Forecast Discussions mentioning any of
"ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 01/07/24
Area Forecast Discussion
National Weather Service Indianapolis IN
904 PM EST Sat Jan 6 2024
.Key Messages...
- Drizzle/patchy fog through the rest of the afternoon.
- A weak system tonight will bring additional light snow with
amounts up to an inch north of Indianapolis.
- Few changes to forecast with storm system Monday night into early
Wednesday; primarily rain and gusty winds expected much of the
event, with a brief burst of light snow accumulations possible at
the onset and ending Monday night and Tuesday night. Impacts to the
Wednesday morning commute possible.
- Yet another strong winter storm is possible in the Midwest late
next week into the weekend. Much too early for details but continue
to watch for possible impacts.
&&
.Forecast Update...
Issued at 903 PM EST Sat Jan 6 2024
At 02z, radar was showing very light returns were occurring mostly
near and west of the Interstate 65 corridor, where wet bulb
temperatures per SPC mesoanalysis were at least a degree or two
above 32 degrees. That said, northeastern sections were right around
freezing and Hi-Res soundings are showing a freezing level well
below 1000 feet with saturation up to 25K feet. This suggests snow
will at least mix in with rain over but perhaps extreme southwestern
sections where temperatures are in the upper 30s. BUFKIT supports
mostly snow over northeastern sections. Although, forcing was not
very impressive with the upstream trough, 180 kt 250 millibar jet
streak over northern Kentucky and the saturated column should allow
precip to expand. Still, it looks like up to an inch is possible by
daybreak near and north of I-74 with negligible accumulation
southwest of I-74. Any snow will be wet and with unimpressive winds
along with the snow, issues should be minor.
&&
.Short Term...(This evening through Sunday)
Issued at 312 PM EST Sat Jan 6 2024
Rest of Today.
Lingering low clouds and abundant near surface moisture has led to
occasional drizzle with lowered visibilities across central Indiana.
Temperatures at Indianapolis have only varied by 3 degrees between
31 and 34 since midnight and with sunset approaching, not expecting
any more than a 1 degree increase through the rest of the day. With
surface temperatures just above freezing, there haven`t been any
impacts from the drizzle but will continue to monitor this ahead of
the loss of the minimal daytime sun. ACARs soundings combined with
IR satellite show that the top of the cloud layer lacks ice which is
leading to the drizzle vs snow as seen earlier.
Tonight.
This cloud layer will begin to deepen later into the evening and
overnight hours with ice nucleation expected to begin around 7-8PM
which will coincide with a weak wave that is expected to move across
the northern counties to bring another quick hitting snow. There is
little to no vorticity with this system with snow being driven more
by lift within the 600mb to 850mb layer which is much less
substantial than what was seen during the overnight hours last night.
This snow should generally remain isolated to points along and north
of I-70 with amounts no greater than an inch for most spots with
most areas seeing closer to 0.50". Temperatures tonight will remain
near steady state with lows in the low 30s with westerly winds
beginning to strengthen as pressure gradients briefly tighten across
the forecast area.
Sunday.
Similar weather is expected for tomorrow with some lingering low
clouds in the morning with drier air gradually working in. Non-zero
instability will arrive by the afternoon with dry adiabatic lapse
rates up to the top of the boundary layer at around 3kft with drier
air above it. This could have led to some brief convective snow
showers/light rain if the top of the cloud layer had been a bit
cooler combined with a weaker cap at the top of the boundary layer,
but with those limitations expect just a few areas of heavier
sprinkles or perhaps light snow mid to late afternoon with much of
the precipitation ending by noon.
&&
.Long Term...(Sunday night through Saturday)
Issued at 312 PM EST Sat Jan 6 2024
Very active long term period across central Indiana, with at least a
couple of impactful systems likely for the region.
The first round of the week comes Monday night into early Wednesday.
A very strong low pressure system will pull quickly northeast out of
the Texas Panhandle into central Illinois and northwest Indiana late
Monday into Tuesday evening. Ensemble guidance is very well
clustered with a low track near or just northwest of the northwest
corner of the forecast area, which will keep central Indiana in the
warm sector and all rain for the bulk of the event.
However, Monday night presents an opportunity for a quick burst of
accumulating snow on the leading edge of the precipitation, despite
borderline near surface temperatures - forecast profiles show a deep
near-isothermal layer near or just below 0C, and with the onset of
strong frontogenetic forcing at the nose of the low level jet Monday
night, dynamic cooling may offset midlevel warm advection for a few
hours either side of midnight and allow for a burst of briefly heavy
snow to accumulate, potentially up to an inch or two, primarily from
Indy northward.
However, strong low and midlevel warm advection as we approach
daybreak Tuesday will rapidly produce a changeover to rain, with
rain continuing through the day on Tuesday. Precipitable water
values continue to exceed climatological 90th percentile much of the
event, with probabilistic guidance showing rainfall amounts in
excess of a half inch a virtual certainty (90%) and in excess of an
inch a significant likelihood (50-60+%), which may put a slight dent
in the longer term drought conditions. Some minimal upright
instability is present in some forecast profiles, and given the
strong dynamics present throughout the depth of the troposphere,
some elevated convection/embedded thunder cannot be ruled out, but
remain uncertain and will not include for now.
As the low continues to wrap up and move rapidly northeast into the
central Great Lakes, onset of cold advection Tuesday night will
promote a potentially rapid changeover back to a mix or all snow,
with potential for another brief burst of accumulations in the
plentiful wraparound moisture before precipitation tapers off late
Tuesday night into Wednesday morning as the column dries from aloft.
Will have to monitor for possible impacts to the Wednesday morning
commute.
Some of the guidance suite produces a weak clipper-type system
moving through the Great Lakes late Thursday into Friday, with
additional potential for light snow or a mix across portions of the
area, particularly north.
Models then show another strong low somewhere in the region Friday
night into Saturday, but extremely large ensemble spread and model-
to-model inconsistencies give very low confidence on precipitation
types and amounts - but another round of impactful precipitation is
on the table.
It remains very important to avoid keying in on one model, one run,
or one cherry-picked extreme solution, particularly for the late
week system, and to instead monitor trends and updates from trusted
sources as the week wears on.
&&
.Aviation...(00Z TAF Issuance)
Issued at 606 PM EST Sat Jan 6 2024
Impacts:
- IFR to LIFR ceilings through around 16z Sunday, then MVFR
- IFR visibilities in rain and snow possible mainly 02z-07z
Discussion:
Poor flying conditions are expected through Sunday morning as a weak
wave moves through. This will bring a light rain and snow mix to the
terminals as well this evening and overnight.
Winds will be light from the west and increase to 10 knots or so
late Sunday morning.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Update...MK
Short Term...White
Long Term...Nield
Aviation...MK
Area Forecast Discussion
National Weather Service Louisville KY
937 PM EST Sat Jan 6 2024
.Forecast Update...
Issued at 736 PM EST Sat Jan 6 2024
Broad troughing coupled with being located under the left exit
region of a strengthening upper-level jet is allowing for some
precip to form. Current ACARS soundings show a low-level moist layer
with subsidence aloft, therefore have added some light drizzle into
the grids. This drizzle will transition to rain as a low-mid level
wave of moisture moves into the region, allowing for the mid-level
subsidence layer to erode. Additionally, low stratus is leading to
areas of lowered visibilities east of I-65 and specifically over the
Bluegrass region. Have added some patchy fog to the grids.
Issued at 936 PM EST Sat Jan 6 2024
Drizzle is beginning to transition to rain, due to mid-level
saturation. Light rain will continue to move through the region in
the overnight hours. Around 12Z there is a chance for rain/snow mix
as the near-surface thermal layer becomes limited and may also be
driven by precip rate. Not expecting any measurable snowfall,
however, we will likely measure a few hundredths to a tenth of an
inch of rainfall.
&&
.Short Term...(This evening through Sunday)
Issued at 325 PM EST Sat Jan 6 2024
=====================================================================
Key Messages...
- Cloudy skies and cool temperatures continue tonight through the
day on Sunday. (High confidence)
- Scattered light rain showers develop this evening, potentially
mixing with snow tomorrow morning. Total precipitation less than
0.10". Snow accumulations not expected. (Medium confidence)
=====================================================================
A broad, wavy upper level trough continues to move eastward from the
central to the eastern CONUS this afternoon, with inclement weather
being experienced by a large portion of the country. The lead
shortwave within the larger trough is associated with the system
that moved through our region this morning, and is lifting off to
the north and east at this hour. Behind the leading shortwave is a
broader trough currently entering the Mississippi Valley. This
feature will move across the Ohio Valley tonight into tomorrow,
providing support for broad, weak mid-level rising motion through
early Sunday morning.
In the low levels of the atmosphere, abundant moisture in the sfc-
850 mb layer has resulted in an expansive stratus shield which
currently extends from east Texas all the way into central Canada.
This area of dense cloud cover should remain over our region over
the next 24-36 hours, with persistent low-mid level cold advection
keeping moisture locked in place. This cold advection will cause low-
level lapse rates, which are currently near isothermal, to steepen
overnight tonight. As a wave of slightly deeper moisture (at least
up to 700 mb) moves through the region later tonight, it will
overlap with the aforementioned steepening lapse rates and synoptic
scale lift from the upper trough to promote the development of
scattered rain showers. As was the case this morning, the near
surface layer will initially be well above freezing, with
precipitation type expected to be rain through at least 06Z Sunday.
However, as cold advection begins to work down to the surface toward
sunrise Sunday, it is probable (50-70% chance) that the heavier
showers will mix with or change to snow. Later Sunday morning
(especially after sunrise), the deeper moisture aloft will exit the
region to the east, limiting DGZ saturation and rain/snow potential.
Overall, the available moisture is fairly meager, so not expecting
much in the way of QPF tonight into tomorrow morning (generally less
than 0.10"). As a result, little to no impacts are expected from and
snow which develops, and temperatures should remain above freezing
in most locations where snow falls.
Late Sunday morning through Sunday afternoon, clouds are expected to
remain overhead as the effects of increasing mid-level heights and
temperatures takes its time in working down toward the surface. 10-
15 mph westerly winds will develop during the morning and continue
through the afternoon hours as the low-level pressure gradient
strengthens between high pressure over the NW Gulf of Mexico and low
pressure off of Long Island. Temperatures should only rise into the
upper 30s and lower 40s Sunday afternoon, with wind chills making
things feel even cooler.
.Long Term...(Sunday night through Saturday)
Issued at 250 PM EST Sat Jan 6 2024
=============================================================
Key Messages:
* Widespread Rain and Very Gusty Winds Tuesday
* Continued Gusty Winds and a Lingering Wintry Mix Possible into
Wednesday
* Another Strong Storm System Possible Late Week
===========================================================
Sunday Night - Monday...
We start the extended with a brief dry spell as surface high
pressure and progressive upper ridging control our area through
Monday. After a chilly start with lows in the mid to upper 20s,
Monday high temps see a nice diurnal rise well into the 40s to
around 50 across our south. These values look to be about 2 to 5
degrees above climo for this time of year.
Monday Night - Wednesday...
An intensifying exit region of a mid to upper level jet overspreads
the mid Mississippi River Valley on Monday night to the Great Lakes
region by Tuesday. This supports strong upper divergence in the
region, along with some aid from a loosely coupled upper jet
structure over the lower Great Lakes region later Tuesday. This will
lead to pretty rapid cyclogenesis during that time as a
strengthening surface low tracks from the Red River Valley (~997mb)
Monday evening, to the mid Mississippi River Valley (~993mb) Tuesday
morning, and then the lower Great Lakes region (~982mb) by Tuesday
evening. Ahead of these features, expect increasing precipitation
chances over our CWA on Monday night as the low level jet responds
with 60-70 knot core and strong Gulf moisture transport. Looking for
a 100% chance of rain late Monday night into Tuesday given the 90+
percentile PWATs and the degree of forcing it appears this setup
lends. Overall, still looking for a widespread 1 to 2 inches of
beneficial rainfall over our area.
The rainfall is the easy part of this system, however a couple of
other hazards/concerns that continue to be monitored. First off, the
onset of precipitation continues to be a close call on whether we
see an initial batch of wintry mix as web bulb temps will be near
freezing at the beginning of the event and before the H85 jet core
really kicks in. This remains a possibility, however wouldn`t expect
much impact from it as the warm air would quickly take over and
widespread rainfall would commence. The next concern, and perhaps
the biggest, with the initial system will be the gusty winds given
the strengthening surface low and resulting pressure gradient. This
combined with potential for increased BL mixiness as a modest "warm
sector" gets established on Tuesday. A third component that could
contribute to increased gusts is the consistent signal that the dry
slot works into our area (at least the southern CWA) by late
afternoon into the evening. As a result of all these factors,
widespread 30 to 40 mph still looks like a high confidence bet, with
stronger gusts over 40 mph also pretty likely for some. Right now
the best locations for this to occur would be across
southern/southeastern KY Tuesday afternoon into the evening. For
reference, LREF probs paint the highest probabilities of 40+ MPH
wind gusts in those areas. A Wind Advisory, at least for some,
appears pretty likely. Still can`t rule out that stronger wind
messaging could be needed on Tuesday, but that would depend on
getting some overlap of the dry slot and strong LLJ core above 50
knots. The window for that may be short-lived as the strongest LLJ
core should be displacing east by that time, but definitely
something to monitor.
The final component to this impressive storm system happens on
Tuesday night into Wednesday as the surface low quickly lifts off to
the NE. We see cold advection take hold with steepening lapse rates
and comma head deeper moisture wrapping back in. Surface temps
should drop to around or just above freezing, and with the
steepening lapse rates some gusty rain/snow showers will likely
develop. Just how gusty depends on those lapse rates, but overall
winds should drop off a bit from Tuesday PM values. This gusty
rain/snow shower threat would last into Wednesday, however something
interesting is that low level winds remain pretty strong into the
day Wednesday, and with "mixed" BL, another very gusty (perhaps
another Wind Advisory?) day is likely. LREF probs again support a
fairly good likelihood of that for some. As mentioned in the
previous forecast, some snow accums could be possible Tue night into
Wednesday, but too early to speculate on what those numbers would
be.
Wednesday Night - Saturday...
Lower confidence into late next week as there should be a largely
dry stretch between Wednesday night and Thursday night. However,
some signal for a another weak system to pass through on Thursday,
which is hurting confidence in that dry stretch just a bit. Another
stronger storm system continues to show up in the data for the
Friday into Saturday time frame, and will be another one to watch.
Overall, looks like a pretty active stretch of weather into mid and
late January.
&&
.Aviation...(00Z TAF Issuance)
Issued at 622 PM EST Sat Jan 6 2024
Summary: IFR or lower CIGs through Sunday morning and rain showers
move through in the overnight hours bringing some lowered VIS.
Discussion: Currently, some low-level moisture below the DGZ, lift
from broad troughing, and being located within the left exit region
of a strengthening upper-level jet is allowing for light drizzle to
form over the region. Later tonight, troughing coupled with a
vorticity maximum and a wave of low-mid level moisture will allow
for some showers to form and move through the region. Ptype will be
primarily rain through most of the night, however, in the early
morning hours, wouldn`t rule out a rain/snow mix with heavier precip
rates. As showers move through the terminals, some lowered VIS
around 4-5SM is possible. Sunday morning, CIGs should rise to low-
end MVFR and slowly lift through the day.
Confidence: Medium-High
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...None.
KY...None.
&&
$$
Update...SRM
Short Term...CSG
Long Term...BJS
Aviation...SRM
Area Forecast Discussion
National Weather Service Miami FL
651 PM EST Sat Jan 6 2024
...New UPDATE, AVIATION...
.UPDATE...
Issued at 640 PM EST Sat Jan 6 2024
The weather this evening is beginning to settle down with a line
of showers and storms pushing south into the Keys and southern
waters. Overnight, additional shower development is eventually
expected to take place with scattered showers and potential
isolated storms most of the day on Sunday. Unlike today, severe or
near-severe storms are not expected for tomorrow. Temperatures
will fall into the 60s tonight and for the early morning tomorrow.
&&
.SHORT TERM...
(Rest of today through Sunday)
Issued at 1238 PM EST Sat Jan 6 2024
Unsettled weather conditions will be likely this afternoon as a line
of storms moves across our area ahead of the passage of a cold
front. As of noon-time today, this line was just starting to enter
South Florida, with leading stratiform rain and ample cloud coverage
helping limit instability over land. A few storms over the waters
have benefited from stronger instability resulting in frequent
lightning, strong winds and at least one waterspout reported by
aircraft pilots.
As the line continues to move over our area this afternoon,
environmental parameters will be favorable enough for a few strong
to marginally severe thunderstorms to develop across portions of the
southwest coast and interior South Florida, namely portions of
Glades, Hendry, Collier and inland Palm Beach counties. With a
paucity of instability but ample shear in place, the main concerns
remain strong, damaging winds and a few tornadoes. Chances for
severe impacts decrease further south and east over our area,
where scattered showers and a few garden-variety thunderstorms
could be possible through the evening hours. Gusty southerly winds
will prevail during this time, with gusts up to 25 kts possible.
The aforementioned front is anticipated to drop through our area
overnight into tomorrow morning, with enough lingering moisture to
support isolated showers developing across southernmost portions of
the peninsula and the local waters. Winds will veer from the
north-northwest once the front pushes through.
Temperatures overnight will remain in the 60s across much of South
Florida, and could rise to the low-mid 70s tomorrow as cooler air
advects over the area.
&&
.LONG TERM...
(Sunday night through next Friday)
Issued at 130 PM EST Sat Jan 6 2024
We`ll start the week off dry with high pressure over the Mid-
Atlantic in control. On Tuesday a system in the middle part of the
country will race towards the Great Lakes by early Wednesday. A cold
front associated with this system will cross the area overnight into
early Wednesday morning. There will be a severe threat to our north
during the day on Tuesday where the dynamics will be better, however
they become less impressive by Tuesday evening and night across
South FL when the precip arrives on our doorstep. A few stronger
storms may be possible across the lake region, but the threat looks
fairly minimum at this point in time.
Dry weather then returns for the middle to end of the work week as
high pressure builds into the region. Another front may bring
showers and isolated thunderstorms to the region next weekend, but
there is still plenty of uncertainty on timing and strength this far
out.
Temperatures will oscillate between slightly below normal and
slightly above normal this week, with the warmest days being Tuesday
and Friday ahead of approaching frontal boundaries. Highs those days
will be in the lower 80s. Otherwise, the rest of the week will see
high temps in the 70s. The only chilly night of the week looks to be
Wednesday night with lows in the upper 40s to upper 50s. Otherwise,
generally looking at seasonal lows in the 50s/60s this week.
&&
.AVIATION...
(00Z TAFS)
Issued at 640 PM EST Sat Jan 6 2024
Generally VFR begins the period as showers and storms continue to
taper off, but additional shower development later tonight and
plenty of low level moisture present will result in potential MVFR
or lower CIGs with MVFR included already. Short-fused amendments
for any heavier rain showers in this period will be possible.
Winds will be lightly breezy around 8-10kts the whole period and
will be shifting often from SW tonight, to NW Sunday afternoon,
and eventually N/NNE Sunday evening.
&&
.MARINE...
Issued at 1238 PM EST Sat Jan 6 2024
Modest southerly flow continues today ahead of an advancing frontal
system. Scattered showers and isolated thunderstorms are possible
across local waters in association with an approaching cold front.
Hazards for mariners include strong to damaging wind gusts,
lightning and the potential for waterspouts. Winds will increase and
turn northerly behind the frontal system, causing elevated wave
heights up to around 9 feet. These dangerous conditions may persist
into the early part of the upcoming week, with moderate to breezy
northerly winds remaining intact.
&&
.BEACHES...
Issued at 1238 PM EST Sat Jan 6 2024
A high risk of rip currents will persist along all East Coast
beaches this weekend as onshore flow continues. As winds strengthen
and shift to the southwest, the risk for rip currents along the Gulf
&&
.PRELIMINARY POINT TEMPS/POPS...
Miami 69 74 64 74 / 50 40 0 0
West Kendall 67 76 61 76 / 50 40 0 0
Opa-Locka 68 75 63 76 / 50 40 0 0
Homestead 69 77 64 76 / 30 30 0 0
Fort Lauderdale 67 74 64 75 / 50 40 0 0
N Ft Lauderdale 67 73 64 75 / 40 40 0 0
Pembroke Pines 66 75 62 76 / 50 40 0 0
West Palm Beach 65 72 61 74 / 30 30 0 0
Boca Raton 66 74 63 76 / 50 30 0 0
Naples 64 70 56 75 / 40 30 0 0
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...High Rip Current Risk through Sunday evening for FLZ168.
High Rip Current Risk through Sunday morning for FLZ172-173.
AM...Small Craft Advisory until 7 PM EST this evening for AMZ650-651-
671.
Small Craft Advisory until 11 PM EST this evening for AMZ670.
GM...None.
&&
$$
SHORT TERM...ATV
LONG TERM....CMF
AVIATION...Redman
Area Forecast Discussion
National Weather Service Reno NV
205 PM PST Sat Jan 6 2024
.SYNOPSIS…
The first significant winter storm for this season is now crossing
into the Sierra with periods of strong valley wind gusts, heavy
Sierra snow, and light to moderate snow accumulations into western
NV. Overnight Sunday into Monday will see the coldest air so far
this winter season. Additional cold storms are stacking up in the
Pacific for possible impacts by mid to late next week.
&&
.DISCUSSION…
At the time of this writing, WFO Reno is being blasted by a strong
southwest downslope flow across our area. A wind gust to 72 mph was
observed up in the weather office at 10:37 this morning. Snow is
just now spilling over the Carson Range section of the Sierra
Front, and giving off that ominous winter-like appearance across
the Truckee Meadows. The main forcing supporting the inbound cold
front is quickly driving southeast spreading snow and snow
showers across the region right now!
STRONG WINDS:
* Stronger southwest winds will continue through this afternoon with
gusts 40-50 mph for many areas across western NV. Higher terrain
across the Sierra crest will see gusts reaching 100 mph or more,
adding to brief near blizzard conditions across higher elevation
areas. Until the cold front drives further south and east, don’t
expect a quick cessation of winds until pressure and thermal
gradient loosen later this evening.
* Wind prone areas like the I-580 corridor through the Washoe
Valley, the US-395 corridor through Mono County, and US-95 south
of Fallon to Hawthorne will still see wind gusts 50-65 mph
through the remainder of this afternoon into the early evening.
Be advised, as moderate to heavy precipitation becomes more
widespread across the Sierra and western NV, the stronger winds
will begin to dissipate into the evening, and the general wind
flow at the surface and aloft will shift more northerly through
Sunday.
* The most notable impact will be felt by high profile vehicles
traveling along more north-south roads and highways across the
Basin and Range from now till at least 6-8PM this evening.
SNOW CONTINUES:
* Central Sierra-Lake Tahoe Basin: Dependent upon your flavor of
blended model guidance, snowfall rates this afternoon into the
evening will vary 1-2”/hr with bursts of 2-3”/hr in more
convection bands across the central into the eastern Sierra. This
equates to a 60-80% chance of snowfall totals of at least a foot
or more across the Sierra crest dependent upon liquid-to-snow
ratios approaching 18:1 to 20:1. There is also a 30-40% for snow
totals approaching 2 feet around higher elevation areas along the
western edge of the Lake Tahoe Basin by the time the storm heads
further south later this afternoon.
* Western NV valleys may pick up an inch or two of accumulated snow
before the last bands of snow push out of the area with the
exiting cold front. Some snow shower bands may loiter for a few
hours after the main snow area pushes through later this evening
(including lake-effect potential south of Tahoe), with snow shower
activity winding down by later tonight to midnight in southern
Mono-Mineral counties.
* Temperatures dropping quickly below freezing tonight will keep
untreated, snow covered roads icy into Sunday morning. Even
though the snow has all but ended, it is advised to take it slow
if on area roadways, and give plenty of room for those vehicle
in close proximity.
DID SOMEONE SAY LAKE EFFECT SNOW? The combination of a much
colder northerly flow spreading across the Sierra and western NV,
and relatively warmer large area lakes, the risk for lake effect
snow lingers till at least midnight. Although not an optimal setup
of reduced low and mid level shear, steep low-mid lapse rates,
and convective instability, areas on the lee-downwind side south
of Pyramid, Tahoe, Mono, and Walker Lakes may see lingering bands
of light snow adding up to an inch of snow.
COLDEST SEASONAL TEMPS: Now that we are on the subject, this colder
northerly flow will pull south what can be considered the coldest
air of the season. Lows overnight Sunday into early Monday will
drop at least 10°F to as much as 25°F below seasonal averages.
Overnight Sunday, some areas across the Sierra crest will see bitter
cold wind chills of -15°F to -25°F. As lower valley areas see
lows dropping into the single digit and teens, those water pipes
exposed outdoors could be at risk for bursting if not adequately
protected. There is still time to place that extra heat lamp in
livestock pens, and hustle outdoor pets that may be challenged
with these colder temperatures to a warmer spot indoors.
CRYSTAL BALLS AND TEA LEAVES: Not really! We emphatically use the
scientific method to assess-interpret-disseminate the best possible
ensemble based forecasts for our part of the world. And the
simulations within the framework of this guidance show this active
winter pattern restarting by mid-week after a brief, but very
cold early week hiatus. By mid-week the next shot winter conditions
returns for an encore performance with a potent cast of gusty
west-southwest higher elevation winds, periods of heavy Sierra
snowfall, and more wintry impacts that includes mountain travel
disruptions. Only low confidence projections can be made at this
time as ensemble guidance displays the usual uncertainties with
trajectory and strength. Don’t give up! Keep checking the
forecast! You don’t want to miss the show! -Amanda
&&
.AVIATION...
* As precipitation pushes deeper into the region, stronger winds
will dissipate quickly by late this afternoon and evening. FL100
winds will gradually decrease and shift more northerly with winds
speeds 20-30kts. Mountain wave turbulence and LLWS will respond in
suite, and dampen significantly across the Sierra and western NV.
Some turbulence will continue across far western NV through Sunday
for inbound aircraft departing and arriving into the RNO-CXP area.
* Sierra terminals will see IFR/LIFR conditions in SN/+SN continuing
through the remainder of the afternoon, and gradually becoming -SN
by 00-02Z. High guidance shows light snow cease by 03-04Z.
Mountain terminals will see at least 6.0”-8.0” of accumulated snow
on runways. Lower CIGS/VIS will cause widespread terrain
obscuration this evening and tonight. With the exception for the
risk overnight of partially dense freezing fog in the Martis and
Sierra valleys, these conditions will gradually improve through
Sunday morning.
* Far western NV terminals (RNO-CXP-MEV) will see periods of -SN/SN
and IFR/LIFR conditions through this afternoon, and then see
clearing after 02-04Z runway accumulations of up to 1.0”-2.0".
Remaining western NV terminals with see periods of IFR conditions
in -SN/SN with up to an inch of accumulated snow on runway
pavements.
* VFR conditions will return to western NV and most Sierra terminals
through Sunday. The slight risk (10-20%) through midnight for lake
effect snow (LES) across larger area lakes may add up to an
additional inch of snow across the South Lake Tahoe (TVL) area.
There also remains the risk of partially dense freezing fog, and
low status, causing brief periods of IFR/LIFR conditions across
parts of the Martis valley(TRK) and the Sierra valley(SVE) till 15-
16Z. -Amanda
&&
.AVALANCHE…
For this weekend`s storm in the higher Sierra elevations (7000+ feet
around Tahoe/Alpine counties, 8000+ feet in Mono County) and the
White Mountains...
TIMING/PEAK SNOWFALL RATES:
* For the Sierra, from 12 noon-6 PM today with peak rates of 1-
3"/hour.
* For the White Mountains, from 7-11 PM this evening with peak rates
up to 1.0-1.5"/hour.
SNOW-LIQUID RATIOS/SNOW AMOUNTS:
* Generally 14-16:1 this afternoon increasing 17-18:1 late this
afternoon and evening, resulting in drier and more powdery snow
compared to recent warmer snow events.
* For the Sierra, 10-20" snowfall with SWE between 1.0-1.50" around
the Lake Tahoe basin, decreasing to 8-16" snowfall with SWE 0.60-
1.0" for Alpine/Mono counties. Higher end scenarios (20-30%
chance) bring up to 2 feet near the crest west of Tahoe.
* For the White Mountains, the most likely snow amounts are 1-4",
with a 10-20% chance for at least 6" of drier-powdery snow.
WINDS:
* Southwest-west 50-65 mph with ridge gusts 100+ mph late this
afternoon gradually decreasing through the evening.
* Winds turn north and decrease late tonight, but remain breezy
through Sunday with ridge gusts near 50 mph for the Sierra and up
to 65 mph for the White Mountains. -Amanda
&&
.REV Watches/Warnings/Advisories...
NV... Winter Storm Warning until 10 PM PST this evening NVZ002.
Wind Advisory until 7 PM PST this evening NVZ001.
Wind Advisory until 3 PM PST this afternoon NVZ003.
Winter Weather Advisory until 10 PM PST this evening NVZ003.
Lake Wind Advisory until 7 PM PST this evening NVZ004.
CA...Winter Weather Advisory until 10 PM PST this evening CAZ071.
Winter Storm Warning until 10 PM PST this evening CAZ072.
Winter Storm Warning until 4 AM PST Sunday CAZ073.
&&
$$