Forecast Discussions mentioning any of
"ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 04/25/21
Area Forecast Discussion
National Weather Service Great Falls MT
845 PM MDT Sat Apr 24 2021
.SYNOPSIS...
Periods of rain and mountain snow area expected today through
Monday night. The most widespread precipitation will occur tonight
and then again Sunday night into early Monday. High pressure
begins to build on Tuesday, with fair and seasonable weather
continuing through the second half of the week.
&&
.UPDATE...
Tweaked overnight temperatures down, just a bit, in some areas.
Also, increased winds a bit to come more in line with current
observations. The most significant changes made during this update
were increases to POPs and the lowering of snow levels. Current
QPF was updated with most current WPC guidance, new Snow Amounts
and Storm Total forecast grids were created, and the Winter
Weather Advisory was updated to lower snow level to 5000 feet from
6000 feet.
- Fogleman
&&
.AVIATION...
613 PM MDT Sat Apr 24 2021 (25/00Z TAF period)
Expect MVFR/IFR/LIFR conditions to prevail throughout this forecast
period in rain/snow/mist/fog and with low ceilings. Mountain
obscuration is forecast to occur for the duration of this TAF
period. Light winds are forecast at all airfields with the exception
of KEKS, where south southeasterly gusty winds will impact light
aircraft until 25/05Z.
- Fogleman
Refer to weather.gov/zlc for more detailed regional aviation weather
and hazard information.
&&
.PREV DISCUSSION...
/ISSUED 613 PM MDT Sat Apr 24 2021/
Remainder of this afternoon through Monday night...An approaching
weak shortwave and associated surface low continues to bring
increased cloudiness to the region this afternoon, though there
are more breaks in the clouds over the southwest. This has allowed
most lower elevation temperatures to reach the 40s and 50s.
Further north, a cool easterly flow has provided an abundance of
low clouds, flurries/drizzle for much of the day. Precipitation
chances will increase for all areas by this evening as the main
piece of energy and moisture move through the region. A slight
chance for a rumble or two of thunder remain possible over the
southwest through this evening as some modest instability builds
in. The suite of short term model guidance continues to suggest
that a band of heavier precipitation moves in this evening across
central Montana, including the Big and Little Belt mountain
ranges. The current winter weather advisories for elevations above
6000 feet in the Little Belt Mountains and for all elevations of
the Rocky Mountain Front and Eastern Glacier County still look
good. Other areas and mountain passes will receive snowfall, but
the advisory segments highlight those areas having higher
confidence in accumulating, or otherwise impactful snow
accumulations for travel and outdoor work or recreation.
Precipitation continues, but becomes more showery on Sunday.
However, the next upper level wave arrives Sunday night and will
cause another period of moderate rain and mountain snow over
Southwest Montana, along with more snow for the central mountains.
Another set of elevation based advisories will likely be needed
for these areas. There is also some concern for a brief period of
accumulation snow for the lower elevations of Judith Basin and
Fergus Counties. Ensembles means are generally calling for an inch
or less of snowfall for the Lewistown area, but each suite
contain a few members with up to 3 inches of snow. Expected 700 mb
temperatures on the warmer side (-4 -8C range) will likely limit
impacts unless a very heavy band of snow happens to develop.
Regardless, the situation will continue to be monitored for winter
weather impacts to travel sunday night/Monday morning across
Central and Southwest Montana. After some residual showers during
the day on Monday, drier conditions return Monday night. - RCG
Tuesday through next Saturday...A seasonable, generally fair, but
somewhat unsettled northwest flow develops through midweek, as we
become positioned on the downstream side of a broad upper level
ridge. Temperatures warm well above normal for the second half of
the work week as the aforementioned high pressure ridge moves in.
Ensemble solutions retain indications of another Pacific weather
system crossing the northern Rockies with periods of rain and
mountain snow. - RCG/PN
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 31 50 30 54 / 90 50 50 30
CTB 29 42 25 52 / 90 40 50 20
HLN 35 54 35 55 / 90 70 70 30
BZN 33 53 33 51 / 90 70 80 50
WYS 28 46 25 45 / 80 80 80 80
DLN 33 52 31 50 / 80 70 60 50
HVR 32 47 30 55 / 70 60 30 30
LWT 30 47 29 48 / 90 70 70 60
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 6 AM MDT Sunday Eastern Glacier...
Northern Rocky Mountain Front...Southern Rocky Mountain Front.
Winter Weather Advisory until 6 AM MDT Sunday Cascade...Judith
Basin...Meagher.
&&
$$
http://www.weather.gov/greatfalls