Drought in Montana, April 1 to 24, 2023

Area Forecast Discussion...UPDATED
National Weather Service Glasgow MT
842 PM MDT Fri Mar 31 2023

.DISCUSSION...

Evening Update: Strange transitional weather pattern is underway
this weekend. Whereas we had snow yesterday (Thursday), the SPC
thunderstorm outlook brings a general risk of thunderstorms to our
CWA later tomorrow (Saturday). This precipitation will be more
scattered and showery in nature compared to the stratiform
precipitation we have been experiencing most of the last 5
months. This showery precipitation is evidenced by the convection-
allowing model data which shows the greatest impact to be a few
thunderstorms during Saturday afternoon, then rain showers for the
rest of the evening. But, a few snow showers and scattered
freezing rain could mix it all together after sunset for our
northern tier zones. Over the 6-hour period from 6 PM to midnight
tomorrow, model data is showing the chance for some banded
precipitation features which could result in accumulations of rain
over portions of the still remaining snowpack near and north of
the Hi-line. Those on shift tomorrow through tomorrow evening will
need to closely watch satellite data and observations as our
radar is currently down for repairs. ----BMickelson

Afternoon Update: Not too many changes were made.

Going High Wind Watch for southern/SW Phillips, Garfield and
Petroleum counties looks good. Models did not offer much change in
the wind field as there seems to be a 50-80% chance of obtaining a
high wind gust in the current Watch area. Winds aloft are
generally 40-45 kts so expecting barely obtaining high wind
warning and thus low impact.

The front that precedes the winds moves east across the area late
Saturday/Saturday evening. Thunder possibility is slight for our
western zones with this and models are showing a higher
probability of precipitation as a result for Saturday Night.

Melting of the snowpack (along and north of Highway 2 from Malta
to the ND border) will occur Saturday and early Saturday Night
with highs reaching the mid 30s to mid 40s. Rainfall Saturday
Night isn't expected to be that heavy (0.10" at best) and mainly
south of the snowpack.

Freezing rain Saturday Night looks be a very small chance (20% or
less) as temperatures will probably not drop below freezing till
after the rainfall for areas near Highway 2. However, temps will be
cooler closer to the Canadian border (especially Sheridan County)
and chances look to be higher. Will cover this with a social
media post for now and issue highlights if needed as we draw
closer. TFJ

MORNING DISCUSSION:
Synoptic Setup: Forecast begins with the coldest air of the north
American continent situated over the Hudson Bay. Most troughs and
ridges are currently being moved around this anchor point in the
flow. Split flow has set up over the eastern third of the CONUS
with the ridge across British Columbia, Idaho, and Washington
while the trough base is ejecting through the Four Corners. Behind
it flow slams back together to zonal flow over the Northeast
Pacific.

Today and Tonight: Last of the early morning snow will exit the
area to the southeast early this morning leaving behind low clouds
across the region and maybe a small amount of fog over the Milk
River Valley. Any fog that does form up should burn off by about
Noon. However, with temperatures breaking above freezing for highs
int he southwest today there may be sufficient moisture to bring
back fog tonight during the normal hours of 3 to 10 AM.

Saturday through Sunday: Peak of the ridge in the split flow will
move through Saturday bringing warmer conditions and 40s across
most of the area for highs. However, a disturbance will move in
behind it and drag Pacific moisture in along a warm front Saturday
night. As this moisture passes across the area there is a small
chance that any rain that forms overnight could potentially freeze
on contact with the ground leading to a freezing rain threat with
slippery roads conditions. Confidence in this and the placement
of it is low and will allow the day shift a second look at it
before acting on any threats here. Low pressure forming over
southern Canada will drag a cold front through Sunday afternoon
bringing a chance for light snow along with increased winds. These
winds will get strong with a High Wind Watch being put out across
the west.

Sunday night through Tuesday night: Arctic cold air will fall in
behind the front dragging daytime highs back into the 20s early
in the week. Minor chances for snow are expected during these
periods.

Wednesday onward: A ridge will begin pressing in over the western
third of the Conus and Canada. This will bring increasing
temperatures each day as it shallows out the arctic air and scoops
it off to the east. By Friday the highs will be in the 40s and
approaching 50s which should help to burn off much of the
remaining snow coverage. GAH

&&

.AVIATION...

LAST UPDATE: 0235Z, Friday evening, March 31

FLIGHT CAT RANGE: Mainly VFR, with possible MVFR 05-14z early
Saturday for KGGW and KOLF.

DISCUSSION: Clouds will clear enough this evening with light winds
that there is about a 30% chance of fog from 06-12z tonight from
KGGW to KOLF.

After a comfortable day of warming temperatures and melting snow, a
cold front will push scattered rain showers and few general
thunderstorms through the area Saturday afternoon and evening.

WIND: Generally light and variable through 06Z Saturday night for
KGGW and KOLF. From the south and southwest around 10 kts for KSDY
and KGDV. Just beyond the end of this TAF cycle, much strong west
winds will arrive with gusts in excess of 40 kts.

TFJ/BMickelson

&&

.GLASGOW WATCHES/WARNINGS/ADVISORIES...
High Wind Watch from Sunday morning through Sunday evening for
Central and Southeast Phillips...Garfield...Petroleum...
Southwest Phillips.

&&

weather.gov/glasgow