Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Great Falls Montana
957 am MDT Sat Jul 30 2016

minor adjustments made to the pop grids. Satellite imagery showing
area of clouds associated with an upper trof moving slowly across
southern Canada. Radar picking up some returns ahead of this feature
but hrrr analysis develops very isolated convective activity across
the hi-line this afternoon. Likewise, hrrr showing isolated
thunderstorms developing over Judith Basin County this afternoon and
then moving them east through Fergus County. Temperatures look good.


updated 1130z.
A dry westerly flow aloft will gradually increase across the
northern rockies and Montana today ahead of an upper level trough
dropping south through British Columbia. At the surface, a trough of low pressure
will shift east across central Montana today, allowing winds to become west
to SW and increase this afternoon. An isolated thunderstorm may
develop in the vicinity of the north-central Montana mtns this afternoon. VFR
conditions will prevail. Hoenisch


Previous discussion...issued 328 am MDT Sat Jul 30 2016

Today through Monday...overall a warm and dry weekend with
elevated fire danger returning. Current WV imagery starting to
show dry air entering into SW Montana with some limited moisture in
central Montana...and the monsoonal moisture...that has been monitored
for days...stopping just short of the Nevada and Idaho border. Upper
level low will push into Canada today bringing warm SW flow to the
area. Today we find out if we are able tap into any of the
monsoonal moisture to our south. Current model runs are showing
the answer is probably not as much as we would like. Far SW Montana may
see a few afternoon thunderstorms from the northern extend of this
moisture...with generally only a few isolated mountain storms
elsewhere. Northern Montana may be the dry air attempts
to push out the not as dry air this afternoon a pseudo warm/dry
line type front may set up. With ample instability...shear from an
increasing jet...and some increased dewpoints from se flow...a few
isolated thunderstorms may develop across the hi-line area this
afternoon and evening. All areas will see warm temperatures
today...with high temps across the lower elevations expected to
reach into the 90s. A weak cool front associated with the upper low
in Canada will then push across the region tonight through Sunday.
This looks to be a fairly dry front...with only a few areas across
the north and far south seeing chances for isolated thunderstorms.
The main story with this front will be the elevated fire danger
concerns for min relative humidity values will drop into the
teens...and gusty westerly winds will be found. For a more detailed
discussion about the fire danger this weekend see the fire weather
discussion below. The main take away is those with outdoor plans
should be mindful of errant Sparks...attend and put out all
campfires...and hold off outdoor burning this weekend. Dry air with
some continued westerly breezes will continue into Monday as brief
ridging begins to approach the area. Temps for Sunday and Monday
will be slightly cooler then the 90s on Saturday...but still could
be near to slightly above climate normals. Anglin

Monday night through Saturday...upper level ridging briefly shifts
east across the region Monday night through early Tuesday with
temperatures warming back to somewhat above average levels again by
Tuesday afternoon. A compact upper level low moves inland along the
Washington/British Columbia border Tuesday and continues east along the Montana/ab border
Tuesday night. Diffluent SW flow aloft and incoming upper level jet
maximum ahead of the low will focus greatest large scale lift across
north-central Montana Tuesday afternoon and evening with a cold front also
looking to shift east across the region during the late afternoon
period. This could create a favorable set-up for potentially severe
convection Tuesday afternoon/evening if enough moisture can return,
which is appearing more likely with an inverted surface trough
setting up across S-central/central Montana Tuesday and east/NE low level
flow ahead of the front across the north-central Montana plains. Drier and
cooler air moves in behind the front late Tuesday night through
Wednesday as the upper low tracks east along the Montana/sk border with
just a small chance for showers along the Canadian border. Thursday
through Saturday period looks to gradually warm as heights build
around an upper level ridge centered over the central Continental U.S. With
weak troughing oriented along the West Coast. Hoenisch


Fire weather...
warm and dry conditions to bring elevated fire danger this weekend.
Southwest flow will bring very warm and drying conditions today
across the forecast area. Min relative humidity values today will begin to lower
into the teens and 20s...with high temps expected to return into the
90s. Increasing breezes will be found across southern and western
portions this afternoon and evening. Only isolated thunderstorms are
expected for today...mainly across the north...far south...and in
the higher terrain. A weak cool front will then push across the
region tonight through Sunday. This will bring slightly cooler
temperatures along with very dry conditions...and only isolated
thunderstorms in the far south and north. Gusty westerly winds may
also be found Sunday...with gusts 20 to 25 mph possible. Despite
these favorable fire weather conditions...fuel status across local
fire zones remains near to slightly below critical values.


Preliminary point temps/pops...
gtf 93 60 88 50 / 10 0 10 10
ctb 89 54 78 48 / 10 0 10 20
hln 94 63 90 54 / 10 10 10 10
bzn 92 57 90 48 / 10 10 10 10
wey 83 53 80 42 / 10 20 20 10
dln 90 56 87 47 / 10 10 10 10
hvr 92 61 86 53 / 20 20 10 20
lwt 88 62 87 52 / 10 10 10 10


Tfx watches/warnings/advisories...



National Weather Service Glossary of Abbreviations