Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/04/25
Area Forecast Discussion
National Weather Service Cheyenne WY
504 PM MST Fri Jan 3 2025
.KEY MESSAGES...
- Areas of dense fog are expected to develop in the Nebraska
panhandle and far eastern Wyoming this evening. A Dense Fog
Advisory had been issued for the Nebraska panhandle tonight
and through Saturday morning. Freezing drizzle is also
possible which could lead to slick conditions.
- A progressive system will move into the area on Saturday,
bringing widespread accumulating snow to the lower elevations.
Mountain snow is also expected with Winter Weather Advisories
issued for the Snowy and Sierra Madre Ranges.
- Active long term pattern continues through the week with
multiple chances for widespread precipitation across the
region.
&&
.SHORT TERM /THROUGH SATURDAY NIGHT/...
Issued at 400 PM MST Fri Jan 3 2025
Expect an active next 36 to 48 hours across the region as both a
backdoor front and progressive storm system affect the area. The
most recent surface analysis shows a stationary front lingering over
the Wyoming/Nebraska border. Easterly flow will slowly retrograde
this front back westward until it gets caught on the Laramie Range.
The resulting easterly flow will advect low-level moisture into the
Nebraska panhandle and likely as far west as the Interstate 25
corridor. Current observations already show fog and low stratus
around the Chadron area. This fog is expected to become dense
and more widespread heading into the evening and overnight
hours. Hi-Res guidance like the HRRR has been consistent from
run to run showing a large swath of dense fog developing from
northeast Wyoming all the way south into southwest Kansas.
Onset of fog will likely occur later this evening and continue
through the morning hours on Saturday as southeasterly surface
winds persist. As a result, did issue a Dense Fog Advisory for
the Nebraska panhandle starting at 8 PM this evening and
continuing until 11 AM Saturday. Will also have to keep an eye
on the fog into Laramie County. Fog will be likely across
Laramie County, however, surface winds will be more southerly
throughout much of the night which may not lead to the
development of dense fog. If dense fog wasn`t enough, there is
also the chance for the development of freezing drizzle across
the panhandle late tonight and into tomorrow morning. A shallow
but saturated column of supercooled liquid close to the surface
looks evident from model soundings across the panhandle. Given
upslope flow, there could be enough lift to generate freezing
drizzle late tonight and into Sunday morning. For now, kept
chance wording for freezing drizzle in the forecast as dry, warm
air aloft is also present on the sounding just above the
supercooled layer. Any dry air intrusion will limit freezing
drizzle. However, it is worth mentioning that some ice accretion
cannot be ruled out. Models like the HRRR show a trace of ice
overnight which could lead to slick conditions during the day
Saturday.
By Saturday, the upper-level progressive system will begin to make
its way into the CWA, bringing the region`s next chance for snow.
With models showing leeside cyclogenesis occurring roughly
along the Colorado/New Mexico border, the surface low will
likely be too far south for the CWA to see any major impacts. As
the surface low moves eastward into Oklahoma Saturday night,
good wrap around moisture into the eastern half of the CWA is
expected. This is likely where the bulk of accumulation will
come from. Snow will likely begin making its way into the
western part of the CWA by early afternoon. Ample moisture and
orographic lift will lead to yet another quick mountain snow
event for the Sierra Madre and Snowy Ranges. Between Saturday
and Sunday morning, the mountain could pick up between 6 and 12
inches. As a result, went ahead and issued a Winter Weather
Advisory. Other areas to potentially watch for an Advisory
would be the Nebraska panhandle as fog dissipates and snow
spreads eastward throughout the day. By Saturday night, higher
QPF amounts are expected across the panhandle with ample wrap
around moisture and the presence of a 700 mb low just east of
the CWA. This coupled with a saturated dendritic growth zone
shown by GFS soundings, could lead to decent snowfall rates
across the panhandle. As previously mentioned, snowfall totals
across the panhandle could warrant Winter Weather Advisories.
Most locations in western Nebraska could see between 2 and 4
inches with locally higher amounts possible wherever convergence
and the saturated DGZ are colocated. For the rest of southeast
Wyoming, snowfall accumulations will total in the 1 to 3 inch
range. Snow will taper off late Saturday night and into Sunday
morning as the low tracks further eastward into the center of
the country.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
Issued at 1200 PM MST Fri Jan 3 2025
The long term forecast will be characterized by an active
northwest flow pattern with several troughs and vort maxes
traversing southeastward through the northern Rockies and high
plains. The unsettled pattern will keep surface temperatures
generally at or slightly below average with two opportunities
for precipitation through the long-term period. The first will
arrive on Monday evening into Tuesday as a deep upper-level
low/embedded trough moves southeast through the Rockies in the
aforementioned northwest flow pattern. A remnant stream of
Pacific moisture will move eastward through the Great Basin and
into southeast Wyoming by Monday evening with westerly upslope
snowfall expected in the higher terrain of the Snowy and Sierra
Madre ranges. A weak surface cold front will accompany this
system, moving south through the high plains on Tuesday morning.
Behind this frontal boundary, surface flow will gradually
transition to a more upslope regime. With lingering moisture in
place aloft and some saturation in the lower portion of forecast
soundings, there is a brief window for some snowfall in the
eastern plains along and east of I-25 for locations such as
Cheyenne and Sidney on Tuesday morning. Soundings dry out
considerably by Tuesday afternoon and any snowfall that does
fall should generally amount to only an inch or two or less.
The next opportunity for precipitation is much less certain and
will potentially come in the Thursday timeframe. Another
shortwave trough embedded in the broader northwest flow regime
will dive southwards and pass through southeast Wyoming and
western Nebraska sometime on the Wednesday night/Thursday
timeframe. Ensemble consensus with this system is much lower,
with at least 30% of ensemble members supporting a very weak
system and likely no precipitation with it at all. Cold,
northwest flow and breezy weather is a more likely solution,
with a possible gradient-driven higher wind event in the typical
wind-prone corridors of Wyoming setting up as the trough skirts
by. Still, the opportunity is there for a few inches of snow in
the higher terrain with the most likely timeframe for this
precipitation coming early on Thursday morning. Overall forecast
confidence in the long-term is medium as ensemble guidance
becomes quite dispersive with specific troughs and vort maxes by
day 5 through 7.
&&
.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 443 PM MST Fri Jan 3 2025
High Plains Terminals: Expect difficult aviation conditions
tonight into Saturday due to low CIGs, fog, and patchy freezing
drizzle. Confidence is high in IFR conditions returning to all
Nebraska panhandle terminals within a few hours from now, and
most likely sticking around through the night and much of the
day Saturday. For KCYS, confidence is lower in timing, but the
back-door cold front should push westward enough to bring IFR
conditions later this evening, but this should dissipate
Saturday morning. A brief break in IFR is possible in Nebraska
Saturday afternoon, but attention turns to snow showers towards
the end of the TAF period.
KRWL & KLAR: Increasing winds tonight may lead to LLWS
overnight. In addition, there is a chance (about 30%) for brief
IFR VIS in snow showers moving through KRWL around 14z to 17z,
followed by another chance for snow showers and IFR conditions
towards the end of the TAF period at both terminals.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...Winter Weather Advisory from 11 AM Saturday to 11 AM MST
Sunday for WYZ112-114.
NE...Dense Fog Advisory from 8 PM this evening to 11 AM MST
Saturday for NEZ002-003-019>021-054-055-095-096.
&&
$$
SHORT TERM...SF
LONG TERM...MAC
AVIATION...MN
Area Forecast Discussion
National Weather Service Dodge City KS
620 PM CST Fri Jan 3 2025
.KEY MESSAGES...
- Drizzle and freezing drizzle event starting late Saturday morning
- Icy mix will transition to snow and blowing snow during the night
Saturday
- Wind gusts over 40 mph and accumulating snowfall will lead to
terrible travel conditions on Sunday
&&
.DISCUSSION...
Issued at 205 PM CST Fri Jan 3 2025
20z surface observations and upper air analysis shows a trough and
closed low located just off the Pacific northwest with a ridge in
the Rockies and a trough in the eastern CONUS. At the surface a
1011 mb low has developed in eastern Colorado leading to south to
southeast winds across the region.
In regards to the upcoming winter storm short term and long term
control and ensemble models are coming into focus at least on the
track with the upper level trough moving from the Pacific northwest
to central Colorado during the day on Saturday. Ahead of the main
system east to southeast winds in the lowest 1 km will stream in
gulf moisture during the morning and afternoon Saturday. Pockets of
drizzle and freezing drizzle will start to form around sunrise and
continue to expand in coverage into the early afternoon. BUFKIT
profiles continue to show a saturated lowest 1 km and good shear
along with a dry mid layer which will support drizzle. Temperature
profiles will be tricky as the moist conveyor belt will also bring
in slightly warmer air into the 850 mb levels with the 0 degree line
setting up roughly along the highway 54 corridor by afternoon. As a
result the precip should stay freezing drizzle along and north of
highway 50 (light accumulations up to 0.10 inch)...a mix of liquid
and ice between highway 50 and 54 and mainly drizzle along the
Oklahoma border. HREF mean totals of ice are roughly up to 0.10
inch west of highway 183 and north of highway 54 and around 0.10
inch east of highway 183 and north of highway 54.
Saturday night into Sunday the storm system will see an increase in
the 500 mb winds leading to the trough turning into a closed low
between 00-06z Sunday. Also of note a 700-850 mb high develops in
the northern plains during this time. These features will largely
determine the track of the upper low as the high in the northern
plains could propagate a slight southward shift. Also the models
don`t suggest a large scale area of convection to the south which
would keep the track more in line with a Kansas-Oklahoma border area
for the upper low to cross. Timing of the low varies from the
quicker RAP solution to the slower NAM and GFS. I`m trending more
with the slower idea which would put the heavier bands of snow
developing after midnight and continuing through noon Sunday. The
way the profiles are shaping up for mesoscale banding it is not
looking favorable for an intense band of snow due to the increased
instability in the dendritic growth zone however with the EFI and
shift of tails showing a sign of increased CAPE from Dodge City to
Pratt we could have some pockets of convective snowfall and brief
bursts of 0.5-1 inch per hour snowfall rates. Basically we should
have a large area of light to moderate snow as the low passes and
the backside lift goes through southwest Kansas. Winds will also
increase as the low tightens with sustained winds 25-35 mph and
gusts 45 mph or more. Blowing snow is expected with this event.
Snowfall totals with the event are still up for change but the
highest confidence at this point shows an area of 3-9 inches along
and north of a Scott City to Dodge City to Pratt line. NBM
probabilities of greater than 5 inches are highest in our northeast
zones with Hays at 60 percent and around Great Bend at 50 percent.
The EFI and shift of tails also supports this with the greatest
totals located in central Kansas especially along the I-70 corridor.
Expect much colder temperatures early next week. Arctic air behind
the low will settle in through Monday and then another reinforcing
shot of arctic air comes in Tuesday.
&&
.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 554 PM CST Fri Jan 3 2025
At the onset of this TAF period early this evening, a narrow
axis of IFR, bordering on LIFR ceiling continued at GCK.
Satellite trends were showing the east edge of this encroaching
on GCK terminal, so they may go to IFR this evening, however
stratus will build back in after a few hours. Aviation weather
conditions will deteriorate at all terminals after midnight and
especially by daybreak Saturday ahead our approaching winter
storm. Widespread IFR around daybreak will likely become
widespread LIFR in fog and/or freezing drizzle, which will
continue through the day Saturday.
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning from noon Saturday to 6 PM CST Sunday for
KSZ030-031-045-046-065-066.
Winter Weather Advisory from noon Saturday to 6 PM CST Sunday
for KSZ043-044-062>064-075>081.
Winter Weather Advisory from midnight Saturday night to 6 PM
CST Sunday for KSZ085>090.
&&
$$
DISCUSSION...Tatro
AVIATION...Umscheid
Area Forecast Discussion
National Weather Service Kansas City/Pleasant Hill MO
553 PM CST Fri Jan 3 2025
.KEY MESSAGES...
- Winter Storm Warning region-wide from 6 pm tomorrow through 3
am Monday.
- 7-13" of snow is likely for areas north of Interstate 70.
- 3-8" of snow is likely for areas along and south of Interstate
70.
- Significant ice accumulations (0.25" or more) for areas south
of Highway 50 (especially Pleasanton KS to Clinton MO).
- Bitterly cold temperatures and wind chills expected Sunday
night trough the end of next week.
&&
.DISCUSSION...
Issued at 157 PM CST Fri Jan 3 2025
The trough that will bring us a significant winter storm later
this weekend is currently approaching landfall across the
Pacific Northwest. By tomorrow afternoon, it will be crossing
the Rockies, with theta e advection beginning to ramp up over
southern portions of our CWA out ahead of the trough. By
tomorrow evening, a closed mid level low is expected to develop
near the Colorado/Kansas border with a surface low developing
over the TX/OK Panhandles. The mid level low should continue to
deepen as it moves eastward, with the trough becoming negatively
tilted and the system taking on the appearance of a prototypical
mid latitude extratropical cyclone as it approaches and moves
through our region. With ample moisture flux into eastern Kansas
and Missouri thanks to the warm conveyor belt, strong forcing
for ascent, and a favorable low track, widespread moderate to
occasionally heavy wintry precipitation is likely to impact the
region beginning tomorrow evening and continuing through late
Sunday night/early Monday morning.
The HRRR has been consistent in developing freezing drizzle
(courtesy of the supercooled warm rain process) across the KC
metro as early as 3 pm tomorrow afternoon, with potentially
significant ice accumulations by tomorrow night. However, so
far the HRRR is mostly alone in this endeavor. The seemingly
more likely scenario is sleet developing across the KC metro,
with freezing drizzle further south toward Linn County KS/Bates
County MO after 6 pm tomorrow as we get a warm nose to develop
between 700 mb and 850 mb. By midnight Sunday morning, the SPC
HREF depicts sleet/mixed precipitation across the Interstate 70
corridor, with snow along a line from Leavenworth to Moberly
(and freezing drizzle/rain possible across our far south area).
Precipitation should gradually changeover to all snow as we go
through the Sunday morning hours, although the region of sleet
and freezing rain along and south of the Interstate 70 corridor
will likely hang on through mid to late Sunday morning.
Precipitation should be all snow by early to mid Sunday
afternoon as arctic air moves in and erodes the warm nose.
Highest snowfall totals should be north of Interstate
70/Missouri River, where precipitation type should become snow
early on in the event (or snow the entire time). Snow totals in
this area should range from 8 to 13 inches. Snowfall totals
should decrease from north to south, with 3 to 8 inches of snow
likely south of Interstate 70. Prime time for accumulating snow
looks to be between 6 am and 6 pm Sunday, and with the potential
for frontogenetic banding as well as the development of a
TROWAL as the warm conveyor belt wraps around the mid level low,
periods of moderate to heavy snow with accumulation rates up to
2" per hour will be possible. These features are the reason why
snowfall totals above a foot remain very much possible for
areas along and north of Interstate 70. Expected dry air
entrainment on the northern edge of the system has cut down
snowfall total a bit up toward the Iowa border. As far as icing
is concerned, 0.25" to perhaps up to 0.5" of ice accumulation
will be possible across our southern zones (toward the Ozark
Plateau), which could cause major travel and infrastructure
issues.
Northerly winds on Sunday could gust as high as 35 to 40 mph,
which will likely yield blowing snow and very poor visibilities,
especially as the snow becomes more dry and powdery Sunday
afternoon as the thermal profiles continues to cool. There was a
discussion early this afternoon with WFO Topeka about upgrading
to a Blizzard Warning for portions of our CWA, but for now have
decided to hold off and just run with the Winter Storm Warning. Snow
should exit the region from west to east on Sunday night into
early Monday morning, and the Winter Storm Warning is set to
expire at 3 AM Monday.
In the wake of this storm system, bitterly cold temperatures will
move into the area and the remainder of the forecast will be well be
normal for temperatures. In fact, we`ll likely see at least three
days in row with lows below zero at KCI (Tuesday - Thursday). With
the wind factored in, we`ll see multiple days with wind chill values
less than -15. This would likely result in the issuance of a Cold
Weather Advisory for multiple days across northern MO/ northeastern
KS.
&&
.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 540 PM CST Fri Jan 3 2025
VFR conditions continue through the overnight. Stratus has been
breaking up with CIGs continuing to left over the next few
hours. Winds start northerly becoming easterly through the
period. VFR conditions persist through early Saturday
afternoon. Light wintry precipitation is forecasted to move in
during the late afternoon; likely starting as FZDZ before
becoming FZRA and/or PL beyond the period.
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
MO...Winter Storm Warning from 6 PM Saturday to 3 AM CST Monday for
MOZ001>008-011>017-020>025-028>033-037>040-043>046-053-
054.
KS...Winter Storm Warning from 6 PM Saturday to 3 AM CST Monday for
KSZ025-057-060-102>105.
&&
$$
DISCUSSION...Williams
AVIATION...Pesel
Area Forecast Discussion
National Weather Service Morristown TN
926 PM EST Fri Jan 3 2025
...New UPDATE...
.UPDATE...
Issued at 920 PM EST Fri Jan 3 2025
Radar and observations indicate the remaining snow showers and
flurries have dissipated, so will remove tonight`s remaining
precip from the forecast with this update. Otherwise, the forecast
generally looks to be on track, so just a few other tweaks at
this time.
&&
.SHORT TERM...
(This evening through Saturday)
Issued at 231 PM EST Fri Jan 3 2025
Key Messages:
1. Mountain snow will continue this afternoon and diminish into
the night. Valley locations may see flurries or light snow.
2. Dry weather Saturday, but much cooler compared to today.
Discussion:
Bands of heavy snow showers have redeveloped on radar and are
bringing quick accumulation and short duration low visibility to
some, especially for southwest Virginia and into far northeastern
Tennesee. Can expect anywhere from an additional couple tenths of
an inch to up to 2 inches more of snowfall. The highest locations,
for example, Roan Mountain may amount to up to 3 more inches
before the system pulls away tonight. Conditions at this time per
SPC with regard to RH aloft, the DGZ, and forcing/evacuation are
still prime for the development of snowfall. As well as air
temperatures aloft dropping past FROPA which is now in North
Carolina. If CAMs follow trends of reflectivity in the next
couple of hours, things should diminish with time this evening.
Isolated showers with flurries may linger into the overnight hours
before we totally clear out. Southern valley and plateau will
continue to remain dry with partly to mostly cloudy skies.
Saturday will trend drier with surface high pressure building in
and brief rising heights aloft. We will still be within NW flow
aloft and since we will be post-frontal, temperatures Saturday
morning and in the afternoon will be cooler in comparison to
today.
&&
.LONG TERM...
(Saturday night through next Friday)
Issued at 231 PM EST Fri Jan 3 2025
Key Messages:
1. The primary system of interested will be on Sunday into Monday.
Ice accumulation is expected.
2. The possibility of high winds for the mountains and foothills
Sunday night into Monday.
3. Very cold air remains across the region next week.
Discussion:
An impactful winter storm is possible on Sunday across the region
with impacts expected across portions of our forecast area,
especially the northern half. A cold, dry airmass will be located
across the region on Saturday night with southwesterly flow aloft
and isentropic lift increasing ahead of a low pressure system across
the Southern Great Plains.
This isentropic ascent will produce light precipitation, mainly west
of Interstate 75, early Sunday morning with precipitation gradually
beginning to increase eastward throughout the day. Very cold, dry
air will be in place at the surface. RAP forecast soundings now
extend out through 18z Sunday, and these soundings show wet bulb
temperatures in the mid 20s. Precipitation will have a difficult
time making it to the surface at first with evaporative cooling
keeping temperatures colder into the afternoon. This is one of these
situations where cold air will already be across the region, and
models often do not resolve the shallow cold air very well. This
causes many global models with coarser resolution to quickly bring
WAA into the area faster than observed. The higher-res mesoscale
model guidance is showing this more realistically with temperatures
across the northern half of the forecast area struggling to get
above freezing until late Sunday afternoon. The RAP soundings are
showing this with temperatures across the central valley remaining
near 31-32 even at 18z Sunday. Overall QPF totals are not very high,
but even light amounts around 0.1 inch would result in hazardous,
icy travel. With the southerly flow, downslope and warming
conditions across the western mountain foothills will result in a
warm nose west of the mountain chain across the foothills. This
means that the highest probabilities of freezing rain ice
accumulation greater than 0.1 inch will be north of Interstate 40
and northwest of Interstate 81. The highest ice accumulation is
expected near the Kentucky line and into southwest Virgina where 0.1
to 0.25 inch of ice accumulation is currently forecast, with locally
higher amounts.
WAA finally brings above freezing temperatures to the region on
Sunday night as the surface low move northeast across the Ohio River
Valley. By Monday morning, winds shift to the WNW/NW as CAA begins
in the wake of a cold front. Scattered light snow showers are likely
on Monday, especially across the higher elevations, as orographic
lift enhances snowfall across the mountains.
For the remainder of the week, we dry out mid-week with a strong,
Arctic high pressure sliding southward out of Canada and into the
mid-Mississippi Valley. Light northerly surface winds will continue
across our forecast area with much below normal temperatures
expected. NAEFS anomalies show temperatures around the 10th
percentile which will result in temperatures about 10 to 15 degrees
below normal.
By the end of the week, another shortwave system may bring some
low chances of precipitation to the region.
&&
.AVIATION...
(00Z TAFS)
Issued at 547 PM EST Fri Jan 3 2025
Any lingering low VFR clouds and possibly a few flurries mainly
north will exit overnight, and VFR conditions are expected for the
period all sites. Winds will generally be from the west and
northwest around 10kts with some higher gusts at times.
&&
.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN 26 44 29 42 / 0 0 10 90
Knoxville McGhee Tyson Airport, TN 21 38 25 36 / 0 0 0 90
Oak Ridge, TN 21 38 25 35 / 0 0 0 90
Tri Cities Airport, TN 19 33 19 34 / 20 0 0 80
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...NONE.
VA...Winter Storm Watch from Sunday morning through Monday evening
for Lee-Russell-Scott VA-Washington VA-Wise.
&&
$$
SHORT TERM...KS
LONG TERM....JB
AVIATION...
Area Forecast Discussion
National Weather Service Omaha/Valley NE
513 PM CST Fri Jan 3 2025
.KEY MESSAGES...
- A strong winter storm will bring a chance of freezing drizzle
Saturday, and then snow to much of eastern Nebraska and
western Iowa Saturday evening through Sunday evening.
- A winter storm warning is now in effect for southeast NE and
extreme southwest IA. 6-10" of snow forecast, with a light
glaze of freezing drizzle before the snow begins. Blowing and
drifting snow also expected. Travel could become very
difficult in this area.
- A winter weather advisory is now in effect for portions of
east central NE and west central IA. 1-4" of snow forecast,
with a light glaze of freezing drizzle before the snow begins.
- Much colder temperatures still forecast early in the week,
with morning wind chill values 10 to 20 below each morning
through Wednesday, with the coldest values in northeast
Nebraska.
&&
.DISCUSSION...
Issued at 330 PM CST Fri Jan 3 2025
We are still expecting a winter storm to impact the region
Saturday through Sunday. The storm is curing moving on the west
cast across western United States. The closed upper low
continues to move across the Rockies into tomorrow, and then
onto the Plains tomorrow night, and then east of the region by
daybreak Monday.
We have upgraded the winter storm watch in southeast NE and
extreme southwest Iowa to a winter storm warning. And we have
issued a winter weather advisory on the northern fringe of this,
for areas from Columbus to Omaha to Red Oak, IA.
This storm system will begin to affect our forecast area during
the day Saturday, but really gets going at peak intensity
Saturday night into Sunday morning. It`s actually a very
challenging winter weather event, and I`ll try to describe some
of that without composing a novel here.
Initially, there may be light snow that spreads into portions of
the area tomorrow morning, but that will be quite light. By
afternoon, as we begin to feel the effects of the upper trough
to the west, the HRRR model has been consistently showing an
area of light freezing drizzle developing, and this is a result
of the not deep enough saturation for ice crystals. While it
will be cold enough aloft for snow, soundings suggest that
the lack of deep layer saturation, combined with the lift from
trough to the west, will allow for a few hours of freezing
drizzle, and if that happens, a light glaze of ice could be put
down before the heavier snow arrives. It`s also important to
note that other models suggest just very light snow Saturday,
and it`s a fine line difference of about 1 degree in temperature.
Best case scenario obviously is that only snow develops, with
no freezing drizzle occurring.
Once the column fully saturates Saturday evening, if there is
any freezing drizzle initially, it turns to all snow, and then
continues across much of the forecast area through Sunday, at
least for the southern half of the forecast area. The forecast
low track has been fairly consistent over the least 24`sh
hours. With the surface low well to our south across OK, with
the closed upper low also passing to our south across KS, this
keeps the heaviest snowfall across our extreme southern forecast
area along the NE/KS border region, with lesser amounts to the
north. The models are also showing the dry air to the north,
with a persistent northerly flow pulling this dry air in, which
limits snowfall on the northern edge. Such that some of the
models are showing a very tight gradient of no snow to a few
inches of snow occurring over a 20-30 mile wide band.
And this leads to the failure modes of this weather system. If
the track changes at all, that very tight gradient of no snow to
very heavy snow will shift north and south. As of right now,
that very tight gradient exists exactly across the Omaha metro
area. In fact, far northern edges of the Omaha metro could see
an inch or less of snow, otherwise known as a typical January
day, while far southern edges along the Platte River could see
2 or 3 inches. And if that zone shifts north or south, it could
change the forecast dramatically. If this shifts south by 20
miles, the Omaha metro area could very well be shut out and
there will be substantial disappointment. It`s within the
envelope of possibility.
As you go farther south, we are still confident in a band of
heavier snowfall from 4 to 10 inches that are forecast for
southeast NE and southwest IA. The Lincoln area is also within
a wide transition zone, such that far northern Lancaster county
might only get 3-4", but southern Lancaster county could get
6-7". Again, any movement in the track of the low will make a
dramatic difference in snowfall amounts at any given location.
Those 10" amounts are forecast along the NE/KS border region and
further points to the south. Don`t forget the chance of
freezing drizzle before the heavier snow tomorrow night, and if
that occurs, it will make things even more slick.
Moving onto the winds, Saturday morning surface winds are from
the east at 5 to 10 mph. As the surface closed low develops
across Oklahoma Saturday night, our winds turn more northeast,
but also increase to 10 to 20 mph, and then become northerly at
15 to 30 mph during the day Sunday, with the higher speeds south
of I80. This will allow for considerable blowing and drifting
of snow in the heavier snow band, such that we feel that travel
will become increasingly difficult, hence the upgrade to the
winter storm warning.
All of the snow begins to end from north to south Sunday
evening, and then no precipitation is in the extended forecast
from Monday through Friday of next week.
While the snow ends, the bitter cold temperatures arrive. We`re
still forecasting well below normal temperatures through the
week, with highs in the teens Monday through Wednesday, and
nighttime lows in the single digits above and below zero. This
could result in morning wind chill values from 10 to 20 below
each morning Monday through Wednesday. Highs are forecast to
climb to the middle to upper 20s by Thursday and Friday, but
that`s still well below normal.
&&
.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 513 PM CST Fri Jan 3 2025
Prevailing VFR conditions are expected to persist into the
overnight hours with ceilings eventually lowering to MVFR
(FL020-025) by 08-11z at KOFK and KLNK, and possibly not until
17z at KOMA. There`s a 20-30% chance of light snow in the 09-15z
timeframe at KOFK and 12-15z at KOMA. Chances for snow mixed
with freezing drizzle increase by Saturday afternoon at KLNK,
and perhaps KOMA.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...Winter Weather Advisory from noon Saturday to 6 PM CST Sunday
for NEZ030-042-043-050>053-065-067.
Winter Storm Warning from noon Saturday to midnight CST Sunday
night for NEZ066-068-078-088>093.
IA...Winter Weather Advisory from noon Saturday to 6 PM CST Sunday
for IAZ069-079-080.
Winter Storm Warning from noon Saturday to midnight CST Sunday
night for IAZ090-091.
&&
$$
DISCUSSION...DeWald
AVIATION...Mead
Area Forecast Discussion
National Weather Service Raleigh NC
913 PM EST Fri Jan 3 2025
.SYNOPSIS...
Arctic high pressure will continue to influence the region through
Saturday night. A storm system will bring rain Sunday afternoon
through Monday, possibly mixing with some freezing rain across the
north.
&&
.NEAR TERM /TONIGHT/...
As of 905 PM Friday...
* Brisk to windy conditions overnight through 2 AM.
Light rain and snow showers that moved through the area earlier this
afternoon/evening were associated with a leading vort max on the
cool side of a unseasonably strong H5 jet streak of over 120 kts as
it pivots across VA and NC. These are now moving into eastern NC
with mostly clear skies in its wake with only scattered cloud cover
at around 6,000 ft. At the surface, CAA behind an Arctic cold front
will allow steep low/mid-level lapse rates to transport momentum
aloft to the surface in the form of strong wind gusts through
roughly 06z. Point soundings from the RAP and HRRR suggest frequent
wind gusts of 25 to 30 kts will be most common, but infrequent wind
gusts of around 40 kts will certainly be possible anywhere across
central NC.
Cold and very dry air behind the front will continue to spill into
central NC with dew points falling into the single digits to low
teens by Sat morning. Overnight lows will settle in the 20s areawide
with low 20s possible in the cool spots of the Piedmont.
&&
.SHORT TERM /SATURDAY AND SATURDAY NIGHT/...
As of 205 PM Friday...
Saturday and Saturday night should be a quiet stretch of weather
with high pressure centered over central Canada and a ridge of high
pressure extending all the way across Iowa, Tennessee, and Florida
to start the day. The ridge of high pressure will weaken as low
pressure develops over the Rockies and moves east into Oklahoma by
Sunday morning. There will still be a bit of a pressure gradient
between the ridge across the Southeast and the departing low
pressure off the East Coast, so winds will be gusty on Saturday, but
not as high as today, likely reaching 15-25 mph. While clouds will
be very few and far between, highs will be noticeably cooler, in the
mid 30s to the mid 40s.
Saturday evening will be clear, with a few clouds beginning to move
in from the west after sunset, although the forecast remains
completely dry. Overnight lows will be similar to tonight`s, with
values in the upper teens through the mid 20s.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
As of 400 PM Friday...
Sunday and Monday:
A mid/upper low will move east from the Southern Plains on Sunday
morning into the TN Valley on Monday, then off the Mid-Atlantic
coast on Monday night as it opens up into a wave. At the surface, an
associated area of low pressure will move from OK into KY/TN on
Sunday and Sunday night, with a secondary low developing over GA/SC
on Monday morning. This secondary low looks to move NE and pass over
central NC on Monday afternoon before moving off the NC coast on
Monday night. Meanwhile strong 1040-1045 mb high pressure will
remain anchored over southern Manitoba and ND.
Clouds will increase across the area on Sunday afternoon, and a band
of WAA-induced precipitation looks to push NE from the TN Valley on
Sunday afternoon. While Sunday`s high temperatures will be in the
40s, ample dry air will be in place with dew points in the teens and
single digits, so temperatures will initially cool into the 30s from
evaporative cooling. It remains uncertain where exactly the wet bulb
freezing line will be, with the NAM continuing to be on the cool
side and indicate upper-20s over the far northern Piedmont, the GFS
keeping the freezing line confined to near the NC/VA border, and the
ECMWF somewhere in between. However, there is also some uncertainty
how much precipitation will even reach the ground with that initial
band, as dew points will be so low, and some guidance indicates it
may largely stay just to our north. The 12z and 18z NAM in
particular backed off on amounts compared to previous runs.
Regardless amounts look light, and lowered POPs from NBM to
slight/low chance in the NW late Sunday afternoon and high
chance/low likely across the north Sunday evening/night.
As for precipitation type, soundings indicate it may start as light
rain or sleet late Sunday afternoon, before transitioning to rain or
freezing rain Sunday evening/night. Any freezing rain potential
should largely stay along and north of I-85, but extend farther east
into the northern Coastal Plain where the highest ice accrual may
end up being if the NAM and ECMWF are correct. South of there,
surface temperatures look warm enough for primarily rain. Southerly
winds ahead of the low and a lack of high pressure to the north,
combined with freezing rain being a self-limiting process, mean the
window for freezing rain should be fairly brief, with temperatures
rising above freezing everywhere after 12z Monday morning. At this
time soundings appear too warm aloft for snow, and this Miller B
type setup is usually unfavorable for it. Impacts look to be pretty
minor with just a light glaze of ice possible over the far north.
But models have been inconsistent and it only takes a slight shift
in track to make a big difference in impacts, so stay tuned for
future updates.
A warm front will push north through central NC on Monday morning,
before the secondary low tracks through the area in the early
afternoon and a cold front pushes through in the late afternoon and
early evening. This will bring a heavier more widespread area of
precipitation Monday morning and afternoon, ending from SW to NE in
the late afternoon and evening. Temperatures will be warm enough
with this round for all liquid, and total amounts of around a half
to three quarters an inch are expected, highest in the NE. The one
exception is a possible brief period of light snow at the very end
on Monday evening in the far NE, which GFS soundings suggest can`t
be ruled out. This is an example of cold air chasing the
precipitation, so any amounts would be very light. The temperature
forecast is still tricky on Monday given the in-situ damming that
will be in place and the low tracking over the area. There is likely
to be a strong temperature gradient somewhere, but for now lean
toward the NAM and Canadian as they tend to do better with handling
these types of events. Forecast highs range from upper-30s to lower-
40s in the far north to mid-50s in the far south. This wedging
should prevent much gustiness from mixing to the surface, but a few
gusts to 20-30 mph can`t be ruled out in the SE. Skies will clear
Monday night and it will stay breezy with NW winds behind the cold
front bringing down lows into the 20s and wind chills in the teens.
Tuesday through Friday:
* Very cold temperatures on the way
In the wake of the departing system, Tuesday through Friday will see
cold and dry conditions as northwesterly flow takes hold over the
area. There is high confidence in well below normal temperatures
during this period, with highs struggling to reach 40 Tuesday and
Wednesday. A potent shortwave trough within the flow is progged to
sweep through the area late Wednesday into Thursday, bringing even
colder temperatures to the area to close out the week. Highs
Thursday will struggle to reach the mid 30s, with only slight
moderation into the upper 30s/lower 40s on Friday. Overnight lows
during this period should be some of the coldest that we`ve seen so
far this season (if not since January 2024) with low to mid teens in
the north and west, and upper teens in the south and east.
&&
.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
As of 632 PM Friday...
There is high confidence in VFR conditions through the TAF period.
Some brief passing -RASN showers are possible at RDU/RWI until ~ 01-
02z with the passage of a cold front and associated upper-trough. No
restriction are expected, but some slightly lower VIS cannot be
ruled out. Confidence in that, however, is too low to mention in the
current TAF. Otherwise, gusty NW winds of 25-30 kt will persist
until 06-07z, after which winds should subside, though not briefly
diminish. Gusts will pick up again Sat morning, ranging from 18 to
22 kt, highest at RDU/RWI. Winds should diminish by early Sat
evening with high pressure building in.
Outlook: VFR conditions are expected until the next frontal passage
on Sunday night to Monday. With this system, there is a high
probability of sub-VFR ceilings and precipitation. Precipitation
should mainly be rain, but a brief period of freezing rain is
possible in the northern portions of the CWA (most favored at
INT/GSO). VFR conditions should return Monday night or Tuesday
morning.
&&
.FIRE WEATHER...
After a cold frontal passage this evening, cool and dry air will
filter into central NC for Saturday. Gusty northwest winds between
25 and 30 mph will continue for the morning and afternoon on
Saturday. The combination of relative humidities between 25 and 30
percent and the gusty winds will be conducive for the formation and
spread of fires over most of central NC except the southern
Piedmont. Most of the region is still in abnormally dry conditions
and also there is some drought across the Coastal Plain. Outdoor
burning is discouraged on Saturday. Please refer to your local burn
permitting authority on whether you can burn. If you do burn, use
extreme caution and ensure fire suppression equipment is readily
available.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Green
NEAR TERM...Swiggett
SHORT TERM...Green
LONG TERM...Danco
AVIATION...Kren/Helock
FIRE WEATHER...Kren