Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/02/23
AREA FORECAST DISCUSSION
National Weather Service Bismarck ND
934 PM CST Sun Jan 1 2023
.UPDATE...
Issued at 922 PM CST Sun Jan 1 2023
03Z satellite and surface observations show a variety of ceiling
heights and visibilities with low stratus in the east, stratus at
7k feet in the northwest, and patchy fog developing in the south
central. The coverage of fog tonight is still uncertain, forecast
soundings don`t really saturate in the lower levels and visibility
guidance from the HRRR has backed off on the fog potential.
Current forecast includes patchy fog for the forecast area, which
seems fair with the current observations and potential. No changes
needed with this update.
UPDATE Issued at 528 PM CST Sun Jan 1 2023
Fog and stratus remain the forecast concern tonight. High-res
visibility guidance produces fog that transitions from west to
east as a surface high slides across the state tonight. With the
center of the high in transition, how long dense fog persists is
uncertain tonight. Will continue the fog potential inherited by
the day shift and will adjust as fog develops later this evening.
&&
.SHORT TERM...(This Evening through Monday)
Issued at 159 PM CST Sun Jan 1 2023
Low level stratus, along with patchy fog, persists from, along, and
east of northwestern ND through the James River Valley. That
said, it has shown rapid areal decline over the past few hours and
may continue to decrease through the remainder of the afternoon
before possibly filling back in this evening. A mid level stratus
deck in northeastern Montana may also encroach into the forecast
area later this afternoon and evening. Finally, a thin and very
translucent layer of high clouds off a west CONUS trough continues
infiltrating the CWA, especially the southern half. More
organized cloud cover should move into the southern half of the
forecast area later tonight and Monday.
One question for this evening into Monday morning is fog
potential. Guidance suggests patchy fog should develop again this
evening, especially in the south central, as winds become light
and variable. Besides fog potential, expect mostly dry
conditions, light winds, and partly to mostly cloudy skies through
the period. Temperatures remain seasonable for this time of the
year with lows tonight and Monday night dropping mostly into the
single digits above zero, while highs Monday should reach the mid
teens to mid 20s.
.LONG TERM...(Tuesday through Sunday)
Issued at 159 PM CST Sun Jan 1 2023
The extended period looks to be quiet with little going on
overall. For the most part, seasonable highs will range from the
teens to mid 20s, with the warmest area consistently being the
southwest. Lows will be mostly in the single digits above zero.
There are hints that the area may begin seeing a warming trend
late in the week and into the weekend. However, as a result of
fairly progressive and weak flow aloft, uncertainty remains. This
uncertainty is illustrated by the latest NBM ensemble guidance
which suggests a continued large 25th to 75th percentile range in
high temperatures Saturday and Sunday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday Evening)
Issued at 528 PM CST Sun Jan 1 2023
Fog looks likely to develop tonight and and Monday morning, likely
from west to east following the progress of a surface high. How
long dense fog may persist is very questionable with how this
surface high will move across the state overnight. An expansion of
MVFR/IFR stratus, possibly LIFR at times, is also possible,
however the coverage and timing of this is uncertain. Overall,
ceiling and visibility impacts can be expected at times through
Monday morning for most areas of western and central North Dakota.
VFR conditions expected after 15Z in the west and 18Z in the
central.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...AE
SHORT TERM...Telken
LONG TERM...Telken
AVIATION...AE
Area Forecast Discussion
National Weather Service Denver/Boulder CO
758 PM MST Sun Jan 1 2023
.UPDATE...
Issued at 758 PM MST Sun Jan 1 2023
No big changes so far from the latest 00Z models that have come
in. The more northerly track still looking to be the correct
solution. However, the details for tonight are still unclear.
General model consensus is that a wave ahead of the main system
will bring a brief period of snow tonight. Most models still show
this, but the location and timing are slightly off. The 00Z HRRR
shows a very weak version of this wave. To add to the uncertainty
with the models is that the HiRes models are already missing the
area of precipitation from Pueblo to Colorado Springs to Akron, so
tough to buy them the rest of the night.
Fine tuned weather type for tonight and Monday. Will stick with
the idea the wave will move north across the area and bring a
period of snow. After this, the mid levels dry, but lower levels
are left saturated. Expect a decent period of freezing drizzle
once the snow passes across the Front Range and eastern plains
late tonight and Monday morning. Don`t expect the snow to return
until Monday afternoon when the low is northeast of the area and
wrap snow makes it into the area. Snowfall amount forecast of
trace to 4 inches looks on track for the Front Range and eastern
plains. Could see a little more over the northeast corner of the
state. Will add a little more ice accumulation due to the extended
period of freezing drizzle. Up to tenth inch seems possible, not
a lot, but plenty to make the roads very slick. Because this, will
keep the Winter Weather Advisory in effect even though snowfall
will likely fall short of criteria. Also increased the coverage
and duration of the fog. Already seeing a good amount of fog and
it should continue through at least Monday morning.
For the mountains, orographic lift combined with the moist
southwest to west flow will bring periods of snow tonight. Then on
Monday, lift from the upper level system will bring additional
snow.
&&
.SHORT TERM...(This evening through Monday)
Issued at 148 PM MST Sun Jan 1 2023
Middle and high cloudiness continue to stream northeastward
across the CWA at this time. Snow over the mountains has decreased
with just scattered showers remaining now and for the rest this
afternoon. Currently, winds across the plains are weak
northeasterly to southeasterly. They are southwesterly over the
high mountains.
The 12Z model runs moved the upper circulation center further north
on its path across Colorado on Monday. It is also a bit slower. At
03Z Monday evening, the center is now over the northeastern corner
of Colorado. Storm total snowfall progs for this storm continue to
decrease on the latest model runs. Left current highlights going
all the same. Was also hard pressed to just drop the Watch over the
eastern plains, so went with an Advisory for those areas as there
will be some snow along with the chance of freezing precipitation.
The freezing precipitation could make very slippery driving
conditons. For temperatures, Monday`s highs are a bit cooler than
current readings are now.
.LONG TERM...(Monday night through Sunday)
Issued at 148 PM MST Sun Jan 1 2023
Monday night into Tuesday, models are showing the 500 MB low tracking
from far Northeastern Colorado into the Upper Midwest. On the
back side of this low, generally light snow and breezy conditions
are expected to continue across the plains with addition snowfall
amounts between a trace and and inch by midnight. The snow should
end by midnight with a few snow showers lingering across the far
northeastern zones into the early morning hours. Across the high
country, periods of light snow are expected to continue through
about noon on Wednesday due to a moist westerly flow aloft. As for
temperatures, max readings are expected to be some 10 degrees
below normal through Wednesday. Dry weather and moderating
temperatures are expected on Thursday as upper level high pressure
moves across the Rocky Mountain Region.
More snow is expected to return to the high country Friday and
Friday night as the next upper level shortwave moves across North
Central and Northeastern Colorado. At this time, snow accumulations
appear to be on the light side due to limited moisture. The plains
should remain mostly dry with near normal temperatures. Upper level
high pressure is progged to rebuild over Colorado by next weekend
with dry weather and seasonable temperatures.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 440 PM MST Sun Jan 1 2023
Fog has just moved into DEN with visibility less than a quarter
mile. Expect some minor improvement to begin in the 03-05Z time
frame when snow moves in. Before this, freezing drizzle will be
possible, though it should be very light. Once the snow moves off
after midnight, there will be a good chance the dense fog returns
with fzdz. This should continue into Monday morning. The next
period of snow moves in around 18Z Monday. Total snowfall for DEN
is expected to be up to 3 inches. Freezing drizzle may create
more issues though.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until midnight MST Monday night for
COZ031-033-034.
Winter Weather Advisory until 8 PM MST Monday for COZ035-036-
039>041-045-046.
Winter Weather Advisory from midnight tonight to midnight MST
Monday night for COZ038-042>044-048>051.
&&
$$
UPDATE...Meier
SHORT TERM...RJK
LONG TERM....jk
AVIATION...Meier
Area Forecast Discussion
National Weather Service Cheyenne WY
455 PM MST Sun Jan 1 2023
.SHORT TERM...(This evening through Tuesday)
Issued at 205 PM MST Sun Jan 1 2023
What a start to 2023!
KEY MESSAGES:
1) Widespread snowfall amounts of 5 to even 10 inches have been
recorded across portions of Carbon and Albany Counties already and
we are only 24 hours into this winter storm!
2) Winter Storm Warnings remain in effect for most of southeast
Wyoming and the Nebraska panhandle, with the exception of the
Laramie Valley where a Winter Weather Advisory is in effect.
3) Generally moderate to high impacts are expected across
southeast Wyoming and the Nebraska panhandle due to widespread
accumulating snowfall. Portions of the Nebraska panhandle may also
experience a brief period Monday morning and afternoon of freezing
drizzle which could lead to ice accumulation.
DISCUSSION: There are so many aspects of this storm to talk about
due to it being such a unique setup, especially for December, but
we are only going to hit on a few.
TIMING: Snowfall began last night and this morning across
portions of southeast Wyoming, the snow briefly lifted for a few
hours over portions of far southeast Wyoming, only to pick back up
later tonight. For timing, heavily leaned the forecast toward the
HRRR due to it picking up the current snowfall better than other
HiRes guidance. The time period for the heaviest snowfall across
the majority of the eastern portions of the CWA remains to be late
tonight through Monday morning as the low drifts northeastward and
the strong TROWAL impacts the majority of the CWA, resulting in
the likelihood for the heaviest precipitation. HiRes guidance
shows this happening mainly between 2 AM and 5 PM Monday. The
HRRR shows the snowfall ending in areas west of the Laramie Range
between 11 PM Monday and 2 AM Tuesday, then the areas of southeast
Wyoming east of the Laramie Range between 2 AM and 5 AM Tuesday,
and finally the Nebraska panhandle by 10 AM Tuesday.
SNOWFALL AMOUNTS: Forecast snowfall amounts have remained
relatively consistent, with the exception of a few minor
adjustments here and there. Carbon and Albany counties have
experienced the brunt of the storm thus far with accumulations 5
to 10 inches at lower elevations and 30 to 40 inches at the
highest peaks in the Snowy and Sierra Madre Ranges. Looking at the
forecast after 5 PM today, Carbon and Albany counties could still
see an additional 4 to 10 inches before the end of the storm. The
exception is the Laramie Valley. Unfortunately due to the
downsloping wind direction, Laramie is likely to be shadowed for
this event once again. The Valley`s best chance for more snowfall
is Monday afternoon when the winds are forecast to shift
northward. Converse, Niobrara, Platte, and Goshen counties are
forecast to see additional 6 to 12 inches of snowfall from 5 PM
today to Monday night. Laramie County is likely to experience a
sharp gradient in snowfall amounts from 4 to 6 inches in southern
parts of the county to 6 to 8 inches in northern parts of the
county. The northern Nebraska panhandle has the greatest
potential, especially up near the Pine Ridge where they could see
widespread 6 to 12 inches and 12 to 15 inches up on the ridge.
There is a great deal of uncertainty in the snowfall totals in
Kimball, Morrill, and Cheyenne counties due to the potential for
mixed precipitation. Currently in the forecast is 4 to 8 inches of
snowfall, but there is potential for freezing drizzle and ice
accumulation late this evening and Monday morning/afternoon. As
the previous discussion mentioned, the GFS soundings continue to
show significant drying aloft later this evening and over night,
while the lowest 8k+ feet remains entirely saturated within the 0
to -10 deg C layer. This will limit potential for ice growth in
cloud and will likely result in heavy drizzle, with significant
ice accretion very possible. Forecast ice accretion remains in the
0.05 to 0.1 inch range, with the highest amounts in Cheyenne
county. However, if the freezing drizzle holds on and does not
switch over to snowfall, the ice accretion amounts will
drastically increase, and snowfall amounts will be slashed. This
could lead to more serious impacts, such as downed trees and power
lines.
TEMPERATURES: Temperatures are forecast to remain relatively
moderate until Tuesday thanks to strong warm air advection at the
surface from the south and east. The environment is quite warm
and moist, especially for December! The dense cloud cover will
also help insulate the surface, preventing much diurnal
temperature fluctuations. Forecast low temperatures tomorrow
morning are in the 20s with high temperatures in the upper 20s to
low 30s. Temperatures in the single digits to teens move in late
Monday night to early Tuesday morning as the snowpack will help
cool the ground and our flow turns northerly, advecting colder air
into the area.
.LONG TERM...(Tuesday night through Sunday)
Issued at 105 PM MST Sun Jan 1 2023
Overview: Long term forecast period looks predominately uneventful,
with right at or just slightly above seasonal temperatures.
Lingering snowpack and a persistent, cool northwest flow aloft, will
help keep temperatures slightly below seasonal normals on Wednesday,
before a slow moderation occurs toward the end of the week. Most of
the region will see dry conditions, but the mountains could see some
lingering light snow showers Wednesday. With weak disturbances aloft
some elevated winds will be possible across the wind prone areas,
but high winds are unlikely at this time. Heading toward the end of
the week, long range models begin to hint at the next weather maker
which could bring some more widespread valley precipitation and
mountain snows back into the forecast.
Discussion: The main discussion point to mention in the long term,
is that potential next system by the end of the week. interestingly
enough, both the GFS and ECMWF are in fairly good agreement on the
longwave ridge/trough/ridge/tough pattern across the entire CONUS.
Focusing on SE Wyoming and the Nebraska Panhandle, both models bring
in a trough feature with the GFS showing a negatively tilted open
trough while the EC has a weak closed low developing across north
central Wyoming at the same time. Both solutions move the system NW
to SE across the region with some decent 700-500mb moisture content.
This would suggest a return of precipitation to the forecast in the
form of light valley rain/snow across Carbon and Albany counties and
mountain snow. PoP forecast will reflect the NBM output with low end
PoPs chances across those areas, while locations along and east of
the Laramie Range should remain dry.
&&
.AVIATION...(For the 00Z TAFS through Monday afternoon)
Issued at 455 PM MST Sun Jan 1 2023
Brief lull in the snowfall for most areas this evening before
activity ramps up again between 03z and 08z tonight. Widespread snow
expected for nearly all terminals through Monday morning. Some
freezing drizzle and fog possible along the Interstate 80 corridor
from KCYS to KSNY late tonight and Monday morning.
HAZARDS/WEATHER TRENDS: For now, will concentrate on start times and
intensity of snowfall arriving between now and 08z tonight: Expect
KRWL to have off and on light to moderate snow through the night and
Monday morning, so no changes planned at this time. Might need TEMPO
groups to address the variable intensity of the snow however.
For most other terminals, Expect snowfall to begin between
03z and 08z from south (KCYS, KSNY) to north (KBFF, KCDR) with a
rapid transition to LIFR conditions expected. KLAR will hold onto a
southeast or easterly wind, so a local snow shadow is likely with
intermittent snowfall and off/on MVFR conditions possible through
most of the night tonight.
&&
.FIRE WEATHER...
Issued at 105 PM MST Sun Jan 1 2023
Widespread snow & colder temperatures should minimize fire weather
concerns for the foreseeable future.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...Winter Storm Warning until 11 PM MST Monday for WYZ101-102-
104>111-113-116>119.
Winter Storm Warning until 5 PM MST Monday for WYZ103-112-114.
Winter Weather Advisory until 5 PM MST Monday for WYZ115.
NE...Winter Storm Warning from 5 PM this afternoon to 11 PM MST
Monday for NEZ002-003-019>021-054-055-095-096.
&&
$$
SHORT TERM...LK
LONG TERM...AW
AVIATION...TJT
FIRE WEATHER...CLH
Area Forecast Discussion
National Weather Service Dodge City KS
456 PM CST Sun Jan 1 2023
...|Updated aviation section...
.SHORT TERM...(This evening through Monday night)
Issued at 1218 PM CST Sun Jan 1 2023
18Z observations are showing a large trough over southern
California with a 100-110 kt jet streak from Baja California
through northern Kansas and Nebraska which is overspreading
widespread high and mid level cloud cover. At the surface a low
and frontal boundary are located in the far north Texas panhandle
and we have widespread light north to northeast winds.
Tonight the surface low and frontal boundary looks to move
slightly to the north and as it does so winds will continue to be
upsloping with the east to northeast direction. Moist air at the
surface will advect ahead of the front and saturate the boundary
layer especially after midnight. 850 mb winds will increase after
06Z and we should see an area of fog and drizzle develop across
most of southwest Kansas with the exception of the far southwest.
HREF probabilities of less than 4 SM being around 50-60% for much
of the area towards sunrise as well as the HRRR RH values and
surface visibilities being low gives better confidence for areas
of fog. The main storm system will be approaching the four corners
region by 12Z Monday and the first of the 700 mb shortwave will
enter into far southwest Kansas at this time. At this point it
looks like the precipitation we see will be mainly from any
drizzle we get with the rain potential being more towards the day
on Monday. Lows tonight should stay above freezing CWA wide so
didn`t see the need to include any freezing drizzle wording.
Monday it still looks like models haven`t quite have a handle on
the track. GFS run to run continues to have the main center in
northeast Colorado. RAP/NAM are a little further south and the
latest 12Z Euro is slightly more north than previous runs. CAM
models are in pretty good agreement of an area of rain developing
along and east of highway 283 after 15Z as the main mid level
energy will move into southwest Kansas. I thought the WPC idea of
having the highest QPF potential from Scott City to Hays looked
good. Elsewhere the dry slot is still also on track for our far
southwest zones so it does look like a quick clearing of the fog
and low clouds should happen for areas around Liberal to Elkhart
with the clearing later in the day for areas from Dodge to Garden
City. I kept the low clouds in for much of the day in our northern
and eastern zones and hence lowered the high temperatures to the
lower to mid 40s. Areas from Liberal to Elkhart will be near 60
and everybody else`s temperatures will be largely factored on how
much of the weak insolation can burn off the fog.
Monday night the last of the strongest mid level energy should
exit into Nebraska and our precipitation should quickly end from
south to north during the evening hours. A cold front on the back
side of the low will race through northwest Kansas during the
evening and southwest Kansas around midnight. This could lead to a
brief changeover to snow for areas along the I-70 corridor but
accumulations should be a dusting at the most. Winds will also
increase as the front passes and lows should fall into the 20s.
.LONG TERM...(Tuesday through Sunday)
Issued at 155 PM CST Sun Jan 1 2023
Tuesday will be cooler as the winds will be out of the northwest
and 850 mb temps range from 0 to -5 (C) and highs in the lower
40s.
Cooler temperatures will continue into Wednesday as the long wave
trough slowly moves through the central plains. By Thursday we
should start a slight warm up as a ridge moves from the Rockies
into the central plains. The next system of interest will be
coming in Friday night through Saturday with the track currently
taking most of the energy to the north.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 454 PM CST Sun Jan 1 2023
VFR conditions will prevail this evening with overcast high
clouds. Low clouds and patchy fog will quickly form after midnight
reducing visibilities and ceilings to IFR to LIFR. These low
clouds and patchy fog will continue into late morning with some
clearing tomorrow afternoon. Winds will generally be form the
northeast through tomorrow morning then shift to a southerly
direction by tomorrow afternoon.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 37 55 25 43 / 30 40 20 0
GCK 36 52 23 41 / 30 40 20 0
EHA 37 59 25 45 / 20 20 10 0
LBL 37 60 24 44 / 30 30 10 0
HYS 35 47 24 39 / 40 60 40 0
P28 41 56 30 46 / 30 40 10 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Tatro
LONG TERM...Tatro
AVIATION...Hovorka_42
Area Forecast Discussion
National Weather Service Des Moines IA
530 PM CST Sun Jan 1 2023
...Updated for the 00z Aviation Discussion...
.DISCUSSION.../Tonight through Sunday/
Issued at 339 PM CST Sun Jan 1 2023
Key Messages:
- Potential for significant ice over northern Iowa late Monday
into Tuesday.
- Primarily rain and some rumbles of thunder central and south.
Radar imagery as we approach 22z shows some minor returns as a
subtle wave percolates through the nearly zonal flow aloft. The
weak forcing and poor moisture availability is preventing most, if
not all of this precip from reaching the ground at this time.
Primary feature of concern at the moment is an amplified trough
digging through the Great Basin and into the Four Corners region.
Models attempt to generate some light, sporadic QPF early in the
day as mid-level waa cranks up ahead of the approaching trough.
Expecting much of thus early day precip potential to also succumb
to dry air. Showers and perhaps some thunderstorms dramatically
increase by late afternoon or evening as the trough emerges into
the central Plains as strong, phased kinematic and thermodynamic
forcing focuses over the state. Northward moisture fetch
strengthens considerably as the trough begins to take on a
negative tilt, with the RAP showing as high as 5 to 6+ g/kg spec
humidity streaming northward on the 295k surface. While mostly
liquid rain is expected central and south, a significant icing
event may unfold over portions of northern Iowa where the deep,
warm moist air overrides surface temps near to below freezing. Ice
accretion efficiency will be limited at times due to moderate
rainfall rates, but much of the 12z model suite has painted a
swath of 0.25"+ ice accums across northwest and into north central
Iowa Monday night. Forecast hedged toward the more consistent
Euro solution, but ice accums were pulled a bit further east to
match the trends shown in several hi-res models. An Ice Storm
Warning was issued for areas most likely to see the heavier ice
amounts. Travel impacts and the potential for power outages are a
concern. A Winter Weather Advisory borders the warning just to the
south where the 0c wet bulb transition likely resides during the
evening into the overnight hours, and thus considerable
uncertainty on potential icing. The longevity of ice impacts is
also in question as warm air continues to be pulled northward and
the sfc thermal field pivots around the low. This may bring temps
back above freezing as far north as Mason City to Algona by early
Tuesday morning, so the end time of the warning/advisory may be
need to be adjusted.
Dry air begins to wrap around the low by later Monday night into
Tuesday morning and erodes a good chunk of the precip over the
forecast area. Precip will begin to focus more on an intense
deformation zone crossing the SD in southern MN. A few inches of
snowfall are possible as it clips our far northwest counties. The
upper low continues to weaken and wobble a bit as it occludes
Tue night into Wed. This will keep some chances for some light
snow around as it interacts with residual moisture over the area.
Weather pattern quiets down over the latter days of the work week
as the upper low departs and a ridge builds over the central
conus. Highs rise from the teens and 20s and Thursday to back into
the 20s and 30s, and perhaps 40s south on Friday. Next window for
winter precip opens next weekend as models bring another upper
low off the Rockies. 12z deterministic models trended more bullish
on QPF potential, however ensemble data sets remain much more
conservative. Latest NBM init may be a bit behind on expanding
mention PoPs over the area, so would anticipate if more widespread
chance PoPs are introduced in forthcoming updates.
&&
.AVIATION.../For the 00Z TAFS through 00Z Monday evening/
Issued at 530 PM CST Sun Jan 1 2023
Patchy fog is possible overnight, however current guidance
suggests this will remain north of the area so have kept from
TAFs for now. Into Monday morning ceilings will drop to MVFR and
then to IFR as stratus spreads across the area ahead of the
approaching system. Precipitation will expand through the late
afternoon, reaching eastern sites just beyond the current TAF
period.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
Ice Storm Warning from 6 PM Monday to 6 PM CST Tuesday for
IAZ004>007-015>017-023-024-033.
Winter Weather Advisory from 6 PM Monday to 6 PM CST Tuesday for
IAZ025>028-034>036-044-045.
&&
$$
DISCUSSION...Martin
AVIATION...Hagenhoff
AREA FORECAST DISCUSSION
National Weather Service Hastings NE
502 PM CST Sun Jan 1 2023
...AVIATION UPDATE...
.DISCUSSION...(This evening through Sunday)
Issued at 358 PM CST Sun Jan 1 2023
Key Messages:
* Complex and significant winter storm with ice and snow will
impact the region Monday into Tuesday. The transition zone from
ice/snow to mostly rain will likely reside over the forecast
area much of Monday-Monday night.
* The Winter Storm Watch has been upgraded to a Winter Storm
Warning, with a few counties added on the S/SE side. A Winter
Weather Advisory has been issued for the same time frame for a
row of counties to the S. Finally, additional counties along
NE/KS state line will go into an advisory Monday night.
* While uncertainties still abound, which is inherent given sharp
transition zone ptype within the forecast area, model spread
has lessened and they appear to be converging toward a solution
that has been most consistent with the EC ensemble mean.
* Finally, it`s important to note that impact timing and severity
will vary widely from N/NW to S/SE, with the Tri-Cities likely
within the transition zone. Folks with end-of-holiday travel
should do so yet today, or tomorrow if heading E/S. Folks
traveling N/W should consider waiting until Tue PM or Wed AM.
Forecast Details:
Primary concerns are in the first 36-48hrs, which is where nearly
all forecasting time was spent on.
Will start off by saying that model spread has generally decr (as
one would expect) over the past 12-24 hrs, though there is still
some spread noted, particularly between EC and GFS/GEFS/CMC. With
that said, there has been a notable trend in the GFS towards the
EC ensemble mean, which is the preferred forecast model for this
package. Early runs of extended HRRR/RAP seem to align well with
the overall thinking from the EPS.
For tonight: Most of the overnight hrs should be fairly quiet. The
exception could be over far S/W zones after midnight, where
DZ and/or FZDZ may develop. May also be some fog over far S zones
by dawn. Models have been trending slower with the onset of
impactful pcpn, and felt confident enough in this trend and that
90-95 percent of the headline areas will dry through tonight to
push back the start of the Winter Weather products until 12Z.
Monday: Again, models have trended a bit slower, but think we`ll
see a rapid influx of moisture/pcpn during the AM hrs as low
pressure deepens along the High Plains. Strong moisture transport
of +2 to +4 std dev PWATs leads me to lean towards solutions with
heavier and more widespread QPF for the daytime hrs Mon. EC has
been leading the way in this aspect, and see no reason to deviate.
The main forecast issue will be pinning down sfc temps. Winds will
be backing from E to NE late tonight-Mon AM, and with sfc high
sitting to the N and thick cloud cover, think temps will really
struggle to rise on Mon. In fact, RAP H925 temps clearly fall
throughout the day, with freezing line starting near ODX, but
ending up near NE/KS state line by Mon eve. This lead me to favor
COLDER sfc temp solutions of the NAMNest/HRRR/RAP, and used some
of this data in a blend with NBM. This resulted in a few deg drop
in hrly temps and highs. This will make frz rain more of an issue
for the daytime hrs, at least for the N third of CWA. The tricky
part will be from roughly the Platte River to Hwy 6 corridor as
even the colder models hover temps within a degree, or two, either
side of freezing...pretty much all day. 12Z HREF shows very little
fluctuation in 32F line from near Elwood to GRI to OLU,
essentially all day. Incr NErly flow will aid in frz rn accum
efficiency, esp. on trees/elevated sfcs., but roads may not be all
that bad within this zone, esp. considering the daylight hrs. This
could be a situation where N side of GRI sees a couple tenths of
ice and HSI receives almost none. Areas S/SE from HSI will likely
experience just a cold rain with temps in mid to upper 30s. There
could be some convective elements to the pcpn by Mon aftn, but
didn`t explicitly include in the forecast. This would actually
decr frz rn efficiency due to runoff.
Monday night: Expect a gradual transition from RA to FZRA to SN
(with perhaps some brief IP mixed in) from W/NW to E/SE during the
eve hrs...exactly how far/fast is uncertain. The speed of this
transition will go a long way in determining final impacts. EC is
generally a bit faster, likely owing to stronger sfc low that
moves along I-35 corridor from KS to IA, then stalls...which leads
to more frozen pcpn for central part of CWA, and more snow for
far W/NW zones. Again, this has been a fairly consistent feature
on the EC/EPS, and was generally the preferred forecast solution.
The stalling and more intense low to mid level low pressure also
lends to more organized wrap-around pcpn and potentially more
snowfall for our area. The forecast was trended in this direction,
but didn`t go as high as the operational EC runs would suggest.
This idea would give mostly fzra/snow by midnight, then mostly
snow by 12Z Tue. NE-N winds will be on the incr, which is
definitely a concern for what will likely be ice-coated trees and
power lines by this time for a majority of our NE zones N of Hwy
6. Would expect some power outages in these areas by dawn Tue AM.
Tuesday: Biggest question for this period will be how long does
pcpn hang on, as even the lesser favored GFS is all snow by dawn
Tue. As mentioned above, EC is generally stronger, more negatively
tilted, and thus more efficient at wrapping warm/moist air
westward within a TROWAL. Again, didn`t go straight deterministic
EC, but felt PoPs AND QPF needed to be incr as even the EPS
lingers snow across most of south central Neb. for the AM hrs.
Colder air wrapping into the system should also incr SLRs, though
probably not much more than 12-13:1. Think most areas N of the
state line should see a dusting to 1" 12Z to 18Z Tue, with perhaps
some areas around ODX to OLU even 2-3". With Nrly wind gusts
around 30-35 MPH, some blowing/drifting snow will likely be an
issue for the harder hit areas through the AM hrs. Some blsn may
extend beyond midday, but felt comfortable leaving headline end
time of 18Z as most areas will be calming down.
So to reiterate...confidence is HIGH that at least PORTIONS of the
CWA will experience significant ice/snow/wind impacts from this
system Mon thru Tue AM. Most likely area for these impacts will be
within the Winter Storm Warning area from late Mon AM through Tue
AM, though the S tier of counties (like Phelps, Hall, Hamilton,
and Polk) may be just barely warm up to delay impacts to Mon eve.
These areas were a tough call on advisory vs. warning, and for
start time. However, felt best to err on side of caution given
potential for post-holiday travel that includes I-80. Significant
impacts to travel will occur, and power outages will be possible,
esp Mon night into Tue., and esp. N of LXN to OLU line.
Confidence in coverage, severity, and timing of impacts decr for
areas S of I-80 and N of the state line. Still think enough ice
and snow will occur to cause travel issues, but may not be until
Mon eve as sun sets and temps cool more solidly below freezing.
Travel impacts will likely peak late Mon night thru Tue AM. Unknown
if enough ice and wind will occur for power issues in this area.
If temps are 1-2 deg cooler during the day Mon, or if wrap around
snow is more organized/persistent, then some of the advy may need
to be upgraded to a warning.
Most areas along/S of the state line will probably remain warm
enough to preclude wintry pcpn issues through about 06Z Tue. May
see some FZRA/IP late, but quick transition should limit amnts.
Some lgt wrap around snw will be possible, but only EC is giving
much more than a dusting. Rising temps as pcpn ends Tue should
lead to improving conditions by midday Tue, even if some minor
ice/snow occurs.
The rest of the forecast is dry. Temps will remain cool through
midweek, then gradually warm Fri into next weekend.
&&
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Tuesday)
Issued at 453 PM CST Sun Jan 1 2023
A -FZRA event is expected to impact the TAF sites tomorrow
morning. I kept EAR in -FZRA during the TAF period as it looks to
remain below freezing. GRI is closer to the freezing line and
looking at some of the short range models thought the afternoon
could warm above 32f allowing for some change over to -RA for a
brief time. My confidence in the -RA is low, but it did look like
a small possibility... Tomorrow afternoon the ceilings look to
drop to LIFR and vis looks to drop also to at least IFR for now.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...Winter Weather Advisory from 6 PM Monday to noon CST Tuesday for
NEZ077-085-086.
Winter Storm Warning from 6 AM Monday to noon CST Tuesday for
NEZ039>041-046>049-060>063-072-073.
Winter Weather Advisory from 6 AM Monday to noon CST Tuesday for
NEZ064-074>076-082>084.
KS...Winter Weather Advisory from 6 PM Monday to noon CST Tuesday for
KSZ005-006.
&&
$$
DISCUSSION...Thies
AVIATION...Beda
Area Forecast Discussion
National Weather Service Goodland KS
458 PM MST Sun Jan 1 2023
.SHORT TERM...(This evening through Tuesday Morning)
Issued at 214 PM MST Sun Jan 1 2023
Overcast skies are dominating the area ahead of a potent trough over
the Baja Peninsula as this is the main weather maker for the
short term period. For this evening, confidence is fairly high in
fog and/or some drizzle occurring along and south of Interstate
70. The HRRR, LAMP and RAP have been in great consistency with the
development of reduced visibilities, some dense fog may possible.
The fog is expected to continue into the morning before the
winter weather side of this system comes into play.
Guidance continues to struggle with the overall positioning of
the system as the 12Z runs were taking it north which favors less
precipitation; whereas the 18Z runs are trending it more south
again. The NAM and GFS has the low over the NW portion of the area
which favors more a wintry mix/freezing rain scenario whereas the
HRRR and ECMWF take it further south which favors more
accumulating snow. The one hazard that most guidance has increased
on is ice accumulation across the area as a result of this I
opted to issue a Winter Weather Advisory for all but Greeley,
Wichita and Gove counties as they are expected to remain above
freezing for the duration of the precipitation. Forecast soundings
do show a fairly stout warm nose especially north of I-70.
Freezing rain mixing with snow is expected to develop across
eastern Colorado late this evening which is what prompted the 06Z
start time for the advisory.
Into Monday, precipitation is expected to increase in coverage in
the form of rain to the south, snow to the north and wintry
mix/freezing rain in between. It is unusual to be this close to an
event and guidance to continue to vary on solutions. Confidence is
high though that wintry weather will occur across the majority of
the area. As additional runs of guidance continue to come in it is
very possible that an upgrade may be needed for portions of the
area. The relative best timing for freezing to occur is overnight
tonight and through the morning Monday before the best chance for
accumulating snow is Monday afternoon through Tuesday morning. Winds
will begin to increase as the system moves off to the east with
gusts up to 35 mph possible. This may create some blowing snow in
areas with greatest snow depth or it may create extra stress on
power poles and trees that have any ice accumulation on them. The
heaviest of snow looks to come to an end overnight Monday and into
Tuesday morning with the advisory ending at 12Z, although some light
wraparound snow does remain possible into Tuesday morning.
High temperatures for Monday were lowered to account for overcast
skies. Highs look to struggle to get out of the mid 30s for the
majority of the area as highs to the south are forecasted to be
in the lower 40s. Temperatures into Tuesday morning may need to be
lowered some if snow pack does occur across the area. The current
forecasted lows for Tuesday morning are in the upper teens to mid
20s across the area.
.LONG TERM...(Tuesday through Sunday)
Issued at 1215 PM MST Sun Jan 1 2023
Light wraparound snow showers may linger into Tuesday morning for
northern parts of the area, otherwise the long term period is dry.
Temperatures will be below normal Tuesday and Wednesday under
northwest flow aloft with highs in the 30s. Upper ridge then moves
across the area on Thursday with temperatures warming into the
40s. Next shortwave trough follows on Friday/early Saturday with
models showing only limited, if any, precipitation chances. System
is of Pacific origin and temperatures are negligibly impacted.
Another ridge builds over the weekend with highs in the 40s and
50s.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 326 PM MST Sun Jan 1 2023
**** Update ****
Lower ceilings and visibilities have begun moving in from the west
already as the air continues to saturate. Have amended KGLD to
start the lower visibilities and ceilings now. This was due to
surrounding observations and best guest based on manual
observation.
****
An advancing trough will bring aviation concerns at each site
starting this evening as ceilings and visibilities will gradually
fall through the evening with IFR being dominant at KGLD around
07Z before a duration of LIFR for the majority of the day Monday.
Ceilings will slowly drop at KMCK becoming MVFR around 11Z and
then IFR around 14Z. Rain/Freezing Rain/Snow can be expected at
each site.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...Winter Weather Advisory from 11 PM MST /midnight CST/ this
evening to 5 AM MST /6 AM CST/ Tuesday for KSZ001>004-
013>016-027-028.
CO...Winter Weather Advisory from 11 PM this evening to 5 AM MST
Tuesday for COZ090>092.
NE...Winter Weather Advisory from 11 PM MST /midnight CST/ this
evening to 5 AM MST /6 AM CST/ Tuesday for NEZ079>081.
&&
$$
SHORT TERM...Trigg
LONG TERM...024
AVIATION...Trigg/KAK
Area Forecast Discussion
National Weather Service Grand Rapids MI
926 PM EST Sun Jan 1 2023
LATEST UPDATE...
Update
.UPDATE...
Issued at 919 PM EST Sun Jan 1 2023
Mainly cloudy skies prevailed across the region at this time.
Where the clouds have scattered out...patchy dense fog has formed.
Kalamazoo was down to 1/4 mile at last check. Many areas will see
fog tonight with some of it locally dense. Given the widespread
cloud cover...confidence is not high enough to go with a dense fog
advisory...but we will have to watch trends closely. I did update
the hazardous weather outlook to mention the potential for
localized impacts from the fog tonight.
&&
.DISCUSSION...(This evening through next Sunday)
Issued at 323 PM EST Sun Jan 1 2023
- Areas of Fog Overnight and into Monday morning
The setup for fog development late tonight looks better than what
occurred this morning into early afternoon. Light or calm winds
beneath an inversion at 1000 ft combined with low dew point
depressions, in some cases zero (RH=100%), should create an
environment supportive of at least light fog to form. Some dense fog
is also possible mainly south of I-96. The inversion height may be a
bit high for more of a widespread dense fog to occur especially
further north (ie. GRR-LAN and points north), but the 12z HRRR does
show inversion heights closer to 500 ft along I-94. The current
thinking is that is where probabilities for dense fog are greater.
- Rain Still on Track for Monday Night and Tuesday
Numerical models have been unwavering for days with regard to a warm
advection rain event Monday night into Tuesday. Yes, as the previous
discussion noted, a few thunderstorms are also possible given
perhaps 100 J/kg of MUCAPE sneaking into areas south of I-96. Not
only is elevated instability possible, but the ECMWF, GFS, and GEM
are all showing potential for surface based instability (in
January!) south of I-96. That is what happens when surface
temperatures push 60F and dew points get into the mid 50s. If we get
to 60F at any of our long term climatological stations, that would
either tie (at AZO) or break (all the other sites) records for
January 3.
The upper low that is bringing widespread precipitation to
California and the Desert Southwest today will lift to the northeast
and deepen over the Midwest. Models are indicating a ~995 mb
surface low moving over Iowa by 12z Tuesday, maturing until 18z
or so before it begins the occlusion process. A 50-60 kt LLJ will
intersect the system`s warm front right over southern Lower
Michigan. Model QPF continues to be solidly in the 0.50"-1.00"
range for southern Lower MI, highest along I-94. Amounts less than
0.50" are looking more likely north of I-96 and especially near
U.S. 10. See the Hydrology section for expected impacts with this
rainfall.
- Rain Changing to Snow Wednesday with Falling Temperatures
The upper low will be slow to depart the region. The 850mb
temperatures start dropping below 0C Wednesday afternoon and colder,
northeasterly low level flow will begin to overspread the region.
We should see temperatures drop below 32F everywhere between
7pm-10pm Wednesday night. Temperatures will continue declining
into the teens and low 20s by Thursday morning. Wraparound
moisture on the north side of the occluding low will move in from
north to south. Model QPF is indicating 0.10"-0.30" of liquid
equivalent falling as pure snow. That occurs as an area of
850mb-500mb deformation swings through, particularly as shown by
the ECWMF and GEM. Even with the GFS, there is shown to be a deep
layer of 925mb-700mb Fn vector convergence setting up especially
near and north of I-96 around 00z Thursday, indicating there will
be an area where the layer`s thermal gradient is potentially
stronger and in general, banded snow is a possibility while this
moves through because of frontogenetical forcing. We could easily
pick up 1"-3" of snow as this system departs, most of that falling
late Wednesday into early Thursday. As a result, the Thursday
morning commute could prove to be rather slippery depending on how
this takes shape. The 12z ECE ensemble mean snowfall (10:1) shows
1"-3" area wide, with a 30% probability for over 3" north of I-96
and a 10% probability for over 6". So, something to keep in mind
for the Thursday morning commute.
- Light Snow or a Mix Possible Next Saturday into Sunday
Another potent West Coast atmospheric river event will occur mid to
late week. Some mid level vorticity with the 500 mb wave
approaching the West Coast mid week is shown to break off and head
on an eastward trajectory. Models are showing a modest shortwave
moving toward the Midwest by the weekend. There are timing and
location differences with this feature, not surprising this far
out. A weak surface low could form. This may give us a chance for
some light snow accumulations or a mix of rain and snow.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 642 PM EST Sun Jan 1 2023
The cloud bases have lifted at most sites with generally MVFR
conditions prevailing. There were even some patches where the
clouds have scattered out. However as we go through the
night...a fairly strong signal for widespread IFR and lower conditions
developing exists for all sites. While we will see some slight
improvement to the ceilings and visibilities during the day on
Monday generally IFR is forecast to prevail into the afternoon for
most site. Rain will be approaching from the southwest later in
the day...but it looks like it will hold off until Monday night.
&&
.MARINE...
Issued at 323 PM EST Sun Jan 1 2023
Some fog is possible overnight and into Thursday morning mainly
near and south of Holland. Otherwise, light wave action is
expected until later Tuesday into Wednesday. By Wednesday, winds
and waves may be hazardous to small craft.
&&
.HYDROLOGY...
Issued at 323 PM EST Sun Jan 1 2023
With expected rainfall of generally 0.50"-1.00" Monday night into
Tuesday, our 72-hr contingency forecasts for area rivers do not
show flood stage being reached on major rivers, even when
factoring in the small chance of an overachieving rain event on a
larger geographic scale (ie. if well over 1.00" occurs along
numerous points within a given basin). However, some significant
within bank rises could occur especially on smaller rivers and
streams with our current QPF and especially if the event
overachieves.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...None.
&&
$$
UPDATE...MJS
DISCUSSION...Hoving
AVIATION...MJS
HYDROLOGY...Hoving
MARINE...Hoving
Area Forecast Discussion
National Weather Service Lincoln IL
809 PM CST Sun Jan 1 2023
.SYNOPSIS...
Issued at 300 PM CST Sun Jan 1 2023
Areas of fog likely again tonight, some of which may be dense. A
strong low pressure system will move through the Midwest this
week, resulting in well above normal temperatures across the area
through Tuesday, with highs in the mid 50s to low 60s. Widespread
showers and scattered thunderstorms move through Monday night into
Tuesday.
&&
.UPDATE...
Issued at 808 PM CST Sun Jan 1 2023
This evening, a warm front stretches from roughly St Louis east-
northeast along the I-70 corridor. Near and north of the front,
low stratus and fog is once again expanding north across central
Illinois and will remain in place overnight. Fog has the potential
to become dense across the area, but this is most likely just
north of the front between the I-70 and I-72 corridors. Meanwhile,
temp-dewpoints spreads across central Illinois are generally less
than 2 degrees area wide. With increasing cloud cover and
seasonably high surface dew points, temps will not be able to move
much overnight and may even warm a degree or two in a few spots.
&&
.SHORT TERM...(This evening through Monday)
ISSUED AT 300 PM CST Sun Jan 1 2023
An active stretch of weather is on tap through Tuesday as strong
low pressure system develops over the central Plains on Mon and
lifts into the upper Midwest by Tues. Forecast impacts across
central IL include:
1) Additional dense fog tonight into Mon
2) Thunderstorms Mon eve into Tues, with a chance for isolated
flooding and strong storms, primarily south of I-70.
3) Potentially record-setting warmth
A deep upper trough is evident across the western US in water
vapor imagery this afternoon, with a baroclinic leaf
overspreading the southwestern Plains. As lee cyclogenesis unfolds
this evening, a frontal boundary positioned across OK/the Ozarks
will lift northward overnight as a warm front.
That warm front will be draped across central IL tonight, keeping
winds light with little change in temperatures/dewpoints
overnight. Another round of at least patchy dense fog is looking
likely. Both the deterministic NBM and the latest HRRR show
widespread dense fog developing. Probabilistic guidance also
favors dense fog, with the HREF showing a 60-80% chance of vis
below a half mile across much of the CWA. Similar to today, fog
could linger through much of the morning on Mon.
The front will continue to lift northward Mon, with a tightening
pressure gradient. High-res guidance tries to develop isolated to
scattered showers across the southern CWA, in response to WAA,
however suspect that height rises aloft in advance of the trough
to our west may help stymie shower activity until later in the
afternoon. A more widespread push of precip, including a chance
for thunderstorms, arrives Mon evening after sunset as warmer,
more moist air advects northward into central IL. Guidance
continues to show marginal instability in place, with a few
hundred J/kg of MUCAPE. A robust LLJ will overspread the area Mon
night, with 850mb winds in excess of 65 kts, resulting in
substantial low level shear. Despite this, severe t-storms still
appear unlikely. Forecast soundings for Mon night show weak,
albeit non-zero, sfc-based instability (lowering the tornado
threat) and weak mid-level lapse rates (eliminating a hail
threat). DCAPE is not particularly high, but any stronger
downdrafts may result in vertical momentum transport of the strong
LLJ winds to the surface, resulting in isolated strong wind
gusts. Will need to keep an eye on any lingering activity across E
IL Tues AM, as forecast soundings show the low-level inversion
weakening. Not only will that allow storms to more readily mix
down stronger LLJ winds, but that may allow weak sfc instability
to develop: soundings show about 50 J/kg of 0-3km CAPE, which is
not overwhelming, but with high low-level helicity (0- 1 km SRH
approaching 400 m2/s2) it would not take much for storms to become
frisky. The key takeaway here: it`s more likely than not that
storms remain sub-severe in our CWA. However, with such strong
low- level shear, it is a setup that demands close attention be
paid to any storms that do develop, especially across E IL into
Tues AM.
PWAT values are expected to push into the 1.25-1.5" range, which
would be among the highest ever sampled in central IL in January.
Despite these values, fast storm motions, a lack of training
storms, and thawed ground should limit the flood potential.
Guidance continues to highlight south of I-70 as the axis of
heaviest precip from this system, and those areas saw 0.75-1.25"
of precip over the weekend. The latest HREF suggests most areas
south of I-70 see another 0.75-1.25" of rain, but localized,
convectively-driven rainfall totals of up to 2" are possible.
Further north, rainfall amounts are most likely to be around 0.5",
with localized amounts up to 1".
Despite mostly cloudy skies, unseasonably warm to near-record
temps will persist through Tues. Highs on Mon will be in the mid
50s to low 60s. As the low pressure approaches from the west Mon
night, continued southerly flow will result in temps staying in
the 50s across much of the area, which would be record warm lows
for Jan 3rd. (The caveat here is that lows may fall enough Tues
eve before midnight to prevent records from being set for that
calendar day). A cold front will push through on Tues, but before
it does, temps are expected to climb into the 60s, nearly 30
degrees above normal for early January. The record warm temps for
Jan 3rd are 61F in Peoria, 63F in Springfield, and 65F in Lincoln,
and our forecast currently calls for records to be broken in
Peoria and Springfield.
.LONG TERM...(Monday night through Sunday)
ISSUED AT 300 PM CST Sun Jan 1 2023
After a cold front moves through on Tues, much cooler air arrives
by Wed. Guidance shows 850mb temps falling from +12C on Tues to
around -5C on Wed. Sfc temps will be nearly about 25-30F cooler
than Tues, which will result in temps back near typical values for
early Jan.
As the upper low meanders around the upper Midwest, it may lead to
scattered showers, primarily snow showers, Wed afternoon through
the overnight into Thurs. The best chance for such showers is
across the northern half of the CWA. Little accumulation is
expected from this activity, with locations that do see snow
likely seeing a dusting or less. NBM probabilities have less than
a 20% chance for seeing 1" of snow. Temps are expected to remain
seasonable through the remainder of the work week, with highs in
the 30s and lows in the 20s.
Into the weekend, a slight warmup is possible as upper level
ridging shifts over the Midwest ahead of another shortwave.
There`s still a good deal of uncertainty in the track/timing of
the sfc low associated with that wave, but will need to monitor
the precip potential Sat/Sun.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 524 PM CST Sun Jan 1 2023
A warm front stretches from roughly St Louis through Paris, IL
this evening and will slowly lift north to near the I-72
corridor by early Monday evening. IFR/LIFR ceilings are expected
near and north of the front through the period along with light NE
to east winds. Visibility is expected to lower with fog
development tonight and could also fall into LIFR category.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Deubelbeiss
SYNOPSIS...Erwin
SHORT TERM...Erwin
LONG TERM...Erwin
AVIATION...Deubelbeiss
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
845 PM CST Sun Jan 1 2023
.UPDATE...
Issued at 845 PM CST Sun Jan 1 2023
Had updated forecast earlier to introduce/expand areas of fog across
parts of northern IL. Most widespread dense fog has been near the
IL/WI border region through mid-evening, and had issued a dense fog
advisory for those areas earlier. Starting to see some patchy dense
fog developing southward into parts of the I-88 corridor at this
time, and while webcams generally indicate this is likely somewhat
patchy, may need to eventually expand fog advisory farther south.
Surface analysis indicates that the weak front which settled across
the area late last night/early this morning runs from just south of
Pontiac to near Rensselaer as 02Z. Air mass south of this boundary
is characterized by temps and dew points in the 40s, while farther
north temps and dews were mainly in the mid-30s aside from a few
milder spots in the Chicago metro. GOES nighttime microphysics RGB
combo shows an extensive stratus layer within the warmer air south
of the boundary, while father north patchy low clouds/obscuration
were harder to see due to mid-level clouds. Quite a spread in
various high-res guidance with respect to fog trends overnight,
though the high-res ARW appears reasonable at this point. This would
suggest some additional expansion across parts of the I-88 corridor
overnight, as well as parts of northwest IN/far southeast cwa. This
(and the RAP to some extent) even suggest some erosion of fog across
the IL/WI border region during the pre-dawn hours as low level winds
turn light north-northeasterly. Based on guidance and obs trends,
may need to expand the dense fog advisory southward across the I-88
corridor by late evening if dense fog becomes more widespread, and
perhaps farther south/southeast overnight as well.
Otherwise, going forecast appears to be in decent shape into Monday
morning and no other significant changes were made.
Ratzer
&&
.SHORT TERM...
Issued at 253 PM CST Sun Jan 1 2023
Through Monday night...
Temperatures this evening and overnight will be rather steady thanks
to some modest low level WAA and low ceilings in anticipation of the
approaching storm system. Meanwhile, a potent, quasi-stationary warm
front will be hanging out in central IL tonight before trekking
northward into the area on Monday. Lows Monday morning will bottom
out near freezing across some of Illinois` northern-most counties
while the far southern CWA nearer to the front will hang in the
lower 40s. Mid-afternoon temperatures will reach the 40s and lower
50s on Monday. Though once the front begins its progression through
the area Monday evening and night, conditions will steadily warm
behind it. Some spots in far south may not even drop below 50 before
they begin warming through the night eventually tapping into the 60s
by Tuesday morning. Areas further north, primarily north of I-90,
will be allowed to cool back into the upper 30s prior to the arrival
of the front Monday night. However, these areas too will warm
overnight with the whole CWA expected to be in the 50s by mid-
morning on Tuesday.
Meanwhile, areas of dense fog this morning have thinned out across
the area, though not completely dissipated. Several spots are still
reporting visibilities under 5 miles as of 2PM. This isn`t expected
to improve much through the remainder of the day before conditions
are expected to worsen tonight. With dewpoints sitting in the upper
30s and lower 40s this afternoon, areas of dense fog are anticipated
to redevelop as we cool down into the 30s this evening and
overnight. The greatest potential for widespread, dense fog is
across and south of the Kankakee River valley where they may see
some limited moisture advection take place overnight. Through the
day tomorrow, fog may stick around or redevelop across areas along
and south of the front as we begin to see that influx of low level
moisture.
As far as the rain expectations go, there have been a few notable
changes among guidance since yesterday`s runs. However, the most
notable would be the drop in coverage and overall intensity and a
resultant drop in QPF. Best guess as to why this is would be the
shift in the track of the LLJ to the southeast. The LLJ was
previously expected to just graze the CWA to the southeast, but
models are now showing it even further displaced from us now moving
through central and southeast Indiana and the higher QPF has
followed suit. The NAM keeps the LLJ a bit more local leading to
higher QPF, though it has certainly become an outlier among models.
The LLJ has also taken some of the moisture with it, though PWAT
values are still shown to exceed one inch across just about the
whole CWA. As high-res and convective allowing models are now
reaching into the brunt of this storm, simulated reflectivity shows
the rain coverage may not be quite as widespread as previously
thought, or at least the window for truly widespread rain has
tightened now that we`ve removed some of our moisture and forcing.
Nonetheless, a healthy amount of rain remains in the forecast
through Tuesday morning. Latest QPF among guidance shows most of the
area receiving roughly 0.5-0.8" of rain. Models and ensemble members
with widespread 1"+ totals have become few and far between.
Though QPF has dropped a bit, thunder chances are kept alive by the
ample low level instability still in play. Not a whole lot has
changed on the thunder front, in fact, with about 200-400 J/kg of
MUCAPE still expected across most of the area, the higher end of
that expected further south in the CWA. Some decent low level shear
also presents a low, but non-zero, threat for a couple of strong
thunderstorms, with damaging winds being the primary concern. The
strong storm threat is mainly a concern south of I-80 where the
greatest instability and stronger low level flow can be found. At
this point, at least a couple of light, embedded thunderstorms in
this area appear probable. The most favorable time for thunderstorms
lines up with the expected timeframe of the heavier and most
widespread rainfall: roughly the six hour period between 10PM and
4AM. The soaking rain overnight will likely be followed by some
scattered showers through much of Tuesday morning with a slight
chance for a light thunderstorm or two hanging on into the morning
as well.
Doom
&&
.LONG TERM...
Issued at 220 PM CST Sun Jan 1 2023
Tuesday through Sunday...
Key weather messages during the long term period are:
* Near-record to record warm high temperatures on Tuesday in
tandem with breezy southerly winds
* Turning colder with a chance for snow including the possibility
of minor accumulation late Wednesday into Thursday.
Following Monday night into early Tuesday mornings threat of rain
and thunderstorms, a dry slot is expected to race northeastward
over the area as the occluding surface low shifts into IA. This is
expected to bring an end to the rain threat across the area late
Tuesday morning through the afternoon as our area becomes
entrenched in the breezy and mild warm sector of this low
following the early morning warm frontal passage. Breezy south-
southwesterly winds, gusting at times to 30 to 35 mph will set the
stage for near record warmth across the area. With 925 mb
temperatures forecast at near-record 12C to 13C values and such a
warm starting point to Tuesday from the system warm sector, we are
feeling confident in mid 60s into the area and possibly even
through the Chicago metro (GFS MOS guidance indicates a high of 65
for ORD!). See the Climate Discussion below for more on the
record daily warmth that could be reached.
The record warmth will come to a quick end into Tuesday night as
the systems cold front shifts across the area. Low-level cold
advection behind this front will take temperatures sharply down
into the 30s Tuesday night, and little to no recovery is expected
on Wednesday as the main upper low/trough begins to shift overhead.
Temperatures Wednesday will thus be a good 25 degrees colder than
they were on Tuesday! Forcing for ascent with the upper low will
provide good chances for snow showers in this cooler atmosphere,
especially late Wednesday into Thursday. While this does not look
to be a large amount of snow for the area, some minor
accumulations are possible. A short period of minor lake effect
snow may also result on Thursday across parts of northwest
Indiana as the winds along the back side of the system turn
northerly across Lake Michigan.
The weather pattern remains unsettled late week into next weekend
as shown by long term guidance. A Pacific-origin wave has some
semblance in the forecast late next week, but too early to add
much value from a guidance blend-provided chance of rain or snow.
KJB/MTF
&&
.CLIMATE...
There is a growing signal for highly anomalous warmth for the
daytime Tuesday, January 3. Forecast highs are currently slightly
above the record daily values shown below:
High Years
------------------------
Chicago 60 1950 & 1874
Rockford 57 1998
If 60 is reached, it would be the first January daily high of 60+
since January 29, 2013 for both Chicago (63) and Rockford (62).
MTF
&&
.AVIATION...
For the 00Z TAFs...
Primary aviation concerns through the TAF period are as follows:
* Expansion and persistence of ongoing low clouds and fog
primarily at RFD/DPA, and possibly ORD/MDW/GYY later tonight
* Brief opportunity for improvement from mid-morning to mid-
afternoon Monday before low cigs and visbys redevelop in the
evening
* Potential for a prolonged period of LIFR to IFR cigs/visbys from
Monday evening through at least daybreak Tuesday.
The Lower Great Lakes are within a low-level pressure col
extending to nearly 850mb leading to calm winds and little to no
thermal or moisture advection. With stagnant low-level moisture
and ever-so-gradually cooling temperatures, fog and low clouds are
expected to expand/redevelop this evening as already evident by
recent visibility and ceiling trends across north-central
Illinois (RFD is reporting a visibility of 1/8 of a mile at press
time). Even though forecast soundings show the low-level stable
layer becoming more shallow with time, conditions appear unlikely
to improve through the next 12 hours owing to the low-level
pressure col remaining locked in place. As a result, confidence is
relatively high in a prolonged period of LIFR to VLIFR conditions
primarily at RFD/DPA.
At ORD/MDW/GYY, confidence in low clouds and fog is lower since
clouds scattered out earlier this afternoon. Any IFR (or lower)
cigs and visbys may be dependent on the ongoing fog near RFD/DPA
expanding eastward. For now, opted to go with a persistence
forecast for the first 12 hours of the TAF (e.g. VFR) in favor of
watching trends for AMDs.
At least some opportunity for improvement in conditions at RFD/DPA
will exists after sunrise tomorrow morning owing to thermal mixing
both beneath and on top of the cloud layers and modest dry
advection from gradually-increasing northeasterly winds. However,
low-level warm air advection will gradually increase during the
afternoon hours as a surface low pressure system materializes in
the Plains. As a result, low clouds are expected to redevelop by
mid-afternoon and especially early-evening, giving way to IFR and
eventually LIFR conditions once again. Drizzle will become
increasingly common toward the end of the TAF period as a warm
front sharpens to the south of the terminals. An extended period
of LIFR to IFR cigs and visbys appears possible from tomorrow
evening through at least daybreak Tuesday.
Borchardt
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...Dense Fog Advisory...ILZ003-ILZ004-ILZ005 until 9 AM Monday.
IN...None.
LM...None.
&&
$$
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Area Forecast Discussion
National Weather Service Memphis TN
836 PM CST Sun Jan 1 2023
...New UPDATE....UPDATE... Issued at 812 PM CST Sun Jan 1 2023
Evening temperatures across the Midsouth range from the Middle 50s
to middle 60s. Dew points are mostly in the low to middle 50s
with a light south wind. Widespread, dense fog does not look as
likely tonight, but we will need to monitor development,
especially near the Alabama State line. Overnight lows should
fall into the middle 50s to around 60 degrees. The HRRR has been
consistent in the development of some light rain or drizzle late
tonight. Rain associated with a longwave trough moving across the
Plains should overspread the midsouth early tomorrow. The Storm
Prediction Center has included most of the Midsouth in a Slight
risk for severe thunderstorms in their day 2 convective outlook.
This is a typical high shear, low instability setup that is common
this time of year. A 40-50kt low level jet will help usher gulf
moisture across the Midsouth featuring dew points in the 60s. A
surface low will track to our north and an attendant cold front
will approach the Midsouth late tomorrow night or early Tuesday
keeping us in the warm sector of the storm most of the day
tomorrow and tomorrow night. Our highest chance of strong to
severe storms will likely be during the overnight hours as the LLJ
develops and shifts over the area. Thermodynamic support may
prove to be a major limiting factor. However, enhanced deep-layer
flow and 40-50+ kt of effective bulk shear should be sufficient
to support supercells. All modes of severe weather are possible,
but confidence is not high that we will see any severe storms.
Additionally, 2-3 inches of rain could result in localized
flooding. Expect clearing conditions from west to East Tuesday
with dry and cooler conditions returning by midweek.
30/Sirmon
&&
.SYNOPSIS...
Issued at 232 PM CST Sun Jan 1 2023
Mild temperatures and dry conditions are the main story for today.
Several locations have climbed into the low to mid 70s this
afternoon under mostly sunny skies. Warm and increasingly more
humid conditions will funnel into the Mid-South tomorrow morning
as a secondary warm front lifts across the region. Showers and
thunderstorms will begin tomorrow afternoon with the first round
of potentially strong to severe thunderstorms arriving early
tomorrow evening. Another round of more widespread convection will
roll into the Mid-South around midnight and continue through the
overnight hours into Tuesday. A few strong to severe thunderstorms
will accompany this line of activity. A minor flooding threat is
also possible as rainfall totals will approach 2 to 3 inches for
areas along and west of the Mississippi River. Dry and cool
conditions will build in behind the exiting system with a return
to near normal temperatures through the remainder of the workweek.
AC3
&&
.DISCUSSION...
(This evening through next Saturday)
Issued at 232 PM CST Sun Jan 1 2023
A great start to 2023 as temperatures are impressively mild this
afternoon. Several locations are already in the low to mid 70s
under mostly sunny skies. Temperatures are expected to remain mild
overnight as WAA continues in advance of a deepening trough over
the Rockies. Expect lows to fall only into the low 60s.
As WAA strengthens overnight, models are hinting at patchy fog and
light drizzle developing overnight and through late tomorrow
morning. A leading shortwave embedded in the main trough will lift
northeast into the Lower Mississippi Valley tomorrow afternoon.
This will kick off the first round of showers and thunderstorms by
late afternoon. A marginal severe threat will exist from late
afternoon through early evening as a batch of thunderstorms lift
northeast along the Mississippi River. A low CAPE and modestly
sheared environment could support a few instances of small hail
and gusty winds with this activity.
By late afternoon the main shortwave will be located over the
Central Plains and begin to take on a negative tilt. Decent height
falls will occur and steepen lapse rates over the Lower
Mississippi Valley. Simultaneously, the LLJ is expected to
strengthen and support a more organized severe threat across the
Mid-South. A likely broken QLCS will arrive in eastern Arkansas
before midnight and sweep across west Tennessee and north
Mississippi overnight. Even though shear will increase
substantially, MLCAPE will remain at or below 500 J/kg. This will
limit the overall threat, but a few instances of damaging wind
gusts and embedded circulations look possible given the kinematics
in place. The main threat appears to be damaging winds with a
secondary threat of short-lived tornadoes and isolated flash
flooding.
This threat will quickly push through the region by daybreak,
exiting northeast Mississippi by mid morning. The current SPC
outlooks handle this system well, accounting for both timing and
expected intensity of this event. Will continue to advertise the
two rounds of storms on messaging platforms and highlight the main
threat as damaging wind gusts.
The cold front will swing through the region by Tuesday evening.
This will knock temperatures back down to near normal for the
remainder of the week. Expect dry conditions and cool temperatures
to persist each day. Highs will mainly be in the 40s and 50s with
lows near freezing each night. The next system looks to arrive
next weekend as another cold front enters the region. Thunderstorm
chances look low with this system for now.
AC3
&&
.AVIATION...
(00Z TAFS)
Issued at 621 PM CST Sun Jan 1 2023
VFR conditions this afternoon will gradually deteriorate overnight
to MVFR and finally IFR by morning through the period. CIGs may
even get down to LIFR intermittently tomorrow morning. Pre-frontal
light drizzle should start making its way into the region before
any heavier showers; mentioned -DZ at all sites from early morning
through the afternoon. -SHRA should start up late afternoon from
west to east, with increasing thunderstorm potential later on in
the evening. The first wave of stronger convection with TSRA should
reach MEM by about 00Z tomorrow, but timing is still inconsistent
among CAMs.
Winds will stay generally southerly around 6-8kt through the
morning, picking up to 10-12kt tomorrow afternoon. As the front
gets closer tomorrow, southerly winds and gust potential will
increase. We could see gusts up to 30kt at MEM tomorrow evening.
LLWS will likely need to be added to at least the extended MEM
TAF for the 06Z cycle. Reduced visibilities (MVFR to IFR) due to
fog and/or showers/thunderstorms will be possible on and off
throughout the day tomorrow, especially at JBR.
CAD
&&
.MEG WATCHES/WARNINGS/ADVISORIES...
AR...None.
MO...None.
MS...None.
TN...None.
&&
$$
PUBLIC FORECAST...JDS
AVIATION...CAD
Area Forecast Discussion
National Weather Service Marquette MI
549 PM EST Sun Jan 1 2023
.SHORT TERM...(This afternoon and Tonight)
Issued at 135 PM EST SUN JAN 1 2023
As a low pressure over northern Lake Superior leaves into northern
Ontario this afternoon and evening, expect low level cloud cover to
stay across the area for the most part (save for a break near Lake
MI tonight). With delta-Ts getting close to 13C this afternoon into
tonight, we could see some weak lake-effect snow/drizzle/freezing
drizzle showers set up across the WNW wind snow belts. If
drizzle/freezing drizzle occurs, some additional slick spots and icy
patches could develop across the roadways; in that case, caution
should be heeded for the morning commute Monday. That being said,
the latest HRRR soundings show inversion heights getting up to
around -10C, so confidence is increasing that we will more than
likely see snow rather than drizzle/freezing drizzle this evening
and tonight. In addition, CAMs show a couple of convergent bands
setting up over the Keweenaw and near the Pictured Rocks National
Lakeshore this evening and tonight; if this occurs, it would not be
out of the realm of possibility for some isolated spots to get an
inch or two of wet snowfall as some moderate snowfall rates could be
seen at times underneath these bands. However, confidence is very
low as to where the higher snowfall amounts would occur (if they do
occur).
.LONG TERM...(Monday through Sunday)
Issued at 243 PM EST SUN JAN 1 2023
Given that there is still model uncertainty on timing of pcpn with
developing Plains storm moving into the Great Lakes region Tue-Wed,
have decided to hold off on any WSW headlines for now. Will issue a
SPS to highlight the potential for a period of heavy snow on Tue,
mainly for west and north central counties and maybe mention some
mixed pcpn/icing potential for south central and eastern counties.
Broad mid-level ridging downstream from the storm system developing
over the southern/central Plains will build across the UP on Monday,
resulting in dry conditions.
By Monday evening EPS guidance shows a sub-1000mb surface low near
the OK Panhandle that tracks northeast to just south of Des Moines,
IA by Tuesday morning. Most of the models and EPS mean show the
surface low moving slowly north into northern IA on Tuesday as the
low occludes, but the vertically stacked low starts moving east
Tuesday night. Comma-head stratiform precip will extend north of
surface low along and immediately north of the system`s warm front.
Precip will be forced by a combination of warm air advection up the
sloped frontal surface and frontogenesis acting on the boundary.
Ensemble means continue to indicate the area of stratiform precip
weakening as it enters our area, but a stripe of QPF >0.50" seems
probable across the west-north central UP. The large majority of
this QPF should fall between 12z Tue-06z Wed, but precip could start
a bit sooner far south and linger longer for the northeast wind lake
effect snow belts for north central counties. Model 850 mb thermal
fields and model fcst soundings now suggest the threat for any
sleet/freezing rain on Tue should stay confined to south central and
eastern portions of Upper Mi. Models continue to show a sharp cutoff
to northern extent of precip associated with a very dry Canadian
ridge north of this system, which could reduce QPF amounts for the
northern Keweenaw. ECMWF, and to lesser extent the 12Z NAM, show a
smaller area of heavy precip developing near the upper level low
late Tuesday night into early Wednesday. While most precip
associated with this feature misses us to our south, it could
enhance lake effect or shift into our area delaying the end of
precip so it should be monitored.
Synoptic scale precip should be lifting out by Wednesday morning as
the very dry Canadian high pressure ridge begins to sinks south into
the Great Lakes region. Models have trended cooler with the air mass
behind the low which would result in lake-850 mb delta-Ts now around
15-16C, but the very dry air mass/shallow CBL suggests additional
LES on Wednesday should be mostly light. Weak low-level convergence,
orographic lifting and favorable positioning of the DGZ within the
CBL could compensate for shallow inversion heights to squeeze out an
inch or two of fluffy accumulation for higher elevation locations,
especially in Marquette and Baraga counties.
Canadian ridging moves over the UP by Thursday morning with clearing
skies, light winds, and fresh snow cover seem like prime ingredients
for temperatures to bottom out across the interior. Raw NBM guidance
shows temps approaching 0F across the interior west with 10th
percentile guidance a few degrees cooler. Ridging continues Thursday
and Friday suggesting clear and chilly nights with sunny and
relatively comfortable days. Chances for pcpn next weekend looking
less certain as models and ensembles seem to depict a split-flow
pattern developing over the Western Great Lakes with perhaps more
ridging and drier weather for Upper Mi.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 548 PM EST SUN JAN 1 2023
Conditions will conitnue to be high IFR/low MVFR this period at all
sites.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 243 PM EST SUN JAN 1 2023
Generally light southeast winds of less than 20 knots this afternoon
into tonight becomes westerly to 20 knots Sun afternoon behind a
trough passage before winds diminish blo 20 knots and become light
and variable again into Monday. A Plains low moving in next week
results in northeast winds increasing to 25-30 knots from Tuesday
into Wednesday when gale force gusts to 35 knots are possible.
Northeast winds then weaken to 20-25 knots by Wednesday evening then
become light and variable blo 20 knots late Wednesday night into
Friday as the low moves east and is replaced by a high pressure
ridge from the west.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...TAP
LONG TERM...Voss
AVIATION...07
MARINE...Voss
Area Forecast Discussion
National Weather Service Morristown TN
908 PM EST Sun Jan 1 2023
...New UPDATE...
.UPDATE...
Issued at 904 PM EST Sun Jan 1 2023
Forecast for tonight generally looks to be on track. Temperatures
are generally running a bit lower than forecast, so will bump most
min temps down slightly with this update. Will also tweak sky and
hourly temps/dew points. Some fog is already starting to show up,
and this will bear monitoring to see how extensive it will
become.
&&
.SHORT TERM...
(This evening through Monday)
Issued at 312 PM EST Sun Jan 1 2023
Key Messages:
1. Clearing skies this evening will lead to patchy dense fog
overnight.
2. Additional clouds move in tomorrow ahead of our incoming storm
system on Tuesday, a few sprinkles possible across the southern TN
Valley late tomorrow afternoon.
Discussion:
Skies will continue to gradually clear this afternoon and evening.
This will allow patchy dense fog to develop overnight as low-level
moisture remains across the area. Though it`s possible that dense
fog may be more widespread than patchy so will have to closely
monitor trends through the night. Overnight lows will be mild with
temps in the lower to mid 40s for most areas.
Heights begin to rise tomorrow in response to the developing storm
system across the Great Plains. With the increasing southwest flow
across our area additional clouds begin to move in during the late
morning to afternoon hours. So expect a little bit of sunshine
after the morning fog burns off but then clouds begin to re-enter
through the day. Areas east of I-75 should see more sun compared
to areas west of I-75. A few sprinkles are possible late tomorrow
afternoon across the southern TN Valley as moisture and upper-
level divergence increase across the area. Highs tomorrow should
be a few degrees warmer, with max temps ranging from the low to
upper 60s.
&&
.LONG TERM...
(Monday night through next Sunday)
Issued at 312 PM EST Sun Jan 1 2023
Key Messages:
1. A strong storm system will affect the area Tuesday through
Wednesday, bringing widespread rainfall, gusty winds, and a few
thunderstorms.
2. Strong winds are expected in the Tennessee mountains and nearby
foothills early Tuesday morning through the afternoon.
3. A few storms could be strong to severe, especially in southeast
Tennessee.
4. Localized flooding is also possible in low-lying and poor
drainage areas that see repeated rainfall.
Monday Night through Thursday
At the start of the period, an increasingly negative trough will be
ejecting out of the Rockies with a ~997mb associated surface low.
These features will continue to progress northeastward towards
Missouri and Iowa with recent height rises and southerly flow
producing notable WAA across the eastern U.S. During this time, the
surface low will be an open wave with the associated warm front
initially south and west of the region and its cold front far to the
west. This will all lead to increasing PoPs Tuesday morning.
With upper divergence via direct ageostrophic vertical circulation,
a strengthening of the 850mb jet to 50 - 60 kts and the MSLP
gradient will create gusty winds area-wide. With the most recent
model data, the set up for mountain wave winds is lacking in the
magnitude of the gradient over the terrain (60 micrometers/km or
less). However, a jet of this magnitude with even some enhancement
is sufficient for confidence in high winds in the mountains. At this
time, it still remains somewhat borderline as to if widespread
warning criteria will be met, so no High Wind Watch was issued on
this shift.
There still remains uncertainty in the timing of convection with the
favorable upper-level divergence. The 18Z HRRR brings organized
convection into the region by the end of the run with the FV3
painting a similar picture with surface-based convection by the
afternoon. However, other mesoscale and global models are still
showing a slower progression more towards the evening and overnight
hours when dynamics are less favorable. In any case, deep-layer
shear values of 50+ kts support organized convection in a linear or
discrete form, depending on the exact direction of the flow. This
will also be combined with low-level SRH values of 150 to 250 m2/s2,
enhanced by the low-level jet. Ultimately, this jet will highlight
kinematic-induced damaging winds as the highest concern within any
storms. Tornado potential remains uncertain due to these continued
disagreements for instability being surface-based on Tuesday. With
all of these factors in mind, the last SPC outlook for Day 3 remains
in line with the current model guidance.
The threat for flooding still remains with indications for a slight
increase in overall rainfall totals from the recent update. Most
places will still likely be near 2" with northeastern areas likely
to see lighter values due to strong downsloping. Also, the latest
FFG shows that more than 3" in 6 hours or over 2" in 3 hours would
be needed for flash flooding. Nevertheless, a deep warm-cloud layer
and potential for multiple rounds of rainfall keep flash flooding
concerns, especially Tuesday evening through Wednesday morning. With
all of these factors in mind, messaging will be kept largely the
same with confidence expected to increase as the HREF moves into the
period. By Thursday, notable height falls and passage of the cold
front will usher in notably cooler temperatures with a few light
sprinkles or flurries possible.
Friday through Sunday
By the weekend, surface high pressure of 1,030mb or more will be set
up across the eastern U.S. with gradual height rises towards the end
of the period. This will keep the region dry with moderation on
Friday and Saturday with some indications of Pops returning by
Sunday. Values were kept at slight chance due to this limited
confidence.
&&
.AVIATION...
(00Z TAFS)
Issued at 521 PM EST Sun Jan 1 2023
The sky has mostly cleared, and it looks like there will be fog
development again tonight. Details are still not certain, but
right now it looks like CHA will drop to at least MVFR while TYS
is expected to drop to at least IFR and at TRI LIFR conditions
look likely later tonight. Conditions should improve to VFR during
Monday morning all sites, but at CHA it may only improve to MVFR
or briefly to VFR before MVFR cigs roll back in.
&&
.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN 47 68 58 69 / 0 10 40 100
Knoxville McGhee Tyson Airport, TN 44 66 53 70 / 0 0 30 100
Oak Ridge, TN 45 64 52 68 / 0 10 30 90
Tri Cities Airport, TN 40 65 49 69 / 0 0 10 80
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...NONE.
VA...NONE.
&&
$$
SHORT TERM...SR
LONG TERM....BW
AVIATION...
Area Forecast Discussion
National Weather Service Pendleton OR
238 PM PST Sun Jan 1 2023
.SHORT TERM...Tonight through Tuesday night...Overall fairly
benign weather continues into Monday morning as impacts remain
focused on fog/freezing fog around the Columbia Basin into the
foothill areas. It’s worth noting the development of a robust
stratus deck combined with modest up-slope flow could facilitate
some very light snow shower and/or flurry activity across the east
slopes of the Washington Cascades headed through Monday morning
as well; low confidence but only minor impacts should this
activity occur. Monday afternoon through Tuesday night a series of
two rather weak disturbances brings a chance of light snow to the
higher elevations, otherwise dry.
Tonight into Monday morning the interior Pacific Northwest remains
under the influence of a ridge of high pressure with a layer of
stratus and patchy fog already in place over the Columbia Basin,
the artifact of ample surface moisture, temperature inversion, and
subsidence aloft. Due to a high degree of confidence in additional
fog formation as depicted by guidance like the HRRR in combination
with freezing overnight temperatures, Freezing Fog Advisories have
been issued for the Kittitas Valley through the Yakima Valley into
the Columbia Basin in addition to the foothills of the Blue
Mountains. As the fog and stratus layer deepens overnight,
westerly to southwesterly flow between 900-800mb may facilitate
the development of light snow shower/flurry activity along the
east slopes of the Washington Cascades as well. Guidance varies
significantly in whether any of this activity actually develops,
but there appears to be the proper forcing/moisture, and enough
model consensus to add this slight chance(10-15%) to the
forecast. Fortunately, impacts appear very minor should it occur.
Monday afternoon the axis of the ridge shifts westward due in-part
to an approaching trough, although this feature will be rapidly
weakening as it moves onshore into Oregon and Washington.
Deterministic and ensemble guidance agree the vast majority of the
precipitation associated with the aforementioned feature dives to
our south Monday night and Tuesday but are do show some
discrepancies in how much is able to make it northward through the
CWA. The NBM in particular wants to keep much of the region dry
outside of just the Cascade crests, deviating from the consensus
of most model systems which paint light snow working through
central/northern Oregon, the Cascades, and the eastern Mountains.
The forecast was adjusted to match the latter, “wetter” scenario.
Overall, impacts don’t appear significant with just light snow
amounts expected, the highest of which(1-3 inches) occurs along
the crests of the Oregon Cascades; generally less than 0.5-1 inch
elsewhere. Tuesday evening a similar, weak upper-level shortwave
passes through the inland Pacific Northwest, containing even less
moisture compared to the one prior. Any chances for snow likely
remain confided to just the Cascade crests for this feature
leaving the rest of the region dry. It’ll be worth keeping an eye
on any model changes as we get closer and confidence in the exact
forcing and available moisture increases. A transitory shortwave
ridge preceding the next weather disturbance quickly arrives over
the region later Tuesday night into Wednesday morning. Schuldt/99
.LONG TERM...Wednesday through Sunday...The long term is expected
to be a somewhat progressive pattern as ridging breaks down across
the region, but models remain in disagreement on the tracking of
potential troughing and how much we will be affected by it in
terms of precipitation.
Deterministic guidance expects the following overall pattern: we
should remain under dry ridging to begin Wednesday, but a deep
upper-level low just offshore will push towards the coastline,
bringing a frontal boundary inland into Thursday. This will
tighten the pressure gradient and bring breezy winds, but these
winds should only reach advisory levels in strength, with gusts
to around 40 to 45 mph with moderate confidence (60%). This front
is expected to weaken and fall apart while the aforementioned low
lifts into the Canadian coastline, keeping the bulk of any
precipitation higher elevation in nature. Meanwhile, overall flow
will shift to southwesterly, promoting a warming trend that will
increase temperatures to above average to end the week. Model
divergence increases over the weekend, but at least some form of
troughing should continue over the region with mountain snow
continuing and possibly low elevation rainfall possible, while
another deep upper low begins to approach from the Gulf of Alaska.
Comparing ensembles versus the deterministic analysis, clusters
show the deep low`s approach during the middle to late portion of
next week, with then some form of troughing elongated over the
PacNW promoting the southwesterly flow expected to bring warmer
temperatures along with possible waves of light to occasionally
moderate precipitation. Primary differences are how much energy
from the troughing drops further south into California, which
could present less precipitation chances for the weekend. Overall,
there is moderate confidence in the above average temperatures,
around 40-50% at this time, with lower confidence in precipitation
and the timing of. Therefore, the NBM blend of a more broad swath
of precipitation is the accepted solution currently to account for
uncertainty. Goatley/87
&&
.AVIATION...00Z TAFs...FG/BR will continue to re-develop this
evening, affecting ALW/PDT, potentially PSC/YKM as well. CIGs and
VSBYs will drop considerably, possibly remaining LIFR overnight.
Otherwise, look for lowered stratus ceilings, with MVFR to IFR
conditions possible DLS/YKM/PSC, and light winds all sites less
than 10kts. Goatley/87
&&
.PRELIMINARY POINT TEMPS/POPS...
PDT 25 32 24 37 / 0 0 10 10
ALW 27 34 24 38 / 0 0 0 10
PSC 27 35 27 37 / 0 0 10 10
YKM 22 32 23 34 / 10 10 10 10
HRI 28 35 27 37 / 0 0 10 10
ELN 19 28 19 30 / 10 10 10 10
RDM 20 33 23 40 / 0 10 20 10
LGD 21 31 21 32 / 0 0 0 10
GCD 18 36 19 37 / 0 0 20 30
DLS 31 37 30 40 / 0 10 20 20
&&
.PDT WATCHES/WARNINGS/ADVISORIES...
OR...Freezing Fog Advisory from 8 PM this evening to noon PST Monday
for ORZ044-508.
Freezing Fog Advisory until noon PST Monday for ORZ507.
WA...Freezing Fog Advisory from 8 PM this evening to noon PST Monday
for WAZ028.
Freezing Fog Advisory until noon PST Monday for WAZ029.
Freezing Fog Advisory until noon PST Monday for WAZ026-027.
&&
$$
SHORT TERM...99
LONG TERM....87
AVIATION...87
Area Forecast Discussion
National Weather Service Pueblo CO
830 PM MST Sun Jan 1 2023
.UPDATE...
Issued at 823 PM MST Sun Jan 1 2023
Updated the forecast based on current trends and HRRR guidance.
Believe we will see a bit more fog and areas of light
drizzle/freezing drizzle east of the mtns/plains interface later
tonight and tomorrow morning. Seeder feeder process ongoing at
this time in the greater PPR, but mid upper levels fcst to dry out
later tonight and upslope will bring low clouds to the general
I-25 corridor region, especially areas N of the Raton Mesa. This
will bring a better chance of fog and drizzle to the above
mentioned areas. I have also bumped up snow amounts a slight bit
for the western sections of El Paso county. /Hodanish
&&
.SHORT TERM...(This evening through Monday)
Issued at 245 PM MST Sun Jan 1 2023
Key Messages:
1) Moderate to heavy snow expected to continue along the mountains
overnight and through tomorrow.
2) Freezing drizzle and light snow possible along the Palmer Divide
area, but high uncertainty still exist.
3) Dry in most other locations with overall near seasonal
temperatures.
Tonight and Tomorrow Synopsis... Active and impactful weather is
expected for the southern Colorado region tonight and through
Monday. Synoptically, a large trough is expected to dig and wrap up
around the four corners region and push off to the northeast over
Colorado. This storm system will bring a slug of Pacific moisture
along with it, causing heavy snow along the mountains, and possible
wintry precipitation along the lower elevations. More details about
expected forecast conditions and hazards are discussed below.
Tonight...
Precipitation: For precipitation, the greatest confidence for
precipitation development/maintenance remains over the mountains,
valleys, and eastern plains. Both deterministic and ensemble model
guidance are in relatively good agreement about moderate to heavy
snow persisting over the higher terrain and spreading across the
valleys this evening and overnight. As the trough approaches from
the west, strong and persistent southwesterly flow will maintain
orographic forcing, the strongest of which will be over the San Juan
Mountains given better orientation of the winds. With the increasing
synoptic forcing and persistent orographic forcing, along with the
Pacific moisture advecting over southern Colorado, moderate to heavy
snow will continue along the mountains overnight, with the heaviest
along the San Juan Mountains. Snowfall rates are likely to be
between 1-2 inches per hour overnight along the San Juan Mountains.
Across the mountain valleys, such as the San Luis Valley (SLV) and
Arkansas River Valley, precipitation is expected to increase this
evening as the trough begins to edge its way over western Colorado
and help to push precipitation off of the higher terrain. For areas
around the Arkansas River Valley, all snow is expected, with light
to moderate snowfall amounts expected. The SLV however is expected
to mostly experience a rain/snow mix as surface temperatures hover
right around and just above freezing for the majority of the night.
As temperatures finally drop late in the night/early morning, a
transition to mostly snow is expected within the SLV, but
precipitation coverage wills start to drop at that time, as the
trough starts pushing over and drier air behind the system starts
advecting into the region. At lower elevations, drier conditions are
expected. As the trough starts pushing over the region, an elevated
drier and warmer layer of air will begin to wrap around the eastern
periphery of the system. This will limit any major precipitation
chances for the plains. With that said though, an isolated rain
shower or two will be possible given modest upglide forcing from
this elevated layer. The area of greatest uncertainty at this time
is along the El Paso County/Palmer Divide areas. Model guidance has
struggled with trying to resolve this region and the possible
precipitation development along these areas, along with model
guidance now starting to trend toward a more disorganized and slower
low as compared to previous guidance. Given that model guidance is
still struggling to resolve things less then 24 hours out from
possible impacts, this is leading to a high-impact-low-confidence-
event (HILCE). With all of that said, here are the current thoughts
about the evolution of things. As the trough starts to approach and
edge its way over Colorado overnight, the aforementioned drier and
warmer layer will start to nudge its way further north and over the
area of concern. This drier and warmer layer of air will help to
limit any major precipitation development just like the eastern
plains. However, a shallow cold airmass will slowly drift into the
southern Colorado region overnight. As this takes place, winds at
the surface will take on a more easterly component and modest
surface upsloping will develop along the Palmer Divide region. Given
this, shallow precipitation is expected to develop. During the
evening/early overnight hours, the warmer layer aloft would be
expected to melt any liquid from the precipitation, and light
freezing drizzle will be possible given the below freezing surface
temperatures. Then progressing through the night, colder, but still
drier, air moves in and any precipitation that is present would be
expected to transition to light snow.
Temperatures... For much of the region, overnight temperatures will
remain above average. Like previously alluded to, a weak and shallow
cold front will sag southward Sunday evening. This will help to
bring in modestly cooler air, but increasing cloud cover will limit
the amount of radiational cooling that could take place, and
temperatures will not drop as much as they would otherwise. Given
this, most across southern Colorado will remain 10-20°F above
average for this time of year.
Tomorrow...
Precipitation: For the day Monday, active weather is expected to
continue. The trough is anticipated to be pushing across the
Colorado region and begin moving to the northeast throughout the
day. This will keep synoptic and orographic forcing in place across
southern Colorado, though moisture will start to decrease as drier
advects in behind the system. Given this, precipitation along the
mountains and valleys will decrease in coverage through much of the
day. With that said though, snow, more scattered in nature, is
expected to continue along the mountains given the forcing
mechanisms in place. As the trough does pass over the region, and
lapse rates steepen from cooler air associated with it, modest
instability is expected to develop. Given this instability,
transient convective snow bands will be possible along the
mountains. As for the eastern plains, they will continue to remain
dry throughout the day. An isolated shower or two is possible though
as the ascent from the dry/warm layer continues over that area.
During the later afternoon, as the trough and associated low move to
the northeast, surface winds will become more northerly behind the
system. These surface winds will lead to more upsloping along the
Palmer Divide, and that, along with better synoptic support, will
allow for isolated to scattered light snow showers to develop along
northern El Paso County.
Temperatures: For the daytime, a wide varying set of temperatures
are expected. Areas further west will experience more westerly winds
and compressional warming. This will lead to slightly above average
temperatures across western areas. Across parts of the plains,
partially clearing skies will help to warm much of this area to
around average for this time of year, with the warmest temperatures
in the far southeastern plains, where more clearing is expected from
the dry slot. Areas further north in the plains will remain near to
slightly below average given the weak cold front and cloud cover
hindering any major warming.
.LONG TERM...(Monday night through Sunday)
Issued at 245 PM MST Sun Jan 1 2023
Key Messages:
1) Chilly Tuesday behind departing system then a warming trend.
2) Pacific storm system brings snow mainly to Continental Divide
region around Friday and Sunday into Monday.
.Monday night and Tuesday...Latest models runs continue the idea
of cyclogenesis in western Kansas Monday evening due to the
shortwave, current off the coast of the Baja Peninsula, moving
into the region. Some models hint that some light precipitation
may move into the eastern plains Monday evening. Currently,
amounts look to be light, if any precipitation moves into the the
region. On Tuesday, chilly northwest flow develops over the
region. Orographics, along with a weak disturbance, will result in
some occasional light snow near the Continental Divide region.
.Wednesday and Thursday...Shortwave ridge builds into the region.
Northwest flow may keep some light snow over the Sawatch range on
Wednesday with little if any accumulations. Warming trend
develops with highs reaching above seasonal values by Thursday.
.Friday through Sunday...Ensemble means have one Pacific trough
passing over the region around Friday with another system
starting to approach the region on Sunday. The NBM and ensemble
means suggest mild weather continuing into the weekend with best
chances for snow near the Continental Divide. --PGW--
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 245 PM MST Sun Jan 1 2023
KALS: Precipitation will be moving off of the mountains this
afternoon and entering the vicinity of the terminal by 23Z. A
rain/snow mix is expected to set in by about 03Z, with quickly
lowering cigs and cool fog limiting visibility at times, bringing
things down towards IFR or worse. Precip type switches to snow by
about 06Z, and with winds expected to lighten overnight fog is
anticipated in the valley through the end of this forecast period.
KCOS: The incoming system will become less organized as it passes
through, giving us a mixed precipitation bag over the next 24 hours.
Showers will move near the TAF site by 03Z, and precipitation will
begin as a cool rain/snow mix with quickly lowering cigs and
decreases to visibility. Currently, a brief period of FZDZ is
expected to pass by the terminal between 08-10Z tonight, before
becoming primarily snow. After precipitation ends early tomorrow
morning, lingering low stratus and potentially fog/mist will last
through the end of this forecast period.
KPUB: VFR conditions are generally expected through 24 hours. Some
precipitation may drift close to the terminal after about 05Z, which
will lower cigs into the MVFR range closer to the end of the
forecast period. Winds will be mostly light and should maintain an
easterly component throughout
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 5 PM MST Monday for COZ058-059-061-
084.
Winter Storm Warning until 5 PM MST Monday for COZ060-066-068.
Winter Weather Advisory until 11 AM MST Monday for COZ067-072-
073-075.
&&
$$
UPDATE...HODANISH
SHORT TERM...SIMCOE
LONG TERM...PGW
AVIATION...GARBEROGLIO
Area Forecast Discussion
National Weather Service Raleigh NC
1033 PM EST Sun Jan 1 2023
.SYNOPSIS...
High pressure will build across and offshore the South Atlantic
states through Monday night. A cold front will approach from the
west mid-week.
&&
.NEAR TERM /THROUGH TONIGHT/...
As of 1030 PM Sunday...
Dense Fog Advisory in Effect through 10 AM Monday for most of
central NC...
Aloft, a broad ridge centered across Cuba was generating zonal flow
across central NC. At the surface, a 1021 mb high off the SC coast
was maintaining weak southwesterly flow across our area, with
dewpoints in the mid 40s to low 50s. Mostly clear skies were helping
temps to quickly lower to the dewpoint temperatures, and with
residual moisture across the region, many areas are developing dense
fog. A Dense Fog Advisory was issued for portions of the Piedmont
and Sandhills for visibility of one-quarter mile or less through 10
am Monday morning. Areas of the Coastal Plain and NE Piedmont may
need a Dense Fog Advisory if fog continues to develop across the
region. Fog will be slow to clear/lift Monday morning. Overnight
temperatures will dip into the mid-40s.
&&
.SHORT TERM /MONDAY AND MONDAY NIGHT/...
As of 200 PM Sunday..
Monday will likely start similar to the previous couple days with
fog, possibly dense in spots, slowly rising to a low overcast
through much of the morning hours. Monday morning an upper level
closed-low will be positioned over the Four Corners region assisting
in the amplification of a downstream ridge axis over the Southeast.
The ridge axis will continue to build over the Mid-Atlantic through
Monday before shifting offshore late Monday night into Tuesday. At
the surface, broad high pressure will be draped along the Carolina
coastline Monday morning before slipping offshore during the
afternoon/evening hours as low pressure pushes into the central
Plains.
The persistent airmass characterized by above normal temperatures
and remnant low-level moisture will largely remain through Monday
night favoring a redevelopment of fog and very low overcast over
much of central NC. The climatologically favored areas will be over
the northwest and southern Piedmont where confidence is highest, but
patchy fog will likely still be an issue across central NC Monday
night into Tuesday morning. Highs will be difficult to pinpoint
Monday afternoon with any confidence as locations stuck in the low
overcast will likely remain in the 50s while places that can manage
to scatter out may shoot up into the mid/upper 60s. The return of
southerly flow and redevelopment in low overcast will keep lows in
the upper 40s to low 50s (roughly 20 degrees above normal).
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
As of 210 PM Sunday...
Tuesday and Wednesday: Medium-range model guidance starting to come
into better agreement. Aloft, the mid-Atlantic will be situated
between the sub-tropical ridge to the southeast and low to the
northwest lifting from the central Plains to the upper MS Valley
Tue/Tue night. The ridge will get pushed further east over the
Atlantic as the low slowly migrates eastward into the OH Valley with
its attendant trough extending south to the Gulf. Gulf moisture
advection will increase Wed/Wed night, with the moist axis extending
north-northeastward through the Southeast and mid-Atlantic. At the
surface, central NC will be situated between high pressure to the
east over the Atlantic and the approaching frontal system to the
west. A warm front will lift northward through the area on Tue/Tue
night ahead of the approaching cold front, though the timing varies
between the models. The southeasterly return flow around the high
will advect Atlantic moisture into the area Tue/Tue night, ahead of
the arrival of the more Gulf moisture immediately ahead of the front
Wed/Wed night. A period of some isentropic lift driven rain across
the area is possible prior to the warm front lifting through and the
rain becoming more convective in nature. The best chance for heavy
rain and thunder will be immediately ahead of the front Wed/Wed
night. Although fropa timing is not quite solidified, generally the
cold front should be through central NC Thu morning. Temperatures
will be significantly above average. Expect highs in the mid 60s to
mid 70s. Lows in the mid 50s to low 60s Tue night will likely
decrease for Wed night in the wake of the front. How much of a
decrease will depend on fropa timing, but for now expect lows Wed
night in the mid 40s NW to around 50 degrees SE.
Thursday and Friday: Aloft, the upper low will swing through the OH
Valley and into the mid-Atlantic Thu/Fri, then lift northeast toward
the New England coast/northern Atlantic Sat. At the surface, the
cold front will continue to progress eastward and well out over the
Atlantic Thu through Sat as Canadian high pressure drops south
through the Plains then drifts eastward through the Deep South and
Southeast, into the mid-Atlantic. Temperatures should decrease to
closer to normal by Fri.
For the Weekend: Forecast confidence decreases quite a bit, due to
model solutions diverging with the track of a trailing upper
low/wave. The trailing upper wave/low will track eastward from the
northern/central Plains, through the upper/mid MS Valley and into
the Great Lakes or OH Valley while a weak ridge progresses eastward
through the Southeast and mid-Atlantic. The track of the upper
low/wave will impact chances for precipitation over the weekend, so
for now will keep the forecast dry until there is better model
agreement/consistency.
&&
.AVIATION /00Z MONDAY THROUGH FRIDAY/...
As of 730 PM Sunday...
24-hour TAF period: With a moist boundary layer and calm winds as
high pressure sits over the region, widespread dense fog and LIFR
stratus are expected to develop after midnight tonight across the NW
Piedmont (including INT and GSO). Fog is also expected around FAY,
but it will likely occur later and confidence in its development
there is a bit lower. The lowest chance of fog is in the NE
(especially RWI) where high-res guidance (including the RAP, HRRR
and GLAMP) shows less fog than before, a trend that is reflected in
the latest TAFs. Fog will be slow to lift tomorrow, lingering until
the mid to late morning, especially at INT and GSO. Winds will be
from the south/southwest tomorrow and light (5 kts or less).
Looking beyond 00Z Tuesday: Given no change in the residually moist
airmass that will linger across the South Atlantic states,
redevelopment of LIFR fog and/or low overcast will likely occur once
again Monday night. Strong swly flow and transport of anomalously
moist air ahead of a cold front will produce widespread
rain/isolated storms and sub-VFR conditions in cntl NC Tuesday night
and Wednesday.
&&
.CLIMATE...
Record Temperatures for Wednesday January 4:
SITE RECORD MAX RECORD HIGH MINIMUM
GSO 74/2005 57/1950
RDU 76/2005 58/1950
FAY 77/2004 60/2004
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
Dense Fog Advisory until 10 AM EST Monday for NCZ007-021>025-038>042-
073>077-083>086-088.
&&
$$
SYNOPSIS...MWS/JJT
NEAR TERM...JJT
SHORT TERM...Swiggett
LONG TERM...KC
AVIATION...Danco/MWS
CLIMATE...RAH
...Update to aviation forecast discussion...
.DISCUSSION...
Issued at 206 PM CST Sun Jan 1 2023
- There will be chance of rain Monday with a few thunderstorms into
Monday evening.
-The rain may change over to a wintery mix of precipitation late
Monday night across north central KS before before ending Tuesday
morning.
Early this afternoon an amplified upper level trough was located
across the Western US with the main upper jet digging into the
northern Baja CA region. A broad upstream H5 ridge was noted across
the southern and central Plains. At the surface an area of low
pressure was located along the TX/OK/KS border with a warm front
extending east-northeast across southern KS.
Tonight through Tuesday:
The upper level trough will amplify as it lift northeast out of the
southwestern US into the central high Plains. A low-level jet will
develop later Tonight and advect residual Gulf Moisture northward
into eastern KS Monday morning. As the WAA increases low stratus
with areas of drizzle will develop across OK this evening and spread
northward into eastern KS through the early morning hours of Monday.
As the DCVA increase ahead of the H5 trough axis, combined with
anisotropic lift, will cause widespread rain to develop across the
eastern counties of the CWA. The warm sector will destabilize enough
during the afternoon hours for 200 to 500 J/KG of MUCAPE combined
with effective shear over 40 KTS, a few of the elevated
thunderstorms may produce small hail Monday afternoon into the early
evening across the eastern half of the CWA. At this time the surface
based severe thunderstorms will remain southeast of the CWA. High
temperatures will reach the mid 50s to lower 60s across the east
central KS. The north central counties will only reach the mid to
upper 40s as the surface warm front will only lift northwest of an
ABI, to MHK, to HIA line. The front will push southeast across the
remainder of the CWA as the surface low deepens ans shifts northeast
across far northeast KS into northwest MO Monday evening. As the
upper low tracks northeast into northern IA by 18Z TUE the precip
should lift northeast of the CWA during the early morning hours of
Tuesday. The cold air advection may cause temperatures to drop below
freezing as the precip exits north central KS, which may cause a
wintry mix of rain changing to freezing drizzle and snow. At this
time amounts look to be very light but if there is a couple hours of
freezing drizzle and snow across the north central KS, then there
may be a few slick spots on area roadways Tuesday morning. Total QPF
Monday into Monday night will range from 0.4 inches in the far
eastern counties to only 0.10 inches in the far southwest counties.
Any elevated thunderstorms that develop may provide isolated higher
amounts.
It will feel cooler on Tuesday as the surface CAA increases and
highs only struggle back into the lower to mid 40s across east
central KS with mid to upper 30s across north central KS.
Tuesday night through Thursday:
The upper level trough will amplify
as it digs southeast from northern IA into the OH River Valley, then
east into the mid Atlantic states. The mid and upper level flow will
become northwesterly as a surface ridge of high pressure builds
southeast across eastern KS. High temperatures will continue to be
cool with lower 30s northeast to the upper 30s across the southern
counties of the southern CWA.
Thursday night through Sunday:
Split flow will develop across the North America, with a northern
stream ridge developing across the northern Plains, and the
southern stream of the upper level jet will become more zonal. A
weak H5 trough will move east cross the central Plains Friday
night and I cannot rule out a few showers into Saturday morning.
High temperatures will gradually moderate through the 40s by next
weekend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 521 PM CST Sun Jan 1 2023
Have backed off a bit on the onset of limiting conditions and the
extent of the limitations at this point based on less humid
boundary layer at issuance time and belief the HRRR and RAP are
too low with visibilities and influencing blends too extreme.
IFR conditions are still expected however for the majority of this
forecast.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
DISCUSSION...Gargan
AVIATION...65
Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
703 PM MST Sun Jan 1 2023
.UPDATE...
Issued at 656 PM MST Sun Jan 1 2023
00z KUNR sounding depicts a modest dry layer below below 600mb,
which as expected, is impeding the progress of precipitation
moving northeast out of southeast WY/NE panhandle. Wasted lift,
but this is accounted for in the forecast tonight. More concerning
is the 00z HRRR trends that tighten the northern edge of the main
snow band, suggesting lesser amounts from Spearfish to Philip,
including parts of Pennington County. HRRR still shows upslope
enhancement over the eastern Foothills, however. The secondary
band of strong frontogenesis that occurs over south-central SD
Monday night suggests higher snow amounts than current forecast
may be needed. Don`t anticipate major changes in the forecast this
evening, but will be watching satellite/radar developments as
well as how they mesh with the entire 00z suite of guidance.
&&
.DISCUSSION...(This Evening Through Sunday)
Issued at 218 PM MST Sun Jan 1 2023
Upper trough crossing the central/southern Rockies this
afternoon, will eject into the region, supporting widespread snow
across most of the area Monday. Two rounds of LSA and associated
precip on track with the first round tonight into Monday, and the
main round of lift expected Monday night across scentral SD. The
main trend of all hires model data has been to tighten the precip
gradient across the FA and shift the heaviest band of snow south
in line with the strongest FGEN. This has resulted in slightly
lower snowfall totals on the northern end of the precip shield,
mainly affecting areas along and north of I90 due to dry air
entertainment from a building high to the north. There remains a
weak upslope enhancement signature in the eastern BH foothills,
but given concerns on dry air, strong sink flow NW of the main
FGEN band, unfavorable profiles for efficient crystal production,
and weak easterly flow, upslope enhancement is expected to be
limited. Hence, Pennington County could potentially struggle to
reach warning criteria, esp if strong subsidence develops north of
the main FGEN band. The only change to the hazards was to add
southern Campbell County to the warning given continued high probs
for warning levels from Wright south. First band of snow will
shift north Monday with a potential lull/downtrend in snow most
areas Monday afternoon. Second/main round of lift per impressive
FGEN will push into scentral SD Monday night and support heavy
snow over scentral SD. Deep DGZ lift and strong forcing will allow
for 1-2 inch (or more) snowfall rates just south of the ll FGEN
max with some places expected to see well over a foot there. NW of
the FGEN band, snow is expected to be light, potentially stopping
in some areas given expected strong subsidence, limiting snow
amounts further. Still expecting breezy northerly winds Monday
night into Tues over scentral SD, with some blowing snow possible,
although not too terrible. Snow will shift east and end Monday
night across the area west to east, possibly lingering over
scentral SD into Tues morning. Not much cold air behind this
system with seasonal temps the remainder of next week and dry
conditions until next weekend when another trough is progged to
cross the region.
&&
.AVIATION...(For the 00Z TAFS Through 00Z Monday Evening)
Issued At 419 PM MST Sun Jan 1 2023
Conditions will deteriorate to MVFR/IFR from southwest to
northeast tonight. Widespread MVFR/IFR conditions expected Monday.
Snow will spread northeast tonight into Monday with areas
IFR/LIFR conditions Monday, especially from the Black Hills to
KICR.
&&
.UNR WATCHES/WARNINGS/ADVISORIES...
SD...Winter Weather Advisory from midnight tonight to midnight MST
Monday night for SDZ024-025-072-073.
Winter Storm Warning from midnight tonight to 5 AM MST Tuesday
for SDZ026-028-031-042>044.
Winter Storm Warning until 5 AM MST Tuesday for SDZ027-029-030-
041-074.
Winter Weather Advisory from 2 AM Monday to 5 AM MST Tuesday for
SDZ032.
Winter Storm Warning from 3 AM Monday to noon CST Tuesday for
SDZ046-047-049.
WY...Winter Weather Advisory from midnight tonight to midnight MST
Monday night for WYZ057.
Winter Storm Warning until 11 PM MST Monday for WYZ055.
Winter Weather Advisory until 11 PM MST Monday for WYZ058.
&&
$$
Update...Helgeson
DISCUSSION...JC
AVIATION...Helgeson
Area Forecast Discussion
National Weather Service Las Vegas NV
749 PM PST Sun Jan 1 2023
.SYNOPSIS...Rain and snow showers will dissipate tonight as an
upper low slowly shifts east away from the area. An active weather
pattern will continue through the week keeping temperatures cool and
bringing additional chances for precipitation.
&&
.UPDATE...Continuing to deal with the upper level low that has been
plaguing the southwest US since last year (haha).
Satellite and mesoanalysis through the evening showed a broad area of
clouds and precipitation rotating around the center of the low, now
likely situated over western Arizona base on cloud circulations.
Widespread clouds and showers were noted through the evening in
eastern Nevada through southeast California into western Arizona.
Further west, it has dried out as the back end of the forcing has
moved in and dry northwest flow and upper level subsidence has taken
over.
The low is expected to slowly move east through the night. This will
shift the main area of clouds and precipitation further east as
well, albeit slowly. Base don where the better forcing should line
up, the highest potential for continued showers overnight will be in
western and northern Mohave County. While the heaviest precipitation
should be winding down in the next hour or two, will need to watch
for residual impacts due to rain in northern Mohave County into
northeast Clark County as the ground is saturated and responses in
local stream gages have been noted. Additional rainfall may result
in minor flooding in spots, especially in the next few hours before
the main axis of moisture and forcing moves east of the area. The
latest models have slowed down the eastward progression of the low
and thus have slowed down the precipitation exiting. Latest trends
would suggest that precipitation may continue in northeast Mohave
County until about 12Z. Updated precipitation chance for tonight to
reflect this trend using the best performing models through the
evening. QPF after 10pm should be light with 6-hourly amounts
remaining under 0.25 inches at all locations after 06Z tonight. Snow
levels will fall to around 3000ft behind the system, but that should
be displaced from where precipitation should be ongoing in the warm
sector. Snow levels where precipitation is expected should remain
around 5000-6000ft through the night, and no changes in the snow
amount or impacts were made from the previous forecast with a 1 to 3
inches possible tonight in the terrain of Mohave County and northern
Lincoln County.
Winds were the other lingering issue with this system through the
evening. As the low has slowed down, winds have been able to over
perform in Nye, Inyo, and Esmeralda County as well as the Yucca
Valley region of San Bernardino County. With continued northerly
flow expected in this area through much of the night, and a decent
850mb jet of 30-40KT noted on mesoanalysis and model output,
increased winds through this region for the overnight period. Not
expecting widespread wind impacts overnight, though some minor wind
impacts due to wind gusts up to 40 MPH are possible in Esmeralda and
western Nye county through the morning.
--Nickerson--
&&
.Previous Discussion...1245 PM PST Sun Jan 1 2023
.DISCUSSION...Through next Sunday.
Wet and white start to the New Year. Still more to come through
tonight as current upper low over the area slowly migrates east.
Not expecting impactful snowfall or winds to continue overnight so
will allow our current products to expire on schedule at 4 pm. Have
seen some pockets of heavy rain in the lower Colorado River Valley
and southern Mohave County associated with isolated thunderstorms
that developed in region of MUCAPE of 100-500 J/KG. Don`t anticipate
thunderstorms to persist much past sunset as HRRR indicates CAPE
values decreasing across southern Mohave County and shifting east
into the Phoenix area. Light rain and snow showers in southern
Nevada and eastern California will linger into the evening before
dissipating, while it will take much of the night for showers to
finally dissipate in Mohave County in an area of subsidence behind
exiting trough.
After a brief break Monday, fast moving impulse will bring chances
for rain/snow to the region mainly Monday night - Tuesday. AR with
this feature skirts to our south so precipitation will be light
during the period.
Ensemble solutions suggest amplification of a stronger ridge over
the Great Basin Wednesday ahead of a stronger trough over the
eastern Pacific. Those ensembles tending to show core of the energy
lifting northeast and weakening as it moves inland. However, AR
associated with this trough will impact California/southern Sierra
the most with again lighter precipitation amounts making it in the
Great Basin and Mojave Desert. May need winter weather headlines in
time for the southern Sierra and White Mtns.
After another brief break Friday, parade of storms from the Pacific
sends another one our way next weekend. Can`t complain as that all
important snowpack in the Colorado Basin continues to build.
Temperatures will be at or slightly below normal through the period.
Intervals of gusty winds possible at times.
&&
.AVIATION...For Harry Reid...A cold front is still expected to push
through the Las Vegas Valley this afternoon, likely arriving at the
terminal between 2130 and 2230Z. As the front passes, an increase
in northwesterly winds and the chance of a few additional light
showers continuing into the evening can be expected. CIGs will also
likely decrease to around 4kft for a few hours behind the front.
Conditions will improve overnight, and lighter winds below 10kts are
expected tomorrow morning and afternoon.
For the rest of southern Nevada, northwest Arizona and southeast
California...While the main band of showers has now moved east of
the TAF sites, additional scattered showers will still be possible
into this evening at the Vegas Valley and Colorado River Valley
sites. A few embedded thundershowers are also possible near KIFP
and KEED through late afternoon. Winds at most sites will develop
or maintain northerly components this afternoon and evening as a
cold front moves across the area. The exception will be KDAG, where
westerly winds are forecast to persist. Improving CIGs and
decreasing winds are expected overnight and Monday as the storm
system shifts to the east.
&&
.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any significant weather or impacts according to standard operating
procedures.
&&
$$
DISCUSSION...Pierce
AVIATION...Planz
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