Flooding in Montana, April 3 to 7, 2018

Area Forecast Discussion...UPDATED
National Weather Service Glasgow MT
645 PM MDT Tue Apr 3 2018

.DISCUSSION...

Sent an update this evening to blend the latest model consensus I
could find regarding the chances for some isolated and scattered
snow showers later tonight through our SW zone areas. Expecting up
to around half and inch of new snow there. Otherwise, not much
changed.          BMickelson

Previous discussion: A weak weather disturbance moving through
the ridge with some moisture associated with it is forecast to
bring some isolated to scattered light snow showers to central mt,
perhaps reaching as far north as Petroleum County. Clouds are
forecast to increase from the west after midnight as this weak
system approaches. Another weak system moving SE is forecast to
bring increasing clouds by Wednesday afternoon into extreme
northern counties of north central and northeast Montana. Snow
showers are forecast to increase Wednesday night into Thursday
with the passing of this system. A cold front will drop southward
bringing colder temperatures. Snow showers with this system will
be scattered and are forecast to produce very light snowfall
amounts. High temperatures on Wednesday will warm into the low to
mid 30s north of the Milk and Missouri rivers and upper 30s to low
40s south of the Milk and Missouri rivers. These temperatures
will increase runoff due to snow melt and some rising water levels
on area creeks.

Thursday cooler temperatures can be expected behind the departing
low pressure system. Another reinforcing cold front is forecast to
drop into northeast Montana Thursday night into Friday dropping
max temperatures into the teens and 20s into Friday.

A potent storm system will cross Montana and approach NE Montana
on Saturday. Ahead of the system on Saturday expect warmer day
time high temperatures with increasing chances of showers Saturday
afternoon. A rain snow mix is possible especially for areas from
the Missouri river south with snow showers north of the Missouri
river.

Saturday night into Sunday morning: The main storm system crosses
over NE Montana producing widespread snow with possible snowfall
amounts from 2 to 6 inches with the heaviest snow accumulation
extending from Phillips county eastward across portions of
Roosevelt and Richland counties.

By Monday and into next week eastern Montana will see a pattern
change as the arctic air is pushed to the east and is replaced by
a warmer maritime airmass. A deep low in the eastern Pacific will
continue to shed weaker fast moving weather system across
Montana through the week.

One note worth pointing out with the pattern change to warmer
temperatures next week will be the increased rapid snowmelt and
the possibility of ice jams on creeks and rivers feeding into the
Milk river with jams also along the Milk River possible as well.
So stay tuned for further updates in the weather and hydro
forecasts.

&&

.AVIATION...

Flight category: VFR conditions thru midnight, then possibly
developing some MVFR CIGS west of a Opheim to Glasgow to Jordan
line toward morning.

Synopsis: Sfc high pressure over the region today as high
pressure aloft builds in. A weak weather disturbance moving
through the ridge with some moisture associated with it, is
forecast to bring some isold to sct light snow showers to central
mt, perhaps reaching as far north as Petroleum County. Cigs are
forecast to lower from the west after midnight as this weak system
approaches.

Generally light and variable winds expected thru the forecast
period.              BMickelson

&&

.HYDROLOGY...

Beaver creek in Phillips County: Had received reports yesterday
that Beaver creek was out of its banks near the community of Harb.
The gage at Guston Coulee is malfunctioning at this time.
Spotters had reported that the creek was rising in that area
during the day on Monday. A combination of water that has already
been coming down the Beaver Creek channel and ice in the creek
causing restriction to the increased flow, will continue to result
in elevated creek levels as this water makes its way downstream.
A flood advisory remains in effect for Beaver Creek.

Milk River: There has been some minor movement of the river ice as
some creeks south of the Milk River began observing rising levels
due to last weeks warmer temperatures and melting snow water entering
those basins which caused them to begin flowing down toward the
Milk River. Willow Creek experienced some good melting in its
basin and elevated creek levels in response last week.

Colder temperatures over the past several days has begun to slow
things down with some gage levels along the Milk already going
back down.

One exception is a rise in the Milk River near Tampico, over the
last 36 hours or so.

Warmer temperatures this Wednesday may produce some creek and
river rises. Colder temperatures are forecast for the second half
of this week and through the weekend, so not anticipating too
much of a change to our current hydro conditions. However warming
temperatures next week will likely cause rising creek levels and
some possible ice jams along the Milk River.

To monitor river stage readings, go to our Advanced Hydrologic
Prediction Service (AHPS) page at www.weather.gov/glasgow then
click on "Rivers and Lakes" then "River Observations". Data for
this page are provided by the USGS.

&&

.GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.

&&

weather.gov/glasgow