Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 231741
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
1141 AM MDT MON MAY 23 2016

...Aviation Section Updated...

.DISCUSSION...

TODAY...

The region will continue under the influence of a low pressure
trof today. Although this will keep scattered showers in the
forecast, overall precipitation amounts will remain low. Updated
to freshen POPs, WX, and QPF. Also, the Flood Warning for Clear
Creek was canceled. Zelzer

&&

.AVIATION...
UPDATED 1741Z.

Latest water vapor loop shows an upper level low drifting slowly
eastward across southern Saskatchewan at this time. Low/mid level
moisture continues to pinwheel around it across our forecast area.
Within this regime, scattered showers will continue to move slowly
E/SE through this evening before a gradual decrease in coverage
occurs. Some models bring additional showers into the area again
Tuesday morning, but confidence in the location/occurrence of the
next round of showers is more uncertain at this time. Through this
evening, lower cigs/mtn obscurations can be expected. CIGS may lift
some across SW MT by Tuesday morning, but are expected to remain
lower across central MT. Instability today should be confined to far
SW MT with KBZN have the best chance of seeing a thunderstorm. Even
there, though, confidence was too low to include in the TAF for now.
Martin

&&

.HYDROLOGY...
Scattered showers will continue over the region for the next few
days. No new additional flooding is expected at this time as
rainfall totals generally remain less than one inch.
However...models suggest another wet system will affect the region
next weekend. Thus some hydrologic highlights might be needed for
portions of the region and an Hydrologic Outlook has been issued
to highlight this event.

&&

.PREV DISCUSSION...
/ISSUED /
Today through Wednesday...A cut off upper level low will continue
to spin over Southern Alberta today...and generally reside over
this region over the next few days as well. As a
result...moisture will pin-wheel around this upper level low over
the next few days. Thus there is a chance for precipitation
through the entire short term period...with North Central MT
having the highest chances for rainfall today and Southwest MT
having the highest chances on Wednesday. Overall precipitation
amounts will generally be on the light side most days...with
locations under the steadier rainfall receiving about 0.10 to 0.20
inches of rainfall. There will be some breaks in the precipitation
at times...especially along the I-15 corridor from Great Falls to
Cut Bank where gusty downslope winds will continue. These
downslope winds will limit the precip a bit in this region. In
terms of temperatures...expect below normal afternoon temperatures
through Wednesday. Temperatures will be the coolest today...with
temperatures becoming a touch warmer each day for Tue and Wed.

For the winter weather advisory over the Rocky Mountain
Front...snow will continue over the mountains...generally above
5000 feet through today. The GFS/EC model continue the snowfall
through tonight...and there is the potential the winter weather
advisory could be extended later this morning. The morning shift
will look at this closer when the 12z runs come. Brusda

Wednesday night through Memorial Day...A broad upper level trough
remains in place across western N America late this week through
the upcoming weekend. Initially, only weak shortwave energy moving
through a NW to W flow aloft Wednesday night through Thursday will
bring a chance of mainly afternoon and evening convective
precipitation with temperatures near seasonal averages Thursday.
Friday through the upcoming holiday weekend, models are in large
scale agreement to bring an upper level low south from the Gulf of
AK into the PAcific NW and gradually have this system edge east
toward the Northern Rockies late this weekend into early next
week. In general, this will bring increasing precipitation chances
to the region and somewhat cooler temperatures as the flow aloft
becomes southerly Friday and Saturday and likely continues through
much of the upcoming weekend as the upper low approaches.
Differences in smaller scale details however increase through the
upcoming weekend as the GFS keeps the upper low center farther
west over the Pacific NW through much of the weekend while the
ECMWF and CMC models take the system into northern Rockies/across
MT respectively much earlier in the weekend. Hoenisch

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  54  39  59  41 /  60  20  40  20
CTB  49  37  57  39 /  70  30  20  30
HLN  56  41  60  43 /  50  20  40  30
BZN  56  37  61  41 /  40  30  30  30
WEY  49  31  52  34 /  40  30  40  40
DLN  56  37  58  39 /  40  20  40  40
HVR  55  42  60  41 /  50  20  30  20
LWT  55  39  59  41 /  40  20  40  20

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until noon MDT today for MTZ009-048.

&&

$$

weather.gov/greatfalls


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