Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/23/24
Area Forecast Discussion
National Weather Service Sioux Falls SD
1017 PM CDT Mon Apr 22 2024
.KEY MESSAGES...
- A few sprinkles to light showers will continue to move
through area east of I-29 this afternoon and evening.
Accumulation are expected to be kept to a minimal.
- A few more isolated sprinkles will be possible Tuesday
afternoon mostly along portions of southwestern MN.
- Rain chances return to the forecast late Thursday afternoon
and continue throughout the weekend, with a lull in activity
possible Friday night into Saturday. A few storms could become
strong to severe.
&&
.DISCUSSION...
Issued at 241 PM CDT Mon Apr 22 2024
Tonight: Another warm and breezy day continues! Taking a look
across the area, partly to mostly cloudy skies continue as a
combination of high cirrus and altostratus push across the area
ahead of a mid- level trough. Current radar imagery shows a few
sprinkles to light showers developing within the altostratus.
However, dry air in the sub-cloud layer has prevented most of
the developing precipitation from reaching the surface. As warm
air advection (WAA) continues to strengthen east of I-29 along
with the LLJ, coverage of developing showers will likely
increase especially across the Buffalo Ridge leading to the
potential for some light accumulations. Nonetheless, most of
this activity should be out of our area by this evening giving
way to clearer skies.
Shifting gears here, our breezy southerly to southwesterly winds
have begun to shift to the northwest behind the cold front and
should continue to gradually decrease this evening. With only a few
sites (mainly KSLB & KSPW) across northwestern IA continuing to have
advisory level sustained winds and gusts, have decided to trim our
original advisory to reflect the sites with the strongest winds. The
wind advisory will continue through 4 PM CDT. Looking at soundings,
deep mixing will continue to bring drier air down to the surface
this afternoon behind the surface front. As a result, ended up
mixing in some RAP guidance into the forecast this afternoon to help
lower our dew points closer to observed values. While this has
resulted in critical RH values (15-25 percent) across most of the
area, greener fuels and moist top soil will keep our fire weather
concerns at marginal at best for a while. Lastly, temperatures will
continue to be above normal as highs approach the upper 60s to low
70s this afternoon with overnight lows only decreasing into the low
to mid 40s.
Tuesday: Looking into Tuesday, cloud cover will begin to build
mostly north of I-90 as another mid-level wave swings across the
area during the morning hours. Increased PVA ahead of the
trough along with an increasing LLJ may lead to a few sprinkles
to isolated showers developing mostly across portion of
southwestern MN. Similar to this afternoon, limited saturation
in the subcloud layer will likely lead to limited accumulations.
However, the dreary condition will likely persist into the
early afternoon hours before gradual clearing occurs from west
to east. Shifting gears to the winds, northwesterly winds will
again increase throughout the day with gusts between 25- 35 mph
possible. Otherwise, lingering cold air advection (CAA) aloft
and northwesterly surface winds will keep temperature more mild
than the previous day with highs only expected to peak in the
upper 50s to low 60s for the day. As conditions clear by the
late evening, the colder air aloft will be allowed to reach the
surface dropping our temperatures back into the low to mid 30s
for the night. While these temperatures could warrant a
frost/freeze headline Tuesday night, three back-to-back days of
freezing temperatures this week likely took out any developing
vegetation. As a result, the headline might not be necessary.
WEDNESDAY: Quiet conditions are expected to prevail as sfc high
builds across the area. Despite the increase in cloud cover during
the afternoon, will see highs rise into the low to mid 60s with the
aid of southerly flow. Gusts then look to gradually increase during
the evening and overnight period, especially along and east of I-29,
with values ranging between 25 to 35 MPH.
THURSDAY: Upper level low over the southwestern CONUS ejects
northeastward Thursday, causing showers and storms to return to the
forecast by Thursday evening. Should see largely dry conditions
persist through the afternoon as upper level ridging holds tight
overhead. Similar to Wednesday night, expect breezy southerly winds
to continue, with gusts between 25 to 35 MPH possible for much of
the day. As a result, expect highs to rise into the upper 60s to
lower 70s. Sfc warm front surges toward the region Thursday evening,
allowing WAA showers to blossom across our area. While some
development may be possible along the MO River Valley near sunset,
think the better chances (>60%) will arrive after midnight.
FRIDAY THROUGH SUNDAY: Widespread showers and storms are expected
heading into the Friday as the aforementioned upper level low nudges
closer to the region. As alluded to in the previous discussion, may
even see a few storms become strong to severe Friday evening if all
the ingredients come together. While the better dynamics currently
look to occur across the central Plains, SPC`s latest D5 Outlook
does maintain a 15% risk of severe weather across portions of NW
Iowa and NE Nebraska. Certainly something to keep an eye on in the
coming days. In regard to temperatures, currently have highs in the
upper 60s to lower 70s, though these values may be a touch too high
if FROPA across quicker than anticipated. Otherwise, look for
showers and storms to continue heading into the weekend. Depending
on how the upper level low tracks, may see a lull in activity late
Friday night through Saturday morning, with wrap around showers
still likely by Saturday afternoon. Model consistency begins to wane
by Sunday as yet another wave near the Rockies ejects toward the
region. Given that the track of this feature could still shift quite
a bit over the next few days, will not speculate on the details just
yet. For now, expect rain chances to continue heading into the new
week with highs generally in the 50s to 60s and lows in the 40s.
&&
.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1017 PM CDT Mon Apr 22 2024
VFR throughout the period. Areas south of I-90 may see some variable
winds for a couple hours overnight, though retaining a westerly
component. Breezy northwest winds ramp up after sunrise, sustained
in the 20 to 25 knot range, with gusts 25 to 35 knots. Winds slowly
decrease during the afternoon hours. Areas east of I-29 may see some
sprinkles Tuesday afternoon, but have left mention out of the TAFs
for KFSD and KSUX terminals as any showers will be light and
scattered if they are able to develop.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
IA...None.
NE...None.
&&
$$
DISCUSSION...SST/Gumbs
AVIATION...APT
Area Forecast Discussion
National Weather Service Hastings NE
836 PM CDT Mon Apr 22 2024
...Short Term Update...
.KEY MESSAGES...
- Can`t rule out a few isolated/scattered showers and
thunderstorms this evening into tonight across mainly the
southern half of the forecast area. Not anticipating any
severe weather, but some storms could be strong with small
hail and gusty winds.
- Near-critical fire weather conditions (potentially spots of
brief critical conditions) are expected across much of the
forecast area Tuesday afternoon, with relative humidity values
falling into the low-mid 20s and wind gusts around 30 MPH.
- A more active weather pattern looks to develop Thursday and
continue on through the weekend. Severe weather is possible
Thursday evening/night, then potentially again Friday/Friday
evening depending on the timing of upper level and surface
features.
&&
.UPDATE...
Issued at 833 PM CDT Mon Apr 22 2024
-- Comments solely focused on overnight thunderstorm potential
(still looks like a few could be on the stronger side):
- Potential still exists for isolated to scattered, elevated
(very high-based) storms overnight almost anywhere in our
coverage area/CWA (except perhaps least likely far northern
counties), with the last few HRRR runs starting to hone in on
the the most favored zone might reside roughly 30 miles
either side of the I-80 corridor (including the Tri Cities).
- The most favored time frame for storms is 10 PM-4 AM
(instability really fades away/shifts east of our CWA beyond
then).
- This is a classic case of modest elevated instability
(primarily based up around 700 millibars or 10K ft. above the
surface) being released as parcels are forced upward by
strengthening southwesterly flow into an elevated frontal zone
(and mainly a few counties north of the well-defined surface
front currently settling southward through our far south-
southeast zones.
- Based on a look at instability/shear progs from latest RAP13
(both plan-view and forecast soundings), and as supported by
HRRR modeled radar reflectivity, there is certainly a chance
that a few storms could be on the stronger side (perhaps even
TRY to become marginally-severe?). Most unstable CAPE (MUCAPE)
values are progged to peak as high as 400-800 J/kg, in the
presence of strong effective deep-layer wind shear at least
40-50KT. Even with this limited instability, could easily
envision a few storms producing hail to at least penny/nickel
size, with a lower (but non-zero) threat of gusty winds at
least 40-50 MPH making it to the surface.
- IF progged elevated instability/CAPE were only a few hundred
J/kg higher (and for sure if 500 J/kg higher), this setup
almost certainly been a would a candidate for an official SPC
Marginal Risk (level 1 of 5) mainly for marginally-severe
hail. As we see it here from the local level, we support the
official overnight outlook remaining as "general thunder", but
we could easily foresee a few stronger cores warranting
Special Weather Statements (SPS), and the latest 21Z SREF
"calibrated severe thunderstorm" parameter suggests a non-zero
chance that a few storms could even try breaching severe
levels (again mainly from a quarter to ping pong ball size
hail perspective).
&&
.DISCUSSION...
Issued at 441 PM CDT Mon Apr 22 2024
Currently through tonight...
Upper air and satellite data showing generally zonal flow in
place across the region this afternoon, as we sit on the
southern side of low pressure spinning over the ND/Canada
border. Elsewhere across the CONUS, broad ridging remains near
the West Coast...another low pressure system is making its way
off the coast of VA/SC. The main impact from the system to our
north up to this point has been the accompanying surface cold
front pushing south...which at 3PM is roughly along a Silver
Creek to Beaver City line. Ahead of the front, southwesterly
winds gusting anywhere from 35-45 MPH have been common, even a
few gusts were closer to 50 MPH. Behind the front, winds switch
to the north-northwest, with gusts closer to 25-30 MPH. Overall
temperatures have worked out pretty well, a quicker passage of
the front would have made for a wider gradient across the
area...as it sits at 3 PM, north-northwest areas are right
around 70 degrees, with right around 80 in the south-southeast.
This evening into tonight, this cold front will continue to
gradually sink south into north central Kansas...and models
still showing the potential for a few isolated/scattered
showers and storms to develop along it. While there are some
minor differences with the exact time things develop and the
overall coverage, models are in pretty good agreement keeping
things focused south of Highway 6 and into north central Kansas.
Models continue to show meager instability through this
evening, but deep layer shear is strong...so while severe
weather is not anticipated, can`t totally rule out some strong
storms with small hail/gusty winds. A few models hint at some
showers try to reach further north later this evening and on, so
kept some low end precipitation chances in the forecast. Any
activity that develops is expected to taper off/move out by
sunrise Tuesday. The surface front loses its initial upper level
push and stalls out across far southern portions of our
forecast area late this evening...with winds area-wide
diminishing...before getting another push and reinforcing those
northerly winds as we get into that 09-12Z time frame. Skies are
expected to be partly-mostly cloudy, and even with winds
diminishing/remaining northerly, overnight lows are forecast to
be in the low-mid 40s.
Tuesday and Wednesday...
Dry conditions are expected as we get into the daytime hours on
Tuesday, with upper level flow a bit more northwesterly as the
system currently to our north digs south into the Midwest and
that broad ridging slides east into the Rockies. Breezy
northerly winds are expected area-wide, with gusts 25-35 MPH
expected, then diminishing late in the afternoon as surface high
pressure sinks south into the region. Expecting partly cloudy
skies...with cooler highs ranging from the mid 60s in the north
to low-mid 70s in the south. Tuesday continues to have the
potential for widespread near- critical (potentially a few brief
spots of critical?) conditions...though cooler, dewpoints look
to be in the 20s, resulting in relative humidities dropping into
the low-mid 20 percent range. Didn`t issue any fire wx
headline, but any change up in temp or down in dewpoint may
result in needing one.
Precipitation chances return to the forecast late Tuesday night
and continue on into Wednesday...but overall confidence
remains on the lower side, so chances are still in the 20-30
percent range. Models showing a fairly subtle mid-level
disturbance sliding through the region and forecast chances are
broad in nature, but better chances look to be focused across
the the SSW half of the area and more so totally south. Little
instability is expected to be in place, so thunder continues to
be left out at this point. At the surface, high pressure sliding
east and low pressure organizing over the Rockies bring a
switch in winds back to the south for Wednesday...and breezy
conditions are expected, especially across the western half of
the area. Forecast highs are in the mid-upper 60s, but if there
does end up being more widespread light precipitation through
the day, wouldn`t be surprised to see that trend down a bit.
Thursday and on...
By Wednesday evening, models are in pretty good agreement
showing an upper level low pressure system moving onto the
central/southern CA coast...with this system being our main
weather driver in the Thursday-Friday time frame. Late Wednesday
night-Thursday morning, though the main low is well west,
precipitation chances start increasing as a lead shortwave
disturbance moves in from the southwest and warm air/moisture
advection picks up. Forecast preciptiation chances increasing
into the 50-70 percent range during the daytime hours, but the
better chances look to be during the evening/overnight hours,
when the main upper level emerges out onto the Plains...aided by
a 45-50ish kt low-level jet. Though not in the more
typical/ideal afternoon/early evening time for severe
weather...this evening/overnight activity continues to have the
potential to be strong/severe, with models showing MUCAPE values
exceeding 1500 j/kg and deeper layer shear around 35-40 kts.
The better instability looks to be focused across the southern
half of the forecast area...which is included in the SPC Day 4
15 percent area (slight risk). Outside of the storm chances,
Thursday is expected to have gusty south-southeasterly winds,
with gusts of 30- 40 MPH not out of the question. Confidence in
highs isn`t high...current forecast is in the mid 60s-near 70
for most locations.
How Friday ends up panning out is still a little
uncertain...driven by questions with how Thursday/Thursday
night evolves and the overall timing of the upper low itself.
Looking at deterministic models...at 12Z Friday the main upper
low could be over the Sandhills of Nebraska or be further
southwest over northeastern CO. A slower/more southern track
would keep better preciptiation chances around the forecast area
longer...but would also be slower to clear the main surface
features out, keeping severe weather as potentially more of an
issue...mainly for areas east of Highway 14. The quicker/more
northern track dries us out and pushes the threat further east
by mid-late afternoon. No matter the timing, gusty southwesterly
winds ahead of the front will give way to gusty west- northwest
winds as the front passes through. Highs are forecast in the
70s for most locations...but like Thursday`s highs, confidence
in on the lower side.
Forward to the upcoming weekend, late Friday night into the
daytime hours on Saturday still looking to bring a brief break
in the action between the departing Thu/Fri system and another
system expected to move in Sat night. Models show this next
upper level closed low pressure system coming out of the Rockies
and onto the Plains a little further south than the Thu/Fri
system...but still brings another chance for widespread
precipitation to the area late Saturday night into the day on
Sunday. Being several days out yet, hard to have a high degree
of confidence.
&&
.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 657 PM CDT Mon Apr 22 2024
- General overview for KGRI/KEAR:
This is a high confidence VFR forecast with regard to
ceiling/visibility, with the ONLY possible exception being
briefly-reduced visibility at some point overnight if a heavier
shower/thunderstorm would happen to pass through (low
probability). Otherwise, winds are the main concern, especially
Tuesday late morning-afternoon when moderately-windy
northerlies will be at their strongest.
- Ceiling/visibility/precipitation details:
Especially the first 12-15 hours will feature plenty of mid-high
level clouds, but with ceiling largely at-or-above 8K ft. There
will be a roughly 6-hour "window of opportunity" for a passing
shower/thunderstorm or two tonight, and this has been handled
with a generic "vicinity thunderstorm" (VCTS) group 02-08Z.
Thunderstorms are not expected to be all that strong, but
suppose small hail/gusty winds cannot be completely ruled out
(along with a very outside chance of brief sub-VFR visibility).
- Wind details:
The majority of the entire period will feature a northerly to
north-northwesterly wind direction, except for a period of
northeasterlies this evening-overnight. Assuming that overnight
winds are not influenced/enhanced by any nearby convection,
sustained speeds should average near-to-below 10KT through the
first 12+ hours. However, winds will pick up during the latter
half Tuesday daytime, overall-strongest 15-22Z during which time
sustained speeds 15-20KT/gusts 24-28KT will be common before
starting to trend down slightly late Tues afternoon.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...None.
KS...None.
&&
$$
UPDATE...Pfannkuch
DISCUSSION...ADP
AVIATION...Pfannkuch
Area Forecast Discussion
National Weather Service Goodland KS
735 PM MDT Mon Apr 22 2024
.KEY MESSAGES...
- Isolated showers and thunderstorms possible through this
evening.
- Near critical fire weather conditions are possible Thursday
west of a line from Flagler to Cheyenne Wells.
- Chance for severe weather Thursday generally east of Highway
25.
&&
.UPDATE...
Issued at 731 PM MDT Mon Apr 22 2024
Little changes regarding the forecast. Widely scattered
thundershowers have developed across eastern portions of the
area including some lightning strikes near Hill City. This
activity looks to move out of the area in the next 30-60 mins
with virtually no impact expected. A brief period of gusty winds
may be possible as DCAPE remains around 1500 j/kg. As for
precipitation chances tomorrow night, have trended them down
about 5-10% due to overall concerns regarding coverage and
placement of the 700mb wave per 21Z RAP as there is some concern
it may be to far north. We will have weak upslope flow however
which may be able to overcome this. Again, severe weather is not
expected tonight or tomorrow night due to minimal amounts of
CAPE present.
&&
.SHORT TERM /THROUGH THURSDAY NIGHT/...
Issued at 130 PM MDT Mon Apr 22 2024
Convergence along a cold front combined with weak wave aloft may
be enough to initiate a few showers or isolated thunderstorms
this afternoon and evening. However, instability is meager and
decreases rapidly by around 01z, so no severe storms expected
and only a few hundredths of precipitation in the limited areas
that see anything. Any lingering showers should end by midnight.
Low temperatures will be in the upper 30s and lower 40s.
On Tuesday, subtle ridging through the afternoon should keep it
dry, while upslope winds at the surface keep it a bit cooler,
with high sin the 60s to lower 70s. Weak disturbance cuts
through the ridge axis Tuesday night with scattered showers.
12-hour mean precipitation amounts by 12z Wednesday are less
than a tenth of an inch. Lows Tuesday night will again be in the
upper 30s to lower 40s.
Wednesday, a few showers may linger into the morning then
clearing. Flow is basically zonal over the top of a ridge
centered over the southern plains. Similar to Tuesday night,
another weak wave moves across the area Wednesday night as the
flow becomes more southwest. There are a few hundred joules of
MUCAPE to work with, so cannot rule out an isolated
thunderstorm. Highs will be in the upper 60s to lower 70s and
lows in the 40s.
Thursday still on track to be the potentially busy day as a
negatively tilted shortwave trough lifts out of the southwest.
Still differences in track/timing, which would potentially
impact how this will play out. GFS has the trough cutting off
Thursday afternoon/evening in northeast Colorado, with trailing
front and dry line into the area which would be favored area for
convective initiation. West of the dry line it will be breezy
with possible fire weather concerns, though latest runs suggest
driest conditions may stay just west of the area. On the other
hand, the ECMWF solution is slower by about 12 hours, with the
upper low cutting off in a similar location Friday morning. This
would result in a lower risk of severe storms on Thursday
afternoon since the dry line is largely absent, although shear
will still be adequate for severe storms for the storms that do
develop. ECMWF main severe threat would be on Friday, and east
of the area, with the local area mainly seeing wraparound
precipitation. High temperatures will be in the 70s and 80s and
lows Thursday night in the 40s.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
Issued at 114 PM MDT Mon Apr 22 2024
As the system from Thursday leaves the area, Friday will see
lingering showers and low-end storms, as well as breezy west-
northwesterly winds. Pressure changes with this system have become
fairly weak with this run of guidance. The big change is the second
low pressure system is looking to arrive earlier than previously
thought. Gusts on Friday seem to max out around 30 kts. The
lingering showers and storms will retreat to the north during the
evening and overnight hours.
Another low pressure system is forecast to move into the area
Saturday evening. There are two guidance suggested tracks that this
system will take. The first track is over our southeastern CWA. This
would give majority of the Tri-State area a decent chance as some
stratiform rain, with a few thunderstorms embedded within. The
precipitation would be primarily be from wrap-around moisture, and
gives us a chance (~5-10%) of seeing some snow mix in. The other
track is across the northwestern CWA. This would give us a favorable
setup for severe weather Saturday evening and overnight. The SPC
currently has a 15% outlook for severe weather southeast of the CWA
on Saturday. This looks to be mostly based on the first track, which
has shown up more often in previous model runs.
Pressure rises behind the front on Sunday are strengthening from 24
hours ago, but are not overly impressive. Gusty northwesterly winds
around 30 kts are currently forecast for Sunday.
Winds that will generally favor the north will cause temperatures to
struggle. Temperatures Friday will be in the upper 60s to low 80s
and, depending on the low pressure system and associated cold front,
Saturday`s temperatures look to range from the mid 60s to low 80s.
Sunday, the Tri-State area will all be around 70 and begin warming
up again Monday, up to the upper 70s. Overnight temperatures look to
cool into the upper 30s to upper 40s.
&&
.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 432 PM MDT Mon Apr 22 2024
VFR conditions remain forecasted for this TAF period. Watching
some virga and/or showers across the Palmer Divide move towards
the KS/CO state line. CAMS have been in relatively decent
agreement in them persisting across the area as dew points are
higher. Current highest confidence in any potential shower
activity looks to be for the KGLD terminal than the KMCK
terminal so will introduce a vcsh in the TAF. Winds will remain
easterly before briefly becoming northerly during the early
morning hours. A period of breezy winds gusting around 20 knots
at each terminal looks likely as well from sunrise through the
early afternoon.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...None.
CO...None.
NE...None.
&&
$$
UPDATE...Trigg
SHORT TERM...KAK
LONG TERM...CA
AVIATION...Trigg
Area Forecast Discussion
National Weather Service Marquette MI
824 PM EDT Mon Apr 22 2024
.KEY MESSAGES...
- Elevated fire weather conditions this afternoon give way to a quick
round of showers and perhaps a few rumbles of thunder this
evening.
- Rain quickly moves out the second half of the night with
clearing skies.
- Another round of precipitation comes Tuesday with rain
changing to snow with a few rumbles of thunder possible
(20-30%) in the south and east. Generally, less than an inch
of wet snow is expected in the north.
- Dry weather in the midweek under high pressure. Elevated fire
weather concerns are expected for Wednesday and Thursday.
- Active weather pattern returns this weekend and continues into
next week.
&&
.SHORT TERM /THROUGH TONIGHT/...
Issued at 226 PM EDT Mon Apr 22 2024
Upper ridging over the central US is beginning to slide eastward
with a compact shortwave moving into the Northern Plains. At the
surface, an associated surface low is moving into Manitoba, leaving
the Great Lakes under a tight pressure gradient as a surface high
remains sprawled out over the eastern CONUS.
SW winds continue to gust up to 20-30mph across much of the UP, and
though high clouds continue to stream across the area, lower to
midlevels remain dry and well-mixed (per early afternoon NUCAPS
soundings). This is sending dewpoints into the teens and lower 20s
across much of the western half of the UP, while to hte east, these
are coming in a couple degrees higher in the lower to mid 20s. With
temperatures already in the lower 60s across most of the area,
widespread RH values near (or even below!) 20% are observed in the
western half of the UP. This is all to say that elevated fire
weather conditions continue to be the rule this afternoon. Don`t
burn! As we head into the late afternoon, dewpoints should slowly
climb as more lower level moisture works in ahead of our next
approaching rain-maker.
A shortwave currently rippling through IA and MN this afternoon
moves into the UP this evening, eventually phasing with the Manitoba
low later tonight. This will bring a narrow swath of rainfall to the
area tonight, with most of the area expected to see some rainfall
for a 1-2hr window. As a dry slot works in behind it, skies quickly
clear from west to east the second half of the night. Most guidance
brings showers into the western UP between 00-02Z, then rain moves
out of the eastern UP between 06-08Z. Given such dry antecedent
conditions, this may be a bit ambitious for an onset timing. Thus,
unsurprisingly, rainfall amounts are lighter across the western half
of the UP compared to areas more eastward that will have more time
to moisten up. Still, totals remain fairly light, generally at or
below a tenth of an inch. Will note that the HRRR favors some
stronger embedded convection, indicated by simulated reflectivity up
to 40dbz. That, too, is a little suspect; this solution remains the
outlier, and soundings show little to no elevated instability. Thus,
have allowed thunder to fall off with this forecast update, but
wouldn`t be totally surprised to hear of a rumble or two overnight
with the HREF showing some CAPE sneaking in overnight (but mainly
following our shortwave).
Otherwise, though winds fall back into the early evening, they
should pick up again with the passing wave before decreasing again
behind it. Temperatures stay mild overnight, generally falling into
the lower 40s with a few spots in the upper 30s throughout the
western UP.
&&
.LONG TERM /TUESDAY THROUGH MONDAY/...
Issued at 342 PM EDT Mon Apr 22 2024
The extended period begins with a quick reprieve from precipitation
giving way to showers and a few thunderstorms in the south and
eastern U.P., with the rain showers transitioning to snow showers
over the northern U.P.. After the cold front causing the
precipitation moves through Tuesday evening, expect dry conditions
to dominate Upper Michigan until Friday; we could see more elevated
fire weather conditions Wednesday into Thursday as a high pressure
sets up over Lake Superior and sunny skies will allow for greater
mixing. As we head into the weekend, a more active weather pattern
returns to the area, with rain chances returning Friday and
continuing into next week.
We start out initially dry Tuesday morning before the backside of
the Clipper low brings a cold front over the area by the late
morning hours. As this occurs, expect showers to move across the
area. Ahead of the cold front in the southern and eastern U.P., we
could see some fairly decent MUCAPEs, with some spots possibly
seeing up to 1500 J/kg aloft. However, unlike today, only around 25-
ish knots or less of 0-6 km bulk shear is expected. Therefore, while
there is a 20-30% chance of seeing thunderstorms over the south and
east Tuesday afternoon, no severe weather is expected. As showers
continue over the northern U.P., expect the rain to transition to
snow as strong cold air advection works its way south across Lake
Superior into Upper Michigan. With some upslope enhancement over the
north facing snow belts from Ironwood to Munising, expect a wet
dusting to possibly up to an inch in some spots. In addition, the
higher terrain near Mt. Arvon could see an additional inch of wet
snowfall as the upslope flow could squeeze out a little more
moisture from the atmosphere. While it is possible that we could see
visibilities down to 1/2 mile at times in the Michigamme Highlands,
with the ground temperatures being so warm recently and temperatures
only dropping down to around freezing during the daylight hours
Tuesday, the snow should be relegated to elevated surfaces and grass
(minimal travel impacts are expected). One more note: while short-
lived if it does occur, there is a small chance (10 to 20%) that we
could see a transition over to sleet/freezing rain for a short time
before the changeover to snowfall Tuesday afternoon. Should this
occur, expect ice accumulations to be just a glaze at the absolute
most, and only on elevated surfaces. The precipitation ends across
the area Tuesday evening as the cold front leaves our area and skies
clear out.
Dry weather is predicted from Tuesday night to Friday morning as a
high pressure ridge sets up over Lake Superior in the wake of the
Clipper`s cold front. With the anomalously cold air overhead Tuesday
night and with skies clearing out, I`m thinking the lows are going
to bottom out down further in the interior areas than what most
model guidance has. Therefore, I went with the NBM10th percentile,
taking the low temperatures into the teens across the interior west
and east; that being said, there is a chance (30%) that I didn`t go
low enough. While Wednesday and Thursday nights will have mostly
clear skies too, the temperatures shouldn`t be as cool as warm air
advection works its way through the region by the middle of this
week. That being said, with the dry conditions overhead, the U.P.
will struggle to make a full RH recovery each night, with the RHs
only recovering to around 60% Wednesday night! Meanwhile, the high
pressure over Lake Superior will keep sunny skies and dry conditions
over us Wednesday and Thursday. Dewpoints Wednesday look
exceptionally low, as the NAM model suite goes well below the
NBM10th percentile in some spots (i.e. the interior far east). While
I put in the NBM10th for Wednesday and Thursday, I could see the
dewpoints being quite a bit lower than what I put in for both days,
especially Wednesday where the difference was most noticeable.
Currently, I have min RHs down to around 20% Wednesday, but with the
high pressure directly over the lake then, RHs could (50% chance) be
even lower than that! Our saving grace, though, is that temperatures
are still looking to be pretty cool Wednesday, with highs expected
to only be in the upper 30s to mid 40s near the Great Lakes and mid
40s to low 50s in the interior areas, and winds are going to be very
light (Less than 10 mph for the most part). On Thursday, I have min
RHs getting down into the low 20 percents, with the lowest RHs in
the interior west. In addition, temperatures will be warmer as highs
get into the 50s across the area with some spots in the interior
west getting into the low 60s. However, RHs Thursday may not be as
low as Wednesday, as some warm, moist air from the Gulf of Mexico
begins to work its way towards the area by then. In addition, winds
are expected to remain fairly light as the high pressure leaves the
region, although they will begin picking up from the south to around
10 to maybe 15 mph at 20 ft by the afternoon hours. Overall, while
the weather will be fairly nice, especially Thursday, elevated fire
weather conditions look to be a concern for the middle of this week.
The fire weather concerns end Friday as our next low pressure system
impacts our area. As the low lifts from the Southern Plains through
the Northern Plains, we are expected to catch one of its fronts
during the day Friday. This will bring additional rain showers and
possibly (20 to 30% chance) thunderstorms back across our area
Friday. As the low itself moves through Lake Superior Saturday,
additional rain showers look to impact our area. Following this, a
second low pressure system lifts from the Southern Plains into the
Upper Midwest through the U.P. to finish out the weekend and early
next week. While it looks like we will get a reprieve after this,
next week looks to continue the active weather pattern as we could
possibly get set up with yet another low pressure system.
&&
.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 823 PM EDT Mon Apr 22 2024
VFR will be predominant through tomorrow morning with the exception
of sporatic MVFR in any heavier rain showers tonight. MVFR will
prevail though by Tue 12-14Z and possibly as low as IFR at IWD and
CMX as a disturbance moves through the area. Meanwhile,
southwesterly winds will continue to gust up to 25 kts, becoming
northwesterly in the wake of the aforementioned disturbance tomorrow
morning, but still gusting.
&&
.MARINE...
Issued at 342 PM EDT Mon Apr 22 2024
Light winds of generally 20 knots or less this afternoon give way to
some southerly gusts of 20 to 25 knots this evening over the eastern
half of Lake Superior as a warm front traverses east through the
lake. Winds for a few hours die down to 20 knots or less by mid
Tuesday morning. However, by late Tuesday morning the system`s cold
front drops down from the north, bringing with it north-
northeasterly gales up to 35 to possibly (40% chance) 40 knots
across the central and eastern lake Tuesday; some moderate freezing
spray could (60% chance) could be seen over the eastern lake Tuesday
night. As the cold air advection behind the low ceases by Tuesday
evening, expect the winds to die down, eventually becoming 20 knots
or less again by Wednesday morning as a high pressure sets up over
the lake. This high pressure keeps the winds light across the lake
for the middle of this week. Stronger winds don`t look to show up
again until Thursday night, when an approaching front brings
southerly winds of 20 to 25 knots back across the lake. As it`s
parent low approaches from the Southern Plains Friday, expect the
winds over the eastern half of the lake to increase to 20 to 30
knots from the southeast, with a few gale force gusts up to 35 knots
being possible by Friday evening. As the low moves into Lake
Superior Saturday, expect winds to turn northerly to 25 to 30 knots
behind the low`s center from west to east across the lake. Strong
winds look to continue over Lake Superior into early next week.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
Small Craft Advisory from 8 AM EDT /7 AM CDT/ Tuesday to 8 AM
EDT /7 AM CDT/ Wednesday for LSZ240>242.
Gale Warning from 8 AM to 2 PM EDT Tuesday for LSZ243>245-
263>266.
Small Craft Advisory from 10 AM Tuesday to 6 AM EDT Wednesday
for LSZ246-247.
Small Craft Advisory from 10 AM Tuesday to 1 PM EDT Wednesday
for LSZ248>251.
Gale Warning from 2 PM Tuesday to 2 AM EDT Wednesday for
LSZ267.
Lake Michigan...
Small Craft Advisory from 1 PM Tuesday to 11 AM EDT Wednesday
for LMZ221.
Small Craft Advisory until 8 AM EDT Wednesday for LMZ248-250.
&&
$$
SHORT TERM...LC
LONG TERM...TAP
AVIATION...TDUD
MARINE...TAP