Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/18/25
Area Forecast Discussion
National Weather Service Cheyenne WY
948 PM MDT Thu Apr 17 2025
.EVENING UPDATE...Main changes tonight were mostly to
precipitation, increased probs across the region based on
ongoing activity, and also some adjustments to overall
accumulations due to that. Winds and temperatures are running in
fair agreement otherwise, so no major changes to these either.
.KEY MESSAGES...
- An impactful winter storm is expected today through Friday.
Widespread accumulating snow is likely. Winter Storm Warnings
and Winter Weather Advisories are in effect for portions of
southeast Wyoming and western Nebraska.
- Remaining unsettled during the weekend through early next week
with chances of showers each day.
&&
.SHORT TERM /THROUGH FRIDAY NIGHT/...
Issued at 253 PM MDT Thu Apr 17 2025
Based on observations, the surface cold front has already moved
through most of the CWA. Temperatures behind the front are colder
with a more northerly component to the wind. Radar shows
precipitation increasing in coverage behind the front. This trend
will continue through the afternoon hours with rain continuing to
make the switch over to snow as the front aloft traverses the CWA.
Cannot rule out a few rumbles of thunder in showers ahead of the
cold front aloft.
For the most part, the forecast remains on track. The potent upper-
level trough responsible for the cold front and precipitation will
continue to push into Wyoming today and be out of the CWA by
Saturday. Accumulating snow is still expected throughout southeast
Wyoming and most of the Nebraska panhandle, with strong
frontogenesis and upslope being the main drivers of snowfall
accumulation. Of course, given the time of year, factors like sun
angle and how quickly the ground can cool off after a few days of
above average temperatures will play a role in snowfall totals. Snow
likely will not start accumulating until late afternoon or after
sunset.
Diving deeper into this system, a lot of the dynamics favor areas of
heavy, banded snow and orographic upslope flow. The GFS shows large
areas of very strong mid-level frontogenesis colocated with areas of
QPF and saturated DGZs. The main area of concern for this set-up
will be west of the Laramie Range, where Winter Storm Warnings are
in effect. This will likely lead to heavy snow at times, especially
late Thursday afternoon through Friday morning. Snow accumulations
in most of the Warning areas will be between 6 and 12 inches. East
of the Laramie Range, orographics and upslope will play a larger
role in snowfall accumulation. North to northeast winds behind the
cold front will be favorable for orographic lift in both the North
Laramie Range and Pine Ridge. Cities along the US-20 corridor,
especially in Wyoming can expect 5 to 10 inches of snow. These
locations are in a Winter Storm Warning. Pine Ridge areas in
Nebraska could see up to 6 inches. The North Laramie Range will be
in a prolonged period of moist upslope flow, so this area is likely
to see the highest snowfall totals in the CWA for this event. Other
areas to watch will include the South Laramie Range and foothills as
well as the Cheyenne Ridge. The Cheyenne Ridge also favors upslope
flow in northerly flow so areas between Wheatland and Cheyenne are
currently in a Winter Storm Warning for 6+ inches of snow. Ensemble
means from the GFS and ECMWF are fairly in line with these totals.
Later shifts will have to keep an eye on Laramie, Rawlins,
Wheatland, and Cheyenne. Hi-Res guidance from the HRRR has increased
snowfall totals across the area overnight. Will have to keep an eye
on these areas to see if Winter Weather Advisories will need to be
upgraded. Models keep consistently showing Laramie getting Warning
level amounts, however, Laramie will be downsloping through the
majority of the event. If strong frontogenesis can overcome
downsloping, then Laramie could see over 6 inches of snow. Lastly,
gusty winds at Rawlins overnight could cause poor visibility with
blowing snow. It is possible that visibility could drop below a
quarter mile for a prolonged period of time, prompting the need for
a short fuse Blizzard Warning. Opted to hold off at this time as
models have trended winds downward a bit compared to previous runs.
Snow will continue through most of the day Friday, but will
gradually taper off throughout the day from north to south. Minimal
accumulations are expected after sunset on Friday, however there
could be a few lingering snow showers overnight. Behind the front,
temperatures will be much colder for Friday. High temperatures will
struggle to reach freezing for much of southeast Wyoming, with low
40s expected for the panhandle. Cold temperatures will continue into
Friday night with teens and 20s expected across the area.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
Issued at 350 AM MDT Thu Apr 17 2025
Deterministic models and ensembles in reasonable agreement this
weekend and next week...showing an unsettled weather pattern
through the extended. Thankfully, it is expected to be more
spring-like with milder temperatures but with a daily chance of
showers and some thunderstorms.
For the weekend, all models indicate the beginning of a long wave
pattern shift as a broad upper level trough replaces the general
mid to upper level ridging that has persisted across the western
United States over the last 4 to 6 weeks. Still remaining on the
cool side this weekend, although models show a slow warming trend
heading into Sunday. Northerly flow aloft will remain over the
area Saturday and Saturday night with the upper level flow backing
into the west on Sunday. Remaining chilly on Saturday with highs
struggling to reach 40 degrees for most of southeast Wyoming,
and 40s to near 50 below 4500 feet. Off/on rain and snow showers
are possible Saturday, but not expecting any additional snow
accumulation outside of the mountains. Sunday looks somewhat
drier with moderate downslope westerly wind expected. It will
also be milder on Sunday with temperatures near normal for mid
April (50s to low 60s).
Next week looks mostly unsettled as a long wave trough settles
over the eastern Pacific and western third of the United States.
This will result in a progressive storm track across Wyoming
and the adjacent high plains of Colorado and western Nebraska.
Although models are in very good agreement with the overall
pattern, there are significant timing and placement differences
between individual models relating to shortwave disturbances
and frontal placement. These differences do show up in the
latest ensemble guidance with relatively high spreads in surface
moisture/PWAT, cloud cover, and precipitation chances. The more
potent disturbances are forecast to move over the forecast area
Monday night, Wednesday, and again on Thursday as a train of
Pacific storm systems move onshore between Oregon and central
California. The most notable weather event may be Tuesday night
and Wednesday across southeast Wyoming, with the GFS the most
aggressive model...showing a stationary front along the
mountains and I-80 corridor as an upper level disturbance moves
parallel to the surface front. GFS suggests that this front and
a midlevel upper level disturbance/cold pool will be the focus
for numerous to widespread showers and thunderstorms through
late Wednesday before the front dissipates. 00z GFS showing some
pretty high QPF totals with mostly rainfall below 7000 feet,
but some solid snowfall totals for the mountains. However, the
other models are not as aggressive and show the front
dissipating much sooner compared to the GFS. Increased POP over
the NBM, but did not go as high as `likely` quite yet due to the
uncertainty. Otherwise, we are expecting a slow warming trend
next week with near or slightly above average temperatures in
the mid 50s to mid 60s. Will need to monitor the potential for
strong thunderstorms since models and ensemble guidance are
showing a gradual increase in low level dewpoints under easterly
upslope flow during the week.
&&
.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 524 PM MDT Thu Apr 17 2025
A weather disturbance and cold front will bring widespread snow
to the terminals through tonight.
Wyoming TAFS...Ceilings will range from 300 to 1500 feet through
15Z, with periods of light snow and fog reducing visibilities
to 1/4 to 4 miles, then ceilings will improve to 1500 to
2500 feet after 15Z Friday. Winds will gust to 25 knots at
Laramie until 01Z, and to 25 knots at Rawlins until 15Z Friday,
and gust to 30 knots at Cheyenne.
Nebraska TAFS...Ceilings will range from 500 to 2500 feet until
15Z Friday, with occasional light snow and fog reducing
visibilities to 1 to 4 miles, then ceilings will improve to
2500 to 3500 feet after 15Z Friday. Winds will gust to 35 knots
until 06Z, then will gust to 25 knots at Sidney after 12Z
Friday.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...Winter Storm Warning until noon MDT Friday for WYZ101>103-105-
109-112-114-116.
Winter Storm Warning until 6 AM MDT Friday for WYZ104.
Winter Storm Warning until 6 PM MDT Friday for WYZ106-110-117.
Winter Weather Advisory until 6 PM MDT Friday for WYZ107-108-
113-115-118-119.
NE...Winter Weather Advisory until noon MDT Friday for NEZ002-095.
&&
$$
UPDATE...CG
SHORT TERM...SF
LONG TERM...TJT
AVIATION...RUBIN
Area Forecast Discussion
National Weather Service Quad Cities IA IL
655 PM CDT Thu Apr 17 2025
.KEY MESSAGES...
- Storms, possibly severe, moving in from the west late
tonight.
- Scattered storms are possible with a frontal passage Friday
afternoon and evening, mainly along and east of the MS River.
- Another storm system may move across the region Sunday with
more in the way of widespread rainfall.
&&
.SHORT TERM /THROUGH TONIGHT/...
Issued at 250 PM CDT Thu Apr 17 2025
Tonight, storms are still on track to develop along the cold
front out across western Iowa. The initial convection still
appears to be supercellular. This may surge east along the I-80
corridor as SW 40+ KT LLJ develops. Timing remains on track with
a storm cluster entering our west around/after 11 PM and then
moving east across the area through about 3 AM. After
consistently tracking storms along Highway 20, the latest couple
of runs of the HRRR have shifted the cluster of storms to the
south along I-80. Uncertainty remains in exactly were the storms
will track and unfortunately will be better defined after
development out west around 6/7 PM and the subsequent evolution
this evening. They may still be strong to severe, with damaging
wind gusts and large hail the main risks. It is noted that the
later the storms move into the area, the lower the risk of
reaching severe criteria. The storms should be progressively
weakening as they track eastward which is maintained with SPCs
Slight Risk (2 of 5) generally west of the MS River and a
Marginal Risk (1 of 5) to the east.
&&
.LONG TERM /FRIDAY THROUGH THURSDAY/...
Issued at 250 PM CDT Thu Apr 17 2025
Friday, the cold front has slowed a bit and may now result in
some storms development along it during the late afternoon along
and east of the MS River. This remains uncertain as it all
depends on how things unfold tonight. Latest CAMs show some
post-frontal development with potential for some elevated
storms with hail the main risk. Another factor that may hinder
development is the degree of cloud coverage Friday morning. This
could limit heating and delay development off to the south and
east. Will need to monitor forecasts more closely with potential
for quick shifts in the forecast direction. Current timing for
storm potential is between 5 and 8 PM. Highs for Friday are
currently expected to range from the upper 60s far NW CWA to
upper 70s/near 80 SE half or so. ..14..
Saturday and Sunday...Saturday a cooler post-frontal day with a few
overrunning showers skirting the far south, rest of the area dry
with highs in the 50s and 60s. Some upper 30s in the north Sat
night. Sunday ensembles coming into more agreement of another strong
cyclone rolling up out of southern plains trof base and somewhere
acrs the mid to upper MS RVR Valley. Depending on this system`s
track, heavy rain and severe weather will be possible on it`s
respective northwest and southeast flanks. Will have to stay tuned
for additional model runs for phasing and trends.
Monday through Wednesday...Longer range ensemble trends in the wake
of whatever system can impact the midwest late in the weekend,
suggest a flattening mid CONUS steering flow and temp moderation
early to mid week. Such a progressive flow would probably mean
another precip making system moving acrs the region toward mid
week. ..12..
&&
.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 633 PM CDT Thu Apr 17 2025
A warm front sits to the west of KCID and KBRL to start the
period with ceilings across the area between 3500 and 6000ft.
Winds are southeasterly round 15 knots with gusts up to 25
knots. Wind speeds are forecast to diminish slightly tonight
with a gradual turn to the south however LLWS is forecast to
develop at all TAF sits after 04 UTC. Ceilings are forecast to
lower to 3500ft area wide by 06 UTC. A disturbance moving across
the area this evening will bring the risk of thunderstorms to
KCID, KDBQ, and possibly KMLI between 04 and 09 UTC. Have placed
prob30s at all three sites to account for this timing.
Confidence is lower that they will impact KMLI. MVFR ceilings
and visibilities will be possible with these storms. MVFR
ceilings will prevail after the storms pass.
Winds will become southwesterly after 12 UTC Friday and
increase to 15 to 25 knots. A cold front is forecast to move
across the area after 18 UTC from west to east. Thunderstorms
will be possible along the front during the afternoon and may
impact KMLI and KBRL after 22 UTC but confidence is low on the
timing so they were left out of the TAFs for this issunace.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...None.
IL...None.
MO...None.
&&
$$
SHORT TERM...14
LONG TERM...14
AVIATION...Cousins
Area Forecast Discussion
National Weather Service Green Bay WI
1023 PM CDT Thu Apr 17 2025
Updated aviation portion for 06Z TAF issuance
.KEY MESSAGES...
- Rain/storm chances continue through Friday. Some storms Friday
afternoon could become strong to severe in and around the Fox
Valley, with large hail being the main threat.
- Next chances for widespread precipitation arrive Sunday night into
Monday. Mixed precip types possible, especially north and west of
US-8.
&&
.DISCUSSION...
Issued at 345 PM CDT Thu Apr 17 2025
RAP surface analysis shows an elongated 992-997 mb surface trough
extending from Colorado to south-central MN, with GOES-East Day
Cloud Phase RGB imagery showing a line of cumulus with some
overshooting tops draped across north-central Wisconsin. Frequent
lightning has been shown with these storms, especially Price
County and north, though lightning trends have decreased with
further penetration into Wisconsin from Minnesota as the airmass
over especially northeast Wisconsin remains stable. More unstable
air is advecting in, with these storms riding a MUCAPE gradient
ranging around 250-1000 J/kg. CAMs have struggled to capture storm
behavior today on the northern end but have been more consistent
in capturing storms kicking off closer to the southern MN portion
of the surface trough. CAMs do consistently show these storms
being the primary threat into the evening and overnight hours. The
12Z HREF suite struggles to keep much elevated instability for
these storms with mean MUCAPE values only in the 100-250 J/kg
range, but shear profile is outstanding with south to southeast
surface winds veering to southwest at near 50 kt by midnight
tonight at 850mb. 0-6km bulk shear values of near 50 kt will keep
organized what storms do make it into the region, though the
meager instability will limit the ceiling of impacts to small to
borderline severe hail and gusty winds.
Moving into the morning hours of Friday, a lull in the precipitation
is generally expected before CAMs indicate convective initiation as
better instability is present (MUCAPE closer to 1000 J/kg) and still
supportive shear profiles (0-3km SRH near 300). However, with the
best synoptic forcing moving past the region during the daytime
hours, it is not completely clear whether the good ingredients for
storms can come together. There is also some question at the ability
for the low levels to be destabilized as the precipitation-moistened
low levels are expected to keep cloud cover over the region even
during the lull in precipitation. Still, the present danger for
damaging winds and severe hail should initiation occur is high
enough to warrant an SPC Marginal Risk (1/5). Regardless of exactly
how things shape out, high pressure encroaching on the region will
quickly extinguish showers overnight Friday into Saturday, with GEFS-
mean 1028mb high pressure residing over the region by Saturday
evening.
After a dry Saturday with highs climbing back into the 50s,
attention turns upstream to a cutoff 500mb low aloft in the Four
Corners region at 12Z Saturday, negatively tilting as it reaches the
Central Plains Sunday afternoon. Isentropically-forced precipitation
ahead of the resulting surface low of 1000-1010 mb will begin to
ramp up PoPs Sunday evening from the south and west. Given the
complexity of the current setup, ensemble spread in the track of
this system and the following system (shortwave-forced low following
the International Border) is high. Winter weather chances are not
quite done for the season, as chances for accumulating snow climb to
20-40% north and west of a line from Rhinelander/Tomahawk to
Florence/Aurora by Monday morning. After brief ridging moves over
the area in the wake of that system, the aforementioned trailing
system approaches for the midweek period of next week, but spread in
the guidance is quite high at this time.
&&
.AVIATION...for 06Z TAF Issuance
Issued at 1018 PM CDT Thu Apr 17 2025
Showers and scattered thunderstorms will move across the area
through 09z, then a lull or break in the rain until mid to late
morning when another round of showers and storms will impact
central and east-central WI. A steadier rain is expected Friday
afternoon, with scattered thunderstorms at times across east-
central Wisconsin. Some of the stronger storms may produce small
hail tonight, while large hail may be possible across east-central
WI Friday afternoon. The other big question is when the low
clouds arrive (MVFR/IFR or lower) arrive late tonight into Friday
morning and should continue through Friday afternoon. CIGS should
gradually improve Friday night as the precipitation comes to an
end.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
DISCUSSION.....WFO MQT GS
AVIATION.......Eckberg
Area Forecast Discussion...Updated
National Weather Service Lincoln IL
901 PM CDT Thu Apr 17 2025
.KEY MESSAGES...
- A cold front will bring scattered thunderstorms to central
Illinois Friday evening. There is a slight risk (level 2 of 5)
for severe thunderstorms with damaging wind gusts and large hail
the primary concerns (15% within 25 miles), but an isolated
tornado cannot be ruled out (2% within 25 miles).
- As the severe threat diminishes Friday night, attention will
turn to flooding concerns as heavy rain develops. Middle 50th
percentile precip amounts through the weekend range from 0.75 to
2.50 inches with some localized swaths over 3.00 possible (90th
percentile forecast).
&&
.UPDATE...
Issued at 901 PM CDT Thu Apr 17 2025
Severe convection continues to bubble over far western Iowa late
this evening. The majority of the CAMs show this activity tracking
east-northeast along the nose of the LLJ into northern IL late
tonight and staying just north of the county warning area. There is
a low chance activity could graze Knox/Stark/Marshall counties late
tonight, but the only model still indicating that is the 18Z NAM
Nest.
Winds will remain elevated overnight with gustiness picking up once
again by mid to late morning. Forecast soundings still suggest
strong capping in place most of the day, which is already noted on
our 00Z sounding with a 10 degree C temperature profile at 700 mb.
The 00Z HRRR still implies there may be a few robust updrafts late
Friday afternoon as the front approaches and the CAP begins to
erode. However, coverage doesn`t begin to expand until later Friday
night as a broad ~50 kt LLJ spreads over the area. Although
confidence isn`t high in the exact start time of convection on
Friday, storms could begin initiating as early as 5-7 pm.
NMA
&&
.DISCUSSION...
Issued at 214 PM CDT Thu Apr 17 2025
Afternoon water vapor imagery shows a very dry mid level air mass
and elevated mixed layer lifting northeast across OK/KS which
guidance depicts overspreading central Illinois overnight into
Friday morning. Soundings show very steep lapse rates that are
nearly dry-adiabatic especially within the 800-600mb layer. This
is atop an incredibly strong capping inversion. MLCIN in excess of
600 J/kg will be in place to start the day Friday and is expected
to persist most of the day across central Illinois very
effectively capping the warm sector and preventing deep
convection. It`s not until the arrival of a cold front Friday
evening that guidance begins to erode the cap. Scattered storms
should eventually be able to form Friday evening, and parameter
space is supportive of severe weather once the cap breaks.
Moderate instability around 1000-1500 J/kg MLCAPE and strong deep
layer shear of 45-50 kt will allow for rotating updrafts with
initially discrete storms. Forcing along the front appears weak
Friday evening with the surface low pulling away across the Great
Lakes and a col area moving into central Illinois late in the
evening. Given the modest synoptic scale forcing and antecedent
cap, it appears that upscale growth will be slow if much at all.
CAMs generally depict scattered clusters of storms over the area.
Storm coverage will increase late in the evening and overnight,
especially south of I-72, in response to a low level jet along the
lower to mid Mississippi Valley overspreading southern Illinois.
Frontal boundary is expected to meander over the southern half of
the state over the weekend and will serve as the focus for
additional rounds of showers and storms. The heaviest period of
rain is expected to be Friday night into Saturday morning
associated with the aforementioned LLJ. Cloud bearing flow
(850-300mb) and deep layer shear vectors are both parallel to the
quasi-stationary surface front indicating that training storms
will be possible. HREF LPMM through Saturday morning shows some
localized swaths of 1.5-2.0 inches with additional rain expected
later Saturday and Sunday.
NBM 72-hour mean QPF from Friday through Monday morning ranges
from around 1.25 along the I-74 corridor to 1.50-2.00 inches
along our southern CWA boundary (Beardstown to Lawrenceville).
90th Percentile indicates that there is some potential for some
higher end rainfall amounts of over 3.00 inches of rain through
the weekend. RFC 6-hour flash flood guidance generally ranges
between 2.5-3.0 inches.
Early next week, departing low pressure over the Great Lakes will
usher in colder air across the Upper Midwest and into central
Illinois while, at the surface, high pressure builds across the
region. This will allow for a dry but slightly cooler start to the
upcoming week. Highs will top out around 60 degrees Monday, but
should begin to warm back up Tuesday and Wednesday as the ridge
axis shifts to our east allowing southwest flow to overspread the
area. Models begin to diverge by the middle of next week, but
another area of low pressure and attendant cold front is expected
sometime in the Wed/Thu timeframe bringing the next chance for
precip to the area.
Deubelbeiss
&&
.AVIATION... (For the 00z TAFs through 00z Friday Evening)
Issued at 624 PM CDT Thu Apr 17 2025
Southeast winds will remain elevated overnight as they gradually
veer to the south by Friday morning. Winds will increase some by mid
to late morning with gusts up to 35 kts expected throughout the day.
Convection developing over the Plains states late this evening is
progged to track east-northeast into northern IL overnight,
though most guidance keeps this activity north of the airfields. A
slow moving cold front will sag into the area late Friday
afternoon, potentially sparking the development of a few scattered
showers or isolated storms near/west of I-55 between 21-00Z.
However, better chances for precipitation look to hold off until
after 00Z.
NMA
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Area Forecast Discussion
National Weather Service North Platte NE
629 PM CDT Thu Apr 17 2025
.KEY MESSAGES...
- Isolated thunderstorms (~20% coverage) are possible late this afternoon
into the early evening hours. There is a marginal threat for
severe storms, mainly from Lincoln County east to Custer
County.
- Post frontal precipitation will become more widespread
tonight with snow expected over northwestern Nebraska. Snow
accumulations on the order of 1 to 3 inches are possible in
the Pine Ridge area.
- Below normal temperatures are likely Friday and Saturday with
readings moderating back to more seasonal normals Sunday.
&&
.SHORT TERM /THROUGH FRIDAY NIGHT/...
Issued at 351 PM CDT Thu Apr 17 2025
The main forecast
challenges in the short term lie in the next 12 to 24 hours with two
main issues.
1) Convective potential this evening across the area.
The frontal boundary is currently south of the area and the 12z 3KM
NAM is about 1 to 2 hours behind on the frontal position currently.
This soln fires off convection along the front, some of which clips
eastern Custer County around 21-23z this afternoon. Given the
current frontal position, have better faith in the 18z HRRR soln
which fires off convection just off to the east and southeast of the
forecast area. That being said, feel at this point that the severe
threat for the forecast area is now minimal. However, elevated
thunderstorms cannot be ruled out as additional post frontal
forcing works into the southern FA early this evening. There remains
a decent amount of elevated CAPE and instability generally south of
highway 92 this evening. Any stray storms which do develop will more
than likely remain below severe limits, but given the mid level
instability, felt it premature to pull out all mention of thunder
through mid evening. Another recent development, which could limit
convective development is what is happening to the agitated CU field
over northeastern Colorado. Over the past hour, this cloudiness is
being sheared apart. Given the model forecast of 60+ KTS of deep
layer shear, this doesn`t surprise me.
2) The threat for snow across the northwestern forecast area. Mid
level lift will increase from eastern Wyoming into the northern half
of the Nebraska Panhandle tonight. NAM12 cross sections taken
through the northeastern panhandle indicate a 3 to 6 hour period of
upright lift (9pm-3am MT) centered over the northern Panhandle. With
temperatures expected to be 30s, falling to below freezing
overnight, temps will be cool enough to facilitate snow. Given the
upright lift, some snow intensities could be on the high side,
especially if banding develops, which is indicated in the HRRR and 3
KM NAM solns. Based on forecast QPF, feel 1 to 3 inches of snow
looks probable in northern Sheridan County. Wouldn`t be surprised if
these amounts go higher in the Pine Ridge. That being said, will
hoist a winter weather advisory for Sheridan County from 9 PM MT
through Noon MT tomorrow. Lighter amounts of snow will be possible
further south into the western Sandhills. Lighter intensities,
coupled with warmer ground conditions, should limit any
accumulations to under an inch.
A northern stream trough will dive south into the Dakotas Friday
into Friday night. This will shift forcing south into Colorado and
Kansas, effectively shifting the precipitation threat south of the
area. However, with northerly winds and persistent cloud cover
Friday, highs will struggle to get out of the 40s.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
Issued at 351 PM CDT Thu Apr 17 2025
Another trough of low pressure aloft, will track across the
central and southern Plains Saturday into Saturday night. This
will increase the chance for precipitation, mainly over the
southern half of Nebraska with the bulk of storms/precipitation
well south of the forecast area in Kansas. Beyond Sunday, the
northern stream will remain active with low amplitude flow
extending across the southern 2/3rds of the CONUS. Temperatures
will be seasonal next week with highs in the 60s to lower 70s.
Precipitation chances do not appear to be good over the next
week and will be highly dependent on moisture return from the
gulf. ATTM this moisture appears to be focused over the eastern
third of Nebraska.
&&
.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 629 PM CDT Thu Apr 17 2025
For the KLBF terminal: Clouds will increase overnight with
broken ceilings reaching around 3000 FT AGL overnight. Ceilings
will fall further Friday morning to around 1500 FT AGL. Winds
will be northerly with gusts up to 25 KTS. For the KVTN
terminal: Ceilings will fall to 1500 to 3500 FT AGL overnight
with a small threat for rain or rain and snow showers. Ceilings
Friday morning into the afternoon hours will fall to 1000 to
1700 FT AGL. Winds will be northerly with gusts up to 25 KTS
thorugh 12z Friday.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from 9 PM this evening to noon MDT
Friday for NEZ004.
&&
$$
SHORT TERM...Buttler
LONG TERM...Buttler
AVIATION...Buttler
Area Forecast Discussion
National Weather Service Omaha/Valley NE
636 PM CDT Thu Apr 17 2025
.KEY MESSAGES...
- Severe weather threat this evening (15-45% chance, mainly 5-10
PM). Primary threat: large hail up to baseballs. Secondary
threats: damaging winds 60-70 mph and tornadoes.
- Shower chances return to the region Sunday though confidence
is low in exact timing/placement of the heaviest rain.
- Increasing chances for showers and storms toward the end of
next week.
&&
.DISCUSSION...
Issued at 231 PM CDT Thu Apr 17 2025
The cold front is currently located along a line from Sioux City
to Humphrey with moisture pooling along and ahead of the frontal
boundary. Dew points are running a bit higher than earlier
forecasts, already up around 60 degrees in many locations. This
has led to a greater amount of cloud cover across eastern
Nebraska and southwest Iowa in the warm sector. Temperatures are
still forecast to get up into the 80s this afternoon with storms
developing along the cold front between 5-6 PM between Columbus
and Thurston Counties.
CAMs have been consistently developing storms along the front
right around 5-6 PM. As we approach storm initiation time, we`ll
see a dry line set up along our western counties of Butler to
Jefferson Counties. This will create a triple-point on the east
side of the approaching surface low along or just north of the
Kansas state line. Strong southerly flow increasing into the
afternoon will enhance low-level helicity in the warm sector
ahead of the cold front. High LCLs around 1500-1800 ft will at
least initially limit shear in the lowest 1km, but 0-3km SRH
values of around 150-300 m2/s2 indicate a good potential for
supercell development. LCLs will be lowering as we get later in
the evening hours, increasing the potential for lower-based
supercells which could produce tornadoes. The greatest threat
with these storms will be large hail up to the size of
baseballs. Tornadoes and damaging wind will also be possible as
well.
The greatest uncertainty with this system is how far south
storms will develop. This morning guidance was trending farther
north with storm development, mostly keeping storms north of the
Omaha Metro. Later guidance has started bringing that potential
back to the south, with storms as far south as Lincoln now
possible. Greatest confidence is in storms developing around
Omaha northward. In any case, the storm farthest south will
likely have the best tornadic potential as it should have a
clear, untapped inflow region. Again, storms will develop around
5-6 PM, moving through Omaha/Council Bluffs around 7-8 PM. The
HRRR develops a trailing supercell out toward Lincoln around 9
PM, but this appears to be an outlier. For the most part storms
should be east of our area by 10 PM, but if the outlier scenario
occurs, we could have one last storm which exits our area around
midnight.
Overnight, skies will be clearing behind the cold front with
northerly winds bringing in cooler temperatures. Low clouds will
develop across our area becoming widespread by daybreak. We
could see some pockets of light rain or drizzle develop in the
low clouds overnight into early Friday, but these should end by
7 AM. Clouds will remain socked in through the day on Friday
with highs only warming into the mid-50s Friday afternoon.
Over the weekend we`ll see the upper-level trough over the
Rockies sink farther south, developing a strong surface low over
the Texas/Oklahoma Panhandle region. This will keep cooler
temperatures locked in over eastern Nebraska and western Iowa.
With skies clearing on Saturday, we will see temperatures warm
to around 60 Saturday afternoon. On Sunday, the northern
periphery of the precip shield will clip our area with highest
chances across southeast Nebraska and southwest Iowa. These
areas could see rain through most of the day while areas in
northeast Nebraska could get missed completely or only see a few
periods of light rain.
Going into next week we`ll see that upper-level trough kick off
to the east bringing back more zonal flow for the first half of
the week. High temperatures will warm back into the 70s starting
Monday, approaching 80 on Tuesday. We`ll want to watch the
overnight hours Monday night into early Tuesday for a potential
MCS as we see a weak shortwave move across our area interacting
with a strong low-level jet. Beyond that we see troughing
redevelop over the western CONUS bringing us back into a
southwesterly flow regime with increased chances for showers and
storms going into next weekend.
&&
.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 616 PM CDT Thu Apr 17 2025
Several concerns for this TAF period. 23z radar imagery shows a
line of supercell thunderstorms from just northwest of KLNK
toward KAHQ to KFET to KTQE. This line will continue to advance
eastward through the evening hours, reaching KOMA by the 01z
timeframe. Have only included mentions of -TSRA in KOMA TAF
given confidence is higher here that the terminal could see
direct impacts. Storms look to remain to the northwest of KLNK,
but have included CB mentions in cloud decks and have also
included a TEMPO for strong wind gusts associated with the
thunderstorm outflow boundary. Expect localized visibility
reductions to MVFR or IFR within any storms. Storms will exit
the area after 3z or 4z.
MVFR ceilings will return late tonight behind the frontal
boundary and persist through about 20z-21z. Winds will switch
to the northwest after 00z or 01z for KOMA and KLNK, and will be
gusty around 20-30 kts throughout the period before subsiding
late in the TAF period.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...None.
IA...None.
&&
$$
DISCUSSION...McCoy
AVIATION...Castillo/Barjenbruch