Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/28/25
Area Forecast Discussion
National Weather Service Aberdeen SD
640 PM CDT Sun Apr 27 2025
.KEY MESSAGES...
- There is a Slight Risk (level 2 out of 5) of severe storms for
central South Dakota late this evening into the early overnight
hours and a Marginal Risk (level 1 out of 5) for eastern South
Dakota and west central Minnesota mainly overnight.
- There is an Enhanced Risk (level 3 out of 5) of severe storms
along and east of I-29 Monday afternoon, with a Slight Risk
(level 2 out of 5) to a Marginal Risk (level 1 out of 5)
extending back into central South Dakota. Large hail, strong
winds and tornadoes are possible along and east of I-29.
&&
.UPDATE...
Issued at 640 PM CDT Sun Apr 27 2025
The entire forecast area remains under a layer of low to mid
clouds with thunderstorms starting to develop across western SD
and western NE. We will continue to monitor these storms to the
west as they shift closer to our area. Strong/damaging winds and
large hail will remain a concern, particularly over central SD
through around 08-09Z before diminishing in intensity across
eastern SD and west central MN. The current SPC Day 1 Convective
Outlook still looks reasonable, with the slight risk of severe
storms mainly near and west of the Missouri River (west of ABR).
There are still some small timing differences, with the latest
HRRR nearly an hour quicker than some of the other CAMS.
&&
.SHORT TERM /THIS EVENING THROUGH MONDAY NIGHT/...
Issued at 307 PM CDT Sun Apr 27 2025
An upper level ridge will get pushed east tonight as a broad
shortwave trough reaches the Rockies. Shortwave energy will ride up
the east side of the trough and across the CWA late this evening and
overnight. Will see additional energy affect the region Monday and
Monday night as the northern portion of the trough strengthens and
tracks across the Northern Plains.
At the surface, the region is currently situated between high
pressure to the east and low pressure to the west. The low will work
its way to western South Dakota/Nebraska by midnight, then becomes
centered over central South Dakota by Monday morning. Showers and
thunderstorms will develop later this evening across southwestern
South Dakota, then will track northeastward across the majority of
the CWA overnight. A combination of the boundary with the low, the
upper level energy, bulk shear of 45 to 60 knots, 1000-2000 J/kg of
MUCAPE and a 35 to 45 knot low level jet, will result in the
potential for some of the storms to be strong to severe, with large
hail and strong wind gusts being the main threats. The far
southwestern CWA may also see a brief period of time when conditions
will be right for a tornado. The Storm Prediction Center has placed
central South Dakota in a Slight Risk (level 2 out of 5) for severe
storms and eastern South Dakota and west central Minnesota in a
Marginal Risk (level 1 out of 5) for tonight.
The surface low and associated boundary will make its way to eastern
South Dakota by midday before tracking into Minnesota during the
afternoon. After a brief respite in precipitation during the morning
hours, additional daytime heating will result in 2000-3000 J/kg of
MUCAPE and 35 to 45 knots of bulk shear, bringing another chance for
thunderstorm development over portions of northeastern South Dakota
into west central Minnesota from midday through mid to late
afternoon, with again a chance for some of the storms to produce
large hail and strong wind gusts, with a tornado or two possible.
The Storm Prediction Center has placed far northeastern South Dakota
and west central Minnesota in an Enhanced Risk (level 3 out of 5)
for severe storms, areas west of there to the James River Valley in
a Slight Risk (level 2 out of 5), and areas west of there including
all but north central South Dakota in a Marginal Risk (level 1 out
of 5). Will also see some post frontal precipitation potential
Monday night, along with cooler air moving in as high pressure drops
over the western Dakotas. Do not expect any accumulation, but could
see light rain mix with, or briefly change over to, snow Monday
night. The precipitation will come to an end over central South
Dakota by midnight or so, with just some lingering showers across
the east after midnight.
Low temperatures tonight will be in the upper 40s to mid 50s. High
temperatures on Monday will range from the mid 50s across north
central South Dakota, to the lower 70s across far northeastern South
Dakota and west central Minnesota. Lows Monday night will be in the
mid 20s to lower 30s.
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
Issued at 307 PM CDT Sun Apr 27 2025
As a surface high pressure moves into SD Tuesday morning, the
chance for precipitation drops and temperatures start to warm. Mid-
level WAA helps to keep temperatures around normal through Thursday,
in the upper 50s to lower 70s. A frontal passage Wednesday
afternoon/evening looks to bring some precipitation over central and
eastern SD Wednesday evening until Thursday morning/afternoon.
Models do vary slightly with the location and when the precipitation
exits SD, though they are coming into more agreement over the past
few model runs. Precipitation looks to be light, with the clusters
having only a 20-30% chance for a tenth of an inch of rain to occur.
After the passage of the frontal boundary, winds look to increase
Thursday afternoon. Northwest winds have the potentially to gust
up to if not over 25kts, mainly west of the Missouri River. Mid-
level moisture helps to keep surface relative humidity values over
35%. Even with the stronger winds, the moisture and the fact
things are starting to green up will help to reduce the need for a
fire weather headline.
After Thursday, an upper-level ridge and surface high pressure
starts to move towards and over SD. This high pressure helps to keep
the chance for precipitation lower while also helping to advect warm
air into central and eastern SD. This looks to warm surface
temperatures slightly, leading to the temperatures Friday and into
the weekend warming 5-10 degrees hotter than normal.
&&
.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 640 PM CDT Sun Apr 27 2025
Terminals KABR,KATY,KPIR,KMBG
VFR conditions start us off at MBG/PIR over central SD, with
plenty of lower clouds in the form of of low end MVFR ceilings at
ABR/ATY. These lower clouds mark a more stable environment over
eastern SD as we monitor storms over western SD/NE spread into our
forecast area overnight through daybreak Monday. The mention of TS
has been added to the forecast. LLWS will also be a concern at ATY
from 11-14Z with winds just above the surface gusting near 40kts.
Winds will increase behind cold front, with gusts of 25-35kts at
most locations from 15Z on out of the northwest.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
&&
$$
UPDATE...06
SHORT TERM...Parkin
LONG TERM...12
AVIATION...06
Area Forecast Discussion
National Weather Service La Crosse WI
658 PM CDT Sun Apr 27 2025
.KEY MESSAGES...
- The severe weather setup for Monday afternoon and night is
coming into better focus and is shaping up to be rather
complex in nature.
- Monday morning storms look to be more disorganized in nature,
but could produce marginally severe hail up to around 1 inch
in diameter.
- The Monday afternoon severe weather threat is highly
conditional, but if storms were to form, they would be in a
favorable environment for rapid development. These storms
would have the potential to produce stronger tornadoes and
larger hail in excess of 2 inches in diameter.
- Storms that develop close to the dryline/cold front in western
MN should move through later in the night and pose mainly a
wind and embedded tornado threat.
&&
.DISCUSSION...
Issued at 210 PM CDT Sun Apr 27 2025
This Afternoon and Tonight
Breezy south winds will continue this afternoon, especially
west of the Mississippi River and in flatter areas before
beginning to decrease after sunset, but some stronger winds are
possible west of the river overnight. Cloud coverage increases
across the area this evening and overnight as high pressure
slides eastward and a warm front lifts northward through the
area. Overnight lows fall into the low to mid 50s across much of
the area.
Monday Morning
A least one ribbon (possibly several) of theta-e advection on
the nose of a 40-50-kt LLJ are expected to result in scattered
thunderstorm development after midnight tonight. Hodograph
profiles through the effective inflow layer are rather
compressed, thus organized/prolonged individual updraft
structures are not expected. However, with 800-1200 J/kg of
MUCAPE situated above the warm nose, cannot fully rule out that
a stronger updraft could be capable of near severe hail. With
the surface low progged to lift to the MN/SD/ND border by midday
Monday, the surface warm front should likewise lift into
northern Wisconsin by the early afternoon.
Monday Afternoon
The severe weather potential for Monday afternoon falls
squarely in the "lower probability, but higher impact" space as
the open warm sector builds into the region. The RAP/HRRR have
been steadfast in a low stratus deck developing in the morning
hours under the cap and lingering well into the afternoon,
though how quickly we mix out given the strong theta-e advection
and daytime isolation remain uncertain. The 500-300-mb ridge
departs by 15-18Z, with increasing height falls resulting in a
dynamic cooling of the cap through the afternoon. The SBCAPE
axis builds up the MN/SD border earlier in the afternoon before
spreading eastward in the afternoon and evening. By 21-23Z,
forecast soundings from Rochester and La Crosse show an
essentially uncapped atmosphere with 2500-3000 J/kg of SBCAPE
and ample deep shear to support discrete storm organization.
With the surface dryline/cold front still well to the west, it
will take a mesoscale forcing mechanism to initiate convection.
What and where that trigger may come from remains unknown. It
could manifest itself as a differential heating boundary on the
edge of the stratus shield, or perhaps a lingering outflow
boundary from the morning convection. The 12Z convective suite
struggles to resolve any appreciable initiation signal in this
time space, with some hints in a few HREF member updraft
helicity tracks.
If a cell does manage to fire in the warm sector, it could
quickly develop supercell characteristics. Forecast hodographs
show some weakness/backing in the 2-5-km layer that could stunt
supercell growth or result in storm splitters, which will need
to be assessed as we zero in on the event. However, the strong
cyclonic curvature in the 0-2-km layer should favor a tornado
risk, possibly strong. The 2-6-km hodographs are not all that
elongated, which could limit the overall 2+" in diameter hail
threat. Nevertheless, with the potential for supercell
structures and mesocyclones, have continued the messaging of
large hail with any discrete cell.
Monday Night
Convection that initiates along the dryline/cold front in
southwest to west-central Minnesota should grow upscale over the
evening hours into multi-cell clusters or lines. How far east
(and south) this line advances is the main concern. Confidence
is high that this mode of storms will take shape, but lesser on
the areal coverage of these storms. The main threats with these
storms would be damaging winds of 60-70 mph and, depending on
the line orientation, embedded tornadoes. There is some concern
that the 0-3-km shear vector orientation is too parallel to the
line orientation to amount to much of a tornado threat, which
bears watching as we move closer to the event. The line of
storms may struggle to impact areas south of I-90, another
aspect that bears watching over the next 12-18 hours.
Overall Event Thoughts
What is rather amazing at 24-30 hours out is the current
disconnect between the synoptic guidance and their AI-based
derived products and the most recent CAM runs. The 00Z EPS/GEFS
AI output is still depicting a swath of 45-60% severe weather
probabilities from Iowa into Minnesota, though trends over the
last 3 days have shown a steady shift to the west and a
depression forming in the values over Iowa. Meanwhile, the 12Z
HREF members came in rather lackluster for convective coverage
this far east. Their main focus is over southwest into central
Minnesota, with with some token members showing initiation in
the warm sector. The 12Z HRRR completely failed to bring any
appreciable convection into the area and kept it all to the
north and west! However, the last three runs of the HRRR neural
network have shown a slow increase in probabilities further
southward into southeast MN and southwest WI for the late
afternoon and evening, so this will bear watching.
Tuesday - Friday: Cooler, Scattered Showers
Surface ridging moves through the region on Tuesday, with
steady cold air advection dropping highs back into the upper 50s
to low 60s under clearing skies. This ridge will be transient
and warm air advection sets up for Wednesday and boost highs
back into the mid to upper 60s. A disjointed polar/subtropical
wave moves through mid to late week and brings with it the
chance for scattered showers Wednesday through Friday.
&&
.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 658 PM CDT Sun Apr 27 2025
VFR cigs will drop to MVFR/IFR cigs overnight as low-level moisture
becomes trapped under a pronounced inversion. Overall, the 27.12z
HREF has fairly high confidence (70-100%) that cigs will drop to
MVFR, even IFR west of the Mississippi River, overnight as low-level
moisture works its way in. Scattered showers will move through the
area with a warm frontal passage towards daybreak with some embedded
thunderstorms possible (20-30% chance) and MVFR vsbys. MVFR/IFR cigs
will hang around through much of the morning and afternoon until the
low-level inversion breaks late afternoon allowing cigs to quickly
clear. Will have to watch the late afternoon and evening period to
see how any thunderstorms may develop. However, given that the CAMs
show minimal signal through 00z, have opted to hold off on any tsra
mention for now. Winds will increase overnight and remain fairly
strong during the daytime hours at 15-25 kts from the south with
gusts of 25-35 kts, occasional gusts to 40 kts will be possible
across unsheltered portions of northeast Iowa and southeast MN.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&
$$
DISCUSSION...Falkinham/Skow
AVIATION...Naylor
Area Forecast Discussion
National Weather Service Des Moines IA
644 PM CDT Sun Apr 27 2025
...Updated for the 00z Aviation Discussion...
.KEY MESSAGES...
- Although conditional, a Moderate Risk (4/5) of severe weather
is in place for northern Iowa Monday afternoon and Monday
night with an Enhanced Risk (3/5) elsewhere. Confidence in
initiation is low, but any storms that do develop would be
capable of high end severe weather, including
strong/significant tornadoes (EF2+).
- Outside the aforementioned window for severe weather, chances
of storms tonight into Monday morning, and then again midweek
before drying out this weekend
- Warmer and more humid Monday, otherwise seasonal temperatures
through the period
&&
.DISCUSSION...
Issued at 300 PM CDT Sun Apr 27 2025
Our pattern will remain active through midweek with both
southern and northern stream influences until things calm down
to end the week as less active northwest flow and then upper
ridging arrive. There isn`t much going on for the time being
however, but the stage was already being set for severe weather
potential. Deep warm and moist advection was already occurring
in the maturing southwest flow aloft ahead of what will be our
parent system for tomorrow. Sfc-700mb objective analysis shows
moisture streaming northward through the Plains and MO Valley,
which has also resulted in widespread stratus in those areas. An
axis of H85/H7 QG forcing mainly driven by thermo effects is
expected to advance into IA overnight with some expansion of
elevated convection, likely rooted above 1km. Effective CAPEs
may reach 1000+ J/kg with bursts of effective shear topping 30
kts. Although it`s not persistent, when it does occur with
elongated hodographs there is some pulsey hail potential with
LFCs near the freezing level.
Looking into tomorrow is when the real questions arrive, along
with a noted MLCAPE axis of 3000+ J/kg as temps and dewpoints
reach the 80s and 60s respectively: possibly the most warm/humid
day of the season thus far. With 0-6km shear values jumping to
50+ kts, the atmosphere will certainly be primed for severe
convection and discrete, all-mode supercells. The question will
be when, or if, initiation occurs however either due to CINH or
a lack of a sufficient forcing mechanism. While there will be
some weak synoptic scale lift across eastern IA from MO into the
MS Valley, and models do suggest some weaker elevated
convection there, the main question will be whether deep convective
initiation can occur along a noted dry line over western IA,
which doesn`t occur too often in the state. Low level mass
convergence will be weak with flow fairly parallel to the
dryline, and the surface low and associated strong QG forcing
moving from MN toward the Great Lakes. Extended range hi res
models at this time yesterday, such as cSHiELD and the NCAR
MPAS ensemble, where noting nearly all healthy convection and
updraft helicity streaks farther north closer to the triple
point and associated warm front, close to the typical conceptual
model for tornado outbreaks. Recent HRRR runs now entering the
applicable window reflect this evolution as well, as do various
MPAS and RRFS runs. However, some 12z HREF members across three
different cores (NamNest, NSSL WRF, HRW FV3) are now depicting
isolated weak to moderate updraft helicity swaths across
northern IA. While the Day 2 SPC outlook has scaled back
probabilities south to north, a Moderate Risk (4/5) is still in
place encompassing locations where some 12Z HREF members are
initiating convection. Any healthy convection that develops
could realize a somewhat alarming near storm environment.
Examination of 00z RAP soundings east of the dryline note
parameter space quite conductive for strong tornadoes in sub
1000m LCLs: 0-500m shear and SRH 30 kts and 326 m2/s2, and
streamwise vorticity at 0.033 (96% of total vorticity). So,
unfortunately, the primary message here needs to be that
possible outcomes range from little to no development this far
south, to isolated, but strong supercells with large hail and
longer track tornadoes. To compound those hazards, any storm
that develops would be moving rapidly, likely in excess of 50
mph with conditions potentially changing quite rapidly,
straining warning and reaction times. Needless to say, it would
be best to continue to monitor for updates into tomorrow. The
severe potential will mainly be in the early evening but
additional storms linger late evening with more development
possible east as convergence increases with the merger of the
approaching cold front and lingering dryline.
Any precipitation should exit overnight however with some
clearing and more seasonal temperatures and humidities for
Tuesday. However precipitation chances will return by midweek.
After a brief period of anti-cyclonic flow in the trailing high
pressure, 1-3km theta-e advection will return again Wednesday
with some influences from what`s left of our current upstream
system in the southern stream, but more so from a a bit stronger
northern stream shortwave dropping into the northern Plains.
The thermodynamic support starting Wednesday will eventually be
aided by more kinematic support as the short wave approaches
into Thursday resulting in a few days with chances for showers
and a few storms. The severe weather potential appears low
however, with limited instability in place. The departing trough
and flow will amplify somewhat to end the week however, leaving
us with equal ridging behind in what will be dry, inactive
northwest flow and seasonal temperatures.
&&
.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 644 PM CDT Sun Apr 27 2025
Low clouds will continue to move across the state this evening,
with MVFR conditions gradually turning to IFR and even LIFR
conditions into Monday morning. Rain showers are possible this
evening into Monday morning as well, with thunderstorm potential
still fairly limited so left out at the terminals at this time
with close monitoring continuing. Ceilings are expected to
increase my late morning into the afternoon, though will see the
potential for additional showers and storms towards the end of
the period, some storms likely becoming severe. Outside of lower
probability mentions, uncertainty remains on exact timing and
location of this activity, so will keep a close eye on this.
Winds will remain breezy throughout the period, but especially
into the mid to late morning and afternoon Monday with southerly
winds gusting to 30-35+ knots.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
DISCUSSION...Small
AVIATION...Bury
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1201 AM EDT Mon Apr 28 2025
.KEY MESSAGES...
- An early week warming trend carries temperatures into the 70s
Monday and into the 80s Tuesday.
- Showers are likely with a chance of thunderstorms late Monday
night and Tuesday morning.
- There is another chance of thunderstorms late Tuesday and Tuesday
evening, a few of which could reach severe intensity, as a strong
cold front moves through the region.
- Dry and cooler by Wednesday.
&&
.AVIATION...
Mid to high cloud spilling over the upper level ridge axis in a jet
entrance corridor will drift across Southeast Michigan this evening
and tonight. Persistent midlevel dry air advection off of high
pressure will lead to VFR conditions throughout the period. A
southeast wind trajectory is expected.
.DTW THRESHOLD PROBABILITIES...
* None
&&
.PREV DISCUSSION...
Issued at 357 PM EDT Sun Apr 27 2025
DISCUSSION...
A broad area of high pressure is centered over the Great Lakes and
delivering an exceptional late April day to SE Mi. Full sun is
helping afternoon temperatures easily reach the mid 60s inland from
the lakes while increasing onshore wind holds readings in the 40s
along the Lake Huron shoreline. Lower Mi is still east of a 500 mb
ridge building across the Midwest which is combining with the surface
high to produce an impressively dry profile shown in the 12Z DTX
upper air sounding. This has so far held back any mid and high clouds
straying eastward from the Midwest zone of developing mid level warm
advection and moisture transport. A few patches of these clouds
eventually make it this far east late tonight and Monday, however
this stage of theta-e advection is weak up against sub 700 mb dry air
from the mid Atlantic into the eastern Great Lakes. No frost
concerns despite the clear sky as surface wind veers south and
increases just enough to hold temperatures in the lower to mid 40s by
sunrise Monday morning. Readings are then positioned for a run into
the 70s as the Monday weather highlight as south wind increases under
clouds still slow to increase during the afternoon.
The mature Plains low pressure system is projected to move from SD
into MN during Monday while having a strong warm front extend into
the mid MS/TN valleys by Monday evening. Plentiful Gulf moisture is
already feeding into the system from the southern Plains today and
will supply elevated moisture transport into the Great Lakes on SW
850-700 mb flow averaging 50 kts late Monday night through Tuesday
morning. Given the available Gulf moisture, prefer a more aggressive
scenario for nocturnal/elevated convection across SE Mi compared to
consensus of deterministic model and HREF QPF ending 12Z Tuesday
morning. It seems very reasonable for upstream surface based storms
to fade Monday evening leaving room for new development on the
strengthening low level jet across Lower Mi after midnight. Bulk
parameters such as NAM 1000-850 mb MUCAPE near 2000 J/kg, GFS 700-500
lapse rate near 7.5 C/km, and HREF mean MUCAPE of 1000-1500 J/kg all
suggest a greater nocturnal convective response compared to QPF
fields through Tuesday morning.
The Monday night/Tuesday morning activity shortly precedes the
surface warm front which races northward across southern Lower Mi by
mid morning. A cloudy inbound warm sector is a good bet again based
on upstream observations across the Plains and Gulf Coasts today. It
will otherwise be a summer air mass sporting mid 60s surface Td and
eventually afternoon highs in the lower 80s. Model soundings show
the boundary layer already well mixed in the morning for a wind
profile supporting gusts surging into the 30 kt range over land
areas. This will help with temperature recovery and formation of an
afternoon instability axis subject to another round of thunderstorm
development late in the day into Tuesday evening. The consensus of
12Z model solutions still favors later/farther east timing, although
questions linger on the timing of cap release and character of the
surface features. The NAM and RAP solutions also still demand
attention due to earlier/farther west timing, and the latest
afternoon adjustments to the SPC Day 3 Outlook move the Slight Risk
back into SE Mi accordingly.
The main cold front sweeps through Lower Mi Tuesday evening leading
to another downward spring season temperature swing. Guidance has
readings dropping into the upper 30s most areas by Wednesday morning
followed by a struggle back toward 60 Wednesday afternoon. The cold
front is nearby to the south to present a cloud component as well by
late day before it returns with another round showers Wednesday
night.
MARINE...
High pressure passing directly over the region maintains light and
variable wind through the afternoon. Wind direction organizes out of
the south tonight and gradually increases in magnitude on Monday as
low pressure develops upstream over the Midwest. However, warm air
advection will result in strong stability over the cool lakes that
will limit wind strength to some degree. Ensemble solutions favor
gusts in the 20 to 25 kt range late Monday into Tuesday within the
southerly wind regime, but a handful of solutions do produce gusts
in the 30 to 35 kt range over central Lake Huron late Monday
evening. Will hold off on a Gale Watch at this time as there is only
a 40% chance for a brief period of gales during this period and do
have concerns with the stable profiles. As the low tracks across the
northern lakes on Tuesday, its cold front trails behind bringing
scattered to numerous showers and thunderstorms to the region. Wind
veering to northwest amidst the post-frontal cold advection will
bring the next window for a brief period of 30+ kt gusts over Lake
Huron Tuesday evening. Low confidence exists for gales in this
window but it will continue to be monitored. High pressure builds in
on Wednesday with wind becoming light and variable.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...None.
Lake St Clair...None.
Michigan waters of Lake Erie...None.
&&
$$
AVIATION.....CB
DISCUSSION...BT
MARINE.......TF
You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.
Area Forecast Discussion
National Weather Service Goodland KS
332 PM MDT Sun Apr 27 2025
.KEY MESSAGES...
- Marginal/Slight risk for severe weather this afternoon,
mainly east of the Colorado border. Hail, wind and isolated
tornado threats possible. The Slight Risk area has increased
to much of the area east of the Colorado border.
- Red Flag Warning remains in effect for northeast Colorado
today, and a Red Flag Warning remains in effect for areas
along/south of Highway 40 for Monday.
&&
.SHORT TERM /THROUGH MONDAY NIGHT/...
Issued at 114 PM MDT Sun Apr 27 2025
Across the region this afternoon, skies are mainly a partly to
mostly sunny mix as clouds continue to erode from west to east. With
a warm front/dryline over eastern Colorado, there has been a
persistent strong southerly gradient w/ gusts over 40 mph at times.
The main wx concerns for the short term period will focus on the
potential for severe weather this afternoon/evening. There is also
critical fire wx conditions for Colorado today and portions of the
area along/south of Highway 40 for Monday.
There is some cumulus beginning to pop up ahead of the warm front
near the Colorado border. The latest SPC meso analysis is now
showing SBCape values 2500-3500j/kg and DCape around 1000j/kg.
Low/mid level lapse rates are slowly increasing as the afternoon
progresses with almost full sunshine now affecting areas that have
been capped through this morning.
The CAMs(HRRR, RAP NamNest) are mixed as to whether there will be
any convection initiated at all this afternoon, with the NamNest
showing best chances starting close to 00z Monday, mainly east of
Highway 27 w/ some late storms possible in the north. Given the
uncertainty for storms to get going, have kept pops around 15-25%
for this event. If they do get going, model soundings do hint at
large 2 inch plus hail and gusts to 60 mph plus. Speed and
directional shear present ahead of the front from the surface to
700mb, so can`t rule out tornado potential. Of course the
aforementioned dryline will play a role in the western extent of any
convection. This is currently west of the CWA.
For the other wx concerns this afternoon/early evening will involve
the dryline for fire weather conditions. Red Flag remains in effect
for Colorado. Winds are meeting criteria and the RH continues to
lower as the dryline approaches.
Any remaining precip lifts N/NE overnight for which there is a 15-
20% chance for a shower or storm. This will give way to mainly
clearing going into Monday for most locales. A weak shortwave on the
backside of the exiting system could bring a 15-20% chance for a
shower in the NW. Otherwise, with winds shifting to the west and
guidance showing a tight gradient 25-35 mph potential, downslope
drying will be present prompting a Red Flag Warning from the
previous Fire Wx Watch for areas along/south of Highway 40. Two
forecast cycles in a row with RH criteria being met, with areas
north in the upper teens and 20s due to clouds from passing
shortwave.
For temps, as cooler air works in from the N/NW, the region will see
a wide range for highs on Monday with upper 60s to lower 70s in
Colorado, and east of there mid 70s to the lower 80s. Warmest areas
east of Highway 83. Overnight lows tonight will range widely with
mainly 40s west of Highway 25, and upper 40s to around 60F east of
there. For Monday night, mainly 30s west of Highway 83 and upper 30s
to lower 40s east of there. Wind chill readings in the 20s across
colorado Monday night into Tuesday morning.
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
Issued at 1008 AM MDT Sun Apr 27 2025
The focus in the extended period from the latest runs of the GFS and
ECMWF Tuesday night through Friday will be a series of mid level
shortwaves that work east-southeast off the north central Rockies
into the Plains region. Best chances for storm/showers potential
will be midweek(30-40%), tapering down to a 15-20% chance into
Friday. There are differences in the two models runs for the end of
the week. There will be a strong amplified ridge building off the
Rockies settling into the Plains. The latest GFS is coming through
with dry conditions, but there is a closed 500mb low coming in from
the west that could play a role in the region`s weather if it
doesn`t get stalled/blocked by the expected ridge. The ECMWF is
closer to the latest NBM guidance bring a 15-20% chance for precip
up along the western periphery of the upper ridge, aided by
southerly flow at the surface due to a lee-side trough in the west.
With the inconsistency, will stay close to NBM guidance as any shift
in the upper ridge by the upcoming weekend could affect precip
potential greatly.
For temps, highs for Tuesday will range in the mid to upper 60s,
with warmer conditions Wednesday in the lower to mid 70s. Upper 60s
to lower 70s for Thursday will give way to warmer conditions for
Friday with a range in the mid to upper 70s. This will give way to
upper 70s through the lower 80s for next weekend, warmest area-wide
on Saturday. Overnight lows Tuesday night through Thursday night
will range from the upper 30s west into the mid 40s east. For Friday
night onward, mainly mid 40s west into the lower to mid 50s east,
warmest east of Highway 83.
&&
.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 331 PM MDT Sun Apr 27 2025
For KGLD, VFR conditions expected through the forecast period.
Winds, southeast 30-40kts through 05z Monday, then south-
southwest 15-30kts. By 10z, backing to the west-southwest
15-30kts w/ highest gusts from 18z onward. LLWS 05z-10z Monday
190-210@45-55kts.
For KMCK, VFR conditions expected through the forecast period.
Winds, south-southeast 20-30kts through 09z Monday, then
shifting back to west-southwest 15-30kts. LLWS 06z-12z Monday
190-210@45-55kts.
&&
.FIRE WEATHER...
Issued at 1049 AM MDT Sun Apr 27 2025
For Sunday, a strong southwesterly gradient(with gusts over 45
mph) across Yuma, Kit Carson and Cheyenne counties in Colorado,
combined with above normal temperatures in the 80s will create
Critical Fire Weather conditions mainly during the afternoon and
early evening hours. Humidity will drop to the lower teens
during this time.
For Monday, westerly flow with gusts to 30-40 mph for areas
along/south of Highway 40 along with humidity into the lower to
mid teens with the downslope warming, will create critical fire
weather conditions during the afternoon/evening hours.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...Red Flag Warning from 11 AM MDT /noon CDT/ to 7 PM MDT /8 PM
CDT/ Monday for KSZ027-028-041-042.
CO...Red Flag Warning until 7 PM MDT this evening for COZ252>254.
Red Flag Warning from 11 AM to 7 PM MDT Monday for COZ254.
NE...None.
&&
$$
SHORT TERM...JN
LONG TERM...JN
AVIATION...JN
FIRE WEATHER...JN
Area Forecast Discussion
National Weather Service Green Bay WI
1046 PM CDT Sun Apr 27 2025
Updated aviation portion for 06Z TAF issuance
.KEY MESSAGES...
- Multiple rounds of thunderstorms are expected on Monday and Monday
night. A significant severe weather outbreak is possible
Monday evening into the overnight hours. Most of the forecast
area has an Enhanced Risk of severe thunderstorms, with parts
of central WI in a Moderate Risk.
- Initial storms on Monday morning could produce small to near
severe hail (up to 1" in diameter), especially north and west
of the Fox Valley.
- A second round of storms (30-50% chance) could develop early
in the evening, particularly over central and north-central WI.
Coverage will be rather isolated, but all hazards will be
possible if discrete storms develop. Uncertainty is highest in
the details for this round.
- The third and final round is forecast to impact the area late
Monday evening into the overnight hours. Confidence is higher
(60-80%) that a line of storms will impact the area which will
be capable of bringing all hazards to the area.
&&
.DISCUSSION...
Issued at 129 PM CDT Sun Apr 27 2025
Short Term...Tonight...Monday...and Monday Night
The latest RAP analysis and satellite/radar imagery show high
pressure departing the region over the central Great Lakes while
low pressure is centered over northeast Wyoming. Well ahead of the
cyclone, mid-level warm advection/frontogenesis and moisture
convergence are leading to scattered, elevated shower activity
moving from west to east across western Wisconsin. Can`t rule out
a few of these showers/sprinkles reaching the ground over central
and north-central WI this afternoon. Otherwise, focus of this
forecast remains on the severe weather potential on Monday and
Monday night.
Chances for showers and storms continues to look to come in three
rounds. The first round occurs on Monday morning when a 30-45 kt
low level jet advects in a surge of elevated moisture into the
region. This round looks to be a few hours later than the previous
forecast and generally in the 7 am to 2 pm time frame. Elevated
instability (bases around 850mb) will increase to about 700 j/kg
with effective shear 30-40 kts. Therefore, it appears that large
hail will be the primary threat particularly if cells can acquire
mid-level rotation (effective shears are sufficient). Also some
evidence in the convective allowing models that gusty winds will
be possible, perhaps up to 40 mph late in the morning after some
heating takes place.
After a lull in storm chances, a warm front will be lifting north
across north-central WI and the Fox Valley from late afternoon
through mid-evening. Potential for another round of storms to
develop will occur in this period, but numerous questions remain
and is one of the most uncertain periods of the forecast. Despite
models indicating instability increasing to around 1500 j/kg,
forecast soundings reveal a pronounced mid-level cap centered
around 800 mb that could mitigate surface thunderstorm develop
along the warm front. Additionally, given the expansive cloud
cover upstream, it`s very realistic to think that the region will
be shrouded in clouds making it difficult for temps/dewpoints to
reach to 72/60 like the current forecast shows. Modifying a NAM
forecast sounding using those surface temps/dewpoints, SB cin is
about 200 j/kg (ML cin around 125 j/kg). This cin decreases to 0
j/kg for a parcel at 800mb. Therefore it seems possible that storm
coverage will be rather isolated or perhaps elevated. CAMS produce
little to no deep convection along the warm front, perhaps due to
a lack of backed flow and convergence to the north of the
boundary. But if surface based storms can develop, wind
parameters suggest all hazards will be possible given 0-1km
helicity of 367 m2/s2, stp of 1.8, and effective shear of 60 kts.
This parameter space is off the charts compared to previous high
end severe weather events in the area and ranks up there with the
April 10, 2011 severe event which produced numerous tornadoes
including an EF-3 tornado at Merrill. Any storms would be moving
rapidly northeast at 60 mph based on the mean cloud layer wind.
As if this wasn`t enough, indications remain that a line of
storms will pass through the forecast area from mid to late
evening. By this point, forecast soundings indicate that the mid-
level cap will have eroded and see signs in forecast soundings of
surface based destabilization (SB capes = 2000 j/kg, cin = -60).
This period will be favorable for all hazards as well, but more in
the QLCS territory rather than discrete cells which would put
damaging winds/tornadoes as the highest risk. This squall line
will be moving rapidly to the east or northeast due to mean winds
230 kts at 55 kts.
Storms look to exit during the early to middle of the overnight.
Long Term...Tuesday Through Sunday
In the wake of the low pressure system, cyclonic flow combined
with sufficient saturation below 8000 ft will be sufficient for
light showers or drizzle on Tuesday. Gusty winds to 30 or 35 mph
through late Tuesday morning could hinder clean up efforts from
the storms that occur on Monday night. Highs on Tuesday will
likely occur in the morning before falling slightly or remaining
steady in the afternoon. Temps for most of the day will range from
the middle 40s over far north- central WI to the upper 50s in the
Fox Valley.
Another low pressure system will bring periods of rain to the
region on Wednesday night through Friday. With the low lifting
northeast over southern Lake Michigan and the Lower Peninsula of
Michigan, the chance of thunderstorms looks low.
The next chance of rain will then occur late next weekend.
&&
.AVIATION...for 06Z TAF Issuance
Issued at 1046 PM CDT Sun Apr 27 2025
VFR conditions and dry conditions are expected late this evening
with mainly mid clouds slowly lowering overnight. Confidence
remains low on exactly where/when the best chances for showers and
storms will occur on Monday and Monday night due to a complex
weather set up. The first chance will be with a band of elevated
showers and storms (50-75% chance) impacting the area on Monday
morning and/or early afternoon. Probabilities of impacts will be
highest over central and north-central WI. The second will be
near/north of a warm front in the afternoon hours. The third will
be with one or two areas/lines of showers and storms that develop
ahead of a low pressure system and cold front to our west and race
eastward across the area. Continued the use of tempo/prob groups
to highlight the most favorable time period for the storm threat,
but adjustments will likely be needed as the picture (hopefully)
comes clearer.
LLWS is expected overnight, especially across central and north
central WI, as winds increase to 30-40 kts at 2000 ft. The strong
winds at 2000 ft will increase on Monday up to 50 kts, keeping the
threat for LLWS going; however, surface gusts to 30 kts will
limit the threat through much of the day. As surface winds
decrease slightly after sunset on Monday, LLWS will again be a
concern.
&&
.MARINE...
Issued at 129 PM CDT Sun Apr 27 2025
A period of poor boating conditions will occur from late tonight
through Tuesday afternoon as a dynamic surface low moves across
the region. Waves on Lake Michigan will approach 4 ft after 4 am
Monday morning as south winds start increasing. The worst
conditions look to occur on Monday afternoon and evening when
there is a 50-60% chance of gale force gusts over the central Bay
and Lake Michigan.
After the cold front passes, northwest winds gusting to 30 kts
will prolong the poor boating conditions through late Tuesday
afternoon.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
DISCUSSION.....MPC
AVIATION.......Bersch
MARINE.........MPC
Area Forecast Discussion...Updated
National Weather Service Lincoln IL
846 PM CDT Sun Apr 27 2025
.KEY MESSAGES...
- Gusty southerly winds (30-40 mph) on Monday will combine with
dry soils to increase the risk of blowing dust from spring
plowing. This may result in localized diminished visibility for
motorists.
- There is a level 2 of 5 (slight) risk for severe weather Monday
night west of I-55, and southeast of roughly I-70 on Tuesday.
- Additional rainfall will occur between Wednesday and Thursday.
There is currently a low (20-50%) chance rain will exceed 1".
Little or no flood impacts are anticipated during the late week
period.
&&
.UPDATE...
Issued at 846 PM CDT Sun Apr 27 2025
Minor updates this evening to account for increased cloud cover
overnight and slightly cooler temperatures as high pressure
centered near Lake Erie continues to push a cooler air mass into
central IL with an easterly wind component, and warm advection
aloft well north of a surface warm front promotes increasing cover
and lowering cloud heights. Lows look to range from lower 50s near
the IN border to mid 50s west of the Illinois River. A slight
chance for showers early in the morning west of the Illinois River
continues to look good with recent high-res models producing
little or no precipitation, but pattern suggesting potential for
light precipitation.
37
&&
.DISCUSSION...
Issued at 1227 PM CDT Sun Apr 27 2025
.Synoptic Pattern...
Current GOES WV imagery depicts a large upper- level low spinning
over the Great Basin this afternoon with a broad ridge positioned
over the central US. Short-term model guidance remains in good
agreement with how this upper low will evolve over the next 72
hours. More or less, half of this disturbance will get swept
northeastward by an emerging northern stream trough, ultimately
going on to produce the necessary forcing for a potentially
historic Upper Midwest severe weather outbreak on Monday. The
other half will become cut off from the main belt of westerlies,
stalling over Death Valley Monday night before additional
shortwave disturbances move onshore and push it across the
Southern Plains Wednesday night and eventually the Mid-
Mississippi Valley by Thursday. This all adds up to a warm,
breezing and wet stretch of weather across the central US, which
will span Monday to Thursday. Then, by next weekend, an extended
period of dry and mild weather will return as an omega block
becomes more pronounced over the region.
.A Warm/Gusty/Dusty Monday...
The surface pressure gradient will tighten Monday as low pressure
deepens and lifts across the Northern Plains. A quick glance at
regional model soundings depicts a shallow but well-mixed PBL,
with very steep LLLR (>9 C/km) and about 35 kts at the top of the
mixed layer beneath the capping inversion. The net result should
be frequent 25-30 mph gusts with sporadic 30-40 mph gusts wherever
serendipitous mixing occurs. While these gusts fall below
traditional Wind Advisory criteria, they should be sufficient for
carrying blowing dust. With relatively dry top soil and increased
field work, we are concerned for hyper-localized areas where
visibility could fall below 1 mile due to blowing dust.
.Severe Wx Monday Eve-Tuesday...
Convective trends for Monday night across central Illinois
continue to look less robust in the face of a stout capping
inversion. Both the 00z & 12z suite of CAMs reinforced the idea
that convection is going to struggle to initialize over SE Iowa
and western Illinois ahead of the front. In a corresponding move,
we have lowered PoPs for Monday evening, now 30-40%, in areas west
of I-55. SPC did trim the Enhanced Risk (level 3 of 5) from far
west central and extreme SE Iowa as a result of these convective
trends. Still, we maintained the Slight Risk (level 2 of 5) for
Monday night in areas west of I-55 where strong kinematics (50-60
kt LLJ) could yield an attendant wind risk.
The severe weather potential for Tuesday continues to look
middling as well, especially with the main upper forcing becoming
displaced further to the east and the better kinematics pushing
off to the east also. RAP guidance does suggest a corridor of
1500 J/kg MLCAPE ahead of the front near and south of I-72, though
deep- layer shear begins to wane. The most recent 18z HRRR does
exhibit some convection initializing mid- morning around St Louis
ahead of a subtle shortwave trough, eventually pushing eastward
into Illinois along the I-70 corridor. While the hodograph doesn`t
scream tornado threat (poor low-level turning), storms do appear
to be sfc- based along the front. Thus, thinking there will be a
brief window before the ambient forcing/kinematics depart our area
where supercell structures may develop and support an attendant
hail and wind threat.
.Additional Rainfall Midweek...
A stalled-out front will begin to lift northward into central
Illinois Wednesday evening into Thursday in response to multiple
shortwave disturbances ejecting out of the Southern Plains. Weak
low pressure will ride along the sfc boundary, bringing off-and-on
showers through much of the day on Thursday before departing
eastward Thursday night. Deterministic NBM QPF generally paints
0.50-1.25" between Wednesday evening and Thursday night, and this
seems to fit the probabilistic data fairly well, with only a low
chance (20-50%) that central and southeast Illinois exceeds 1"
during this mid- week period.
MJA
&&
.AVIATION... (For the 00z TAFs through 00z Monday Evening)
Issued at 602 PM CDT Sun Apr 27 2025
An approaching storm system will bring increasingly windy
conditions the upcoming 24 hours, as well as lower cigs from
around 14-18Z that could briefly lower to MVFR with isolated -shra.
Nevertheless, any -shra or MVFR cigs are too low probability for
mention in 00Z TAFs. Winds SSE around 10 kts overnight, increasing
after 14Z to S 20 kts with gusts around 30 kts by 18Z.
37
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Area Forecast Discussion
National Weather Service Miami FL
734 PM EDT Sun Apr 27 2025
...New UPDATE, AVIATION...
.UPDATE...
Issued at 726 PM EDT Sun Apr 27 2025
The dry conditions will continue to remain in place across the
region tonight as high pressure remains in control of the weather
pattern across South Florida. With winds diminishing overnight
combined with a mainly clear sky, there will be just enough lower
level moisture in place to support the possibility of patchy fog
development over interior portions of Southwest Florida late
tonight into early Monday morning. Any fog that does develop will
lift shortly after sunrise on Monday morning. Low temperatures
tonight will generally range from the lower 60s across the Lake
Okeechobee region to the lower 70s across the east coast metro
areas.
&&
.SHORT TERM...
(Rest of today through Monday)
Issued at 1242 PM EDT Sun Apr 27 2025
South Florida remains situated between a dipole of surface ridging
today, with a ridge axis present in the Gulf in conjunction with a
separate foci in the western Atlantic. Not much more exciting when
looking aloft as there is a lack of synoptic forcing across the
region with quite the stagnant vertical column in place. This
morning`s 12Z sounding and the latest model soundings show the
continuance of a stout mid-level subsidence inversion that will
continue to stifle any real rain chances (outside of a few shallow-
layer stray isolated showers advecting into the east coast metro
areas via easterly flow). Given the lack of any synoptic influence
aloft, the mesoscale will dictate the weather regime once again
today with winds veering onshore along both coasts during the
afternoon hours. Can`t rule out an isolated shower this afternoon
along the gulf breeze across inland southwestern Florida but overall
rain chances remain lackluster.
The amplification of a deep-layer ridge across the southeastern
United States on Monday will slow the progression of a backdoor
frontal boundary propagating southwestward across the Florida
Peninsula occurring in tandem with a weak upper level shortwave
ridge-riding. With the weak boundary on our doorstep, periphery
moisture associated with the frontal boundary in tandem with diurnal
heating and convergence (localized ascent along the gulf breeze
boundary) could set the stage for a few isolated showers and storms
across inland southwestern Florida. There will still be considerable
amounts of low-level dry air to contend with but if an updraft is
able to sustain long enough, forecast model soundings from CAMS such
as the HRRR, RAFS, and RAP show enough marginal instability to get a
thunderstorm going across inland southwestern Florida. Given how dry
the vegetation has become across our area and the isolated nature of
any rainfall, any lightning strike could potentially spark new
wildfires.
High temperatures will be similar this afternoon and once again on
Monday. The warmest temperatures are forecast for inland
southwestern Florida with widespread high temperatures in the low
90s. Along both the immediate gulf coast as well as the majority of
the east coast metro, temperatures will remain in the middle to
upper 80s during the afternoon hours.
&&
.LONG TERM...
(Monday night through next Saturday)
Issued at 319 PM EDT Sun Apr 27 2025
A rinse and repeat weather pattern will prevail for the rest of the
work week into the weekend as easterly flow continues and we remain
mostly dry. A weak frontal boundary will pass through, or what`s
left of it, on Tuesday. Ensemble guidance indicates a slight rise in
moisture (1.4-1.6") and potential for scattered light showers (30-
40%) across South Florida. The additional support of diurnal heating
and sea breezes will help build quick-moving light showers during
the afternoon. Unfortunately, the WPC QPF forecast is not
optimistic about how much rainfall we will receive. Deep-layer
ridging will remain established across the western Atlantic waters
through the end of the week with light synoptic flow aloft.
Subsidence and a consequent capping inversion will keep rainfall
to a minimum. Outside of a few shallow-level stray showers, the
stretch of dry and warmth will continue with drought conditions
continuing to worsen. Under the easterly flow, expect highs to be
a bit cooler on the east coast than the west, with mid to upper
80s east and low 90s west.
&&
.AVIATION...
(00Z TAFS)
Issued at 726 PM EDT Sun Apr 27 2025
Mainly VFR conditions will prevail throughout the forecast period.
Easterly winds around 10 kts this evening will become light and
variable across most terminals overnight. Some patchy fog could
develop across the interior overnight but this fog should stay
away from the terminals. Winds will increase out the east after
14z Monday and could be gusty at times during the afternoon hours.
At KAPF, winds will shift and become WSW in the afternoon as a
Gulf breeze develops.
&&
.MARINE...
Issued at 1242 PM EDT Sun Apr 27 2025
Easterly winds are expected to remain for the rest of today and into
early this week across our local Atlantic waters, with a light to
gentle westerly breeze developing each afternoon across the Gulf
waters. Seas generally 1-2 ft in the Atlantic through Monday and a
foot or less in the Gulf. Seas will start to rise in the Atlantic
for the mid-week period as a moderate to fresh breeze re-develops.
&&
.BEACHES...
Issued at 1242 PM EDT Sun Apr 27 2025
A high risk of rip currents will prevail at Palm Beach county
beaches today with a moderate risk of rip currents remaining across
Broward and Miami-Dade beaches. As easterly flow remains with us for
the foreseeable future, the elevated rip current will persist along
the east coast for much of this upcoming work week.
&&
.FIRE WEATHER...
Issued at 131 AM EDT Sun Apr 27 2025
Although winds will remain light across the region this afternoon,
relative humidity values will drop to near or just below critical
levels (low to mid 30s) across inland southwestern Florida. This may
result in enhanced fire behavior as vegetation remains quite dry
across these areas. Closer to both coasts, relative humidity values
will remain well above thresholds as onshore flow moderates relative
humidity values as sea-breezes move inland.
&&
.PRELIMINARY POINT TEMPS/POPS...
Miami 72 86 73 82 / 0 10 10 20
West Kendall 68 86 70 84 / 0 10 10 20
Opa-Locka 71 86 72 84 / 0 10 10 20
Homestead 71 83 73 83 / 0 10 10 20
Fort Lauderdale 72 83 73 80 / 10 10 10 30
N Ft Lauderdale 72 85 73 81 / 0 10 10 30
Pembroke Pines 72 86 74 86 / 10 10 10 20
West Palm Beach 69 84 71 81 / 0 10 20 30
Boca Raton 71 83 72 82 / 0 10 20 30
Naples 68 88 68 88 / 0 10 0 30
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...High Rip Current Risk through Monday evening for FLZ168.
AM...None.
GM...None.
&&
$$
SHORT TERM...Hadi
LONG TERM....JS/SH
AVIATION/UPDATE...CWC
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
835 PM CDT Sun Apr 27 2025
.KEY MESSAGES...
- Level 4/5 (Moderate) Risk for multiple rounds of severe
thunderstorms late tonight through Monday evening. Please have
multiple ways to receive warnings so you can take shelter if
needed.
- LATE TONIGHT INTO MONDAY MORNING thunderstorms develop, and a
few may be severe with large hail as primary threat.
Localized damaging wind gusts are possible.
- MONDAY AFTERNOON / EVENING, is the most dangerous period with
strong tornado potential IF storms develop. Scattered large to
very large hail and damaging winds are likely as well.
&&
.UPDATE...
Issued at 749 PM CDT Sun Apr 27 2025
Tonight into Monday morning...
We`ve seen some impressive supercells develop in the Sandhills
region of northern Nebraska this evening. We like the general
idea of the HRRR that these supercells will congeal into an MCS
over south central SoDak, then ride the nose of the LLJ ENE
through the night, ending up in northwest WI late Monday
morning. Current expectations are that these storms will be
moving into western MN around 4am, reaching west central and
northwest WI around 9 or 10 in the morning. This means the
morning commute for the Twin Cities will likely feature
thunderstorms to contend with. These storms will be elevated,
but with muCAPE of nearly 2000 j/kg and 60 kts of deep shear,
some elevated supercells are likely with this activity, driving
a primarily hail threat late tonight through Monday morning as
they move through the area. After that, it`s a question of where
does round two setup. Early arriving 00z guidance would say
that the second round starts on the cold front in western MN
during the early afternoon, with a QLCS sweeping across MN from
there. From the main discussion below, it looks like we are
starting to favor the scenario they mentioned where storms are
tied to what develops along the cold front, with a severe QLCS
to follow (see paragraph 4 for those details).
&&
.DISCUSSION...
Issued at 300 PM CDT Sun Apr 27 2025
General Discussion...We`re expecting thunderstorms to develop
late tonight across the eastern Dakotas into western Minnesota,
and spread across central Minnesota into northern Wisconsin
early Monday morning. The main threat with this morning
convection is large hail, with damaging wind as as secondary
threat. Then we expect a break from late morning into early
afternoon. This should allow the atmosphere to recharge during
this time as strong southerly winds bring warm and moist air
across the region. By Monday afternoon, another round of storms
are expected to develop. This second round is the most dangerous
with strong tornado potential if storms develop. The
ingredients will be in place for rotating storms, and in
addition to tornadoes, very large hail and damaging wind will be
possible. There is some uncertainty on timing and location of
this second round of storms, but we ask that folks remain
vigilant and take any warnings that are issued seriously. For
Monday afternoon/evening, the Moderate Risk isn`t that everyone
will see storms, rather it`s that if storms form, they could be
bad.
Technical Discussion...The first round of storms is interesting
in the fact that we have a very impressive elevated mixed layer
moving over the region, and confidence is quite high that storms
will develop on the leading edge of this EML. The wind shear in
these elevated storms is quite unidirectional, but the speed
shear should be sufficient for supercells capable of producing
large hail. The low level jet will also be strengthening with
speeds of 40 to 45 kts developing within the 900-800mb layer.
Given these strong winds just off the deck, damaging wind is
also a secondary threat for late tonight into early Monday
morning.
There is some uncertainty in the exact timing of when these
storms clear out Monday morning, but we do expect them to exit
to the northeast. Meanwhile boundary layer southerly winds will
advect warm and moist air across the region beneath this
elevated mixed layer. This should allow the atmosphere to
destabilize despite little if any solar insulation. In fact, low
level stratus from the morning convection could enhance the
tornado threat for later in the day by allowing the strong
inversion to remain in place, which would cause the surface
winds to respond more to the synoptic pressure gradient and take
on a southeasterly component. In this type of setup, you can
get hodographs that resemble a sickle, which have been noted on
significant severe weather days. If this scenario plays out,
expect low stratus to eventually transition to boundary layer
convective rolls, or cloud streets, similar to what to what we
see today. These cloud streets are a visual representation of
streamwise helicity, and can be a morning precursor to an
environment favorable for tornadoes (July 19, 2018 in Iowa, and
May 17, 2016 in western Wisconsin). The cloud streets will
eventually mix out into cumulus, followed by convective
initiation.
This convective initiation is probably the biggest wildcard for
the afternoon/evening storms. If storms manage to form ahead of
an approaching cold front in the warm sector, then strong
tornadoes are possible for the reasons outlined above. These
storms pose the risk for producing strong tornadoes. However,
there is a chance that storms only fire along the cold front. In
that scenario, tornadoes are still possible, but storms would
more likely quickly grow upscale into a line, and the main
threat would be damaging wind with shorter-lived (and usually
weaker) QLCS tornadoes. An alternate scenario is that given the
positive tilt of the upper level wave, storms struggle to form
along the cold front, and this ends up being a lower impact
event.
Tuesday through Saturday...Skies will clear as this parent storm
system races quickly off to the northeast, and high pressure
will build in leading to dry conditions through Wednesday.
Another weak system will bring a chance for showers and
thunderstorms late Wednesday into Thursday, but the threat for
severe weather is very low. Then conditions dry out again for
the weekend.
&&
.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 749 PM CDT Sun Apr 27 2025
As mentioned in the update, our first round of storms this
period can be found between the Sandhills and Black Hills. These
storms will impact central MN, with the main question being how
far south do they extend. TS chances with this first round are
highest (90%) at AXN and STC and lowest (50%) at MKT and EAU.
We`ll have stratus that will blanket the area behind the first
round of storms, but we`ll start to see cigs lift in the
afternoon as storms initiate along the cold front in western MN
around 19z. These storms will form into a line that moves across
MN, reaching MSP between 23z and 01z (6-8pm) and eventually RNH
and EAU just after this period ends.
KMSP...Confidence is highest with the round one TS forecast.
With thunderstorms expected to impact MSP between 6am and 8am.
As if having thunderstorms adversely impact the morning push
isn`t fun enough, round 2 will likely impact the evening push.
/OUTLOOK FOR KMSP/
TUE...MVFR/-SHRA likely in mrng. Wind NW 10-20 kts.
WED...VFR, chc MVFR/-SHRA late. Wind SSE 10-15 kts.
THU...MVFR, chc -SHRA. Wind NW 10-20 kts.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...None.
WI...None.
&&
$$
UPDATE...MPG
DISCUSSION...JRB
AVIATION...MPG
Area Forecast Discussion
National Weather Service Marquette MI
725 PM EDT Sun Apr 27 2025
.KEY MESSAGES...
- Rain and snowmelt will continue to lead to rises on area
rivers and possible minor flooding on typically flood-prone
rivers, especially early to mid week as a strong low pressure
brings additional rainfall to the area.
- An active and warmer pattern is expected through Monday. Some
strong to severe thunderstorms are possible (30% chance), with
severe hail and wind gusts being the main threats.
- There is a non-zero chance for flash flooding across our area
Monday into early Tuesday morning, with the highest chance of
occurrence currently over the west (around 5% according to
WPC).
- Southerly gales to at least 35 knots are expected between
Marquette and Grand Marais Monday afternoon into Monday
evening. North to northwest gales of 35 knots possible Tuesday
over at least north central and eastern Lake Superior.
- RHs into the 20 percents are possible Wednesday as a dry high
pressure moves through the area.
&&
.SHORT TERM /THROUGH TONIGHT/...
Issued at 111 PM EDT Sun Apr 27 2025
We remain in the proverbial "calm before the storm" so to speak the
rest of today and tonight as increasing cloud coverage from the west
moves in as a low over the Plains approaches. As warm air advection
has begun over the area, observing stations are already showing weak
southerly flow over the U.P. early this afternoon. As the warm front
of the low continues to advect warmer and more moist air into the
region, expect the southerly winds to progressively increase with
time the rest of today through tonight. With cloud cover being less
than what I`ve been expecting previously, we may see high
temperatures sneak into the mid 60s across most of the area today;
thus, I may need to revisit my high temperature forecast from this
morning. In addition, with RHs are getting down into the mid to
lower 30 percents in the interior areas early this afternoon, expect
them to drop down even further in the interior east and interior
west later this afternoon; expect the interior east to drop down
into the mid 20 percents and the interior west to drop down to
around to just below 30 percent this afternoon before improving this
evening and overnight.
While neighboring radars are showing returns over the central and
western U.P. early this afternoon, it appears nothing is reaching
the sfc based off of the observing stations and high cloud bases
(lower levels evaporating any precipitation before it reaches the
sfc). Expect this trend to continue through the rest of this
afternoon through the overnight hours, although with more moist air
from the Gulf being advected in, expect the cloud bases to lower,
with the Ironwood area possibly seeing some light rain
showers/thunderstorms beginning late tonight/early Monday morning.
With cloud cover and warm air advection increasing tonight, expect
the low temperatures to get down into to around 40 in the east to
around 50 in the west, with locally warmer temperatures in the
downslopes by the Lake Superior shoreline.
&&
.LONG TERM /MONDAY THROUGH SUNDAY/...
Issued at 355 PM EDT Sun Apr 27 2025
The main event begins Monday as showers and thunderstorms enter into
the western U.P. during the early morning hours. With the severe
weather threat not looking to materialize until the afternoon and
evening hours as the LLJ approaches from the southwest, these storms
could (hopefully) use up the energy that`s already in the atmosphere
and keep the severe weather further south and out of our area.
Another way we could avoid severe weather Monday and Monday night is
if a convective complex develops over Wisconsin or Iowa (or even
further south) beforehand; if this occurs, then the warm and moist
air from the Gulf will be hit that convective complex like a wall,
and we will only have worked-over air to deal with, significantly
decreasing our severe potential to possibly nothing! However,
should these possibilities not occur (especially the second
scenario), then severe hail and winds are on the table as the warm
sector of the low sets up shop over us. While there looks to be a
strong temperature inversion in the lower levels of the atmosphere
thanks to the warm front of the low advecting air in from the south,
some breezy conditions are still expected at the sfc, with Munising
possibly gusting up to at least 40 mph during the afternoon and
evening hours via southerly downsloping winds. Besides the winds,
the ARW and NAM4km show a line of thunderstorms moving through the
western U.P. beginning Monday afternoon; meanwhile, the HRRR keeps
the convective mode discrete until a potential QLCS moves through in
the evening and overnight hours (the ARW and FV3 show this as well).
While the CAMs do show storms weakening as they travel eastwards
Monday and Monday night, with a LLJ moving in and providing ample
shear to the atmospheric profile, storms are likely be sufficiently
tilted for mesocyclone maintenance, and thus could keep going until
the convection is out of our area. While tornadoes are not expected,
an isolated tornado or two now cannot be completely ruled out near
the Wisconsin border as the cold front moving in during Monday
evening and overnight hours could provide some much needed low-level
helicity and an unstable profile near the sfc of the impressive
frontal boundary, with this being the greatest further west in the
U.P.. Expect the severe threat to end behind the cold front this
evening as it pushes from northwest to southeast with time.
In addition to the severe weather, we have a low (around 5%
according to WPC) chance of seeing isolated flash flooding problems
over the area Monday and Monday night, mainly over the west. With
ensemble guidance highlighting PWATs getting up to the 99th
percentile of modeled climatology (1.25 to possibly even 1.50
inches), all that`s need is training storms in order to get flash
flooding to occur. However, given the high uncertainty regarding the
location and placement of rain showers and storms (as well as
convective mode during the day Monday), pinpointing when and where
it will happen (and that`s a BIG IF) is a mystery at this point. If
it does occur, it would most likely occur over the western U.P.
where the better storm environment is. Regardless, even if we do not
get flash flooding out of this event, we could still see river rises
across the area as some spots could see a soaking rainfall. This may
create minor river flooding in some spots across the U.P. as we move
into Tuesday and Wednesday. However, uncertainty on this is also
high at this time given that convection will mainly be forced at the
mesoscale level until the cold front pushes through Monday evening
(unlike the synoptic rainfall expected over the Northland early this
week).
Behind the cold front, expect a dry slot to move through the area
before the wrap-around moisture of the low hits us Tuesday morning
and brings additional light rain and snow showers back across the
area. Given that temperatures are expected to remain above freezing
on Tuesday, no snowfall accumulation is expected. With high pressure
quickly moving in Tuesday night, expect the precipitation to end
across the area by early Tuesday evening, with the far east holding
onto the rain and snow showers last.
Calm and fairly pleasant weather is in store for us Wednesday, with
winds being light and high temperatures generally getting into the
50s. However, with ensemble guidance showing PWATs below the 10th
percentile of modeled climatology, we could see min RHs drop down
into at least the 20 percents by the afternoon; this will need to be
monitored in the future as some elevated fire weather concerns could
be realized due to conditions being so dry with the airmass,
especially if we get skunked on the rainfall with this upcoming
system. The saving grace for Wednesday though is that winds are
expected to be light.
Additional rains showers are expected to move over us late this week
as a weak shortwave from Canada phases with a stronger low lifting
through southern Lower Michigan into northern Quebec. We could see
some snow mix down to the sfc in the wrap-around moisture/phasing
inverted trough, but uncertainty on that remains high at this time.
Behind this, a rex block moves from the Plains into the Ohio Valley.
Should the rex block be south enough, we could see some shortwaves
bring additional rain showers over us next weekend; if not, then
expect dry weather.
&&
.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 725 PM EDT Sun Apr 27 2025
VFR conditions and breezy winds will linger this evening. While VFR
conditions continue overnight, winds should subside as we decouple.
Upper level winds are strong enough to pose a low level wind shear
threat, but its marginal. With low confidence, opted to leave it out
of this TAF. Monday, at least 2 rounds of thunderstorms will build
into the area. The first looks to press into KIWD late morning/early
afternoon, then lift northeast. The second follows after this
period. Scattered showers or thunderstorms may develop between the
two rounds. Confidence is lacking on exact placement of storms, so
prob30s were included. Ceilings are expected to fall to MVFR after
the first wave, potentially to IFR at KIWD. In addition to the
thunderstorm potential, strong low level winds will support wind
gusts upwards of 30kts and low level wind shear, even in the absence
of thunderstorms.
&&
.MARINE...
Issued at 355 PM EDT Sun Apr 27 2025
The light winds of 20 knots or less this afternoon increase from the
south tonight into Monday, eventually becoming southerly winds of 20
to 30 knots over the eastern half of the lake by Monday afternoon,
with a gales of 35 knots or greater expected along the southerly
nearshore from Marquette to Grand Marais, MI during the afternoon
and evening. As a low lifts from the Plains into the lake Monday
evening before exiting into Canada overnight, expect the winds to
become north to northwesterly behind the low`s passage, with gales
of 35 to 40 knots being seen across the north central and eastern
lake Tuesday. With high pressure building in quickly behind the low,
expect winds diminish back down to 20 knots or less again as early
as Tuesday evening. The light winds continue into this upcoming
weekend.
Expect thunderstorms to move into the lake Monday and to continue
into Monday night. A few of these storms could bring severe hail and
winds to the sfc, with the SPC showing a Slight Risk (15% chance or
more) of severe weather over most of the lake Monday and Monday
night.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
Gale Watch from Tuesday morning through Tuesday afternoon for
LSZ242>245.
Gale Watch from Tuesday morning through Tuesday afternoon for
LSZ248-265.
Gale Warning from 2 PM Monday to 2 AM EDT Tuesday for LSZ249-
250.
Gale Watch from Tuesday morning through Tuesday afternoon for
LSZ249>251-267.
Gale Watch from late Monday night through Tuesday afternoon
for LSZ263-264.
Gale Watch from Tuesday morning through Tuesday afternoon for
LSZ266.
Lake Michigan...
Gale Watch from Monday afternoon through late Monday night for
LMZ248-250.
&&
$$
SHORT TERM...TAP
LONG TERM...TAP
AVIATION...JTP
MARINE...TAP
Area Forecast Discussion
National Weather Service Morristown TN
907 PM EDT Sun Apr 27 2025
...New UPDATE...
.UPDATE...
Issued at 906 PM EDT Sun Apr 27 2025
Forecast on track this evening with no big updates. Updated hourly
temps and dewpoints to match up with latest obs.
&&
.SHORT TERM...
(This evening through Monday)
Issued at 205 PM EDT Sun Apr 27 2025
Quiet weather this period. High pressure over OH today will shift
east and be located near the Mid-Atlantic coastal region tomorrow,
which will result in a southerly low level flow across the
Southern Appalachians and TN Valley. At 850-700 mb, we will see
that southerly flow bring some higher theta-e air and weak
isentropic lift. The HRRR produces a few isolated showers during
the day, but forecast soundings appear strongly capped. The
forecast will have a dry day. The southerly flow will bring warmer
temperatures in the upper 70s to lower 80s for most locations
outside the mountains.
&&
.LONG TERM...
(Monday night through next Sunday)
Issued at 205 PM EDT Sun Apr 27 2025
Key Messages:
1. Above normal temperatures through Friday. Slightly cooler (near
normal) temperatures next weekend.
2. Rain chances return Tuesday, showers likely on Friday with a
frontal passage.
Discussion:
A ridge of high pressure over the Gulf through the mid and upper
level will build across the region on Tuesday, resulting in
temperatures rising above normal, into the 80s. With the surface
flow remaining southerly, increasing moisture in the boundary
layer will bring some diurnal rain chances. This setup continues
with little change for Wednesday and Thursday. Northern sections
will have a higher PoP than southern sections due to the Gulf
ridge and weak disturbances passing by on the northern edge of the
ridge.
A deeper trough digs into the Plains late in the week, which
begins to affect our area on Friday with better rain chances and
a chance of thunderstorms. Too early to assess the potential for
severe storms at this time, but it will be something to keep an
eye. Behind the cold frontal passage Friday/Friday night,
temperatures will return closer to normal for next weekend, with
highs mainly in the 70s.
&&
.AVIATION...
(00Z TAFS)
Issued at 715 PM EDT Sun Apr 27 2025
VFR conditions through the period at all sites.
&&
.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN 57 81 61 81 / 0 0 0 10
Knoxville McGhee Tyson Airport, TN 54 81 58 82 / 0 0 0 20
Oak Ridge, TN 54 80 58 82 / 0 10 0 30
Tri Cities Airport, TN 51 77 53 80 / 0 10 0 30
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...NONE.
VA...NONE.
&&
$$
SHORT TERM...
LONG TERM....DGS
AVIATION...
Area Forecast Discussion
National Weather Service Omaha/Valley NE
649 PM CDT Sun Apr 27 2025
.KEY MESSAGES...
- There`s a 5-10 percent chance of severe weather in northeast
Nebraska overnight, with the main hazards being large hail and
damaging winds.
- Severe weather is likely along and east of a front Monday
afternoon and evening. Exact frontal location and storm
coverage remain uncertain. Any storms that do develop will be
capable of destructive hail, damaging winds, and tornadoes.
- Dry weather for Tuesday, but rain chances are back in the
forecast for Wednesday and Thursday.
&&
.DISCUSSION...
Issued at 234 PM CDT Sun Apr 27 2025
Rest of this afternoon through tonight...
Early afternoon mesoanalysis showed a deepening lee cyclone over
northeast CO, with gusty southeast winds to the east of that
feature advecting an increasingly moist low-level air mass into
the central Plains. That moisture has contributed to widespread
cloud cover as of midday across the area, with visible satellite
suggesting we could see a few cloud breaks this afternoon.
Latest CAM data are in reasonably good agreement in suggesting
the development of diurnally enhanced thunderstorms later this
afternoon across portions of western NE. A subset of those
storms may persist into tonight as moist, unstable inflow is
enhanced by the development of a 50+ kt low-level jet.
Considerable model variability exists in the coverage and
location of the nocturnal storms, with only the 12z NSSL-WRF
indicating simulated reflectivities moving through northeast NE
after midnight. Forecast soundings ahead of that activity depict
a favorable overlap of moderate instability and relatively
strong vertical shear. As such, a conditional --albeit low--
threat for isolated severe weather (in the form of damaging
winds and/or large hail) exists overnight, mainly in northeast
NE. Otherwise, the models indicate only low-reflectivity
structures that are probably indicative of drizzle or light
showers.
Monday and Monday night...
Areas of light showers could persist Monday morning, aided by a
zone of strong warm advection and moisture flux along the low-
level jet. By afternoon, decreasing clouds coupled with
steepening lapse rates and boundary-layer dewpoints in the 60s
will yield a moderately unstable air mass ahead of the Pacific
front/dryline advancing east through the area. The 12z models
continue to indicate various positions of the front by mid to
late afternoon when thunderstorm development is expected. These
variations are likely due to different boundary-layer mixing
schemes present in the models. For example, the NAM Nest and
NSSL-WRF indicate the western-most scenario along a Sioux City
to Lincoln to Fairbury line. In contrast, the HRRR and RAP,
offer the eastern-most scenario along a Harlan to Shenandoah to
Falls City Line.
Another interesting aspect of this forecast is either the
absence of CAM-simulated thunderstorms along the front in our
area, or the quick dissipation of any CAM-simulated storms. We
suspect that a combination of weak convergence along the front
coupled with the deleterious effects of dry-air entrainment on
the simulated updrafts are contributing to this model behavior.
Synoptically, the 12z parametrized models indicate the trailing
edge of meaningful 500-mb height falls (implied forcing for
ascent) overspreading the Pacific front during the time of peak
heating. Moreover, model soundings suggest that the capping
inversion across the warm sector will not be overly strong. And
while it appears that convergence along the Pacific front will
be relatively weak, the above factors suggest that isolated
thunderstorm formation and maintenance are more probable that
what the current CAMs indicate.
The moderate instability combined with 50-60 kt of deep-layer
shear will support rapid supercell evolution with any storms
that develop. Destructive hail greater than 2" in diameter is
possible, as are locally damaging wind gusts, and a few
tornadoes. Veered low-level winds and resultant, smaller SRH
may limit tornado intensity in our area, especially in the
eastern-most frontal scenario mentioned above. A potentially
greater, significant tornado risk could materialize in the 6-9
PM timeframe in western IA, should the western-most frontal
scenario play out.
A secondary area of strong to severe thunderstorm development
could materialize Monday afternoon into evening in northeast NE,
near the SD border. The presence of steep low/mid-level lapse
rates and modestly strong vertical shear will support some
storm organization, with damaging winds and large hail being the
main hazards.
Any storms that develop in either of the two above-mentioned
regimes are expected to move out of our area by mid to late
evening.
Other potential hazards on Monday are strong south winds with
gusts up to 40 or 45 mph, both ahead of and behind the Pacific
front. The strong winds will coincide with a rapidly drying low-
level air mass to the west of the Pacific front, resulting in
areas of high to potentially very high fire danger. The recent
rainfall has contributed to considerable fuel greenup, and as
such, we are not planning any fire-weather headlines.
Tuesday through Saturday...
The 12z global models continue to indicate the progression of a
multi-stream trough through the central U.S. Wednesday and
Thursday, and that is reflected in increased precipitation
chances during that timeframe. The best measurable precipitation
chances (peak PoPs of 40-70%) are on Wednesday. High temperatures
will be mainly in the 60s and 70s with Saturday potentially
being the warmest day with readings in the mid to upper 70s.
&&
.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 648 PM CDT Sun Apr 27 2025
Widespread MVFR with a few pockets of IFR were seen across the
forecast area at the start of this TAF period. Ceilings will
continue to deteriorate throughout the nighttime, reaching
widespread IFR after 2z. Have included more lines to approximate
the timing and any CAC changes, but expect amendments to be made
as needed. Ceilings will improve to MVFR around 10-14z at KOFK
and KOMA, and will improve slightly earlier around 8z at KLNK.
VFR conditions are expected by the late morning to afternoon
hours.
A slight chance for rain/drizzle exists along a line from KHJN
to KOLU to KLCG through about 12z. However, confidence in any of
our TAF sites seeing direct impacts is low, so have not included
any mentions for this issuance.
Winds will remain gusty throughout the TAF period from the
southeast at 15-20 kts with gusts up to 30 kts. Winds will switch
to the southwest by the afternoon hours.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...None.
IA...None.
&&
$$
DISCUSSION...Mead
AVIATION...Castillo/McCoy
Area Forecast Discussion
National Weather Service Topeka KS
609 PM CDT Sun Apr 27 2025
.KEY MESSAGES...
- Isolated severe storms are possible this evening over portions of
central and north central Kansas with large hail and damaging winds
being the main hazards.
- A large upper level system moves into the region Monday,
increasing the risk for severe storms across eastern Kansas Monday
afternoon and evening. All modes of severe weather will be possible.
- Rain and storm chances persist over much of next week as a
frontal boundary stalls near the I-44 corridor.
&&
.DISCUSSION...
Issued at 226 PM CDT Sun Apr 27 2025
19Z surface analysis shows low pressure along the lee of the ROckies
from eastern Wyoming into New Mexico. Dry line still remains from
near AKO to just east of LHX. Mid level low/ trough was located over
Nevada into southern California and was progressing slowly eastward
this afternoon. Visible satellite showed continued clearing over
western Kansas and into parts of north central Kansas this
afternoon. Meso analysis shows airmass destabilizing east of the
dryline in western Kansas along with convergence near the dryline.
An isolated storm or two may develop from west Texas into northwest
Kansas by early evening per CAMS. HRRR still tries to develop a
storm or two early this evening in central Kansas and if they do
develop the environment would be favorable for a strong to severe
storm with hail the main hazard. Confidence remains low for storms
to move into north central and central Kansas later this evening as
much of the forcing and instability will remain focused into
western Kansas.
On Monday, a vigorous wave and associated jet will move out into the
Plains. The energy from the southwest mid level trough will eject
from New Mexico into Nebraska while phasing with a northern stream
trough across the Dakotas. Ahead of the dryline a capping inversion
should hold for much of the day, then erode by 00Z-01Z. Forecast
soundings show some curvature in the hodographs with veering winds
in the low levels, allowing for storms to ingest streamwise
vorticity. Main hazards still look to be large hail and damaging
winds, a few tornadoes will also be possible. Cells will be discrete
and take on supercell Characteristics, but look to remain isolated
in eastern Kansas. Threat will continue through the evening hours.
The pacific front will make its way through the cwa Monday night as
it overtakes the dryline. Temperatures look to warm into the 80s on
Monday.
Tuesday the frontal boundary sets up southeast of the area across
southwest Missouri into Oklahoma where best chances for
destabilization and convection will be located. Increasing low level
isentropic lift and theta-e advection over the frontal boundary will
lead to elevated showers and storms Tuesday night focusing across
southeast and east central Kansas. Some locally heavy rainfall will
be possible for areas south of I-35.
An approaching mid level trough moving into the southern and central
Plains on Wednesday will keep showers and a few storms in the
forecast, focused mainly across northeast and east central Kansas
where the best moisture convergence will be located as the main
trough moves east into the Plains. Precipitation chances continue
through Thursday evening. Friday will be dry with a a return of
elevated showers and storms late Friday night into Saturday with
increasing low level jet and a minor wave ejecting northeast into
Kansas. Scattered showers and storms will continua into Sunday with
mass response ahead of a large mid level trough moving into the
Rockies. Most day will be in the 70s for highs for much of the week.
Last discussion for my career today for the area, it`s been a
great run.
&&
.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 603 PM CDT Sun Apr 27 2025
IFR conditions at the current hour are expected to improve to
MVFR from 02-03Z as southerly low level winds increase from 10
to 15 kts sustained, gusting to near 20 kts overnight. LLWS is
marginal given that gusty sfc winds veer to the south while the
LLJ at 2 kft increases around 50 kts after 08Z. South sfc winds
increase over 20 kts sustained after 15-18Z while latest
HRRR/RAP scatter the MVFR cloud deck by the afternoon.
Confidence for any TSRA at terminals is too low for mention at
this time.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
DISCUSSION...53
AVIATION...Prieto