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Area forecast discussion 
National Weather Service Great Falls Montana
427 am MDT sun Jul 31 2016

Discussion...

Today through Tuesday...an outflow boundary from Canada has set up
two Stark air masses this morning across the County Warning Area. From the California/Montana
border south to Great Falls dewpoints in the 50s are found...with
dry air and dewpoints in the 30s and 40s south of Great Falls.
This difference in airmass is important to note for where there
will be extreme fire danger versus elevated fire danger today as
a cool front will bring more dry air and gusty winds today. From
about Helena south extreme fire danger is expected today with
fuels now in the very high danger class...low relative humidity values this
morning continuing through this afternoon...and expected
increasing gusty winds...with gusts up to 30 miles per hour. A red flag
warning has been issued for the fire danger today...see our fire
weather discussion for more details. Elsewhere...this mentioned
front will still bring gusty winds and dry air...so elevated fire
danger is still expected...and those outdoors should still be
mindful of what may spark a fire. Thunderstorm chances will only
be confined to the more moist air in the far north and far south
as the front and upper level disturbance moves through today.
Isolated coverage is expected...with gusty winds being the main
threat. Thunderstorm chances will diminish tonight...giving way to
dry and warm conditions for Monday...as brief ridging moves into
the area. Tuesday still looks to be an interesting day for the
potential of severe weather. Mid level low moves into the pac northwest
by Tuesday afternoon sending increased moisture with SW flow.
Meanwhile a sfc low develops in Wyoming and southern Montana bringing moist
easterly flow. A triple Point of sorts looks to set up near Havre
by Tuesday evening. As the upper level wave moves across the
area...with the associated frontal boundaries...thunderstorms will
be possible. Timing now looks the thunderstorms may be more of a
later show...so decrease pops slightly for Tuesday
afternoon...however...timing should be monitored. Given high shear
values from a strengthening jet...and modest
instability...isolated to scattered severe weather is possible by
Tuesday afternoon...then becoming better chances Tuesday night.
Gusty winds and continued dry conditions...may also bring more
elevated fire danger for Tuesday...mainly from Helena and
south.Temperatures will be slightly cooler today through
Monday...however...still remain near to slightly above normal.
They could then return to the 90s on Tuesday. Anglin

Tuesday night through Saturday...a fairly vigorous mid-upper level
low tracks from the Idaho Panhandle east along the Canadian border
Tuesday night and Wednesday. Models have slowed the timing of this
feature slightly with Tuesday evening/night period now looking to
hold the best potential for convection as a cold front sweeps east
across the forecast area. Low level moisture and instability will be
greatest across eastern portions of north-central Montana where strong
forcing ahead of the upper low and and favorable speed/directional
wind shear looks to provide a threat for severe thunderstorms,
particularly along areas near the Canadian border Tuesday evening.
As the system tracks east along the Montana/sk border late Tuesday night
and Wednesday moisture wrapping around the low will maintain a
chance for showers along the Canadian border while dry, breezy and
cooler conditions spread over the rest of north-central and SW Montana. Upper
level ridging rebuilds over the interior western US Thursday through
next weekend for generally dry and warming conditions with some
potential for an increase in moisture under a SW flow aloft by the
weekend. Hoenisch

&&

Aviation...updated 0545z.

VFR conditions will prevail through Sunday evening under a dry
westerly flow aloft with greatest impact to aviation being
surface winds through tomorrow. Outflow/frontal boundary originating
in ab has pushed south through kctb bringing an abrupt/gusty wind
shift to the north and this boundary will likely continue south
overnight, bringing a shift to north/northwest winds at kgtf and khvr between
08-09z. On Sunday winds will strengthen from west through the afternoon
period across all of N-central/SW Montana with winds gradually veering to
northwest Sunday evening before diminishing. Hoenisch

&&

Fire weather...

Red flag warning issued for fire weather zone 118 from noon today
until 8 PM this evening. This morning Max relative humidity in some areas is
struggling to get to 50 percent...with Helena Airport only at 30
percent currently. A weak cool front is expected to push across
the region this morning...bringing with it increased westerly
winds and more very dry air. Slightly warmer and dryer than
expected conditions on Saturday caused fuels to reach the very
high danger class for portions of fire zone 118. Now with critical
fuels in place...a red flag warning has been issued for fire
weather zone 118 today for relative humidity in the low teens and wind gusting
near 25 miles per hour or higher. Elsewhere will see elevated fire danger
today with breezy winds and dry air...however...fuels remain below
critical levels in these areas. Only a few isolated thunderstorms
are expected across far northern and southern portions today. Dry
conditions will remain for Monday...however...winds will begin to
diminish tonight through Monday. More elevated fire danger
returns Tuesday ahead of an approaching system...with low relative humidity and
gusty winds expected. Anglin

&&

Preliminary point temps/pops...
gtf 87 50 86 51 / 0 0 0 10
ctb 77 47 80 48 / 20 10 0 10
hln 89 53 88 55 / 0 0 0 10
bzn 91 46 88 49 / 0 0 0 10
wey 81 40 79 43 / 20 20 0 10
dln 86 46 86 49 / 0 0 0 10
hvr 85 51 84 51 / 0 0 0 10
lwt 87 51 83 53 / 10 10 0 10

&&

Tfx watches/warnings/advisories...
red flag warning from noon today to 8 PM MDT this evening for
mtz118.

&&

$$

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