Area Forecast Discussion
Issued by NWS Glasgow, MT

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432
FXUS65 KGGW 210200
AFDGGW

Area Forecast Discussion
National Weather Service Glasgow MT
800 PM MDT Sun May 20 2018

.DISCUSSION...

745PM UPDATE:
Changes for the evening seem to be few. Cloud coverage was
adjusted slightly from FEW to SKC for TAFs. Reduction in wind
gusts and sustained speed appears to be on track for a 8PM
removal of the lake wind advisory. Remainder of the forecast looks
good. GAH

PREVIOUS AFTERNOON DISCUSSION:
Clear skies will continue across the area through tonight as high
pressure overhead provides sufficient subsidence. Monday will
start out with clear skies, but clouds will be on the increase
through the day, especially out west, as a weak upper level short
wave trough moves southeast into Northeast Montana.

At the surface, moisture return will increase rapidly tonight into
Monday with dewpoints returning to near 50 degrees across southern
areas by Monday evening. Upslope flow across the higher terrain
out west combined with just enough lift from the weak short wave
should be enough to trigger a storm or two by Monday evening
across western Phillips and Petroleum Counties. Outside of the
higher terrain, storm coverage through Monday night should remain
isolated to scattered at best.

As this shortwave moves off to the east on Tuesday, an area of low
pressure will begin to move in from the southwest. Surface
dewpoints will reach the middle and upper 50s by Tuesday afternoon
with PWAT values around an inch. This will make for some semi-muggy
conditions by Montana standards as highs rise into the upper 70s
to near 80. Expect additional isolated to scattered storm coverage
on Tuesday, with the best activity remaining to the south of the
area.

The best storm chances arrive Wednesday and Thursday as the
better upper-level lift moves into Northeast Montana. There will
be an area of low pressure at the surface that looks to remain
well southeast of the CWA, so the severe threat appears to be
minimal at this time.

A ridge of high pressure begins to move in Thursday night into
Friday, drying the region out. Temperatures throughout the
forecast period look to remain above normal. --Mottice--


&&

.AVIATION...

FLIGHT CAT: VFR

SYNOPSIS: Clear skies will continue through much of the TAF
forecast period. A small trough and disturbance from the north
will increase cloudiness by late Monday.

WIND: Southeast at 10 to 15 kts with gusts to 25 kts through the
early evening before dying down. Calming below 10 kts later
tonight... and increasing slightly on Monday afternoon.

GAH/--Mottice--

&&

.GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

weather.gov/glasgow



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