Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/22/21
Area Forecast Discussion
National Weather Service Dodge City KS
1049 PM CDT Sun Mar 21 2021
...Updated Aviation...
.SHORT TERM...(This evening through Monday Night)
Issued at 322 PM CDT Sun Mar 21 2021
Upper air analysis showed a large positive tilted trough extending
from the northern Plains into the Great Basin. The northern part
of this trough was shearing off to the east while the southern
part was digging southeast with a closed low developing over Utah.
Elsewhere, a cold front had moved into southwest Kansas and
currently extends from just west of a Hays to Liberal line.
The front will move a little more to the southeast this evening
before becoming stationary. The upper low over Utah will track
from Utah across northern New Mexico tonight and Monday. Ahead of
this system, upper level flow will become increasingly difluent
with increasing upward vertical motion over the central High
Plains tonight. Precipitation chances will increase tonight.
Latest model guidance doesn`t develop much until mid/late evening
with precipitation increasing in areal coverage later tonight into
Monday. Instability is weak to non-existent this afternoon and
the models only show a modest increase this evening so
thunderstorm coverage may be pretty limited. Areas of rain will
initially develop in areas behind the front over western/northern
sections of the forecast area and then spread east late tonight.
On Monday through Monday night the upper system tracks takes on a
more neutral to negative tilt as it moves across the northern
Texas Panhandle and northwest Oklahoma into eastern Kansas. The
bulk of the rain across western Kansas will occur on Monday before
ending from west to east Monday night as the upper system pulls
away. There could be a little light snow mixing in over far
western sections Monday evening before the precipitation ends but
no accumulation is expected. Total precipitation amounts should
range from around a half inch over far western sections of the
area to around 1.5 inches across portions of central and south
central Kansas.
.LONG TERM...(Tuesday through Sunday)
Issued at 322 PM CDT Sun Mar 21 2021
Another upper level system will dig into Arizona by Tuesday night
and move out through the southern Plains through Wednesday night
and Thursday. There continues to be a little more uncertainty as
to how far north any precipitation from this system will get into
Kansas but at this time, the most likely area will be across the
southern half of the forecast area. There could also be more of a
rain/snow mix with this system depending on the amount of cold air
this system has.
The central Plains should dry out and warm up by next weekend as the
upper level flow becomes more zonal and low level downslope flow
develops over the central High Plains.
&&
.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1049 PM CDT Sun Mar 21 2021
High confidence that poor flying conditions will prevail through
the balance of this TAF period. VFR seen presently at the airports
will continue for about the first 6 hours of this TAF period, with
widespread IFR/LIFR stratus expanding across the terminals around
12z Mon. Poor flying weather is expected daylight Monday, with
continued IFR/LIFR stratus, and reduced visibility in BR/-SHRA/RA.
Rain showers will be numerous Monday, and some of the rain will
be heavy at times, reducing visibility to MVFR, and IFR at times.
The best chance of thunderstorms is near/SE of DDC around 21z Mon-
00z Tue. Followed the HRRR solutions with its depiction of a
strong deformation band producing widespread rain and IFR/LIFR
flight category 00-06z Tue. NE winds will prevail for most of this
TAF cycle, then trend NWly and increase in strength after 00z
Tue. NW wind gusts of 30-35 kts are expected toward the end of
this TAF period.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 42 49 34 55 / 70 90 40 10
GCK 38 44 31 54 / 80 90 40 0
EHA 37 43 29 55 / 70 80 20 0
LBL 40 49 30 56 / 70 80 30 0
HYS 40 48 35 52 / 80 100 70 20
P28 46 56 40 57 / 70 90 60 10
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Gerard
LONG TERM...Gerard
AVIATION...Turner
Area Forecast Discussion
National Weather Service Duluth MN
959 PM CDT Sun Mar 21 2021
.DISCUSSION...(This evening through Saturday)
Issued at 344 PM CDT Sun Mar 21 2021
Summary: chances of light rain move in for this evening and
overnight, with drier conditions during the day Monday. A more
prolonged period of precipitation moves in for Monday night,
lingering through Wednesday. A mix of rain, snow, and possibly some
freezing rain will be possible. More chances of precipitation are
possible next weekend.
Gusty southerly winds will continue this afternoon before a weak
cold front passes through the region this evening and overnight.
Current surface analysis shows the front situated over far northwest
Minnesota, moving east towards the region. Chances of rain showers
will be possible with this front. However, accumulations are
expected to be low due to the amount of dry air the rain has to
overcome. Winds will shift more westerly overnight once the front
passes through. Total rainfall will range between 0.05" to 0.20",
highest amounts expected to fall over the Minnesota Arrowhead.
High pressure will nose into the Northland for Monday, resulting in
mostly sunny skies, especially over northeast Minnesota.
Relative humidities should become dry, but winds will be light and
variable, so hazardous fire weather conditions aren`t anticipated.
Attention then turns to the prolonged period of precipitation for
Monday night through Wednesday. The culprit is a nearly vertically-
stacked area of low pressure moving northward from the south. A
longwave upper-level trough will support surface cyclogenesis over
the TX Panhandle region. As the trough pivots more northerly, the
surface low will follow suit towards the Northland. A leading band
of frontogenetical forcing ahead of the surface low will bring
chances of rain over northwest Wisconsin Monday night. Precipitation
will become more widespread as the enhanced isentropic upglide with
the surface low lifts northward. The surface low will lift into the
region on Wednesday, and exit late Wednesday. Precip types are a bit
uncertain, thanks to a very cool low-level thermodynamic
environment. Both the NAM and GFS model soundings are indicating
sufficient saturation in the ice bearing layer aloft, but
temperatures above freezing in the boundary layer will likely result
in either rain or non- accumulating snow. A warm layer aloft, most
likely over the North Shore, could result in freezing rain if the
surface temperatures can cool by a degree or two. For now, we have
higher confidence in a rain/snow mix, with little freezing rain.
This system does look to be rather wet, with rainfall amounts of
over 1 inch possible. Accumulating snow is most likely over
northeast Minnesota where the coldest air will be situated. We could
see accumulations of at least a few inches along and north of the
Iron Range, but this may change!
Once the surface low shifts off to the northeast, dry conditions
should return to the Northland for Thursday and Friday. The ECMWF
model is hinting at a larger system that could skim the eastern
portions of the region, while the GFS and GEM models keep the region
dry. There could be more chances of precipitation for next weekend,
but uncertainty remains on the spatial coverage and timing due to
differences among the global models.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 628 PM CDT Sun Mar 21 2021
A cold front and upper trough were moving through the Northland
this evening with showers near and behind the cold front and well
ahead over northern Wisconsin and far eastern Minnesota. Gusty
winds continued ahead of the front but those are expected to
diminish over the next 1 to 3 hours. Ceilings are expected to
lower to low VFR or MVFR for most areas with the MVFR ceilings
most likely along and behind the front. The showers may reduce the
visibility to MVFR and possibly briefly to IFR. Any IFR visibility
restrictions should be short-lived, around an hour or less. As the
front passes through, winds will veer to west then northwest but
they are expected to remain at or below 10 knots except for a
brief increase as the front passes. There is some indication low
MVFR ceilings could form later tonight, especially over far
northern Minnesota. The RAP was indicating some low level moisture
but confidence is not very high on it forming or how widespread
it will be. We added a mention in some of the TAFs but mostly left
it as scattered for now. VFR conditions are expected for much of
the day Monday.
&&
.MARINE...
Issued at 959 PM CDT Sun Mar 21 2021
A cold front will move across the lake tonight, shifting winds to
the west and bringing light rain. Localized gusts around 25 knots
will be possible early this evening before winds ease to 5 to 10
knots tonight. Waves are also expected to subside to 2 feet or less.
The exception will be along the North Shore from Two Harbors to
Grand Portage, where waves will remain around 1 to 3 feet tonight.
Conditions on Monday are expected to be quiet with mostly sunny
skies and west-southwest winds of 5 to 10 knots.
Low pressure approaches the area on Tuesday, which will bring rain
and increased winds. Winds are expected to veer to the northeast on
Tuesday and strengthen to 15 to 20 knots. Wind gusts on Tuesday may
reach up to 30 knots. At this time, the pressure gradient associated
with this system appears too weak to produce widespread gale-force
winds. Waves may build to 4 to 7 feet on Tuesday, except in
Chequamegon Bay where waves will be around 1-3 feet in the ice free
areas. Small Craft Advisories will likely be needed for Tuesday.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 38 49 33 41 / 60 0 70 90
INL 29 45 24 47 / 60 0 10 30
BRD 33 52 35 45 / 60 0 60 90
HYR 40 55 38 50 / 50 0 100 90
ASX 43 54 34 43 / 50 0 90 90
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
LS...None.
&&
$$
DISCUSSION...JTS
AVIATION...Melde
MARINE...Unruh/Melde
Area Forecast Discussion
National Weather Service Marquette MI
631 PM EDT Sun Mar 21 2021
.SHORT TERM...(This evening through Monday)
Issued at 408 PM EDT SUN MAR 21 2021
WV imagery and RAP analysis indicated a mid/upper level trough over
the western CONUS and a downstream ridge from the Lower Mississippi
Valley into the eastern Great Lakes. A shortwave trough extended
from southern Manitoba into western North Dakota. At the surface,
strong southerly flow prevailed ahead of a trough into northwest MN.
Vis/IR loops showed mid and high clouds increasing with the WAA
pattern ahead of the trough. Any pcpn lagged well to the west near
of just behind the trough, over eastern ND into nw MN.
Tonight, expect clouds to thicken this evening with 800-600 mb fgen
supporting rain over MN that will not spread into western Upper
Michigan until late this evening as the dry antecedent airmass
slows its progress into the area. As the supporting dynamics
weaken and lift north of the area overnight, the rain should
diminish with only lower end POPs into the central and east late
tonight or early Mon. Mild conditions will continue with min temps
only in the lower 40s. Gusty south winds will also prevail this
evening, especially near the Great Lakes.
Monday, with the front/trough sliding east of the area and weakening
any lingering light rain will diminish early. Otherwise, drier air
with a weak ridge building into the area will bring clearing into
the afternoon. Temps will again climb well above normal with highs
from around 50 north to the upper 50s south.
.LONG TERM...(Monday night through Sunday)
Issued at 344 PM EDT SUN MAR 21 2021
The longterm period looks to continue with above normal temperatures
through the first half of this week. During the middle of the week
and through the weekend, models suggest temperatures fall back
closer to normal, but perhaps still slightly abv, to round out the
month of March.
Broad ridging over the ern CONUS will slowly slide to the east as a
trof follows behind. By Monday, this trof takes on more of a split-
flow pattern with the northern stream bringing a weak cold front
across the UP with some light pcpn and a southern stream wave gets
cut off and drifts east through the 4 corners and into TX. Tuesday
night into Wednesday, this wave lifts northward, progged to pass
through western to central Upper Michigan by Wednesday afternoon,
while bringing a pcpn shield of rain Tuesday through early Thursday
morning. Split flow and broad troffing with a series of waves are
progged to continue across much of the central and wern CONUS behind
this wave into the weekend. Models suggest another wave shifting
from the Pac NW through the Rockies and into the GL region on
Friday, but this one looks to stay a bit to the south through Lower
Michigan. Another wave follows in a similar path, before lifting
through the GL Sunday, bringing another chance of pcpn across mostly
the eastern half of Upper Michigan and potentially missing us all
together...still some time to shake out the details.
As the warm front pushes across the UP Monday night, moisture looks
to be marginal initially, as well as the WAA but models that show
pcpn are suggesting decent isentropic ascent that will bring a
chance of light rain. Behind this warm front, there looks to be a
break in the pcpn as dry air mixes into the profile, cutting off
deeper moisture as well. NCEP models are trending towards little to
no break in the pcpn, thus a bit more qpf than their EC/GEM
counterparts. More widespread forcing for ascent and moisture
profiles arrive later in evening on Tuesday, as a shield of pcpn
will shift over the UP, bringing widespread rain with amounts most
likely between 0.3 and 0.7 inches across the UP for the event. I did
trend the fcst a little drier given the wet bias of the NCEP models
and antecedent PWATs near their 10th pctl. However, despite GFS
being an outlier, its solns have remained consistent. There is still
a chance for amts to approach upwards of 1.0 inch, with the better
chance of this remaining across wern UP or across the south-central.
Models show the strongest forcing, especially in the GFS, remaining
off to the west over Lake Superior and the Arrowhead of MN where the
better fgen forcing will be. This system looks to slowly shift over
the UP through Wednesday night, before shifting away into Thursday
morning. Some model differences in how this event ends, with the GFS
coming down from its outrageous -20C from yesterdays run and NAM/GEM
850mb temps have come down some. So while I took out any mention of
snow through Wednesday aftn given the sounding profiles, there is a
chance some snow starts to mix in as the event winds down Wednesday
evening, mainly across the west with little to no accum expected at
this point. With Upper Michigan in a shortterm drought, I am unsure
how much of this pcpn will be able to help. There is still quite a
bit of frost in some locations, and only a couple inches of thaw in
the snow free areas. Possible that locations lose quit a bit of pcpn
to runoff vs any infiltration, but we will take what we can get at
this point. Aside from localized ponding of water in low-lying
areas, or potentially some basements, not expecting any river
flooding from this pcpn.
Models continue their differences behind this exiting low with a
second southern stream shortwave ejecting to the NE from ern TX
Thursday night, lifting through the Central Plains and into the Ohio
River Valley. This low has trended slightly more north with the
latest run and outside of ern UP getting a glancing blow, still
expected to remain to the south. Heading into the weekend, a
building ridge moves onto the West Coast as another wave rounds the
trof as it shifts east. Models have diverging solns at this point,
but ensem means show a developing sfc low somewhere in the Ohio River
Valley/Lower Great Lakes region. Could bring some pcpn, or even some
snow across ern Upper Michigan, or it could remain to the south all
together, still a week out to sort out the details.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 630 PM EDT SUN MAR 21 2021
TAFs will continue to be VFR into this evening but then will lower
to MVFR at IWD and CMX later tonight with the approach of a
trough/cold front from northwest MN. Drier air moving in Mon behind
the front should lift cigs to VFR. There will be LLWS at KSAW into
tonight as a LLJ remains over the area. SSW winds will also be
gusty, around 25 knots at CMX and 30 knots at IWD and SAW.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 408 PM EDT SUN MAR 21 2021
Over the east half, southerly winds are expected to remain near 30
knots tonight. Winds on the west half will remain lighter in the 20-
25 kt range through tonight. Lighter winds are expected Monday as a
low pressure trough moves over the area. By Tuesday, a low pressure
system over the Mississippi Valley will result in winds veering
around to NE and increasing to 20-30 kts, greatest over the western
third of the lake. NE winds may even reach low-end gale force gusts
over the west end late Tuesday into Wednesday morning before backing
N-NW and diminishing to 20-25 knots late Wednesday night into
Thursday as the low lifts northward across the lake and weakens.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...JLB
LONG TERM...JAW
AVIATION...07
MARINE...JLB
Area Forecast Discussion
National Weather Service Pueblo CO
602 PM MDT Sun Mar 21 2021
.UPDATE...
Issued at 600 PM MDT Sun Mar 21 2021
Updated forecast for current temps/winds. Also decreased pops
early this evening over far eastern plains as precip will not get
out that way till a few more hours or so. /Hodanish
&&
.SHORT TERM...(This evening through Monday)
Issued at 320 PM MDT Sun Mar 21 2021
A few showers are currently showing up on radar over El Paso and
surrounding counties, and a few observations have been reporting
snow showers. Winds have also been consistently gusty today, though
the wind highlight expired earlier this morning, gusts to around 30
mph have been pretty consistent across the area today, with some
easterly gusts making it through La Veta Pass into Alamosa.
The passing low has sent a front south across the plains, with the
resulting gusty upslope aiding in the onset of precipitation. As the
low tracks southeast, precipitation will begin to spread over El
Paso and Teller Counties before encompassing most of the I-25
corridor, Sangre de Cristos and the Wet Mountains as well as the
Continental Divide and eastern San Juans. Impact wise, through the
initial hours of this evening most of the precipitation is expected
to fall as rain. High temperatures today have been on the warm side,
with most, if not all, of the plains sitting above freezing. Snow is
expected to occur over the mountains, but the lower elevations are
not expected to switch to snow until after about 9pm. El Paso will
likely be the first location to switch over, before the rain/snow
line moves south throughout the night. Given the lift associated
with this system, and the potential for upsloping on the north side
of the Palmer Divide, snow rates later tonight could top off at 2-3
inches per hour, although the heavy snow is not expected to last
very long, which is what mostly warranted the highlight for those
areas. Some areas around the Palmer Divide, as well as the Pikes
Peak region and Teller County, could be seeing upwards of 8-10
inches by late Monday night, while the Colorado Springs area could
see around 5 inches. The system is progressing fairly quickly, and
given the high temperatures today and yesterday, the potential
impacts will be largely dependent on location and temperatures. The
Palmer Divide and high elevations will be seeing more snow, and the
Divide specifically will be seeing brief periods of heavier snow, so
some accumulation is expected by the end of the event. Other areas
further south will mostly just be seeing accumulation on grassy
areas, as roads will be too warm and any falling snow is expected to
melt pretty quickly. Wet, slushy roads could be possible, however,
and caution while driving is encouraged.
The southern I-25 corridor will also potentially be seeing brief
heavier snow, given the upslope component towards the Raton Mesa,
with the last several runs of the HRRR and NAM Nest potentially
putting some pockets of more convective-looking snow over parts of
Las Animas County, which warranted it being added into the existing
Advisory for that area, in case road conditions become hazardous.
Those areas are expected to pick up 4-6 inches of snow on average,
with the adjacent mountains picking up about twice that amount.
However, Pueblo County was still left out of the highlights, as none
of the high-res models had us picking up more snow than previously
forecasted, and with the late rain-snow switch and warm high
temperatures, impacts are expected to be minimal.
Tomorrow, as the cyclone and trough dig east, precipitation will
follow, leaving some lingering snow over the central and southeast
mountains while the more widespread precipitation pushes east.
Models have been in disagreement over the mode of precipitation,
with the latest HRR predicting mostly rain, while other models are
calling for more of a rain-snow mix, which seems more likely given
the expected high temperatures for tomorrow. Either way, roads are
still expected to be too warm for anything to stick there, so
impacts to travel are expected to be minimal there as well.
.LONG TERM...(Monday night through Sunday)
Issued at 320 PM MDT Sun Mar 21 2021
A few flurries or snow showers will linger over the mountains and
far ern plains Mon night as upper low departs, with activity ending
by early Tue morning. Break in precip will be brief, as next upper
wave drops south through the Great Basin Tue, before swinging slowly
eastward through the srn Rockies Tue night and Wed. Expect snow
showers to redevelop over the mountains ahead of the wave by Tue
afternoon, then fairly widespread snow becomes likely over the
mts/valleys and I-25 corridor Tue night into Wed.
Track of this system will be farther south than Sun/Mon low,
suggesting heaviest precip will fall over the ern San Juans, srn
Sangres and srn I-25 corridor. Accumulations could be significant (1-
2 feet at the highest elevations) in these areas by Wed afternoon,
and we`ll likely need winter wx highlights at some point in the next
few forecast cycles. Ahead of the system, some warming expected Tue
afternoon, though maxes will still fall short of seasonal averages.
Precip diminishes over the ern mts and plains late Wed, while
farther west, mountains along the Continental Divide see renewed
snow shower chances as last upper wave rotates toward the area.
21/12z deterministic models have backed off considerably on precip
with this wave, as energy splits and nrn stream portion lifts
quickly into the high plains. Expect mainly mt snow showers both
Thu/Fri as weakly unstable air mass persists across the region,
before ridging returns and dry/warmer weather develop next weekend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 320 PM MDT Sun Mar 21 2021
VFR conditions expected the rest of the day today at KALS, KCOS and
KPUB, although gusty winds are expected to last. Overnight tonight,
precipitation is expected to set in at all three terminals.
KALS...Gusty west-southwest wind to about 30 mph will persist the
rest of the afternoon, turning more easterly after about 00-03Z and
remaining gusty. Showers will drift near the terminal around this
time as well from the east, although it is very unlikely anything
will directly impact the terminal.
KCOS...Occasionally gusty east-northeast winds will persist through
most of the night, turning more northerly after 00Z. Rain showers
have developed near the terminal, and are expected to turn to snow
by 00Z, leading to potential MVFR-IFR conditions that should last
well into tomorrow.
KPUB...Gusty northeast winds will last into the night, with rain
showers setting in near the terminal after 00Z. The precipitation is
expected to begin as rain over the terminal around 03Z and
transition to snow about 2 hours later, bringing conditions down to
MVFR-IFR overnight, which will last through the end of the forecast
period.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until noon MDT Monday for COZ058>063-
072>078.
Winter Storm Warning until noon MDT Monday for COZ079>082-084.
Winter Weather Advisory until noon MDT Monday for COZ083-085-087-
088.
&&
$$
UPDATE...HODANISH
SHORT TERM...GARBEROGLIO
LONG TERM...PETERSEN
AVIATION...GARBEROGLIO
Area Forecast Discussion
National Weather Service Reno NV
241 PM PDT Sun Mar 21 2021
.SYNOPSIS...
Winds increase Monday afternoon through Tuesday as a cold front
moves through the region. There will be a chance for snow showers
Monday night with some snow-covered roads possible into commute
time Tuesday morning, especially in western Nevada and extreme
northeast California. Another front is expected Thursday for a
drop in temperatures, breezy winds, and a chance for showers.
&&
.SHORT TERM...
After quiet weather into early Monday morning (just a mid and high
level cloud increase tonight), the focus turns to a disturbance
currently near the British Columbia coast. That wave will push
into the interior Pacific Northwest and northern Rockies by Monday
afternoon and evening, with an "inside slider" dropping down the
backside of the trough into western NV Monday night. Ahead of
the slider, the incoming trough will push a lead frontal boundary
into northern NV/CA tomorrow. This could bring a few rain and snow
showers to areas north of Susanville and Lovelock with a few
sprinkles/flurries possibly reaching down to Hwy 50 east of Fallon.
Any showers look quite light and no road travel impacts are expected
through Monday afternoon.
Turning to the "inside slider", it looks much like a true inside
slider as it is expected to drop down east of the Sierra crest rather
than the hybrid situation we often get where the disturbance drops
through northwest CA and into the Sierra. With the true slider track,
areas across western/west-central NV are expected to receive more
rain and snow than the Sierra; however, the devil is in the details
as slight shifts east or west can make a big difference for who
receives widespread precipitation and who gets little or no
precipitation.
As far as travel impacts, complicating the issue further will be
the precipitation rates and road surface temperatures as precipitation
will be blasting through in a couple hours or less Monday night.
While we would expect a rapid transition from a mix of rain and
snow to all snow with the slider`s precipitation bands, areas below
about 4500 feet may wind up with just wet roads if snowfall rates
remain light. As is typical with sliders, there will likely be narrow
bands of heavier snowfall rates embedded in the larger precipitation
band; however, embedded narrow bands are not able to be forecast
confidently at this point. What does all this mean? Be prepared for
a light snowfall in western/west-central NV and extreme eastern CA
(especially Mono County) Monday night and be prepared for a slushy,
slow commute Tuesday morning, especially above lower valley floors.
Tuesday looks brisk with breezy northerly winds and well below average
temperatures. Any road impacts due to snow will likely end by mid-
morning as the sun gets to work on paved areas (even with cloud cover).
Note that strong easterly winds are expected for the Sierra crest
westward (gusts to 100 mph or so possible exposed areas) by Tuesday
afternoon and especially Tuesday night as high pressure builds into
the western Great Basin. Winds on Lake Tahoe will also increase
substantially with rough waters likely by late morning or early
afternoon. -Snyder
.LONG TERM...(Wednesday Onward)...
* Main trend here is the inland trough for Thursday is trending more
eastward which lessens the snow and wind impact potentials for W
Nevada and the Sierra. Light rain or snow showers are now looking
confined to areas east of Hwy 95 into central Nevada coupled with
the best forcing, with some minor upslope showers possible for the
E Sierra. North/northeast winds not looking too interesting either
with ECMWF EPS means showing 20-30 mph Thursday in most areas, and
only 10% of members above 40 mph in wind prone spots.
* Otherwise the long term is focused mainly on temperature trends.
Wednesday will be an interesting day in between systems. Cold
air behind the Tuesday wave isn`t too robust; however, NBM
guidance showing mainly N/NE flow Wednesday with a very late day
switch to downsloping westerlies. As such, for example, max
temps range from 49 to 66 in the 10th-90th NBM percentiles for
RNO and 41-55 at MMH airport. So some good boom-bust potential
on Wednesday`s temps.
* For Thursday the dip in temps is not as pronounced now with a more
easterly trajectory of that trough. Into next weekend the NBM
continues to show a big spread in max/min temps, depending on
where the upper ridge axis sets up. Therefore, confidence in
temperature forecast is below normal. Could either stay seasonably
cool or could get quite warm relative to normal into the following
week.
* In any scenario am not seeing meaningful or cohesive storm
signals in the GFS or ECMWF EPS guidance. Some low-end storm
noise here and there into early April but it`s a pretty good bet
for below normal precip next 1-2 weeks.
-Chris
&&
.AVIATION...
Shortwave ridge aloft resulting in light winds and plentiful sunshine
today with clear skies extending into this evening. Sharp inland-
trajectory trough drops into the Great Basin Monday night. In the
broad ascent zone ahead of this wave, mid and high level clouds
increase late tonight through tomorrow. Breezy northwest winds will
also kick up Monday with gusts 20-30 kts likely at most airfields
in the Sierra and W Nevada. Some pockets of MVFR blowing dust
possible between HTH-NFL-WMC.
Depending on westward extent of the trough axis, a "slider" band of
snow showers is possible across W Nevada Monday night. This could
put down a fast 30-60 minute period of IFR snow from RNO/CXP/MEV
eastward to NFL and into central Nevada. Whether or not this sticks
to runways is TBD - depending on how quick we cool off at night and
residual heat from previous day. Based on HRRR and NAM high-def
simulations there`s roughly a 70% chance of a dusting, 20% chance of
an inch or so. Early Tuesday morning outbound traffic at RNO and
other sites could be affected by need for deicing, snow clearance.
-Chris
&&
.REV Watches/Warnings/Advisories...
NV...None.
CA...None.
&&
$$
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visit...
http://weather.gov/saltlakecity/general/afd_faqs.php