Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/13/22
Area Forecast Discussion
National Weather Service La Crosse WI
814 PM CST Sat Nov 12 2022
Issued at 810 PM CST Sat Nov 12 2022
Overall, the main concern for the next 24 hours will be the
degree of low cloud cover over the region. Given the large
expansive upstream stratus/stratocumulus shield and light N/NW flow,
have increased sky cover through tomorrow to at least have
"mostly cloudy" wording in the forecast. The deterministic/
ensemble-based guidance are really struggling to resolve these
clouds, so the sky cover update goes well beyond the NBM 90th
percentile input (the most aggressive available) and leverages a
subjective analysis of HRRR sounding profiles. These show
convective temperatures being reached throughout at least the next
24 hours--inferring the presence of at least mostly cloudy skies.
Also nudged lows a few degrees higher given the lessened
.DISCUSSION...(This evening through Saturday)
Issued at 310 PM CST Sat Nov 12 2022
- Snow Monday into Wednesday with some accumulations
- Below normal temperatures continue into next weekend
Water vapor satellite imagery and heights show a closed 500mb low
pressure system over Ontario. The trough extended southwestward
toward the forecast area with a couple more embedded impulses in the
northwest flow aloft. Other areas of closed low pressure were noted
over Alberta Canada and northern CA and Oregon. At the surface, a
trough has push south with continued cold air advection. Some of
the stronger winds aloft have been mixing down 15 to 25 mph. Surface
high pressure was located to the west through the Dakotas into the
Mid-Missouri River Valley. At 2pm...temperatures were in the 30s
with scattered snow showers. These were mostly east of the
Mississippi River, however earlier in the day much of the area had
light snow or flurries with some minor accumulations on cold
surfaces. KRST reported 0.1", KLSE a trace, here at the NWS 0.1",
however other spots reported trace to 0.9" (north side of RST).
Flurries for Some Tonight/Sunday and Cold:
We remain under cyclonic flow tonight, however ridging will build in
from the west. Lingered flurries into the evening, then clouds will
become more patchy. The RAP forecast soundings of RH show the
variable nature of low, mid and higher level RH. The cloud cover
will impact temperatures tonight. Low temperatures should dip into
the mid teens to lower 20s. For Sunday, as surface high pressure
builds in, we continue to see patchy clouds. A strong jet aloft
will also try to bring in increasing mid and high clouds. Areas
north of I94 could see some lingering flurries as well. Temperatures
remain well below normal Monday in the 30s.
Snow Moves in for Some Sunday night through Late-week
We continue to see some differences in the details as the trough
over southern Canada slowly rotates through the Northern Plains
Sunday night...then as the trough over Southern Plains lifts north
into the Mid-Mississippi Valley region, this blocks the progress of
the northern stream wave and they gradually merge through Tuesday
night and remain over the region through Wednesday. The NAEFS
temperatures remain 1 to 2.5 standard deviations below normal with
precipitation type predominantly being light snow.
The low level jet increases across the Central Plains Sunday with
mid level warm air advection across the local area Sunday night into
Monday. Light snow chances are higher across MN into northern WI
closer to the upper low Monday. Tuesday and Tuesday night, snow
chances increase for the area with the storm system in the region.
The snow chances continue into Wednesday until that portion of the
storm system pulls away. With the lack of focused forcing at this
time, current snow amounts are still on the light side. The EC
Ensembles continue to show light snow totals of an inch or two, with
a range of .5 to 4 inches at KLSE and KRST for the long duration.
Some wind gust potential Tuesday per the EPS with gusts 15 to 30
mph. Additional snow chances later in the week along with below
normal temperatures into the week as the longwave trough pattern
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 501 PM CST Sat Nov 12 2022
MVFR cigs have waned from both TAF sites this evening. Upstream,
MVFR cigs sustain in central MN. Therefore, have continued tempo
MVFR for KRST. KLSE with lower elevation and VFR cigs upstream
expected to remain VFR. The upper level trough scoots east for
Sunday with a ridge building in from the west. This will
introduce drier air off the deck. Numerous model differences
surrounding moisture content and therefore cloud base. Have
continued BKN VFR cigs based on higher resolution model sounding
with northwest flow this time of year. Given its higher
elevation, possible for KRST to dip back into MVFR cigs, but not
enough confidence to introduce at this time.
Area Forecast Discussion
National Weather Service Green Bay WI
554 PM CST Sat Nov 12 2022
Updated aviation portion for 00Z TAF issuance
.SHORT TERM...Tonight and Sunday
Issued at 247 PM CST Sat Nov 12 2022
The latest RAP analysis and satellite/radar imagery show deep
layer cyclonic flow continuing between low pressure over Maine and
high pressure over the northern Plains. While there were some
breaks in the overcast this morning, those holes have filled in
this afternoon with help from heating of the day and very minor
surface instability. Cellular snow showers and flurries have also
developed away from the more organized lake effect snow showers.
Think these snow showers could persist into early this evening,
although little to no accumulations are expected outside of the
lake effect snow belts. Forecast concerns continue to revolve
around snow shower trends and potential accumulations.
Tonight...Cold cyclonic flow will continue with onshore flow off
Lake Superior. Large scale ascent will weaken during the evening
as the upper trough axis shifts across Lake Michigan into the
state of Michigan. As a result, diurnal aided snow showers will
likely diminish by early this evening, and should see a
diminishing trend of the lake effect snow bands through the night
with increasing subsidence and influx of dry air. An additional
1-2 inches of snow appears possible over far northern Vilas
county, while surrounding areas will see less than an inch. Widespread
strato- cu remains upstream, so it`s difficult to think rapid
clearing with occur. But some holes are likely to develop,
particularly in the downsloping areas of north-central and east-
central WI. Low temps ranging from the upper teens to middle 20s.
Sunday...Polar high pressure will be inching east towards the
region. As the influx of dry air continues, weakening north flow
should lead to any remaining lake effect snow bands to retreat
into the Upper Peninsula. Some minor accumulations remain possible
over Vilas county until that occurs. Areas outside the lake effect
snow belt should see increasing sunshine. Temps will remain
chilly, and change little form today`s readings.
.LONG TERM...Sunday Night Through Saturday
Issued at 247 PM CST Sat Nov 12 2022
The upper pattern will be fairly consistent through next weekend. A
500mb ridge over the eastern Pacific will keep high amplitude
flow in place across central CONUS. The influx of colder air from
the north will keep the a downstream upper trough in place for the Great
Lakes, providing numerous opportunities for precipitation through
the work week.
Surface high pressure is anticipated to still be in the area
Sunday night into Monday, making for a quiet end to the weekend.
Precipitation trends then increase Monday afternoon as
precipitation arrives from the west. Additionally, southeasterly
flow near Lake Michigan could bring in at least one round of
precipitation to the lakeshore, so kept the pops in for the
lakeshore before the showers arrive from the west.
From there, the main trough will setup over WI, bringing in the
main period of precipitation for Tuesday, Wednesday, and Thursday.
Although precipitation will be light throughout, there will be
numerous scattered snow showers through this period of the
forecast, so kept pops relatively high. Additionally, rain could
mix in at times over the lake and lakeshore areas where boundary
layer temps could mix just warm enough to move away from all
flurries. Away from the lakeshore and Fox Valley, this system
could be the first accumulating snow for many, with generally less
than or around an inch over the multi day period for portions of
Cyclonic flow will linger on through the end of the week, finally
pulling even cold air into the region for Friday into the weekend.
Current forecast brings highs in the upper teens to middle 20s
across the region.
.AVIATION...for 00Z TAF Issuance
Issued at 543 PM CST Sat Nov 12 2022
Cold NNW flow off Lake Superior will continue tonight into early
Sunday, resulting in lake-effect snow showers over north central
WI, and especially Vilas County. Some of the snow showers will
make it as far south as RHI tonight. Another area of concern will
be northern Door County, where bands of lake-effect snow/rain
showers will continue tonight. Elsewhere, scattered light snow
showers or flurries will taper off early this evening, as an upper
level trough shifts east of the region. MVFR/IFR conditions will
continue in the lake-effect regions into Sunday morning, while
most other locations should see VFR conditions (SCT-BKN
stratocumulus) through the TAF period. Gusty northwest winds will
taper off this evening, and become fairly light during the day on
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
522 PM CST Sat Nov 12 2022
.SHORT TERM...(This evening through Sunday night)
Issued at 254 PM CST Sat Nov 12 2022
- Light snow and flurries persist this afternoon and evening.
This Afternoon through Sunday night... It has been another day of
persistent light snow and flurries falling from the deck of stratus
clouds, which have stuck around a touch longer than guidance
originally thought, likely due to the cold/damp northerly flow. These
will persist through the evening hours before gradually tapering off
overnight. Impacts should be minimal but consider this a friendly
reminder: please exercise caution on the roads as we start the cold
season... if a surface appears wet, please assume it`s untreated/icy!
Our stratus deck has also prevented our temperatures from moving
much over the past 24 hours. At MSP airport has remained 28F since
Friday evening and looking ahead it`ll only cool a few degrees
tonight and warm back near 30 on Sunday. Highs across the area will
reach the mid to upper 20s on Sunday. Lows tonight will be in the
lower 20s to mid 20s in the Twin Cities. The northwest winds finally
shift to the southeast on Sunday ahead of an approaching system,
otherwise conditions will be similar to Saturday. Another chance for
light arrives Sunday night as a weak sfc low associated with an
inverted trough moves into western Minnesota from the Dakotas. I`ve
opted to increase PoPs from 06z to 12z Monday since confidence is
rather high that we`ll see light snow across western MN, but QPF will
only amount to a trace to a few hundredths in that time period by
Monday morning. If you`re looking for additional light snow chances,
we`ll see them in the extended period early next week.
.LONG TERM...(Monday through Saturday)
Issued at 254 PM CST Sat Nov 12 2022
- Periods of light snow from Monday through Wednesday. Light
- Arctic cold front passes through Thursday, bringing more
occasional light snow or flurries and much colder air late week.
Broad cyclonic flow aloft within a deep upper level trough will keep
an unsettled and cold pattern around throughout the long term.
Multiple short waves within the cyclonic flow will also bring
periodic snow chances through most of next week.
The first wave to watch will swing east across the northern Plains
into the Upper Midwest Sunday night/Monday. A period of light snow
is likely with this feature. The column will gradually saturate
Sunday night with a fairly deep, moist DGZ resulting by early Monday
morning. Most of the QPF differences among guidance stem from
boundary layer moisture quality and timing of features. GFS appears
too dry Monday. Lift will be modest, but existent throughout much of
the column, thereby supporting a broad area of light snow. The potent
vorticity max itself could allow for a few brief bursts of steadier
snow. An inch, maybe two, could occur depending on eventual QPF and
duration of steadier snow. PoPs have been increased to 50-60 percent,
but will need to be increased further when timing and boundary layer
moisture quality become more certain. The first short wave lifts
northeast by late Monday and Monday night, but occasional light snow
or flurries will likely continue due to modest lift and a moist
Attention will turn to another wave across the southern Plains with
more moisture to work with. The cyclonic flow will be maintained
across the north central states and will work to phase with the
southern wave Tuesday as it tracks northeast along or just north of
the Ohio Valley. An inverted trough extending from system to the
broader upper low could enhance the availability of moisture locally.
Forecast soundings again depict a saturated column with weak lift
extending throughout the entire layer for a prolonged period of time.
This would suggest widespread light snow, especially Tuesday
afternoon with the arrival of another vort max. Another inch or two
are possible. Added PoPs into Wednesday due to the moist cyclonic
flow remaining in place.
An arctic front will push through Thursday, reinforcing the cold air
in place. Highs will remain in the teens Friday with lows in the
single digits. Once again, with steep low level lapse rates and
moisture within the DGZ, some snow showers are possible Thursday.
Most of the column should be colder than the DGZ by Friday, which
should then limit the extent of snow showers.
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 514 PM CST Sat Nov 12 2022
Guidance may think we`ll see this stratus start to breakup overnight
into Sunday morning, but satellite trends show otherwise. Forecast
soundings from the RAP show moisture in the 2k-4k foot layer going
nowhere this period, so kept stratus in place at all locations
through the entire period. We may see some breaks, especially Sunday
afternoon, but this looks like a perma-stratus situation. We should
continue to see some flurries this evening, though with vis
restrictions not expected, kept any SN mention out of TAFs.
KMSP...We`ll have light winds this period, trending easterly Sunday.
Unless we see clearing break out tomorrow in WI, these easterly winds
will only help to keep the clouds in place. Fortunately, heights will
remain VFR, it`s just going to be another day of all clouds and no
/OUTLOOK FOR KMSP/
MON...VFR. -SN/MVFR & IFR likely. Wind SE 5-10 kts.
TUE...MVFR. -SN/IFR likely. Wind SE 5 kts.
WED...MVFR. Chc -SN/IFR. Wind NW 5-10 kts.
Area Forecast Discussion
National Weather Service Blacksburg VA
1009 PM EST Sat Nov 12 2022
A strong cold front will cross the eastern United States through
tonight, spreading light precipitation into the Mid Atlantic
region. High pressure builds in behind the front for Sunday and
Monday, with gusty wind and much colder air. Well below normal
temperatures continue into next week, with low pressure tracking
through the southeastern states Tuesday.
.NEAR TERM /THROUGH SUNDAY/...
As of 1009 PM EST Saturday...
Cold front will continue to move east across the region tonight.
Most of the prefrontal showers have ended in our east. Clouds
will linger along the mountains tonight into Sunday morning.
Downsloping flow and drier air will help remove clouds east of
the Blue Ridge overnight. Gusty northwest winds will advect cold
air into our region. Wind gusts along ridgetops could be as
high as 40 mph. The Namnest and HRRR showed the highest gusts
along the southern Blue ridge tonight. Modified temperatures
tonight into Sunday morning utilizing the latest surface obs,
their trends and blended in the NBM. In general, lowered
temperatures a few degrees in the west this evening and
overnight. Low temperatures tonight will range from around 20
degrees in the highest elevations to around 40 degrees in the
As of 610 PM EST Saturday...
The cold front is moving across eastern Kentucky and western West
Virginia this evening. Meanwhile, prefrontal showers have moved east
of the Blue Ridge and should clear the piedmont around 10 PM. For
most of the night, clouds will persist across the mountains,
especially western slopes. Downsloping flow and drier air will help
remove clouds east of the Blue Ridge starting around midnight.
Colder air will filter into the area tonight with lows dropping into
the mid 20s to lower 30s. Through the early morning hours, some snow
flakes may fall in extreme southwestern Virginia and southeast West
Virginia...particularly along western slopes. No snow east of the
Blue Ridge but temperatures will cool down into the upper 30s to
Pressure rises and a cross-barrier jet will bring breezy and gusty
conditions to the mountains and foothills into early Sunday
afternoon. Wind gusts along ridgetops could be as high as 40 mph.
As of 125 PM EST Saturday...
Much colder air arrives overnight with most precipitation
Broad troughing encompassed about the eastern half of the CONUS
this afternoon. A negatively-tilted short wave was brushing by
our region, and was helping to steer a baroclinic zone east. The
boundary was currently from east of the NJ coast, to the Blue
Ridge, to the FL panhandle. On the west side of this boundary,
much colder air and some snowfall was noted, with temperatures
in the 30s already pushing into western TN and KY.
Showers were moving quickly across the southern Appalachians,
and will continue to shift southeast through the afternoon and
evening into the Piedmont areas of VA and NC. NW winds will push
the front east, ending the precipitation for most by this
evening. Upslope showers intensify for the higher terrain late
tonight however, with the highest peaks seeing light additional
precipitation as a rain/snow mix. The Greenbrier Valley will
have the best shot at seeing a couple tenths of an inch of snow
through Sunday morning.
Gusty NW winds in the wake of the front will facilitate strong
cold air advection tonight through Sunday. Skies begin to clear
out over the Piedmont tonight, while areas along and west of the
Blue Ridge will remain locked under cold air stratus. 850mb
temperatures drop below 0C everywhere in our area, and as low as
-9C for the mountains. Surface temperatures overnight will drop
into the low 20s to low 30s for the mountains, and into the mid
to upper 30s for the Piedmont. By Sunday, highs will range from
about 12 to 20 degrees below normal, equating to low 30s to low
40s for the mountains, and to the upper 40s to low 50s for the
Piedmont. The wind chill will make it seem about 5-10 degrees
cooler than that.
Confidence in the near term forecast is moderate.
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/...
As of 130 PM EST Saturday...
Wintry precipitation possible late Monday night/Tuesday...
In the wake of a departing upper level shortwave Sunday night,
high pressure at the surface will build into the area with
cold air advection continuing. This will allow temperatures to
fall well into the 20s early Monday morning, which will be the
coldest values since March for many locations.
Our attention then turns to the upper level low currently
spinning across the Pacific northwest. There is fair agreement
in the models that this feature digs across the southern plains
before lifting into the Ohio Valley by Tuesday morning. As this
system approaches, insentropic lift quickly increases as an
850mb southerly jet forms above the shallow cold air near the
surface. With the deepest moisture arriving around dawn, expect
a light wintry mix to develop, especially across the mountains,
but depending how fast the moisture can arrive, a light mix may
even been seen for a couple of hours east of the Blue Ridge
early Tuesday morning.
With the area coming under the influence of the left front quad
of a 250mb 110+ MPH jet and increasing UVV, expect
precipitation to be widespread, so continued likely POPs in most
areas Tuesday afternoon and evening. SREF forecast soundings
suggest any light wintry precip Tuesday morning should
transition to rain, expect for some of the deepest mountain
valleys. Any wintry accumulations Tuesday should be light, with
areas outside western Greenbrier County forecast to receive less
than one-half inch.
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
As of 140 PM EST Saturday...
Confidence is high for well below temperatures...
While there are some differences in the deterministic models
with regard to the timing and magnitude there is agreement
that an anomalously deep upper level trof, with reinforcing
shortwaves will maintain well below temperatures through much of
the long term period.
The WPC cluster analysis tools and NCEP ensemble models agree
that 500mb heights will be 2-3 standard deviations below
average, especially on Thursday and Friday, which will keep
temperatures well below normal.
The southern stream shortwave that will bring precipitation,
including snow in the mountains, on Tuesday will lift
northeast out of our area, but with a southerly low level
jet/isentropic lift over the sfc wedge of high pressure,
precipitation will likely linger Tuesday night before the low
level flow shifts to the west/southwest triggering upslope snow
showers. Some minor snow accumulations are possible in the
mountains, with the ECMWF ensembles hinting at light
accumulations even into the New River Valley and NW NC.
The strongest surge of cold air arrives Thursday as the next
northern stream shortwave pushes a cold front through our area.
Uncertainty increases with the strength/amplitude of the next
northern stream shortwave that enters the Great Lakes Friday and
into next weekend, but with a large majority of the WPC clusters
continuing to hold the deep trof over much of the eastern 2/3rds of
the country, will continue to keep temperatures well below normal.
.AVIATION /03Z SUNDAY THROUGH THURSDAY/...
As of 615 PM EST Saturday...
Prefrontal showers are moving across the piedmont (KLYH/KDAN) this
evening and should clear the area by 10 PM. Areas east of the Blue
ridge will see clouds wither away starting around midnight, but
persist across the mountains into Sunday morning. Ceilings along
western slopes (KBLF) will likely be at or below IFR levels. Other
mountain locations (KLWB/KBCB) should have ceilings in the MVFR
The passing cold front will turn winds to the northwest this
evening, with gusts up to 35 kts or so through Sunday.
Extended Aviation Discussion...
Dry air and VFR conditions arrive for all by Sunday afternoon
through Tuesday morning. On Monday and Tuesday winds will be light
Another system is likely to bring sub-VFR conditions and
precipitation by later in the day Tuesday. Gusty downsloping winds
once again clear skies out along and east of the Blue Ridge for
Wednesday, while the mountains see prolonged stratus and light