947
FXUS65 KBYZ 091911
AFDBYZ

Area Forecast Discussion
National Weather Service Billings MT
111 PM MDT Thu May 9 2024

.DISCUSSION...
Through Friday Night...

Satellite imagery shows central Rockies low continuing to sag
southward (and cut off) as heights build across the northern
Rockies. We remain under easterly flow aloft with plenty of low-
mid level moisture to produce more showers today especially in
upslope areas. There is a 300mb easterly jet over northern WY, a
position that leaves us in the RRQ for weak ascent this afternoon
(though most forcing is at lower levels). Instability extends from
the SFC to roughly 600-650mb, or about -10C...shallow and not
cold enough for much if any lightning risk late this afternoon &
evening. BLX radar currently scattered showers developing,
including over our east where convective temps (lower 60s) have
been reached).

Overall forecast is in good shape over the next 9-12 hours, with
scattered to numerous showers and some additional upslope snow for
the high terrain. Have already cancelled the winter highlights,
but locally heavy snow along the northeast aspects is expected
above 7kft over the next several hours. Shower activity will
persist beyond sunset but generally speaking it will taper off
from north to south thru the night, as aforementioned ridging
becomes more dominant. Light downslope gradients remain in place.
Although you would expect a healthy risk of fog tonight, the
westerly winds keep models from showing much fog potential.
However, with boundary layer moisture quite elevated and more
showers yet to come, localized valley fog is still a good bet late
tonight into early Friday as skies gradually clear. Greatest
potential for fog is from 06-15z.

Friday will be dry & warmer (finally) as upper low moves out of
our picture and the easterly flow aloft becomes a drier NW flow.
Look for highs into the mid-upper 60s most places tomorrow.

JKL

Saturday through Thursday...

Upper level ridging over the region will bring warmer and mainly
dry conditions through the weekend. Weak disturbances in the flow
will cause the ridge to flatten, bringing a 20-30% chance for
showers and isolated thunderstorms Sunday afternoon into evening.
Then, Monday afternoon into Tuesday, a shortwave will move into
the region, bringing an increased chance (30-50%) for showers and
(15-30% chance) thunderstorms. Cyclonic flow will extend the
chance for precipitation into Thursday.

High temperatures will be in the mid to upper 70s through Monday.
Then, after the shortwave drops in, temps are expected to dip
into the 60s to low 70s for Tuesday through Thursday. With the
warmer weekend temps, much of the wet snow that has fallen at
elevations below 8000 ft in the last couple days is expected to
melt out. As a result, expect to see rises along streams emerging
from the foothills. At this time, any flooding risk is unlikely.
Archer

&&

.AVIATION...

Occasional showers and mountain snowfall will continue to impact
the area thru the evening, w/ the greatest shower coverage west
and south of KMLS, and especially near the mountains and
foothills. Showers will taper off late tonight. MVFR to IFR can be
expected with the showers (poorest flying conditions along the
foothills). Mountains will be frequently obscured due to snow,
especially the northeast aspects. Drying will finally arrive late
tonight into Friday, but localized visibility reductions due to
fog are possible from roughly 06-15z (probabilities of fog
impacting a TAF site are low at this time). Look for widespread
VFR tomorrow from mid morning through the afternoon as high
pressure aloft builds over the region. JKL

&&

.PRELIMINARY POINT TEMP/POPS...

    Fri     Sat     Sun     Mon     Tue     Wed     Thu
-----------------------------------------------------------
BIL 042/067 045/076 047/076 050/076 049/067 045/067 046/074
    40/U    00/B    02/W    13/T    45/T    34/T    23/W
LVM 035/064 038/071 043/075 046/072 044/066 042/066 043/071
    20/U    00/U    01/U    13/T    35/T    34/T    23/W
HDN 039/068 039/076 044/077 046/078 047/068 044/068 044/075
    50/U    00/U    12/T    14/T    55/T    34/W    23/T
MLS 042/068 043/076 047/076 049/078 049/067 043/066 045/072
    20/U    00/B    12/W    13/T    44/T    23/W    22/W
4BQ 043/066 042/075 047/075 047/078 048/066 044/065 044/072
    30/U    00/U    02/W    12/T    54/T    33/W    22/W
BHK 039/068 041/074 045/075 046/077 046/066 040/065 040/070
    20/U    00/B    02/W    13/T    44/T    23/W    22/W
SHR 040/065 037/073 043/074 044/075 044/065 041/064 041/072
    60/B    00/U    03/T    14/T    66/T    44/T    22/T

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...None.
WY...None.

&&

$$
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