Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 06/27/23
Area Forecast Discussion
National Weather Service La Crosse WI
658 PM CDT Mon Jun 26 2023
.DISCUSSION...(Tonight through Monday)
Issued at 207 PM CDT Mon Jun 26 2023
Key Messages:
- Smoke impacting air quality and visibilities,
especially in Wisconsin
- Shower and Thunderstorms chances ramp back up later Wednesday
into Wednesday night with low end severe weather risk
- Other precipitation chances Friday and Saturday
Tonight & Tuesday Smoke:
Near-surface smoke has returned to the region, ushered in by
southwesterly flow on the back side of a departing surface low. The
eastern half of Wisconsin is currently experiencing the highest
concentrations of near-surface smoke. Most surface observations show
visibilities of 3 to 5 miles. The HRRR smoke model shows some of
this smoke moving southwest today with locations east of the
Mississippi River seeing an increase in near-surface smoke by this
evening.
Expect reduced visibilities and AQI values in the Moderate to
Unhealthy categories. Susceptible populations, including those
with heart or lung disease, older adults, children, and pregnant
people, should keep outdoor activities light and short. Tomorrow
near- surface smoke concentrations should improve from north to
south during the day with a majority of impacts remaining east of
the Mississippi River.
Tonight through Wednesday Night Trends and Storm Threats:
Closed upper low continues to spin across Great Lakes as mean ridge
builds across central Plains. Although still dealing with pesky
stratus, light showers, and smoke /see previous section/ around low,
trend is for a little quieter going into Tuesday as low moves away
and ridge axis approaches.
Spoiler is short wave trough ejecting out of Intermountain West that
is progged to flatten said ridge and combine with Canadian short
wave to sweep a front into western Great Lakes towards Wednesday.
Mid level southern wave may provide enough shear /40 kts or so/ for
stronger storms with low level moisture axis a bit more respectful
across Iowa and Minnesota as moisture rides north ahead of front.
Some spread in the 26.12z model runs with deterministic surface dew
points fields but prefer ECMWF solution with lower dew points
holding tough in Wisconsin which has been a constant so far this
convective season. Bottom line is we will have to watch trends for
convective threat as waves approach. Day 3 MRGL RISK by SPC seems
like a good step at this point.
Overall coverage of showers or storms on Wednesday also unclear.
Some signs that rain threat could be best north of the immediate
area tied closer to northern wave, but also see some hints of
convective clusters in various CAMS further south. Given time of
year and decent wave passing through, most areas will at least have
a shower or storm threat at some point late Wednesday into Wednesday
night with lower risks closer to Interstate 90 corridor perhaps.
Thursday through Monday:
While medium range guidance starts to vary in outcomes with time,
big picture is less blocking pattern and more general westerlies
meaning more passing systems moving through. Appears there could be
more of a persistent troughing across northern Great Lakes from late
week into the weekend, with separate waves transversing the
central CONUS south of our area. This pattern would at the very
least suggest minimal severe weather risk as we close out our
climatological peak part of the season. Various chances of rain
/20- 30%/ mainly focused on southern waves but later forecasts
might be able refine or tighten gradients.
Surface ridge Sunday and Monday might bring some of the best weather
with a far lower rain threat and a warming trend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 658 PM CDT Mon Jun 26 2023
VFR conditions are expected through the TAF period.
As previously mentioned, the main concern revolves around smoke
at the surface. Latest guidance continues to keep highest
concentrations just to the east of KLSE, but if smoke does make it
farther west visibility restrictions at KLSE will be possible.
Have maintained the current VFR visibilities, but will continue to
monitor trends and observations through the evening for any
adjustments needed later. Increased winds will gradually subside
overnight and remain light through the period.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
DISCUSSION...KAA/Shea
AVIATION...EMS
Area Forecast Discussion
National Weather Service Denver/Boulder CO
826 PM MDT Mon Jun 26 2023
.UPDATE...
Issued at 822 PM MDT Mon Jun 26 2023
A severe thunderstorm east of Pine Bluff continues to track closer
to the CO border. SPC has issued a Severe Thunderstorm Watch which
includes Logan, Segwick and Phillps counties until midnight MDT.
Main threats are large hail up to 2 inches and wind gusts to 70
mph. An isolated tornado is also possible.
UPDATE Issued at 710 PM MDT Mon Jun 26 2023
Isolated showers/thunderstorms have develop over the Palmer Divide
south of Denver so I add some isolated coverage across Elbert and
northern Lincoln County this evening. Elsewhere will be fairly
quiet but will need to watch a severe thunderstorm north of Pine
Bluffs, NE. The models hint of this possibly clipping Sedgwick
County around 10 pm. Outside of some minor adjustment to those
areas, the rest of the grids look good. We fell short of the 90
degree mark this afternoon with a high of 86 for Denver. Another
chance awaits on Tuesday, but that will be close too.
&&
.SHORT TERM...(This evening through Tuesday)
Issued at 240 PM MDT Mon Jun 26 2023
Day cloud phase satellite shows a sunny picture this afternoon with
minimal cloud cover over the region. A patch of cumulus has
developed across the northeast portion of the plains. These are the
areas that display a less capped environment on the SPC
mesoanalysis. Moisture is still evident with dewpoints in the 60s
across the east plains. The mountains and urban corridor will still
likely remain on the dry side this evening. With the more favorable
environment, can`t rule out a storm over the east plains this
evening which may present the potential to be strong to severe. It`s
not looking to be a widespread, high probability scenario.
For Tuesday, the ridge remains aloft with continued warming aloft
and less moisture. A 500mb jet remains aloft and model soundings are
supportive of ample mixing to the surface (up to 500mb in some proxy
soundings), transporting the enhanced winds down to the surface in
the afternoon. There is a little uncertainty in how strong the gusts
get and this has to do with a few factors. One is cloud cover as
some models show some mid-level moisture. This could damper the
overall mixing. Next is that a handful of higher-res models and also
the NAM project a weak front moving through late afternoon/early eve
which could also impact potential for deep mixing. Another cluster
of guidance is set on the full mixing scenario such as the HRRR and
even the HREF means stick to this as well. As a result, bumped
winds/gusts down a little bit and settled for potential for 25-30
mph gusts in the urban corridor. For precip. potential, there will
be some instability out on the east plains and some residual
moisture resulting in low PoPs in the afternoon/early evening. Highs
will make another attempt at hitting 90 Tuesday, but if mid-level
clouds form, it may prevent this. Regardless of the details, expect
a decently hot, breezy, dry day across northeast Colorado.
.LONG TERM...(Tuesday night through Monday)
Issued at 240 PM MDT Mon Jun 26 2023
Colorado will be between a trough over the Pacific Northwest and
ridge to the south and southeast. There will be southwesterly flow
aloft with warm and dry weather through about mid week. The
trough should advance in the latter part of the week, as more of a
shortwave, bringing lift and better moisture which should result
in greater coverage and intensity of precipitation. It is an
overall familiar synoptic setup for the long term forecast period,
but lacking the anomalous moisture of recent weeks.
Expect a cooling trend through the week supported by a couple
weak, cool fronts, probably passing late Tuesday or early
Wednesday and Thursday. Fog and low clouds are possible Thursday
morning behind the front. The cooling trend will probably break
sometime over the weekend, then temperatures to warm back up
through the rest of the period.
This weekend, flow aloft will turn northwesterly behind the
passing shortwave, which would normally favor us a more active
weather pattern were we to retain moisture for it. However, there
looks to be more dry air aloft with will likely suppress
convection significantly. Ensemble forecast systems, such as the
WPC cluster analysis, suggest low confidence in the finer forecast
details for the late weekend and early next week, as solutions
differ on the placement and intensity of the next synoptic wave.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 710 PM MDT Mon Jun 26 2023
VFR tonight, with southeast winds (8-12 kts) transitioning to
drainage this evening. VFR Tuesday, lighter southwest winds in the
morning will transition to gusty west/northwest winds by the
afternoon, with gusts to 30 kts after 19z.
&&
.FIRE WEATHER...
Issued at 240 PM MDT Mon Jun 26 2023
Elevated to critical fire weather conditions likely Tuesday across
the high country, foothills, and western I-25 corridor. Ample
mixing will promote breezy conditions at the surface paired with
RH less than 15 percent in the mentioned areas. Despite weather
conditions reaching Red Flag criteria in many spots, fuels remain
non-critical due to recent rainfall. This will reduce fire
weather concerns and therefore won`t result in headlines.
Elevated to critical fire weather conditions likely to persist
across the high country and parts of the adjacent and southern
plains Tuesday evening and Wednesday afternoon and evening.
Afternoon minimum humidity 10 to 15 percent will be coincident
with gusts to around 30 mph in many areas. However, fuels are
still wet and non-critical across northeast Colorado, and this
mitigates fire weather concerns. In recent days, and few wildfires
which started failed to spread, and this increases confidence.
&&
.HYDROLOGY...
Issued at 240 PM MDT Mon Jun 26 2023
Dry conditions expect across the burn areas Tuesday, resulting in
no threat for flash flooding across the burn areas. Some
rivers/creeks continue to run high across the plains, but are
forecast to trend below action stage in the next day or two.
There may be a limited threat of burn area flash flooding,
particularly to Cameron Peak, in the latter half of the week and
weekend. Through about mid week, any showers should be
significantly moisture limited.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...Cooper
SHORT TERM...Mensch
LONG TERM...EJD
AVIATION...Cooper
FIRE WEATHER...EJD/Mensch
HYDROLOGY...EJD/Mensch
Area Forecast Discussion
National Weather Service Columbia SC
839 PM EDT Mon Jun 26 2023
.SYNOPSIS...
Scattered showers and thunderstorms are expected later this
afternoon and into tonight. Confidence continues to increase
for strong to potentially severe thunderstorms with large hail
and damaging winds as the primary hazards. Drier air then
spreads into the area Tuesday into Wednesday with seasonable
temperatures. More typical summertime conditions follow for the
late week period and into the weekend as ridging slowly builds
east.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
Overall it has been a relatively quiet afternoon with most of
the convection and severe weather remaining to our north, but
storms have recently developing across the NC Piedmont and
expanding in coverage around the CLT metro area. Radar shows
these storms moving with the mean flow from west to east and
should remain to our north, however, there is a lone supercell
crossing the state line into SC southwest of Shelby that we will
have to monitor.
The environment over the forecast area remains very unstable
with LI values around -10C and MLCAPE values 1500-2000 J/kg with
DCAPE values 1300-1400 J/kg. A moisture gradient exists across
the region with PWATs ranging from 1.4 inches west to 1.7 inches
east with dewpoints in the 70s. Hi-res guidance has not been
great with initiation this afternoon so confidence has been
limited in them but the HRRR and others are indicating
convection developing over our area later this evening as the
shortwave energy drops further south and the cold front to the
west pushes into the region.
Severe watch for Lancaster/Chesterfield counties continues
until 11 pm. Have updated pops to account for the general lack
of activity thus far but expecting some additional convection
during the 9pm-3am time frame. Severe risk continues during this
time but uncertain if storms may become elevated with time
through the night reducing the severe risk. Temperatures will
remain mild overnight with lows in the upper 60s to lower 70s.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/...
Tuesday and Tuesday Night: The trough shifts east on Tuesday
ushering in a drier air mass. A reinforcing front will move
through during the afternoon and evening hours but should not
have much impact on the forecast area outside of producing
scattered clouds. Any showers and thunderstorms that develop
should remain to our east closer to the coast. Despite the
passage of a cold front, temperatures should be similar to today
with highs in the upper 80s to lower 90s. Tuesday night is clear
and dry with lows in the mid to upper 60s.
Wednesday and Wednesday Night: An upper-level ridge will build
over the Central United States on Wednesday. This will likely
be the driest day of the week under mainly sunny skies as weak
surface high pressure builds to our north. Temperatures will
remain in the upper 80s to lower 90s during the day. Overnight
lows will be in the upper 60s to near 70 degrees.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
Ridging anchored over the Central CONUS will be the primary
driver of our weather during the long term. Rising heights will
promote a slight warming trend. Moisture also gradually
increases due to easterly to southeasterly surface flow,
allowing for the typical summertime showers and thunderstorms in
the afternoon and evening. The combination of heat and humidity
could result in several days of Heat Index values in the 100 to
110 range during peak heating later this week. The ridging
flattens this weekend as a trough digs into the Eastern United
States which could increase convective chances Sunday and
Monday. Temperatures will be above normal through the extended
period.
&&
.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
Storms have remained north of the area but are expected to start
forming within the Midlands around and after sunset.
Thunderstorm coverage is expected to be isolated to scattered
and lowest chances are along the Augusta area. No restrictions
are expected outside of thunderstorms and showers, but strong
gusts possible within thunderstorms. Convection will exit to
the east by 08z. Few to scattered cumulus Tuesday afternoon
otherwise clear. Winds westerly with gusts up to 25kt. Fog
threat remains low.
EXTENDED AVIATION OUTLOOK...Drier air through mid-week with low
confidence in restrictions. Diurnally driven convection may
lead to brief restrictions late this week into this weekend.
&&
.HYDROLOGY...
The Congaree river remains in flood due to the widespread heavy
rainfall last week and reservoir operations. Please refer to
water.weather.gov/ahps for the latest river stage observations
and forecasts.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
&&
$$
Area Forecast Discussion
National Weather Service Cheyenne WY
525 PM MDT Mon Jun 26 2023
.SHORT TERM...(This evening through Wednesday night)
Issued at 330 PM MDT Mon Jun 26 2023
The main forecast challenges over the next few days mainly deal with
the ongoing isolated to scattered storm potential over portions of
the area.
Currently we have mostly clear skies across the area after the
morning cloud cover has mostly broken up. The early morning
convection modified the surface airmass for most areas east of the
Laramie range, causing a lot of hires models to be playing catchup
this afternoon. The low levels remain quite moist in this area with
dewpoints mainly in the 50s, while very dry air tries to work in
aloft. This has mixed down to the surface for areas west of the
Laramie range, sending dewpoints plummeting into the teens, while a
sharp dryline sits close to the crest of the Laramie range. The main
uncertainty for today and tonight is the location and development of
any convection. Stronger than expected nocturnal convection has
thrown a wrench into this evening`s forecast by turning over the
atmosphere up north and leaving a few outflow boundaries scattered
about the area. The HRRR and NAMnest have been fairly consistent
since 12z in showing a lone supercell initiating off of the remnant
outflow boundary between 22z and 00z this evening, and then
skirting off to the east across the central/southern panhandle.
The main uncertainty is if this potential cell can survive through
the substantially dry middle atmosphere located over Wyoming and
make it to the more favorable moisture environment further east,
or get choked off quickly. If it can survive, the potential storm
would encounter a moist, unstable environment with 0-6km shear of
50 to 60 knots, which could support large hail growth. This
prompted an expansion of the Marginal risk to the south and an
introduction of slight chance PoPs for most areas east of the
Laramie range.
We will also have to watch the potential for another round of Dawes
county clippers this evening and into tonight. Moist isentropic lift
will develop this evening in the presence of substantial elevated
instability and ample shear. Our area will again be on the edge of
the favorable moisture environment, but the dynamics suggest this
activity could expand a little further southward than what the hires
models are showing right now. Again, the main uncertainty is if
something will be able to develop this far south, but if it does, it
will have the potential to produce large hail and gusty winds. This
looks like a very late show, starting after 00z and going
potentially through 09z or so. The main area of concern here is
Converse, Niobrara, Sioux, Dawes, and Box Butte counties.
On Tuesday, the ridge axis of the stout but intense ridge located
over Texas will shift slightly eastward with a shortwave moving over
the top of it. This should push the dryline further east and bring
gusty southwest winds to much of the area along and west of I-25.
Gusts of 40 to 50 mph are likely. Overall a warm and dry day for the
southern half of the CWA (especially west), though deeper moisture
will likely remain present further north and east. Added lift from a
weak shortwave should help kick off some convection once again
mainly along and north of a line from the Ferris mountains to
Wheatland to Alliance. The unstable and highly sheared environment
will remain in place, so any storms that develop will have the
potential to produce large hail and gusty winds, but again the
uncertainty is in the development and location of any storms. For
Wednesday, expect the dryline to back into the Laramie range in the
morning, bringing in higher low-level moisture and overall
precipitable water to areas along and east of the Laramie range.
Thus, rinse and repeat for the forecast with rounds of isolated to
scattered thunderstorms developing during the afternoon, with the
potential to become severe collocated in the unstable, sheared
environment. Added in more widespread chance PoPs to most of the
area except southern Carbon county for Wednesday afternoon and
evening. Temperatures should be similar to Tuesday west of the
Laramie range, and a little cooler to the east.
.LONG TERM...(Thursday through Monday)
Issued at 400 PM MDT Mon Jun 26 2023
Long Range models still indicate a return to an unsettled weather
pattern starting during the middle of this week across southeast
Wyoming and the rest of the Nebraska Panhandle. Unsettled weather is
also expected to linger into this weekend with broad northwest flow
aloft, which will result in above average precipitation and cooler
than normal temperatures for early July.
All models continue to show the next upper level Pacific trough
moving into the Utah/Colorado/Wyoming region for Thursday and
Friday. 500mb heights are around one standard deviation below
average for late June with this trough, so expect a good chance of
cooler than normal conditions and numerous showers and thunderstorms
given recent above average boundary layer moisture and PW`s.
Thursday still appears to be the best day for severe thunderstorms
with MLCAPE between 1500 to 2500 j/kg and 0-6km shear above 45 to 50
knots. A potent shortwave ahead of the main trough is expected to
lift northeast across the area during the afternoon. Kept increased
POP towards 80 percent across the bulk of far southeast Wyoming and
most of western Nebraska. Cooler temperatures are expected with
highs dropping into the 70s and possibly staying in the upper 60s
Friday afternoon. Threat of flooding due to excessive rainfall may
return late this week and next weekend due to high PW`s and training
of storms.
Once the Pacific upper level trough exits the area to the east
Friday afternoon into the weekend, mid to upper level flow will back
into the northwest. Historically, this is typically and unsettled
and stormy weather pattern for southeast Wyoming and western
Nebraska for early July. So will have to closely monitor boundary
layer conditions coming up over the next few days. Expect below
normal temperatures during this period with a slow warming trend by
Sunday. Showers and thunderstorms are expected each day, especially
across southeast Wyoming with some stronger storms possible.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 524 PM MDT Mon Jun 26 2023
Main aviation concern this evening will be an isolated strong storm
or two. Expect frequent lightning, hail, and gusty winds with any
storm. Heavy rain could also lower visibility and CIGs. Other than
an isolated storm, gusty winds are expected at western Nebraska
terminals overnight with gusts up to 30 kts possible. Increased
moisture from more easterly flow will allow for the development of
low stratus. Lowered CIGs at western Nebraska terminals but did not
go below VFR as confidence is low to medium of this occurring.
Gusty winds return Tuesday afternoon.
&&
.FIRE WEATHER...
Issued at 330 PM MDT Mon Jun 26 2023
While fuels remaining in greenup status will prevent the issuance of
any fire weather headlines, near critical weather conditions are
possible across portions of the area along and west of the Laramie
range over the next few days. Very dry air in the middle atmosphere
moving in from the west is mixing down to the surface over Carbon
and Albany counties this afternoon, producing RH below 10% in some
areas with gusty southwest winds. Much higher moisture is present
east of the Laramie range, with a very sharp dryline in between. The
dryline is expected to dance back and forth across the I-25 corridor
over the next few days, creating a low confidence forecast in RH for
the Laramie range and eastern foothills.
Tuesday looks similar to today with warm temperatures and very dry
air to the west. Expect minimum RH to drop below 15% across most of
Carbon and Albany counties, as well as portions of Platte and
Laramie counties as the dryline retreats eastward. Southwest winds
gusting over 40 MPH are also likely in the same areas. Similar on
Wednesday, but for a smaller area as moisture surges back westward
and winds lighten up a bit. Isolated showers and thunderstorms are
possible mainly east of the Laramie range each afternoon. Expect
cooler temperatures, higher humidity, and greater precipitation
chances for Thursday into the weekend.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...None.
&&
$$
SHORT TERM...MN
LONG TERM...TJT
AVIATION...SF
FIRE WEATHER...MN
AREA FORECAST DISCUSSION
National Weather Service Hastings NE
609 PM CDT Mon Jun 26 2023
...Aviation Update...
.DISCUSSION...(This evening through Monday)
Issued at 405 PM CDT Mon Jun 26 2023
Key Messages:
* Wildfire smoke from Canada has been moving into portions of the
U.S. today. The HRRR shows the potential for some of that smoke
reaching as far south as Nebraska late this afternoon and into
this evening. Areas may encounter some hazy skies should this
smoke make it into the area.
* Periodic showers and thunderstorms will be possible from late tonight
through Sunday across the region. Right now, the best chance
for precipitation will be Thursday evening through Friday.
* Unseasonably warm temperatures are expected Wednesday and
Thursday, with highs reaching the 90s for portions of the area
both days. Of the two days, Wednesday will be the hotter day
with highs nearing triple digits in north central Kansas.
A Flood Warning continues for areas along the Platte River in
western and central Dawson County until further notice. Please
refer to the latest Flood Warning statement for additional details.
An upper ridge remains over the forecast area today with an upper
trough just offshore of Southern California. Afternoon high
temperatures today will be primarily in the 80s. A few low 90s will
be possible for portions of north central Kansas. Smoke from
wildfires up in Canada will continue to filter south into the U.S.
this afternoon and evening. The HRRR near-surface smoke shows some
smoke potentially making it as far south as Nebraska this evening.
Overnight, a weak shortwave trough will move through the region. We
will have a small chance of seeing a few thunderstorms develop to
our northwest late this evening, moving into the Hastings forecast
area after midnight. At this time, severe weather is not currently
expected.
Expect a similar set up for Tuesday, with the ridge remaining over
the region and afternoon temperatures expected to be in the 80s.
There will be a chance for additional thunderstorms in the afternoon
and evening as another shortwave trough moves through the area. A
few strong to marginally severe thunderstorms will be possible late
Tuesday afternoon through the evening. The best chance for any
severe weather across the forecast area will be mainly across
portions of Greeley, Howard, Sherman, Valley and Nance counties in
Nebraska. Large hail and damaging winds will be the main hazards
with any thunderstorms that develop.
Periodic showers and thunderstorms will be possible Wednesday
through Friday across portions of the High Plains and Central High
Plains. The pattern remains fairly unchanged through Thursday, with
the upper ridge still in place over the area. Afternoon high
temperatures Wednesday and Thursday will be primarily in the upper
80s to upper 90s, with Thursday being the cooler of the two days.
Morning lows will range from the low 60s to low 70s.
Thursday night into Friday, the upper trough to the west will lift
from the Four Corners Region into Nebraska and Kansas. For the time
being, this looks like the best chance for widespread precipitation
chances across the Hastings forecast area. Heading into the
weekend, the trough will exit the region to the east. Additional
small (20-30%) chances for showers and thunderstorms will be
possible across portions of the region. After a brief cool down
(low to mid-80s) Saturday, temperatures return to the mid to upper
80s Sunday.
&&
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Wednesday)
Issued at 541 PM CDT Mon Jun 26 2023
High pressure over SD/MN will slide ESE during the period which
will shift the winds from NNE to SE. A SFC trough moving out of
the Rockies tomorrow will tighten the gradient across the TAF
sites which will bring gusty winds to the sites around mid-
morning. Looking at the RAP smoke model for tonight it tries to
mix some smoke down to the SFC after 6z. I will put HZ in for now
and will pass on to next shift the possibility of FU making it
into the TAF sites overnight. Tomorrow morning the models try to
bring some scattered showers maybe an isolated TSRA across the
area. Didn`t have the highest confidence for VCTS for EAR, but
felt VCSH could be possible. The HRRR has higher chances around
GRI, so decided to put in VCTS for them.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
DISCUSSION...Wekesser
AVIATION...Beda
Area Forecast Discussion...Updated
National Weather Service Lincoln IL
845 PM CDT Mon Jun 26 2023
.SYNOPSIS...
Issued at 845 PM CDT Mon Jun 26 2023
Partly cloudy conditions will prevail across central Illinois
tonight with low temperatures dropping into the lower to middle
60s. Hazy skies will be observed on Tuesday as afternoon high
temperatures climb into the middle 80s.
&&
.UPDATE...
Issued at 845 PM CDT Mon Jun 26 2023
Winds have decreased markedly over the past couple of hours with
01z/8pm obs showing only a few remaining gusts of 15-20mph
along/northeast of a Bloomington...to Decatur...to Lawrenceville
line. As the pressure gradient relaxes and daytime mixing wanes,
N/NW winds will decrease to less than 10mph across the board by
midnight. Smoke from Canadian wildfires that mixed to the surface
earlier today across Wisconsin and northern Illinois continues to
drift E/SE into parts of central Illinois. Minor visby reductions
down to 7-8 miles have been noted as far south as Lincoln and
Champaign: however, lower visbys of 3-5 miles remain focused
further north in the Chicago metro area. Based on boundary layer
flow and latest RAP smoke forecast, think the thickest smoke will
skirt the KILX CWA to the N/NE this evening. FEW-SCT diurnal
clouds will dissipate over the next hour or two, with hazy skies
expected to prevail through the night. Overnight lows will drop
into the lower to middle 60s.
Barnes
&&
.DISCUSSION...
Issued at 233 PM CDT Mon Jun 26 2023
------------------------- [Key Messages] -------------------------
1. Hazy skies from Canadian wildfire smoke Tuesday.
2. Hot and humid Thursday-Friday. Uncertainty in high temperatures
is vast due to potential for thunderstorms.
3. 30-50% chances for thunderstorms Thursday through Saturday. Some
of those storms could be severe.
4. Only 5-10% chances for sufficient (2 inches or more) rainfall to
relieve the drought, but thunderstorms could bring beneficial
(0.5 inch+) amounts to some areas.
-------------------------- [Discussion] --------------------------
The deterministic models are in agreement the upper trough will
meander east into the Northeast over the next 36 or so hours, while
a ridge builds into the Plains. 850mb temperatures will thus be on
the increase as flow at 925mb is forecast, at least by the GFS and
ECMWF, to finally veer from northerly to southerly in central
Illinois late tomorrow night or early Wednesday morning. With
fewer clouds around to mitigate solar heating, tomorrow will be
several degrees warmer than today, though temps could get knocked
down a degree or so by haze which the HRRR and RAP agree will be
moving into our area from the north overnight. Surface
observations of reduced visibility associated with low level
smoke, together with the RAP`s forecast for 20-30 ug/m^2 of near
surface smoke, also suggest we could have some true haze around in
the morning-early afternoon, though air quality concerns are not
high for us at this time with Illinois EPA`s forecast for moderate
values tomorrow.
Wednesday, under the WAA regime, we`ll have a better chance for
getting into the upper 80s, at least west of I-55. The NAM and RAP
suggest we could even get some precip into the area as early as
Wednesday morning, but our current thinking is that this is too
aggressive and the air mass will take more time to sufficiently
moisten for precip; in fact, the NAMNest suggests that dewpoints
will have fallen into the mid 40s to low 50s by late Tuesday
night, which is not exactly ideal for convection. By Thursday
morning, however, the GFS and ECMWF each suggest dewpoints will
have climbed into the upper 60s/low 70s, which will contribute to
at least a few thousand J/kg of SBCAPE by Thursday afternoon.
Given increasing elevated instability late Wednesday night, one
can`t rule out a couple storms which, given increasingly steep mid
level lapse rates, could produce some hail. However, the better
chance for storms (should a trigger manage to break the cap) will
be Thursday afternoon, by which time NBM suggests a ~60% (25%)
chance for SBCAPE over 2000 (3000) J/kg. The GFS is even more
aggressive and has upwards of 4000 J/kg of MUCAPE across our
southern CWA Thursday afternoon, around the time that the
deterministic ECMWF shows a swath of lightning activity > 1500
flashes/km^2 crossing central/eastern Illinois from northwest to
southeast, and various deterministic models suggest a wave of
either west to east or northwest to southeast-moving storms will
cross some portion of the state. It`s a low-probability but
potentially high impact scenario, so I don`t want to raise any
alarms...However, it`s worth noting that with (1) largely
unidirectional shear, (2) the instability axis near/across our
area, and (3) forecast DCAPE upwards of 1200 J/kg, this
environment would be conducive to a forward propagating, damaging
wind-producing MCS event somewhere across the Midwest/Ohio Valley
Thursday/Thursday night. The odds of our CWA taking a direct hit
are not particularly high, but we`ll need to keep an eye on
forecast trends over the next couple days. At this point, we`re
not outlooked by SPC for day 4 given predictability issues, but
the CSU MLP has a 15% contour across our west (mainly for hail)
Wednesday (for the late night period) and across our south both
Thursday and Friday. The deterministic models each suggest waves
of scattered storms will be possible thereafter through Saturday,
with large uncertainty in the timing of the quasistationary/cold
front`s passage which should mark the end of our thunderstorm
potential.
NBM suggests 70-80% probabilities that we`ll see some rain between
Wednesday night and late Saturday, and 50-60% chances for more
than a half inch of precipitation, however its probabilities have
been running a little high lately given our dry soil`s ability to
modify the boundary layer air mass. At this point, we just don`t
want to advertise precip chances too much to give more (possibly
false) hope to those in agriculture and other occupations where
rain is disparately needed.
One forecast parameter which is also critical but is unfortunately
inseparable from precip/convection is temperature. With dewpoint
values forecast to eventually make it into the 70s, low temperatures
will not be particularly comfortable Thursday and perhaps (depending
on timing of the cold front) Friday nights. However, high
temperatures are much more uncertain given the potential for
downdrafts to quickly chill the boundary layer near thunderstorms,
the location of which is impossible to determine at this juncture.
Given 56% (23%) of the Low Resolution Ensemble Forecast (LREF)
system has 850mb temps above 22 (24) degC in Springfield by
Thursday, the potential exists for heat; NBM even suggests 35-50%
chances for surface temps to reach/exceed 95 degF both Thursday and
Friday with the highest chances south of I-72 on Friday.
By the start of next work week, cluster analysis suggests the ridge
across the Great Plains and South will begin to flatten and 500hPa
heights will decrease across the Midwest/Ohio Valley for zonal or
northwest flow and milder temperatures, though spread among the LREF
ensemble members suggests considerable uncertainty in temperatures
and precipitation potential. Should the front, which the
deterministic models suggest will stall somewhere to our south
Sunday-Monday, begin to lift back northward, we could have renewed
precip chances and warmer weather. However, we won`t really be able
to nail that down until we get a better handle on the next couple
days.
Bumgardner
&&
.AVIATION... (For the 00z TAFs through 00z Tuesday Evening)
Issued at 637 PM CDT Mon Jun 26 2023
Northwesterly winds will continue to gust 15-25kt for the next
hour or two before the gusts subside after dark. Smoke from
Canadian wildfires has mixed to the surface across northern
Illinois, with 23z/6pm obs showing widespread visbys of 3-7 miles.
Given boundary layer flow and latest RAP smoke forecast, think the
bulk of the lowest visbys will graze the KILX CWA to the north
later this evening. Have dropped visbys down to around 6 miles at
both KBMI and KCMI for a time, with visbys improving after
06z-08z. Will need to keep an eye on future smoke forecasts, as
hazy skies are expected on Tuesday...with the potential for some
additional visby reductions as smoke once again tries to mix to
the surface. Confidence is too low to include in the forecast at
this time. Winds on Tuesday will veer to northerly and will not be
as strong as they were today...generally from 10-15kt. SCT
diurnal cloud cover at around 3500ft is expected from late morning
through the afternoon.
Barnes
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
...Updated Aviation Forecast Discussion...
.DISCUSSION...
Issued at 235 PM CDT Mon Jun 26 2023
Key Messages:
- Smoke/haze will continue to affect the region through Tuesday.
- Small chance for showers and thunderstorms Tuesday.
- Hot Wednesday with heat indices approaching 105 south of I-80.
- Marginal Risk for severe storms Wednesday.
Tonight through Tuesday...
High pressure built into the region today, keeping skies mostly
clear and temperatures warm. By 2 PM, temperatures had reached the
low to mid 80, with a few 70s sprinkled across our northeastern
counties, where cloud cover lingered. Winds were lighter today,
still out of the northwest, but only gusting up to around 20 to 30
mph. Smoke from Canadian wildfires kept skies hazy this afternoon,
as it was pulled south by a low pressure system moving through the
Great Lakes. Smoke will likely linger over the region tomorrow and
into Wednesday as well, if the HRRR smoke fields verify.
A shortwave will traverse the upper ridge over the nation`s
midsection tonight and Tuesday, sparking the development of an MCS
over southwest SD which will move into northern NE tonight. This
convection will likely begin to degrade as it approaches our
forecast area, however, the remnants will bring us a chance for a
few scattered showers and storms throughout the day, Tuesday.
Wednesday...
Another shortwave disturbance will work to flatten the upper ridge
Wednesday, while dragging a weak cold front along the surface.
Plenty of instability (1200-2500 J/kg) and deep layer shear (40-50
kts) will be available, however the capping inversion could be too
strong to overcome. A Marginal Risk remains in effect for parts of
eastern Nebraska and all of western Iowa for Wednesday afternoon
and evening.
Heat will also be an issue Wednesday as afternoon highs creep into
the upper 90s. Humidities will increase into the middle of the week
as well, bringing heat indicies into the low 100s along and south of
I-80.
Thursday and Beyond...
A better chance for more widespread thunderstorms looks possible
Thursday night through Friday as a northern Plains trough moves
toward the region, pushing a cold front through the area. A few
strong to severe storms could be possible, however timing and
location is still questionable. Temperatures will gradually cool
back into the low to mid 80s Saturday. Sunday and Monday look mostly
dry with northwesterly flow aloft.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 614 PM CDT Mon Jun 26 2023
VFR conditions through the period. While there is some haze out
there, don`t think it will impact visibility significantly. And
there will also be a 30 percent chance of showers at KOFK 12-16z.
Otherwise, winds less than 12 knots at TAF issuance, but become
southeast and increase to 12 to 22 knots by 16-17z.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...None.
IA...None.
&&
$$
DISCUSSION...KG
AVIATION...DeWald
Area Forecast Discussion
National Weather Service Shreveport LA
1001 PM CDT Mon Jun 26 2023
...New UPDATE...
.UPDATE...
Issued at 947 PM CDT Mon Jun 26 2023
Some of the hi-res short range CAMs continue to suggest the
possibility for some isolated convective initiation across
southeastern Oklahoma and southwestern Arkansas during the
overnight hours, likely after 07Z. The 01Z run of the HRRR depicts
a narrow band of storms drifting south and east along a similar
axis as seen yesterday evening across southern to southeastern
Arkansas. To that end, have elected to continue the slight PoPs as
issued in the afternoon package.
However, this is far from a slam dunk scenario, with considerable
spread in position and intensity. FV3 Hi-Res suggests more
aggressive initiation, but located entirely to our east during
the pre-dawn hours and WRF-ARW2 depicts little more than a few
showers.
Given the unstable environment sampled in this evening`s 00Z
flight from KSHV, with 4000+ J/kg of SBCAPE, some storms becoming
severe cannot be ruled out. Large hail remains a possibility, as
well as damaging winds, particularly in decaying storms, as
suggested by 1360 J/kg of DCAPE.
The forecast package otherwise remains on track, with lows
dropping into the mid to upper 70s by the 12Z hour.
/26/
&&
.SHORT TERM...
(This evening through Tuesday Night)
Issued at 228 PM CDT Mon Jun 26 2023
Another sloppy short-term is in store for the Four-States region,
including continued heat products, and another possible round of
severe weather overnight tonight. The region remains on the fringe
of the high-pressure building off to our west, high pressure that
won`t shift overhead until the long-term. This will allow for our
northern zones to remain under the NW flow regime that we`ve been
stuck in the past two and a half weeks. Given this regime, and a
decaying boundary along the Red River, thunderstorms may develop
into the evening and overnight hours and move SE. While widespread
severe weather is not anticipated at this time, a few of these
thunderstorms could produce large hail given decent lapse rates.
Beyond tomorrow, that strong upper-level ridge should finally
begin to take hold of the region. Overnight lows will barely fall
into the upper-70s, with widespread triple-digits on the horizon.
As such, the Heat Advisory has been extended over the course of
the entire short-term, now expiring at 7AM Wednesday.
/44/
&&
.LONG TERM...
(Wednesday through next Sunday)
Issued at 228 PM CDT Mon Jun 26 2023
Much of the long term period will be characterized with the hottest
temps observed so far this year, with at least several days (if not
more) of triple digit heat expected for much of not all of the
region. This will occur as the typical summertime death ridge begins
to expand E over the region into the Lower MS Valley from the Srn
Plains, and linger through at least the first half of the upcoming
weekend. To add insult to injury, WSWrly low level winds will add to
the rapid daily warmup, while also keeping the Gulf shut off, thus
limiting any cu field to deter heating. In fact, some locales will
near record highs, and despite the mostly clear sky expected
overnight each night, limited cooling is expected, with min temps
not falling much below 80 degrees especially as SSW winds keep the
air mixed. Thus, some record high mins will be possible as well.
Some mixing of dewpoints is expected each afternoon, with resultant
heat indices in the higher end of the Heat Advisory criteria. There
may be some instances where Excessive Heat Warnings may be needed
for portions of the region, but this will be determined on a daily
basis.
The upper level ridge remains progged to gradually break down
Saturday afternoon and night, in response to upper troughing that
will swing SE from the Great Lakes SW into the Ozarks. This trough
will also help to reinforce a weak sfc front S into OK/NW AR
Saturday night, which may help focus convection as it drifts S by
Sunday. The GFS remains more bullish than the ECMWF with the
breakdown of the ridge, and thus more bullish with scattered
convection mainly N of the Highway 82 corridor of NE TX/Srn AR. Have
not deviated much from the NBM pops Saturday night through Monday,
with the potential uptick in isolated to widely scattered convection
especially as the ridge continues to flatten. Should be able to ease
off of the triple digit heat by Sunday, although above normal temps
will continue, with the potential for Heat Advisories even extending
for at least portions of the region through the end of the long term
period.
15
&&
.AVIATION...
(00Z TAFS)
Issued at 611 PM CDT Mon Jun 26 2023
For the 27/00Z TAFs, VFR conditions will continue to prevail in
the near term, with an enduring Cu field across northern airspace
and SKC elsewhere. Vis may drop to MVFR conditions after 27/10Z
before improving quickly after 27/13Z. Short range hires guidance
suggests the development of storms across southeast Oklahoma and
southern Arkansas in the late overnight hours but not with enough
coverage or confidence to prevail in FM groups at this time. A
clearer picture should exist by the preparation of the 27/06Z
TAFs.
/26/
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 79 100 80 101 / 10 10 0 0
MLU 76 96 78 101 / 30 30 0 0
DEQ 77 96 75 100 / 30 20 0 0
TXK 78 100 78 103 / 20 10 0 0
ELD 76 95 76 100 / 30 30 0 0
TYR 77 100 78 101 / 0 0 0 0
GGG 78 99 78 101 / 0 0 0 0
LFK 77 99 77 100 / 0 0 0 0
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...Heat Advisory until 7 AM CDT Wednesday for ARZ050-051-059>061-
070>073.
LA...Heat Advisory until 7 AM CDT Wednesday for LAZ001>006-010>014-
017>022.
OK...Heat Advisory until 7 AM CDT Wednesday for OKZ077.
TX...Heat Advisory until 7 AM CDT Wednesday for TXZ096-097-108>112-
124>126-136>138-149>153-165>167.
&&
$$
SHORT TERM...26
LONG TERM....15
AVIATION...26
Area Forecast Discussion
National Weather Service Topeka KS
550 PM CDT Mon Jun 26 2023
...AVIATION UPDATE...
.DISCUSSION...
Issued at 228 PM CDT Mon Jun 26 2023
Forecast summary:
- Heat builds by mid-week generally between 105-110 degree heat
index values.
- Spotty rain chances generally during the nocturnal periods and
early morning especially Tue-Wed mornings.
- Best rain chances of the week appear to be Friday night time frame.
Forecast thoughts:
The upper level pattern across the CONUS features a deep closed low
and trough over the Great Lakes region transitioning to a low
amplitude but broad ridge with axis through the central Plains.
Another trough is positioned over the western CONUS through the
Pacific northwest into northern California region. Southwest flow
results from the Desert Southwest into the central Rockies. With a
surface ridge in control at the surface across the forecast region
and dewpoints into the middle 50s, a perfect day remains ongoing
across the area. This continues into tomorrow with return flow
becoming established which will steadily increase Gulf moisture back
to the region.
Weak isentropic ascent with return moisture to the region into
Tuesday morning may help spotty showers or a thunderstorm develop
early then dissipate with mostly Sunny conditions and temperatures
rising to around 90 with low overall humidity as dewpoints should be
slow to increase.
The near term challenges for the week appear to be into the early
Wednesday period whether or not an MCS moves into the area from
western Kansas. This would act to provide an increase in moisture to
the region and if the cloud shield does clear the area by mid to
late morning temperatures could rise to around 100 along and south
of I-70. Additionally, better return flow under the ridge aloft
should be in place, so dewpoints look to rise to the mid to upper
60s across much of the area. This will result in heat index values
generally from 101-109 degrees across the area. Overall, heights
rising to around 591 dam across the southern parts of the area give
reason for concern that heat headlines may be required at least Wed-
Thurs.
Friday could still see elevated heat levels before an upper level
trough digs into the area and brings increased rain and storm
chances for the late day and overnight period Friday with a modified
cold front bringing relief to the area for the July 4th weekend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday)
Issued at 550 PM CDT Mon Jun 26 2023
Dry air within the surface ridge is expected to keep P6SM
SKC conditions in place tonight. There are signs of some mid level
moisture advection developing across central KS towards 12Z. The
HRRR has been trending with some elevated SHRA moving east through
mid morning. Looks like the potential for this holding together
and making it to MHK is around 20 percent. So will hold off on
including precip in the forecast for now, but will show mid level
AC increasing through the morning.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
DISCUSSION...Drake
AVIATION...Wolters