Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/10/25
AREA FORECAST DISCUSSION
National Weather Service Wakefield VA
1025 PM EST Thu Jan 9 2025
.SYNOPSIS...
Cold and dry conditions continue into Friday. Low pressure is
expected to lift northeast from the Gulf coast Friday, tracking
along the Carolina coast Friday night into Saturday, bringing
additional winter weather to the region. Dry conditions return
later this weekend into early next week.
&&
.NEAR TERM /THROUGH FRIDAY/...
As of 900 PM EST Thursday...
Key Messages:
- Similarly cool temperatures for tomorrow with less wind as
high pressure moves over the area.
Little change to the forecast this evening. Transient high
pressure just to our W will keep quiet wx and clear skies
overnight. Temps will be feel similar to last night with lows in
the teens in the piedmont to lower 20s in SE VA/NC NE. A few
single digit readings are possible over the snowpack across the
NW. Wind chill temps remain continue to remain just above Cold
Weather Advisory criteria so will not have any headlines.
Skies will start off clear Friday morning, but as the next low
pressure system moves further east, clouds will begin to build
during the day. High temps for the day will be in the mid 30s
towards the piedmont and upper 30s to 40F in SE VA/NE NC.
&&
.SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/...
945 PM EST Thursday Update...
General trend among the 00z model suite, including among the
hi-res output, has been a continued upward trend in
QPF/snowfall amounts with a slightly more amplified system.
There is also better agreement on the potential placement of a
narrow band of higher totals in the 4-6" range, generally across
the northern tier of the current Winter Storm Warning per the
00z HRRR and NAM. While we will defer the final decision on
headline upgrades to the overnight shift, it is looking quite
likely that the winter storm watches for wrn Chesterfield, the
city of Richmond, and points W will need to be upgraded to a
warning for 3-5" of snow. Additionally, at least advisories will
almost certainly be needed for a tier or two of counties N of
the current watches/warnings, including on the MD Eastern Shore.
Higher uncertainty remains over the SE due to mixing/p-type
concerns, but will also need at least advisories here as well.
As of 400 PM EST Thursday...
Key Messages:
- Winter Storm Warnings now in effect for South Central/Central
Virginia to across Virginia Eastern Shore. Winter Storm Watch
continues for the Central Piedmont Virginia region and coastal SE
Virginia/Northeast North Carolina.
- Moderate to heavy snow is likely with 2-4 inches expected.
Locally higher amounts of 4-6 inches is possible depending on
where the heaviest band of snow develops.
All eyes are on the winter weather system that will impact the area
late Fri night into Sat. The deep trough that has been over the
region this week will move offshore Fri. A low pressure system
over the Gulf Coast will continue to track and make its way NE
to move across the area Fri night into Sat. This low pressure
is of the Miller A type, bringing snow and wintry precip to
much of the SE US, however remaining relatively weak and not
strengthening until well offshore Sat afternoon. Models have
continued to increase confidence in the timing of the event and
snowfall amounts. Precip is expected to start off as all snow
and then transitioning to freezing rain/rain in the SE of the FA
first, then eventually the whole FA as the system pulls further
offshore. Snowfall totals have remained relatively consistent
with previous forecast, with a general 2-4" for most of the
area, with heavier bands potentially allowing 4-6". However, the
location of the highest amounts is dependent on where the
heavier bands of snow end up. Models continue to disagree on
where the heavy bands will lay with the GFS and NAM models in
the 12z run place the higher amounts more on the north side of
the counties in the WSW, while the ECMWF and HRRR place the
higher amounts on the southern side of the warned counties. The
heavier band will be dependent on where FGEN ends up, as the
bands will be to the north of it. With the uncertainty, have
included S Central/Central VA to VA Eastern Shore in a Winter
Storm Warning, where confidence is highest and continued the
Watch for areas with lower confidence for the higher bands.
Further south across NE NC and towards VA Beach, a warm nose will
push thru preventing higher snow accumulations with the likely
precip being rain and/or wintry mix. A light glaze of ice is
possible, but not expecting amounts to accumulate more than a few
hundredths in most areas.
Precip will quickly come to an end by or shortly after sunrise for
western portions of the CWA and by mid morning further to the east.
Skies will clear up afterwards and with temps warming up to the
lower to mid 40s, some snow melting should be allowed.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
As of 320 PM EST Thursday...
Key Messages:
- Slightly warmer Sunday-Monday, with another surge of well
below normal temperatures Tuesday through Thursday. Generally
dry through the period.
Low pressure will be rapidly intensifying well offshore Saturday
night, with sfc high pressure across the TN Valley settling east
into the local area. Mostly clear Sat night with lows in the mid
teens inland to the mid 20s near the coast (it could potentially
be colder well inland depending on snow amounts received with
the Fri night/Sat system). Weak ridging aloft slides off the
coast late Sunday into Monday, allowing enough return flow for a
modest warm up (especially Monday). Highs Sunday in the mid 30s
north to the lower 40s south, with highs Monday ranging from
the upper 40s to near 50F in NE NC to the low-mid 40s across the
north. It remains dry and mostly sunny/mostly clear through the
period. Beyond that, the models are in good agreement with the
next anomalous, deep upper trough diving ESE from the upper
midwest to New england from Monday night through Wednesday.
Expect another round of very cold/well below normal temperatures
to prevail, with highs mainly in the 30s and lows mainly in the
teens and a blustery NW wind much of the time. At this time,
wednesday looks to be the coldest day with highs only in the
upper 20s to lower 30s for the northern 1/2 of the CWA and in
the mid 30s over the south. Cold Weather Advisories may be
needed at times.
&&
.AVIATION /04Z FRIDAY THROUGH TUESDAY/...
As of 625 PM EST Thursday...
No flight restrictions are expected through early Friday
evening. Clear skies are expected tonight, with gradually
increasing/thickening mid-high clouds Friday morning into the
afternoon ahead of our next wintry system. WNW winds of 8-12 kt
tonight...a few gusts to 15-20 kt are possible at SBY and ORF.
Additionally, a somewhat stable near-surface inversion and a
belt of stronger winds aloft could lead to some LLWS at SBY and
RIC between 00 and 09z Friday. Continued the TAF mention at SBY
and introduced it at RIC w/ this 00z update. Winds Friday will
be significantly lower, generally 5-10 kt, while eventually
backing to the W and then SW later in the day.
Outlook: A quick-moving winter storm affects the region Fri
evening through Sat morning. Light to moderate SN begins after
00z, first across the Piedmont, reaching most terminals by
03-06z Sat. Periods of +SN are possible after 06z. A changeover
to IP or -FZRA and then RA is expected early Sat across the SE
(including ECG/ORF). Significantly reduced VSBY and IFR/LIFR
CIGs can be expected in SN. Dry conditions return Sat afternoon
with VFR prevailing through the rest of the weekend.
&&
.MARINE...
As of 330 PM EST Thursday...
Key Messages:
- Gale Warnings continue for the Chesapeake Bay, coastal waters, and
the Lower James River into tonight.
- Another area of low pressure approaches the region late Friday and
moves across the area Saturday, likely bringing solid SCA conditions
back to the local waters.
- NW winds and unsettled marine conditions return late Monday into
the middle of next week.
Gale force northwesterly gusts continue across northern coastal
waters into the overnight due to the tight, albeit slowly
slackening pressure gradient between the low off the Canadian
Maritimes and the high over the Ohio Valley. The winds will
gradually subside late tonight into early Friday morning as the
high shifts east helping to relax the pressure gradient. Gale
headlines will need to replaced with SCAs as conditions over
northern waters into early Friday.
A brief period of sub-SCA conditions is forecast Friday morning
into early aftn, as high pressure moves over the region and
then offshore ahead of the next system approaching from the SW.
NW winds are forecast to strengthen again Saturday afternoon
with a brief period of solid SCA conditions expected. 12z/9
guidance suite and local wind probs show only a low chance for
gale conditions with this next system and these are mainly
focused well offshore as the low deepens off hte coast Saturday.
Conditions improve on Sunday and linger into Monday as high
pressure moves in from the west. Unsettled conditions return
late Monday into the midweek period as low pressure to the north
brings another cold front across the waters.
3-5 ft waves in the Ches Bay this evening will gradually subside
overnight into Friday before increasing back into the 2-4 ft range
as winds increase behind Saturday`s system. Seas build to 5 to 8 ft
this evening before decreasing below 5 ft by Friday afternoon. Seas
build back to 3-5 ft in offshore flow Saturday into early
Sunday.
&&
.TIDES/COASTAL FLOODING...
Prolonged NW winds have allowed tidal anomalies to fall across the
region. The lowest levels were across the Currituck Sound where the
Low Water Advisory continues until 6 AM Friday. A more widespread
period of Low Water Advisories is likely tonight into Friday behind
the NW surge. Some locations across NC and MD may approach -2 ft
tidal departures during this time. Low Water Advisories are needed
again for tonight`s low tidefor the upper James River and the
Rappahannock River. Will also need low water advisories for the
Atlantic waters of the VA Eastern Shore. As the winds subside
tomorrow, low water conditions should improve.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...None.
NC...Winter Storm Warning from 7 PM Friday to 1 PM EST Saturday for
NCZ012.
Winter Storm Watch from Friday evening through Saturday
afternoon for NCZ013>017-030>032-102.
VA...Winter Storm Warning from 7 PM Friday to 1 PM EST Saturday for
VAZ060-065>067-079>090-092-093-099-100-514-516-518-520-
523>525.
Winter Storm Watch from Friday evening through Saturday
afternoon for VAZ061-068-069-095>098-513-515.
MARINE...Small Craft Advisory until 10 AM EST Friday for ANZ630>632-634.
Low Water Advisory until 7 AM EST Friday for ANZ633.
Small Craft Advisory until 7 AM EST Friday for ANZ633-638.
Small Craft Advisory until 4 AM EST Friday for ANZ635>637.
Low Water Advisory until 4 AM EST Friday for ANZ637.
Gale Warning until 4 AM EST Friday for ANZ650-652.
Low Water Advisory until 1 AM EST Friday for ANZ654-656.
Small Craft Advisory until 1 PM EST Friday for ANZ654.
Small Craft Advisory until 4 PM EST Friday for ANZ656-658.
&&
$$
SYNOPSIS...LKB
NEAR TERM...KMC/SW
SHORT TERM...AJB/KMC/SW
LONG TERM...LKB
AVIATION...SW
MARINE...MAM/MRD
TIDES/COASTAL FLOODING...
Area Forecast Discussion
National Weather Service La Crosse WI
841 PM CST Thu Jan 9 2025
.KEY MESSAGES...
- Light flurries and light snow tonight. Little, if any,
accumulation expected.
- Flurries Friday afternoon.
- Accumulating snow likely from late Saturday Night into Sunday.
- At this time, snow amounts look to range from 1 to 4 inches.
The highest totals will be be north of Interstate 90 in
Wisconsin. The highest probabilities (40-60%) for 3 inches or
more of snow is currently north of Interstate 90 in Wisconsin.
&&
.UPDATE...
Issued at 823 PM CST Thu Jan 9 2025
Last several runs of the HRRR/GFS/RAP/NAM have continued to
suggest the low levels will remain saturated overnight after the
return of dry air in the DGZ cuts off the ongoing light snow,
opening the door to potential freezing drizzle if enough lift
occurs in the low levels. On this point, only the HRRR is
bullish on low level lift overnight in the post-frontal
environment. As cold advection aloft continues Friday morning,
the top reaches of the low level saturated layer will cool to
below -12C, suggesting any hydrometeors would be ice crystals.
Therefore, while freezing drizzle was introduced to the forecast
tonight into early Friday morning, kept mentions to a slight
chance or less (15 percent or less) and retained the already
included flurries through much of the day tomorrow.
Ferguson
&&
.DISCUSSION...
Issued at 259 PM CST Thu Jan 9 2025
Tonight
The models continue to short that a northern shortwave trough
over the Canadian Prairies will move east into Hudson Bay.
Meanwhile, a southern stream shortwave trough will move east
from the Southern Plains in the western Gulf States. Like the
past couple of days, the 09.12z models are continuing to show
that the frontogenesis will weaken as it moves east across the
area. As a result, the snow totals for tonight continue to range
from a dusting to maybe a half inch. For La Crosse, the GEFS
has went down from 100% chance of a 1/10th of an inch or more
yesterday to 33.3 percent in the 09.12z GEFS. There has been no
change in the ECMWF ECE which has consistently showed that
La Crosse will see anywhere from 1/10th to 1/2 inches of snow.
Friday
Another shortwave trough will move southeast through the Upper
Mississippi River Valley. Like the past couple of days, the
moisture is primarily located between 950 and 800 mb. The
combination of cyclonic flow aloft and steep low level lapse
rates between 950 and 900 mb will result in scattered flurries
during the afternoon.
Saturday night through Sunday morning
Unlike the past couple of days, the low pressure area is moving
through the region faster than originally thought. This is due
to the cyclogenesis occurring more over Michigan instead of over
the Upper Mississippi River Valley. This reduces the time in
which light snow has the chance to fall across the area. In
addition, there was a shift northward in the track of the low
pressure area. While this is the case, there is still some
uncertainty on the placement of the deformation band in the wake
of this system. With many models currently in agreement that the
deformation band will likely stay along and north of Interstate
90. The highest probabilities (40-60%) for 3 inches or more of
snow is currently north of Interstate 90 in Wisconsin.
Monday Night through Wednesday
Much colder air spills southward into the region in the wake of
the Sunday low pressure area. Depending on how much snow falls
across the area, we might have to reduce our current
temperatures 5 to 10 degrees.
&&
.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 602 PM CST Thu Jan 9 2025
Light snow and associated reductions to MVFR and IFR remain the
main concern for aviation interests over the next 24 hours. Cold
front and associated snow is beginning to advance eastward
across the area, with ceilings expected to reduce to MVFR/IFR
over the next 6 hours. As for visibility reductions, areas to
the west of the Mississippi River valley should see MVFR
conditions with occasional drops to IFR while farther east, with
snow reducing in intensity as the front advances, occasional
drops to MVFR visibilities are favored. After the main snow
departs tonight, sporadic flurries may occur during the day
Friday - with low confidence in occurrence and timing, these
flurries are not included in the TAFs.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&
$$
UPDATE...Ferguson
DISCUSSION...Boyne
AVIATION...Ferguson
Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
554 PM CST Thu Jan 9 2025
...New AVIATION...
.SHORT TERM...
(Tonight through Friday night)
Issued at 232 PM CST Thu Jan 9 2025
Key Messages:
- Well below normal high and low temperatures will continue through
the short term period.
- Another round of light rain will develop late this evening from
north to south.
- A Freeze Watch is in effect for late Friday night into early
Saturday morning across the Northern Ranchlands.
Well below normal temperatures will continue through the end of the
first full week of January across Deep South Texas. The latest
observations and RAP guidance indicates a coastal low continues to
track northward along the Lower Texas coast, just north of our
forecast area over the Gulf waters. Despite a lull in precipitation
this afternoon, another round of light rain will develop later this
evening as forcing for ascent associated with an upper level
trough/closed low overspreads across the state and interacts with
favorable moisture content across the region. Rain chances will
increase from northwest to southeast late this evening, and should
come to an end Friday morning. Temperatures tonight won`t vary by
much once again tonight, with lows ranging from the upper 30s across
the Northern Ranchlands to low 40s across the Lower RGV. In
combination with persistent northerly winds around 10-15 MPH and
occasional gusts around 20 MPH, "feels like" temperatures Friday
morning will range from the upper 20s across the Northern Ranchlands
to mid 30s across the RGV.
It will still feel quite chilly on Friday with highs in the low 50s
as overcast skies and northerly winds persist. However, there is a
potential for temperatures to remain in the upper 40s, similar to
the past several days due to persistent cold air advection. There
are still some inconsistencies among high res guidance and
probabilistic NBM guidance, but if subsequent runs continue to trend
on the colder side, it is likely high temperatures will remain in
the upper 40s Friday afternoon.
We continue to monitor the potential for sub freezing temperatures
late Friday night into early Saturday morning across portions of the
Northern Ranchlands. Probabilistic guidance indicates there is a
medium to high chance (50-70%) of temperatures less than 32 degrees
across most of the Northern Ranchlands early Saturday morning. The
biggest question will be whether clouds will clear quickly enough to
promote efficient radiational cooling processes during this time.
The latest suite of HREF guidance indicates there may be sufficient
clearing with 20-40% cloud cover, which may allow for temperatures
to fall to around 30-32 degrees early Saturday morning. We`ve opted
to issue a Freeze Watch for Zapata, Jim Hogg, Brooks, and Kenedy
counties to account for this potential from 3 AM to 9 AM Saturday
morning and will continue to monitor trends.
&&
.LONG TERM...
(Saturday through next Thursday)
Issued at 232 PM CST Thu Jan 9 2025
Key Messages:
-A Freeze Watch in effect until 9 AM Saturday.
-Below normal temperatures expected through the long term.
-Rain chances taper off for the weekend but return for the workweek.
A cold start to the long term period with Saturday morning
temperatures in the low 30s in the northern Ranchlands to near 40 in
the lower Valley. A freeze watch is in effect beginning late Friday
night into until 9 AM Saturday morning. As surface high pressure
moves northeast through the day Saturday, temperatures will warm
into the mid to upper 50s. Will continue the warming trend into
Sunday where highs will reach the mid to upper 60s.
Another mid/upper level trough will move through the Plains on
Sunday which will bring another cold front through Deep South Texas
Sunday night. Will see slightly cooler temperatures on Monday in
wake of the front with highs in the upper 50s to low 60s, with
similar afternoon highs through Wednesday. Overnight, lows will
gradually warm through the period. A return to southeasterly flow on
Thursday will begin to warm temperatures once again, but still
remain below seasonal norms.
Dry conditions are expected through the weekend. As the
aforementioned cold front passes, rain chances will return becoming
enhanced Tuesday and Wednesday as an inverted trough develops along
the coast.
&&
.AVIATION...
(00Z TAFS)
Issued at 552 PM CST Thu Jan 9 2025
MVFR to IFR conditions are expected to generally continue into
Friday, before conditions gradually improve west to east. The
chance of light rain or drizzle returns tonight, especially late
tonight, also ending west to east into Friday afternoon. Winds
remain northwesterly and breezy through this TAF period.
&&
.MARINE...
Issued at 232 PM CST Thu Jan 9 2025
Tonight through Friday night...Adverse marine conditions will
continue through the period as a coastal low continues to drift
north along the Lower Texas Coast. Northerly to northwesterly winds
around 20-25 knots with occasional higher gusts will maintain
elevated seas around 7-9 feet with occasional higher seas through
late Friday night. A Small Craft Advisory will remain in effect for
the Gulf waters. Winds and seas should begin to subside late Friday
night into early Saturday morning.
Saturday through Wednesday...Improving marine conditions are
expected on Saturday. Another cold front will push through the
waters off the lower Texas coast late Sunday with winds and seas
increasing in its wake which will lead to Small Craft Advisory
conditions beginning Monday morning. While winds will decrease
headed into Tuesday and Wednesday, wave heights will remain elevated.
Rain chances will continue through the period, briefly drying out on
Saturday.
&&
.PRELIMINARY POINT TEMPS/POPS...
BROWNSVILLE 42 50 41 56 / 100 70 10 0
HARLINGEN 37 51 36 57 / 90 50 0 0
MCALLEN 40 54 40 61 / 90 30 0 0
RIO GRANDE CITY 38 53 35 58 / 90 20 0 0
SOUTH PADRE ISLAND 46 53 46 57 / 100 80 10 0
BAYVIEW/PORT ISABEL 40 52 39 56 / 100 70 10 0
&&
.BRO WATCHES/WARNINGS/ADVISORIES...
TX...Freeze Watch from late Friday night through Saturday morning for
TXZ248>251-351.
High Rip Current Risk through Friday afternoon for TXZ451-454-
455.
GM...Small Craft Advisory until 6 PM CST Friday for GMZ150-155-170-
175.
&&
$$
SHORT TERM...22
LONG TERM....68
AVIATION...56-Hallman
Area Forecast Discussion
National Weather Service Columbia SC
656 PM EST Thu Jan 9 2025
.SYNOPSIS...
A cold and dry air mass remains in place through tonight. An
impactful winter storm is expected to push into the area on
Friday and Friday night, yielding sleet and freezing rain across
the northern 2/3rds of the forecast area. A Winter Storm Warning
and Winter Weather Advisory remain in effect for tomorrow and
tomorrow night because of this. Storm system is forecast to
exit on Saturday morning, with dry and cold weather continuing
well into next week.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
Key Message(s):
- Cold and dry with high pressure building into the area.
High pressure over the Ohio and Tennessee River Valleys
continues to push into the area tonight ahead of the incoming
system, leading to clear skies to begin the night. Very dry air
is also in place over the area, with dew points currently in the
low to mid teens across the region. These factors are leading to
efficient radiational cooling to begin the night. In fact,
temperatures have fallen around 10 degrees in the past hour.
Expect temps to continue dropping rapidly into the lower to mid
20s. Cloud cover from the approaching system begins to filter
into the region around midnight, maybe a bit sooner for the CSRA
based on latest satellite imagery. Temperatures are expected to
remain relatively steady for the rest of the night into
daybreak.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/...
Key Message(s):
- A Winter Storm Warning is in effect from 10am Friday until 7am
Saturday for our northern and northwestern counties.
- A Winter Weather Advisory is in effect from 10am Friday until
4am Saturday for our counties along and just south of the I-20
corridor.
- Confidence is high in an impactful Winter Storm on Friday and
Friday night, with the greatest impacts expected across the
northern forecast area.
- Some uncertainty regarding surface temperatures remains, especially
in the Advisory area, but confidence has grown over the
previous 24 hours.
============================================
SYNOPTIC OVERVIEW
============================================
12z upper air analysis reveals deep, positively tilted upper level
trough across the western CONUS, progged to translate eastward over
the next 36 hours. An intense upper level jet is associated with
this, forecast to become anti-cyclonically curved over the southern
US over the next 18 hours. Convergence ahead of this is forecast to
drive an arctic high pressure system eastward from the OH/TN Valley
by Friday morning. The airmass associated with this is of Arctic
origin, with temperatures well below normal and dewpoints in the
single digits to lower teens. Expecting temps to generally be in the
low or mid 20s to start the day on Friday, with thick mid and upper
level cloud coverage overspreading the region shorty before sunrise
Friday. Upper level ascent will increase through the day, with an
initial band of warm air advection precipitation forecast to push
eastward over the area. The airmass will be very dry in advance of
this, with dewpoint depressions in the 20F range. As a result, it is
uncertain whether we actually get much precipitation to mix to the
surface.
More large scale forcing, featuring strong warm air advection,
anomalously strong moisture advection (90th+ percentile per NAEFS),
and strong height falls/vorticity advection, will overspread the
forecast area. Another area of dry air is expected to briefly
overspread the FA and allow for more wet bulbing as this precip
approaches, with temps generally below freezing in the northern
2/3rds of the forecast area at the onset of precipitation. The warm
nose will increase quickly as a 30-40 knot LLJ overspreads the area,
changing anything that is initially sleet to freezing rain from
south to north. This precipitation could be fairly efficient,
especially along and north of I20. A band of strong frontogenesis is
likely to develop within the strong warm advection regime, and
should combine with the strong moisture transport to yield decent
precipitation rates despite this being a quick hitting storm. Temps
along the I20 corridor are likely to bump up above 32F sometime
after 9p or 10p, with the northern forecast area explicitly forecast
to remain below freezing now. Rain is expected to generally
decrease from west to east early on Saturday morning after 2am.
============================================
IMPACTS & FORECAST UNCERTAINTIES
============================================
Impacts may begin as early as Friday afternoon with the passage of
the initial isentropic band of precipitation. While it seems too dry
to really yield much in the way of precipitation or impacts, some
guidance is more bullish on this precip reaching the ground (CAN/GFS
guidance). This initial batch of precipitation is likely to be a mix
of rain/snow/sleet if it does reach the ground, as soundings are
generally isothermal across the forecast area. The overall trend
today amongst guidance not named the HRRR (HRRR begins too warm and
too moist Friday given lack of airmass modification expected in the
surface high) has been towards a slightly colder & wetter solution.
Both of those things make sense for a couple of reasons. For
starters, the airmass in advance of this system is outside of
typical climatology in terms of just how cold and dry it is. For
example, it is nearly 2p here at CAE & we have had sunshine &
downslope flow all day and that has barely gotten us to 40F. The
surface high that will push over the region tonight features very,
very dry air and should yield ideal radiational cooling
conditions, setting up Friday morning to be quite cold, with
temps expected in the lower to mid 20s. Most operational
guidance was warmer than this, and with copious cloud cover &
wet-bulbing expected with precipitation, it will be difficult to
get temperatures warmer than the mid 30s across most of the
forecast area.
Secondly, the models trending wetter make sense given the overall
synoptic setup. Robust warm advection combined with strong moisture
transport vectors should yield efficient precipitation rates
across the forecast area. So overall QPF has bumped up a bit
across the central and northern FA, which is increasing
confidence in a more impactful freezing rain and sleet event
across the northern forecast area.
There is greater confidence in sensible weather impacts across the
forecast area with this forecast package than there was 24 hours
ago, primarily owing to the cooler, wetter solutions that have come
in overall. Confidence is high enough to upgrade the Winter Storm
Watch to a Warning with this package for up to 0.25" of freezing
rain accumulation and up to 0.5" of snow/sleet. These accumulations
could create challenges with travel on Friday night, and may put
strain on area trees. This is especially true across the western
Midlands and CSRA where the trees are still weak from Hurricane
Helene`s impacts back in September. A Winter Weather Advisory will
be issued along the I20 corridor, including the Augusta and Columbia
Metro areas. This area can expect a trace of freezing rain up to
maybe 0.2" if temps remain cold enough long enough.
This is the primary question overall with this system - what does
the surface profile look like. Confidence is fairly high that the
northern portion of the forecast area will stay below freezing for
the duration of the event, with sleet the likely onset precipitation
between 5p and 8p, changing over to all freezing rain between 9p and
11p. Soundings generally support a shallow enough warm layer and
deep enough cold layer in the north to yield an extended period of
sleet. While sleet may cut into the freezing rain totals a bit, it
is likely that this may exacerbate travel issues especially on
bridges and secondary roads where sleet is more prone to
accumulation. In the winter weather advisory, surface temperatures
are just less certain. The surface sub-freezing airmass is likely to
be so shallow that freezing rain will be the predominant precip type
for much of the event. But when and where any given area
changes over the plain rain is tough to pin down in that area.
An extended period of sub freezing temperatures any longer than
is currently forecast could yield a more impactful event.
Similarly, a 1F increase in temps from 31.5F to 32.5F can yield
a non-event. It is just so difficult to forecast it that exactly
and when it happens. Confidence is high that our southern tier
of counties is likely to remain above freezing for much of the
event as they`ll be too close to the surface low to really
support much in the way of freezing rain. Make preparations to
avoid travel across the forecast area on Friday night if at all
possible. Isolated power outages are also possible, especially
in the Winter Storm Warning area.
Precipitation is expected to quickly exit stage right after 3a-6a on
Saturday, with cold and dry air returning to the area. Thankfully,
temps are likely to rise above freezing by Saturday afternoon, which
should allow the melting of ice across the area. Highs on Saturday
should be in the low to mid 40s, with overnight lows returning to
the 20s.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
Key Message(s):
- Brief warm up followed by more cold weather
High pressure aloft moves offshore on Monday in response to a fast
moving shortwave trough passing well to the north of the region.
Temperatures on Monday should reach normals which is the first time
in the region in almost two weeks. The warm up should be brief with
a reinforcing shot of cold Canadian air moving in behind the
shortwave for the rest of the week. Expect temperatures to be 5 to
10 degrees below normal Tuesday through Thursday. Thankfully it
should be dry during this part of the forecast period.
&&
.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
Although VFR conditions still expected through the TAF period,
mixed bag of precip will be moving in through the morning
Friday.
Clear skies to start off the taf period, with some cirrus moving
into the region after midnight. Ceilings will remain vfr through
the majority of the day on Friday, although they are expected to
be lowering through the day as precip begins moving in and lower
levels slowly moisten up from the top down. Some guidance does
indicate higher probability of beginning to fall into mvfr or
lower conditions late in the period, but majority of any lower
ceilings not expected until after 00z Saturday.
In addition to the clouds, a mixed bag of precip will be moving
into the region after sunrise, impacting the CSRA sites of
ags/dnl by 15z. Slightly later at cae/cub/ogb. At all sites the
initial precip will be rather light, and do expect to have a
mixture of rain/snow/sleet through 18z. A change over to all
rain should occur through the afternoon, although temperatures
may hover close to freezing. This will bear watching as a slight
change on surface temperatures would cause a change in surface
precip type. With that said, the main period with potential for
freezing rain should occur close to and after 00z Saturday.
Winds light and variable overnight, then shifting easterly
through the day on Friday.
EXTENDED AVIATION OUTLOOK...Deteriorating conditions with
ceiling and visibility restrictions possible Friday night into
early Saturday morning as low pressure over the Deep South moves
northeast across the area. Wintry precipitation is possible
Friday night. Restrictions ease on Saturday with no additional
aviation concerns through Tuesday.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...Winter Storm Watch Friday morning for SCZ016-018-020>022-025-
026-115-116.
Winter Storm Warning from 10 AM Friday to 7 AM EST Saturday
for SCZ016-018-020>022-025-026-115-116.
Winter Weather Advisory from 10 AM Friday to 4 AM EST Saturday
for SCZ027>031-037-038-135-136.
GA...Winter Storm Watch Friday morning for GAZ040.
Winter Storm Warning from 10 AM Friday to 7 AM EST Saturday
for GAZ040.
Winter Weather Advisory from 10 AM Friday to 4 AM EST Saturday
for GAZ063>065.
&&
$$
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1037 PM EST Thu Jan 9 2025
.SYNOPSIS...
An area of low pressure will track from the Gulf Coast and reach
the western Carolinas late Friday into early Saturday. As the low
approaches, deeper moisture will spread over our area with wintry
weather expected. The wintry weather should end Saturday morning
as the low moves off the Atlantic Coast. In its wake, dry and cold
weather returns and lingers thru early next week.
&&
.NEAR TERM /THROUGH SATURDAY/...
As of 1018 PM Thursday
Key Messages:
1) Confidence is high that a winter storm will impact the area
Friday morning through early Saturday morning.
2) No significant change to previous thinking. Forecast appears to
still be on track. Interim model runs kept a very slight upward
trend in precip amounts across the region, but not enough to
suggest any significant increase in snow/ice amounts yet.
3) Regardless of precipitation type, increased QPF and resulting
storm total snow, sleet and ice forecast supports the winter storm
warning for the entire area.
No mid-course corrections suggested by the latest model
guidance. Our forecast remains in the envelope of model
solutions, between the recent HRRR runs that continue to favor
the warning-criteria snow across the mtns and I-40 corridor, and
the NAMNest that has more freezing rain south of I-85. Doubtful
at this point that any model trend could develop that would cause
us to alter the snow and ice fcst substantially at this point. In
the mean time, satellite imagery shows the leading edge of the
high clouds rapidly approaching from the west, about to reach the
western edge of the fcst area at 11 pm. Thickening clouds after
midnight looks like a safe bet. A slightly earlier cloud up will
also not affect the fcst because the leading edge of the precip
will not reach the area until after daybreak if the new CAMs
are any indication. Dew points continue to run lower than fcst,
suggesting that our wintry precip type forecast is in good shape
once the precip arrives after daybreak.
Otherwise...Sprawling high pressure with arctic origins remains
entrenched across the region this evening with a cold and dry
airmass in place. Farther upstream, a southern stream trough
continues to dig across the Desert Southwest and northern Mexico as
intense Pacific jet energy dives down the Rockies. A northern stream
trough is also dropping across the Midwest and into the Great Lakes
region. Upper divergence overspreading a coastal baroclinic zone
draped along the Gulf Coast has instigated surface cyclogenesis
along the southeast Texas coast. With time, the surface low will
shift east and lift across the Gulf states and into far southern
Georgia by tomorrow evening. While the southern and northern stream
fail to fully phase, substantial upper divergence and increasing
forcing for ascent will allow for a blossoming precipitation
shield to overspread the area starting tomorrow morning through
early Saturday morning.
An initial wave of precipitation will slide across the area in
association with a band of low- to mid-level frontogenesis. Profiles
will quickly saturate with surface wetbulb temperatures well below
freezing across the entire area. Almost everyone will likely see
at least a quick burst of snow at onset. Thereafter, confidence
is high that a prominent warm nose will lift into the area in
association with a 40-50kt low-level jet. This will result in
snow changing over to sleet and eventually freezing rain. This
continues to be strongly supported by the NAM solution (albeit
maybe a degree or two too warm with the warm nose) along with
the 12z suite of CAMs. Sleet may mix in with snow, or become
the predominate precipitation type entirely, as far north as
the I-40 corridor and even portions of the mountains. Freezing
rain will quickly become the main precipitation type south of
I-85 with a continued mix of sleet and freezing rain along the
I-85 corridor. The highest elevations, far northern mountains,
and foothills along and north of I-40 are likely to remain all
snow the longest before sleet mixes in and cuts back on totals.
Of important note, though, is a notable uptick in QPF seen in nearly
every member of guidance. In some cases, especially across the North
Carolina foothills and Piedmont, QPF has nearly doubled from what
was previously expected. Thus, while mixed precipitation types will
generally result in lower snow totals, additional moisture and sleet
is expected to prove sufficient to reach warning criteria. Thus,
the entire area has been upgraded to a winter storm warning for
heavy mixed precipitation. The highest snow totals are still
expected across the southwest mountains with higher totals now
forecast across the northern mountains as well. A local minimum
in snow/sleet may be realized across the French Broad Valley due
to downsloping. Snow/sleet totals have also increased along and
north of I-40. Sleet will begin to cut into snow totals even more
between I-40 and I-85. The I-85 corridor itself is expected to
be a big mixed bag of several hours of snow changing to a lot of
sleet and then ending with a couple tenths of an inch of ice. Some
locations near or just north of I-85 may see upwards of 2" or even
isolated 3" of pure sleet. Ice may become increasingly problematic
south of I-85 where duration of snow/sleet will be much more limited
before the warm nose transitions precipitation to all freezing
rain. Here, ice accumulations are forecast to range from 0.2-0.35"
with isolated higher amounts not out of the question.
Regardless of location and precipitation type, impacts are expected
to be potentially significant. Multiple days of cold weather has
resulted in cold ground/road temperatures. Wetbulb temperatures
are also supportive of surface temperatures in the mid to upper
20s across much of the area through the event with the wetbulb
freezing line south of the area. Travel impacts will quickly ramp up
following precipitation onset and the amount of sleet/ice expected
could make travel quite difficult. Some melting will likely occur
Saturday afternoon as clouds dissipate and temperatures warm above
freezing, but secondary roads and shaded locations will likely
see very little melting. Snow showers will also continue along
the Tennessee border into Saturday afternoon with additional light
accumulations likely.
&&
.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
As of 2:45 PM EST Thursday: the short-term fcst picks up at 00z
on Sunday with upper trofing moving off the Atlantic Coast and
low-amplitude upper ridging building over the Southeast in the
trof`s wake. Upper ridging will linger over the Southeast into
early next week, but will get flattened/suppressed from the NW
as broad upper trofing amplifies over the Great Lakes. At the
sfc, broad high pressure will be spreading over our region from
the west as the period begins late Saturday. The high will linger
over our area into early next and is expected to get reinforced
from the west by the end of the period late Monday into Tuesday.
As for the sensible wx, conditions should remain dry and with
below normal temperatures thru the period.
&&
.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
As of 2:35 PM EST Thursday: the extended fcst picks up at 00z on
Tuesday with broad and flat upper trofing over the NE CONUS and
flat upper ridging over the SE CONUS. Over the next few days, the
upper trof will gradually dig further southward and migrate east-
ward and is expected to be moving off the Atlantic Coast by the
end of the period next Thursday. At the sfc, broad high pressure
will be spreading over our area from the west as the period begins.
The high gets reinforced from the NW late Tues/early Wed. Most of
the long-range guidance has a weak/dry cold front moving thru our
area on Wed with another round of high pressure in its wake to end
the period. The colder temperatures are expected to return for most
of the period, with values at least 10 degrees below climatology
thru mid-week.
&&
.AVIATION /04Z FRIDAY THROUGH TUESDAY/...
At KCLT and elsewhere: VFR conditions at all terminals through
Friday morning with increasing high and mid clouds. During that
period, wind will be light NW to N or variable. Conditions will
deteriorate rapidly as precipitation spreads west to east in the
late morning through early afternoon. Most terminals will likely
see at least an initial period of light snow as the precip starts,
which will bring the ceiling down to MVFR. After about a two hour
period, more significant precip will work its way to the ground,
most likely staying mainly snow at KAVL and KHKY, and a mix of
snow and sleet at the Upstate terminals and KCLT. AS this happens,
the ceiling and vis will come down to IFR and LIFR. At KCLT,
a changeover to FZRA is expected in the late evening as warmer
air moves in above the sfc.
Outlook: The precip should move out in the early morning hours
on Saturday. Dry weather returns thereafter and persists into
next week.
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...Winter Storm Warning from 7 AM Friday to 7 AM EST Saturday for
GAZ010-017-018-026-028-029.
NC...Winter Storm Warning from 7 AM Friday to 7 AM EST Saturday for
NCZ033-035>037-048>053-056>059-062>065-068>072-082-
501>510.
SC...Winter Storm Warning from 7 AM Friday to 7 AM EST Saturday for
SCZ008>014-019-101>109.
&&
$$
SYNOPSIS...JPT
NEAR TERM...PM/TW
SHORT TERM...JPT
LONG TERM...JPT
AVIATION...PM
Area Forecast Discussion
National Weather Service Wilmington NC
1009 PM EST Thu Jan 9 2025
.SYNOPSIS...
Arctic high pressure will build in through Friday ahead of a
storm system that will bring non-liquid precip to areas away
from the coast. The system will bring rain, freezing rain, and
possibly some sleet late Friday into early Saturday, with a
Winter Weather Advisory in effect. Bitterly cold and dry
weather will then return into mid next week.
&&
.UPDATE...
No major changes with this fcst update. Massaged the hourly
cloud coverage thru the night, especially early on given the
clear skies illustrated by latest sat imagery.
705pm Update...
With wind gusts no longer occurring, temps have been dropping
faster than the fcst dictates. Adjusted hourly temps and to a
degree the hourly dewpoints to accommodate this current trend
into the evening and overnight. We don`t quite decouple but
sheltered areas may experience a further drop in temps, like
BackIsland RAWS Station in Holly Shelter Pender County, NC.
Still remaining above Cold Weather Advisory thresholds taking
into account the area coverage.
519pm Update...
Raised a SCA for the local waters good from 10pm Fri thru 4pm
Sat. Seas and especially winds will meet thresholds as low
pressure, with some ongoing intensification, moves nearly
overhead Fri night into early Sat.
&&
.NEAR TERM /THROUGH FRIDAY NIGHT/...
The near term forecast at least from a time frame standpoint
has been extended through 12 UTC Saturday to maximize continuity
through the event beginning late tomorrow. For the extreme near
term/bookkeeping activities lows for tonight remain on the cold
side but with winds much lighter the need for a cold weather
advisory is mostly gone. The storm system currently developing
across the Gulf of Mexico will move across the area later Friday
through Saturday morning.
Overall I`m impressed by the model consistency with regards
to the GFS and ECMWF. The GFS has consistently shown less
chance of freezing rain accumulations inland while the ECMWF is
a little more bullish on the extent of the frozen precipitation
but somewhat lighter in qpf amounts. Overall this could be
considered noise and in not really unexpected as there are
slight wobbles with each particular cycle. Now we have the high
resolution guidance in play as well. The NamNest shows a more
aggressive solution while the HRRR at leas the 12 UTC run has
very little in the way of frozen precipitation. I will be
leaning toward the NAM just a little bit for this package.
As the relatively weak area of low pressure moves across the
southeast later Friday and offshore early Saturday an early
swath of light qpf will move south to north across the CWA.
Even though temperatures will likely be somewhat above freezing
the thermal profiles could thread the needle to allow a few snow
flakes along with sleet to occur. By early evening more qpf
develops and with dewpoints still below freezing allowing
freezing rain to develop with perhaps more sleet via the GFS. In
time the rain gets heavy enough to allow wet bulb temperatures
to reach freezing or just below for a few hours. Finally the
precipitation slowly transitions to all liquid but the trend
will be a grind. Overall the freezing rain shield has been
expanded to the south and east and a winter weather advisory
will be issued to address. The freezing rain amounts have been
slightly increased but just enough sleet may enter the qpf total
to keep amounts in advisory criteria. This for far northwest
areas as points south and east have lighter amounts. It should
be noted the HREF/FRAM ensemble mean numbers are in good
agreement with these amounts and trends. Finally highs Friday
will be in the middle to upper 30s with Saturday morning lows
upper 20s well inland and lower 30s along the coast.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
The period will begin with weak Arctic high pressure still
holding on near the coast and the low pressure system offshore
from NC, probably centered to our NE. This will make a bit of a
temperature gradient between our inland and coastal areas, with
temps at the coast near or slightly above 50 degrees. Inland
meanwhile will be in the mid 40s. Through Saturday night, cold
high pressure will build in from the west, and conditions look
ideal for radiational cooling outside of some lingering high
clouds primarily over SC. Lows in the lower to mid 20s, colder
spots dropping into the mid to upper teens. Similar conditions
expected Sunday under high pressure with full sun and increasing
clouds overnight with a shortwave ahead of zonal flow aloft.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
Cold and dry under zonal flow through midweek before a trough
pushes through with a dry cold front. Highs will start out near
50 then drop to being firmly in the 40s, coldest conditions
expected Wednesday and Wednesday night with lows near 20. Some
warming is possible towards the end of the period as high
pressure builds in from the west/southwest.
&&
.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
VFR conditions expected through the 24 hr TAF period with the
exception of the introduction of a PROB30 group for P6SM -FZRA
for late Fri afternoon for FLO and LBT terminals. Clear skies
attm, will give way to increasing upper than mid level cloud
decks later tonight thru daytime Fri. A stratocu/st deck at 4k
to 5k ft to accompany the -FZRA at mentioned terminals. Winds to
drop to 5k or less tonight, mainly from the NW-N. A variable
wind direction likely for much of daylight Fri across all
terminals but will highlight a predominate direction in lieu of
going VRB.
Extended Outlook...MVFR cigs/vsbys early Fri night with IFR
possible during predawn Sat hrs into daylight Sat morning
as a storm system moves through. With possible wintry precip,
mainly Fri eve across LBT and FLO terminals. High pressure and
VFR to dominate Sun thru Tue of next week.
&&
.MARINE...
Through Friday Night...The northwest winds will diminish to
10-15 knots with seas dropping to 2-4 feet tonight. Overall
Friday will see light wind speeds with the direction changing
from north to southeast in time as low pressure moves across
the southeast. This flow will increase through the night into
Saturday possibly leading to a brief headline as seas will rise
in time as well.
Saturday through Tuesday...A low pressure system will likely be
to our NE at the start of the period. Flow will be west to
northwest behind the system gusting +25 kts with seas +6 ft and
SCA conditions likely. Conditions will improve through late
Saturday into Saturday night, high pressure moving overhead by
early next week. seas generally 1-3 ft with light north flow.
West winds will increase Monday into Tuesday as the pressure
gradient tightens ahead of a cold front.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
NC...Winter Weather Advisory from 4 PM Friday to 7 AM EST Saturday
for NCZ087-096-099-105.
SC...Winter Weather Advisory from 4 PM Friday to 7 AM EST Saturday
for SCZ017-023-024-032-033-039-059.
MARINE...Small Craft Advisory from 10 PM Friday to 4 PM EST Saturday
for AMZ250-252-254-256.
&&
$$
SYNOPSIS...ILM
UPDATE...DCH
NEAR TERM...SHK
SHORT TERM...LEW
LONG TERM...LEW
AVIATION...DCH
MARINE...SHK/LEW
Area Forecast Discussion...Updated
National Weather Service Lincoln IL
748 PM CST Thu Jan 9 2025
.KEY MESSAGES...
- A storm system tracking along the Gulf Coast will spread snow
across central Illinois tonight into Friday. Snow accumulations
of 2 to 4 inches will occur southeast of a Macomb to Lacon
line, with lower amounts of 1 to 2 inches to the northwest. The
higher amounts around 4 inches will occur southeast of I-70.
- Below normal temperatures are expected again after the weekend,
for the first half of next week. Daytime highs will be in the
teens, with overnight lows in the single digits. Wind chill
values below zero will be common Monday night and Tuesday night.
&&
.UPDATE...
Issued at 747 PM CST Thu Jan 9 2025
Regional radar mosaics show echoes reaching the Missouri/Illinois
border this hour, but surface reports show the snow is still back
across central Missouri. The evening sounding from our office
shows a lot of dry air above 850 mb, and while HRRR soundings for
Springfield show moistening from the top down overnight, the
900-700 mb layer may not really moisten up until after 3 am.
Further east at Champaign, the layer doesn`t really moisten up
until the 6-9 am time frame Friday morning. Recent updates were
made to adjust the snow chances through the night, delaying the
onset in the western CWA by a few hours and significantly cutting
back on them over the east.
No changes have been made to projected snow amounts. However,
because it appears the I-55 corridor should be out of the snow
well before the midnight expiration time of that segment of the
Winter Weather Advisory, the end time in that area has been
adjusted back to 6 pm.
In addition, low temperatures tonight east of I-55 have been
adjusted downward by a few degrees, but they should begin to rise
by late evening.
Geelhart
&&
.SHORT TERM... (Through Late Friday Night)
Issued at 326 PM CST Thu Jan 9 2025
A sfc low in southeast TX will track east-northeast along the Gulf
coast with an inverted trough extending up into the mid Mississippi
River valley. A low pressure area in northern Canada will track
east as well, with a cold front extending down into the US and
connecting with the inverted trough in the mid Mississippi
valley. These features will combine...along with the 500
trough...to product another winter system that will spread more
snow from the plains and into the eastern US. This track should
have the heaviest snowfall south of IL and south of where the
heaviest snow fell last weekend. Some of the models have increased
the QPF values across the CWA which is resulting in slightly
higher amounts of snowfall across the area. The highest amounts in
our CWA will fall along and southeast of I-70 with 3-4 inches
possible. With the snowfall increasing and spreading to the
northwest, amounts have increased some toward the Illinois river.
This has resulted in an expansion of the Winter Weather Advisory
to include all counties on either side of the Illinois river.
Amounts will be lower, around 2 inches, but with the snow starting
overnight and then spreading to the northeast into the morning
hours, which could impact the morning commute in those area. The
snow will move to the east during the day, Friday, with amounts of
2-3 inches expected, from early morning into the afternoon.
Again, the morning commute could be effected, but also the evening
commute could be effected in some parts. In the southeast, along
I-70 and southeast, the snow should start during the morning hours
and last through the afternoon, and will definitely impact the
evening commute in areas along I-57 and to the east. Locally
higher amounts are possible in the east and southeast, due to
enhanced dynamics that could occur as the front and inverted
trough phase together. The snow will end from west to east, ending
in the west in the early afternoon and in the evening in the
east.
Temps through Fri night will be near normal
Auten
.LONG TERM... (Saturday through Next Thursday)
Issued at 326 PM CST Thu Jan 9 2025
After this system moves through, most of the weekend will be dry,
but there is a clipper system that will slide across the northern
half of IL, spreading light snow across the northeastern third of
the CWA on Sunday. Currently, snowfall amounts are expected to be
very light with amounts of 1/2 inch or less.
The remainder of the extended period will be dry but the main
issue is temps will become very cold again, with high temps in the
teens and twenties for Mon through Wed and overnight lows in the
single digits Mon night and Tue night. A positive note: temps do
look like they will begin to trended warmer toward the end of the
week.
Auten
&&
.AVIATION... (For the 00z TAFs through 00z Friday Evening)
Issued at 517 PM CST Thu Jan 9 2025
While VFR conditions will prevail through about 06Z, aviation
impacts increase between 06-12Z as snow moves northeast into
central Illinois. Ceilings will quickly deteriorate to below 1,000
feet as the snow develops, with visibility dropping to around
1.5SM. However, periods of lower visibility, near 3/4SM, are most
likely from KSPI-KCMI during the morning hours. The snow will
edge eastward during the afternoon as a cold front moves into the
area, with winds shifting to the northwest as early as 18Z around
KPIA. However, ceilings only marginally improve behind the front,
though they should lift to above 1,000 feet at KPIA/KSPI late
afternoon.
Geelhart
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from midnight tonight to 6 PM CST Friday
for ILZ029-031-036>038-040>043-047>053.
Winter Weather Advisory from midnight tonight to midnight CST
Friday night for ILZ044>046-054>057-061>063-066>068-071>073.
&&
$$
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
850 PM CST Thu Jan 9 2025
.KEY MESSAGES...
- Light snow will impact much of the area late tonight into
tomorrow, including during the morning commute. A Special
Weather Statement was issued highlighting expected impacts.
- It`s going to be cold next week, especially the first half of
the week.
&&
.UPDATE...
Issued at 850 PM CST Thu Jan 9 2025
The forecasted system moving in from the southwest looks to be
mostly on track bringing light snow tomorrow morning and lasting
through the afternoon. As the 00Z guidance came in, it appears
the hi-res models are suggesting a slight southward shift to
the system as a whole and slowing down the arrival time. That
adds slightly lower confidence on the exact timing of snowfall
arriving in the city, but with a cold front moving in from the
west right on the heels of the initial system, there was no
overall changes on the expectations for snow totals. Light snow
should gradually taper off from west to east in the afternoon.
A lot of focus tonight was given to the risk for freezing rain
tomorrow morning. Model soundings do have a saturated column up
to around 5000 feet with southerly flow right at the base of the
inversion and temperatures through the column below -12C. The
area that had the best "look" to the soundings were around the
Rockford Metro area with a lack of agreement in model soundings
closer to the lake. The front is currently in west-central Iowa
moving east, and most of the observations are for snow. Given
that there are no upstream obs (currently) for freezing drizzle
and that the window for it looks to be short (before 6AM),
confidence was low enough to hold off on issuing any headlines
for the risk at this time. If it did occur, it would probably
only be a trace of ice, but that could be enough to create slick
spots. A close eye will be kept on obs to the west through the
night in case a quick change to the forecast needs to quickly
be made.
DK
&&
.DISCUSSION...
Issued at 255 PM CST Thu Jan 9 2025
Through Friday Night:
Regional water vapor imagery showcases two features heading our
way. The first is is a cold front working across the northern
Plains. Some light snow showers can be found along the front
across the eastern Dakotas and parts of Minnesota. Light snow
may continue to cling on onto the boundary as it moves into the
Midwest tonight, but as low-mid level profiles remain dry on
either side of the front, it will struggle to produce anything
more than that. The second feature is a ridge laden with Gulf
moisture that`s lifting into the region from the southern
Plains. These two features will phase over the area late tonight
allowing for more widespread snow to develop ahead of the front
into tomorrow.
Water vapor imagery shows that this moisture is advancing a bit
quicker than models have been showing. Recent high-res and
regional camps have picked up on the trend spreading the higher
snow totals a tad farther to the north and west and widespread
snow may kick off a hair earlier. Still, it looks like the more
widespread snow will wait to blossom until closer to the Fox and
Illinois River Valleys leaving the Rockford metro and vicinity
with much lesser accumulations than what`s expected farther
south and east. In fact, model soundings suggest that saturation
may be too shallow near the front for cloud ice prior to that
moisture getting in here. Therefore, it`s possible that in lieu
of light snow, the Rockford metro and surrounding locales may
see a few hour period of freezing drizzle before switching to
snow. A slight chance for freezing drizzle was introduced to
this area in the forecast prior to daybreak.
The widespread snow looks to take off right as the morning
commute does in the predawn hours of tomorrow and continue
into the afternoon. Snow rates should largely be on the lighter
side, but could approach 0.5" per hour at times during the
morning when forcing will be maximized and mid level lapse rates
steepen up beneath the building upper jet. There is fair
agreement on totals with an inch or two expected around much of
the Chicago metro up to the I-90 corridor and closer to 2 to 3"
south of I-80. Probs for anything greater than 3" are low
across our CWA. Areas north and northwest look to end up with a
dusting to several tenth of an inch. A lot of models, even many
of the coarser global camps, have really picked up on the idea
that the gradient in snow totals will be pretty sharp owing to
an awfully tight mid level density gradient along the jet. A
couple tens of miles could possibly mean the difference between
a light coating and an inch or two of accumulation.
As mentioned, the brunt of the snow is expected to fall during
the morning commute tomorrow. Although this will likely slow
things down, expected snow rates and totals weren`t quite there
to warrant issuing a Winter Weather Advisory at this time.
However, an SPS was issued for Dekalb, LaSalle, Livingston, and
all counties east for the expected travel impacts tomorrow.
Anticipate slick roads, reduced visibility, and slower-moving
traffic during the day tomorrow, particularly through the
morning. The snow should taper off to the east during the
afternoon.
Some guidance is producing some lingering spotty snow showers
in the cold advection regime into the evening. Forcing and
saturation will be scarce, but conceptually could support some
light precip. The RAP and HRRR are resolving traces of freezing
drizzle around the area following the snow as dry advection
aloft may eat away at cloud ice. Given the seemingly low
probability, any mention was omitted from the forecast for now.
Any additional snow or freezing drizzle that does materialize
will be very light and shouldn`t contribute any further impacts.
Doom
Saturday through Thursday:
An Alberta Clipper is progged to dig southeast into the upper
Mississippi Valley Saturday night, then turn northeast and track
across the upper Great Lakes Sunday. A track this far north
should keep the chances for more meaningful snow accumulations
well north of our CWA. However, there could be a narrow band of
warm air advection snow (or even brief ice pellets at the onset
as column saturates top down) Sunday. Based on the latest suite
of run, the chances for an inch or more of accumulation are
very low, ranging from around 30% near the WI border down to
<15% I-88/290 corridor and to near zero from the I-80 corridor
and points south. Obviously if this system were to trend farther
south in later runs, then those chances would increase some, but
at this point, this system doesn`t look like a big deal for our
area.
A formidable cold front trailing south of this clipper is
progged to sweep across the area early Monday morning,
delivering a healthy shot of cold air to the region. High temps
Monday could end up being in the morning with steady or even
slowly falling temps (into the teens) in the afternoon. Lows
Monday night and Tuesday look to be in the single digits with
daytime highs Tuesday in the teens. Winds don`t look terribly
strong, but with such cold temps will be enough to knock wind
chills down below zero.
Other than the brief snow chances Sunday, the long term period
looks dry. After a cold first half of the week next week, temps
look to moderate some late next week and moreso next weekend.
- Izzi
&&
.AVIATION /00Z TAFS THROUGH 06Z FRIDAY/...
Issued at 538 PM CST Thu Jan 9 2025
Forecast concerns include...
Several hours of light snow Friday.
Ifr cigs/vis with the snow, possible lifr vis at times.
Possible freezing drizzle across northwest IL and at RFD.
Chance of snow showers Friday evening.
Snow is expected to spread across the entire area during the
predawn hours Friday morning and continue into Friday afternoon,
ending from northwest to southeast. There continues to be good
agreement with the track of the system as well as start times,
which will be around 10z for ORD/MDW. The snow is expected to
continue all morning, slowly decreasing in intensity by early
afternoon and then ending during the mid afternoon. Across
northwest IL and at RFD, the precipitation may begin as a mix of
light freezing drizzle and light snow before changing to all
light snow. Confidence is only medium for this mix as well as
how long it may persist. Continued prevailing mention at RFD but
changes are possible with later forecasts. There is also a
small chance of freezing drizzle Friday afternoon for the
Chicago area terminals as the precipitation ends. Confidence is
low for this potential and no mention with this forecast, but
trends will need to be monitored.
There is also a chance for snow showers or flurries Friday
evening. If actual snow showers materialize, some tempo mention
for lower conditions may be needed.
Cigs/vis will quickly lower through mvfr as the snow begins and
prevailing ifr cigs/vis are expected for several hours, slowly
improving Friday afternoon. While prevailing vis will likely
remain in the 1-2sm range, its possible for vis below 1sm with
periods of moderate snow, especially southeast of the terminals.
Cigs are expected to slowly lift through mvfr Friday afternoon
and likely scatter out Friday evening, though only medium
confidence.
Low level winds will steadily increase this evening and this
will likely lead to periodic gusts into the 15-20kt range for
most locations with directions starting southerly and drifting
to south/southwest through the evening. Gusts should diminish
after midnight with speeds diminishing to 10kts or less by
daybreak. Directions will turn southwest Friday morning,
westerly Friday afternoon and northwest Friday evening. cms
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.
&&
$$
Visit us at weather.gov/chicago
Area Forecast Discussion
National Weather Service Raleigh NC
1010 PM EST Thu Jan 9 2025
.SYNOPSIS...
Arctic high pressure will settle into the lower Middle Atlantic
tonight and Friday. An area of low pressure will track northeast
across the Gulf coast Friday and South Atlantic coast Friday night.
High pressure will build back in Saturday night and Sunday.
&&
.NEAR TERM /THROUGH TONIGHT/
As of 800 PM Thursday...
Under clear skies and a very dry airmass, winds have decoupled at
most locations across the area. In response, temperatures have
plummetted. While temperatures across the northern half of the
forecast area are dropping at a similar pace to last night, across
the southern half temperatures are 3 to 4 degrees colder. Despite an
increase in high clouds/cirrus late, expect another very cold night.
Lows 15 to 20, which is 10 to 15 degrees below normal . Those going
out tonight should dress warm.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
As of 400 PM Thursday...
* Winter Storm Watch upgraded to a Winter Storm Warning/Winter
Weather Advisory, for Friday afternoon through Saturday morning.
Confidence remains high the storm will have potentially significant
impacts for much of central NC. While current totals are slightly
below criteria with this latest forecast issuance, expected impacts
warrant the upgrade to a warning for all but Cumberland, Sampson,
and Wayne counties (which are now under a Winter Weather Advisory).
There is still uncertainty wrt p-types and durations of each in most
locations, which could impact accumulations. There is the potential
for a swath of greater ice accumulation exceeding warning criteria,
however uncertainty remains where exactly that will be.
The overall synoptic pattern remains largely unchanged. Similarly,
there has been little change at the surface with the track of the
low as it moves ewd along the Gulf Coast Fri, then newd through the
Southeast US and off/along the Carolina coast Fri night/early Sat.
However, small track differences remain with the GFS track just
inland of the NC Coast, the EC and NAM just offshore, and the HRRR
and RAP over the NC coast. These seemingly small differences in
track are one of the factors responsible for continued uncertainty
in p-types and locations and duration thereof. The other factor is
the strength of the warm nose aloft, which also varies amongst all
the available guidance.
With cold, dry air in place at the surface and sufficient lift and
saturation in the dendritic growth zone, onset of precip should
largely be snow, even though surface temperatures may be above
freezing (the exception could be the far srn Coastal Plain where it
could be a rain/snow mix). Once snow starts, the low levels will
quickly saturate, with temperatures rapidly decreasing and dewpoints
rising. As the warm nose aloft strengthens and the surface
temperatures drop below 32 degrees, expect sleet and freezing rain
to mix in. Best chance for mostly snow (with maybe a little sleet)
will be along the VA border and far NW Piedmont. Best chance for
limited wintry precip and a changeover to rain through the end of
the event will be over the srn Coastal Plain. In between however,
there will likely be a wintry mix, with some accumulation of snow,
sleet, and freezing rain all possible. Some of the hi-res guidance
shows a narrow band of sleet/fzra with snow to the north and rain
south, however some of the other guidance has a more spatially
expansive area of mixed p-type. As mentioned earlier, there could be
a swath of ice accumulation in the 0.2 to 0.3 inch range, but given
the uncertainty have kept amounts 0.2 inches or lower for now.
Similarly with snow amounts, if the corridor of mixed p-types is
narrower, then there could be higher snowfall totals across the
north where sleet is currently expected to mix in, thus cutting down
on amounts. For now, an estimate of the axis of greatest ice accum
generally extends from Wadesboro to Sanford to Smithfield, which
could still shift with later forecasts. Snowfall totals could range
from around 3 inches along the VA border to 0.5 inches or less in
the SE.
Latest forecast guidance has precipitation quickly exiting the area
between 09Z and 15Z Sat, after which the forecast should remain dry.
Temperatures will depend to some degree on how much accumulation of
wintry precip remains on the ground. With that caveat in mind, for
now expect highs in the upper 30s to mid 40s, lowest north. Lows Sat
night should drop into the upper teens/low 20s.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY...
As of 250 PM Thursday...
The long term forecast is dominated by dry and cool conditions.
Sunday, a deep ridge will build over the region, which should move
offshore on Monday. This will allow temperatures on Sunday to cool
into the low to mid 40, with low temperatures in the low to mid 20s.
Southerly winds as the high moves offshore will moderate Monday`s
temperatures with highs in the mid to upper 40s and lows in the mid
to upper 20s, making Monday the warmest day of the forecast.
Tuesday, a dry cold front associated with a shortwave trough is
expected to reach Central NC, bringing another shot of colder Arctic
air. This should leave high temperatures generally in the mid 30s to
low 40s and lows in the mid teens to low 20s in the middle of next
week.
&&
.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
As of 620 PM Thursday...
TAF period: High confidence that the bulk of the next 24 hours will
be VFR, although it appears likely that INT/GSO will have IFR
conditions by the end of the TAF period. Skies are clear across the
area right now, with high clouds moving in from west to east after
midnight. Northwest wind overnight will back to the southwest by
late Friday morning. A chance of snow will move into the Triad
Thursday afternoon, with snow likely in those locations by sunset
and dropping visibilities to IFR. There will also be a chance of
precipitation (most likely snow) at RDU/FAY in the afternoon, but
less confidence that precipitation will arrive before 00Z.
Confidence is too low to include a mention of precipitation at RWI
before 00Z.
Outlook: Wintry mixed precipitation and LIFR/IFR flight restrictions
are likely Friday evening into Saturday morning. There is high
confidence that all terminals will receive at least some snow, and
that FAY will likely changeover to rain at some point, but there is
low confidence in the evolution of precipitation types through the
night. LLWS is also likely Friday night, primarily . VFR conditions
are likely to return Saturday morning and persist through the rest
of the outlook period.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning from 1 PM Friday to 10 AM EST Saturday for
NCZ007>011-021>028-038>043-073>077-083>086.
Winter Weather Advisory from 1 PM Friday to 10 AM EST Saturday for
NCZ078-088-089.
&&
$$
SYNOPSIS...Kren
NEAR TERM...CBL
SHORT TERM...KC
LONG TERM...Helock
AVIATION...Green
Area Forecast Discussion
National Weather Service Salt Lake City UT
352 PM MST Thu Jan 9 2025
.SYNOPSIS...Gusty winds across southern Utah decrease through
Thursday night. The next storm system is then expected to pass
through the region Friday night into the weekend, bringing potential
for accumulating snow from central Utah northward. Drier and colder
conditions then settle in for early next week.
&&
.SHORT TERM (Through 00z Sunday)...In the wake of the passing and
mostly dry system, gusty conditions continue across much of
southern Utah. This seems to be occurring as a mix of the
anticipated strong gap/canyon winds at areas downwind of favored N
to NE oriented canyons (given the strong surface pressure
gradient), as well as just general synoptic mixing of higher
momentum air down across a broader area. The latter has resulted
in an expansion of the Wind Advisory`s areal extent given the
observed magnitudes. Anticipate the gap winds will persist a bit
longer into the evening across lower Washington County than the
general synoptic gusts elsewhere, so have the Wind Advisory
expiration times set accordingly. While some stronger gusts may
accelerate through a few localized N to NE oriented canyons
overnight, anticipate a general trend downward as the pressure
gradient relaxes.
Moving into Friday, the trough associated with the prior system
will shift south and eastward away from the region, with mid level
ridging flexing in from the west in its place. For much of the
day, dry air associated with the ridge will help keep conditions
dry. Additionally, will see H7 temps warm several degrees through
the day. Model forecast soundings continue to suggest sheltered
lower elevation valley areas may see very little mixing, if not
stay inverted, limiting how much daytime highs actually increase.
Higher terrain will realize some warmer temps though, as will any
valley that successfully mixes out a bit more. With the transient
nature of the ridge, not really anticipating enough time to see
much in the way of haze buildup or associated air quality
concerns.
The next system then pushes in Friday evening onward into the
weekend. By Friday evening, increasing precipitation chances will
coincide with increasing synoptic forcing ahead of a more robust
shortwave and associated cold front. Precipitation chances then
look to be maximized for a period coinciding with (and in the
period after) frontal passage, likely sometime Friday night into
Saturday morning, though some timing differences remain among
various models/ensembles. This will also mark the period of
highest precipitation rates for most locations. Lower elevation
precipitation will generally taper off or decrease in coverage
throughout the day, with mountains seeing more persistent snow,
especially those that do well orographically in stronger west to
northwest flow regimes.
The biggest question with the system continues to appear to be
how much moisture will it carry and what will the exact trajectory
be. Precipitation type on the other hand looks more certain, with
quick intrusion of cold H7 temps ensuring snow levels support
snow areawide (where precipitation occurs, of course). With that,
current forecast does carry roughly 0.5-1.0" snow for lower
elevations, including the Cache Valley and Wasatch Front southward
to around the I-70 corridor or so. Even the 25th percentile
amounts carry some minor low elevation accumulations, with 75th
percentile bringing some places up closer to 2" or so (and of
course more at bench areas). While arguably somewhat meager
amounts, given a relative lack of low elevation snow this season,
those planning on travel should keep an eye on road conditions.
The high terrain from central Utah northward should see a bit more
appreciable totals. 25th percentile amounts generally sit in the
2-6" range for most mountains, with the 75th percentile more
aggressive in the 4-12" range. Better odds favor terrain further
north, as well as terrain orographically favored in that stronger
west to northwesterly flow regime (such as the Upper Cottonwoods).
Another low confidence factor to monitor will be potential for
lake effect/lake enhanced snow showers Saturday, given the
coldness of the airmass settling in.
For this forecast, opted to hold off on issuing any advisories
given the current gridded/deterministic amounts only have a very
small handful of areas which hit local criteria. Further
uncertainty is noted on whether we trend more towards the 25th
percentile (even less areas likely to hit) or the 75th percentile
(easier headline decision). Additionally, the first look at
available high res guidance raises some questions. 18Z HRRR for
example only shows advisory level accumulation in a small handful
of localized mountain areas, while the 18Z high resolution NAM
carries more appreciable amounts. A number of coarser global
ensemble members also show potential for more limited snow
accumulations. Despite this uncertainty and associated lack of
current winter headlines, anyone planning travel to higher
elevations (especially if it coincides with the period of highest
precip rates) should be aware of potential adverse driving
conditions and plan accordingly.
.LONG TERM (After 00Z Sunday/5PM Saturday)...A cold post-frontal
airmass with northerly flow aloft will be in place Saturday
evening with a few lingering showers remaining across the central
and northern mountains. These showers will dwindle as flow aloft
weakens and shortwave ridging builds into the area. With a cold
northerly flow remaining in place, temperatures overnight Saturday
will be quite cold. Additionally, gusty northerly winds will
persist across southern Utah, but likely remain below advisory
criteria.
A secondary shortwave wave will move into northern Utah overnight
Sunday into Monday morning. With some lingering low level
moisture and subfreezing temperatures areawide, any snow that is
able to fall with this shortwave will quickly stick to all
surfaces. This could make for a hazardous morning commute on
Monday morning. Not all guidance is on board with this, however,
with some members bringing more of a northeasterly flow ahead of
cutoff low evolving. This would lead to dry conditions across the
Wasatch Front. This shortwave is still outside of the high-res
window so there will be a better picture of what this might entail
once we get into range of the high-res guidance.
Beyond this shortwave, drier conditions will settle into the area
along with colder than normal air for much of next week. A very
similar pattern looks to evolve next week that we saw with this
past week`s trough that led to a low developing and shifting
southwest which lead to some gusty downsloping winds across the
Wasatch Front. Most guidance is in agreement with a cutoff low
developing off the coast of California that could bring easterly
downsloping winds to northern Utah by Tuesday/Wednesday. The
location of this low pressure will determine how much easterly
flow, if any, develops. Eventually, this low moves back on shore
which could bring more precipitation to the region by the end of
next week.
&&
.AVIATION...KSLC...Winds out of the northwest will persist through
the rest of the afternoon and early evening, becoming lighter
after 02z. Winds may become light and variable after 04z, with
prominent south flow around 5-6kts not prevailing until as late as
12z. VFR conditions will continue.
.REST OF UTAH AND SOUTHWEST WYOMING...Gusty northerly winds are
expected to continue through the afternoon and early evening
across many areas. Across the north, gusts have largely been
20-30kts at most. Southern sites have seen even higher gusts, with
locally high gusts up to 40-50kts downwind of higher terrain,
such as at KSGU, KBCE, and KHVE. These winds will largely decrease
through the evening, though KSGU could see these winds persist as
late as 06- 07z. VFR conditions will prevail, aside from a small
(25%) chance of fog developing near KLGU in the early morning.
&&
.SLC WATCHES/WARNINGS/ADVISORIES...
UT...Wind Advisory until midnight MST tonight for UTZ123.
Wind Advisory until 9 PM MST this evening for UTZ127-128-130-131.
WY...None.
&&
$$
SHORT TERM...Warthen
LONG TERM...Mahan
AVIATION...Cunningham
For more information from NOAA`s National Weather Service visit...
http://weather.gov/saltlakecity