Severe Thunderstorm Warning 26, NWS Great Falls, MT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1100 PM MDT Thu Jul 10 2014

.DISCUSSION...
Update forthcoming. Lingering monsoonal moisture, along with
atmospheric instability along the southwest Montana/Idaho border, is
allowing isolated thunderstorms to continue. However, the moisture
source is beginning to decrease and convective activity should
further decrease with the loss of daytime heating. Have scaled back
the POP field through midnight, keeping POPs over extreme south and
southeast Montana. Have scaled back POPs even further after
midnight. In the north, circulation around an upper low centered
over western Saskatchewan is pushing moisture into an unstable
airmass and across the Canadian prairie. This moisture has combined
with a cold front moving south and the result is the development of
isolated thunderstorms. Satellite imagery indicates a strong
thunderstorm moving east-southeast across southern Alberta at this
time. RUC model data and HRRR analysis want to bring the core of
this storm south of the international border after 05z, affecting
areas along the Hi-Line. Have gone with low POPs across the northern
portion of the county warning area for this reason, bringing the
threat as far south as Lewistown and as far west as Great Falls per
the RUC. Temperatures look reasonable.

&&

.AVIATION...
UPDATED 0500Z.
VFR conditions will generally continue across the area through at
least Friday evening. Moisture wrapping around a low pressure system
in central Canada combined with a weak cold front moving south
through north central/central Montana area has caused scattered
thunderstorms to develop across north central Montana (including
KCTB KHVR). These storms will likely weaken as they spread south
into central (KGTF KLWT) Montana through, so have only mentioned
VCSH in those TAFs at this time. Clouds/showers/storms will decrease
after 15Z as the system exits the area. However, monsoonal moisture
will move back into southwest Montana (including KBZN) after 18Z,
bringing a chance of thunderstorms there.
Coulston

&&

.PREV DISCUSSION...Issued 242 PM MDT Thu Jul 10 2014

Thursday through Saturday...Hot and dry conditions will continue
as the slowly moving large scale ridge continues to be dominant
force in the weather pattern over much of the Western United States.
Will continue to remain in a transition period on the edge of the
ridge through at least the next 24 hours. This will allow for
showers to develop as moisture allows. The best chance will be
with afternoon heating over the Mountains of Southwest Montana and
across the highline Thursday Evening as a weak disturbance moves
across the northern counties. By Friday a slight increase in
available moisture will allow for more showers and thunderstorms
to develop with afternoon heating...however showers will likely be
limited to scattered at best coverage. Another round of showers
will again occur on Saturday during peak heating mainly over the
higher terrain. Suk

Saturday night through Thursday...An upper level ridge high
pressure will be over the region this weekend...then the upper level
ridge will shift westward on Monday...as a fairly strong upper level
low pressure over the Great Lakes area rotates a bit cooler air into
the region. As the upper level low over the Great Lakes begins to
move eastward on Tuesday...the upper level ridge will also start to
shift back eastward for Tuesday afternoon through Thursday. Thus
fairly warm temperatures are expected for Sunday...then seasonable
temperatures for Monday and Tuesday...with a return to slightly
above normal temperatures for Wednesday and Thursday. In terms of
precipitation...confidence is quite low on any one given day...thus
most days the chances for thunderstorms are fairly isolated. The
best time frame for any storms to occur will be late afternoon
through around Midnight...but again the thunderstorm activity should
be fairly isolated and not have significant impacts on any one given
day. Brusda

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  54  78  54  86 /  20  10  10  10
CTB  51  75  50  84 /  20  10  10  10
HLN  58  84  58  88 /  10  10  20  20
BZN  53  83  54  83 /  10  30  20  40
WEY  44  79  44  76 /  30  50  40  50
DLN  54  84  55  83 /  10  20  20  40
HVR  56  80  53  88 /  20  20  10  10
LWT  54  78  53  84 /  20  20  20  20

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

weather.gov/greatfalls
www.twitter.com/NWSGreatFalls
www.facebook.com/US.NationalWeatherService.GreatFalls.gov

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREAT FALLS MT
1025 PM MDT THU JUL 10 2014

MTZ009-010-110515-
EASTERN GLACIER MT-NORTHERN ROCKY MOUNTAIN FRONT MT-
1025 PM MDT THU JUL 10 2014

...SIGNIFICANT WEATHER ADVISORY FOR NORTHERN GLACIER COUNTY UNTIL
1115 PM MDT...

AT 1018 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING
A STRONG THUNDERSTORM 36 MILES NORTH OF KIOWA...OR 58 MILES NORTHWEST
OF CUT BANK...MOVING EAST AT 35 MPH.

HAIL UP TO ONE-HALF INCH IN DIAMETER AND WIND GUSTS UP TO 40 MPH ARE
EXPECTED WITH THIS STORM...ALONG WITH HEAVY RAIN AND FREQUENT
DANGEROUS LIGHTNING.

LOCATIONS NEAR THE PATH OF THIS STORM INCLUDE...MAINLY RURAL AREAS
OFNORTHERN GLACIER COUNTY.

IF THREATENING WEATHER APPROACHES YOUR AREA...TAKE SHELTER IN A
STURDY BUILDING.

LAT...LON 4901 11271 4871 11302 4887 11359 4901 11354
TIME...MOT...LOC 0425Z 287DEG 29KT 4901 11337

WARANAUSKAS

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREAT FALLS MT
101 AM MDT FRI JUL 11 2014

MTZ011-047-110745-
BLAINE MT-HILL MT-
101 AM MDT FRI JUL 11 2014

...SIGNIFICANT WEATHER ADVISORY FOR EASTERN HILL AND WESTERN BLAINE
COUNTIES UNTIL 145 AM MDT...

AT 1254 AM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING
A STRONG THUNDERSTORM 21 MILES NORTHWEST OF HAVRE...MOVING SOUTHEAST
AT 35 MPH.

HAIL UP TO ONE-HALF INCH IN DIAMETER AND WIND GUSTS UP TO 40 MPH ARE
EXPECTED WITH THIS STORM...ALONG WITH HEAVY RAIN.

LOCATIONS NEAR THE PATH OF THIS STORM INCLUDE...MAINLY RURAL AREAS
OFEASTERN HILL AND WESTERN BLAINE COUNTIES.

LAT...LON 4872 10927 4847 10943 4869 11011 4892 10991
TIME...MOT...LOC 0701Z 297DEG 31KT 4876 10988

WARANAUSKAS