Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 242040
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
240 PM MDT Wed May 24 2017

.SYNOPSIS...

.Synopsis...A strong low pressure system moving slowly east across
the Canadian Prairies will maintain windy conditions through tonight
with some potential for damaging winds across north central Montana
through this evening before winds diminish slightly and turn to the
northwest. Moisture wrapping around the low pressure system will
spread showers south across the region overnight with a period of
rain showers likely cross much of central Montana late tonight
through Thursday morning. Breezy to windy and cooler than average
conditions persist on Thursday with a gradual warming and drying
trend anticipated through the upcoming holiday weekend.

&&

.DISCUSSION...

Tonight through Friday...Vigorous/stacked low pressure system
centered along the AB/SK border this afternoon will slowly track
southeast across SK tonight, maintaining strong westerly/veering to
northwesterly wind flow aloft and a tight pressure gradient at the
surface. Overall high wind potential will decrease through this
evening with the loss of surface heating, though a few stronger wind
gusts to near 50kts remain possible and the high wind warning will
remain in effect though midnight. Flow aloft shifting to the NW will
shift focus for strongest winds from areas along the Rocky Mtn front
to more isolated areas, particularly in the vicinity of the Island
Mtn ranges of n-central MT. TROWAL-like feature wrapping around the
back side of the low will spread precipitation south into northern
portions of the forecast area this evening and south through central
and SW MT late tonight through Thursday morning. Have increased pops
some tonight with most areas seeing less than 0.10" precip, but some
localized higher amounts in excess of 0.25-0.50" are possible across
the central MT Mtn ranges, including the Little Belts, where some of
this will fall as snow at the highest elevations late tonight into
Thursday morning. Unsettled N/NW flow aloft with embedded
disturbances continues across the region Thursday afternoon through
Friday as the low slowly moves east across S-Central Canada. Breezy
to windy conditions are likely on Thursday, though winds should be
below high wind thresholds. A few showers and thunderstorm are
possible during the afternoon period on both days with a greater
focus for convection over the higher terrain areas of SW and Western
MT. Hoenisch

Friday night through Wednesday...Overall a large upper level low
will influence our weather through the Holiday Weekend...with a
ridge trying to build in next week. Friday night through Saturday a
large upper low in Canada will attempt to enter the states keeping
us in an unsettled northwest flow pattern to start Memorial Day
Weekend. Limited moisture and instability will be found with this
pattern...bringing some scattered showers and a few weak
thunderstorms through Saturday. Best chance for precip is still west
and south of a line from about Cut Bank to Lewistown to Billings,
with more isolated activity east of this line. Ridge tries to build
in the region on Sunday and Memorial Day...although with the large
upper low across the Northern Plains we never fully escape the north
to northwest flow. Models now indicate enough of the ridge enters
our cwa making for a decent second half to Memorial Day weekend with
warming temperatures and only isolated shower and thunderstorm
activity. More of the ridge moves into the area for Tuesday into
Wednesday, however, it flattens quickly leaving us vulnerable to
weak disturbances riding over the top of it. The result will be
chances for scattered afternoon and evening shower and thunderstorm
activity each day. Thunderstorms and this point look to be weak and
limited in coverage. Each day will be warmer than the previous in
the long term. Memorial Day high temperatures in the 70s are
expected...with this warming trend looking to continue into next
week. The large disturbance to our east may linger some breezy nw
flow on Saturday...and to a lesser extend on Sunday. Lighter winds
should then be found on Memorial Day into next week. Anglin

&&

.AVIATION...
Updated 1730Z.

Strong low pressure system tracking east across southern AB/SK will
maintain strong westerly flow aloft with gusty west winds across
much of the region today. Strongest winds of 30-40kts sustained with
gusts to around 50kts will be across N-central MT terminals. Winds
will be slow to subside this evening while veering to northwesterly.
VFR conditions prevail through early this evening, then moisture
wrapping around the back side of the low will spread south bringing
MVFR cigs and a chance for rain showers from north to south late
tonight into Thursday morning. Hoenisch

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  43  60  40  64 /  60  30  20  20
CTB  41  58  38  62 /  50  30  20  20
HLN  44  62  41  66 /  30  30  20  20
BZN  39  58  38  61 /  30  50  10  30
WEY  29  50  30  53 /  10  30  40  40
DLN  36  57  38  60 /  10  30  20  30
HVR  45  62  39  66 /  50  30  10  20
LWT  40  56  37  60 /  50  50  10  20

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
High Wind Warning until midnight MDT tonight Blaine...Cascade...
Central and Southern Lewis and Clark...Chouteau...Eastern
Glacier...Eastern Pondera...Eastern Teton...Fergus...Hill...
Judith Basin...Liberty...Toole.

High Wind Warning until midnight MDT tonight Northern Rocky
Mountain Front...Southern Rocky Mountain Front.

&&

$$

weather.gov/greatfalls



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