Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 230240
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
840 PM MDT Wed Mar 22 2017

.UPDATE...

Updated forecast has been sent. Made very minor changes to sky
cover and PoPs. A weak wave currently over Washington and Oregon
will move east northeast during the overnight hours, which will
bring increasing cloudiness and scattered rain/snow showers to
the Continental Divide and higher elevations across Southwest and
Central Montana. An isolated shower straying as far east as the
I-15 corridor across North Central Montana is also not totally out
of the question. Winds will gradually decrease throughout the
night, but begin increasing once again tomorrow morning between
8am-11am. Should the boundary layer mix during the night (which
current BUFKIT sounding are not depicting), breezy conditions
would occur due to decent cross barrier flow across the Northern
Rocky Front. - Moldan


&&

.AVIATION...
Updated 0015z.

Southwest flow aloft will bring clouds and isolated showers around
KBZN/KEKS this evening. Otherwise conditions should be VFR except
for local mountain obscurations. Winds will be gusty in the KCTB
area on Thursday. db

&&

.HYDROLOGY...
300 PM Update.

Ice jam on the Big hole river was reported to have released last
night with flood waters having receded today and several surges
observed at gages downstream along the Big Hole and Jefferson
Rivers. Lodge creek north of Havre remains above flood stage but
continues to fall, however with some snow still evident on satellite
imagery upstream south of the Cypress Hills, minor flooding will
continue for a bit longer and the flood warning for this area
continues until river levels lower below flood stage, likely on
Thursday or Friday. Milk river at Harlem continues to fluctuate
right around the minor flood stage level. With the exception of
Lodge creek, most tributaries of the Milk River upstream of this
area have decreased so a decline in river level is expected later
tonight or tomorrow, however for now minor flooding continues and
the flood warning for the Milk River at Harlem has been extended
through tonight. Hoenisch

&&

.PREV DISCUSSION...
/ISSUED 615 PM MDT Wed Mar 22 2017/

Tonight through Friday...Overall a fairly quiet short term
forecast today. Daytime heating with a weak upper cold front is
currently bringing some weak instability across portions of the CWA.
A few isolated to widely scattered showers and thunderstorms are
possible until sunset with the best chances coming across the
southwest. Widespread thunderstorms...and especially strong
thunderstorms...are not expected as shear values are likely to
high for the weak instability that is available. Other than a few
mountain rain and snow showers...dry conditions are then expected
for the remainder of the area tonight. Breezy winds found this
afternoon should diminish later this evening. A large upper low
still skirts to our south Thursday. The brunt of the precipitation
with this system will be out of our CWA...however...there are
still some chances for rain and snow above 6000 feet in the
deformation zone across southwest MT. Little impacts are expected
for either rain or snow showers...and mainly dry conditions are
expected for the remainder of the area on Thursday. High pressure
ridge and dry air then end precip chances and bring clearing skies
Thursday night. Friday then looks to be mainly dry with breezy
south to southwest winds. As the ridge breaks down later
Friday...a few mountain showers are possible across the west.
Temperatures will be slightly cooler tomorrow behind today`s weak
front...then warm back into the 60s for Friday. And with dryer air
moving in...the recent fog concerns we have had should
diminish...with little fog expected to return during the short
term period. Anglin

Friday Night through Wednesday...A large scale, but weakening
Pacific trough moves inland Friday night. Orographic precipitation
is likely to develop up to the Continental Divide by Saturday
morning, with snow levels dropping below about 6000 ft. Several
smaller shortwaves will move through this unsettled west-southwest
flow. Models are converging on a solution that would favor rain and
mountain snow across Southwest Montana Saturday afternoon. Some
solutions are wetter than others, but ensemble averages support
around one-tenth to one-quarter inch of liquid QPF and 2-4 inches of
snow above 7500 feet. Fair weather returns for Sunday as an upper
level ridge axis amplifies and crosses the state.  The overall
pattern remains progressive, with another large scale Pacific trough
spreading moisture across the intermountain west Monday or Tuesday.
Model solutions diverge widely late in the period, though favoring a
return to fair weather for Wednesday. Temperatures remain slightly
above average through the period. PN

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  35  54  32  64 /  10  10   0   0
CTB  34  50  27  56 /  10  10   0  10
HLN  35  53  31  61 /  10  10   0  10
BZN  33  52  29  58 /  20  20  10   0
WEY  27  40  19  42 /  20  30  20  10
DLN  32  51  29  55 /  10  20  20  10
HVR  36  57  28  62 /  10  10   0   0
LWT  35  51  30  59 /  10  20  10   0

&&

.TFX WATCHES/WARNINGS/ADVISORIES...

Flood Warning remains in effect until further notice for the Milk
River near Harlem in Blaine County.

Flood Warning remains in effect until further notice for Lodge
Creek near Havre in Hill County.&&

$$

weather.gov/greatfalls



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