Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 271524

924 AM MDT Wed Aug 27 2014

.UPDATE...Have updated winds to indicate stronger gusts along the
Rocky Mountain Front today through Thursday. Westerly flow aloft
and a weak downslope pressure gradient have combined to increase
winds through canyons and passes with gusts currently topping out
around 35 mph at Deep Creek. Pattern will support continued gusty
westerly winds along the Front Range until a wind shift to the
north occurs Thursday evening as a weak Canadian cold front pushes
through the region. Skies will remain clear to mostly clear today
and temperatures will top out in the 80s at most locations. mpj


High pressure ridging over the Northern Rockies will keep conditions
stable and dry, with a mix of clear skies and scattered high clouds
next 24 hours.  Winds will be light across the region today.


/ISSUED 515 AM MDT Wed Aug 27 2014/

Cut-off upper-low continues to rotate over the Central Rockies and
is centered over Utah as of 10Z/Wednesday. This feature will have
little influence on Montana`s weather with sct showers/storms only
reaching as far north as Idaho and Wyoming.

Today...Zonal flow and negligible pressure gradient from the sfc up
through the troposphere will result in clear skies, light winds, and
seasonal temps. SREF 1000-500 mb thicknesses rise to near 573-576
dam...700 mb temps increase to ~8 C.

Thursday...Cold air advection in the 1000-500 mb layer looks to hang
mainly west of the forecast area through Thursday aftn, allowing
temps to reach the mid 80s. The tail end of an upper jet will brush
north-central MT during the evening/nighttime and a 500 mb vort max
will traverse through MT from west to east. These features should
produce isolated showers during this time.

In concert with these mid/upper level disturbances, a low-level
cold front, albeit a weak one, will slide through north-central
MT, increasing dewpoints to the lower 50s. NAM has MUCAPE values
up to 1 K J/kg along the boundary. Therefore, there is a slight
chance for thunder.

Friday...As the sfc boundary stalls just south of GTF Friday
morning, a SE flow will develop in response to a high pressure
center moving through the Dakotas. This flow will support low-level
moisture advection and should sustain 50-55 F dewpoints which will
create an unstable air mass over my eastern forecast area during the
aftn...MUCAPE may exceed 1 K J/kg. However, showers/storms should
remain isolated. Uttech

Friday Night through Wednesday...Cool and unsettled conditions are
expected for this period.  The primary weathermaker will be
a longwave trof that gradually moves into the region on Sat and will
persist across the Northern Rockies and the Great Basin areas
through much of next week.  A series of quick-moving shortwaves
embedded within the larger trof pattern will bring scattered showers
and thunderstorms on Saturday, Monday, and Wednesday with isolated,
lingering showers possible on Sunday. An autumn-like cooling trend
begins with passage of a cold front in the early aftn on Sat, and is
then maintained by northwest flow aloft through at least Mon.  After
near-normal temperatures on Sat, high temps each following day will
be about 10-15 degrees below normal, with highs only reaching the
low-mid 60s.  Will also be keeping an eye on possibility of
breezy-to-gusty surface winds along the Rocky Mtn Front and adjacent
foothills and plains on Mon and Tues as a leeside trof develops over
central MT with high pressure ridging west of the Continental
Divide. Waranauskas


GTF  84  55  85  53 /   0   0   0  20
CTB  85  53  79  50 /   0   0  20  20
HLN  85  55  87  54 /   0   0   0  20
BZN  81  47  84  48 /   0   0   0  20
WEY  70  38  72  39 /   0   0  10  20
DLN  79  49  82  50 /   0   0   0  10
HVR  86  55  85  53 /   0   0  10  30
LWT  82  55  84  54 /   0   0  10  20



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