Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/02/24
AREA FORECAST DISCUSSION
National Weather Service Albany NY
929 PM EDT Mon Apr 1 2024
.SYNOPSIS...
As high pressure builds east across Quebec, a warm front and
low pressure system south of our region start to approach
tonight bringing thickening clouds then increasing chances of
rain on Tuesday. A developing complex storm system will bring
rain, mixed precipitation and snow for the mid week with
significant snowfall possible, especially over the higher
terrain late Wednesday through Thursday.
&&
.NEAR TERM /THROUGH TUESDAY/...
UPDATE...As of 920 PM EDT, cold front currently located just
north of the Mohawk River in Saratoga County extending into the
eastern Mohawk Valley, and settling southward. Behind the
front, dewpoints drop off into the mid 20s to around 30, along
with a brief surge of gusty north/northeast winds, while south
of the front, temps remain in the mid 40s to lower 50s with
dewpoints in the 30s along with light west to southwest winds.
This boundary will continue settling southward overnight,
allowing winds to shift into the north/northeast, along with
slightly drier air pressing southward.
Skies have become clear to partly cloudy across most of the
region, and expect a period of mainly clear skies over the next
few hours, especially areas south of I-90. Some clouds near the
aforementioned front will develop at times, especially across
southern VT/northern Berkshires, and eventually closer to the
eastern Catskills.
Otherwise, no significant changes with this update other than
trending temps/dewpoints to current obs.
[PREVIOUS 400 EDT]...Mostly cloudy skies in place south of
Albany, with partly/mostly sunny to the north. A weak
disturbance continues to push south/east of the region through
late this afternoon. High pressure will start to build east from
south end of Hudson Bay into N. Quebec tonight, while a warm
front starts to lift north into the Ohio Valley and mid Atlantic
regions. So there should be plenty of high/mid level clouds
around, although some breaks will occur north of Albany. Most of
the area should be dry, although will mention slight chance of
rain developing in the far southern part of the area towards
daybreak. Lows will be coldest across higher terrain and
northern areas, ranging from the upper 20s to upper 30s.
On Tuesday, the west-east oriented front will slowly lift
northward as the flow pattern begins to amplify. The primary
cyclone will be tracking northeast across IL/IN while a weaker
cyclone develops near or just south of the Delmarva.
Moisture/lift from this system will be battling drier air
associated with high pressure to the north, with ridging
extending south/west from New England into the eastern NY. So
the best chances for precip will be for areas from around the
Albany and the I-90 corridor south/west, with mainly dry
conditions to the north/east. Temperatures look to be warm
enough for plain rain, except for some higher peaks of the
Catskills where some snow may occur. Highs should be mainly in
the 40s to lower 50s, with some 30s in mountain areas.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
Winter Storm Watch issued for the western/southern Adirondacks,
southern Vermont, northern Berkshires, eastern Catskills,
Helderbergs and Schoharie Valley from early Wednesday morning
through Thursday night...
Precipitation will expand north/east Tuesday night, as the
primary cyclone tracks into Michigan, while southeast winds
aloft strengthen and transport moisture northward along with
increasing isentropic lift through the night. A strengthening
low level northerly ageostrophic wind component will result in
colder air advecting southward beneath the warming aloft. So
this setup look to result in rain changing to sleet in the S.
Adirondacks and S. Greens, and possibly the Helderbergs,
Taconics and Berkshires, with plain rain elsewhere.
The northerly low level ageostrophic wind is forecast to
strengthen further on Wed, which will continue to deepen the
colder air beneath the warm nose aloft. This should result in
rain to sleet expanding south from the Adirondacks/Greens to the
Helderbergs, E. Catskills, Berkshires during the day. Sleet
could change to snow during the afternoon in parts of the S.
Adirondacks. NAMNest indicating sleet/snow potential at this
time, although we are not yet in the time window for the HRRR
and other HREF components just yet so details will be refined
further later in time. High temperatures may occur during the
first half of the day (30s to lower 40s), with temperatures
falling during the afternoon as wetbulb effects occur.
Potentially strong winds may develop in the downslope areas of
the S. Greens, Berkshires and Taconics starting Wed afternoon
and evening as the E-SE jet strengthens. There will be a strong
inversion developing too, so it will depend on how much wind can
mix down beneath the inversion. Wind gusts may exceed Advisory
level in some areas, but with such a strong (60-80 kt) jet just
above the inversion level there is some potential for > 58 mph
gusts. Will continue to monitor trends.
Guidance indicating the coastal cyclone intensifies near or
just north of the Delmarva late Wed into Wed night, ahead of a
sprawling upper level low tracking east into IN/OH. The Wed
night to Thu time frame is when the most impactful winter
weather is expected, with significant snowfall in the higher
terrain and possible accumulating snow into lower elevations as
well. As the coastal cyclone tracks NE along or near the S. New
England coast, this is when the most significant QPF should
occur. U-component wind anomalies of -3 to -4 STDEV signals
strong east/southeast flow with continued moisture transport.
Colder air aloft will filter in Wed night into Thu as the core
of upper low tracks east across PA/NY. This is when rain could
change to snow even across most lower elevations. Lower
elevation accumulating snow potential is the most uncertain part
of the forecast at this time. Also how much sleet vs. snow
accumulates in the S. Greens and Berkshires is also uncertain,
with the 12z NAM indicating more sleet than snow. In the
transition zone between rain and sleet, some freezing rain is
possible but probs are rather low at < 20%.
We have noted there is significant spread in the LREF (long
range ensemble forecast) between the 25th and 75th percentiles.
Probs from the ECMWF for > 6" snow still highest > 70% over the
S. Adirondacks and S. Greens, although > 50% across most other
higher terrain areas. GFS ensemble probs are similar, although
slightly greater. Probs for > 3" snow are in the 30-50% range
from around the Capital District northward in the Hudson Valley,
with lower probs south.
The Winter Storm Outlook(probability of exceeding 7" snow) from
the Weather Prediction Center in the 2-4 day period shows > 80%
probs across most of the S. Adirondacks and S. Greens, with
50-80% probs for the rest of the higher terrain areas west/east
of the Hudson Valley. So there is fairly high confidence for
significant snow across higher terrain areas at this time range.
A Winter Storm Watch has been issued for all these areas due to
the high potential for > 7" snow along with some sleet.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
Long term period begins at 00z Friday with the upper low
spinning over our region and the surface low sitting just
northeast or east of Cape Cod. While there is still some
uncertainty in the exact position of the upper and surface low,
their proximity to the region will result in periods of snow
showers across the region, especially in the northwest upslope
areas where up to a few more additional inches of snow
accumulation is possible. The best chance for snow showers will
be Thursday night and Friday. Snow may mix with rain in some
valley ares Friday with diurnal warming. Coverage of
precipitation should gradually decrease in coverage Friday night
and especially on Saturday as the upper low and surface low
track off to the east and we get away from the moist cyclonic
flow aloft. With the upper low around, temperatures will run on
the cool side for the first half of the long term.
Saturday night through Monday...As the storm system pulls away
to our east, upper ridging amplifies over the center of the
country. High pressure develops on the downstream side of the
ridge near/north of the Great Lakes, and may move into our area
towards the end of the long term period. This will result in
much drier conditions and a warming trend in temperatures. While
the solar eclipse is still too far away for specific details,
conditions could end up favorable for viewing the eclipse if the
upper ridging and surface high remain over/near our area as
some of the long-term guidance suggests.
&&
.AVIATION /01Z TUESDAY THROUGH SATURDAY/...
Through 00Z/Wednesday...VFR conditions expected overnight
at all terminals with occasional bkn-ovc mid-level clouds at
6-10 kft.
Rain will slowly spread from south to north during Wednesday,
reaching KPOU between 13Z-16Z/Tue, KALB and KPSF between
17Z-20Z/Tue, and KGFL after 20Z/Tue. A few pockets of moderate
rain may occur after 22Z/Tue at KPOU, KALB and KPSF. Some snow
may also mix in at KPSF toward or after 00Z/Wed.
Vsbys initially will be VFR, however MVFR Vsbys may develop
within any areas of moderate rain. Cigs should trend to MVFR
from south to north as well once steadier rain develops,
although may not occur until after 00Z/Wed at KGFL.
Light south to southwest winds 3-6 KT will become north to
northeast at 4-8 KT by midnight and will persist through Tuesday
morning. Winds will then veer slightly into the east to
northeast and increase to 5-10 KT by Tuesday afternoon.
Low level wind shear may develop at KPSF after 22Z/Tue as east
to southeast winds increase to 30-35 KT at 2000 FT AGL, while
surface winds remain east to northeast at 10 KT or less.
Outlook...
Tuesday Night: High Operational Impact. Definite RA.
Wednesday: High Operational Impact. Breezy. Definite RA.
Wednesday Night: High Operational Impact. Breezy. Definite RA...SN.
Thursday: High Operational Impact. Breezy. Definite RA...SN.
Thursday Night: Moderate Operational Impact. Chance of SHSN.
Friday: Moderate Operational Impact. Chance of SHRA...SHSN.
Friday Night: Moderate Operational Impact. Chance of SHRA...SHSN.
Saturday: Low Operational Impact. Breezy. NO SIG WX.
&&
.HYDROLOGY...
Flooding is generally not expected this week due to the long
duration of precipitation and a significant portion being frozen
(sleet/snow) over the higher terrain. However, due to
increasing and persistent southeast flow minor flooding due to
tidal effects are expected to develop at and in vicinity of
Poughkeepsie along the Hudson River by early Wednesday morning.
Flooding may also occur during subsequent tidal cycles.
For details on specific area rivers and lakes, including observed
and forecast river stages and lake elevations, please visit the
National Water Prediction Service /NWPS/ graphs on our website.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...Winter Storm Watch from Wednesday morning through late
Thursday night for NYZ032-033-042-047-051-058-063-082.
MA...Winter Storm Watch from Wednesday morning through late
Thursday night for MAZ001.
VT...Winter Storm Watch from Wednesday morning through late
Thursday night for VTZ013>015.
&&
$$
SYNOPSIS...JPV
NEAR TERM...KL/JPV
SHORT TERM...JPV
LONG TERM...Main
AVIATION...KL/Picard
HYDROLOGY...JPV
Area Forecast Discussion
National Weather Service Dodge City KS
607 PM CDT Mon Apr 1 2024
.KEY MESSAGES...
- Strong weather system will bring widespread showers and a few
thunderstorms to southwest KS this afternoon into the
overnight hours.
- a brief switch to wet snow is likely early Tuesday morning,
but impacts will be minimal.
- Dry, warming trend daytime Tuesday through the end of the work
week.
- Next weather system looks to take aim at the central plains
over the weekend.
&&
.SHORT TERM /THROUGH TUESDAY/...
Issued at 200 PM CDT Mon Apr 1 2024
Latest water vapor satellite imagery and RAP upper air analysis
reveals a large, positively tilted trough over the western
CONUS, with an embedded vorticity max rounding its base over
southern NM. Ahead of this wave, a surface low was centered
over far northeast KS, with southwest KS already in the wake of
its trailing cold front. As the upper level trough continues
sliding east, short range guidance suggests the embedded
shortwave impulse will eject to the northeast, passing just
south of our area. Given the strongest mid-level deformation
resides just to the northwest of an ejecting impulse, this path
is nearly ideal for precipitation across southwest KS. Indeed,
the 12Z HREF shows widespread showers and a few thunderstorms
beginning around 21-22Z over our far southwest zones, expanding
in coverage with time and leaving a large swath of 0.25-0.75" of
QPF by 12Z Tuesday along and south of a Johnson City-Larned
line, with the highest amounts along the KS/OK border. The
majority of this precipitation will fall as rain, but a
combination of strong cold advection behind the front and
adiabatic cooling will likely facilitate a switch to wet snow
during the early morning hours Tuesday, however little to no
impacts are expected. Tuesday morning, all precipitation will
exit stage right by 15Z, with lows in the 30s.
Daytime Tuesday, overcast skies will gradually erode from west
to east as the upper level trough axis passes overhead, with all
zones under mostly clear skies by mid-afternoon. The strong
early April sun will aid in afternoon highs reaching the upper
50s/low 60s, but northerly winds in the 20-25 mph range gusting
to 35 mph will make it feel cooler.
&&
.LONG TERM /TUESDAY NIGHT THROUGH MONDAY/...
Issued at 200 PM CDT Mon Apr 1 2024
The rest of the work week will feature a dry, warming trend as
medium range ensembles suggest upper level ridging will build
over the western CONUS Tuesday night into Wednesday in the wake
of the upper level trough, move east with time and pass
overhead daytime Friday. Afternoon highs will steadily increase
from the low/mid 60s on Wednesday to the mid/upper 70s on Friday
with little fanfare. Daytime Saturday, ensembles indicate a
powerful, negatively tilted upper level trough will eject onto
the High Plains. If this were to happen in late May, we would be
talking about high-end severe weather potential, but
thankfully, limited moisture return will likely prove to be a
significant mitigating factor. That said, thunderstorms, some
potentially severe, are possible Saturday afternoon and evening
as EPS/GEFS probability of exceeding 0.1" of QPF are already in
the 40-60% range for roughly the eastern half of our area.
&&
.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 603 PM CDT Mon Apr 1 2024
A large storm system will move through the central and southern
plains for tonight providing all the terminals with extensive
cloud cover through the night and morning hours. MVFR flight
category will be the most likely cloud conditions as ensembles
have 70-100% chance of MVFR flight categories for all terminals.
A band of rain showers and potentially some brief mixtures of
snow will move in the vicinity of GCK, DDC, and LBL between
03-09Z. Most of the precipitation should be out of the area by
sunrise Tuesday morning. Cloud ceilings should also increase
after 18Z as the system moves out and VFR flight categories
should be the result between 18-00Z. Winds throughout the time
period will be strong at 15-25 kts with gusts around 30 kts.
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...Springer
LONG TERM...Springer
AVIATION...Tatro
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1146 PM EDT Mon Apr 1 2024
.KEY MESSAGES...
- An active weather pattern continues during the early to mid week
period as rain showers move back in tonight mainly along/south of I-
69. Rain expands in coverage Tuesday morning before becoming more
scattered latter half of the day. Scattered thunderstorms possible
Tuesday evening.
- The rain tonight and Tuesday morning precedes development of a
strong storm system that strengthens and then stalls overhead during
the mid week period.
- Scattered to numerous rain-snow showers Wednesday into Thursday.
No accumulation during the daylight hours, though Wednesday night
has a low chance to see minor grassy accumulations as lows fall to
near freezing.
- The low pressure system exits eastward by Friday leading to a dry
and slightly warmer weekend.
&&
.AVIATION...
A steady increase in low level moisture occurs through the period,
as a low pressure system advances into the region. Associated
reduction in cloud base expected overnight and early Tuesday,
resulting in MVFR to IFR restrictions as additional pockets of
showers develop at times. A period of widespread IFR likely
throughout Southeast Michigan for the afternoon hours, with
increasing potential for LIFR cigs and some visibility restrictions
as near surface saturation increases. Some increase in elevated
instability may offer a small window for thunderstorms to develop
late in the day, but confidence in occurrence remains very low.
Winds held firmly from the northeast tonight and Tuesday. Gust
potential largely limited by poor mixing, but flow off Saginaw Bay
brings a greater possibility at MBS at times.
For DTW...Expansive area of low stratus with prevailing northeast
wind through Tuesday afternoon. Low chance for a thunderstorm mid
afternoon through early evening Tuesday.
.DTW THRESHOLD PROBABILITIES...
* High for ceilings 5000 ft or less through Tuesday evening.
* Low for thunderstorms Thursday afternoon and early evening.
&&
.PREV DISCUSSION...
Issued at 324 PM EDT Mon Apr 1 2024
DISCUSSION...
Stationary frontal boundary remains draped from central Missouri to
central Ohio resulting in cooler, drier NE low level flow into SE MI
this afternoon. While this has supported sunnier early day skies for
most of the area, clouds will increase in coverage through the
remainder of the day as low pressure over Plains lifts northeast
along the stalled front towards the Great Lakes. Associated showers
expand over SE MI after 00Z this evening as elevated moisture
transport (mainly aoa 800mb) rides the frontal slope into southern
MI. Main instability pool holds well to the south over the Ohio
Valley, though soundings still suggest weak elevated instability
creeping north of the state line late this evening offering a slight
chance for a few rumbles of thunder in the far south. Otherwise,
consistent moisture transport beneath the right entrance region of a
northern Great Lakes jet streak should support a scattered to
numerous coverage of showers particularly south of I-69 tonight. For
areas north, while latest CAM runs have been more bullish in
maintaining scattered shower coverage through most of the night,
aforementioned dry northeasterly flow is expected to greatly cut in
rainfall intensities/amounts.
Frontal boundary begins to lift north late tonight-early Tuesday
offering the potential for any remnant overnight convection over the
mid-Mississippi to likewise lift into northern OH/southern MI and
bring a window for greater shower coverage/intensities for areas
south of M-59. Should this occur, a break in rain for these areas
would be increasingly plausible as a trailing convective subsidence
bubble would track through Tuesday afternoon. Conversely for areas
to the north, with the shift of the front, the elevated frontal
slope is progged to lift over the Thumb/central MI by late Tuesday
morning coinciding with a developing exit region of a secondary jet
streak over the Midwest. Result is a likely more persistent coverage
of showers throughout the day Tuesday. Low pressure undergoes rapid
occlusion as it reaches the Great Lakes with its cold/occluded front
lifting into SE MI Tuesday late afternoon-evening. Ample elevated
moisture will be in place across the area by this point- RAP 850mb
dewpoints forecast to be 8-11C which approaches record daily
maximums on sounding climatology, supporting another period of
scattered to numerous showers. Additionally this moisture supports
the generation of several hundred J/kg of elevated MUCAPE and
scattered thunderstorms. Some uncertainty in how far north the
surface warm front/surface instability reaches as a couple of CAM
solutions suggest it gets up to around the state line- SPC has placed
Lenawee and Monroe counties in a Day 2 marginal risk due to these
solutions. That said, current thinking is there`s a better shot that
the front holds just to our south preventing this instability from
getting into the CWA. Impressive dry slot then follows the frontal
passage Tuesday night into Wednesday morning bringing a lull in
precip for the area.
Occlusion process leads to the mid-level low becoming a closed,
cutoff circulation stacked with the surface low that slowly spirals
overhead Wednesday into Thursday as it gradually drifts eastward.
Off-on rain-snow showers can be expected throughout this period as
thermal troughing settles over the central Great Lakes with 850mb
temps falling into the upper negative single digits. Forecast
soundings still suggest boundary layer temps will be too warm both
daytime Wednesday and Thursday to support any accumulations.
Wednesday night looks to be the `best` shot for some areas to see a
minor accumulation, mainly on grassy surfaces, as low temps fall to
near freezing.
Low vacates the region by late Thursday allowing broad Canadian
surface high pressure to build in from the west. Thermal troughing
is slower to dislodge however with continuing northerly flow
maintaining below average temps through the end of the work week.
Pattern looks to shift by next weekend as ridging over the Plains
slides across the Great Lakes moderating temps back to at or above
normal.
MARINE...
Strengthening east/northeast winds will be the concern through the
mid week period as a strong low pressure system slowly tracks
through the region. This low will track along the stalled front
across the southern Great Lakes Tuesday before veering off to the
north and stalling over southern Lake Huron Tuesday night and
Wednesday and then slowly moving to the east away from the area
Wednesday night and Thursday. The low will strengthen to around
985mb with a strong easterly low level jet wrapping around the low
within the tight gradient. This will all lead to a long period of
Marine Hazards with Small Crafts and Gales across the region, mainly
Lake Huron. Could be a brief lull in winds Wednesday night as the
center of the low passes over the lake but winds then look to
increase again back to near Gales Thursday. We`ll hold off on any
headlines that far out and see how things trend moving forward for
now. Cool northerly flow then looks to hold over the region through
the end of the week.
HYDROLOGY...
An active period of rain showers continues tonight through mid week,
although the primary time period of heavier rain is expected tonight
and Tuesday. Rainfall totals of a quarter to a half inch are
possible tonight south of I-69 with a tenth to quarter inch to the
north. Totals Tuesday of quarter to half inch are possible across
southeastern Michigan with localized amounts near 1 inch. Coverage
becomes scattered Tuesday afternoon into Wednesday as the parent low
pressure system stalls over Lower Michigan. It is an active pattern
but the expected rainfall is spread out over enough time to minimize
flooding potential across SE Michigan.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...Gale Warning from 4 PM Tuesday to 10 PM EDT Wednesday for
LHZ361>363.
Small Craft Advisory from 4 AM Tuesday to 4 PM EDT Wednesday for
LHZ421-422-441.
Small Craft Advisory from 4 PM Tuesday to 5 AM EDT Wednesday for
LHZ442-443.
Lake St Clair...None.
Michigan waters of Lake Erie...Small Craft Advisory until 10 PM EDT Tuesday for LEZ444.
&&
$$
AVIATION.....MR
DISCUSSION...KDK
MARINE.......DRK
HYDROLOGY....BT/KDK
You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.
Area Forecast Discussion
National Weather Service Quad Cities IA IL
908 PM CDT Mon Apr 1 2024
.KEY MESSAGES...
- Periods of rain showers with scattered storms through
tonight.
- Severe weather chances have diminished for this evening with
mainly an isolated marginally severe hail threat south of I-80.
- Heavy stratiform rain is possible late tonight through
Tuesday, which may transition to a rain/snow mix across the
north already by Tuesday afternoon.
- Snow accumulations continue to look possible mainly Tuesday
night into Wednesday morning, but still some uncertainty on
amounts, snow rates, and surface accumulation potential.
Additionally, strong NW winds are expected Tuesday night and
Wednesday with gusts up to 45 mph.
&&
.SHORT TERM /THROUGH WEDNESDAY/...
Issued at 300 PM CDT Mon Apr 1 2024
Late Afternoon through Tonight
A developing area of low pressure was located over NW Missouri
early this afternoon with a surface warm front extending to the
east across northern MO into central/southern Illinois. This
places eastern Iowa and northwest Illinois on the cold side of
the boundary with steady east winds, a low overcast, and some
light fog (1 - 3 mile visibilities). The low will track to the
east-southeast into tonight, passing through southern Illinois
before heading northeastward on Tuesday toward NW Indiana.
Warm air and moisture advection north of the front will lead to
periods of showers and thunderstorms through tonight. Some of
these storms could be severe across the southern portion of the
outlook area, mainly south of Highway 34 where SPC has a Slight
Risk. The primary threats are large hail, damaging wind gusts,
and a low chance for an isolated tornado. The surface warm front
is forecast to shift to near the southern tier of counties late
this afternoon and evening, so there is potential for surface-
based storms in the far south with the convection remaining
elevated north of Highway 34.
Timing for Severe Storms:
The most likely window for strong to severe storms across the
south is between 5 PM to 10 PM. Latest CAMs and HREF UD
helicity probabilities peak during this period across the
southern tier of counties. Examination of forecast soundings and
hodographs definitely portray an environment conducive for
supercells capable of the aforementioned threats. SPC
mesoanalysis already has 1000-1500 MUCAPE across the south with
500 J/kg of MLCAPE nudging into far southern Scotland and Clark
Counties. Latest HRRR forecast soundings in far NE Missouri
show moderate low-level shear of 25+ kts and SRH over 100 m2/s2
(both in the 0-1 km layer).
The main uncertainty for tornadoes lies with whether or not
discrete convection can interact with the front before the
activity grows upscale. Any supercell that can latch onto the
front has potential to become tornadic in a favorable
thermodynamic environment characterized by very low LCLs and
dewpoint depressions of 5 F or lower.
Tuesday
A deep closed off upper low is forecast to wrap up over the
Western Great Lakes region as the strong surface low begins to
slow down and occlude over Lower Michigan. The local area will
be in the sweet spot for steady precipitation to redevelop
Tuesday AM, associated with a deformation band and zone of 850-700mb
frotogenesis. Expect widespread rain to last through the day,
and as cold air advection ramps up on the back side of the low a
transition to a rain/snow mix and even all snow is likely
across the north by Tuesday afternoon. Minor accumulations are
possible across far NW Illinois Tuesday afternoon, but with the
warm ground and temperatures holding above freezing, most of the
snow accumulation should hold off until Tuesday night into
Wednesday AM.
Rain Potential Today through Tuesday Afternoon: Total
precipitation amounts are forecast to reach 0.50 to 1.50 inches
over much of the area (heaviest south of I-80, lowest in the
NW).
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
Issued at 215 PM CDT Mon Apr 1 2024
Tuesday night...SREF blends paint a picture of a sub-990 MB sfc low
acrs far southwestern MI at 00z, slow-rolling or gyrating up acrs
the northwest portion of the state by Wed morning. With the upper
low west and southwest of that feature and closer to home here,
synoptically we should have a wrap around def zone precip shield
increasing acrs the area from the north-northwest as the night
progresses. Fcst soundings support the idea of an omega rich
environment top-down dynamically cooling the vertical profiles to
mainly wet snow parameters as the night progresses as well, while
the sfc layer remains in the low to mid 30s. Thus see a transition
to a mainly wet snow event for most of the area overnight and into
Wed morning, with increasing snowfall rates to 1 to 2 inches an hour
at times helping overcome mild sfc`s especially between 06z-15z Wed.
So there may be some snow accumulation by mid wed morning, with at
least a few inches possible in the stronger lift/dendritic layer
zone acrs far east central/northeast IA into far northwest IL, even
taking into account some melting/sublimation.
The Wed morning commute may be impacted by snow/wind reduced
visibility and some slush accum on travel sfc`s, especially elevated
ones. Early thoughts taking into account extent of lift, temp
profiles, "happy medium" SLR`s, and saturation is to advertise 1 to
2 inches of snow accum`s along and northeast of a line from Cedar
Rapids, to southeast of the Quad Cities, to northeast of Princeton
IL. 2 to 3 inches possible along/ north of a line from Manchester
IA, to MT Carroll IL. 3+ inches north of Freeport IL. Will then go
with just a wet dusting west and south of these accumulation areas
acrs most of the rest of the CWA. Will adjust POPs and QPF
accordingly. An winter weather advisory may eventually be needed for
portions of the area/NE IA into NW IL for a combo of snow/wind if
model trends continue.
Wednesday...Deterministic ensembles trending with a sub-990 MB sfc
low gyrating back acrs southwestern MI or southern LK MI by 18z Wed,
effectively arching tight cyclonic LLVL pressure gradient flow
pattern acrs the CWA. The upper low will look to move eastward acrs
IN and into OH through Wed night, but still enough influence to
produce snow showers or bands with some additional snow accums acrs
the area on Wed. NBM highs only reached with an afternoon lull in
the snow/graupel shower activity, but will still undercut the
blended highs. Even with marginal mixing, sfc winds may gust close
to or above advisory levels. H85 mb winds may approach 50 KTs.
Again, these brisk winds combined with falling snow and greatly
reduced visibility may warrant some type of winter wx headline/
advisory eventually for the day, something to keep in mind if the
signals persist.
Thursday and Friday...The latest ensembles continue to suggest large
near vertically stacked cyclone complex to continue to gyrate acrs
the eastern GRT LKS into the northeast Atlantic on Thu, with
effective omega block acrs the Rockies and western Plains. Thu still
a blustery cooler day probably held down below guidance even with
deep mixing, as well as a few linger snow/rain/graupel showers
skirting southward acrs the eastern CWA. Thu night, if we get
clearing and sfc wind decrease with sfc high edging down acrs the
upper to mid MS RVR Valley, this night could be the coolest of the
week with lows down in the 20s in some locations. Friday more under
the influence of both sfc and upper ridging for sunshine and
rebounding temps in the 50s.
Saturday and Sunday...Longer range ensemble and upper jet patterns
suggest the omega block to reign acrs much of the mid CONUS, with
generally dry conditions and moderating temps back into the 60s
through Sunday. Some chance for western-flank-of-ridge showers and a
few thunderstorms undercutting or battling omega ridge and sweeping
into and acrs the area late Sunday/Sunday night. ..12..
&&
.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 632 PM CDT Mon Apr 1 2024
A warm front sits across northern Missouri into central Illinois
this evening with widespread rain spreading northward into the
area this evening and continuing overnight. Scattered
thunderstorms are possible at KBRL and KMLI this evening and
placed a tempo group at both sites. Expect IFR to LIFR
conditions at all TAF sites tonight into Tuesday. Conditions
will remain LIFR to potentially VLIFR through at least 18 UTC on
Tuesday. However, once a cold front moves across eastern Iowa
and northwest Illinois during the afternoon ceiling and
visibilities may improve. Cold air moving into the area behind
the cold front may result in snow mixing with rain at KDBQ.
&&
.HYDROLOGY...
Issued at 900 PM CDT Mon Apr 1 2024
Recent rainfall combined with 1 to 1.5 inches of QPF in the
next 24hrs has resulted in river forecasts for portions of the
Rock, the Green, and the La Moine River to rise near or above
flood stage in the next 36-48 hours. Due to low confidence in
placement of the heaviest rain, have issued River Flood Watches
for Joslin, Geneseo, and Colmar this evening. If confidence
increases tomorrow morning that flood stage will be reached,
flood warnings will be issued.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...None.
IL...None.
MO...None.
&&
$$
SHORT TERM...Uttech
LONG TERM...12
AVIATION...Cousins
HYDROLOGY...Gross
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
632 PM CDT Mon Apr 1 2024
...New AVIATION...
.SHORT TERM...
(Tonight through Tuesday night)
Issued at 238 PM CDT Mon Apr 1 2024
Skies have cleared out west with some low and high clouds continuing
across the eastern two-thirds of the area early this afternoon.
Southerly flow is breezy at times with temperatures in the 70s and
80s. With the clearing out west, temperatures in the 90s and
possibly upper 90s may be possible out there late this afternoon. A
large trough axis remains to our west and lift associated with this
system is expected to arrive this evening at the same time as a
frontal boundary. This should allow for some isolated to scattered
showers and thunderstorms to develop. This should initially occur
over the northern Hill Country around 8-10 pm then possible spread
southeast throughout the remainder of the evening period. High-res
model soundings do some convective inhibition in place, but latest
runs of the HRRR show initiation. The convective environment would
be supportive of some large hail with steep mid-level lapse rates in
place. Shear values will also be supportive of organized convection
should thunderstorms initiate. Large hail and damaging winds would
be the main risk, but 0-3km SRH values do support a non-zero tornado
threat and can`t completely rule that out. Most of the high-res
models have the activity dissipating by 6z as they enter the Coastal
Plains with just some lingering non-severe showers and perhaps a
storm.
Once the boundary moves through the region, much drier air and some
west/northwest winds will filter into the area. Mostly clear skies
can be expected by tomorrow morning with lows reaching into the 50s
to middle 60s. Clear skies will continue into tomorrow with highs
reaching the 70s to lower 80s. Humidity values will drop to near 20
percent or less across areas west and south of I10/I37. This in
combination with breezy northwesterly winds at the surface should
create near critical to critical fire weather conditions mainly near
the Rio Grande. Will likely need a Grassfire Danger Statement or
perhaps a Red Flag Warning for some of the southwestern counties
tomorrow. With dry air in place and weakening winds, lows tomorrow
night will be on the cooler side in the 40s to near 50 degrees.
&&
.LONG TERM...
(Wednesday through Monday)
Issued at 238 PM CDT Mon Apr 1 2024
Seasonable and more comfortable weather trends through mid to late
week across South-Central Texas. Lower humidity levels will trend
under mostly clear skies. Northerly breezes diminish into Wednesday
afternoon before becoming light and variable from Wednesday night
into early Thursday. Winds become south-southeasterly towards late
Thursday and increase into and through the day on Friday. Friday
with the uptick in the southerly flow should see moisture and cloud
cover start to gradually increase. Lingering upper level energy
across the region into midweek becomes more strung out and should
have little if any impact to our sensible weather. No rain will be
expected through Friday. Areas out west closer to the Rio Grande
could see some elevated fire weather concerns in the afternoons but
wind speeds could stay enough both Wednesday and Thursday afternoon
that may help preclude this potential. Afternoon highs across the
region are to range from the mid 70s into the mid 80s while the
overnight lows dip into the mid 40s to the mid 50s.
The upper level pattern is to become more active out west through
this upcoming weekend. The first of two separate upper level lows
moves through the Desert Southwest into the Central Plains from
Saturday into Sunday. This will send a cold front across the area
from Saturday night into Sunday morning. There will be a chance to
slight chance for rain and thunderstorms with this front in the
area. Post-frontal northwesterly winds filters in behind this front
through Sunday but the medium range model guidance indicates that
this flow may be short-lived as the winds quickly respond to the
approach of the next upper level low into the Desert Southwest by
returning out of the southeast from Sunday night towards Monday
morning. The cloud cover into Monday morning remains forecast to
increase thanks to the southeasterly moisture return and with the
strengthening southwesterly flow aloft in the advance of that next
upper level system. Rain chances also may start to filter in as
well. While a cloudy and possibly wet solution is most favored at
this time with approach towards the Solar Eclipse timeframe, there
remains plenty of time to analyze medium range guidance as some
ensemble members with recent model runs have slightly slowed that
moisture return with the southeasterly flow in comparison to the
previous runs.
&&
.AVIATION...
(00Z TAFS)
Issued at 631 PM CDT Mon Apr 1 2024
Ceilings have returned to VFR at all sites as a front begins to move
across South Central Texas. This boundary will pass through DRT
between 00-01Z, with I-35 sites sometime between 03-06Z. Expect a
broken line of showers and thunderstorms to move across I-35 sites
with the better chances for TSRA at AUS/SAT. After the frontal
passage, winds will shift from the northwest and become gusty late
morning through Tuesday night.
&&
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 60 80 51 76 / 50 0 0 0
Austin Bergstrom Intl Airport 60 80 49 76 / 50 0 0 0
New Braunfels Muni Airport 60 81 49 77 / 40 0 0 0
Burnet Muni Airport 56 72 46 75 / 60 0 0 0
Del Rio Intl Airport 60 81 51 82 / 10 0 0 0
Georgetown Muni Airport 59 75 47 75 / 60 0 0 0
Hondo Muni Airport 57 82 47 79 / 40 0 0 0
San Marcos Muni Airport 59 80 48 76 / 40 0 0 0
La Grange - Fayette Regional 64 80 48 75 / 40 0 0 0
San Antonio Intl Airport 61 81 51 77 / 50 0 0 0
Stinson Muni Airport 62 83 50 78 / 40 0 0 0
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Short-Term...29
Long-Term...Brady
Aviation...27
Area Forecast Discussion
National Weather Service Hastings NE
627 PM CDT Mon Apr 1 2024
.KEY MESSAGES...
- Pesky light drizzle, rain and perhaps even some brief light
snow possible overnight into the first part of Tuesday
daytime, but MOST of our coverage area (CWA) will likely
remain dry, and any measurable rain/snow appears rather
unlikely.
- Beyond Tues morning, our forecast is dry (with fairly high
confidence) through at least Sat AM, with a decent chance of
rain/thunderstorms then arriving Sat afternoon-Sat night, and
perhaps some lingering showers into Sunday daytime (some
chance that the Saturday storms could at least be strong, but
too soon to declare any legitimate severe threat).
- Temperature-wise: today was clearly the coolest day of the
next 7 days, with a steady rebound upcoming with highs solidly
into the 50s most areas Tues-Wed, upper 50s-mid 60s Thurs, 60s
to spotty low 70s Fri-Sat, then mainly 60s Sun-Mon.
- With the main exception of Thursday (lightest wind day), most
all other days through the next week appear breezy to windy.
Fortunately, no days currently carry an obvious/higher-end
fire weather threat, but much of the area is on track for
solidly "near-critical" conditions for Wednesday.
&&
.DISCUSSION...
Issued at 459 PM CDT Mon Apr 1 2024
-- PRIMARY CHANGES TO THIS 7-DAY FORECAST PACKAGE VERSUS THE
PREVIOUS ONE (issued early this morning):
There were no "big time" changes, but a few worth mentioning
include:
1) Rain/thunderstorm chances (PoPs) especially for Sat night
were nudged up into "likely" 60-70% territory, as at least for
now this looks like a decent chance for widespread rain.
2) High temps for both Friday-Saturday were lowered at least
2-5 degrees from our previous forecast (especially for Friday),
as although it will certainly warm as the week goes on, it might
not be quite as pronounced.
-- "BIG PICTURE" 7-DAY FORECAST OVERVIEW/COMMENTS (including all
further discussion of the Wed night-Monday time frame):
- Overall, the large scale upper air/surface features depicted
by various models including NAM/GFS (in the shorter term) and
GFS/ECMWF (in the longer term) remain in fairly remarkable
agreement through the next week, bolstering confidence in the
overall going forecast.
- Briefly breaking down the next week in "chunks:
1) An upper trough axis passes overhead tonight into Tuesday,
bringing our continued/limited precip chances into Tuesday AM.
2) Wed-Fri: we gradually come under increasing influence of
upper ridging aloft, as we remain on the backside (west of) a
large scale trough departing through the eastern continental
U.S. (CONUS) and the next large-scale trough arriving into the
western CONUS. As the eastern upper trough departs, our surface
temperatures will gradually warm.
3) Sat-Sun: Both the ECMWF/GFS solutions swing the
aforementioned western trough into the Central Plains in a
somewhat negatively-tilted fashion, with widespread
showers/thunderstorms anticipated Sat afternoon-Sun AM as the
main push of forcing arrives. At least for now, low-level
moisture/instability levels appear fairly low to support a true
severe storm threat, but a few stronger storms cannot be ruled
out and this bears watching as it gets closer in time.
4) Sun night-Monday appear mainly dry as the weekend disturbance
lifts north and/or east of the Central Plains.
-- SHORTER TERM FORECAST DETAILS FOCUSED SOLELY ON THESE NEXT
48 HOURS (through Wednesday daytime):
- CURRENT/RECENT WEATHER SCENE AS OF 4 PM:
This morning featured widespread light drizzle and quite a bit
of at least light fog (visibility mainly no worse than 1/2 to 1
mile) across most of our CWA, but this afternoon the fog
dissipated and any drizzle has been reduced to spotty/patchy at
most. However, widespread mainly low clouds have resulted in a
cloudy/mostly cloudy afternoon, with high temps on track to only
reach somewhere in the 40s across most of our Nebraska CWA, with
upper 40s-low 50s more common in our KS zones. Adding to the
fairly chilly start to April have been steady northerly winds
sustained at least 15-20 MPH/gusts 25-30 MPH. In the mid-upper
levels, water vapor satellite and short term model data depict a
large-scale trough gradually crossing overhead, as some phasing
takes place between separate northern jet stream/southern jet
stream waves. At the surface, our CWA remains well north-
northwest of sharp surface front stretched across eastern KS
into northern MO (and points south) sparing us a pronounced
severe storm threat that will affect several states to our
south-southeast.
- THIS EVENING-OVERNIGHT:
From a hazardous weather perspective, we really "dodged a
bullet" with the aforementioned passing trough, as the severe
storm threat is clearly focused to our south-southeast, while
last night and earlier today any legitimate accumulating snow
focused to our north over northern NE. That same trend is
expected to persist tonight, as although large-scale forcing
from the trough continues driving through, an overall lack of
mid- level saturation is expected to keep our MEASURABLE precip
chances quite limited. That being said, have kept low-end
chances for drizzle, light rain and even spotty light snow going
through the night (any snow post-midnight), as it will almost
impossible to rule out some very light/pesky precip. Sometimes
in these situations, we are concerned about a "sneaky" band of
slushy/measurable snow appearing as the system departs, but
latest higher-res models such as HRRR offer little support for
this, due in part to the low level temperature profile mostly
remaining JUST warm enough to favor chilly rain over a snow
transition. In other departments, whether any given location
sees precip or not, it will be a cloudy/mostly cloudy night and
it will remain breezy to windy out of the north, with sustained
speeds commonly 15-25 MPH/gusts 25-30+ MPH. The combo of
clouds/winds will help to keep temps from dropping very far from
daytime highs, and if anything lows were nudged up very
slightly, aimed from low 30s northwest, mid 30s central, upper
30s far southeast.
- TUESDAY DAYTIME:
Added some low-end precip chances/PoPs to the 7-10 AM time frame
in our southeast zones (mainly southeast of a Geneva-Osborne
line) to cover any lingering light precip (mainly rain but
perhaps a touch of slushy snow?), but the vast majority of the
CWA will be dry through the day. Skies will steadily clear
through the day following a cloudy start. Under mostly sunny to
sunny skies, afternoon highs will climb a solid 5-10+ degrees
warmer than today..as we are aiming from mid-upper 50s in most
Neb zones, and upper 50s to around 60 in KS zones. However, this
warm-up will be tempered by continued breezy to windy conditions
with north winds generally sustained 20-30 MPH/gusts 30-40 MPH.
Fortunately for fire weather concerns, relative humidity (RH)
will drop no lower than 30-35% most areas.
- TUESDAY NIGHT:
This should be a breezy/dry night under mostly clear skies, with
northwest winds generally sustained 10-20 MPH and some gusts up
to around 25 MPH (especially east). Low temps a few degrees
colder than tonight most places...aimed from upper 20s far
north/west-central to mid 30s far southeast (but low 30s most
places).
- WEDNESDAY DAYTIME:
Overall similar to Tuesday in many ways (most sunny, but breezy
to windy albeit maybe a touch weaker), but with slightly lower
RH values raising fire weather concerns a bit. High temps are
aimed low 50s northeast, mid 50s central to upper 50s-low 60s
southwest. Sustained north-northwest winds mainly 15-25
MPH/gusts 25-35 MPH. With slightly drier air in place, afternoon
RH values are expected to bottom out 20-25% especially in most
of the southwestern 2/3rd of the CWA, driving fire weather into
"near-critical" territory (this has been introduced to our
Hazardous Weather Outlook/HWOGID).
&&
.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 602 PM CDT Mon Apr 1 2024
IFR CIGS will continue across the area this evening as a broad
area of stratus is seen on satellite slowly creeping southward.
Expect winds to remain steady and out of the north this evening,
increasing after 02/06Z as a surge in winds from the north will
increase winds to near 30 KTS...as some light BR (MVFR VSBYS at
worst) along with LIFR CIGS overtake the area. Expect some
gradual clearing during the morning hours Tuesday, with near
full sunshine (VFR conditions) by late morning or early
afternoon...as winds continue to gust in the 30-35KT range for
much of the day. The pressure gradient should finally begin to
relax by the tail end of the TAF period as an area of surface
high pressure settles in across the high plains from the north.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...None.
KS...None.
&&
$$
DISCUSSION...Pfannkuch
AVIATION...Rossi
Area Forecast Discussion
National Weather Service Green Bay WI
1048 PM CDT Mon Apr 1 2024
Updated aviation portion for 06Z TAF issuance
.KEY MESSAGES...
- Light snow mainly south of Hwy 29 will diminish by late this
evening. Additional minor accumulations up to an inch,
especially on grassy surfaces.
- Confidence is increasing for significant accumulating snow from
Tuesday afternoon into Wednesday morning (50% or greater in a
winter storm). The highest snowfall amounts will be east of a
line from Wautoma to Pembine where 6 inches or more of snow is
possible. High end amounts could reach up to a foot over the
lakeshore areas. A Winter Storm Watch has been issued.
- Winds will be on the increase Tuesday afternoon into Tuesday
night, with strong gusts expected through Wednesday. Widespread
wind gusts up to 30 to 50 mph will be possible during this
time. Minor blowing and drifting snow and also sporadic power
outages will be possible. Aviation travel could also see
delays.
- The Tuesday afternoon and Wednesday morning commutes will
likely be slow or difficult. Impacts will likely be the highest
for the Wednesday morning commute, but slushy and slippery
roads will be possible for the Tuesday afternoon commute as
well.
&&
.DISCUSSION...
Issued at 235 PM CDT Mon Apr 1 2024
Short Term...Tonight and Tuesday
The latest RAP analysis and satellite/radar imagery show a
northern stream shortwave moving across northwest Ontario and
northern Minnesota and a deep trough over the Rockies to the
desert Southwest. Confluent flow between these features is
contributing to a fgen band of precip lifting northeast into
central Wisconsin and the Fox Valley. Despite surface temps in the
upper 30s to lower 40s and dewpoints in the 20s, surface wet bulb
temps are in the middle 30s, so not out of the question for a
little snow to mix in with the rain. Far northern WI is more
entrenched in the drier air (dewpoint depressions 15-20F) and
therefore should remain dry through the afternoon.
Looking upstream, low pressure is developing over the central
Plains with a large trough stretching from the Rockies to the
desert Southwest. Forecast concerns revolve around precip and
accumulation trends tonight, followed by heavy precip on Tuesday.
Tonight...The fgen band of light precip will continue through the
evening before diminishing overnight over central to east-central
WI. Most precip should remain south of a Mosinee to Green Bay
line. As boundary layer temps cool, more snow will be mixing in
with the precip through the evening that could result in light
accumulations on grassy surfaces before the precip trails off. Northern
WI will likely remain dry through the night. Low temps in the mid
20s to mid 30s.
Tuesday...After a lull in the precip for part of the morning,
precipitation is expected to surge northeast as surface low
pressure rapidly intensifies as it moves northeast towards
southern Lake Michigan. Strong dynamics will accompany the
associated shortwave in addition to upper divergence and mid-level
fgen. Arrival of the strong forcing and associated lift will lead
to an area of heavy precip moving into the area from southwest to
northeast from late morning through the afternoon, though timing
of the heavier precip may shift yet.
The heaviest precip (0.25" to 0.50") is likely to occur from the
Fox Valley and Bayshore to the Lakeshore in the afternoon. There
are some indications that a secondary heavy precip axis will develop
in the afternoon over central to north-central WI in a 700-500mb
fgen band, though confidence in those amounts is lower than
further east over northeast WI.
In general, confidence is only low to medium with precip amounts
as CAM output is generally lower than NWP output from the
ECMWF/GFS/NAM/RAP. The latter models have shown a consistent
slower and deep trend of the 500mb and surface low and have chosen
to stick with the more consistent guidance.
Another relatively uncertain aspect is ptype and associated
impacts. Lowered surface temperatures within the precipitation to
generate more snow in the forecast. Temperatures will likely be in
the mid 30s for much of the day, which leads to the possibility of
a rain snow mix. This may be more true within lighter precip
rates. However, when the heavier precip rates move through in the
afternoon, concern is precip will trend over to snow with higher
accumulations than forecast (1-3") through the end of the
afternoon. The higher precip rates will likely result in more
impacts as the heavy snow overwhelms the warm ground temps. This
should lead to higher impacts on area roads for the evening
commute than earlier in the day.
Winds will also be increasing through the day, but the heavy, wet
snow will limit the blowing and drifting somewhat. Some
blowing/drifting appears possible from the Fox Valley to the
Lakeshore by late afternoon.
Putting it together, will issue a Winter Storm Watch from 1 pm Tue
through 1 pm Wed from Waushara to northern Marinette counties to
the Lakeshore.
Long Term...Tuesday Night Through Monday
NWP models and probabilistic forecasts continue to ramp up
snowfall amounts for Tuesday night through Wednesday as a
deepening low tracks towards the central Great Lakes then
retrogrades back towards Lake Michigan. Moisture and lift with
this system are impressive, with abundant frontogenesis in the
dendritic growth zone for a prolonged period of time likely
producing snowfall rates of 1 to 2 inches per hour at times.
There will also likely be a mesoscale band setting up at some
point across east-central Wisconsin or the lakeshore, which could
enhance snowfall amounts even further to 2 to 3 inches per hour.
A tight pressure gradient will cause northerly winds to gust to 30
to 50 mph at times in addition to the moderate to heavy snow,
likely reducing visibilities significantly. The highest impacted
areas will be the eastern half of the cwa from roughly Wautoma to
Pembine where heavy snow and gusty winds will cause Winter Storm
conditions Tuesday night into Wednesday morning. Given the
potential for Winter Storm conditions across this area (50% or
greater) will issue a Winter Storm Watch through early Wednesday
afternoon.
Although the heaviest snow will be over by Wednesday afternoon,
precipitation will linger across the area through Thursday morning
as the low slowly pulls away from the region. A tight pressure
gradient will remain across the western Great Lakes during this
period, with windy conditions remaining through Thursday.
Additional snowfall amounts during this period will be on the
lower side, with amounts of an inch or two possible at times
across the north, and less than an inch elsewhere.
High pressure will then build in behind the departing low late in
the week, with dry weather expected to last into the weekend as
the high slowly drifts through the area. The next chance for
precipitation comes next Monday when a slow moving low from the
northern Plains approaches the area from the west.
&&
.AVIATION...for 06Z TAF Issuance
Issued at 1047 PM CDT Mon Apr 1 2024
Where snow was earlier, conditions have improved late this
evening. Expect conditions to drop back to mainly MVFR overnight
through daybreak on Tuesday. There may some very light snow or
rain/snow at times but no impact to visibility is expected.
Ahead of a strong cyclone, precip will quickly surge from
southeast to northeast across the region on Tuesday morning.
Flight conditions will deteriorate in this precip to IFR or
possibly LIFR in a mix of rain and snow. By late afternoon the
primary ptype looks to become snow at even the north-central
terminals with widespread IFR to LIFR conditions expected.
Moderate to heavy snow with blowing and drifting snow will carry
into Tuesday night with widespread LIFR conditions. Could also see
some airports near minimums by this time, especially GRB, ATW and
MTW.
As deepening low wraps up over the central Great Lakes, sfc winds
will increase with gusts over 25-30 kts by Tuesday evening. Winds
aloft will be strong enough to also support LLWS at most of the
TAF sites.
&&
.MARINE...
Issued at 235 PM CDT Mon Apr 1 2024
A rapidly deepening low pressure system approaching the central
Great Lakes region will cause a tight pressure gradient across the
western Great Lakes region Tuesday night into Wednesday night.
Northerly winds will gust to 35 to 45 knots at times as this low
slowly moves through the central Great Lakes, providing for a
prolonged period of high winds from Tuesday night into Wednesday
night. Given the potential for gale force winds, issued a Gale
Watch for the nearshore and bay of Green bay during this period.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
Winter Storm Watch from Tuesday afternoon through Wednesday
afternoon for WIZ013-020>022-031-037>040-045-048>050-073-074.
&&
$$
DISCUSSION.....MPC/Kurimski
AVIATION.......JLA
MARINE.........Kurimski
Area Forecast Discussion
National Weather Service Indianapolis IN
1057 PM EDT Mon Apr 1 2024
.KEY MESSAGES...
- Scattered to widespread showers and thunderstorms this evening
through tonight; A few severe storms are possible with the primary
threat being large hail.
- Flash Flood Watch in effect this evening into Tuesday afternoon.
Repeated rounds of heavy rainfall. From 1 to 3 inches of rainfall
is possible, with locally higher amounts.
- Severe thunderstorms are once again possible on Tuesday, with all
associated hazards possible.
- A significant temperature drop is expected post frontal passage on
Tuesday evening. Potential impacts in the cold sector include
scattered snow showers and overnight frost/freeze.
- Early forecast thoughts on the April 8th eclipse covered in the
CLIMATE section at the bottom
&&
.MESOSCALE UPDATE...
Issued at 1057 PM EDT Mon Apr 1 2024
Earlier convective development has evolved into an area of heavy
rainfall that is slowly moving east, essentially training over
similar locations. The LLVL Jet is still struggling to ramp-up;
however, some of the latest guidance is indicating that around 6Z
tonight we will see this field develop and should further enhance
the upscale growth to convection upstream. Frontal boundary is
trying to sag south with the ongoing area of heavy rainfall between
IND and Terre Haute. Still seeing considerable lightning output,
which suggests continued development to the area of rain. The slow-
moving nature to the convection suggests growing concerns for flash-
flooding. There is still potential that overnight additional
convection will develop further south of the ongoing convection which
could prolong the activity overnight. The question will remain how
this impacts convection for later hours and Tuesday morning.
Previous mesoscale discussion issued at 8PM EDT...Convection has
continued to evolve upstream over Central Illinois positioned along
the frontal boundary, with the leading activity nudging into West
Central Indiana the last 30 minutes. Vertical extent to the cores
has not been too substantial, but is developing in the proximity to
the steadily increasing LLVL jet. The concern with some of the
leading towers will be if they are drifting north of the quasi-
stationary boundary they could easily produce larger hail stones due
to the much cooler airmass underneath. Surface observations have
indicated some backing the last couple of hours; however, helicity
within the 0-1km layer does not appear to be much different from
earlier. Satellite imagery is indicating some stronger vertical
growth to pockets of the convection drifting into Central Indiana,
so expect some continued upscale growth to convection. Given the
proximity to the boundary and taller structures beginning to develop
at a faster pace, this should aid in the enhancement to lightning
generation. Which is presently occurring to convection near
Greencastle Indiana and further west.
&&
.FORECAST UPDATE...
Issued at 940 PM EDT Mon Apr 1 2024
For details on the severe threat, please see the latest Mesoscale
Discussion.
Showers and thunderstorms continue to develop across the western
forecast area this evening. Expect coverage to gradually increase
across central Indiana as the 850mb jet increases tonight. Adjusted
PoPs in the first few hours to reflect current trends, then
continued high PoPs all locations overnight.
Advected Layered Precipitable Water imagery shows a deep flow of
moisture into the area, so the heavy rain/flooding threat will
continue. Flood Watch looks good.
Some of the colder air (mid to upper 40s) has slipped into the far
northern forecast area, so lowered low temperatures there a bit.
Meanwhile, lower 70s continue in the far southwest. Low temperatures
in the south look good, but adjusted hourly temperatures as needed.
&&
.SHORT TERM (This evening through Tuesday)...
Issued at 300 PM EDT Mon Apr 1 2024
Quite a bit to talk about in the short term period, primarily
concerning severe convective and flooding potentials.
CURRENT CONDITIONS
A deep upper-level trough currently resides over the intermountain
west, with the primary axis stretching from southern California to
North Dakota. The trough is expected to maintain a positive tilt as
it translates eastward through tomorrow. This orientation generally
allows deep southwesterly flow to prevail. At the surface, a sharp
quasi-stationary front is draped from west to east across Illinois,
Indiana and into Ohio. Temperatures in the 50s are found north of
the boundary, and in the 70s south of it. Sustained southerly flow
out of the Gulf of Mexico has allowed abundant moisture to stream
northward over the past 24-48 hours. Given the amount of warm
buoyant air flowing northward, it is no surprise to see CAPE values
over 1000 J/kg concentrated along the front. Instability is surface-
based south of the boundary, and elevated to the north (rooted
around 850-700mb).
THIS AFTERNOON
Latest satellite imagery shows clearing across central Illinois and
Indiana, and points southward. This should help destabilize the lower
atmosphere to some degree, and help the front gradually lift
northward once again. Recent High-Res/CAM data hints at this front
becoming the focal point for convective initiation this afternoon,
mainly after 18z or so. In terms of parameter space, we have CAPE,
as mentioned earlier (1000J/kg currently, rising to 1500J/kg by
afternoon). Lapse rates leave a lot to be desired, with values in
the 6.0 to 6.5 C/km range. Deep moisture extends up to the EL, with
CAPE profiles taking on a long and skinny appearance per RAP
soundings. Flow is relatively uniform through 850-700mb, increasing
more rapidly upward from there. A decent amount of CAPE exists in
the Hail Growth Zone, with flow increasing in this layer for good
storm top ventilation. Additionally, max parcel levels are quite
high (10 to 12km). Model hodographs are generally long and straight,
with some slight curvature in the 0-1km layer. Low-level curvature
increases a bit around sunset and after as a developing Low-level
jet acts to elongate this part of the hodograph. Plenty of
instability exists down low (upwards of 100J/kg 3CAPE), mainly along
and just south of the warm front.
Storm mode should initially be discrete, with a few supercells
possible. Should these supercells develop along and just south of
the warm front, then a tornado or two cannot be ruled out. Hail
appears to be the primary hazard today, and a few instances of hail
to 2 inches in diameter is not out of the question should lapse
rates improve. Upscale growth into an MCS is expected overnight,
which will allow the primary hazard to transition to severe wind
gusts.
TONIGHT
As mentioned just before, upscale growth into an MCS or several
clusters of storms is anticipated. Hi-res guidance shows storms
training along the east-west oriented front, and a signal for heavy
rain is likewise picked up on by various global models. On average,
a widespread rainfall total around 1-3 inches is likely, with
locally more depending on where training convection sets up. Current
guidance shows this area along and just north of the I-70 corridor,
but some other members of guidance depict it across southern
portions of the CWA. Given the spatial uncertainty in various forms
of guidance, but agreement in the overall signal...we went with a
Flash Flood Watch for the entirety of the CWA. Heavy rainfall is
expected to continue on and off through the night.
TUESDAY
There has been a rather significant shift northward with high-
res/CAM guidance regarding the position of a surface low expected to
develop during the day Tuesday. Guidance now begins to strengthen
the low over northern Missouri, and into Illinois, before lifting it
northeast towards lower Michigan. This, in turn, allows the warm
sector to extend further north. In this scenario, much of central
Indiana would be in this warm buoyant corridor just ahead of the
strengthening low. Parameter space in this warm sector is more
robust than today, with very long hodographs, deep CAPE, and steeper
lapse rates (6.5-7.5C/km). Model soundings show dry air in the 850-
700mb level, with abundant moisture near the surface. Additionally,
a much stronger low-level jet should exist (50-60kt). So what does
this all mean? All convective hazards are on the table tomorrow,
from strong winds, to large hail, and possibly tornadoes. This trend
in the models is recent, and will need to be monitored to see if it
becomes consistent run-to-run. Discrete cells should be favored, as
the north-south oriented cold front interacts with the west-
southwest shear vector to limit upscale growth. Additionally, cell
motions should be very fast. We also upped high temperatures for
Tuesday as well, since we look to be deeper into the warm sector now.
&&
.LONG TERM (Tuesday night through Monday)...
Issued at 300 PM EDT Mon Apr 1 2024
The bulk of the long range will be dominated by the system
developing in the short term.
Guidance is in good agreement now regarding a potent vort max diving
down out of Canada and phasing with the western trough as it
advances east. This phasing allows the surface low, mentioned in the
Tuesday section above, to strengthen rapidly. The system then
occludes over the Great Lakes, slowly spinning in place for the
remainder of the week. As colder air wraps around the system, snow
chances increase Wednesday into Thursday. Accumulations are
currently unlikely, given stronger April sun angle and warm ground.
Though a coating on elevated or grassy surface is not out of the
question.
Thereafter, ridging looks to build to our west as we head into the
weekend. Latest trends in guidance have been a bit slower and
further west for the big closed low mentioned above. That may allow
low-level stratocu to persist a bit more than currently shown.
Nevertheless, a gradual clearing trend is expected this weekend
along with warming temperatures. This forecast depends on how
quickly the closed low can exit the region.
Eclipse Outlook / Extended...
SEE CLIMATE SECTION
&&
.AVIATION (00Z TAF Issuance)...
Issued at 718 PM EDT Mon Apr 1 2024
Impacts:
- Showers increasing in coverage and becoming widespread by 06Z
- Scattered to numerous thunderstorms in the widespread rain
- Ceilings falling into MVFR and IFR by 06Z
- Wind direction may vary considerably in convection and as warm
front meanders
Discussion:
Confidence in timing of arrival of widespread rain is medium
due to mesoscale influences, but widespread rain should arrive by
around 06Z along with scattered to numerous storms. Ceilings and
visibility will lower in rain. Severe convection is possible.
Widespread rain will end by around 12Z Tuesday and some improvements
in ceilings will take place in the morning. A strong cold front will
move in during the afternoon bringing more scattered to numerous
convection.
&&
.CLIMATE...
Issued at 300 PM EDT Mon Apr 1 2024
It is now about a week out from eclipse day and as stated in
previous iterations of this discussion, a few signals can be
deciphered from long range guidance.
As mentioned in the discussion above, a deepening/occluding low
pressure system is anticipated to develop over the eastern US. As
this low deepens, it should act to bottle up the upstream wave
pattern. This can be seen in guidance as a deepening trough over the
western US. It`s this trough that could be the determining factor as
to what kind of weather we see on Monday April 8th.
Taking a step back, global teleconnections show strongly negative
phases in both the NAO and AO. This means that the synoptic scale
will dictate our weather going forward, and with a very strong and
occluded low over the east coast...it is likely that the position
and longevity of this system will determine the evolution of the
west coast trough.
Latest ensemble guidance depicts both the eastern and western
troughs becoming highly amplified with an increasingly squeezed
ridge in between. A flow pattern similar to a classic omega block
looks to take shape by Friday. With strongly negative
teleconnections, a pattern featuring blocking is not a surprise.
Guidance begins to diverge over the weekend as models struggle to
depict how the aforementioned features interact within the bottled up
flow. Guidance typically struggles in blocking patterns, and can be
too fast with synoptic-scale features. This can be seen in recent
trends with today`s system that has been gradually shifting westward
with time.
It`s tough to downscale this pattern into a cloud cover forecast for
the 8th. The primary questions are how much does the occluded east
coast low affect the upstream pattern, and in what form the western
trough ejects eastward. As guidance comes into greater consensus,
the answers to these questions will likewise come into focus. Stay
tuned for further updates.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
Flood Watch through Tuesday afternoon for INZ021-028>031-035>049-
051>057-060>065-067>072.
&&
$$
MESOSCALE...Beach
UPDATE...50
SHORT TERM...Eckhoff
LONG TERM...Eckhoff
AVIATION...50
CLIMATE...Eckhoff
Area Forecast Discussion
National Weather Service Louisville KY
1032 PM EDT Mon Apr 1 2024
...Forecast Update...
.KEY MESSAGES...
* Severe storms possible late tonight toward daybreak Tuesday, with
damaging winds, large hail, and spin-up tornadoes possible.
* Severe storms are likely Tuesday. Damaging winds, large hail, and
tornadoes are all possible. Localized flash flooding is also
possible in areas impacted by repeated heavy rainfall.
* Perhaps a rain/snow mix Wednesday night early Thursday then much
colder with freeze potential Friday Night.
* Eclipse weather starting to come into the 7-day forecast.
&&
.UPDATE...
Issued at 1031 PM EDT Mon Apr 1 2024
Convective complex has set up across central IL/IN at this hour, and
the latest trends in the data suggest that the farther north
solution is winning out to this point. As a result, thinking that
timing for the arrival of the convective complex can be pushed back
to the 4 or 5 AM time frame across southern Indiana, then pushing
ESE through the I-64 corridor through sunrise and the morning hours.
We do expect to see an uptick in warm advection showers and storms
picking up over the next 3 hours across our NW CWA as the low level
jet ramps up to 45-50 knots by 09-12z, but overall this isn`t
expected to be the main show. When the convective complex does
arrive in the pre-dawn to sunrise hours, expect it to be weakening
with mainly a wind threat. Can`t rule out a brief spin up tornado,
but would be more focused on the wind. Given the northward trend in
recent data, decided to hold off on the flood watch expansion
westward across more I-64 north counties, but still a bit concerned
heading into Tuesday with some training storms in this area.
After the morning wave, concern is still pretty high for what
happens in the dry slot ahead of the cold front for Tuesday
afternoon and evening. Soundings take on a pretty convincingly
tornadic look, including the threat for some strong and longer track
tornadoes with support from SARS sounding analog data. Low level
hodographs with very strong 0-1km shear would be supportive of good
streamwise vorticity ingestion in the presence of very strong
forcing and moderate instability nearing 1500 J/KG of ML CAPE.
02/00z run of the HRRR shows plenty of concerning UH tracks across a
large region, so the current threat/outlooks seem warranted, if not
some potential for upgrades. One factor hurting confidence for a
full blown outbreak is how much time we will have to clear out in
the dry slot, and build some instability. Right now, it does appear
we break out into the afternoon, and if that continues to be the
trend then confidence in some tornadic storms with all hazards will
continue to grow.
Previous Update...
Things are quiet across the CWA at this hour, with the warm front
analyzed from central IL, through southeast IN, and down into far NE
KY at this hour. The cap held through the afternoon and into the
early evening, although a 0005z AMDAR sounding shows the cap has
mostly eroded. Given the lack of any notable forcing at the moment
expect us to stay quiet for several more hours before activity picks
up. We`ll see the low level jet increase to around 45-50 knots
between 03 and 12 z tonight beneath strong exit region upper jet
structure. This will provide favorable deep layer shear across our
area as upstream MCS begins to impinge on our area.
The current picture upstream is becoming increasingly active with
supercells and strong to severe storm clusters across MO and IL, and
this activity is expected to ride generally W to E along the warm
frontal boundary through the overnight. Latest cams suggest that a
pretty concerning train of supercells and mixed QLCS modes could
train along the boundary somewhere between the I-64, and I-70
corridors, with the favor currently more on the Indiana side of
things. Given this training worry about a Flash Flood threat in
addition to the wind, hail, and tornado threat. Some of the latest
data has this activity pretty far north, and keeps our northern CWA
out of the game until 4 or 5 AM, while other data is a bit further
south and gets us going after 2 AM, which is when the LLJ should be
starting to ramp up pretty good. Am inclined to strongly consider
adding some more of our southern Indiana counties into the Flash
Flood Watch with the caveat that the farther north solution would
likely make this a bust. On the other hand, training of this
magnitude does lend to some potentially serious flooding concerns
somewhere between those two corridors.
Overall the severe threat through the overnight, and especially in
the pre-dawn hours to dawn still looks on the table, although feel
most confident in the 4 AM to midday time frame for the first wave,
mainly along and north of I-64. No changes to the main threat of
damaging winds and perhaps some flooding, with threats of some brief
tornadoes and hail also on the table.
&&
.SHORT TERM /THROUGH TONIGHT/...
Issued at 341 PM EDT Mon Apr 1 2024
Complex weather scenario starting to unfold over the next 24-36 hrs
with multiple opportunities for severe weather. Going in
chronological order, and increasing SVR potential...
Through This Evening...
Quasi-stationary front hung up over southern Indiana has started to
lift back north as a warm front. Isolated storms have popped over
the Wabash Valley and are mainly on track to slide just north of our
Indiana counties. However, as they generate outflow, redevelopment
is possible in our area of responsibility in southern Indiana, and
we have enough shear and steep enough mid-level lapse rates to
support large hail. We`re also sufficiently rooted at the sfc to see
damaging winds. This threat will diminish within an hour or two
after sunset.
Overnight...
Convection is underway over southern Kansas and northern Oklahoma,
and is expected to congeal into a squall line and accelerate
eastward this evening. This activity will cross the Mississippi
around midnight or shortly after, running just north of due east
into southern Indiana and northern parts of central Kentucky during
the pre-dawn hours. These storms will be mainly a damaging wind
threat, but large hail is also possible. The orientation of the
shear vector nearly parallel to the line doesn`t support prolific
spin-up tornado production, but anywhere the line becomes wavy, the
tornado potential will ramp up. Main focus on timing will be 2 AM to
7 AM EDT, with the line decaying around sunrise as it pushes into
the Bluegrass region of Kentucky.
There`s also some potential for training cells, especially along and
north of the I-64 corridor. However, with the lack of rain so far
today, am not inclined to expand the existing Flood Watch.
Tuesday (mainly afternoon)...
Severe risk on Tuesday could be highly dependent on how much the
overnight/early morning squall line works over the environment, and
how much precip lingers into the morning. Overall we do expect the
atmosphere to reload, but only so much agreement on the ability for
storms to fire ahead of the incoming cold front. Strong low-level
and deep-layer shear supports fast-moving supercells if it can
overcome the modest CIN, but some of the models are only developing
storms right on the cold front. All severe modes are on the table,
including damaging winds, large hail, and fast-moving, potentially
strong tornadoes. The SVR threat declines quickly with the passage
of the cold front, but that won`t happen until sunset or just after
in some of our south-central and east-central Kentucky counties.
&&
.LONG TERM /TUESDAY THROUGH MONDAY/...
Issued at 341 PM EDT Mon Apr 1 2024
Tuesday evening expect the cold frontal system responsible for
Tuesday daytime stormy weather to be pushing through southern IN and
central KY. The sprawling upper level system will slowly push across
the Midwest during the day Wednesday. With the tight pressure
gradient on the back side of the front, and moisture associated with
that upper low, expect Wednesday to be cold, windy, and dreary with
some light rain showers moving across the region. Any deeper cores
that develop during the afternoon could have some small hail. Not an
ideal day for the 50th anniversary of the Super Outbreak. In fact,
Wed. night we may briefly get cold enough to have a rain/snow mix in
a few spots. Activity shouldn`t be heavy enough for any impactful
snow on the ground though.
Clouds and precip chances will slowly shift east through the day
Thursday. Ridging will slowly build in Thursday night and
potentially hold onto to Sunday. That ridging will bring in less
cloud cover, and combined with winds dying down could bring a freeze
Friday night and Saturday night. Thursday night temperatures look to
fall into the 30s, but winds should stay up enough to preclude frost
formation, save for in very sheltered locations.
Sunday night/Monday the deterministic models (12Z GFS/00Z CMC/00Z
Euro) all bring an upper low into the Northern Plains. Our area will
be in the southwest flow between the narrow ridge pushing east of
our and this upper low. This pattern tends to bring high clouds
over our area. Those deterministic models pull in some rain chances
as well, and the 00Z ensemble runs tend to agree with that
chance...with several members showing at least light QPF through
Monday. Sky cover grids still have a fairly wide spread in coverage
for Monday afternoon, but the means line up with climo for sky cover
on Eclipse Day...so no big signal seen just yet.
&&
.AVIATION /00Z TAFS THROUGH 06Z THURSDAY/...
Issued at 752 PM EDT Mon Apr 1 2024
Very active and challenging forecast over the next 24 hours as
several rounds of storms, including some strong to severe, could
impact the I-64 corridor TAF sites. Currently we are VFR and expect
increasing mid clouds through the evening hours, along with steady S
or SSW winds. Perhaps a few gusts between 15 and 20 mph will linger.
Ceilings are expected to lower and around and after Midnight, with
solid MVFR setting in (likely below 2 k feet at times) just before
and around sunrise. Some gusty winds between 20 and 25 mph will be
possible at times. However, the biggest concern overnight will be
for a strong complex of storms working along and north of I-64. Have
tried to time this wave for the HNB/SDF TAF sites, as well as some
potential to impact LEX. Stayed a bit more optimistic at RGA/BWG for
that first wave.
Another wave of showers and storms is then expected just after
sunrise into early afternoon, where more strong to severe storms are
possible. A final wave could then develop along the cold front late
afternoon into early evening. Wind gusts through afternoon and
evening could be 20 to 25 mph sustained out of the SW with gusts of
30 to 35 mph outside of any t-storm activity.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...Flood Watch through Tuesday evening for KYZ032-033-035>037-
040>043-049.
IN...Flood Watch through Tuesday evening for INZ079.
&&
$$
UPDATE...BJS
SHORT TERM...RAS
LONG TERM...RJS
AVIATION...BJS
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
842 PM CDT Mon Apr 1 2024
.KEY MESSAGES...
- Flood watch has been issued for southeastern 5 counties for
tonight.
- Heavy rainfall will also occur with the showers and storms
which will lead to rise in area stream and rivers and may lead
to flooding of low-lying areas and ditches.
- Storm system to transition rain to wet snow late Tuesday into
Wednesday which could yield some accumulations.
- Blustery and chilly through Thursday with waves of snow and rain
showers into or a bit beyond Thursday morning
- Cool and breezy Friday then warming trend through early next
week with rain shower chances returning later Sunday into
Monday
&&
.UPDATE...
Issued at 841 PM CDT Mon Apr 1 2024
Have opted to issue a Flood Watch for tonight for our
southeastern tier of counties.
Evening soundings from DVN and ILX both had PWATs around 1.15"
or around 200% of normal with even higher PWATs on objective
mesoanalysis upstream. Thunderstorms earlier this evening
produced measured rainfall of 0.60" in just 15 minutes,
signifying just how efficient of rain producers storms can be in
this current environment. Strong forcing should allow the large
area of moderate to heavy rain with embedded thunderstorms over
northeast MO and western IL to continue spreading eastward and
likely shifting a bit north with time. Flash flood guidance
(FFG) over Ford, Iroquois, Benton, and southern Newton/Jasper
Counties is around 1-1.5/1 hour and 1.33-1.67/3 hours.
While there remains some uncertainty where the more mesoscale
bands of heavier rainfall will set up, given the airmass and
potential very heavy rainfall rates and the rather low FFG and
saturated grounds, felt it was prudent to hoist a flood watch
for tonight far southern CWA.
Elsewhere, scattered showers and some thunderstorms are likely
across the remainder of the CWA tonight. Certainly the potential
is there for locally heavy rainfall, but there is lower
confidence in coverage becoming widespread enough to pose a
significant flash flood threat. Having said that, given the high
PWATs, any storms that do occur could be efficient rain
producers.
Regarding the severe potential...the synoptic warm front has
lifted north to nearly our CWA border, however, the convective
cold pool has really shifted the more effective front farther
south into downstate IL. There is some weak elevated instability
(MUCAPE of a few hundred j/kg), but with widespread convection
downstate intercepting the low level jet, suspect the threat of
any severe weather is quite low.
Otherwise, no big changes made to the going forecast for
tonight.
- Izzi
&&
.DISCUSSION...
Issued at 335 PM CDT Mon Apr 1 2024
Through Wednesday:
Showers and thunderstorms continue to develop along the 850 mb
warm front which is currently analyzed across northern IA,
northern IL, and northwest IN. RAP mesoanalysis shows a plume of
300 to 500 J/kg of MUCAPE south of the 850 front along with
modestly steep mid-level lapse rates which will continue to
support the development of showers and thunderstorms through
this evening. A few of these storms could even become strong to
possibly severe this evening if they are able to interact with
the 60+ kts of bulk shear overhead. The main threat with any
strong to severe storms will large hail up to quarter size, but
some localized gusty winds are also possible. Given this
potential SPC has extended the marginal (level 1 of 5) risk
north to I-88 through tonight.
While the instability is expected to gradually wane from north
to south overnight, the broad ascent generated by the upper
trough sprawled across the southwest CONUS and surface low
lifting into central IL will allow showers to persist into the
day on Tuesday. Couple this forcing with the ample moisture
present (PWATs around 1.0 inch) and there continues to be the
threat for periods of heavy rainfall as well. Guidance continues
to favor areas south of I-80 for the greatest rainfall totals
(totals possibly in the 2 to 3 inch range), but most of
northeast IL and northwest IN are forecast to see amounts around
1.0 inch. Given the above average soil moisture and already
heightened river levels from last night`s rain some localized
flooding may occur especially in low-lying and more flood prone
areas.
Heading into Tuesday the aforementioned surface low is expected
to lift northeast into lower Michigan Tuesday afternoon which
should bring the track over the southeast corner of our forecast
area. In doing so, it looks as if the warm sector may remain in
parts of our area into Tuesday afternoon which looks to
generate another threat for strong to severe thunderstorms.
While most of these storms look to be mainly elevated, there is
a growing signal amongst hi-res guidance that some surface based
instability may creep into parts of our area east of I-57 which
would make for a threat of gusty winds, large hail, and
possibly even a isolated tornado. As such SPC has reintroduced a
marginal risk (level 1 of 5) for all of northwest Indiana and
portions of northern IL near the IL-IN line. Keep in mind there
is still some uncertainty in regards to the exact low track
which could shift and force the warm sector east of the area so
be sure to closely monitor the forecast for changes.
Once the surface low pushes east of the area Tuesday afternoon
it is forecast to quickly deepen as the broad southwest trough
begins to phase with an upper low forecast to dive out of Canada
into the Great Lakes. As this occurs the ongoing rain is
expected to transition to wet snow late Tuesday into Tuesday
night as colder air advects into northern IL behind the upper
low. Initially, accumulations with any snow look to be limited
due to surface temperatures still above freezing, but as
temperatures cool Tuesday night some slushy accumulations could
materialize. While guidance is generally in good agreement with
this evolution there is some uncertainty in exactly where the
upper low and the deepening surface low will establish which
will impact where the heaviest axis of snow will occur. At this
time it looks as if the highest snow accums should occur north
of our area into southern Wisconsin and lower Michigan, but
there is a signal in guidance that higher totals (in excess of 2
inches) could reach into northern IL late Tuesday night into
Wednesday. Regardless, wet snow is expected to persist through
the day on Wednesday before winding down Wednesday night.
Additionally, winds will also turn northwesterly in the wake of
the surface low with speeds increasing through the day on
Tuesday into Wednesday. Depending on where exactly the surface
low stalls once it gets into Lower Michigan, we could see winds
gusting upwards of 35 to 40 mph on Wednesday.
Yack
Wednesday Night through Monday:
Exceptionally deep and cold closed mid-upper level low pressure
will be centered in approximately the Michiana area early
Wednesday evening. The 500 mb low, which will bottom out around
520 DaM, nearing record lows for 500 mb heights for early April,
will pivot southeast into Thursday morning. As such, the strongest
large scale forcing will exit east and southeast of the area,
yielding a more showery precip regime, particularly overnight into
Thursday. There`s a window in the early to mid evening over
interior northern and central Indiana, closest to the closed low
and coldest temps aloft, for some more persistent snow/snow
showers, though it`s questionable if surface wet bulb temps will
be supportive enough. Another short-wave wrapping southward around
the circulation early Thursday morning may bring another
temporary enhancement to the precip rates in ongoing rain and snow
showers.
With brisk northerly flow down the fetch of water temps
in the 40s over the lake, any lake enhancement and potential
accumulations from it would likely be relegated to well inland.
All in all, the more showery nature of the precip and marginal
temperatures in the lower to mid 30s suggest that additional
slushy accumulations will be limited, localized, and thus less
likely to cause any travel impacts. Shower coverage should further
wind down Thursday afternoon as the closed low shifts into the
northeast US. It will be unpleasant through Thursday with
unseasonably chilly temperatures (lows in the 30s and highs in the
40-45F range) with northerly gusts up to 30-40 mph. Large waves
and elevated lake levels may cause some overwash onto vulnerable
portions of lakeshore paths and trails, particularly in Chicago
and Lake County Indiana.
It will take some time to lose the influence of the pronounced
eastern troughing on Friday, with continued cool northerly breezes
keeping highs in the 40s, coolest lakeside, despite increased
sunshine. Saturday will be a fairly pleasant day with plenty of
sun and highs in the 50s away from the lake, but only in the 40s
lakeside due to onshore winds persisting. The next western trough
will eject east in the Sunday-Monday timeframe, accompanied by a
return of shower chances. Temperatures will likely continue their
warming trend, though the magnitude of this warm-up into Monday
will be dependent upon the track and evolution of the trough
traversing the region.
Castro
&&
.AVIATION /00Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 630 PM CDT Mon Apr 1 2024
Aviation weather concerns through the 00Z TAF period include:
* Intermittent rain showers through the bulk of the period
* Periodic thunderstorms possible through mid-evening
* IFR cigs expected through the period
* Snow mixing with rain Tuesday afternoon and evening. True snow
showers likely at RFD
Rain showers continue to move across the area in waves early this
evening. A brief bout of thunderstorms will move over the Chicago
sites shortly after 00Z. Additional storms can be found farther
upstream. While it looks as though these subsequent storms will
remain south of the TAF sites, it`s possible that some could reach
the Chicagoland airfields through mid-evening or so. Rain will
continue intermittently through the night and most of Tuesday. Late
Tuesday afternoon, rain is expected to transition into a rain/snow
mix for the last several hours of the 30-hr TAF period. At RFD, full-
blown snow showers look likely beginning as early as mid-afternoon
and lasting into the evening.
Vsbys will take occasional trips down to MVFR between the periodic
showers and residual fog/mist. IFR vsbys will be possible underneath
any thunderstorms or heavier rainfall. Cigs around the area have
been bouncing between MVFR and IFR for several hours. It`s expected
that we`ll find ourselves beneath predominantly IFR cigs throughout
the period, although there is a growing signal for periods of LIFR,
particularly during the morning on Tuesday.
Meanwhile, winds should remain a steady NE into tomorrow afternoon.
Gusts to around 20 kt are likely to stick around but become less
frequent tonight. Winds will build through the day tomorrow gusting
to 25 to 30 kt during the afternoon and evening. Direction will flop
over to NW late in the afternoon close to when we expect that
transition to a rain/snow mix.
Doom
&&
.MARINE...
Issued at 335 PM CDT Mon Apr 1 2024
A period of strong northerly to northwesterly winds remains
likely late Tuesday through Thursday, though with continued
uncertainty with the details. Deepening surface low pressure will
track from central Illinois to southern Lake Michigan or western
Lower Michigan Tuesday evening. The low pressure will bottom out
at 29.00 to 29.15 inches Wednesday night into early Thursday and
then slowly weaken the rest of Thursday as it meanders eastward.
High pressure around 30.2 inches over the Plains states will
cause a tight pressure gradient between it and the deep surface
low and the resulting potential for gale force winds.
There may be a window for gale force gusts north of the deepening
low pressure center mid-late Tuesday afternoon, though did not
modify the gale watch yet to encompass this period. A slightly
farther northwesterly track of the surface low in Monday`s most
recent model guidance lowered the chance for a higher end gale
scenario late Tuesday night through Thursday. It`s possible that
after the late Tuesday period, the next best chance for 35-40 kt
northerly gales will be late day Wednesday through early to mid
Thursday afternoon. As noted earlier, given the uncertainty, did
not upgrade the Gale Watch to a warning for the nearshore waters.
However, did extend the Watch in time a bit until 3 PM CDT on
Thursday.
Castro
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...Flood Watch until 5 AM CDT Tuesday for ILZ033-ILZ039.
IN...Flood Watch until 5 AM CDT /6 AM EDT/ Tuesday for INZ010-
INZ011-INZ019.
LM...Small Craft Advisory until 1 AM CDT Wednesday for the IL and
IN nearshore waters.
Gale Watch from late Tuesday night through Thursday afternoon
for the IL and IN nearshore waters.
&&
$$
Visit us at weather.gov/chicago
Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
906 PM EDT Mon Apr 1 2024
.SYNOPSIS...
A frontal boundary will linger in the vicinity of the area
through Tuesday as multiple disturbances pass through aloft.
Low pressure will track into the Great Lakes Tuesday night, with
another area of low pressure developing overhead on Wednesday.
This secondary area of low pressure will lift off to our
northeast Wednesday night, eventually dragging a cold front
through the area. Upper troughing will linger aloft through
Friday and Saturday, before high pressure builds in for Sunday
and Monday.
&&
.NEAR TERM /THROUGH TUESDAY/...
A backdoor cold front continues to progress southwestward at
the surface, and now extends across Highland, Augusta, Nelson,
and extreme southern Albemarle counties. Along and south of that
boundary, we have manage to accrue about 500-1000 MUCAPE in an
environment with about 40-50 knots of effective bulk shear in
place per the latest RAP mesoanalysis. That environment is
marginally conducive for a rogue supercell and a conditional
threat for damaging winds and large hail if any storms are able
to become established. This has happened with one storm moving
into Nelson county this evening. Do expect storms to weaken
rapidly as they move northeast into much more stable air.
A mid-level shortwave will lift from the Mississippi Valley
toward the Great Lakes later tonight. In response, a push of
warm advection will ensue aloft atop the cold air wedge and
showers will start to break out first across southwestern
portions of the forecast area late this evening. These showers
will gradually spread northeastward over the course of the
night, with most locations likely receiving some precipitation
overnight. Forecast soundings show some limited instability
aloft, so a few rumbles of thunder may also be possible.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/...
There may be a brief lull in the showers tomorrow morning,
especially to the south of I-66/US-50. However, 12z CAMs show a
decaying MCS moving into the area from the west during the mid-
late morning hours. The bulk of the forecast area should be
solidly within the CAD wedge at that time, so the MCS should be
elevated in nature. This should keep the threat for any
damaging winds low, and even elevated instability appears to be
minimal at that time, so the threat for severe hail with the MCS
will likely be very low as well. Precipitation and resultant
evaporational cooling at low levels from the MCS will help to
thermodynamically reinforce the wedge, and consume any elevated
instability that had previously built up. That stabilization and
subsidence in the wake of the MCS may make it difficult for any
storms to reform during the daytime in its wake. 12z CAMs are
split on whether any storms can reform along the retreating CAD
wedge, but the majority show little in the way of
shower/thunderstorm activity during the afternoon and even early
evening hours. If storms were to form, there will be a
conditional threat for damaging winds and large hail, especially
across central Virginia, the central Shenandoah Valley, and to
the west of the Allegheny Front, where they`ll likely end up on
the warm side of the boundary by day`s end. SPC has those areas
in a Slight Risk for severe thunderstorms tomorrow, with a
Marginal Risk further east.
Large scale ascent will be on the increase Tuesday night as a
deep upper trough/closed low approaches from the west and strong
height falls ensue aloft. This uptick in forcing for ascent
should lead to an increase in the coverage of showers and
thunderstorms Tuesday night. With elevated instability in place
and ample shear present, some hail can`t be ruled out with any
of these storms.
The upper trough/closed low will continue to progress eastward
on Wednesday. The primary low associated with the system will
remain over the Great Lakes, but most guidance shows a
secondary low forming over our local area. Additional showers
and thunderstorms may be possible Wednesday morning through the
first half of Wednesday afternoon in advance of the system`s
cold front. Uncertainty remain high this far out, but some of
those storms could be strong to severe as well. Much of the
region is in a Marginal Risk from SPC on Wednesday.
With the multiple rounds of rain over the next several days,
far western portions of the forecast area remain in a Flood
Watch through Tuesday.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
Showers will be ending from west to east across the area Wednesday
except in the Appalachian region as low pressure pulls away from the
coast. Attention will then turn to mountain snow showers Wed night
through Thu night as upper low moves overhead and freezing levels
drop. Off and on snow showers will continue as several disturbances
rotate around drop and colder air continues to usher in on
strengthening NW winds. Cloudy, unsettled conditions with sct-nmrs
rain showers can also be expected at low elevations as additional
shortwave energy rotates around upper low. Winds will also become a
concern Thu into Fri as pressure gradients tighten behind deepening
low offshore. Freq gusts to 35 mph will be common with peak gusts to
50 mph in any shower. Strongest winds appear to be in the Thu night-
Fri morning time frame before gradually subsiding Saturday into
Sunday. Overall, expect a chilly week for early April with improving
weather not expected until next Sunday a week from today.
&&
.AVIATION /01Z TUESDAY THROUGH SATURDAY/...
Showers or a brief thunderstorm may develop in the vicinity of
a surface front located near CHO this evening, but for now that
remains just south of the area. Winds will generally be light
out of the northeast.
Chances for rain will increase through the night tonight. A
rumble or two of thunder can`t be ruled out during the second
half of the night IFR ceilings are expected through the night.
There is a decent signal in CAM guidance for a decaying MCS to
move across the area late tomorrow morning. VCTS has been
introduced to most of the TAFs to account for this potential.
Ceilings should remain IFR through the day tomorrow.
There may be a bit of a lull in precipitation behind the late
morning MCS. Confidence is increasing in the development of
storms during the late morning into early afternoon across
central VA. Have included a VCTS for that in the latest TAFs.
Additional storms may be possible tomorrow night through the
first half of Wednesday, but confidence in exact timing remains
low. Sub-VFR ceilings should persist through at least midday
Wednesday. Winds will generally maintain an easterly component
(somewhere between NE and SE) through midday Wednesday, before
shifting around to out of the NW Wednesday afternoon.
Widespread showers are expected Tue-Tue night. Thunderstorm threat
exists south of I-70 with a severe risk (mainly hail) south of US-
50. The greatest severe risk is over central VA along the I-64
corridor. Anticipate there will be flight restrictions Tue-Tue night
due to the showers and thunderstorms in the area. Persistent showers
should start exiting the area by 12Z Wed, but occasional showers
will be possible through Thu in the vicinity of the upper low. Winds
will become a concern Thu into Fri with gusts to 30 kt likely.
&&
.MARINE...
Sub-SCA north to northeasterly winds are ongoing over the water
this afternoon. Winds will turn easterly later tonight, and
remain easterly through Wednesday morning. Prevailing sub-SCA
conditions are expected during that time, but a few gusts could
reach low-end SCA levels over northern portions of the Bay
tomorrow afternoon into Wednesday morning. SMWs may also be
possible with any storms that move over the waters. Winds turn
northwesterly behind a cold front Wednesday afternoon. Small
Craft Advisory conditions appear possible in the wake of the
front Wednesday afternoon.
Thunderstorms will be the primary hazard Tue-Tue night south of US-
50/Bay Bridge. SCA conditions are possible across the southern
waters Tue through the end of next week. Gale force winds are
becoming increasing likely Thu into Fri.
&&
.TIDES/COASTAL FLOODING...
Tidal anomalies are forecast to slowly increase over the next few
days as southeast to south winds push water up the Chesapeake Bay
and Tidal Potomac. A frontal boundary lifts north into the
area, causing winds to become east to northeast through mid
week. Sensitive locations at Annapolis and Straits Point are
likely to reach Action Stage today and Tuesday during the
highest diurnal tide. A few other locations could also reach
Action Stage during this time. For Wednesday, this is when some
locations could reach Minor Flood, mainly Annapolis, Straits
Point, and DC SW Waterfront. A cold front sweeps through
Wednesday night, and offshore winds behind it causes tide levels
to quickly drop through Friday.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...Flood Watch through late Tuesday night for MDZ001-501-502.
VA...Flood Watch through late Tuesday night for VAZ503-504.
WV...Flood Watch through late Tuesday night for WVZ501>506.
MARINE...None.
&&
$$
SYNOPSIS...KJP
NEAR TERM...CJL/KJP
SHORT TERM...KJP
LONG TERM...LFR
AVIATION...LFR/CJL/KJP
MARINE...LFR/DHOF/KJP
TIDES/COASTAL FLOODING...KRR
Area Forecast Discussion
National Weather Service Nashville TN
844 PM CDT Mon Apr 1 2024
...New UPDATE...
.UPDATE...
Issued at 829 PM CDT Mon Apr 1 2024
There`s very little change to the forecast this evening. The 00Z
sounding from OHX shows a pronounced elevated version at ~775 mb,
but not as pronounced as the 12Z sounding. Lapse rates above the
inversion are a robust 7.4 C/km. There`s still not a great deal of
low-level shear, but that will change between now and tomorrow
afternoon as near-surface winds increase ahead of an approaching
cold front. The 00Z HRRR forecast sounding valid for BNA at 19Z
tomorrow almost entirely erodes the inversion and gives some
notable severe storm parameters: SBCAPE of 2,064 J/kg, LI of -7,
700-500 mb lapse rate of 6.9 C/km, PWAT of 1.61" and 0-3 km
helicity of 319. The HRRR shows discreet cells developing by
midday tomorrow, with a broken line of cells coming together right
around BNA by 21Z. There is also a wide disparity in QPF values,
ranging from less than 1/4" over northwest Middle Tennessee to
more than 3" over parts of the Cumberland Plateau. Indeed, the
atmospheric models don`t project a great deal of moisture
consolidating ahead of the cold front until it passes east of BNA
and gathers steam.
&&
.SHORT TERM...
(Rest of today through Tuesday Night)
Issued at 1134 AM CDT Mon Apr 1 2024
It`s another warm day with temperatures in the 70s with plenty of
cloud cover around. A couple of sprinkles were noted on radar this
morning but the radar is currently clear. The area should stay dry
through the evening. A couple of showers and storms will be possible
closer to dawn and into the morning hours particularly in the north
and west as low level advection ramps up. A strong storm cannot be
ruled out but the main window for severe weather chances continue to
be Tuesday afternoon and early evening.
CAMS show additional storms developing around 18z over the CWA or
just to the south and lifting east/northeastward. Instability
parameters are higher than what was shown in previous days now
that CAMS are in range. Median HREF surface CAPE values are above
1000 J/kg Tuesday afternoon. In addition, some CAMS including the
HRRR show low level winds more backed than previous days. With
that, SRH values have increase by about 50-100 m2/s2 with 0-1 SRH
values around 200-300 m2/s2. More than ample 0-500mb bulk shear
will be in place to support organized updrafts. This is
increasing my confidence in the severe weather threat tomorrow
afternoon. Tornadoes, large hail, and damaging winds will all be
possible. Storm modes may initially start as cells but should
evolve into line segments as the afternoon progresses. If cells
are able to stay isolated for a couple of hours, a long track
tornado cannot be ruled out. The one point of uncertainty with
this event is the coverage of morning activity. If the morning
wave is more widespread, storms may take longer to initiate in the
afternoon and be limited to the eastern half/third of the CWA.
With that fact, confidence in severe weather is highest in the
eastern part of the CWA where all CAMS have convection tomorrow
afternoon.
Storms should move off the plateau by 00z or 01z Wednesday. Some
showers may persist behind the main line of storms but the window
for severe weather will be shut by then.
&&
.LONG TERM...
(Wednesday through next Monday)
Issued at 1134 AM CDT Mon Apr 1 2024
Behind Tuesday`s front, conditions will be cooler on Wednesday
with highs in the lower to mid 50s with 15-20 mph W/WNW winds.
Scattered showers will be possible on Wednesday as a lobe of
energy rotates around the large upper low centered over the Great
Lakes. Thursday will be another cool day with a couple additional
showers possible along the northern plateau. Lows Thursday night
will drop into the low to mid 30s but the frost may be limited by
winds remaining at 5-10 mph. Highs on Friday should be about 5
degrees warmer with more sunshine. Frost may be more widespread
Saturday morning with lows again in the low to mid 30s with calmer
winds. Temperatures will continue to rebound going into the
weekend as the upper low moves off to the east and troughing over
our area is replaced with upper ridging.
&&
.AVIATION...
(00Z TAFS)
Issued at 721 PM CDT Mon Apr 1 2024
Multiple fluctuations in weather elements, especially ceilings &
vsbys, expected after 02/09Z with several admendments probable.
02/17Z-02/24Z potential at terminals/within vcnty of svr convection
development/movement across with potential sfc wind gusts up to
45kt-50kts+ CKV/BNA/MQY with isolated gusts 65kt + SRB/CSV. TEMPO
groups used to address best 2 hr window for higher sfc gust. Best
potential for 3hr window. Atmospheric low level pressure gradient
influences will support gusts to 30kt, sustained SW winds 10-20kts.
&&
.PRELIMINARY POINT TEMPS/POPS...
Nashville 67 78 45 57 / 20 90 60 30
Clarksville 67 78 43 54 / 30 80 40 30
Crossville 62 72 40 51 / 10 80 90 50
Columbia 66 76 44 57 / 10 90 50 20
Cookeville 65 74 42 52 / 10 90 90 50
Jamestown 62 74 40 51 / 10 90 90 60
Lawrenceburg 66 76 45 57 / 10 90 60 20
Murfreesboro 66 77 44 57 / 10 90 70 30
Waverly 65 76 42 55 / 30 90 40 20
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE.......Rose
SHORT TERM...Reagan
LONG TERM....Reagan
AVIATION.....JB Wright
Area Forecast Discussion
National Weather Service Paducah KY
647 PM CDT Mon Apr 1 2024
.KEY MESSAGES...
- A few showers or storms are possible along the I-64 corridor
this afternoon as temperatures rise to near 80.
- The main risk for severe storms is this evening through the
night, mainly from SEMO through S Illinois to SW Indiana, with
damaging winds the most likely severe weather hazard, though
all are possible.
- Additional storm development is possible mid morning to early
afternoon Tuesday east of the Mississippi River as the cold
front makes its passage. Wind gusts up to 30-40 mph are
possible Tuesday and Wednesday.
- Temperatures will be about 10 degrees below normal by the
middle of the week in the 50s/30s. Frost and possibly freeze
headlines still are possible, with the best chance Friday
night.
&&
.DISCUSSION...
Issued at 340 PM CDT Mon Apr 1 2024
The warm front remains near I-70 in Central Illinois today. As a
result, shower and storm development is generally north of the
forecast area, with only a couple isolated storms in the I-64
corridor this afternoon. These have moved out suggesting limited
potential for the remainder of the afternoon and early evening.
Temperatures have soared to the mid to upper 70s with a few
isolated spots reaching 80.
Forecast trends today have been to reduce precip chances
throughout the today-Tuesday period, with the main focus for
strong to severe storms concentrated in the late evening to
overnight hours as storms enter Southeast Missouri before
midnight and track northeastward through Southern Illinois into
Southwest Indiana. Western Kentucky has reduced chances but
storms remain a possibility there as well. The enhanced risk of
severe weather remains for the northern/western portions of the
Quad State today, with a slight risk over much of the rest in
the southeast.
Model soundings produce MLCAPE near 1000, PW near 1.5, and dew
points in the lower half of the 60s with mid-level lapse rates
peaking at 8-8.5 C/km this evening. There is plenty of shear,
0-3 km shear near 50 kts and 0-6 km of 60+ kts along with SRH of
200-300. Southwesterly winds today are slowly backing towards
southerly this afternoon. A strong LLJ moves in with winds of
50+ kts. Limitations are a model capping inversion around 800
mb, along with less favorable timing late night. Early evening
discrete storm potential is better to the north/west, with late
evening/overnight storms taking on an at least somewhat
organized structure. Damaging winds are the primary severe
weather hazard with significant winds a possibility, though
large hail (mainly from any discrete cell development) and
tornadoes are also possible.
The RAP has been most aggressive with afternoon storms, which
have not materialized. The NAM continues to produce little in
the way of thunder over the forecast area throughout the entire
event. The ARW/FV3/HRRR track storms late evening to overnight
from SEMO/SIL/SWIN and areas of WKY near the Ohio. This group is
more likely to be closer to the solution.
As the trough approaches tomorrow, the surface cold front moves
through, allowing for potential redevelopment of storms. Some
strong to severe storms are possible but in the Quad State
confidence is low, with the better chances to our east and
southeast. Overall, QPF values have trended lower, with almost
trivial amounts in the south (highly conditional on storms
moving over areas) and around an inch in the north. The cold
front crosses through by the end of the day, with highs midday
ahead of the front. Temperatures drop significantly afterwards
with lows near 40 Tuesday night. The low pressure rapidly
deepens over Michigan and stalls, allowing for wrap-around
showers Wednesday as PoPs have been significantly increased to
account for this. Gradient winds remain a concern Tuesday to
Wednesday with gusts around 30 mph Tuesday and 30-40 mph
Wednesday.
Dry conditions are expected for the end of the week with
continued northwesterly flow. Lows in the mid-30s are forecast
Wednesday night and Thursday night though breezy winds should
limit frost formation. Lighter winds, along with lows in the low
to mid 30s Friday night, pose the best potential for any
frost/freeze issues.
A warming trend occurs over the weekend as winds shift to
southeasterly by Sunday. Models vary on progression of a system
in the Central Plains Sunday-Monday, resulting in PoPs in the
forecast and temperatures becoming well above normal Monday.
This system funnels moisture northward from the Gulf, and
provides uncertainty regarding cloud cover for eclipse day next
Monday. Current ensemble averages don`t provide help for those
looking for a decisive forecast at this stage.
&&
.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 647 PM CDT Mon Apr 1 2024
MVFR ceilings will develop northward across the region this
evening, then scattered SHRA/TSRA will move eastward across the
region in the overnight to early morning hours. Brief IFR
visibilities and lower MVFR ceilings will be possible as the
convection passes. There is a possibility of very strong winds
(>50kts) with the storms. Ceilings will climb to VFR levels by
midday over most of the region. South winds will gust 15-20kts
this evening, and then increase to 20-25kts overnight into the
morning. As a cold front approaches and passes, west southwest
winds will gust 20-30kts at times.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...None.
MO...None.
IN...None.
KY...None.
&&
$$
DISCUSSION...ATL
AVIATION...DRS