Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/12/21

forecast discussion below highlights. Have seen a slow erosion of

the low clouds from the west with satellite being masked some by

 high cirrus but guidance and trends suggest a west to east
clearing line for the overnight period across the northern valley.
Patchy dense fog is developing from near Detroit Lakes north to
near Thief River Falls with this area expected to have the worse
conditions before improving late tonight into tomorrow morning.

&&

.SHORT TERM...(This evening through Tuesday night)
Issued at 324 PM CST Mon Jan 11 2021

HRRR/NAM have been pretty accurate with 925 mb and lower cloud
trends the past few days and has been doing reasonable so far
today. Once exception today, its 925 mb RH was progged too far
south. Low clouds will gradually clear out of NE ND from the west
and it is hopeful fog moves out too. Fog patches have remained
persistent for days on end esp in Langdon/Cando/Park River ND
areas. HRRR indicates main fog tonight will be more in NW/WC MN
esp in that area just east of the valley from Fergus Falls up to
Roseau. Will have fog mentioned there but maintain some fog
mention into NE ND til 06z. When/if clouds clear out of NE ND fog
may return in more ground fog situation but boundary layer winds
remain sufficient it would appear to prevent it. But we have been
down that rabbit hole before.

Tuesday should see any fog/low clouds give way to a partly sunny
sky.  Mild with mostly low-mid 30s.

.LONG TERM...(Wednesday through Monday)
Issued at 324 PM CST Mon Jan 11 2021

Main focus within the long term discussion will be on a winter
system to affect portions of eastern North Dakota into northwest and
west-central Minnesota between the late Wednesday and Friday
timeframe. While the severity and location of impacts remain
uncertain, at least minor impacts from this system appear likely
(i.e. four out of five chance), with around a two in five chance of
advisory level impacts, and a one in ten chance of seeing warning
level (i.e. significant) impacts. Because of these odds, this system
should be monitored for impacts from accumulating and drifting snow,
gusty winds, light icing, and reduced visibility.

Analysis of WPC clusters, ensemble percentile tables, and
deterministic runs yield high confidence in a well developed clipper-
type system to move out of south-central Canada into the Upper
Midwest around Wednesday-Thursday. This high confidence extends to
the belief of a deeply amplifying upper trough into the western
Great Lakes region Thursday-Friday timeframe helping maintain the
strength of the clipper as it moves west of the area. As the wave
pattern deepens, the clipper may slow as to moves west of the area,
possibly increasing residence time of impactful sensible weather.

There is also relatively high confidence in the presence of high
winds over 40 mph associated with this system to spread over the
Dakotas and into Minnesota. There are even some indications of very
strong winds over 55 mph Thursday and Friday, mainly within the
Dakotas into the Red River Valley. This is due to a strong jet of
low level winds accompanying the clipper`s initial cold front late
Wed into Thursday lingering around the backside of the clipper as
the upper trough deepens Thursday-Friday.

Lesser confidence revolves around the amount, location, and timing
of snow/wintry mix which will dictate severity of impacts
considering the likelihood of high winds to accompany wintry precip.
Ensemble guidance from NBM, ENS, and GEFS all point toward a greater
than 60 percent chance of at least minor QPF over 0.10 inches assoc
with this system, and thus one can infer minor winter impacts are
going to be likely. Guidance begins to diverge in suggesting greater
amounts of QPF/wintry precip, although it is possible to see
advisory level impacts (30-50 percent) with even at least some
possibility of warning level impacts (10 percent). Warning level
impacts translate to very difficult to impossible travel through
relatively long duration (greater than 24 hrs) of near-blizzard
conditions, significant drifting snow, and heavy snow. The presence
of near-blizzard conditions will be dependent to locations that see
falling and/or accumulated snow greater than 2 inches, and is
something the CIPS analog is showing values greater than 50 percent
in the typical Red River Valley. That being said, we shouldn`t focus
on one particular scenario over the other. With the range of
scenarios extending from minor, more nuisance type impacts to
significant impacts, the forecast of this late Wed to Friday system
should continue to be monitored.

Beyond Friday, confidence deteriorates in sensible weather, although
northwesterly flow looks to remain the dominant synoptic flow
pattern.

&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 540 PM CST Mon Jan 11 2021

Stratus and fog to impact most sites for part of the period with
FAR and GFK clearing this evening. Will see the worst conditions
at TVF and BJI for the overnight period with LIFR. Expecting VFR
conditions tomorrow once the remaining fog burns off.


&&

.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.
$$

UPDATE...JK
SHORT TERM...Riddle
LONG TERM...CJ
AVIATION...JK



AREA FORECAST DISCUSSION

National Weather Service Hastings NE

 602 PM CST Mon Jan 11 2021

.DISCUSSION...(This evening through Monday)
Issued at 355 PM CST Mon Jan 11 2021

The area has seen a welcome relief from persistently cldy, dreary
conditions today with nearly "wall to wall" sunshine across south
central Nebraska and north central Kansas. The only cld cover on
regional satellite is a narrow band of high cirrus associated with
quick-moving clipper system moving from Dakotas into MN. WV
imagery and RAP analysis indicates fairly active upper flow across
the CONUS as a whole, with strong vort maxima noted over S AZ,
AR, Great Lakes and New England, along with aforementioned wave
closer to home over Dakotas. None of these look to be particularly
impactful to local area, however. Shortwave ridging extends from
CA to N Rockies and will be main weather influencer next few days
ahead of a much stronger upper trough late week. Highs today have
been mild in the mid 40s to low 50s.

The main forecast concern is the potential for prolonged strong
winds Thu into Fri associated with an intense upper low forecast
to dig from N Rockies Wed night into the Mid MS Valley by Thu PM.
Appears the initial cold front and surge of strong winds will
arrive Wed night into Thu AM. Right off the bat, deterministic EC
and several of its ensembles indicate potential for fairly
widespread wind gusts of 50 to 60 MPH. The wind potential with
this system has gone nowhere but up on last several runs of EC
ensemble, with the mean coming more in line with higher
deterministic solution with each run. In fact, EC ensemble max
wind gust for GRI on Thu has incr from 36kt on 09/12Z run, to 47kt
on latest 11/12Z run. Also...not only has the magnitude been
steadily incr, but the length of time of strong winds has incr as
well, as more and more model solutions drastically slow the system
down over Mid MS Valley Thu night into Fri. Gut feeling is that
we`ll lose enough mixing to avoid widespread issues Thu night, but
seems to be some consensus towards another wind incr for daytime
Fri. GFS and EC differ on location and intensity of H85 winds by
Fri, though, so still some uncertainty. Agree with previous shift
that if current trends continue may soon need a High Wind Watch
for late Wed night into Thu.

Pcpn continues to look scant with this system, but will obviously
need to monitor the location of stalled upper low and associated
wrap- around pcpn closely, given how strong the winds will be. If
there`s a shift to the SW, pcpn chcs, and perhaps blowing snow,
will incr. Don`t want to draw direct comparisons to the system we
had Dec 23rd, though, as temps look to be several deg warmer.

Finally, would be remiss not to mention risk for incr fire weather
concerns, as well, esp for S/SW portions of CWA that have seen
less snow cover as of late. Model RH progs are already at near-
critical levels, but even if RH remains somewhat marginal, the
magnitude of wind gusts would alone be concerning.

Otherwise, enjoy and mild temps and relatively lgt winds thru Wed.
Have continued trend of going on warmer side of guidance for Tue
and Wed, though didn`t go straight CONSMOS just yet for Wed as
there could be incr high clds. Temps will turn colder Thu-Sat, and
the wind will make it feel even colder, but this appears short
lived as both GEFS/EPS have near to above normal temps Jan 17-20.



&&

.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Wednesday)
Issued at 601 PM CST Mon Jan 11 2021

VFR conditions expected with light wind. Confidence is high with
this persistent forecast.

&&

.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&

$$

DISCUSSION...Thies
AVIATION...Heinlein



Area Forecast Discussion

National Weather Service Goodland KS

 322 PM MST Mon Jan 11 2021

.SHORT TERM...(This evening through Tuesday night)
Issued at 131 PM MST Mon Jan 11 2021

Satellite and 500 mb RAP analysis showed a closed low over eastern
Arkansas this afternoon. Meanwhile, a shortwave trough continued
southeast across Arizona and New Mexico as upper ridging extended
from the west coast eastward towards the central Rockies. At 1:30 PM
MST, skies were sunny, with west/northwest winds at 10 to 15 mph.
Temperatures mainly ranged in the low 40s to low 50s.

Quiet weather persists tonight while northwest flow develops aloft
and the southeastern CONUS shortwave closes off and heads towards
Texas. Behind this disturbance, ridging continues to push into the
Plains. Expect lows in the teens and low 20s, with light west winds
under clear skies.

Tuesday looks to be even warmer than today, with highs in the 50s
and westerly surface flow. Am not anticipating much of a pattern
change in our area as the aforementioned low travels further into
Texas. However, dry air will be in place and attention turns to fire
weather conditions. Relative humidities are expected to fall into
the 15 to 25 percent range across the region in the afternoon.
Fortunately, west winds will be light at 10 mph or less. For Tuesday
night, temperatures should be a bit warmer, mainly in the 20s. Dry
weather prevails with mostly clear skies.

.LONG TERM...(Wednesday through Sunday)
Issued at 253 PM MST Mon Jan 11 2021

At the start of the long term period, long term guidance shows the
CWA under the front part of an upper air ridge with an upper air low
over the LA/AR border yielding a north-northwesterly flow aloft on
Wednesday. On Wednesday evening, an upper air trough moves toward
the CWA from the northwest with the base reaching the CWA by
Thursday morning. On Thursday, the long term models show a low
developing in the Great Plains area with some discrepancy in its
placement. As the low intensifies and progresses slowly east-
southeastward during Thursday, the flow over the CWA changes to
northwesterly as the back part of the trough advances over the CWA.
Going into Friday morning, the low appears to start to close off in
the western Great Lakes region which causes the flow over the CWA to
become more northerly. By late Friday going into Saturday, the low
progresses eastward allowing a trailing upper air ridge to start to
move over the CWA. By Saturday afternoon, another trough begins to
move in from the west reaching down to the TX/OK border and places
the CWA under the back end of this trough by Sunday morning. Later
Sunday, the flow aloft turns westerly as another jet streak digs
into the western CONUS. As models show some discrepancy in placement
and timing of upper air features later in the long term period, this
situation will be monitored to see if better agreement is seen in
future runs.

At the surface, the Tri-State area continues to see mostly dry
conditions as well as possible near critical elevated fire weather
conditions during the long term period. On early Thursday, models
show a cold front associated with a surface low near the
ND/MN/Canada border quickly making its way through the CWA bringing
windy conditions with forecasted northwesterly sustained winds up to
30 mph and gusts possibly reaching 50 mph in some areas. On Friday,
similar windy conditions continue in the CWA through the day as the
surface low tightens its gradient on its way in the Great Lakes
region. As both days show these windy conditions, near elevated fire
weather conditions are possible for the Tri-State area particularly
the extreme eastern portions on Wednesday and southwestern quadrant
on Thursday as forecasted minimum RH values look to dip below 20%.
On Saturday, models show a cold front passing through the area as
well as slight chance for light snow showers in the far western
parts of CO counties of Kit Carson and Cheyenne during the afternoon
evening hours. While long term models show a minimal amount of
snowfall associated with the slight chance of snow, this coverage
area may expand eastward depending on how the system plays out in
future model runs.

The Tri-State area expects Wednesday to be the warmest day in the
long term period with high temperatures in the upper 50s to middle
60s. As a cold front passes through the Tri-State area early
Thursday, highs for the day expect to range from the lower 40s in
the western portion to the lower 50s in the eastern portion. Friday
sees lows in the lower to middle 40s followed by highs in the lower
to upper 40s for the remainder of the extended period. Tri-State
area overnight lows for Wednesday expect to range from the upper 20s
in the western portion to the middle 30s in the eastern portion. Tri-
State area overnight lows for Thursday drop to the upper teens in
the western areas to the middle 20s in the eastern areas. The
remainder of the long term period expects to stay between the upper
teens and lower 20s range.

&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 322 PM MST Mon Jan 11 2021

VFR conditions are expected at KGLD and KMCK terminals through the
TAF period. Mostly clear skies are forecast. West winds at 5 to 10
knots prevail through Tuesday morning before shifting to the
southwest in the afternoon.

&&

.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&

$$

SHORT TERM...JBH
LONG TERM...076
AVIATION...JBH



Area Forecast Discussion

National Weather Service Green Bay WI

 545 PM CST Mon Jan 11 2021

Updated aviation portion for 00Z TAF issuance

.SHORT TERM...Tonight and Tuesday
Issued at 235 PM CST Mon Jan 11 2021

The latest RAP analysis and satellite/radar imagery show
shortwave energy passing across the central Great Lakes early this
afternoon. Meanwhile, a second shortwave is sliding southeast
over North Dakota. Weak warm advection in the low levels, ahead of
this 2nd shortwave, contributed to increasing moisture levels
just enough to produce freezing drizzle over northern WI this
morning. Visibilities have improved over the northwoods this
afternoon, so think freezing drizzle is no longer a threat for the
rest of the day. However, freezing drizzle could be a concern
again late tonight and is the focus of this forecast.

Tonight...A weak shortwave impulse be traversing the region during
the evening. Mid-levels remain very dry, so the threat of snow is
very low. But convergence along a surface trough may be just
enough to touch off some patchy freezing drizzle, mainly after
midnight over central to east-central Wisconsin. Will add to the
forecast, but remain skeptical that it could produce widespread
travel impacts. Otherwise, another low overcast night with patchy
fog developing by late evening. Lows mainly in the low to mid 20s.

Tuesday...Low clouds will likely continue to blanket all of
northeast Wisconsin during the morning. But as warmer/downsloped
air invades the region from the west, there are indications of
thinning low level moisture that could lead to partial clearing in
the afternoon. As a result, went with warmer highs into the lower
30s for most locations.

.LONG TERM...Tuesday Night Through Monday
Issued at 235 PM CST Mon Jan 11 2021

Quiet weather is expected through the middle of the week, with
with warmer air arriving ahead of a cold front approaching from
the Northern Plains. Highs are expected to reach 35 to 40 degrees
on Wednesday, roughly 15 degrees above normal.

Models support a significant pattern change for late in the work
week, and are in better agreement regarding timing of the incoming
surface and upper lows. The main difference is that the ECMWF is
a bit farther south with the surface/upper lows than the GFS.
Mixed rain/snow is expected to develop on Thursday as the vertically
stacked low moves into the western Great Lakes. This system will
drift east across the area Thursday night into Friday night,
producing scattered to numerous snow showers through the period.
As the low shifts to our east on Saturday, potential for minor
lake-effect snow showers will develop in north central WI, then
taper off Saturday night. Will probably see some snow accumulations
over the region with this slow-moving system, with several inches
possible in north central and parts of central WI over a couple
day period. The prospects for strong winds appear to be less than
earlier expected.

Temperatures will settle back to near-normal for the weekend and
early part of the next work week.
&&

.AVIATION...for 00Z TAF Issuance
Issued at 541 PM CST Mon Jan 11 2021

The main concerns this TAF issuance will be the continued low
clouds and fog potential. Eastern TAF sites have seen some
improvement to VFR ceilings this evening; however, more low
MVFR/IFR clouds are expected to redevelop late this evening and
overnight. There is a small chance of freezing drizzle, but the
possibility is low enough to leave out with this issuance.
Otherwise, IFR/LIFR clouds and visibilities will continue/develop
across central and north-central Wisconsin tonight into Tuesday
morning. Some improvement is expected Tuesday afternoon; however,
models continue to point toward additional, possibly more
widespread fog, Tuesday night.
&&

.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM.....MPC
LONG TERM......Kieckbusch
AVIATION.......Cooley



Area Forecast Discussion

National Weather Service Louisville KY

 916 PM EST Mon Jan 11 2021

.Forecast Update...
Issued at 916 PM EST Mon Jan 11 2021

A band of light snow developed over southern Kentucky earlier this
evening. A very light dusting has appeared in grassy areas in
Franklin and Scottsville. The roads on area traffic web cams look
like they are in good shape and most traffic appears to be moving at
normal speeds. Warren, Simpson, and Allen counties are spot treating.

The band continues from Franklin to Jamestown but within
the past hour has shown signs of widening and weakening. This trend
is expected to continue as the 5H wave over the Tennessee Valley
weakens and continues to push off to the east. Also, satellite
animations show a large area of dry air spreading from the Blue
Grass into southern Kentucky. The snow is already light and should
be reduced to flurries by midnight Central.

&&

.Short Term...(This evening through Tuesday)
Issued at 240 PM EST Mon Jan 11 2021

...Light Snow Accums Possible Across Southern KY This Evening...

The closed upper low is now over eastern Arkansas, and is expected
to move ENE through the Tennessee Valley tonight, weakening into
more of an open wave as it does so. Current water vapor imagery
shows a nice deformation axis stretching from Arkansas up through SE
Kentucky and into the central Appalachians. This is focusing a lot
of mid level moisture streaming over the southern half of the CWA,
and is expected to result in some light precipitation later this
afternoon into the evening hours across our far south and southeast
CWA. Some of the higher res models like the HRRR and NAM have been
hinting at a small deformation induced band of snow mainly in the
21z to 03 z time frame across our south, and given the setup and
familiarity from a recent event we tend to believe the output. As a
result, will mention a trace to a half an inch of snow from south of
Bowling Green over to the Lake Cumberland region. An isolated amount
closer to an inch cannot be ruled out somewhere along that axis if
the band persists/pivots enough. Temperatures have barely gotten to
freezing this afternoon under heavy cloud cover, so do expect the
low levels will be conducive to some light accums, especially the
later into the evening we get. A few slick spots on area roadways
seem possible. Plan on handling the potential with a Special Weather
Statement and continue mention in the HWO and social media graphics.
Evening shift will have to monitor any band development in case
stronger messaging is needed.

Outside of the snow/precipitation potential, cloud cover over the
rest of the CWA is the other issue/concern. Have seen some breaks at
times, and the western edge of the stratus out over MO/IL seems to
be thinning, but overall stayed fairly pessimistic with the clouds
through the remainder of the afternoon and evening. Do have pretty
rapid improvement toward and after midnight, with expected mostly
sunny skies by Tuesday. This should result in slightly "warmer"
temperatures peaking in the low to mid 40s.

.Long Term...(Tuesday night through Monday)
Issued at 234 PM EST Mon Jan 11 2021

Quasi split flow regime develops across the southern Plains into the
Tennessee/Lower Ohio Valley to start off the long term period. This
will result in dry weather for much of the week for central Kentucky
and southern Indiana as systems generally stay off to our north
and/or south. Temperatures should stay mild through the end of the
week as highs push into the upper 40s and low 50s under plentiful
sunshine.

The mild conditions won`t last long, though. Toward the end of the
week and into the weekend, long range guidance is in fairly good
agreement of a large scale trough/upper level low (ULL) digging into
the Midwest and Great Lakes region and impacting the eastern third
CONUS. Moisture return ahead of the cold front associated with the
trough will be very limited as most flow around and above 900mb does
not tap into the Gulf of Mexico. As a result, vast majority of
models and their ensemble members only paint light QPF amounts
(<.10") with fropa. Depending on how the trough/ULL tracks, there
may be some opportunities for light bouts of wintry weather over the
weekend, though these remain too unpredictable to narrow down for a
specific day/period at this time.

&&

.Aviation...(00Z TAF Issuance)
Issued at 618 PM EST Mon Jan 11 2021

MVFR stratus continues to plague the region, although a large clear
patch has opened up from LEX and CVG into southern Ohio. Satellite
animations show that the westward push of this clearing has slowed,
so for now in the TAFs will keep HNB/SDF/HNB under the stratus. LEX
has cleared out but may regain clouds later tonight. Winds will be
light and variable. BWG may see a few flurries as a weakening upper
level disturbance passes by to the southeast.

We should finally lose the low clouds tomorrow (if not tonight) as
high pressure builds into the region and and low level winds freshen
and come in from the southwest.


&&

.LMK WATCHES/WARNINGS/ADVISORIES...
IN...None.
KY...None.
&&

$$

Update...13
Short Term...BJS
Long Term...DM
Aviation...13




Area Forecast Discussion

National Weather Service Marquette MI

 559 PM EST Mon Jan 11 2021

.SHORT TERM...(This evening through Tuesday)
Issued at 414 PM EST MON JAN 11 2021

WV imagery and RAP analysis indicated a multi-stram mid/upper level
pattern with one shortwave exiting the region toward northern Quebec
and another moving from northern Manitoba into northwest Ontario.
Farther south, a shrtwv was sliding through the eastern Dakotras. At
the surface, a southwest flow of shallow low-level moisture ahead of
a trough through MN has supported persistent stratus deck and
mist/fog or fzdz that has resulting in some slippery untreated
surfaces. The clouds have been thick enough to limit temps to the
mid and upper 20s.

Tonight, weak to moderate 700-300 qvector conv with the Manitoba
shrtwv is expected to brush mainly northern Lake Superior into
eastern Upper Michigan. wsw low level winds with 850 mb temps around
-8C may be enough to support some light lake effect snow showers of
flurries through portions of the Keweenaw. Otherwise, little or no
pcpn is expected. However, cannot rule out some patchy fzdz, given
the abundant low level moisture. Clouds will also limit diurnal
range with min readings only into the low to mid 20s.

Tuesday, mid level and weak sfc ridging building into the area
with increasing wsw flow should bring some clearing by afternoon.
The sunshine and WAA will push temps into the mid 30s.

.LONG TERM...(Tuesday night through Monday)
Issued at 327 PM EST MON JAN 11 2021

Beginning Tuesday night, weak ridging with WAA will start us off.
This looks to be largely a continuation of the previous few nights,
with overcast skies and lows near 20F in the interior and mid-upper
20s by the lakeshores. The ridging will give way to a weak shortwave
sinking southeast into the Upper Great Lakes late overnight. Some
light snow may be possible in the east, but maintained a dry
forecast given the better forcings look to stay outside of our
forecast area. During the day on Wednesday, 850mb temps will stay
between 1-4C across the area. This warm air aloft will help raise
temps to ~15 degrees above normal. With the southwest flow, some
should climb into the upper 30s to near 40F. The warm air aloft will
continue overnight Wednesday and lows will respond with only
dropping into the mid 20s in the cold spots and near 30F by the
lakeshores.

Attention then turns upstream. An amplifying ridge off the west
coast will introduce broad troughing into the region. As this
longwave pattern begins to establish itself, a shortwave will eject
out of the Canadian Rockies late on Wednesday. From here, the
guidance continues to project varying solutions as the shortwave
evolves into a closed circulation. There are still notable
differences among the guidance, but the general consensus is that
the feature will occlude as it pivots from its southeast trajectory
and begin migrating toward the northeast somewhere between Lake
Superior and central Wisconsin early Friday. These spatial
differences result in difference locations for the system`s dry slot
and where any lake enhancement could occur. Ultimately the estimated
snow totals vary, but overall it still looks to be a good shot for
some widespread synoptic snow.

Guidance has slowed the system`s progression through the region.
Overall it looks to linger over the region into late Friday/early
Saturday, when it lifts out into Ontario. This delay will also delay
the colder air sinking south. 850mb temps look to break the -10C
mark early Saturday and fall to around -15C by the afternoon. With
the lake surface hovering around +3-4C, the resulting instability
will be enough for lake effect snow to develop within the north to
northwest wind snow belts Saturday into early Sunday. From there,
guidance again becomes mixed and most models have dialed back the
lake effect snow potential with winds taking on a more westerly and
perhaps even southwesterly direction. With the colder airmass,
daytime highs during the weekend look to peak in the 20s and lows to
fall into the teens with single digits possible Sunday night.
&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 559 PM EST MON JAN 11 2021

Persistent low level moisture will maintain IFR/low MVFR conditions.
Conditions are expected to lower back down to IFR/LIFR tonight. As
southwest winds increase late, conditions could lift back to MVFR
and even VFR toward Tue morning at KSAW but confidence is low.
&&

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 437 AM EST MON JAN 11 2021

A trough moving across Lake Superior will result in west to
southwest winds of 25-30 kts over the west and north-central
portions this morning, with a few gale force gusts possible at
higher platforms. Winds will subside below 20 kts by this afternoon
and generally remain below 20 kts tonight despite the passage of a
weak trough. West to southwest winds will increase again to 25-30
knots Tuesday into Tuesday night over west and north central
portions of the lake in advance of another trough passing over the
area late Tue night. Winds die down below 20 knots by late Wednesday
morning and remain that way into at least Thursday morning. A storm
system moving across the area could bring an increase in winds late
Thursday into Friday, but the strongest winds will likely occur on
Saturday when colder air advects in behind the system creating more
unstable conditions along with gusty north to northwest winds to at
least 30 knots.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&

$$

SHORT TERM...JLB
LONG TERM...JP
AVIATION...07
MARINE...Voss




Area Forecast Discussion

National Weather Service Pocatello ID

 846 PM MST Mon Jan 11 2021

.UPDATE...

Updated low temps tonight based on evening trends.

13

&&

.PREV DISCUSSION... /issued 145 PM MST Mon Jan 11 2021/

SHORT TERM...Tonight through Wed night. Next 24 hours or so from
this afternoon should be quiet with continued cool temperatures
and nearly calm wind. Main issue would be the potential for
isolated freezing fog issues laying down ice on road surfaces. By
Tuesday afternoon, a very wet, warm, and windy winter storm is
expected to enter the western zones, and slowly spread eastward,
reaching the Wyoming border later Tue night. This is very warm
subtropical air and snow levels along the Utah border will soar to
8000ft elevation, and even 7000ft in the central Idaho mountains.
The eastern Magic Valley will see warming temperatures during the
overnight on Tue night, and should stay above freezing. As long as
that happens, the risk of freezing rain due to the elevated warm
layer is very low. But if the temperatures there cool to below
freezing, the risk spikes upward. Snow will develop at first even
in the Snake River plain, but during Wed afternoon the rain-snow
line will rise in elevation there, not quite getting to the
7000-foot elevation. Temperatures on Wed will reach 40 degrees
even at Idaho Falls, and will be around 50 in the Burley area, so
the snow at lower elevations will not linger and will not
accumulate to much. Temperatures come crashing down Wed night as
a northerly wind kicks in. This large temperature difference is
indicative of a strong cold front that comes in from the north
and northwest. This will bring 20 to 30 mph wind with stronger
gusts during the day Wed, mainly in the Snake River plain and
along the ridges of the central Idaho mountains. With the mild
air, the snow will be heavy and would expect some avalanche
concerns, but that will be determined by avalanche experts as the
storm approaches.

Messick

LONG TERM...Thursday through next Monday. Cool, dry and breezy
northwest flow is expected to be in place across the region behind
our departing system. A ridge of high pressure will then briefly
settle over the region Friday morning, bringing lighter winds and a
continuation of dry conditions. A weak but strengthening area of low
pressure is then seen swinging through the region Friday afternoon
through Saturday morning. Like so many of our systems this winter,
this one will be relatively moisture-starved, and snow showers
associated with the system will be confined to primarily higher
terrain areas. Given the relative lack of moisture and relatively
fast forward motion of this system, amounts should be confined to an
inch or two (with locally higher amounts) across higher terrain
areas. Locally breezy conditions are expected with this system as
well. Cool, dry and breezy northwest flow will then return to the
area late Saturday and early Sunday. Another system is then expected
to move through the region late Sunday to early Monday. This system
is nearly an identical copy of the Friday afternoon-Saturday morning
system, with a nearly identical track and strength. Expect another
round of mainly light, high elevation snow showers and locally
breezy conditions with this system before dry conditions return
later Monday. Global models and ensembles are all in excellent
agreement, thus forecaster confidence is fairly high through the
long-term forecast period at this point.

AD

AVIATION...Central and eastern Idaho remains within the relative
calm before the storm through the end of the forecast period at 18Z
Tuesday, when an incoming storm system and its associated
precipitation will be on the doorstep. Until then, relatively benign
conditions are expected. Fog and stratus is once again a concern
tonight, and some combination of both are possible at KDIJ and KIDA.
Have included fog at KDIJ starting at 03Z and 09Z at KIDA based on
3km NAM, HRRR and NBM trends. IFR and LIFR conditions are possible.
However, confidence is typically low on fog/stratus trends.
Southerly winds begin to increase just above the boundary layer
tonight after 06Z, but fall just short of LLWS criteria through the
end of the period, with winds forecast to remain largely in the 15-
20kt range in the 1kt-2kt ft layer. After any lingering stratus/fog
burn off after mid-morning, thickening/lowering clouds will be on
the increase from the west, with precipitation onset at KSUN
expected Tuesday evening. At this time, outside of fog/stratus
concerns, VFR conditions are expected through 18Z Tue.

AD

&&

.PIH WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from 11 AM Tuesday to 5 PM MST Wednesday
for IDZ072-073.

&&

$$