Scientific Forecaster Discussion
fxus65 kggw 221950
Area forecast discussion
National Weather Service Glasgow Montana
150 PM MDT Wed Mar 22 2017
Short term...for northeast Montana...tonight through Fri...
Synoptic setup: short term begins with a large ridge over the
western half of the US running from the New Mexico through
eastern Montana and up into central Saskatchewan. To the east a
highly amplified trough of equal size runs from off the coast of
British Columbia to off the coast of Southern California. These
two large airmasses have creates southern to southwestern flow
running from Southern California to western Montana.
This afternoon and evening: ridge will exit out of the area with a
warm front moving across at the surface. This will exit most of
the rain showers from the eastern side of the state by the late
Thursday morning through the afternoon: flow will transition to
the southwest during this time. The base of the trough off the
coast of California will move inland and beginning transversing
the Desert Southwest. This will take the bulk of the energy for
lift and leave it well south of the County Warning Area. However, just enough
Pacific moisture may be able to make it up to impact southern
Montana with rain showers. A few of these may be able to spill
into the far southeast corners of the County Warning Area over the Yellowstone
valley before dying off. Total should be minimal with maybe a
couple hundredths for those areas impacted. Gah
Thursday night and friday: a return upper level ridge pattern
across the area will bring dry weather conditions to northeast
Montana along with mild to warm temperatures. Highs will reach the
50s for most places and some 60s in the southwest zones. Maliawco
Long term...Fri night through Wed...
The long term forecast as described below remains on track. The
only changes were to trend toward latest 12z consensus model
blends. Expect a shortwave trough to pass through the region over
the weekend with some scattered showers associated with that
system along a surface cold front. Models continue spread into
next week but overall expect continued chances for precipitation
with somewhat cooler temperatures. Maliawco
Previous long term discussion:
the extended forecast begins Friday evening with northeast
Montana located under an upper level ridge, with cut-off low
spinning across the Southern Plains. There will be a Pacific
trough that will come onshore and cross The Divide Saturday
evening. Models remain unclear with the timing. But after a mild
Saturday morning, the front should move across the area Sunday
afternoon or evening.
The trough then moves across the area Sunday. Besides timing,
models are unclear about quantitative precipitation forecast amounts also. The GFS creates a more
structured storm with a surface low parked over eastern Montana.
The inverted trough in place when the cold front pushes through
could generate moderate rain through Sunday. The ec remains mostly
dry for this period.
The timing of the next trough is even more out of tune between the
GFS and the ec. The best that can be said is there is a cooler and
wetter trough pattern in store for next week.
Went with a broad brush blend of models until models align.
flight cat: VFR
Synopsis: a warm front has rapidly moved across the northeast
Montana is about to exit for ND as of this afternoon. A few high
clouds are moving in behind it. There is an isolate chance for
rain showers at kgdv Thursday morning but chances are too low to
include in the tafs.
Wind: southeasterly at 10 to 15 kts, backing around to the west
behind the front this afternoon. Calming to light and variable
overnight. Then switching to the west to northwest at around 10
to 15 kts Thursday.
the big Muddy Creek in Sheridan County continues to drop further
below minor flood stage this afternoon. However, reports from law
enforcement indicate continued running water over area roadways.
In addition, there is concern with warmer temperatures that levels
could rise again. In order to gain additional confidence in the
downward trend, and to allow further time for running water to
continue to recede on local roadways, the Flood Warning was
extended for an additional day. The milk river at Dodson also
continues to rise as a result of higher river levels upstream.
Expect this to lead to rises at Glasgow in the coming days. These
conditions will need further monitoring into next week. Maliawco