern Cook County which would have lead
to a Winter Storm Warning. There is little confidence that the
area will receive greater than 6 inches in 12 hours so adjusted
the QPF down where there is higher confidence of reaching the 3 to
5 inches previously mentioned. Due to that, a Winter Weather
Advisory has been issued beginning tonight through tomorrow
evening.
Next our attention is drawn to the system that will affect the
region for the first half of the weekend. A trough will swing out
into the plains late Friday afternoon and continue moving
northeastward affecting the southern counties of the CWA by late
Friday afternoon. There is concern because the models runs have
brought the system northward that this might continue in the
following runs. Therefore have held off on a Winter Storm Watch at
the moment to see if this trend continues. Other concerns with
system is that there could be an indication that on its current
track the snow might fall further north than expected. A jet
couplet sets up over WI which can be seen in the higher omega
values. This could bring higher snow totals towards the Duluth
metro. Additionally, two frontogenesis bands set up that could
also contribute to higher snow totals. One is west to east across
Duluth where as teh other is further south towards souther WI.
There is still a lot of uncertainly with this storm so this will
certainly be something to watch over the next few days because any
wiggle will cause the snow totals to adjust north or south.
After the storm moves out the region we will be under the
influence of an upper level ridge through the early part of next
week. There is some concerns that the temperatures mid-week may
be too warm for the snow pack that is currently on the ground
along with any additional snow that will fall this weekend. At the
moment, no changes have been made to the long term temperatures.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 531 PM CST Wed Dec 8 2021
Mostly VFR conditions were observed across the region late this
afternoon, with only some lingering MVFR ceilings along the
International Border region. VFR conditions will remain in place
before a round of light to moderate snow moves into the region
after sunrise Thursday as a mid-level shortwave passes through.
Ahead of this wave, some stronger 850 mb flow will support low-
level wind shear at all TAF terminals, with winds aloft around 40
to 50 kts. The snow should result in mostly IFR ceilings and
visibility reductions before the ceilings improve from west to
east late Thursday. The forecast models are in good agreement with
the ceiling heights dipping to IFR for a time at all TAF
terminals, but there is a bit more uncertainty regarding the exact
visibility reductions due to the falling snow. Due to riming ice
crystals expected, snow should be more of the wet and heavy
variety.
&&
.MARINE...
Issued at 944 PM CST Wed Dec 8 2021
Southerly winds will be on the increase overnight with speeds from
10 to 20 knots and gusts from 20 to around 25 knots. We added in
the Saxon Harbor area to a Small Craft Advisory tonight into
Thursday afternoon, mainly due to stronger gusts. Gusts will be
from 25 to 30 knots on Thursday across much of western Lake
Superior most areas will continue to be under a Small Craft
Advisory. The wind will veer a bit to southwest on Thursday then
veer to west to southwest Thursday night and diminish late.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 12 30 16 30 / 30 60 0 10
INL 11 29 11 27 / 20 40 0 0
BRD 14 33 15 31 / 20 20 0 20
HYR 10 31 14 31 / 20 60 0 30
ASX 11 32 16 32 / 30 70 10 20
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...Winter Weather Advisory from 4 AM to 10 PM CST Thursday for
MNZ021.
LS...Small Craft Advisory until 4 AM CST Friday for LSZ140>142-146-
147-150.
Small Craft Advisory until 4 PM CST Thursday for LSZ148.
&&
$$
UPDATE...Melde
DISCUSSION...KSE
AVIATION...Melde/JTS
MARINE...Melde
Area Forecast Discussion
National Weather Service Quad Cities IA IL
818 PM CST Wed Dec 8 2021
.UPDATE...
Issued at 818 PM CST Wed Dec 8 2021
Wintry Mix possible for AM Commute
Impacts: Latest trends in the CAMs are hinting to more of fzra
threat eventually turning to sleet and snow for the AM commute.
There are still unknowns about whether or not it will precipitate
near daybreak. If it does, we expect an onset of fzra mixed with
sleet, turning to sleet and then snow. Temperatures are cool
enough to cause an issue with icy surfaces. With confidence low on
occurrence have opted to not issue a winter weather adv as of
late. If precip reaches the ground, this will affect most of the
area, with the greatest impacts expected near CID and IOW.
Meteorology: With dry low levels, the use of MaxTw to determine
if ice will melt is too cool, instead the use of MaxTa is needed.
The RAP looked to have a good handle on warm temps aloft starting
precip as fzra before evap cooling causes sleet and then snow. The
HRRR has been trending towards more coverage of ice accum with the
onset of precip. The NAMnest is the most impactful as it lingers
fzdz across the area during the day. Do not think this will happen
as most fzdz issues occur at dark. There remains questions about
saturation and actual precip occurring. This is why we have kept
chc pops as opposed to higher. If confidence in this occurring
increases, then we would possibly need an ADV overnight.
&&
.SYNOPSIS...
Issued at 240 PM CST Wed Dec 8 2021
A surface ridge of high pressure over the central and northern
Mississippi River valley was providing clear skies and light winds.
Despite the full sunshine and bare ground, the weak mixing and light
winds were confining temperatures to the lower to mid 30s this
afternoon. A very dry airmass remained in place with widespread
dewpoints in the teens. Looking westward, the next in the succession
of fast moving systems was in the form of a shortwave trough seen on
water vapor imagery moving into the central rockies, which was
inducing lee troughing across eastern WY and CO. This system will
rapidly move through the area bringing our next potential for light
precipitation early Thursday. A much larger, more organized winter
storm system will track through the Midwest Friday and Saturday.
&&
.SHORT TERM...(This Evening through Thursday)
ISSUED AT 240 PM CST Wed Dec 8 2021
Clear and cold conditions through this evening will be followed by
increasing clouds then a quick wave of precipitation early Thursday.
Tonight will see a rapid drop to lows in the lower to mid 20s north
and mid to upper 20s south under the clear skies and light winds.
Temperatures will then begin to rebound after midnight with the
onset of high, then mid level cloud cover and increasing southeast
winds ahead of the surface trough.
Thursday, models are in agreement with the upper level wave and
round of forcing lifting northeast across eastern Iowa and northwest
Illinois roughly from 09Z to 15Z. With only mid and upper level
moisture to work with, top down saturation into the very dry low
levels will eat into much of any precipitation potential. Isentropic
lift and mid level forcing come together the greatest over east
central Iowa, where high chance pops are maintained for a quick
round of light snow, possibly mixed with a period of freezing rain.
With only a few hundredths QPF, no appreciable accumulation is
expected in eastern IA, but a dusting of snow is possible further
north over northeast IA into southern WI. Slight chances for rain or
snow are mentioned further southeast from SE IA into far eastern IA
into NW IL. Low level warm advection on brisk south to southeast
winds will boost temperatures well into the 30s as the precipitation
exits northeast into WI by noon.
The warm air advection southerly winds will continue into the
afternoon ahead of the surface trough that traverses the area by
evening. This will boost temperatures into the 40s to possibly lower
50s in the far south despite cloud cover that will likely break up
too late in the day to provide much of an impact.
.LONG TERM...(Thursday Night through next Wednesday)
ISSUED AT 240 PM CST Wed Dec 8 2021
Friday and Saturday...Of course, concentrating on the large low
pressure storm system this period ejecting out of the southern
plains and up toward or across the local area Friday night. The 12z
GFS and GEM have not that much of a deviation from previous runs,
with the main sfc low moving SW-to-NE almost bisecting the CWA from
the same direction and sfc low overhead of the Quad Cities by 9-10
PM or so at 994 MB depth, with eyes on south central LK MI by 1 AM
Sat morning. THe 12z NAM and GEM may even be a bit farther west then
the GFS, and conceptionally the H85 MB low tracks northwest of the
sfc feature. The ensemble idea of these solutions still suggests
increasing sfc temps and mainly rain spreading up acrs the area
after mid Friday morning, with a wintry mix of rain/sleet/snow acrs
portions of eastern IA north of I80 until mid afternoon when the mix
gets shunted along and north of the western Hwy 20 corridor. In-
wrapping northeast to southwesterly pre-cyclone LLVL flow will make
for late day highs in the mid to upper 30s north, to near 50 in the
far south. Rain/showers will look to get flushed out to the east,
with areas of fog and drizzle moving under the approaching sfc low
and wind cull Friday evening. Isolated thunder may occur just
southeast of the CWa FRiday evening, before we get on the backside
and winds veer west to northwest and increase/become gusty in
tightening cyclonic LLVL pressure gradient.
Top-down and dynamical cooling bring about a precip change to
rain/sleet/snow going to all snow from west to east after 03z Sat,
but these models and there ensemble blend suggest the system`s
associated def zone just to clip the northwestern quarter or so of
the CWA with 1-2 inches of snow accum northwest of a Cedar Rapids to
Dubuque line by Sat morning. The in-wrapping cold conveyor driven
sfc winds nearing advisory level strength probably becoming more of
a story, or the combo of lingering light snow and brisk winds. The
heavy snow swath currently appears with these solutions to lay out
from along the SD/NE border, up along and just north of the IA/MN
border region and into north central WI. Continuing into Sat,
falling temps in the 30s then either maintaining or slight rebound to
low 40s at best, with ongoing 20 to 30 MPH winds with gusts 40-45
MPH. Any lingering light snow or flurries Sat morning in these
strong winds will have to be taken into account in any type of
advisory that might be needed(winter wx or wind based).
After all that, the new 12z ECMWF has come in with a bit of a
southeast jog of it`s LLVL low pressures back from it`s previous
run. It`s wetter as well, with QPF amounts ranging from a quarter
inch in the south, to over 0.75 of an inch in the northwest by early
Sat morning. The Euro evolves the change over snow def zone in a way
that it produces at least advisory level snows acrs the northwestern
third of the CWA Friday night, and the brisk winds producing some
blowing and drifting snow into early Sat morning. So that while this
Euro run/model is a more pessimistic outlier of the other model
blends, it shows that the scenario is far from certain and more
phasing and timing issues will need to be resolved over the next 24
to 36 hours.
Sunday...Warming south-southwest return flow in the wake of the
upper trof continuing to eject out acrs the northeast GRT LKS, and
also return flow on northwest flank of southeast CONUS sfc ridge,
will rebound temps well back up in the 40s, with even some lower 50s
possible south. Depending on any snow cover from the Friday night
system, temps may be held down in the northwest or north but that is
very subjective at this point.
Monday through next Wednesday...Broad thermal ridge and LLVL return
flow still on track to being unseasonable/near record warmth to the
region, with thicknesses and mix out temps suggesting 50s and 60s. A
near 70 reading may even be possible by the end of the period. On
fly in the mild ointment are signs of a west-to-east frontal
boundary getting hung up parallel under mid level ridge, if retreat
push slows late Mon thru Tue and may be a convergent focus for
return flow to produce some warm up hampering clouds or even spotty
light precip Tue or Tue night. But low confidence in this and better
moisture return from the south may occur later in the week past
Wednesday. ..12..
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday Evening)
ISSUED AT 617 PM CST Wed Dec 8 2021
VFR conditions are expected through the next 12 hours before a
possible MVFR deck and precip moves into the area. Expect mainly
snow, but some fzdz or fzra is possible around 12z at CID/DBQ.
Probability of this occurring is low, so left out of TAF.
Otherwise expect clouds to remain and finally return to VFR after
precip ends.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
UPDATE...Gibbs
SYNOPSIS...Sheets
SHORT TERM...Sheets
LONG TERM...12
AVIATION...Gibbs
Area Forecast Discussion
National Weather Service Pueblo CO
720 PM MST Wed Dec 8 2021
.UPDATE...
Issued at 706 PM MST Wed Dec 8 2021
No substantial changes to ongoing forecast with high wind warning
continuing for the southern Sangre De Cristo mountains with peak
wind potential between 03z and 09z when best mountain wave
parameters are in place. After 09z, cross-sections show strong
forward shear aloft as the upper jet translates in and this pulls
back the highest winds to the peaks. Will continue to watch latest
wind observations in mesonet and ASOS sensors this evening for
possible highlight expansions with western portions of Huerfano
county most at risk for needing a highlight. But given the limited
coverage to that zone, will hold off for now and continue to
monitor trends which should be revealed in the next hour or two.
-KT
&&
.SHORT TERM...(This evening through Thursday)
Issued at 317 PM MST Wed Dec 8 2021
...Strong winds along the east slopes of the southern Sangre De
Cristo mountains this evening and tonight AND Heavy snow for the
most of the southwest and central mountains tomorrow into Friday...
Currently...
A broad but rather strong mid level trough was over the western
United States. A lead short wave was currently moving over the
region and was bringing some light snow to the Continental Divide. A
stronger wave associated with this broad trough was still offshore
of the Pacific NW.
Locally, mild temperatures were over the region, as temps ranged
from the L50s to L60s across the plains. Over the larger valleys,
temps ranged in the 30s and 40s.
The winds were starting to pick up over the higher terrain, with the
strongest winds noted over the southern sections of the central
mtns.
Rest of today through tonight....
The main concern will be the strong wind potential over the southern
Sangre De Cristo mountain. The lead wave is bringing windy conditons
to this area during this afternoon. These stronger winds will
decrease early this evening but ramp up once again by mid evening
and last into the early morning hours. HRRR continues to indicate
winds gust potential to 100 mph over the east slopes of the southern
sangres later tonight. Without saying, a high wind warning is in
effect for this region through early tomorrow morning.
Periods of light snow over the contdvd will continue into the
evening hours and then decrease, but will once again pick up over
the n sections of the central mtns towards morning. 1 to 3 inches
will be possible.
Otherwise, a mild night is once again over the plains with min temps
in the 30s. Over the high country, temps will be rather uniform,
with lows generally in the teens and 20s.
Tomorrow...
The 2nd stronger wave will move into the region and snow will ramp
up significantly, especially during the latter half of the day. This
trough has quite a bit of moisture with it and snow will likely
become heavy at times over the western slopes. The southwest
mountains will likely be favored tomorrow afternoon as the flow will
a bit of a SW component to it. Snow amounts over the SW mtns overall
will likely be less than earlier forecast due to the wind component
not being as favorable.
Over the remainder of the of the region, the plains will once again
see another mild and dry day. Winds will be breezy near the mtns
with the breezy winds pushing eastward as the day progresses. In the
gap flow area, winds will be stonger, with gusts 20 to 30 mph
possible.
As for precip, the snow will slowly push eastward, and snow showers
will be possible over the San Luis valley later in the day with snow
increasing over the tops of the Sangres late in the day. More "blow
over" will occur across the SW and Central mtns, with steady snow
developing over the northern sections of the upper Ark Rvr valley in
the afternoon.
RH values will be higher tomorrow area wide so no fire weather
issues anticipated. Also, regarding all of the mtns, it will still
be windy at higher elevations. However, especially over the s mtns,
winds will decrease as compared to tonight.
.LONG TERM...(Thursday night through Wednesday)
Issued at 317 PM MST Wed Dec 8 2021
Key Messages:
- Significant new snowfall for the Continental Divide Thursday night
through Friday afternoon; light to moderate snow for the eastern
mountains.
- Light snowfall across the San Luis Valley Thursday night, and
along the I-25 Corridor Friday.
- Another storm Tuesday?
Thursday night through Friday...Latest model runs swing the upper
low pressure system across the region Thursday night through Friday,
though the upper trough looks less amplified and slightly farther
north. While the Continental Divide still looks like it will be hit
with significant new snowfall, the strength of this system is now in
question for the eastern mts and plains. Timing of this system shows
the upper trough axis crossing the Great Basin Thu evening, pushing
into western CO early Fri morning, then exiting the state and
continuing on into the central US Fri night. Total new snowfall
accumulations forecast through the event are expected to fall in the
one to two foot range for the eastern San Juan Mts as well as the
eastern Sawatch Mountains, though the southwest mts will likely be
the heaviest hit. Strong winds gusting up to 55 mph will also affect
those areas, so very dangerous travel conditions are likely. Lesser
snow amounts, 4 to 6 inches, and wind gusts up to 45 mph, will be
possible across the La Garita Mountains, and higher remaining
elevations of Lake and Chaffee Counties, and to a lesser degree the
Sangre De Cristo Mountains starting Friday.
On the back side of this system, strong north to northwest flow with
gusts up to 45 mph is expected to develop across the far eastern
plains Fri afternoon and evening.
As for temps, plan on lows in the 20s and 30s Thu night, then
warming into the 30s for the high valleys and upper 30s to upper 40s
for the plains on Fri.
Saturday through Monday...A ridge of high pressure builds into the
region as the winter system exits to the east. The coldest air of
the season so far will likely be in place early Saturday morning
with clearing skies, then look for dry conditions with gradually
warming temps over the weekend and into the start of the next work
week. Plan on high temps Saturday in the 30s for the high valleys
and 40s for the plains, then for Sunday and Monday 40s to around 50F
for the high valleys, and mid 50s to mid 60s for the plains.
Tuesday and Wednesday...Long range models are in fairly good
agreement in bringing a deep upper trough of low pressure onshore
across the West Coast late Monday. This system will cross the
southwestern US Tuesday and Wednesday, bringing another round of
snow and wind to the higher terrain for both days. Stay tuned. Moore
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 317 PM MST Wed Dec 8 2021
PUB and COS...
VFR anticipated during the next 24 hours. light winds tonight will
become southwesterly by late morning and become gusty during the
afternoon.
KALS...
Dry through tonight and tomorrow morning. showers will be possible
tomorrow afternoon. At this time do not expect MVFR conditions but
cant rule out a heavier snow shower causing brief periods of mvfr.
Gusty sw winds are expected tomorrow at KALS.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from 5 AM Thursday to 5 PM MST Friday
for COZ058-061-066.
Winter Storm Warning from 5 AM Thursday to 5 PM MST Friday for
COZ060-068.
High Wind Warning until 5 AM MST Thursday for COZ074-075.
&&
$$
UPDATE...KT
SHORT TERM...HODANISH
LONG TERM...MOORE
AVIATION...HODANISH