Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 212104
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
304 PM MDT Fri Apr 21 2017

.DISCUSSION...

Rest of Today through Saturday Night...Latest water vapor imagery
shows a weak mid-level low over central/southwestern at this time.
Lift and convergence within this low is keeping areas of generally
light rain/snow going across part of the area at this time. However,
there has been a noticeable decrease in the coverage of precip over
the past several hours and this trend should continue as the mid
level low shifts SE tonight. In its wake, high pressure will build
in at the surface with decreasing winds. With lingering moisture and
light winds tonight, the main concern will be low clouds/fog. Low
clouds may tend to limit fog development, but any area that clears
out could see patchy dense fog quickly develop with visibility
reduced to less than a mile at times, especially from Midnight
through early Saturday morning and primarily in areas that saw
heavier precip amounts over the past 24-36 hrs. For now, we`ll hold
off any dense fog products, but this will be closely monitored
tonight. In the mountains, additional very light snow accumulations
are likely through early this evening, but significant impacts are
not expected. Martin

Sunday through Friday...Overall an unsettled weather pattern will
reside over the region through much of next week. Precipitation
chances will increase once again on Sunday/Monday as the next
upper level disturbance moves across the Intermountain West. For
Tuesday and Wednesday, a stronger upper level disturbance will
move through the region during the afternoon hours on both days,
resulting in a fairly good chance for scattered showers,
especially over Southwest MT. During the overnight hours, the rain
could change to snow, especially for elevations above 5500 feet.
For Thursday and Friday, an upper level trof will still be over
the region. The chances for precipitation will be lower, but can`t
be ruled out at this point. In terms of temperatures, generally
seasonable to slightly below normal afternoon temperatures are
expected through the week. Brusda/Moldan

&&

.AVIATION...
Updated 1822Z.

-SHRA will continue to impact much of the forecast area,
especially KCTB/KGTF/KHLN/KBZN, and will be accompanied by mtn
obscurations and, at times, MVFR conditions. Shower activity
should gradually diminish this evening. However, lingering low
level moisture will likely lead to lower CIGS/VIS in stratus/fog.
If any terminal sees less cloudcover tonight than currently
anticipated, VIS could be much lower than currently advertised in
the TAFS and this will be closely monitored through the night.
Martin

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  32  61  38  56 /  40  10  10  60
CTB  28  57  38  56 /  20   0  20  40
HLN  32  62  40  58 /  20   0  10  50
BZN  30  61  37  58 /  30  10  10  50
WEY  21  49  29  50 /  20  10  10  40
DLN  29  58  39  57 /  10   0  10  50
HVR  33  58  38  58 /  30  10  10  50
LWT  32  56  38  57 /  50  20  10  60

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

weather.gov/greatfalls



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