Special Weather Statement, NWS Missoula, MT

Area Forecast Discussion
National Weather Service Missoula MT
318 AM MDT Thu Jun 27 2019

...STRONG THUNDERSTORMS AGAIN EXPECTED IN THE NORTHERN ROCKIES
THIS AFTERNOON...

.DISCUSSION...Low pressure positioned to the west leaves north-
central Idaho and western Montana with southwesterly flow and
persistent disturbance passages. One of these disturbances is
producing a round of showers this morning, but the main story is
for another day with thunderstorms. Little has changed with the
projections for thunderstorms today, which are still expected to
develop in north- central Idaho and western Montana and strengthen
as they approach and move east of the Divide. The forecast holds
plenty of lift and shear for a few of the storms to be strong and
possibly severe west of the Divide, but the likelihood of severe
storms is much higher east of the Divide. Showers and
thunderstorms will linger through the evening and other than a
shower of two tonight will be mostly dry.

Locations that have rain this evening, along with clearing skies,
will have patchy fog Friday morning. Thunderstorm chances return
for Friday, but it does not look to be as unstable so likely not
as many storms as today.

Moisture profiles show an area of much drier air to move into the
region during Friday night, so there may only be a few showers
Saturday, which is represented in the current forecast. The
current weather pattern is a bit fickle so it’s not out of the
question to have additional showers on Saturday. A very similar
story seems plausible on Sunday as well.

Next week models continue to show yet another upper level low
taking up residence over NW Washington. This effectively
reestablishes southwest flow over the Northern Rockies and brings
about a return of widespread shower and thunderstorm chances on
Monday. Lesser chances are presented in the latest guidance on
Tuesday. But this seems to be primarily due to timing of the
various atmospheric waves passing through the flow which is
something that's very hard to predict this far into the future. So
have maintained a forecast for similar chances as Monday for now.

By mid week long range models suggest the coastal trough will
slide inland across Idaho and Montana, lingering over the area
through the end of next week. This type of pattern would support
widespread showers and thunderstorms across the area which could
affect Independence Day celebrations in some places.

&&

.AVIATION...Surface observations are starting to show many spots
with small dew point depressions, so patchy fog is possible for a
few hours this morning. Cloud cover and showers are moving into
north-central Idaho early this morning which will move into
western Montana by sunrise. Isolated thunderstorms are also
embedded so a few lightning strikes are possible during this
morning. The unstable and active southwesterly flow over the
region will again lead to thunderstorms this afternoon. Convective
allowing models show thunderstorms developing in north-central
Idaho and western Montana beginning around 27/1900z. These
thunderstorms are expected to strengthen with a few strong and
potentially severe thunderstorms possible west of the Divide, but
conditions east of the Divide have been consistently forecast to
be favorable to for severe storms. Most of the storm activity will
decrease by 28/0300z and those with appreciable rain will likely
have a few hours of fog during Friday morning.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...None.
ID...None.
&&

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MISSOULA MT
622 AM MDT THU JUN 27 2019

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

0615 AM     HAIL             9 SW WHITEFISH          48.31N 114.47W
06/27/2019  M0.75 INCH       FLATHEAD           MT   TRAINED SPOTTER

&&

AL

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MISSOULA MT
658 AM MDT THU JUN 27 2019

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

0618 AM     HAIL             WHITEFISH               48.41N 114.33W
06/27/2019  M0.75 INCH       FLATHEAD           MT   TRAINED SPOTTER

            DIME TO PENNY SIZE HAIL.

&&

AL

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MISSOULA MT
959 AM MDT THU JUN 27 2019

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

0319 PM     HAIL             4 SW COMO               46.06N 114.23W
06/26/2019  M1.00 INCH       RAVALLI            MT   NWS STORM SURVEY

            MINOR TREE DAMAGE REPORTED.

&&

AL

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MISSOULA MT
1018 AM MDT THU JUN 27 2019

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

0341 PM     HAIL             6 ESE GRANTSDALE        46.17N 114.03W
06/26/2019  M1.25 INCH       RAVALLI            MT   NWS STORM SURVEY

&&

AL

Special Weather Statement
National Weather Service Missoula MT
1221 PM MDT Thu Jun 27 2019

MTZ006-007-271845-
Bitterroot/Sapphire Mountains MT-Butte/Blackfoot Region MT-
1221 PM MDT Thu Jun 27 2019

...SIGNIFICANT WEATHER ADVISORY FOR NORTHWESTERN DEER LODGE AND
SOUTHEASTERN GRANITE COUNTIES UNTIL 1245 PM MDT...

At 1220 PM MDT, Doppler radar was tracking a strong thunderstorm 16
miles west of West Valley, or 20 miles west of Anaconda, moving
northeast at 40 mph.

Dime size hail and winds in excess of 40 mph will be possible with
this storm.

Locations impacted include...
Philipsburg, Georgetown and Porters Corner.

LAT...LON 4598 11331 4604 11349 4640 11328 4630 11304
TIME...MOT...LOC 1820Z 204DEG 37KT 4608 11336