Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 151601
AFDTFX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1001 AM MDT Tue Apr 15 2014

.UPDATE...

Today...An upper level low pressure shortwave will cross the Rockies
today and cooler, windier conditions will spread across the plains.
Scattered showers ahead of this shortwave will mainly affect the
western mountains and Southwest Montana but the chance of showers
will increase everywhere later into the afternoon and evening.
Updated to raise a few max temps. Also freshened winds and wx
grids. Zelzer

&&

.AVIATION...
UPDATED 1200Z.
Expect VFR conditions this morning to gradually give way to more
widespread IFR conditions late this afternoon through tonight.
Mountains will become obscured as widespread rain/snow develops over
much of North Central and Central MT. Expect the precip to continue
into Wednesday and spread southward into Southwest MT. Generally IFR
conditions can be expected across much of the region through the day
on Wednesday. Brusda

&&

.PREV DISCUSSION...
/ISSUED 600 AM MDT Tue Apr 15 2014/

Today through Thursday...Clouds continue to increase this morning
as shortwave energy moves across the area. Snow will develop over
the Northern Rocky Mountain Front this morning and has prompted
the issuance of a Winter Storm warning for elevations above 5000
feet. A Winter Weather Advisory is in effect for elevations below
5000 feet. Associated surface low pressure will move to southeast
Montana by late afternoon and this will begin to draw cold
Canadian air across the area. The resulting upslope flow will
produce snow over the mountains and periods of rain and snow over
the plains. The heaviest precipitation will be found in a band
stretching from eastern Glacier County, through Pondera and Teton
Counties, to Cascade County, and on to Judith Basin and Fergus
Counties. Mountains should see 4 to 8 inches of snow with 2 to 4
inches possible over the plains. Precipitation should continue
through Wednesday afternoon before tapering off. Lingering
instability showers will continue Wednesday night before becoming
isolated showers Thursday. Temperatures will be near seasonal
averages today but dropping some 15 to 20 degrees below seasonal
averages Wednesday across the central and northern portions of the
county warning area. Afternoon readings will warm Thursday but
will remain below seasonal averages.

Thursday night through Tuesday...Expect a few light showers over the
Rocky Mountain Front on Thursday night...with the showers spreading
eastward out over the Plains on Friday. The main upper level
disturbance producing the precip during this period will move across
southern Canada...but enough moisture/instability will move across
MT that showers will develop...especially over North Central MT. The
precip activity should come to an end by early Saturday
morning...and overall a very nice weekend is expected for all of
North Central and Southwest MT. There is a very small chance for an
isolated shower over the mountains of the Rocky Mountain Front and
around Big Sky this weekend...but otherwise...most areas will be dry
with spring like temperatures. Afternoon highs on Saturday will be a
few degrees above normal...but on Sunday high temperatures should
average 4 to 8 degrees above normal. There is the potential that the
high temperature for Sunday could be a few degrees warmer than
currently forecasted if the GFS model pans out.

Then looking ahead to next Monday through Wednesday...the storm
system that was previously forecasted to move into the region for
Monday into Tuesday...now looks like it will move into the region on
Tue/Wed. Both the GFS and EC have different solutions on this event.
The GFS is very wet/mild and flood highlights would probably be
needed. The EC is not quite as wet...but it would favor the
potential for severe thunderstorms. Thus for now...with the
uncertainty...I will lean more towards climo pops and temperatures
that are near/just above normal...and see how the GFS/EC models work
themselves out over the next few model runs. Brusda

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  55  30  36  23 /  50  80  80  30
CTB  51  27  34  20 /  50  80  70  30
HLN  54  33  43  26 /  40  50  60  30
BZN  53  28  46  24 /  60  70  70  30
WEY  46  21  40  18 /  50  60  50  30
DLN  53  28  46  26 /  40  40  50  20
HVR  59  29  38  21 /  30  70  40  30
LWT  52  28  32  20 /  40  80  80  30

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY from 6 PM this evening to 6 PM MDT
Wednesday Broadwater...Cascade...Eastern Glacier...Eastern
Pondera...Eastern Teton...Fergus...Gallatin...Judith Basin...
Madison...Meagher.

WINTER WEATHER ADVISORY until 6 PM MDT Wednesday Central and
Southern Lewis and Clark...Southern Rocky Mountain Front.

WINTER WEATHER ADVISORY until 6 PM MDT Wednesday FOR ELEVATIONS
BELOW 5000 FEET FOR Northern Rocky Mountain Front.

WINTER STORM WARNING until 6 PM MDT Wednesday FOR ELEVATIONS
ABOVE 5000 FEET FOR Northern Rocky Mountain Front.

&&

$$


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