Forecast Discussions mentioning any of
"ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 01/29/20
AREA FORECAST DISCUSSION
National Weather Service Hastings NE
951 PM CST Tue Jan 28 2020
Issued at 948 PM CST Tue Jan 28 2020
Updated the dense fog advisory to begin earlier tonight as we have
sites that have hit 1/2SM to 3/4SM already, with this occurring
more often and decreasing with time. Opted not to expand the
advisory east as GLAMP trending not as foggy in our east and SREF
and HRRR indicate that we will not fog up as much there as well.
With cloudy conditions, I went closer to CONSRAW and raised our
low temperatures to the upper 20s for Wednesday morning.
.SHORT TERM...(This evening through Wednesday)
Issued at 155 PM CST Tue Jan 28 2020
Aloft: Progressive fairly low-amplitude flow conts over the CONUS
per aircraft wind obs and RAP tropopause analyses. They depicted
a narrow shrtwv trof from SA all the way down to TX. A shrtwv
ridge was over the Rckys...with the next trof along the W coast.
The trof currently over the Plns will cont moving E and cross the
CWA this eve. The Rckys ridge will diminish in amplitude and move
thru tomorrow. The trof along the W coast will be discussed below.
Surface: 1026 mb high pres was over ON and extended down to IA. A
sfc trof coincided with the mid-upr lvl trof. This trof will cross
the CWA this eve as well and then dissipate tomorrow. The ON high
will strengthen a bit and slide into QB...but still extend SW to
IA. The pres grad over NEB/KS will be very weak thru tomorrow.
Rest of this afternoon: Patchy -SN has been falling with VSBYs
mostly between 1 and 3 miles. The back edge of this snow will
gradually progress E...bringing the snow to an end W of Hwy 183.
The leading edge of the snow will also progress E with -SN moving
into the Hwy 81 corridor.
The snow is light and melting on contact with roads. With temps
hovering right around frzg...there will be little or no accum.
Skies are sunny immediately W of the upr trof. Clds will begin
breaking up W of Hwy 183.
Tonight: Patchy -SN will linger into the eve along and E of Hwy
281. Again...with little or no accum.
Believe we will have a fog problem on our hands tonight. Low
stratus will not be scoured out of the entire CWA. This low cld
cover and the precip has kept dwpt depressions very small today.
Winds will be very light or even calm tonight. As temps begin
falling after sunset...this is a recipe for stratus CIGs to
descend (where stratus remains) or dense fog to form where clds
Have issued a Dense Fog Advisory for the W 2/3 of the CWA (along
and W of Hwy 281). It may take some time for CIGs to lower...but
believe this will need to be expanded to encompass the entire CWA.
We`ll let the next couple shifts monitor the trends. Regardless...
have strongly worded the fcst to indicate this potential.
Kept fcst lows on the higher side of the guidance envelope...but
did not go as high as I desired to remain in collaboration
thresholds with neighboring offices.
Wed: Foggy thru late morning...and while we will see gradual
improvement thereafter...it could linger well into the day from
the Tri-Cities N and E. Most the CWA will remain cldy...but the
stratus and fog should erode from the edges. Since it will be
sunny over Wrn NEB/KS...that means the best chance for sunshine
developing will be S and W of the Tri-Cities.
The clds will keep temps from warming much where there is no
sunshine. Wrn and Srn counties should at least get to 40F and
possibly into the low 40s.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 155 PM CST Tue Jan 28 2020
Aloft: The flow will become a bit more amplified thru early next
wk...but still remain progressive. The trof currently along the W
coast will split and the Nrn piece will cross NEB/KS Thu. The
passage of this trof will shift the flow to NW Fri. Significant
heights will occur heading into the wknd as a broad ridge builds
over the Wrn USA but conts moving E. NW winds over NEB/KS will
become W Sun as the ridge crests overhead. Winds will then become
SW Mon as the next fairly substantial Pac trof moves onshore and
approaches the rgn. This trof is fcst to cross the Plns Tue with a
The last 2 runs of global mdls (GFS-FV3/EC/CMC/UKMET) are
generally in good agreement/tightly clustered. That said...there
are a couple runs that indicate the possibility of a closed low at
the base of the trof over KS Mon or Tue. That potential will need
to be monitored.
Surface: A sfc trof will move thru Thu in concert with its upr-
lvl reflection. Another sfc trof will slide thru Fri associated
with low pres heading E thru Srn Canada. Deep low pres will move
into SW Canada Sat and this will induce warm frontogenesis down
the entire lee of the Rckys...and downslope winds strengthen in
its warm sector. The strength of this low will increase temp
extremes both ahead of and behind it. The warm front will cross
the CWA Sat and we`ll remain in the warm sector Sun as the low
heads E thru Canada. The trailing cold front will slam thru here
Sun night or Mon with a surge of much colder air. Chilly high pres
over the Wrn USA will then build-in Tue.
Temps: We`re going to be stuck with lots of clds over the rgn
thru Thu. That will keep the diurnal range of temps suppressed
(cooler highs and milder lows). That should change Fri with a big
2-day warm-up in store for Sat-Sun. There will be an unusually
warm plume of air developing and spreading over the Plns. 850 mb
temps could be as high as +18C. Some guidance says our fcst is not
nearly warm enough! As of this fcst we are now advertising highs
ranging from 45 near OLU to 60 over the SW fringe of the
CWA...with low 50s in the Tri-Cities. Sun there is bigger bust
potential. We`re indicating 50s over the NE 1/2 of the CWA and 60s
over the SW 1/2. It`s psbl that mid-upr 60s could flood the
entire CWA. Even if that doesn`t pan out ...we`re still looking at
a very very mild wknd. Tue temps could be locked in the 20s for
highs with widespread cloud cvr.
Precip: Nothing significant in the offing. The 06Z and 12Z NAM
suggest there could be a touch of -SN Thu AM ahead of that shrtwv
trof. The 12Z EC lends a little support. The GFS doesn`t develop
any QPF until it`s E of the CWA. This minor potential is not
currently in the fcst...but it may need to be added if confidence
increases. If anything falls...it is looking very minor (less than
0.10 QPF) just acrs our NEB counties. The fcst is dry until Mon
night and even that`s not looking that good...with very
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Wednesday)
Issued at 558 PM CST Tue Jan 28 2020
Ceilings will be difficult off the bat as there appears to be a
hole in the MVFR stratus, but this should fill in and lower over
time. I expect visibility to lower quite a bit over time as the
stratus descends. Winds will remain light.
NE...Dense Fog Advisory until 10 AM CST Wednesday for NEZ039-040-046-
KS...Dense Fog Advisory until 10 AM CST Wednesday for KSZ005-006-017-
Area Forecast Discussion
National Weather Service Pittsburgh PA
145 PM EST Tue Jan 21 2020
After scattered flurries today, dry weather is expected through
Thursday under building high pressure. Precipitation chances return
Friday through the weekend with crossing low pressure.
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Areas of stratocu and flurries continue this afternoon with moisture
below a temperature inversion, and cold nrly flow off the lakes. The
clouds and flurries will slowly erode by this evening with increasing
.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/...
Ridging should maintain dry weather as it moves east across the
region through the period. A gradual warming trend is also expected,
with temperatures above average by Thursday with SW flow aloft as
the ridge axis shifts east of the area.
.LONG TERM /FRIDAY THROUGH TUESDAY/...
An upper low is progged to track E from the Upper Midwest, reaching
the Upper OH Valley region Friday night and Saturday. Rain and snow
chances should increase with the approach and passage of the low.
Snow chances should continue Sunday as the upper low tracks to the E
Coast, and a shortwave trough rotates around it. Another trough in NW
flow aloft should maintain slight to low precip chances Monday.
Temperatures are expected to average near or a few degrees above
.AVIATION /19Z TUESDAY THROUGH SUNDAY/...
Recent AMDAR soundings suggest shallow, low-level moisture remaining
trapped beneath a subsidence inversion. This, combined with backing
flow to the nw in response to a crossing shortwave is likely to
maintain MVFR in lake-enhanced stratocu and flurries until
increasing subsidence promotes VFR later this afternoon.
Restrictions are likely again by Fri with the approach of low
Area Forecast Discussion
National Weather Service Great Falls MT
750 PM MST Tue Jan 28 2020
Snowfall lingers in our southwest counties as a major shortwave
trough digs deep into the western U.S.. This trough will move south
and eastward along the United States/Mexico border, until it exits
The Treasure State. A strong area of upper level higher heights is
currently located over The Pacific Ocean, with the associated ridge
stretching northeastward into northern Alberta. This ridge enters
the Montana western border on Wednesday favoring fair weather.
Inherited forecast is looking good; therefore, no updates are
required, at this time.
A Pacific cold front will bring rain and snow to the mountain
areas of southwest Montana through late tonight. Drier
conditions are expected for Wednesday, but a series of disturbances
will bring increasing winds and mainly mountain precipitation to
the region Wednesday night through Friday, with Saturday likely
being the warmest and windiest day of the week.
Rest of this Afternoon through Wednesday...
Digging shortwave continues to dive southeast this evening across
the Northwest US just ahead of a strong upper high pressure ridge
aloft. The main focus for accumulating snow will remain over
Southwest Montana through late tonight. Forecast snow amounts
there are a bit lower than from previous forecasts in the valleys,
but they are a bit higher in the mountains (mostly above mountain
pass level). Above 7500 feet, mostly 4 to 8 inches of snow is
expected, but accumulations will likely be less than 2 inches
below there. A weak cold front associated with the disturbance
may bring a few rain/snow showers to the plains, but they will be
isolated at most and not produce much precipitation. Precipitation
will start moving out of the area with the disturbance after
midnight, and high pressure aloft will help bring clearing skies
and breezy westerly downslope winds for Wednesday. This
disturbance will not cool temperatures much, keeping highs for
this period mostly in the 40s and lows in the 20s, both above
Wednesday Night through next Tuesday... In more of a northwest flow
aloft, two more disturbances may bring precipitation to the area,
one Wednesday night and the other on Friday. Main impact with the
Wednesday night disturbance will be the potential for some light
snow and freezing drizzle along and west of the Continental
Divide, however at this time no significant impacts are expected.
A broad high pressure ridge will be building into Montana on
Friday, which combined with a strong north Pacific low moving into
Canada will help to initiate a powerful westerly jet stream aloft
for late Friday through Saturday. Confidence has become quite high
in widespread strong to high winds developing late Friday but
especially Saturday, with a moderate to high-end wind event
possible. With confidence in high winds about as high as one can
get for the Rocky Mountain Front this far out, we have issued a
High Wind Watch for the Rocky Mountain Front. Additionally, we
will assess the need to expand the watch to include much if not
all of the north-central plains in later shifts. The warm
temperatures, at or near record highs Saturday, will also help
decrease relative humidity and increase fire danger on the
grasslands of the plains. Breezy and mild conditions will linger
into Sunday, but a strong Canadian cold front will move south
through the area during the afternoon and evening. This will bring
significantly cooler temperatures (likely going from 20 degrees
above normal on Saturday to 10 to 20 degrees below normal on
Monday), along with a chance for at least light measurable snow
for most areas. Will monitor this situation for possible winter
weather highlights. Temperatures will remain cool into Tuesday
under a northwest flow aloft in the wake of the cold front, but
there should be less of a chance for snow.
Updated 507 PM MST Tue Jan 28 2020 (29/00Z TAF Period)
KCTB, KHVR, KGTF, KLWT and KHLN will remain VFR throughout this TAF
period. KEKS and KBZN will dip into the MVFR range, while KWYS will
become IFR with possible LIFR conditions, overnight. Expect mountain
obscurations mainly in southwest Montana. Additionally, aircraft
icing is forecast.
.PRELIMINARY POINT TEMPS/POPS...
GTF 26 46 30 45 / 0 10 50 10
CTB 23 44 28 43 / 10 10 20 0
HLN 25 43 28 44 / 20 10 40 10
BZN 22 42 24 42 / 40 20 60 20
WYS 14 31 13 31 / 60 50 60 30
DLN 19 35 23 37 / 50 20 30 10
HVR 20 40 28 43 / 0 10 50 20
LWT 25 42 26 42 / 10 10 60 30
High Wind Watch from Friday evening through Saturday evening
Northern Rocky Mountain Front...Southern Rocky Mountain Front.