Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 02/12/21
Area Forecast Discussion...UPDATED
National Weather Service Corpus Christi TX
944 PM CST Thu Feb 11 2021
Zone of isentropic lift over the coastal plains and the coastal
waters this evening will gradually shift to the east during the
overnight hours. 12Z CRP sounding showed region of elevated
instability with MUCAPE values around 500 J/kg. Lightning data
shows thunderstorms mainly over the Gulf waters but a few strikes
just south of Corpus Christi. Adjusted PoPs to reflect forecast
trend for tonight. Models show isentropic lift will increase
again over the Coastal Bend. HRRR model showed convection will
increase again early Friday morning. Raised PoPs slightly for
the Coastal Bend region for Friday. No major changes made to
the current temperature forecast. Temperatures have been
generally steady this evening.
.PREV DISCUSSION... /Issued 541 PM CST Thu Feb 11 2021/
Poor aviation conditions will persist tonight into Friday with
IFR ceilings prevalent through the period for south Texas.
Scattered light showers will continue over the coastal plains
through most of the evening hours with MVFR vsbys/LIFR ceilings.
Another round of showers is expected to develop Friday morning
leading to MVFR vsbys from 14-20Z Friday. Some improvement to
MVFR ceilings will be possible over the northern Brush Country
on Friday with IFR ceilings holding elsewhere.
PREV DISCUSSION... /Issued 428 PM CST Thu Feb 11 2021/
SHORT TERM (Tonight through Friday Night)...
The first punch of our cold air outbreak came in this morning,
stronger than expected. Cold advection, thick low cloud cover and
rain showers all played a role in keeping temps nearly steady
throughout the day in the upper 30s and lower 40s. We will not see
much adjustment in these temperatures over the next 36 hours with
highs tomorrow mainly in the lower 40s and lows tonight and
tomorrow night in the mid and upper 30s. with a moderate northerly
wind tonight, especially east, wind chill values will drop into
the upper 20s northeast.
Isentropic lift should weaken tonight decreasing PoPs across the
area. A stray shower is still possible tomorrow, mainly east as a
mid-level trough tracks across the region.
LONG TERM (Saturday through Thursday)...
The big story in the long term remains with the frigid and wintry
weather expected Sunday Night into Monday. For Saturday, weak
isentropic lift will continue with light rain possible ahead of the
next approaching mid-level trough. Temperature profiles for Saturday
remain above freezing which should maintain precipitation mainly in
the form of rain.
The second trough will aid in a second surge of high pressure and
additional CAA into South Texas, bringing much colder temperatures,
with overnight lows expected to drop below freezing for most
locations for early next week. Early Sunday morning, there remains a
very slight potential for freezing rain/sleet for far northern areas
ranging from Cotulla to Victoria. This is highly dependent on any
light rain forming in the first place, as any rain could potentially
cool the atmosphere closer to the wet bulb temperature which
forecast soundings hover around freezing. Again, this is a very
Isentropic lifting strengthens Sunday night into Monday as the
second surge meets up with a surface coastal trough. PWATs are
expected to increase to nearly 1.3 inches which is higher than the
75th percentile of normal moisture for South Texas. This will ramp
up rain chances Sunday Night, with light to moderate rain showers.
However, as the colder air begins to filter in, with temperatures
reaching freezing, the rain is expected to start to transition to a
more freezing rain event late Sunday Night/early Monday morning.
Freezing temperatures may not reach coastal regions until near
daybreak. As Monday continues, temperature profiles support sleet
formation as well. Models did warm slightly with the 12Z run which
would limit how far south locations may observe freezing rain/sleet.
However, at this time, the NAM has yet to pick up on this system for
Monday so do not want to deviate far from previous forecast
packages with regard to temperatures.
In addition to the wintry precip, will say that the second surge of
pressure is showing a tighter pressure gradient which will lead to
stronger winds over the waters with a potential for Gale Warnings
across the Gulf waters for Monday.
The gusty winds over land will lead to wind chills reaching at least
advisory conditions of below 25 degrees, with possible warning
conditions for northern areas where wind chills drop into the single
As we head into Monday night, the surface coastal trough will
quickly lift to the northeast with continued northerly wind over
South Texas. This will gradually taper off wintry precipitation as
the bulk of the moisture exits the region. This will, however, lead
to some clearing with overnight lows to become even colder dropping
into the 20s to even the teens in some parts.
Temperatures will gradually/relatively warm for Tuesday into the 40s
but lows in the 30s will still be expected Tuesday night.
Another coastal trough will develop for Wednesday once again
returning moisture and rain chances to the region ahead of another
cold front Wednesday night. For now, have most activity in the form
of rain, but as some locations are showing to drop to near freezing
Wednesday night, will need to monitor the development of this system
for the potential of additional wintry precip Wednesday night.
Patchy fog and light rain will continue tonight with an isolated
thunderstorm also possible. Expect visibilities mainly between 1
and 3 miles. Moderate to strong winds will continue through Friday
night. A Small Craft Advisory is in effect across the near and
offshore waters through midnight Friday night, and for the bays
through mid-day Friday. The chance for showers will continue into
Friday. Northerly winds will continue to be strong through early
next week due to surges of arctic air, with gusts to gale force
Monday and Monday Night. A Gale Warning may be needed for Monday.
Showers will be possible over the weekend, with the chance of some
wintry precipitation mixed in Monday. Rain chances should taper
off by Tuesday but return Tuesday Night.
.PRELIMINARY POINT TEMPS/POPS...
Corpus Christi 38 43 39 47 36 / 70 40 20 30 30
Victoria 35 42 37 44 34 / 70 30 20 20 30
Laredo 40 44 38 45 36 / 40 20 20 30 20
Alice 37 42 38 46 35 / 70 30 20 20 30
Rockport 37 45 39 49 36 / 70 40 20 30 30
Cotulla 38 43 38 45 34 / 40 10 10 30 20
Kingsville 38 43 39 47 35 / 70 30 20 30 30
Navy Corpus 38 46 41 49 39 / 70 50 30 30 30
GM...Small Craft Advisory until midnight CST Friday night For the
following zones: Coastal waters from Baffin Bay to Port
Aransas out 20 NM...Coastal waters from Port Aransas to
Matagorda Ship Channel out 20 NM...Waters from Baffin Bay
to Port Aransas from 20 to 60 NM...Waters from Port Aransas
to Matagorda Ship Channel from 20 to 60 NM.
Small Craft Advisory until noon CST Friday For the following
zones: Bays and Waterways from Baffin Bay to Port Aransas...
Bays and Waterways from Port Aransas to Port O`Connor.
Area Forecast Discussion
National Weather Service Grand Rapids MI
1047 PM EST Thu Feb 11 2021
Issued at 245 PM EST Thu Feb 11 2021
- Light snow tonight with highest accumulations North
- Another round of snow for Saturday with cold air to follow
- A couple of potential rounds of accumulating snow next week
Issued at 1037 PM EST Thu Feb 11 2021
The forecast is largely evolving as expected. The exit region of
160 knot polar jet core is causing enough lift to create a large
area of light snow over southern WI and northern IL at 10 pm. The
jet core lifts northeast so most of this snow will fall north of
I-96 between say 3 am and 10 am on Friday.
However there is a glitch (of course). Looking at the Saturation
Equivalent Potential Temperature difference between 1000 mb and
850 mb, it becomes more negative than it did on the 8th when there
was 6 to 10 inches of snow near Port Sheldon. This is one of the
enhance lake snow bands. The band will be strongest during the mid
morning hours over central Lake Michigan as it is shifting back
across the lake toward Michigan. It will be weakening when it
comes on shore. Even both the NAMnest and the HRRR have locally
heavy precipitation amounts (which typically means there will be
locally heavy snowfall even of the location is not exactly
This band comes onshore by early Friday afternoon so it would be
in the afternoon into the evening we would see the heavier
localized snowfall. At this point there is to much uncertainty to
say much more than it is possible. One other point is that both
the NAMnest and HRRR show a secondary snowfall max EAST (yes
EAST) of US-131 in the evening. That is were the east flow from
the departing system centered to our south, converges with the
incoming surface high. The NAMnest version of this is closer to
US-131 with the heaviest snowfall, and mostly north of GRR. The
HRRR is about one row of counties east of US-131 but also north of
.DISCUSSION...(This evening through next Thursday)
Issued at 245 PM EST Thu Feb 11 2021
-- Light snow tonight with highest accumulations North --
The sunny skies across most of the area this afternoon, will be
replaced by some light snow moving over the area for tonight. This
light snow is the result of a short wave moving in from the west,
interacting with sufficient deep moisture. The deepest moisture will
be from along I-96 and areas north. This scenario will support a
general trace along I-94, to around three inches or so along the
U.S.-10 corridor by Friday morning.
Lake effect/enhancement is not really in play as the light snow with
the wave comes through. This is because the flow remains from the
NNE through much of the event. In the wake of the system on Friday,
what lake effect band is offshore over the lake will come onshore
Friday morning into Friday evening with the mean low level flow
shifting to a westerly component for a short time. We will see some
additional accumulations on Friday west of U.S.-131, before it
shifts back offshore Friday night as the flow becomes easterly
-- Another round of snow for Saturday with colder air to follow --
We have a generally similar setup for another round of accumulating
snow for Saturday into Saturday evening as compared to tonight.
There is the potential for snow amounts to be a little higher and
widespread for this system. Moisture is fairly deep for the entire
region to start with. In addition, the microphysics could be a bit
more favorable with the DGZ quite deep, which would help out snow
ratios a bit. The forcing ahead of this wave a little better with a
bit better upper divergence ahead of this wave. Right now, 2 to 4
inches looks like a good middle ground for much of the area. This
has the potential to be a little lower or higher depending on how
exactly everything comes together.
Once this wave moves by, we will see a reinforcing shot of colder
air push in from the north. 850 mb temps on Saturday will be in the
negative mid teens C, with negative mid 20s C coming in on Sunday.
As one would expect, this will help to trigger some lake effect on
Sunday. The lake effect does not look to be impressive at this
point, for two reasons. The first reason is that we do not see the
coldest temperatures aloft and cyclonic flow aloft come down this
way with the northern branch of the jet staying north. This is a
somewhat shallow cold air mass coming in. Also, the flow is NNW on
Sunday, but will shift to more NNE Sunday night, taking the lake
effect mostly offshore. There will be accumulations Sunday-Sunday
evening, just not too impressive at this time.
-- A couple of potential rounds of accumulating snow next week --
We are watching two periods next week for the potential of
accumulating snow that could affect the area. The periods are
generally Tuesday and then Thursday, with exact timing to be
We will see a long wave trough become established over the central
portion of the country. Decent pieces of energy/short waves will be
embedded in this flow, and will lift out of the long wave trough. As
they lift out, they will have a good potential to draw Gulf moisture
northward, and produce a fairly expansive area of wintry
The track and timing of any systems that would eject out of the main
trough is quite uncertain out at this time frame. There is the
potential that the systems would come close enough to bring
accumulations of snow to the area, or they could end up far enough
south and east that the precipitation would miss the area. It does
seem that we will be far enough established under the cold air that
precipitation type would be mainly snow, if it makes it up this way.
The more wintry mix of freezing rain and sleet would likely stay
further south at this time. There is plenty of time to monitor these
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 620 PM EST Thu Feb 11 2021
VFR persists this evening, but as light snow moves into the area
overnight we will see conditions deteriorate. Ceilings should
stay MVFR, but visibility may drop into IFR during periods of
heavier snow. Snow should impact most TAF sites, however JXN may
be spared as snow stays a bit further north. Meanwhile winds will
turn easterly through Friday morning, then vary a bit northerly
Issued at 245 PM EST Thu Feb 11 2021
Winds and waves may come up a bit later Friday as the winds and
waves build a bit behind the departing system that comes through
late tonight. This may necessitate a brief Small Craft Advisory, but
this should not be a significant marine event.
Our concerns are focused on Saturday night and Sunday, as winds and
waves will come up quite a bit with the next surge of cold air
poised to move in. The colder air combined with the winds/waves will
also create some freezing spray issues. Conditions should then
improve a bit on Monday as winds/waves come down some.
Area Forecast Discussion
National Weather Service Northern Indiana
627 PM EST Thu Feb 11 2021
Issued at 1235 PM EST Thu Feb 11 2021
Clouds continue to move in as a weak system approaches the
western Great Lakes. Some flurries and lake effect snow showers
are possible with this system into Friday. Another system will
bring a better chance of light snow for late Friday into early
Saturday with some light snow accumulations likely. A reinforcing
shot of arctic air is expected this weekend.
.SHORT TERM...(This Evening through Friday)
Issued at 300 PM EST Thu Feb 11 2021
The next shortwave, on the nose of a 140 kt jet at 400 mb, will take
a more northerly route through the Western/Northern Great Lakes
tonight as a large south-central Canada polar low begins to
congeal. This system may clip far nw IN and lower MI will a few
snow showers later this evening into Friday morning, with a few
flurries not out of the question into the rest of the area with
the area split between better forcing to the north and low level
frontal forcing well to the south.
Lake effect snow showers will develop again in mainly
Berrien/LaPorte counties on Friday as trajectories turn more
northerly behind a weak low level trough. Forecast soundings depict
the potential for light accums/impacts as the convective layer
overlays into the DGZ with good saturation wrt ice. Mainly dry/cold
elsewhere with highs recovering into the low-mid 20s.
.LONG TERM...(Friday Night through Thursday)
Issued at 300 PM EST Thu Feb 11 2021
The weekend into next week will continue to feature persistent arctic
air and periodic snow chances.
Another light snow event is expected Friday night into Saturday
across the Midwest and Lower Lakes. Band of snow will initially be
narrow as an approaching low amplitude lead shortwave induces an
elevated fgen response across northern IL-far nw IN-lower MI Friday
night. Snow ratios often overperform in these scenarios with several
inches of fluffy snow possible where better banding sets up. An
increase in large scale ascent is then expected by Saturday
afternoon as a more amplified mid level trough pivots through. This
should allow for light snow to fill in to the south during the day
on Saturday as a deformation band attempts to orient sw to ne across
the local area during the day. This could allow for an inch or two
of additional snow for the entire area on Saturday, mainly along/nw
of US 24. Fri night-Sat totals may exceed 3 inches in far nw IN and
Shot of colder air will follow Sunday into Sunday night with sub-
zero wind chills and lake effect snow showers possible. Some good
news is that the GFS has come into better alignment with the
"warmer" ECMWF showing much lower probabilities for advisory level
wind chills (-15F or colder) during this time.
A lobe of the polar vortex, just north of the Minnesota/Canada
border, will finally release east early next week, with southeast
CONUS upper ridge expansion, and the amplification of longwave
troughing across the Rockies/Plains. A low level baroclinic zone
will reorient from the Deep South northeast through the
Appalachian Chain in this regime, with a frontal wave developing
along this feature Mon-Tue, and again toward the end of the week
in response to pacific origin mid level shortwaves ejecting
northeast out of the Four Corners region.
The late Mon-Tue system will have a swath of snow on its northwest
fringe as it tracks northeast, with strong arctic high pressure over
the north-central US and lingering mid level confluence over the
Great Lakes determining the track/strength of the developing low
pressure system. Models overall show a coastal transfer with deeper
moisture shunted east of the area, which may keep this more of an
advisory level snow under the upper level shortwave. A lot of time
remains to sort out the details, so stay tuned. The trailing system
to follow next week could bring another bout of accumulating snow.
.AVIATION...(For the 00Z TAFS through 00Z Friday Evening)
Issued at 625 PM EST Thu Feb 11 2021
A shortwave passes by to the north, but it won`t do much more than
make it overcast tonight as midlevel dryness eats into that snow
chance. A weak shortwave just to the south of that shortwave may be
able to provide a period of MVFR CIGs Friday morning, but moisture
depth in the column could preclude this from occurring meaning it
could scatter out instead.
We`ll also have to watch the lake effect snow plume meander back
east from IL. This may affect SBN with some snow showers mid morning
into the afternoon hours potentially bringing MVFR VIS. The RAP
time sections indicate VIS could get into IFR. However, don`t have
enough confidence to include IFR VIS in this issuance since
inversion heights look low enough and there is some question about
how far inland the lake effect band can come before it dissipates
as the lake effect band loses structure and forcing over land.
Better chances for more widespread system snow move in after this
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Area Forecast Discussion
National Weather Service Newport/Morehead City NC
919 PM EST Thu Feb 11 2021
Weak low pressure will move away from the North Carolina coast
tonight. A series of several more weak lows will track near the
coast Friday and into early next week.
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
As of 910 PM Thursday...Lower lvl isent lift combined with upr
lvl divergence is producing widespread rain with some embedded
heavier shra over the region. Cont mostly categorical pops
overnight. CAA will lead to lows in the upr 30s N and W to
mostly lower 40s SE.
Prev disc...Scattered light showers moving into the western
tier of the CWA at mid- afternoon. Latest HRRR and 3km NAM shows
the light precipitation expanding from northwest to southeast
and to the coast by late evening and overnight. Some embedded
moderate showers are possible, especially in the 00z to 06z
timeframe, but most of the rainfall will be on light side.
Chilly temperatures and NE breezes will accompany the rain
tonight. Expect lows in the 36 to 40 degree range over most of
the CWA with some mid 40s around Ocracoke and Hatteras.
.SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/...
As of 320 PM Thursday...Another is the series of low pressure
waves moves offshore during the day Friday and will produce
another mostly light rain. Amounts will range from about one-
quarter inch over the Outer Banks to just a few hundreths of an
inch further inland. We will remain locked in low stratus clouds
with strong cold air damming with little temperature recovery
tomorrow, with highs likely only 3 to 5 degrees warmer than
lows, in the upper 30s to mid 40s.
.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
As of 315 AM Thu...An active pattern will persist through the
long term as a series of systems develop along a stalled frontal
boundary off the Southeast coast.
Friday Night...Broad area of stratiform precip will be moving
offshore Friday night, giving us a brief reprieve in rain
Saturday through Sunday...Modest mid-level trough axis over the
Midwest trailing into the Mid Atlantic will swing across the
region Sat, spinning up yet another low pressure system across
the southeast. System will become better organized Sat aftn as
it reaches the Carolina coastal waters. Widespread rain expected
all day Sat as the system moves through the region. Models
continue to show CAD occuring across the Piedmont Triad region,
which will keep temps cool in central NC during the aftn and
provide some ptype issues there. Unlikely at this time for
Eastern NC to see much ptype issues with this storm, we can
expect a very sharp temp gradient Sat with this system. Areas
west of Hwy 17 will likely stay in the low to mid 40s with
locations east towards the coastline reaching the upper 40s to
Low will push out of the region Sat night into Sun morning. We
will see a brief break from the rain before a weak mid-level shortwave
lifts across the Southeast, churning up yet another low that
will move north and east through the region. Best chc for rain
with this system will occur late Saturday aftn into the
overnight hours with the bulk of QPF confined to the southern
tier and Crystal Coast. Temps Sat will remain cool around the
mid to upper 40s.
Washington`s Birthday through Tuesday...Coastal low will
continue pushing offshore Monday morning, providing another
quick lull in the rain during the day. A few light sct showers
remain possible Mon morning through the aftn as the coastal low
lifts out before a much stronger storm system marches across the
Southeast and into our region Mon night into Tuesday. Models
continue to trend towards a stronger inland system riding
northeast along the Appalachia region. Timing still differs
between models, but the general setup remains the same. Warm
front will force its way north across Eastern NC overnight
Monday into Tuesday morning. Expect widespread rain and warm
temps on Tuesday before the cold front pushes through late Tue
aftn into the nighttime hours.
Wednesday...High pressure will build in from the north in the
wake of the cold front, giving us a solid breather to a wet
pattern before yet another storm system begins to get its act
together late Wed night.
.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
Short Term /through Friday/...
As of 610 PM Thursday...High confidence in IFR or worse
conditions thru period. Low lvl CAA will lead to strong
inversion developing with widespread stratus expected tonight
thru the day Fri. Will also see rain/fog tonight and patchy
rain/drizzle/fog Fri that will lower vsbys at times as well.
Long Term /Friday Night through Tuesday/...
As of 345 AM Thu...Numerous rounds of low pressure systems are
expected to train across the region through the long term,
bringing extended periods of sub-VFR conditions through Tuesday.
Short Term /Tonight and Friday/...
As of 910 PM Thursday...NE winds are increasing over the region
as gradient tightens between high pres building in from the N
and weak low developing to the SE. Cont SCA all wtrs except wrn
Prev disc...Winds at late afternoon are NE at 10-20 knots with
seas 4 to 6 feet. Surge of NE winds develops later this evening
and overnight. Small Craft Advisories will be in effect for NE
winds 15-25 knots with a few gusts to 30 knots and seas up to
6-8 feet through the overnight hours into Friday. Winds may back
to more Northerly during the day on Friday, but will remain
quite gusty as yet another in a series of weak waves of low
pressure move along the frontal boundary offshore.
Long Term /Friday Night through Tuesday/...
As of 350 AM Thu...Unsettled weather expected through early
next week. A stationary boundary settled across the southern
waters will allow numerous low pressure systems to train along
the boundary. Broad coastal low will pass through the area
Friday and strengthen offshore. Strong Nrly winds will persist
into Friday night reaching 20-25 kts with gusts up to 30 kts.
Winds calm slightly Sat and Sun to around 15-20 kts, but seas
across the northern waters will remain near or at SCA criteria
for quite some time. Winds ramp back up again on Monday ahead of
the next system with gusts nearing 25 kts by Monday night.
MARINE...Small Craft Advisory until 4 AM EST Saturday for AMZ135.
Small Craft Advisory until 11 AM EST Friday for AMZ131-230-231.
Small Craft Advisory until 1 AM EST Sunday for AMZ152-154.
Small Craft Advisory until 7 AM EST Saturday for AMZ156-158.
Small Craft Advisory until 7 AM EST Sunday for AMZ150.
Area Forecast Discussion
National Weather Service Pocatello ID
900 PM MST Thu Feb 11 2021
.UPDATE...Have made a few tweaks to going forecast for tonight
based on recent observation and radar trends. Temperatures along
the Divide near the Montana border have already dipped slightly
below forecast minimums, therefore have pushed the forecast a bit
colder in that region. Winds coming out of the Monida region along
I-15 near the Montana border are quite gusty, and have pushed
winds up slightly there to account for those gusty north
conditions, as well as tweaked slightly higher in a few other
under-represented areas. Broad area of precipitation shifting
through southeast highlands is well covered, but increased
precipitation chances through the Eastern Magic Valley and South
Hills/Raft River region to account for upstream radar returns and
bullish HRRR precipitation forecast. Strong batch of warm
air expected to surge along the I-86 corridor as this
precipitation moves in. Consequently, have weakened overnight snow
accumulations in this region, though a mix of rain/snow is quite
likely. This is a tough forecast. A degree or two different could
mean a very different scenario for some locations by morning. DMH
.PREV DISCUSSION... /issued 249 PM MST Thu Feb 11 2021/
SHORT TERM...Today through Saturday. We still have strong
northwest flow aloft over our area. Moderate west southwest winds
are occurring down low for the Eastern Magic Valley and the Snake
plain. Cold air is filtering over the Montana Divide bringing
much cooler temperatures for our Northeast areas. There are some
really cold windchills, widespread in the single digits to teens
in Upper Snake plain and Upper Snake Highlands. Expect this trend
of moderate to strong west to southwest winds and much cooler
temperatures for our northern areas to continue through the
period. In addition, a moist wave is starting to move in northwest
flow this afternoon and will continue through much of Friday. The
Sawtooth mountains will receive 2 to 7 inches (with locally
higher amounts) of upslope snow where a winter weather advisory
is in place. Bigger impacts will be for our Eastern Highlands,
including the Teton Valley, Big Hole Mountains, Caribou Highlands,
and the Wasatch Mountains where still expecting 5 to 10 inches of
snow for valley and 8 to 16 inches of snow for mountains is
expected. Winter storm warnings are still in effect for these
locations. Blowing and drifting snow from strong winds will be an
impact as well. A winter weather advisory remains in effect for
the Island Park, Bear Lake Region, Blackfoot Mountains and
Marsh/Albion mountains for 2 to 4 inches of lower elevation snow
and 4 to 8 inches of higher elevation snow combined with blowing
and drifting snow. Areas of uncertainty continue to be our valley
areas from Pocatello to Burley. Currently, there is a tight
gradient of expected snow due to temperatures. Temperatures should
drop quickly, but how quickly to get accumulating snow, will
continue to be the challenge. Bench areas could see a couple of
inches of snow. Valleys will likely be around an inch with this
system due to elevated temperatures due to winds. Localized
valleys could get more. West southwest winds continue to be strong
with gusts of 30 to 35 mph along the I-86 corridor with this
system. These winds will likely extend east and north as well.
With this strong west southwest winds there could be some freezing
rain for the Eastern Highlands late this afternoon into early
evening. If this occurs it will not be widespread nor last that
For Saturday we are expecting a second system impacting our
Eastern Highlands and Snake Plan as well as the Eastern/Southeast
and Southern Highlands. With cold air filtering south into our
whole area, lower elevations will see snow too, where 2 to 4
inches is expected. 3 to 6 inches is likely for higher elevations,
especially for our Southern areas. Also, if a convergence band
sets up, the Pocatello area could see higher amounts in the 3 to 6
inch range. We are holding off on advisory for these areas until
this current system is mostly through. This snow will impact all
Expect temperatures above normal for our West and Southwest areas
and below normal for our northeast areas thorugh Friday and drop
below normal for all areas by Saturday.
LONG TERM...Sun through next Thu night. Something of a break in
winter storms for Sun, but another trough and associated weak cold
front expected to arrive late in the day Mon and continue into Tue
night. Lingering precipitation for Wed and Thu in northwesterly air
flow, so it favors the east side of the Snake River plain and
southeastern highlands, along with the northwest end of Custer
County. The cool down and winds associated with this particular
front are at this time fairly limited and the snowfall has only
patchy accumulations above 6 inches; definitely a weaker storm than
what is occurring in the near term. The farther east in the forecast
area, the less agreement on temperatures, but timing between the GFS
and ECMWF is excellent, the only differences-and they are minor-are
in precipitation amounts. It is generally wetter with the ECMWF, but
even that isn`t true every 6 hour period.
AVIATION...Morning guidance indicating continued slower evolution
of conditions with the incoming storm. However, IFR is expected at
KBYI, KPIH, and KIDA, with likely airport closure at KDIJ. KSUN is
in somewhat of a precipitation shadow, and will be IFR during some
of the morning hours, but is actually expected to experience partial
clearing by the afternoon. Limited clearing in the late afternoon
for KPIH and KBYI, but no such luck for KIDA and KDIJ. Messick
Winter Weather Advisory until 10 PM MST Friday for IDZ058-061-
Winter Storm Warning until 10 PM MST Friday for IDZ060-063>065.
Winter Weather Advisory until 5 PM MST Friday for IDZ072.