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000
FXUS65 KTFX 081143
AFDTFX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
445 AM MST Sat Mar 8 2014

...UPDATE TO AVIATION...

.DISCUSSION...

An upper level ridge of high pressure will gradually shift east
across the Northern Rockies today, providing the forecast area
with generally clear, dry and mild conditions. Cold pool still
lingers at elevations below 3000 ft along the Marias, Milk and
Missouri Rivers, but should erode quickly this morning as SW winds
overspread the region. Already seeing localized strong west winds
along the northern Rocky Mtn Front and expect winds to increase
and expand eastward late this afternoon and evening as the ridge
axis shifts east and winds aloft increase from the west. The upper
ridge continues to flatten tonight with strong west flow aloft
overspreading much of the forecast area. A high wind warning is
already in effect for the Rocky Mtn Front region with the rest of
Glacier county and areas near the Sweetgrass Hills seeing strong
winds develop by this evening. Pressure gradient between a
lee-side trough over north central MT and high pressure over the
Yellowstone Park region should support strong south winds over
Norris Hill in Madison county beginning this evening and
continuing through Sunday morning. Potential for strong winds also
exists over much of the remainder of north central MT late tonight
through Sunday, especially over areas near the continental divide
as well as areas to the north and east of the Little Belt,
Highwood and Bears Paw Mtns. By Sunday night an upper level trough
of low pressure moves onto the west coast and into the interior
western US on Monday. Winds will diminish Sunday night and shift
to the NW over north central MT by Monday morning in response to
low pressure developing over SW MT and WY. Models continue to
advertise the development of widespread precipitation over Central
and SW MT on Monday ahead of the upper trough and associated with
favorable dynamics to the north of an upper level jet maximum
moving into WY. Northern edge of the precipitation shield is where
models still have some difficultly with ECMWF model depicting the
widespread precip as far north as Great Falls while GFS and NAM
models keep the bulk of the precipitation along and south of a
Helena to Lewistown line. Snow levels will be lowering late Sunday
night through Monday as cooling aloft occurs with the incoming
trough. At this point significant accumulations (in excess of 6")
look to be limited to areas above pass levels, but this will need
to be monitored for possible winter weather highlights as snow
levels lower to near valley floors/plains by Monday afternoon.
Temperatures will warm to upper 40s and 50s this afternoon with
very mild overnight low temps expected tonight due to increased
winds and cloud-cover. The mild start Sunday morning and gusty
west winds through the day will help boost temperatures into the
50s to near 60 at many lower elevation locations Sunday afternoon.
Temperatures will cool to the 30s and 40s on Monday.

Monday night through Saturday...Medium range period starts off with
an upper level wave sweeping across Montana Monday night and
Tuesday. As this feature moves southward early in the period
widespread precipitation over the southern third of Montana will
taper off and move out of the state. Upper level ridging  builds
across the western states on Wednesday but the remainder of the time
period will be marked by a somewhat unsettled northwesterly flow
aloft with occasional disturbances moving over Montana. Models
continue to keep temperatures near of above seasonal averages
through the week with generally breezy conditions expected over the
north central plains. At this time, models suggest that any
precipitation should be confined to the western and southwest
mountains from mid-week onward through the weekend. However, with a
somewhat unsettled and inherently unpredictable northwesterly flow
aloft, have trended pops toward climatology for the end of the week
and into the weekend. mpj


&&

.AVIATION...
UPDATED 1145Z.
Upper level ridging will prevail over the Northern Rocky Mountains
for widespread VFR conditions through early Sunday morning. Gusty
westerly winds are expected across western portions of north central
Montana through the forecast period. A disturbance moves through the
upper ridge after 00Z Sunday for increasing mid and high level
clouds with mountain obscurations and areas of mountain snow. mpj

&&

.HYDROLOGY...
Snowmelt runoff will continue to contribute to lowland flooding in
areas of poor drainage across much of central and southwest MT. As
temperatures warm significantly over the weekend, snowmelt will
likely increase across additional areas of north central and
southwest Montana. Therefore, a hydrologic statement was issued for
these areas, addressing the increasing threat for additional
flooding, especially in poor drainage areas, and the potential for
further flood statements. Coulston/Hoenisch

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  53  42  60  33 /   0   0   0  30
CTB  47  39  56  28 /   0  10  10  10
HLN  50  33  55  33 /   0   0  10  70
BZN  46  30  52  33 /   0   0  10  40
WEY  40  23  43  34 /   0   0  30  80
DLN  46  30  48  30 /   0   0  10  60
HVR  47  34  57  28 /   0  10  10  10
LWT  52  39  57  34 /   0   0  10  20

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
HIGH WIND WATCH from late tonight through Sunday evening
Blaine...Cascade...Central and Southern Lewis and Clark...
Chouteau...Eastern Pondera...Eastern Teton...Hill...Judith Basin.

HIGH WIND WARNING until 9 PM MDT Sunday Northern Rocky Mountain
Front...Southern Rocky Mountain Front.

HIGH WIND WARNING from 5 PM MST this afternoon to 9 PM MDT
Sunday Eastern Glacier...Liberty...Toole.

HIGH WIND WARNING from 5 PM MST this afternoon to 9 PM MDT
Sunday For Route 287 over Norris Hill in Madison County.

&&

$$


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