Area Forecast Discussion
Issued by NWS Glasgow, MT

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FXUS65 KGGW 270304

Area Forecast Discussion
National Weather Service GLASGOW MT
904 PM MDT Sun Mar 26 2017

.SHORT TERM...for northeast Montana...tonight through Tue...

While the main forecast is largely on track, pops were expanded to
cover a larger portion of the CWA tonight into Monday while a weak
front moves through the region. Maliawco

Previous Discussion...

Synoptic Setup: Short term begins with Warm Dry air
developing over the Four Corners and Zonal flow over Montana.
Farther west a Trough is developing off the coast from southern
California to British Columbia.

Tonight through Monday: A ridge will build out of the hot high
pressure of the Four Corners and fill in behind it during this 24
hour timespan. This will develop and push a warm front across the
CWA by Monday morning. A partial feed of pacific moisture and
slightly higher than normal surface moisture will pass over this
front generating a few isolated to scattered showers during the
day period. GAH

Monday night into Tuesday: A quick succession of short-wave ridge
followed by short-wave trough will bring an unsettled weather
pattern to northeast Montana. Model consensus indicates that
precipitation will result mainly in scattered rain showers mostly
around the periphery of our CWA through mid-day Tuesday. By
Tuesday afternoon and evening, it seems that the rain showers
begin to get better organized into a north-south band either over
our central or eastern CWA.  BMickelson

.LONG TERM...Tue night through Sun...

Late Tuesday night through Wednesday morning, the remainder of the
banded rain showers will slowly exit our eastern zones. Whether or
not these storms will become thunderstorms will depend on if they
are able to tap into the limited amount of instability in the
atmosphere. The main trough and greater energy with this system
resides further south, closer to the deeper, upper-level low. For
now, will keep a mention of thunder out of the forecast until a
strong signature becomes evident.

The next storm system set to impact NE Montana will be with the
next push of low pressure from the west around Thursday afternoon
through Friday. More model variability and uncertainty for this
far out. BMickelson

Previous long term discussion: The long term begins with a
departing trough Tuesday night and Wednesday into the Upper
Midwest while a shortwave ridge builds across Montana. As a
result, rain showers will exit and warmer and drier weather
conditions will prevail for the midweek.

A more amplified trough will develop into the western CONUS for
Thursday with a closed low splitting off on the southern extent
across the Great Basin. Do expect broad dynamic forcing for ascent
and ample moisture to lead to increasing rain showers with this
system as it impacts the CWA. As the effects would not reach the
region until day 5 or 6, there is still plenty of uncertainty as
to where the steadiest rain showers may occur. Nevertheless, this
will be a period of interest in the coming days.

Given the increasing spread in ensemble 500mb heights beyond
Thursday, the forecast was largely trended toward latest 12z
consensus model blends. Maliawco



SYNOPSIS: weak trough will move in from the SW Monday bringing
rainshowers. Brief afternoon MVFR is possible in the heaviest

WINDS: Light and variable overnight becoming southeast at 5 to 15
kts Monday.





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