Special Weather Statement, NWS Great Falls, MT

Area Forecast Discussion
National Weather Service Great Falls MT
545 PM MDT Thu May 13 2021

...AVIATION SECTION UPDATED...

.SYNOPSIS...

Light rain showers and some isolated thunderstorms associated
with a weak weather disturbance continues to move across the
region through this evening. Additional weak weather disturbances
moving across the area will maintain a small chance for showers
at times each day through Saturday, with temperatures remaining
close to seasonal averages. Stronger high pressure builds over the
region later this weekend into early next week for a period of
warmer than average temperatures with mainly dry conditions.

&&

.DISCUSSION...

Tonight through Saturday...Clouds and widely scattered showers,
along with a few isolated thunderstorms, continue to track through
the area through this evening as a weak weather disturbance
passes through the region from northwest to southeast. Another
weak disturbance in west- northwesterly flow aloft moves from
southern BC into AB this evening, which will likely lead to some
isolated showers and possibly a weak thunderstorm over
northcentral MT late this afternoon and evening. The next upper
level trough moving in from the eastern Pacific splits with most
of the energy diving south across CA and into the SW US this
weekend, though some weaker disturbances are expected to track
across the Northern Rockies and Southwest MT Friday and Saturday.
This will maintain a chance for isolated to scattered showers and
a few thunderstorms mainly during the afternoon/evening periods
through Saturday. Temperatures remain near seasonal averages
through Friday with some warming occurring on Saturday, as heights
rise and upper level ridging begins building in from the NW.

Sunday through next Thursday...Upper level ridging strengthens
across the NW US and Northern Rockies Sunday and Monday for mainly
dry conditions and temperatures warming above seasonal averages.
Medium range deterministic and ensemble guidance continues to
trend toward stronger and longer duration ridging over the region
that now looks to continue through at least Tuesday of next week.
This would result in afternoon temperatures near or exceeding 80F
for many lower elevation sites Sunday through Tuesday along with
minimal chances for precipitation. The ridge looks to shift east
by the middle of next week with SW flow increasing across the
region Tuesday and Wednesday as the next Pacific trough moves
onshore bringing better chances for precipitation and some cooling
by mid-late next week.

&&

.AVIATION...
545 PM MDT Thu May 13 2021 (14/00Z TAF period)

Weak disturbances embedded within an unsettled northwesterly flow
will continue to bring scattered showers and a few thunderstorms to
the north-central terminals through 14/06Z, with any lingering
activity being mostly confined to KHVR thereafter. Additional shower
and thunderstorm activity can be expected Friday afternoon and
evening, with the best chances likely being southeast of a KHLN to
KGTF line. Mostly VFR conditions expected for this TAF period, but
brief and localized periods of MVFR conditons, mountain obscuration,
and gusty erratic winds will be possible during periods of
convective precipitation. -RCG

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

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  40  66  40  72 /  30  10  10  10
CTB  39  65  40  71 /  30  20   0  10
HLN  45  69  44  74 /   0  20  10  20
BZN  40  69  40  70 /   0  20  10  30
WYS  30  65  30  63 /  10  40  20  40
DLN  41  67  40  69 /   0  20  10  20
HVR  42  69  42  73 /  40  10   0  10
LWT  39  63  39  67 /  20  40  10  30

&&

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

http://www.weather.gov/greatfalls

Special Weather Statement
National Weather Service Great Falls MT
657 PM MDT Thu May 13 2021

MTZ011-045-140130-
Liberty-Hill-
657 PM MDT Thu May 13 2021

...A STRONG THUNDERSTORM WILL AFFECT NORTHEASTERN LIBERTY AND
NORTHWESTERN HILL COUNTIES...

At 656 PM MDT, a strong thunderstorm was located 27 miles north of
Joplin, or 31 miles north of Chester, moving southeast at 25 mph.

Brief heavy rain, winds in excess of 40 mph, and half inch hail are
possible with this storm.

This storm will remain over mainly rural areas of northeastern
Liberty and northwestern Hill Counties.

If outdoors, consider seeking shelter inside a building.

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

LAT...LON 4877 11043 4864 11079 4898 11099 4900 11092
      4900 11068
TIME...MOT...LOC 0056Z 331DEG 22KT 4896 11082

SC

Special Weather Statement
National Weather Service Great Falls MT
739 PM MDT Thu May 13 2021

MTZ011-045-140215-
Liberty-Hill-
739 PM MDT Thu May 13 2021

...A STRONG THUNDERSTORM WILL AFFECT EAST CENTRAL LIBERTY AND WEST
CENTRAL HILL COUNTIES...

At 737 PM MDT, the strong thunderstorm was weakening somewhat, but
it has formed a cluster of weaker storms now. This cluster was
located 15 miles north of Inverness, or 23 miles northeast of
Chester, moving southeast at 25 mph.

Brief heavy rain, winds in excess of 30 mph, isolated lightning
strikes and pea size hail are possible with this storm.

Locations impacted include...
Hingham and Rudyard.

This includes Highway 2 between mile markers 338 and 348.

If outdoors, consider seeking shelter inside a building.

These storms may still intensify, so be certain to monitor local
radio stations and available television stations for additional
information and possible warnings from the National Weather Service.

LAT...LON 4880 11088 4892 11063 4864 11025 4847 11057
TIME...MOT...LOC 0137Z 322DEG 22KT 4878 11067

SC