Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Glasgow Montana
728 PM MDT Sat Mar 15 2014
Short term...for northeast Montana...tonight through Monday...
update... sky cover seem to be more cloudy than expected therefore
minor adjustment to the forecast to increase cloudiness for the
evening hours. Otherwise all other elements on track. Proton
Tonight through Sunday...upper ridging will build in from the
west making for dry conditions and a warming trend. Tonight will
bring partial clearing which will allow for decent radiational
cooling. Still a bit tough to say how lingering snowfall from last
nights system will impact temperatures...but held with the thought of
cooler temperatures for areas which saw snow accumulations. Sunday brings
strong warm air advection which will make for temperatures pushing 60
degrees at most locations. Sunday afternoon does look a bit breezy
as low level instability allows stronger westerly winds aloft to
mix down. Gilchrist
Sunday night through Monday...large ridge across the area will
exit to the southeast as a large trough over Pacific northwest
moves in. Near the surface a warm frontal boundary will form up
across the northern half of the County Warning Area and become a Focal Point for
precipitation while warm temperatures fill in behind it to the
south. Dominant precipitation type will be rain for these periods. By middle
day Monday the trough will arrive and spin up a surface low over
the western half of the state and trek it across Montana through
the early afternoon hours. A cold front will firm up behind it
during the late afternoon along with intensifying showers.
Long term...Monday night through Saturday...
Monday night through Tuesday... pcnw trough will move into the
area with deepening cold air as a larger ridge develops over the
coasts of British Columbia and the pcnw. From about 6pm to
midnight rainfall will briefly intensify behind the surface low as
a transition from rain to snow begins. However after midnight the
bulk of precipitation is anticipated to begin exiting the area as
snow completely fills in. So... snow totals will be low for the
event. During the day Wednesday lingering snow and rain shower
will be possible but light in the cooler drier air. Gah
Temperatures for Wednesday and Thursday will be warmer as the
upper ridge axis tracks east over The Rockies. A longwave trough
will push onshore during this time... latch onto the Lee side
trough Thursday morning and move through eastern Montana Thursday
afternoon through Friday morning. Confidence for measurable
precipitation with this system is fairly high but the quantity and
placement remains uncertain. Probability of precipitation were increased across the County Warning Area
for Thursday through Friday however the rest of the forecast had
minimal or no changes made. Aec
previous long term discussion...
in general...synoptically speaking...the extended forecast period
is dominated by a cyclic and progressively strong upper-level
weather pattern of alternating troughs and ridges throughout. Each
passing trough seems to be on a similar trajectory from the west-northwest
toward the east-southeast through the region at large.
For northeast Montana...this will largely translate into
alternating short periods of dry and wet...somewhat more of a
General synoptic model agreement holds tight through most of the
forecast period...which was not the case over the last few days.
Consequently...forecast confidence has increase significantly
regarding the extended forecast period.
It is still a bit tricky this time of year with precipitation type due to
freezing temperatures each night. Overcast skies will keep
temperatures from becoming too cold with each storm...but could
still drop cold enough for a rain and snow mix after the midnight
period of any storm system.
Monday night...models in excellent agreement showing a departing
storm system with moderate to heavy rain across our southern zones
in connection with a strong upper level trough sweeping through
Tuesday through Wednesday...a general northwest flow aloft sets up
with a few subtle shortwaves resulting in some nuisance showers.
Thursday morning through Friday night...the next wet and active
storm system passes through the area. Precipitation amounts are a bit less
certain this far out so chose to broadbrush the grids a bit here.
synopsis: mostly improving conditions will continue to build in
behind an exiting low pressure system through tonight. However low
clouds may linger. Sunday afternoon will be breezy as low level
instability allows gusty winds aloft to mix down to the surface.
Cigs: broken MVFR clouds tonight. Expect a broken middle level deck Sunday
Winds: southerly 8-12kts. Winds then going westerly around midday
Sunday and increasing to 15 to 25 kts...with gusts to around
Area rivers will continue to be monitored for Spring season
responses over the next several days and weeks from recent snow
melt...additional storms...and a few more potential ice jams.
The milk river continues to slowly rise. The Glasgow gage is at
20.95 feet and flood stage there is 25.0 feet.
Frenchman creek at the Canadian border northeast of Whitewater
appears to have crested on Friday afternoon...but is holding nearly
steady at 10.34 feet. Flood stage there is 12.0 feet.
High water continues to flow all along the Poplar River system
and it may see increased rises by Sunday in response to the accumulating
precipitation expected there this weekend.