Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/15/23
Area Forecast Discussion
National Weather Service Burlington VT
905 PM EST Sat Jan 14 2023
Low clouds will prevail across most of the North Country tonight
with some clearing possible over the St Lawrence Valley, where
temperatures may drop into the single digits. On Sunday we should
see increasing amounts of sunshine with temperatures warming to
seasonable levels by afternoon. A storm passing to our east may
produce a few scattered snow showers on Monday, with warming
temperatures back above normal by early this upcoming week.
.NEAR TERM /THROUGH SUNDAY NIGHT/...
As of 902 PM EST Saturday...Snow chances have been increased
over our high terrain areas. In particular, we`re receiving
reports of coating on the roads from light snow across the
Adirondacks. Additionally, forecast soundings indicate cooling
to be enough that there should be some saturation in the DGZ as
the low stratus lingers. Orographic forcing should be enough to
squeeze some light accumulations overnight. General timing looks
to end about 5 AM, but could be as late as 7 to 8 AM depending
on how quickly we dry out overnight. Added 0.2" of snow and
increased PoPs to 30 to 50 percent over a large swath of the
Adirondacks. Have a great night!
Fcst challenge tonight wl be areal coverage of clouds/potential
clearing acrs the SLV and impacts on temps. Water vapor shows
large scale subsidence/dry air aloft directly acrs our cwa this
aftn associated with building hghts, while vis satl pic shows
plenty of low stubborn clouds. The classic setup of sfc to 900mb
moisture trapped below thermal inversion, which looks to
persist into the overnight hours. Have noted some clearing
trying to advance acrs the SLV with lower dwpts upstream at
Ottawa in the single digits. Following the RAP/HRRR sounding
profiles, does support clearing skies overnight, which should
result in temps cooling to near 0F, with maybe some
patchy/shallow fzfg. RAP sounding shows very sharp/shallow
inversion profiles, with temp falling way below cross over
value, supporting this potential, even with some lowering dwpts.
Otherwise, clouds wl drive overnight low temps with many
locations holding in the mid/upper teens, except some single
digits where clearing develops toward sunrise on Sunday.
Sunday/Sunday night no large scale changes made to the crnt fcst as
mid/upper lvl ridge and associated deep dry layer builds acrs our
western/central cwa. This should eventually erodes llvl moisture
with increasing amounts of sunshine anticipated on Sunday. However,
last place to see the sun wl probably be the eastern CPV and Western
Slopes based on northerly flow/convergence and lingering moisture
per soundings at BTV. Temps wl be the coolest northern SLV and
northern CPV valleys with values l/m 20s, while midslopes and ridges
warm into the mid 20s to lower 30s, due to inversion/thermal belt. A
challenging temp fcst again overnight Sunday night as sharp llvl
inversion prevails with deeper/protected valleys dropping quickly as
winds decouple. Have lows generally ranging from 0F SLK/northern SLV
to 15F eastern/southern VT where some high clouds may develop. Also,
have bumped pops up toward chc by 12z Monday for eastern VT, which
is supported by ECMWF/CMC and NAM retrograding some mid lvl moisture
back toward our cwa.
.SHORT TERM /MONDAY THROUGH MONDAY NIGHT/...
As of 335 PM EST Saturday...As an area of low pressure over the
Atlantic passes to the east, moisture on the western edge of the
system may extend into eastern Vermont. Model guidance suggests that
precipitation will be confined to northeastern Vermont, although
there is some disagreement. For example, the GFS shows precipitation
remaining to the east of our CWA while some Canadian guidance is
showing the potential for precipitation to reach as far west as the
Champlain Valley. Light snow showers appear likely for the areas
east of the Green Mountains, however there is the potential for
wintry mix Monday night which will continue to be monitored.
Overall, no major impacts are expected with this system.
Temperatures will continue to be on the colder side due to northerly
winds, with high temperatures in the mid and upper 20s in most
places. Low temperatures will be in the single digits to mid teens,
however lows in northeastern Vermont will be milder due to low cloud
cover associated with the moisture from the low pressure system.
.LONG TERM /TUESDAY THROUGH SATURDAY/...
As of 341 PM EST Saturday...No big changes to the midweek system that
will weaken as it traverses the Great Lakes region and brings light
mixed precipitation into our region. Have added some light ice
accumulation in the Tuesday afternoon/evening period across southern
St. Lawrence County given strong signals for a shallow warm layer
while surface temperatures remain below freezing. The potential for
freezing rain over mainly southern portions of northern New York and
Vermont does look fairly high and will likely lead to hazardous
travel. Thankfully amounts will be on the light side before
precipitation trends towards either plain rain or snow by Wednesday
when somewhat heavier precipitation arrives associated with cooling
aloft. Wednesday looks to be the mildest day of the week with
temperatures well above freezing in most locations with southerly
low level flow, in at least the early part of the day, prior to a
A moisture laden low pressure system still is on track to impact the
region in the Thursday afternoon through Friday time frame and again
will likely be messy with regards to precipitation type given
marginally cold air. Southwesterly flow aloft will tap into the Gulf
of Mexico and Atlantic during the event, and a dual upper jet
structure looks favorable for a strengthening low pressure system,
so heavy precipitation amounts are possible. At this time, we
continue to favor snow based on the model consensus/NBM.
Predictability remains lower than average with large spread in storm
track, although timing is in reasonably good agreement. Quite a few
ensemble members draw enough warm air aloft to change precipitation
to a wintry mix and/or rain before a secondary low to our southeast
can draw colder air back into northern New York and Vermont.
Therefore, was not willing to go with only snow as the precipitation
type, especially given the recent weather pattern and the lack of
support for an all snow event from the GFS ensemble. However, even
the latest GFS has a CIPS analog to a heavy upslope snow event from
February 24, 2012, so ingredients for significant snowfall are
definitely in place. Stay tuned as to how much snow as we can
solidify the event details in the coming week. Ultimately, the storm
will pass to our east towards late Friday with steady precipitation
becoming limited to dwindling snow showers on Saturday.
.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
Through 18Z Sunday...MVFR ceilings prevail at TAF sites attm.
While conditions will generally improve to VFR overnight, have
taken a more cautious approach at BTV due to low clouds from
lake response and SLK given ample moisture locked into the
terrain. MSS at the edge of cloud shield, which poses another
concern...namely fog development. Have increased patchy fog
across the St. Lawrence Valley (and northern Adirondacks), but
have stayed away from taking restrictions at MSS (or SLK for
that matter) thus far. Have maintained the BCFG comment at MSS
By 14-15z Sunday, expecting widespread VFR conditions with light
north/northeast winds of 5 to 10 knots.
Sunday Night: VFR. NO SIG WX.
Martin Luther King Jr Day: VFR. Slight chance SN.
Monday Night: VFR. NO SIG WX.
Tuesday: VFR. Chance SN.
Tuesday Night: Mainly VFR, with local MVFR possible. Likely RA,
Chance SN, Likely FZRA.
Wednesday: Mainly MVFR, with areas IFR possible. Chance SHRA,
Chance FZRA, Slight chance SHSN.
Wednesday Night: Mainly MVFR, with local VFR possible. NO SIG WX.
Thursday: Mainly VFR, with local MVFR possible. Chance SN, Slight
chance RA, Slight chance FZRA.
Area Forecast Discussion
National Weather Service Billings MT
756 PM MST Sat Jan 14 2023
Forecast looks to be on track tonight with low temperatures in the
low 30s to 20s across the region. Adjusted cloud cover up to the
south and east of Billings as mid to high-level clouds moved in a
little early. Even with the 0.05" of rain at Miles City, dew point
depressions between Miles City and Baker remain above 5 degrees,
keeping fog chances low for now. HRRR continues to keep visibility
up overnight. Arends
Tonight through Monday Night...
The weak shortwave that moved out of the Great Basin and into
Montana this morning has mostly moved north of the area. Miles
City did pickup 0.05" with the activity, but the rest of the day
should be quiet across the area as the energy has moved on. Given
the increase in lower-level moisture associated with the wave,
cannot rule out some fog mainly around Miles City and Baker, but
the current HRRR keeps visibility up.
The next issue on the horizon is the trough moving off the
Pacific. This will continue to push the ridge east bringing lower
heights and increasing cyclonic flow. It will also provide a
little more moisture. The best chance for snow remains in the
mountains where the 24 hour total Snow Monday remains around 70%.
The ensembles have trended higher with the precipitation for the
lower elevations, so have a little more snow on the lower
elevations. Twenty-four hour amounts are still generally an inch
Additionally, Monday morning in eastern Montana the temperature
profiles continue to support some light freezing drizzle or
freezing rain. There is a saturated layer below freezing, but it
does not support ice being present to produce snow. The NBM has
started to introduce some chance for freezing rain now, still of
a slight chance (less than 30 percent), but has added it to the
Tuesday through Saturday...
The theme for the mid- to late-week forecast period is changing
weather. Several shortwave troughs and ridges will move over the
Northern Rockies, bringing periods of dry weather and periods of
light snow in parts of the region.
On Tuesday, a weak shortwave trough will be over the region but
the forcing is so weak, we think that the only effect will be
mostly cloudy skies.
Tuesday night-Wednesday, the shortwave trough will exit MT to the
east, and shortwave ridging will move in behind it. This ridge
will facilitate decreasing cloudiness Tuesday night and mostly
sunny skies Wednesday.
Wednesday night through Thursday night, the shortwave ridge will
exit MT to the east again, and a stronger shortwave trough will
move over our region. This trough will bring a 30-50% chance of
snow to and near the Beartooth/Absaroka and Crazy Mountains and
adjacent foothills Wednesday night, then a 20-70% chance to much
of the lower elevations and all area mountains Thursday (greatest
chance in the mountains). Models are suggesting a northwesterly
flow upslope-downslope precipitation reduction/enhancement
pattern, so areas northwest of Billings would receive the least
amount of snow while areas southeast of Billings and mountains
would receive the most precipitation. As of now, though, the
probability of at least one inch of snow is near or greater than
50% only in the foothills of southern Big Horn and Sheridan
Counties and in the mountains, with the chance decreasing away
from those areas to near 10% for Billings and Baker and lower
values north of these areas.
Friday into Saturday, an upper ridge will build over the eastern
Pacific and Pacific Northwest, extending to the Northern Rockies.
The ridging will cause any snow to diminish early Friday, and dry
weather then through most of Saturday. Furthermore, stronger mid-
level winds crossing the Rocky Mountains will produce downslope
warming on Saturday. Later in the day Saturday, models then
suggest the upper flow should turn more northwesterly over our
region with a disturbance moving through the flow and a 20-40%
chance of snow showers.
High temperatures will generally be in the 30s and 40s Tuesday,
Wednesday and Saturday and 30s Thursday and Friday. RMS
VFR will prevail across the area through the TAF period, under
scattered to broken mid/high clouds. Isolated snow showers are
expected over the Beartooth/Absaroka Mountains tonight into
Sunday. Mountains will be occasionally obscured. JKL
.PRELIMINARY POINT TEMP/POPS...
Sun Mon Tue Wed Thu Fri Sat
BIL 030/044 031/043 026/043 023/042 027/038 025/039 025/042
00/E 33/S 10/B 00/U 13/S 21/B 12/S
LVM 028/043 030/041 022/038 019/037 023/033 019/032 019/038
02/S 41/E 00/B 00/B 34/S 21/B 12/S
HDN 021/040 025/038 022/040 018/040 020/038 021/037 019/041
00/B 34/O 10/B 00/U 14/S 21/B 12/S
MLS 022/036 024/032 023/035 019/038 021/036 022/034 020/037
00/B 13/S 20/E 00/U 02/S 21/B 11/B
4BQ 025/043 027/036 026/040 023/040 021/038 024/034 022/038
00/B 34/S 21/B 00/U 02/S 31/B 11/B
BHK 022/038 022/030 020/034 018/035 017/033 017/029 015/034
00/B 12/S 10/E 00/U 01/B 21/B 01/B
SHR 025/042 026/037 021/037 017/038 016/034 019/032 014/038
01/B 56/S 21/B 10/U 14/S 42/S 12/S
Area Forecast Discussion
National Weather Service Las Vegas NV
713 PM PST Sat Jan 14 2023
.SYNOPSIS...Active weather will continue across the area through
the Tuesday. The first round of mountain snow, valley rain, and
Mojave wind will continue through this evening, with dangerous
mountain travel expected. After a brief break on Sunday, the
second round of heavy mountain snow and valley rain spreads over
the area Monday into Tuesday. Dry, cooler weather is forecast for
the remainder of next week with temperatures 8 to 10 degrees below
.UPDATE...Update focused on lowering QPF for the
higher elevations in the first 6 hours (00Z-06Z) this evening.
Nearly an inch and half for the Spring Mtns looked unattainable
based on previous observations late this afternoon where SNOTEL were
reporting about 0.20"/hour. So blended the latest NBM with HRRR and
NAM to reduce values. Rain has been light across Las Vegas Metro
with amount generally less than 0.10" so far. Outside of the valley,
have seen some higher amounts between 0.50"-1.00" within the Pahrump
Valley, central Nye County, Owens Valley and parts of San Bernardino
County. Latest NBM shows PoPs starting to decrease late this evening
across Inyo, Esmeralda and western San Bernardino Counties. That
line advances east through Clark County between midnight and 2 am,
finally exiting eastern San Bernardino and southern Mohave Counties
between 4-6 am PST/5-7 am MST Sunday. Need to monitor parts of
southeast San Bernardino and southern Mohave Counties overnight as
some nuisance flooding is possible with pockets of moderate rain
.DISCUSSION...Tonight through Tuesday.
The first wave of a two part AR event is underway with radar
showing returns over the Sierra and also the Western Mojave
Desert. As of noon, observations sites in the Western Mojave
Desert were reporting up to tenth of an inch with snow piling up
quickly in the Sierra where Snotel sites have reported 4-13
inches since 10 am this morning. The heaviest period of snowfall
for the Sierra will continue through 10 pm this evening before
showing signs of tapering off. Total snowfall from this first wave
of 1-2 feet is expected along the upper eastern slopes of the
Sierra by 10 am Sunday with higher amounts up to 3 feet above 9000
Expect rain and high elevation snow to spread across the region
this afternoon and continue overnight. Snow was already falling
in the Spring Mountains at noon and is expected to become heavy at
times this afternoon and evening before tapering off by daybreak
on Sunday. Widespread light showers are expected through mid
afternoon in the valleys then moderate to heavy rain at times late
in the afternoon and this evening. Rain and high elevation snow
will continue after midnight but should begin winding down in our
western areas but continuing in our eastern areas. Went with a
Winter Weather Advisory for the Sheep Range and elevations above
5500 feet in Mohave County. The highest impact areas could see 4-7
inch snowfall with higher amounts in the highest elevations where
impacts are limited.
Sunday will be mostly an in between day as we wait for the second
wave to push into the area Sunday night and Monday. Lingering
precipitation on Sunday in mainly Mohave County could lead to
additional snow accumulations in the Arizona Strip and Hualapai
Mountains. Shower chances increase over much of the area Sunday
night but overall precipitation amounts will generally light. The
main concern will be lower snow levels between 4-5k feet. This
colder air could coat some lower elevation highways such as 395
in the Owens Valley with an inch of snow making travel hazardous.
As precipitation intensifies on Monday, the snow level will
increase to about 4500-5000 feet across our northern zones and
5500-6500 feet across our central/southern areas. Significant
snowfall is forecast again for the mountains with widespread rain
across the valley on Monday. A Winter Storm Warning is already in
effect through Tuesday morning for the Sierra and White Mountains
with additional headlines in other areas likely needed.
Wednesday through Saturday...the water hose for our area shuts off
as one more system is forecast to move from the Gulf of Alaska
through the Great Basin. This one looks dry and could be mainly a
wind maker for our area. What is notable is the cold air that
settles into place from mid week into the weekend. Temperatures
are forecast to be 8-10 degrees below normal.E
.AVIATION...For Harry Reid...Light rain will move across the
terminal this afternoon, decreasing CIGs to 3-5kft. The heaviest
precipitation is expected this evening when CIGs may lower to 2 to
3kft during periods of heavier rain. While most of the rain should
end by midnight, a few lingering showers will continue for a few
more hours, especially over the higher terrain surrounding the
valley. Winds will remain southerly into tomorrow morning, gusting
up to 25kts at times overnight. Winds will turn more westerly after
daybreak on Sunday, and decreasing clouds are expected by the
For the rest of southern Nevada, northwest Arizona and southeast
California...Extensive clouds and periods of rain will affect all
TAF sites this afternoon and tonight. CIGs decreasing to 3 to 4kft
is likely, with CIGs potentially falling to below 2kft during
periods of heavier precipitation. The rain may also mix with or
change over to snow at KBIH overnight before ending. Winds will
generally be south to southwest and gusty at times, especially at
KDAG. All sites should see improving conditions tomorrow morning
and afternoon before another system approaches from the Pacific
.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any significant weather or impacts according to standard operating
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