663
FXUS65 KBYZ 050202
AFDBYZ

Area Forecast Discussion...Updated
National Weather Service Billings MT
802 PM MDT Fri Oct 4 2024

.KEY MESSAGES...
- Strong winds tonight through Saturday (east).

- Critical Fire Weather conditions through Saturday.

- Strong cold front Tonight.

- No chance of meaningful precipitation over the foreseeable
  future.

&&

.UPDATE...
Latest analysis shows cold front is currently from about Havre to
just east of Helena and trailing off to Dillon...pushing
east/southeast. Winds have reached over 55 mph in our foothills
(Peak is 63 mph so far at Livingston) in response to its approach.

We decided to upgrade the High Wind Watch in our east to a
warning. Model guidance and soundings are mixed on how strong
winds may get over the east. However, there is enough indication
that turbulent activity along frontal passage may push gusts over
55 mph for a brief period. Best mixing along the front should be
strongest across northern Rosebud County/northern Custer. In
addition, pressure rises behind front are progged (HRRR) to be
16-17 mb per 6 hrs, which exceeds our rule of thumb for strong
winds. Given we will probably see a few isolated gusts reach high
wind criteria and winds will remain elevated for an extended
duration through Saturday...we upgraded the high wind watch to a
warning for Rosebud, Custer, Fallon and Carter Counties. Valid
period will be midnight to 6 pm Saturday.

Estimated Frontal Timing:
Livingston ~1000 pm
Billings ~1145 pm
Sheridan ~200-300 am
Miles City ~100 am

BT

&&

.DISCUSSION...
The rest of today through Saturday night...

Winds: Strong winds are expected over the west this afternoon
into overnight and over the east late this evening into Saturday.
Ahead of the cold front moving through tonight, stronger southwest
winds aloft mixing down, along with tightening of the surface
pressure gradient, is driving strong winds near Livingston and
the western foothills. A Wind Advisory is in effect for this area
through midnight and there is an 80% chance of gusts greater than
58 mph near Livingston.

As the cold front passes through overnight, winds will become
more westerly to northwesterly, which is unfavorable for gusts
over 58 mph in the Livingston/Nye area, but is expected to
increase winds across the rest of the region. From Wheatland to
northern Stillwater counties, a High Wind Warning is in effect
from 6 PM tonight through noon Saturday. Over the rest of the
region, gusts 30-40 mph will be common along and behind the
frontal passage, slowly decreasing through the day, and lingering
into Saturday evening over the east. Some signals point to
stronger gusts possible over the east with the frontal passage, so
a High Wind Watch over northern Rosebud to Carter counties
remains in effect from 3 AM to 6 PM Saturday, and the evening
shift will take another look to upgrade or drop when the newest
model data arrives.

Fire Weather Concerns: In addition to the strong winds and
incoming cold front, Relative Humidities are expected to be in the
teens and 20s. A Red Flag Warning is in effect over the west to
central zones as far east as Big Horn county in Montana and
Sheridan county in Wyoming from noon today through 6 PM Saturday
and over the rest of the region from midnight through 6 PM
Saturday.

Smoke from the Elk fire in the Bighorn mountains continues to
impact the area, particularly Sheridan county, and an Air Quality
Alert for Sheridan county remains in effect through 1 PM Monday.
Archer

Sunday through Friday...

Main forecast concerns are on continued warm and dry conditions
through next week.

High forecast confidence in a ridge remaining in place over the area
through much of next week. WPC cluster members are in good agreement
indicating this pattern will persist through at least the middle of
next week.  The NBM probabilities are showing very little spread in
high temperatures at KBIL from Sunday through Wednesday with the
25th and 75th percentiles only 2 to 4 degrees apart over this
timeframe.  Therefore, forecast confidence is high that highs will
be in the upper 70s to lower 80s during this timeframe. Wednesday
looks to be the warmest day when there is a 63 percent chance that
highs could reach or exceed 80 degrees. Uncertainty starts to
increase beyond Wednesday with larger spreads noted in NBM high
temperature percentiles.


&&

.AVIATION...

00Z Update: KLVM will continue to gust to around 40-50 kts from
the SW until the front passes through, shifting winds to the W/NW
(around 05-06Z). The frontal passage is expected to pass through
KBIL and KMLS around 06-07Z shifting winds NW with gusts of 35-45
kts likely. Shifting winds at KSHR have the possibility to reduce
surface visibility as a result of the Elk Fire in the Bighorns.
The most likely timing for this is 06-09Z after which winds will
become northwesterly. Just how low visibilities will get is
uncertain and is dependent on fire activity. Breezy NW winds will
continue into tomorrow with gusts of 25-40 kts likely. TS

&&

.PRELIMINARY POINT TEMP/POPS...

    Sat     Sun     Mon     Tue     Wed     Thu     Fri
-----------------------------------------------------------
BIL 049/069 042/074 045/079 048/081 048/082 050/081 050/078
    00/N    00/U    00/U    00/U    00/U    00/B    01/B
LVM 043/068 039/077 041/078 043/079 045/080 046/081 047/077
    10/N    00/U    00/U    00/U    00/U    00/B    11/B
HDN 048/069 037/076 041/080 043/083 044/084 046/083 047/080
    10/N    00/U    00/U    00/U    00/U    00/U    01/B
MLS 050/066 037/072 041/078 044/081 045/082 048/081 048/079
    10/N    00/U    00/U    00/U    00/U    00/U    00/B
4BQ 050/066 038/074 043/079 047/082 048/083 050/084 051/082
    00/N    00/U    00/U    00/U    00/U    00/U    00/B
BHK 045/065 033/069 039/077 043/082 044/082 046/083 047/080
    00/N    00/U    00/U    00/U    00/U    00/U    00/B
SHR 043/069 036/077 042/081 043/083 045/083 046/084 047/082
    00/N    00/U    00/U    00/U    00/U    00/U    01/B

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...High Wind Warning in effect from midnight tonight to 6 PM MDT
      Saturday FOR ZONES 31>33-37.
     High Wind Warning in effect until noon MDT Saturday FOR ZONES
      34-42-63-141-172-228.
     Wind Advisory in effect until midnight MDT tonight FOR ZONES
      65-66.
     Red Flag Warning in effect until 6 PM MDT Saturday FOR ZONES
      123>129.
     Red Flag Warning in effect from midnight tonight to 6 PM MDT
      Saturday FOR ZONES 130>133.
WY...Red Flag Warning in effect until 6 PM MDT Saturday FOR ZONES
      274-284.

&&

$$
weather.gov/billings