Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 02/16/25
Area Forecast Discussion
National Weather Service Columbia SC
745 PM EST Sat Feb 15 2025
.SYNOPSIS...
A strong cold front will move through the region Sunday morning.
Widespread showers and isolated thunderstorms are expected along
and ahead of the front. Strong gusty winds are expected through
the day. The winds will slowly subside Sunday night as the
pressure gradient relaxes. A cool and dry air mass will settle
over the area through Tuesday. A low pressure system will move
into the southeastern States mid-week with wintry precipitation
possible across the northern Midlands. A cold and dry air mass
will build into the area late week with below normal
temperatures continuing into next weekend.
&&
.NEAR TERM /UNTIL 7 AM SUNDAY MORNING/...
Key Message(s):
- Scattered showers continue this evening
A strong cold front will move across the Deep South tonight and
enter into the forecast area from the west around day break.
Tonight, ahead of the front, isentropic lift will lead to
isolated or scattered showers. However the deeper moisture
shifts north of the FA late tonight so shower activity should be
lower than earlier in the day. A tight temperature gradient
over the area will slowly erode through the night as the front
approaches. Expect a non-diurnal temperature trend with lows for
the night likely having already occurred. Ongoing convection in
GA will be very near or have entered the CWA from the west at
the end of the near term. Winds will pick up around sunrise but
the strongest winds are expected past 7 AM, covered further in
the short term section.
&&
.SHORT TERM /7 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/...
Key message(s):
- Windy conditions and some strong-severe thunderstorms are
likely between 8am and noon. Breezy conditions will linger
through the afternoon.
By 6am Sunday, a strong front will be approaching the area from the
west. A wide swath of strong south-southwesterly 850mb winds will
proceed the front itself, with guidance consistently showing 60+
knots throughout Sunday morning. Consequently, the gradient surface
winds will steadily strengthen throughout early Sunday morning ahead
of the convective line itself. Winds 25-35 mph are likely ahead of
the line, but due to the neutral stability, the strongest 850mb
winds will likely not mix down without forcing. Despite extreme low
level shear, the severe-tornado threat is relatively low from this
convective line, as there is little if any most unstable instability
(let alone any surface based CAPE); HREF mean MU CAPE only climbs to
around 100 J/kg with no members showing anything more appreciable.
However, the synoptic and mesoscale forcing will be significant
along this line, so an isolated tornado is not out of the question.
SPC continued their Marginal risk outlook as a result. A Wind
Advisory is in effect starting at 5am to cover the prefrontal
gradient winds and cold advection behind the line; short fused
warnings will be used as needed for segments of the convective line
that warrant additional attention. The strongest winds from the
system will likely occur with the mixing from convection showers-
storms or directly behind the line. HRRR cross sections suggest some
very strong descent behind the line, adding another mechanism to mix
down stronger winds. The general timing looks to be roughly 7am-
noon for the convective line to push from the CSRA through the
coastal plain and eastern Midlands.
Behind the front, winds will shift out of the west and remain breezy
throughout the afternoon. Cold advection, relatively deep mixing,
and unidirectional shear should easily be able to mechanically mix
down 25-35 mph winds until Sunday evening.
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
Key Message(s):
-Dry and cool early in the week.
-Potential for wintry weather midweek.
-Colder than normal into next weekend.
Monday and Tuesday...Upper trough over eastern Canada and
trough out in the Intermountain West with resulting fast zonal
flow aloft across the eastern CONUS early in the week. At the
surface, a very strong pressure ridge over south central Canada
will be building southeast and expect generally dry and cool
conditions, slightly warmer Tuesday as warm advection develops
as the upper trough out west moves into the Plains.
Cold air damming expected mid week with ridge building in from
the North into the western Carolinas. Warm front expected in
the SC coastal Plain. Ensembles suggest weak low pressure
developing along the Gulf coast, moving northeast to the
Carolina coast Wednesday night. NBM pops are quite high during
this period so expect widespread rain, although heavier rain
focused in the coastal plain closer to max moisture flux axis
suggested in the NAEFS guidance. Cut max temps Wednesday due to
potential cold air damming especially north Midlands. Soundings
suggest a precip type issue Wednesday night into Thursday
morning with wintry precip possible in the northern Midlands.
Freezing rain the main threat. Note the ECMWF deterministic is
rather threatening. Ensembles show an anomalously deep upper low
from the Ohio Valley east across the Mid Atlantic transitioning
to fast zonal flow aloft across the southeast. High pressure
will be building southeast from the Plains and this should lead
to temperatures below normal and cooler normal temperatures into
next weekend.
&&
.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
...Low Clouds and Fog Possible Tonight....
CIGs have been decreasing at the terminals this evening, with
CAE already reporting LIFR conditions. Also monitoring for the
potential of low visibilities later tonight (especially CAE/CUB)
as areas of fog develop. Conditions will continue to
deteriorate during the next few hours until a warm front lifts,
clearing the lower clouds and patchy fog. Strong winds near the
top of the boundary layer are expected to continue tonight and
into Sunday so maintained LLWS at all TAF sites. A strong cold
front will sweep across the forecast area Sunday morning
bringing a period of rain and isolated thunderstorms. Winds
could be particularly strong during the frontal passage, but are
also anticipated to be breezy both before and after the front,
as southwesterly winds turn westerly.
EXTENDED AVIATION OUTLOOK...A approaching system on Wednesday
and Thursday will bring some precipitation and associated
restrictions.
&&
.HYDROLOGY...
Recent rainfall totals in the headwaters of the area rivers in
the Upstate of SC and western NC indicate that 3 to 5 inches
fell with amounts from one half inch eastern Midlands to 2
inches across the Piedmont. This has produced rises on the area
rivers and streams that will continue over the weekend. The
rivers are near crest and forecast to fall over the next couple
of days. However, additional systems are expected to bring more
rainfall to the region through the period.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...Wind Advisory from 5 AM to 6 PM EST Sunday for SCZ016-018-
020>022-025>031-035-037-038-041-115-116-135>137.
GA...Wind Advisory from 5 AM to 6 PM EST Sunday for GAZ040-063>065-
077.
&&
$$
Area Forecast Discussion
National Weather Service Grand Junction CO
447 PM MST Sat Feb 15 2025
.KEY MESSAGES...
- Precipitation has become more convective in nature this
afternoon with a few more inches possible over the higher
terrain. Winter Storm Warnings remain in effect through 6PM.
- Another round of snow moves in tomorrow afternoon affecting
the northern and central mountains and Flat Tops. Winter Storm
Watches have been issued for those areas with the highest
elevations of the northern mountains possibly seeing over a
foot of new snow.
- Remaining portions of the forecast area, outside of the clouds
and snow, will see variable cloudiness and high temperatures
hovering near normal through the start of the work week.
&&
.SHORT TERM /THROUGH SUNDAY NIGHT/...
Issued at 106 PM MST Sat Feb 15 2025
Precipitation has taken a definite convective turn this
afternoon as a shortwave moves across the region. Models picked
up this disturbance well and with plenty of moisture remaining
in the atmosphere along with fairly steep lapse rates,
instability is being released allowing for some heavier snow to
continue. The HRRR and NAMNEST are both performing well with the
placement and intensity of this snow with both also showing a
marked downturn in activity after 6PM this evening. The Winter
Storm Warnings remain in effect through 6PM as well so don`t see
any need to pull down these highlights early. Early morning
cloudiness has finally started lifting across much of the area
and those areas seeing peeks of sun will also likely see some
gusty winds of 20 to near 30 mph at times as mixing brings down
some stronger winds. Some light snow will continue through
midnight but significant accumulations are not expected.
Early Sunday morning, a ridge axis will be located over southern
California, stretching up into Nevada, eastern Oregon and
Washington State. The jet stream will be riding up and over the
ridge and will eventually break it down causing the jet to become
more meridional in nature. Hope you folks in and around
Steamboat Springs like snow because the next round starts
tomorrow afternoon and continues through early next week. The
remnants of a relatively weak AR will make it to our northern
mountains, Flat Tops, and to a lesser extent, the central
mountains and the west to east nature of the jet will allow
favorable orographics to also occur as pieces of energy move
through the mean flow. A foot of new snow with locally higher
amounts is expected for the Park Range and Elkheads with 6 to
12 inches possible for the Flat Tops and central mountains. Some
uncertainty with moisture amounts does remain however so these
amounts could change. With current highlights still in effect,
opted to issue Winter Storm Watches for those 3 zones valid from
11AM Sunday through 7AM Tuesday. May also need to issue for
Steamboat Springs proper as ensembles are showing possibly 6
inches falling in town. Areas south of the northern valleys will
see a mostly sunny start to the day though some dense fog can`t
be ruled out across portions of the CWA thanks to residual low
level moisture. Clouds will be on the increase from north to
south as they day progresses. Outside of the areas mentioned
above, some light snow will make it down to the San Juans and
over the eastern Uintas but amounts will range from about 2 to 4
inches. As far as highs are concerned, most areas will see near
normal except for the northern valleys and those areas seeing
the precip. They will stay below normal by several degrees.
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
Issued at 106 PM MST Sat Feb 15 2025
The passage of two subtle shortwave troughs highlights the long term
forecast.
The first advects through the northwesterly flow aloft on Monday
bringing mountain snow to the northern and central Colorado
mountains. Upstream of the main shortwave trough, marginal positive
vorticity advection and jet dynamics team up to create ascent for
the slightly elevated PWATs left behind after Sunday`s moisture
advection. The brunt of the forcing passes through Monday morning
through the evening hours. This is also when we expect snowfall
accumulations to pick up in the northern and central mountains with
rates increasing from north to south along the Divide.
Light snow continues across the northern mountains through Tuesday
as upslope flow continues to drive precipitation chances despite the
arrival of a drier airmass. We will have to wait and see if the
forcing or the moisture wins out. The arrival of drier air could
halt accumulations earlier that the forecast currently calls for.
After a quieter Wednesday with ridging overhead, the next shortwave
is progged to drop into the Four Corners region before stalling out
through Friday. Moisture advection looks strongest with the arrival
of the wave on Thursday. However, weak forcing and the short
residence time of the moisture will likely limit accumulations. At
this time the late-week wave looks to be the weaker of the two
systems on deck for this week.
&&
.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 430 PM MST Sat Feb 15 2025
Light snow showers continue through the evening along and east
of the line KHDN-KTEX with brief periods below ILS breakpoints.
These showers end by 07Z with skies across the region scattering
out. Stronger winds aloft will produce mountain wave turbulence
and areas of LLWS at the mountain sites. The next Winter system
moves into the northern mountains after 16Z spreading southeast
into the central Colorado mountains through the afternoon.
Expect impacts at KHDN beginning around 18Z, and KEGE, KASE and
KRIL after 21Z with low ceilings and visibility below ILS
breakpoints due to snow showers.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...Winter Storm Warning until 6 PM MST this evening for COZ004-
005-009-010-012-013-017-018.
Winter Storm Watch from Sunday morning through late Monday
night for COZ004-010-013.
UT...None.
&&
$$
SHORT TERM...KJS
LONG TERM...GF
AVIATION...DB
Area Forecast Discussion
National Weather Service Springfield MO
524 PM CST Sat Feb 15 2025
.KEY MESSAGES...
- Showers and a few thunderstorms this afternoon transition to
snow this evening and tonight. Forecast snow accumulations of
a dusting to 1 inch, locally up to 2 inches could produce a
few slick spots and reductions to visibility.
- Windy conditions tonight into Sunday. Northwest winds will
gust up to 30-35 mph.
- A winter storm will impact southeast Kansas and southwest
Missouri Monday evening into Wednesday morning. There are
medium to high chances (50-80%) of at least 5 inches of snow
accumulations.
- High confidence in dangerously cold temperatures and wind
chills Tuesday through Thursday.
&&
.SHORT TERM /THROUGH SUNDAY/...
Issued at 320 PM CST Sat Feb 15 2025
Water vapor imagery depicts quite well the upper-level longwave
trough shifting east through the High Plains this afternoon.
Strong and deep south-southwesterly flow is producing robust
moisture advection through the Lower Mississippi and Ohio
valleys. A frontal boundary is focusing a band of showers and
thunderstorms from northern Arkansas and southeast Missouri
arcing into northeast into Tennessee and Kentucky. A secondary
boundary is forcing a band of lighter precipitation north of the
I-44 corridor. The attendant surface low is situated over
extreme southeast Kansas and northeast Oklahoma early this
afternoon and will gradually shift east throughout the day.
As the low has moved into Missouri, the southern band of
thunderstorms has clipped portions of south-central Missouri and
the eastern Ozarks. Though the heaviest rainfall axis will
remain well to the east of the CWA, the 12Z HREF LPMM suggests
locations in south-central Missouri could receive up to 0.75 to 1
inch of rain.
Behind the low, a colder airmass will push into the area. Models
show fairly good agreement that wrap-around precipitation on the
back side of the system will result in a period of light snow for
much of the forecast area beginning late this afternoon and into the
overnight hours. Point forecast soundings depict modest lift through
the dendritic growth zone, generally limiting snowfall rates.
However, RAP output suggest banding could briefly produce higher
snowfall rates. The NBM 25th-75th percentile data suggest
snowfall totals ranging from a trace up to 2 inches locally.
Top-down analysis suggests a very brief period of mixed
precipitation (rain, snow, sleet) could occur during the
transition from rain to snow, but this is not expected to last
long. Widespread travel impacts are not expected, but a few
slick spots and reductions to visibility are possible.
Overnight low temperatures drop into the teens and mid 20s. With the
departing low to our east and broad high pressure expanding across
the Plains, a tightening pressure gradient will produce breezy
northwest winds gusting up to 30-35 mph. The combination of cold and
wind will drive wind chills into the -5 to 10 degree range.
&&
.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
Issued at 320 PM CST Sat
Feb 15 2025
Winter Storm Monday Evening-Wednesday Morning:
Confidence is increasing that a winter storm will bring
hazardous travel conditions and disruptions to daily life
through southwest Missouri and southeast Kansas Monday evening
into Wednesday morning.
Ensemble clusters have remained in fairly good agreement
regarding the synoptic features that will be in play for this
event. Aloft, southwest Missouri and southeast Kansas will be
under the right entrance region of a 120+ kt upper-level jet
streak Tuesday morning. By Tuesday evening, a shortwave is
progged to dig through the Plains, now placing the region under
the left exit region of the jet, further enhancing synoptic-
scale lift. Analysis of frontogenetic forcing from the global
models suggests the strongest forcing will occur in the 700 mb
layer, coinciding with negative EPV to the south, suggesting
enhanced frontal circulation. Furthermore, ECMWF ESATs are
showing specific humidity standardized anomaly values of 1-2
through this layer, indicating ample moisture content. These
factors combined with a cold thermo profile and tall dendritic
growth zone will support heavy snowfall potential. With the
snowfall spanning multiple forecast periods, the Extreme
Forecast Index (EFI) and Shift of Tails do not necessarily
capture an extreme snowfall signal, with weaker signals on each
side of 00Z Wednesday.
Latest 48-hr Snowfall Probabilities Ending 12 PM Wednesday:
>2 inches: 90-100%
>4 inches: 70-95%
>6 inches: 50-90%
>8 inches: 15-80% (lowest near MO/AR border)
To that end, the Probabilistic Winter Storm Severity Index
(WSSI-P) is likewise showing increasing chances for impacts
across the board:
Minor Impacts: 80-100%
Moderate Impacts: 60-90%
Major Impacts: 10-50%
Thus, there are high chances of at least moderate impacts, which
means to expect disruptions to daily live, hazardous driving
conditions, and closures and disruptions to infrastructure. A
Winter Storm Watch has been issued
Of course, details remain uncertain at this point, and forecast
adjustments will occur over the next 48-72 hours. We urge
everyone to keep up with the NWS forecast and make preparations
as needed.
Dangerous Cold Tuesday-Thursday:
There remains high confidence that an anomalously cold airmass
will barge into the region behind the snow Tuesday through
Thursday. Ensembles show an impressive 1050+ mb surface high
pressure system dropping out of Canada for the middle of the
week, bringing with it bitterly cold air. NAEFS and ECMWF ESATs
show this exceeding the 99th percentile of climatology across
the north-central CONUS. In fact, the EFI is already just about
maxed out (-0.90 to -0.99) for both minimum and maximum
temperatures Tuesday through Thursday across our CWA. NBM
percentile data show high probabilities (>75%) that afternoon
max temperatures will struggle to climb into the 20s through
this period, with overnight lows in the single digits above and
below zero. With a decent surface pressure gradient in place,
northerly winds will push wind chills even lower. Forecast minimum
wind chills range from -10 to -25 degrees Tuesday night through
Thursday night. Further refinements to the temperature and wind
forecasts may nudge these wind chills either way, but overall
there is high confidence in dangerously cold conditions during
this period.
Fortunately, ensembles agree in showing a gradual warmup late
week into next weekend, with only low probabilities for
precipitation. Indeed, the Climate Prediction Center`s 6-10 day
outlook shows increasing probabilities of below normal
precipitation through the Feb 21-25 timeframe.
&&
.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 512 PM CST Sat Feb 15 2025
Rain and drizzle moving through the area reducing CIGVIS to
primarily IFR with some LIFR. Gusty NNW surface winds again this
evening with sustained speeds of 15-20 kts and gusts up to 25
kts. Precipitation will switch over to snow or rain/snow mix in
the next couple of hours as temperatures drop below freezing
beginning in the northwest. Low CIGVIS will accompany this
activity as it moves through to the east-southeast. Ceilings
begin to rise to MVFR midmorning Sunday as the system moves out.
Winds will remain out of the northwest but will calm after
precipitation moves out.
&&
.SGF WATCHES/WARNINGS/ADVISORIES...
KS...Winter Storm Watch from late Monday night through late Tuesday
night for KSZ073-097-101.
MO...Winter Storm Watch from late Monday night through late Tuesday
night for MOZ055>058-066>071-077>083-088>098-101>106.
&&
$$
SHORT TERM...Didio
LONG TERM...Didio
AVIATION...Nelson
Area Forecast Discussion
National Weather Service Topeka KS
510 PM CST Sat Feb 15 2025
.KEY MESSAGES...
- Light snow is likely (up to 60%) along the Nebraska State line
by Monday morning. Amounts look to be limited to the north and
around an inch or two.
- More impactful winter weather is expected Monday night and
through the day Tuesday. There is a 60% to 80% chance for
several inches of snow. A winter storm watch is posted for
areas with the better chances for more than 5 inches.
- Dangerously cold temperatures are forecast through mid-week
and confidence in this forecast is good. Wind chill values could
be as cold as 30 below zero.
&&
.DISCUSSION...
Issued at 247 PM CST Sat Feb 15 2025
20Z water vapor imagery showed a shortwave lifting over the TX
and OK panhandles within a synoptic scale upper trough extending
north into central Canada. A second upper level low was noted
over the Gulf of Alaska with a shortwave ridge axis along the
west coast. Surface obs showed a cold front pushing into
southeast KS with high pressure building south through the
northern plains.
For the late afternoon and this evening, there is still a chance for
some very light freezing drizzle or snow across east central KS as
the shortwave lifts east. Recent RAP and NAM progs show isentropic
downglide below 800MB, so the lift developing the band of precip in
south central KS now is likely from the shortwave and deep enough to
have ice in the cloud. This would favor snow over drizzle as the
afternoon progresses. And snow amounts should be minor with most
guidance only showing a few hundredths of an inch QPF.
Focus shifts to the winter weather forecast for Monday and Tuesday.
There is good consistency and agreement in the operational models
with precip chances and confidence is increasing that we will get
several more inches of snow by Tuesday evening. The first opportunity
for snow looks to move into northern KS Monday morning as some mid
level frontogenesis develops a broad band of snow. This could produce
an inch or two along the Neb state line, but the frontogenesis
doesn`t extend much further south than that. So most areas are
expected to see only some light snow. Probabilities for 2 inches or
more are only around 20 percent north of highway 36.
The more impactful weather is forecast to develop Monday night and
persist through the day Tuesday. Again there is good agreement in
broad synoptic forcing for precip. Although it doesn`t appear to be
a very dynamic system, ensembles continue to show a sudo warm moist
conveyor belt feeding into southern KS on Tuesday with anomalously
high moisture availability. With a very cold airmass, snow to liquid
ratios look to be between 15:1 and 20:1 and it wouldn`t take a lot
of QPF for snow to begin to add up. The focus of the warm air
advection had shifted from previous runs over central KS to
southeast and east central KS with the 12Z runs. This is the source
of the greatest uncertainty. Where does the conveyor belt set up and
how much moisture is able to lift north into the cold air. Am a
little leery of some of the QPF amounts shown by the NBM and
ensemble means with over a half inch of QPF across east central KS.
This produces some hefty snow amounts over east central KS. But at
the same time the probabilities for greater than 6 or 8 inches have
come down in the NBM which is curious. The consistency in the
operational solutions and the NBM showing a 40 to 50 percent chance
for exceeding 6 inches across east central KS have led to going with
a winter storm watch. Will have to keep in mind the potential for
the higher QPF and snow amounts. The 90th percentile, or worse case
scenario, shows that around 10 inches is not out of the question.
Later shifts can reevaluate if the watch should be expanded beyond
the initial issuance.
The other main impact is going to be the brutally cold temperatures
that come in for next week. Most guidance shows a 1045MB high
pressure system building into the central plains by Thursday night.
Ensemble data shows little spread of only a few degrees between the
25th and 75th percentile. So confidence in the temp forecast through
next week is good. The NBM mean should be a good forecast for temps
and we will probably need some cold weather headlines eventually.
&&
.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 508 PM CST Sat Feb 15 2025
MVFR ceilings will prevail through the night. Cloud cover should
start to erode from west to east tomorrow morning. Additional
cloud cover could move in by the early afternoon. Gusty
northerly wind will continue this evening and begin to subside
by tomorrow morning.
&&
.CLIMATE...
Updated at 247 PM CST Sat Feb 15 2025
Record Low Temperatures
Tuesday, February 18
Record (Year) Forecast
Topeka -9 (1978) 0
Concordia -10 (1978) -3
Wednesday, February 19
Record (Year) Forecast
Topeka -11 (1978) -7
Concordia -3 (1978) -7
Thursday, February 20
Record (Year) Forecast
Topeka -13 (1889) -13
Concordia -5 (1918) -12
Friday, February 21
Record (Year) Forecast
Topeka -2 (1939) -8
Concordia -3 (1918) -3
Record Minimum High Temperatures
Tuesday, February 18
Record (Year) Forecast
Topeka 13 (1936) 6
Concordia 11 (1929) 1
Wednesday, February 19
Record (Year) Forecast
Topeka 14 (1929) 3
Concordia 16 (1929, 1959) 6
Thursday, February 20
Record (Year) Forecast
Topeka 10 (1918) 10
Concordia 8 (1918) 10
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
Winter Storm Watch from late Monday night through late Tuesday
night for KSZ035-KSZ037-KSZ054-KSZ055-KSZ056-KSZ058-KSZ059.
&&
$$
DISCUSSION...Wolters
AVIATION...Jones
CLIMATE...Reese/Wolters