Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/19/23
AREA FORECAST DISCUSSION
National Weather Service Albany NY
918 PM EST Wed Jan 18 2023
Some clearing is expected for tonight with seasonable
temperatures. A complex storm system will bring a wintry mix of
precipitation to the region Thursday and Friday. Drier weather
returns for much of the weekend, but another winter storm is
expected to bring snow or rain to the region for Sunday night into
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
As of 915 pm, temps running a few degrees higher than forecast
due to breezy conditions and clouds taking a while to dissipate.
Also a few lingering flurries/sprinkles noted on NYSM cams over
the ADKs and Mohawk Valley. A few minor tweaks to the grids but
overall no big changes needed.
As of 353 PM EST...Upper level shortwave trough located over
New England and Atlantic Canada is quickly moving eastward, with
upper level shortwave ridging moving into the area for tonight.
IR satellite imagery and surface observation shows widespread
cloud cover over the area late this afternoon thanks to abundant
low level moisture trapped beneath an inversion. 3km HRRR does
suggest some partial clearing will be occurring overnight,
especially for valley areas, as the northwest flow downslopes
off the terrain and some drier air works into the region from
With some clearing expected to occur, temps overnight will fall
into the 20s across most of the region.
.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/...
Updated 730 pm...noticing some trends in the 18Z guidance for
dynamical and wetbulb cooling to possibly offset warm advection
aloft and keep p-type as snow for a bit longer than anticipated
in the 18Z Thu to 03Z Fri timeframe in a narrow zone just north
of I-90. It will be a close call with likely a sharp north/south
snowfall gradient between mixed precip zone and areas that see
mostly snow. Updated snow grids to hedge a bit higher from I-90
north. No changes needed to headlines attm but will reevaluate
with the 00Z guidance.
A complex winter storm will be impacting the region through much
of the short term period. Low pressure will be moving across
the Midwest and into the Great Lakes on Thursday. This primary
low will be weakening as it reaches the eastern Great Lakes.
Meanwhile, a secondary low will be developing off the northern
mid Atlantic coast for Thursday night and it will be lifting to
the northeast off the coast of New England for Friday.
Thursday morning will start off dry across the entire area,
although clouds will be quickly increasing and thickening from
south to north. Warm advection will be underway thanks to a
southerly low level jet of around 30 to 40 kts. A band of steady
precip will be lifting south to north for the late morning into
the early afternoon hours. Although surface temps will be in the
mid 30s for many areas, dewpoints will remain in the 20s. As
dynamic cooling/wet bulb effects occur with the onset of the
precip, most areas will be starting off as snowfall. From about
the Capital Region and I-90 on southward, precip will only
remain all snow for a short period (1 to 3 hours or so), as
warmer air arriving aloft will allow a changeover to sleet or
freezing rain. Some southern locations (mid Hudson Valley into
NW CT) may see the boundary layer warm just enough for precip to
jump to just a plain rain. However, many northern and sheltered
areas will remain a wintry mix, including freezing rain into the
evening hours. Far northern areas will see enough cold air
entrenched in place, to keep p-type as mainly snow, with areas
further north seeing the least potential for mixed precip. Temps
will likely be situated close to freezing in many areas, with
everyone with a few degrees on the freezing mark and temps
holding fairly steady.
The steadiest precip will be through the late evening hours.
Once the best warm advection starts shifting away, there will be
a lull in the precip from about midnight onward. Even within the
lull, on and off light precip (mainly wintry mix or freezing
drizzle) will be occurring for the late night hours. Temps will
hold fairly steady or slowly rise in the low to mid 30s across
the entire area.
On Friday morning, steady precip will return as the secondary
coastal low starts to take over and the large upper level trough
will be moving overhead. This will allow precip to be mainly
snow, although some light rain is still possible for valley
areas when precip is lighter in intensity. The steadiest precip
is expected for the morning hours, with precip by afternoon
mainly for upslope and high terrain areas. Once precip starts to
wind down, temps will rise to the mid 30s to low 40s for valley
areas (upper 20s to low 30s for the high terrain). It will be
clearing out for Friday night with temps falling back into the
teens and 20s.
A Winter Weather Advisory is in effect for nearly the entire
area for Thursday afternoon into Friday. While valley areas may
only see a coating to a few inches of snowfall, 3 to 6 inches of
snow is possible for the northern higher terrain areas
(Adirondacks, Greens and Berkshires). Slick travel is expected
on both the Thursday evening and Friday morning commutes,
especially for northern areas.
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
Increasing subsidence is likely through the day Saturday with high
pressure building in. However, forecast soundings suggest moisture
may remain trapped beneath the building inversion, so skies may
remain partly to mostly cloudy with seasonable temperatures.
High impact weather potential remains focused on the late Sunday
through early Monday time period. Models suggest a deep, positively
tilted trough sweeps across the eastern half of the CONUS
Sunday/Sunday night, allowing anomalous moisture to spread poleward
up the eastern seaboard. The trough may assume a negative tilt
and/or cut off as it reaches the Northeast US. A surface low is
expected to develop in the Deep South Sunday morning, strengthening
as it moves up the east coast toward southern New England by Monday
morning. This is typically a good general track for moderate to
heavy precipitation in our area. Typical spread in the strength and
track of the low center will determine sensible weather impacts, as
model consensus puts the 850 mb freezing line (rain/snow line, in a
general sense) somewhere toward the central/southern portion of the
forecast area. Overall, ensemble solutions have tended to cluster
more in a favorable low track for accumulating snow for at least the
higher terrain, and also possibly some of the valleys. Unlike recent
storms, current model consensus tracks the low south and east of the
forecast area, allowing colder air to be in play. Some mixed precip
also cannot be ruled out. Will continue to mention potential for
winter weather impacts in the Hazardous Weather Outlook.
Early indications are for seasonable weather in the wake of this
system late Monday into Tuesday, with possibly some lingering lake
effect or even light synoptic-scale snow with potential for a
moisture-starved northern stream wave. Potential exists for another
more widespread precipitation event Wednesday with another deep
trough lifting up the eastern seaboard.
.AVIATION /02Z THURSDAY THROUGH MONDAY/...
MVFR ceilings at ALB and PSF this evening should erode by 04 -
06 UTC as drier air pushes towards the region resulting in VFR
conditions at all terminals. VFR conditions will then persist
overnight with high clouds overspreading the area leading BKN-
OVC ceilings at or above 20kft. As we approach 09 - 15 UTC,
ceiling will continue to lower from south to north as our next
area of precipitation spread northward. POU will likely
observing MVFR ceilings first with rain potentially mixed with
sleet arriving by 12 - 15 UTC. Clouds lower at ALB and PSF next
resulting in MVFR ceilings by 15 - 18 UTC as snow mixed with
sleet spreads northward. GFL will then observe MVFR ceilings
closer to 18 UTC as snow arrives.
Precipitation type remains a challenging forecast tomorrow
afternoon as warm air tries to move in aloft while surface
temperatures will likely stay near the freezing mark. A mix of
snow and sleet is expected at ALB and PSF with periods of all
wet snow possible during moderate or heavier precip rates.
Given milder temperatures, expecting a mix of rain and sleet at
POU before becoming mainly rain towards the end of the TAF
period. GFL should remain cold enough for mainly all snow to
Westerly winds this evening remain a bit breezy at ALB, POU and
PSF with sustained winds near 8 - 12kts while GFL is lighter
near or under 5kts. Winds should continue to weaken overnight
and become near or under 5kts at all sites, especially by
sunrise. Weak winds gradually increase through the day and shift
out of the northeast to east-southeast sustained 4 - 8kts.
Thursday Night: High Operational Impact. Definite RA...SN...FZRA...SLEET.
Friday: High Operational Impact. Definite RA...SN.
Friday Night: Moderate Operational Impact. Chance of SHSN.
Saturday: No Operational Impact. NO SIG WX.
Saturday Night: No Operational Impact. NO SIG WX.
Sunday: Low Operational Impact. Slight Chance of RA...SN.
Sunday Night: High Operational Impact. Likely RA...SN.
Monday: Moderate Operational Impact. Breezy. Chance of RA...SN.
CT...Winter Weather Advisory from 10 AM Thursday to 1 PM EST Friday
NY...Winter Weather Advisory from 10 AM Thursday to 1 PM EST Friday
Winter Weather Advisory from 1 PM Thursday to 1 PM EST Friday
Winter Weather Advisory from 11 AM Thursday to 1 PM EST Friday
MA...Winter Weather Advisory from 11 AM Thursday to 7 PM EST Friday
VT...Winter Weather Advisory from 11 AM Thursday to 7 PM EST Friday
AREA FORECAST DISCUSSION
National Weather Service Sioux Falls SD
839 PM CST Wed Jan 18 2023
Issued at 828 PM CST Wed Jan 18 2023
Snow has finally arrived for locations along/south of I-90 after
suffering from saturation issues thru the first part of the
evening. Snowfall reports from the Hwy 20 corridor thus far have
generally underachieved expectations from what was expected from
the initial round of heaviest snow. 00z hi-res guidance seemingly
clustering around the idea of a more narrow corridor of higher
amounts from Sioux City to Yankton and then back east toward
Canton and Spencer. With this said, current radar trends show a
more convective nature to the far southern flank of this area
lending some question as to whether higher snow rates will be
consistent enough to yield the highest totals. Tend to think, the
highest corridor may actually end up either side of a Yankton to
Beresford to Cherokee line instead. Have updated forecast grids to
reflect these thoughts favoring a heavy HRRR blend and manually
shifting this axis slightly.
.SHORT TERM...(This Evening through Thursday)
Issued at 400 PM CST Wed Jan 18 2023
1. An impactful winter storm will bring heavy snow to areas south of
Interstate 90 for tonight into early Thursday. Greatest uncertainty
with snow amounts continues to reside along the northern snowfall
2. With increasing northerly winds, areas of blowing snow will be
possible into Thursday.
2. Quieter conditions return Friday into the beginning of next week
with temperatures at or just below normal.
THIS AFTERNOON: Current mesoanalysis shows shows the upper level low
lifting out of KS into NE, with the surface low positioned over
southeastern KS. Warm air advection and midlevel frontogenesis is
lifting through the MO River corridor out ahead of the wave, and
current radar/observations/and webcams are indicating light to
moderate snow developing through the south central SD into the mid
MO River Valley this afternoon. Drier air to the north and east has
kept precipitation at bay over that area through the afternoon,
though snow will eventually begin to shift northward through the
TONIGHT/THURSDAY: Model runs and ensembles today have continued the
southward trend over yesterdays runs, though showing variation from
run to run with the northern snowfall gradient. In addition,
ensemble plumes show a wide spread of solutions, running anywhere
from 1 inch upwards to 7 inches or higher at Sioux Falls - which
lies in the northern snowfall gradient. What all this means is that
snowfall totals may be lower then the previous forecast along the
Interstate 90 corridor, and confidence remains low on exact snowfall
amounts through this area - and there will be a few inches of
variation over a short distance through this area. Confidence is
much higher to the south, and snow will become heavy at times
through the lower MO River corridor into northwestern IA by this
evening. HREF ensembles continue to indicate snowfall rates of 1 to
2 inches an hour over that area, with snow quickly accumulating
through 06Z. As mentioned in the earlier discussion, heaviest
amounts will generally reside south of Highway 18. Most of the
accumulating snow will come tonight between 00Z to 12Z Thursday
morning, then only very light lingering snow east of Interstate 29
through late morning.
Total snowfall amounts for the entire event have not changed
significantly (with some lowering along the northern snowfall
gradient as mentioned above ), with 8 to 14 inches along the MO
River corridor into northwestern IA. Amounts then trend down
northward to the Interstate 90 corridor, with 3 to 6 inches through
that area. Back through east central SD into the northern James
River Valley amounts will be 2 inches or less. Related to this, did
not make any headline changes with snowfall amounts still at least
touching criteria within each county, though if models continue to
trend even further southward some headlines may need to be
downgraded sometime tonight.
In addition to the snowfall, as mentioned in previous discussions
northerly winds will increase tonight into Thursday. With gusts
around 30 mph, visibilities will be greatly reduced at times in
blowing snow - especially when snow is falling.
.LONG TERM...(Thursday Night through Wednesday)
Issued at 400 PM CST Wed Jan 18 2023
FRIDAY-SUNDAY: Behind the current system, we are left in a
northwesterly upper level flow for Friday with surface high pressure
building into the region during the day. This will lead to a dry
day, with below normal temperatures and highs in the lower to mid
20s. A northern stream/southern stream upper level trough swings
into the central CONUS for Saturday, phasing to the east of our area
by late Sunday. The southern stream portion will be the stronger of
the two, and any precipitation will be collocated with this feature.
Fortunately, at this time it appears that any of this activity will
remain south of our CWA. Temperatures do modify a bit for the
weekend, as highs climb back closer to normal for this time of year.
MONDAY-WEDNESDAY: The active upper level pattern continues through
midweek, with another upper level trough drifting into the region
for Monday into Tuesday. A couple models would produce light
precipitation for portions of our area with this on Monday, then
again later on Tuesday, though with lack of agreement among models
left the forecast dry for now. Temperatures do look to cool down on
Tuesday behind this system, then moderating again on Wednesday.
.AVIATION...(For the 00Z TAFS through 00Z Thursday Evening)
Issued at 506 PM CST Wed Jan 18 2023
In the very near term, fog is in place across portions of SW MN
and NW IA from roughly a SLB to OTG to CNB line east. This will
reduce vsby below 1 SM for the next few hours before being
replaced with wintry precip concerns thereafter.
Shield of snow is working north, just now arriving into KSUX with
arrival into KFSD by mid evening. South of I-90, high snow rates
will drive vsby to or below 1/2 SM with snow rates dropping off
with northern extent. The combination of IFR/LIFR ceilings and
reduced visibility from -SN will result in sub IFR conditions
through the overnight.
Snow will transition east of I-29 by daybreak Thursday and exit
the forecast area by mid morning. Northerly winds will gust as
high as 25 kts at times.
SD...Winter Storm Warning until 9 AM CST Thursday for SDZ062-066-067.
Winter Storm Warning until 6 AM CST Thursday for SDZ050-063>065-
Winter Weather Advisory until 9 AM CST Thursday for SDZ055-056.
Winter Weather Advisory until 6 AM CST Thursday for SDZ057>061.
MN...Winter Storm Warning until 9 AM CST Thursday for MNZ081-089-090-
Winter Weather Advisory until 9 AM CST Thursday for MNZ071-072-
IA...Winter Storm Warning until 9 AM CST Thursday for IAZ001>003-
Winter Storm Warning until 6 AM CST Thursday for IAZ031-032.
NE...Winter Storm Warning until 6 AM CST Thursday for NEZ013-014.
Area Forecast Discussion
National Weather Service Goodland KS
642 PM MST Wed Jan 18 2023
Issued at 642 PM MST Wed Jan 18 2023
Update to forecast for minor tweaks on temps/winds from latest
obs. Current Winter Storm Warning/Winter Wx Advisory still
ongoing. The cwa is seeing continued wrap-around moisture
bringing additional snows. The stronger northerly flow is
continuing to push eastward with basically areas west of Highway
25 seeing gusts up to 30-40 mph at times, and do expect for
eastern areas as the evening progresses. As a result will
continue mention of blowing snow this evening. Will re-assess any
potential earlier exit from the current winter wx products should
the wrap-around snows taper off before it`s current 06z Thursday
.SHORT TERM...(This evening through Thursday Night)
Issued at 306 PM MST Wed Jan 18 2023
At the beginning of the short term period, the latest RAP analysis
currently shows the upper air low over the eastern portion of the
CWA with an upper air ridge over the Rockies. Radar and satellite
imagery along with surface observations show light to moderate
snowfall and lower visibility in portions of the CWA as well as a
low overcast cloud ceiling across the entire CWA. Forecast models
show the low moving east-northeast towards the IA/NE border
overnight yielding a northerly to northwesterly flow aloft in the
wake of the low. At the surface, snowfall chances look to slowly
taper off beginning in the southwestern portions of CWA during the
evening hours and completely exit out of region in the northern
portions a few hours after midnight. Additional snowfall amounts
look to range between less than inch in the southern portions of the
CWA to around 3 inches in the NE counties though locally heavier
amounts may be possible if snow bands linger in an area. Forecast
QPF totals for the remainder of the snow look to range between a
few hundredths to a few tenths. With temperatures decreasing
overnight, hazardous travel conditions could continue due to icy
roads and surfaces if not treated. Frozen drizzle cannot be
completely ruled out as well for the rest of Wednesday along with
some fog mixed in with the precipitation should supporting
conditions be met. In addition, the CWA may see some breezy north-
northwesterly winds overnight possibly gusting up to around 30
kts. Blowing snow has been added to the Wx grids though snow has
been wet and heavy, so not the best confidence it will occur.
Opted to continue the Winter Storm Warning and Winter Weather
Advisories as the winter weather is still ongoing. Overnight lows
look to be in the lower teens to lower 20s with wind chills in the
single digits and possibly slightly below zero in the far western
portions of Yuma and Kit Carson counties.
On Thursday, models show the upper air low moving further east over
the Great Lakes region with the ridge over the Rockies drifting a
bit eastward allowing for the CWA to see a west-northwesterly flow
by the afternoon hours and going into the evening. Farther west,
another upper air low moves towards the NV/UT border by the
overnight hours. At the surface, dry conditions can be expected for
the CWA throughout the entire day with northwesterly to westerly
winds during the day that expect to slow down overnight. Low
visibilities do not look to be an issue for the first day in a while
due to fog or snowfall, but will monitor this in case conditions
change. Thursday`s daytime highs look to range between the lower 30s
and lower 40s followed by overnight lows in the upper single digits
to the middle teens with wind chills between a few degrees below
zero and the upper single digits.
.LONG TERM...(Friday through Wednesday)
Issued at 100 PM MST Wed Jan 18 2023
Friday...a closed upper level low centered over northwest Arizona in
the morning is forecast to move nearly due east into northwest New
Mexico by 00z Saturday then east toward southeast Colorado/extreme
western Oklahoma by 12z Saturday.
High clouds overspread the area during the day with increasing
moisture in the 850-500mb layer during the night. Snow is expected
during the night and for this round it favors those along and south
of Interstate 70. Not much wind expected during the time of snowfall
so blowing or drifting snow is not expected. Snowfall amounts are
currently forecast to range from a few tenths of an inch along the
KS/NE border to as much as 2 to 4 inches along and south of
High temperatures are forecast to be in the upper 20s to lower 30s
over all but Greeley and Wichita counties (little if any snow cover)
where highs are expected to be in the lower 40s. Low temperatures
fall into the middle teens to lower 20s.
Saturday...although the closed low slowly opens up into a wave
within a larger upper level trough, those south of Interstate 70
will still receive some additional light snow through much of the
day. Additional accumulations range from zero along the KS/NE border
to around 2 to 3 inches from Hill City to Tribune south. Dry weather
is expected during the night.
High temperatures are forecast to only be in the upper 20s to middle
30s with low temperatures a few degrees either side of 10 degrees.
Sunday...attention turns to an approaching upper level trough that
approaches from the northwest. Moisture in the 850-500mb increases
by late afternoon to support some slight chance pops for some light
snow across far eastern Colorado. During the overnight hours, snow
chances increase a bit more, especially along and west of the CO/KS
border. Accumulations at this time appear to be minimal.
High temperatures remain about 10 degrees below normal in the lower
to middle 30s. Low temperatures fall into the lower to middle teens.
Monday...the general trend from the GEFS, GEM, GFS and ECMWF models
is for the upper trough axis to move through the area during the day
with northwest flow over the area during the night. We`ll be
continuing with some slight chance to low chance pops during the day
with the trough moving through with decreasing chances from west to
east during the night. Snowfall amounts are currently expected to be
around a few tenths of an inch. High temperatures remain below
normal in the middle 20s to lower 30s. Low temperatures fall into
the single digits to around 10 degrees above normal. Wind chill
readings overnight in the single digits above and below zero.
Tuesday...there could be some slight chance pops for light snow in
the morning as a weak wave moves through from the west. The rest of
the period looks dry. Given 850mb temperatures in the single digits
below zero and some expected snow cover for parts of the area it
looks to remain cold with highs in the upper 20s to lower 30s. Low
temperatures fall into the lower to middle teens.
Wednesday...the forecast area is under northwest flow aloft. 850mb
temperatures remain in the zero to -5C range from the GFS/ECMWF/GEM
models generally supporting continued cold high temperatures in the
lower to middle 30s. At this time it appears to be dry.
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 422 PM MST Wed Jan 18 2023
For KGLD, winter storm is slowly winding down. 1-4sm in snow and
blowing snow through 09z Thursday. Ceilings around OVC010-020.
After 09z, MVFR ceilings giving way to VFR by 12z. Winds,
northwest 15-30kts through 12z Thursday, then 10-15kts.
For KMCK, impacts from storm similar as KGLD. Around 1-3sm in
snow/blowing snow giving way to 6sm by 08z Thursday. Ceilings
OVC009-015. By 10z MVFR conditions with VFR by 16z. Winds, mainly
northwest 15-30kts, then west-northwest around 10kts by 16z.
KS...Winter Storm Warning until 11 PM MST /midnight CST/ this evening
Winter Weather Advisory until 11 PM MST /midnight CST/ this
evening for KSZ015-016-027>029-041-042.
CO...Winter Storm Warning until 11 PM MST this evening for COZ090-091.
Winter Weather Advisory until 11 PM MST this evening for COZ092.
NE...Winter Storm Warning until 11 PM MST /midnight CST/ this evening
Area Forecast Discussion
National Weather Service Green Bay WI
741 PM CST Wed Jan 18 2023
New Information added to update section.
Issued at 740 PM CST Wed Jan 18 2023
The latest RAP analysis and satellite/radar imagery show low
pressure centered over eastern Kansas this evening. A band of
precip in a strong frontogenesis zone is lifting north across Iowa
and northern Illinois. This band will be approaching central
Wisconsin and the southern Fox Valley around midnight. As the band
lifts north across the region, the HREF indicates about a 3 hour
period of 1+ per hour snowfall rates starting after about 08-09z
in central WI and the Fox Valley, and 12-13z over north-central
and far northeast Wisconsin. The latest short range data indicates
snowfall that is quite similar to the going forecast, so do not
foresee making changes to the headlines that are in effect.
Otherwise, scattered light snow showers are becoming more
widespread along the lakeshore and into the Fox Valley this
evening. Have increased precip chances through the evening prior
to the snow band arriving.
Issued at 233 PM CST Wed Jan 18 2023
A significant snowfall tonight into Thursday, Temperatures
returning closer to seasonal normals.
The flow across North America will remain split. The forecast
area will initially be under the influence of the southern stream,
with a powerful southern stream cyclone crossing the region. Over
time, the area will come more under the influence of the northern
stream. Temperatures will not be as warm as the past few days,
but should still be AOA normal. Precipitation is also expected to
be AOA normal.
.SHORT TERM...Tonight and Thursday
Issued at 233 PM CST Wed Jan 18 2023
The main short-term forecast issue was determining snowfall
totals and aligning forecast headlines.
The main change with this issuance was to shift the max snowfall
north a bit. It also increased a bit N and W of the Fox Valley,
and decreased a bit in E-C WI. These changes fit with the ECMWF
tracking the mid-level circulation across the forecast area
tomorrow. The southern edge of the coldest cloud tops on satellite
imagery was first taking shape, but also seems likely to cut
right across the forecast area. This fits with heavy snow NW of
the Fox Valley, and raises some concern snow totals in E-C WI
might be a little lower than initial estimates. For this reason,
opted to go with an advisory for Winnebago>Manitowoc. Went with a
warning just north of there (Waupaca>Kewaunee) because there could
be a burst of heavy snow just before the morning commute that it
would be hard for highway crews to clean up before drivers head
out on the road.
The mid/upper level dry slot will likely affect E-C WI tomorrow,
causing snow to taper down quickly during the mid-late morning.
It could change to drizzle/freezing drizzle (depending on boundary
layer temperatures) as ice is lost from the cloud layer. On the
flip side, steep mid-level lapse rates could also result in some
convective elements developing right ahead of the dry slot.
Elsewhere, snow should diminish from S to N during the day
tomorrow, as the best dynamics shift off to the NE.
.LONG TERM...Thursday Night Through Wednesday
Issued at 233 PM CST Wed Jan 18 2023
A persistent eastern Pacific upper ridge will continue well into
next week with systems topping this ridge, then dropping southeast
across the CONUS. Trying to time these systems and their impacts
on our weather remains the main forecast challenge. Temperatures
to remain above normal, but there are definite signs of a return
to winterlike temperatures starting late next week.
Thursday night and Friday...
Lingering snow showers are expected into Thursday night with
individual mid-level shortwaves rotating within a cyclonic flow.
Any additional accumulations will be minimal (< 0.5"). Cooler air
being pulled into WI behind the departed system will send min
temperatures down to around 20 degrees north-central WI, mainly
middle 20s eastern WI. Other than perhaps a few lake effect snow
showers or flurries over Vilas County Friday morning, there could
be a few peeks of sunshine Friday afternoon as the cyclonic flow
dissipates and some drier air advects into the region. Max
temperatures to range from the middle 20s north-central, to around
30 degrees across eastern WI.
Friday night and Saturday...
High pressure is forecast to move across the mid-MS Valley/OH
River Valley Friday night bringing partly to mostly cloudy skies
and light west winds to northeast WI. A potential big range in
temperatures will be possible depending on the cloud cover with a
fresh snowpack on the ground. Have lowered temperatures a few
degrees from the previous forecast with mins ranging from 5 to 10
above zero north-central, middle to upper teens across east-
central WI. Any breaks in the clouds will fill in on Saturday as a
cold front and associated mid-level longwave trough move into the
Upper MS Valley. Models indicate there is more energy developing
at the base of this trough over the southern Plains at this time,
thus no precipitation expected over the region during the day. Max
temperatures for Saturday to range from the lower to middle 20s
north, middle to upper 20s south.
Saturday night and Sunday...
This longwave trough to extend from Hudson Bay through the western
Great Lakes to the southern Plains Saturday night with a surface
low developing in the vicinity of southern MO/northern AR. Showers
and thunderstorms over the Gulf Coast states will rob moisture
inflow farther north, however models have trended the northern
fringe of precipitation into southeast WI and may have to add a
small chance pop to east-central WI late Saturday night into
Sunday morning. Otherwise for the rest of the forecast area, look
for mostly cloudy skies for the latter part of the weekend with
max temperatures on Sunday to be in the 25-30 degree range.
Sunday night and Monday...
A ridge of high pressure is expected to move into the western
Great Lakes Sunday night and allow for skies to at least become
partly cloudy. Clouds will be on the increase once again on Monday
as the next cold front pushes into the Upper MS Valley. Better
upper support in the form of a closed upper low trails over the
northern Plains, thus do not anticipate any precipitation on
Monday. Little change in the thermal profiles, thus max
temperatures on Monday to again be in the 25-30 degree range.
Monday night and Tuesday...
Much like the previous system, this trough eventually digs south
into the southern Plains Monday night, then shifts east into the
Gulf Coast states on Tuesday. Gulf moisture will be cut-off,
leaving the northern side of the trough (and cold front) with
little moisture. Cannot rule out a few snow showers or at least
some flurries, thus have added a small pop to the forecast for
Monday night into Tuesday. Max temperatures on Tuesday to range
from the middle 20s north-central, upper 20s to lower 30s
Tuesday night and Wednesday...
A few snow showers could linger into Tuesday evening over eastern
WI, otherwise dry conditions are expected. Prevailing northwest
flow into WI will bring another cold front/shortwave trough into
the western Great Lakes region on Wednesday. Precipitation chances
may increase later in the day, but a bit early as there are some
timing issues among the models. The models do agree that colder
air will overspread northeast WI late next week with temperatures
settling at or below normal and some potential for lake effect
snows over north-central WI.
.AVIATION...for 00Z TAF Issuance
Issued at 532 PM CST Wed Jan 18 2023
MVFR conditions late this afternoon will deteriorate considerably
after midnight as a band of moderate to heavy snow shifts north
across the area. Scattered flurries and very light freezing
drizzle may occur prior to this heavy snow band arriving over
northeast Wisconsin. Within the snow band, anticipate IFR/LIFR
conditions after midnight into Thursday morning as the band shifts
north. Lighter snow and some DZ/FZDZ (depending on boundary layer
temperature) will continue in the wake of the main snow band after
15z over central WI and 18z over northern WI.
Winter Storm Warning from 2 AM to 6 PM CST Thursday for WIZ005-
Winter Storm Warning from midnight tonight to 3 PM CST Thursday
Winter Storm Warning from midnight tonight to noon CST Thursday
Winter Weather Advisory from midnight tonight to noon CST
Thursday for WIZ048>050.
Area Forecast Discussion
National Weather Service Grand Rapids MI
1008 PM EST Wed Jan 18 2023
Issued at 1008 PM EST Wed Jan 18 2023
There are no plans to modify/expand the Winter Weather Advisory
at this time.
Current sfc temperatures are in the mid to upper 30s near and
south of I-96, whereas many locations to the north are 33 to 35.
Dew points are still in the mid to upper 20s across the majority
of the area with the exception of the I-94 corridor which is
slightly above 32. The 00Z DTX showed considerable dry air above
There have been numerous MPING reports of sleet mixing in with
the rain across Chicago-land this evening. Based on the 00Z DTX
sounding as well as HRRR fcst soundings, suspect we`ll see a
similar situation here. Soundings show a warm nose above 0C
between roughly 4-6K feet, but a sub-freezing layer between about
While sfc temps may lower a tad once precip commences due to wet
bulb effects, the primary p-type is expected to be rain south of
the advisory area. (although some sleet mixed in for awhile at
the onset). A mixture of precip types is still supported across
the advisory area, although soundings and sfc temps suggest that
sleet may be more prevalent than freezing rain.
Exception may be across the area north of a Big Rapids to Clare
line where sfc temps may be just cold enough to support some
freezing rain and/or light accumulations of snow. However road
temps are still in the mid to upr 30s so impacts may be delayed.
East winds will be cranking up overnight and the hourly HRRR
updates continue to show 40-45 mph gusts developing after
midnight. This may be a bit on the high side, but there are some
peak gusts reports of 30-35 kts currently noted in nrn IL.
.DISCUSSION...(This evening through next Wednesday)
Issued at 203 PM EST Wed Jan 18 2023
-Mixed precipitation developing tonight for parts of the region
Guidance is generally settling in on a period of snow...sleet then
freezing rain/drizzle for interior Lower MI including Big
Rapids...Mount Pleasant and Harrison for later tonight into
Thursday morning. This is the region that is most likely to see
surface temperatures falling to near or just under freezing
tonight. Impacts are looking likely. We issued a winter weather
advisory as a result for these locations.
The approaching warm front and associated overrunning
precipitation will be the main source for the precipitation. Mid
level FGEN is noted tonight on the north side of the front as
well. With a dry slot in the 700 to 500 mb layer pushing north of
the CWA by noon Thursday...we will only feature the headline
until then. If surface temperatures stay below freezing during the
afternoon and we still have drizzle persisting its possible that
the headline may need to be extended in those region. Another item
monitor is whether impacts will occur tonight for places like
Muskegon...Grand Rapids and Lansing. If surface temperatures end
up a degree or two lower tonight...we may need to shift the
headlines further south. Generally though...that is not the most
likely scenario so no headlines for those locations...but close
monitoring will be needed.
-Impacts for the Friday morning commute?
As the wave of low pressure pulls away later Thursday afternoon
into early Friday...the colder air will filter/wrap back in. In
the mid levels...the associated closed low tracks through MI and
most models suggest that around 12z Fri...a vort max may dig into
the backside of this departing feature. If this happens...in the
colder air...we could see some stronger bands of snow around.
Based on this...we may see some impacts on the roads then...which
will be near the morning commute Friday.
-Possible accumulating snow Saturday night to Sunday
A weak surface wave is shown to track east northeast through OH
and IN during this timeframe. The accompanying positive tilted mid
level trough will be tracking eastward through the CWA during
this period as well. The GFS is showing deep moisture...mid level
FGEN and decent omega in the DGZ. The surface temperatures remain
below freezing for most of the event. Thus...this system has the
potential to generate some impacts. The Canadian and ECMWF are
also supportive for a couple of inches of snow as well.
-A surge of arctic air possible end of next week
Models are showing a stronger mid level wave and associated cold
front tracking through the area on Thursday. Behind these features
it looks like the region will see a surge of arctic air tracking
in. How long it lasts is unclear. The GFS and Canadian model are
much more aggressive with this airmass...showing 925 mb temps
dropping down to -20 to -25 deg C...while the ECMWF takes the
values down to -15 deg C keeping most of the arctic air in
Ontario. Also the Canadian and GFS are showing a stronger surface
wave generating a swath of snow here in MI...while the ECMWF has
this feature displace southeast of the CWA.
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 700 PM EST Wed Jan 18 2023
Expect MVFR cigs this evening but as rain moves in from south to
north after 03Z or so look for conditions to trend down to
predominately IFR overnight. A brief period of sleet was
maintained at MKG/GRR/LAN in this TAF update for late tonight,
although this risk is quite low and we may be able to remove it
entirely in later updates.
Rain tapering to mainly drizzle toward 12Z Thursday with arrival
of mid level dry slot, although IFR conditions lingering most of
the day. New showers approaching AZO/BTL/JXN late in the period
Thursday from the southwest, which could even bring a risk of
thunder (after 21Z or so). This threat is currently too low (and
too far out in time) to have in the TAFS-- but will need some
consideration in later TAF updates.
Issued at 203 PM EST Wed Jan 18 2023
The easterly flow will increase considerably ahead of the warm
front and approaching associated low pressure system tonight into
Thursday. The wind at 925 mb increases to 40 to 45 knots along and
ahead of the frontal zone. We are not forecast to mix to that
level...but this feature will help to increase the surface winds.
We hoisted a small craft advisory as a result.
MI...Winter Weather Advisory until noon EST Thursday for MIZ037>040-
LM...Small Craft Advisory until 11 AM EST Thursday for LMZ844>849.
Area Forecast Discussion...UPDATED
National Weather Service Memphis TN
833 PM CST Wed Jan 18 2023
Issued at 833 PM CST Wed Jan 18 2023
A moderately organized trailing stratiform QLCS is marching
eastward across the Mid-South this evening. No warnings have been
issued so far today across the CWA but we have seen some transient
mesovortices and a few weak minisupercells. The kinematic
environment continues to show impressive deep and low-level shear
across the Mid-South. Effective-layer shear remains in the 50-60kt
range with 0-3km shear vectors from the WSW at around 50 kts.
Effective storm-relative helicity also remains quite strong at
400-600 m2/s2 ahead of the advancing convective line.
Instability has been the missing ingredient thus far. Both MLCAPE
and SBCAPE remains at or below 500 J/kg across the CWA with 0-3km
CAPE generally less than 50 J/kg. We`ve actually seen very little
lightning across the area with the the bulk of the GLM response
along/south of I-20. Given the continuation of weak circulations
along the leading edge, we opted to extend the Tornado Watch until
10 PM for portions of north MS. Confidence is low that we`ll need
any warnings, but any pockets of instability could stretch one of
these weaker couplets into a brief, spin-up tornado should the
line segment become more favorably oriented with respect to the
low-level shear vector. The good news is that most of this will
be east of the CWA by midnight with improving conditions
Gusty winds are still expected through midnight for portions of
West TN and northeast MS ahead of the line. Thus, the Wind
Advisory will continue for now. It is noted that NBM v41 wind
speeds/gusts are too high across the board, so these were cut
down to a more reasonable level.
Issued at 330 AM CST Wed Jan 18 2023
A progressive midwinter weather pattern will prevail over the
lower 48 states through early next week.
At midafternoon, GOES water vapor imagery shows an upper low
centered over southern Nebraska. A the surface, a cold front
extends from an occluded low over central Missouri, southward
through east Arkansas. This front will provide a focus for
thunderstorms as it moves through the Midsouth through early
evening. Strongly veered low level wind profiles will provide a
marginal tornado threat where sufficient low level instability
can be realized.
(This evening through next Tuesday)
Issued at 310 PM CST Wed Jan 18 2023
Severe thunderstorm potential will remain the primary forecast
challenge in the short term. Low level wind shear remains
favorable for rotating updrafts, but instability remains in
somewhat in question. In particular, HRRR depicts 0-3km CAPE
below 100 J/kg, suggesting limited buoyancy outside of the frontal
convergence zone. Given the upstream breaks in overcast over the
Arklamiss, we decided to issue a tornado watch for the delta and
portions of southwest Tennessee.
Fair and cooler weather will prevail Thursday and Friday, under
fast zonal flow aloft.
Our next upper low will take a more southerly track, lifting from
the southern plains into the Ozarks Saturday night. This system
will bring showers over the weekend, but little to no severe
Another upper low will follow quickly early next week. This system
will dig as far south as Texas, before tracking into the lower MS
River Valley Tuesday and Tuesday night. Like the weekend system
before it, little to no severe weather threat is anticipated with
this system. By the time it exits Wednesday morning, some light
wrap-around rain/snow can`t be ruled out north of I-40.
Issued at 508 PM CST Wed Jan 18 2023
Showers and a few thunderstorms currently along and west of the
Mississippi River will continue to move east across the remainder
of the Mid-South tonight as a cold front moves through the region.
VFR ceilings will prevail for most of the evening with some periods
of MVFR ceilings with some of the showers and thunderstorms. All
of the showers and thunderstorms will be out of the region shortly
after midnight as the front moves into middle Tennessee and north
Winds will be mainly from the south at 10 to 15 knots with higher
gusts this evening. Winds will shift to the southwest overnight
behind the cold front and then to west by Thursday afternoon as a
secondary cold front passes through.
MS...Wind Advisory until midnight CST tonight for MSZ002>006-009-
TN...Wind Advisory until midnight CST tonight for TNZ003-004-020>022-
Area Forecast Discussion
National Weather Service Marquette MI
959 PM EST Wed Jan 18 2023
Issued at 958 PM EST WED JAN 18 2023
No significant changes have been made to the fcst this evening.
Water vapor imagery and RAP analysis show a very well-defined mid-
level low over the central Plains with pronounced mid-level dry slot
surging n thru MO. Ahead of the dry slot and within in a zone of
strong isentropic ascent/upper diffluence, mdt to hvy pcpn is
occurring across IA into northern IL. Lincoln, IL 00z sounding
showed a saturated column with precipitable water of 1.03 inches,
close to the record high value for mid Jan. At 850mb, winds were se
at 40kt with a dwpt of 5C. So, abundant moisture is advecting n with
A quick check of incoming 00z model guidance shows no surprises, and
the latest round of guidance is largely consistent with the last 6
to 12 hrs of model runs. Updates this evening slightly slowed the
onset of the synoptic snow. Impressive upper diffluence and a
healthy sweeping arc of isentropic ascent will spread snow n across
the fcst area on Thu. Still looks like most areas will see much of
the snow accumulation occur during a 6hr period, but after the heavy
snow passes, steady snow will linger thru Thu evening across
Marquette County. In that area, there will be lingering lake
enhancement with a pronounced upslope boost to snowfall as low-level
winds will be perpendicular to the terrain rise from sw of the city
of Marquette into the Huron Mtns.
.SHORT TERM...(This afternoon)
Issued at 1255 PM EST WED JAN 18 2023
Light lake-effect/upslope snow continues across the area this
afternoon as a low pressure from the Central Plains begins to lift
towards the Great Lakes region. As this happens, winds are expected
to become more northeast/easterly, and indeed we are beginning to
see this on the most recent radar imagery (as of this writing).
Thus, the light lake-effect/upslope snow may expand in coverage over
the western UP this afternoon (at the expense of coverage in the
east). That being said though, don`t expect much more than a dusting
this afternoon. With cloud cover and cool temps aloft hanging around
today, most places are looking to stay below freezing, save for near
the Lake MI shoreline.
.LONG TERM...(Tonight through Wednesday)
Issued at 453 PM EST WED JAN 18 2023
- Winter Weather Warning and Advisory in effect tonight through
- Localized heavier snowfall amounts expected along a Menominee,
Delta, Schoolcraft swath
- Localized heavier snow amounts across Marquette County in the
upslope northeast flow on backside
The main focus of the forecast period continues to be on
tonight/tomorrow`s winter storm. Impending storm system is currently
situated over eastern Kansas with precipitation field extending from
the Gulf northward across the Ohio Valley and Midwest. Meanwhile, a
well-defined dry slot can be seen pushing into eastern portions of
Kansas and Oklahoma on water vapor imagery.
Latest 12Z model runs continue to favor a northeastward track into
northern Illinois by tomorrow morning and onward through lower
Michigan by tomorrow evening. It will be a quick moving system with
best q-vector convergence concentrated across southern and eastern
portions of Upper Michigan. Short range deterministic models have,
however, shifted to a slower progression. So, any headlines have
now been held off until Thu 09Z (mainly south), overspreading the
remaining eastern counties after Thu 12Z. Opted toward a warning
for central and eastern portions of the UP with a Winter Weather
Advisory across the western counties. Latest models have been
highlighting a swath of especially higher snowfall totals across
Menominee, Delta, and Schoolcraft Counties with snow rates as high
as 1 to 2 inches per hour. This does seem a bit overdone, but
nonetheless would not rule out some localized snow totals in the 8
to 12 inch range over those counties during a period of enhanced
isentropic lift from Thu 12-18Z. And, Marquette County is
especially expected to overachieve with additional snow
accumulations in the upslope northeast flow on the backside. As a
result, did carry the warning across Marquette County through Fri
12Z with the rest of the area expiring at Fri 06Z. Farther west,
confidence is now high enough to include Gogebic, Ontonagon,
southern Houghton, and Baraga Counties in a Winter Weather
Advisory, and those could potentially be upgraded to warning with
future forecast issuances.
After the lingering lake effect snow on Friday morning, the
pattern will settle down through Saturday with weak ridging. Look
for temperatures to plummet into the low teens or lower on Friday
night though with any radiational cooling.
Further out, variability increases in long range models, but the
trend continues toward additional low snow chances from Monday
night through Tuesday with the next shortwave trough and
associated cold front.
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 648 PM EST WED JAN 18 2023
With abundant low-level moisture aided by ne flow across Lake
Superior, expect IFR cigs to persist tonight at IWD/CMX/SAW. On Thu,
low pres tracking ne to the Great Lakes will spread a band of snow
from s to n across Upper MI. Although the heaviest snow will impact
SAW, all terminals will likely see LIFR conditions. Expect
improvement to IFR by mid aftn at IWD and during the late aftn at
CMX/SAW. NE winds will be gusty to 20-30kt on Thu.
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 223 PM EST WED JAN 18 2023
Northeast to east winds increase to 20 to 30 knots across Lake
Superior tonight ahead of an approaching low pressure from the
Central Plains, eventually becoming gales up to 40 knots over the
western portion Thursday; in addition, northeast to east gale force
gusts up to 35 knots are possible Thursday afternoon into evening
over the eastern half, particularly near the Canadian border. As the
low pressure quickly pulls away Thursday night and Friday, expect
winds to weaken as they begin to slowly back to the north, becoming
20 knots or less by Friday. Expect the light winds to continue until
Saturday morning, when CAA ahead of a digging low pressure from
Canada brings southwest to west winds of 20 to 30 knots across the
west and north central lake. Winds look to die down to 20 knots or
less again late Saturday night/Sunday morning as slight WAA moves
back over the area due to the low passing over. Light winds continue
for the rest of the weekend and early next week until late Monday
into Tuesday, when a cold front from Canada brings more westerly
winds of 20 to 25 knots back across Lake Superior.
Some moderate freezing spray could be seen across the northern
portions of the lake Thursday and Thursday night.
Winter Weather Advisory from 7 AM Thursday to 1 AM EST Friday
Winter Storm Warning from 7 AM Thursday to 7 AM EST Friday for
Winter Storm Warning from 4 AM Thursday to 1 AM EST Friday for
Gale Warning from 7 AM to 7 PM EST Thursday for LSZ162-240>242-
Gale Warning from 4 AM to 3 PM EST Thursday for LMZ221-248-250.
...Updated Aviation Forecast Discussion...
Issued at 338 PM CST Wed Jan 18 2023
- Heavy snow will fall this evening and overnight in northeast
Nebraska. The heaviest snow will affect areas from Albion
through Norfolk, Wayne, and Tekamah. Travel will be very
hazardous in these areas.
- South of a David City to Fremont to Harlan line, much of the
heaviest precipitation will fall as a mix of sleet, freezing
rain, rain, and snow. For several areas including Omaha,
Council Bluffs, and Lincoln, this will result in lighter snow
amounts than previously forecast. Travel will be hazardous in
these areas due to ice and snow.
Regarding the first point above, the forecast for northeast
Nebraska remains largely on track. Have reduced snow amounts
slightly from the previous forecast owing to a bit of infiltrating
dry air, but still anticipate a lot of snow to pile up with the
heaviest amounts from Albion through Norfolk, Wayne, and
Tekamah...and into west central Iowa north of HWY 30. Bottom line,
very difficult travel with 6-12 inches of snow likely and a few
areas potentially getting a bit more. It`s worth noting too that
parts of central NE are now approaching 18 inches.
Now for the area near and south of a David City to Fremont to
Harlan line: Sometimes mother nature throws a curveball. Today
the curveball is in the form of warmer-than-expected temperatures
aloft. While the heavy precipitation is indeed falling in the
locations where it was expected, the fact is that locations near
and south of a line from David City to Fremont to Harlan are
experiencing much of that precipitation as freezing rain, sleet,
and rain in addition to the snow that was originally anticipated.
The end result will be hazardous travel conditions due to a mix of
ice and snow in these areas, but the snow that folks see...well
it`s not going to be as deep as I expected even just this morning.
Somedays 1 degree makes a huge difference and today is one of
those days. Frustrating to us as meteorologists who take great
pride in our work, but we also know when it`s time to update the
forecast. As the evening goes on, keep in mind that this is still
a solid winter storm and travel will be quite hazardous due to the
sleet and freezing rain in addition to the snow.
Issued at 255 PM CST Wed Jan 18 2023
The following features were noted in the upper air plots this
morning. At 850 mb there was a decent moisture feed from the Gulf
of Mexico, with dewpoints to 10 C or higher from OK and AR south.
The thermal gradient at 700 mb over the central Plains was not
overly tight, but will be increasing. A 12 hour height fall of 100
meters was observed at KAMA and a jetstreak of 140 knots at 300
mb was seen in the KMAF sounding. The 100 meter HFC max was
probably close to about 120 meters based on model initializations.
12Z model time/height sections depict peak Specific Humidity
values as high as 4 g/kg in the 850 to 700 mb layer in our area.
This moisture content with some instability and very strong
diffluence aloft should yield some snow amounts of over 8 inches
in the northern parts of our forecast area.
Closed mid tropospheric low will track from western KS early this
afternoon through southeast NE and southwest IA tonight, then to
near the WI/IA/IL border by Noon Thursday. Heaviest snow in our area
will be associated with the deformation zone and/or TROWAL (trough
of warm air aloft). TROWAL seems to be relative well depicted in
the 700 mb Theta-e (Equivalent Potential Temperature) field.
Water vapor imagery and radar loop show a dry slot punching into
the area from the south. Recent RAP output supports the area of
heaviest snow from western and central NE then to northeast NE.
But it also depicts a small area that will move eastward near the
NE/KS border (probably convective snow/sleet). We have made some
downward adjustments to snow forecast amounts from previous. We
have not see the high snow rates like those farther to the west.
Surface low at 2 pm was southwest of KSLN (Salina, KS). A warm front
extended eastward into southwest MO. Winds in our area were from the
east or northeast. The surface low should track northeast tonight.
As it does so, our winds will turn to the north or northwest and
increase. The surface low should be near the IA/IL/MO border by
12Z Thursday (6 am local time). The 500 mb low should have moved
to south central IA by that same time. Some light snow could
linger until about 9 am Thursday morning, but the bulk of
accumulating snow will have ended in our area well before then.
The period from Thursday afternoon through Friday night should be
mainly dry. A split flow pattern will be over the CONUS by Friday
night/Saturday, with a closed low in the southern stream. At this
time, it looks like about the southern half of the forecast area
will have a chance for light snow. The highest chances will be
along the KS border and the 12Z models were in decent agreement
with that. Other weak systems may bring a light snow Monday
afternoon and Monday night, then again toward Tuesday night. We
will take a closer look at those systems once the current system
has exited the area.
Look for highs in the 20s and 30s from tomorrow (Thursday) into
the mid part of next week. Lows will range from about the upper
single digits to around 20.
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 524 PM CST Wed Jan 18 2023
Still seeing the potential for mixed precipitation at KLNK/KOMA
for a couple more hours before becoming all snow. And should be
all snow at KOFK with heavy snow potential for a few hours.
IFR/LIFR conditions, but eventually becoming MVFR and possibly VFR
later in the TAF forecast. Northeast winds at or above 12 knots,
becoming northwest through time. Snow potential at KOFK 8-12
inches, and 2-4 at KLNK/KOMA, but even that might be on the high
side for these two locations since we`ve had such a mixed
precipitation event at the onset.
NE...Winter Storm Warning until 6 AM CST Thursday for NEZ011-012-
Winter Weather Advisory until 6 AM CST Thursday for NEZ052-053-
IA...Winter Storm Warning until 6 AM CST Thursday for IAZ043-055-056.
Winter Weather Advisory until 6 AM CST Thursday for IAZ069-079-
Area Forecast Discussion
National Weather Service Pocatello ID
751 PM MST Wed Jan 18 2023
.UPDATE...Slight update to the forecast to increase coverage area
for potential freezing fog farther north into the Island Park
area and a bit more of the Eastern Highlands in general. Have
already had a report of light freezing mist creating slick road
conditions near the Ashton area. AMM
.PREV DISCUSSION... /issued 144 PM MST Wed Jan 18 2023/
SHORT TERM...Tonight through Thursday night.
Next Pacific system approaching Idaho tonight into Thursday with
light snow expected with the heaviest in the southern hills and
Albion Mountains where 1 to 3 inches may fall with up to 6 inches
above pass level through Thursday. Elsewhere may see 1 to 2 inches
in the central mountains and maybe an inch or two in the Burley
region. Expect less than an inch through Thursday. Low
temperatures tonight mainly teens and 20s with some single digits
mountain valleys and highs Thursday in the 20s to low 30s across
the region. Light winds expected through the short term for the
most part at 10 knots or less.
LONG TERM...Friday through next Wednesday. Cut-off upper low drops
into the Four Corners area on Friday with ridging over the Pacific
Coast. By Saturday, models bring in a trough into the PAC NW thereby
flattening the upper ridge as the cut-off low ejects into the
Central Plains. As the upper trough in the Pacific advances into
Idaho Saturday night, snow will begin in the Central Mountains and
expand to the rest of the forecast area Sunday morning.
Deterministic models show this as a fast-moving trough, and should
not result in heavy snow accumulations. Latest NBM indicates a 20 to
40 percent chance of 2+ inches over the Caribou Highlands, Bear
River Range, the Big Hole Mountains and the Island Park area. The
trough should exit to the southeast and deepen over the Four Corners
region by Sunday night. Ensemble clusters show there is some
uncertainty in the westward extent of the upper trough Sunday and
Monday. The 00Z CMC ensembles favor a more westward positioning of
the trough, though the 12Z run appears to shift it further east.
Surface temperatures will likely be below normal with single digit
and below zero lows seen over much of the region. Hinsberger
AVIATION...Transient ridge traverses the region today. Fog/stratus
is seen on SAT imagery this morning across much of the Snake Plain
and in the Teton Valley. BYI remains near the western edge of the
stratus, but stratus should linger at PIH and IDA through most of
the afternoon/evening. Fog has been in and out of DIJ this morning,
but overall conditions should improve there. NBM indicates PIH may
lift to VFR this evening. IDA should remain LIFR, but may see some
improvement to MVFR early this evening. An upper trough will dive
into eastern Oregon tonight with snow beginning at BYI and SUN
around 11Z. HRRR visibility drops as low as 2SM with snow at BYI.