Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/15/21

Area Forecast Discussion

National Weather Service La Crosse WI

 745 PM CST Thu Jan 14 2021

.UPDATE...Tonight
Issued at 739 PM CST Thu Jan 14 2021

Based on model and radar trends, forecast snowfall amounts have
been increased along and east of the Mississippi River into the 3
to 6 inch range. Meanwhile, snow totals in southeast Minnesota in
the Winter Storm Warning area were decreased into the 6 to 8 inch
range due to less snow expected tonight.

As the dry slot moves into the area overnight, the snow will
quickly diminish or end from the southeast. This should occur at
KLSE and KRST between 15.07z and 15.09z.

&&

.SHORT TERM...(This evening through Friday)
Issued at 201 PM CST Thu Jan 14 2021

Messy winter system continues to impact the region early this
afternoon, with warm air aloft leading to more of a wintry mix west
of the Mississippi River this morning and dry air preventing much
from falling to the east. Early afternoon surface observations
showed a surface low over far southeast Minnesota/far northeast
Iowa. While we`re going through a bit of a precip lull currently,
expect an uptick in coverage and intensity as we go through the
afternoon. As said low deepens through the afternoon, expect a cold
conveyor belt to start ramping up, bringing in higher PWAT air from
the east. In addition, short term guidance is in good agreement of
some stronger frontogenesis and a TROWAL providing plenty of lift
for an enhanced band of snow to form west of the Mississippi River
and pivot over the I-90 corridor. Unfortunately, it does look like
the timing of the band will impact the evening commute, especially
near and just west of the Mississippi River. While 14.12Z HREF
guidance doesn`t show particularly high chances for 1" per hour
rates in this band (30-50 percent), would expect at least some spots
within the band to see those rates, especially given the
aforementioned forcing beginning to show up in the latest guidance.

The surface low looks to move southward tonight with dry air
wrapping around it and into much of the forecast area overnight.
This will lead to snow lightening up or stopping completely for much
of the area. How far north and west the dry air makes it through
Friday morning remains a large question and will impact snowfall
totals quite a bit. That said, short term guidance is in reasonable
agreement that snow continues over the northwest half of the
forecast area (roughly a line including Charles City, IA and La
Crosse). To the southeast, CAMs do suggest the potential for some
light precipitation in the dry slot and RAP soundings are trending
toward a deep enough saturated layer for some freezing drizzle or
very light snow, pending presence of in cloud ice. That said many
other pieces of guidance are much shallower with the low level
moisture and weaker with the lift, which would result in a dry
period. For now keeping low precip chances in the forecast.

On Friday, the low will slowly push south/southeast with light snow
filling back in across the area. When all is said and done, expect
highest amounts of around 6 to 10" in southeast Minnesota where they
will receive the longest duration of snowfall and also be impacted
by the heavier band this evening. Elsewhere, totals are expected to
range from around 2 to 6 inches. Again, amounts will really depend
on how much of lull we see tonight. In addition, surface
temperatures right around freezing may prevent sticking at the onset
of snow, especially in river valleys, so snow totals may be lower in
those areas. Overall, totals did come down a bit, owing to said
warmer surface temperatures, as well as expected lower snow/liquid
ratios (right around 10 to 1). Still, with the anticipated higher
snowfall rates with the band tonight, do still look like we should
reach winter storm warning criteria, or at least be very close, so
not adjusting any headlines.

.LONG TERM...(Friday night through Thursday)
Issued at 201 PM CST Thu Jan 14 2021

Our winter storm will slowly depart into the Ohio Valley Friday
night with some lingering light deformation band snow across the
area, but little to no additional accumulation. Can`t rule out some
patchy freezing drizzle in spots overnight as the column desaturates
aloft. With persistent cyclonic flow over the region, forecast
soundings certainly show possibility of flurries into Saturday,
especially east of the Mississippi River. Slightly better snow
chances look to arrive heading into Saturday night and Sunday with a
weak shortwave dropping through the area. Plenty of GEFS and EPS
members show an area of light snow working southward across the
area, so will retain small precip chances in the forecast. Certainly
not looking like any appreciable snowfall out of this weak feature,
likely just an inch or less mainly near and west of the Mississippi
River. Temperatures will cool a bit over the weekend but will still
remain above normal for mid-January.

High pressure drifts over the region Sunday night into Monday, and
then a clipper system is progged to drop somewhere into the region
later in the day. Plenty of model spread in whether this system
remains a quick-hitting, sheared out wave aloft or whether it
develops into a slower-moving, deeper wave with impacts lingering
into Tuesday. As such, just relied on a blend for now which yields
slight chance PoPs for a portion of the area. Will continue to
monitor this feature. Models diverge more late in the period but
there is some potential for a Panhandle Low ejecting into the Ohio
Valley or Great Lakes region by Thursday. Very low confidence on
track this far out and whether it might eventually impact part of
the area, so another feature we`ll just continue to monitor.
Temperatures next week look to sit near or just above normal.

&&

.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 529 PM CST Thu Jan 14 2021

A band of moderate to heavy snow is expected to move northward
toward the Interstate 90 corridor early this evening and then stay
in the region through 15.08z. Hourly snow rates look to be in the
0.5 to 1 inch range. One new development in the HRRR is that the
heaviest snow looks to stay mainly in Wisconsin. We will continue
to monitor this to see whether this trend continues before making
too many changes to the KRST TAF. A dry slot looks to move into
KLSE around 15.08z. This may result in the remainder of the TAF
period for KLSE. As far as KRST, we will have to monitor where
the FGEN band forms for late tonight and Friday.


&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...Winter Weather Advisory until 6 PM CST Friday for WIZ017-029-
     032>034-041>044-053>055-061.

MN...Winter Weather Advisory until 6 PM CST Friday for MNZ088-095-096.

     Winter Storm Warning until 6 PM CST Friday for MNZ079-086-087-
     094.

IA...Winter Weather Advisory until 6 PM CST Friday for IAZ008>011-018-
     019-029-030.

&&

$$

UPDATE...Boyne
SHORT TERM...CA
LONG TERM...Kurz
AVIATION...Boyne



Area Forecast Discussion

National Weather Service Pueblo CO

 845 PM MST Thu Jan 14 2021

.UPDATE...
Issued at 822 PM MST Thu Jan 14 2021

Overall, no big changes to the forecast for tonight, and no big
changes to the headlines for Friday. However, did make some upward
adjustments to the winds and gusts.

Upper level system will continue to spin over the central CONUS,
with the western edge still impacting parts of CO tonight into
Friday afternoon. While winds will remain gusty over the area,
the stronger winds will be situated to the east for much of
tonight. Winds and gusts still on track to quickly increase early
Friday morning, and did think about starting the High Wind Warning
slightly earlier. At this time, any timing differences look to be
small, but will continue to monitor tonight as it is possible for
winds and gusts to strengthen sooner especially across Kiowa
County.

Latest RAP analysis showing some rather strong winds, 50-75kt, not
too far off the deck over the Central Plains. As the 700mb low
slightly retrogrades later tonight into Friday morning, will see
these stronger speeds pivot back over the far eastern plains of CO.
With tightening pressure gradient and mixing Friday morning, will
see speeds/gusts really ramp up from early to mid morning. Given
those speeds currently in place, expected trends with the pattern,
and with model soundings showing these speeds in place over the
far eastern plains by tomorrow morning, did increase winds and
gusts. Have mentioned of northerly gusts up to 65 mph, but I am a
little concerned there could be some occasional higher gusts
during the mid morning time frame. Didn`t want to go too high at
this time, but don`t think a few gusts in the 70-75 mph range
would be out of the question. Will continue to monitor trends
tonight and adjust as needed. It does look as if windier
conditions will be present to the west of the current High Wind
Warning, however, not enough to support expansion of the current
headline. Strongest winds and gusts will occur through midday, but
should begin to see a downward trend by early Friday afternoon,
though still remaining on the strong side.

&&

.SHORT TERM...(This evening through Friday)
Issued at 242 PM MST Thu Jan 14 2021

.SHORT TERM...(Tonight and Friday)

...One more day of wind, then add enhanced fire danger...

Currently...The strong upper low pressure system located over Iowa
and the Dakotas has created strong north to northwest winds across
much of the forecast area today with many locations reporting gusts
of 40 to 50 mph. Winds have been much stronger across the higher
elevations, but most sites save for the far eastern plains have
struggled to reach high wind criteria. Mt wave cirrus shield from
earlier today has finally dissipated, and temps at most spots have
only warmed into the 30s and 40s.

Tonight...The upper low moves very little tonight, as a H7 80kt jet
sits overhead. However, high res models are indicating that the
lower levels should decouple this evening and weaken, especially
along the I-25 corridor. Under clear skies, look for very cold temps
overnight along the corridor as well as the San Luis Valley.
Elsewhere, across the far eastern plains as well as the higher
terrain, winds will stay elevated for much of the night and minimum
temperatures will be more moderate. Expect lows in the 20s along the
eastern border, in the teens along the I-25 corridor and Upper
Arkansas River Valley, and 5 below to 10 above for the San Luis
Valley.

Tomorrow...Similar set up for tomorrow as the upper jet laying
across the region mixes down to the surface, and decided to issue
another high wind warning for those spots closest to the eastern
border starting at 5 am. Winds there are expected to increase to 30-
40 mph, with gusts up to 60 mph possible. The upper low center pulls
to the east enough that the focus area for the stronger winds should
slide out of the I-25 corridor, and since those areas did not meet
criteria today, felt safe in leaving them out. However, it will
still be windy tomorrow all areas. Also went ahead and issued a Red
Flag Warning for Kiowa, Bent, Prowers and Baca counties. Those areas
will have the strongest winds as well as the driest air, so critical
fire weather conditions are anticipated starting at 10 am and
lasting until 5 pm. After 5 pm models show the strongest winds
overhead will have moved east, and with the short days, high wind
conditions as well as critical fire weather conditions will ebb.
Look for high temps in 40s tomorrow for the plains, and 30s for the
high valleys. Moore

.LONG TERM...(Friday night through Thursday)
Issued at 242 PM MST Thu Jan 14 2021

The pattern will start to become somewhat more active through this
long term period as several disturbance will be moving through and
an active jet pattern will be over the region. Additionally, with
the jet over us, temps will are expected to at or around seasonable
values through this period. Based on current guidance, the best
chance for meaningful precip will occur during the Tuesday time
frame as a rather stout short wave is fcst to drop south across the
Great Basin, and favorable upslope flow is fcst to develop over the
region. The potential problem with this fcst scenario is if the
short wave drops south too far west, and then the chance of precip
will not be so favorable over the region (on the other hand if it
moves a bit farther east then we will see better upslope over our
fcst area). For now, the ensemble guidance is showing nearly all
members with some precip over the region during the Tuesday time
frame.

Other short waves are fcst to move across the region during this
period. A weak wave will move across the during the Saturday time
frame and this will likely bring some light snow to the mountains
during this time frame.

Later in the week things may continue to be active as a long wave
trough is likely going to push through. How this trough come through
and how amplified it will be still is uncertain, but it will likely
continue cool and unsettled later in the week.

As for temperatures, given the jet pattern over the region temps
will remain at or around seasonable through this period. Tuesday
will likely be the coolest day. /Hodanish

&&

.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 242 PM MST Thu Jan 14 2021

VFR conditions will prevail for all locations throughout the
forecasted period. The tightening of the gradient with the
low pressure system that is propagating southeastward to the
northeast will provide strong and gusty winds this evening, so some
light to moderate CAT could be possible, especially east of the
Rampart Range and further eastward over the plains. Winds will
decouple later this evening and remain strong and gusty over the
mountain ranges and along high mountain canyons and passes
throughout the night. These winds will begin to percolate back
to the surface by 17Z tomorrow and become strong and gusty and even
stronger in the northeastern portion of the CWA by tomorrow
afternoon as a significant jet maxima at the 700mb level of 75-85kts
sets up over this area, so expect even some moderate or even
possibly severe CAT to be present again from 17Z to 00Z if flying
below FL100 over this portion of the CWA. Winds will increase over
20kts from the surface up to FL020 due to this jet maxima aloft,
therefore there will be LLWS (Speed sheer) present for COS from 17Z
throughout the remainder of the forecasted period.


&&

.PUB WATCHES/WARNINGS/ADVISORIES...
High Wind Warning from 5 AM to 5 PM MST Friday for COZ095>099.

Red Flag Warning from 10 AM to 5 PM MST Friday for COZ234>237.

&&

$$

UPDATE...RODRIGUEZ
SHORT TERM...MOORE
LONG TERM...HODANISH
AVIATION...STEWARD



Area Forecast Discussion

National Weather Service Riverton WY

 354 PM MST Thu Jan 14 2021

.SHORT TERM...This evening through Friday night
Issued at 150 PM MST Thu Jan 14 2021

After a varied weather day yesterday with record high temperatures
in spots and winds in excess of 60 mph, today is much quieter. It
is still quite windy, especially over Johnson County where a High
Wind Warning remains in effect until 5 PM this afternoon. While
it is less windy than yesterday, expect many areas to continue
gusting to over 40 mph at times until around sunset. MOS data
show winds diminishing in most places by around this time, with
some areas still lingering into the evening hours.

The current pattern over the CONUS is highly amplified with a deep
trough carved into the Plains and MS Valley and a closed low near
the Quad Cities. In the west, an area of high pressure is
centered off the California coast southwest of Point Conception.
In between is a tight gradient with a strong northerly to
northwesterly flow. This is the flow that is currently over
Wyoming. This should allow for dry conditions through the rest of
the day, under a good deal of sunshine. The only exception would
be over the Bighorns and Absarokas, where some lingering snow
showers may be around through the afternoon hours. The
aforementioned trough is projected to move eastward slowly
throughout the period, allowing the winds to finally lessen. With
winds diminishing tonight and the absence of much cloud cover,
low temperatures should be seasonably cold with some below zero
readings over the western mountains and single digits to teens
elsewhere. The ridge becomes more oriented west to east tomorrow
with the axis forecasted to be over the CWA around 00Z Saturday.
Therefore, expect the daylight hours Friday to remain dry with
temperatures several degrees warmer over the mountains and other
areas being similar to today. By the time tomorrow night comes,
models show a shortwave trough moving through the overall ridge
pattern. Some light snowfall is possible with this feature, mainly
over the western mountains and the Bighorns. It is not out of the
question that southeast Sweetwater County may also see some snow,
as the HRRR puts out an area of precipitation from Rock Springs to
Wamsutter at 09Z and 12Z Saturday. MOS data shows just under 20
percent PoP on the NAM from 06-12Z for Rock Springs, so
confidence is low on anything of significance over this area.
Expect accumulations up to an inch over the Tetons and near
Yellowstone and, possibly, one to two inches over the Bighorns.

.LONG TERM...Saturday through Thursday
Issued at 150 PM MST Thu Jan 14 2021

Any leftover snow from the Friday night system should be ending
Saturday morning, with mainly dry conditions with transitional
ridging and surface high pressure building into western Wyoming.
These dry conditions should hold through Saturday night and into
Sunday morning.

The next Pacific trough then moves into northwestern Wyoming for
Sunday afternoon and crosses the state through Monday. Both the
ECMWF and GFS are in fairly good agreement with keeping the
chances of precipitation across the area through Monday night.
Both models also favor northern Wyoming for the heaviest QPF.
There are some differences in the details however. The GFS is
somewhat further south with the best forcing and has heavier QPF,
especially in eastern areas. Meanwhile, the ECMWF keeps the
system a bit more disorganized with the best forcing to the north
across Montana. As a result, confidence on any snowfall amounts
remains low at this time. Still time to watch it though, as it is
still 3 days out.

Shortwave ridging should then bring mainly dry conditions for
Tuesday. Uncertainty then gets cranked up to 11 for the evolution of
the possible next system for midweek. The models continue to be
undecided on the effect of an upper level low near California and
that will be the determining factor. The models also continue to
show very poor run to run consistency. For now, we kept things
mainly dry with snow mainly over the mountains until there is
more model agreement.

&&

.AVIATION...For the 00Z TAFS through 00Z Saturday

VFR conditions are expected at all terminals through the TAF period.

Strong west to northwest wind observed this afternoon across much
of the area will weaken this evening. Most locations will
generally have light winds by around 06Z. The exception will be
breezy westerly winds will remain at KRKS through the TAF period.

A few snow showers over the northern mountains, pushing into the
adjacent lower elevations, will be ending at the beginning of the
TAF period.

Patchy morning fog across the far western valleys is not out of
the question, but overall boundary layer moisture looks a bit dry
for anything widespread.

Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for
the latest information on icing and turbulence forecasts.

&&

.FIRE WEATHER...
Issued at 150 PM MST Thu Jan 14 2021

Expect windy conditions to continue for the afternoon hours, making
for good conditions for any smoke dispersal.  Temperature inversions
may set up tonight for basin areas with a mainly clear sky and light
winds.  Dry conditions are expected for the day Friday.  Some snow
may return to the western mountains and Bighorns Friday
night/Saturday morning.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
High Wind Warning until 5 PM MST this afternoon for WYZ010.

&&

$$

SHORT TERM...Clayton
LONG TERM...Hattings
AVIATION...Murrell
FIRE WEATHER...Clayton