Severe Thunderstorm Warning 11, NWS Great Falls, MT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
241 PM MDT Wed May 28 2014

.DISCUSSION...

Tonight through Friday...Primary concern in the near-term is the
developing threat for strong/severe convection this evening.
Visible satellite showing several area of growing cumulus. Strong
deep layer shear and moderate instability will aid in storm
development as the evening progresses. Highest threat for severe
weather...including the potential for an isolated tornado...will be
generally along and east of a line from Havre to Stanford. Can't
rule out convection over C/SC MT but greatest threat there will be
gusty winds. Beyond tonight...anticipate benign conditions for the
day on Thursday with seasonable temps generally in the mid 60s to
near 70 degrees. Temps warm back into the 70s for the lower
elevations on Friday. May see a few storms develop over southwest
MT during the afternoon hours. Foltz

Friday Night through Wednesday...Extended forecast period shaping up
to be several days of mostly cloudy skies with multiple periods of
rain as a broad, slow-moving, Pacific shortwave trof works its way
across the region.  On Sat morning, the trof axis and its closed
low pressure area will be just coming ashore along the California
coast.  South-southeast winds aloft ahead of the trof axis will push
a swath of monsoonal moisture from the Four Corners area into the
Northern Rockies, leading to first round of scattered showers and
thunderstorms Sat aftn/eve. As the trof reaches the Great Basin on
Sun, winds aloft switch to east-southeast, which will draw moisture
from the Central Rockies and upper Midwest states back westward into
MT. This moisture should combine with Pacific moisture accompanying
the shortwave, resulting in widespread precipitation from Sun
through Tues.  As noted in earlier discussions, rainfall amounts and
the location(s) of heavier rainfall are of particular concern as
there is potential that several areas may receive high amounts that
will combine with ongoing snowmelt to quickly raise river and stream
levels, especially over the southwest counties and along the Rocky
Mtn Front. Latest runs of the GFS and ECMWF forecast models are in
good agreement on the shortwave's speed/path and the broad precip
coverage, but marked differences continue on total rainfall amounts
and locations of the higher rainfall values.  Too early yet to lean
toward any one model's rainfall solution, but the overall forecast
of persistent wet conditions should be a heads-up to local land and
emergency managers, as well as the general public, of an increasing
flood threat.  The rain should taper off Tues night, with only
spotty precip coverage expected on Wed, but the flood threat would
continue into late next week as high water levels make their way
through area river/stream basins. Waranauskas&&

.AVIATION...
UPDATED 2345Z.
One weather disturbance will result in showers and thunderstorms
over central Montana spreading into northcentral Montana early this
evening. Expect a brief period of MVFR or even IFR visibilities and
possibly ceilings in heavy rain. There will also be local hail and
wind gusts to 50 knots with the thunderstorms. Another weather
disturbance will bring a few showers near and after midnight with a
risk of thunderstorms near and east of a KHVR-KLWT line. Late
tonight through Thursday morning expect skies generally clearing
from the west. Also gusty west winds 20 to 30 knots will develop
Thursday over the northern plains. Blank

&&

.HYDROLOGY...
UPDATED 110 PM Wednesday.
A Flood Warning remains in effect for the Big Hole River and a Flood
Watch has now been issued for the Gallatin River at Logan and
Gallatin Gateway. Guidance from the MBRFC continues to suggest that
water levels on several other rivers in Southwest Montana will rise
to near flood stage in the coming days.

An ESF has been issued for Southwest Montana for the short term...as
a few small creeks have reached bankfull. However...many of these
smaller streams and creeks that have reached bankfull are doing so
for only a few hours each day before lowering again.

Main concern for the entire forecast area continues to be the
potential for heavy precipitation developing over a snow packed
mountain range. Medium range models continue to indicate the
potential for a widespread moderate to heavy rainfall event this
weekend through early next week which could produce an increase in
hydrologic issues.

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  47  67  40  73 /  40  10   0  10
CTB  43  64  36  72 /  50  10   0  10
HLN  48  70  44  77 /  10  10  10  20
BZN  45  70  39  75 /  10  10  10  30
WEY  37  69  32  76 /  10  10  10  20
DLN  44  69  39  74 /  10  10  10  20
HVR  50  72  39  77 /  40  10   0  10
LWT  47  65  42  70 /  30  10   0  10

&&

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

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PRELIMINARY LOCAL STORM REPORT...CORRECTED
NATIONAL WEATHER SERVICE GREAT FALLS MT
517 PM MDT WED MAY 28 2014

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

0512 PM     HAIL             3 SSW ULM               47.39N 111.54W
05/28/2014  E0.75 INCH       CASCADE            MT   NWS EMPLOYEE

            MOSTLY PEA-SIZED HAIL BUT ONE STONE OF 0.75 INCH

&&

CORRECTED REMARKS

MPJ

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREAT FALLS MT
519 PM MDT WED MAY 28 2014

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

0515 PM     HAIL             11 SSE ULM              47.28N 111.43W
05/28/2014  E0.50 INCH       CASCADE            MT   TRAINED SPOTTER

&&

MPJ

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREAT FALLS MT
520 PM MDT WED MAY 28 2014

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

0518 PM     HAIL             2 N GREAT FALLS         47.53N 111.29W
05/28/2014  E0.88 INCH       CASCADE            MT   NWS EMPLOYEE

&&

MPJ

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREAT FALLS MT
523 PM MDT WED MAY 28 2014

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

0518 PM     HAIL             5 SSE ULM               47.37N 111.48W
05/28/2014  M0.70 INCH       CASCADE            MT   TRAINED SPOTTER

&&

UTTECH

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREAT FALLS MT
530 PM MDT WED MAY 28 2014

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

0515 PM     HAIL             5 S CASCADE             47.20N 111.70W
05/28/2014  E0.70 INCH       CASCADE            MT   TRAINED SPOTTER

&&

MPJ

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREAT FALLS MT
547 PM MDT WED MAY 28 2014

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

0543 PM     HAIL             3 SSE RAYNESFORD        47.23N 110.71W
05/28/2014  E0.25 INCH       JUDITH BASIN       MT   TRAINED SPOTTER

&&

MPJ