Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/11/20
Area Forecast Discussion
National Weather Service Columbia SC
1035 PM EST Thu Dec 10 2020
.SYNOPSIS...
High pressure will provide dry weather and warming temperatures
through Saturday. A series of cold fronts will move through the
region next week supporting a periodic chance for rain. This
pattern will bring cooler weather than in the near term, though
still near normal for the time of year.
&&
.NEAR TERM /THROUGH TONIGHT/...
For much of the night, the atmosphere will continue to have
limited moisture, winds will be light to calm, and skies mostly
clear. However late tonight, closer to Friday morning, shallow
moisture off the Atlantic will be pushing inland on light
easterly winds and is expected to move into the eastern and
central Midlands by sunrise. In addition, some moisture will be
moving up the Savannah River valley towards the CSRA. Models
have been trending more towards some areas of dense fog possibly
developing between 08z-09z lasting through 13z-14z, especially
in the eastern and southern Midlands, and portions of the
southern CSRA. Currently still have mention of patchy fog
developing late tonight in the forecast, but this will need to
be monitored overnight for development of denser and more
widespread conditions. Temperatures will fall down into the
lower 40s to upper 30s, but may stabilize as the moisture moves
in and possible cloudsand fog form.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY/...
Surface high pressure will be near or over the Mid Atlantic
States on Friday and Saturday. Dry weather is anticipated
through the daytime on Saturday. Deep south to southwest flow
will keep temperatures above normal. High temperatures will be
in the mid 60s to lower 70s both days. Lows Friday night will be
slightly warmer in the low to mid 40s as clouds begin to
increase.
&&
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
An upper level shortwave trough will lift from the Ozarks into
the Ohio River Valley by late Saturday. The associated cold
front will slowly push through the Deep South and Southeast
overnight. With the stronger upper level dynamics far north of
the region and limited moisture advection, any showers
overnight should be scattered. Dry air will push into the
forecast area on Sunday as the front moves east. Daytime temps
should be similar to the previous few days with highs in the mid
60s to low 70s.
The next upper trough will swing into the southern US on Monday.
Surface low pressure will develop to the south and west of the
FA and move through the region quickly. Moisture will be deeper
with this system and supports likely PoPs on Monday. Another
upper level trough will follow suit mid-week with dry weather
expected between systems. Moisture appears to be more shallow
with the second system and may not bring as much rain to the
area as the earlier system. Dry weather will return late this
week as the trough and associated surface low lift out of the
region.
From Monday through the remainder of the period, temperatures
should generally be near normal.
&&
.AVIATION /04Z FRIDAY THROUGH TUESDAY/...
High confidence in VFR conditions all terminals through 03z-06z
then possible IFR or LIFR in stratus and or fog 08z- 14z time
frame.
High pressure over eastern VA and NC extending into the area
will move offshore overnight. Skies clear this evening but as
onshore flow develops late tonight, low level moisture will
advect into the area. The latest lamp and mos guidance are now
indicating some restrictions late tonight with stratus and fog.
Support from HRRR and NBM. Although cross-over temps still low,
strong nocturnal cooling at least through the evening may
increase fog threat. Based on the latest data...went a little
lower on visibility late tonight and early Friday morning and
introduced a low ceiling at terminals except DNL with IFR
conditions and possible LIFR at OGB/AGS. Restrictions should
improve by 15z with mainly clear sky and light and variable
winds.
EXTENDED AVIATION OUTLOOK...A cold front will move into the
region Saturday night and Sunday with ceiling and visibility
restrictions possible. Restrictions at times may linger into
Monday.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
&&
$$
Area Forecast Discussion
National Weather Service Dodge City KS
512 PM CST Thu Dec 10 2020
...Updated Aviation Discussion...
.SHORT TERM...(This evening through Friday)
Issued at 343 PM CST Thu Dec 10 2020
Thick cirrus clouds continued to push northeast out across western
Kansas this afternoon ahead of a rapidly ejecting upper low centered
across west-central/northeast New Mexico. Monitoring regional radar
mosaic and surface observations, there is more bark than bite as
only one observation was showing rain on the southern High Plains,
that being Dalhart, TX on the 21Z ob. The upper low will continue to
shear out and weaken tonight as it moves northeast, largely due to
the upstream kicker that was digging into the Great Basin region.
Therefore, the precipitation episode during the Tonight period will
not be much of anything at all and confined to areas of mainly far
west central Kansas. The latest HRRR does show light accumulating
precipitation finally commencing around 04Z with more farther west
across southeastern Colorado.
As the 700mb deformation axis improves slightly after 06Z, the
southwest to northeast axis of precipitation should become better
organized with light accumulating snow covering a larger portion of
mainly far west central and northwest Kansas by daybreak Friday. The
700mb development will shift east into north central Kansas later in
the day Friday, and this is where the focus for additional light
snow will be. This is expected to clip our far northern counties of
Ellis and Trego, but even this is starting to look less and less
impressive. Nevertheless, we will continue to carry one half to one
inch of snow generally northwest of a Lakin to Ness City to La
Crosse line.
by Friday afternoon, the 700mb low and greatest area of
ascent/saturation will slow down if not stall out for a bit across
north central KS as it starts to feel the influence of the next,
stronger upstream mid level potential vorticity anomaly. The
resultant area of greater precipitation (in the form of mainly wet
snow) late Friday is expected to be just northeast of Ellis County
outside of our forecast area, but this will continue to need to be
watched. Otherwise, that will be it for this first storm system
with the remainder of Friday being cloudy/mostly cloudy in a north-
northwest wind 15 to 20 mph.
.LONG TERM...(Friday night through Thursday)
Issued at 343 PM CST Thu Dec 10 2020
Two more storms are poised to move across the Western Plains through
the Long Term period. The next storm Saturday Night into Sunday
could prove to be quite the snow-producer as it`s development in all
levels of the troposphere will be a bit more impressive and focused,
leading to greater upward vertical motion, snowfall rates, and storm
total amounts. The three major global models are all showing a
fairly similar solution of light to moderate snowfall extending from
eastern Colorado southeast across southwest Kansas, across
northern/eastern Texas Panhandle into much of Oklahoma. As is always
the case, the devil is in the details, but it stands to reason that
some portion of our forecast area may see 3+ inches of snow with
this late weekend system. This would lead to moderate impacts,
especially if snowfall rates are pretty high (1/2 inch per hour or
greater). There is very high confidence that the entire late weekend
storm will be in the form of all snow.
Yet another storm is showing up early next week in this active
regime. Since this is 5+ days out, this particular storm has a
tremendous amount of uncertainty, although there is some run-to-run
consistency in the ECMWF model of fairly robust mid-latitude cyclone
development across the Central Plains potentially impacting
southwest Kansas with more winter precipitation (with a stronger
north wind).
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 505 PM CST Thu Dec 10 2020
Moisture and lift will tonight as an upper level trough exits the
Rockies and moves out into the Central Plains. Initially this
evening mid level moisture will be on the increase but after 04z
an area of low clouds (1500 to 3000ft AGL) will begin to spread
across southwest Kansas. These low clouds will thicken and lower
through the remainder of the night and linger through the day on
Friday based on the latest BUFR soundings. Ceilings are expected
to fall below 1000ft AGL after 09z Friday. Along with the increase
in low level moisture there will be a chance for some light rain
or light snow, especially between 06z and 18z Friday. The winds
overnight and Friday will be northerly at 10 to 15 knots.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 31 35 24 40 / 30 30 10 0
GCK 29 34 21 38 / 40 40 20 0
EHA 30 36 21 41 / 30 30 10 0
LBL 29 36 21 40 / 20 20 10 0
HYS 31 33 24 38 / 40 50 40 0
P28 34 40 28 42 / 20 20 10 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Umscheid
LONG TERM...Umscheid
AVIATION...Burgert
Area Forecast Discussion
National Weather Service North Platte NE
534 PM CST Thu Dec 10 2020
.SHORT TERM...(This evening through Friday night)
Issued at 322 PM CST Thu Dec 10 2020
The models are coming into better agreement with a forecast solution
for the expected snow across the cntl Plains tonight and Friday. The
NAM and SREF have trended south favoring southwestern Nebraska. The
snow forecast leans on the short term model blend for 1 to 2 inches
of snow south of Interstate 80, including srn Custer county. This
forecast might be a little generous given the RAP is suggesting the
forcing will be even farther south, mainly across KS but the HREF is
close to the operational forecast favoring southwest Nebraska as
well as KS.
The temperature forecast tonight and Friday night continues to lean
on the short term model blend plus bias correction. This forecast
keep temperatures on the warm side of the forecast envelop tonight
and Friday night. Cloud cover should limit radiational cooling
effects. The guidance blend is in place for Friday`s highs, which is
slightly cooler than the short term model blend.
.LONG TERM...(Saturday through Thursday)
Issued at 322 PM CST Thu Dec 10 2020
The models are in good agreement carrying an upper level low
through Nebraska Saturday. This low is currently off the coast of
British Columbia. The models suggest the potential for some light
snow affecting the Panhandle and swrn Nebraska Saturday night. Less
than an inch accumulation is in place. The NAM soundings shows the
cold pool with sub-30C temperatures at h500mb steepening lapse rates
and cooling the column to saturation. 30 POPs are in place across
swrn Nebraska and the srn Panhandle. It is possible this snow could
spread farther east according to the NAM but the SREF, GFS and ECM
will keep this snow farther west, mostly across WY and Colo.
The forecast is dry after Saturday night but the models are coming
in stronger with a reinforcing cold front Monday night. Snow
chances, currently less than 20 percent, may ramp up with later
forecasts.
Temperatures in the extended forecast are cooler and this is the
result of the stronger push of cold air moving in next week. The
upper level pattern is showing signs of becoming more progressive
and active. This is the basis for cooler temperatures which are near
or slightly below normal through Tuesday. A warming trend is
expected Wednesday and Thursday with highs in the 40s.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 534 PM CST Thu Dec 10 2020
A storm system crossing the central Plains will bring wintry
conditions to the region beginning early Friday morning. MVFR cigs
will continue for much of the forecast period for southwest
Nebraska (including KLBF) as light snow develops around 11/12z.
Expect brief drops to IFR cigs and visby mid to late morning. Northern
Nebraska will likely remain dry, although cigs will also drop
there. Winds will be primarily out of the north around 10 kts.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...CDC
LONG TERM...CDC
AVIATION...Snively
Area Forecast Discussion
National Weather Service Marquette MI
641 PM EST Thu Dec 10 2020
.SHORT TERM...(This evening through Friday)
Issued at 357 PM EST THU DEC 10 2020
WV imagery and RAP analysis indicated a split flow pattern with a
shortwave through northwest Ontario. At the surface, a
trough/front extended southward from the west end of Lake
Superior. Light southerly flow prevailed through Upper Michigan
with temps well into the mid 40s while brisk northerly winds were
moving in behind the trough. Although clearing had developed over
the southwest half of Upper Michigan, clouds were quickly
approaching as the trough moves in.
Tonight, as winds become northerly and low level moisture increases,
expect potential for some light pcpn. Even with little or marginal
instability as 900 mb temps fall to -6C, upslope flow into the
higher terrain may result in some drizzle changing to fzdz as temps
drop overnight. Ice nuclei will likely be scarce as most of the
moisture remains at or below -8C. Untreated roads could become
slippery even with a brief period of frozen pcpn. With low clouds
moving in, kept min temps toward the higher end of guidance.
Friday, CAA will continue with 900 mb temps dropping to around -9C
as winds veer to the ne or nne. Any fzdz that develops may become
mixed with or change to light snow showers or flurries. Temps will
drop but still remain above normal with highs from the lower 30s
north to the mid and upper 30s south and east.
.LONG TERM...(Friday night through Thursday)
Issued at 429 PM EST THU DEC 10 2020
Cut off upper level low will eject out of the central plains area
and become absorbed with part of the southern stream flow as its
trajectory continues to be modeled towards the Great Lakes area.
Model guidance is in solid agreement now with timing and placement
of surface low. The mid-latitude cyclone will mature over the
southern Lower Peninsula of MI, bringing our area some gusty winds
by late Saturday. Majority of the the precipitation will stay to our
south and southeast. This will continue the trend of well below
normal snowfall for the month of December as we are near 12.5 inches
below average for the MQT office. Increased the chance of snow
showers over our Keweenaw Peninsula to Ironwood regions as north to
northeast winds will take hold on Saturday. However, the
accumulation looks to be low despite persistent winds over that
region. Taking a quick look at internal NWS WPC ensembles, the
western forecast zones of the U.P. have a mean average closer to 1
inch of snow whereas the eastern and southern zones of the U.P. have
a mean average of 2 inches. Not a huge difference, but it lines up
nicely with the evolution of the weather system bringing increased
chances of snow showers this weekend, but not amounting to much for
the area overall. The weather system will move to the northeast and
help usher in continued pulses of cooler air, which will keep the
temperatures near seasonal averages
An additional shortwave disturbance will make its way over the
region by Monday. This will bring another round of light snow
showers across the region and another impulse of cold air over the
CWA. Temperatures at 700mb will be in the -16C to -20C range, which
will certainly keep it feeling colder for the afternoon highs to
start the week. Additionally, the impulses of shortwaves will
continue with another weak disturbance moving across the region
Tuesday afternoon into Wednesday morning. Lake effect snow showers
are certainly possible with this shortwave through Wednesday.
Weak atmospheric ridge begins to amplify over the central to eastern
CONUS, allowing temperatures to moderate slightly beginning Thursday
of next week. Would not be surprised to see afternoon highs start
creeping up above the freezing mark to end out the week, which would
put our region back into slightly above normal readings with regard
to temperatures. This lines up nicely with the CPC 8-14 day outlook
of above average temperatures/precipitation favored for the Great
Lakes region.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 641 PM EST THU DEC 10 2020
A cold front will reach CMX and IWD around 01Z and SAW around 02Z
tonight. Cigs are expected to quickly drop into the IFR range within
an hour or two behind the front and may briefly drop into the LIFR
range. Cigs are expected to gradually improve Friday morning and
should linger in the MVFR range throughout the day. Winds
veering to northerly result in upslope flow resulting in a chance of
drizzle reducing visibilities to MVFR around 03-06z. Patchy drizzle
may change to freezing drizzle as temperatures fall overnight and
northerly winds may become gusty at SAW on Friday morning.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 357 PM EST THU DEC 10 2020
Winds will veer around to north tonight as a cold front sweeps
across the lake. 20-30 kt northerly winds are likely behind the
front into Friday morning. Winds across the lake should subside
below 20 kts by Friday evening. Models have remained consistent with
the track of the low pressure system that will be moving through the
Great Lakes Saturday meaning northeast winds Saturday and Saturday
night should remain in the 20-30 kt range with gales still remaining
unlikely. Winds are expected to back around to NW and diminish to
around 20 kts for Sunday and Monday.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...JLB
LONG TERM...BW
AVIATION...EK
MARINE...JLB
Area Forecast Discussion
National Weather Service Pueblo CO
750 PM MST Thu Dec 10 2020
.UPDATE...
Issued at 735 PM MST Thu Dec 10 2020
Radar/satellite trends this evening reveal snowfall has been slow
to pick-up over the I-25 corridor and plains, while light to
moderate snow was occuring farther west over the San Luis Valley
and Continental Divide. New 00z NAM and recent runs of the HRRR
have become very pessimistic for accumulating snow along and east
of the mountains, with accums less than an inch along I-25 and in
Teller county, and only a couple inches farther west over the
Sangres/Wets. Models have increased snowfall somewhat over the
eastern half of the San Luis Valley, where swly orographic flow
will help somewhat. Will keep current set of highlights in place
for now, but will make some downward nudges to snowfall in the
I-25 corridor while bumping up accums in the San Luis Valley a
couple inches.
&&
.SHORT TERM...(This evening through Friday)
Issued at 248 PM MST Thu Dec 10 2020
A shortwave trough will make its way across the region beginning
this evening bringing widespread snow across both the mountains and
the lower elevations. We have a Winter Weather Advisory in effect
over the eastern San Juan Mountains, the Sangre de Cristo
Mountains, the Raton Pass, and the Wet Mountains. Snow is expected
to begin over the eastern San Juans first, then northeasterly as the
night progresses. The one notable difference between this forecast
package and the previous forecast package is that we started the
Winter Weather Advisory over the Sangre de Cristo Mountains and the
Raton Mesa to a 5PM start time, as compared to an 8PM start time.
The reason for this is because higher resolution models are
resolving a relatively strong snow band forming over Raton Mesa,
which is expected to drop a quick 2 to 5 inches this evening and
into the overnight, beginning at around 5PM. The higher elevations
under the Winter Weather Advisory are expected to see 5 to 10 inches
of fresh accumulation.
The rest of the region is expected to get snow as well, but the
amounts are not expected to be high enough to warrant the issuance
of a Winter Weather Advisory. Keep in mind, though there isn`t an
advisory issued, roads can become slippery. So please be cautious,
especially during the Friday morning commute! A brief lull in
snowfall is expected across the adjacent plains during the morning
tomorrow, but by mid afternoon, light snow will begin once again.
There is a bit of concern that some snow bands will form off of
Pikes Peak area and the Wet Mountains, but confidence is low on that
occurring. The evening and night crew may have a better handle on
that happening tomorrow afternoon.
The mountain valleys 2 to 4 inches, with the heaviest snowfall
amounts expected to fall during the overnight tonight. Colorado
Springs proper is expected to see 1 to 2 inches this evening through
tomorrow, but further north and to the west, snow amounts increase
to 2 to 5 inches. The plains are expected to range from .5 to 2
inches of snow, with the lesser amounts near the Kansas border.
Pueblo proper is expected to see around an inch of snow.
.LONG TERM...(Friday night through Thursday)
Issued at 248 PM MST Thu Dec 10 2020
Models continue to stay in agreement, sending a broad upper-level
trough over our area Friday night into Saturday. The GFS, EC and NAM
all have the initial trough moving out of our area pretty quickly
overnight before we get a brief break in the weather early Saturday.
Snowfall during the first part of the period is expected to remain
on the light side.
The upper-level low associated with the strongest section of the
trough will move in Saturday evening, driven by very strong
northwest flow aloft in the jet. The next shot of snow to the area
is expected to set in sometime Saturday evening and last through
Sunday morning, but the speed of the system differs slightly between
the GFS, EC and NAM. The GFS and EC have begun to agree more on a
solution the last few runs, placing the low and the main section of
the trough axis to our west. However, the EC places the trough
slightly to our north as well Saturday evening, before digging south
clear into Texas and lasting into late Sunday morning. The GFS
currently has the system moving at approximately the same speed, but
not digging quite as far south and giving us less widespread
snowfall into Sunday morning. To the contrary, the NAM kicks the
upper-level low out a little bit faster, and currently has the least
amount of precipitation forecasted among the three models. Have
stuck closer to the GFS and EC solution, and therefore are expecting
several inches of snowfall over the mountains Saturday night before
transitioning to the plains by morning. While snowfall will be
fairly widespread, current forecasted totals look light although
will have to monitor going forward for the possibility of any heavy
snow bands that could form. With snow on the ground being a very
likely occurrence Sunday morning, low temperatures for the day have
been taken down a few degrees across the board, with temperatures at
or below 35 across the vast majority of our area.
A lower confidence forecast remains in place for the rest of next
week, as conditions are expected to even out somewhat on Monday, the
flow becoming more zonal ahead of the next major trough that is
expected to translate across the area Tuesday, bringing us our next
chance at snowfall.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 248 PM MST Thu Dec 10 2020
VFR conditions are expected for the next few hours, but ceilings
will fall and snow will also begin to fall during the evening for
KALS, KCOS, and KPUB, see the TAF for expected timing. MVFR will be
likely during these time periods, but IFR is possible. During the
morning, there will be a brief lull in snowfall, increasing
conditions to VFR, but flight categories are expected to fall once
again to MVFR during the late morning and afternoon. Conditions
will improve back to VFR later in the evening.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 11 PM MST Friday for COZ066>068-
072>075.
Winter Weather Advisory from 11 PM this evening to 11 PM MST
Friday for COZ079-080.
&&
$$
UPDATE...PETERSEN
SHORT TERM...SKELLY
LONG TERM...GARBEROGLIO
AVIATION...SKELLY