Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 07/11/24
Area Forecast Discussion
National Weather Service Bismarck ND
942 PM CDT Wed Jul 10 2024
.KEY MESSAGES...
- Smoky skies are expected to continue through the night before
clearing out on Thursday.
- Hot and humid conditions are expected Thursday through
Sunday, with highs mostly in the upper 80s to upper 90s.
- Low to medium chances (20 to 40%) for showers and
thunderstorms are in the forecast each night starting
Thursday night and continuing through the weekend.
&&
.UPDATE...
Issued at 940 PM CDT Wed Jul 10 2024
The main change made with this update was bumping up sky
coverage for the smoke that has been filtering in from the
north. While not at the surface, it did add a bit of a haze to
the sky, and will linger around until the morning hours on
Thursday. Apart from that, just blended in the current
observations to the forecast.
.UPDATE...
Issued at 622 PM CDT Wed Jul 10 2024
Minimal changes were made to the forecast for this update. Broad
surface high pressure continues to sit across much of North
Dakota, keeping skies generally clear and winds relatively
light. Just slightly tweaked cloud coverage to account for
diurnal cumulus in the west. Otherwise, the forecast remains on
track.
&&
.DISCUSSION...
Issued at 325 PM CDT Wed Jul 10 2024
This afternoon, the synoptic pattern was characterized by troughing
over the Great Lakes Region, while a stationary heat dome was placed
across the Desert Southwest. North of this, a shallow ridge was
moving over the Northern Rockies, with sharp northerly flow in place
across the Dakotas. Broad high pressure was centered over the
region, with relatively light surface winds. Although cloud cover is
very limited, GOES GeoColor satellite imagery shows continued
smoke aloft across central and eastern North Dakota, so we do
have slightly increased cloud cover in these areas to account
for not quite full sunshine. Expect a hazy sunset tonight with
quiet weather through the night, and forecast lows in the 60s.
Flow aloft turns a bit more northwesterly on Thursday downstream of
the shallow ridge, with a stout low-level thermal ridge beginning to
build into the region. Forecast highs range from the upper 80s from
the Turtle Mountains to the James River Valley, to the mid and
perhaps upper 90s in the southwest. Southerly low-level flow will
also advect in a higher moisture air mass, with dew points in the
lower 60s across the north and central. Chances for precipitation
(20-40%) return late Thursday afternoon to the northwest, expanding
into much of central North Dakota overnight, as an upper level
shortwave moves through. Shear and instability both look marginal,
so for right now expecting showers and non-severe thunderstorms
through Thursday night, although we wouldn`t be surprised if a
storm or two ended up on the stronger side.
With flow aloft turning more zonal, HRRR and RAP forecast smoke
models agree on the bulk of smoke aloft moving out of the area by
later on Thursday. There is some uncertainty on the expanse of near-
surface smoke, with model guidance showing low but still-
present concentrations through the day Thursday due to the low-
level return flow. For now will keep out of the gridded forecast
but can`t rule out slightly reduced visibilities, especially in
our far eastern counties.
A similar pattern is expected through the weekend, with hot, humid
conditions across the area and 20-40% chances for showers and
thunderstorms in the evening and overnight hours. The highest
chances are mainly across northern and eastern parts of the
state. Machine learning probabilities are low but persistent
every day, with deterministic guidance already advertising
moderate to high instability, although bulk shear is generally
on the marginal side. Highs through Sunday will mainly be in the
upper 80s to upper 90s across the area, with a low (around 20%)
chance of highs exceeding 100 degrees F in southwest North
Dakota, focused in the Bowman and Hettinger areas. Forecast heat
indices are staying below advisory criteria, although are
beginning to get close in LaMoure and Dickey Counties on
Saturday.
There is relatively high confidence in temperatures cooling down
some next work week, but the question is how cool. The placement of
the ridge axis across the Northern Rockies, as well as the location
of the downstream trough, will determine how warm temperatures stay.
Cluster analysis reveals ensemble members are split about 60/40,
with the slight favoring towards the trough axis extending back to
the Minnesota/Wisconsin area which would bring lower heights and
cooler temperatures to North Dakota. 40 percent of ensemble
members have the trough further away, higher heights, and
subsequent warmer temperatures across the area.
If the cooler solution verifies, some locations could see highs
return to the upper 70s by the middle of the work week. Overall, the
general expectation is for highs to remain mainly in the 80s through
the work week, so much more seasonable compared to the upcoming
weekend. Blended precipitation chances stay generally in the 15
to 30 percent range through midweek.
&&
.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 622 PM CDT Wed Jul 10 2024
VFR conditions are present across all terminals and will prevail
through the TAF period. Smoky skies continue across the area,
but confidence remains too low in this smoke reaching the
surface overnight. Generally light southerly winds will prevail,
potentially becoming a bit gusty at KDIK and KMOT overnight and
into tomorrow morning, with gusts up to around 20 kts.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...Besson
DISCUSSION...Jones
AVIATION...Besson
Area Forecast Discussion
National Weather Service Dodge City KS
1101 PM CDT Wed Jul 10 2024
.KEY MESSAGES...
- Quiet tonight with only at 15% chance of storms across central
Kansas
- Mid to upper 90s Thursday and Friday
- Still looking like a hot weekend
&&
.DISCUSSION...
Issued at 200 PM CDT Wed Jul 10 2024
The weather for 95% of the FA should be quiet tonight. There is a
very small concern of some very isolated storms developing across
central Kansas tonight. Confidence on this happening is very low.
The 3 km NAM depicts this possibility, however, grand ensemble (GE)
probabilities of >0.01" are only 10 to 30%. Would not be surprised
if nothing happens at all. The HRRR is pretty quiet for tonight.
Regardless, much of the FA should see quiet weather for the rest
of the afternoon and evening. Lows tonight will be mainly in the
60s. The heat will be on Thursday and Friday. Expect highs in the
mid to upper 90s. This matches well with GE probabilities of 90 to
100% of >90F temps both days.
The bottom line is that a 500 hPa anticyclone will move from the
Desert Southwest over to the Great Basin during this period. This
mid level high will continue to move east and should be located over
the spine of the Rockies through the weekend. This high pressure
center is strong at 597 to 599 dm. This supports hot highs continue
through much of the period. Low 100s cannot be ruled out, particularly
on Sunday as the mid level ridge prevails closer to the state.
This matches some with EPS probabilities of 40 to 60% of highs >100F
Sunday. It has been noted this ensemble approach sometimes runs cool.
Unfortunately, storm chances look doubtful as this high prevails.
&&
.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 1100 PM CDT Wed Jul 10 2024
VFR conditions will prevail in vicinity of all TAF sites through
late Thursday afternoon. Light and variable winds through late
Thursday morning are expected to turn east-southeasterly 5 to 15kt
in the afternoon as lee side troughing develops in eastern Colorado.
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
DISCUSSION...Sugden
AVIATION...JJohnson
Forecast Discussion at weather.gov/mqt.
&&
.HYDROLOGY...
Issued at 330 AM CDT Wed Jul 10 2024
A Flood Advisory continues across portions of the Rainy River
Basin, extending as far east as Lac La Croix and as far west as the
Rainy Lake outlet. This advisory remains in effect through
Friday, but as levels in waterways further east crest, it may be
trimmed in its areal extent prior to expiring. However, for
areas further west, the Advisory may need to be extended in
time. Lingering high water from rains in June continue across
the Rainy River Basin. The Vermilion River continues to fall.
This has allowed the lake level increases on Crane Lake to slow
considerably, with lake levels having flattened out in the last
12 hours, likely having reached its crest. Lac La Croix levels
are cresting and should begin to slowly recede through this
week.
All this high water continues to lead to steady rises on downstream
lakes, notably Namakan/Kabetogama (Nam/Kab) lakes where minor
flooding continues, and on Rainy Lake where levels have just exceed
the rule curve. Past events have shown there is a lag between the
crest at Lac La Croix and the crest on Namakan lake of anywhere from
3 to 10 days (the longer coming from events when rain fell around
peak waters). As water levels upstream crest and begin to come down,
rates of rise on Nam/Kab should begin to slow and eventually crest,
possibly by late this week or this weekend. Rates of rise have
slowed to 1-1.5"/day over the weekend and in the last 24 hours there
was only about a 0.5" rise on Kabetogama/Namakan as inflows are
decreasing. Until peak, another 2.5-7 inches of rise could be
possible (estimate, not an official forecast), with the high end
of that range probably being a worst case scenario. This could
bring Nam/Kab just over 1120 feet with a peak level somewhat
similar to the high water during the summer of 2014. This is
still 2 feet or more below the high water levels of Spring 2022
- we are nowhere close to that level of flooding and extreme
rises to that point are currently not expected. As is usual for
this basin, water will move slowly and recessions will happen at
glacial speeds with some flavor of high water possibly
continuing through the month. However, peak should happen sooner
rather than later, based on latest observations. Additional
rainfall may cause brief rises in tributaries and extend the
period of high water in core lakes. Boaters should expect high
water, potentially hidden underwater hazards (including
submerged docks), and strong currents in constricted areas.
Generally light winds are expected, except for possible brief
erratic gusts out of thunderstorms, so wave heights should
remain fairly minimal.
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...Beach Hazards Statement until 10 PM CDT this evening for
MNZ037.
WI...Beach Hazards Statement until 10 PM CDT this evening for
WIZ001.
MARINE...None.
&&
$$
DISCUSSION...Britt
AVIATION...Unruh
MARINE...Britt
HYDROLOGY...Rothstein
Area Forecast Discussion...Updated
National Weather Service Lincoln IL
842 PM CDT Wed Jul 10 2024
.KEY MESSAGES...
- Scattered showers and thunderstorms are expected into Friday.
Locally heavy rain will be the main concern.
- Trends continue to point toward heat and humidity building early
next week, with the heat index above 100 degrees as early as
Sunday.
&&
.UPDATE...
Issued at 841 PM CDT Wed Jul 10 2024
Scattered showers and thunderstorms continue along the I-74
corridor this evening while more isolated activity is in place
further south. A number of outflow boundaries have surged well
ahead of storms in the area which along with loss of daytime
heating should allow convection to diminish in coverage over the
next few hours. Will maintain some isolated mention of precip for
portions of central Illinois overnight as an upper low currently
over Iowa digs slowly southeast tonight.
Deubelbeiss
&&
.SHORT TERM... (Through Thursday)
Issued at 252 PM CDT Wed Jul 10 2024
Latest water vapor imagery shows a compact upper low and
associated trough across northern Iowa. Ahead of this, a band of
showers and scattered storms has developed from near Mattoon into
northern Illinois west of Rockford. This band appears to have
initiated near a lingering surface boundary, with the NAM Nest
handling it the best, keeping sporadic activity into the
afternoon. With the Iowa activity, the ARW appeared to initiate
it the best, though several of the high-res models show a general
increase in activity as the wave gets closer to Illinois. PoP`s
have been increased into the 40-50% range into early evening over
the northern half of the forecast area, though the latest HRRR and
FV3 suggest decent chances continuing as late as midnight. While
parameters for any severe weather in our area are meager, an
increase in precipitable water values to around 1.5 inches early
this evening point toward locally heavy rain with the stronger
storms, currently favored north of I-74. The upper trough will not
be in any hurry to exit, so a repeat of pop-up showers/storms is
expected Thursday, especially afternoon.
Geelhart
.LONG TERM... (Friday through Next Wednesday)
Issued at 252 PM CDT Wed Jul 10 2024
Upper level high pressure ridge, currently anchored across the
Desert Southwest into Saskatchewan, will gradually build eastward
through the weekend, though flattening a tad. By early next week,
a large portion of the central and southern CONUS will be under
its influence, with the main storm track along the Canadian
border. A few more showers/storms will start the weekend with
another wave scooting out ahead of the ridge, but main focus for
convective activity will be with potential MCS activity along the
periphery of the ridge. The GFS holds the ridge on a little longer
with the storm track mainly north, while the European model
settles a boundary closer to our area. At this range, will keep
PoP`s in the 20-30% range while things shake out a little more.
With the heat, WPC guidance continues to suggest a >40% chance of
heat index values reaching 105 degrees (local heat advisory
criteria) Monday and Tuesday. Much will depend on the
aforementioned MCS activity and any residual cloud cover, but
evapotranspiration season is in full swing and dew points well
into the 70s may counter any suppressed temperatures. As it is,
high temperatures in the 90-95 degree range are still expected
Sunday through Tuesday.
Geelhart
&&
.AVIATION... (For the 00z TAFs through 00z Thursday Evening)
Issued at 628 PM CDT Wed Jul 10 2024
Scattered thunderstorms are ongoing across central Illinois, but
will begin to taper off in coverage mid to late this evening with
dry conditions expected the remainder of the evening and
overnight. Scattered storms will again be possible Thursday
afternoon and evening. Light and variable winds will be in place
most of the overnight hours, and will eventually set up out of the
NE at less than 10 kt mid to late Thursday morning. Meanwhile,
some patchy fog is possible Thursday morning, especially along the
I-74 corridor.
Deubelbeiss
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
1055 PM CDT Wed Jul 10 2024
.KEY MESSAGES...
- Scattered non-severe thunderstorms in the area this afternoon
and again tomorrow afternoon.
- Hot and humid conditions expected early next week. Heat
indices may approach or exceed 100 degrees.
- Periodic thunderstorm chances Saturday through mid next week,
including the potential for a couple nocturnal/early AM
t-storm complexes.
&&
.UPDATE...
Issued at 1043 PM CDT Wed Jul 10 2024
Updated PoPs through the evening into the overnight to account
for the ongoing shower and storms coverage across north central
and east central Illinois into far northwest Indiana. Lots of
boundaries tracking across the region this evening brought
widespread growing and decaying storm activity. Some of the
heaviest storms produced heavy rainfall and gusty winds, however
these have since diminished to widespread rainfall across the
aforementioned area over the past couple of hours. Now seeing
the breakdown of these boundaries throughout the region where
shower activity cannot sustain and should continue to see the
diminishing activity fade away.
Starting to see some additional development across far
northwestern Illinois into the Mississippi River Valley. This
precipitation is anticipated to remain near the edge of our
area, however models do not have the best handle on this
development.
Baker
&&
.DISCUSSION...
Issued at 339 PM CDT Wed Jul 10 2024
Through Thursday Night:
Convection has sprouted this afternoon along a surface
convergence axis extending from near Freeport, IL to near
Danville, IL. Convective coverage should continue to increase
heading into this evening as large-scale forcing for ascent
increases with the approach of a mid-level disturbance currently
twirling its way across southern Minnesota and into Iowa, with
outflow boundaries also helping to kick-start new convection. A
consistent signal in recent runs of both the HRRR and WoFS
lends relatively high confidence in the convective footprint
remaining maximized generally near and west of a Rockford, IL to
Watseka, IL line, but radar and satellite observations suggest
that at least isolated showers and possibly storms remain
probable through this evening farther to the east.
Mediocre mid-level lapse rates and deep layer shear should
prevent any of today`s storms from becoming severe, and a warm
nose near 600 mb will also likely play a role in curtailing
overall thunderstorm coverage and longevity, particularly east
of the aforementioned line. That being said, the strongest
convective cores can still be expected to produce locally
torrential rainfall, small hail, and gusty winds (possibly up to
around 45-50 mph). With the relatively slow storm motions and
presence of multiple surface boundaries, wouldn`t be entirely
surprised if any favorable cell-boundary interactions led to an
isolated funnel cloud or two being spotted somewhere -- though
any actual touch-downs occurring would be highly unlikely.
The same air mass will remain in place into tomorrow, and thus
similar conditions to today can be expected. High temperatures
will likely end up being in the low 80s/near 80F at most
locations, though onshore flow should cause locations closer to
the lakeshore to remain in the 70s. The aforementioned
Minnesota/Iowa disturbance will likely be near or directly over
our forecast area come tomorrow, and with similarly moist near-
surface conditions remaining in place, isolated to scattered
diurnal convection thus is likely to blossom once again. Current
thinking is that convective coverage tomorrow may not be quite
as widespread as it should be today, and it appears that it may
end up focusing near and south of I-80, but the QPF spread in
the latest suite of forecast guidance warrants carrying at least
a slight chance PoP mention across our forecast area.
Once again, lackluster mid-level lapse rates and deep layer
shear should curtail a threat for severe weather, but we`ll have
to keep an eye on the potential for localized minor flooding
with the expectation that any storms that develop will be
slow-moving, efficient rainfall producers. The likelihood of
any hydrologic concerns arising would be greatest wherever the
rainfall amounts from today and yesterday were highest. Also
couldn`t rule out some additional funnel cloud funny business
given the likelihood of a mid-level vorticity maximum gyrating
directly over our CWA.
Ogorek
Friday through Wednesday:
Friday will be primarily quiet and seasonably warm (mid 80s
inland), except cooler (mid-upper 70s) near the lake. Following
the exit of mid-upper level low pressure into the central and
eastern Great Lakes, very dry air aloft and persistent mid-
level height rises of 4 DaM/12 hour should effectively cap most
of if not all diurnal convective development. With lingering
higher dew points south of I-80 (upper 60s to around 70F),
erosion of MLCINh and subtle convergence may be enough for
widely isolated showers and maybe a thunderstorm, if any
updrafts can survive pronounced dry air entrainment. Surface
high pressure will remain over the area through Friday night,
making for a quiet and seasonably mild night.
The first potential episode of convection in the humid and at
times stormy pattern expected this weekend through early next
week may arrive Saturday morning in parts of the area, probably
in a weakening state. This will occur in concert with a warm
front lifting north and a large instability reservoir advancing
eastward across the mid and upper MS Valley. Large scale forcing
mechanisms will be lacking through the afternoon, though any
convectively induced impulses, and convergence tied to lingering
outflow and the northward advancing warm front may be enough for
widely scattered afternoon pulse-type thunderstorms (30-40% PoPs).
Highs on Saturday will be in the mid to upper 80s, except
slightly cooler lower 80s along the Illinois shore due to lake
influence backing winds east- southeasterly. Dew points in the
upper 60s to lower 70s at peak heating will yield peak heat
indices in the low-mid 90s, a harbinger of things to come Sunday
through Tuesday.
Expansive mid-upper 500s DAM 500 mb ridging centered over the
inter-mountain west and mean troughing centered over Hudson Bay
will set up a hot and humid northwest flow aloft locally in the
Saturday night-Tuesday timeframe. Unlike previous occurrences
this warm season of overnight arriving convection weakening
quickly as instability diminishes, the impressive instability
reservoir (3000-4000+ J/kg of MUCAPE) will largely remain in
place through the period. This entails a period of "ring of
fire" conditions, where our position on the northeast flank of
the ridge puts us in the threat zone for southeastward moving
convection, including potentially well-organized severe MCSs,
and episodes of flash flooding due to PWATs up in the ~1.75-2"
range at times (150-200% of normal).
Aside from operational and ensemble members hinting at the
likelihood of this type of activity, specific timing
predictability in these types of patterns are commonly low
confidence. This maxes out PoPs only in the chance (30-40%
range) during windows of MCS favorability at this lead time.
The first window may be Saturday night, prior to stronger deep
layer shear being present, followed by Sunday night into early
Monday when 40+ kt of deep layer bulk shear is forecast. Monday
night into early Tuesday could end up being another window for
parts of the area as well. Classic in these type of patterns,
there will be many dry hours, and a relative daytime
lull/capping Sunday and Monday PM will support highs in the
lower to possibly mid 90s with dew points in the 70s yielding
peak heat indices flirting with heat advisory (105+F) criteria.
Tuesday afternoon will be similar thermally to Sunday and
Monday, though perhaps less capped with a bit better chance of
widely scattered PM thunderstorms as a weak cold front advances
south. It`s unclear whether the appreciable instability axis
will be shunted far enough south by Wednesday to limit another
round of convection, especially south of I-80, as the cold front
takes on back door characteristics. What is of higher confidence
is an end to the hot and humid conditions, with forecast high
temps on Wednesday in the low-mid 80s inland and upper 70s near
Lake Michigan.
Castro
&&
.AVIATION /00Z TAFS THROUGH 06Z FRIDAY/...
Issued at 650 PM CDT Wed Jul 10 2024
Forecast concerns include...
Chance of showers this evening and again on Thursday.
Possible fog overnight.
Scattered thunderstorms are mainly focused across west and
central IL early this evening and this looks to be the area
where they will continue into the evening as they slowly weaken.
Additional showers will be possible across northern Il along
with possibly an isolated thunderstorm in the next hour or so as
various outflow boundaries interact with each other.
There will be another chance for showers and possibly isolated
thunder on Thursday with better chances southwest of the
terminals. Along with isolated coverage, confidence is too low
to include any precip mention in this forecast.
Fog is possible overnight into early Thursday morning and mainly
south and west of the Chicago terminals. There may also be some
mvfr or possibly ifr cigs across central IL, where the current
rains are the heaviest. Overall confidence for fog is low and
maintained mention at RFD and GYY. Trends will need to be
monitored through the night.
Wind directions have been problematic with the various outflow
boundaries. Eventually, they should settle on a light southeast
direction this evening or become light and variable. Winds may
favor a more light north/northeast direction by daybreak and
then remain northeasterly on Thursday. cms
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.
&&
$$
Visit us at weather.gov/chicago
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
647 PM CDT Wed Jul 10 2024
.KEY MESSAGES...
- Scattered showers and thunderstorms will continue into this
evening with locally heavy rain possible, particularly across
southern Minnesota.
- The second half of the work week will be mainly dry with hot
and humid conditions arriving by the weekend, along with the
return of thunderstorm chances.
&&
.DISCUSSION...
Issued at 146 PM CDT Wed Jul 10 2024
Scattered showers and thunderstorms have been ongoing much of the
day across south central Minnesota. Anywhere from a quarter inch to
near three quarters of an inch of rain has fallen where the more
persistent rain continues to fall early this afternoon. Further
north and west, afternoon convection is starting to take shape,
much like the past two days. Isolated to scattered
thunderstorms will once again last into the evening hours with
locally heavy rain and gusty winds possible. STC reported a 44
MPH gust with the thunderstorm that moved through around 1:30pm,
so winds of this caliber with other stronger storms will
continue to be a threat. Overnight, high pressure moves overhead
with clearing skies and light winds leading to patchy dense fog
by Thursday morning. We will finally get a break from the daily
precip chances Thursday through Friday with highs beginning to
climb into the mid to upper 80s.
This warming trend will continue into the weekend as the upper ridge
over the western CONUS shifts east, with low level southerly
flow sending ample Gulf moisture northward. Many locales will
see their first 90 degree day of the year on Saturday with low
to mid 90s expected area wide by Sunday. When coupled with dew
points in the 70s, heat headlines may be needed with WBGT values
in the mid 80s. With this heat and humidity comes ample
instability, but with 850mb temps nearing 18-20C both days, it
may be hard to overcome that cap. A series of shortwaves are
expected to traverse the region Saturday and Sunday, but the
stronger and more impressive wave of the weekend looks to arrive
early Sunday. This would be the better of the two days for
severe weather, but there is still plenty of uncertainty this
far out. Heading into next week, hot and humid conditions will
hang on through Monday before a cold front moves through and
allows temperatures to fall back into the low 80s through the
end of the period.
&&
.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 627 PM CDT Wed Jul 10 2024
The upper low that helped spark today`s storm is over northern
Iowa and will work toward the Quad Cities through the night.
This will finally bring to an end our daily diurnal shower
activity. The only concern this period will be the potential for
fog given the expected light winds and skies that will be
clearing through the night. Fog will be most likely at locations
that saw rain today, with the HRRR hitting MKT/RWF particularly
hard. For the rest of Thursday, no concerns are expected as a
diurnal cu field develops with winds gradually turning to the
southwest at less than 10 kts.
KMSP...Fog will be of the radiational variety that MSP almost
never gets, so fog is not expected Thu morning for MSP.
/OUTLOOK FOR KMSP/
FRI...VFR. Wind S 5-10 kts.
SAT...VFR. Slight chc -TSRA. Wind S 5-10 kts.
SUN...VFR. Slight chc -TSRA. Wind SW 5-10 kts.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...None.
WI...None.
&&
$$
DISCUSSION...Dye
AVIATION...MPG
Area Forecast Discussion
National Weather Service Omaha/Valley NE
611 PM CDT Wed Jul 10 2024
.KEY MESSAGES...
- A few storms may produce hail and gusty winds this afternoon
into this evening. Best chances are in southeast Nebraska and
southwest Iowa.
- Most should remain dry through the weekend, but like many
recent days, there could be some spotty showers and storms
Thursday and Friday (5 to 10% chance).
- Dangerous heat is expected for much of the area this weekend
into Monday, with heat index readings of 100 to 110 degrees
likely. Sunday and Monday will be the hottest days.
&&
.DISCUSSION...
Issued at 233 PM CDT Wed Jul 10 2024
Mostly clear skies are obscured in parts of southwestern Iowa
with a shortwave helping to produce some agitated cumulus from
Seward County, NE to Montgomery County, IA. The area has gone
from an SPC category of "general thunder" to now "slight with
hatched hail", representing a two category jump in severe
weather threat. A WATCH has been posted from Lancaster County to
past the Kansas and Missouri state lines and far southern Iowa.
The primary change in the forecast was a slight increase in
expected BWD and steepening lapse rates with newer model runs.
The primary threat is 1-2" hailstones with a multicellular
storm mode. As the boundary layer cools this evening, the LL
lapse rates moderate and storms should weaken. The last of the
convection should be pushing into Missouri by midnight.
Have introduced patchy fog to the grids overnight in response to
the lack of winds and high dewpoints. Believe northeast Nebraska
has best chance of seeing the fog, but it could as far south as
I-80. Latest HREF suggests about a 50% chance of visibility
slipping below 5 miles along and north of I-80. With a high
summer sun angle, expect that fog to dissipate quickly on
Thursday morning.
While skies are expected to remain mostly cloud-free, we expect
them to remain milky with continued Canadian wildfire smoke
elevated across the area. The HRRR produces very little surface
smoke in it`s mid-day runs today, though at 3,000 feet the smoke
is considerably more dense and growing denser over the next 24
hours, especially for western Iowa. For all but those very
sensitive to smoke, it should act mostly as a sun filter.
Believe Thursday and Friday`s low POP chances deserved to be
pushed lower with deterministic models keeping things dry with
weak instability, little forcing, and paltry but noted cap in
place both afternoons.
Attention turns to the season`s hottest three day stretch so
far with high temps in the middle to upper 90s for three
consecutive days. Dewpoints, too, will be trending toward the
extreme. Have bumped up those supplied by the NBM.
Evapotranspiration from crops will help western Iowa`s
dewpoints to climb at least into the mid-70s: Hot and humid.
Sunday and Monday will be the hottest days with heat indices
managing 102 to 106 for most on Sunday and similar readings for
the southern half of the CWA for Monday as a cold front slips
through the area. As it stands, we`re shy of our excessive heat
warning criteria each afternoon but close to the 75F minimum
heat index suggested by NWS directives. The lower criteria
needed for a heat advisory may be met with forecast max heat
indices of 105+. As confidence grows heat headlines may need to
be issued, especially in the metro areas where concrete and
massive apartment buildings tend to hold the day`s heat much
later into the night.
20-30% PoPs have been introduced to the forecast for Monday
night (cold front) and Tuesday as the upper level ridging
breaks down and flow becomes zonal.
&&
.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 556 PM CDT Wed Jul 10 2024
Scattered thunderstorms are ongoing across southeast Nebraska.
This activity is within the vicinity of KLNK, though
precipitation is expected to remain south. Lightning should
move out of the KLNK terminal area by the start of this TAF
period, but will monitor closely. There is also a very low
chance (10-15 percent) of a thunderstorm at KOFK between 01 and
03 UTC. These storms, currently around Sioux City, appear to be
weakening and odds are will not make it to KOFK. Convection
should remain south of KOMA. After 07 UTC, patchy fog (30 to 40
percent chance) is expected to develop across eastern Nebraska
and western Iowa. It does not appear to be a strong signal at
TAF sites, however if fog does develop visibilities down to 2
miles will be possible. Will monitor closely for inclusion into
TAFs tonight. Any fog that develops should be gone by 13 UTC.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...None.
IA...None.
&&
$$
DISCUSSION...Nicolaisen
AVIATION...Darrah