Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Glasgow Montana
742 PM MDT sun Mar 29 2015
Short term...for northeast Montana...tonight through Tuesday...
the inherited forecast stands with only a few minor adjustments to
winds and sky cover to bring current with recent trends and
observations. Expect partly cloudy sky conditions with light west
winds as temperatures fall through the middle and upper 30s to lower
40s in a few of the usual warmer locations. Concerns are growing
for a period of showers and perhaps a thunderstorm Tuesday before
very gusty winds impact the region Tuesday night and Wednesday.
More information will be provided with the release of the morning
Current conditions across northeast Montana are
pleasant...slightly warm...slightly cool and a bit breezy with
mostly sunny to partly cloudy skies under a weak upper-level
ridge. Surface boundary is easily drying out after a widespread
wetting rain from last night. Widespread fog is not expected
tonight...but some isolated areas of mist and River Valley patchy
fog may be possible from midnight tonight to sunrise Monday
Tonight through Tuesday mid-day...expect warming temperatures
under a strengthening upper-level ridge with partly cloudy to
sunny skies and winds generally below 15 miles per hour. In other
words...Monday and Tuesday will be just about perfect for this
time of year.
By Tuesday afternoon...a large upper-level trough from the Gulf of
Alaska to the northern rockies will turn the flow over northeast
Montana from westerly to southwesterly and allow a few showers and
isolated thunderstorms to form over central Montana and drift over
our western zones. Rain showers are expected to increase in
coverage and precipitation amounts beginning Tuesday evening as a the
leading edge of a cold front passes through the area. Bmickelson
Long term...Tuesday night through Sunday...
tweaks were made to the early portion. Windy conditions are expected
Wednesday but wrap-around moisture and cold air will give snow to
areas just northeast of the County Warning Area Wednesday night. Models seem to be
advertising a cut-off low rather than an upper trough digging into
the Pacific northwest next weekend. This would give NE Montana a better chance of
mild conditions while the Pacific northwest gets much needed moisture/snow. Tfj
the latest 12z model guidance continues with a cold front Tuesday
night reaching northeast Montana. A surface low and closed upper
low will track north of the region across southern Saskatchewan.
This will act to greatly enhance the surface pressure gradient
across the County Warning Area. Thus...while shower and possibly thunderstorm
activity can be expected Tuesday night and Wednesday...the larger
concern looks to surround gusty westerly wind potential.
Decent cold air advection behind the cold front along with this tight pressure
gradient will likely mean business. Latest guidance is pointing to
sustained wind speeds in the 20-30 miles per hour with gusts in the 40-50 miles per hour
range. In time this could easily become a strongly worded lake
Wind Advisory situation...and will have to watch the usual windy
locations for high wind. This is several days out from now and
with several factors involved confidence is not yet there on
that...but if nothing else expect very gusty conditions Tuesday
night and Wednesday across northeast Montana. As this event enters
the day 3 period...would like to inspect more closely lapse
rates...among other parameters...available in the NAM BUFKIT
forecast soundings across the region to ascertain more detail.
After a couple of days...some mesoscale guidance will be able to
also offer some input as to what to expect.
Northwest flow aloft in advance of a Pacific shortwave ridge will
become established across the northern High Plains in the wake of
the Tuesday night/Wednesday system. Embedded in this flow will be
shortwaves...somewhat difficult to time given increasing spread in
the 500mb height ensembles this far out in the extended period.
Nevertheless this pattern supports near climatology probability of precipitation with a daytime
slight chance of rain showers and nocturnal rain/snow mix with
cooler thermal profiles at night.
While precise timing is difficult to pin down...12z European model (ecmwf)/GFS have
broad consensus on having a Pacific Ridge translate east across
Montana which would lead to drier conditions and moderating
temperatures. Given this information...will have a dry forecast to
finish out the long range period...for now. Maliawco
synopsis: ridging will build back into the region over the next 24
Flight category: VFR.
Wind: less than 15 kts across the region.