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Area forecast discussion 
National Weather Service Great Falls Montana
236 PM MDT Tuesday Oct 6 2015


Tonight through Thursday...a dry westerly flow aloft persists over
the region with a weak upper level ridge over the northern
rockies and Montana. Satellite imagery this afternoon shows a plume of
moisture upstream of the region moving into the Pacific northwest with
origins in the central Pacific. An initial shortwave embedded
within this plume of Pacific moisture, currently located near
Vancouver Island, will move east along the US/Canadian border
tonight through Wednesday, flattening the upper level ridge
somewhat, but mainly brining an increase in high level cloud-
cover through Wednesday morning. Additional shortwave energy,
deeper moisture and an upper level jet maximum streams across the
region late Wednesday through early Thursday. Most of the
precipitation associated with the passage of this energy will be
along and west of the Continental Divide with spotty precipitation further
east over central and southwest Montana. By Thursday afternoon...weak
upper level ridging develops for drier conditions. Temperatures
will remain slightly above seasonal averages through Thursday.

Thursday night through Tuesday...not much change with medium range
forecast. The period begins with an upper ridge building over the
area. Moisture moving through the ridge Thursday night will result
in isolated, mainly mountain showers. By Friday, the ridge pushes
further east. The GFS moves short wave energy across southern Canada
and develops isolated showers near Glacier park. An upper trough
approaching the West Coast Saturday begins to break down the ridge
and shifts the flow aloft to a more southwesterly direction. A Lee
side trough develops Saturday afternoon bringing breezy and dry
conditions to the area. The models bring a short wave across the
area Sunday but differ on the timing of this feature with the European model (ecmwf)
being much faster than the GFS. Regardless, both models bring
showers to the Rocky Mountain front and isolated showers to the
adjacent plains. Surface pressure gradient tightens Sunday and winds
will increase and become gusty. Westerly flow aloft Monday will
bring isolated showers to the higher terrain with gusty winds
continuing. Northwest flow aloft returns Tuesday with isolated
showers. Temperatures will be well above seasonal averages Friday
and Saturday but begin to decline on Sunday in the wake of the short
wave passing through the area. Afternoon readings to start the week
will be near seasonal averages.


updated 1741z.
VFR conditions will prevail over the next 24 hours as westerly flow
aloft persists. At the surface...winds will remain light today before
becoming westerly and strengthening by about 05 knots Wednesday morning...
especially at kctb. Jaszka


Preliminary point temps/pops...
gtf 46 65 43 65 / 0 10 20 10
ctb 43 67 43 67 / 0 10 10 10
hln 45 67 49 69 / 0 10 20 10
bzn 39 73 45 68 / 0 10 30 10
wey 28 59 34 58 / 0 10 20 20
dln 40 70 45 67 / 0 10 20 10
hvr 40 69 41 65 / 0 10 10 10
lwt 44 67 43 65 / 0 10 10 10


Tfx watches/warnings/advisories...



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