Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/28/24
Area Forecast Discussion
National Weather Service La Crosse WI
647 PM CDT Sat Apr 27 2024
.KEY MESSAGES...
- Isolated severe storm chances in the 4-9 pm window today south
of Highway 18 in swrn WI and Clayton/Fayette counties in IA.
Large hail and damaging wind are the main threats.
- Heavy rain axis has shifted south of the area. A more
widespread rain of 0.75-1.25" is expected through Monday, with
most falling Sunday and Sunday evening. Storms will be around
but the risk of those being severe is quite low after this
evening.
- An active week is ahead with periodic rain and storm chances,
with severe storm probabilities looking low at this time, but
stay tuned. Later Tuesday is the next opportunity.
&&
.DISCUSSION...
Issued at 206 PM CDT Sat Apr 27 2024
Severe Thunderstorm Potential This Afternoon/Evening:
At 1 PM, surface observations show southwesterly winds persisting
area wide. The hi-res models are in very good agreement for winds to
slowly begin turning to the west throughout the afternoon for much
of the area except far southwest Wisconsin and parts of eastern Iowa.
This will create a weak convergence zone along an axis from the Strawberry
Point, Iowa area towards Lone Rock, Wisconsin. With a lack of synoptic-
scale forcing due to weak shortwave ridging aloft, this will be the
primary forcing mechanism for ascent. South of the aforementioned
convergence axis, a reservoir of 700-1200 J/kg of mixed layer CAPE
is progged to continue to increase with daytime heating. HRRR model
soundings support the CAPE axis growing to 1500- 1800 J/kg in the
southern parts of Clayton and Grant Counties by late afternoon. In
previous forecasts and model soundings, this instability was capped
by an elevated mixed layer 2-3 km off the surface, but recent HRRR
soundings at Dubuque have reduced the strength of the warm nose aloft
leading to less capping. Day Cloud Phase satellite imagery shows
hints of this as well, with bubbly cumulus cloud tops along and south
of Highway 151, and some glaciation and orphan anvils further south.
The lack of a stable layer aloft could lead to airmass thunderstorms
developing as daytime heating continues to fuel the environment.
Thunderstorms that form before the weak convergence zone sets up
would be rather pulsy in nature and may decrease the potential of an
organized severe weather threat this afternoon/evening.
If the cap does develop this far north this afternoon and inhibit convection
until convergence is present, isolated to scattered severe storms are
possible in southern Clayton and Grant Counties. The seasonably strong
CAPE mentioned above combined with 35-40 knots of deep-layer shear supports
supercells capable of producing large hail and damaging wind. A tornado
or two cannot be ruled out with around 20 knots of 0-1 km shear present
and a very brief window of helicity greater than 150 m^2/s^2 in model
soundings, but generally speaking hodographs are straighter in nature
for much of the event making large hail the primary threat.
With the lack of strong forcing this evening, thunderstorms will succumb
to a stabilizing atmosphere after sunset this evening. The forecast for
tonight is much drier than previous forecasts with all of the stronger
forcing remaining south of the forecast area until early tomorrow morning.
Rain and Storms for Sunday into early Monday
As the current four-corners deep low ejects out of the southwest
and tracks northeast across the region, lift increases Sunday
on a brush-by of QVector convergence /strongest northwest/ and
the Highway 20 warm front trying to shift north as the surface
low tracks through Minnesota. Low-level moisture advection shifts
north during the morning hours and continues to supply the area
abundant moisture /precipitable water values at the 95th percentile
to near record by late day/. One change is the moist air stream is
bifurcated, keeping the very juicy air in the northeastward stream
from IL->MI /precipitable water 1.50"+/. While the surge in moisture
occurs, the model consensus surface warm front remains near the
WI/IL border and west into IA as the low occludes, limiting CAPES
to 500J/Kg, reducing severe storm potential. This triple point
will evolve northward overnight Sunday ahead of the cold front,
with some surface-based instability /500 J/Kg/ dragging northeastward
into WI per the latest RAP forecasts. Wind shear is still pretty
impressive for this time frame with long,straight hodographs. Right
now, this RAP migration of the triple point and surface instability
is more of an outlier compared to the HREF CAMS. It is something
to monitor Sunday night. The current SPC marginal severe storm risk
appears appropriate with such reduced instability. So, waves of
showers and storms continue until Monday where cold and dry air
advection stabilize the atmosphere from southwest to northeast post-
low. Rainfall amounts look to be in the 0.75-1.25" range from Sunday
to Monday, with the 27.12Z HREF having about 20-35% chances for 1"+.
Active Weather Next Week, Monitoring for Severe Storm Potential
Tuesday: Increasing mid-level winds ahead of a deeper longwave trough
evolving over the northcentral/northwest CONUS Tuesday will lead to
the monitoring for our next chance of severe storms. An open Gulf of
Mexico flow will provide a moisture tongue into IA/MN ahead of a north-
south oriented cold front Tuesday afternoon. By evening, the 27.00Z
Grand Ensemble mean places the cold front near I-35 with 70-80% probabilities
of 40 kt 0-6km bulk wind shear. Forecast soundings from the 27.12Z GFS/NAM
for 7 pm Tuesday show some moderate capping in place and the area being
on the northern extent of the instability tongue. The ensemble probability
of SBCAPE over 500 J/KG is only 15-20% just west of the Miss river. So,
the kinematics are in place for severe storms, but instability looks to
be a limiting factor at this time. The 27.00Z CSU severe probabilities
from machine learning indicate as axis centered on I-35 from DSM-DLH of
5-15% late Tuesday. So, will continue to keep an eye on this potential.
Mid-Late Week: Swift zonal flow continues across the CONUS with various
solutions and large spread on the shortwave troughs moving through with
a frontal zone and instability in the region. Forecast confidence is quite
low on any details beyond Wednesday but big picture says periodic rain/storm
chances and breezy at times into the weekend with near normal temperatures.
&&
.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 647 PM CDT Sat Apr 27 2024
Main taf concerns through the taf period are IFR conditions and
thunder potential at both taf sites through the taf period.
Another surface low is expected to lift northward over the area
late tonight into Sunday. Ceilings are expected to lower into
MVFR late tonight...around or after 06z Sunday. Then lower to
IFR after 10z Sunday at both taf sites. Along with the lowering
ceilings...showers will overspread the region. Instability is
limited over the taf sites during the daytime hours Sunday.
Storms should be isolated across the region. For now...will not
mention any thunder in the tafs due to the coverage of the
storms. Within the heavier showers visibility could be reduced
to IFR at both taf sites after 15z Sunday.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&
$$
DISCUSSION...KAA/Baumgardt
AVIATION...DTJ
Area Forecast Discussion...UPDATED
National Weather Service Quad Cities IA IL
1005 PM CDT Sat Apr 27 2024
.KEY MESSAGES...
- Active period continues into the overnight and also into
Sunday.
- Flash flooding remains a concern overnight into Sunday morning
for areas that will have received repeated rounds of storms
south of I-80, and this is where a Flood Watch continues.
- Scattered severe weather remains possible, mainly well south
of I-80 overnight, but also into Sunday although prior
convection may have an impact on the magnitude/timing/location
of severe weather Sunday PM.
- Unsettled weather continues through next week, with periodic rain
chances.
&&
.UPDATE...
Issued at 1002 PM CDT Sat Apr 27 2024
The primary expectations for the forecast largely continue on
track as we head into the overnight hours. An isolated severe
risk continues, and a potential for a developing flash flood
threat in mainly the Flood Watch area will be something we have
to monitor closely with regenerating thunderstorms.
A mesoscale convective vortex (MCV) near the Iowa/Wisconsin/
Illinois border region will continue to shift northeast through
midnight, dragging a somewhat decaying line of thunderstorms
eastward in the zone along/north of I-80. An associated cold
pool from the storms` longevity should help continue to push
this too east of the CWA. Further south and southwest of our
area too, a low-level jet of 45-50 kt as observed on upstream
profilers in western Missouri will support isentropic lift
along/north of the outflow-modified boundary. This will likely
result in storms in central/northern Missouri to continue to
thrive with even new development possible to the west of these,
all of which will likely clip or advance over the southern CWA.
It may depend on cold pool magnitude that develops with this
convection in Missouri, as there already is an ongoing meso-high
in southeast Iowa "shoving" things along. If that is sufficient
enough of a push, it may take the brunt of the severe threat
mainly south or just clip the southern tier. Severe winds are
the main threat, but cannot rule out a brief tornado threat
given still high values of low-level CAPE, especially ahead of
the outflow boundary.
Of greater concern is the training storms in the southern CWA
in a high moisture transport environment. Looping the radar in
Missouri shows some attempts at backbuilding, and RAP forecast
Corfidi vector do become 5-10 kt across the far south between
05Z-09Z. Similarly, if the cold pool development is sufficient,
it may propagate the heaviest rainfall rates along too and just
south/southeast of the CWA, but confidence in that occurring is
low at this time and the threat still very much includes our
south. Given the wet conditions in this area from Friday (1-1.5
inches) and already this evening (additional 0.5-0.75 inches),
this area is primed for a flash flood risk if 1+ inch per hour
rates set up for 2-3 hours.
&&
.SHORT TERM /THROUGH MONDAY/...
Issued at 140 PM CDT Sat Apr 27 2024
Late morning surface analysis shows a surface low centered
across eastern Minnesota and western Wisconsin, with a cold
front draped to its south across east central Iowa and northwest
Missouri. Off to our southwest, another surface low with a
warm front and dry line was centered over the Oklahoma
panhandle, with storms ongoing along this and ahead of a
shortwave in the same location. This shortwave will progress
northeast over the next few hours, and will be the driver of our
weather over the next couple of hours.
The overall forecast remains on track for the area, with shower and
storm coverage expected to increase over the next few hours. The
first round should be focused along the stalled cold front draped
across east central Iowa as we destabilize and reach our
convective temperature in the upper 70s. Latest CAMs focus the
threat mainly along and northwest of the HWY 151 corridor. Ample
0-6km shear and steep mid-level lapse rates pushing CAPEs
around 1000-2000 J/kg may lead to storms capable of large hail
initially.
The second round of storms will come this evening as the
aforementioned shortwave rides the front and drives additional
lift across the area. A renewed LLJ will also ensure ample lift
and increased vertical shear. There remains some uncertainty as
to where storms will initiate and track, which is likely tied to
early PM convection and how much it stabilizes that warm sector
air in eastern Iowa. Regardless, HREF ensembles continue to
paint areas mainly south of Interstate 80 with high POPs. Severe
storms will also be possible with mainly a large hail and
damaging wind threat with near straight hodographs and cold pool
dynamics in play. While low, can`t rule out a tornado threat in
the QLCS and with any remnant boundaries from early PM storms.
Look for this threat to wane by midnight, with concerns turning
more towards a heavy rain/flash flood risk.
Speaking of which, we will need to keep a close eye on flash
flooding potential with these storms. LLJ will advect in a rather
robust PWAT feed across the region with values approaching 1.75" by
midnight. Where storms do train, latest CAMs show QPF by Sunday
morning approaching 2-4 inches. This looks to be favored mainly
in southeast Iowa, west central Illinois and northeast Missouri,
where a Flood Watch is now in effect through Sunday morning.
Heading into Sunday, scattered showers and storms will persist
through the morning and early afternoon, with a renewed round of
more widespread linear showers and storms expected by the
evening ahead of another robust shortwave ejecting out of the
Rockies. There is potential for this activity to become severe,
with the Storm Predication Center advertising a Level 1 to 2
risk for the area. The primary threats with storms will be
damaging winds and large hail, with a secondary tornado threat
if low-level shear can materialize.
&&
.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
Issued at 140 PM CDT Sat Apr 27 2024
Post cold front passage, we will be in for a dry start to the
week with high pressure moving across the central Plains and
mid-Mississippi River Valley. By mid to late week, a renewed
round of showers and storms is expected for the area as a trough
in the Rockies ejects several shortwaves across the Plains and
Midwest.
&&
.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 613 PM CDT Sat Apr 27 2024
A stormy period will be in place this evening, with
thunderstorms widespread before 06Z in eastern Iowa and
northwest Illinois. Winds will potentially exceed 40 kts along
and south of Interstate 80 through 04z.
Otherwise, thunder may become more sporadic overnight, with
rain and mvfr cigs continuing. Sunday, a gradual improvement to
higher MVFR to low VFR is expected, with another round of storms
moving in during the afternoon from west to east.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...Flood Watch through Sunday morning for IAZ087>089-098-099.
IL...Flood Watch through Sunday morning for ILZ025-026-034-035.
MO...Flood Watch through Sunday morning for MOZ009-010.
&&
$$
UPDATE...Ervin
SHORT TERM...Friedlein
LONG TERM...Speck
AVIATION...Ervin
Area Forecast Discussion
National Weather Service Kansas City/Pleasant Hill MO
606 PM CDT Sat Apr 27 2024
.KEY MESSAGES...
- Another round of severe storms possible this afternoon and evening.
All severe hazards are possible during the day with a trend
to flooding/ flash flooding overnight.
- Strong to potentially severe storms linger into Sunday.
- Unsettled pattern continues Tuesday through the end of next
week. Best potential for additional severe storms is Tuesday
afternoon and evening.
&&
.DISCUSSION...
Issued at 243 AM CDT Sat Apr 27 2024
Today - Tonight: Satellite and radar imagery early this morning show
what is likely an outflow boundary draped from northeastern MO
southwestward over the KC area and then into eastern KS. It`s
possible this could be the cold front but there isn`t much of a
temperature/dew point difference across it. Regardless, models
have not initiated this boundary well and are too far north with
it. The boundary will stall close to where it is as of ~08Z.
The RAP 305K surface shows this reasonably well. There will be
enough forcing along this boundary that showers and storms
should increase in coverage across northern MO through the
morning hours. During the morning hours, when potential
instability is weakest, the threat of severe weather looks to be
low. Going into the afternoon and evening hours, as a very warm
and humid airmass builds south of the boundary, CAPE values
will increase substantially. Models vary on this as well but
HREF probabilities show a greater than 90% chance for 2000+ J/kg
of SBCAPE. There`s even a 20% chance for SBCAPE to be greater
than 3000 J/kg over eastern KS and western MO. Additionally, as
upper-level flow increases, deep-layer shear will increase so
we`ll be staring down the barrel of a potentially 3000+ J/kg
airmass with 40-50 kts of shear. If a storm can get going in the
open warm sector, it will very likely become severe with all
hazards possible. This still seems unlikely this far east and is
much more likely further west, closer to the dryline. The
region will also be in a favorable location of an
anticyclonically curved upper jet with strong diffluence noted
over the forecast area on streamline plots. In the lower-levels,
a strong low-level jet will increase in the evening with
intense moisture transport nosing right into eastern KS and
western MO. This all points to an increase in coverage/
intensity of convection this evening with rounds of very heavy
rainfall and flooding/ flash flooding likely into the overnight
hours.
Sunday - Sunday Night: Saturday night`s convection will bleed into
Sunday as the low-level jet shifts eastward through the day and the
diffluent upper flow persists. With convection ongoing at the start
of this period, and then continuing through the day, we`ll struggle
to rebuild the instability. CAPE values look to be at least half of
what we saw Saturday and likely even less, potentially less than
1000 J/kg. While deep-layer shear will remain impressive, the weaker
instability will limit the potential for severe weather.
Monday - Monday Night: This period looks to be dry as the main
trough that brought multiple rounds of severe weather to the region
exits to the east and a drier airmass moves into the area.
Mid to Late Next Week: Low-level flow returns to a southerly
trajectory Monday night into Tuesday. That will advect moisture back
into the area just in time for the next front to interact with
it Tuesday. The warmer and more humid airmass will lead to
moderate instability with potentially 2000+ J/kg of MLCAPE
Tuesday afternoon. With 30-40 kts of deep-layer shear, can`t
rule out additional chances for strong to severe storms.
Unsettled weather will likely continue through the end of the
week as the area remains in a humid airmass with multiple
shortwave troughs moving through the flow. This will be resolved
better (and this forecaster will have more time to look at it)
in the coming days.
&&
.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 604 PM CDT Sat Apr 27 2024
Scattered thunderstorms becoming more widespread across the
metro through 04Z. Convection is expected to shift focus farther
to the southeast this evening. Potential for strong wind gusts
and large hail in the thunderstorms. MVFR stratus develops
behind the convection, and lingers through at least mid-day
Sunday with breezy south winds continuing.
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
MO...Flood Watch through Sunday afternoon for MOZ001>008-011>017-
020>025-028>033-037>040-043>046-053-054.
Wind Advisory until 7 PM CDT this evening for MOZ011-012-020.
KS...Flood Watch through Sunday afternoon for KSZ025-057-060-
102>105.
Wind Advisory until 7 PM CDT this evening for KSZ025-102.
&&
$$
DISCUSSION...CDB
AVIATION...Collier
Area Forecast Discussion
National Weather Service Jackson MS
958 PM CDT Sat Apr 27 2024
...New MESOSCALE UPDATE...
.MESOSCALE UPDATE...
Issued at 957 PM CDT Sat Apr 27 2024
Rest of tonight...
GOES East water vapor imagery & RAP analysis indicate stout upper
cold core trough digging over the Four Corners, which is leading
to widespread ascent, convection & severe weather across the Great
Plains. Our region remains in the drier pattern, with center of
mean ridging in the Carolinas & sfc subtropical high centered in
the western Atlantic. 00Z sounding indicate PWs less than 1.3
inches this evening. The Gulf coast states remain in southerly
return flow, but there is some indications that some dry
thermodynamic profiles could advect in off the Gulf, keeping a
quiet night in store. No rain is expected but some stratus is
possible to build across the southern half of the area. 4-5mb
gradient currently analyzed in LAPS analysis this evening.
Sustained winds around 10mph will persist, with some higher gusts
at times. Seasonably warm lows, some 5-10 deg F above normal, in
the low-mid 60s are expected. Updates are out. /DC/
&&
.DISCUSSION...
Issued at 309 PM CDT Sat Apr 27 2024
Through Sunday:
In the near-term, dry air with analyzed PWATs generally below 1.3
inches this afternoon is the limiting factor for much in the way of
shower or thunderstorm potential. Surface-based CAPE values over
2000 J/kg and decent low-level and mid-level lapse rates would
otherwise support convection. A stray shower or storm cannot be
ruled out this evening, but gusty gradient winds up to 30-35 mph
will be the main concern this evening. Continued moisture advection
and a better-timed shortwave trough passing through the ArkLaTex
region tomorrow afternoon could support a few showers or
thunderstorms during the daytime. Most of the activity should stay
to our west through the daytime however, as the wave interacts with
a dryline feature and generates organized severe weather threat for
East Texas into western Louisiana. Gusty southerly winds will
continue across the area, so will keep the Limited wind graphic in
effect through the day tomorrow.
Sunday night through Saturday:
The severe thunderstorm activity to our west on Sunday will have the
chance to make a run into at least northeast Louisiana and southeast
Arkansas tomorrow night. Hi-res guidance runs show a mature squall
line developing from the afternoon activity, and potentially bowing
out as it reaches the western portions of our forecast area late
Sunday evening into early Monday morning. A Slight Risk area for
potential damaging wind gusts and a possible tornado have therefore
been added for the Sunday night time frame. This line should
continue eastward into the day, possibly stalling out or losing
momentum before it fully clears our forecast area. A Marginal risk
for severe thunderstorms will continue into the day Monday, and the
potential for heavy rain with this system will also necessitate a
Limited Flash Flooding risk as well. Hazardous Weather Outlook
graphics have been updated and issued accordingly.
A fairly progressive split flow regime sets up over the CONUS
through the rest of next week, driving a few potential periods of
showers and thunderstorms as shortwave troughs moving east and
interact with spring-like humid and unstable air masses across the
South. When not raining, afternoon high temperatures should push
the upper 80s/lower 90s range. /NF/
&&
.AVIATION...
(00Z TAFS)
Issued at 702 PM CDT Sat Apr 27 2024
Gusty southeasterly sfc winds will continue through early
evening, mainly winding down by 28/02-04Z. In the wake, increased
flow in the low-levels will support onset of low-level wind shear
(LLWS) around 30-40kts at most TAF sites, mainly after 28/04-09Z.
This will remain psbl through around daybreak. MVFR stratus
should develop at central & southern TAF sites (i.e. HKS, JAN,
PIB, HBG & HEZ), with onset between 28/09-13Z & earlier onset at
southern TAF sites. Daytime mixing will lead to VFR flight cats
by midday & gusty southeasterly sfc winds, up to 20mph sustained
& gusts up to 30mph, psbl through the end of the TAF period. /DC/
&&
.PRELIMINARY POINT TEMPS/POPS...
Jackson 65 83 67 78 / 0 20 10 80
Meridian 64 84 63 82 / 0 20 10 60
Vicksburg 66 86 68 76 / 0 20 20 90
Hattiesburg 65 83 67 81 / 0 20 10 60
Natchez 66 85 68 77 / 0 20 20 90
Greenville 66 84 67 74 / 0 20 40 100
Greenwood 65 84 67 75 / 0 20 20 90
&&
.JAN WATCHES/WARNINGS/ADVISORIES...
MS...None.
LA...None.
AR...None.
&&
$$
DC/NF/DC
Area Forecast Discussion
National Weather Service Marquette MI
808 PM EDT Sat Apr 27 2024
.KEY MESSAGES...
- Scattered showers and isolated thunderstorms this afternoon.
- Breezy this afternoon into early this evening with 35-40 mph
gusts expected, strongest gusts this afternoon south central
and early this evening over Keweenaw and eastern shoreline.
- Active pattern continues as 3-4 low pressure systems track
across the region over the next week. Above normal
temps/precip are expected including thunderstorm chances.
&&
.SHORT TERM /THROUGH TONIGHT/...
Issued at 329 PM EDT Sat Apr 27 2024
Water vapor imagery and RAP analysis show a vort max/shortwave near
Thunder Bay, ON tracking ne. At the sfc, weakening low pres
associated with the shortwave wave is analyzed over and just e of
the Keweenaw. Ahead of these features, clusters of sct shra are
occurring into the Upper Great Lakes this afternoon. Maybe a rumble
of thunder could be possible in areas of partial clearing central UP
but fcst soundings suggest mid-level warming/drying will be a big
inhibitor, especially by 21Z this afternoon when any t-storm threat
will probably be gone. Current temps across Upper MI generally range
from the upper 40s in low clouds and cool onshore southerly flow
near Lake Mi southeast to lower to mid 70s into southern Dickinson
and Menominee counties in warm southwest flow and some cloud breaks
there. Most locations range from the mid 50s to mid 60s. Mixing
through 4-6 kft has also allowed for southwest winds to gust around
35 mph into south central areas. As the sfc low continues to track
ne across northern Lake Superior through early evening, moist
wraparound upslope flow on the backside of the low will continue to
support scattered showers into western counties early evening.
Elsewhere, any lingering isolated showers should die out near
sunset.
A 5-7 mb 3-hr pres rise max tracking across northwest Upper
Mi and south central Lake Superior and favorably aligned along the
gradient wind could provide an isallobaric boost to westerly winds
and gusts late afternoon into early evening across these areas,
particularly across the Keweenaw Peninsula where brief gusts near 35-
40 mph could be possible. Brief west gale gusts to 35 knots may also
be possible into south central areas of the lake late
afternoon/early evening.
Winds veering to the north-northeast on the backside of the low
later tonight will maintain mostly cloudy skies across the area but
increasingly anticyclonic low-level flow through the night should
result in dry conditions. Min temps tonight will range from the mid
30s west and north central to the lower 40s south central and east.
&&
.LONG TERM /SUNDAY THROUGH SATURDAY/...
Issued at 456 PM EDT Sat Apr 27 2024
The extended forecast period will be active with fairly good
agreement in the model guidance through Wednesday. Even though the
guidance begins to diverge into the latter part of next week, the
consensus on a wet and active pattern holds true.
Sunday will start off dry with a high pressure over northern Ontario
and the negatively tilted trough over NE and KS. During the day, the
trough lifts northeast toward the Upper Midwest and the associated
sfc low tracks from KS to IA. Weak WAA and isentropic ascent ahead
of the low will try to increase showers from the south, however the
drier northeast flow looks to slow this down and limit showers to
the south central in the afternoon. Showers overspread the UP Sunday
night as the trough moves into MN and the sfc low lifts north-
northeast bringing better forcing and a ~45kt LLJ over the UP. There
could be some rumbles of thunder in the south central Sunday night.
Some breezy east winds are expected to mix down from the LLJ with
gusts up to 35 mph, especially in the eastern UP and Keweenaw Sunday
night through Monday morning. The trough then pivots northeast over
the UP on Monday reinvigorating the showers and possibly providing
enough forcing for some weaker thunderstorms. That being said,
strong storms are not expected as instability is limited with spotty
MUCAPE around 200j/kg, the inversion in model soundings is fairly
strong, and mid level lapse rates are mostly below 6C/km. PWATs
highlight a surge of ample moisture off the Gulf of Mexico, bringing
up to 1" to the UP Monday morning, which is noted above the NAEFS
90th percentile for Sunday night into Monday. This should bring a
good soaking to the UP with 0.5" to 1.5" of rain by Monday night and
help alleviate fire weather concerns for the next few days.
Showers lift north out of the UP Monday night as the trough and sfc
low lift over Lake Superior, temporarily bringing dry weather back
to the UP for Tuesday and diminishing winds. WAA during the day
accompanied by clearing skies will bring above normal highs in the
50s near Lake Superior and in the far east with 60s elsewhere. The
dry weather is quickly replaced Tuesday evening as a shortwave races
across the Plains, passing over the Upper Great Lakes Tuesday night
into Wednesday morning. The sfc low associated with this shortwave
looks to pass northeast through MN into northern Ontario bringing a
round of showers Tuesday night into Wednesday. Instability again is
fairly low, so only a few rumbles of thunder are expected at this
time.
Dry weather looks to follow for Wednesday with some breezy west
winds behind the low pressure system`s cold front. Current NBM
probabilities of wind gusts exceeding 40 mph is around 15-30%, so
expected gusts are around 25-35mph. Uncertainty begins to grow in
the forecast for the rest of the week, but chances for precip
increase toward the end of the week as we track out the next low
pressure system or two to move through the Great Lakes.
&&
.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 808 PM EDT Sat Apr 27 2024
Poor flying conditions to continue in west-northwest flow as
moisture wraps around departing low pressure system. IWD will
consistently remain at IFR/LIFR levels in the upsloping. Meanwhile,
LIFR at CMX will gradually improve to IFR early tonight and
eventually MVFR by early Sunday morning. SAW, on the other hand,
will be on a downward trend from VFR this evening to MVFR and then
IFR/LIFR early tonight. In addition, west-northwest winds will gust
up to 24 kts through this evening at CMX and SAW.
&&
.MARINE...
Issued at 456 PM EDT Sat Apr 27 2024
A few west gale force gusts to 35 kt are possible for a brief period
late this afternoon into the evening across eastern Lake Superior as
the low pressure moves northeast into northern Ontario. Winds back
northeasterly late tonight into Sunday as the next system approaches
from the southwest. Northeast gales up to 40 kt are expected across
the far western lake Sunday afternoon with northeast becoming
easterly gales to 40 kts spreading across the entire lake Sunday
night. While a few gusts may exceed 40 kts Sunday night into Monday,
highest probabilities are on the low end (25-45%). The strongest
winds are expected in the far east as well as the north central
portion of the lake between the Keweenaw and Isle Royale where there
could be some channeling. Gales quickly diminish Monday afternoon as
the low pressure tracks across western Lake Superior Monday night.
The Gale Watch has been upgraded to a Gale Warning, now starting at
18z Sunday in the far west (3z Monday elsewhere) and ending at 21z
Monday.
During the gale event, waves will be highest from Duluth Harbor to
the Bayfield Peninsula, with significant wave heights up to 14 ft
possible Monday morning. Wave heights Monday morning around Isle
Royale will also be higher, up to 13 ft. Waves across the lake fall
below 8 ft Monday evening. There also is a slight chance for
thunderstorms on Monday.
Winds fall below 20 kts Monday night, mainly remaining below until
Wednesday morning.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
Gale Warning from 2 PM EDT /1 PM CDT/ Sunday to 5 PM EDT /4 PM
CDT/ Monday for LSZ162.
Small Craft Advisory from 3 PM EDT /2 PM CDT/ Sunday to 8 AM
EDT /7 AM CDT/ Monday for LSZ241.
Small Craft Advisory from 3 AM Sunday to 8 AM EDT Monday for
LSZ242.
Small Craft Advisory from 1 AM to 11 PM EDT Sunday for LSZ243.
Gale Warning from 11 PM Sunday to 5 PM EDT Monday for
LSZ243>246-263>266.
Small Craft Advisory until 11 PM EDT Sunday for LSZ244-245.
Small Craft Advisory until 11 PM EDT this evening for LSZ248.
Small Craft Advisory until 8 AM EDT Monday for LSZ249>251.
Lake Michigan...
Small Craft Advisory until 5 AM EDT Sunday for LMZ248-250.
&&
$$
SHORT TERM...Voss
LONG TERM...Jablonski
AVIATION...TDUD
MARINE...Jablonski