Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 02/05/22
Area Forecast Discussion
National Weather Service Gaylord MI
925 PM EST Fri Feb 4 2022
Issued at 925 PM EST Fri Feb 4 2022
Sharp upper level trough axis and weak surface reflection has
reached Lake Michigan late this evening. With very little moisture
to work with...only synoptic precip being produced by this system
is very light snow showers/flurries across much of our CWA.
Persistent mid Lake Michigan snow band is trying to push onshore
across portions of our Lake Michigan shoreline around FKS and MBL
as expected...but onshore push is being limited by the opposing
land breeze. Expect this will remain the case as we head into the
overnight hours. Expect majority of any accumulating snow will be
limited to just these shoreline areas from FKS to MBL...with the
rest of our CWA only receiving a dusting of new snow. Certainly
expect another very cold night...but not as cold as last night.
Overnight lows will fall into the single digits above and below
.NEAR TERM...(Through Tonight)
Issued at 336 PM EST Fri Feb 4 2022
...Still cold, but not as cold as last night...
High Impact Weather Potential...Minor. Cold temps/wind chills.
Light snow accums parts of nw lower MI.
A poorly defined 1026mb clipper low is over sw WI. The parent
forcing shortwave is fairly vigorous, but broader MSLP across the
region is quite high, and moisture availability is poor. Snow
shower activity over ne WI has increased, as forcing moves in over
residual lake effect processes in earlier ne low-level flow. There
is a brief transition to weak sw to w 1000-850mb this afternoon
and early evening, before convoluted and still light northerly
flow returns by overnight. Main precip concern is whether lake
effect banding can push onshore into nw lower MI. Temps/wind
chills are the primary concern for most places.
Stronger Lake MI lake effect band is evident on visible sat this
afternoon, seen thru a thin veil of higher clouds. This band is
slowly pressing eastward, and our low-level flow will remain weak
enough for only slow motion to continue. As it gets closer to nw
lower MI, the band will encounter a land breeze. This is at a
relative minimum this afternoon, as land surface temps have
`warmed` into the upper teens. As we move past peak diurnal
heating, the land breeze circulation will strengthen as temps cool
over land. There is probably a window this evening for some
stronger snow showers to reach coastal Manistee Co, and perhaps as
far north as the Dunes and Manitous. Will have 1-2" accums along
the coast in these areas, highest near MBL. Think that by late
evening/overnight, an increasingly dominant land breeze will push
and keep the stronger band offshore. Recent HRRR runs largely jive
with the above thinking.
Cloud cover will initially be fairly extensive, though thin, with
cirrostratus and some mid clouds. As the clipper digs se-ward, and
northerly low-level flow returns, we will see partial clearing
work in from the north toward midnight. Eastern upper and ne lower
MI will see a period of mostly clear skies overnight (though lake
clouds from Superior will spill back into eastern upper very
late). This will contribute to cold temps again tonight, though
not as much as last night. Mins will range from zero to 10 below
in eastern upper, n central and ne lower MI. Single digits above
zero in nw lower MI. Wind chills reach the mid minus teens in
parts of eastern upper MI.
.SHORT TERM...(Saturday through Monday)
Issued at 336 PM EST Fri Feb 4 2022
High Impact Weather Potential: Accumulating snow in eastern Upper
Saturday afternoon/night...potential freezing drizzle across
northern Lower late Saturday night into Sunday...
Last 24-48hrs has seen the upper level jet max depart the region up
the SW-NE oriented flow as trough axis slides into the Great Lakes
today...leaving Michigan under the left entrance region of the
jet...typically favored for upper level convergence, sinking motion,
and surface high pressure...which resulted in the bitterly cold lows
last night across the area. Upstream...another strong (140+kt) upper-
level jet max is riding the height/thermal gradient on the
downstream side of ridging progressing eastward into the western
Plains. A stronger shortwave crossing into British Columbia is
temporarily smooshing the prevailing western ridge...but it is on
the rebound behind it. Otherwise...a niblet of energy has
disconnected from the flow and is dropping southward along the
Shortwave dropping into the Upper Midwest is resulting in some mid-
level moisture and a surface response (1028mb low) zipping
southeastward across the Upper Mississippi Valley...through broad
areas of ~1040mb surface high pressure attempting to control much of
the northern and central CONUS. Stationary boundary extends
northwestward into Alberta (where else?? Seems like it`s been there
forever now...) from this surface low, along the baroclinic zone
aloft there...as another area of ~1040mb surface high pressure
slides southeastward into the central Canadian Prairies/northern
Plains...upstream from the area of cold and dry surface high
pressure that moved through last night. This extremely cold and dry
airmass overwhelming the Great Lakes results in lake aggregate
effects showing up on the surface analysis, as latent heating from
the lakes results in a hydrostatically lowered pressure overhead.
(This is slightly harder to see now that the clipper system is
dropping in.) Baroclinic zone across the southeastern US as trough
axis swings into the Great Lakes today results in a continuation of
the SW-NE oriented surface boundary and low pressure slowly trekking
eastward through the Appalachians this morning...taking the bulk of
the moisture along with it.
Going forward...will look for trough axis to swing through the Great
Lakes today/tonight...with a brief ridge moving in ahead of the next
shortwave niblet diving into the flow with a strengthening jet max
moving in as well. As this niblet moves into the Great Lakes
Saturday night into Sunday...ridge across the west coast will
rebound...allowing troughing to take hold of the central CONUS for a
time. However...additional niblets getting underhand-pitched up the
flow by the general area of upper level low heights over the western
Pacific will again shift suppress/shift the ridge eastward going
into Sunday and Monday. This will force the trough axis through the
Great Lakes going into Monday...as the next upstream niblet chugs
through the Canadian Prairies/Northern Plains early next week.
Primary Forecast Concerns: Winds Saturday and Saturday night...Snow
potential Saturday through the period...freezing drizzle potential
later Saturday night into Sunday...
Warm advection will commence Saturday as low-level winds become more
southerly with time, veering with height. Pressure gradient will
tighten as well...suggesting that sustained winds will be a bit
stronger through the period. If we mix up to 925mb...could be
looking at gales along the Lake Michigan coastline...as there are
signals for stronger winds even up at that level off the deck...so
will have to keep that in mind for our Lake Michigan zones (which
will be where better mixing would be expected anyway). Even
so...with somewhat stronger southerly surface winds in play Saturday
night...could be looking at some blowing snow concerns along US-2 in
Mackinac county, as snow gets blown off the ice cover up there in
northern Lake Michigan. Weakening pressure gradient Sunday will
result in decreasing winds with time.
Saturday...as jet max moves through the flow...it may briefly
support some upward forcing with left exit quadrant dynamics in
play...though it doesn`t appear overly strong attm. Best forcing
aloft appears to be attributable to the shortwave itself as it comes
on scene later Saturday night...with niblets of energy passing by to
our southwest. There may be some low-level convergence across
southern Mackinac county early on Saturday morning...apparently
largely attributable to mesoscale factors...so may have to keep an
eye on that, perhaps even for our Lake Michigan coastline a little
further south (though nothing overly impressive noted attm).
Otherwise...as flow becomes more southwesterly and then southerly
with time...will look for better boundary layer convergence across
the central UP, with a long fetch over a majority of the length of
Lake Michigan. These signals only grow stronger with time Saturday
evening ahead of the surface system, waning to some degree through
the remainder of the night. Winds appear to become slightly more
southwesterly with time Saturday night into early Sunday
morning...which should shift the position of the band eastward with
time through the night, and lead to some potentially higher snowfall
totals in the Tip of the Mitt for early Sunday. The shifting winds
may help mitigate snowfall totals to some degree...as we`ll be more
evenly watering the garden, as opposed to putting a firehose on the
garden all night Saturday night.
Mid-level moisture begins to spread into the region through the
afternoon Saturday into Saturday night...and do see a response in
boundary layer moisture with time as well...likely mainly in the way
of warm advection processes as top down saturation occurs (aided in
S flow areas by existing boundary layer moisture leading to seeder
feeder processes). Over-lake instability appears greatest during the
daylight hours Saturday into early Saturday night...waning with time
as temperatures aloft rise (thanks to warm advection). That being
said...925mb temps look to remain around -8 to -10C for much of the
northern half of Lake Michigan going into early Sunday morning, with
even warmer temps approaching from the south by then, which may help
shut the lake off for a time. Given that overlake instability will
still be decent at the same time as deeper moisture and excellent
low-level convergence will be in play...Saturday afternoon and
particularly evening should see the highest snowfall rates and
totals. Noting continued signals, per model-derived guidance, for
upward motion pegged in a reasonably deep isothermal layer in the
DGZ...snowfall rates and snow-to-liquid ratios (SLRs) could be
rather impressive at times Saturday evening. (This, combined with
the aforementioned stronger winds off Lake Michigan could make
travel rather difficult for parts of US-2 along the coast in
Mackinac county later Saturday into Saturday night.)
Do note some signals that mid-level moisture may hold on a little
firmer into Sunday than previous guidance had suggested...which may
help mitigate the idea of freezing drizzle to some extent. That
being said...there are still signals, particularly in model derived
soundings, of some boundary layer moisture with cloud top
temperatures around -10C or perhaps warmer. -10C is typically a
lower/warmer bound for ice nuclei activation...though some ice
nuclei may become activated at warmer temps than this. (And we have
basically almost zero idea of what kind of ice nuclei are up there
to know whether or not they`ll become activated and produce cloud
ice vs. staying supercooled liquid droplets... the temperature
thresholds are more of a probability of cloud ice thing, with higher
probabilities of seeing cloud ice the colder your clouds are.) For
the most part, looks like forcing in this layer should be relatively
minimal late Saturday night into Sunday...but any sort of lift could
produce freezing drizzle (such as upslope flow, which could be a
problem for the interior higher terrain with south/southwesterly
flow). Looks like the best chance for this freezing drizzle crud to
take place will be very late Saturday night into Sunday morning into
part of Sunday...until we get a little deeper moisture to colder
temperatures aloft as the trough axis approaches and slides through,
dragging better moisture aloft (as well as cooler temperatures
aloft) along with it...supportive of a transition back to snow.
Areas across eastern Upper and perhaps the Tip of the Mitt may
remain all snow through the period...though there are some signals
they may flirt with cloud top temps of -10C as well at times into
Sunday. Definitely something to keep an eye on...as temps will be
warmer, but are not overly likely to break the freezing mark.
Otherwise...looks like snow potential should continue on into Sunday
night until the better moisture departs aloft going into Monday...
with 850mb temps dropping Sunday night behind the slow-moving
front/trough aloft...supportive of a) a potential uptick again in
widespread snowfall as the trough moves in (increasing
convergence/lift in areas of moisture), and b) perhaps some lake
effect snow potential behind the system into Monday. Winds becoming
more northerly with time Monday suggests any lake bands will
ultimately shift more offshore through the day. May still see some
kind of west/northwest flow lake effect through the night Sunday
into early Monday.
.LONG TERM...(Monday night through Friday)
Issued at 336 PM EST Fri Feb 4 2022
High Impact Weather Potential: Minimal attm.
A fair bit of uncertainty comes into the fray for the start of the
extended...as guidance isn`t quite sure how to handle that niblet
moving through the Northern Plains/Canadian Prairies. A more
coherent solution would lead to a stronger surface system with more
warm advection ahead of it...whereas as a more out-of-phase,
slightly more nebulous solution for troughing in the northern stream
may not be quite as dramatic. Either way, there are still signals
for troughing to return to the center of the country for a time
toward the middle of next week. There is additional uncertainty with
this, too...as basically the same idea remains -- a more coherent
and unified trough would allow for more direct cold advection into
the northern US...whereas a less unified trough would be a little
more like partially blocking the firehose of cold air. Will have to
keep an eye on this going forward.
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 611 PM EST Fri Feb 4 2022
Sharp upper level trough axis and weak surface reflection will
swing thru Michigan this evening. Do not expect much in the way of
synoptic snow...but weak low level flow will shift to west...which
will likely push mid lake snow bands over Lake Michigan into
portions of NW Lower Michigan tonight into Saturday morning...
mainly around TVC and MBL. Conditions will drop to MVFR/IFR within
some of these snow bands. More widespread snow will begin to
develop from NW to SE Saturday afternoon ahead of a developing low
pressure system moving out of the Northern Plains and into the
Western Great Lakes. Again...mainly MVFR/IFR conditions are
expected as this snow develops. Light/variable winds tonight into
Saturday morning will become southerly at around 10 kts by
Saturday afternoon ahead of that system.
Issued at 336 PM EST Fri Feb 4 2022
Light winds remain in place into early Saturday, as a weak clipper
crosses the southern lakes. S to sw winds will ramp up
considerably on Saturday, and gales are a distinct possibility on
Lake MI for part of Sat evening.
LM...GALE WATCH from Saturday evening through late Saturday night for
Area Forecast Discussion
National Weather Service Green Bay WI
955 PM CST Fri Feb 4 2022
Updated aviation portion for 06Z TAF issuance
Issued at 246 PM CST Fri Feb 4 2022
Light snow ending this evening, then another round of light snow
possible Saturday into Saturday evening, mainly across the north.
Temperatures stabilizing at near-to-above-normal levels.
The fairly persistent strong ridging near the west coast of North
America will flatten significantly as Pacific jet energy breaks
through the ridge and sweeps east across the continent. This will
will result in at least a temporary break in the flow of cold air
from high latitudes into the northern CONUS. Temperatures will
still undergo daily swings with the passage of individual weather
systems, but should be above normal most of the time after
tomorrow. The new pattern still looks unfavorable for significant
precipitation, so below normal amounts expected for the next week.
.SHORT TERM...Tonight and Saturday
Issued at 246 PM CST Fri Feb 4 2022
The latest RAP analysis and satellite/radar imagery show a digging
shortwave and associated surface trough passing across the
northern Mississippi Valley early this afternoon. Light snow has
been gradually spreading east across northeast Wisconsin ahead of
the shortwave. Meanwhile, a robust mid-lake snow band moved into
northern Door county from northern Lake Michigan, briefly
dropping visibilities at Ephraim to 1/4 mile. Looking upstream,
the next clipper is moving into the Pacific northwest and poised
to impact the region tomorrow. Forecast concerns mainly revolve
around snow chances/trends followed by min temps tonight.
Tonight...Light snow will be ending early in the evening across
northeast Wisconsin as the shortwave trough axis shifts into
northern Lake Michigan. Little to no additional accumulations are
expected. Models appear to be a little too aggressive with the
cloud cover tonight based on current satellite imagery, so think a
several hour period of clearing will occur before high and mid
clouds return late. As a result, remained on the cold side of
the temperature guidance, particularly at the cold spots over the
northwoods. Lows ranging from the mid teens below zero at Tomahawk
to near 0 along the Lake Michigan shoreline.
Saturday...The next clipper will rapidly move into Minnesota by
the end of the afternoon. Models insist on a fgen band developing
over far northern wisconsin by late morning before translating
east to Door county in the afternoon. This area may be a little
further north than previous forecasts, and shifted the highest
chances north somewhat. Accumulations still look like 1-2 inches
near the U.P. border will be possible, and up to an inch south of
a Arbor Vitae to Wausaukee line. South winds will become breezy
in the afternoon with gusts to 30 mph. Temperatures will rebound
into the mid teens north to the low 20s south.
.LONG TERM...Saturday Night Through Friday
Issued at 246 PM CST Fri Feb 4 2022
Fairly quiet weather is expected throughout the long-term portion
of the forecast. There will be at least a few light precipitation
events, but the timing of those is nearly impossible to pin down
after Saturday evening due to the increasingly zonal flow.
The medium range model ensembles had been fairly consistent in
showing a consolidation/re-amplification of the eastern Pacific
ridge by the end of next week. There is still some support for
that in the latest runs, but it has lessened considerably from
what it was a few days ago. So the longer range temperature trends
are now more uncertain, and it`s hard to even estimate when the
next substantial precipitation event will affect the area.
.AVIATION...for 06Z TAF Issuance
Issued at 949 PM CST Fri Feb 4 2022
High/mid clouds will return overnight into Saturday morning, with
IFR conditions developing across far northern WI as light to
occasionally moderate snow overspreads the area in the late
morning and afternoon hours. Light snow will likely persist into
the evening hours. The RHI TAF site will be most affected by the
snow, though AUW and CWA may see a brief period of light snow
around midday, and other locations may see some flurries in the
Light and variable winds are expected overnight, followed by
gusty south winds Saturday afternoon and evening. A period of LLWS
may occur at some of the TAF sites Saturday evening.
Area Forecast Discussion
National Weather Service Indianapolis IN
1034 PM EST Fri Feb 4 2022
...Updated Aviation Discussion...
Issued at 921 PM EST Fri Feb 4 2022
Had to make quite a bit of changes for the rest of the night. Ramped
up cloud cover and slowed down clearing from west to east based on
obs and satellite trends. This necessitates raising temperatures a
few degrees overnight and matches better with our neighbor offices.
Even so, temperatures will bottom out near zero and wind chills will
be below zero.
The next change was to bring in light snow or flurries to
northern sections based on recent obs, radar returns and HRRR
soundings. Lafayette, Kokomo, Frankfort and Crawfordsville were all
currently reporting light snow or flurries. Judging by the quick
movement, lack of deep moisture and radar echo strength, little or
no accumulation is expected.
.Short Term...(This evening through Saturday night)
Issued at 212 PM EST Fri Feb 4 2022
* Cold temperatures this weekend
* Wind chill values below zero tonight.
Surface analysis early this afternoon shows a strong ridge of high
pressure stretching from the southern plains to lower
Michigan...providing a cold NW surface flow across Central Indiana.
A weak area of low pressure was found over western WI with a
trailing cold front across IA to NB. GOES16 shows high clouds
drifting east across Indiana with clearing skies found upstream
under the ridge axis over MO and IA. Radar shows any lingering
flurries have exited the area to the east.
At this time...no wind chill advisory appears to be needed as winds
are expected to remain near 5knts or less overnight...producing wind
chill values in the 0 to -10F range. Will adjust as needed if winds
end up being stronger than anticipated.
The surface ridge is expected to push east of Indiana along with a
deep trailing trough within the flow aloft. This will allow winds to
become more westerly overnight. This westerly flow riding over the
cold air in place at the surface will lead to stratocu formation
overnight as forecast soundings hint at lower level saturation this
evening and early overnight. Still with fresh snow in place across
the area along with 850mb temps near -16 and light winds a cold
night is ahead. Forecast soundings show the arrival of startocu this
evening but clear it out after 09Z...allowing for a few hours of
radiational cooling. Thus will trend toward a mostly cloudy evening
with decreasing clouds overnight. Given the previously mentioned
features in play...will trend lows at or below the NBM.
Saturday and Saturday night...
Models suggest mainly zonal flow in place on Saturday and Saturday
Night with little in the way of forcing dynamics available. Weak
ridging appears to push across Indiana within the mid levels with
subsidence as a weak low pushes across Ontario...well north of
Indiana. Within the lower levels...warm air advection begins on
Saturday as the cold air previously in place begins to exit
east...and by Saturday night a warm front associated with the low to
the north is suggested to push across Indiana. This will allow 850mb
temps to rise to -2C by Sunday morning. Forecast soundings through
the Saturday and Saturday night remain dry...suggesting subsidence.
Again...given the fresh snow and still cold air in place...will
trend highs and lows at or below the NBM.
.Long Term...(Sunday through Friday)
Issued at 212 PM EST Fri Feb 4 2022
-- CAA with NW flow and building high pressure will lead to a dry
and chilly to start next week
-- Weak clipper system possible late next week, providing small
chances for precipitation and slightly warmer temperatures.
A persistent ridge over the US west coast will keep the mean
steering flow out of the NW for the Ohio Valle through the long
term. However, meridional influences will keep conditions fluctuating
every couple of days. To begin the long term, a weak low level wave
will be exiting, with moderate CAA in its wake. This will drop
temperatures below normal once again for Sunday and Monday with
highs in the mid 30s to mid 20s. With strong subsidence in the low
levels, any cloud cover will be in the upper levels, with no
Shifting to mid-week, a low amplitude disturbance will approach the
upper Midwest, shifting the low level flow towards the SW. This
should create a pattern conducive to warming with highs back into
the upper 30s and low 40s. This wave looks rather dry with not
enough prolonged southerly flow for adequate moisture return, but
some upper to mid level cloud cover is likely.
By the end of the week, ensemble variability is high leading to much
lower forecast confidence. Some ensemble members are picking up on a
stronger wave with marginal moisture return, leading to PoPs on
Friday. Still without anything nearing a model consensus, chances
remain low at this time.
.Aviation...(06Z TAF Issuance)
Issued at 1034 PM EST Fri Feb 4 2022
- VFR flying conditions are expected through the TAF period.
- Winds will be less than 10 knots and start off 270-310
degrees, then shift to 180-210 degrees after 18z.
High pressure and drying column will combine for VFR flying
conditions through the TAF period. Winds will be less than
10 knots and switch from west and northwest to south and
southwest this afternoon.
Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
513 PM MST Fri Feb 4 2022
.DISCUSSION...(This Evening Through Friday)
Issued at 131 PM MST Fri Feb 4 2022
The upper trough has shifted to the eastern CONUS,
while a ridge builds over the west, and a shortwave pushes into
the Pacific NW. Morning flurries have disappeared, and skies are
mostly sunny. At the surface, high pressure sits over the central
Dakotas, with a trough over MT/WY, and a warm front draped across
our CWA. West of the front, winds are southwesterly and breezy,
and temperatures are in the 30s; east of the front, winds are
easterly and light, with temperatures in the teens.
Pacific NW shortwave will approach the northern plains tonight.
Initially, only weak CAA and some gusty winds are expected on
Saturday. Models disagree about wind strength: GFS ensemble and HRRR
show advisory criteria winds likely across northwestern SD, but MOS
guidance and ECMWF ensemble are more marginal. Forecast soundings
still indicate 50+ kt 850 mb winds early Saturday morning, but
decreasing winds aloft once mixing starts. Likeliest place for
strong winds will be across NW SD where the pressure gradients will
be tighter, so will issue a Wind Advisory there.
Secondary piece of energy associated with the shortwave will push
colder air into the region Saturday night into Sunday, and this combined
with moisture advection, light snow will develop. Froude number
is indicative of upslope enhancement over the northern Hills
Saturday evening through Sunday morning, and models continue to
slightly increase forecast snow amounts. Over the past few days,
the NBM 50th percentile has increased from 0.5 to 3 inches; now
the 90th percentile is up to 6 inches over the Black Hills. An
advisory may be needed later. Also looks like there could be some
light snow showers just about anywhere on the plains, so
broadbrushed slight chance pops. Little to no accumulations are
expected on the plains.
Warm air advection resumes briefly late Sunday into Monday, allowing
highs Monday to reach the 40s and 50s. However, the active pattern
returns for the rest of the week, resulting in breezy periods and
occasional snow showers. Moisture will be limited, so any snow
accumulations should be light.
.AVIATION...(For the 00Z TAFS Through 00Z Saturday Evening)
Issued At 411 PM MST Fri Feb 4 2022
VFR conditions will continue through the TAF forecast period. A
period of low level wind shear is expected across western South
Dakota overnight. Gusty northwest winds will be found across the
area on Saturday, with the strongest winds across the plains north
of the Black Hills.
SD...Wind Advisory from 8 AM to 5 PM MST Saturday for SDZ001-002-012-