High Wind Watch 18, NWS Great Falls, MT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1200 PM MDT Fri Sep 27 2013

.UPDATE...
Minor update for the grids today just adjusting POP down for all
of the plains. Conditions look sunny and mostly dry today with
winds picking up this afternoon.

&&

.AVIATION...
UPDATED 1800Z.
VFR conditions will continue. High clouds will move back into the
area from the west this evening. West winds will increase through
the afternoon hours especially across the plains of Central and
North Central Montana.

&&

.PREV DISCUSSION...
/ISSUED 555 AM MDT Fri Sep 27 2013/

Today through Sunday...The upper level trough that brought rain
and mountain snow to the region will continue to move east
today. Residual clouds will linger across the eastern and southern
portions of my forecast area this morning with some light snow
persisting near Yellowstone Park. However, skies are expected to
generally clear this afternoon with a weak but broad shortwave
ridge building over the Northern Rockies tonight and Saturday.
Westerly flow aloft will increase and surface pressure east of the
Continental Divide will fall as a lobe of upper level energy moves
over the region tonight. Surface winds will increase during this
period and there is a possibility that favored canyons and passes
along the Northern Rocky Mountain Front could approach high wind
criteria for a short period late tonight. Westerly flow aloft will
also bring increasing Pacific moisture inland with orographic
uplift expected to bring precipitation to the mountains near the
Continental Divide late tonight through Sunday. During this period
temperatures and snow levels will rise so mostly rain is
anticipated by Sunday afternoon. Rain on fresh snow-pack will
likely cause increased flow on small creeks and streams but
flooding is not anticipated at this time since mountain snow-pack
is still fairly light. Main concern for the short term period will
be the continued increase in mid-level winds and tightening
surface pressure gradients with strong and gusty winds expected
along the Rocky Mountain Front by Saturday evening. Have therefore
issued a High Wind Watch for Saturday evening through late Sunday
afternoon for this region. mpj

Sunday night through Friday...Medium range forecast models continue
to show a near a very fast progressive westerly flow aloft over the
area through next week. The upper level trough responsible for
this pattern will continue to strengthen and and expand from its
location in the Gulf of Alaska south along the BC coast and into
western Canada. An induced upper level ridge downstream of this
trough will begin the long term period bringing dry windy
conditions. These winds are expected to remain strong as the
shortwave troughs ejected from the level low approach the region
and a decent pressure gradient along with a strong upper level jet
continue to reside over the area. By Monday a shortwave will be
ejected out over Montana and could bring some rain and snow
showers to the area...with the bulk of the snow remaining in the
mountains. After Monday models diverge in timing and location of
subsequent shortwave troughs moving across the region. However
models do continue to keep the fast progressive pattern in place.
Have continue to keep pops slightly above seasonal averages due to
this increased likelihood of showers moving quickly across the
area in this type of flow pattern. Suk

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  57  41  65  50 /   0   0   0   0
CTB  57  37  60  47 /   0  10  20  20
HLN  56  38  64  45 /   0   0  10   0
BZN  53  34  64  41 /   0   0  10   0
WEY  43  22  49  29 /  20  10   0   0
DLN  51  34  61  40 /   0   0  10   0
HVR  61  37  67  46 /   0   0   0   0
LWT  52  34  63  43 /   0   0   0   0

&&

.TFX WATCHES/WARNINGS/ADVISORIES...

HIGH WIND WATCH from Saturday evening through Sunday afternoon
Northern Rocky Mountain Front...Southern Rocky Mountain Front.

&&

weather.gov/greatfalls

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE GREAT FALLS MT
219 PM MDT FRI SEP 27 2013

MTZ008>010-012-014-015-044-046-048-049-052-281200-
BEAVERHEAD-NORTHERN ROCKY MOUNTAIN FRONT-EASTERN GLACIER-CASCADE-
CENTRAL AND SOUTHERN LEWIS AND CLARK-MADISON-TOOLE-
EASTERN PONDERA-SOUTHERN ROCKY MOUNTAIN FRONT-EASTERN TETON-
JEFFERSON-
219 PM MDT FRI SEP 27 2013

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL
MONTANA...NORTH CENTRAL MONTANA AND SOUTHWEST MONTANA.

.DAY ONE...THIS AFTERNOON AND TONIGHT

HIGH WIND HIGHLIGHTS ARE IN EFFECT FOR PORTIONS OF NORTH CENTRAL
TONIGHT.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

HIGH WIND HIGHLIGHTS ARE IN EFFECT FOR PORTIONS OF NORTH CENTRAL
AND SOUTHWEST MONTANA THROUGH SUNDAY EVENING.

.SPOTTER INFORMATION STATEMENT...

ANY SPOTTER REPORTS OF HIGH WINDS WOULD GREATLY BE APPRECIATED.

MTZ011-013-045-047-050-051-053>055-281200-
HILL-CHOUTEAU-LIBERTY-BLAINE-JUDITH BASIN-FERGUS-BROADWATER-
MEAGHER-GALLATIN-
219 PM MDT FRI SEP 27 2013

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL
MONTANA...NORTH CENTRAL MONTANA AND SOUTHWEST MONTANA.

.DAY ONE...THIS AFTERNOON AND TONIGHT

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.