Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 07/15/24
Area Forecast Discussion
National Weather Service La Crosse WI
1008 PM CDT Sun Jul 14 2024
.KEY MESSAGES...
- Storm chances persist for this evening into Monday evening. A
few storms may be strong to severe with damaging wind gusts
and localized flooding being the primary threats primarily on
Monday. Large hail is a secondary threat.
- Hot and humid conditions continue into Monday with highs in
the upper 80s to near 90. Widespread heat indices in the lower
to upper 90s with some areas reaching 100 on Sunday.
- Cooler and drier conditions beginning Tuesday and into much of
the upcoming week with highs in the middle to upper 70s.
&&
.DISCUSSION...
Issued at 304 PM CDT Sun Jul 14 2024
Humid With Storm Chances This Evening, Some Strong to Severe:
Muggy conditions are the name of the game this afternoon with
observed dewpoints across much of the region well into the 70s. Air
temperatures maintaining into the lower to mid 80s are maybe a touch
cooler than expected with some cloud cover around but still
relatively on track to see highs reach into the upper 80s in
spots by late afternoon and early evening with heat indices in
the middle to upper 90s in some locales.
As we head into the evening hours, our convective environment is
essentially a powder keg with guidance showing the potential for the
cap to erode across southern portions of our area during the evening
hours (shown in the KDBQ 14.13z RAP sounding at 6pm). When
considering MLCAPE values of 2000-3000 J/kg across our south would
expect storms to initiate very quickly with anything that provide
any kick in the atmosphere. Looking at GOES-16 water vapor imagery,
a remnant MCV can be noted across western and central MN that
is slowly trekking southeast accompanied with a subtle
shortwave. As a result, many of the CAMs rapidly develop a
cluster of storms across portions of northeast IA and
southwestern WI later this evening. Currently, the main question
with this is the aforementioned cap which tries to erode with
this weak forcing. How much the cap erodes will determine
convective coverage. Shear profiles appear fairly weak with
0-6km shear in the 14.16z RAP being fairly minimal, around 20-30
kts. As a result, would expecting a more multi-cell
configuration with individual cells struggling to maintain.
Consequently, would only expect to see hail with more robust
updrafts. However, with fairly robust DCAPE values collocated
with the MCV, would think that cores could collapse fairly
vigorously which could lead to isolated downburst gusts to 60
mph. Storms will quickly exit the region to the southeast with
the window for storms being likely a few hours (through about
8-9pm at the latest).
Severe Weather Potential Early Monday into Monday Evening:
As we head into the overnight, forecast soundings show in the 14.16z
RAP has low-level saturation and fairly light winds throughout
the low-levels. Consequently, with much of the recent rainfall
we have seen over the past few days, could see areas of fog
initially during the overnight, with questions remaining as for
how long it maintains as an incoming MCV approaches. As this MCV
and accompanying 500mb shortwave approaches, expecting to see
convection as it approaches the local area during the morning
hours. As it then progresses eastward a surface cold front is
draped across our region and pushes south with additional
convective initiation possible. As a result, with severe regimes
in play for Monday several different scenarios may be possible.
Starting with the morning MCV, as the shortwave moves through
the local area (Which also still maintains some uncertainty in
timing amongst deterministic guidance) during the morning hours,
modest MLCAPE of 2000-3000 J/kg would certainly provide enough
of a boost to get convection going. However, deterministic
soundings (14.15z RAP) would suggest a cap is still largely in
place during the morning hours which would be a serious
hindrance to convection as noted in the 14.12z HRRR which has
storms fizzling out as they approach the local area. However, if
storms can form an organized cold pool with the higher
effective bulk shear in the vicinity of the MCV. This type of
convective complex (as illustrated in the 14.12z ARW) would
likely pose some damaging wind threat if it can utilize the
instability gradient and get through the cap.
As we head into afternoon, the aforementioned cold front pushes
through the region during the afternoon. The key question as we
approach this time of day is how the cap will behave, the CAMs
vary considerably on this with the 14.12z HRRR keeping the cap
in place throughout the day leading to minimal convective
development as the front progresses through. This is contrasted
heavily by the most aggressive solution in the 14.12z ARW which
would favor an organized MCS along the boundary pushing south
with relatively uncapped thermodynamics and plenty of 0-3km
shear (roughly 35-50 kts in the 14.15z RAP) for forward
propagation and potential bowing structures. As a result, if
this scenario were to manifest would expect damaging winds to be
the primary threat with heavy rainfall potentially leading to
flash flooding concerns where soils are already very saturated.
Consequently, the SPC has a slight risk (Threat level 2 of 5)
across much of the local area.
The last caveat to this whole forecast is an organized MCS across
central IA that some of the recent CAMs have been trying to pick up
on. While much of the CAMs mainly keep it south of the area through
the afternoon and evening hours, fairly favorable 0-3km shear
profiles and MLCAPE of 3000-5000 J/kg in the 14.15z RAP would enable
a bow echo type structure to push east with the potential for
damaging wind gusts (perhaps approaching 70-80 mph).
Furthermore, this is highlighted in the 14.12z HRRR neural
network probabilities which has modest probabilities (40-50%)
for winds over 50 kts across portions of northeastern IA. With
some uncertainty in exactly where the MCS positions itself the
SPC has put extreme southern portions of our forecast area
across northeast Iowa and southwestern WI in an Enhanced risk
(Threat level 3 of 5) to address this potential. However, many
questions remain such has how any prior convection`s outflow
could affect the environment and available instability for this
MCS. As a result, will be very important to stay tuned to
upcoming forecast updates as mesoscale details become more fine
tuned.
Regardless, if storms materialize will want to watch the heavy rain
potential as well with precipitable waters of around 2" and fairly
respectable warm cloud depths (around 3.5 km in the 14.12 NAM)
which would lead to some efficient rainfall makers. While the
14.12z EC/GEFS ensemble generally only has medium probabilities
(30-60% chance) or over 0.5" through Monday night, the 14.12z
HREF ensemble max paints spots of 2-3" over the next 48 hours
which would suggest areas that receive repeat rounds of storms
could see locally heavy rainfall amounts. As a result, when
considering prior rainfall from yesterday of anywhere 2-5"
leading to saturated soils, localized flash flooding may be
possible.
Cooler and Dry Pattern Begins Tuesday:
Going into Tuesday, a broad scale synoptic trough pivots its way
into our region, aiding in the shove cold air advection further
south resulting in a cooling trend through the middle of next week.
As a result, the 14.00z grand ensemble (GEFS/EC ensemble/Canadian
ensemble) with an inter-quartile range of highs at La Crosse
for Wednesday of 71 to 76 with a median of 74. Median
temperatures in the grand ensemble generally trend in the middle
70s to lower 80s. Additionally, with increasing subsidence with
surface high pressure building in mid-week, would expect
minimal precipitation chances through Friday.
&&
.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 1005 PM CDT Sun Jul 14 2024
Much of the showers and storms will remain south and southeast
of the TAF sites overnight. On Monday, there will be 2 areas of
showers and storms moving southeast through the region. The
first will move through the morning. This one looks to be
weakening, so did not include precipitation at KLSE. The other
one moves in during the afternoon. Still some uncertainty on
the strength of these storms, so just went with vicinity showers
at the TAF sites.
With the light winds overnight, decided to add BCFG between
15.09z and 15.13z for KLSE.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&
$$
DISCUSSION...Naylor
AVIATION...Boyne
Area Forecast Discussion
National Weather Service State College PA
1126 PM EDT Sun Jul 14 2024
.SYNOPSIS...
High pressure will remain near Bermuda for the first part of
this week, resulting in a prolonged heat wave over the region. A
cold front will push southeast across Pennsylvania late
Wednesday, then high pressure will build in from the Great Lakes
late in the week.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
The main feature of interest in the near term forecast is a mid
level shortwave entering Western PA, which is progged to track
across Central PA late tonight. Modest height falls and surging
pwats ahead of the shortwave supports at least a slight chance
of an overnight shower over much of the area. Can`t rule out a
tsra across the Susq Valley, where RAP indicates higher
instability overnight.
The entire region will remain very warm and humid overnight with
increasing clouds and an overall uptick in humidity ahead of
the upstream shortwave aiding in keeping temps up. See no reason
to deviate from NBM min temps, which range from the mid 60s in
the coolest northern valleys to the mid 70s in the more
urbanized spots of the Lower Susq Valley.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
Diurnal heating, combined with the approach of shortwave over
the Grt Lks, should result in scattered convection Monday
afternoon/early evening. Modest instability/shear profiles could
support some multicell storm organization and the threat of
isolated severe weather, mainly over Northern PA where progged
mid level flow is strongest. Convection should dissipate after
sunset, as the shortwave passes east of the area.
The more-certain wx trouble is the heat. Have converted the
watch to a warning for Mon and Tues. Wed also looks hot, but
more like advy numbers for the SE only. To keep confusion to a
minimum and play up the danger in the nearer two days, we`ve
chosen to make the simple change to a warning for Monday and
Tuesday at this point and left Wed out of it.
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
Heat wave peaks Tuesday afternoon, as a large Bermuda high
pumps increasingly hot and very humid air into CPA. 850mb temps
rising to around 22C supports highs peaking between 90-100F with
max heat indices 100-105F southeast of the Alleghenies. High
confidence in excessive heat risk lead to the issuance of a heat
advisory for the south central mountains and Middle Susquehanna
Valley Mon & Tue and an excessive heat warning for the Lower
Susq Valley, where max heat index around 105F appear likely.
A round of at least semi-organized/possible severe convection
is possible Tuesday PM ahead of cold front pressing southeast
through the Great Lakes toward Lake Erie. However, a better
chance of more widespread showers/tsra is in the cards for Wed
PM with the passage of the front.
All medium range guidance supports a return to fair and
seasonable weather with much lower humidity late in the week, as
high pressure builds southeast from the Grt Lks. Will maintain
just a slight chance of convection along the southern tier
Thursday to account for some uncertainty regarding how far the
dying cold front makes it south of the Mason Dixon Line.
The stalled front is likely to return northward next weekend,
resulting in the return of diurnal convection, mainly over the
southern counties.
&&
.AVIATION /03Z MONDAY THROUGH FRIDAY/...
Line of showers/storms moving east across Ohio continues to
weaken, but still expecting BFD and possibly JST to see a few
showers from this later on this evening.
Overnight, BFD stands the best chance (50-60%) of seeing MVFR
ceilings while all other sites see much lower probabilities and
thus have maintained VFR conditions at all other sites. Given a
good deal of cloud cover, have opted to maintain VFR
visibilities at this time with fog more confined to deeper
valleys. Sub-VFR probabilities for visibility cap out at 30-40%.
Monday will bring a better chance of showers and storms in the
afternoon and evening. The highest probability of having a
storm will be in BFD, UNV and IPT, as there will be a weak
trough swing down from the north. Still too early to nail down a
specific time for TSRA/CB mention.
A real/potent cold front does look like it will finally pass
through in mid-week (Tues night or Wed) and bring a drier
airmass behind it.
Outlook...
Tue...Scattered, mainly aftn, SHRA/TSRA possible.
Wed...More widespread SHRA/TSRA, with brief restrictions likely.
Thu...Lingering -SHRA diminishing.
Fri...no sig wx.
&&
.CLIMATE...
The duration of warm nights is noteworthy. Here are the longest
stretches with temperatures at or above 70F on record at
Harrisburg.
# OF DAYS DATES YEAR
17 7/19-8/04 2020
13 8/16-8/28 2021
13 7/13-7/25 2010
12 7/18-7/29 2022
12 7/17-7/28 1999
12 7/20-7/31 1940
11 8/04-8/14 1977
10 8/10-8/19 2016
10 7/14-7/23 2013
10 8/01-8/10 1968
10 7/21-7/30 1898
9 12 times, most recently 7/3-7/11/2020
8 7/04-7/12 2024
.................................................
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
Heat Advisory from noon Monday to 8 PM EDT Tuesday for PAZ019-
025>028-034-035-045-046-049>053-058.
Heat Advisory until noon EDT Monday for PAZ036-056-057-059-
063>066.
Excessive Heat Warning from noon Monday to 8 PM EDT Tuesday
for PAZ036-056-057-059-063>066.
&&
$$
SYNOPSIS...Fitzgerald
NEAR TERM...Fitzgerald
SHORT TERM...Fitzgerald/Dangelo
LONG TERM...Fitzgerald/Bowen
AVIATION...Guseman/Dangelo
CLIMATE...Evans
Area Forecast Discussion
National Weather Service Cheyenne WY
937 PM MDT Sun Jul 14 2024
.KEY MESSAGES...
- Red Flag Warning for the majority of southeast Wyoming and
portions of the Nebraska Panhandle today. Dry thunderstorms
will become scattered to numerous, and possible fire starts
from lightning strikes may occur.
- Very hot temperatures will continue through Monday. Heat
Advisories remain in effect for the High Plains along and east
of I-25.
- Increased precipitation chances and cooler temperatures are
expected late Monday through Wednesday.
&&
.SHORT TERM /THROUGH TUESDAY/...
Issued at 145 PM MDT Sun Jul 14 2024
High based thunderstorms beginning to develop across parts of
the CWA at 1PM. Seeing lightning strikes across central Laramie
County near Cheyenne...and out in Carbon County from Rawlins to
Arlington. Beginning to see development across Albany County and
southern Platte County as well. Looking at GFS forecast
soundings...18Z PWATS range from 0.6 inches out near Rawlins to
0.7 inches in the Panhandle. There is a surface trough analyzed
along a line from Pine Bluffs to Casper along the east slopes of
the Laramie Range. An upper level vort max moving through the
ridge this afternoon providing some upper level lift which will
set us up for a pretty significant dry lightning event the
remainder of this afternoon into this evening.
Looking at HRRR and RAP simulated radar...convection blossoms
after 22Z along the Laramie Range with high based storms moving
into the Panhandle through 03Z-04Z. Given very dry air in the
lower elevations...storms will be high based and mainly dry.
Given what we are seeing currently...will keep the Red Flag
Warnings going as they are through 10 PM this evening. Local
fire customers will need to be on alert for increased fire
starts with these dry thunderstorms through mid to late evening.
PWATS on the increase for Monday...increasing to an inch across
southeast Wyoming and near 1.2 inches in the Panhandle. Better
chances for wetting rains. ECMWF/SREF/NAM and GFS all showing
fairly widespread QPF across the CWA. Continued high PoPs (50-80
percent) Monday afternoon and evening...that dissipate towards
06Z.
These diurnally driven showers and storms will continue Tuesday
with good chances for afternoon and evening storms. Long/skinny
CAPE profiles suggest storms capable of producing heavy rainfall
with these increased PWATS.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
Issued at 431 AM MDT Sun Jul 14 2024
For the extended period, weather across SE WY and E NE will be
dominated by a persistent ridge of high pressure over the western
half of the United States. A broad upper trough centered over
Ontario at the beginning of the period will shift east into Quebec
by Thursday, allowing the western ridge to expand north and east
causing height rises and weakening flow aloft through Saturday.
Abundant mid-upper level mositure will continue to round the ridge
over WY and W NE. At the surface, persistent southerly/southeasterly
flow will keep low-mid-50s dew points in W NE through the weekend.
Confidence in the large scale evolution through Saturday is high
given ensemble and deterministic model agreement. By Sunday, models
begin to diverge on the timing of a trough digging into the
northwest US, which may begin to break down the ridge for the end of
the weekend and start of next week.
For Wednesday, showers and thunderstorms look to be most abundant
for this day given the position of the ridge allowing for better
flow aloft and embedded disturbances to force development. With PW
values ranging from 0.75" to over 1" over much of E WY and W NE,
above normal for this time of year, storms that develop could
produce heavy rainfall. Flash flooding potential will be enhanced by
relatively slow storm movement. Both Instability (adequate moisture
beneath steep ll and ml LRs) and borderline deep layer shear (still
decent flow aloft) should support a strong-severe storm, especially
further east into NE. Temperatures across the region will be the
coolest of the forecast, with highs ranging from the low to mid 80s
for most. Confidence in the general precip+temp forecast for Wed is
moderate-high, with details regarding exact location of storms and
severe potential low-moderate.
Thursday through Saturday, as the ridge expands and heights rise,
flow aloft will weaken, and temperatures will rebound. Although deep
layer shear and instability will be slightly weaker, abundant
moisture aloft and very deep inverted V profiles will support
showers and storms producing gusty winds, along with a dry lightning
potential, especially further into WY. The strongest thunderstorm
potential will be confined to W NE where ll mositure and shear will
be best. High temps each day are expected to rise into the upper 80s
to low 90s for the lower elevation areas. Confidence in the forecast
during this period is moderate, while that in thunderstorm intensity
is low given cross-model and run-run inconsistencies in the degree
of ll moisture return and extent during this period.
Sunday and beyond, the upper trough digging into the US should
dampen the ridge at some point impacting our sensible weather.
However, timing and impact differences yield low confidence in when
and what that impact will be.
&&
.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 932 PM MDT Sun Jul 14 2024
West northwest flow aloft will continue, with low and mid
level moisture increasing on Monday, producing increasing
chances for late day showers and thunderstorms.
Wyoming TAFS...Scattered to broken clouds near 10000 feet will
continue. Expect thunderstorms in the vicinity after
00Z Tuesday. Winds will gust to 25 knots at Cheyenne from 12Z
to 00Z, and to 23 knots at Rawlins and Laramie from 15Z to 00Z.
Nebraska TAFS...Scattered to broken clouds from 8000 to
10000 feet will continue. Thunderstorms will be in the vicinity
after 00Z Tuesday. Winds will gust to 25 knots at Sidney from
15Z to 20Z.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...Red Flag Warning until 10 PM MDT this evening for WYZ417-418-
425-428>433.
Heat Advisory until 10 PM MDT this evening for WYZ101-102-107-
108-118-119.
NE...Heat Advisory until 8 PM MDT Monday for NEZ002-003-019>021-054-
055-095-096.
Red Flag Warning until 10 PM MDT this evening for NEZ435>437.
&&
$$
SHORT TERM...GCC
LONG TERM...WFOCYS
AVIATION...RUBIN
Area Forecast Discussion
National Weather Service Des Moines IA
644 PM CDT Sun Jul 14 2024
...Updated for the 00z Aviation Discussion...
.KEY MESSAGES...
- Enhanced Severe Storm Risk Monday with potential of
significant damaging wind gusts over 70 mph
- Heat Advisory in place to this Evening and Monday South
- Cooler and Mainly Dry Tuesday through Sunday
&&
.DISCUSSION...
Issued at 252 PM CDT Sun Jul 14 2024
.Short Term /Tonight through Monday Night/...
Confidence Short Term: Low to Medium
Several competing factors in the short term forecast again this
period with regard to precip chances. Heat remains the constant for
now, though debris clouds from leftover convection will modulate
highs a bit again today in some areas. Weak synoptic surface
features remain over the region. Aloft at H700, the leading edge of
the cap of 10C was over eastern Iowa at 12z. This did allow the two
MCS to increase in strength around sunrise as they reached the
eastern extent of the H700 cap. The approaching wave/MCS from South
Dakota has now entered the region of warmer air aloft and
correspondingly diminished over northern Iowa as anticipated. By
this afternoon, some increase in storm coverage is expected as the
H700 wave over the Northern Plains tracks east into Iowa this
evening and crosses the state overnight. The synoptic models
(EC/GFS) are holding the H700 cap over Iowa through the overnight.
CAMS, particularly the HRRR and ARW cores are showing some weakness
in the cap again over eastern Iowa by 21-23z this afternoon. Though
no solution is heavily favored over the other, we will keep some
thunder chances this afternoon over the northeast along the US20 to
US30 corridors. Tonight the main areas of convection should hold
north of Iowa until late in the period when some storms may cross
into northern Iowa prior to sunrise as a stronger MCS moves through
southern Minnesota and Wisconsin. Lows tonight will fall to the
upper 60s to lower 70s in the north while the central to south will
remain in the mid 70s. Tomorrow lingering debris clouds north and
the sagging surface boundary will hold temperatures in the 80s north
while the south again will be in the 90s with heat indices in the
100s. Tomorrow will be similar to today with regard to timing out
convection. We will still be battling the H700 cap for a portion of
the day into the afternoon hours. The main difference tomorrow is
the added surface moisture convergence along the boundary moving
through the region, plus increasing shear during the day and
afternoon. CAMS are now showing some earlier initiation with late
morning into early/mid afternoon firing of convection along the
sagging boundary into central Iowa. Upper level wind fields are
looking more favorable for a potential severe bowing system
with more significant damaging thunderstorm winds into the
afternoon hours. Still a fair amount of uncertainty with
initiation and placement, but a corridor between US20/I80 and
around or slightly east of I35 is more favored at this time. SPC
is upgrading SWODY2 to enhanced over central to eastern Iowa
with this potential in mind. Will need to monitor trends
overnight into early Monday morning with regard to outflow,
approaching upper level system and model convective trends.
After the main area of early afternoon convection exits the
region, we will still see trailing convection along the boundary in
the evening into overnight hours south as the front sags into
northern Missouri. With upper level return flow over the boundary,
more storms will be possible through Tuesday 12z in this area.
Lows Monday night will fall to the lower 60s north to the lower
70s in the south.
.Long Term /Tuesday through Sunday/...
Confidence: Medium to High
After tomorrow`s potential significant convection, we will get a
welcomed break from storms, heat and humidity through the end of the
period. Still looking on track for highs to cool to the 70s to
lower 80s with lows in the 50s to lower 60s for much of next week.
There is some uncertainty late in the period with regard to return
moisture, but some showers may advance back into western section
around next Sunday.
&&
.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 644 PM CDT Sun Jul 14 2024
A cluster of thunderstorms this evening is impacting KALO. While
precipitation will pass near to just south of the terminal,
lighting will be a threat for the next hour. Activity this
evening should remain clear of other TAF sites. Confidence
decreases on Monday morning as there is the potential for
convection across northern and eastern terminals. Timing and
location have been difficult to pin down and will depend greatly
on how the current storms in Iowa and overnight convection
across the midwest play out. Therefore have kept to VCTS
mentions and will need to update later as confidence increases
in the details.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
Heat Advisory until 8 PM CDT this evening for IAZ004-015-023-
024-033>035-044>048-057>062-070>075-081>086-092>097.
Heat Advisory from 1 PM to 8 PM CDT Monday for IAZ057>062-
070>075-081>086-092>097.
&&
$$
DISCUSSION...REV
AVIATION...Hagenhoff
Area Forecast Discussion
National Weather Service Sioux Falls SD
1053 PM CDT Sun Jul 14 2024
.KEY MESSAGES...
- High humidity with temperatures in the 80s and 90s will lead
to heat index values of 95 to 105 degrees. Heat Advisory
remains in effect for areas along and south of I-90 until 8
PM.
- An area of thicker wildfire smoke can be seen on satellite
advecting into south central SD. This moves east through the
evening along the southern MO River Valley and northwestern IA;
however, no surface impacts are currently expected.
- Showers and storms are possible tonight through late Monday
morning, although confidence is very low in coverage and
timing. Strong to severe storms are possible if storms develop,
with all hazards possible.
- Unsettled pattern continues into mid/late next week with
periodic low shower and storm chances. Starting Tuesday,
temperatures will be near to below normal for this time of
year.
&&
.DISCUSSION...
Issued at 236 PM CDT Sun Jul 14 2024
CURRENTS THROUGH MONDAY: Morning cloud cover has diminished/moved
east, although diurnal cumulus is developing across the region. Also
noting an area of thicker wildfire smoke over south central SD;
however, no surface impacts are expected at this time as it moves to
the southeast through the evening hours. Temperatures continue to
climb into the 80s and lower 90s. Despite being a bit cooler than
yesterday, dew points in the mid 60s to mid 70s raise heat indices
into the mid 90s to 105 degrees F. Maintained the on-going Heat
Advisory for areas along/south of I-90.
Now, attention turns to chances for showers and storms overnight
through Monday. Models continue to struggle this run in resolving
short wave trajectories over the area during this time, including
source region (ND v.s. western SD), timing (tonight v.s. mid
day Monday), strength, and number of waves. This leads to very
low confidence in convective chances through Monday afternoon.
In one camp of models, the main short wave ejects out of ND late
tonight bringing a complex of storms into portions of
southwestern/central MN as it collides with a surface boundary.
This scenario is mostly evident in the NAMNest, ARW, and some
runs of the HRRR today. The FV3 is in a similar camp, although
is much further to the west (bringing the storms to areas west
of I-29). Some of the guidance (a couple of HRRR runs and the
RAP) either don`t have this feature or shift it much further
east in MN. Another short wave is progged to move into the area
later Monday morning, and depending on where the boundary ends
up after any overnight convection, this may be a catalyst for
additional storm development in the late morning tomorrow
along/south of I-90. The NAMNest is the most aggressive with
this development in northeastern NE, quickly growing upscale
along the front into northwestern IA. Given all the uncertainty,
generally tried to use an average of the hi-res models and
previous forecast for pops. If storms are able to advect into
or develop over our area into late Monday morning, they could
quickly become strong to severe. MUCAPE is generally 1500 J/kg
or higher (at times approaching 3000+ J/kg), bulk shear of 35+
knots, and steep mid level lapse rates of over 8 deg C/km
support wind gusts to 70 mph and golf ball sized hail. Based on
last night/early this morning`s storms, would not be entirely
surprised if a stronger complex of storms produces wind gusts to
80 mph. Can`t rule out a tornado or two with the surface
boundary hanging around, low LCLs, and 0-1 bulk shear around 20
knots. Locally heavy rain is possible as PWATs sit between 1.5
and 2 inches. Not anticipating widespread flooding issues as
convection is expected to be fairly progressive.
Lows tonight in the upper 60s to lower 70s. Highs tomorrow will be
highly dependent on morning convection, cloud cover, and how far
south the boundary is. Seasonal temps expected with highs in the 80s
to lower 90s. High dew points push heat index values into the upper
90s to near 100 in the southern MO River Valley into northwestern
IA.
MONDAY NIGHT AND TUESDAY: As the boundary moves south Monday night,
CAA begins to filter in, bringing cooler temperatures. A couple of
weak waves bring some occasional precip chances to the area, but
severe weather is not expected. Lows in the upper 50s to mid 60s.
Highs Tuesday will be slightly below average thanks to the CAA
and cooler surface high pressure moving in. We`ll only warm into
the mid/upper 70s to lower 80s.
MID WEEK ONWARD: Surface high pressure meanders south around
the northern/central Plains mid week, sliding east into the Great
Lakes late week. Northwesterly flow regime and CAA to neutral
advection keep temperatures cooler than average. Highs in the
70s to mid 80s and lows in the 50s to lower 60s. A few weak
waves could bring some shower and storm chances to the region,
but probability is low (< 30%). Synoptic pattern becomes more
amplified later in the period as troughing digs in over the
eastern US and high pressure deepens over the Southwest.
&&
.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 1053 PM CDT Sun Jul 14 2024
VFR conditions begin the TAF period. Showers and storms have
developed across North Dakota late this evening and look to grow
into a complex as they progress southeastwards through the night.
The storms look to remain along and northeast of a De Smet, SD to
Luverne, MN to Spencer, IA line. While away from all TAF sites, have
included VCSH in KFSD`s TAF as some trailing showers could impact
the terminal. Should see the complex of storms push east/southeast
of the area by mid morning tomorrow.
A second round of lighter showers is possible during the afternoon
hours but confidence is only high enough to include in KHON and
KFSD`s TAFs as of now. A cold front will push through the area
during the morning hours which will turn surface winds to out of the
north. More storms could develop during the afternoon hours on the
cold front but confidence is low in where storms could develop at
this time. Any chance for showers and storms will push
east/southeast of the area by the evening hours, leaving light
northerly winds to finish out the TAF period.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
IA...None.
NE...None.
&&
$$
DISCUSSION...SG
AVIATION...Meyers
Area Forecast Discussion
National Weather Service Hastings NE
622 PM CDT Sun Jul 14 2024
.KEY MESSAGES...
- A Heat Advisory remains in effect through 8PM this evening for
Valley, Greeley, Sherman, Howard, and Nance counties in
Nebraska. Heat index values as high as 105 degrees are
expected.
- A Heat Advisory is also in effect for all counties along and
south of Interstate 80 as well as Merrick and Polk counties in
Nebraska, and for the entirety of north central Kansas,
through 8PM Monday. Heat index values as high as 110 degrees
are expected.
- Cooler temperatures are expected Tuesday through the end of
the week, with high temperatures in the 80s Nebraska to around
90 over northern Kansas on Tuesday and then in the 70s and
80s Wednesday into next weekend.
- Several small 20% chances for precipitation most
evenings/overnights, with the best chance Tuesday evening into
Tuesday night (30-60%).
&&
.DISCUSSION...
Issued at 304 PM CDT Sun Jul 14 2024
This Evening into Tonight...
It will be another warm muggy night with a slight chance (20%)
that a few thunderstorms that develop west of our area could
possibly slip into our western forecast zones mainly after 10
PM. Severe weather is not expected and the marginal risk area
for today has been removed from the forecast. Any thunderstorms
that can make it into our western forecast area should be
dieing out as they move in or shortly after.
Monday (Last Hot Day For Now)...
Our Kansas zones will most likely still be baking with over 105
heat index values. However, northern zones will start to see
some relief from the heat as a cold front slides southeast
through the day. The NBM does indicate a pretty good spread in
possible temperatures for this time of year leading towards more
uncertainty in the Tri-Cities area due to frontal timing and
cloud cover. However, heat index values in the Tri-Cities should
still get over 100 for at least a little while and may still
briefly hit 105 in some spots. The 18Z HRRR is one of the more
aggressive models when it comes to evening thunderstorms moving
in from the west and a little more aggressive than recent runs.
Therefore, have increased POPs a bit above 20% NBM values, and
closer to 30 percent favoring areas south and southwest of I-80.
There is a marginal risk and we could see some isolated severe
weather along and behind the cold front mainly during the later
evening hours.
Tuesday (Cooler and Best Chance for Rain)...
The NBM temperature spread tightens up a bit in the 80s across
Nebraska, while Kansas zones may still hit 90. Agree with NBM
guidance that this is probably our best chance for a more
widespread appreciable rainfall across the area. However, the
most favored zones will be from about the Tri-Cities and points
to the southwest and south (40-60%). Locations northeast of the
Tri-Cities will see lower rainfall chances 30-40%. Again can
not rule out a few isolated marginally severe storms.
Wednesday through next Weekend...
We will remain under the influence of a cooler northwesterly
upper level flow pattern that will result in highs only in the
upper 70s and 80s. Rainfall chances are not great, but within
this flow pattern there will be weak shortwaves passing through
resulting in several mainly small (20-30%) rain chances that
tend to favor evening and overnight periods.
&&
.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 615 PM CDT Sun Jul 14 2024
For KGRI/KEAR Airports:
High confidence VFR conditions through the period with some
elevated haze and scattered passing high clouds. East
southeasterly winds near 10 KTS this evening will gradually
subside overnight while becoming more southerly, eventually
shifting and becoming northwest behind a cold front Monday
afternoon. While an increase in mid/high level clouds will
likely be observed with this front Monday afternoon, no
precipitation is anticipated through the valid TAF period.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...Heat Advisory until 8 PM CDT Monday for NEZ048-049-060>064-
072>077-082>087.
Heat Advisory until 8 PM CDT this evening for NEZ039>041-046-
047.
KS...Heat Advisory until 8 PM CDT Monday for KSZ005>007-017>019.
&&
$$
DISCUSSION...Wesely
AVIATION...Rossi
Area Forecast Discussion
National Weather Service Goodland KS
1000 PM MDT Sun Jul 14 2024
.KEY MESSAGES...
- Potentially damaging wind gusts this evening.
- Heat Advisory remains in effect for all but far eastern
Colorado Monday.
- Cooler (less hot) temperatures and a bit better chance for
rainfall for much of next week.
&&
.SHORT TERM /THROUGH MONDAY NIGHT/...
Issued at 500 PM MDT Sun Jul 14 2024
Tonight...isolated to scattered showers/thunderstorms are
anticipated to move from west to east through about 12 AM MDT (1
AM CDT), impacting those generally west of a line from near
McCook to Colby and Oakley. The primary hazard will be wind
gusts up to 65 mph. HRRR is showing a potential for heat bursts
after about 10 PM MDT as shower/thunderstorm activity
dissipates. Low temperatures are forecast to be in the middle
60s to middle 70s.
Monday-Monday night...we`ll have another chance for showers and
thunderstorms from late afternoon through the overnight hours as
a better organized weather system moves through from the
northwest. A few severe thunderstorms will be possible. High
temperatures are forecast to be in the middle 90s to around 107
with low temperatures in the lower 60s to lower 70s. Heat
indices as high as 107 are forecast (Norton/Graham counties).
Tuesday-Tuesday night...We`ll have a lull in precipitation
chances until late afternoon when another weather system moves
through from the west-northwest. Presently we have likely pops
(60%) for overnight thunderstorm chances. High temperatures
return closer to normal for early July with upper 80s to lower
90s forecast. Low temperatures also near normal in the upper 50s
to middle 60s.
Wednesday-Wednesday night...lingering moisture in the 850-500mb
layer in the northwest flow aloft will continue to support daily
and overnight chances for rainfall. Presently we have 20%-70%
chances during the day with 20%-50% chances overnight. With
cooler temperatures aloft and quite a bit of cloud cover, high
temperatures look to be below normal with 80 to 85 degrees
forecast. Low temperatures are forecast to be in the upper 50s
to lower 60s.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
Issued at 500 PM MDT Sun Jul 14 2024
Slightly below normal daytime highs in the 85 to 90 degree range
are forecast with low temperatures a few degrees either side of
60. Daily rainfall chances are in the 20% to 30% range in
general as weather systems move through from the northwest.
&&
.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1000 PM MDT Sun Jul 14 2024
KGLD...VFR conditions are expected through the period. A
southerly wind up to 10kts is expected at taf issuance, veering
to the west at similar speeds through 12z. Winds continue to
veer to the north through the day Monday at speeds up to 11kts
or so. For Monday evening, winds remain generally from the north
around 11kts. Showers and thunderstorms could be near or over
the terminal after about 22z Monday with a bit better chance
after about 03z as the next weather system moves through. The
primary hazard would be strong gusty winds. Given overall
coverage and timing, I will not be including any mention in the
forecast at this time.
KMCK...VFR conditions are expected through the period. A light
and variable wind is forecast from taf issuance through 14z.
From 15z-01z, west winds veer to the north then northeast,
gusting up to 20kts or so after 23z. After 02z, winds remain
from the northeast around 11kts. Regarding shower and
thunderstorm chances, presently the best chance for any to be
near or over the terminal is after about 03z. Similar to KGLD,
the primary hazard will be strong gusty winds. There wont be a
mention of thunderstorms in this taf forecast.
&&
.CLIMATE...
Issued at 423 AM MDT Sun Jul 14 2024
Sunday high temperature records
Record Year
Yuma 105 2010
Burlington 105 1925
Goodland 107 1934
Tribune 107 1934
Colby 109 1934
McCook 109 1954
Hill City 113 1934
Monday high temperature records
Record Year
Yuma 102 2006
Burlington 103 2000
Goodland 106 1925
Tribune 108 2000
Colby 108 1925
McCook 112 1925
Hill City 113 1934
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...Heat Advisory from 9 AM MDT /10 AM CDT/ to 8 PM MDT /9 PM CDT/
Monday for KSZ001>004-013>016-027>029-041-042.
CO...None.
NE...Heat Advisory from 9 AM MDT /10 AM CDT/ to 8 PM MDT /9 PM CDT/
Monday for NEZ079>081.
&&
$$
SHORT TERM...99
LONG TERM...99
AVIATION...99
CLIMATE...
Area Forecast Discussion...Updated
National Weather Service Lincoln IL
747 PM CDT Sun Jul 14 2024
.KEY MESSAGES...
- Intense heat continues tomorrow, with heat indices of 100-110
degrees during the day. Not much relief is given overnight with
lows in the mid to upper 70s.
- Some relief from the heat comes Wednesday as a cold front pushes
through central and southeastern Illinois over night Tuesday.
The CPC shows a below normal trend on temperatures for the next
14 days.
- Multiple MCS passages are forecast for the coming days before a
brief break starting Wednesday. Some of these storms have the
potential to be severe with damaging winds as the main risk.
&&
.UPDATE...
Issued at 746 PM CDT Sun Jul 14 2024
This evening, a broken line of thunderstorms has developed from
near Rockford SW across the Quad Cities. Strong instability in
excess of 3000 J/kg is in place ahead of this line of storms. 00Z
ILX sounding showed a "loaded gun" setup with around 3000 J/kg
MLCAPE and -68 J/kg MLCIN. Deep layer shear in the region is
marginally sufficient (around 25-30kt) to support organized
convection this evening and do anticipate storms to congeal into a
more organized line over the next few hours. Cloud bearing flow
and forward propagating corfidi vectors will generally steer these
storms west-to-east across northern Illinois with some potential
of clipping our far northern CWA where a severe thunderstorm watch
is currently in effect. Damaging wind gusts will be the primary
hazard with these storms. That said, veering LLJ this evening will
help the southwestern end of the line back-build with upshear
Corfidi vectors suggesting storms will propagate S/SW late this
evening into portions of the area. Where this occurs, a heavy rain
threat is possible due to the slow moving nature and training of
storms. Latest HRRR suggests a few pockets of around or just in
excess of 2 inches of rain is possible north of I-72.
Deubelbeiss
&&
.DISCUSSION...
Issued at 214 PM CDT Sun Jul 14 2024
The MCS this morning skirted by the northern periphery of the CWA
without incident. This won`t be the only round that threatens
central Illinois. Currently, we are keeping a close eye on the MCV
that is propagating through north-central Iowa. The HRRR and
NAMNest depict the MCV and it`s reignited convection taking a
southerly dip once it gets to Illinois, with the NAMNest being the
most dramatic in its southern pull. The environment will have had
time to recover from the morning convection, as surface heating
occurs with the mostly clear skies, the moisture is far from gone
(as we can feel the soupy airmass outside), and the MCV (and
rebounding CAPE values) provides the needed lifting mechanism. By
mid afternoon, SBCAPE values rise to ~3000 J/kg ahead of the CI,
with very little to no cap. The main hazard as the next round
moves through will be damaging, gusty winds.
Tomorrow, the severe threat continues, but this time bigger and
better than before. Another complex is expected to develop over Iowa
by late morning and move eastward. Its track has it entering the
northern CWA by late afternoon between 22-00z. As it does, the
environment is primed. The cap is very little (~-20 J/kg),
allowing the line to become surface based. SBCAPE values ahead of
the line as it enters are 4000-5000 J/kg. The 0-6km bulk shear
looks to be around 40-50 knots. SPC has areas along and north of
I-74 outlooked for an Enhanced Risk (level 3 out 5). There is a
30% damaging wind risk with a 10% chance of wind gusts greater
than 65 knots for areas along and north of I-72. Localized flash
flooding is also in play for tomorrow as the area is already quite
saturated and PWATs are 1.8-2 inches at the time of the passage.
The heat won`t be taking a break tomorrow neither. Today the heat
indices are expected to top out between 100 and 105 degrees. The dew
points today and tomorrow will be in the upper 70s, getting very
close to 80. The 12z.14 HREF shows a 60% chance of dewpoint
exceeding 78 degrees tomorrow afternoon, ahead of the storm complex.
Heat indices are forecast to top out near 110 degrees tomorrow
(Monday). A cool down is expected starting Tuesday as a cold front
is set to move through, wiping out the moisture. Beyond Tuesday,
temperatures become slightly below normal for this time of year,
giving us the well needed break from the soupy heat. Highs will be
around the upper 70s to mid 80s from Wednesday into the end of the
forecast period.
There are some additional rain chances through early Thursday
morning, then will be dry through Sunday. This break should give the
area a chance to breathe after the multiple rounds of heavy rain
recently.
Copple
&&
.AVIATION... (For the 00z TAFs through 00z Monday Evening)
Issued at 631 PM CDT Sun Jul 14 2024
Scattered storms upstream over eastern Iowa will be the focus for
any activity spreading south into central Illinois later tonight.
Confidence remains low in timing and placement, but the better
chances for any storms will be at our northern 3 TAF sites (PIA,
BMI, CMI). PROB30 groups are noted at each of these airfields
between 04-10Z. South-southwest winds will become light overnight
then turn breezy tomorrow afternoon. Mostly VFR conditions will
be seen outside of storms, with another round of convection
possible Monday evening.
NMA
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
Heat Advisory until 8 PM CDT Monday for ILZ027>031-036>038-
040>057-061>063-066>068-071>073.
&&
$$
Area Forecast Discussion
National Weather Service Northern Indiana
920 PM EDT Sun Jul 14 2024
.KEY MESSAGES...
- There are periodic chances for showers and storms (20 to 60%) tonight
through Tuesday night, with one or more rounds of strong to
severe storms possible during this timeframe.
- Best chances for severe weather will be on Monday late
afternoon into the evening, when there is an Enhanced Risk
(level 3 of 5) for severe weather. Damaging winds 60-75+ mph
and a few tornadoes possible.
- Alongside the severe threat, flooding is also possible in any
storms, especially in areas that remain saturated from the
remnants of Beryl.
- Hot and humid Monday, depending on storm coverage, timing, and cloud
cover. Afternoon heat indices mid 90s to near 100 degrees.
- Cooler, drier weather is anticipated midweek through next
weekend.
&&
.UPDATE...
Issued at 919 PM EDT Sun Jul 14 2024
Previous forecast trends were maintained, with only small update
item of note to slightly increase PoPs across northwest half of
the area late evening into the overnight.
Compact convectively enhanced vortex continues to track east
across northwest/north central Illinois this evening with ring
of convection initiating over the past few hours from eastern
Iowa into southern Wisconsin and northern Illinois. Background
synoptic shear remains marginal, but RAP analysis suggests a
small pocket of 35-40 knot effective shear associated with this
small scale vort max. Despite this, convection has been rather
loosely organized up to this point with several storm
mergers/interactions across NW Illinois and some periodic signs
of some mid level rotation due to these mergers. Still
expecting these storms to congeal into a more linear feature
late this evening/early overnight as they track east. Upstream
00Z RAOBs from KILX/KDVN indicates very strong instability with
3000-3500 MLCAPEs.
Earlier stabilizing effects from northern Indiana early day MCS
will be eroded by westerly advection of this better upstream
instability axis along with eastward progression of some better
mid level lapse rates. Some low level CIN is expected to develop
this evening locally for mixed layer parcels however, so some
question as to the vigor of this convection as it tracks east
into a slightly less unstable environment locally. There could
be some tendency for more vigorous storms to develop upwind
across central/east central IL as northern portion of the storms
across southern Great Lakes become more outflow dominant. Some
isolated severe threat still appears to be intact west of US 31
locally in the 05Z-08Z period with a period of potential gusts
into the 40 to 60 mph range. Hail threat should be tempered with
eastward extent as storms congeal later this evening. Locally
heavy rainfall will be some concern across the west tonight,
especially considering recent heavy rainfall over the past week.
&&
.DISCUSSION...
Issued at 231 PM EDT Sun Jul 14 2024
Multiple rounds of storms are expected over the next 48 hours, with
one or more rounds being strong to severe. Our CWA is on the
periphery of a building ridge in the Plains, and with northwest
steering flow, this puts the Upper Midwest and Great Lakes regions
in a very favorable zone for storms. Several strong shortwaves that
drop into the Midwest in the coming days may help to sustain several
rounds of MCSs. SPC has us in a Day 1 Slight Risk (level 2 of 5), a
Day 2 Enhanced Risk (level 3 of 5), and a Day 3 Marginal Risk (level
1 of 5). The next 48 hours come with a lot of uncertainty in the
coverage, timing, and number of rounds of storms. Alongside the
severe threat, flooding is also possible with any of the MCSs. Many
locations, especially in the Wabash and St Joseph river basins, have
had 5 to 8 inches of rain this week. With saturated ground and
elevated rivers, it won`t take much for these areas to experience
more flooding. High PWATS of and the potential for storms to
backbuild along outflow boundaries has me concerned about flooding
potential in addition to the multi-day severe threat.
As the initial round of storms today has now exited the area,
dry conditions will return for the next several hours before yet
another chance for storms. Hi-res models have yet to come to a
strong consensus, but it is looking more plausible (medium
confidence) that an MCS will develop over eastern IA/northwest
IL late this evening and move eastward into our CWA between 10
PM to 12 AM EDT tonight. With ample MLCAPE 2000-3000 J/kg and
DCAPE 1000+ J/kg, damaging winds would be the main hazard
overnight. The greatest confidence in severe weather is along
and west of US 31, as the MCS should weaken as it pushes
eastward overnight.
There is increasing confidence in severe weather Monday late
afternoon and into the evening. SPC has introduced 30% hatched wind
probabilities into the Day 2 Outlook, prompting the need for a
Enhanced Risk (level 3 of 5) upgrade across northern Indiana.
Another progressive MCS/bow-echo could develop upstream of a much
more favorable environment and ride along the highest theta-e axis
through southern WI, northern IL, and into northern IN. Strong
buoyancy, increasing vertical shear, and favorable thermodynamics
(dewpoints low 70s, highs upper 80s to low 90s, MLCAPE of 4000
to 5000 J/kg) could certainly yield a high-end impact damaging
wind event. A derecho is possible with organized damaging winds
60-75+ mph and a few tornadoes possible.
Heat and humidity build on Monday, with highs in the low 90s and
heat indices potentially in the upper 90s to low 100s. Heat Advisory
headline could be needed. Uncertainty in storm coverage, timing, and
lingering cloud cover could all result in temperatures being lower
than what is currently forecasted.
An upper level trough will pivot through the Great Lakes on Tuesday,
resulting in chances for storms ahead of and along the front. A
continental, cooler airmass from Canada will sink south midweek,
resulting in seasonable highs in the 70s, a stark decrease in
humidity, and dry conditions.
&&
.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 755 PM EDT Sun Jul 14 2024
Temporary stabilizing effects from earlier convective complex
have allowed for mainly dry conditions through early this
evening. However, stronger westerly upstream flow will
overspread northern Indiana over the next several hours in
advance of next upstream mesoscale convective vortex across NW
Illinois. This will allow for recovery in instability via
advection. Convection has already initiated with this feature
with moderate to strong instability across these areas. This
showers and storms should encounter some instability gradient as
they reach into northwest Indiana, but localized stronger
shear/forcing with the small scale vort max should allow for
another round of thunderstorms at the terminals in the 04Z-08Z
timeframe. Strongest gusts to around 40 knots expected at KSBN
with these potential storms with brief IFR vsbys possible. These
showers and storms should wane late tonight, with next upstream
possible convectively enhanced short wave arriving toward end of
this valid period with more thunderstorm chances. Given a good
deal of uncertainty at that forecast distance in this pattern,
will omit mention in TAFs for now.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...Flood Watch through late Monday night for INZ012>015-020-022-
103-104-203-204.
OH...None.
MI...Flood Watch through late Monday night for MIZ078-177-277.
Air Quality Alert until midnight EDT tonight for MIZ177-277.
MARINE...None.
&&
$$
UPDATE...Marsili
DISCUSSION...Johnson
AVIATION...Marsili
Area Forecast Discussion
National Weather Service Morristown TN
1031 PM EDT Sun Jul 14 2024
...New UPDATE...
.UPDATE...
Issued at 1008 PM EDT Sun Jul 14 2024
Though they appear to be fading from radar since making changes,
did populate some showers for parts of the central plateau for the
next couple of hours. From about central plateau, to Knoxville, to
GSMNP and southward, mostly under two tenths of an inch was
recorded today from showers, that is if measuring equipment
captured it accurately. Highs today from mid-day climate verified
well against forecast. Everything else in the nearest term checks
fine besides some most recent obs being blended into the future
hourlies.
KS
&&
.SHORT TERM...
(This evening through Monday)
Issued at 306 PM EDT Sun Jul 14 2024
Key Messages:
1. Hot again on Monday with increasing moisture across the
southern valley and plateau.
2. Higher risk of diurnal convection on Monday afternoon, mainly
across the plateau and southern valley.
Discussion:
General persistence pattern continues with synoptic conditions
potentially resulting in slightly higher chances for diurnal convection
on Monday afternoon. Temperatures will be within a degree or two
of the past couple days with increasing moisture resulting in
higher heat index values between 100 and 105F for the southern
valley near Chattanooga.
While the 850mb ridge remains across the Southeast CONUS, a
weakness or col at 500mb will shift slightly eastward and will be
across Middle and West TN. These slightly lower heights aloft, and
increased moisture to our west, will result in some higher
convective coverage across the Midsouth and portions of the Lower
Tennessee River Valley. This is evident in RAP soundings which
show increasing moisture across the Cumberland Plateau and
portions of the southern valley near Chattanooga on Monday
afternoon. While LFC heights are around 3km this afternoon, they
lower to around 2km on Monday afternoon due to increased moisture.
Instability is also forecast to go from around 500 J/Kg this
afternoon to 1500 to 2500 J/Kg on Monday afternoon. This
thermodynamic environment will increase DCAPE to around 1000 J/Kg
across the plateau and southern valley on Monday afternoon with a
low risk for stronger, potentially severe thunderstorms capable of
damaging downburst wind gusts. Further north across the central
valley through northeast TN and southwest VA, drier air remains
with more limited rain and thunderstorm chances.
Daily Record High Maximum Temperatures
Date Chattanooga Knoxville Tri-Cities Oak Ridge
07-14 103(1954) 101(1954) 98(1954) 101(1954)
&&
.LONG TERM...
(Monday night through next Sunday)
Issued at 306 PM EDT Sun Jul 14 2024
.LONG TERM...
Key Messages:
1. Extreme heat will continue on Tuesday with highs in the mid to
upper 90s and heat index values into the 100s across much of the
area.
2. Scattered storms are expected on Tuesday with more numerous
coverage Wednesday and Thursday. Lower chances continue into this
weekend with temperatures dropping to below normal.
Monday Night through Thursday
At the start of the period, quasi-zonal flow will be in place aloft
with weak embedded shortwaves and surface high pressure receding to
the south. During this time, 500mb heights will still be above
5,900m with near record 850mb temperatures reaching to 21 Celsius by
the day on Tuesday. A shift to weak southerly flow will advect some
moisture into the area, which will increase humidity in comparison
to recent days. Accordingly, temperatures will not reach quite as
high as the days prior, but heat index values will still rise into
the 100s. The increase in moisture will also bring chances for more
scattered convection, mainly along the higher terrain due to weak
forcing overall.
On Wednesday, troughing from the north will deepen, leading to
height falls and further suppression of high pressure. A frontal
boundary will be noted north of the Ohio River Valley. As this front
approaches from the north, additional, more widespread chances of
convection exist on top of terrain-based development. By Thursday,
the front will likely reach near the area, providing additional lift
and further reduction in temperatures. It is still unclear how much
coverage there will be because of the significant drought and recent
trends. But the pattern does look promising for more substantial
rain chances, which are very much needed due to worsening drought.
Friday through Sunday
Late in the week and into the weekend, the main question will be how
far south the frontal boundary reaches, which will affect the
available moisture and overall forcing. Much of this timeframe will
see more of a troughing pattern, keeping temperatures more moderated
and even slightly below normal. Based on these indications, daily
rain chances were maintained, but confidence is still limited based
on the persistent dryness recent model biases.
Daily Record High Maximum Temperatures
Date Chattanooga Knoxville Tri-Cities Oak Ridge
07-15 103(1977) 98(1995) 96(1995) 100(1980)
07-16 105(1980) 100(1980) 100(1988) 103(1980)
07-17 103(1980) 101(1980) 94(1980) 103(1980)
&&
.AVIATION...
(00Z TAFS)
Issued at 739 PM EDT Sun Jul 14 2024
VFR expected for most of the period at all sites except an increasing
chance of showers and thunderstorms Monday afternoon at CHA.
PROB30 added to reflect that chance. Cloud cover expected to
increase at all levels into Monday afternoon as moisture is
advected into southern parts of the CWA. Otherwise, winds expected
to be light from the south to westerly direction.
&&
.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN 75 98 74 96 / 10 30 20 50
Knoxville McGhee Tyson Airport, TN 73 97 74 95 / 0 20 10 40
Oak Ridge, TN 72 98 73 95 / 0 20 10 40
Tri Cities Airport, TN 68 95 69 93 / 0 10 10 40
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...NONE.
VA...NONE.
&&
$$
SHORT TERM...JB
LONG TERM....BW
AVIATION...KS