Area Forecast Discussion
Issued by NWS Great Falls, MT

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
FXUS65 KTFX 190527

Area Forecast Discussion
National Weather Service Great Falls MT
1125 PM MDT Sun Mar 18 2018

...Aviation Section Updated...


The update this evening included refreshening and updating the
forecast via radar and short-range model trends. Still
anticipating snow to increase across northwestern areas through
the night time hours, where a Winter Weather Advisory remains in
effect until noon tomorrow. Otherwise, only light snow showers
remain across central areas thanks to a passing closed upper-level
low. This feature will quickly exit to the east with mostly dry
conditions to follow. Snow will gradually increase across the
Plains of far northern MT late tonight/early tomorrow possibly
impacting the Hi-Line from Havre on west. Not anticipating much in
the way of significant snowfall accumulations in these areas.
However, we will continue to keep a close eye on these areas
through the overnight hours if any additional highlights become
necessary. KLG



Areas of snow and some fog will continue to cause minor impacts
across central and north-central Montana through tonight and Monday.
Temperatures moderate early this week, before a cooler and more
unsettled pattern potentially returns late in the week.


Updated 0525Z.

Southwest Montana : MVFR conditions are possible through the early
morning hours at the KBZN and KEKS terminals due to ceilings and
visibilities from snow showers and mist, however, conditions are
generally expected to be VFR for the remainder of the 1906/2006 TAF
period. Mountain obscuration is likely due to a broken/overcast mid-
level cloud deck for the remainder of tonight and through the day on

North Central Montana : MVFR, IFR, and even LIFR conditions are
expected through much of the 1906/2006 TAF period at the KCTB, KHVR,
KGTF, and KLWT terminals, with a period of MVFR conditions possible
at the KHLN terminal early this evening then improving to VFR
thereafter. LIFR conditions are most likely to occur at the KCTB,
KHVR, and KGTF terminals tonight and early Monday morning due
reduced visibilities from freezing fog/snow and low ceilings as a
upper level disturbance crosses the region. Mountain obscuration
will occur over this timeframe. Snow and fog will gradually come to
an end during the late morning/early afternoon hours today, however,
low ceilings are expected to remain. - Moldan


Updated 18/400 AM.

Daytime high temperatures will be on the rise at both low and high
elevations into the middle of the upcoming work week, with
temperatures peaking on Wednesday and Thursday in the 40s and 50s
across most of Southwest and North Central Montana. Precipitation
coverage will be on the increase from Wednesday and into the first
half of the weekend, with some of the precipitation falling in the
form of rain, especially at lower elevations (i.e. valleys and over
the plains of North Central Montana). Increased snowmelt is likely
by the middle of the week, as the combination of warming
temperatures and rain falling on the antecedent snowpack occurs.


/ISSUED 510 PM MDT Sun Mar 18 2018/

Today through Monday night...Areas of light snow and snow showers
will continue into this evening and overnight across the area in
association with a weakening shortwave that had been a closed upper
low across our area. A more focused area of snow will develop this
evening along the Northern Rocky Mountains this evening in
association with another disturbance rotating the upper low in
southern Canada. This will bring another round of accumulations from
Marias Pass north as well as extending eastward along and east of
the Hi-Line. A Winter Weather Advisory continues for the Northern
Rocky Mountain Front beginning at 9 pm this evening and extending
through Monday morning. Advisories may need to be extended east once
confidence increases in snow accumulations to the east across far
north-central Montana. In the wake of the upper level disturbance
passage, downsloping and subsidence aloft should help to scour out
the lower clouds that have plagued Central MT of late. Precip will
wind down as well, but may linger a bit longer in the mountains. CC

Tuesday through Saturday...Main forecast concerns are warming
temperatures, followed by a return to wet and unsettled weather.

H500 ridge over the Desert Southwest/Great Basin will amplify over
the Rockies Tuesday and into the day on Wednesday, all the while a
shortwave over the Gulf of Alaska digs towards the Pacific Northwest
and deepens. A weak shortwave traversing the amplifying ridge
Tuesday afternoon will bring some slight chance POPs to Southwest
Montana where better low- to mid-level moisture resides, but
otherwise will generally just bring some high clouds to the
remainder of North Central Montana for the afternoon/evening hours
on Tuesday. During the day on Wednesday the H500 ridge axis slides
east across Southwest and North Central Montana, with the flow
becoming increasingly southwesterly by the evening/overnight hours.
1000-500 mb thickness values on Wednesday climb to around 435-445dam
and warm air advection increases ahead of the approaching H500
trough over the Pacific Northwest, which should support high
temperatures in the 40s/50s south and west of a Browning, to Great
Falls, to Lewistown line, and the 30s north of this line (with the
coolest reading over Blaine and Hill counties where a substantial
snowpack still resides). Precipitation chances over the mountains of
Southwest Montana and along the Continental Divide on Wednesday will
be on the increase as the H700-H500 southwest flow begins to usher
in additional Pacific moisture, but will likely be very showery in
nature. High temperatures on Thursday will be similar to that of
Wednesday as 1000-500mb thickness values remain in the 435-445dam
range, however, increasing mid-level clouds and precipitation
coverage could hold temperatures down slightly. As just stated,
precipitation coverage is expected to be on the increase across most
of Southwest and North Central Montana during the day and night on
Thursday, as synoptic scale ascent associated with a shortwave
rotating through the main H500 trough moving from the Pacific
Northwest and towards the Northern Rockies overspreads the region.
Model solutions begin to diverge with the evolution of the upper
level pattern from Friday onwards, which will have an affect on the
timing of additional rounds of precipitation for Southwest and North
Central Montana. However, continued wet and unsettled weather is
expected to end the work week and persist into the first half of the
weekend. - Moldan


GTF  24  40  24  43 /  20  10  10   0
CTB  20  34  21  38 /  80  60  10  10
HLN  24  41  25  44 /  20  10  10  10
BZN  21  39  21  43 /  30  20  20  10
WEY  13  31  12  34 /  20  20  30  20
DLN  18  36  17  39 /  20  10  10  10
HVR  17  31  18  35 /  50  80  30  10
LWT  21  37  23  40 /  20  30  20   0



Flood Advisory continues until further notice for snowmelt in
Jefferson...Broadwater...and Northern Gallatin Counties.

Winter Weather Advisory until noon MDT Monday Eastern Glacier...
Northern Rocky Mountain Front.


$$ is the U.S. government's official web portal to all federal, state and local government web resources and services.