Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/10/21
Area Forecast Discussion...Updated
National Weather Service Billings MT
818 PM MST Tue Nov 9 2021
.UPDATE...
A fragmented upper trough was working through Washington and
northern Idaho this evening. Ascent on the front side of the
trough was producing an area of light showers over central zones
(away from downslope influences). Generally from Billings west,
downslope was ruling over ascent and precipitation was drying out
as it moves east. This will turn around later tonight as the main
trough axis sweeps across and overpowers the downslope. Main
locations for precipitation looks to be over the mountains (in
particular the northwest facing slopes) and locations from
Treasure to Big Horn counties. This handled pretty well in
existing forecast and will let ride. Temperatures were still
fairly mild with readings in the 40s and the cold front just west
of Billings. Temperatures will fall into the mid to upper 30s as
readings will be held up by west to northwest winds. Look for a
rain and snow mixture in lower elevations toward morning but
believe warm ground and winds will keep accumulations down.
Exposed surface, such as bridges and overpasses have the best
chance of getting a light accumulation, so keep that in mind for
the morning commute. TWH
&&
.DISCUSSION...
Tonight through Thursday night...
An upper trough will move eastward across southern Canada and the
northwestern US tonight and reach the northern Plains Wednesday
afternoon. This trough will bring a cold front across the area
this evening, with mountain snow showers and lower elevation rain
showers that change to snow showers tonight. Mid-level
frontogenesis and northwesterly upslope flow look to produce Snow
accumulations tonight of generally 1 to 6 inches in the
mountains (greatest in Beartooths). Given the northwesterly flow,
amounts should be lighter in the foothills due to lack of
upsloping from that wind direction, with snow accumulations less
than one inch. Downsloping will limit precipitation amounts
especially for areas northwest of Billings. The HRRR model is
reasonably showing precipitation forming over central areas late
this evening and then moving east/southeastward into southeast MT
and north central WY early Wednesday morning. Even in these areas
that are more favored to receive precipitation tonight,
precipitation amounts will be light, generally less than 0.1 inch.
There could be a few slick spots, especially on bridges and
overpasses, in Sheridan County Wednesday morning as the wet
surface from rain and snow could freeze as the air cools.
On Wednesday, the upper trough will move eastward into the
Dakotas. The precipitation will diminish over southeast MT, but
there will still be isolated to scattered rain and snow showers
over south central MT and north central WY from instability. This
pattern will also cause mid-level wind speeds to increase to
about 30-40 kt. Strong low-level lapse rates will facilitate a
windy day tomorrow as those mid-level winds mix down to the
surface. Winds will gust to 35-50 mph across the area, with the
strongest gusts expected in the western foothills, from Nye
northward to Big Timber and Harlowton and westward to Livingston. Winds
will subside somewhat Wednesday night with the loss of solar
heating and associated stabilization of the lower levels, but it
will still be breezy over southeast MT with gusts to 30 mph due to
a surface pressure gradient there.
Thursday, an upper low will deepen as it moves from ND to MN. As
this low deepens, winds aloft and the surface pressure gradient
will strengthen over southeast MT. This pattern should produce
gusts to 50 mph over southeast MT Thursday afternoon. The low will
move farther eastward Thursday night which will cause the surface
pressure gradient to weaken and thus winds will decrease through
the night with gusts to 30 mph possible there late Thursday
night. In addition, there will also be snow showers in the
mountains as a weak disturbance moves over that area but amounts
will be light.
Low temperatures tonight will generally be in the 20s and 30s,
then 20s Wednesday night and teens and 20s Thursday night. High
temperatures will be in the 40s to near 50 degrees Wednesday and
30s and 40s Thursday. RMS
Friday through Tuesday...
Unsettled weather looks to prevail through the extended forecast
with ensembles showing short periods of ridging followed by
shortwaves moving through the region in northwest flow.
Friday looks to be fairly dry with ridging over the region, before
beginning to break down on Saturday as a shortwave drops in from
the northwest. The wave will bring some chances for rain and
mountain snow, along with cooler temperatures into Sunday. Breezy
northwest winds look to spread over the area on Saturday as well. Snow
may linger over the mountains on Sunday in unstable northwest
flow. Ridging then looks to build in for Monday, before another
possible system drops in from the northwest on Tuesday, bringing
additional precipitation chances.
High temperatures are forecast to range from the 30s over the
east, to around 50 degrees over the west on Friday with mainly 50s
over the area on Saturday. Temperatures cool into the 40s on
Sunday, before warming back into the 50s on Monday and Tuesday.
Low temperatures in the 20s and 30s are forecast most nights. STP
&&
.AVIATION...
A clipper system dropping through the region will bring increasing
clouds and scattered rain and mountain snow showers to portions
of the area through tonight, along with a wind shift to the
northwest. Localized MVFR to IFR conditions are possible with the
shower activity, along with mountain obscurations. Otherwise, VFR
will prevail. Breezy northwest winds can be expected across the
area on Wednesday behind the clipper. STP
&&
.PRELIMINARY POINT TEMP/POPS...
Wed Thu Fri Sat Sun Mon Tue
-----------------------------------------------------------
BIL 035/048 029/044 027/048 039/056 036/049 036/057 041/056
52/J 21/N 11/B 23/R 32/R 21/E 24/R
LVM 027/043 024/044 029/051 039/054 034/051 037/058 039/053
72/J 12/J 12/O 23/R 33/R 11/N 24/R
HDN 033/050 027/044 022/048 035/057 031/049 032/058 036/058
72/W 21/N 11/B 24/R 32/R 21/E 23/R
MLS 035/048 028/039 019/040 031/053 029/046 031/052 034/053
42/W 10/N 01/B 33/R 21/E 11/E 12/R
4BQ 037/047 029/039 020/042 033/054 031/046 032/055 036/056
52/W 21/N 01/B 24/R 21/B 11/B 12/R
BHK 035/046 026/036 017/035 024/049 026/043 026/050 032/052
51/N 11/N 01/U 33/R 21/B 10/E 12/R
SHR 032/046 024/042 022/048 034/057 031/049 030/058 035/058
63/J 22/J 11/B 24/R 32/O 11/B 13/R
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...None.
WY...None.
&&
$$
weather.gov/billings
Area Forecast Discussion
National Weather Service Grand Rapids MI
708 PM EST Tue Nov 9 2021
LATEST UPDATE...
Update
.SYNOPSIS...
Issued at 257 PM EST Tue Nov 9 2021
- Fall Storm to bring Winds Thursday with Snow Showers over the
Weekend -
&&
.UPDATE...
Issued at 707 PM EST Tue Nov 9 2021
I have added fog, locally dense ,to our grids/forecast for late
tonight into early Wednesday morning in the I-69 area. This is the
result of the surface high coming overhead early Wednesday
morning, resulting in clear skies and light winds. In the boundary
layer we have a weak northeast winds. That is just enough to
bring some shallow moisture from Lake Huron into the I-69 area.
Since surface temperatures should be near freezing by then, that
has the potential of creating several hours of freezing fog. This
could be a travel issue if it happens. So for now, I have updated
the grids and forecast products to include this.
A side note to this, just about all of our that all of our high
resolution models are forecasting this fog and in the same area
(I-69). I have noted over the past few years ,when the NAM,
NAMNEST and RAP model all have dense fog in the same place at the
same time, it just about always ends up happening. Tonight that is
the case. So I am really concerned about this. Hence the forecast
update.
&&
.DISCUSSION...(This evening through next Tuesday)
Issued at 257 PM EST Tue Nov 9 2021
Weak f-gen bringing light rain/sprinkles this afternoon with most
precip evaporating in dry subcloud layer. This peels off to the
east this evening as cold front/sfc trough moves through.
Potential remains for a strong Fall storm Thursday with upper low
bringing snow showers into Saturday, with an uptick in the snow on
Sunday as a clipper/shortwave trough moves through.
Upper trough across the northern plains digs southeast on
Wednesday with surface cyclogenesis across the central Plains on
Thursday before the low occludes and begins to fill on Friday. The
deepening low will generate an isallobaric wind component that
may result in some strong gusty winds on Thursday.
We expect rain showers to break out Wednesday night as warm
advection wing arrives. The heavier rain then moves in Thursday
morning with the warm conveyer belt as moisture is drawn north
into the expanding circulation of the low. There are some fairly
strong environmental winds coincident with this feature so any
deeper updrafts in embedded convection could bring wind gusts over
40 mph. Fortunately, instability is limited so we are not
expecting widespread wind damage, but scattered power outages are
possible. The wind threat continues in the cold advection pattern
Thursday afternoon, with forecast wind profiles showing 35 to 40
mph in the mixing layer during the afternoon over much of the
forecast area and 45 mph gusts possible along Lake Michigan.
There looks to be a break in the precip Thursday night as the dry
slot is over Lower Michigan, then lake-enhanced snow showers move
in on Friday as deeper moisture with the upper low moves in.
Southwest flow at this time suggests our northwest zones from
Muskegon County to Mason County and inland of there will see the
possibility of accumulating snow as strong low level convergence
in this area could produce snow rates able to overcome marginal
surface temperatures.
As the axis of low pressure shifts east Friday night, the flow
goes west and the better surface convergence shifts south along
the coast. Wet bulb zero heights diminish to near the surface on
Friday night and continue there over the weekend, with some areas
getting measurable snow sticking to the ground. We expect p-type
to be mostly snow except right along Lake Michigan where the
residual warmth of the water may be enough to keep a mix with rain
and prevent accumulations.
An uptick in the snow is expected on Sunday as the core of the
cold air moves through with the potential for a clipper type low
or sharp upper shortwave trough enhancing the snow. This feature
is shearing out as it gets absorbed into the circulation of the
big upper low with snow showers diminishing on Monday as it moves
east and heights begin to rise. A general 1 to 3 inch snow event
could be expected by that time.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 645 PM EST Tue Nov 9 2021
Currently skies are clearing over all of our TAF sites but the
I-94 TAF sites still have cigs just above MVFR (3500 ft). There is
some drier air moving in so all sites should be clear or nearly so
by 03z-05z. Winds will be light and variable.
Then we have a fog issue. Seems with winds being calm and skies
clear an a northeast wind in the boundary layer this is enough
low level moisture from Lake Huron to result in dense fog for our
I-69 and I-94 TAF site in the 09z to 12z time frame. I am not 100%
on this but since the RAP, HRRR, and NAM are all showing it and
typically when they all show this happening it does end up
happening I put it in those TAF sites. This fog should be shallow
and should mix out quickly after sunrise, even in November.
Winds will be more or less east or east northeast at the surface
on Wednesday. High and mid clouds will increase during the
afternoon as the frontal cloud band gets closer to this area.
The system clouds move in late in the day and rain should follow
after 04z on Thursday.
&&
.MARINE...
Issued at 257 PM EST Tue Nov 9 2021
We will not issue a Gale Watch is it appears winds are marginal
and although there could be some gusts to 35 to 40 knots Thursday,
the duration is not expected to be more than a few hours. We will
assess this again on the midnight shift, but at this point it
looks like a long duration Small Craft Advisory from Wednesday
night into the weekend will be the way to go.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...None.
&&
$$
UPDATE...WDM
SYNOPSIS...Ostuno
DISCUSSION...Ostuno
AVIATION...WDM
MARINE...Ostuno