Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/08/21

Area Forecast Discussion

National Weather Service Gaylord MI

 650 PM EST Tue Dec 7 2021

.NEAR TERM...(Through Tonight)
Issued at 343 PM EST Tue Dec 7 2021

...Lake effect snow reinvigorates tonight...

High Impact Weather Potential: Moderate. Accumulating lake
effect/enhanced snow nw lower MI.

High pressure is crossing southern IN/OH. 1013mb low pressure is
over nw IA. This low will approach southern Lake MI by morning,
though this low will tend to fill overnight, as cyclogenesis
proceeds over northern MI. An initial, weak shortwave pushes from
southern MN to central lower MI tonight, but a stronger wave digs
across Superior tonight. The surface low reorganizes further north
in response to that.

A small area of synoptically-driven will continue eastward, just
north of the original surface low. This would track into central
lower MI late evening/overnight, tending to diminish with time as
the original low deteriorates. The synoptic component to snowfall
tonight will be negligible. But the low levels are abundantly cold
(widespread temps in the teens) and potentially unstable. Lake
effect snow should see a considerable resurgence with the added
moisture, and a rather long sw fetch on Lake MI. 850mb temps of -13
to -15C will provide abundant instability, and a respectable DGZ
(and at times max omega within it) to promote fluffier snowfall and
higher snow-liquid ratios. Sw flow holds for most of the night, only
veering w-nw over Lake MI toward 12Z.

Have adjusted QPF and snow ratios higher. How much higher? Well,
multiple runs of the HRRR have generated over an inch of liquid QPF
on a small part of Emmet Co tonight. The HRRR is likely in general
overdone, but sw flow events do get excessively exuberant on
occasion over the tip of the mitt. Do have a small area of Emmet Co,
between Harbor Spgs and Cross Village, getting up to 8" of fluffy
snow tonight. Without much wind, and with a largely nocturnal event,
a warning does not appear necessary.

Have expanded the advisory a touch this afternoon, to include
Charlevoix Co (where healthy snow is expected along the coast,
including in the city of Charlevoix). Cheboygan Co was also added,
though this was a tougher call; heavier snow amounts should only be
in a small portion of nw Cheboygan Co, west of the city of
Cheboygan. But this includes a decent stretch of I-75, and have
elected to include largely for that reason.

With increasing cloud cover, and low-level warm advection, temps
won`t get an opportunity to fall too much. Mins will be mainly in
single digits above zero in eastern upper MI, and in the lower to
middle teens in northern lower.

&&

.SHORT TERM...(Wednesday through Friday)
Issued at 343 PM EST Tue Dec 7 2021

High Impact Weather Potential: System snow Thursday with
precipitation-type issues Thursday night...additional system later
Friday.

Pattern Synopsis/Forecast:

Morning surface analysis shows broad high pressure across the
eastern CONUS...though Lake Aggregate troughing holds on across
Northern Michigan, resulting in lingering lake effect snow here.
Next system upstream is located over southeast South
Dakota...associated with a trough axis aloft extending from
Minnesota southwestward into the Lee of the Rockies. Thermal
boundary at the surface is analyzed from this system back into
southern Montana towards the Oregon/Washington coast. Thermal
gradient aloft is tightening across Alberta this morning as ridging
moves onshore...resulting in a stationary boundary analyzed over
this same area...with a resultant upper level jet max as well, which
will feed into the troughing across the central CONUS.

By Wednesday morning...will look for trough axis to have moved
nearly overhead...and continue to swing through through the
remainder of the day. Ridging will be quick to move in behind
it...ahead of a southern stream shortwave taking shape across the
central/southern Rockies, with a resultant surface low ahead of it.
This niblet will head northeastward along the flow...affecting us
Thursday. Flow will amplify across the CONUS...as well as upstream
over the Pacific...going through the day Friday. This will result in
a deeper and more organized trough axis across the western central
CONUS by late Friday...with another deep trough diving toward the
Pacific coast of North America for the end of the short term...and
beginning of the extended.

Primary Forecast Concerns: Lingering snowfall Wednesday...return of
snow and precipitation type issues Thursday?...ditto for
Friday...gusty winds late week as well...

By Wednesday morning...trough axis aloft should be poised just to
our west/northwest...swinging across the CWA through the day...and
taking much of any remaining mid-level moisture along with it. Will
look for the surface reflection to be ahead of the trough axis
aloft...with fropa likely taking place during the morning hours,
resulting in NW flow behind the system. Would look for a potential
band of snow to precede the front, given some potential upper level
support along/ahead of the trough aloft...though the strongest
signals for snow will remain across northwest Lower Wednesday
morning. Currently doesn`t look like there`ll be a ton of wind with
this (thankfully), which should help keep any lingering lake effect
behind the system closer to shore. Does appear that inversion
heights fall through the day as we lose mid-level moisture...but,
like trying to brake in the snow...it will take longer to put the
stop on the lake effect machine than we may expect. Guidance points
toward some potential NW flow convergence across Eastern Upper
through the day...which is something we`ll have to keep an eye on,
particularly with somewhat better instability up that way.

Once surface high pressure passes by Wednesday night (which could
result in a chilly night for some areas that stay clear to mostly
clear with lighter winds...), will look for southerly flow to return
and strengthen for Thursday ahead of the next system, related to a
couple niblets of energy in the flow ahead of larger-scale troughing
across the western/central CONUS. As deeper moisture returns to the
Great Lakes ahead of this system on strong southerly flow...will
look for some warm advection precip to spread into the area ahead of
a weakening surface low in broader surface troughing extending
northward to a surface low in central Manitoba. This surface
trough/cold front will swing through Thursday into Thursday night
...lending to additional synoptic support for precip...in
combination with an approaching upper level jet max. Attm...deepest
moisture looks to be a little further north with this system, closer
to the UP and Tip of the Mitt...but will have to watch this in the
next day or two to see if anything changes. Looks like this will
likely be focused later in the afternoon into early Thursday night,
with guidance perhaps a touch quicker than previously. With warm
advection comes potential for p-type issues...so will have to keep
an eye on that as well. Additionally...with the warm advection
aloft...and a deep mid-level dry layer Thursday evening/night, but
saturated low levels possible up to around 850mb...may have some
freezing drizzle concerns to contend with.

Going into Friday...the column begins to saturate again from the top
down ahead of a more substantial system developing out in the
central/southern Plains. This will remain a tricky forecast...as
guidance continues to track this system through the Great Lakes,
though recent model trends seem to indicate a further south and east
track. This suggests we may have more frozen/mixy crud to deal with,
as opposed to the primarily rain situation we`d have if it were
further north...though there is still a fair amount of uncertainty
in the exact track and timing attm. Will have to watch this
closely...as it will bring a conglomeration of potential impacts to
the area...including mixed precip and gusty winds, in addition to
higher-moisture-content synoptic snow...all of which will be
dependent on where the system tracks. Currently...may be dealing
with a bit of a calm-before-the-storm situation early Friday...with
the biggest impacts perhaps holding off till later in the
day/evening...but will have to see how timing trends play out in the
coming model runs.

.LONG TERM...(Friday night through Tuesday)
Issued at 343 PM EST Tue Dec 7 2021

High Impact Weather Potential: Moderate...potential system Friday
night into Saturday...

Pattern Synopsis/Forecast:

Aforementioned deep and organized trough axis will swing across the
central CONUS Saturday...with a strong upper level jet max ahead of
it. Synoptic moisture will advect in from the south on Friday night
into Saturday ahead of the surface low. An abundance of upper level
support looks to be in play with this system...as a strong upper
level jet passes through the flow. As mentioned above, at the end of
the short term...will have to keep an eye out for some p-type
issues, as warm advection should cause us to flirt with some warmer
temps aloft. Either way, it should be rather unpleasant Friday night
into Saturday. As we get in behind the system on Saturday night into
Sunday, with some wraparound moisture on the backside of the
system...and some colder air aloft moving in...will look for lake
effect potential to return to Northern Michigan.

Beyond Saturday...will be watching the pattern turn more ridgy
across the CONUS/eastern CONUS going into the start of next week.
May have to watch out for some niblets trying to pass through the
flow at times, with some uncertainty in how strong the ridge will
ultimately end up being. That being said...temperatures will
probably become the main story going forward, unless signals dampen
in the next few days.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 646 PM EST Tue Dec 7 2021

Lake enhanced snow will continue to increase at PLN, MBL and TVC
overnight into Wednesday morning before waning by afternoon.
Cigs/Vsbys will be mainly MVFR but IFR vsbys are possible at
times. At APN only a few flurries are expected. Generally low end
VFR cigs/vsbys are then expected Wednesday afternoon. Winds will
be light and variable through early Wednesday then pick up and be
a bit gusty out of the northwest Wednesday morning and afternoon.

&&

.MARINE...
Issued at 343 PM EST Tue Dec 7 2021

High pressure is passing to our south today, with winds decreasing
somewhat as they back toward the sw. Sw winds linger into tonight,
though will start to veer nw toward morning, as low pressure
develops over northern MI. Relatively light nw to w breezes hold
for Thursday and Thu night.


&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...WINTER WEATHER ADVISORY until noon EST Wednesday for MIZ016-017-
     020-025-031-099.
LH...NONE.
LM...NONE.
LS...SMALL CRAFT ADVISORY until 5 AM EST Wednesday for LSZ321.
&&

$$

NEAR TERM...JZ
SHORT TERM...FEF
LONG TERM...FEF
AVIATION...AS
MARINE...JZ



Area Forecast Discussion

National Weather Service Goodland KS

 313 PM MST Tue Dec 7 2021

.SHORT TERM...(This evening through Thursday)
Issued at 215 PM MST Tue Dec 7 2021

At the beginning of the short term period, current RAP analysis
shows the CWA having a west-northwesterly flow aloft while there is
an upper air ridge over the Pacific Northwest and an upper air low
just off the coast of central CA. By tonight, the front part of the
ridge is expect to make it over the CWA turning the flow over the
CWA north-northwesterly overnight. At the surface, dry conditions
look to continue across the CWA. Winds look to be light and variable
through the remainder of the afternoon and turn southerly at 5 to 10
mph by the evening hours before transitioning to more west-
southwesterly overnight. Daytime temperatures do not expect to pass
over the 50 degree mark before beginning to cool with overnight lows
between the upper teens and lower 20s.

On Wednesday, the ridge makes it over the CWA during the day while
the aforementioned upper air low opens up into a trough in the
southwestern CONUS. By the evening hours, the trough is expected to
weaken while moving towards the CWA turning the flow aloft
southwesterly. Overnight, models show a zonal upper air flow looks
over the CWA. At the surface, dry conditions continue while a lee
surface trough is expected to develop over the Front Range due to
the pattern aloft that moves through the CWA during the evening
hours. With this surface feature, winds on Wednesday expect to blow
from the south at around 15 to 20 mph with gusts up to 30 mph
possible during the day. Winds expect to slow to 5 to 10 mph and
turn westerly late by the evening hours. Daytime high temperatures
on Wednesday expect to range between the middle 50s and the lower
60s with overnight lows in the middle 20s to lower 30s.

For Thursday, the next weather maker for the area starts to develop
thanks to an upper air trough in the Pacific Northwest. Models show
this trough strengthening and moving eastward throughout the day
with its front part reaching over the CWA late Thursday turning the
flow aloft southwesterly again. At the surface, models show a
surface low developing in central CO during the day with this
pattern aloft and slowly moving eastward over the CO/KS border by
Thursday night. As mentioned in the previous short-term forecast
discussion, models still continue to show most of the CWA in the
warm sector of the system overnight though the position of the low
looks to have moved slightly southward. With this setup,
northwestern Yuma county looks to see a slight chance for light rain
in the evening. This precipitation expects to transition to light
snow and increase in coverage to most of Yuma county along with
portions of the NE counties overnight which might be the start of a
possible winter event for the CWA that goes into the beginning of
the long term forecast period. Daytime highs on Thursday expect to
range between the middle 50s and the lower 60s followed by overnight
lows in the upper teens to lower 30s.

.LONG TERM...(Friday through Tuesday)
Issued at 220 PM MST Tue Dec 7 2021

Friday...GEFS/GFS/ECMWF models remain in pretty good agreement
bringing an upper level trough across the area during the day,
moving east and away from the area during the night. At the
surface, low pressure over southwest Kansas in the morning moves
east into the Wichita area during the afternoon, reaching the
Kansas City area by days end. Behind the surface low, a 1024mb
surface moves into the area from the west.

North winds gusting up to 35 mph or so are expected during the day
with steadily decreasing winds during the night as the pressure
gradient relaxes.

The latest model runs have lowered the high temperatures compared to
12 hours ago with lower 30s to lower 40s currently expected.
Blending the various 2m temperatures and MOS guidance numbers
suggests that the current high temperature forecast may be a few
degrees too high so further refinements may be needed. Low
temperatures are expected to fall into the single digits to lower
teens above zero in far eastern Colorado to the upper teens near
Hill City.

Regarding precipitation chances, the latest model trends have
increased pops across all but the extreme east and southern parts of
the forecast area (Hill City to Tribune south) as wraparound rain
and snow looks more promising in the morning. Chances decrease some
and include the entire forecast area in the afternoon with dry
conditions expected during the night as the storm moves away from
the area. At this time, snowfall amounts of a trace to an inch are
expected from Cheyenne Wells to Norton northward, highest across
Yuma county to McCook.

The combination of snow and north winds gusting to 35 mph will
likely produce some reduced visibilities at times with the highest
chance along the KS/NE border during the day.

Given that we`re still 72 to 84 hours out from this "event" and that
the storm system itself has yet to develop further refinements to
the forecast area likely.

Saturday...broad upper level ridging redevelops over the area with
high temperatures in the upper 30s to upper 40s and low temperatures
in the middle teens to lower 20s. Breezy west to southwest winds are
possible during the day, mainly across far eastern Colorado. If
snowfall amounts from Fridays storm are higher, its likely that high
temperatures for Saturday will need to be adjusted down due to snow
cover.

Sunday...high temperatures continue to warm with middle 50s to
around 60 expected. Low temperatures are currently forecast to be in
the upper teens to lower 20s.

Monday...upper level heights slowly rise ahead of a developing upper
level trough off the west coast. High temperatures are expected to
be in the middle 50s to around 60 with low temperatures in the
lower 20s to near 30.

Tuesday...the forecast area is under southwest flow aloft ahead of
the west coast upper trough which is forecast to move ashore.
GFS/ECMWF/GEM 850mb temperatures are forecast to be in the 15C to
17C range which should easily support the current forecast of lower
to upper 60s. Given typical mixing at 850mb these forecast highs
could be several degrees on the cool side with highs in the 70s very
possible.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 305 PM MST Tue Dec 7 2021

Both KGLD and KMCK expect to see VFR conditions throughout the 00Z
TAF period. KGLD starts with southerly winds around 7 kts that
become westerly around 12 kts at 02Z before slowing to around 7
kts again at 10Z. By 17Z, KGLD winds turn southwesterly and then
return to southerly when they speed up to 13G21 kts at 18Z. The
KMCK terminal sees south-southeasterly winds around 6 kts to
begin the 00Z TAF period that turn southwesterly by 07Z. At 08Z,
KMCK winds expect to become light and variable until 16Z when
they become southerly again around 7 kts. By 20Z, winds at KMCK
speed up to 13G20 kts for the remainder of the period.

&&

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

$$

SHORT TERM...076
LONG TERM...99
AVIATION...076