Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 291547
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
947 AM MDT SUN MAY 29 2016

.UPDATE...


&&

.DISCUSSION...Overall not many changes made to the morning update.
Dry westerly flow continues overhead through this morning. Trough
extending down from Canada will bring moist sw flow this
afternoon...and producing weak instability. Latest NAM run
provides a little more scattered thunderstorm activity this
afternoon then past runs. Updated PoPs slightly to account for
this. Thunderstorms look to remain below severe criteria
today..although a few isolated storms with small hail and gusty
winds are possible. Better chances of showers and thunderstorms
still looks to be this evening...through tonight...and into
Memorial Day...except across far SW portions of the CWA...where
precipitation activity will remain isolated in coverage. Isolated
to scattered showers and thunderstorms could remain for
Tuesday...with Wednesday still looking warmer and dry. Anglin


&&

.AVIATION...
UPDATED 1135Z.
Dry westerly flow aloft will continue. As an upper level disturbance
approaches northwest Montana after 00z, the flow aloft will become
increasingly southwest. Isolated afternoon showers and thunderstorms
will increase in areal coverage after 00z. VFR conditions prevail
with increasing MVFR after 00z due to lowering ceilings and
precipitation. Gusty erratic winds near thunderstorms.

&&

.PREV DISCUSSION...
/ISSUED /

Today through Tuesday...Dry westerly flow aloft will persist
through the morning hours but will become increasingly southwest
during the afternoon as an upper trof moves across the Pacific
Northwest. A chinook arch has developed in the lee of the Rockies
and should remain through the morning hours. With moisture and
instability increasing during the afternoon, isolated showers and
thunderstorms will develop, mainly near the western and southwest
mountains and over adjacent plains. Showers and thunderstorms will
increase in areal coverage overnight as the upper trof approaches
the continental divide and an associated cold front moves across
the area. Models are in fairly decent agreement with the forming
of a closed upper low over northeast Montana Monday afternoon and
focusing the best chance for precipitation over central and
northern Montana. The upper low continues to exit to the east
Monday night but wrap-around circulation will keep showers active
across the northeast portion of the county warning area. Tuesday
will see lingering showers in the east but drying conditions
across the west as high pressure begins to build in. Gusty
northwest winds Tuesday will keep temperatures cool. Afternoon
readings will be near to slightly above seasonal averages today
but will drop below said averages Monday and Tuesday.

Tuesday night through Sunday...Warm and dry conditions are
anticipated from Wednesday through next weekend as a broad upper
level ridge sits over the western United States. A few minor
shortwave features will move through the ridge and could produce
isolated afternoon thundershowers mainly over our western and
southwest mountains. Temperatures will trend above average, reaching
the low to mid 80s across much of our forecast area. PN

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  71  44  59  41 /  20  40  60  40
CTB  67  41  55  39 /  10  10  60  40
HLN  71  45  61  42 /  30  30  50  20
BZN  71  42  62  37 /   0  30  40  30
WEY  61  37  56  32 /   0  20  20  20
DLN  69  41  62  37 /  10  20  30  10
HVR  72  47  59  46 /   0  20  60  60
LWT  69  45  57  41 /  20  60  50  40

&&

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

$$

weather.gov/greatfalls


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