Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/22/22
Area Forecast Discussion
National Weather Service La Crosse WI
537 PM CST Fri Jan 21 2022
.SHORT TERM...(Tonight and Saturday)
Issued at 215 PM CST Fri Jan 21 2022
A good amount of weather heading at us with the first of three snow-
producing systems moving through tonight. Current surface analysis
has a strong warm front oriented from eastern ND into central NE
with about a 15-20F temperature rise behind it /so, the area will be
warming all night/. GOES water vapor imagery showing more impressive
darkening over nwrn ND within the parent shortwave trough
circulation located over swrn Saskatchewan. An INCREDIBLY dry air
mass is found in the morning regional soundings with 30C dewpoint
depressions below 500mb in the pre-wave environment. Impressively,
the radar and surface observations are showing this band of forcing
producing snows in the 1/2-2SM range in the Dakotas /and increasing
in coverage over the past two hours/...impressive work to saturate
that dry air. This snow band from MN-NE is well correlated with low-
level warm advection ahead of the warm front. Winds have been on the
increase and as this front approaches, expect gusts to increase to
30 mph west of the Miss river. Post-warm front, winds shift to W-NW
with many gusts to 40mph over the Dakotas.
The forecast is pretty much on track with accumulating snow with the
snow band moving in this evening and shifting quickly east and out
by sunrise Saturday. With the moderate QG forcing and isentropic
lift / warm advection working together, and this continuing to
mature as the shortwave trough shifts southeast, feel that the snow
totals are on track with generally 1" or less southwest of I-94, 1-
2" along and north of I-94.
Winds are a bit of a challenge with this system as the flow just
above the surface is racing into the 40-50kt range this evening. The
majority of model soundings stabilize in the boundary layer this
evening and really arent mixing to realize this potential. Thus,
have lowered the gust speeds tonight a fair amount. This is of lower
confidence as the lapse rates are very close to mixing deeper. This
will need to be monitored. Once the front passes later tonight,
lapse rates in the lowest 1km become steeper but the low-level wind
field has decreased, and it still seems to allow gusts of 25-30 mph
in the sunrise hours. So, have forecast that ramp down this evening
in the gust speed with another ramp up around sunrise.
.LONG TERM...(Sunday through Friday)
Issued at 215 PM CST Fri Jan 21 2022
The shortwave parade continues into Monday, with a couple more shots
for accumulating snows. While none of the systems over the next few
days will bring an "appreciable" amount of snow, by Monday
morning most of the area could/will have a fresh 3 to 5 inches.
SAT/SAT NIGHT: bits of upper level energy slated to quickly follow
the system from tonight, swinging across the local forecast area
around 06z Sun, exiting southeast around 12z Sun. Models in good
agreement with taking the associated sfc low across IA, placing the
system`s deformation region from southern MN, across northeast IA
and through northern IL (generally southwest of I-94). Slug of low
level thermodynamics in this region (evidenced with upglide on 280-
295K sfcs) along with sloping southwest to northeast frontogenetic
forcing (in this case, more punchy in the 900:800 mb layer). Ample
lift with enough saturation for snow production.
Amounts? Current track would place the main band from southern MN,
across northeast IA and southeast of there. DGZ via RAP bufkit
soundings could be in excess 250 MB while the NAM and GFS would
favor 50-100 mb. Disagreement centers on differences in temps a
loft. Will lean toward something in the middle for now, with snow
ratios generally 15/20 to 1. Where it snows, time in residence will
help with the deformation region running along the same track as
system movement. Overall, currently looking at 1 to 3 inches, but
see some potential for some higher amounts in a more compact region,
which could lie just southwest of the local area (per latest
HRRR/RAP).
SUN NIGHT/MON MORNING: similar to Sat night with another shortwave
sliding across the region with a slug of low level thermodynamics.
Track is more northward with decent agreement between the models
sliding the associated sfc low southeast across central MN into
central WI between 00-09z Mon. Frontogenetic support runs mostly
north-south, ahead of the sfc low. Bulk of the associated snow would
fall along/northeast of I-94 in this scenario. Snow ratios likely
somewhere in the 15/20 to 1 range. Totals from 1 to 3 inches also
favored at this time.
OVERALL: the locations that get the bulk of the snow Sat night will
flip flop with the areas that don`t for Sun night. With some
locations expected to get around 3", slight shift in system track
and/or increase in snow ratios could push those locations up into
Winter Weather Adv criteria. Something to keep an eye on.
TEMPS: at or below normal for the much of the new week with the
upper level pattern holding (more or less) with ridge across the
west coast and troughing in the east. Various shortwave troughs will
reinforce the trough while also pushing slugs of cold air across the
region. Interludes of shortwave ridging favor closer to normal
temps...but these are brief. Working into the weekend, previous GFS
and EC runs were at odds with how amplified the upper level pattern
will be and positioning of ridge/troughing (and thus how cold/warm
it could be). Current 12z runs in better agreement. However, EC
ensemble members showing quite a spread...as much as a 30 degree
spread between low-high end for temps. Confidence lower in this
period as a result.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 537 PM CST Fri Jan 21 2022
A band of accumulating snow will move across the area this evening
into tonight. IFR visibilities are likely for a couple of hours
as the snow begins and will gradually improve as the snow rates
decline. MVFR ceilings are also likely through the overnight
hours. Northwesterly winds will return tomorrow morning with
15-25kt gusts mainly in the morning. Low-level wind shear is also
in place this evening at RST.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&
$$
SHORT TERM...Baumgardt
LONG TERM....Rieck
AVIATION...KAA
Area Forecast Discussion
National Weather Service Denver/Boulder CO
903 PM MST Fri Jan 21 2022
.UPDATE...
Issued at 832 PM MST Fri Jan 21 2022
The cold front finally progressed south through the Denver metro
this evening, with a corresponding north wind shift that generated
a brief spurt of localized snow showers for the western and
southern metro. Light westerly downslope winds suppressed much of
the wintry activity east of the Front Range earlier this afternoon,
with generally a dusting to 2 inches reported along the southern
urban corridor. Not expecting any meaningful additional snowfall
east of the foothills this evening, so went ahead and cancelled
the Winter Weather Advisory for eastern Boulder and Jefferson
Counties. Moderate snowfall has been much more persistent across
the foothills, including I-70 from Golden to the Eisenhower
Tunnel. Expect snow to continue for these areas through the next
2-3 hours, gradually dwindling in coverage and intensity. With
considerable weekend traffic in the mountains and continued snow
showers, will maintain the advisory for these areas, which still
runs through midnight.
Skies will clear quickly tonight, and combined with light winds,
could lead to a few areas of fog across the plains late tonight
into Saturday morning. Have therefore added a mention of patchy
fog in this evening`s forecast update for portions of the plains.
Lows will generally be in the teens east of the mountains
(pushing closer to 20 F around the metro), with single digits and
a few sub-zero values likely in the high country, coldest
in/around typical high valley cold pools. Dry and milder Saturday,
with mostly sunny conditions.
&&
.SHORT TERM...(This evening through Saturday)
Issued at 120 PM MST Fri Jan 21 2022
Light and at times moderate snow is occurring in many spots
across the area, in particular within the winter weather advisory.
The latest HRRR has backed off snow amounts in zone 39 (Boulder
to west metro Denver), but with cold road temperatures even 1-3"
of snow will cause issues for travel this evening. There are
still good signs pointing to convective instability moving south
along the Front Range later this afternoon and evening, which with
increased snow rates we still expect that could/should make for a
messy rush hour--especially in the foothills above 6,500 feet all
along the Front Range and the west part of the Palmer Divide. The
advisory looks like the right highlight through midnight for now.
Elsewhere a decent snow is possible along the higher elevations of
the Front Range and in the mountains along and south of I-70,
with 2-6" possible through midnight. The Park and Gore Ranges may
only see an inch or two as instability is lacking in that area
and there really isn`t any upslope flow. The northeast plains
won`t see much snow either, because of the downslope flow off the
Cheyenne Ridge, especially eastern Larimer, Weld, and points
eastward. Closer to the terrain of the Palmer Divide may see a
half inch of snow.
Snow should end tonight from north to south, by midnight if not
sooner as the upslope weakens and the trough moves even further
south of us into Arizona. The mountains in Park County and the
Palmer Divide near the El Paso line may hang onto light snow for a
few hours more, but no significant additional accumulation are
expected after midnight.
Any lingering icy/snow covered roads will quickly recover/improve
Saturday morning with no chance of snow, mostly sunny skies, and
much warmer temperatures advected from the northwest. Expect
highs in the 40s for the plains and I-25 urban corridor, with 30s
in the mountains valleys other than North and Middle Parks. It
looks like the inversions will hold strong on Saturday without
much wind to scour out the cold air. Highs will remain in the low
to mid 20s there. Winds will be weak across the area other than
the far northeast plains where west winds 10-20 mph with gusts to
25 mph are expected during the afternoon hours.
.LONG TERM...(Saturday night through Friday)
Issued at 120 PM MST Fri Jan 21 2022
Split weather pattern remains over Colorado through Sunday as a
closed low spins over the Desert Southwest and the main storm
track stays off to the northeast. This will result in mild
temperatures and dry conditions. Highs should climb into the lower
50s over northeast Colorado where the snow has melted off and
above the inversion.
Models are good agreement showing a trough diving south across
the Rockies late Monday and Tuesday. Timing is slightly different,
but not too far off. The center of the trough pushes southeast
over the Four Corners. A cold front associated with this system
pushes south through Colorado sometime Monday. Highs will depend
on the timing of the front, so a fair amount of uncertainty
remains with the temperature forecast for Monday. The highest
snowfall amounts should be west of I-25, along the east slopes of
the Front Range mountains and foothills. Here, upslope flow should
help produce a few more inches. At this time, looks close to
advisory amount snowfall with heaviest amounts being 4-8 inches in
the foothills and mountains. The far eastern plains are expected
to see only a little to no snowfall.
Northwest flow aloft will continue over the Central Rockies
Wednesday through Friday. A few models show a weak trough embedded
in the northeast flow aloft moves across Colorado. Most of the
ensemble members are dry during this period, so will keep PoPs
low, but can`t totally rule out snow during this time frame.
Expect temperatures to be near to slightly below normal under this
northwest flow. Could see a windy day or two as flow aloft
increases.
&&
.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 832 PM MST Fri Jan 21 2022
Snow showers have tapered off across the metro, and additional
precipitation appears unlikely for any of the TAF sites. Current
light N/NE winds will become more variable with some SW drainage
flow developing overnight, but remaining very light. Expect mid
and high level clouds to continue to thin overnight, with clear
skies by morning. The one caveat/concern will be the continued
potential for fog development, mainly 06Z-14Z, in the vicinity of
the terminals. Confidence in occurrence is low, but potential
seems high enough to still warrant VCFG in the TAF. If fog
develops, there will be a chance for vis of 1/2 SM or less. VFR
conditions are expected most of the day Saturday, along with light
winds which should gradually transition to a northerly direction
in the afternoon.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until midnight MST tonight for COZ035-
036.
&&
$$
UPDATE...Rodriguez
SHORT TERM...Schlatter
LONG TERM...Meier
AVIATION...Rodriguez
Area Forecast Discussion
National Weather Service Charleston SC
955 PM EST Fri Jan 21 2022
.SYNOPSIS...
An area of coastal low pressure will lift northeast along a
cold front tonight. The low will produce freezing rain across
portions of the region tonight. Dry high pressure will then
build from the west Saturday through Monday. Low pressure could
affect the area next Tuesday, followed by another cold air mass
through the rest of the week.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
Numerous reports of freezing rain continue to stream into the
office this evening, mainly across the Charleston Tri-County.
Reports elsewhere are typically hard to get this time of night.
As expected, the most significant icing has occurred across
Berkeley County where some fairly decent ice is now covering
trees, cars and other structures per social media and spotter
reports. Local storm reports (LSRs) are being issued as reports
are received and quality controlled.
No changes were made to the Winter Weather Advisory with this
update. Watching a corridor of enhanced pcpn developing across
east-central Georgia that will trek across far interior
Southeast South Carolina and Southeast Georgia as well as the
Charleston Tri-County overnight. This area of pcpn aligns well
with the corridor of strongest lift associated with the right
entrance region of the upper jet moving across the Carolinas.
There is concern with temps below freezing that ice accrual rates
will increase for about 2-4 hours later tonight as this area of
pcpn pushes through. Updated ice accumulations are not much
different than the previous update, but there are still concerns
that about amounts could get close to Ice Storm Warning
criteria (0.25" or greater) across eastern Berkeley County and
upper Charleston County. After some internal discussion, the
decision was made to not upgrade at this time given the impacted
area reaching >0.25" should be relatively small. In addition to
freezing rain, RAP soundings over interior Southeast South
Carolina suggest the warm nose aloft could erode just enough
closer to midnight to support occasional mixing of the freezing
rain with a little sleet. While this should not be much of a
contributing factor to this event, it may be noticeable for a
few hours. Finally, after rain ends patches of freezing drizzle
may linger to 1-2 hours after daybreak. While this is not
explicitly shown in the text or gridded forecasts, this will
have to watched carefully.
22/02z mesonet observations show the freezing line is tad ahead
of schedule across interior Southeast Georgia, so near term was
adjusted to reflect this.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/...
Saturday: A coastal low and associated cold front will push east of
the forecast area through the morning hours. Short term guidance
indicates that deep dry air will sweep west to east with the passage
of a mid-level trough early Saturday. The arrival of the dry air
should end precip across the land zones, with a few lingering rain
showers over the coastal waters. Temperatures should begin the day
in the upper 20s inland to the low 30s. Cloud cover is forecast to
remain high through the morning, then a few breaks of sunlight is
expected during the afternoon. Using a blend of MOS, temperatures
should warm above freezing by mid-day with high temperatures
expected to reach the low to mid 40s. Any wintry accumulations
across the CWA should steadily melt through Saturday afternoon.
Sunday and Monday: Dry and cold conditions will remain across the
forecast area both days. Temperatures Sunday morning should remain
well below normal, with low to mid 20s across the area. Full sun on
Sunday with cool thicknesses should yield high temperatures from
upper 40s across Berkeley and Charleston County, to the low to mid
50s across SE GA. A dry cold front is timed to sweep into the region
by Monday morning. Mostly clear conditions and lingering cool llvl
thicknesses should yield low temperatures in the upper 20s to around
30 Monday morning, with highs in the mid to upper 50s.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
Tuesday: Another southern stream low pressure system will track
across the Deep South Monday night, passing across the region
Tuesday and Tuesday night. Temperatures during the night are
forecast to remain in the upper 30s with daytime temperatures
warming into the low to mid 50s. This event is expected to support
at least likely PoPs for a cold rain.
Wednesday through Friday: The center of Canadian high pressure is
forecast to track from the Northern Plains on Wednesday morning to
the East Coast by late Friday. The forecast is expected to remain
dry. Temperatures will remain below normal, with lows in the 20s and
30s and highs in the 40s and 50s.
&&
.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
Temperatures have dropped to freezing at KCHS and will do so
soon at KJZI. Expect freezing rain and/or freezing drizzle to
prevail at both terminals overnight with cigs dropping to IFR.
The risk for ice accumulations will be present at both
terminals. The Freezing rain should end by 08-09z, but a period
of freezing drizzle may linger until daybreak. IFR cigs will
gradually improve to MVFR by early afternoon. For KSAV, liquid
rain or drizzle will persist with IFR cigs. A brief period of
freezing rain could occur at the terminal early Saturday, but
confidence is still somewhat low if any meaningful ice
accumulations will occur. Similar to KCHS and KJZI, conditions
will improve to MVFR by early afternoon.
Extended Aviation Outlook: VFR conditions expected through
Monday. Flight restrictions will be possible in showers Tuesday
and Tuesday night.
&&
.MARINE...
Tonight: Our area will remain sandwiched between a cold front
offshore and high pressure centered to our west. The interaction
between these two features is causing the surface pressure
gradient to be elevated. Additionally, there is cold air
advection across the area. This is resulting in elevated winds
and building seas across our waters. Small Craft Advisories are
in effect for all of our waters, except the Charleston Harbor.
Saturday through Wednesday: High pressure will increase across the
forecast area on Saturday. North winds are forecast to remain gusty
with lingering seas are forecast to remain through Saturday evening
outside the Charleston Harbor. Small Craft Advisories in effect for
all coastal waters outside the Charleston Harbor through Saturday
evening. A Small Craft Advisory for the outer Georgia waters, from
20nm to 60nm, will remain in effect through Sunday afternoon due to
elevated seas. Low pressure will gradually organize over the Deep
South on Monday, passing over the region on Tuesday and Tuesday
night. Winds will vary with the approach and passage of the low,
remaining below advisory criteria. High pressure is expected to
build across the region on Wednesday with gusty north winds,
possibly reaching around 20 kts.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...Winter Weather Advisory until 7 AM EST Saturday for GAZ087-088-
099>101-114>116-118-138.
SC...Winter Weather Advisory until 7 AM EST Saturday for SCZ040-
042>045-047>052.
MARINE...Small Craft Advisory until 8 PM EST Saturday for AMZ350-352-
354.
Small Craft Advisory until 4 PM EST Sunday for AMZ374.
&&
$$
Area Forecast Discussion
National Weather Service Wilmington NC
944 PM EST Fri Jan 21 2022
.SYNOPSIS...
Freezing rain, sleet, and snow will fall tonight across the
eastern Carolinas. Dangerous travel conditions are expected.
Dry high pressure will build in Saturday keeping the area dry
and cold through early next week. The next low pressure system
moves through Tuesday with a chance of rain. High pressure will
build in Wednesday into Friday.
&&
.UPDATE...
Reports of sleet mixing in with or replacing the freezing rain
are showing up across the Myrtle Beach to Wilmington corridor
this evening. Accumulating sleet is occurring in Whiteville. West
of I-95 snow is becoming the dominant form of precip and
accumulations are starting. The most intense portion of this
winter storm will unfold now through about 2 AM. Changes with
this forecast update include expanding sleet down to the coast a
few hours earlier than anticipated, and minor tweaks to
temperatures.
&&
.NEAR TERM /THROUGH SATURDAY/...
Temperatures are hovering right around the freezing mark across the
CWA this afternoon, with reports of light icing occurring. Areal
coverage of light precip will increase through late afternoon and
evening as moisture surges north and lift is enhanced ahead of the
shortwave currently moving into western TN.
Have made some slight adjustments to the storm total ice and snow
amounts, based on some colder guidance coming in, indicating that a
changeover to snow or snow/sleet may occur for most of the CWA
during the evening hours...closer to midnight along the coast. The
GFS supports this idea, showing healthy moisture and lift in the
-12C to -18C layer, spreading west to east across the forecast area
tonight and exiting the coast around 12Z Saturday.
HRRR continues to pick up on some banding that could develop across
the Pee Dee early this evening and transition east to the coast
overnight. This would enhance potential accumulations, and we`ll
monitor its progression. WPC has tweaked their guidance up a
smidge as well. At this point, it appears that ice accumulation
across the far western CWA may be limited this afternoon and
evening, simply because a changeover to sleet/snow could occur
before much ice can accrete. This would translate to slightly higher
snow amounts, which we have adjust up to 3" or so across northern
Darlington, Marlboro, Dillon and Robeson counties.
Highest ice accretion is still expected across northern Horry
county, northeast across the Cape Fear, where we expect a range of
generally 0.25-0.5".
As the precip exits the coast late tonight, would not be surprised
if flakes are flying all the way to the beaches. Accumulating
snow...albeit less than an inch...is now expected as far east as a
Wilmington to Conway to Kingstree line. East of that line, although
flakes may fall, we are not expecting a significant
accumulation.
All winter weather warnings and advisories will remain unchanged.
Conditions will become extremely hazardous through the remainder of
the afternoon and overnight, and will remain so after sunrise
tomorrow. After lows tonight around 30-32 degrees, highs Saturday
should only reach the upper 30s.&&
&&
.SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY/...
The wintery precipitation will be gone from the forecast area. With
winds dropping Saturday night and multiple types of frozen
precipitation on the ground overnight, the area will see the lowest
temperatures of the year. The forecast will go below guidance, with
temperatures are expected to fall into the teens except at the beach
strands. The Sunday morning lows look to be only a few degrees
warmer than the record lows for the date.
Record Lows Sun Jan 23, 2021
Record Forecast Lows
ILM - 17 2011 19
LBT - 16 2011 17
FLO - 14 1985 18
CRE - 16 2011 21
High pressure across the Carolinas will give way to another cold
front crossing the area overnight Sunday. This time dry, and the
main impact will be increased wind speeds.
High temperatures are expected to rise into the middle 40s inland
to the upper 40s at the coast. Lows at the coast are expected to
fall back into the lower 20s to middle 20 inland and the upper 20 at
the beaches. Highs on Monday will increase into the upper 40s to
lower 50s with a few mid-50s at the beaches.
&&
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
In the middle to upper levels, the low over the southern tip of
Baffin Island north of Hudson Bay continue to send short wave
troughs embedded in the large scale trough. The Carolina`s will see
a low-pressure area develop over the western Gulf and quickly cross
the area ahead of another polar front cross the area on Tuesday.
Then cold high pressure builds over the area later in the week. The
precipitation on Tuesday may begin as a quick scattered snow shower
well inland, but as we quickly warm up Tuesday morning, it will
change over to rain. No accumulations at this time are expected.
Over this period, temperatures will remain below normal.
Highs are will be in the middle the upper 50s and lows in the middle
30s.
&&
.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
Freezing rain falling across the area now is expected to
transition over to sleet and snow between 02-04z at the KFLO
and KLBT airports. MVFR to IFR ceilings will be joined by IFR
visibility where snow occurs. Along the coast there will be a
substantial period of freezing rain lasting through around 07z,
but even here precipitation may end as a period of sleet and
snow between 07z- 10z Saturday. Afterward, low ceilings will
linger through Saturday morning, perhaps even lasting into the
afternoon along the coast, before moisture thins and clouds
diminish.
Extended Outlook...MVFR/IFR conditions continue Fri night into
Saturday. VFR returns Saturday and continues through Monday.
MVFR/IFR possible with next system on Tuesday.
&&
.MARINE...
Through Saturday, Strong northerly flow will continue tonight
and Saturday as low pressure deepens off the Outer Banks. Gusts
will reach 35 knots north of Little River Inlet, where a Gale
Warning will remain in effect. A Small Craft Advisory remains
in effect south of Little River, where gusts will reach 30 kt
tonight. Winds will very slowly diminish on Saturday as the low
lifts away. Seas of 4 to 7 feet are already being
observed...highest in the outer waters of east of Cape Fear, and
these will persist well into Saturday before beginning to
subside late in the afternoon.
Saturday Night through Wednesday, High pressure over the
coastal waters Saturday night through Sunday will give way to a
cold front late Sunday night, and this low will move well
offshore. High pressure will return late Monday, and a quick-
moving low- pressure system in the Gulf of Mexico will combine
with a front from the Northern Plains and will sweep across the
waters on Tuesday. There will be a good chance of rain. High
pressure will return over the waters on Wednesday.
Winds are expected to remain at or below 15 knots until Wednesday
with winds 15 to 20 knots. Overall the winds will be offshore most
of the period. Seas will range from 2 feet near-shore to 4 feet off
the coast. On Wednesday, seas will build to 3 to 5 feet.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...Ice Storm Warning until noon EST Saturday for SCZ054-058-059.
Winter Storm Warning until noon EST Saturday for SCZ017-023-
024.
Winter Weather Advisory until noon EST Saturday for SCZ032-033-
039-055-056.
NC...Ice Storm Warning until noon EST Saturday for NCZ096-099-
105>110.
Winter Storm Warning until noon EST Saturday for NCZ087.
MARINE...Small Craft Advisory until 6 PM EST Saturday for AMZ254-256.
Gale Warning until 6 AM EST Saturday for AMZ250-252.
&&
$$
SYNOPSIS...ILM
UPDATE...TRA/CRM
NEAR TERM...CRM
SHORT TERM...RH
LONG TERM...MAS/RH
AVIATION...TRA
MARINE...RH/CRM
Area Forecast Discussion
National Weather Service Lincoln IL
745 PM CST Fri Jan 21 2022
.SYNOPSIS...
Issued at 328 PM CST Fri Jan 21 2022
Fast-moving systems in northwest flow will bring occasional
chances for light snowfall through the early part of next week.
The best chances for accumulating snow in central Illinois will
be from Saturday night into Sunday morning. Another shot of cold
air is forecast to affect central Illinois from Tuesday into
Wednesday.
&&
.UPDATE...
Issued at 745 PM CST Fri Jan 21 2022
Upper wave stretches from northern Minnesota to southern South
Dakota, per latest water vapor imagery. Cirrus shield ahead of
this wave has crossed the Mississippi River and clouds over the
forecast area will begin thickening soon, though the eastern CWA
should remain fairly clear into late evening. Surface obs area
showing the light snow still north of Des Moines, and the core of
this snow should track north of the forecast area after midnight.
Will maintain sub-20% PoP`s along and north of I-74 later tonight,
with mainly just a threat of flurries in our area.
With the clouds thickening soon northwest of the Illinois River,
low temperatures were bumped up a tad there, but most areas still
are on track, with temperatures holding relatively steady over the
next several hours.
&&
.SHORT TERM...(This evening through Saturday)
ISSUED AT 328 PM CST Fri Jan 21 2022
Visible satellite shows scattered low clouds over portions of
southern and western Illinois fading with time. Winds have become
light from the south as a surface ridge moves off to the
southeast. Expect some increase in south/southwest winds late
tonight as the pressure gradient increases ahead of the next
surface trough, slated to come through during the late morning
hours on Saturday. Cloud cover associated with the upper wave can
currently be seen over portions of the Missouri Valley, and has
moved into western Iowa. Though some light precip could be
associated with this wave north of I-74, snow accumulations are
unlikely. HRRR soundings show a notable dry layer below about
3000-4000 feet that precip may struggle to make it through. We
still included some low probabilities for measurable precip and
have mentioned light snow/flurries in the forecast for early
Saturday morning.
Otherwise, expect temperatures to warm to right around freezing in
most of central Illinois on Saturday with west/northwest winds
behind the morning surface trough. The next, somewhat stronger
disturbance will affect central Illinois on Saturday night/Sunday
morning.
&&
.LONG TERM...(Saturday night through Friday)
ISSUED AT 328 PM CST Fri Jan 21 2022
The next trough/associated surface low is forecast to slide into
central Illinois late Saturday night/early Sunday morning, with
breezy north winds during the day Sunday behind the passage of the
surface low/front. Prior to this, some accumulating snow is
forecast with the greatest amounts expected over areas north of
I-74. Areas where accumulating snow is forecast have come a bit
southward, with the NBM 50th percentile 24-hour snowfall for this
period making a noticeable southward shift in the last 12 hours.
Still, most areas are expected to see snow in the 0.5-1.5 inch
range with only minor impacts expected.
Breezy southwest winds are expected during the day on Monday
before the next cold front makes its way into central Illinois in
the Monday evening time frame. Some brief light precip is
possible behind the front late Monday evening into early Tuesday
morning, but more notable is a closed low ejecting out of the
southwest US as a compact short wave trough passing to our south
on Tuesday. About 25% of ensemble members show 0.25" or more of
precipitation southeast of I-70 on Tuesday in association with
this feature, with the rest mostly dry.
More confidently, a surface high takes hold by Wednesday with
another bout of cold temperatures expected. With winds expected to
be around 10 mph out of the northwest Wednesday morning, we may
need to watch wind chill temperatures as well.
Generally, a pattern with fast-moving troughs traversing the
Midwest in northwest flow is forecast to continue through the
remainder of the week with low probabilities for significant
precipitation.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 522 PM CST Fri Jan 21 2022
Incoming disturbance will result in a general lowering of clouds
through the night, along with winds increasing and becoming more
southwest. Core of the associated snowfall should remain north of
the local terminals, though a bit of light snow or flurries can`t
be ruled out near KPIA/KBMI. Ceilings in these areas should fall
to around 4000 feet toward 12Z, and remain closer to 6000 feet
further south. Once the disturbance passes, winds will slowly
trend toward the west by late morning. Some gustiness is expected
over eastern Illinois into the afternoon, but speeds over 10
knots are expected over the entire area.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Geelhart
SYNOPSIS...AAT
SHORT TERM...AAT
LONG TERM...AAT
AVIATION...Geelhart
Area Forecast Discussion
National Weather Service North Platte NE
530 PM CST Fri Jan 21 2022
.SYNOPSIS...
Issued at 331 PM CST Fri Jan 21 2022
A long wave trough of low pressure was the dominant weather
feature across the CONUS this morning. High pressure was located
north of Hispaniola with a ridge extending north across the
western Atlantic. High pressure was also located around 500 miles
off the coast of northern California. A ridge extended north of
this high into the Alaska panhandle and eastern portions of the
Gulf of Alaska. Within this long wave trough of low pressure, a
shortwave trough extended from the eastern Great Lakes, southwest
into central Texas. Further west, shortwaves were noted over
Wyoming and northern Nevada with another shortwave trough over
Saskatchewan. At the surface, arctic high pressure was the
dominant feature over the western half of the CONUS this morning.
A warm front was situated from eastern North Dakota, south into
western Nebraska. Just east of this feature, a line of
precipitation was present. Along the leading edge of this line,
light freezing rain was occurring, with a change over to snow,
then rain. Skies were mainly cloudy this afternoon with the
exception of the northwest and 2 PM CT temperatures ranged from 23
at O`Neill to 45 at Gordon.
&&
.SHORT TERM...(This evening through Saturday night)
Issued at 331 PM CST Fri Jan 21 2022
Looking at the latest NAM12, and HRRR solns, and clearing across
the northwestern forecast area, precipitation should be ending by
6 PM CT this evening. In the meantime, will send out the zones
with a pre-first period to handle exiting precipitation generally
east of a line from Bassett to Imperial. A weak clipper system
will track across Minnesota overnight with westerly and
northwesterly winds persisting into the overnight. An arctic front
in association with the clipper will dry to back into the far
northeastern forecast area overnight making it to around O`Neill
toward 12z Saturday. With the westerly winds expected overnight
and the arctic airmass east and northeast of the area, overnight
lows will be somewhat milder in the teens. On Saturday, a second
clipper system will dive south from Saskatchewan into southeastern
North Dakota by 00z Sunday. As this system tracks southeast, it
will force the arctic front northeast of the area as a warm front.
Decent westerly winds, coupled with H85 temps of 0 to 3C, will
push highs into the 40s for Saturday. As the clipper dives
southeast into the upper Missouri valley Saturday night, a cold
front will back into the area from the east and make it as far
west as the northeastern forecast area. The core of the arctic air
will remain east of the area Saturday night with only a glancing
shot of it in the northeastern forecast area.
.LONG TERM...(Sunday through Friday)
Issued at 331 PM CST Fri Jan 21 2022
On Sunday, yet another clipper system, will track from southern
Canada into eastern North Dakota. Winds will shift around to the
west once again with even warmer H85 temps noted with readings of
3-6C Sunday afternoon. Highs will be in the lower to middle 50s
which is right at the middle of the NBM. An arctic cold front will
be forced south through the area late Monday bringing a limited
threat for snow, mainly across the west as the arctic air is
forced west into the Panhandle. Current forecast has a mention of
light snow Monday afternoon/night, focused mainly west of highway
83. This agrees well with the latest ECMWF and GFS solns from this
morning. After temps in the 20s/lower 30s Tuesday, temps will
moderate back to more seasonal levels as the core of the arctic
airmass transitions from the Great Lakes east into the Mid
Atlantic. Readings on Wednesday and Thursday will be in the 40s.
This will be followed by upper 40s to around 50 Friday. With the
exception of Monday afternoon/night, the forecast will remain dry
in the predominately northwesterly flow aloft regime.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 528 PM CST Fri Jan 21 2022
Storm systems dropping south through Canada and tracking through
the Dakotas and the upper Midwest will spread dry stable air into
wrn and ncntl Nebraska. The risk of MVFR or lower flight
conditions tonight and Saturday is low, less than 20 percent.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Buttler
SHORT TERM...Buttler
LONG TERM...Buttler
AVIATION...CDC
Area Forecast Discussion
National Weather Service Marquette MI
710 PM EST Fri Jan 21 2022
.SHORT TERM...(This afternoon)
Issued at 101 PM EST FRI JAN 21 2022
Upper air pattern consists of a 500 mb trough in the Rockies and a
trough in the Canadian Prairies this morning along with a trough in
the lower Great Lakes region. The Canadian Prairies trough will move
into the Northern Plains by this evening. In the meantime, the wind
has picked up and become gusty in most places and temperatures are
warming nicely with sunshine out. Did not make too many changes to
the going forecast except added in some small pops in the east with
a Lake Michigan lake effect snow band that is on the edge of ERY and
that will remain through this afternoon and have it dry in the west
through this afternoon.
.LONG TERM...(Tonight through Friday)
Issued at 401 PM EST FRI JAN 21 2022
The weather for the next 7 days will continue to alternate between
cold and not quite as cold but still pretty cold, with multiple
bouts of light snow and lake effect snow - just as it has for past
couple weeks.
Tonight, a cold front will swing across the U.P. from west to east
with a band of light snow. Compared to radar returns over Minnesota,
all of the CAMs are handling its placement well. Leaned on the RAP
and HRRR for timing of POPs overnight tonight. QPF is minimal -
general 0.05-0.1", although some lake enhancement off of Lake
Michigan could boost QPF up to 0.15" over the east. A very thick DGZ
should lead to fluffy snow with SLRs of around 20:1, so that`ll
translate into 1-2" of snow in most areas, with up to 3" east. The
other story will be the gusty SW winds as a strong LLJ moves
overhead. HRRR profiles show 60-70 kt winds in the lowest 1-2 kft
AGL which, when oriented downslope into Marquette and the rest of
Lake Superior shoreline from Big Bay to Grand Marais, should lead to
a few hours of impressive gusts. Have issued a Wind Advisory for
Marquette and Alger Counties this evening to cover the potential for
a few hours of 50 mph gusts and associated blowing snow, although
these stronger gusts will mostly be confined to within a few miles
of the shoreline. Snow will transition to NW wind lake effect snow
tomorrow behind the cold front and then continue through Sunday with
mostly light accumulations.
Another clipper system is likely Sunday night into Monday morning.
Models have come into a good consensus in depicting another fluffy
inch or so of snow, perhaps 2" south central. More NW wind lake
effect snow will develop Monday afternoon behind the clipper and
then continue through late Tuesday night or Wednesday morning. This
looks like another standard NW wind multi-band LES event with light
accumulations, although the GFS hints at perhaps a stronger
convergence band developing into Alger and Schoolcraft Counties late
Tuesday which would lead to locally heavier amounts if it verified.
Tuesday looks like the coldest day of the next 7 with highs in the
single digits. Lows Tuesday night should fall to around -10 to -20
away from the lakes, and not quite as cold where lake effect cloud
cover will persist.
Overall the large scale pattern of western CONUS ridging and eastern
CONUS broad troughing looks to continue through the end of next
week, with temps rising back to near normal for late January by the
end of the week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 710 PM EST FRI JAN 21 2022
Approaching cold front will bring a band of -sn across the area
tonight. Expect intial VFR at IWD/CMX/SAW to fall to IFR soon after
the -sn begins, generally mid evening at IWD/CMX and around 06z at
SAW. In addition, strong low-level jet translating across the area
ahead of the front will lead to LLWS at all terminals for most, if
not all, of the evening. Southerly sfc winds will also be gusty to
around 30kt. After the main band of -sn passes, prevailing MVFR
should be the rule at all terminals overnight. While IWD/SAW should
remain MVFR on Sat, developing lake effect -shsn/blsn will likely
lead to prevailing LIFR conditions at CMX.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 354 PM EST FRI JAN 21 2022
High-end southwest gales are still expected tonight across the lake
with some low-end storm force gusts possible. Therefore, have
upgraded the Gale Warning to a Storm Warning for parts of the
western and north-central lake. The Heavy Freezing Spray Warning
remains in effect. Winds will subside below gale force by sunrise on
Saturday, except for a few marginal gale gusts over the east half
Saturday afternoon. With multiple shots of cold air expected, winds
across the lake will remain in generally the 20-30 kt range through
Tuesday along with periodic bouts of heavy freezing spray. Lighter
winds and decreased freezing spray coverage are expected Wednesday.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
Wind Advisory until 2 AM EST Saturday for MIZ005-006.
Lake Superior...
Heavy Freezing Spray Warning until 7 AM EST Sunday for
LSZ263>267.
Gale Warning until 7 PM EST Saturday for LSZ245>251-265>267.
Storm Warning until 1 AM EST Saturday for LSZ263-264.
Gale Warning until 7 AM EST /6 AM CST/ Saturday for LSZ162.
Gale Warning until 4 AM EST /3 AM CST/ Saturday for LSZ240>244.
Heavy Freezing Spray Warning until 7 PM EST /6 PM CST/ Saturday
for LSZ162.
Lake Michigan...
Gale Warning until 7 AM EST Saturday for LMZ221-248-250.
&&
$$
SHORT TERM...07
LONG TERM...RJC
AVIATION...Rolfson
MARINE...RJC
AREA FORECAST DISCUSSION
National Weather Service Raleigh NC
830 PM EST Fri Jan 21 2022
.SYNOPSIS...
Cold high pressure will extend into the region from the north
through tonight, as a wave of low pressure tracks northeastward
along a front sitting just off the Southeast and Carolina coast. The
high pressure area will continue to extend across the area through
Monday. An upper level disturbance will move in from the southwest
on Tuesday, and will be followed by passage of another Arctic cold
front from the northwest and north Tuesday night. Cold high pressure
will return for Wednesday.
&&
.NEAR TERM /THROUGH TONIGHT/...
As of 830 PM Friday...
Light snow has finally made it to the surface at Roxboro,
Greensboro, and Burlington with light snow back in the Foothills at
Morganton, Hickory, and Mount Airy. We may have to add Winston-
Salem/Forsyth to the Advisory as they are the only hold out at the
current time (and points north deeper into the very dry air in
Stokes and Rockingham Counties). It is just a matter of time before
the light snow reaches them as well. However, getting an inch in
Forsyth will be a reach - and right now we are expecting less than 1
inch (Advisory Criteria). Snowfall rates will climb as the upper
trough approaches. Note that light snow was falling in upstate SC.
The snow will accumulate readily as temperatures are in the lower to
mid 20s.
As for the SE portion of the area, the latest radar and MPING
reports show the snow/freezing rain line now moving SE through far
SE Cumberland, north-central Sampson, and central Wayne. Freezing
rain has changed to snow at Fayetteville (airport in the past ten
minutes). Freezing rain and sleet continues around Clinton and
Goldsboro. This will change in the next few hours to snow.
Otherwise, the snowfall amounts appear on target and no changes are
currently needed based on trends.
Previous discussion as of 655 PM Friday...
Snow has developed and overspread the SE Piedmont/Sandhills and
central and northern Coastal Plain as of 700 PM. The snow/freezing
rain line extended from southeastern Scotland NE across southeast
Hoke, southern Cumberland, and NW Sampson County. Temperatures
were very cold, in the lower to mid 20s allowing the snow to
accumulate quickly to nearly all surfaces, even as light as it has
been thus far.
To the south, light freezing rain was reported at Laurinburg,
Fayetteville (airport), and Clinton. However, this transition line
will progress southeast changing the precipitation type to
snow/sleet then snow in the next couple of hours. Rockingham,
Hoffman and the north side of Fayetteville have already changed to
light snow. Travel will become hazardous quickly as temperatures in
the south were in the mid to upper 20s.
There was a cut off to the snow to the NW where dry air continued to
hold in place over the north-central Piedmont. Dew points were in
the lower teens across the Triad to Roxboro.
Expect the precipitation to continue to fill in and expand
northwest. The Triad continues to be the X factor as the amount of
very cold and dry air at the surface will lead to plenty of virga to
start. Boone has finally started reporting light snow and there
should be enough saturation to get some light snow in the Triad
between 800 and 1000 PM.
The latest radar trends suggest 1/4 to 1/2 inch per hour rates to
develop in the next few hours from near Hoffman to Southern Pines to
Sanford, Raleigh, Louisburg and Halifax eastward into the Coastal
Plain.
The current forecast looks well on track and only a few tweaks have
been made to the weather grids at this time.
Previous discussion... As of 300 PM Friday...
...Have expanded winter weather warnings and advisories back further
through the Piedmont with higher confidence in pockets of greater
snowfall amounts...
Winter storm warnings are now in effect for areas along and
southeast of a line from Wadesboro to Roanoke Rapids. Winter weather
advisories have been issued for areas northwest of here for the
remainder of central NC except Forsyth.
Latest guidance and observed trends are increasingly supportive of a
high potential for heavy snow bands to develop over portions of
central and eastern NC over the next 15 hours, with the focus on the
7p-3a time frame. The latest surface analysis shows frigid high
pressure nosing down through central NC with cold/dry air advection,
including single-digit dewpoints just to our N. Radar continues to
show spotty elevated returns facing this dry subcloud layer and thus
not reaching the ground. However, this is expected to change as the
deep layer forcing for ascent strengthens as we head into the
evening, resulting in saturation of the column and a blossoming of
wintry precip over central NC, all in tandem with a band of
increasing H7-H5 fgen from the central Piedmont E nearly to the
coast between 02z and 08z. Most large scale models depict much
stronger and more focused upper divergence over north-central and
northeast NC than previous runs showed, and the potent mid level
shortwave trough crossing the region this evening/tonight now takes
on a neutral to slightly negative tilt as it reaches central NC.
High res model guidance including recent HRRR runs also show well
the bands of heavier precip starting this evening. Much of the area
will see a fully below-0C column except for the SE, roughly along/SE
of a Maxton-to-Goldsboro line which will see some warming aloft,
although the expected degree of glazing in the SE has trended lower
in recent model runs, and even this area may see decent snowfall
with fairly light icing except for areas SE of Clinton. Given the
higher confidence in the occurrence of heavy snow bands, have bumped
up storm total snow to 2.5-4.5" along and east of a Wadesboro-to-
Roanoke Rapids line. Areas NW of here will likely see some snow, but
lasting a shorter time and with a lower threat of heavy snow, so we
issued an advisory for the remainder of the area, except Forsyth,
for snow totals up to 2". A quick exit of the precip from W to E is
expected by sunrise or very soon thereafter. Lows from the teens to
lower 20s. Chilly NW winds through the night will culminate in
daybreak wind chills into the single digits to lower teens. -GIH
&&
.SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/...
As of 110 PM Friday...
The central of the coastal low bringing precipitation tonight will
have moved well offshore by sunrise. While precipitation will remain
along the North Carolina coastline, our local forecast area should
be clear of precipitation. Clouds will linger through the morning
east of US-1, but by the afternoon, skies should be mostly sunny
everywhere. Northerly winds will continue through the day, and while
highs will be warmer than today, they will still be well below
normal, primarily in the mid to upper 30s. Only a small amount of
melting will be able to occur with temperatures barely rising above
freezing.
The wind will become light and variable overnight, and with the
addition of mostly clear skies and fresh snow cover in many
locations, conditions will be prime for radiational cooling.
Forecast lows are in the mid-teens, and temperatures will likely be
colder in locations where snow remains on the ground. The hard
freeze will certainly melt any precipitation that manages to melt
during the daytime hours.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
As of 110 PM Friday...
Broad high pressure will extend across the southeastern United
States Sunday and Monday. A surface low will move from Minnesota
Monday to northern New York Tuesday and continue northeast along the
Canadian border into Wednesday. The associated cold front will
extend all the way south into Texas and the Gulf of Mexico. This
part of the forecast has not changed from 24 hours ago; however, the
new wrinkle in the forecast is the GFS and ECMWF both spinning up a
wave of low pressure along the southern end of the cold front along
the Gulf Coast which will travel across Florida and over the
Atlantic Ocean. The second low would likely help to bring additional
moisture into the Carolinas from the Atlantic Ocean. Will continue
with 40-50 pops Tuesday and drop pops to 20-30 Tuesday night.
Continue to think that precipitation may briefly start as snow in
the morning, quickly change over to rain, fall primarily as rain,
then possibly change over to snow before ending Tuesday night. High
pressure will then dominate the eastern half of the country
Wednesday and Thursday, with a system remaining to the north over
the Great Lakes on Friday.
Temperatures will remain below normal the entire week. Highs will be
in the 40s Sunday through Tuesday before the cold front drops highs
back into the 30s and 40s for Wednesday and Thursday and some
moderation occurs Friday. The coldest night will be Wednesday, with
lows dropping into the upper teens and lower 20s. Several melting
and re-freezing cycles can be expected of tonight`s snowfall.
&&
.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
As of 640 PM Friday...
IFR to LIFR conditions with areas of snow and fog can be expected
through 06z at KRWI and KRDU, with KFAY transitioning from light
freezing rain to snow around or before 02z-03z. The KINT and KGSO
areas will be on the edge of the snowfall and thus will likely have
MVFR to VFR CIGS and VFR VSBYS with only very light snow through
around 06z. The snow will begin to taper off from west to east
between 06z and 09z from KRDU to KRWI/KFAY. A return to VFR
conditions can be expected between 09z and 12z in the east.
VFR conditions are expected in all areas on Saturday and Saturday
night.
Looking beyond 18Z Saturday: VFR conditions will dominate from late
Saturday through Monday as high pressure builds in. An approaching
front and upper level trough will bring a risk of sub-VFR conditions
with rain chances on Tuesday.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning until 7 AM EST Saturday for NCZ011-026>028-
040>043-074>078-083>086-088-089.
Winter Weather Advisory until 4 AM EST Saturday for NCZ007>010-
022>025-038-039-073.
&&
$$
SYNOPSIS...Hartfield
NEAR TERM...Badgett/Hartfield
SHORT TERM...Green
LONG TERM...Green
AVIATION...Badgett/Kren
Area Forecast Discussion
National Weather Service Sacramento CA
1254 PM PST Fri Jan 21 2022
.SYNOPSIS...
Strong north/east winds today and tomorrow. Continued dry next
week with lighter winds.
&&
.DISCUSSION...
The strong offshore winds have arrived to northern California
today. Already observing very strong gusts in the Sierra Nevada
with Hell Hole RAWS station (Placer County, 5240 ft elevation)
reporting a gust of 57 mph at 12 PM PST. The strongest gusts in
the Sacramento Valley have been so far confined to the far
western side, extending into the Delta region. Travis Air Force
Base is reporting north winds with a gust of 40 mph at 12 PM PST.
Strengthening offshore surface pressure gradients are responsible
for these strong offshore winds. If it were to be September/
October/November, we would have fire weather concerns with this
pattern setup. Fortunately, plentiful precipitation over the past
3 months have eliminated fire weather concerns this time around.
The north-south gradient will peak later today/tonight, followed
shortly thereafter with the peak of the east-west gradient
tonight/early tomorrow. As has been previously mentioned, wind
speed/gust forecasts have been gradually trending upward over the
last 48 hours. Look for peak gusts of 50-70 mph along/west of the
Sierra crest, locally higher at wind-prone peaks, gaps, and
canyons. Latest high-res guidance such as the HRRR and 3 km NAM
are very concerning, and depict these strongest gusts well.
Official forecast winds and wind gusts incorporate this guidance.
For the Sacramento Valley, peak gusts will range between 30-45 mph
with the strongest gusts, and locally higher gusts along the west
side of the Sacramento Valley and into the Delta area (i.e.,
Solano County).
Impacts associated with these strong winds include the potential
for downed trees, particularly in the mountains where the
strongest winds are forecast; possible power outages; and
difficulty with travel for high-profile vehicles. Furthermore,
expect mountain recreation impacts for those planning to hike,
ski, and/or snowshoe today/tomorrow. Exercise extreme caution if
venturing into forested areas as conditions will be dangerous with
the strong winds!
Winds will begin to subside during the day on Saturday, and
continue to decrease overnight Saturday. Dry, light offshore flow
will persist through the weekend and into Monday with above-normal
temperatures expected to continue. // Rowe
&&
.EXTENDED DISCUSSION (Tuesday THROUGH Friday)...
Ensembles and clusters remain in solid agreement with upper level
ridging over the West Coast through much of next week. Could see
a weak trough approach the West Coast in the Day 7-8 timeframe, as
is depicted in the ensemble means and a few clusters. For now,
the National Blend of Models keeps the chance of measurable
precipitation at 10 percent or less region-wide through next week
Friday. // Rowe
&&
.AVIATION...
VFR conditions across interior NorCal next 24 hours. Widespread
with gusts 25-40 kts in the Valley and gusts 30-50 kts in portions
of the foothills and mountains, locally up to 70 kts over the
Sierra Nevada through 00Z Sunday.
&&
.STO WATCHES/WARNINGS/ADVISORIES...
High Wind Warning until noon PST Saturday for West Slope
Northern Sierra Nevada-Western Plumas County/Lassen Park.
Wind Advisory until 7 AM PST Saturday for Carquinez Strait and
Delta-Central Sacramento Valley-Mountains Southwestern Shasta
County to Western Colusa County-Northern Sacramento Valley-
Northern San Joaquin Valley-Southern Sacramento Valley.
&&
$$
...Update to aviation forecast discussion...
.DISCUSSION...
Issued at 225 PM CST Fri Jan 21 2022
Recent water vapor imagery showing a broad upper trough axis from
southern Saskatchewan to the Great Basin with two stronger waves in
the trough -- one moving east-southeast on the northeast end and
another moving south on the southwest end.
Scattered radar returns over northwestern Nebraska have produced
very light precipitation per objective observations, and forcing for
ascent as the mean trough pushes southeast and the aforementioned
stronger anomalies split around the region keep precipitation
chances low as the trough slides through tonight into Saturday
morning. Model soundings do show quite a bit of cloud cover moving
through with decent lapse rates in the ice crystal formation layer,
though ascent is meager and the low-levels continue to stay dry.
Have kept any precip mention out but, as previously mentioned, a few
areas of flurries could materialize. The cloud cover helps keep
tonight`s temperatures much warmer than recent nights. Deeper
northwest winds mix some warmer air down for Saturday with highs
back near normal. Another weak frontal system passes through the
area Saturday night and with some cirrus again keeping temps up with
similar highs on track for Sunday.
A shortwave trough diving south out of western Canada Sunday night
into Monday ushers the southwest states cut-off low east across the
southern Plains and a Canadian airmass into the local region Monday
night into at least Wednesday. Monday`s temps should still be able
to reach the 50s even with a late-day frontal appearance and with
the main upper waves again flanking Kansas, precip chances are
rather low. Wind chill values may fall a bit below zero both Tuesday
and Wednesday mornings in the cold air. Temperatures may rebound for
Thursday as another wave enters the central states from the
northwest though the airmass behind this again looks modified for
little cooling for Friday. Precipitation chances continue to look
low in this regime though light amounts can`t be ruled out around
Thursday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 539 PM CST Fri Jan 21 2022
Main thing to watch is an area of MVFR stratus currently
stretching from northwest KS into central NE. Model guidance
suggests this should lift by the time it moves across TAF sites
overnight; main question is by how much. Have leaned on RAP for
timing and cigs as it appears to be handling the current situation
reasonably well based on upstream obs, but cigs could still lift
faster if this is too pessimistic. VFR looks likely to persist,
though cigs near 3000 ft remain possible overnight before skies
clear out. There could also be a brief period of directional LLWS
around sunrise as winds veer near 1000 ft, but confidence is too
low to include at this time.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
DISCUSSION...65
AVIATION...Picha