Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/04/23
Area Forecast Discussion
National Weather Service La Crosse WI
1050 PM CDT Mon Apr 3 2023
.DISCUSSION...(This evening through Monday)
Issued at 231 PM CDT Mon Apr 3 2023
Key Messages:
- Latest model trends with the system for Tuesday suggest a
slightly slower timing and a more eastward track to the surface
low. This could allow the warm front to briefly work into
portions of the area in the evening. Main threats look to be
large hail and damaging winds with a conditional tornado
threat.
- Flow transitions to zonal with the next system dropping in from
the northwest and possibly bringing some rain to the upcoming
weekend.
Tuesday - Wednesday...
Focus is definitely on the system coming for Tuesday and the
possible severe weather impacts it may bring to the local area.
The system is now within the time range of the RAP and other hi-
res meso- scale models. Even looking at the broader global scale
models, there has been a subtle eastward shift of the surface low
track Tuesday afternoon and evening. Now, instead of the surface
low tracking across eastern Nebraska/western Iowa it may come out
of southeast Nebraska into north-central Iowa/southeast Minnesota.
In response to this, the warm sector and CAPE pools could get
brought farther to the north and west and bit more into the local
area, especially during the early evening hours. At 05.00Z the RAP
suggests the surface low should be advancing northeast across
western Iowa with the warm front stretched out in the U.S. Highway
20 corridor, just to the south of the area. The best surface
based CAPE will reside south of the front, but enough overrunning
moisture to push ML CAPE values into the 1000 J/kg range up to
about the Iowa/Minnesota border. By 05.03Z the RAP brings the
surface low into north-central Iowa with the warm front possibly
advancing north a couple rows of counties into the local area.
Surface dew points would climb into the middle to upper 50s with
SB CAPE coming up to around 1500 J/kg while the ML CAPE reaches up
into the Interstate 90 corridor. The whole pattern continues to
shift northeastward through the rest of the evening and overnight
with the warm sector gradually get pinched and pushed to the east
the cold front starts to undercut the warm sector.
As for storm modes, plenty of shear to work with, both deep layer
and in the lowest levels. With the strong upper level jet
rotating around the upper level low, 0-6 km shear values are
expected to be 60+ knots throughout the period when storms are
possible. Low level shear will be best in the vicinity of the warm
front and on the order of 30 to 40 knots. The question becomes
whether this shear will come into play or not. Forecast sounding
from the 03.09Z RAP suggest the low level moisture pool could be
rather shallow with the potential for an inversion/cap to remain
in place just above the surface. Hodographs show a large degree of
turning in the lowest 3 km and especially in the lowest 1 km.
However, if the cap holds and the lowest 1 km in taken out of the
equation, the hodograph becomes much less impressive and more
straight line. All this suggests hail and damaging winds are the
main threats with a conditional tornado threat.
Timing of when all this occurs looks to be the biggest wild card.
The 03.15Z RAP continues to trend in the same direction as what
the 03.09Z was showing but has slowed everything down just a
touch. This has resulted in the RAP not showing the warm front
edging into the area until about 05.02Z or so. The 12Z HREF is
displaying very similar trends to the RAP but it is even a bit
slower bringing the warm front in and confines the warm sector to
relatively small portion of northeast Iowa into southwest
Wisconsin.
Sunday...
After the next system moves past the region, a bit of a pattern
shift looks to take place. The southwest flow will give way to
zonal flow with the next system that comes in off the Pacific
expected to move across southern Canada before dropping southeast
across portions of the Upper Midwest into the Great Lakes over the
upcoming weekend. This looks to push a cold front across the
region with some precipitation expected to develop along it. Some
model differences on how much and when, but at least there is
agreement that if precipitation does occur, it will be warm enough
for just rain.
&&
.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1050 PM CDT Mon Apr 3 2023
As another potent spring upper wave moves into the central U.S. next
36 hours will see a variety of weather impact aviation conditions.
While VFR conditions prevail at moment, strengthening frontal zone
just south of the area will lead to an increasing cooler northeast
to east low level flow leading to eventual saturation and lowering
ceilings by daybreak Tuesday. In addition, warm air advection riding
over front will lead to elevated convection breaking out Tuesday
morning before lifting off to the northeast. This could lead to
widespread MVFR conditions with some IFR ceilings possible /20-30%/.
There could be a break in convective chances before stronger storms
form in warm sector to the south and ride northeastward over front
by early evening. Lower confidence in coverage for the later storm
threats but would expect at least scattered coverage to impact
aviation areas. Convective timing details will be worked out in near-
term periods.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
DISCUSSION...04
AVIATION...Shea
Area Forecast Discussion
National Weather Service Binghamton NY
932 PM EDT Mon Apr 3 2023
.SYNOPSIS...
A warm week is ahead, but there will be multiple chances for
showers throughout, with the potential for a few thunderstorms
Wednesday into Thursday. Drier and cooler conditions return for
the end of the work week into the weekend.
&&
.NEAR TERM /THROUGH TUESDAY NIGHT/...
Early this evening, radar returns are showing up now across
central NY. However, quite wide temperature/dewpoint spreads are
still present across the region. Increased the overall chance
of rain heading into the evening hours but decreased QPF with
only very light rain falling under the highest DBZ this evening.
However, shower coverage and intensity is expected to pick up
overnight north of the Twin Tears.
3 PM Update
Mostly sunny skies continue across the area late this afternoon.
Clouds are pushing into west-central NY as a weak frontal boundary
approaches from the north and west. Model guidance shows this front
slowly sagging south into the Twin Tiers by late evening, with showers
develop along and north of the boundary. Later tonight the front
loses it southward progression, stalling out near the US RTE 20
corridor...this will continue to be the focal point, north to
I-90 for periods of rain overnight. The HRRR and 3km NAM show
periods of moderate rain developing, perhaps even locally heavy
at times. There will be a tight gradient in QPF, with much lighter
rainfall amounts across the Twin Tiers, as only scattered
showers or patchy drizzle is expected. Current forecasts show a
1/4 to 3/4 of an inch of rain between US 20 and I-90 by Tuesday
morning, then quickly fading to less than a 1/10th an inch for
the Twin Tiers, and no measurable precipitation for the Wyoming
Valley region. There could also be some patchy fog late tonight
into Tuesday morning, especially for areas along and north of
the frontal boundary. Otherwise it will be cool with lows in the
upper 30s to mid-40s.
Heading into Tuesday, the front will remain stalled, bisecting CNY
early in the morning. Most of the shower activity will be confined
to our northern area, up toward I-90 in the morning. Then, the front
gradually lifts northward during the day. This will allow for some
partial clearing from the Twin Tiers south across NE PA. Temperatures
are progged to surge into the mid-60s to lower 70s for afternoon
highs from I-86/17 south across all of NE PA. Further north where
lower level clouds will linger much of the day, and surface winds
remain out of the east highs are only forecast to reach into the
50s..with some upper 40s for northern Oneida county. There will
be some modest instability due to the daytime heating, and this
may allow for isolated to scattered showers to redevelop south
of the front across the region; carried 20-35% PoPs for now to
cover this potential.
The boundary then pushed back north as a warm front Tuesday night,
as 850mb temperatures surge to +10C or even +12C before daybreak
Wednesday morning. Guidance shows some modest surface base CAPE back
across southwest/south-central PA. A few showers may roll through on
the west-southwest mid level flow. There is a minimal chance for a
rumble of thunder as the showers move north-northeast into our area.
However, overall PoPs are low and any showers will be isolated in
nature overnight. Temperatures hold in the mid-40s to mid-50s
overnight, and surface dew points also rise into this range. There
could be some patchy fog once again in this setup; although
southeast winds begin increasing later at night at 5-15 mph.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY/...
330 PM update...
Wednesday morning a warm front will lift north out of our area
putting the entire area in the warm sector. West of interstate
81 temperatures will rise to around 70 with dewpoints in the mid
and upper 50s. The Catskills to the Tug Hill will be about 10
degrees cooler. South winds will increase to 20 mph with gusts
to 30. Rounds of showers are expected with a slight chance of
afternoon thunderstorms in the north and west closet to the
approaching cold front. There will be some instability then but
forcing will be weak.
Stronger and possibly severe thunderstorms will move in
Wednesday night just ahead of the cold front. A low level jet in
excess of 50 kts will provide shear. Instability weakens with
saturated soundings. There is also low level turning so
tornadoes are possible too. Forcing is much better with upper
level short waves and the surface cold front. Temperatures and
dewpoints stay mostly in the 50s.
Thursday the cold front is on the way out to the southeast.
Showers and thunderstorms continue to the morning then taper
off to showers starting midday from north to south. Morning
highs will be from 60 north to low 70s south. Temperatures fall
into the 50s late in the day. Northwest winds will be breezy
behind the front but not as strong as Wednesday.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
330 PM update...
High pressure will dominate the weather pattern for this period.
On Thursday and Friday a cold front will continue to drop south.
A large area of high pressure over the Plains early Thursday
will be over the Great Lakes late Friday into Saturday with cool
dry air. As the high comes in northwest winds will be strong
keeping it cooler. Friday will be the coolest with 40s in CNY to
low to mid 50s in NEPA. Friday night lows will be in the 20s to
low 30s. With a warm southwest flow Sunday into Monday
temperatures will warm. Monday lows will be from the mid 30s to
mid 40s with highs in the 60s.
&&
.AVIATION /02Z TUESDAY THROUGH SATURDAY/...
A bit of a tricky aviation forecast, with just KAVP with high
confidence in seeing VFR conditions. Elsewhere across the
Central NY terminals, after mainly VFR conditions this evening,
MVFR to Fuel Alternate ceiling and visby restrictions will move
in overnight/early Tuesday morning. There is also the
possibility of seeing occasional IFR restrictions at KSYR and
KRME. Brief improvement is expected late Tuesday morning into
the early afternoon, before restrictions return later in the TAF
period. KSYR and KRME may see at least MVFR restrictions for the
entire TAF period.
Outlook...
Tuesday afternoon through Thursday...Lingering restrictions with
periods of showers, drizzle and low CIGs around
Friday through Saturday...Mainly VFR expected.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...None.
NY...None.
&&
$$
SYNOPSIS...MPK/MJM
NEAR TERM...MJM/MWG
SHORT TERM...TAC
LONG TERM...TAC
AVIATION...BJG
Area Forecast Discussion
National Weather Service Denver/Boulder CO
834 PM MDT Mon Apr 3 2023
.UPDATE...
Issued at 834 PM MDT Mon Apr 3 2023
The forecast over the next 24 hours remains very challenging
across northeast Colorado. Water vapor satellite imagery showing
good lift across Wyoming, eastern Utah, and the western half of
Colorado ahead of a strong upper level low over the Great Basin.
This lift will progress northeast through the overnight hours.
Tough call how far east it makes it. Most models keep the best
lift over Wyoming. However the 18Z ECWMF remains slightly farther
south and shows an inch of QPF for northern Larimer county
overnight. Don`t think this much precipitation will occur, but
increased PoPs for tonight and Tuesday morning for this and also
increased snowfall by an inch or two over the foothills and
mountains.
Also, there remains considerable uncertainty in where this
cyclogenesis occurs. The 18Z Canadian and ECMWF show the surface
low forming over southeast Colorado with the rest somewhere over
northeast Colorado. Favor the southern solution, so expect the
cold front to arrive early Tuesday morning. Chances for snow will
be better if this occurs, so nudged PoPs up as well for Tuesday
morning. Confidence isn`t very high in this solution, so didn`t go
crazy with PoPs or snowfall.
&&
.SHORT TERM...(This evening through Tuesday)
Issued at 259 PM MDT Mon Apr 3 2023
A complex forecast over the next 36 hours or so as another storm
system impacts our forecast area. A strong upper trough should
progress from the northern Great Basin eastward towards the Black
Hills by Tuesday afternoon. With both the 500mb and 700mb lows
tracking along the CO/WY border, this isn`t a particularly
favorable storm track for moisture across the plains, though the
mountains should benefit from another round of moderate to heavy
snow.
Regional radar and satellite data suggest snow is slowly
developing across the high country this afternoon, and should
continue to increase this evening into the overnight hours. A
briefly heavier period of snowfall... with rates of 1-2" per hour,
still looks likely tonight as strong 700-500mb frontogenesis and
increasing QG ascent should aid in efficient snowfall growth. This
mainly should impact the Park Range and Medicine Bow Range/RMNP,
though some of the I-70 corridor could pick up a quick inch or two
as well. As the upper low ejects into the plains, the flow aloft
should shift to the west, and orographic snow showers should
continue through the day Tuesday. Haven`t made any changes to the
highlights at this time.
Meanwhile, a strong surface low is expected to develop along the
eastern plains tonight/early tomorrow morning, with cold air
filtering into the urban corridor behind it. There is considerable
uncertainty in where this cyclogenesis occurs... with nearly a
250 mile spread between the HRRR (near Sterling) and some global
models (somewhere between Pueblo and Springfield) by 12z Tuesday.
These model differences have led to a low confidence forecast for
most of the plains on Tuesday. Most of the American models have
trended towards a drier solution for the morning, with a better
push of moisture arriving later in the day. Some ECM/RGEM/GEM runs
contradict this and have the main shot of cold air and light snow
coming during the morning hours. With little consistency at this
point, our current forecast lies somewhere in the middle. With a
strong jet/frontogenesis nearby, it`s always possible that a few
spots (mainly Larimer county) benefit more than our deterministic
forecast, and the evening shift will have to watch that potential.
.LONG TERM...(Tuesday night through Monday)
Issued at 259 PM MDT Mon Apr 3 2023
Tuesday night, the main upper level low will have moved to the north
and east of the region. A front will have pushed through the
region with northerly winds and cooler air behind it. Weak
synoptic ascent lingers over the region during the evening with
sufficient moisture. This will support the remaining showers to
move across the high country. The cooler airmass behind the front
should keep showers as snow. Northerly flow may provide some
component of upslope to enhance showers slightly in the southern
foothills and Palmer Divide. Overall, little accumulation is
anticipated with 1/2 to 2 inches for the favored areas mentioned
and no accumulation to a trace elsewhere for the lower elevations.
Dry subsident air works in early Weds keeping the plains dry and
decreases coverage of showers in the mountains through Weds AM.
A weak shortwave embedded in the northerly flow aloft behind the
previous system moves across the region Wednesday. Although weaker
than the main upper low of the trough, this system brings a period
of weak large scale ascent. Cross sections show limited moisture,
but it will be enough for showers in the mountains. Model
soundings show fairly steep lapse rates in the afternoon thanks to
the Spring daytime heating. This will also help initiate
scattered showers in the mountains and foothills. There is a
chance (20-30%) showers to move onto the adjacent plains and
Palmer Divide afternoon/early evening. Overall, accumulations, if
any... are expected to be minor. Snow showers decrease overnight
into Thursday.
Ensemble guidance supports general weak ridging aloft moving into
the region Thursday through the weekend. This will start a warming
and drying trend with temperatures approaching 70s territory
across the lower elevations by Saturday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 547 PM MDT Mon Apr 3 2023
A cyclone lifted northeast across the Denver area, passing just
east of KDEN. Northwest winds to prevail behind it and then
slowly back west to southwest this evening. For Tuesday,
challenging part of the forecast is where the surface low will
form. Models show anywhere from far northeast Colorado to
southeast Colorado. Favor the southern trend, which means a sooner
arrival of north winds/cold front and lower clouds for Tuesday
morning. Expect the cold front to push through 11-12Z with lower
clouds and hour or behind it or so. Ceilings of 2000 to 4000 feet
are expected for most of Tuesday. Lower ceilings and visibility
will accompany the snow showers. Better chance for this will be at
KBJC and KAPA.
&&
.FIRE WEATHER...
Issued at 259 PM MDT Mon Apr 3 2023
Fire danger should decrease on Tuesday with much cooler and wetter
conditions across the region. The exception to this may be Lincoln
county south of I-70, which may stay just south of the cold front
through the mid-afternoon. Some hi-res guidance supports a narrow
window of Red Flag conditions and our current forecast grids
support this as well. However, there still isn`t enough confidence
in how quickly/how far south the front will progress tomorrow
morning, and thus we`ve held off on any mention of highlights.
A warming a drying trend begins Thursday, extending into next
weekend. For the most part, winds remain light. It will become quite
dry with relative humidity values dropping into the 8-14 percent
range for Lincoln County, South Park, Palmer Divide and Denver
Metro. Friday through the weekend, winds over the Palmer Divide,
South Park, and Lincoln County may be just below critical values, so
elevated conditions can be expected in those areas.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning until midnight MDT Tuesday night for COZ031.
Winter Weather Advisory until midnight MDT Tuesday night for
COZ033.
&&
$$
UPDATE...Meier
SHORT TERM...Hiris
LONG TERM...Mensch
AVIATION...Meier
FIRE WEATHER...Hiris/Mensch
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1152 PM EDT Mon Apr 3 2023
.AVIATION...
Ceilings are expected to undergo a rapid drop to MVFR then IFR
during the overnight as ongoing rain cools and moistens the low
levels. The widespread rain associated with an elevated front will
exit to the east around 12Z, although some drizzle/light rain may
linger through the morning. Stratus will hold across Se Mi through
the day on Tuesday as the sfc front holds south of the state while
moisture is transported aloft north of the front. Model soundings do
suggest daytime heating will support some increase in ceiling
heights during the afternoon.
For DTW...Occasional showers will persist through the overnight,
with the more persistent showers expected north of metro. Weak
instability overnight will only support a slight chance of an
additional thunderstorm.
DTW THRESHOLD PROBABILITIES...
* High in ceilings below 5000 feet tonight and Tuesday.
* Low in thunderstorms tonight.
&&
.PREV DISCUSSION...
Issued at 856 PM EDT Mon Apr 3 2023
UPDATE...
An initial convective release earlier this evening resulted in an
area of thunderstorms which impacted portions of the northern Detroit
suburbs into the north third of the city of Detroit, and resulted in
rainfall amounts between .5 and .7 inches. While regional radar does
suggest a northward shift in the better frontogenetical forcing, weak
elevated instability along the south portions of the ongoing fgen region
suggests additional convective elements are possible south of the
main fgen band. This and given the earlier rainfall totals has prompted
the expansion of the flood watch to the M 59 corridor counties. There
was a very abrupt edge to the convection in Wayne County. So most of
the county has yet to receive much rain. Therefore, Wayne County was
not included in the watch expansion. If additional convective
elements impact the north sections of the city of Detroit, short
fused flood products (advisory or warning) will be issued.
The recent RAP continues to show very good system relative
frontogenesis tonight within the mid levels. Model cross sections
also show a very upright frontal circulation in the mid levels
persisting through the night. Regional radar is supportive of the
idea of a northward shift in the stronger frontal ascent. While this
raises concerns that Midland/Bay/Huron counties may need to be added
to the watch, the potential for an additional convective release
along the frontal slope may again cause the rain to focus a little
farther south. The very steep mid level lapse rates shown on the 00Z
DTX sounding also support this potential. These factors will warrant
holding off a northward expansion to the watch attm. Otherwise, total
rainfall within the watch area of 1 to 2 inches remains valid.
PREV DISCUSSION...
Issued at 323 PM EDT Mon Apr 3 2023
DISCUSSION...
A frontal boundary draped from low pressure over eastern Ontario
southwest through lower MI into the mid Mississippi Valley into
Kansas will sag south thru the region as this low continues east
into Quebec. Decent pool of moisture has pulled north into the
MO/southern IL and this will feed northeast into the region tonight
and focus along the frontal boundary as it stalls over the area.
This same air mass will also bring a decent ribbon of warm air
advection along the H85-H7 layer of this frontal surface which will
result in an expansion of the current rain banding now gradually
organizing from SW Lower MI back west along the WI/IL state line.
This moisture/warm air flux into the area will be enhanced by right
enhance jet dynamics with a relatively narrow, yet strong, fgen
response along this portion of the front. Have opted to issue a
Flood Watch generally along the I-69/M-46 corridor where rivers
continue to run high from the heavy rains (widespread 1.50-2.00")
late last week. The ground within this general area is saturated
given these recent rains, epsecially with the lack of any active
vegetative growth this early in the season, so flooding potential
seems to be a bit more elevated than usual. This will be especially
true if some HiRes model solutions for a 50-60 mile wide band of 1+
inches of rain with local amounts of 1.50-2.00" materializes. This
banding will come together late today and be most active as the jet
circulation enhances fgen from late this evening on through the
overnight.
This rain banding dissipates quickly into Tuesday morning as upper
supports strips away to the east with the frontal boundary sagging a
bit further south in its wake. A fairly wide range in temperatures
can be expected with this baroclinic zone draped over the southern
Great Lakes with highs around 60 along the MI/OH/IN state line
dropping back to the mid/upper 40s over northern parts of the area
with mid 50s common for most of the region.
This front then surges quickly back north late Tuesday night into
early Wednesday as a warm front in response to deep low pressure
developing over the central plains and then lifting northeast into
the upper midwest. Rain chances will increase substantially as this
front works back north through the region and lift from the strong
storm system to the west begins to overspread the area. A much
warmer airmass in the wake of this front will lead to warming
temperatures overnight after evening lows in the 40s to around 50.
By daybreak Wednesday, expect widespread 60s, especially over the
southwest half of the forecast area.
The warm front will continue north Wednesday and the warm sector of
this storm system will overspread all of Southeast Michigan with
highs in the lower to locally mid 70s in many locations and dew
points also climbing into the lower 60s. These springtime conditions
will lead to the potential for severe thunderstorms as at least
modest instability develops over the area with time. Impressive
shear values associated with the strong wind field from this large
low pressure system will be supportive of convective organization as
a cold front pivots east through the area during the afternoon to
early evening. This should support a squall line of some sort with
intensity depending largely on how much destabilization is able to
occur during the day. While the overall surface flow is veered to
south/southwest by this point, strong speed shear and some veering
with height still leads to very long hodographs which suggests there
may be some tornadic risk within more discrete cells either in
advance of the cold front/squall line or within kinked portions of
the potential line. Otherwise, damaging straight-line winds will be
the main threat with some potential for large hail in the strongest,
most well organized updrafts.
In the wake of this busy early/mid week period, much quieter
conditions set up from late week into the weekend as a large high
pressure system settles east/southeast through the area from Canada.
Much cooler conditions with highs in the 40s/50s are expect Thursday
into Friday as the high encroaches on the areas with moderation into
the weekend, back into the 50s/60s, as the high continues on to the
east and southerly return flow develops.
MARINE...
A warm front tied to developing low pressure over the Midwest
gradually lifts through the central Great Lakes over the course of
Tuesday. A tightening gradient leads to strengthening east-northerly
flow in advance of the front focused over the northern part of Lake
Huron. With a still cool resident airmass, neutral to slightly
unstable thermal profiles will support gusts firmly within gale
territory Tuesday evening into early Wednesday morning. As a result,
a Gale Watch has been issued over the northern half of the lake.
Given the wind direction, waves increase around the Thumb
Tuesday/Wednesday warranting Small Craft Advisories for the
nearshore waters. The aforementioned strong low pressure lifts
through the northern Great Lakes late Wednesday driving a strong
cold front through the central Great Lakes Wednesday night-early
Thursday. Scattered strong to severe thunderstorms will be possible
across the region in advance of the front daytime Wednesday. Strong
cold air advection post-front offers another window for
potential gales Thursday.
HYDROLOGY...
A band of rainfall with embedded thunderstorm will set up this
evening centered near the I-69 corridor with rainfall amounts of an
inch or more expected within a relatively narrow band between M-59
and M-46. Localized amounts may near 2 inches by early Tuesday
morning. A Flood Watch has been issued with some flooding possible
over this region and significant rises in area rivers expected.
Additional showers and thunderstorms can be expected again Tuesday
night into Thursday as a strong low pressure system organizes to the
west. Initial rain will occur along a warm front lifting north over
the area with a cold front bringing showers and thunderstorms by
Wednesday afternoon and evening. Locally heavy rainfall may lead to
additional flooding concerns over parts of the area.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...Flood Watch until 8 AM EDT Tuesday for MIZ053>055-060>063-068>070.
Lake Huron...Small Craft Advisory from 5 PM Tuesday to 4 PM EDT Wednesday for
LHZ442-443.
Gale Warning from 5 PM Tuesday to 10 AM EDT Wednesday for LHZ361-
362.
Small Craft Advisory from 10 AM Tuesday to 4 PM EDT Wednesday for
LHZ421-422-441.
Lake St Clair...None.
Michigan waters of Lake Erie...Small Craft Advisory from 5 PM Tuesday to 4 PM EDT Wednesday for
LEZ444.
&&
$$
AVIATION.....SC
UPDATE.......SC
DISCUSSION...DG
MARINE.......KDK
HYDROLOGY....DG
You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.
AREA FORECAST DISCUSSION
National Weather Service Kansas City/Pleasant Hill MO
620 PM CDT Mon Apr 3 2023
.Discussion...
Issued at 412 PM CDT MON APR 3 2023
Key Messages:
- Strong Thunderstorms Forecast Tuesday & Tuesday Night
- Severe Potential There; Capping Inversion May Hold Activity Back
- Strong Non-Thunderstorms Winds Tuesday
Discussion:
Confidence in occurrence of Tuesday afternoon thunderstorms: Medium.
Confidence in occurrence of severe storms if thunderstorms develop in
the afternoon: Medium-High
Confidence in occurrence of a squall line late Tuesday Night: Medium
Confidence in Non-Thunderstorm Wind Gusts Tuesday afternoon and
evening: Medium-High
The stationary boundary that dropped into the area last night is
currently positioned between Hwy. 36 and Interstate 70. Temperatures
have been in the mid 50s in northern Missouri, with mid 70s south of
Interstate 70. This boundary may sink to around Interstate 44, so
expect temperatures in the upper 50s for most of the forecast area
this evening. A few isolated showers are possible along the boundary
as moisture transport has increased south of the boundary. These
showers tonight do not appear to present any substantial threat.
The main PV anomaly has arrived in the west coast. A deep H5 trough
has developed in this area and the H5 jetstreak of 100+ kts is
starting to approach the trough axis. The trough will continue to
dig for the next 6-8 hours into the desert southwest. Strong CVA has
been occurring downstream of the trough axis. A broad area of WAA and
dCVA have phased favorable for robust lee cyclogenesis, and a
distinct cyclone is already analyzed over the Front Range. There has
already been response, with a surface trough extending eastward
across the Plains into the western Ohio River Valley. This roughly
has aligned with the thermal boundary that is oriented across the
forecast area. South of the boundary, the southerly flow has
provided strong WAA and some insentropic ascent. While the boundary
layer remains very dry, dewpoints have slowly increased this
afternoon, and cloud cover has developed indicating that moisture
return is underway for eastern Kansas through Central Missouri. As
the 100+ kt jet moves across the trough axis, the H5 trough will
steadily lift northeast out of the desert southwest. This will
continue to phase dCVA over the center of the surface cyclone, and
deepening of the system will continue. In response to the WAA over
the Ohio River Valley, there may be brief rise in H5 heights at some
point overnight with weak subsidence that will clear out the cloud
cover and suppress shower activity. This however will be short-lived
but important for setting the stage Tuesday afternoon for a severe
convective threat. It will not be too long before the stronger CVA
arrives in the forecast area and the H5 height falls take place over
the eastern Plains into the middle Mississippi River Valley. Tuesday
mid to late morning, the area will likely see some upper-level
diffluence and enhanced isentropic ascent, which may be able to
force a few light showers and thunderstorms. However, 12z CAM
guidance from this morning was not overly in favor of this. The main
limiting factor will be the southwesterly 700-500mb winds bringing
in an strong EML that creates a strong inversion over most of the
area Tuesday morning through Tuesday afternoon. Even elevated
parcels may run into problems initiating convection due to
entrainment of very dry air. Slight chance POPs have been put into
the forecast for a few hours Tuesday morning to account this
potential, as a weak lobe of vorticity may provide some kinematic
forcing for elevated activity. By Tuesday afternoon, the nose of the
H5 jet streak begins to enter eastern Kansas. By this time, the warm
front will have surged northward into Iowa. However, the surface
cyclone will promote surface pressure falls across most of the area,
and right now looks most robust for the northeast portion of the
forecast area. Tuesday after 18z is when the severe threat begins
for our forecast area. There are multiple scenarios that could play
out over two rounds. First, will be the threat for discrete
supercells in the afternoon, mainly north of I-70 and east of I-35.
Second round will present the potential for QLCS potential. If the
the -150 J/kg of CIN does not erode and the dryline ahead of the
cold front moves through, the afternoon discrete threat may not
materialize, but could still see a QLCS late into the evening.
Second scenario, that cap cannot be overcome, and the dryline mixes
the boundary so much that the cold front does have enough moisture
to develop a QLCS. However, any convection that develops tomorrow
after 17-18z will present a severe threat. The next paragraph will
discuss the afternoon discrete threat on the conditions we see
initiation, and the paragraph after that will discuss details of
what a QLCS would do if it develops.
Model consensus on a potent warm sector with this surface cyclone is
strong. Probabilities for SBCAPE over 1000 J/kg is above 99 percent,
and most solutions are producing SBCAPE over 2000 J/kg. Deep layer
shear will not be an issue at all with the 100 kt jet streak. Bulk
shear values of 0-6km will start out around 50 kts, and could
increase to 70 kts or beyond. Most of the warm sector will hold a
threat for initialization if the cap can break, and present wind,
hail and tornadic hazards. At this time, the most favorable for the
strongest supercells would be our northeast in the area that is
highlighted by the moderate risk. With the EML in place, mid-level
lapse rates will likely exceed 8.0 C/km, and the boundary layer may
become dry adiabatic before hitting the cap. Between 15-18z, the low-
level winds (0-1km) will mainly be dominated by speed shear, with
weak backing in the 2-4km layer. While storm-relative inflows may be
on the stronger side around 30 kts, but overall the combination of
thermodynamics and wind shear profile should support hail. Theta-e
deficits within the boundary layer will be very strong as well,
which will allow strong cold pools and perhaps stronger RFDs to
punch through and cause damaging winds. The hail and wind threat
applies to most the Day 2 Enhanced Risk area. Tornadoes, while
possible, will have struggles in most of our forecast area. While 0-
1 km SRH values climb above 200 m^2s/s^2, most areas outside the
moderate risk area have a mean wind motion that provides more
crosswise vorticity ingestion than streamwise. The SRH values are
greatly being augmented by the strength of environmental vorticity
and stronger storm-relative winds. The fast storm motions of 40-50
kts may make it difficult to deviate to the right for the favorable
streamwise vorticity ingest in our forecast area. A tornado could
still be produced by any supercell even outside of the moderate risk
if perhaps if it finds a mechanism to take the crosswise vorticity
and make it streamwise. Supercells that develop a right deviant
motion though will be able to ingest more helicity and strengthen.
The further northeast in Missouri you look and then into eastern
Iowa and western Illinois, the low-level hodographs become much more
favorable, as areas closer to the warm front and center of the
surface cyclone will have backed surface winds out of the southeast.
In this area, even storms that initialize and first move with the
mean wind will be able to realize more streamwise vorticity ingest,
and thus present a higher tornado probability. Further, looking at
the 12z HREF output, the stronger updraft helicity tracks are
concentrated where the surface winds are more backed. Main
contributions for that are from the NSSL-WRF and Hires FV3. The HRRR
so far has been keeping most of the forecast dry, unable to break
the cap until the convergence increases east of the forecast area.
If storms initiate in the afternoon, it will likely be near the KC
metro, with the severe threat then increasing as storms move east.
Confidence is a bit iffy in the western parts of our area. If the
surface low ends up tracking further northwest of the area, perhaps
the threats get pulled back. However, there is not much support for
that.
At some point, another dryline mixes eastward across Kansas into
Missouri, and will eat away at the moisture and also bring strong
non-thunderstorm wind gusts. The wind advisory highlights the area
of 45 to 50 MPH wind gusts. Attention then turns to the cold front
back over the High Plains Kansas. Currently, even with the strong
mixing of the dryline, the HRRR continues to develop a line of
thunderstorms along the cold front, and rather strong storms. Other
members of the HREF also develop weak updraft helicity tracks across
this line. If there is a large temporal separation between afternoon
activity and the evening, CAPE may be able to recharge across the
forecast area again. If the cold front accelerates faster than the
dry line mixing eastward, the cold front`s convergence may actually
have a moist boundary layer to work with. If a QLCS develops, expect
the typical straight line wind threats, as cold pools will be
strong. In addition, a LLJ kicks in, and some of that momentum
likely gets dragged down. There is also potential for QLCS
mesovortex generation, that could present a QLCS tornado threat.
Currently, 0-3km bulk shear vectors are progged at 50 kts with a
west-southwest orientation, which provides a substantial orthogonal
component to the cold front itself, and component to a QLCS itself.
With 0-3km CAPE exceeding 75 J/kg and strong wind shear, line surges
and bowing segments can easily meet the three basic ingredients for
mesovortex generation, resulting in QLCS tornadoes and enhanced
winds. This could be a problematic situation with this being
overnight, as in some instances this could happen in few a minutes,
not to mention line propagation speeds of 45-50 kts possible. Even
if the mesovortex generation threat is not realized, a QLCS if it
develops will still present a straight line wind threat.
Beyond Tuesday, expect neutral conditions with zonal flow. Chances
for rain activity return by the end of week.
&&
.Aviation...(For the 00Z TAFS through 00Z Tuesday Evening)
Issued at 611 PM CDT MON APR 3 2023
MVFR to IFR conditions are expected to develop north of highway 36
overnight. Strong southerly winds are expected to develop on
Tuesday, with the potential for storms after 18Z. Best chances for
storms are east of highway 65 through 00Z Wednesday, so did not
include mention at this point.
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
KS...Wind Advisory from 2 PM Tuesday to 1 AM CDT Wednesday for KSZ025-
057-060-102>105.
MO...Wind Advisory from 2 PM Tuesday to 1 AM CDT Wednesday for
MOZ012>015-020>023-028>031-037>039-043>045-053-054.
Wind Advisory from 7 PM Tuesday to 1 AM CDT Wednesday for MOZ007-
008-016-017-024-025-032-033-040-046.
&&
VFR conditions will
$$
Discussion...Krull
Aviation...BT
AREA FORECAST DISCUSSION
National Weather Service Hastings NE
633 PM CDT Mon Apr 3 2023
...AVIATION UPDATE...
.DISCUSSION...(This evening through Monday)
Issued at 225 PM CDT Mon Apr 3 2023
Key Messages:
* Light drizzle is expected to develop and fill in across much of
the area overnight tonight, but with temperatures remaining
above freezing, mixed precipitation is not a concern.
* Critical Fire Weather concerns are expected ahead of a powerful
upper level system Tuesday afternoon. The worst conditions are
expected across the southeastern portions of the local
area...where a Red Flag warning is in effect.
* Blowing dust ahead of the associated cold front Tuesday
afternoon could also result in reduced visibilities across
mainly north central Kansas.
* Light snow combined with near-severe wind gusts behind the cold
front could result in reduced visibilities in pockets of light
snow Tuesday evening.
* Mainly dry weather anticipated over the remainder of the period
with multiple days resulting in additional fire weather
concerns.
A powerful upper level system over southern California will
emerge into the plains over the next 24 to 36 hours. This low is
expected to further intensify as it moves across the local
area...resulting in intense winds, extreme fire weather conditions
and bringing some small chances for precipitation.
Ahead of this system...models are indicating increasing moisture
across the region overnight...which should eventually saturate the
lowest layers of the atmosphere and potentially bring some light
drizzle by daybreak Tuesday. Model soundings have a classic
drizzle look to them...with very dry air above the saturated
layer...as does simulated reflectivity in model data...and expect
a dreary and drizzly start to the day Tuesday. Despite this
start...expect clearing and eventually good mixing and strong
southwesterly winds to develop ahead of an approaching cold
front...which will result in the anticipated critical fire weather
concerns. If the NAM/NAMnest is correct...winds ahead of the front
may be a bit overdone...but given the very strong winds in HRRR
and other meso-scale guidance...went and upgraded the fire weather
watch to a Red Flag warning early in the shift for the areas with
the greatest potential to see the warmer/windy conditions.
Behind the front...could see some light precip...but overall this
will not amount to much...with overall only a dusting to a few
tenths of an inch of snow expected to accumulate across the
northwestern fringes of the area. If snow is realized...however...
the very strong winds associated with the intensifying upper
level low will likely result in areas of reduced visbility.
Beyond this system...mainly zonal and uneventful upper level flow
is anticipated across the region...with a rapid return to above
normal temperatures anticipated by the end of the week with
multiple potential fire weather days expected through next
weekend.
&&
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Wednesday)
Issued at 626 PM CDT Mon Apr 3 2023
Expect VFR CIGS to prevail through the evening hours as mid-
level clouds begin to filter back into the area early this
evening. Expect MVFR CIGS to move in later tonight...eventually
falling and becoming IFR overnight as the atmosphere moistens and
some light drizzle develops. This drizzle along with low CIGS
should remain through much of the morning Tuesday. Winds will
begin to relax ahead of the next front around mid-morning and CIGS
will begin to improve during the afternoon. Winds will once again
increase, this time out of the southwest, with VFR CIGS mid- to
late Tuesday afternoon.
&&
.FIRE WEATHER...
Issued at 225 PM CDT Mon Apr 3 2023
Breezy northeasterly winds and minimum relative humidity values
near 25 percent are resulting in near critical fire weather
conditions across much of the local area this afternoon. This has
been aided by thinner cloud cover and deeper mixing than
originally anticipated. The more critical Fire weather conditions
are expected across the local area Tuesday when increasing
southwesterly winds and a further spike in temperatures will allow
relative humidity values to fall between 10 and 20 percent. The
worst conditions Tuesday are expected across north central Kansas
as well as portions of south central Nebraska generally south of a
York-Cambridge line...where a Red Flag warning is in effect from
noon to 8 PM CDT.
While much cooler air will filter in behind this cold front on
Wednesday, could still see near-critical fire weather conditions
during the afternoon hours as much drier air also filters in
across the region. Additional fire weather concerns are possible
Friday and possibly into next weekend as well.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...Red Flag Warning from noon to 8 PM CDT Tuesday for NEZ063-064-
073>077-082>087.
KS...Red Flag Warning from noon to 8 PM CDT Tuesday for KSZ005>007-
017>019.
&&
$$
DISCUSSION...Rossi
AVIATION...Hickford
FIRE WEATHER...Rossi
Area Forecast Discussion
National Weather Service Grand Junction CO
552 PM MDT Mon Apr 3 2023
.SHORT TERM...(Tonight through Tuesday night)
Issued at 302 PM MDT Mon Apr 3 2023
Showers have been slow to develop across the majority of the
forecast area this afternoon with returns gradually increasing
over the last hour or so. Activity has been persistent over
northeast Utah and the Northwest Colorado Plateau with SNOTELs
already reporting 2 to 5 inches of snow over the Eastern Uinta
Mountains. This has mostly been due to the presence of a weak
midlevel front as well as the relatively stationary 110 to 130 kt
jetstreak throughout the morning. Said jet has also resulted in
the tightening of the southwest gradient aloft across the Western
Slope as the Pacific trough digs into the Great Basin and as the
jet begins to encompass the rest of the region. Pacific moisture
has advected into the region from the southwest with precipitable
water (PWAT) values projected to reach 120% of normal by late this
afternoon. Even with this uptick in moisture there is still some
dry air situated in the lower levels of the atmosphere, as evident
by the 12Z GJT sounding as well as current dewpoints in the upper
teens to low 20s this afternoon. Warm air advection due to the
mild southwest flow has allowed temperatures to jump to near or
slightly above normal this afternoon, resulting in an even broader
T/Td gradient. Instability fueled by the warm air combined with
the jet aloft has led to deep mixing across the forecast area this
afternoon. As expected, surface gusts have exceeded 60 mph in the
southern and central mountains with gusts to near 50 mph so far
in the valleys. Winds will only continue to increase as the day
goes on and as the main cold front approaches from the northwest,
resulting in the development of virga showers in the aforementioned
locations with dry air lingering towards the surface. NBM winds
have already under-produced for some of the central zones over the
last couple of hours, so blended in some 90th percentile to
better represent current conditions. This has also led to an
increase in projected winds for said areas later today and, as a
result, went ahead and upgraded the Wind Advisories to High Wind
Warnings for the Roan and Tavaputs Plateaus as well as the I-70
corridor from Debeque east towards Edwards. The remainder of the
wind highlights are still on track and set to drop off at 11 PM
this evening, but could be extended later in the night depending
on where things are at. As noted previously, these strong southwest
winds will lead to increased potential for blowing dust, focused
along the Four Corners region. Latest DEBRA satellite imagery shows
thick dust impacting southern California and southern Nevada for
the last several hours and, most recently, the development of blowing
dust over northern New Mexico, just south of the San Juan River
Basin. Will continue to monitor the latest trends to see if this
plume will reach our CWA later today and lead to any reduced
visibilities.
CAM guidance, particularly the NAMNest, is still highlighting the
potential for a band of showers to develop from southeast Utah
northeast into the Flat Tops late this afternoon. The HRRR is not
as on board with this trend but, given the projected frontogenesis
as the midlevel boundary begins to finally nudge further east and
due to the already present instability, would not be surprised to
see the band materialize. Again, this won`t remedy the dry low
levels so virga will still be a concern for the southern and
central valleys in particular as we head into the early evening
hours. The atmosphere will finally saturate tonight as the Pacific
trough and associated surface front begins to lift across the
area. Broad-scale ascent will be maximized across the Western
Slope during the 00Z to 12Z period tonight and Tuesday morning,
resulting in numerous showers, particularly across the higher
terrain. Cold air will quickly advect into the area in the wake of
the front with 700mb temperatures still on track to reach 10 to
15 degrees C below normal by Tuesday morning. Snow levels will
crash to the remaining valley floors as a result with light
accumulations of half an inch to 3 inches expected. Warm antecedent
conditions will minimize accumulations on the roads so impacts in
the lower elevations (apart from the Northwest Plateau) will be
minimal. Travel will continue to be hazardous in the mountains
into Tuesday due to the impacts from snow and wind.
Mid to late Tuesday afternoon will see the axis of the upper
level trough straddle the Continental Divide. The abnormally cold
airmass in place in the wake of the system will result in steepened
lapse rates across the Western Slope Tuesday afternoon. Showers
will become more convectively-driven as a result with CAM guidance
anticipating some additional bands of snow setting up by mid
afternoon. Even though the jet will have shifted east of the
Divide by Tuesday afternoon, a continued tight gradient aloft will
result in breezy post-frontal conditions. While certainly not on
the magnitude of this afternoon`s winds, gusts will still be
between 25 to 35 mph on Tuesday. The combination of convective
snow showers and breezy conditions will see hazardous travel
remain a threat into Tuesday evening. Therefore, made no changes
to the ongoing winter highlights with this afternoon`s package.
Showers will quickly taper off in coverage after sunset Tuesday
night, though isolated activity will linger over the higher
terrain into early Wednesday.
After a mild day today, high temperatures on Tuesday will drop
back to well below normal. These values will also be some 20 to 25
degrees cooler than this afternoon. Tonight`s lows will begin to
tick down compared to this morning as the front begins to move
through the northern zones, but the real change comes on Tuesday
night/early Wednesday morning behind the front and as the denser
cloud cover begins to dissipate. More on the values and where they
will sit compared to normal in the long term discussion below.
.LONG TERM...(Wednesday through Monday)
Issued at 302 PM MDT Mon Apr 3 2023
Anomalously cold temperatures will blanket the West Slope Wednesday
morning in the wake of a spring snowstorm. Morning lows will sit
somewhere between 10-15 degrees under early April normals across
much of the region. Instability behind the cold front should help
with a few straggler showers on Wednesday. This will likely wring
out another 1-2 inches of snow across the higher terrain, but
nothing like we saw with the main body of the storm on Tuesday. High
sun angles and longer daylight are on our side with these late
season storms and this one`s bite should get tempered rather quickly
as weak ridging builds in late Wednesday. Temperatures Thursday
and Friday should see a bump of nearly 10 degrees each day.
Climatological normals should return for the weekend, as deterministic
models begin to sell a high amplitude ridge gaining traction over
the Intermountain West.
Uncertainty creeps in Saturday evening, when the GFS would like to
drag the trough of a Canadian Border clipper low through our
northern mountains. Confidence is pretty low in this feature. In the
event of any precipitation making it this far south on Saturday, I
can`t see any totals requiring highlights at this time. Height rises
are expected to continue Sunday and Monday as a strong southwesterly
jet max pushes the warmest air of the season into the region. Some
temperature guidance is forecasting low desert valleys in the 70`s
by Monday with mountain towns in the low 60`s.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 540 PM MDT Mon Apr 3 2023
Strong southwest winds will persist ahead of a cold front, which
is currently draped across northwest Colorado, nosing into
southeast Utah. This frontal boundary will continue to trudge
east, southeast through this evening and weaken as it crosses the
Divide between 09 to 12Z Tuesday morning. Expert periods of
lowered CIGs and VIS as the boundary crosses over remaining TAF
sites east of the boundary. Aviation conditions drop below MVFR,
with periods down to IFR, due to snow or rain mixed with snow.
Sustained winds of 25-35 kts are also anticipated ahead and along
the frontal boundary, decreases to 15-25 kts in its wake. However,
unsettled weather and scattered precipitation in the wake of the
front maintain poor aviation conditions with VCSH likely for
nearly every TAF site and wind gusts of 20-35 kts extending
through Tuesday afternoon.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...Winter Storm Warning until 6 AM MDT Tuesday for COZ001.
Wind Advisory until 11 PM MDT this evening for COZ002-014-018-
019-023.
High Wind Warning until 11 PM MDT this evening for COZ003-
006>008-011-017-020>022.
Winter Weather Advisory until 9 PM MDT Tuesday for COZ003-009-
010-012.
Winter Storm Warning until midnight MDT Tuesday night for COZ004-
013.
Winter Weather Advisory until 9 PM MDT Tuesday for COZ017>019.
UT...High Wind Warning until 11 PM MDT this evening for UTZ022-025-
027>029.
Winter Weather Advisory until 9 PM MDT Tuesday for UTZ028.
Winter Storm Warning until 6 PM MDT Tuesday for UTZ023.
&&
$$
SHORT TERM...MMS
LONG TERM...LTB
AVIATION...ERW
Area Forecast Discussion
National Weather Service Grand Rapids MI
952 PM EDT Mon Apr 3 2023
LATEST UPDATE...
Update
.UPDATE...
Issued at 952 PM EDT Mon Apr 3 2023
Narrow FGEN band of locally heavy rainfall depicted by HiRes
guidance appears to be setting up a bit farther north than
expected; from Oceana County to Isabella County. Latest RAP
guidance shows best 700 mb FGEN persisting in this area overnight
although scattered to numerous convective elements will continue
to stream in from the southwest south of that main band. Will
expand the Flood Watch one row of counties north momentarily.
&&
.DISCUSSION...(This evening through next Monday)
Issued at 335 PM EDT Mon Apr 3 2023
-- Flood Potential Tonight --
A sloped frontal surface from near the south state line at 850 mb to
near I-96 at 700 mb will undergo frontogenesis tonight while strong
southwesterly moisture transport impinges on the front at 700 mb.
Above 700 mb, lapse rates will be moist-neutral if not slightly
conditionally unstable. As upward vertical motions are augmented on
the warm side in ageostrophic response to the frontogenesis, a
focused band of precip development is expected much of the night in
the vicinity of I-96 while scattered quasi-convective showers
develop to the south toward I-94.
An increasing number of models among the HREF plus several runs of
the HRRR have increased the concentration and max rainfall amounts
for tonight, up from 0.5-1.0 to 1.0-1.5 inch, in a 30-mile wide
stripe from the vicinity of Grand Haven to St Johns. Following what
is a Top 10 wettest year-to-date at Lansing and Muskegon, and a Top
1-2 wettest year-to-date at Grand Rapids and Kalamazoo, the risk of
areal flooding increases with each successive heavy rain event.
Friday`s thunderstorms already produced urban and low-lying flooding
in areas that saw 1.5 to 2 inches of rain. Rain intensity tonight
will be relatively moderated, and as such, the expectation for flash
flooding is not high, but water over low-lying areas including dips
in roadways is a concern in the dark night. Occasional lightning is
also possible.
-- Severe Thunderstorm Potential Tuesday to Wednesday --
Unlike Friday when numerous thunderstorms were likely but it was
questionable how many would be severe, Tuesday night to Wednesday
has the opposite problem, as it`s questionable how many
thunderstorms will develop, but any cell that does develop has a
greater individual chance of being severe. Several opportunities for
scattered thunderstorm development exist from Tuesday evening
through Wednesday afternoon.
Elevated convective cells with a large hail threat are possible
Tuesday evening deep into the night, to the north of the advancing
surface warm front, as convergence on the nose of a strengthening
low-level jet increases along the northward-sloped warm frontal
surface. One significant wildcard will be the degree of 700 mb
capping above the moist layer and under the presence of the upper-
level ridge. From the capping layer up to 500 mb will be steep lapse
rates as great as 8 C/km, an Elevated Mixed Layer supplied from
Monday`s atmosphere in the high elevations of Colorado to West Texas.
If cells of deep convection do occur, up to 1500 J/kg of CAPE and
pockets of moderate upper-level shear support a large hail threat.
The surface warm front is progged to progress through Lower Michigan
from late Tue evening to Wed morning. Temperatures will rise during
the night, and with that will the threat for damaging wind gusts
from any thunderstorms. A broad synoptic 55 knot wind field at 925
mb (beneath 1 km) will be established during the early morning hours
Wednesday in the warm sector. Thunderstorm development remains
questionable and model solutions varied for this time frame, mostly
due to uncertainty in upstream convective development and
convective inhibition.
Going into late Wed morning and early Wed afternoon, a trend toward
slower cold front arrival may increase the threat of scattered
severe thunderstorms capable of all hazards including tornadoes over
Lower Michigan. The minutia of mesoscale details at that point in
time are unforeseeable for now. However, even absent any
thunderstorms, we may be flirting with advisory-strength winds
during the day Wed.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 753 PM EDT Mon Apr 3 2023
VFR prevailing for a few more hours but conditions trending down
later this evening as rain intensity/coverage increases. By 06z
most of the terminals should have IFR conditions which will
continue through the day Tuesday. Showers are expected to
decrease in intensity and coverage early Tuesday morning, but
occasional drizzle/mist and/or widely scattered showers should
still linger through the day. Can`t rule out a few tstms tonight
but given the isolated nature and low confidence did not include
them in the TAFs. East winds increasing on Tuesday to 12-22 kts.
&&
.MARINE...
Issued at 335 PM EDT Mon Apr 3 2023
Small craft advisory will be issued for increasingly strong east
winds on Tuesday, becoming south-southwest on Wednesday. Strong
winds (gale force strength) will be present above a stable but
shallow cold marine layer on Wed so this will have to be monitored
closely. Thunderstorms over Lake Michigan capable of large hail are
possible Tuesday evening through Wednesday morning.
&&
.HYDROLOGY...
Issued at 350 PM EDT Mon Apr 3 2023
With a narrow band of heavy rain expected to develop overnight
tonight, the risk of localized flooding will be focused generally
along the I-96 corridor. Most at-risk will be small creeks and
streams, as well as other low-spots and areas with poor drainage.
The other concern focuses on the rivers. With each round of heavy
rain, the soils get re-saturated, the creeks and streams swell, and
the larger rivers continue to rise. With two more rounds of rain
expected over the next few days, the Grand River basin looks like it
could get hit by both of them, which will prolong and possibly
worsen the flooding that is already happening along the tributaries
of the Grand (Maple, Thornapple, and Red Cedar). Additionally, the
Grand River itself near Comstock Park is now expected to stay above
flood levels for much of the week.
Further north, water levels are starting to fall along the Muskegon
River, but this will be short-lived as the rain Tuesday Night and
Wednesday will get river levels rising again. At this point it`s
unclear if water will again reach flood levels, but anyone living or
recreating along the river should pay extra attention to the river
forecast as the week progresses.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Flood Watch until 8 AM EDT Tuesday for MIZ050>052-056>059-
064>067.
LM...Small Craft Advisory from noon Tuesday to 8 PM EDT Wednesday for
LMZ844>849.
&&
$$
UPDATE...Meade
DISCUSSION...CAS
AVIATION...Meade
HYDROLOGY...AMD
MARINE...CAS
Area Forecast Discussion
National Weather Service Gray ME
1140 PM EDT Mon Apr 3 2023
.SYNOPSIS...
High pressure crests the East Coast today with a southerly
breeze, then a clipper brings some rain and snow showers mainly
north tonight. High pressure builds in from the north for the
middle of the week and sets the stage for a cold air damming to
develop, meanwhile low pressure moves into the Great Lakes and
brings widespread precipitation to the area with potential for
mixed precipitation over the cold air dam. High pressure will
build in behind this system`s cold front late in the week, with
gusty winds on Friday. High pressure remains in control this
upcoming weekend.
&&
.NEAR TERM /THROUGH TUESDAY/...
1140 PM Update...Subtle short wave is now crossing the crown of
Maine with a band of Fgen forced precipitation shifting ever so
slightly southward. Temperatures have trended warmer than
previous forecast and have blended in recent obs with hi res
guidance to bring them up over the next couple of hours. Surface
obs shows precipitation is reaching the ground in the form of
light rain under most recent radar returns and have adjusted
weather grids to account for more in the way of rain showers
than snow showers.
640 PM Update...Forecast is in good shape this evening with area
webcams showing some light snow showers across the north under
the more robust returns on radar. Observations under areas of
weaker returns suggest precipitation is not reaching the ground.
Have mainly fine tuned PoPs based on latest runs of the HRRR
with increasing chances for snow and possibly rain showers
across the north over the next few hours as a short wave crosses
Quebec sending a cold front into northern zones. Otherwise have
refreshed near term temperatures to capture the latest round of
observations.
Previously...
A clipper type system will exit through eastern Canada tonight.
Warm air advection over northern areas this evening will be
replaced by cold air advection in the mountains as a front slips
through the region. This system remain relatively moisture
starved, however some rain and snow showers can be expected
across the north. The latest HRRR suggested scattered light
rain showers may reach southern areas later tonight with this
feature.
Overnight lows will be milder than last night. Mostly 30s can be
expected in the north with upper 30s to lower 40s in the south.
&&
.SHORT TERM /TUESDAY NIGHT/...
The front will become quasi-stationary Tuesday near the New
Hampshire and Massachusetts border. This may allow for a couple
light rain showers over southern areas. Temperatures will
struggle through the 40s in Maine, but readings may reach the
50s for highs over southern New Hampshire.
By Tuesday night, a strong high pressure system will attempt to
build into our region with cold temperatures and lowering dew
points entering northern portions of the forecast area.
Meanwhile, the stationary front will attempt to move northwards
as a warm front setting up a strong frontal zone across the
region. Temperature profiles suggest that as boundary layer
temperatures begin to cool and cold air damming takes hold,
some of the light rain showers will change to light freezing
rain by late at night. This mix will be confined to northern
areas.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Overview: Potentially impactful wintry mix event Wednesday
evening into early Thursday for western ME and northern NH.
Temperatures rebound Thursday, with wet weather continuing. A
cold front will pass through the region into Friday, with cooler
temps and gusty winds. Drier conditions in store for the
weekend with seasonable temperatures.
Details: Focus in the long term remains the chance for a wintry
precip event mid-week. Much of the prior talking points
continue: chance of ice accretion greatest within the western ME
mountains and far northern NH Wednesday into Wednesday night,
showery and foggy elsewhere.
Changes this update: expand ice area slightly outside of the
mountains into the foothills and portions of the interior,
increase QPF somewhat with stratiform precip trending a bit
further south, blended more deterministic guidance in to capture
cold air dam better Wed/Wed night. Net result was an increase in
ice accum in regions of greater confidence.
Continued uncertainty remains in 1. overall QPF, and 2. sfc
temps in and outside of the mountains.
For QPF, precip onset will likely occur Wednesday afternoon,
with more substantial rates into the evening hours. Believe
current guidance showing precip Wed morning is just low stratus
or fog at this time, as dry air remains in the profile. Guidance
has trended further south with a portion of stratiform
precipitation crossing Wednesday evening and overnight. This
brings greater amounts into the Jackman, ME region and other
portions of western ME. Elsewhere, precip may be more showery as
forcing is lacking in expanding warm sector. Thus, kept amounts
lower here. Should this stick through additional runs, could see
continued uptick in QPF.
As for surface temperatures, greatest confidence in sub
freezing temps throughout Wed and Wed night is firmly across the
Boundary mountains and valleys of western ME and northern NH.
More uncertainty lie into the ME and NH foothills where cold
air may still be slow to wick away due to CAD as more widespread
precip overspreads the area Wed afternoon and evening. Overall
expect these areas outside of the mountains to slowly push near
or above freezing after midnight Wednesday night.
Incoming precip patterns may be dictated by possible upstream
convection, then high variability could result in QPF and as a
result ice accretion. NBM probs have been consistent here, but
more deterministic guidance is variable in placing more
continuous showers across the mountains. Currently have forecast
amounts up to three tenths of an inch for northern Somerset and
Franklin counties, but this may be more of a floor when
comparing to ECMWF forecasts. CAD traditionally will win in this
region until low level cold air is flushed, and low level winds
capable of doing so may not arrive until after midnight
Wednesday. This comes as anomalous high pressure is finally
budged east by the stacked low pressure in the western Great
Lakes.
Temperatures do rebound well across the region Thursday, and
plain rain should fall as a result across the area. The next
attention grabbing day would be Friday where a passing cold
front will bring very breezy conditions to the area. With the
windy conditions amid deep mixing, RH values will fall quite low
across southern NH. Will need to watch for fire weather concerns
where snow has melted and wind/low RH overlaps.
Dry conditions continue into the weekend with high pressure in
the region with seasonable temperatures.
&&
.AVIATION /04Z TUESDAY THROUGH SATURDAY/...
Short Term...VFR conditions lowering potentially to MVFR
overnight in scattered light precipitation and lowering ceiling.
Borderline MVFR conditions to continue on Tuesday before IFR
conditions develop Tuesday night per latest model solutions.
Long Term...IFR conditions likely Wed into Thurs as low ceilings
remain in rain and potentially FZRA near KHIE and the western ME
mountains. LLWS is also possible. Vis may also be restricted at
times in fog and precipitation. Conditions improve Thursday
night as a cold front moves through. VFR is expected Friday and
Saturday, but gusty W to NW winds are possible at most
terminals.
&&
.MARINE...
Short Term...South to southwesterly winds will remain gusty
overnight with seas building to 4 to 6 feet along the outer
waters. Will continue with the SCAs.
Long Term...Occasional SCA conditions Wed/Thursday. Of greater
limitation may be visibility in occasional fog. A cold front
will cross the waters Thursday night, with westerly winds
gusting up to 30 kt Friday.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...Small Craft Advisory until noon EDT Tuesday for ANZ150-152.
Small Craft Advisory until 6 AM EDT Tuesday for ANZ151-153-154.
&&
$$
NEAR TERM...Cannon/Schroeter
SHORT TERM...Cannon
LONG TERM...Cornwell
Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1033 PM CDT Mon Apr 3 2023
.UPDATE...
Issued at 920 PM CDT Mon Apr 3 2023
Latest surface analysis was showing a front across west central
Illinois into central Missouri with temperatures remaining in the
mid 60s to around 70 south of the front and 50s to the north of
it. Have made a few minor adjustments to lows based on current
observations. Showers and thunderstorms have yet to develop
across the area and latest RAP soundings are showing a strong CAP
over the area, so have lower chances for the rest of the night.
First peek at 00Z model guidance shows no significant change to
tomorrow, so did not make any updates. Forecast still looks on
track.
Britt
&&
.SHORT TERM... (Through Late Tuesday Night)
Issued at 245 PM CDT Mon Apr 3 2023
Key messages through Wednesday morning:
- A conditional threat for severe weather, some of which may be significantly
strong, exists Tuesday afternoon through Wednesday morning.
There will likely be at least two timeframes for the threat: one
during the afternoon and early evening on Tuesday in northeast
Missouri and west-central Illinois and another overnight Tuesday
into Wednesday morning. However, all of this is very
conditional on the strength of a capping inversion.
- It is worth noting separately that, IF any thunderstorms
develop during the afternoon on Tuesday, they will be scattered
and the potential exists for very large hail, strong tornadoes,
and damaging wind. Thunderstorms during the second round will be
a bit more widespread, but the significant potential would be
slightly lower.
- Outside of the severe thunderstorm threat, strong non-
convective wind gusts in excess of 45mph are forecast associated
with the larger-scale system. A Wind Advisory was issued for
parts of northeast/central Missouri from 7pm Tuesday until 7am
Wednesday.
Regional surface analysis drapes a warm front across northern
Missouri and west-central Illinois, just south of Quincy, IL. Behind
the front, dewpoints are on the rise and temperatures continue to
climb into the 70s. Aloft, an amplified trough continues to dig
across the western CONUS and draw deep south/southwest flow through
the Great Plains and Mid/Lower Mississippi Valley. This evening, as
a low-level jet intensifies over western Missouri, isolated to
scattered thunderstorms are possible along and north of the warm
front in northern Missouri and west-central Illinois. While 700-
500mb lapse rates look impressive in model soundings (~8C/km) north
of the CWA, instability (elevated or otherwise) is at a premium and
large-scale forcing is rather marginal. While we may see small hail
in any convection that can manage to develop in that area, anything
more impactful looks very unlikely.
Attention then shifts to the potential for severe weather Tuesday
afternoon into Wednesday morning across the region. During the
morning on Tuesday, the trough out west becomes broader and a
shortwave impulse ejects into the central/northern Great Plains
during the afternoon. A deepening surface low will shunt east and
then northeast through the day, continuing to draw moisture further
north into our region and raise temperatures into the 80s across
most of the area. The parameter space remains highly favorable for
discrete severe convection starting in the afternoon on Tuesday:
strong deep-layer shear perpendicular to an approaching dry line
amidst MLCAPE in excess of 2000J/kg in some locations and 8C/km+ 700-
500mb lapse rates. Modeled hodographs are also favorable for
sufficient streamwise vorticity available for a very real tornado
threat in any supercells that develop.
However, it is important to stress that the strength of a capping
inversion across most of the warm sector appears very formidable in
the deterministic guidance, the 12Z HREF, and CAM soundings. With
little/no low-level convergence available to help overcome the
inversion, and heights aloft appearing to remain unchanged with time
(or perhaps rise slightly and promote subsidence), overcoming this
CIN will be no small feat. As a result, the threat for severe
weather is highly conditional on the inversion being overcome. Where
free convection can be realized, there is a significant and
worrisome threat for a high-end severe weather: strong tornadoes,
very large hail, and damaging wind. As it currently stands, it
appears that any threat will occur in at least two waves. The
first will be Tuesday afternoon and early evening in northeast
Missouri and west-central Illinois, where we may see some modest
height falls that sufficiently erode the inversion to allow for
free convection. In this environment, any discrete convection will
contain threats of strong tornadoes, very large hail, and
damaging wind. CAMs continue to vary considerably regarding the
timing for these thunderstorms, and some have no threat developing
at all amidst a strong inversion.
A relative lull in the severe thunderstorm potential will exist
roughly after sunset when diurnal heating ends and the inversion
becomes more pronounced. The surface low will likely track through
Iowa and strengthen the pressure gradient and interact with non-
negligible low-level lapse to the point of causing sustained 20-
30mph winds, with gusts up to 45mph. A Wind Advisory will take
effect at 00Z Wednesday for this threat of non-convective winds. A
cold front will approach the region with the low ejecting further
north and east overnight Tuesday into Wednesday, posing the second
threat for severe weather. By this point, deep-layer shear is
oriented less favorably for discrete convection compared to the
earlier round. However, the angle compared to the forcing is such
that would still promote discrete convection initially ahead of the
front.
There is a bit more confidence that the inversion will be
weakened in the vicinity of the forcing that would allow for severe
thunderstorms, but questions of appreciable instability at that time
still exist. All severe hazards will exist with this round as well,
but are tied very closely to 1) how long the storms can remain
discrete and 2) how much instability they can access. The threat
will follow ahead of and along the front through into Wednesday
morning, ending when the front clears the CWA sometime during the
late morning. There is also a low potential for training convection
to cause minor flooding in streams and creeks across southeast
Missouri and southwest Illinois. Given the relatively progressive
nature of the forcing and individual thunderstorms, and their short
residence time in more favorable conditions for efficient rainfall,
I doubt flash flooding will be a concern.
MRB
.LONG TERM... (Wednesday through Next Monday)
Issued at 245 PM CDT Mon Apr 3 2023
Temperatures behind the cold front will likely be notably cooler
than Tuesday`s values (by roughly 30 degrees) with strong cold air
advection in place aloft. Depending on how cold it can get, relative
humidity north of I-70 would approach 30% amidst 20mph sustained
winds. Assuming the fuels are sufficiently dry (which would depend
on the coverage of the thunderstorms overnight), there might be a
few hours of elevated fire danger in the northern parts of the CWA.
However, I`m not confident enough in the exact RH/wind speed overlap
to necessarily message elevated fire danger at this point.
Wednesday night has potential to see temperatures dip below
freezing, and with vegetation becoming greener with each passing
warm day, a frost/freeze threat exists Wednesday night into Thursday
morning. Beyond then, longwave troughing engulfs most of the CONUS
and dry, seasonably cool conditions will persist through the end of
the week. A gradual warmup is likely with winds eventually returning
out of the south by the end of the work week, but there is quite a
bit of spread among the probabilistic guidance and the NBM as it
comes to high temperatures. Our next chance for precipitation beyond
Wednesday comes late Sunday evening into Monday when a upper-level
wave drops into the region from central Canada. Deterministic
guidance and ensemble cluster analysis display considerable
uncertainty in the strength and position of the wave.
MRB
&&
.AVIATION... (For the 06z TAFs through 06z Tuesday Night)
Issued at 1029 PM CDT Mon Apr 3 2023
Expect mainly dry conditions through the period. Main exception
will be this evening scattered thunderstorms will also be possible
on Tuesday afternoon at UIN/COU/JEF. There is too much
uncertainty in whether these storm will develop to include in the
terminals at this time. Did also put VCTS at STL after 06Z on
Tuesday night when there will likely be a line of showers and
thunderstorms approaching the terminal ahead of a cold front.
Ceilings will also drop to MVFR at UIN and the St. Louis area
terminals late tonight through mid morning on Tuesday before
improving to VFR by late morning. Otherwise, winds will be 12
knots or less through 13-16Z before increasing out of the south
with gusts into the 25-30 knot range by afternoon.
Britt
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...Wind Advisory from 7 PM Tuesday to 7 AM CDT Wednesday for
Audrain MO-Boone MO-Callaway MO-Cole MO-Knox MO-Lewis MO-
Marion MO-Moniteau MO-Monroe MO-Osage MO-Ralls MO-Shelby MO.
IL...None.
&&
$$
WFO LSX
Area Forecast Discussion
National Weather Service Pueblo CO
704 PM MDT Mon Apr 3 2023
.UPDATE...
Issued at 702 PM MDT Mon Apr 3 2023
Per GOES sat pix imgy, the dust has lifted off to the northeast
away from El Paso county. Likewise, will allow dust advisory for
parts of the region to expire. HODANISH
UPDATE Issued at 436 PM MDT Mon Apr 3 2023
An area of blowing dust is clearly visible on the blowing dust sat
pix imgy. This dust is pushing across the Sangre De Cristos in
eastern Fremont and into El Paso counties. Some of this dust will
push across NW Pueblo and SE Teller, but the areal coverage is
pretty small. HODANISH
&&
.SHORT TERM...(This evening through Tuesday)
Issued at 331 PM MDT Mon Apr 3 2023
Key Messages:
1) Damaging winds continue across the San Luis Valley, the San
Juans, and the Sangre de Cristos tonight.
2) Moderate to heavy, wind-driven snow expected across the San Juans
and the central mountains.
3) Another round of critical fire weather and damaging high winds
expected on our plains for tomorrow.
Currently..
A weak frontal boundary passed through early this morning, bringing
slightly higher dewpoints and southeasterly winds to portions of our
plains, which have stuck around a bit longer than expected in some
areas. Many of our mountain adjacent locations have mixed out, and
are seeing strong southwesterly winds as of 3pm. At this time,
Trinidad is already seeing 45 mph due westerly gusts. Expecting
westerlies and southwesterlies to spread across the plains over the
next hour or two, which could lead to some visibility restrictions
with blowing dust. Blowing dust has been ongoing across the San Luis
Valley, where 65 mph winds and blowing dust with visibilities down
below a mile are already being recorded on satellite imagery, area
webcams, and asos observations. Dust Storm Warnings and Advisories
are in place over portions of the valley until 7pm this evening.
Rest of Tonight..
As the trough axis approaches, our flow continues to become more and
more southwesterly. This pattern will bring moderate to heavy at
times snowfall to the Continental Divide. Winter Weather Advisories
are in place for the Sawatch Range and the San Juans, where wind
driven snow and accumulations up to around 8-12 inches are expected.
Blowing snow could lead to dangerous travel conditions and degraded
visibilities, especially through mountain passes. Heaviest snowfall
rates look to come in through the overnight and early morning hours
of tomorrow, though light to moderate snow continues throughout the
day. As the pressure gradient tightens overhead and the jet
approaches, damaging winds are expected to continue through the
overnight hours across the San Juans and the Sangres, where High
Wind Warnings are in place until tomorrow morning. Overnight lows
will likely stay warmer than normal on our plains, with many
locations only falling into the 40s.
Tomorrow..
The jet axis moves overhead by around 6am tomorrow morning, allowing
damaging winds and dry air to spread across our lower elevations. A
High Wind Warning has been issued for lower elevations of Huerfano,
Las Animas and Baca counties, where winds are expected to gust up to
60 mph. Another tier of counties has the potential to see damaging
winds tomorrow as well, mainly through Prowers, Bent, Otero, and
southern Pueblo counties, though certainty is low to medium for
these areas at this time. High res models continue to back a cold
front across our plains tomorrow afternoon and tomorrow evening,
which would effectively cut off the potential for high winds for
areas along and north of highway 50 depending on what time the front
makes its way through. Current HRRR solutions bring the front into
the highway 50 corridor by around 4-5pm tomorrow afternoon. If the
front looks to come through any slower than this, these counties
will likely need to be added to our wind highlights. Precip chances
spread into Teller County and Northern El Paso County tomorrow
afternoon as well, though accumulations look to be very light early
in the event.
Regardless of the front, critical fire weather conditions are
expected across our plains for tomorrow. With early mixing and
continued gusty southwesterly winds, relative humidity values look
to fall into the teens and single digits as early as 8am in some
locations. This will allow for several hours of critical fire
weather conditions across our plains before the front arrives. With
increasing cloud cover and the cold front pushing through northern
portions of the forecast area early in the afternoon, daytime highs
are likely going to be much cooler tomorrow, with many locations not
making it into the 60s on our plains.
.LONG TERM...(Tuesday night through Monday)
Issued at 331 PM MDT Mon Apr 3 2023
Key Messages:
1) Cooler with precipitation chances over and near the higher
terrain Tuesday night and Wednesday.
2) Warming and drying trend expected into the weekend.
Tuesday night-Wednesday night...A broad upper trough continues to
lift out across the Rockies Tuesday night, with its associated
frontal boundary pushing south and west across the southeast
Plains Tuesday evening. Models continue to indicate enough
moisture and lift along and behind the front to support scattered
rain and snow showers across southeast Colorado through the
evening, with the best snow accumulation potential of a couple of
inches across the Pikes Peak/Palmer Dvd region, as well as the Wet
Mts and southern Sangre de Cristo Mts into the southern I-25
Corridor, with breezy north to northeast winds behind the front.
Light snow accumulations can also be expected across the central
Mts Tuesday night, as developing northwest flow aloft helps to
wring out available moisture. Precipitation winds down late
Tuesday night into Wednesday morning, with another weak
disturbance within the northwest flow remains progged to translate
across northern Colorado. Increasing moisture and uvv associated
with this wave, combined with low level east to southeast low
level flow, will allow for another round of scattered showers to
develop Wednesday afternoon and evening, especially across the
central Mts and into the Pikes Peak region, where another inch or
2 of snow could be possible. Temperatures through this period to
remain below seasonal levels, with lows in the teens across the
lower elevations and in single digits above and below zero across
the highest terrain, and highs Wednesday mainly in the 40s across
the plains and in the 20s and 30s across the higher terrain.
Thursday-Friday...Moderating westerly flow aloft remains progged across
the region through the end of the work week, with temperatures warming
back to above normal temperatures into 60s and 70s by Friday. There may
still be enough breezes in the afternoon to support near critical fire
weather conditions across portions of the I-25 Corridor on Thursday,
and possibly across portions of the far southeast Plains on Friday, with
breezy southerly winds east of lee troughing across the I-25 Corridor.
Saturday-Monday...Upper level ridging remains progged to build across
the Great Basin and into the Rockies into early next week, leading
to a continued warming and drying trend, along with less wind and
lower threats of critical fire weather conditions.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 331 PM MDT Mon Apr 3 2023
For KCOS and KPUB..VFR conditions are expected at both terminals for
the next 24 hours. Southwesterly wind gusts up to 45kt continue to
be possible through max heating this afternoon. Gusts are expected
to weaken through the overnight hours, with southerly and
southeasterly winds taking over for a few hours after 06Z at both
terminals. Mid-level cloud decks are expected to move in late in the
period, with snow showers possible in the vicinity of KCOS tomorrow
morning, especially north and west of the terminal. Blowing dust
with MVFR visibility will also be possible at KPUB both afternoons,
but have left mention out of the TAF for now as confidence is low.
For KALS..IFR conditions in blowing dust are expected to continue
until around 01Z this evening, with periods of LIFR possible from
21Z to 00Z this evening as well. Conditions are expected to improve
to VFR quickly once the dust settles, which should happen between
around 2Z to 4Z tonight at the latest. Southwesterly winds remain
gusty overnight, with gusts up to 40kt remaining possible into
tomorrow morning. Snow showers are expected along the terrain
surrounding the terminal, but are not expected on station at this
time.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 9 PM MDT Tuesday for COZ060-068.
High Wind Warning until 9 AM MDT Tuesday for COZ068.
Red Flag Warning until 9 PM MDT this evening for COZ221-222-224-
226>237.
High Wind Warning until midnight MDT tonight for COZ069>071.
High Wind Warning until 9 AM MDT Tuesday for COZ072>075-078>080.
Red Flag Warning from 8 AM to 8 PM MDT Tuesday for COZ227>237.
High Wind Watch from Tuesday morning through Tuesday afternoon
for COZ086-093-097-098.
High Wind Warning until 6 PM MDT Tuesday for COZ087.
High Wind Warning from 9 AM to 6 PM MDT Tuesday for COZ088-094-
099.
&&
$$
UPDATE...HODANISH
SHORT TERM...EHR
LONG TERM...MW
AVIATION...EHR
going forward in the forecast discussion and how the event may
unfold for Tuesday evening into early Wednesday morning.
Before getting into the details of the most plausible scenario,
let`s set the stage with environmental background. The environment
will be conducive for strong to severe thunderstorms with MLCAPE
values around 1000-1500 J/kg, 0-6km shear of 60-70 knots, and
ample amounts of moisture. Furthermore, the atmosphere will
feature strong low level turning with 0-1km SRH values of greater
than 200 m2/s2. Forecast soundings and hodographs remain
favorable in the low- levels. This environment would be supportive
for discrete supercells in the warm sector and a line of
thunderstorms along the trailing cold front. The big remaining
uncertainties is when and if the cap breaks. This will take some
sort of impulse/energy to break the cap.
The first low confidence potential "round" for severe
thunderstorms to develop will be mid to late afternoon across
portions of south central and central Missouri. Confidence remains
low given the strong cap in place through the afternoon, but may
need further evaluation based on mesoanalysis in the near term.
That sets the stages for a mostly dry afternoon and early evening.
Recent RAP guidance and soundings would suggest some weakening of
the cap around after 00Z, with a potential complete break in the
cap approaching 06Z. This has been captured by some of the 12Z
suite of CAM guidance. However, it is worth noting there remains
uncertainty in the cap breaking given the lack of sufficient
cooling aloft and marginal height falls ahead of the line of
thunderstorms. The second potential round for severe
thunderstorms is with regards to discrete supercells developing
ahead of the dryline/cold front late Tuesday evening into the
overnight. Confidence is low to medium on this potential. As
previously mentioned, the cap will play a key role in this severe
round materializing. This area of concern for nocturnal
supercells is outlined by the SPC Day 2 Enhanced and Moderate
Severe Weather Outlooks, generally along and east of the Highway
65 corridor with the greatest focus across south central Missouri.
This would set the stage for all severe weather hazards including
large hail, damaging wind gusts, and strong tornadoes. This would
be problematic given the timing of this setup overnight Tuesday
into early Wednesday morning. It will be important to stay
updated with the forecast over the next 24 hours, as mesoscale
features are resolved. Lastly, the cap stands the best chance of
getting broken as forcing increases along a cold front overnight
Tuesday. Keep in mind, there is the potential for ongoing
supercells along and east of Highway 65 in the same timeframe that
a line of thunderstorms develops within the Interstate 49
corridor. Adequate instability remains in place through the
overnight in conjunction with strong low level wind shear,
including 0-3km shear of 40-50 knots. This line of thunderstorm
would pose the risk for damaging wind gusts and a few tornadoes.
To summarize, there are three timeframe and areas of focus for
severe potential on Tuesday into Wednesday morning. Confidence is
highest in the nocturnal threat at this time, but remaining
uncertainties still exist. There remains alternate scenarios, such
as little convection at all if the cap remains stout.
The secondary impactful weather element from this system will be
gusty south winds. NBM and HREF probabilities continue to support
wind gusts of 30 to 45 mph by Tuesday afternoon through Tuesday
night. Winds in excessive of 45 mph may occur in areas across
southeast Kansas into west central Missouri. Given the higher
confidence in winds up to 45 mph occurring, a Wind Advisory has
been issued for portions of southeast Kansas into west central and
central Missouri.
.LONG TERM...(Wednesday through Monday)
Issued at 310 PM CDT Mon Apr 3 2023
By Wednesday morning, the expectation is for showers and
thunderstorms to exit the area. Westerly wind gusts will slowly
subside behind the frontal passage as cooler and drier air filter
into the region. Expect zonal to northwest flow to setup over the
area Wednesday through Friday, with daily highs in the 50s to
around 60. Lows fall into the 30s. This will reintroduce the
potential for some frost by late week and will need to be assessed
in future forecasts. In general, confidence remains low on frost
potential given the dry air mass in place late week.
By the weekend, temperatures will be on the rebound into the
upper 60s to lower 70s. Most of the weekend should remain dry with
low precipitation chances by Sunday evening. No significant storm
systems are expected beyond the early week system.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 611 PM CDT Mon Apr 3 2023
For the 00z TAFS, winds should become less gusty for the evening,
but some gusts will be possible again overnight and especially on
Tuesday with the approach of the next system. Some wind gusts over
30 kts will be possible during the day. Low level wind shear will
also be possible tonight with 40 to 45 kts of shear in the lower
2000 feet. Some lower cloud cover will be possible on Tuesday, but
should remain in VFR.
&&
.SGF WATCHES/WARNINGS/ADVISORIES...
MO...Wind Advisory from 2 PM Tuesday to 1 AM CDT Wednesday for MOZ055-
066>068-077>080-088>091-094.
Wind Advisory from 7 PM Tuesday to 1 AM CDT Wednesday for
MOZ056>058-069>071-081.
KS...Wind Advisory from 2 PM Tuesday to 1 AM CDT Wednesday for KSZ073-
097-101.
&&
$$
SHORT TERM...Perez
LONG TERM...Perez
AVIATION...Lindenberg