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000
FXUS65 KBYZ 212044
AFDBYZ

Area Forecast Discussion
National Weather Service Billings MT
244 PM MDT Sun Apr 21 2024

.DISCUSSION...

Today through Monday night...

High surface pressure to our southeast continues to move away
allowing more upper level westerly downsloped flow to take over
today ahead of an upper trough. This will lead to temperatures in
the mid 60s to low 70s. Southerly 850mb winds will bring in dry
air, especially in our eastern zones where RH values will likely
be in the mid to upper teens today. Prefrontal winds will gust to
around 20kts today for locations near the Dakotas border as a
synoptic pressure gradient sets up. Due to the greenup that is
being experienced for these locations and winds that aren`t
particularly strong, we have decided not to issue any fire weather
products. Western gap areas such as Livingston will see winds
gust into the 30s kts today due to high pressure over Yellowstone
Park. The Idaho Falls to Lewistown pressure gradient is not
strong and neither are the 700mb winds. Looking at observations
it looks like these winds will be caused by cold air drainage
leading to a more localized pressure gradient. NBM gives
Livingston a 40% chance of seeing a 50mph max wind gust today.
This may be on the high side but strong winds are expected
regardless.

Starting this evening around 21Z, a cold front from a low in
southern Canada will bring precipitation chances to the region.
Most locations across southeast Montana will have a 30-50% chance
of precipitation with accumulations expected to remain light.
With winds out of the north/northwest, higher elevations from the
Beartooths over to Powder River county will have the best chance
(50-70%) at getting greater than 0.1 in of precipitation. The cold
front will be accompanied by stronger gusts (20 kts) of wind
switching winds to be out of the northwest this evening into
tonight. Tomorrow will see cooler temperatures in the high 50s to
low 60s for most. Northwest winds will pick up tomorrow afternoon
as the low to our east sets up a good pressure gradient. Wind
gusts in the 30s kts will be widespread across southeast Montana
with locations in our eastern zones having a 50-70% chance of
gusting over 40 kts. RH values across the region will be in the
teens to low 20s. The lowest RH values will not coincide with the
strongest winds however with RH values in the east being in the
low to mid 20s. Temperatures will be seasonal further reducing any
fire threat. Due to these factors we don`t currently plan to
issue any fire products for tomorrow. Torgerson



Tuesday through Sunday...

An active weather pattern is shaping up this week. Be sure to
monitor the forecast over the coming days.

Flat ridge building over the northern Rockies will bring us period
of dry weather Tuesday through Wednesday morning. Temps will
respond accordingly. Look for highs into the lower 60s Tuesday
then lower-mid 70s Wednesday.

As the ridge axis shifts to the east and opens the door to Pacific
energy in the backed SW flow aloft, the potential for showers
begins in our west late Wednesday afternoon and evening. This
seems to be the transition period to a more active, cooler and
wetter pattern.

Lower heights associated with a deepening western CONUS trof will
bring higher chances (50-70%) of showers (and a few t-storms) by
Thursday. Precipitable waters will also climb to above seasonal
normals as we advect a component of plains moisture. This is also
where confidence drops.

Generally speaking, progression of the western CONUS trof will
bring elevated chances of showers and cooler (but not cold) temps
Friday through the weekend. This is the main message at this point
and folks should monitor the forecast if they have outdoor plans
next weekend. The big question is whether or not a more organized
and wetter system materializes. Ensembles continue to show
tremendous spread in QPF, but 500mb height analysis shows a
noteworthy trend. Upstream low anomaly in the north Pacific has
trended deeper, resulting in more Pacific flow coming into BC/WA
and a more transitory evolution/less organization of the western
CONUS trof. For this reason, feel that the probability of a
significant precip event has decreased with today`s model
trends...though obviously this is something to watch. Also,
regardless of how the trof evolves, there is confidence that 700mb
temps fall below zero by Friday and even colder over the weekend,
so we are not looking at a more problematic rain-on-snow event
for the high terrain. Of course, if a more dynamic system does
materialize, our mountains could see another dose of heavy
snowfall. Lower elevation ptype should remain just rain. As for
temperatures, look for 50s to mid 60s for highs across lower
elevations Friday through Sunday.

JKL

&&

.AVIATION...


There are clouds moving over the region currently as a front will
move across southeast Montana later this afternoon and evening.
This front will bring a 30-50% chance of showers to much of the
area. It will also bring a wind shift as winds will shift from
more southwesterly to northwesterly. These northwesterly winds
could gust to 25kts this evening and overnight. Tomorrow will see
stronger northwesterly winds gusting to near 40kts in some places.
Torgerson

&&

.PRELIMINARY POINT TEMP/POPS...

    Mon     Tue     Wed     Thu     Fri     Sat     Sun
-----------------------------------------------------------
BIL 036/060 033/061 037/074 048/070 047/061 043/058 042/058
    50/N    00/U    01/B    26/T    44/W    36/W    45/W
LVM 030/057 029/059 036/072 044/064 041/057 038/052 038/054
    10/N    00/B    03/W    47/T    56/T    46/W    45/W
HDN 035/061 031/064 035/077 045/072 047/064 043/062 042/061
    60/N    00/U    00/B    24/W    44/W    35/W    45/W
MLS 038/059 034/061 038/073 046/072 047/066 043/063 043/063
    31/N    00/U    00/U    12/W    32/W    13/W    33/W
4BQ 038/059 035/061 038/075 048/072 047/063 044/060 044/062
    30/N    00/U    00/U    13/W    43/T    24/W    44/W
BHK 036/057 033/058 035/070 043/070 044/062 040/059 040/059
    31/N    00/B    00/B    13/T    43/W    23/W    34/W
SHR 034/057 031/061 033/074 043/069 043/059 038/056 038/057
    52/R    00/B    01/B    26/T    65/W    46/W    55/W

&&

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

&&

$$
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