Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/26/24
Area Forecast Discussion
National Weather Service Burlington VT
1030 PM EST Wed Dec 25 2024
.SYNOPSIS...
Surface high pressure will bring several days of quiet weather
to the North Country. Dry air will help produce cold mornings,
but daytime temperatures will trend milder and then above
normal over the weekend. A pattern change to unsettled weather
then will unfold with chances of rain and areas of freezing rain
possible beginning on Sunday.
&&
.NEAR TERM /THROUGH FRIDAY/...
As of 1023 PM EST Wednesday...Valley locations are have dropped
into single digits across the region as the perfect mix of clear
skies, no wind and snow on the ground have seen us blow past of
the original forecasted overnight low temps at 10pm. Have
adjusted overnight lows down a bit, as we have not really seen
the potential freezing fog set up as of yet and that may not
come until closer to sunrise. Beyond that, no significant
changes to the forecast which should put the final bow on this
cold and quiet Christmas Day. Previous discussion follows...
Main thing for the evening update is that NEK is seeing some
much quicker than expected temperature drops as the sun has set,
Newport seeing 5 degrees currently, while areas across the
region outside of NEK are in the teens right now. Have made some
adjustments for temps out there and just some minor tweaks
overall. Right now, still expecting spots of freezing fog as the
inversion sets up,though still not sure how widespread in the
valleys it will be, but we may end up issuing an SPS to cover
potential slippery travel in areas that see freezing fog.
Previous discussion follows...
A stagnant weather pattern will continue with high pressure
anchored to southwestern Quebec through at least tomorrow night.
No precipitation is expected and temperatures will remain below
freezing. Many areas will see nothing but clear skies while
others see bouts of low clouds and fog with persistent undercast
for our area`s mountains. The main forecasting challenge will
continue to be the fine scale evolution of these low clouds and
their impacts on temperature.
Aloft, an upper level wave currently over northwestern Quebec will
move southeastward across our region tonight with no impacts.
However, as it exits, upstream ridging will really build, resulting
in increasing heights and resulting warming trend. This scenario
will produce increasingly inverted temperature profiles with warmer
air aloft. The warmest air is currently centered around 8,000
feet above the surface, and this inversion will lower towards
4,000 feet, enhancing the difference between our high terrain
and the valleys. The mountain summit warming trend is a bit
slower than previously thought, but it will be getting
noticeably milder; current temperatures in the higher terrain in
the upper teens should make it to near freezing by tomorrow
night.
Meanwhile, valleys will have large diurnal ranges with clear skies,
light winds, and a fresh snow pack supporting cold nights with
development of surface inversion such that overnight temperatures
will generally be much colder than in higher terrain. Below zero
lows can be expected in most locations that remain clear, with
daytime heating supporting large recoveries into the mid and upper
20s for most spots. However, it is still unclear unfortunately
as to what areas see stratus and where fog develops.
That being said, there are enough indications of fog to go ahead and
add mention where model guidance suggests reduced visibilities each
of the next two nights. Any freezing fog could have localized
impacts to travel, so use caution especially in the overnight/early
morning hours if traveling. For sky cover, have relied heavily on
NAM3 moisture progs, which were helpful for the evolution of today`s
clouds and preferable to a blend that shows partly cloudy skies at
most. Also noted that the latest HRRR also shows redevelopment of a
lake cloud in the persistent north wind that remains in the along-
lake direction (parallel to the broad waters) of Lake Champlain.
Compared to last night, it appears the cloud layer should be
shallower with lower chance of flurries given reduced lake-induced
instability with 925 millibar temperatures gradually warming, but
with plenty of uncertainty, have a least added mention of flurries
where skies are favored to be cloudy.
&&
.SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY/...
As of 308 PM EST Wednesday...High pressure remains entrenched through
the day on Saturday, bringing a continuation of the quiet wintry
pattern. The sunny weather will continue through Friday, but clouds
on Lake Champlain could develop for a few hours in the morning. A
significant inversion will in place and with weak solar insolation
and snowpack, it will remain strongly in place during the day.
Freezing levels look to generally be in the 7,000-8,000 ft range
except at the surface where temperatures will generally remain below
freezing. On Friday, the inversion looks to keep the coldest high
temperatures in the St. Lawrence and Champlain Valleys where highs
will generally be in the 20s. In the Adirondacks and higher terrain
of Vermont, temperatures will generally be a few degrees higher.
Ideal radiational cooling conditions will exist Friday night so
temperatures should drop into the teens in most places. If this
occurs, temperatures will not be that cold in the atmosphere until
around 15,000 feet. Southerly flow develops on Saturday and mixes
some warmer air down to the surface. Temperatures should rise above
freezing in most places, ending over a week of mostly below freezing
temperatures.
&&
.LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/...
As of 308 PM EST Wednesday...If you are enjoying your White
Christmas/start to Hanukkah, make the most of the next couple days
because rain moves in on Sunday and temperatures mostly stay above
freezing for the first half of the week. High pressure remaining in
place at the onset will create some cold air damming on Sunday,
particularly east of the Greens and parts of the St. Lawrence
Valley. It should be cold enough at the surface that the
precipitation starts as freezing rain there. Light precipitation
rates should limit ice accretions but several hours of freezing rain
are possible. A strengthening low-level jet looks to mix enough warm
air to the surface to send temperatures above freezing everywhere by
Sunday night, but after that, model divergence leads to less
forecast confidence. The deterministic Euro favors a strong low
developing to the west and an associated low-level jet that
scours out all the cold air. This would lead to high
temperatures well into the 40s and 50s. However this is on the
warm end of solutions and is not supported by most of the GEFS
members and around half the Euro ensembles. These members form a
weaker low and begin developing a secondary low south of the
region during the day on Monday and significantly limit the warm
air advection, keeping temperatures in the upper 30s and 40s.
The stronger low/warm solutions could create a potential for
flooding but there is too low confidence for any details.
Temperatures drop back a bit behind this low but generally stay
around and above freezing into Wednesday. A second low makes a
run at the region for Wednesday but most models either bring the
center to the south or develop a quick enough secondary low
where elevation dependent snow is possible. However, with it
being a week out and with many models having it miss the region
completely, it is too early for any definitive details. However,
regardless of the outcome, more substantive cold air looks to
move in behind it and winter should return.
&&
.AVIATION /04Z THURSDAY THROUGH MONDAY/...
Through 00z Friday...Challenging aviation forecast this evening
as high pressure subsidence is expected to produce low ceilings
and/or dense freezing fog as well as very light or calm winds.
Highest chance of visibilities dropping below 3 miles and/or
ceilings falling below 1000 miles above ground level are sites
SLK, MPV, and MSS. SLK has already begun hinting at freezing fog
just head of 00Z Thursday with vis bouncing between 1 and 3
miles. This as well as model solutions are indicative of IFR or
LIFR vis occurring again tonight. Have tempo vis 1-2 mile from
03Z-07Z Thursday, then prevailing 2SM 07Z-13Z Thursday. In
addition to low vis, an overcast layer at 200-400 feet is likely
07Z onward. With a little less confidence for IFR at MPV, have
included a tempo group from 04Z-08Z of 1-2 mile vis and broken
100-300 foot cig. And for MSS, visibilities are also beginning
to sink this evening, but only hovering at about 6-8 miles.
Expecting vis to drop under 3 miles (with accompanying 600-800
foot cig) by about 08Z and potentially last through 14Z. For
MSS, a light northeasterly wind is most likely to provide enough
moisture to reduce vis/cig. Otherwise, MVFR conditions
anticipated for most sites around 06Z-12Z, leaning more towards
MVFR vis than cig as clear skies prevail. If winds turn
northerly or easterly for BTV, we may be under threat for IFR
conditions as well around 08Z-12Z, but not enough confidence to
include in the TAF just yet.
Outlook...
Thursday Night: VFR. NO SIG WX.
Friday: VFR. NO SIG WX.
Friday Night: VFR. NO SIG WX.
Saturday: VFR. Slight chance FZRA.
Saturday Night: Mainly VFR, with local MVFR possible. Chance RA,
Chance FZRA.
Sunday: Mainly IFR, with areas MVFR possible. Likely RA, Chance
FZRA.
Sunday Night: MVFR. Definite RA.
Monday: MVFR. Likely RA.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...None.
NY...None.
&&
$$
SYNOPSIS...Kutikoff
NEAR TERM...Kutikoff/Verasamy
SHORT TERM...Myskowski
LONG TERM...Myskowski
AVIATION...Storm
Area Forecast Discussion
National Weather Service Cheyenne WY
445 PM MST Wed Dec 25 2024
.KEY MESSAGES...
- Scattered snow showers will continue through the evening hours
in the mountains and adjacent valleys.
- The next storm system will bring strong winds and another
round of mountain snowfall will move in Thursday afternoon
into Friday morning.
- Multiple additional rounds of mountain snowfall and strong
winds are likely Friday through Monday.
&&
.SHORT TERM /THROUGH FRIDAY NIGHT/...
Issued at 300 PM MST Wed Dec 25 2024
The first storm system in a lengthy train of shortwaves coming in
from the Pacific during the last week of 2024 is currently
moving across the area. The circulation center of the upper level low
is currently moving along the CO/NM border, with plentiful cloud
cover streaming north ahead of the trough axis. Weak northwest flow
behind the trough axis is producing a few scattered snow showers
mainly along and south of I-80 in Carbon and Albany counties ahead
of a band of 500-mb vorticity lagging the main trough axis. Once
this moves through by around midnight, snow shower activity will
come to an end as dry air in the mid to upper atmosphere and
subsidence takes over. Between now and then, the mountains and parts
of the Laramie/Saratoga valleys (especially further south) may pick
up a dusting to two inches or snow of new snow. Mid to high clouds
will clear out quickly after midnight, allowing for good radiative
cooling tonight. With decent low-level moisture still in place, we
may see some patchy fog developing Thursday morning, particularly in
the Laramie Valley/Shirley Basin, as well as valleys of Carbon
County and possibly into the North Platte River Valley from Douglas
towards Scottsbluff.
Thursday will start off nice, but the influence of the next storm
system will arrive quickly. This shortwave is riding on the nose of
an impressively strong Pacific jet that extends nearly contiguously
from east Asia, and is already pushing cloud cover into the West
Coast states. Expect mid to high level clouds to increase late
Thursday morning through the afternoon as southwest flow aloft
increases. SW to NE oriented pressure/low-level height gradients
will also increase through the day, with the Craig to Casper
gradient peaking mid-afternoon. After a nice Christmas present of a
few days break from the strong winds, this expected to come to an
end for tomorrow. GFS-based in-house guidance indicates fairly high
probabilities of high winds of 60 to 80% in the areas favored by
southwest flow aloft. These zones, including Arlington/Elk Mountain,
Muddy Gap, and Converse County were all upgraded to a High Wind
Warning extended in time until 03z. With model guidance showing the
surface trough just west of I-25, confidence was too low to upgrade
the watch for the Bordeaux area just yet. Lower confidence areas of
the I-25 corridor in Platte County, and the I-80 summit will also
need to be monitored for a possible expansion of the watch/warning,
but the window will be fairly short. For I-25 in Platte County, the
best window will be late Thursday afternoon into the evening along
the surface front pushing through the area, just as the flow aloft
become WSW to due W rather than SW. For the I-80 summit, the best
window will be during the evening and possibly early Friday morning
as the flow turns WNW behind the departing shortwave trough.
This next shortwave will also bring another round of mountain
snowfall. First, another elongated band of 500-mb vorticity
collocated with higher 700 to 300-mb RH will push in around midday
Thursday. Mountain snow will resume with this feature, which should
also produce some isolated to scattered snow showers over the
valleys and western High Plains, possibly producing a dusting to a
half inch or so for some valleys west of the Laramie Range. After a
brief break, snow resumes in the mountains and adjacent valleys
Thursday evening into the early overnight hours. The main trough
axis will pass over our mountain zones around 12z Friday, which
should bring another break in snowfall. This was a tricky event to
determine which type of headline should be in effect for how long,
since additional snow events for the mountains will be right on the
heels of this one. After consideration, decided to issue a Winter
Weather Advisory just for the Sierra Madre range covering 18z
Thursday through 12z Friday, which is the first shortwave trough
discussed above. While the break may only be 6-9 hours, combining
the two events (second event Friday PM into Saturday AM) would lead
to Warning criteria amounts, and the expected snowfall rates and
potential for breaks in snowfall is not likely to lead to Warning-
level impacts. Additional advisories or an extension to the initial
advisory will likely be needed for the following events Friday into
the weekend as much-needed mountain snow accumulation continues.
Expected accumulations in the Snowy range are around 3-6" with the
first event at this time, so decided to hold off on any headlines.
However, the HRRR shows a period of moist NW flow at the tail end of
the system on Friday morning that would push the Snowy Range into
Advisory territory (and produce a dusting to 2" or so for Converse/
Niobrara counties). Confidence in this solution playing out is too
low at this time to expand the Advisory, but later shifts will need
to monitor this potential.
Lastly, yet another shortwave trough will be right on the heels of
Thursday`s event, increasing the winds and mountain snowfall Friday
afternoon. There should be enough of a break to split up headlines,
but a similar round of high winds and mountain snow into Saturday
morning.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
Issued at 300 PM MST Wed Dec 25 2024
Saturday into Sunday, a weak upper level ridge pushes into the
Rocky mountains and gets flattened by a low pressure system
moving through the Canadian provinces condensing the pressure
gradients over the Rocky mountains and into our area. A
prominent jet streak will provide some upper level synoptic
support as small shortwave moves eastward through the basin and
high plains. Model guidance also forms an small trough on the
leeward side of the Laramie Range. This will help tighten the
pressure gradients at the mid-levels and surface to give us
another day of strong winds. The mid levels winds (850-700mb)
start at 56knots and progressively get stronger through the day
reaching about 65-70knots by Saturday night. Looking at pressure
differences at the 850mb levels, the Craig to
Casper/Arlington/Bordeaux reach values between 60 and 80 meters
from 06z on Saturday thru 06z on Sunday. At the 700mb level
these values range from 55 to 74 meters. These tight gradients
give higher confidence to our high wind scenario. Also, the GFS
omega fields also depict strong subsident flow during this time
period these strong winds will likely mix down to the surface
and some headline consideration will likely be made for this
time period. The question will be to include our wind prone
adjacent areas into the headline decisions or not. Precipitation
during this time period looks to be contained to the mountains
since the predominant pattern also keeps the high plains dry
from downsloping off the mountains.
Sunday into Monday, There is a very short window in the evening
where the winds wont be as strong and the pressure gradients relax.
Then by late Sunday night into Monday morning the models show the
pressure gradient tightening again as a small surface low enters our
area producing strong winds once again. However looking at the 850mb
and 700mb pressure differences, the 700mb values drop from 50`s to
the 20`s as the day progresses Monday leaving some uncertainty in
the strength of the wind gusts outside of the wind prone areas.
However, by the early afternoon on Monday our mid level wind flow
changes from a westerly to a Northern flow allowing for the chance
for precipitation across the high plains east of I-25. Looking at
the ensemble members for Monday there a few members that bring some
precipitation past the mountains and into the higher plains although
accumulations may not amount to much given how dry the mid levels
may be and the uncertainty of the strength of forcing during that
time.
Tuesday, pressure gradients look to relax as our shortwave has moved
eastward. The pressure differences at the 850 and 700mb level look
to drop into the 20`s and teens as the day progresses promoting
higher confidence that the winds wont be as strong as the previous
days. Also any type of synoptic forcing looks to degrade over the
day minimalizing any precipitation chances.
&&
.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 445 PM MST Wed Dec 25 2024
Weak Pacific storm system will remain well to our south and push
east into the central Plains. Brief rain/snow showers are possible
for the southern terminals near the Colorado border. Other than a
brief break and clearing skies tonight, another Pacific front will
quickly move east into Wyoming on Thursday, resulting in increasing
clouds and a chance of light snow.
HAZARDS/WEATHER TRENDS: Main forecast concern tonight is the
potential for fog and/or low CIGS, mainly for KLAR and KRWL.
Confidence is limited with HREF and SREF probabilities around 15 to
25 percent. Added VCFG to the KRWL TAF for now, but didn`t mention
anything for KLAR at this time. Confidence appears very low for the
Nebraska terminals as well tonight. For Thursday after 16z, gusty
westerly winds are expected with gusts up to 40 knots possible.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...High Wind Warning from 9 AM to 8 PM MST Thursday for WYZ101.
High Wind Warning from 5 AM to 8 PM MST Thursday for WYZ104.
High Wind Watch from Thursday morning through Thursday evening
for WYZ106.
High Wind Warning from 2 AM to 8 PM MST Thursday for WYZ110.
Winter Weather Advisory from noon Thursday to 5 AM MST Friday
for WYZ112.
NE...None.
&&
$$
SHORT TERM...MN
LONG TERM...MM
AVIATION...TJT
Area Forecast Discussion
National Weather Service Dodge City KS
603 PM CST Wed Dec 25 2024
.KEY MESSAGES...
- Fog and drizzle through the overnight
- Cloudy, cool, fog and drizzle for first half of Thursday
- Mild weekend ahead
&&
.DISCUSSION...
Issued at 222 PM CST Wed Dec 25 2024
Satellite imagery shows a 500 hPa low located over the Four Corners
region this afternoon. Moisture advection downstream of this low
had already been established across southwest Kansas. A cloudy, cool,
and foggy day has resulted with this moisture advection pattern in
place. This pattern will continue through the overnight hours as
the upper level low continues to move closer to the greater region.
The net result is another overnight into the morning period filled
with clouds, drizzle, and fog.
Forecast skew-t/log-p`s from various models from various locations
show that the needed at least 1 km thick saturated layer for drizzle
will likely become established late tonight into the morning. In
addition, there is some forecast wind shear on top of the saturated
layer in the skew-t/log-p`s that is needed for drizzle formation.
The HRRR is quite aggressive with low visibilities for much of the
FA. However, have seen this time and time again with this model too
aggressive with dense fog development, when really the model is forecasting
a stratus layer rather than dense fog. The 3 km NAM was used more
as a basis for a first order approximation of where dense fog could
form this evening. This initial forecast is east of Highway 83. The
swing shift will have to watch how this evolves with short term guidance
to determine if a dense fog advisory is needed. Regardless of how
the fog evolves, the general atmospheric profile suggests more of
an environment for drizzle and less for any appreciable rainfall
amounts. The moisture might just might be shallow enough for drizzle
but not for much more. Will also watch for trends in the short term
guidance before this shift ends to determine if I will issue a dense
fog advisory or not. Some minor good news is that dewpoints and temperatures
should be above freezing, so even if there is fog, overall travel
impacts should be insignificant with the above freezing temperatures
forecast. From a probabilistic messaging perspective, the HREF does
have the highest probabilities of visibilities less than 1/2 mile
from Scott City to Dodge to Hays. Looking forward, all this low level
moisture will be slow to clear Thursday. The net result is cloudy,
cool, foggy, drizzle conditions likely continuing through mid to
late morning.
Looking beyond Thursday, a minor wave with limited moisture moves
across the state Friday. Some very light precipitation and even fog
might be associated with this. The weekend is looking to be mild
with above normal temperatures, light winds, and dry condition likely.
Good weather for taking down holiday decorations.
&&
.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 603 PM CST Wed Dec 25 2024
Widespread LIFR to VLIFR flight category conditions are expected
to develop heading into the early overnight hours, and though
the post sunrise timeframe early Thursday. A cool moist upslope
regime with enhanced large scale lift due to a transient wave
aloft just to our south over the Panhandles will promote the
drizzle and fog setup, driving visibility to one half to one
quarter mile at any of the terminals after midnight as well as
low ceilings less than 500 ft. Once these conditions set in, the
improvement isnt anticipated to begin until at least 16z.
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
Dense Fog Advisory from 11 PM CST /10 PM MST/ this evening to
noon CST /11 AM MST/ Thursday for KSZ030-031-043>046-061>066-
074>081-084>090.
&&
$$
DISCUSSION...Sugden
AVIATION...Russell
Area Forecast Discussion
National Weather Service Grand Forks ND
952 PM CST Wed Dec 25 2024
.KEY MESSAGES...
-Slight chance for freezing drizzle along and north of Highway
200 late this evening through sunrise Thursday.
-Patchy dense fog Thursday morning for the Red River Valley
into northwestern and west central Minnesota
-Light rain with a little wintry mix will impact the area
Friday night through Saturday.
&&
.UPDATE...
Issued at 950 PM CST Wed Dec 25 2024
Saturation is looking less and less of a concern, so the
probability for freezing drizzle in the near term is
diminishing. Having said that, there remains a signal,
particularly in northwest Minnesota, for freezing drizzle to
develop after midnight. At this point however, the probability
for more freezing fog rather than freezing drizzle is increasing
thanks to drier above 1km air.
UPDATE Issued at 636 PM CST Wed Dec 25 2024
No changes to this update. Drifting snow continues this evening
but this will come to an end as winds continue to diminish.
There remains the slight chance for freezing drizzle through the
overnight hours, although observations and reports have not
arisen yet this evening.
&&
.DISCUSSION...
Issued at 300 PM CST Wed Dec 25 2024
...Synopsis...
Zonal to near southwesterly flow continues through the next several
days for the northern plains. Weak wave moves through central
Manitoba bringing slight synoptic forcing to portions of the
northern forecast area late this evening into Thursday morning.
Soundings show saturation in the lowest levels, with dry air aloft
and lacking ice crystals. This brings the slight chance for freezing
drizzle late this evening and into the early portions of tomorrow. A
stronger wave moves through the flow Friday into Saturday bringing
precipitation to portions of the area. Temperatures will be above
freezing and well above normal for this time of year. So
precipitation will most likely fall as rain and transition over to
snow as the colder air wraps back around Saturday night. Ensembles
have started to show a shift in temperatures and the pattern aloft
early in the New Year as a Hudson Bay low starts to form bringing
much cooler temperatures toward the Dakotas and Minnesota.
...Freezing Drizzle Chances...
Current satellite has a large area of stratus over eastern North
dAkota and into portions of northwestern and west central Minnesota.
This patchy dense fog will continue through the remainder of the
day. Areas where winds have increased out of the south (Red River
Valley) have seen decreased chances of dense fog, but increased blow
ice chances. Fallen snow from this morning and in the past several
days has started to drift and blow in isolated areas. It has the
chance to refreeze quickly on surfaces creating slick travel
conditions. Areas in open country have seen blowing snow as well
reducing visibility by a couple miles. If traveling watch out for
slick travel and slight reductions to visibility.
A weak upper level wave shifts through central Manitoba and into
Ontario this evening and overnight bringing weak synoptic forcing to
the forecast area. Underneath this area of forcing we have a deep
layer of saturation near the surface (around a KM deep) with dry air
aloft from the west. This is indicated in numerous soundings for
areas along and north of Highway 200. Lacking ice crystals aloft
from the dry air and low level saturation bring the slight chance for
freezing drizzle to areas along and north of Highway 200. This is
dependent on the weak forcing and how deep the lower layer
saturation is. Any area that experiences freezing drizzle would see
impacts due to slick conditions. The areas that have the best chance
are along the International Border where forcing is more likely. We
will continue to monitor the slight chance for freezing drizzle this
evening and overnight.
...Patchy Dense Fog...
As the nights prior have seen, patch dense fog continues to be a
theme for each morning. Lower level saturation and areas with little
to no wind and lacking clouds develop fog. HRRR and some CAMS
indicate the best area to see patchy dense fog will be in the Red
River Valley and into northwestern and west central Minnesota after
6z and through 18z tomorrow. Rime ice/hoar frost are possible due to
the sub freezing temperatures overnight. There are further chances
for patchy fog on Friday morning as we hold onto the lower level
saturation across the region and the lighter winds, however
temperatures will be at or above freezing limiting the frost.
...Precipitation Friday into Saturday...
Friday afternoon, a wave propagates from the Texas/Oklahoma
panhandle region through Wisconsin and Ontario. As it does so, warm
air advection ahead of it will lead to widespread precipitation
across the Upper Midwest. Temperatures aloft are well above freezing
not just to our south, but also over our FA. This will result in
rain as the predominate precipitation type Friday night into
Saturday morning. Cooler air wraps around the backside of the system
during the day Saturday, which should change rain over to a brief
wintry mix. Most guidance keeps the best synoptic forcing and thus
highest QPF totals east of this FA. Therefore, light QPF totals
are expected, highest east of the Red River Valley.
Behind this wave, flow turns northwesterly to start the new work
week. Ensembles are very consistent in bringing a shortwave down out
of the Northern Rockies through the Northern Plains, but keep it
southwest of the FA. Behind the wave, cold air works down from
Canada, dropping temperatures back closer to seasonal averages.
&&
.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 518 PM CST Wed Dec 25 2024
IFR ceilings will continue for a majority of the TAF period.
As winds diminish this evening, blowing snow will become less of
an issue for visibility. However, this is likely to be replaced
by freezing drizzle for DVL/GFK/TVF overnight tonight. This
potentially will push eastward towards BJI, but for now
confidence is low in how far east this gets. FZDZ will end after
14z at the latest for all TAF sites. As we progress through the
morning and afternoon, the only aviation impact will be the
ongoing IFR ceilings.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.
&&
$$
UPDATE...Perroux
DISCUSSION...Rafferty/Spender
AVIATION...Perroux
Area Forecast Discussion
National Weather Service Hastings NE
539 PM CST Wed Dec 25 2024
.KEY MESSAGES...
- Another round of fog and freezing fog is expected to thicken
up across the area this evening (assuming it ever went away at
your location today!).
- Light drizzle will be possible overnight tonight into the
daytime hours Thursday. Some of the initial bouts of drizzle
may freeze on contact and cause a thin glaze of ice by early
Thursday morning.
- Fog will likely again be an issue Thursday night into Friday
morning, with a bit of light rain possible (20-30%) across the
entire forecast area during the daytime hours Friday.
Accumulations will be minimal (0.01-0.05").
- The weak disturbance that crosses the area Friday will
hopefully be enough to help scour out the low clouds and fog,
allowing for a partly to mostly sunny...and warmer (50s)...
weekend.
- A small chance for precip returns Monday with a colder system
that has about a 20-30% chance of bringing up to an inch of
snowfall accumulation across areas primarily near and north
of I-80.
&&
.UPDATE...
Issued at 503 PM CST Wed Dec 25 2024
With the lowering visibility and continuation of the fog this
evening, the issuance time for the Dense Fog Advisory has been
moved up to 5:00PM.
&&
.DISCUSSION...
Issued at 309 PM CST Wed Dec 25 2024
Another cloudy and foggy day across much of the local area.
Temperatures have struggled to climb above freezing in spots,
especially across areas where the fog has held strong. While
visibilities have improved across the majority of the region
this afternoon, and the dense fog advisory was allowed to expire
at 2 PM, there remain some pockets of thicker fog that could
continue to cause travel difficulties.
For tonight, expect fog to quickly thicken up again after
sunset, and have the next dense fog advisory going into effect
at 5 PM across the local area, although this may be an hour
late for the central part of the area if conditions never really
improve. The 18Z run of the HRRR then keeps dense fog across
much of the local are through midday Thursday, which judging
from the past couple of days may not be long enough. The main
difference for tomorrow is there should also be some light
drizzle to start the day associated with the upper level low
tracking across northwestern New Mexico this afternoon. While
this system should pass well south of the region Thursday, moist
southerly flow and weak ascent ahead of the front should result
in the formation of some drizzle across the area.
Initially, there is a concern for some light freezing drizzle
overnight tonight, which if realized could result in some slick
surfaces to start the day Thursday. While surface temperatures
will likely be very close to or slightly below freezing at times
overnight, they should rise above freezing during the early
morning hours...ending the threat for additional freezing
drizzle - with dense fog then likely being the bigger disrupter
during the morning hours tomorrow. Due the overall low
confidence that much, if any, freezing drizzle will be realized,
opted to forgo a winter weather advisory and include the
potential for slick surfaces once again in the dense fog
advisory and HWO.
One final night of dense fog (hopefully) is then anticipated to
impact the local area Thursday night into Friday morning, with
the next upper level disturbance bringing a chance for some
light rain mainly during the daytime hours Friday. While the
rain will not amount to much (a couple of hundredths is all),
hopefully this system will help to scour out some of the
persistent low level moisture that has been responsible for the
fog the past few days. As a result, we are anticipating a warmer
weekend with mostly sunny skies as a weak ridge of high
pressure crosses the local area.
This upper level ridge will be followed by a quick passing
disturbance in northwest flow next Monday. While moisture will
be limited, model ensembles are indicating there could be a bit
of light snow with this system, with about a 20-30 percent
chance for up to an inch of snowfall primarily north of
interstate 80. Still quite a bit of uncertainty here, but with
the trajectory of the system in northwest flow, this system will
likely not surprise to the upside, but rather mark the
transition from a warmer weekend to a cooler and occasionally
unsettled period thereafter.
&&
.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 534 PM CST Wed Dec 25 2024
For KGRI/KEAR Airports:
IFR to LIFR conditions are expected for both terminals through
late Thursday morning. Dense freezing fog is expected overnight,
in combination with low ceilings. The freezing fog and
possibility of some drizzle may leave a light glaze of ice on
untreated surfaces. Visibilities and ceilings are expected to
improve tomorrow afternoon, with another chance for fog and low
ceilings expected Thursday evening.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...Dense Fog Advisory until noon CST Thursday for NEZ039>041-
046>049-060>064-072>077-082>087.
KS...Dense Fog Advisory until noon CST Thursday for KSZ005>007-
017>019.
&&
$$
UPDATE...Stump
DISCUSSION...Rossi
AVIATION...Wekesser
Area Forecast Discussion
National Weather Service Green Bay WI
616 PM CST Wed Dec 25 2024
Updated aviation portion for 00Z TAF issuance
.KEY MESSAGES...
- The risk for patchy freezing drizzle will spread from south to
north overnight tonight through Thursday with a light glazing
possible on untreated surfaces, making for slick travel in some
areas. Chances are highest across central Wisconsin.
- Widespread clouds, periods of showers, and fog are expected
Thursday through the weekend with locally dense fog possible at
times, with visibility reduced to 1/4 mile or less.
- Above normal temperatures are expected to continue through the
end of the year with colder temperatures returning during the
first week of January.
&&
.DISCUSSION...
Issued at 230 PM CST Wed Dec 25 2024
Tonight-Thursday night:
As surface high pressure departs eastward, an unseasonably warm,
moist airmass will begin to lift northward. There continues to be a
signal for drizzle late tonight through Thursday as persistent low-
level warm/moist advection results in increasing moisture depth and
widespread low clouds redeveloping. RAP soundings show the low-
level saturated layer increasing above 1 km overnight across
central/east-central WI and into north-central WI on Thursday,
which tends to be the entry level depth for drizzle production,
assuming sufficient lift. The HREF shows the highest probabilities
(40-70%) for a light glazing of ice west of the Fox Valley
through Thursday, spreading north with time from central/east
central WI overnight into Thursday morning. Ultimately, though,
freezing drizzle potential will depend on both the moisture depth
and degree of lift through the saturated layer and these trends
will need to be watched, as any light icing could make untreated
roads slick. A quicker arrival of sufficiently deep moisture would
increase chances for freezing drizzle while chances would lower
if moisture remains shallower ahead of the arrival of the warm
air. As warmer air lifts north, a gradual transition to mainly
drizzle/light rain is expected from the south Thursday with
cooler sub-freezing dew points points and light icing potential
persisting across northern Wisconsin during the afternoon into
Thursday night. Along with any drizzle, the warm air overspreading
the colder ground may lead to locally dense fog at times as well.
Although a Winter Weather Advisory for freezing drizzle may be
needed for some areas late tonight or Thursday as confidence
grows, especially central into northern Wisconsin, for now
collaborating with neighboring offices to issue a special weather
statement to highlight the risk.
Friday-Wednesday:
Confidence remains high for well above average temps this weekend
with gradual cooling through the first half of next week as mid-
level troughing overspreads the central US.
Widespread clouds, periods of showers, and areas of fog are expected
late this week into the weekend with deep southerly flow and
precipitable water values exceeding 0.75" for some, above the 99th
percentile relative to climo. Overall, rain amounts look to be in
the 0.25-0.50" range for most locations, with about 30-50% chances
of greater than 0.50" by Sunday. The highest rain chances (70-90%)
remain focused on Friday into Friday night as a stronger shortwave
trough swings northeastward
By early next week, another Pacific shortwave trough is forecast to
eject from the central Rockies eastward towards the Mid-Mississippi
Valley. At this time, the higher precip chances look to be south of
the area with global ensembles painting 20-40% probabilities, lowest
northward.
&&
.AVIATION...for 00Z TAF Issuance
Issued at 615 PM CST Wed Dec 25 2024
An IFR stratus deck is expected to expand from central to
northern Wisconsin for the TAF period, bringing low ceilings to
the region. Over the Fox Valley and lakeshore, another deck of low
IFR stratus is expected to arrive from the south, filling in the
skies that have been largely clear for GRB and ATW today. Some
patchy ground fog may be around before the stratus arrives, but
will likely minimally impact air traffic as the fog will be quite
shallow. Once the clouds fill in, drizzle and another round of fog
are likely by the late overnight period, possibly bringing a
window freezing drizzle to portions of central Wisconsin. The fog
and low ceilings are then expected to stick around through much
of the day Thursday.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
DISCUSSION.....JM
AVIATION.......Uhlmann
Area Forecast Discussion...Updated Aviation
National Weather Service Lincoln IL
548 PM CST Wed Dec 25 2024
.KEY MESSAGES...
- Dreary conditions with light rain or drizzle, fog, and overcast
skies will continue through tonight across central Illinois.
- High temps mainly in the 50s along with daily chances for rain
are expected Thursday through Monday.
&&
.DISCUSSION...
Issued at 135 PM CST Wed Dec 25 2024
DREAMING OF A DREARY CHRISTMAS...
This afternoon, a loosely defined area of low pressure is
centered over eastern Texas with a stationary front extending
northeast across the mid Mississippi Valley into portions of
central Illinois. Isentropic ascent atop this boundary most
notably along the 280-290K surfaces will persist the rest of today
and tonight driving some light rain or drizzle. RAP moisture
profiles show deep layer moisture cutting off north of a SPI to
CMI line demarcating the more drizzly conditions from where
slightly higher precip amounts are expected. HREF 24-hr mean QPF
through 6am Thursday morning shows less than 0.05 inches north of
the SPI-CMI line while south, amounts increase up to around 0.30
inches (south of I-70).
MILD AND WET THURSDAY THROUGH THE WEEKEND...
Shortwave ridging will move across central Illinois Thursday with
notable drying aloft above 700mb. Despite the upper level
subsidence over the region, low level isentropic ascent and
saturated conditions will continue allowing drizzly conditions to
continue. This lull in the forcing will be short lived, however,
as a series of shortwaves are progged to lift from the southern
Great Plains across the Midwest late Thursday through the weekend.
The first wave is poised to lift across Illinois late Thursday
night into Friday bringing another bout of widespread showers to
central Illinois. LREF mean QPF during this time ranges from
around a quarter inch north to half an inch south across central
Illinois. Another shortwave will follow late Friday into Saturday
morning supporting additional showers while yet another shortwave
will move across the lower/mid Mississippi Valley Saturday night
into Sunday. This last wave has trended further south and is also
slower which will help mitigate the previous forecast concerns for
possible severe weather (low CAPE, high shear setup) with
instability now shunted much further south. Meanwhile, mid level
south to southwest flow will prevail during this timeframe
resulting in above normal temps. Highs will generally run in the
50s each day with a few spots possibly tagging 60 degrees
Saturday.
PATTERN CHANGE NEXT WEEK...
While the wet and warm conditions will be in place to start the
upcoming week, upper level longwave trough is expected to flatten
out and shift to our east with an attendant surface low lifting
across the Ohio Valley late Monday into Tuesday. Behind this wave,
northwest flow will overspread central Illinois driving temps
back down closer to the seasonal norms by midweek, while at the
surface, ridging will build southeast from the northern Great
Plains setting the stage for at least a couple days of dry weather
around the middle of next week.
Deubelbeiss
&&
.AVIATION... (For the 00z TAFs through 00z Thursday Evening)
Issued at 526 PM CST Wed Dec 25 2024
A weak stationary front will remain draped over central Illinois
through Thursday afternoon before exiting northward. The net
effect will be poor flying conditions with periods of low stratus
and drizzle moving through each of the terminals throughout this
TAF period. Have maintained optimism at KSPI/KDEC and soon to be
KCMI where visibility is anticipated to firmly improve as surface
winds become more S/SE tonight. Despite this, ceilings at these
sites will remain on the cusp of LIFR/IFR through late Thursday
morning. Meanwhile, at KBMI and KPIA, am anticipating the poorest
conditions with visibility perhaps falling to one-half mile or
less at times tonight while ceilings remain LIFR into Thursday.
MJA
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Area Forecast Discussion...UPDATED
National Weather Service Morristown TN
1036 PM EST Wed Dec 25 2024
...New UPDATE...
.UPDATE...
Issued at 1020 PM EST Wed Dec 25 2024
Forecast is tracking along just fine at the moment, so no notable
changes for the evening update. Regional radar imagery does show
some returns making their way northeast across the northern part
of Alabama late this evening. The latest few runs of the HRRR
suggest perhaps an isolated spit of rain or two will make it into
our CWA tonight, but the bulk of the forcing is going to be far to
our west and what`s on radar the last few hours has not produced
much rain at observational sites, so chose to keep the forecast
dry.
&&
.SHORT TERM...
(This evening through Thursday)
Issued at 242 PM EST Wed Dec 25 2024
Key Messages:
1. Unseasonably mild conditions will continue through Thursday.
High temperatures will be around 10 degrees above normal.
Discussion:
A weak short-wave will across the region overnight and Thursday
morning but upper and surface ridging over the area will remain
in control. Besides increasing mid-level cloudiness this evening
and overnight, no precipitation is expected.
The clouds will help keep temperatures several degrees milder
tonight.
For Thursday, the weak wave will move east allowing sunshine to
return with another unseasonably mild day in store for the
Tennessee valley and southern Appalachians.
Surface ridging will keep winds light through the forecast period.
&&
.LONG TERM...
(Thursday night through next Wednesday)
Issued at 242 PM EST Wed Dec 25 2024
Key Messages:
1. Warmer than normal temperatures will persist through the weekend
and into early next week.
2. Increasing chances for rain showers Friday into the weekend.
3. Gusty mountain wave enhanced winds for the usual higher
elevations and foothills at times Thursday night through Saturday
night or early Sunday. Right now the strongest winds look likely to
occur Sat night, but the details are still uncertain.
Discussion:
We start the period Thursday night with upper ridging over the
eastern CONUS and a trough to our west. A shortwave trough moving
up the western periphery of the eastern ridge will lift by to our
west and into the Great Lakes Region Friday into Friday night with
another weaker wave on its heels, and then another more significant
short wave trough will push east and across our region later
Saturday night/Sunday with a weak cold front pushing through as well
on Sunday. The low level jet will increase out of the south Thursday
night and will continue over the area with varying strength through
Saturday night/early Sunday, bringing considerable moisture to our
area. Precipitable water values will be above the 90th percentile
for this time of year for much of Friday afternoon through early
Sunday as values will be above 1 inch across much of the area during
that time. We will see some showers at times Friday into Saturday
as the first couple of short waves brush by to our west, but the
more significant forcing will come Saturday night into early Sunday
as the stronger wave and front approach and we come under the right
entrance region of a strong upper jet. It will be warm and wet
overall during this period, and ensemble data shows some very weak
instability at times so a few rumbles of thunder cannot be ruled out
as well especially Sat night. With the plentiful moisture
available, some localized flooding will be possible although at this
time it does not look like a widespread threat. Right now QPF values
for the entire Friday through Sunday night time period are generally
around one and a half to two and a half inches.
In addition to the rain, the southerly low level jet will bring
gusty mountain wave enhanced winds to some of the higher elevations
and foothills at times late Thursday night through Saturday night or
early Sunday. The details are still uncertain, but right now it
looks like the strongest winds will be Saturday night as the low
level jet peaks in intensity. Later shifts may need to issue wind
advisories especially for Sat night but perhaps for during some
earlier periods earlier as well if the surges in the low level jet
are significant enough.
No strong cooling behind Sunday`s front but there will be some
drying, and Monday should be rain free with a continuation of above
normal temperatures. Late in the period another system is expected
to approach although models are still struggling with the details.
This system is forecast to bring additional showers by the
Tuesday/Wednesday time frame.
&&
.AVIATION...
(00Z TAFS)
Issued at 632 PM EST Wed Dec 25 2024
VFR conditions will prevail through the period, with only light
winds and some SCT-BKN mid/high clouds to contend with.
&&
.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN 58 39 58 45 / 0 0 0 10
Knoxville McGhee Tyson Airport, TN 58 36 58 39 / 0 0 0 0
Oak Ridge, TN 57 37 57 38 / 0 0 0 0
Tri Cities Airport, TN 57 32 57 36 / 0 0 0 0
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...NONE.
VA...NONE.
&&
$$
SHORT TERM...CD
AVIATION...CD
Area Forecast Discussion
National Weather Service Norman OK
530 PM CST Wed Dec 25 2024
...New AVIATION...
.KEY MESSAGES...
Updated at 527 PM CST Wed Dec 25 2024
- Patchy dense fog and drizzle possible this evening/overnight.
- Heavy rain and strong to perhaps severe storms Thursday
afternoon (southern Oklahoma).
- A warming trend is expected into the weekend.
&&
.NEAR TERM...
(Rest of today and tonight)
Issued at 222 PM CST Wed Dec 25 2024
The persistent low cloud cover will remain through the overnight
hours. Although the depth of the cloud layer may not change much,
the thermal profile may, such that very light showers or drizzle
will form. Visibility is expected to lower tonight/overnight, but
unsure about the potential for dense fog again. Perhaps parts of
northern and central Oklahoma have the best opportunity.
&&
.SHORT TERM...
(Thursday through Friday night)
Issued at 222 PM CST Wed Dec 25 2024
A mid-level trough will move across far southern Oklahoma and
northern Texas Thursday into Thursday evening. Lift associated
with this system will result in an increase in rain/showers across
parts of western Oklahoma and western north Texas early Thursday
morning. The precipitation is expected to expand in coverage by late
morning/early afternoon across southern Oklahoma. Although on the
weak side, elevated instability is expected to result in convective
elements with an increase in precipitation rates and perhaps wind
gusts (south central and southeastern Oklahoma). At this time, it
appears there will be a better push on a weak frontal boundary
across parts of central and northern Texas. This should result in
a better opportunity for strong to severe storms mainly south of
our area. The HRRR has a convective system pushing east of the
area by mid afternoon with additional showers/storms developing
across far southern Oklahoma under the colder part of the trough.
It appears heavy rainfall (1 to 2 inches) is possible across
south central/southeast Oklahoma with a low end chance of
wind/hail.
Although the airmass will be modified some, this system will not
ushering in much drier air. Light winds are expected overnight
Thursday, so fog will be possible again Thursday overnight into
Friday morning. Another trough is expected to move across the
central/southern Plains on Friday. Will maintain low PoPs with
this feature. The flow will remain cyclonic across the central
U.S. until another wave pushes across the area on Saturday. After
this trough passes, temperatures are expected to warm well above
average for late December.
&&
.LONG TERM...
(Saturday through next Tuesday)
Issued at 222 PM CST Wed Dec 25 2024
No changes to the extended forecast
Issued at 304 AM CST Wed Dec 25 2024
The main message on the sensible weather front looks to escalating
temperatures into the weekend and early next week. Another embedded
upper wave looks to pass the area on Saturday, though with continued
dry flow behind multiple surface frontal passages, nil precipitation
chance is currently advertised. Otherwise, afternoon temperatures
look poised to warm towards unseasonably warm readings (widespread
60s to low/mid-70s south) amidst advection of warmed/downsloped
airmasses.
Ungar
&&
.AVIATION...
(00Z TAFS)
Issued at 527 PM CST Wed Dec 25 2024
Low ceilings, fog, and occasional drizzle will continue through
the overnight period into the day on Thursday, with most locations
seeing LIFR ceilings through at least mid afternoon tomorrow
before potentially improving to IFR (though confidence on this is
not super high). Rain showers will increase across western north
Texas into southern Oklahoma by late morning into the afternoon.
Chances for thunderstorms were too low to include in the TAF at
this time, but a low chance (~20%) exists for thunderstorms to
impact KSPS or KDUA.
&&
.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK 44 53 42 57 / 0 60 0 0
Hobart OK 43 53 42 58 / 10 60 0 0
Wichita Falls TX 46 57 44 65 / 10 70 0 0
Gage OK 39 51 37 54 / 20 40 0 20
Ponca City OK 42 54 39 55 / 10 30 10 10
Durant OK 50 58 46 62 / 10 90 10 0
&&
.OUN WATCHES/WARNINGS/ADVISORIES...
OK...None.
TX...None.
&&
$$
NEAR TERM...06
SHORT TERM...06
LONG TERM....06
AVIATION...08