Severe Thunderstorm Warning 45, NWS Great Falls, MT

Area Forecast Discussion
National Weather Service Great Falls MT
549 PM MDT Thu Jun 27 2019

.UPDATE...

Storms moving through North Central Montana have been producing
heavy rainfall, and even some flooding in the Great Falls area.
Have therefore issued a Flash Flood Watch for the eastern half of
North Central Montana, as these storms should produce similar
heavy rainfall in a short amount of time. Concerns will be street
flooding in the cities and low land flooding outside of town. This
will be in effect until 10 pm, as most of the shower activity
should be exiting the area by then.

The storms in this area have remained strong to severe and some
have shown signs of rotation. Some Tornado Warnings have therefore
been issued, but we've only received reports of funnel clouds so
far. However, the threat for tornados remains high along and east
of a Havre to Judith Gap line.

Have also removed Toole, Pondera, and Teton Counties from the
Severe Thunderstorm Watch. The airmass appears to have stabilized
enough there that severe storms are now unlikely. However,
additional storms have developed upstream of Lewis and Clark and
Jefferson Counties that could become strong to severe as they move
into areas with less cloudiness. Will leave that Watch in effect.

Coulston

&&

.SYNOPSIS...

A line of showers and thunderstorms has developed just east of
the Southern Rocky Mountain Front and moving toward the
northeast. Some of these storms have the potential to produce
large hail and damaging winds. This activity should diminish or
move out of the area by midnight. After today, isolated to
scattered showers and thunderstorms are possible through the
middle of next week. In addition, a few more severe storms may
occur on Friday in our eastern zones. Temperatures should be near
or slightly below- normal over the next seven days.

&&

.AVIATION...
Updated 1130 AM MDT Thu Jun 27 2019 (18Z/27 TAF issuance)

Outside of any shower/thunderstorm activity and lingering low
clouds over KGTF and KCTB, mostly VFR conditions are expected for
the next 24-hours. Disturbances embedded within the southwesterly
flow aloft along with other dynamics will produce scattered to
numerous showers and thunderstorms generally between 20Z/Thu and
04Z/Fri, while isolated lighter showers and thunderstorms are
possible before and after that period. Note that Periods of
MVFR/IFR may accompany any shower or storm. Some thunderstorms
are still expected to become severe this afternoon and early
evening, especially in central and north-central MT. Quarter-
size or larger hail and erratic surface gusts of 50 to 70 knots
are the primary severe threats, along with the potential for
heavy downpours. Regional surface winds remain light outside
outflow (i.e. precip-cooled air emanating from any shower or
storm). Lastly, patchy fog may redevelop tonight over the the
North- Central terminals again late tonight along with localized
MVFR/IFR.

&&

.PREV DISCUSSION...
/ISSUED 252 PM MDT Thu Jun 27 2019/

Remainder of today and tonight...A line of showers
and thunderstorms has developed east of the Southern Rocky
Mountain front and is moving in a southwest to northeast
direction. These storms are moving into a moist environment with
good jet dynamics, wind shear, and instability. As a result, a
severe thunderstorm watch has been issued for the entire CWA with
the exception of Beaverhead, Gallatin, Glacier, and Madison
Counties. The primary thunderstorm threat will be severe hail up
to the size of quarters or larger and wind gusts up to 60 to 80
mph. Heavy downpours of rain are also expected, which could cause
some localized flooding. This activity is expected to start
diminishing and moving out of the area around 4Z but some
isolated showers and storms will continue to linger thereafter.
rcg

Friday through next Wednesday...Latest deterministic and ensemble
model guidance is in rather good agreement during this period.
Thus, southwesterly flow aloft and embedded shortwave disturbances
should continue to affect our CWA as the longwave trough axis
remains to our west and the longwave high pressure ridge remains
essentially anchored to our east. Isolated to scattered showers
and thunderstorms are possible daily, especially during the
afternoon and evening hours. In addition, a few severe
thunderstorms may affect eastern portions of the CWA Friday
afternoon and early evening, when moderate instability and strong
vertical wind shear may exist. Temperatures should remain near or
slightly below-normal.
- Jaszka

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  49  74  50  76 /  70  20  30  10
CTB  44  71  45  73 /  60  20  20  10
HLN  49  77  50  80 /  50  30  30  20
BZN  47  78  47  79 /  20  20  30  10
WEY  37  73  40  73 /   0  10  10   0
DLN  45  73  46  75 /  10  10  10  10
HVR  50  76  52  77 /  90  20  50  20
LWT  47  74  49  72 /  50  50  60  50

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch until 10 PM MDT this evening Blaine...
Chouteau...Fergus...Hill...Judith Basin...Liberty...Toole.

&&

http://www.weather.gov/greatfalls

Special Weather Statement
National Weather Service Great Falls MT
516 PM MDT Thu Jun 27 2019

MTZ011-013-045-272345-
Chouteau-Liberty-Hill-
516 PM MDT Thu Jun 27 2019

...A STRONG THUNDERSTORM WILL AFFECT SOUTHEASTERN LIBERTY...WEST
CENTRAL HILL AND NORTHWESTERN CHOUTEAU COUNTIES...

At 516 PM MDT, a strong thunderstorm was located 17 miles southeast
of Chester, moving northeast at 30 mph.

Wind gusts up to 50 mph and half inch hail are possible with this
storm.

Locations impacted include...
Inverness and Rudyard.

This includes Highway 2 between mile markers 336 and 345.

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 4818 11072 4829 11093 4863 11063 4847 11030
TIME...MOT...LOC 2316Z 217DEG 27KT 4831 11076

SC

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREAT FALLS MT
545 PM MDT THU JUN 27 2019

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0544 PM     FLASH FLOOD      1 NW GREAT FALLS        47.52N 111.31W
06/27/2019                   CASCADE            MT   BROADCAST MEDIA

            TWITTER PICTURES OF WATER ON ROADS NEAR THE
            NW BYPASS. RELAYED BY MEDIA.

&&

JAA

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREAT FALLS MT
550 PM MDT THU JUN 27 2019

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0549 PM     TSTM WND GST     8 W CHRISTINA           47.38N 109.49W
06/27/2019  E60 MPH          FERGUS             MT   TRAINED SPOTTER

&&

JAF

Special Weather Statement
National Weather Service Great Falls MT
556 PM MDT Thu Jun 27 2019

MTZ011-047-280015-
Hill-Blaine-
556 PM MDT Thu Jun 27 2019

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

At 556 PM MDT, a strong thunderstorm was located 26 miles north of
Havre, moving northeast at 30 mph.

Wind gusts up to 50 mph and nickel size hail are possible with this
storm.

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

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

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 4882 10958 4893 10980 4900 10973 4900 10934
TIME...MOT...LOC 2356Z 216DEG 28KT 4893 10964

SC

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREAT FALLS MT
607 PM MDT THU JUN 27 2019

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0540 PM     FLOOD            3 SE DENTON             47.29N 109.91W
06/27/2019                   FERGUS             MT   TRAINED SPOTTER

            BRIEF HEAVY RAIN CAUSED FLOODING OF SPOTTERS
            BASEMENT. HOWEVER, RELATIVE IN DENTON PROPER
            DID NOT HAVE FLOODING.

&&

SAC

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