Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 07/25/23
Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
155 PM AKDT Mon Jul 24 2023
.SYNOPSIS...
Active weather continues over the next few days for the Eastern,
Central and Western Interior. Isolated strong to severe storms are
possible this afternoon and evening. Thunderstorm activity
decreases tomorrow, but still a few strong storms are possible in
the Central and Eastern Interior. Well above average and near
record temperatures are expected to persist through at least
Thursday. We are also observing smoke in the region through
tomorrow.
&&
.DISCUSSION...
Upper Levels and Analysis...
Upper high remains centered over the Central and Eastern Interior
into Yukon. Low pressure areas aloft in the Bering Sea and over
the Northwestern Territories will squeeze the high over the
Interior. However, the low pressure area to the west will slowly
push the ridge to the east over the next few days. At the surface,
weak surface troughing persist across the Interior and combined
with a weak shortwave riding north along the western portions of
the upper level ridge will help initiate storms this afternoon
and evening as well as tomorrow afternoon and evening.
Model Discussion...
The 12Z run of models today starts with very good agreement
with observations and between models. There are just minor
differences in the short term, but nothing significant. Model
spread begins in the long term with a more progressive GFS on
Friday. There are also disagreements with the strength of the
upper low in Siberia during the weekend. The ECMWF and Canadian
continue to have better agreement with each other through early
next week.
Central and Eastern Interior...
The main story for the Central and Eastern Interior will be heat
and thunderstorms. Afternoon highs continue to be hot with
temperatures ranging from the mid-80s to the lower 90s. We should
still be able to get a few 90s through tomorrow, but then
probabilities of 90 degree weather drop out by Thursday. It will
still be warm with most of the lowlands in the upper 70s and 80s
towards the end of the work week. Smoke continues to invade the
region from Canada, but the HRRR indicates that near surface smoke
should be leaving the area on Tuesday evening. Scattered
thunderstorms are expected across portions of the area. There is
plenty of instability as observed with the CAPE and Lifted index
values, but shear is very lack-luster as we remain under the
ridge. Isolated storms may be able to become strong to severe, but
they may not last long due to the subsidence aloft. The main
hazard with any storm continues to be frequent lightning, gusty
and erratic winds, hail and periods of heavy rain. Thunderstorm
activity tomorrow will be less active, and even less active by
Wednesday.
West Coast and Western Interior...
Meridional flow continues over the West Coast bringing periods of
rain over the next few days as the upper low over the Bering Sea
approaches the region. The Western Interior will see isolated to
scattered storms through tomorrow, especially in the eastern
portions of the region. Storms become isolated on Wednesday, but
periods of rain will be possible through the end of the work week.
North Slope and Brooks Range...
Near record warm temperatures continue over the next few days in
the North Slope as the upper high remains in the vicinity
extending into the Arctic Coast. Temperatures will be in the 70s
with locations near the Brooks Range reaching the lower 80s.
Isolated showers and thunderstorms are expected in across most of
the area. Cooler weather is expected to return towards the end of
the work week. Areas of fog continue to be possible near the
coast during the morning hours.
Extended Forecast Days 4-7...
Uncertainty continues in the extended forecast as models start to
diverge by weeks end with the Canadian and ECMWF having similar
solutions with shortwave troughs becoming a closed low and
descending into the Gulf of Alaska. Meanwhile, the GFS develops a
secondary low that slowly travels over Central AK. The EC and
Canadian have the upper ridge reestablished by Sunday near the
Arctic Coast. Therefore, warm temperatures would continue over the
Interior if this pans out, but the GFS indicates cooler
temperatures. Currently, supporting the EC/Canadian deterministic
combo and their ensemble means with the warmer temperatures.
Coastal Hazard Potential Days 3 and 4...None.
&&
.FIRE WEATHER...
Isolated to scattered storms are the main concern in the near
term through Wednesday. These storms bring frequent lightning and
gusty and erratic winds. The lightning could result in multiple
new fire starts over zones 220, 221 and 223. There is a red flag
warning out for today to account for the risk of new fires in the
area due to lightning. A new Red Flag Warning was issued for
zones 220 and 221 (areas east of Tanana) for the same reasons on
Tuesday. Although storm activity is expected to be weaker. We are
still expecting storms in the Interior through the rest of the
week, but coverage and strength will be less. As the upper high
slowly tracks east, we get more moisture from the west lowering
the fire weather risk. Winds will be relatively light through the
foreseeable future with a few exceptions. Winds around 10-15 mph
from the east are expected along the Yukon Flats on this evening.
Plus, westerly winds around 10-15 mph along the Tanana Valley on
Tuesday.
&&
.HYDROLOGY...
High flows continue over the Tanana River. Locally heavy rain due
to storms over the next few days could result in quick rises over
rivers and streams, especially for the Tanana River. Anomalously
high snow levels generally above 10-11 kft are expected over the
next two days. Glacial melt and melting of high elevation snow is
highly likely. Therefore, expect a rise of rivers and streams
near the Alaska Range through the week. These high flows will
cause issues along low lying areas, plus there will be an increase
of debris along rivers and streams.
&&
.AFG WATCHES/WARNINGS/ADVISORIES...
AK...Red Flag Warning for AKZ220-221-223.
Red Flag Warning for AKZ220-221.
PK...Small Craft Advisory for PKZ801-850.
Small Craft Advisory for PKZ815-860-861.
Small Craft Advisory for PKZ816-851.
Small Craft Advisory for PKZ817.
Small Craft Advisory for PKZ854.
&&
$$
Area Forecast Discussion
National Weather Service La Crosse WI
700 PM CDT Mon Jul 24 2023
.DISCUSSION...(Tonight through Monday)
Issued at 230 PM CDT Mon Jul 24 2023
Key Messages:
- Summer heat kicks in this week, highlighted by highs in the mid
90s for Wed-Fri. Heat indices around 100 at times for a few
locations. Thu looks like the hottest day.
- Sporadic shower/storm chances this week...with late Tue night/the
weekend currently harboring the higher chances.
* ISOLATED CONVECTION INTO THE EVENING (20-30%)
A bit of shortwave energy along with a sfc boundary was working on
about 1500 J/kg MUCAPE (via the RAP) over north-central
MN...developing billowy cu and (very) isolated convection. Most CAMS
continue to develop showers/storms as the day wears on, generally
very spotty to scattered, east and southeastward - with more focus
along the west-east lying sfc front across northern WI. CAMS tend to
want to weaken the convection as it nears the local area, moving
into drier/not as unstable environment. RAP looks to be
mixing/drying out too much...so could be under doing the amount of
instability available over western WI. For now will roll with 20-30%
chances into the evening, mostly north of I-90 and along/east of the
Mississippi river.
Overnight, the RAP/HRRR hint that a small area of convection could
get going north of I-94. Lingering pool of instability and the
frontal boundary look to be the culprits, with a suggestion that
weak low level moisture transport could also play a role. Differing
opinions between the CAMS and the weak forcing lower confidence in
this transpiring. Will keep out of the forecast for now and monitor
model/observational trends and adjust forecast if needed.
* HOT WEEK...but more seasonable weekend on tap
No change with model expectations in the upper level flow for the
week - upper level ridging builds in from the plains, but continues
to show more flattening compared to the amplification it had over
the west coast last week. Main heat dome holds to the west as a
result. The long range guidance then continues to favor
reestablishing the ridge back westward for the weekend, placing the
upper mississippi river under northwest flow and relatively cooler,
more seasonable air.
The GFS continues to be ignored for the most part...suffering from
overhyping of temps - too much mixing/super adiabatic profiles.
Numerical guidance via the GFS loves +100 degrees Wed/Thu for KLSE
while the EC is 10 degrees cooler. 925 mb temps in the NAM/EC top
out +27/28 for Thu afternoon - very warm/hot, but not that far
outside "the norm" for late July. EPS guidance places approx 75% of
its members at 90+ degrees Thu/Fri...a slight shift later into the
week for its favored warmest days. The GEFS, while too hot, still
suggests the warmest days would be Wed/Thu.
Rain/associated clouds could temper the heat a bit as we move
through the week - but timing/location/higher chances remains
uncertain - and won`t try to nitpick temps down for any potential
dousing of rain this many days out.
Will continue to hold with the model blend for temps...keeping it
very warm, but well below any record/near record values. Heat
indices will hover around 100 for a few locations in the Wed-Fri
time period - with Thu currently shaping up to be the hottest. Can`t
rule out the need for heat related head lines - specifically for Thu
where more widespread 100+ heat indices could be reached.
* RAIN CHANCES THIS WEEK - Late Tue Night, Fri-weekend holding most
of the chances
Various ripples in the upper level flow are progged to work from
across the plains to the upper/middle mississippi river valleys this
week. Long range guidance spin a shortwave across the region late
Tue night-Wed and gets a bit more active as we move into the weekend.
Low predictability at this juncture with location and there could be
saturation issues. Instability on the lower end and not much for
potential wind shear, at least until the weekend. Won`t stray from
model blend for chances - hovering in the 20-40% range. Expect more
refinement (chances/areal extent) as we move through the week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 655 PM CDT Mon Jul 24 2023
VFR conditions through around 09Z with some lingering mid and high
clouds due to the convective debris from storms earlier this
afternoon. There are hints at isolated storms trying to
develop near KLSE overnight, however only a couple models show
this. Forcing is weak, thus confidence is too low to include in
the forecast. Attention then turns to the fog potential. A low
level inversion is forecast to set up with low level moisture
trapped in the river valley. Models vary on how light the winds
will be; not quite as light as this morning through 1-2K ft, but
light enough to mention patchy fog and may include LIFR vsbys for
a short time between 11 and 13Z.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
DISCUSSION...Rieck
AVIATION...Zapotocny
AREA FORECAST DISCUSSION
National Weather Service Bismarck ND
947 PM CDT Mon Jul 24 2023
.UPDATE...
Issued at 938 PM CDT Mon Jul 24 2023
With this update pops were sped up a bit Tuesday morning to bring
slight chances into the west by around 06Z, based on new 00Z CAMs.
No current changes in thinking regarding convective uncertainties
as described in the earlier AFD, will let the full suite of 00Z
high-res models and ensembles come in before considering adjusting
any messaging.
UPDATE Issued at 642 PM CDT Mon Jul 24 2023
A quiet but hot evening continues as 23Z temperatures range from
the mid 80s to the upper 90s across western and central North
Dakota. No changes needed with this update.
&&
.SHORT TERM...(This Evening through Tuesday night)
Issued at 207 PM CDT Mon Jul 24 2023
Hot temperatures and thunderstorm chances highlight the short term
forecast today.
Currently, skies were mostly sunny with mainly thin high clouds
pushing from west to east. Temperatures ranged from 80 around the
Turtle Mountains, to the upper 90s far west. A few locations in
the far west could top out at or above 100 degrees.
For tonight, expect quiet and warm conditions this evening. Clouds
will begin to increase from west to east late this evening and
overnight. High based showers or isolated thunderstorms are
possible as early as late this evening in the far west, but mainly
after midnight. Lows will range from the mid 60s to lower 70s.
On Tuesday, elevated morning showers and isolated thunderstorms
will continue to propagate east into central ND within an area of
persistent warm advection. Meanwhile, a mid-upper level shortwave
trough makes its way through the mean upper ridge over western ND.
By Tuesday afternoon/evening the threat for strong to severe
storms will increase across central and eastern North Dakota.
While the overall severe threat does increase, there are some
possible scenarios for failure. However, with RAP forecast ML
CAPES of 2000-3000 J/KG over central ND late Tuesday afternoon
into Tuesday evening, the previous forecast of 70 mph winds and
golfball sized hail for the main hazards still seems reasonable
and we will message these.
There is a pretty strong cap in place Tuesday, so that is one
issue there for potential failure. With instability this strong,
any storms that would develop would probably quickly become
severe. As mentioned earlier, persistent warm advection would help
this cause. However it does look like a pretty thick layer of mid
and high clouds spreading across the forecast area Tuesday. Thick
enough that the forecast high temperatures have backed off a bit
over the south central portion of the state Tuesday. The added
clouds and any shower activity could limit heating and dampen the
severe threat a bit. Also, the cold front that is moving through
western and into central ND Tuesday, looks to stall over central
ND until a stronger northern stream wave eventually forces the
front eastward on Wednesday. We will still have moisture pooling
and low level convergence along the front, and some ascent from
the diurnal heating. The question is: with the added forcing for
ascent from the shortwave, will this be enough to initiate
convection over central ND. If so, initially we could see some
high based supercells. With a well mixed boundary layer and steep
lapse rates strong winds would be possible. A mid afternoon NAM
forecast shows an elongated hodograph with 40 knots of effective
shear, indicating large hail also being a threat. Thus the reason
for sticking with the previous severe weather hazards. Some
guidance suggests that convection could develop into an MCS.
Perhaps not until its beyond the JRV, but other guidance suggest
the potential for it to happen earlier. Whether it`s in the JRV,
or not, the hazardous wind threat would increase.
Convection would probably be out of the forecast area by late
evening, with a warm and muggy overnight for central ND.
.LONG TERM...(Wednesday through Monday) Issued at 207 PM CDT Mon
Jul 24 2023
One more hot day to begin the long term period, then seasonable
temperatures and daily chances for thunderstorms.
On Wednesday the upper level ridge and thermal trough get pushed
into the eastern Dakotas, while the aforementioned northern stream
trough tracks across the southern Canada Prairie Provinces, with
its attendant surface cold front draped across central North
Dakota. This could make for another day of strong to severe storms
over the eastern Dakotas, and potentially back into portions of
central ND, depending on the timing of the cold front. Once any
convection clears the area on Wednesday, cooler temperatures will
return for a while.
Thursday and through the weekend, NBM ensemble temperature spread
is rather high so will stick close to the given guidance which is
generally in the 80s. A broad quasi-zonal upper level flow will
provide daily chances of thunderstorms. Moderate to strong bulk
shear should be available so depending on the the given the
temperature and moisture profile each day, strong to severe storms
could be possible. However, with the broad flow the
predictability in timing and placement will remain low. NBM pops
reflect this with a broadbrush of 20-30 pops through much of the
period.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday Evening)
Issued at 642 PM CDT Mon Jul 24 2023
Quiet evening with a southeast breeze will give way to isolated to
scattered showers and isolated thunderstorms in western North
Dakota early Tuesday morning. Coverage within guidance is fairly
inconsistent at any TAF site, so left mention of shower out for
now. Showers and thunderstorms move into central to eastern North
Dakota after 15Z. Flow will shift west at the western TAF sites
Tuesday morning.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...AE
SHORT TERM...TWH
LONG TERM...TWH
AVIATION...AE
Area Forecast Discussion
National Weather Service Cheyenne WY
922 PM MDT Mon Jul 24 2023
.UPDATE...
Issued at 914 PM MDT Mon Jul 24 2023
A line of thunderstorms will continue to march east through
eastern Niobrara and eastern Goshen counties. These storms are
moving through an environment with decent -10 to -30 degC capes
around 500j/kg and surface based cape values between
2000-25000j/kg along with 0-6km shear around 30 to 35kts. Would
not be surprised to see these storms continue to push through the
northern panhandle through midnight and produce some gusty winds
to 50 to 60 mph along with nickel size hail. The remainder of the
area, should clear out with only a possibility of a few light
showers.
&&
.SHORT TERM...(This afternoon through Tuesday night)
Issued at 205 PM MDT Mon Jul 24 2023
Main forecast concerns during the short term period with be
scattered showers and thunderstorms this afternoon and Tuesday
afternoon with the chance for occasional lightning and gusty
winds.
Latest GOES WV imagery shows an upper level high centered along
the CO/NM border with monsoonal moisture wrapping around into our
area. This has led to initial cumulus development over the South
Laramie Range and northern CO Front Range with upwards of ~500
J/kg of MLCAPE per the latest RAP analysis. Forecast soundings are
rather dry in the boundary layer with above average temperatures
today as the upper level ridge still remains over our area for
another day. With inverted-v profiles as the LCL extends above the
freezing level for most sites, could have gusty outflow winds from
storms and even weaker showers. Most will be around 40 mph, but
cannot rule out localized outflow winds gusting 50-60 mph similar
to what occurred near KEAN yesterday. Main area to watch will be
along the I-80 corridor from Laramie through Kimball now until 7
PM MDT before storms dissipate in addition to farther north in
east-central WY closer to a passing shortwave approaching.
Looking ahead to Tuesday, warm but slightly cooler temperatures
are expected as the upper level high begins to break down over our
area. Afternoon highs will still be in the 80s and 90s across much
of the area. Showers and thunderstorms are expected once again
with gusty winds, but should mostly be confined to the I-80
corridor based on the timing of the shortwave passage. CAMs
support scattered storm coverage in these areas as well as in the
northern NE Panhandle near the sfc low. Instability will be rather
limited behind the shortwave with decreasing mid-level lapse
rates, so will need to continue monitoring the timing of this
system. Additionally, will see gusty west to northwest winds
throughout the day with the shortwave passage, especially along
the higher terrain and wind-prone locations.
.LONG TERM...(Wednesday through Sunday)
Issued at 205 PM MDT Mon Jul 24 2023
Not much change in the long-term forecast period in today`s 12z
guidance. The broad southwestern CONUS ridge will persist from
Wednesday through early weekend before to break down
slightly under influence from a weak trough in the northwest.
Ultimately however, only minor differences in the day-to-day
forecast will be noticeable over this timeframe.
The hottest weather over the long-term period will come on Wednesday
and Thursday. 500mb heights as well as 700mb temperatures will peak
during this time as the dome of the southwestern ridge slides under
Wyoming through the central and southern Rockies. As has been the
case over the past several days, and will be the case through the
short-term, faster flow aloft along the northern periphery of the
ridge will result in at least some marginal wind shear, with PWAT
values near seasonal averages on the north end of the ridge as well.
The result will be a continuation of general afternoon showers and
thunderstorms, developing first over the higher terrain and
transitioning eastward in the later afternoon hours. These
precipitation chances will help to at least temper the afternoon heat
somewhat from what the upper-end of this pattern could produce.
As a shortwave trough over the Pacific Northwest impinges on the
large ridge later in the week, expect a flattening trend to the
overall upper-air pattern. This forecast is particularly favored by
the GFS/GEFS ensemble mean, but is in slight contrast to prior
forecast trends and the current ECMWF, which shows the potential for
a deamplification of the ridge into the weekend. Shower and
thunderstorm chances will likely increase slightly each day with
temperatures dropping a degree or three as well each day through the
weekend if the GFS were to come to fruition. The ECMWF/EPS remains
warmer for now. Given the differences in model guidance, forecast
confidence is only low to moderate in terms of the potential for
well-above average temperatures and precipitation chances. Overall,
have continued the trend of nudging precip chances upward from model
guidance blends as guidance has not handled the duration of mountain
storms lingering into the evening hours in the high plains. Have
also nudged temperatures upward slightly in the long-term as well.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 513 PM MDT Mon Jul 24 2023
Wyoming Terminals... Isolated showers and some thunderstorms are
present across southeast Wyoming. All terminals are VFR and
expected to remain VFR for the 00Z TAF period. Ceilings around
10000 ft AGL will remain at KCYS and KLAR for the next 3 to 4
hours. Gusty winds return tomorrow afternoon with all terminals
gusting between 25 and 30 kts. KRWL will have the highest gusts
around 30 kts.
Nebraska Terminals... Isolated showers and thunderstorms in
southeast Wyoming will move into western Nebraska this evening and
potentially impact Nebraska terminals. VFR conditions at all
terminals are expected to last through the 00Z TAF period, but if
a thunderstorm moves directly over a terminal visibility may drop
into the MVFR category briefly. Most storms clear by midnight with
gusty winds expected tomorrow afternoon. Winds will gust to 25
kts at all terminals.
&&
.FIRE WEATHER...
Issued at 205 PM MDT Mon Jul 24 2023
Minimal fire weather concerns despite hot weather continuing
today with dry conditions. Afternoon showers and thunderstorms
expected, but wetting rainfall is unlikely. Expecting west to
northwest winds gusting 25 mph (35 mph in the higher terrain)
Tuesday afternoon with RH values in the 20s. Will continue to see
a monsoonal moisture push continue through the week with daily
chances for showers and thunderstorms.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...None.
&&
$$
UPDATE...REC
SHORT TERM...MB
LONG TERM...MAC
AVIATION...AM
FIRE WEATHER...MB
Area Forecast Discussion
National Weather Service Duluth MN
943 PM CDT Mon Jul 24 2023
.DISCUSSION...(This evening through Sunday)
Issued at 447 PM CDT Mon Jul 24 2023
Summary: Very warm and humid conditions are ahead for the middle
part of the week before cooling closer to normal heading into the
weekend. Chances for showers and thunderstorms will persist
through much of the forecast period as well.
A cold front stretched from the Straits of Mackinac into northern
Wisconsin and central Minnesota this afternoon. A subtle shortwave
aloft was leading to isolated to scattered thunderstorm
development north of the front from the I-35 corridor into
northwestern Wisconsin behind the front with additional
development ahead of the front across central and southern
Minnesota. Latest SPC RAP analysis shows around 1000-2000 J/kg of
CAPE in the vicinity of current development with around 20 to 30
knots of effective shear. Storms have had trouble maintaining in
this environment with better shear offset to the south of the CWA.
Expecting this trend to continue over the next few hours despite
CAMs not showing this activity at all. Quiet conditions will then
be in place for the overnight hours with areas of smoke aloft.
A stronger shortwave will move through the northwest flow aloft
Tuesday afternoon into Tuesday night with better chances for
showers and thunderstorms expected over much of the CWA. CAMs
currently favor the late afternoon into the overnight hours.
Forcing looks much better with this shortwave with a convective
environment similar to the one currently in place. A few stronger
storms will be possible mainly north of Minnesota 210 Tuesday
afternoon and evening with gusty winds and large hail being the
primary threats.
Temperatures will then warm into the 80s to middle 90s for
Wednesday and Thursday with heat indicies approaching 100F in far
southern areas. Most of Wednesday currently looks dry during peak
heating before another shortwave moves through for the overnight
hours bringing chances of showers and storms. This activity may
linger into Thursday which may suppress highs in some areas and
prevent them from reaching into the 90s. Cooler temperatures are
then forecast to enter the region with readings closer to normal
for this point of the summer. These seasonable temperatures will
continue through the weekend along with chances for showers and
thunderstorms.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 645 PM CDT Mon Jul 24 2023
A few showers and thunderstorms continued from south of Pine City
east through parts of northwest Wisconsin. The trend has been for
these to become weaker and more sparse. However, CAM guidance
suggests additional development over east-central Minnesota in
northern Wisconsin will be possible for several more hours.
Hazy/smoky skies will continue with some spotty visibility
restrictions. Fog will also be possible again tonight and we have
a mention at KHYR but may need to expand.
Confidence is low on shower/storm coverage on Tuesday and we left
the mention out of most TAFs for now. Later updates will refine
the timing once guidance becomes clearer on how the showers/storms
will evolve.
&&
.MARINE...
Issued at 943 PM CDT Mon Jul 24 2023
Outside of a few gusts, winds will remain below 15 knots through
Wednesday. Fog will be possible tonight with it dense in spots.
The area from Port Wing through the Outer Apostle Islands to Saxon
Harbor has the best chance at seeing fog and a visibility that
drops to a mile or less. Conditions will be monitored for a
possible Dense Fog Advisory. The fog is expected to lift after 8
AM Tuesday.
Thunderstorms will be possible Tuesday evening into Wednesday.
Some of the storms could be strong.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 56 83 63 88 / 0 10 30 10
INL 55 85 63 85 / 10 50 60 20
BRD 62 93 67 95 / 10 10 40 10
HYR 58 89 66 92 / 20 10 50 20
ASX 55 86 65 89 / 0 10 40 20
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
LS...None.
&&
$$
DISCUSSION...BJH
AVIATION...Melde
MARINE...Melde
AREA FORECAST DISCUSSION
National Weather Service Kansas City/Pleasant Hill MO
621 PM CDT Mon Jul 24 2023
.Discussion...
Issued at 255 PM CDT MON JUL 24 2023
Key Messages:
- Hot and humid conditions likely this week but conditional on
whether or not we see MCS activity.
Afternoon water vapor imagery with 500mb heights overlaid show the
upper ridge has made little progress eastward. This keeps the area
in northwest flow, on the edge of more intense heat, and the warmer
air aloft that would more clearly inhibit convective development
like areas to our west. Afternoon visible satellite imagery shows a
high-based CU field arching back to the northwest, which may
delineate the edge of stronger inhibition and deeper drier air to
the west. Water vapor imagery also shows a shortwave rounding the
top of the ridge in eastern Montana and will quickly start to
dive southeast as it rounds the ridge. Isentropic plots again show
strong and focused ascent in the 310K and 315K levels over
eastern NE and KS into western MO. All this points to another shot
of convection tomorrow morning into the afternoon. The HRRR, NAM
Nest, ARW, and RAP all show some convection moving into the area
tomorrow morning, although timing and location varies. Given this,
have added some low chance PoPs and increased cloud cover for
tomorrow morning. Of course, this has a direct impact on
temperatures. My thought is that with the potential convection,
temperatures will be slightly cooler than what would otherwise be
possible, given the ambient thermal environment. This keeps us
below heat advisory levels again. With all that said, if
convection doesn`t materialize, or shifted further east, we`ll
very likely see highs in the mid to upper 90s with some areas
close to 100 with heat indices near or exceeding 105. So like
yesterday, will hold off on heat products with this forecast and
see if storms can develop so we can be more confident with any
heat advisory.
For later in the week, the ridge flattens out and expands eastward.
This favors increasing temperatures in the forecast area. However,
we remain in the nebulous area where any upstream convection could
still move southeast and influence the area. So like yesterday,
we`ll continue to message the potential for dangerous heat and take
the issuance of any heat related products day to day. Models
continue to show the upper ridge strengthening over the middle of
the country this weekend and into next week. This is a clearer
signal of dangerous heat with less potential for convection
interfering with that heat.
&&
.Aviation...(For the 00Z TAFS through 00Z Tuesday Evening)
Issued at 619 PM CDT MON JUL 24 2023
VFR conditions are currently expected through the period.
Increasing mid to high ceilings are likely through the overnight
and through Tuesday morning. There remains a signal that some RA
or TS is possible late morning through midday. At this time, given
low confidence, will continue to leave out a mention in the TAFs.
Winds will generally be out of the south and southwest through
the period, increasing tomorrow through the end of the period.
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
MO...NONE.
&&
$$
Discussion...CDB
Aviation...Kurtz
Area Forecast Discussion
National Weather Service Grand Forks ND
909 PM CDT Mon Jul 24 2023
.UPDATE...
Issued at 906 PM CDT Mon Jul 24 2023
Scattered t-storms are starting to form northwest of Portage la
Prairie Manitoba and this area is highlighted by more and more
CAMs indicating t-storm development continues near Lake Manitoba
and moves southeast thru the night and potentially affect far NW
Minnesota after midnight, more like after 08z. So did add pops
with latest NBM guidance which shows 30 pops for thunder from
neare Hallock east to Baudette late tonight.
UPDATE Issued at 625 PM CDT Mon Jul 24 2023
The probability for showers and thunderstorms in our CWA is
diminishing with each passing hour. Cumulus clouds have developed
within the Grant/Wilkin county area, but have lacked agitation
thanks to very limited forcing. Other than that, smoke will
continue to be the primary impact for the overnight hours.
&&
.SHORT TERM...(This evening through Tuesday night)
Issued at 228 PM CDT Mon Jul 24 2023
Key Messages:
-Smoke continues to move across the area thanks to a NW flow aloft.
Patchy areas in NW MN could see visibilities drop below 6 miles.
-Isolated chance (<20%) for showers or a stray thunderstorm later
this afternoon and evening. Conditional chance as no lifting
mechanism is available.
-Isolated to scattered strong to severe thunderstorms Tuesday
evening ahead of a frontal boundary. Strength of the boundary and
the capping of the atmosphere are uncertain. Large hail and damaging
winds will be the main treats.
-Heat begins to build today and into the middle portions of the
week.
Discussion:
During the early morning hours Tuesday brief patchy fog is possible
in lakes country as dew points remain in the 60s and overnight lows
reach the low to mid 60s. Dew point depressions near zero and light
and variable winds could create low lying patchy fog. Once sun rises
the chances would diminish.
Smoke continues to move across portions of the forecast area today
and linger into Tuesday. Majority of the smoke is aloft, but a few
areas in NW MN could see the smoke mix down to the surface reducing
visibility briefly to 4-6 miles. RAP and HRRR guidance has smoke
remaining across the area through tomorrow morning before winds
start to move the smoke further to the east. Higher level smoke
could linger longer into the afternoon on Tuesday.
Latest HI Res guidance has continued to diminish the chances for
isolated showers and storms this evening across west central MN.
With no lifting mechanism to initiate development chances for
development are <5%. This is not the case for tomorrow afternoon as a
frontal boundary begins to shift into the region.
An approaching warm front Tuesday afternoon brings strong
temperature advection through the 700mb level. Highs reach into the
low to mid 90s. Strong southerly moisture flow brings dew points
into the upper 60s to lower 70s allowing apparent temperatures to
reach into the mid to potential upper 90s by the afternoon.
Instability ahead and along the front reaches up to 2500 J/kg. The
approaching front will help trigger thunderstorm development. There
are three types of scenarios. The less likely scenarios (<20%), is a
linear organized line developing along the warm front as dew points
reach into the mid 70s. This would help erode the CAP faster
allowing for storms to become organized and increase a damaging wind
threat. The other less likely outcome (<20%) is the CAP remains in
place and temperatures don`t reach the convective point in the
afternoon. Moisture flow would need to be minimal and dew points
only reach into the low to mid 60s. This would rely on the frontal
boundary to be strong enough to break the CAP. The most likely
scenario is discrete storm develop along and ahead of the front.
Modest frontogentic strength along with dew points in the upper 60s
to lower 70s would allow for some of the CAP to erode slowly and
develop discrete thunderstorms. With 0-6km shear 35kts+ and weak low
level shear <10kts, we would see a hail threat and a marginal wind
threat. This scenario is the most likely outcome and HI Res guidance
has picked up on this trend in multiple runs. Hail up to ping pong
balls and winds up to 60mph will be the main threats for Tuesday
late afternoon through the evening.
.LONG TERM...(Wednesday through Monday)
Issued at 228 PM CDT Mon Jul 24 2023
Key Messages:
-Heat continues to build across the region Wednesday, with highs in
the 90s to potential 100 degree mark in isolated locations.
-Chance for stronger storms Wednesday evening as a secondary
boundary moves through the area.
-Zonal flow sets up mid to late week increasing chances for showers
and storms on and off through the early part of the weekend.
Discussion:
Temperature advection continues to surge in the low to mid levels
bringing temperatures into the mid to upper 90s for Wednesday. Dew
points have increased from previous runs, with them reaching into
the lower 70s. High dew points and warm temperatures help increase
heat indices to near 100 degrees during the afternoon. We have a
chance to reach near heat advisory criteria briefly during the
afternoon for areas within the Red River Valley and near the SD
border. Things that could hinder our Apparent T`s from reaching the
low 100s are stronger winds and precipitation chances. Winds are
looking to be rather light around 5-10kts, but we do have
precipitation chances in the afternoon and evening hours.
A secondary boundary shifts down from Canada during the late
afternoon and evening helping initiate thunderstorms in the northern
forecast area. Uncertainty lies with the placement and strength of
the thunderstorms. This is due in part to the convective
temperatures being high, a strong CAP, and the boundaries strength.
A stronger boundary could easily break the CAP and initiate
development however this is a less likely scenario. Convective
temperatures are looking to be in the upper 90s and areas may
struggle to reach the upper 90s for highs in the northern forecast
area. This would help hold the CAP in place. Chances are there for
thunderstorms, but uncertainty is high at this time. Any storm that
would initiate could build their updrafts quickly and bring hail and
strong winds.
After the secondary boundary moves through temperatures start to
drop, but remain warm across the region. Highs on Thursday reach
into the upper 80s and low 90s briefly before dropping to the low to
mid 80s to finish off the week and go into the weekend. Clusters
have indicated this happening from a result of the amplified ridge
flattening out across the northern plains. A trough moves in from
Alaska helping to flatten out the ridge and relieve some of the
northern United States from the heat. However, as zonal flow sets up
and instability remains we could see a trend of on and off
thunderstorm chances through the remainder of the long term.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 625 PM CDT Mon Jul 24 2023
Limited to minor aviation impacts are expected for all TAF sites
through 12z. LLWS may arise at DVL overnight tonight, although the
probability is only about 50-60%. Still, given potential impacts,
we have added it to the TAF. Impacts on TAF sites could increase
after 12z as scattered showers and thunderstorms spread across the
area. There is low confidence in location of showers/storms so
for now it has been foregone from the TAF. Any storms that do
impact TAF sites may present the potential for gusty and erratic
winds, hail, and lightning/Cb development.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.
&&
$$
UPDATE...Riddle
SHORT TERM...Spender
LONG TERM...Spender
AVIATION...Perroux
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
722 PM EDT Mon Jul 24 2023
.UPDATE...
Issued at 721 PM EDT MON JUL 24 2023
Early evening update is being sent out to speed up arrival of
higher (chance) PoPs in association with approaching storms from
the west and northwest. Used primarily a blend of 1-hr NBM,
GFS1hr, and 18z NAMNest for PoPs and QPF. No other significant
changes were made.
&&
.SHORT TERM...(This evening through Tuesday night)
Issued at 418 PM EDT MON JUL 24 2023
A disturbance aloft is moving southeast from the Upper Midwest
and is expected to enter central portions of the Ohio Valley
tonight. Thunderstorms are firing to our west and northwest late
this afternoon as a result. Guidance does suggest increasing
coverage of storms to our west and northwest through the late
afternoon and evening. The 12Z SPC HREF is showing a low
probability, but none the less some potential for some stronger
updrafts along and just south of the Ohio River, possibly kissing
our Bluegrass counties as well. MLCAPE (~2000 J/kg) combined with
marginal effective shear of 20-25 kts may allow for a strong storm
or two late this afternoon for areas closer to the Ohio River. At
this time this threat of severe thunderstorms remains just north
and west of our forecast area. Time will tell if anything manages
to drop far enough southeast to impact any of our area. Did
include some strong thunderstorm wording in the HWO for the
potential, which is expected to be mainly along and north of the
I-64 corridor. Recent runs of the hrrr do keep the bulk of
activity to our north and further west though there is some
redevelopment across eastern portions of our forecast area late
tonight. However, by then there is an even less favorable storm
environment in place for severe weather across eastern Kentucky.
In addition, any activity appears to become more elevated, less
surface based with time. After a relative lull in the threat of
rain around dawn Tuesday, the threat of storms increases a bit
again as the aforementioned short wave disturbance tracks out of
the Ohio Valley. Thus have low end chance PoPs (~30%) lingering a
bit through the day Tuesday for good measure.
Difficult to say how much fog we will see overnight, which will
depend greatly on any convection that develops, and lingering
cloud cover (debris) from shower and thunderstorm activity
overnight. At present kept fog going in our river valleys but the
forecast may be a bit pessimistic overall with extent. In
addition, overnight lows could be a bit too cool depending on
trends with overnight rainfall. Either way, sensible weather is
expected to be quite warm and muggy tomorrow as afternoon highs
approach 90 with dew points around 70, the first day of a string
of hot and uncomfortably sticky days. It is summer after all.
.LONG TERM...(Wednesday through Monday)
Issued at 354 PM EDT MON JUL 24 2023
There is reasonable model agreement through at least the first few
days of the long term period. Strong upper level ridging over the
southwest CONUS will build eastward and result in rising
geopotential heights for our region as an eastern CONUS trough
continues to retreat northward. However, the ridge does not make a
complete merger with the Bermuda high, leaving a weakness or col
over the southeast CONUS. This weakness may still allow for some
isolated convection at times, despite the building heights. Aside
from any limited cooling from convective precip, the rising heights
will result in climbing temps, probably bringing the hottest
readings of the summer thus far.
During the weekend and early next week a series of upper level waves
moving through the flow in eastern Canada and New England is
expected to suppress the ridging southward. This would allow a cold
front to move into KY from the north late in the weekend, providing
a focus for potential convective development. Models are struggling
with the progress of the front at the end of the period, with
uncertainty as to whether it makes it through the area or stalls.
Have continued a mention of precip through Monday, albeit with a
lower POP due to the uncertainty of whether drier air can arrive and
kill precip potential. The increase in clouds, POP, and potential
frontal passage should result in at least slightly lower temps
from the weekend into early next week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
ISSUED AT 721 PM EDT MON JUL 24 2023
A line of generally weakening showers and thunderstorms will move
across the region through 06z, with expected clearing behind it
allowing for the formation of fog, possibly becoming dense between
09z and 12z Tuesday morning. Fog should burn off with mostly clear
skies through midday before scattered low to mid-level clouds
develop for the remainder of the period with a low chance of a
shower or thunderstorm. Other than some gusty winds in the
vicinity of thunderstorms, winds are expected to be light,
generally below 5 kts. However, southwest gradient winds (5-10
kts) develop by tomorrow afternoon as high pressure slides off to
our east.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...CMC
SHORT TERM...RAY
LONG TERM...HAL
AVIATION...CMC
Area Forecast Discussion
National Weather Service North Platte NE
636 PM CDT Mon Jul 24 2023
...Aviation Update...
.SYNOPSIS...
Issued at 329 PM CDT Mon Jul 24 2023
Key Messages:
- Severe weather is possible Tuesday. The primary hazard appears
to be damaging wind gusts.
- A Heat advisory is in effect across southwest and north central
Nebraska Tuesday. The potential for heat advisory conditions
Wednesday and Thursday is uncertain.
- Thunderstorms are possible for most of the next 7 days. Strong
winds should be the primary concern. The risk of severe weather
beyond Wednesday is uncertain.
&&
.SHORT TERM...(This evening through Tuesday night)
Issued at 329 PM CDT Mon Jul 24 2023
Heat products can continue across swrn Nebraska today and Tuesday.
The heat advisory can be extended into ncntl Nebraska Tuesday
afternoon. The temperature and dew point forecast leans on the short
term model blend plus bias correction for highs in the 90s to near
100. The suggested dew points in the 60s to around 70 are on the
high side of the forecast envelop and this is appropriate given the
recent wet weather.
Satellite indicates a MCV operating across srn SD this afternoon and
the system has shown little sign of activation. The system should
drift southeast through cntl/ern Nebraska later this afternoon and
evening. None of the models are showing this system activating and
this is probably due to the lack of sfc focus and weak moisture
transport. It is worth watching given the belt of strong
northwesterlies aloft, 25-50kts at h500-300mb.
Attention turns to a disturbance across ID/WY which will move east
and produce a round of thunderstorms across wrn and ncntl Nebraska
overnight. The HRRR suggested strong but sub-severe wind gusts. POPs
for this system are limited to 30 percent. None of the models show
upscale growth occurring as it moves east.
Another disturbance, across NV this afternoon, will move east and is
the basis for isolated to scattered thunderstorms Tuesday from about
4 pm to midnight. The storm threat is somewhat uncertain regarding
whether large hail or wind damage would be the primary threat but
given the very warm sfc temperatures and rich moisture aloft, wind
damage would appear to be favored.
POPs for the forecast tonight through Tuesday night lean on the
short term model blend plus the NAMnest and HRRR which are on the
aggressive side of the model envelop.
.LONG TERM...(Wednesday through Monday)
Issued at 329 PM CDT Mon Jul 24 2023
The models are in very good agreement showing the upper level ridge
of high pressure across the desert Southwest migrating north and
east into the srn Plains this week and beyond. What is interesting
is the attendant plume of subtropical moisture attached to the
wrn portion of the ridge will be directed mostly across the cntl
Plains. This feature and the weak upper level forcing shown by the
models is the basis for isolated/chance POPs nearly daily
throughout the extended forecast. It is worth noting this is an
upper level moisture plume which will maintain moist adiabatic mid
level lapse rates. Thus, the severe weather concern would most
likely be damaging wind gusts. A belt of 25 to 50 kt westerlies
will remain overhead at 300mb and this deep layered shear could
support isolated severe storms depending on the time of day and
sfc focus.
The blended model solution shows heat indices near 100F across parts
of swrn and ncntl Nebraska Wednesday and Thursday. The potential for
heat advisories will be examined in later forecasts. It looks like
these areas will be on the wrn and nrn edge of higher values
centered over KS and cntl/ern Nebraska. The potential for excessive
heat across wrn and ncntl Nebraska seems marginal at this point.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 634 PM CDT Mon Jul 24 2023
VFR conditions will prevail through the forecast period.
The biggest question revolves around potential convection
developing after 05Z Tuesday around the VTN TAF site. CAMs do have
some agreement on thunderstorms in the area although timing is
varied as is the potential strength of the storms. Current
thinking is that any storms tonight will be sub-severe, however
will have erratic/gusty wind potenial as updrafts collapse. Have
included a separate group for VTN suggesting this potential,
though confidence is only modest currently.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
Heat Advisory from 1 PM CDT /noon MDT/ to 10 PM CDT /9 PM MDT/
Tuesday for NEZ005>010-025>029-036.
Heat Advisory until 10 PM CDT /9 PM MDT/ Tuesday for NEZ037-038-
057>059-069>071.
&&
$$
SYNOPSIS...CDC
SHORT TERM...CDC
LONG TERM...CDC
AVIATION...JWS
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
631 PM CDT Mon Jul 24 2023
.SHORT TERM...
Issued at 305 PM CDT Mon Jul 24 2023
Through Tuesday night...
Key Forecast Messages:
* Haze from wildfire smoke into Tuesday
* Hot conditions on Tuesday away from the lake though with
increasing humidity level/heat indices
* Small chance(20% or so) of thunderstorms late Tuesday
night/early Wednesday, mainly near and west of I-39 from 4am-7am
The main item of note through Tuesday morning will be haze from
wildfire smoke drifting into northwest Indiana. 4-7 mile visibility
is common as of this writing from northwest Illinois east-southeast
across the Illinois Chicago metro. Based off visible satellite trends
and HRRR and RAP near-surface smoke forecasts, expecting the haze
to drift southeast through tonight, as alluded to above, with
perhaps visibility dipping a bit lower. Also, may be patchy fog
south of US-24, particularly in Indiana, though withheld mention
for now. Otherwise, looking at a tranquil night under weak
surface ridging. Can`t rule out a few "blips" overnight over far
interior sections, though this already low chance looks a bit more
favorable across west central Illinois to the west and southwest
of far southwest CWA sections. Lows will range from the low-mid
60s for most of the area to around 70F in Chicago.
Tuesday will be capped to convection and likely feature a bit less
Cu than today (Monday) near the lake breeze. Lingering haze from
Canadian wildfire smoke should gradually drift eastward through
the day. The bigger story will be the first widespread 90F+ highs
for areas away from the lake since July 4-5. Climo of forecast 925
mb temps supports generally 90-92 (official range of 89-92F), so
wouldn`t be surprised at spots up to 93F or so. Saving grace will
be likelihood of dew points mixing out some at peak heating,
especially northeast half or so of the CWA, keeping forecast heat
indices near to only slightly above the actual air temps.
On Tuesday night, the guidance is generally depicting rather dry
mid-levels (h7-h5), shown on forecast soundings. Thus, despite an
uptick in MUCAPE, should retain fairly appreciable MUCIN through
much of if not the entire overnight. As the low-level jet perks up
after midnight, associated isentropic upglide may be enough for
widely isolated showers, likely lacking lightning. Best chance for
any TS with the potential isolated activity looks to be near and
west of I-39. Finally, showing a small sliver of chance PoPs and
TS 4am-7am to account for the low probability scenario of earlier
arrival of an upstream MCS prior to 12z Wednesday. Better chance
for this and any associated severe weather threat to move in is
beyond 12z Wednesday (refer to Long Term AFD below for mid-week
and beyond convective threats).
Castro
&&
.LONG TERM...
Issued at 305 PM CDT Mon Jul 24 2023
Wednesday through Monday...
Key Forecast Messages:
* Building heat and humidity especially Wednesday through Friday
with an increasing threat for heat-related illnesses, barring
effects from thunderstorms
* Opportunities for episodic clusters of thunderstorms, including
severe weather. At this point, a signal remains for severe weather
events somewhere in the region on Wednesday and again on Friday
into Saturday.
* Cooling temperatures this weekend and beyond, but just how fast
and how cool are opportunities for refinements in future forecast
packages.
Technical discussion:
Ensemble model guidance remains in remarkably good agreement that
the upper-level ridge responsible for record-breaking heat across
the southern and western United States will gradually shift eastward
Wednesday onward, leading to building heat and humidity across the
Great Lakes. As the ridge slides eastward however, it will gradually
lose amplitude, meaning the magnitude of heat locally shouldn`t be
nearly as pronounced as to the south and west of our area.
Nevertheless, ensemble mean 850mb temperatures are poised to rise in
the lower 20 C range Wednesday through Friday setting the stage for
daily highs in the low to mid 90s. When combined with increasing
humidity levels (surface dew points in the upper 60s if not
outright lower 70s), daily forecast heat indices will range from
100-105F Wednesday through Friday. Forecast wet-bulb globe
temperatures, which take into account sun angle, cloud cover, and
wind speed in addition to temperature and humidity levels, are
poised to reach the upper 80s to around 90s each day, which
typically corresponds to heat related illnesses if preventative
measures are not taken. So, the message for Wednesday through
Friday is that heat and humidity levels will rise, potentially
toward dangerous levels.
The fly in the ointment with the forecast for heat is, of course,
opportunities for convection which may very well hold temperatures
well below our forecast each day. In this pattern, it can be
impossible to pinpoint exactly when and were convection will occur,
largely due to a dependences on previous episodes of convection that
reinforce and relocate an effective warm frontal boundary. At this
point, signals remain for a convective episode somewhere in the
region on Wednesday and another on Friday. However, exactly when
(morning or afternoon?) and where (northern Illinois or somewhere
else entirely?) will be determined as we get closer and can track
individual responsible shortwaves and the location of the effective
warm front. At any rate, any convective episode will likely feature
severe weather (damaging winds, hail, and even tornadoes) based on
the availability of corn-enhanced instability, seasonably strong
upper-level flow and shear, and a plume of steep mid-level lapse
rates.
(It`s worth noting that if convection entirely misses our area
Wednesday through Friday, we may very well have multiple days in
a row with dangerous heat. The criteria for an Excessive Heat
Warning in Cook county is 3 consecutive days with a peak heat
index over 100. Given the expectation for *some* convection
nearby or the potential for an outflow boundary from convection
to our north to surge south along the lake and into Cook county
Wednesday, Thursday, or Friday, confidence in 3 consecutive days
with heat indices >100F is simply too low. In other words, there
are too many opportunities to bust our temperature forecast to
justify the issuance of an Excessive Heat Watch. Forecasting experience
tells us we`ll probably have to deal with both storms and heat at
different through the 3-day period).
Saturday onward, ensemble model guidance suggests upper-level
troughing will attempt to build into the Great Lakes. The result
should be a trend toward cooler, more seasonable temperatures,
lowering humidity, and lower chances for rain. Just how fast (and at
what magnitudes) upper-level troughing develops will be an
opportunity for refinement in future forecast packages.
Borchardt
&&
.AVIATION...
For the 00Z TAFs...
Aviation Forecast Concerns:
* Reduced visibility in wildfire smoke into Tuesday morning.
Canadian wildfire smoke has spread into the region today, with
visibilities generally in the 3SM-6SM range early this evening.
High-res HRRR/RAP model forecasts of smoke concentration would
suggest reduced visibility will linger into Tuesday morning before
improving. Will need to monitor visibility trends during this
period, as forecasts do support some increase in concentrations
tonight especially for the Chicago metro terminals.
Otherwise, a weak area of surface high pressure and associated
light pressure gradient will continue to support light and
variable winds overnight, with the exception of easterly winds for
the Chicago terminals early this evening before the lake breeze
circulation decays. Winds look to turn more southerly Tuesday as
the surface high moves off to the east and weak low pressure
develops over the Plains. High-res guidance suggests winds may
become south-southwest late morning/midday, though confidence is
somewhat low on south-southwest as opposed to south-southeast by
afternoon. A southeasterly lake breeze is expected to develop by
late afternoon however, which should bring southeast winds into
KORD/KMDW by 22Z-00Z.
Ratzer
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.
&&
$$
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Area Forecast Discussion
National Weather Service Memphis TN
905 PM CDT Mon Jul 24 2023
...New UPDATE...
.UPDATE...
Issued at 859 PM CDT Mon Jul 24 2023
Evening satellite shows mostly clear skies over the Mid-South
deeply entrenched in northwest flow. It should be a quiet, warm,
dry overnight period until after sunrise. A few CAMs show a weak
MCS arriving on the MO/AR state line around 8AM tomorrow, but the
00Z HRRR and NAM both show no convection at all. The current
forecast has a slight chance (at least 15%) of showers and
thunderstorms that might clip a few of our nothern counties
tomorrow morning, but nothing widespread or significant. The
current forecast reflects the guidance well and no changes were
needed with the evening update.
&&
.SYNOPSIS...
Issued at 209 PM CDT Mon Jul 24 2023
Possible isolated convection is expected to come through the NW
portion of TN and should remain north and along the I-40
corridor. Clear skies and warmer temperatures throughout the next
week are expected with the high pressure system building in from
the west.
&&
.DISCUSSION...
(This evening through next Sunday)
Issued at 209 PM CDT Mon Jul 24 2023
The 18Z HRRR guidance has held strong in bringing possible
convection into the NW portion of TN tonight. After days of
continuous storms, an upper level ridge will extend from the SW
and eastward well into the region bringing clear and warm weather.
Isolated convection is still possible but limited over the next
couple of days as we are on the periphery of the ridge. Due to
smaller potential for convection, temperatures in the region will
start to increase. This will result in temps being in the mid to
upper 90s by midweek. We are expecting to be below heat advisory
criteria this week but possible reevaluation of heat advisories
for next week will need to be done as temperatures increase.
By the end of the week, the ridge will weaken and bring more of a
zonal flow briefly rather than the NW flow that we have been
experiencing throughout most of the summer.
&&
.AVIATION...(00Z TAFS) Issued at 612 PM CDT Mon Jul 24 2023
Isolated convection across the Midsouth should dissipate within
the next hour or two. Additional convection is possible again
tomorrow, mainly near JBR. A strengthening ridge and surface high
pressure should result in mostly clear and dry conditions. VFR
conditions are expected to prevail at all sites through the TAF
cycle. Southwest winds will prevail tomorrow, generally 5-10kt at
MEM, MKL and TUP, slightly stronger at JBR tomorrow afternoon.
30/Sirmon
&&
.MEG WATCHES/WARNINGS/ADVISORIES...
AR...None.
MO...None.
MS...None.
TN...None.
&&
$$
PUBLIC FORECAST...GNC
AVIATION...JDS
Area Forecast Discussion
National Weather Service Marquette MI
1201 AM EDT Tue Jul 25 2023
.SHORT TERM...(This afternoon and tonight)
Issued at 127 PM EDT MON JUL 24 2023
Hazy, but mostly clear skies have been observed on GOES visible
satellite imagery today. The culprit continues to be upstream
Canadian wildfires which are utilizing northwest flow aloft to
stream smoke into our forecast area. Despite this, enough solar
radiation has been able to penetrate the smoke and warm most of the
region into the 70s and support some diurnal cloud development.
Exceptions look to be near Lake Superior, particularly out near
Grand Marais which has been swamped in with fog. There, we`ve
largely only warmed into the 60s.
RAP analysis paints a weak meso-high over eastern Lake Superior with
a lake breeze developing off of Lake Michigan/Bay of Green Bay. With
continued northwest flow aloft and an an elongated shortwave
migrating through central Wisconsin, increased convergence across
south-central Upper Michigan is expected to take advantage of
growing instability and support shower and thunderstorm development
later this afternoon. Model guidance suggests MLCAPE increasing to
1000-1500j/kg with deep layer shear of 20-25kts. If convection is
able to ride the boundary, a stronger storm or two capable of
producing hail should be expected.
Expecting only a couple hours of convective activity as the setting
sun helps to remove convective energy. Overnight temps dipping into
the low 50s may be able to support patchy fog developing, mainly
across interior central and east. Expect lakeshore temps to bottom
out in the mid 50s to near 60F.
.LONG TERM...(Tuesday through Monday)
Issued at 300 PM EDT MON JUL 24 2023
Upper air pattern consists of a 500 mb trough over the Pacific NW
and a ridge across the Rockies and southern and central plains 12z
Tue. A shortwave in the northern Rockies 12z Tue moves across the
northern plains 00z Wed and into the upper Great Lakes 12z Wed. A
trough by Lake Winnipeg 00z Thu moves across Ontario on Thu. Did not
make too many changes to the going forecast overall. Temperatures
get very hot this forecast period.
In the extended, the GFS and ECMWF show a 500 mb ridge across the
central and southern plains 12z Fri with a belt of westerlies across
the northern U.S. with a weak shortwave passing across the upper
Great Lakes with a cold front that has moved through the area. Upper
ridging builds into the northern Rockies 12z Sat. The ridge then
builds into the northern plains 12z Sun through 12z Mon as troughing
moves into the eastern U.S. Temperatures look to be near normal for
this forecast period.
&&
.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1201 AM EDT TUE JUL 25 2023
VFR will be the predominant flight category this morning However,
will insert mention for MVFR at SAW during the pre-dawn hours again
with a tempo for IFR/LIFR. Otherwise, do not expect any other
impacts with light winds.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 300 PM EDT MON JUL 24 2023
Winds should remain under 20 kt for much of the week as a warm
airmass invades the region. By Friday, a cold front is forecast to
drop in from the north, which could result in a period of gusty wind
immediately behind it. Episodic thunderstorms are possible over the
lake Tuesday night through Friday, with low confidence on timing and
placement at this time. Also, periods of dense fog are likely at
times.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...JTP
LONG TERM...07
AVIATION...TDUD
MARINE...07
...Updated Aviation Forecast Discussion...
.DISCUSSION...
Issued at 355 PM CDT Mon Jul 24 2023
Key Messages:
- Hot and humid for the week ahead. Expect highs mostly in the
90s and heat index values 100-107 through at least Thursday.
- Have increased chances of showers and thunderstorms for
Tuesday.
.TONIGHT...
Temperatures are mostly in the 80s as of 19Z, but some 90s have
already developed. They`ll be common through the work week.
Dewpoints, in the sticky 70s, are also forecast to remain above
normal. `Tis the season for dewpoints above 70F. Omaha Eppley`s
climatology shows less than 5% of days in May reaching this mark
with a frequency of about 30% of June days. July marks the peak
with about 55% of days hitting 70F or higher Tds. Some of that
moisture is from the Gulf of Mexico... but some is from corn
sweat. An acre of corn gives off nearly 4,000 gallons of water
every day.
Water vapor imagery shows the amplified ridge over the Rocky
Mountains with h5 heights reaching 600 decameters over the Four
Corners. A reinvigorating convective complex can be spotted south
of St. Louis.
A heat advisory was posted early this morning through Thursday for
afternoon heat indices pushing close to 105 or hotter. Worth
noting that overnight heat indices dip only to 70 or mid-70s. This
makes it difficult to cool off at night, especially in the
strongest urban heat islands of Omaha and Lincoln. This makes the
heat all the more dangerous as cooling off at night will be
difficult for those without A/C units.
Expect to see some stars and a waxing crescent tonight with some
high level clouds moving in from the west.
.TUESDAY...
Spotty convection is possible, if not likely, through much of the
day on Tuesday. It begins with a weak shortwave moving into
northeast Nebraska by daybreak. Have introduced some 20% POPs
across most of the CWA as the wave moves NW to SE over the course
of the day. Storms should be elevated thanks to relatively dry air
below 8,000 feet. The morning severe threat looks minimal at best.
The best chances of showers and storms will be in the evening. The
SPC has increased the SWO to "SLIGHT" for parts of far northern
Nebraska. The threat here seems to be from an MCV that guidance
has developing over the eastern Dakotas that will approach the
Norfolk, NE area overnight. Believe the best chances of severe
storms would be between midnight and 6am Wednesday. Damaging wind
gusts would be the primary threat.
.REST OF THE FORECAST...
Wednesday and Thursday will the hottest days of the week, though
Friday`s temps have been trending up and may soon oblige us to
extend the heat advisory in time and expand in area.
The ridge of high pressure allows the temps to soar and convection
to remain generally capped each afternoon. NAEFS mean temperatures
at 850hPa climb close to 30C... which is a maximum in the 30 year
reanalysis climatological window centered on late July.
The NBM`s probabilities show a 25-50% chance of any one location
hitting 100F on Friday. Those numbers climb by another 10% for
Thursday... suggesting it`s likely at Lincoln, Norfolk, and the
Omaha metro.
A cold front will sweep through the area on Friday afternoon and
knock temps down 5-10 degrees. This will mean highs in the low to
mid-90s ... still well shy of seasonal norms. The front brings a
chance of showers and storms and helps moderate the upper ridge.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 606 PM CDT Mon Jul 24 2023
Latest HRRR data indicate a loosely organized cluster of
thunderstorms moving into northeast NE toward daybreak Tuesday,
with remnants of that storm activity potentially reaching the
Omaha and Lincoln areas by mid-morning. The other CAMs depict
slightly different scenarios, so will not include TSRA in this
forecast. 00z model data will be evaluated for potential inclusion
in the 06z forecast. Otherwise, southeast winds at less than 12 kt
are expected to increase to 12 kt or slightly above by early to
mid-afternoon Tuesday.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...Heat Advisory until 9 PM CDT Thursday for NEZ030-042>045-050>053-
065>068-078-088>093.
IA...None.
&&
$$
DISCUSSION...Nicolaisen
AVIATION...Mead
Area Forecast Discussion...Updated
National Weather Service Pendleton OR
708 PM PDT Mon Jul 24 2023
Updated aviation discussion
.SHORT TERM...
Tonight through Wednesday night...lAtest satellite imagery showed
a cold front across portions of Kittitas, Yakima and Klickitat
Counties then extending southwestward. This front will continue
moving eastward and will cross the remainder of the region through
tonight. Gusty winds will occur ahead of the front and with its
passage.
While the front is mainly expected to be dry, there could be a
few showers in the Washington Cascades. Behind the front, the flow
is expected to become more westerly as low pressure moves into
British Columbia. The westerly flow will continue into early
Wednesday, before the flow becomes more southwesterly in response
to a weak trough moving onshore early Thursday.
With the exception of the showers today in the Cascades, the rest
of the short term period looks dry.
The HRRR Smoke model shows some surface smoke even as far north
as northeastern Oregon this afternoon, but highest concentrations
are in central Oregon near the Bedrock Fire, where Redmond is
already seeing some reduced visibilities. Vertically Integrated
Smoke concentrations are much higher over a good portion of the
area even as far north as the Tri-Cities, later this evening into
tonight, so its possible there could be haze. The ultimate
over the next few days is how much will the smoke and haze impact
high temperatures? That is something we will have to watch, but
definitely seems like there will be some effect, especially for
central Oregon.
Winds today look to gust into the 30 to 35 mph range, with gusts
as high as 40 mph. The previously issued Red Flag warning still
looks good. There is high confidence (70 to >90%) of wind gusts
greater than 39 mph today across portions of the Columbia Basin
and the Simcoe Highlands. However, when looking at winds greater
than 47 mph, except around the Simcoe Highlands where percentages
range from 30 to 50%, general confidence is mainly less than 20%.
For Tuesday, winds will be still breezy but lower, with gusts
mainly 20 to 30 mph in the Basin, with gusts possibly to 35 mph in
the Simcoe Highlands. Wind gust probabilities greater than 39 mph
are 30-40% across the Simcoe Highlands and negligible elsewhere.
With lower winds and humidities about the same, fire weather
concerns will be elevated, but look to be below red flag criteria.
Temperatures will be very close to seasonal the next few days.
Highs on Tuesday will range from the lower to mid 80s in central
Oregon to the upper 80s to near 90 degrees in the Columbia Basin
Wednesday will be similar, but will be perhaps a degree or tow
warmer.Overnight lows will mainly be in the 50s to around 60
degrees tonight, then the 40s to mid 50s Tuesday night and
Wednesday night. As mentioned above, confidence in temperatures is
average at best, especially where haze and smoke impacts are
highest.
.LONG TERM...
Thursday through Monday...Summertime weather continues during the
extended period with the primary points worth highlighting being
near-normal temperatures, diurnally breezy winds through the
Cascade gaps, and mostly dry southwesterly flow aloft associated
with good ensemble agreement in mean upper-level troughing
stretching from the northeast Pacific Ocean to southwest Canada
and more loose ensemble agreement (per ensemble clusters) in
timing of several weak systems passing across the Pacific
Northwest through the period. While not necessarily indicative of
the lack of potential for highlights, the ECMWF EFI does not show
strong ensemble agreement in any climatologically unusual events,
be it temperatures, wind, or precipitation. Plunkett/86
&&
.AVIATION...00Z TAFs...A deep upper-level closed low has moved
ashore along the British Columbia coast late this afternoon. A cold
frontal boundary from the low is making its way through the area and
is bringing a band of SCT-BKN mid and upper level clouds with it
along with a few rain showers along and near the Cascades. KYKM had
some light rain showers earlier but that has just about ended and do
not anticipate any showers at TAF sites through 00Z tomorrow
afternoon. Showers will remain possible over the Cascades through
early tomorrow morning. Skies will mostly clear this evening but FEW-
SCT cirrus above 20K feet AGL will continue through tomorrow
afternoon. Winds will continue to be strong with west to northwest
winds at 12 to 20 kts with gusts to 30 kts through 04Z-06Z this
evening when winds will drop below 12 kts. Winds will begin
increasing again around 15Z tomorrow and all TAF sites will increase
to 10 to 20 kts with gusts to 30 kts around 18Z-22Z tomorrow
afternoon. Smoke and haze from regional wildfires will continue
through the next 24 hours and and may reduce VSBY at times,
especially at KRDM and KBDN which have dropped to MVFR levels this
afternoon. Additionally, KPSC may have occasional VSBY of 4-6SM this
evening and tomorrow afternoon due to BLDU. Perry/83
&&
&&
.PRELIMINARY POINT TEMPS/POPS...
PDT 56 83 52 84 / 10 0 0 0
ALW 60 87 54 88 / 0 0 0 0
PSC 64 88 58 88 / 10 0 0 0
YKM 54 83 50 85 / 0 0 0 0
HRI 60 88 54 89 / 0 0 0 0
ELN 54 78 51 83 / 10 0 0 0
RDM 49 83 46 85 / 0 0 0 0
LGD 54 84 51 86 / 0 0 0 0
GCD 53 88 51 90 / 0 0 0 0
DLS 61 83 57 87 / 0 0 0 0
&&
.PDT WATCHES/WARNINGS/ADVISORIES...
OR...Red Flag Warning until 11 PM PDT this evening for ORZ641.
WA...Red Flag Warning until 11 PM PDT this evening for WAZ691.
&&
$$
SHORT TERM...77
LONG TERM....86
AVIATION...83
Area Forecast Discussion
National Weather Service Springfield MO
613 PM CDT Mon Jul 24 2023
Key Messages:
1. Scattered thunderstorms possible (30-50% chance) mainly east
of Highway 65 late tonight into early Tuesday morning. A few
storms may produce wind gusts up to 50 mph and locally heavy
rainfall. There is a limited risk for flash flooding
2. Hot and breezy for the remainder of the week.
.SHORT TERM...(This evening through Tuesday)
Issued at 214 PM CDT Mon Jul 24 2023
Synoptic Scale Pattern and Current Conditions: Water vapor imagery
reveals that a strong upper level ridge persists across the
Rockies with a northwest flow aloft in place from the Dakotas
through the Mid Mississippi Valley. At the surface, a stationary
front is analyzed from southern South Dakota through eastern
Nebraska and into northern Missouri.
Remnant cloud cover from a complex of thunderstorms continues to
drift southeast across southern Missouri. An associated outflow
boundary has now pushed into northern Arkansas with scattered
thunderstorms persisting south of this feature.
The clouds and earlier outflow have kept temperatures down today.
However, we do think that most areas will make a late afternoon
run at the upper 80s and lower 90s as clouds continue to thin.
Quiet Evening Ahead: As we head into the late afternoon and early
evening hours, any thunderstorm activity near the MO/AR border
will shift south with the aforementioned outflow boundary. Given
that there will not be sufficient time for the atmosphere to
recover, chances for thunderstorms late this afternoon and early
this evening look very low (less than 10%).
Overnight Thunderstorm Potential: A nocturnal low-level jet will
develop and nose into eastern Kansas and western Missouri from
late this evening into the overnight period. Isentropic upglide in
the vicinity of that surface front may result in more
thunderstorm development, initially across northern and perhaps
central Missouri. This is backed fairly well by 12Z CAMs. The last
few runs of the RAP also show a trend of removing convective
inhibition (owing to isentropic upglide) for parcels lifted in the
850-700 mb layer.
Thus, our confidence is increasing in thunderstorm potential from
late tonight through early Tuesday morning, especially east of the
Highway 65 corridor. We have bumped PoPs up into the 30-50% range
for this scenario. PoPs may need to be further increased across
the eastern Ozarks, especially if upstream thunderstorms are able
to grow upscale into another MCS.
Speaking of the MCS scenario, there would be an attendant threat
for gusty winds if a southeastward moving system takes on a
linear nature. Gusts of 30-50 mph would be the most likely
scenario if the system does indeed become linear. CAMs are showing
little in the way of probabilities for winds greater than 50 mph.
Hot Tuesday: Short term ensembles are in good agreement that the
upper level ridge will expand east starting on Tuesday with that
surface front also beginning to lift north as a warm front. While
we may still be dealing with leftover convection across the
eastern Ozarks early Tuesday morning, much more in the way of
sunshine will be in place by the afternoon. This will allow
temperatures to warm into the middle to upper 90s over most areas.
NBM statistical data reveals that some locations along the I-49
corridor will make a run at the 100 degree mark.
For the most part, dew points on Tuesday will not be all that
oppressive. Most areas will be in the lower to middle 60s. This
will keep heat indices in the 95-104 range for most areas. The one
exception will be areas of extreme southeast Kansas and west-
central Missouri where dew points in the upper 60s are expected.
This would put heat indices in the 104-107 range. We considered a
Heat Advisory, but decided to hold off and get a better feel for
overnight and early morning convection and cloud cover.
Tuesday will also be somewhat breezy, especially across southeast
Kansas and western Missouri. Southwesterly wind gusts of 20-30
mph are expected across this region. This may offer a slight
amount of relief from the heat.
The potential for thunderstorms Tuesday afternoon is less than 10%
as the atmosphere becomes increasingly capped with warming 700
mb temperatures.
.LONG TERM...(Tuesday Night through Monday)
Issued at 214 PM CDT Mon Jul 24 2023
Hot for the Remainder of the Week: WPC cluster scenarios all
reveal the upper level ridge slowly building east along and north
of the I-40 corridor. Each cluster scenario takes the 500 mb 5940
meter height contour north of the forecast area and into
northeastern Missouri. Meanwhile, 850 mb temperatures are forecast
to warm into the 25-28 Celsius range. That surface warm front
will also lift well north of the region.
This gives us high confidence that high temperatures will top out
in the middle to upper 90s on a daily basis along and south of the
I-44 corridor through at least Friday. Southwesterly surface
winds will likely favor temperatures warming into the 98-102
degree range north of the I-44 corridor starting on Wednesday.
With dew points expected to remain in the 60s, afternoon heat
indices will top out in the 100-108 degree range. This will likely
require future heat headlines.
Thunderstorm chances look very low (less than 15%) as warm mid-
level temperatures and large scale subsidence will be hostile to
updraft development.
Early Next Week: Confidence in temperatures begins to decrease by
next Sunday as NBM statistical data shows more spread. The
extended cluster scenarios do begin to decrease heights across the
area and nudge the 500 mb 5940 meter height contour back
southwest into the Missouri Ozarks. Ensemble 850 mb temperatures
also show a slight cooling trend. Thus, we may see a slight
cooldown by early next week.
The large scale regime by early next week may also put us back in
line for MCS potential. Ensembles do show a general trend
towards that surface front dropping back south into at least
northeastern Missouri. We have maintained 10-20% NBM PoPs for next
Sunday and Monday given a general lack of predictability out that
far.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 612 PM CDT Mon Jul 24 2023
VFR conditions will prevail across the area this evening and
through the day on Tuesday. There is a low in chance for an
isolated shower/storm overnight but most locations should remain
dry and this low chance should mainly be east of the TAF sites.
Low level wind shear will be possible overnight into Tuesday
morning, mainly at the KJLN TAF site. Gusty south to
southwesterly winds will develop across the area Tuesday
afternoon and evening.
&&
.SGF WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&
$$
SHORT TERM...Schaumann
LONG TERM...Schaumann
AVIATION...Wise
Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
806 PM EDT Mon Jul 24 2023
...New UPDATE, AVIATION...
.UPDATE...
Deep moisture and southwest to westerly flow helped fuel scattered
to numerous showers and storms this afternoon, with the greatest
coverage from around the Tampa Bay north through the Nature Coast.
Showers and a few storms are still shifting east into these areas
from the Gulf early this evening, but should largely dissipate
over the next couple of hours with the loss of solar heating.
However, HREF and HRRR models are showing chances for a few
showers to linger off the Nature Coast throughout the overnight
period as the upper level trough continues to extend south into
the northern Gulf.
The forecast looks on track with southwesterly/westerly flow
continuing for much of the area on Tuesday. This will result in
some early morning showers shifting onshore from the Gulf from
around the Tampa Bay north, then showers and storms building east
into the interior during the afternoon. No significant changes are
planned for the evening update.
&&
.AVIATION...
(00Z TAFS)
Scattered showers and a few storms will continue to linger around
KTPA, KPIE, KLAL, and KSRQ for the next couple of hours, then
mainly rain free and VFR conditions should hold overnight. Some
early morning showers will be possible shifting onshore around the
Tampa Bay from 12-15z, then more widespread showers and storms
will be possible in the afternoon, quickly shifting inland.
&&
.MARINE...
Issued at 321 PM EDT Mon Jul 24 2023
Scattered to numerous showers and thunderstorms will continue to
move across the northern and central waters over the next day or
so while west to southwest winds persist across the waters. Winds
become easterly during the second half of the week with shower
and thunderstorm timing shifting to the mainly late afternoon and
evening. Locally hazardous conditions are possible in the
vicinity of storms.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 80 93 80 95 / 20 40 10 50
FMY 78 97 77 96 / 10 40 20 60
GIF 76 94 76 94 / 20 50 10 60
SRQ 79 94 77 96 / 10 30 10 50
BKV 73 93 72 96 / 30 50 10 60
SPG 82 91 81 93 / 20 40 10 50
&&
Sea Breeze Thunderstorm Regime For Tuesday: 4
Sea Breeze Thunderstorm Regime For Wednesday: 1
For additional information on sea breeze regimes, go to:
https://www.weather.gov/tbw/ThunderstormClimatology
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...None.
Gulf waters...None.
&&
$$
UPDATE/AVIATION...Fleming
PREVIOUS MARINE...Close