000
FXUS65 KTFX 240535
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
1135 PM MDT Tue Apr 23 2024

...Updated Aviation Section...

.SYNOPSIS...

Winds will begin to increase late tonight as surface high
pressure departs the Northern Rockies, with breezy and gusty
winds then expected through the day on Wednesday. These breezy
and gusty southwest to west winds will help to push temperatures
well above normal across all of Southwest through North Central
Montana on Wednesday, with highs peaking in the 70s to
potentially low 80s.

&&

.UPDATE...

No need for an update to the overnight portion of the forecast;
the current forecast has a good handle on the situation.

Thin high cloudiness will continue to move through the high
pressure ridge, as winds remain relatively light. Low temperatures
overnight still look to remain mostly in the 30s at lower
elevations and in the mid to upper 20s in the mountains, keeping
the area 5 to 10 degrees warmer than seasonal averages. -Coulston

&&

.AVIATION...
1135 PM MDT Tue Apr 24 2024 (24/06Z TAF Period)

VFR conditions prevail across all terminals during this TAF period.
Wednesday afternoon and evening there is a slight (20%) chance of
rain at the KEKS and KBZN terminals. There wasn`t enough
probabilistic guidance to include a PROB30 group for the rain for
those two TAFs. In the middle of this TAF period at the KGTF and
KCTB terminals there will be winds gusting up to 20 kts and 30 kts
respectively. Wednesday afternoon there will be isolated instances
of mountain wave turbulence across North-central and Central
Montana. -IG

Refer to weather.gov/zlc for more detailed regional aviation
weather and hazard information.

&&

.PREV DISCUSSION...
/ISSUED 520 PM MDT Tue Apr 23 2024/

Rest of today through Wednesday...H500 transient ridge axis will
slide east of the Northern Rockies through this evening, with the
upper level flow backing to the west to southwest in its wake
ahead of shortwave troughing moving over the Gulf of Alaska and
Western Canada. Pacific moisture (at least within the upper
levels) advecting northeast within this west to southwest flow
aloft will lead to increasing cloud cover from southwest to
northeast through the late afternoon and evening hours tonight.
Surface flow will also begin to veer to the south and west
throughout the overnight hours tonight as surface high pressure
moves east of the Northern Rockies and cyclogenesis occurs over
Central Alberta ahead of the aforementioned shortwave trough.
These veering winds combined with the increasing upper level
cloudiness will help to keep temperatures tonight some 5-10
degrees warmer than last night, with most locations falling into
the 30s. By Wednesday strong low level warm air advection and
downsloping winds will help to push high temperatures into the
70s across most lower elevations, with even a few locations
approaching the low 80s over the plains of Central and North
Central Montana. Isolated to scattered rain and rain/snow
mountain showers will be possible from the late afternoon through
overnight hours on Wednesday across Southwest and Central
Montana; however, precipitation amounts beneath any given shower
will be light and generally less than 0.05". - Moldan

On Thursday an upper level disturbance moving over the Great
Basin towards the Central Rockies will help to spread
precipitation north across Southwest and into portions of Central
Montana. For areas along and south of the Montana Highway 200
Corridor and west of US Highway 287 south of Three Forks there is
a 10 - 20% chance for a 0.10 of an inch of rain or greater. For
the lower-elevations from Three Forks to the Bozeman area south
to the Idaho border there is a 15 - 40% chance of 0.25 of an inch
of rain or greater on Thursday. The rain in Southwestern Montana
on Thursday could come in the form of a thunderstorm. For the
Gallatin and Madison ranges there is a 20 - 40% chance for a
tenth of an inch of snow or greater on Thursday. - IG/Moldan

Friday through next Tuesday... On Friday an upper-level trough
will begin to over North-central, Central, and Southwestern
Montana. This will bring cooler temperatures and precipitation to
the area. This upper-level trough will remain in place over North-
central, Central, and Southwestern Montana on Saturday. At this
time precipitation type/amount and how much cooler the area will
get with this system is uncertain. Additionally, currently it is
likely that locations along and south of the Montana Highway 200
Corridor will receive the highest total precipitation amounts.
The mountains of Southwestern Montana will most likely receive
snow. This will need to continue to be monitored for updates.

On Sunday clusters indicate that an upper-level ridge will most
likely move over North-central, Central, and Southwestern
Montana. On Monday that upper-level ridge will most likely stay
over the area. This will bring a slight warm-up to North-
central, Central, and Southwestern Montana on Sunday and Monday.
On Tuesday three of the clusters (76% of ensemble members)
indicate that there will be an upper-level trough that begins to
move toward Montana. This would indicate a new weather system
moving toward Montana. The other cluster (24% of ensemble
members) has zonal flow over North- central, Central, and
Southwestern Montana which would keep status quo weather for the
area. -IG

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  39  77  47  66 /   0  10  20  10
CTB  33  72  39  64 /   0   0  10   0
HLN  39  77  46  67 /   0  10  20  20
BZN  34  74  45  64 /   0  10  20  60
WYS  28  64  38  53 /   0  20  30  90
DLN  35  70  43  63 /   0  10  20  40
HVR  38  75  44  69 /   0   0  10   0
LWT  35  72  43  63 /   0  10  10  20

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

http://www.weather.gov/greatfalls