Area Forecast Discussion
Issued by NWS Glasgow, MT
FXUS65 KGGW 300206
Area Forecast Discussion
National Weather Service GLASGOW MT
806 PM MDT FRI JUL 29 2016
.SHORT TERM...for northeast Montana...tonight through Sun...
Changes to the forecast this evening actually focused more on the
forecast for late tomorrow afternoon. A weak disturbance is
anticipated to drop out of Canada and clip the far northwestern
corridoor of the CWA before dissipating near sundown. This will
generate a few isolated showers during the afternoon. GAH
PREVIOUS SHORT TERM DISCUSSION:
Isolated to scattered showers with some thunder occurred today
across the CWA. Instability has been best this afternoon over the
western zones according to the LAPS. Some mesoscale models are
showing convection to drop SE out of SW Sask this afternoon and
into the western zones. Otherwise, loss of diurnal heating early
this evening will kill any convection quickly this evening.
Upper pattern showing a northwest flow over the area that will
become zonal Saturday as an upper low drops into western Canada.
This upper low will drift into the Prairie provinces Sunday
creating a diffluent southwest flow over NE Montana.
Mainly clear skies tonight through Sunday morning can be expected
with a warmup. 850 mb temperatures will reach the 20s*C late
Saturday through Sunday.
Sunday afternoon will be a mystery to solve as the models
continue their differences. The GFS is benign while other models
develop thunderstorms over the eastern zones. Based on what
happened today with the GFS, the wetter/more unstable solution
seems better. Cannot quite nail down severe potential at this
point, therefore will continue to monitor. TFJ
.LONG TERM...Sun night through Fri...
With a persistent jet stream from southern Oregon through North
Dakota through the beginning of next week, continued moisture from
the Pacific Ocean will stream across our region. The best model
agreement shows the best chances for precipitation through the
area from Tuesday afternoon through Wednesday morning as an
organized compact low pressure system emerges over the continental
divide. Generally expecting an otherwise quiet weather pattern
aside from the Tuesday/Wednesday system. BMickelson
Previous long term discussion:
Weak westerly flow with embedded shortwaves sliding along the
Canadian border continues through next week. This will result in
the occasional thunderstorm and generally mild temperatures.
Heights lower on Monday with the passage of an upper wave through
the Canadian prairies before another thermal ridge pushes into the
Treasure state on Tuesday. Another shortwave trof pushes through
the region midweek. Models in better agreement with pulling the
wave south of the border and bringing better moisture into the
state to produce thunderstorms with the frontal passage Tuesday
night into Wednesday morning.
Cooler weather follows behind this midweek trof before ridge
begins to rebound over Montana for the end of the week. Ebert
VFR conditions are expected through the TAF period. However,
increasing clouds are expected late Saturday afternoon and evening
as a subtle upper level disturbance approaches. This may also
bring in an isolated shower or thunderstorm, particularly near the
KGGW taf site. Winds are expected to be light from the southeast
overnight before increasing from the south on Saturday at 5 to 10