Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 231118
AFDTFX

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

Updated Aviation Discussion

.DISCUSSION...
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

&&

.AVIATION...
UPDATED 1118Z.
An upper level low with center nearly stationary over SW
Saskatchewan today will continue to circulate moisture into the
region. Area of widespread showers from roughly KCTB to KHVR will
gradually sag southward this morning with showers becoming more
numerous across central and southwest MT and MVFR ceilings and
mountain obscuration becoming increasingly widespread. Decreasing
trend in precipitation and slow improvement to ceilings will begin
this evening. Breezy west winds will become northwesterly today and
eventually decrease this evening. Hoenisch

&&

.HYDROLOGY...
A flood warning continues for Clear Creek. The river has just gone
below flood stage...but with showers moving back into the
region...there is a chance for the creek to go back above flood
stage. Thus we will wait until the morning model runs have been
issued and determine later this morning the appropriate highlight
for this creek.

Otherwise...scattered showers will continue over the region for
the next few days. No new additional flooding is expected at this
time over the next few days as long as rainfall totals generally
remain less than one inch. However...both the GFS/EC are progging
another wet system to affect the region sometime next weekend.
Thus some hydrologic highlights might be needed for portions of
the region and an ESF outlook has been issued to highlight this
event. Brusda

&&

.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 /  60  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.

Flood Warning continues for Clear Creek until further notice.

&&

$$

weather.gov/greatfalls



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