Area Forecast Discussion Issued by NWS Glasgow, MT
000
FXUS65 KGGW 130821
AFDGGW
Area Forecast Discussion
National Weather Service Glasgow MT
221 AM MDT Wed Mar 13 2024
.DISCUSSION...
MORNING DISCUSSION:
The 500 hPa trough over the PNW is in the process of cutting off
and ejecting from the main jet stream. This area of synoptic
upper-level divergence will be the main reason for enhanced lift
across Montana, bringing areas of light rain and snow across the
plains across the southern half of Montana this morning and
moderate snowfall across higher elevations. The 00Z HREF grand
ensemble and its individual members continue to focus today`s
precipitation across southern Montana. Areas of southern Petroleum
and Garfield Counties have the greatest chance of receiving at
least 0.01" of precipitation (20-50%) today. A frontal system
moves through late this afternoon, reducing ceilings from north to
south tonight with best chances for a stray rain/snow shower
mainly in north central North Dakota, but otherwise, just a simple
wind shift is expected with this frontal passage across northeast
Montana.
From Thursday, the now cutoff low hangs around the Southwest US,
setting up a quasi-omega block, resulting in a quasi-stationary
ridge across much of the US Northwest and Canadian West coast. The
northwest flow around this ridge is progged to remain far enough
east to keep the CWA dry through the start of the upcoming week.
The trickiest part of the forecast will be in the from Days 7-9,
where ensemble clusters start showing the breakdown of the ridge
over the Northwest US, with the main difference being how the
eastern CONUS trough presents itself. Cluster 1 (50% of ECMWF
ensemble members) of 500 hPa heights shows a more anomalous
lowering in heights across New England, resulting higher heights
across eastern Montana, while Cluster 2 (57% of GEFS members)
shows a secondary trough over Hudson Bay being more anomonously
lower in heights, resulting in this anomonously lowering in
heights to have more influence across our CWA. We`ll keep
monitoring this spread in solutions and how this may affect
temperatures and QPF as we head into the latter-half of March.
-Enriquez
&&
.AVIATION...
UPDATED: 0815Z
FLIGHT CATEGORY: VFR today becoming MVFR tonight
DISCUSSION: Scattered light rain/snow showers mainly remain south
of KJDN and KGDV. A weak frontal system passage from north to
south, beginning from 1800 MDT will bring a lower cloud deck,
resulting in dropping ceilings as low as 500 to 1000ft, with areas
across the far MT/ND border region seeing even lower ceilings,
increasing to above 2000ft by Thursday afternoon.
WINDS: Light and variable this morning, becoming more 10-15kt
from the NW through Thursday morning.
-Enriquez
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
weather.gov/glasgow