Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/11/24
Area Forecast Discussion
National Weather Service Burlington VT
1104 PM EST Wed Jan 10 2024
.SYNOPSIS...
As low pressure departs, gusty southwest winds will continue
tonight. Precipitation chances will be low overnight, although
widespread light snow in the western Adirondacks will result in
minor snow accumulations. On Thursday, scattered snow showers
will develop in much of the region, especially in the afternoon
and evening with light accumulations of a dusting to a few
inches. A more significant storm then will bring widespread snow
and gusty winds Friday night into Saturday.
&&
.NEAR TERM /THROUGH THURSDAY NIGHT/...
As of 1030 PM EST Wednesday...No big changes. Scattered showers are
winding down. Temperatures have been slow to decrease thus
far. Previous discussion follows.
Main story for tonight will be breezy and cooler conditions as
cold air advection filers in on westerly winds. Water vapor
imagery and RAP analysis shows a fast moving upper level trough
pushing northeastward across the region late this afternoon,
while double barreled sub-980 millibar low pressure gains
latitude over southern Quebec and northern Maine. The shortwave
trough is promoting scattered higher elevation snow and valley
rain showers but deep moisture is lacking; with relatively warm
cloud temperatures, not seeing much snow potential this evening
outside of the western Adirondacks. In that region, better
moisture is present thanks to Lake Ontario and west-southwest
winds and an inch or so of new snow is possible. As freezing
levels fall this evening, any precipitation should trend towards
snow across the region.
For tomorrow, after a quiet start to the day, snow showers will
blossom ahead of an open wave with a weak surface reflection
that is currently over the Midwest. While the system will be on
a weakening trend, broad lift and favorable thermal profiles
should promote good snow growth. Not looking at the most fluffy
snow as 850 millibar temperatures would ideally be a bit lower,
but certainly not a wet snow either. With westerly low level
flow, the western slopes of the Greens should do fairly well
with up to a few inches of snow accumulating during the late
afternoon and evening. If Froude numbers end up more blocked
than currently expected, amounts could be a bit a bit higher
expanding back across the Champlain Valley and relatively
limited east of the Greens. Temperatures will peak in the low to
mid 30s in the valleys and sub-freezing elsewhere;
precipitation will be all snow. Precipitation will gradually
subside overnight in the western upslope areas of the high
terrain as surface high pressure slides in from the west. Little
or no additional snow is expected after midnight tomorrow.
&&
.SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/...
As of 323 PM EST Wednesday...Quiet weather returns on Friday as
shortwave ridging briefly skirts across the area. Partly sunny
skies and light winds should be the rule with a broad increase
in high clouds toward evening as highs top out in the upper 20s
to mid 30s.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
As of 323 PM EST Wednesday...A return of impactful weather is
still on track for Friday night into Saturday evening as another
rapidly deepening system tracks into the Great Lakes on the
front end of a meridional polar trough slowly digging southward
across the Central/Northern Plains. This system will take on
similar characteristics to last night`s system, with a burst of
warm frontal snows transitioning to mixed rains/snows into
Saturday morning. Gusty east/southeast winds are also expected
in favored downsloping locales, though the magnitude this time
around looks to be slightly less - perhaps 40 to 50 mph at first
look. Early snow progs suggest a 1-3" event for the Champlain
Valley and 3-7" elsewhere with locally higher totals in excess
of 8" in the High Peaks region of the Adirondacks where some
southerly upsloping component will be present. Mixed snows/rains
then taper to snow showers by Saturday evening onward with some
lake effect response in the L. Ontario snowbelts as
temperatures cool back to more seasonal norms. Some light
additional accumulations will be possible, especially downwind
of L. Ontario and the higher terrain. Post-frontal southwesterly
winds are likely to trend quite gusty in the SLV during the
evening as well, where gusts in the 40-50 mph range will be
possible.
Thereafter, on and off chances for snow showers/sct. flurries
will continue into the early and middle portions of next week as
the aforementioned longwave trough slowly settles across the
eastern third of the nation and weak shortwave features traverse
the mean westerly flow. Some linger lake effect snows may also
be possible east of Lake Ontario. There is yet another system
progged to develop across the eastern seaboard/western Atlantic
on the front end of the main trough toward the middle of next
week, but the latest trends in deterministic guidance have been
to keep the main impacts of this feature to our south. Mean
ensemble solutions, including the National Blend concur and
other than the scattered snow showers/flurries mentioned above,
no large-scale impactful weather is forecast into Wednesday.
Temperatures should settle into a seasonal mid-winter regime
during this period with daily highs in the 20s and lows in the
single digits/teens.
&&
.AVIATION /00Z THURSDAY THROUGH MONDAY/...
Through 00Z Friday...A general trend from VFR/MVFR to all MVFR
is expected from 00-03Z with ceilings the main contributor to
flight restrictions. IFR vsby snow at KSLK persists through
01-03Z as well, but otherwise no precipitation is expected
through the overnight. Winds will be the bigger aviation
concern, becoming gusty from the WSW at 20-28kts within the next
couple of hours, and not abating until after 12Z. Locally
around KSLK LLWS will additionally prevail through 06Z with
summits winds around 40-50kts.
Outlook...
Thursday Night: Mainly VFR, with areas MVFR possible. Isolated
SHSN.
Friday: VFR. NO SIG WX.
Friday Night: Mainly VFR, with areas MVFR and IFR possible.
Strong winds with gusts to 40 kt. Definite SN.
Saturday: Mainly MVFR, with local IFR possible. Windy with gusts
to 35 kt. Definite RA, Definite SN, Chance SHRA.
Saturday Night: Mainly VFR, with local MVFR and IFR possible.
Windy with gusts to 35 kt. Chance SHSN, Likely SN.
Sunday: Mainly VFR, with local MVFR possible. Chance SHSN.
Sunday Night: Mainly VFR, with local MVFR possible. Slight chance
SHSN.
Martin Luther King Jr Day: MVFR. Slight chance SHSN.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...None.
NY...None.
&&
$$
SYNOPSIS...Kutikoff
NEAR TERM...Kutikoff/Neiles
SHORT TERM...JMG
LONG TERM...JMG
AVIATION...Lahiff
Area Forecast Discussion
National Weather Service Duluth MN
536 PM CST Wed Jan 10 2024
.KEY MESSAGES...
- Lake effect event will continue through tonight and into tomorrow
for the North Shore with Winter Weather Advisories and Warnings in
effect until Thursday morning.
- Multiple snow chances heading into the weekend.
- Arctic blast with dangerous wind chills expected heading into next
week. Wind Chill headlines will be needed in future cycles.
&&
.DISCUSSION...
Issued at 412 PM CST Wed Jan 10 2024
Short Term:
A shortwave approaching from Canada has induced cyclogenesis of a
surface low straddling the Manitoba/North Dakota border over the
past couple days. Through the next 36 hours it’ll slowly move
southeastward while weakening in the process before exiting our
region late on Thursday. In the meantime, this low pressure will
induce easterly flow off of the still warm and unfrozen Lake
Superior. With cold air aloft and the warm lake, we are expecting a
moderately substantial lake event to unfold through tomorrow across
the North Shore. Weak ascent from the approaching shortwave has
already given way to a snowy morning across NE Minnesota and NW
Wisconsin. Through this morning we’ve already seen snowfall rates
pushing 0.25-0.5” from the Iron Range into the Duluth/Superior area.
More recently the heavier rates have begun to push further NE up the
North Shore. This trend will continue through the afternoon and into
this evening as wind vectors turn a tad more southeasterly. In the
process, not only will the length of the fetch increase but the
nature of the lake effect will become more linearly banded rather
than the current multi-banded structure.
The result of this will decrease the widespread nature of the
snowfall but instead focus it more for greater impacts. This means
that into this afternoon and continuing through the night, we are
expecting hazardous conditions from Silver Bay and extending towards
Two Harbors. Snowfall rates will increase and reach in excess of
0.75”/hr with near whiteout conditions at times. By the time it’s
all said and done, there’s high confidence(75-90%) that snowfall
totals will be in the 6-11” range where the band parks tonight
somewhere between the aforementioned cities. Totals will decrease
moving away from the band but isolated totals nearing 6” are
possible (30-50%) from Duluth towards Grand Marais. The band will
wind down Thursday morning as winds begin to veer away even further
north towards the Canadian Border.
Extended Range:
Into the weekend, the active pattern will continue with multiple
shots for snow possible for the CWA. The first event comes later on
Thursday but is of lower confidence (20-30%). As the low pressure
that’s currently near the Dakotas moves towards Lake Superior by
Thursday morning, there’s a chance it could reform into a mesolow of
sorts. This solution was shown by the 18z HRRR that it could
reinforce/reform that lake effect band across the North Shore. If
this does occur another few inches could be possible across the
northern half of North Shore through Thursday night.
Following this, a more widespread snowfall event could unfold as an
inverted trough signature appears over our area attached to a very
anomalous storm moving across the Southern Great Lakes. This
inverted trough feature which multiple CAMs are picking up on would
allow for snowfall to reach up to the MN/WI border. Confidence in
this feature is on the low end (25-35%) as global models are not in
agreement with CAMs. They have a more southerly track tied with
weaker inverted trough meaning no lift in our CWA and no snow as a
result. North/south trends of the main storm well to our south will
have to be watched moving forward.
Cold Air Threat:
Following close behind the storm to our south on Friday will be a
1040mb high pressure coming out of Canada. High latitude blocking
over the last few days will push an extremely cold airmass directly
from the Arctic region into Canada and eventually into the CONUS by
late this weekend. Temperatures will be 15-30 degrees below normal
starting on Sunday and until Tuesday at the earliest. Sunday and
Monday look to be the worst of the upcoming stretch.
A strong pressure gradient force will arise due to the 1040+ high to
our west and the existing 975mb to our east. Our region will be
stuck in the middle and as a result see elevated wind gusts touching
30+ mph. Strong wind gusts and temperatures below zero will create
dangerous wind chill values well in excess of
-15F. We will need wind chill headlines in the coming forecasting
cycles once we get a bit more clarity on the arrival time and
magnitude of the cold air.
&&
.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 532 PM CST Wed Jan 10 2024
Continued poor flight conditions with high spatial variability
in the conditions. Model guidance is divergent on how to handle
ceilings, visibilities, and snow. Overall, a fairly low
confidence forecast in the specifics, but generally conditions
get a little worse overnight and then improve some Thursday
afternoon. Winds switch from east to west through the period
with gusts remaining below 15 kt.
&&
.MARINE...
Issued at 412 PM CST Wed Jan 10 2024
Easterly winds will lead to building waves along the North Shore
tonight into Thursday, mainly from Two Harbors to Grand Marais
where waves of 2 to 5 feet will be possible. These waves will
also be possible across the Outer Apostle Islands as well. Winds
will be around 20 knots or less. Small Craft Advisories have
been issued for the areas where the highest waves are expected. Light
winds are expected by Thursday evening before turning
northeasterly ahead of strengthening low pressure to our south.
Winds Friday will increase to 20 to 30 knots with gusts to 35 to
40 knots. These winds will generate waves of 6 to 10 feet
around the head of the lake and along the South Shore.
Additional headlines will be needed starting on Friday and
extending into the weekend.
Lake effect snow bands will lead to areas of reduced
visibilities at times. A stronger band is expected to develop
and affect areas along the North Shore from Two Harbors to
Taconite Harbor tonight and tomorrow before weakening.
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...Winter Storm Warning until 6 PM CST Thursday for MNZ020.
Winter Weather Advisory until 6 PM CST Thursday for MNZ037.
WI...None.
MARINE...Small Craft Advisory from 10 PM this evening to 10 PM CST
Thursday for LSZ141>143.
Small Craft Advisory from 10 PM this evening to 4 PM CST
Thursday for LSZ150.
&&
$$
DISCUSSION...BJH
AVIATION...Wolfe
MARINE...BJH
Area Forecast Discussion
National Weather Service Goodland KS
707 PM MST Wed Jan 10 2024
.KEY MESSAGES...
- Arctic air moves into the area on Thursday with patchy
freezing fog in the morning and a chance for light snow in the
afternoon and evening.
- Arctic front briefly retreats on Friday with highs in the
teens in eastern areas and 30s in western areas.
- Several days of bitterly cold temperatures and life
threatening wind chills begins Friday night and continues
through Monday. Occasional light snow will also occur during
that time, but significant accumulations are not currently
anticipated.
&&
.UPDATE...
Issued at 701 PM MST Wed Jan 10 2024
RAP and HRRR soundings are indication the potential for some
freezing drizzle to occur around frontal passage time (late
morning into the early afternoon). The main uncertainty with
this is the coverage and duration as precipitation should
quickly turn over to light snow. However, if the dry air aloft
does linger a bit longer than a glaze of ice is possible.
Other changes to the forecast were to increase temperatures a
bit tonight due to the southerly winds and the increase in mid
to high clouds. Also did lower temperatures a bit into Friday
morning due to guidance suggesting stronger CAA and clouds
clearing a bit quicker.
&&
.SHORT TERM /THROUGH FRIDAY NIGHT/...
Issued at 215 PM MST Wed Jan 10 2024
Initial front arrives tomorrow morning with cold air slowly
filtering in from the northeast. Might see some patchy freezing
fog along/behind the front in the morning. Highs will range from
the teens in southwest Nebraska to the upper 20s in northeast
Colorado. Next shortwave trough moves through in the afternoon
and evening hours bringing a chance for light snow. Somewhat of
a disconnect from the short term hi-res models which show little
to no snow and the global deterministic models which still show
1 to 3 inches in eastern areas. Not ready to completely remove
snow chances, but did lower amounts with only an inch or so
mainly in Norton and Graham counties in northwest Kansas. As
skies clear Thursday night temperatures will drop to around zero
and wind chills to around 15 below. Wind Chill Advisory is on
track and no changes made.
The Arctic air will try to retreat eastward on Friday and
perhaps make it as far as Highway 27 in northwest Kansas.
Temperatures east of the front in the Arctic air will remain in
the teens while west of the front temperatures will warm into
the upper 20s to lower 30s. However the Arctic front makes a
renewed surge southward Friday night as another shortwave trough
moves into western Nebraska. This will begin the extended
period of bitterly cold temperatures as lows by Saturday
morning will be around 5 below and wind chills around 20 below.
May see some light snow late Friday night north of Interstate 70
with the shortwave. However, accumulations of less than one
inch currently anticipated.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
Issued at 215 PM MST Wed Jan 10 2024
Arctic air mass will be firmly entrenched across the region
Saturday through Monday, then a slow moderation of temperatures
begins on Tuesday. Occasional light snow will occur, with the
best chances of accumulating snow late Saturday night through
Sunday morning where an inch or two will be possible. However,
significant accumulation of snow is not expected during this
outbreak. The bigger story will be temperatures and life
threatening wind chills. Highs will be in the single digits
above zero on Saturday and single digits below zero on Sunday,
with lows 10 to 15 below Saturday and Sunday nights. Should
have no problem reaching Wind Chill Warning criteria of 25 below
or colder Sunday and Monday mornings, with Wind Chill Advisory
criteria currently forecast for Saturday and Tuesday mornings.
So will continue the long Wind Chill Watch for now and begin to
chop away at it day be day once warnings/advisories are
determined.
&&
.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 408 PM MST Wed Jan 10 2024
VFR conditions are forecast to start the period. The main focus
will be on a incoming cold front which may bring some fog and
LLWS to the area around sunrise. Light snow will then develop
early afternoon near the KGLD terminal and then spread east
through the rest of the period. Winds will also become breezy
around 30 knots which may bring some blowing snow potential
as well. Guidance is just now starting to hint at some fog with
the frontal passage, so will continue to monitor to see if the
signal continue.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...Wind Chill Advisory from 7 PM MST /8 PM CST/ Thursday to 8 AM
MST /9 AM CST/ Friday for KSZ001>004-013>016-027>029-041-
042.
Wind Chill Watch from Friday afternoon through Tuesday morning
for KSZ001>004-013>016-027>029-041-042.
CO...Wind Chill Advisory from 7 PM Thursday to 8 AM MST Friday for
COZ090>092.
Wind Chill Watch from Friday afternoon through Tuesday morning
for COZ090>092.
NE...Wind Chill Advisory from 7 PM MST /8 PM CST/ Thursday to 8 AM
MST /9 AM CST/ Friday for NEZ079>081.
Wind Chill Watch from Friday afternoon through Tuesday morning
for NEZ079>081.
&&
$$
UPDATE...Trigg
SHORT TERM...JDK
LONG TERM...JDK
AVIATION...Trigg
Area Forecast Discussion
National Weather Service Green Bay WI
855 PM CST Wed Jan 10 2024
New Information added to update section
.UPDATE...
Issued at 840 PM CST Wed Jan 10 2024
Evening updates included the following:
- Increased snowfall amounts over Door County and issued a Winter
Weather Advisory from midnight through 10 am Thursday.
Combination of synoptic snow with the incoming short-wave trough
and lake-enhancement in association with a meso-low will lead
to higher accumulations.
- Issued a Special Weather Statement for travel concerns with
tonight and Thursday morning`s snow.
- Added mention of possible near-blizzard conditions in the Fox
Valley and lakeshore for the Friday-Saturday morning winter
storm, where gusts to 45+ mph and a more powdery snow support
potential for considerable blowing and drifting.
&&
.KEY MESSAGES...
- A round of light snow is expected tonight into Thursday
morning. Most locations will see 1 to 3 inches of snow except
for snowfall totals under an inch over far northern Wisconsin.
Accumulations of 3 to 5 inches, locally higher, are expected
over Door County, where some lake-enhancement appears imminent.
- Another well-organized weather system looks to impact the
region Friday into Saturday, bringing heavy snow and strong
winds. Probability of at least 6 inches of snow ranges from
70-90% across the Fox Valley and lakeshore areas. Probability of
wind gusts of at least 40 mph range from 40-80% for this same
area.
- Much colder temperatures will move into the region after the
strong system departs on Saturday. Wind chills may become
dangerously cold each morning from Sunday through Wednesday.
&&
.DISCUSSION...
Issued at 303 PM CST Wed Jan 10 2024
Short Term...Tonight and Thursday
The latest RAP analysis and satellite/radar imagery show a weak
high pressure ridge axis moving across western Wisconsin. Despite
the surface ridge, widespread overcast conditions exist across the
region. Looking upstream, broad troughing is moving east across
the northern and central Plains while a relatively stronger
shortwave is tracking across Nebraska. This compact wave is
looking rather impressive on satellite imagery. As this
troughiness and the aforementioned shortwave move across the
region, snow trends and potential impacts are the main forecast
concerns.
Precip and Snowfall Trends: Warm advection will increase this
evening ahead of the mean trough coming in from the west. Radar
returns are expanding over Minnesota and far northwest Wisconsin
and this trend should continue for the rest of the afternoon
before spreading across north-central Wisconsin this evening. This
should lead to light snow expanding this evening with a half
inch possible by midnight.
While that is ongoing, precip intensity is expected to increase in
the comma head of the compact shortwave across Iowa. This comma
head of higher precip/snowfall rates is then expected to lift
northeast across southwest, east-central, and far northeast
Wisconsin overnight. While precip intensity is expected to weaken
somewhat as it moves into east-central WI, upwards of a half inch
per hour snowfall rates appear possible over the Fox Valley to far
northeast WI overnight, which will continue into the Door
Peninsula on Tuesday morning. Low level convergence and a weak
lake influence may also locally increase snowfall rates further.
As a result, most of the region, with the exception of far
northern WI, will see 1-3 inches of snow. The highest snowfall
looks to occur over Door County. Hourly precip amounts suggest the
heaviest snow should fall over the Fox Valley prior to the morning
commute, though slippery conditions will likely linger into the
6-8 am hour. Because snowfall will be diminishing in intensity,
will hold off on issuing a Winter Weather Advisory. Also don`t
like complicating headlines with a stronger system impacting the
region on Friday.
After the snow moves out on Thursday morning, overcast conditions
with light snow and flurries could persist through the day over
far northern WI.
Temperatures: Small swings in temperatures are expected over the
next 24 hours due to cloud cover and precip. No significant
changes were made to the previous forecast.
Long Term...Thursday Night Through Wednesday
The main focus for the long-term forecast period is an impactful
system that will bring significant snowfall and strong winds to
much of the Midwest. Following Thursday`s fast-moving system,
another piece of closed upper-level energy will make its way up
into the Great Lakes region, placing an ~978 mb surface low
over the Ohio River Valley. The dynamics with this system look
very similar to those of the departing system from earlier this
week, although colder temperatures suggest higher snow
accumulations this time around. A Winter Storm Watch is currently
in effect for every county in the CWA excluding the northwestern
counties of Vilas, Oneida, and Lincoln given a trending
northwesterly track for the driving surface low.
Precipitation... Confidence is increasing in an impactful snowfall
event for most of the forecast area Friday through Saturday.
Temperature profiles suggest that the bulk of the precip
associated with this system will fall as snow, although warm
lake temperatures may allow for some rain or heavier snow to mix
in along the lakeshore Friday evening. Probabilities for exceeding
6 inches of snowfall are averaging around 80 to 90% in the Fox
Valley to lakeshore areas, increasing from the 50 to 60% threshold
shown in previous runs of the NBM. Locally highest amounts look to
be confined to the lakeshore with some lake/bay enhancement
possible with an easterly/northeasterly wind component. As winds
back to the north on the back end of the departing surface low,
colder temperatures will be advected further south, suggesting a
transition to all snow especially along the lakeshore and near
the bay. Snow is likely to become lighter and accumulate faster around
this time as snow ratios increase due to the aforementioned cold
air advection.
Winds... Strong northeast to northwest winds are expected to bring
additional impacts to the forecast area Friday night into Saturday
morning. The pressure gradient on the back end of the surface low will
tighten across most of Wisconsin as it exits to the northeast. A
lingering area of high pressure hovering across the US/Canada
border has forced an enhanced area of pressure falls across the
Midwest during this time, leading to the NBM trending higher for
both wind gusts and snow accumulations. Current model guidance has
suggested around a 70 to 80% chance of exceeding storm force wind
gusts of 35 mph, although gusts in excess of 40 to 45 mph are
likely near the lakeshore. A combination of gusty winds and light
snow falling during this time may create significantly reduced
visibilities and hence hazardous travel.
Temperatures... Temperatures following the passage of this system
are expected to drop quickly, with low temperatures in the single
to double digits below zero expected for much of the forecast
area to begin the week. Wind chill headlines may be possible
during this time, as it wouldn`t take much wind to quickly tank
wind chills at these temperatures. Many locations across the
forecast area look to approach Wind Chill Advisory criteria of
-20 degrees or colder.
&&
.AVIATION...for 00Z TAF Issuance
Issued at 545 PM CST Wed Jan 10 2024
A weak short-wave trough was already producing patchy light snow
over parts of north central and far northeast WI early this
evening, but a stronger short-wave will bring more concentrated
snow to the southeast half of the forecast area overnight into
early Thursday. Much of the area will see 1-3 inches of snow, with
the highest amounts likely occurring in the Fox Valley, bayshore
and lakeshore areas. Meso-models show a more intense band setting
up over the Door Peninsula around 12z/Thu, so locally higher
amounts are plausible there. Ceilings will lower this evening,
with visibilities falling to IFR/LIFR as the steadier snow
overspreads the region late this evening/overnight. The worst
conditions are expected to occur in the Fox Valley and lakeshore
areas between 08z-14z/Thu.
Improving conditions will generally occur after 14z Thursday.
Ceilings, however, will likely remain MVFR through the TAF
period.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
Winter Storm Watch from Friday morning through Saturday morning
for WIZ011>013-019>022-030-031-035>040-045-048>050-073-074.
Winter Weather Advisory from midnight tonight to 10 AM CST
Thursday for WIZ022.
&&
$$
UPDATE.........Kieckbusch
DISCUSSION.....MPC/Goodin
AVIATION.......Kieckbusch
Area Forecast Discussion
National Weather Service Northern Indiana
724 PM EST Wed Jan 10 2024
.SYNOPSIS...
Issued at 336 PM EST Wed Jan 10 2024
Light snow along the Michigan stateline late tonight through
Thursday morning will bring about 1 to 2 inches of snow. A strong
winter storm is expected Friday and Saturday followed by a blast
of Arctic air.
&&
.SHORT TERM...(This Evening through Thursday)
Issued at 336 PM EST Wed Jan 10 2024
Key message:
*Light snow along the Michigan stateline late tonight through
Thursday morning. 1 to 2" is expected.
A trough digging in through Nebraska today accelerates east and taps
into somewhat improved mid-level moisture through time. A period of
moderate snow occurs late tonight and lingers through the morning
commute Thursday. Snow totals near 1 inch, are favored north of US
30, with totals closer to 2 inches along and north of the Michigan
state line. Snow duration will only be about 6 to 9 hours, with a
reasonably deep DGZ (5k FT) for a time before drying and weakening
omega. Confidence is high for totals of Trace to 2 inches thanks to
the short duration, modest forcing, and strong model agreement.
&&
.LONG TERM...(Thursday Night through Wednesday)
Issued at 336 PM EST Wed Jan 10 2024
Key Messages:
*Starting Friday, a winter storm brings rain, snow, wind, followed
by dangerous cold.
*A winter storm watch is in effect for counties along the Michigan
state line, excluding Ohio.
A winter storm watch was issued this afternoon for counties along
the Michigan State line (aside from Ohio) where confidence is
greatest on the probability of impactful accumulating snow,
paired with gusty wind. Exact snow totals are still questionable
(as described below) but this watch area has a reasonable chance
of seeing 6" of snow. Confidence wanes for Hillsdale, Branch,
LaGrange and Steuben, where some solutions favor more rainfall vs
snow (I am skeptical). Those outside of the watch should not let
their guard down: strong wind paired with even small snow amounts
will be problematic by Friday night.
High resolution and short-term model guidance is beginning to take a
stab at the incoming winter storm. Generally speaking, these
solutions have erred on the warmer, rainy, side of the equation.
This is in contrast to the long-range models which have maintained
their course. The in- house National Blend takes into account
these warmer solutions, as does WPC. At the moment, I am very
cautious about these warm solutions.
Modest experience and pattern recognition yields the following
concerns with this system: I am very skeptical of the high
resolution models that attempt to bring the warm front north of
Hillsdale county. Though I will concede that there is not a blocking
high pressure to the north with this current forecast scenario.
Secondly, with this strong of a system and the anticipated influx of
cold air, a dramatic cooling of the atmospheric column should occur,
aiding in a faster transition to snow (from rain) for those on the
west and northern side of the surface low. It should be noted that
ensembles have a discrepancy as great as 150 miles for the surface
low track. Therefore, I`m leaning more heavily on the consistent
long-range models for this forecast cycle.
It is important to note that at this moment, the whole forecast area
is not subject to a "blockbuster" snowfall. That is risk is perhaps
maximized toward northwest IN and southwest MI. I say "perhaps"
because of the uncertainly with the aformentioned shorter range
models. Furthermore, a wetter (lower) snow-to-liquid ratio at onset
will automatically result in compaction and lower measured totals.
Do not miss out on the higher confidence forecast items like 35 to
45 mph wind gusts Friday night and Saturday, followed by brutally
cold air Saturday night. Wind gusts of at least 30 mph are expected
across the whole forecast area, but a corridor of wind gusts near 45
mph are plausible in a corridor from Defiance to Marion, IN. The
coldest days of the week will be Monday and Tuesday with high
generally in the single digits with lows Monday morning and Tuesday
morning below zero.
Lake effect snow showers persist on the eastern shore of Lake
Michigan Sunday through at least midweek. Small daily accumulations
are expected, limited by a DGZ "on the floor" with equilibrium
levels barely reaching 5,000 FT.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday Evening)
Issued at 647 PM EST Wed Jan 10 2024
A clipper type of system was just upstream over northern IL. This
system will race across the area tonight and bring a brief round
of snow. Considering the dynamics of this system, am inclined to
lower VSBYs at SBN down (briefly) to 1/2SM SN from 06Z to 10Z
given the latest HRRR and other models (as well as obs & trends).
Will wait until after 00Z package starts coming in to make any
changes. Otherwise, large area of fuel-alternate MVFR conditions
should prevail for most of the period.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...Winter Storm Watch from Friday morning through Saturday
afternoon for INZ005>007-103-104-203-204.
MI...Winter Storm Watch from Friday morning through Saturday
afternoon for MIZ078>081-177-277.
OH...NONE.
LM...Small Craft Advisory until 10 PM EST this evening for LMZ043-046.
Storm Watch from late Friday night through Saturday afternoon
for LMZ043-046.
&&
$$
SYNOPSIS...Brown
SHORT TERM...Brown
LONG TERM...Brown
AVIATION...Skipper
Visit us at www.weather.gov/iwx
Follow us on Facebook...Twitter...and YouTube at:
www.facebook.com/NWSNorthernIndiana
www.twitter.com/nwsiwx
www.youtube.com/NWSNorthernIndiana
Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
724 PM PST Wed Jan 10 2024
.SYNOPSIS...10/110 PM.
A low pressure system will move through interior California
tonight into into Thursday, bringing strong winds, cold
temperatures, mountain and pass level snow and a chance for light
rain. Best chances for snow will be late tonight into early
Thursday over the Grapevine and northern Ventura mountains where
significant blowing and drifting snow may cause near zero
visibilities and very hazardous travel. High surf and coastal
flooding are possible through Friday at west and northwest facing
beaches.
&&
.SHORT TERM (WED-SAT)...10/147 PM.
A very cold upper level system is dropping through the interior
portion of the West Coast. As is typical with systems that take
this inside track it will not have a lot of moisture with it but
what moisture there is will fall as snow at lower than usual
elevations. There is also a very strong core of winds associated
with this system (140kt at 250mb) and we`re already starting to
see winds picking up over the coastal waters and in some of the
mountains. The most impactful part of the storm will come through
the area tonight into Thursday morning. Winds will be ramping up
quickly over the mountains tonight and expect widespread warning
level winds there, possibly up to 80 mph in the most favored
higher elevation areas of the western San Gabriel mountains and
near the Kern County line. Winds will filter down into portions
of the valleys and coastal areas, though not as strong as in the
mountains. It`s a very tricky forecast for the wind speeds,
especially at lower elevations where some areas protected from the
northwest winds could see very little wind while other more
exposed areas, especially through the Santa Clarita and San
Fernando Valley, could see very strong winds at times, especially
if wave conditions develop. High wind warnings are in effect
across all the mountains and some valleys and wind advisories are
in effect for many other areas. Winds are expected to drop off
later Thursday.
The precipitation portion of the system will be on the lighter
side but still potentially very impactful. Given the colder than
usual temperatures associated with this storm as a result of the
storm track, snow levels will lower rapidly tonight and drop to as
low as 3500 feet. Because of the inside track the storm is taking
and the resulting downsloping/drying effect to the lee of the
mountains, precip will likely be confined to SLO/SB Counties and
the mountains of Ventura and LA Counties. Can`t completely rule
our a stray shower elsewhere but amounts would be negligible.
Overall precip amounts expected to be a quarter inch or less.
However, the upslope flow developing on the north facing mountains
from the Grapevine area into northern Ventura County could
generate briefly moderate to locally heavy snow in those mountains
with accumulations up to 2-5 inches. Latest HRRR and HREF models
continue to indicate hourly rates approaching a third of an inch
per hour in that area between 3 and 6 am Thursday, likely the most
impactful period for Interstate 5 over the Grapevine.
Accumulations of those amounts historically result in delays and
even temporary closures to that highway and other roads in the
area.
Temperatures tonight will be very tricky as the cold air moves in
rapidly while at the same time winds are increasing. Wind chills
could drop below zero in some of the coldest mountain areas
(covered by the Winter Storm Warning). Lower elevations will be
quite cold as well though actual overnight lows will be largely
dependent on winds as temperatures in windier areas will be
somewhat modified while wind protected areas will be very cold.
Opted to not issue any freeze hazards at this time due to the
mixing but there likely will be pockets of near to sub freezing
temps tonight at protected lower elevation areas.
Thursday night into Friday will likely be even colder as the winds
die down and clouds clear following the storm passage. Could see
places like the Antelope Valley dropping into the high teens and
some coastal valleys in the 20s to low 30s. May need numerous
frost/freeze hazards for Thursday night.
A slow warming trend Friday and Saturday with overall quiet
weather and clear skies but still quite cold at night.
.LONG TERM (SUN-WED)...10/154 PM.
Another inside slider system comes through Sunday into early
Monday. Many of the ENS ensembles have some light precip across
much of the area while most of the GEFS solutions take the system
too far east to generate any precip locally. Just going with the
NBM pops for now which basically keeps rain chances across SLO/SB
Counties and the mountains. Likely some brief gusty northwest
winds following that system but otherwise dry weather with slowly
warming temperatures into next week but remaining mostly in the
60s with still chilly morning lows.
&&
.AVIATION...11/0320Z.
At 2345Z, there was no marine layer or inversion at KLAX.
Moderate confidence in the current forecast. KPRB, KSBP, and KSMX
will likely vary between MVFR and VFR conditions as light rain
continues to spread into the area. At the remaining sites, there is
a 30% chance of BKN015-BKN025 cigs 04Z-15Z Thur. Winds speeds may
be 5-10 kts higher than forecast during peak winds. Moderate to
strong low- level wind shear and turbulence is possible at all
terminals after 06Z, especially over the higher terrain from Santa
Barbara county to Los Angeles county.
KLAX...There is a 30% chance of BKN015-BKN025 cigs 06Z-15Z Thur.
There is an 80% chance of moderate to strong low- level wind shear
and turbulence from 06Z Thur. North wind gusts of up to 30 kts
are possible from 06Z-18Z Thur. No significant east winds are
expected.
KBUR...After 06Z Thur, there is a 30% percent chance of
BKN015-BKN025 cigs. There is an 90 percent chance of moderate to
strong low-level wind shear and turbulence 06Z-18Z Thur.
&&
.MARINE...10/155 PM.
High confidence in the current forecast. Higher confidence in the
forecast for winds relative to seas. Widespread Small Craft
Advisory (SCA) conditions are expected this evening and
continuing into Thursday. The chances for Gales will increase
today from a 40-50% chance to a 60-80% chance by this evening and
continue through Thursday morning. The highest chances are for the
waters south of Point Sal to San Nicolas Island and west of the
Channel Islands, while the lowest chances are for the waters
nearshore along the Central Coast and inner waters closest to
shore between Point Mugu and San Mateo Point.
Winds will slowly diminish and seas will gradually subside from
early Thursday through Friday. There is a high-to-likely (50-70
percent) chance of SCA conditions through Thursday afternoon and
night, especially due to SCA seas. Winds and seas could increase
again over the weekend.
Due to the large swell and steep wind waves, west and northwest
facing harbor entrances could experience very hazardous conditions
with large breaking waves.
&&
.BEACHES...10/157 PM.
A large northwesterly swell will build through tonight, and high
surf will develop again on all west and northwest facing shores.
The latest swell guidance suggest that sets to 10-15 feet are
likely on the Central Coast by this afternoon, peaking on
Thursday morning at 12-17 feet. To the south at Los Angeles and
Ventura County beaches, surf heights of 5-10 feet are expected,
peaking on Thursday.
With higher astronomical high tides from 6.8 feet to 7.3 feet
Thursday morning, minor coastal flooding is likely around the
times of the morning high tide. The large swell combined with a
locally generated short-period swell produced by expected gales
over the coastal waters should result flooding of normally dry
areas, such as parking lots and walkways around the morning high
tides.
Beachgoers are advised to remain off rock jetties and NEVER turn
their back to the ocean. Every set of waves has a much higher wave
embedded within that has a potential to sweep people off jetties
and shorelines.
&&
.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory in effect until noon PST Thursday for zones
38-345>348-350-354>358-366>368-371-374-548. (See LAXNPWLOX).
High Wind Warning in effect until noon PST Thursday for zones
87-88-349-351>353-362-369-370-372-373-375-376-379>383-549-550.
(See LAXNPWLOX).
High Surf Advisory in effect until 3 PM PST Thursday for
zones 87-362-366. (See LAXCFWLOX).
Coastal Flood Advisory in effect from 4 AM to noon PST
Thursday for zones 87-354-362-366. (See LAXCFWLOX).
Coastal Flood Advisory in effect until noon PST Thursday for
zones 340-346. (See LAXCFWLOX).
High Surf Advisory in effect until 9 AM PST Friday for zones
340-346. (See LAXCFWLOX).
High Surf Advisory in effect until 3 AM PST Friday for zone
354. (See LAXCFWLOX).
Winter Storm Warning in effect until noon PST Thursday for
zones 377-378. (See LAXWSWLOX).
PZ...Gale Warning in effect until 3 AM PST Thursday for zone 645. (See LAXMWWLOX).
Gale Warning in effect until noon PST Thursday for zones
650-655. (See LAXMWWLOX).
Gale Warning in effect until 9 AM PST Thursday for zone 670. (See LAXMWWLOX).
Gale Warning in effect until 4 PM PST Thursday for zones
673-676. (See LAXMWWLOX).
&&
$$
PUBLIC...MW
AVIATION...Phillips/Schoenfeld
MARINE...Hall/Schoenfeld
BEACHES...Hall/Schoenfeld
SYNOPSIS...MW
weather.gov/losangeles
Experimental Graphical Hazardous Weather Outlook at:
https://www.weather.gov/erh/ghwo?wfo=lox
Area Forecast Discussion
National Weather Service Riverton WY
352 PM MST Wed Jan 10 2024
.KEY MESSAGES...
- Snow tapering off today, with one final push overnight tonight
across the state.
- Second system arrives Thursday afternoon, with moderate snow
returning to western mountains.
- Significant polar surge arrives for the weekend, with
temperatures struggling to get above zero.
&&
.DISCUSSION...
(This evening through Wednesday)
Issued at 153 PM MST Wed Jan 10 2024
Next weak shortwave poised in Idaho, ready to sweep across the
state tonight, which will bring a few more inches of snow to the
western mountains, and will likely bring another quick squall
long the I-80 corridor this evening. There is enough wrapping
around this system to push light snow northward into central WY,
so a couple inches of snow will also fall in Natrona and Johnson
Counties generally after midnight tonight. This round of Winter
Storm Warnings and advisories expires this evening, and will
likely not need extending.
Second wave is "hot" on the heels of the first one, with moderate
snowfall picking right back up for the western mountains Thursday
afternoon. This snow episode is going to be an extended period of
snow, lasting through the weekend, with significant accumulation
for the western mountains. Warnings will likely go right back up
after these first ones expire, and will extend through the
weekend.
Friday, an embedded wave to surge southward in this flow, bringing
a significant cold front through areas east of the divide. The
gradient from this system is expected to bring a significant
southwest winds across the state early Friday, with frequent gusts
above 40mph, especially west of the Divide and from RKS to CPR.
This wind will likely coincide with snowfall, so dangerous travel
conditions will spread west of the Divide during the afternoon.
Blizzard conditions continue to be a concern during this period.
The cold front will surge southward during the afternoon east of
the Divide, bringing a significant cold pool. This first surge
remain shallow, and won`t clear the Divide yet, so Saturday
temperatures will be a significant difference north to south, with
northern WY failing to get above zero, while southern WY warms
into the 30s. Later in the weekend into early next week, the
airmass will moderate some, as most of the cold pool sweeps
southeast across the Plains. But there will be enough push to
finally get some colder air west of the Divide, with high
generally in the single digits and low teens by early next week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday Afternoon)
Issued at 350 PM MST Wed Jan 10 2024
West of the Divide...KBPI/KJAC/KPNA/KRKS Terminals
KJAC Terminal...Snowfall rates will continue to decrease over the
next few hours, with only VCSH prevailing after 03Z, eventually
becoming prevailing VFR overnight. Snow showers will begin to move
back into the region late in the period ahead of the next
KRKS Terminal...Winds have begun to diminish, however, banded
convective snow showers are expected to move through the region
through 04Z this evening. Hi-res models, namely the HRRR and NAMNest
indicate one distinct band, likely lasting less than 30 minutes. A
quick, intense snowfall with gusty winds is expected with the
snowband, and vsby will quickly decrease to IFR or LIFR. Conditions
will return to VFR or MVFR just as quickly, once the snow band
passes. Otherwise, prevailing VFR conditions are expected.
KBPI and KPNA Terminals...Similarly to KRKS, a brief period of
banded snow showers is possible through 02Z, but otherwise expect
prevailing VFR conditions.
East of the Divide...KCOD/KCPR/KLND/KRIW/KWRL Terminals
A cold front will drop southward across the region this evening,
bringing snow showers with it. KCOD and KCPR have the best chance
(70 to 80% chance) of seeing IFR conditions as a result, with lesser
chance (40 to 50% chance) at KLND, KRIW, and KWRL overnight. All
terminals will return to VFR by 12Z Thursday, with the exception of
KCPR where low clouds may linger through the end of the period.
Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for
the latest information on icing and turbulence forecasts.
&&
.RIW WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning until 5 PM MST this afternoon for WYZ001-
013-023.
Winter Storm Warning until 11 PM MST this evening for WYZ012-
024-027.
Winter Weather Advisory until 11 PM MST this evening for
WYZ014-028>030.
&&
$$
DISCUSSION...Straub
AVIATION...Hensley