River Flood Warning 9, NWS Billings, MT

Area Forecast Discussion...Updated
National Weather Service Billings MT
1011 AM MDT Wed May 23 2018

.UPDATE...
Upper low was moving into south central Montana this morning.
Areas of moderate to heavy rainfall was wrapping around the low
over northern and western areas of south central Montana. Rivers
running high, with many reports of an inch or more with this
lates round of rain from overnight through this morning. The east
has dried out and lowered PoPs there. Will have to watch the
southeast closely this afternoon, as clearing has worked in there
with adequate cape. Shear will be borderline, but hail should
certainly be a threat. Heaviest rain will bank over western
locations today with a tapering off affect on the eastern edge.
TWH

&&

.SHORT TERM...valid for Tdy and Thu...

Water vapor imagery shows strong diffluence over the region as
shortwave lifts through central WY, associated with broad upper
low over the intermountain west. Areas of rain since yesterday
evening have been moderate to heavy mostly in our central cwa to
this point. Atmospheric moisture is quite high...see 00z raobs
showing precipitable water of just under an inch at GGW and RAP,
and over an inch at BIS. We've seen reports of 1-2 inches since
Tuesday evening, and Billings has received about a quarter inch of
rain as of this writing. Rain will continue and should become
enhanced as vorticity axis lifts into our cwa early this morning.
This includes our east which has been mostly dry so far but should
see a period of showers/t-storms during the early morning hours.

As shortwave continues to lift northward, a mid level low will
deepen a bit west of Billings. This will result in a westward
shift in the heavier precip. Our western cwa will see anywhere
from 0.50-1.50 inches of rain today. Eastern parts will see
decreasing showers from south to north through the morning. Will
make no changes to the Flood Watch that is in effect for Roundup-
Billings-Sheridan westward.

Other concern today is severe weather across our east. Decreasing
cloud cover after early morning showers will allow for quick
warming and destabilization. Initially, we will see dry slotting
and descent in our far east, but there is an axis of convergence
on NW side of surface trof (i.e. near places like Forsyth and
Miles City) that should allow convection to fire by early-mid
afternoon. By evening, as upper low tracks slowly east and a
weaker wave lifts through eastern WY, there is risk of strong to
severe storms across southeast MT. Hail and wind are the primary
threats with any severe weather today.

Weather will quiet down tonight as trof lifts to the northeast.
We'll see some breezy westerly winds and just isolated coverage
of mainly diurnal showers/t-storms on Thursday. None of the storms
on Thursday will be severe.

Temperatures today will ary quite a bit, ranging from the upper
50s in our far west to lower 80s in our far east. We should see
mid 70s to mid 80s everywhere on Thursday as ridge begins to build
back in, along with the drier west winds. JKL

.LONG TERM...valid for Fri...Sat...Sun...Mon...Tue...

No big changes in the extended. Friday will be the best chance for
a dry day as ridging builds in. By Saturday afternoon the next
trough/cutoff low over the western US will start to influence the
area. Showers and thunderstorms will start to develop over the
mountains during the afternoon and the spread east. More
shortwaves will move through the area through Wednesday. The
biggest concerns with these storms will be the high moisture
content with this system producing heavy rainfall. This will
continue the risk of flooding as rivers will be nearing the peak
of snowmelt runoff season.

Please monitor water.weather.gov for the latest on our streams
into early next week. The main spring runoff will likely be upon
us later this week through the holiday weekend and will need to be
closely monitored for potential flooding. Reimer

&&

.AVIATION...

Showers and thunderstorms will create MVFR to localized IFR
conditions west of a line from Roundup to Billings to Red Lodge,
with many VFR weather east of that line. Storms will have locally
heavy rain. Scattered thundestorms will develop over southeast
Montana this afternoon and evening, with a few strong storms (some
hail and strong winds) possible. TWH

&&

.PRELIMINARY POINT TEMP/POPS...

    Tdy Thu     Fri     Sat     Sun     Mon     Tue
-------------------------------------------------------
BIL 066 053/081 055/086 056/087 056/080 056/077 055/077
    +/T 42/T    11/U    12/T    23/T    55/T    54/T
LVM 058 048/077 049/082 050/082 051/074 051/072 050/074
    +/T 63/T    22/T    12/T    36/T    65/T    44/T
HDN 072 051/083 054/088 057/091 057/083 057/081 055/080
    8/T 42/T    11/U    11/U    23/T    55/T    54/T
MLS 078 056/080 058/087 060/090 061/085 061/083 060/081
    6/T 52/T    10/U    00/U    33/T    54/T    53/T
4BQ 081 054/080 057/086 058/090 060/085 059/082 057/079
    2/T 31/B    11/U    00/U    14/T    55/T    54/T
BHK 080 054/077 055/084 056/088 058/084 058/081 056/078
    4/T 41/B    10/U    01/U    23/T    44/T    54/T
SHR 075 050/079 052/083 053/087 055/079 053/077 051/075
    3/T 42/T    21/U    11/U    24/T    56/T    54/T

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...Flood Watch in effect through late tonight FOR ZONES
      28-29-34-35-38>42-56-57-63>68.
WY...Flood Watch in effect through late tonight FOR ZONES 98-99.

&&

weather.gov/billings

Hazardous Weather Outlook
National Weather Service Billings MT
317 AM MDT Wed May 23 2018

MTZ030>041-056>058-064>068-WYZ098-099-231030-
Treasure-Northern Rosebud-Custer-Fallon-Northern Stillwater-
Yellowstone-Powder River-Carter-Southern Big Horn-Eastern Carbon-
Northern Park-Northern Sweet Grass-Red Lodge Foothills-
Northern Big Horn-Southern Rosebud-Paradise Valley-Livingston Area-
Beartooth Foothills-Absaroka/Beartooth Mountains-Crazy Mountains-
Northeast Bighorn Mountains-Sheridan Foothills-
317 AM MDT Wed May 23 2018

This Hazardous Weather Outlook is for portions of south central
Montana...southeast Montana and north central Wyoming.

* WHAT...Showers and thunderstorms, with potential for heavy
  rainfall and a few severe thunderstorms.

* WHERE...Southern Montana and northern Wyoming.

* WHEN...Today.

* ADDITIONAL DETAILS...A few severe thunderstorms capable of
  producing large hail and strong winds are possible from Hysham to
  Lame Deer eastward this afternoon and evening.

* ADDITIONAL HAZARD CONCERNS...Showers and thunderstorms will
  produce areas of heavy rainfall. Some rivers and streams could
  see aggressive rises from this rainfall. Localized low land
  flooding is possible as well.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Hazardous Weather Outlook is issued when hazardous weather could
impact the region within the next week. Be sure to stay tuned for
future updates as locations, timing, and impacts could change.
Begin preparations to mitigate any impacts that could result from
the hazardous weather.

&&

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PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BILLINGS MT
958 AM MDT WED MAY 23 2018

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

0600 AM     HEAVY RAIN       1 NW COLUMBUS           45.64N 109.27W
05/23/2018  M1.61 INCH       STILLWATER         MT   CO-OP OBSERVER

0630 AM     HEAVY RAIN       N REED POINT            45.71N 109.54W
05/23/2018  M4.10 INCH       STILLWATER         MT   PUBLIC

0700 AM     HEAVY RAIN       3 NE FROMBERG           45.42N 108.87W
05/23/2018  M1.39 INCH       CARBON             MT   COCORAHS

0700 AM     HEAVY RAIN       2 WNW JOLIET            45.50N 109.01W
05/23/2018  M3.11 INCH       CARBON             MT   COCORAHS

0700 AM     HEAVY RAIN       8 E COLUMBUS            45.62N 109.10W
05/23/2018  M1.79 INCH       STILLWATER         MT   COCORAHS

0700 AM     HEAVY RAIN       6 SSW MOLT              45.78N 108.97W
05/23/2018  M1.25 INCH       STILLWATER         MT   CO-OP OBSERVER

0700 AM     HEAVY RAIN       5 N RED LODGE           45.19N 109.25W
05/23/2018  M2.00 INCH       CARBON             MT   TRAINED SPOTTER

0700 AM     HEAVY RAIN       4 N RED LODGE           45.26N 109.23W
05/23/2018  M1.38 INCH       CARBON             MT   COCORAHS

0700 AM     HEAVY RAIN       3 NE RED LODGE          45.22N 109.22W
05/23/2018  M1.59 INCH       CARBON             MT   COCORAHS

0700 AM     HEAVY RAIN       7 E COLUMBUS            45.62N 109.10W
05/23/2018  M1.40 INCH       STILLWATER         MT   COCORAHS

0700 AM     HEAVY RAIN       1 ENE FORT SMITH        45.31N 107.92W
05/23/2018  M1.00 INCH       BIG HORN           MT   COCORAHS

0700 AM     HEAVY RAIN       2 WSW JOLIET            45.47N 109.01W
05/23/2018  M1.70 INCH       CARBON             MT   CO-OP OBSERVER

0700 AM     HEAVY RAIN       2 W STORY               44.58N 106.93W
05/23/2018  M1.06 INCH       SHERIDAN           WY   COCORAHS

0736 AM     HEAVY RAIN       5 WSW BILLINGS          45.76N 108.61W
05/23/2018  M1.00 INCH       YELLOWSTONE        MT   COCORAHS

0743 AM     HEAVY RAIN       5 S BILLINGS            45.72N 108.52W
05/23/2018  M1.24 INCH       YELLOWSTONE        MT   COCORAHS

0747 AM     HEAVY RAIN       2 SSE BILLINGS          45.76N 108.52W
05/23/2018  M1.05 INCH       YELLOWSTONE        MT   TRAINED SPOTTER

0800 AM     HEAVY RAIN       7 SW BILLINGS           45.71N 108.65W
05/23/2018  M1.06 INCH       YELLOWSTONE        MT   COCORAHS

0800 AM     HEAVY RAIN       3 SW RED LODGE          45.16N 109.29W
05/23/2018  M1.62 INCH       CARBON             MT   COCORAHS

0800 AM     HEAVY RAIN       RAPELJE                 45.97N 109.25W
05/23/2018  M1.03 INCH       STILLWATER         MT   CO-OP OBSERVER

0800 AM     HEAVY RAIN       6 WSW RED LODGE         45.16N 109.36W
05/23/2018  M1.15 INCH       CARBON             MT   MESONET

0800 AM     HEAVY RAIN       6 SSE COLUMBUS          45.55N 109.22W
05/23/2018  M3.14 INCH       STILLWATER         MT   COCORAHS

0800 AM     HEAVY RAIN       16 S SHERIDAN           44.57N 106.93W
05/23/2018  M1.46 INCH       SHERIDAN           WY   COCORAHS

0800 AM     HEAVY RAIN       13 SSW GREYCLIFF        45.58N 109.85W
05/23/2018  M1.53 INCH       SWEET GRASS        MT   MESONET

0800 AM     HEAVY RAIN       1 S ABSAROKEE           45.52N 109.45W
05/23/2018  M1.61 INCH       STILLWATER         MT   COCORAHS

0800 AM     HEAVY RAIN       6 S LOCKWOOD            45.73N 108.40W
05/23/2018  M1.28 INCH       YELLOWSTONE        MT   MESONET

0800 AM     HEAVY RAIN       1 NNW PRYOR             45.43N 108.54W
05/23/2018  M1.05 INCH       BIG HORN           MT   CO-OP OBSERVER

0802 AM     HEAVY RAIN       4 WSW BILLINGS          45.76N 108.61W
05/23/2018  M1.08 INCH       YELLOWSTONE        MT   COCORAHS

0900 AM     HEAVY RAIN       1 SE BILLINGS           45.77N 108.48W
05/23/2018  M1.10 INCH       YELLOWSTONE        MT   CO-OP OBSERVER

0930 AM     HEAVY RAIN       1 S RED LODGE           45.18N 109.26W
05/23/2018  M2.07 INCH       CARBON             MT   CO-OP OBSERVER

&&

LD