National Weather Service Weather Forecast Office

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

000
FXUS65 KBYZ 150116
AFDBYZ

Area Forecast Discussion
National Weather Service Billings MT
716 PM MDT Sun Apr 14 2024

.UPDATE...
Quiet weather this evening but changes are coming soon. Our air
mass was too dry and stable for any diurnal convection today, but
note there is a t-storm a little north of Golden Valley County on
the north side of the Snowies. Satellite imagery shows an upper
low over the great basin, and upper air analysis indicates a 100kt
H3 jet lifting thru central UT. There are cooling tops in the
diffluent region over southeast ID into western WY. Mid level
lapse rates will remain steep as ascent increases from the south,
so expect shower coverage to increase over our west thru the
evening and overnight. Forecast has a good handle on this. Have
made minor tweaks to early evening pops and winds based on current
trends.

Billings airport tied its daily record with a high of 80F today,
the first 80 degree day of 2024. No other records were set or
tied.

JKL

&&

.DISCUSSION...
Late afternoon through Monday night...

Water vapor imagery was showing a flat ridge over southern
Montana and northern Wyoming, with a deep upper low over central
California. The upper low will become the weather player Monday
and Monday night, with a relatively calm period tonight.

For tonight, the upper ridge axis will slide into southeast
Montana, while the upper low progresses into southwest Utah. Upper
divergence will slide into our western zones late this afternoon
and tonight for ascent. Low levels were dry, with dewpoints in the
20s and 30s, and forcing this afternoon and evening is not
progged to be terribly strong, so will keep the chance of showers
low (around 20%). Cape values were low but some mid level
instability was present. SPC paints areas to the west and north
with the best chance of seeing lightning, so left it out for now,
but would not be surprise to see a strike or two over western
zones this evening. Forcing increase overnight over the western
zones, so raised the chance of showers after midnight to 30-40%.

Showers and clouds will linger over the western half of the area
Monday morning, before the stronger forcing moves in for Monday
afternoon with the upper low pulling into northern Colorado. A
surface low will be strengthening in northeast Colorado, which
will drive north to northwest winds over the western half of the
area. All of this will provide a cooler day on Monday for western
and central zones. Showers, with a few thundestorms, are expected
to develop with upslope flow developing. The thunderstorms over
the western half of the area are not expected to be too strong,
but with cape values around 600j/kg and persistent ascent, can not
rule out some gusty winds and small hail with a few storms.

The stronger storms on Monday will reside over the southeast. A
surface trough from Powder River to Custer county Monday afternoon
should serve as the focal point for development. Capes around
800j/kg will lead to a few stronger cells developing. Precipitable
water values climb to around 0.90 inches, which will lead to
locally heavy rain with the storms. Persistent surface convergence
Monday afternoon and night should keep showers and thunderstorms
developing through the night over the southeast zones, and
therefore the chance of rain is 60-70%. In fact, NBM was placing a
70% chance of picking up at least 0.25 inches of water over the
southeast zones Monday night, with Red Lodge at a 30% chance and
Billings at 20%.

Snow levels fall to around 9 thousand feet Monday night, so some
of the higher tops will get 2-4 inches of snowfall, but the bigger
event for the mountains (and foothills for that matter) for
snowfall will hold off until Tuesday night (see extended
discussion below). TWH

Tuesday through Sunday...

Tuesday... A dynamic weather pattern is finally being agreed upon
by model ensembles. With the EC and GFS ensembles placing a deep
low over the Central Plains, leaving a brief period of split flow
ahead of an approaching trof from Canada. This trof and associated
low pressure center will progress through southern Alberta and
southern Saskatchewan into the end of the week. As this low
pushes along the border, cold air will rush in along with ample
moisture, bringing wetter conditions across much of the forecast
area through Thursday.

Currently, models depict a strong jet at 300mb Tuesday night
through Wednesday, shuttling lots of PNW moisture into the
Northern Rockies. Latest forecasted QPF amounts range from a few
hundredths to over an inch for this event. The highest QPF totals
exist in the mountains and surrounding foothills. Almost all of
the forecasted precipitation is expected to fall in the Tuesday
night to Thursday morning period. Precipitation in the foothills
will likely begin as a rain/snow mix before turning over to all
snow overnight Tuesday. Current snow levels Tuesday night into
Thursday morning are only a few thousand feet, along with fairly
wet snow ratios, 15-10:1. While 700mb flow is not very strong
during this time frame, favorable lapse rates of 7-9C/km will
provide ample forcing and increased snowfall rates. Low level
flow direction will be WNW to NNE, which will be favorable for
some upslope into the mountains and foothills. As a result, Winter
Storm Watches have been issued for the Absaroka/Beartooths mtns,
as well as the Big Horn and Pryor mtns, with 10-20 inches of snow
possible. There is also a Winter Storm Watch for the Absaroka
Beartooth Foothills, including Red Lodge and Big Timber, for 5-10
inches of snow. The watches for the mountains will begin at 6pm
MDT Tuesday and go until 6pm MDT Thursday. The watches for the
foothills will begin at 9pm MDT Tuesday and last until 12pm MDT
Thursday.

For lower elevations, chances for rain are more likely, with
daytime highs in the 40s on Wednesday and Thursday. Current storm
total QPF amounts in the forecast have up to 0.25" for Billings
and 0.50" for Livingston and Sheridan. Very little moisture is
anticipated for locations north and east of Billings.

Relevant snowfall and precipitation probabilities can be found at
weather.gov/byz

As the low and trof depart to the northern Midwest late Thursday,
zonal flow will begin to settle in, despite the fact that
lingering energy with general cyclonic flow persists in the upper
levels. Probabilities for precipitation will still be present
Friday and Saturday, ranging from 10-50%, with highest chances in
the mountains. With increasing heights and a ridge building in
from the PNW, high temperatures will climb back into the mid 40s
to low 50s Friday and Saturday. Temperatures will continue
climbing with the ridging on Sunday, with highs back into the
60s.

A final note, there is a potential period of breezier conditions
on Wednesday, with gusts in the 20-40s mph range. It is worth
noting though, that the latest NBM is amplifying winds a bit more
than we find to be likely.

There is still some uncertainty with this event, as a result, stay
tuned to the forecast for any updates and products this week.

Matos

&&

.AVIATION...

VFR conditions will prevail across the area into Monday morning.
Isolated to scattered showers are expected W of KBIL, potentially
impacting KLVM (30% or less chance). Clouds will increase through
the night, with the chance of showers increasing toward Monday
morning. Showers with isolated thunderstorms will increase over
the area Monday afternoon, with strong storms possible in far SE
MT. Expect conditions to deteriorate in precipitation Mon.
afternoon to MVFR/IFR or less. Localized to areas of mountain
obscuration tonight will become more widespread during Monday. Arthur

&&

.PRELIMINARY POINT TEMP/POPS...

    Mon     Tue     Wed     Thu     Fri     Sat     Sun
-----------------------------------------------------------
BIL 048/071 046/063 035/044 027/047 026/045 027/051 031/066
    25/T    31/N    66/S    22/S    11/B    11/B    11/B
LVM 046/064 038/059 030/040 022/043 021/042 022/051 031/062
    37/T    32/R    86/S    22/S    11/B    11/B    12/R
HDN 044/074 047/065 035/046 025/048 025/047 025/054 029/067
    14/T    41/B    56/S    22/S    11/B    11/B    11/B
MLS 045/076 049/063 035/045 027/045 023/043 025/049 030/063
    02/W    42/R    12/S    11/N    00/B    01/B    01/B
4BQ 046/077 047/060 035/044 027/045 025/044 025/048 030/063
    03/T    63/R    13/S    11/N    01/B    01/B    11/U
BHK 043/075 043/059 032/044 024/042 020/041 022/046 026/058
    02/W    75/R    12/S    11/N    01/B    01/B    01/B
SHR 042/072 044/060 031/040 021/042 021/043 020/049 026/062
    04/T    61/N    68/S    32/S    22/S    11/B    11/B

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...Winter Storm Watch in effect from Tuesday evening through
      Thursday morning FOR ZONES 56-66.
     Winter Storm Watch in effect from Tuesday evening through
      Thursday afternoon FOR ZONES 67-171.
WY...Winter Storm Watch in effect from Tuesday evening through
      Thursday afternoon FOR ZONE 198.

&&

$$
weather.gov/billings