Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 210301

900 PM MDT Sun Jul 20 2014

Current satellite imagery and webcams show mix of mostly clear
(central counties)to partly/mostly cloudy skies (Hiline and
southwest MT areas) across the region this evening.  Also, band of
very light rainshowers continue to pass through portions of the
Hiline. Little precipitation has been recorded so far but dew points
and humidity values have been creeping upward so may see some light
rainfall there through this evening.  Very spotty showers have also
developed over southwest MT; expect precipitation chances and
coverage to increase in that area thru the nighttime hours as
additional moisture currently over southern ID is steadily advancing
northward.  Predominant precip type should be rainshowers but can`t
rule out a few short-lived, pulse-type thunderstorms over both of
these areas. Going forecast is largely on track.  Just made a few
minor tweaks on temperatures and humidities to better match current
observations and raised precip chances slightly over the southwest
counties based on latest forecast model projections for the moisture
in Idaho.


/ISSUED 220 PM MDT Sun Jul 20 2014/
Tonight through Tuesday...Southwesterly flow will bring a few
disturbances to Montana over the next couple days. Isolated to
scattered showers and thunderstorms may develop near elevated
terrain during peak heating. Temperatures are expected to remain
near seasonal averages with gusty winds diminishing into Monday.
Smoke from fires in the Pacific Northwest has moved into southern
Canada but may return to the region Monday.

Tuesday night through Sunday...Not many significant changes to the
medium range period. The period begins with the upper ridge axis
over eastern Montana and southwest flow aloft continuing to bring
moisture and instability to the area, resulting in scattered
thunderstorms Tuesday night. Wednesday will find a closed upper
low approaching the Pacific Northwest with increasing diffluent
flow aloft over the area. Short wave energy spinning out from the
low and associated trof will aid in thunderstorm development
across the area Wednesday afternoon through evening. The models
are fairly consistent placing the upper low over southern Alberta
by Thursday. The ECMWF has the low further north than either the
GFS or the GEM. Regardless, none of the models have much in the
way of qpf associated with this feature, mainly isolated
convective activity across the northeast. With the low moving east
into Saskatchewan Friday, the flow aloft becomes westerly once
again and the airmass begins to dry. Upper ridging over the area
during the weekend brings dry condition, though some moisture
works its way north from the southwest U.S. Sunday and brings a
chance of isolated thunderstorms over the southwest mountains.
Temperatures will be above seasonal averages to start the period
but will drop below seasonal averages from midweek through the


Primary aviation concern...increasing chances for showers and
thunderstorms by around 10z tomorrow, especially over southwest
MT. Have continued mention of VCSH for most terminals but wouldn`t
be surprised to see brief MVFR conditions in heavier
showers/isolated thunderstorms. Could see showers off and on
during the morning hours with drier conditions expected by late
afternoon. Winds gusts will continue to subside this evening and
will become light and variable overnight. Foltz


GTF  58  82  56  84 /  10  40  20  30
CTB  53  78  50  81 /  20  30  10  30
HLN  61  82  59  86 /  10  50  40  30
BZN  56  80  53  86 /  20  60  50  20
WEY  46  69  40  78 /  30  70  50  20
DLN  57  78  52  82 /  20  60  40  30
HVR  57  84  54  87 /  30  30  10  20
LWT  56  81  55  85 /  20  40  40  20



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