828
FXUS65 KTFX 090500
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
1100 PM MDT Mon Jul 8 2024

...Aviation Section Updated...

.SYNOPSIS...

The warming trend continues with temperatures peaking well into the
90s to near 100 by Wednesday and Thursday. Highs level off in the
80s and 90s for the second half of the week while afternoon
breeziness becomes more pronounced. Little to no precipitation is
expected aside from an isolated afternoon or evening storm or two
heading towards the weekend.

&&

.Update...

Evening update has been published, with only minor adjustments
made to the on-going forecast. Upper level ridge axis will
continue to build eastward and over the Northern Rockies through
Tuesday. Low level water vapor imagery this evening shows very
dry air beneath this ridge along the western seaboard, with mid-
level imagery showing some moisture rounding the ridge axis over
Southwest Canada and dropping southeast towards North Central
Montana. This mid-level moisture will provide some scattered mid-
level clouds throughout the overnight hours, but otherwise very
dry air will continue to overspread Southwest through North
Central Montana. This will lead to one of many upcoming nights of
poor moisture recovery, especially within thermal belt locations.

&&

.AVIATION...
09/06Z TAF Period

VFR conditions prevail this TAF period under mostly clear skies and
light winds. The greatest concern will be for density altitudes
given forecast hot temperatures Tuesday. -AM

Refer to weather.gov/zlc for more detailed regional aviation weather
and hazard information.

&&

.FIRE WEATHER...

The first extended period of very warm to hot weather is expected
this week with temperatures warming into the 90s to near 100 by
mid- week before leveling off in the upper 80s and 90s heading
towards the weekend. The combination of the warming temperatures
with minimum relative humidity values falling to critical levels
and only moderately recovering overnight will accelerate the
seasonal drying of fuels, particularly for grassland areas.

Additionally, weak disturbances will begin to move through the
Northern Rockies during the second half of the week, resulting in
increased westerly breezes and instances of isolated thunder
activity. Fire containment officials should be prepared for a
quick transition into fire weather season and those in the general
public should be mindful of the rapidly drying conditions and
avoid activities that produce sparks or involve unattended open
flames. - RCG

&&

.PREV DISCUSSION...
/ISSUED 537 PM MDT Mon Jul 8 2024/

Upper level ridging continues to build into the Northern Rockies
this afternoon and temperatures have quickly warmed well into the
80s and will approach and exceed 90 degrees in some spots before
days end. The latest SPC meso-analysis shows surface CAPE going
over 500 J/kg over portions of North-central MT and cloud builds
over higher terrain are being observed on satellite; however, mid-
level lapse rates hovering around 6.5C/km will ensure shallow
development with minimal chances (<10%) for shower or storm
development through this evening. 500 mb heights slowly increase
through Thursday and will maintain a day to day warming trend
through mid- week before temperatures level off during the second
half of the week. Temperatures will peak in the middle 90s to near
100 Wednesday and Thursday, approaching record highs for some
locations. Although, there will be at least some heat related
impacts from this quick incline in temperatures, the situation
will continue to be handled by messaging for now.

The ridge is dampened some by weak disturbances passing through a
modest westerly flow aloft Thursday into the weekend. This will
introduce a notable increase in westerly breezes and the
opportunity for a few isolated storms. Although temperatures do
begin to level off, they will remain well above average and
generally range in the upper 80s to upper 90s. The continued warm
temperatures in addition to breeziness and isolated thunder
activity will result in a quick transition into peak fire season,
see the fire weather section for more for more information. - RCG

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  59  91  60  97 /   0   0   0   0
CTB  58  92  59  95 /   0   0   0   0
HLN  63  96  62 100 /   0   0   0   0
BZN  55  91  56  96 /   0   0   0   0
WYS  43  83  44  87 /   0   0   0   0
DLN  53  89  54  94 /   0   0   0   0
HVR  61  93  61  97 /   0   0   0   0
LWT  56  86  57  91 /   0   0   0   0

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

http://www.weather.gov/greatfalls