FXUS65 KGGW 171539

Area Forecast Discussion
National Weather Service Glasgow MT
939 AM MDT Tue Jul 17 2018


Lowered pops and MinRH for today. Looks like RHs bottom out in the
mid teens in Phillips County this afternoon. TFJ

Previous Discussion...
An upper ridge that is over Eastern Montana this morning will
move to the east today. A shortwave upper trough will move into
the area this afternoon as a slow moving cold front moves into
Central Montana. Unstable air mass will allow showers and
thunderstorms to develop over the southwest half of the forecast
area this afternoon and evening. Otherwise, very warm temperatures
will prevail with highs between the upper 80s and mid 90s.

The upper trough will be over Eastern Montana tonight and
Wednesday while the cold front becomes quasi-stationary over the
western part of the forecast area. There will be a good chance of
showers and thunderstorms over most of the region tonight and the
northeast half of the forecast area on Wednesday as the trough
moves slowly east. Much drier air mass moves into the western
zones Wednesday afternoon with west to northwest winds which will
lower RH to teens in the afternoon and create the possibility for
critical fire weather conditions. There is high confidence in the
low RH but there is forecast uncertainty in the winds at this
point due to model differences in the location of the front. Will
maintain Fire Weather Watch in the west for now.

Flow aloft turns to the NW Wednesday Night as upper trough moves
to the east. Another shortwave on Thursday will move the front to
the east with enough instability for a chance of showers and
thunderstorms in the afternoon.

Surface high pressure Thursday Night and an upper ridge on Friday
will allow for mainly dry weather.

The ridge remains over the area on Saturday with dry and warm

An upper trough on Sunday will bring a cold front through the area
with a chance of showers and thunderstorms. NW flow aloft with
prevail early next week with below normal temperatures and mainly
dry weather. Forrester



Expected Flight Category: VFR.

Synopsis: Upper level ridge moves to the east this morning. Mostly
clear skies will prevail at the TAF sites with some high clouds at
times. Mid level clouds will move into the area tonight from the
SW as an upper level trough moves into Eastern Montana. Showers
and thunderstorms will be possible at times late tonight and
Wednesday, but KGGW should remain dry.

Wind: East to southeast winds today around 10 knots will diminish
to 5 to 10 knots tonight. TFJ



Main Point: A potential critical fire weather day is forecast for
Wednesday afternoon and evening.

Synopsis: A cold front will move into the region on Wednesday.
Much drier air will move into areas west of Glasgow and Jordan
Wednesday afternoon with RH falling into the teens with gusty west
to northwest winds possible. Hot and very dry conditions are
expected, especially across the western zones (134, 135, 136).
Thus, a Fire Weather Watch remains in effect for Wednesday
afternoon and evening to increase awareness of the situation.

Winds/RH: Winds Wednesday afternoon and evening are expected to
mostly be 10-20 mph especially in Phillips County, with gusts to
near 30 mph at times. Minimum RH values will generally be in the
low to mid teens across the western half of the region.


Fire Weather Watch from Wednesday afternoon through Wednesday
evening for MTZ134>136.



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