Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/17/22
AREA FORECAST DISCUSSION
National Weather Service Albany NY
902 PM EST Fri Dec 16 2022
.SYNOPSIS...
The coastal cyclone will move slowly northeast of Cape
Cod tonight and head towards Nova Scotia on Saturday. The
precipitation will change over to snow across the entire region
early this evening with the highest totals across the higher terrain
but some accumulating snow in the valley areas. The snow will taper
to snow showers north and east of the Capital Region Saturday
morning. Cold weather will continue this weekend with lake effect
snow impacting the western Adirondacks Saturday night through Sunday
night.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
Messy upper deformation precipitation still building north into
our region and small bands of enhanced precipitation should
reorient to more west/east through the night. There are zones of
very light precipitation between enhanced small bands and that
trend will continue through the night, with varying intensities
of precipitation.
Snow is now falling in the mid Hudson Valley and southern
Taconics but seeing a little mix with rain around Glens Falls
and Brattleboro but precipitation should become snow later this
evening and stay snow through daybreak in those areas. Higher
snow amounts in higher terrain will continue but valley areas
will see enough for considerable slushy and wet accumulations.
Thanks to everyone for snow reports. Just minor adjustments to
temperatures and precipitation trends through tonight
PREVIOUS DISCUSSION:
Coastal low pressure continues to move slowly northeast towards
southeast New England for early this evening. The short-wave
has become negatively tilted in the mid and upper level
deformation zone. The coastal low producing the heavy wet snow
over the higher terrain and north and west of the Hudson River
Valley will slowly move northeast towards Cape Cod tonight. The
secondary low is connected to the occluded/stacked low over the
Upper Midwest and wester Great Lakes Region. The closed/cutoff
low at H500 continues to spin centered over northern WI and
eastern MN.
The low to mid level frontogenesis continues to increase in the
northwest quadrant/mid-upper level deformation zone of the
cyclone and the snow has been rapidly changing over to heavy
wet snow in the Capital District/Upper Hudson River Valley. Some
low-level warm air in the boundary layer/down-sloping off the
western New England higher terrain/lower snow to liquid ratios
held totals down in the valleys areas, especially in the Hudson
River Valley, portions of the eastern Mohawk Valley and lower
terrain west of the Berkshires, and southern Greens. Also, the
Taconics has been warm in the mid 30s to around 40F, but the
better dynamics, heavy pcpn and cold conveyor belt will allow
all the rain or rain/snow mix to change to snow the next couple
hours. We are going to hold onto the headlines through the
evening commute and into tonight. Many of the valley areas will
be on the lower end of the ranges but light to moderate
accumulations are expected tonight.
The Capital Region/northern Taconics/central and eastern Mohawk
Valley could still get 2-6" additional snow. The southern and
central Taconics may only get 1-4". The higher terrain of the
eastern Catskills, eastern Adirondacks may receive 5-9", and the
southern Greens 6-12". Some storm totals in the southern Greens
could exceed 2 feet. Also, some tallies in the eastern Catskills
in the southern Adirondacks may reach 18-24". The Lake George
northern Saratoga Region may get an additional 3-7". The mid
Hudson River Valley an inch or two at most. The Berkshires may
receive 3-6" with the higher amounts over the northern Berks up
to a foot. The northern Litchfield hills possibly 1-3". The 12Z
HREFS continue to indicate high chance or low likely
probabilities for an inch an hour snow rates over the higher
terrain including the Berkshires/southern Greens/eastern
Adirondacks and eastern Catskills. Snowfall rates of an half an
inch to an inch and hour will allow be possible in the valleys.
A possible pivoting snowband may form associated with the
coastal cyclone over western to central New England as the H700
low closes off near eastern New England, which may enhance snow
rates to an inch or two an hour for southern VT and the
Berkshires. We also have to monitor for some localized Mohawk
Hudson Convergence documented by local CSTAR research with the
north/northwest winds down the Upper Hudson River into the
Capital Region and west/northwest winds down the Mohawk River
Valley converging with low-level moisture present and good
forcing aloft. If this occurs, it may add to the snow totals a
bit over the Capital Region/northern Taconics.
The latest 3-km HRRR and NAMnest has the snow taper to snow
showers south and west of Capital Region between 05Z-08Z, and
then further north towards the Capital Region between
08Z-11Z/SAT. Some west/northwest upslope snow showers may
continue along the spine of the southern Greens and western
Adirondacks,as well as the northern Taconics after daybreak.
Lows tonight will be in the mid 20s to lower 30s.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/...
Winter Storm Watch issued from 1 am EST Sunday to 7 am Monday
for the potential of heavy lake effect snow for northern
Herkimer and Hamilton Counties....
Tomorrow...Th upstream upper level low continues to slowly
migrate eastward over the Great Lakes Region. The coastal low
moves east of the Gulf of Maine. We are expecting residual
upslope snow showers to persist over the southern Greens,
Berkshires, northern Taconics and the southern Adirondacks.
Some of the snow showers and flurries may linger over the Lake
George Saratoga Region. In the west/southwest flow cyclone flow
aloft clouds will persist from the Capital Region north and east
with some clearing possible to the south. Additional snow
accumulations will range from a half an inch to a couple inches
in the upslope areas. Highs will run a little below normal with
upper 20s to lower 30s over the higher terrain and mid and
upper 30s in the valleys.
Saturday Night into Sunday Night...The mid and upper level
closed low moves towards the Northeast Saturday night into
Sunday. In the cyclonic flow, lake effect snow is expected to
develop down stream of Lake Ontario. A persistent, multi-lake
fetch and potential band development with extension into the
western Dacks is possible based on the 3-km NAM and Canadian
Regional as early as Sunday morning. Favorable delta T temps
from the surface to 850/700 hPa and a moderate class of
instability is implied base on some of the upstream Bufkit
soundings. The inversion height looks to range 8-10 kft with the
potential for single band Sunday into Sunday afternoon with a
250-260 degree trajectory. Locations mainly along and north of
the Old Forge/Route 28 would have the greatest impact. A Watch
was issued for the potential of getting 7" inches of snow Sunday
into Sunday evening before the flow veers to the northwest and
the band may become transitory moving into the Mohawk Valley
Sunday night. Most locations will see some clearing Saturday
night outside the potential lake band development with lows
falling into the teens and lower 20s.
The flow gradually veers to the west/northwest late Sunday pm
into Sunday night with some upslope snow showers possible over
the southern Greens, Berkshires and the west/southwest
Adirondacks on Sunday. The snow shower activity may become more
widespread with the winds shifting to the west/northwest and the
upper low moving over head Sunday Night. We kept
likely/categorical PoPs over the western Adirondacks/western
Mohawk Valley Sunday night with slight or low chance PoPs from
the Capital Region, Berkshires and eastern Catskills north and
east. Some light accums are expected with the lake effect snow
band south of the watch area with 1-3" or so in the western
Mohawk Valley. Fragments of snow showers associated with the
upper low may produce light snow accums in a few locations.
Within the lake band some amounts could exceed 7" in a 12-hr
period (why the watch was issued). The upper low moves southeast
Ontario and northern NY on Sunday with partly to mostly cloudy
conditions. Highs will be a tad colder in the 20s over the mtns
and lower to mid 30s in the valleys and over the hills. Lows are
expected in the 20s Sunday night.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
The longterm forecast period begins with the core of an upper-
level, closed low pressure system exiting the region to the east
and sliding off the New England coast. While it takes with it
the steep moisture axis that will have brought widespread
precipitation to the region by the termination of the weekend,
encircling its western periphery is a short wave feature that
will enhance moisture advection from Lake Ontario, bringing lake
effect snow into the western Adirondacks and northwestern-most
portions of the Mohawk Valley. This lake effect snow should
carry through early Tuesday morning before high pressure ridging
builds in overhead, introducing a drier environment to the
forecast area Tuesday night through Thursday morning.
While confidence is fairly high in the aforementioned conditions, it
decreases significantly when considering the model-illustrated event
for late next week. While general consensus suggests the
introduction of an arctic airmass to the greater portion of central
CONUS by mid-week, models differ greatly with the expectations of
the track of this airmass and the impacts it could have for the
forecast area. While the CMCNH and ECMWF track the potent low
pressure system into the region from the west, the GFS appears to
show it digging to the southeast before developing a coastal element
and heading north in the form of a nor`easter. Precipitation
duration, type, and intensity will be track-dependent. With great
uncertainty still present at this time, PoPs have been kept on the
low-end of likely with NBM output of precipitation type. This system
will continue to be monitored as its window of occurrence draws
closer.
Temperatures during this period are expected to be seasonably chilly
with overall temperatures in the 20s to 30s throughout the forecast
area.
&&
.AVIATION /02Z SATURDAY THROUGH WEDNESDAY/...
Snow is expected to continue throughout the night at all TAF
sites causing IFR-LIFR conditions. Currently, KALB/KPSF/KPOU
have both restricted visibilities and ceiling heights within the
IFR category while KGFL`s conditions fall within the MVFR
category. The MVFR conditions at KGFL are expected to transition
to IFR by 02z with the possibility of snow increasing in
intensity at times.
Snow is expected to persist through tomorrow morning, with
locally moderate intensities possible at times. Snow showers at
KPOU will be the first to taper off as the moisture-rich system
progresses northward. Snow should cease by around 10z here while
KALB/KGFL/KPSF could see lingering snow showers until
approximately 13-15z. Once precipitation ends, MVFR ceilings
will be maintained for the remainder of the morning until
improvements to VFR come along in the afternoon. VFR conditions
will then be maintained for the remainder of the 00z TAF cycle.
Winds throughout this period will be light and northwesterly
ranging from 5-10 kt.
Outlook...
Saturday Night: No Operational Impact. NO SIG WX.
Sunday: No Operational Impact. NO SIG WX.
Sunday Night: Moderate Operational Impact. Chance of SHSN.
Monday: Low Operational Impact. Breezy. NO SIG WX.
Monday Night: No Operational Impact. NO SIG WX.
Tuesday: No Operational Impact. NO SIG WX.
Tuesday Night: No Operational Impact. NO SIG WX.
Wednesday: No Operational Impact. NO SIG WX.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...Winter Storm Warning until 10 AM EST Saturday for CTZ001.
NY...Winter Storm Warning until 10 AM EST Saturday for NYZ032-033-
038>043-047>052-054-058-061-063-082>084.
Winter Storm Watch from late Saturday night through Monday
morning for NYZ032-033.
Winter Weather Advisory until 7 AM EST Saturday for NYZ053-059-
060-064-066.
MA...Winter Storm Warning until 10 AM EST Saturday for MAZ001-025.
VT...Winter Storm Warning until 10 AM EST Saturday for VTZ013>015.
&&
$$
SYNOPSIS...Wasula
NEAR TERM...NAS/Wasula
SHORT TERM...Wasula
LONG TERM...Gant
AVIATION...Gant
Area Forecast Discussion
National Weather Service La Crosse WI
930 PM CST Fri Dec 16 2022
.DISCUSSION...(This evening through Friday)
Issued at 250 PM CST Fri Dec 16 2022
Key Messages:
- Nuisance light snow continues tonight into Saturday with minor
travel impacts
- Chance of additional light snow Monday into Monday night, but a
more impactful system lies on the horizon for the second half of
the week
- Pre-Christmas Arctic blast with temps gradually falling Sunday
into the work week - increasing likelihood for bitter cold wind
chills
Continued Light Snow Tonight Into Saturday:
Vertically stacked low pressure system continues to slowly inch
eastward across northern Wisconsin. Deep cyclonic flow overhead and
saturated low levels have been supportive for widespread light snow
across the area since last night, but the good news is we`re finally
nearing the end of this nearly week-old system. Accumulations will
continue to come in small amounts at a time the rest of this
afternoon into tonight, adding up to an additional 1 to 2 inches by
this time on Saturday. Small enough to not cause major travel
headaches, but enough to cause some lingering nuisance slippery
roads and reduced visibility. Brisk southwest to west winds today
have been strong enough to cause some minor drifting in open areas
given this dry/light snow variety. Not seeing much evidence for
blowing snow issues, but can`t rule out some patchy blowing snow in
open areas west of the Mississippi River.
Heading into tonight and Saturday, the low will slowly migrate into
the Upper Great Lakes region. Associated QG forcing will gradually
become more focused across our north as the system slowly pulls
away. So highest snow chances should eventually become focused
mainly near and east of the Mississippi River. Moisture aloft will
slowly strip out from the the top of the saturated layer heading
into Saturday, but forecast soundings suggest a decent chance for
lingering light snow or flurries across most of the area for much of
the day. Looking like the snow machine finally should shut down
heading into Saturday night and Sunday.
Can`t rule out a brief transition to light freezing drizzle in spots
the rest of today into Saturday if we`d temporarily lose cloud ice,
but HRRR soundings indicate this would be transient so stuck with
all snow in the forecast.
Next Chance of Light Snow Arrives Monday Into Monday Night:
Ensemble guidance indicates an increasing likelihood of another
system bringing a round of light snow to the region as the new work
week unfolds. An upper low coming onshore southern California on
Sunday would spawn this system in the lee of the Rockies Sunday
night, which would then impact our region Monday into Monday night.
Based on current expected speed and track of this system (certainly
subject to change), it looks like main impacts would begin Monday
afternoon and continue through the overnight. As of now, QPF amounts
look light with 16.00Z GEFS/EPS/CMC ensemble blend indicating only
about a 20 to 30 percent probability for greater than 0.10" liquid.
Stronger Winter System Later in the Week:
Greater winter impacts are anticipated from a more organized,
intense system arriving sometime in the second half of the work
week. Very low model consensus in storm track, timing, and
associated impacts that far out, but there`s at least general
agreement for a more potent system in that timeframe. For now will
let NBM precip chances suffice, with the expectation that models
will continue to waver from run to run. Definitely a system to
monitor in the coming days if you have holiday travel plans heading
into next weekend.
Blast of Arctic Air Heading Into Next Week:
Biggest story heading into next week will be a blast of Arctic air,
which will begin spilling into the region as early as Sunday behind
the departing cyclone. Already seeing signals for anomalous cold
showing up in NAEFS percentiles (below 10th percentile) and ECMWF
EFI, which will likely strengthen in the coming days as models come
into better agreement. Coldest blast looks to come Tuesday and
beyond. Bitter cold wind chills are looking like a decent bet within
that timeframe with potential for -20 to -30 or colder. Will
continue to gradually increase our messaging on these potential
impacts as we get closer.
&&
.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 930 PM CST Fri Dec 16 2022
CIGS: cigs look to hold mostly MVFR through Sat night, with
improvement as we move into Sunday and a weak ridge of high pressure
starts to influence the region.
WX/vsby: main areas of -SN exiting and/or shifting north overnight.
Cyclonic flow a loft will continue some flurries through Sat, with
some threat for an additional snow shower or two (and related drops
in vsby).
WINDS: westerly and sustained in the low/mid teens through Sat. Some
gusts into the lower 20 kts possible.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
DISCUSSION...Kurz
AVIATION.....Rieck
Area Forecast Discussion
National Weather Service Goodland KS
626 PM MST Fri Dec 16 2022
.UPDATE...
Issued at 622 PM MST Fri Dec 16 2022
With area obs continuing to show a fairly quick decrease in
winds, and with the latest HRRR a showing surface ridge axis
pushing slowly east into the western portions of the cwa as the
evening progresses, plan on updating forecast to remove mention of
blowing snow. Will also see if temps warrant a bump down. Clear
skies, leftover snowpack and light winds will be major factors,
especially in northeast Colorado. Will await latest obs at 02z
Saturday then issue.
&&
.SHORT TERM...(This evening through Monday Morning)
Issued at 254 PM MST Fri Dec 16 2022
Strong northwesterly winds continue across the area today behind the
departing low pressure system. Wind gusts of 50-55 mph have been
coming throughout the late morning and afternoon hours. Surface high
pressure over Colorado looks to move slowly to the east overnight
tonight which will bring this prolonged period of windy conditions
to an end heading into the weekend. A few plumes of blowing dust has
developed across southern portions of the area as the 1 hour GFS
does support some marginal lapse rates based on local office
climatology does support the blowing dust potential. An area of
lower ceilings which looks to be related from blowing snow in
Nebraska being lofted into the area may lead to some flurries
over the eastern portions of the area through sunset. Into
tonight, winds will become westerly around 10-15 mph along with
clearing skies. Overnight lows are forecast near zero across east
Colorado to the mid teens over the eastern CWA. Winds are
expected to be lightest over areas due to effects of the surface
high and lighter winds where an eye on radiational cooling
potential looks to be realized. Some locations west of Highway 385
may approach -15 wind chills along with air temperatures near -5
may occur.
Into the weekend, weak ridging develops over the western CONUS along
with winds becoming more southerly. This will allow temperatures to
become more normal with highs in the in the upper 30s to low 40s
across the area, snow packed areas from this weeks blizzard may be a
few degrees cooler due to a higher albedo. Perhaps the most welcome
news will be the relief from the gusty to strong winds that has
impacted the area for the majority of this past week. Winds will be
mainly from the WNW at 5-15 mph on Saturday before becoming more
variable on Sunday.
Into Sunday Night, a developing trough over the SW CONUS will be the
next potential weather maker for the Tri-State area. As the trough
moves through the area this will allow the first area of cold air to
drain into the area with NW portions of the area falling below zero
with near 15 below wind chills. I did introduce some silent pops
over the eastern portion of the area as some light snow may work its
way into the CWA. Guidance differs on how far north moisture is
able to advect into the area.
.LONG TERM...(Monday through Friday)
Issued at 328 PM MST Fri Dec 16 2022
The main story for the long term period continues to be the expected
cold as an Arctic airmass is pulled southward into the central
CONUS.
Monday begins with an upper-level trough with its axis through
eastern CO/western KS, allowing southwesterly winds aloft to shift
west-northwesterly. At the same time, a low pressure center is
located over the Maine/New Brunswick/Nova Scotia region with another
positioned in the vicinity of Alberta with ridging between the two
systems. As a lee low traverses eastward over the TX/OK Panhandles
and southern KS, surface winds will be out of the north-northeast
over our area. Lows Monday morning range from just below 0 into the
mid-teens. Highs will be a bit cooler than they were over the
weekend, in the mid-20s to mid-30s. Overnight lows will range from a
couple degrees below zero into the mid to upper-single digits.
Tuesday continues cold with afternoon highs in the low-20s to mid-
30s.
Heading into Wednesday, an amplified ridge over the central CONUS
begins to break down as another upper low, and the source of the
very cold temperatures, dives south on the backside of the strong
low system over the Great Lakes and another ridge amplifies over the
west coast. Wednesday`s temperature forecast is largely dependent on
timing of cold front passage. Current forecast has the front moving
through Wednesday afternoon/evening, so afternoon high temperatures
expected to range from near 30 north to low-40s south. Overnight
Wednesday night with gusty winds in the 25-35 knot range
accompanying the front and the very cold temperatures plummeting to
near 10 below, minimum wind chill values range from 20s below to mid-
30s below zero. Currently only looking at slight PoPs for northern
portions of the area. On Thursday, highs will struggle to get out of
the teens. Thursday night lows fall into the mid-single digits above
and below zero. NBM throws slight PoPs in over northern portions of
the area towards the end of the long term period as a shortwave
trough develops and moves over. Expect some improvement in
high temperatures reaching the mid-20s to mid-30s on Friday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 355 PM MST Fri Dec 16 2022
For KGLD, mainly VFR conditions through the forecast period. 6sm
in blowing snow is possible from 00z-03z Saturday. Winds
northwest 25-35kts through 03z Saturday, then west-northwest
10-15kts. LLWS 03z-16z Saturday 330@35 to 45kts.
For KMCK, VFR conditions through the forecast period. Winds
northwest around 20-30kts through 03z Saturday, then west-
northwest 10-15kts. LLWS 03z-12z Saturday 320@40kts.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...JN
SHORT TERM...Trigg
LONG TERM...CC
AVIATION...JN
Area Forecast Discussion
National Weather Service Grand Rapids MI
733 PM EST Fri Dec 16 2022
LATEST UPDATE...
Update
.UPDATE...
Issued at 732 PM EST Fri Dec 16 2022
Our forecast remains on track. A quick look at recent observations
at MKG and GRR confirm our 12 hour forecast from this morning is
on track. IR satellite image loops show the shortwave enhancing
the snowfall this evening will continue to impact this area early
this evening and then as the upper low gets closer yet another one
moves in after midnight. The depth of the moisture is, as noted
be previous discussions unusually deep, in the area of 15000 to
20000 ft. The DGZ gets rather deep, nearly 5000 ft actually and
the base of it gets down to near 5000 ft. There is lift, mostly
below the DGZ but there is decent lift even so in the DGZ. So,
bottom line is it will keep snowing through the night.
Another aspect to the snow this evening is we have a mid-level
cold front coming through. At 850 mb the temperature drops from
-9c to -12c in less than 50 miles. That gradient does move inland
of the lake shore. So there is some FGEN to this too. Beyond that
surface temperatures are now below freezing south of here. South
Bend has fallen to 27 degrees and temperatures over WI and IL are
all in the lower to mid 20s now. So the surface cold air is
coming in. Of course having road temperatures below freezing
helps that cause too. All of our road weather sensors have below
freezing temperatures now. This tells me the snow will stick on
all surfaces.
That being so, I increased the pop to 100% over the Advisory
area, after all, it is snowing and will keep snowing. I slightly
increased snowfall to 2 to 5 inches overnight too. Beyond that I
added patchy blowing snow along the lake shore were winds will
have gusts over 30 mph, which is enough to cause drifting snow
with air temperatures below freezing.
&&
.DISCUSSION...(This evening through next Friday)
Issued at 326 PM EST Fri Dec 16 2022
- Lake Effect Snow Impacting Travel Through Saturday Night
Several inches of snow are expected in the Advisory area through
Saturday night, leading to travel impacts as temperatures drop below
freezing this evening and tonight. We have expanded the Advisory to
include Osceola, Mecosta, Montcalm, Ionia, and Barry Counties.
Synoptic and mesoscale components will work together this evening
to enhance snowfall intensity and coverage. Upper level lift and
deep moisture in excess of 10,000 ft this evening will couple with
increasing lake-induced instability (50-100+ J/kg) and favorable
omegas below and within the DGZ to yield accumulating snowfall.
Where all these factors line up, SLR values will probably exceed
15:1 in places. Snowfall rates will be decent but not out of
control, with generally a half inch to an inch per hour wherever
the bands are steadiest. There will be some waxing/waning to the
bands as better synoptic lift moves in and out of the region over
the next 24 hours.
1000mb-700mb RH stays high for the duration of this event into late
Saturday night, and lift below and within the DGZ (especially off
the HRRR guidance) will keep bands going for awhile, though there
will be a pivot to the orientation of the bands from SW flow this
evening to W flow Saturday. Locations that will be impacted by both
flow regimes will see the highest accumulations, especially across
Ottawa, Allegan, and western Van Buren. That said, accumulations and
impacts will be spread out well inland given cloud layer winds over
30 mph.
There is some question about whether a convergent band of snow may
develop between I-69 and I-94 later Saturday as flow off the lake
goes west but near surface flow inland stays closer to SW. That will
be something to watch, which could end up being a short duration but
locally impactful situation.
Overall, there are no compelling factors to change the Advisory to a
Warning anywhere, given accumulations are not likely to reach a
higher level of impact to travel/commerce on a larger scale, and
winds will likely not be high enough to warrant mention of blowing
snow. Still, snow may easily get lofted/blown around on roads as
traffic displaces newly fallen snow.
- Chance for Light Snow Showers Monday Night/Tuesday
There is some model support for snow showers Monday night into
Tuesday as either a 500mb shortwave moves through or we get a
glancing blow from a deepening upper low to our north. The GFS is
more ambitious with this, and is probably too deep with the Tuesday
upper low compared to the GEFS mean and ECE mean. As a result, this
will probably be a minor event in terms of any light synoptic snow
or lake effect / hybrid setup.
- Impactful Winter Weather Possible Mid to Late Next Week
Ensemble guidance continues to indicate a surge of Arctic air moving
into the Great Lakes region later next week. The GEFS is on the
early side of the ensemble envelope (Wed.) while the ECE and CMC are
later (Thu.). The ensembles are averaging 850mb temperatures of -18C
to -20C with this air mass, which is not earth shattering but it is
pretty cold nonetheless. Ensemble mean high temperatures yield
readings in the teens while this air mass is overhead. There are
some deterministic runs that show 850mb temps of -25C or colder,
which remains within the realm of possibility, but plenty of time to
watch. Cold temperatures in the teens or 20s will persist into
Christmas Eve and Christmas Day it appears.
As this change in air mass occurs, we will have to watch the
longwave pattern evolution and monitor the orientation of upper
level heights and possible surface cyclogenesis on the cusp of this
Arctic air blast. Medium range guidance such as the ECMWF and GEM
are depicting borderline wild cyclogenesis impacting Lower Michigan
later next week. These types of solutions are not uncommon at this
forecast range and for this time of year. While tempting to discard
them as fantasy, a closer look at ensemble guidance from the ECE and
CMC reveals that there are some members that support a depending
low impacting the Great Lakes. Notably, while the ECE still favors
the East Coast to have a more favorable synoptic setup for a deep
low / Nor`easter, there was a jump in membership from the 00z
suite to the 12z suite that shows a Great Lakes cyclone
developing. These forecast details will be difficult to resolve
until we get closer to the event. At this point we can say that
there is at least a small risk for a winter storm mid to late next
week with potential lake effect to follow that.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 641 PM EST Fri Dec 16 2022
Lake effect snow showers will keep the western TAf sites mostly
IFR through Saturday night. Ceilings will actually mostly be MVFR
but visibilities will frequently fall below 3 miles and
occasionally may fall to 1/2SM SHSN or even 1/4SM +SHSN. I did
not try to time these much beyond 4 hours. Even so for MKG, GRR
and even AZO and BTL (not as much at these sites) you will see
that off an on. Winds turn more westerly toward 12z, so I would
think the conditions at GRR, AZO, and BTL will be lowest then.
Inland of US-131, or the I-69 TAFs, the snow showers will likely
not get that far inland after 06z but once the sun comes up and
winds are more westerly they should get the snow showers too.
It will be breezy through Saturday. Typically winds are not as
gusty at night, inland of the lake shore (MKG) but once the sun
comes up tomorrow the gusty winds will return to all sites.
Bottom line .... MVFR cigs with frequently IFR visibilities in
snow showers from now through Saturday night.
&&
.MARINE...
Issued at 326 PM EST Fri Dec 16 2022
SCA remains in effect until Sunday evening as winds and waves will
continue to be hazardous to small craft. SW winds over the lake
will shift westerly on Saturday. Waves of 4 to 8 feet are
expected.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Winter Weather Advisory until 1 AM EST Sunday for MIZ037>039-
043>045-050-051-056>058-064-065-071.
LM...Small Craft Advisory until 7 PM EST Sunday for LMZ844>849.
&&
$$
UPDATE...WDM
DISCUSSION...Hoving
AVIATION...WDM
MARINE...Hoving
Area Forecast Discussion
National Weather Service Gray ME
1043 PM EST Fri Dec 16 2022
.SYNOPSIS...
Low pressure moves into the Gulf of Maine tonight. Widespread
snow continues across most areas, with rain at the southern
beaches, and a mix of rain and snow near the southern coastal
areas and through the necks of the Midcoast. Heaviest snowfall
amounts are still expected over the higher terrain with no
changes to the current Winter Weather Headlines with this winter
storm expected to linger through Saturday. The system will be
slow to exit into the North Atlantic with continued chances for
snow showers in the mountains through Monday while areas south
of the mountains see an end to precipitation Saturday night.
Relatively quiet weather is expected through mid week as high
pressure builds into New England by Wednesday. Another potential
impactful system late next week is increasingly likely.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
1040 PM...Meso models, particularly the HRRR were spot on this
evening in bringing some moderate snow into the ME coastal and
adjacent coastal plain, as well timing the drop of temps by a
degree or two, just enough to allow for efficient accums.
transverse banding is noted in the reflectivity just offshore
indicating strong FG along the coastal front. Have mot changes
the winter hazards, as we could see enough snow, if banding
persists in much of ME to reach warning criteria. The area that
seems least likely for this to happen is the interior mid-coast
and Capital region, where not much has fallen yet, and models
are pushing the best forecast back to the east, toward the best
FG forcing around daybreak.
740 PM...The storm is panning about well through much of NH,
but this is not the story in ME, where many inland areas of wrn
ME, have underperformed in snow fall totals so far. Based on
that, I have adjusted snow total for today down close to the
obs, and this has lowered snow amounts some. Not enough to
change any hazards at this point, but would like to see snow
accums start to pick up. Most of the problem in this area was
that the snow was melting as it fell, given temps roughly 32-24,
and although it snowed steadily all afternoon in some places,
actual accums were under 2." It is starting to slowly turn
colder in ME, and Meso models continue to show a several burst
of moderate to heavy snow moving onshore this evening and
overnight, so no changes yet to hazards yet. Winds should peak
around or shortly after midnight as well and have been gusting
25-35 mph, highest near the coast.
Previously...The season`s first significant winter storm pushes
northward across New England today, continuing through tonight
as a surface low and associated mid-level circulation track
northward through eastern Mass. This has been a well-advertised
storm for several days, so I won`t go too-terribly far into the
meteorological weeds with this... and will (attempt to) stick to
the trends and changes to the forecast for this long-duration
event. The primary points of uncertainty remain the location
rain-snow line and snow accumulation efficiency in the presence
of marginal low and mid- level temperature profiles. Focus with
this forecast is on the track of the low/mid-level circulation
with greater warm air intrusion with a near-shore track and
vice-versa. Generally speaking... the forecast has trended ever-
so-slightly cooler... but with some impacts to those right
along the razor`s edge of the rain/snow line, but ultimately no
change to the hazard map.
At this mid-afternoon hour, the rain-snow line sits roughly
along the Midcoast`s Route 1 corridor, through the southern side
of the 202 corridor of SW ME into NH, and down toward the
Manchester area into its western foothills. As the driving
circulation pushes north, temperatures aloft are forecast to
rise above freezing... which will bring the rain- snow line
further inland toward the Monadnocks and Belknaps, although by
this time the dry slot also works in and cuts precip rates down
regardless. This is a slightly cooler solution over the
interior where warnings remain in place, with higher snowfall
amounts over the Upper Merrimack and into the Saco River
Valley... notably, have increased totals through the 202
corridor by a couple/few inches, given this remains the bullseye
for forcing as the low pressure circulation pivots toward the
Seacoast.
One other area of concern was the rain/snow line along the
Midcoast. Given elevated dew points south of the current
rain/snow line and a maritime contribution to ENErly flow
through the necks and islands, I don`t expect this line to
change much due to precipitation processes with the heavier band
coming onshore later this evening and overnight. This increase
in confidence has sharpened the snowfall gradient through the
Midcoast with little or no accumulation south of Rte 1 but up to
several inches once you`re in the hills further inland.
Finally, in the mountains... totals have come up by a couple
inches across the board in the higher terrain, particularly
through the higher terrain of New Hampshire where confidence
continues to increase in 1.5-2" QPF amounts as forcing and
adequate moisture slowly pivots over those areas and squeezes
out snow for the next 12+ hours... while areas further east dry
slot and rates diminish.
The general trend through the overnight will be to bring
temperatures back below freezing and transition any rain back
over to snow as cool air pours in from the north... except for,
perhaps, at the immediate southern coast. This trend happens
under a general dearth of forcing however so this should only
lead to light snowfall amounts during the morning.
Winds continue to be of minimal concern especially given cooler
solutions keeping lapse rates unfavorable. Strongest wind gusts
are expected where rain occurs; along the immediate coast and
inland through Rockingham County, topping out in the 35-40 mph
range this evening. One potential impact will be gusts where
wet, sticky snow clings heavily to trees... which may lead to a
few outages, in addition to those further inland under greater
snow load.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...
By Saturday morning, low pressure will be sitting in the
eastern Gulf of Maine with lift from its circulation strewn
mostly across the mountains, wrapping back down through western
New Hampshire as northwest winds start to filter through behind
the system. These are the areas where snow is likely to persist;
with bands of snow sliding east through the day as low pressure
departs toward Nova Scotia. These bands have a couple inches of
snowfall potential, although northwesterly flow will allow
upsloping to pile on several more inches through the mountains.
Southern New Hampshire may see some pokes of sunshine just
before sunset as the system pulls away, with modest clearing
over southern New Hampshire though the overnight. Meanwhile
upsloping clouds and showers will continue through the
overnight... with a chance that showers linger over central
Maine into the morning.
For winds... mixing won`t be very good so long as clouds and
snow remain in play, so for the most part steady 10-15 kt will
continue out of the north, then northwest... with gusts to
around 25 kts in the southern interior of New Hampshire
diminishing overnight.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
Overview...
Light snow lingers across northeastern areas Sunday morning
from today`s system, with upslope snow showers persisting into
the work week across the higher terrain. High pressure gradually
builds in on Monday and Tuesday, which then crosses New England
on Wednesday. Low pressure approaches from the southwest on
Thursday, and likely brings rain or snow, and wind Thursday
night and Friday.
Details...
The long duration storm will likely continues to bring light
snow to northeastern zones Sunday morning, with improving
conditions south of these areas. The storm is expected to linger
across the Canadian Maritimes into Tuesday. With high pressure
approaching from the west, northwesterly flow brings an extended
period scattered snow showers to the mountains and upslope
faces from Sunday through early Tuesday. Elsewhere, breezy
conditions are expected with the northwesterly flow direction on
Monday and into Tuesday.
Despite the persistent northwesterly flow and fresh snowpack
across most areas, arctic air modified by marine airmasses being
entrained by the blocking across northeastern Canada yields
temperatures near normal for the early and middle portions of
the workweek. The arrival of the high pressure center on
Wednesday brings colder nighttime temperatures Wednesday night.
Thursday`s temperatures will likely start to be influenced by
the next approaching storm system, with the track of this system
determining whether a cooler northerly flow or warming
southeasterly flow materialize.
Model consistency continues on the development of a coastal
storm, with impacts likely sometime during the Thursday night to
Friday timeframe. What remains unclear is the track and
resultant precipitation types. After a shift toward snowier
solutions yesterday afternoon, models overall trended warmer
with the solutions overnight and today. With the system still
about six days out, there will continue to be some back and
forth on the model runs, so we will continue to message that
precipitation remains likely, while uncertainty on the precip
type continue.
One concern with any warmer solutions is that stronger onshore
winds would accompany a warmer and wetter solution. With
astronomical tides at their monthly peak, coastal flooding
remains a concern with this system. Even an offshore track would
likely yield at least minor impacts, but the severity of these
impacts will ultimately be determined by the track and timing of
this system, which we`ll continue to monitor over the coming
days.
&&
.AVIATION /04Z SATURDAY THROUGH WEDNESDAY/...
Short Term...Widespread IFR and local LIFR continues in SN and
southern RA (at KMHT/KPSM) this afternoon and evening, the
exception being the usual KHIE, sheltered by the White
Mountains. Northeasterly winds around 10-15 kts gust to near 30
kts at the coast through... up to around 35 kts later this
evening as a storm system pushes northward into the Gulf of
Maine. Significant restrictions will continue overnight with
bouts of more intense precipitation rates bringing visibility
down to 1/2 SM or less at times. As the storm pulls east and
away from the area on Saturday... winds will turn to the north
and then northwest with very gradual improvement late in the day
as ceilings lift and scatter, with improvements more likely
toward the east Saturday night. Snow will be more off- and- on
tomorrow... leading to off-and- on visibility restrictions. At
KHIE, upsloping flow likely leads to prolonged IFR in low CIGs
and SHSN through Saturday night.
Long Term...Upslope snow showers and mainly MVFR ceilings are
likely at HIE on Sunday and Monday. Elsewhere, VFR conditions
become predominant on Sunday and persist through midweek.
Northwesterly wind gusts around 25kts are expected on Monday,
and then ease Monday night. Rain or snow is then likely Thursday
night and Friday.
&&
.MARINE...
Short Term...Northeasterly winds increase to a strong gale this
evening as low pressure crosses the Cape and enters the Gulf of
Maine. As the circulation tracks east through the GoM late
tonight and tomorrow, winds will turn to the north and then
northwest... gradually diminishing to SCAs on Saturday through
the overnight. This may bring the Gale Warning down sooner than
currently advertised.
Long Term...SCA conditions continue through Monday with
northwesterly winds and residual elevated seas, and then
gradually lower on Tuesday as northwesterly flow eases. High
pressure gradually builds in through midweek. A coastal storm is
likely Thursday night and Friday.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...Winter Storm Warning until midnight EST Saturday night for
MEZ007>009-012>014-018>022-033.
Winter Weather Advisory until midnight EST Saturday night for
MEZ024>028.
NH...Winter Storm Warning until midnight EST Saturday night for
NHZ001-002-004.
Winter Storm Warning until 7 PM EST Saturday for NHZ003-
005>009-011-015.
Winter Weather Advisory until 7 PM EST Saturday for NHZ010-012-
013.
MARINE...Gale Warning until 6 PM EST Saturday for ANZ150>154.
&&
$$
SYNOPSIS...
NEAR TERM...Casey/Cempa
SHORT TERM...Casey
LONG TERM...Clair
AVIATION...
MARINE...
Area Forecast Discussion
National Weather Service Indianapolis IN
926 PM EST Fri Dec 16 2022
.Forecast Update...
Issued at 926 PM EST Fri Dec 16 2022
Enough justification per radar and ob trends to continue slight
chance of light snow showers over northern sections through the
early overnight as the upper low spins over northern Wisconsin. Any
sort of other support for snow showers was lacking and moisture was
rather shallow confined to 2-5K per BUFKIT and ACARS soundings.
Thus, not expecting any accumulation with mostly no more than
flurries. Cold advection will allow temperatures to bottom out in
the lower 20s despite the solid stratocu.
&&
.Short Term...(This evening through Saturday)
Issued at 245 PM EST Fri Dec 16 2022
- Cloudy and cold with Flurries or snow showers this evening and
Saturday Afternoon
Surface analysis early this afternoon shows deep low pressure in
place over MN/WI. This deep low was providing broad cyclonic flow
across the region, including Indiana, reaching as far south as the
Tennessee River Valley. GOES16 shows extensive cloud coverage across
Central Indiana. A weak upper wave was found over IL and was pushing
east into Indiana. Radar shows some light snow showers entering NW
Indiana associated with this wave. Temps were holding in the mid
30s. Aloft, large and broad cyclonic flow was in place, again
centered over WI/MN, impacting much of the midwest and plains.
Tonight...
Cloudy skies are expected to remain across Central Indiana tonight.
Models suggest the upper short wave will depart east early this
evening and effectively take the best forcing along with it.
Furthermore the loss of any minimal surface instability due to
heating also points to a diminishing trend. Forecast soundings show
a bit more dry air within the lower levels as the wave departs.
Still however soundings suggest a thin area of low level saturation
indicative of trapped cold air advection strato-cu beneath an
inversion aloft. HRRR also suggests some scattered flurry/snow
shower coverage tonight, but again they trend toward dry overnight.
Overall any accumulation will be minimal to a dusting. Thus will
include some early evening pops for some light snow showers as the
forcing departs but trend to just an isolated flurry overnight.
Expect cloudy skies given the cold air advection and continued
cyclonic flow, with lows in the lower 20s.
Saturday...
The broad and deep upper low over WI is expected to push across the
Great Lakes on Saturday. This will keep cyclonic upper flow in place
across Indiana and our region. While the models suggest dry mid
levels, a weak short wave within the flow once again is suggested to
push across Central Indiana during the afternoon. Once again
forecast soundings show steep lapse rates favorable for convective
snow shower development. Thus will continue with cloudy skies on
Saturday and focus on small pops for these minor snow showers or
flurries during the afternoon hours. Again, any accumulation will be
minimal to a dusting. Given ongoing cold air advection and expected
cloud cover will look for only a minimal rise in temps with highs in
the upper 20s to near 30.
&&
.Long Term...(Saturday night through Friday)
Issued at 245 PM EST Fri Dec 16 2022
* Continued cold with an Arctic blast arriving late in the period.
* Mostly dry late weekend through early next week.
* Potential for at least light snowfall mid to late week, possibly
impactful.
The weekend will come to an end with the large upper low that has
brought significant weather impacts to much of the central CONUS and
much cooler conditions to central Indiana centered over the eastern
Great Lakes and rapidly departing.
In its wake, modest ridging at the surface and aloft will bring
continued cool and dry weather to the area through the start of the
work week. A pair of upper level disturbances, one large upper low
well to our north and another weak wave near or just to our south,
will pass through the region late Monday into Tuesday. While a few
flurries cannot be ruled out with these disturbances, their forcing
look to be much too far away for measurable precipitation, and the
most likely scenario at this point is an increase in cloud cover as
the midlevels moisten up but the lower levels remain quite dry. Will
keep flurries out for now given the magnitude of the dry low level
air.
A strong Arctic high will be poised to push toward the region mid to
late week, whether it leads or trails the coming weather maker, with
high confidence that significantly below normal temperatures can be
expected, including highs in the teens or perhaps lower by week`s
end, and lows in the single digits and perhaps sub zero depending on
snowfall. Dangerous wind chills well below zero appear likely late
in the week as the holiday weekend approaches.
Various models are struggling mightily to converge on a coherent
solution to the mid to late week pattern. In broader strokes, a
significant upper level system looks to drop into the central or
eastern CONUS mid to late week and induce strong cyclogenesis
somewhere in the eastern half of the country. This will have the
potential to produce a snowstorm, perhaps significant, for some part
of the country that may include central Indiana - this certainly
bears close monitoring given the busy pre-holiday travel timeframe.
Blend probabilistic guidance shows a high likelihood of at least
minor accumulating snowfalls in the Wednesday to Friday timeframe,
with low but still significant probabilities of impactful snow
accumulations. This will obviously depend upon which of the numerous
and varied model scenarios ends up verifying, but again, this will
bear close monitoring and scrutiny over the next several days.
Anyone with holiday travel plans should keep a close eye on the
forecast in the coming days.
&&
.Aviation...(00Z TAF Issuance)
Issued at 613 PM EST Fri Dec 16 2022
Impacts:
- Borderline VFR and MVFR ceilings through the TAF period
- Flurries or light snow showers mainly before 11z and after 18z
- Winds 230-250 degrees with gusts to near 25 knots, especially
after 18z Saturday.
Discussion:
Cyclonic flow with embedded impulses moving around the base of the
Great Lakes upper low will bring VFR and MVFR flying conditions
with flurries or light snow showers possible tonight and Saturday
afternoon. It will also be gusty with southwest winds gusting to
near 25 knots.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Update...MK
Short Term...Puma
Long Term...Nield
Aviation...MK
Area Forecast Discussion
National Weather Service Newport/Morehead City NC
1004 PM EST Fri Dec 16 2022
.SYNOPSIS...
Dry and cool high pressure will build over the area this
weekend through early next week. The next storm system could
impact ENC by mid to late next week.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
As of 1005 PM Fri...Forecast tracking well. Higher cirrus
beginning to build a bit with weak jet divergence in congruence
with modest moisture fields per RAP analysis. This will persist
through the overnight hours. No changes made this evening.
Prev disc...Quiet, dry, and cool conditions on deck for tonight
with light CAA persisting and mostly clear skies through at
least the first half of the overnight allowing for some modest
cooling. Mid-upper clouds put a lid on ideal radiational cooling
later this evening, so temps will be relatively mild, in the
mid/upper 30s interior to low 40s OBX.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/...
As of 330 PM Fri...Quick moving low amplitude shortwave will
swing through the OH Valley and the Mid Atlantic through the
day, with reinforcing modest CAA in wswrly flow. Temps will be
near climo generally in the mid 50s for most of ENC. The
shortwave will act to inc cloud cover with only partly sunny
skies expected for a better part of the day.
&&
.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
As of 3 AM Fri...Cold high pressure will build over the area
over the area this weekend and early next week. Mid to late
next week looks more active, with potential for coastal low
development and another frontal system approaching from the
west.
Saturday through Monday...Cyclonic flow continues aloft through
the weekend with the upper low remaining centered over the
Great Lakes through Saturday before sliding into northern New
England and southern Canada Sunday as sfc high builds in from
the west. A series of shortwave troughs will transition through
the flow aloft bringing reinforcing shots of CAA but with
limited moisture expecting little to no precip. Below normal
temps through the period. Highs Saturday in the low to upper
50s, 45-50 deg Sunday and Mon. Lows near or below freezing
expected across much of the area each night.
Tuesday through Friday...Sfc high will continue to build in
from the west early next week, grad weakening as low pressure
grad strengthens moving through the Gulf of Mexico, possibly
lifting along the SE coast mid week. Light rain possible Tue
and Wed, best chances along the coast, with weak front and low.
Forecast continues to look very interesting Wed night into Fri,
with a good amt of uncertainty. Amplifying upper trough is
forecast to dig through the central and eastern US Thu and Fri,
likely leading to cyclogenesis along/near the coast. Based on
thermal profiles, added rain/snow mix to portions of the coastal
plain late Wed night/Thu am, then expanded mention eastward Thu
night and Fri. Still too early for specifics (exact ptype,
potential accumulation, etc). But there is potential for wintry
precip late next week. Will continue to cap pops at chance.
Below normal temps will continue through the period, with much
colder arctic air expected late week and next weekend.
&&
.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
SHORT TERM /through Sat/...
As of 710 PM Fri...High confidence in VFR conditions this
evening as high pressure expands eastward from the southern
Plains. Only clouds overnight should be cirrus riding a powerful
H3 jet, otherwise clear skies are expected. Similar conditions
expected tomorrow with a modest increase in 6-7 kft cloud cover
as a weak shortwave approaches the region. WSW to W winds may
gust to 15 kt at times tomorrow afternoon.
LONG TERM /Saturday night through Tuesday/...
As of 3 AM Fri...Pred VFR conditions expected this weekend into
early next week with high pressure in control.
&&
.MARINE...
SHORT TERM /through Sat/...
As of 330 PM Fri...General wswrly flow at 10-15 kt persist
through early this evening, though large ENE swell cont 6-8 ft
@ 15 seconds for nrn and ctrl waters. WSW winds inc again tonight
ahead of shortwave, with SCA conditions returning to the srn
waters once again. Speeds will generally be 15-20 kt over the
sounds, and 15-25 kt over the coastal waters. The breezy
conditions perist through Sat, and in fact increase a bit late
in the day towards evening, where an SCA may eventually be
needed for Pamlico Sound late in the day or early Sat evening.
LONG TERM /Saturday night through Tuesday/...
As of 3 AM Fri...Gusty W/NW winds 15-25 kt will continue
through Sunday night. Conditions will be slow to improve with
high pressure building in, weak low development offshore and
rounds of strong CAA. SCAs continue for the southern waters into
Sunday, and Monday for the northern and central waters. Seas
4-7 ft Sat, 4-6 ft Sun and 3-6 ft Mon. NW winds diminish to 15
kt or less Mon afternoon. Seas expected to finally drop below 6
ft Monday evening for the northern and central waters. N/NE
winds 5-15 kt Tue with seas 2-5 ft.
&&
.MHX WATCHES/WARNINGS/ADVISORIES...
NC...None.
MARINE...Small Craft Advisory until 7 PM EST Monday for AMZ150-152-154.
Small Craft Advisory until 4 PM EST Sunday for AMZ156-158.
&&
$$
SYNOPSIS...MHX
NEAR TERM...TL/MS
SHORT TERM...TL
LONG TERM...CQD/CB
AVIATION...MS/CEB
MARINE...TL/CEB