Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 07/16/23
Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
854 PM CDT Sat Jul 15 2023
.UPDATE...
Issued at 850 PM CDT Sat Jul 15 2023
Overall, the forecast is doing fine. Did add low pops to the
northeast CWA where the last few runs of the HRRR have been
claiming that late night showers are possible. Given current
activity over nc/ne ND, decided it might not be a bad idea to
throw out some 20 percenters. Forecasted temperatures look fine
overnight.
&&
.SHORT TERM...(This Evening through Sunday Night)
Issued at 224 PM CDT Sat Jul 15 2023
Smoke continues to stream in on the jet within the upper trough.
There is some improvement in vsby this afternoon in the northeastern
cwa as the trough digs farther south, taking the smoke with it.
However, the western edge is expected to move in tonight and Sunday
morning dragging the smoke back in. Latest HRRR runs continue to
clear the near surface smoke out Sunday afternoon, through
persistent upper level northwesterly flow will keep that smoky haze
in the sky for longer.
Surface high pressure builds in from the northwest on Sunday
bringing lighter winds with occasional breezes mixing down. The
weekend forecast remains dry with smoke and the upper trough keeping
high temperatures around 5 degrees below average.
.LONG TERM...(Monday through Saturday)
Issued at 224 PM CDT Sat Jul 15 2023
Key Messages:
* Smoke still nearby to start the week.
* Chances for showers and storms late Monday night into Tuesday
night.
By 12z Monday, the 500mb ridge currently over the western U.S. up
through the British Columbia/Alberta border will shift east from
Saskatchewan through MT/WY and into the southwestern states. While
this northwesterly flow pattern will keep smoke across portions of
the area, the 12Z run of the HRRR smoke modeling does show most of
the surface smoke pushed south and west of the forecast area. Smoke
has reduced visibility to 6 miles or less at MBG since around noon
Friday. At the surface we`ll have an elongated area of high pressure
stretching from Saskatchewan through much of ND and eastern SD.
Expect this area of high pressure to sink to our southeast through
the day Monday with dry air remaining in place. Warm air advection
showers or storms will return as early as Monday evening over
central SD as a surface low organizes to our southwest. Enhanced by
a 30-40kt low level jet, strong shear, and a low level moisture with
dewpoints in the 60s moving in. The SPC marginal risk for day 3
looks reasonable, with elevated storms and hail being the main
severe threat given from the strongest storms overnight into early
Tuesday morning. By 12Z Tuesday the surface weather map should show
a low near the Alberta/Saskatchewan border, with another low
generally over western NE. Our forecast area will remain between
these 2 features as the Canadian low moves across Manitoba and into
MN on Wednesday, and the low to our south continues to exit
southeast. During the day Tuesday, chances of showers/storms slowly
diminishes, with the focus shifting to northeastern SD later Tuesday
afternoon into Tuesday night/closer to the surface low. Other than
late Monday night into Tuesday night, much of the rest of the
forecast period looks dry. A large area of high pressure over
southwestern Canada will move into the Northern Plains Thursday
through Saturday.
The temperature forecast become is little more uncertain with lower
confidence as we move into Tuesday, despite less smoke in the area.
For example, in the NBM there is a 10 degree spread in the 25th and
75th percentile for highs Tuesday for Aberdeen, ranging from 7 7 to
87 degrees. 80s look realistic for all locations by Wednesday, and
through much of the rest of the period. A few readings in the 90s
will be possible next Saturday over central SD.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday Evening)
Issued at 613 PM CDT Sat Jul 15 2023
Terminals KABR,KATY,KPIR,KMBG
Widespread smoke both sfc and aloft will continue over the region
through Sunday. Most of sfc smoke will exist for KMBG/KPIR.
Otherwise expect milky looking skies to continue, with little to
no chance of rain.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
&&
$$
UPDATE...TDK
SHORT TERM...Wise
LONG TERM...KF
AVIATION...TDK
Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
350 PM AKDT Sat Jul 15 2023
.UPDATE...Current satellite imagery shows a cluster of
thunderstorms moving NW towards Hyder. Added a slight chance of
thunderstorms for areas around Hyder for the next 6 hours.
Remember, when thunder roars, go indoors.
&&
.PREV DISCUSSION......ISSUED AT 227 PM AKDT...
SHORT TERM...The broad high pressure currently in place over the
north central gulf is slowly breaking down as a surface low
pressure drifts northward and diminishes. Light winds and calmer
sea is the main story for marine through Sunday. Larger story is
the enhanced CAPE over northern British Columbia both this
evening and tomorrow. Model sounding tonight from both the NAM
and HRRR indicate storm motion will be quasi parallel to the Coast
Mountains and therefore any thunderstorms will likely not enter
the area from Canada. As for storm initiation in areas such as
Misty Fjord, lifting index appear to not support any thunderstorm
development. Given this information, no thunderstorms were added
for the tonight time period.
For tomorrow, vorticity aloft moving northwest from B.C. will
likely develop some showers as it passes over. Winds through the
weekend will see light winds primarily during the overnight/early
morning hours followed by sea breezes developing through the day.
Strongest sea breezes continue to be expected out of the West
near Point Couverden (10-15kt) and near Skagway. The low to the
south will occasionally cause 15kt winds near Dixon Entrance and
up Clarence Strait.
LONG TERM.../Monday through Thursday/...A definitive shift in the
pattern is in store for SE AK through the long term, though not
necessarily a return to a fully active weather pattern. Aloft, a
broad upper level low will become quasi-stationary over the lower
Gulf, blocking any large scale systems from crossing into SE AK
until the low finally departs through the weekend. In the mid and
lower levels of the atmosphere, this will translate into a series
of weak short waves which will rotate around the low and into the
panhandle from the South - or alternatively from the E depending
on the orientation of the steering flow from wave to wave.
At the surface, this ultimately means that periods of rain showers,
and perhaps a few thunderstorms if given sufficient vorticity
banding, will be interspersed between otherwise drier weather
conditions. Cloud cover will prove to be more widespread than it has
been the week prior, though periods of offshore flow will still
enable clearing in many locations through various parts of the
time frame.
The most powerful of these short waves will arrive on Tuesday,
though it is perhaps more accurate to call it a decaying frontal
band rather than a more typical shortwave trough. Anticipate some
small craft conditions in conjunction with this frontal band, and
the greatest precipitation to be along the outer coast and in the
southern half of the panhandle - though think that most of the
area will see at least some rain from this event. This system will
have largely departed the area by Wednesday, leading to renewed
chances of drier weather, or at least more isolated rain showers,
across much of the area until another wave arrives on Thursday.
The weekend itself will see greater chances of more organized
precipitation as the upper level low begins to move off to the NE,
enabling stronger waves - or potentially even organized systems
not directly associated with said upper level low - to begin
impacting the panhandle.
Winds will be subject to sea breeze impacts, particularly across
the N half of the panhandle. Anticipate that high temperatures
will continue to remain in the 60s and 70s before the possibility
of a cool down arrives during the weekend though this is not yet
set in stone.
AVIATION...Wrap around showers originating from a low southwest of
Haida Gwaii continue to move over the southern panhandle with
very light precip reported in Kake, Ketchikan, and Klawock this
morning. Still, CIGs are solidly VFR and there are large breaks in
the cloud cover. Early morning marine layer along the outer coast
affected aviation operations this morning with the central outer
coast being hit the hardest. Winds continue to be light at 10 to
12 kts with the northern portion of Lynn Canal likely getting up
to 15 kts this afternoon. The situation tomorrow will be much like
today except with CIGs down to MVFR conditions and more frequent
shower activity.
&&
.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...None.
MARINE...None.
&&
$$
SHORT TERM...NC
LONG TERM....GFS
Aviation...Fritsch
Visit us at http://www.weather.gov/Juneau
Area Forecast Discussion
National Weather Service Amarillo TX
625 PM CDT Sat Jul 15 2023
...New AVIATION...
.SHORT TERM ...
(This evening through Sunday night)
Issued at 254 PM CDT Sat Jul 15 2023
Strong to severe thunderstorms will be possible once again this
evening across most of the combined Panhandles. Damaging winds
and large hail will be the main hazards, although a brief tornado
or two can`t be ruled out in the western TX Panhandle. The main
threat will then shift to flash flooding as additional showers and
storms re-develop through the night.
As of 18z, GOES water vapor satellite imagery and RAP mesoanalysis
show an upper level shortwave starting to take shape over NE NM
as northwest flow crosses over the Rockies. Convection is already
developing off the mountains, and this trend will continue
through the afternoon as the wave deepens. A ridge of quality
theta-e advection is building into the area, and with mid to
upper 60s dew pts in place, daytime heating has helped to produce
1500-2500 J/kg of uncapped MUCAPE. Favorably oriented 40-50kt
sfc-6km bulk shear will favor isolated supercell development in NE
NM/SE CO at first, but should congeal into clusters and
eventually an MCS as they move into the TX Panhandle. The main
threats will start off as large hail up to 2" (7-8 deg C/km mid-
level lapse rates) and damaging winds of 70+ mph (DCAPE values
around 1000-1500 J/kg). The environment won`t be terribly
favorable for tornadoes with low-level shear forecast to be
rather weak (<10 kts sfc-1km), but with backed winds at the sfc
and decent turning with height in the low levels, there could be
some slightly improved hodograph curvature after 00z in the W/SW
TX Panhandle that may support brief tornado potential. The longer
storms stay at least somewhat discrete, the longer this potential
may exist. In general though, damaging winds should become more
prevalent as storms move S/SE through the evening. Best chances
(>50%) will be in the southwest half of the combined Panhandles
(along a Boise City - Pampa - Wellington line), but storms could
potentially extend slightly further north and east across the
area.
Flash flooding will be a prominent threat as well, especially
into the overnight hours. CAMs have continually shown a corridor
of showers and storms re-developing behind the main line after it
exits to the south. PWATs of ~1.50" or greater will provide
plenty of fuels for heavy rainfall rates with any storms that
develop. This may lead to training over areas that have already
received heavy rainfall with the first round, creating rainfall
totals well over 0.50-1.00" by Sunday morning. Some areas will be
especially sensitive to flooding, especially locations such as
Dumas which received 2.00" of rain with last night`s storms. On
Sunday, high pressure starts to nudge northward back into the
Panhandles and begin to dry us out. Southwest winds at the sfc
and clear skies will help daytime highs warm into the low 90s
across the area. Overnight lows will be in the 60s.
Harrel
&&
.LONG TERM ...
(Monday through next Friday)
Issued at 254 PM CDT Sat Jul 15 2023
Through the extended, the high pressure center at 500mb is
expected to shift back and forth across the southwestern CONUS.
This could lead to some polarizing days where we start with hot
and dry conditions, then transition to a warm and wet pattern.
This will mostly be determined at the synoptic level.
Thunderstorm coverage and daily high temperatures will depend on
the position of the high pressure center and shortwave timings
from the associated mid level trough.
Monday through Wednesday, the 500mb high returns from the west and
settles above New Mexico and eastern Arizona. This could lead to
stable atmospheric conditions until Wednesday evening, where the
upper level pattern shifts allowing thunderstorms to move in from
the northwest. Until then, breezy southwest winds between
15-20kts will prevail during the afternoon for each day. There
could also be heat concerns for Palo Duro Canyon on these first
three days. The NBM already shows surface temperatures around 105
degrees at the canyon floor during the afternoons. An advisory
for PDC will be assessed as we approach the new week. Thunderstorm
chances could return as early as Tuesday evening, but the chances
are quite a bit lower compared to Wednesday. Still, if the cap
breaks, we could see some isolated showers in the northwest
Panhandles that evening. Therefore, we have let the NBM keep
slight chance pops for Tuesday. Then on Wednesday, better chances
for storms enter into our area from the northwest.
Thursday through Saturday, the 500mb high retreats back to the
north and sits over the four corners region. Repeated shortwaves
are forecasted to eject off of the Rockies and generate storms in
our area for the remainder of the extended. Under the right
conditions, some of these storms could become strong to severe.
However, that is going to be dependent on trough ejection timing
and the environmental conditions present. High temperatures for
the remainder of the week could decrease to the upper 80`s and mid
90`s.
Rangel
&&
.AVIATION...
(00Z TAFS)
Issued at 619 PM CDT Sat Jul 15 2023
Thunderstorms are expected at KDHT and KAMA this evening, but
further amendments will be needed to narrow down timing.
Additional rain and thunderstorms will be possible throughout the
night at both terminals, but it is uncertain where it will occur.
Additional amendments may be needed depending on where the
overnight activity sets up. The threat for thunderstorms will
likely end by 12z at the latest.
&&
.PRELIMINARY POINT TEMPS/POPS...
Amarillo TX 86 65 91 68 / 40 60 20 0
Beaver OK 87 65 93 68 / 10 20 10 0
Boise City OK 83 61 91 63 / 30 50 20 0
Borger TX 87 67 93 69 / 60 50 20 0
Boys Ranch TX 87 65 93 67 / 40 60 20 0
Canyon TX 87 64 92 67 / 30 60 20 0
Clarendon TX 86 68 90 68 / 50 60 20 0
Dalhart TX 84 61 90 62 / 30 60 20 0
Guymon OK 86 63 92 64 / 20 20 10 0
Hereford TX 89 64 92 67 / 30 70 20 0
Lipscomb TX 87 65 92 68 / 10 30 20 0
Pampa TX 88 65 89 68 / 60 40 20 0
Shamrock TX 88 68 91 67 / 50 50 20 0
Wellington TX 89 68 92 68 / 50 60 20 0
&&
.AMA WATCHES/WARNINGS/ADVISORIES...
TX...None.
OK...None.
&&
$$
SHORT TERM...38
LONG TERM....55
AVIATION...52
Area Forecast Discussion
National Weather Service Birmingham AL
1003 PM CDT Sat Jul 15 2023
...New SHORT TERM...
.SHORT TERM...
(Tonight through Sunday)
Issued at 944 PM CDT SAT JUL 15 2023
The lingering showers and storms over the southern counties dissipated
quickly after sunset. Another upstream MCS over western MS has
been tracking southeast this evening with the leading edge near
Jackson MS. The activity will likely decrease in intensity
overnight, but the HRRR model does show some convective activity
entering west Alabama around 11 PM CDT. The convection spreads
southeast overnight south of I-20 and towards I-85. I will
increase rain chances across west Alabama starting around midnight
and show 30-40 percent rain chances across the southern counties
through sunrise.
58/rose
Previous short-term discussion:
(This afternoon through Sunday)
Issued at 1248 PM CDT SAT JUL 15 2023
Had to make several changes to the forecast this morning due to the
early morning rainfall across the northern third of the area
associated with a decaying MCS. That feature left cloud cover and
stable air over much of the northern portions of the area with
subsidence behind it which was noted on vis satellite imagery by a
clearing in the cloud cover across our northwest. This required
adjustments to temperatures since the trends were off, and lowered
highs slightly for areas generally north of I-20 where some
locations may remain in the 80s today. Meanwhile, it remains hot and
humid across the southern half of the area where temperatures are in
the upper 80s to lower 90s with dewpoints in the upper 70s. Heat
indices are already up near 108 degrees at Montgomery and 104-106
in the surrounding areas, so the Heat Advisory remains in effect.
Another cluster of thunderstorms over Central Mississippi is
being monitored as it moves through the west-northwesterly flow
and will eventually reach the AL/MS state line within the next
couple of hours. Some of the short term models show this activity
favoring a trend in more of a southerly/southeasterly direction
this afternoon which would take it towards our southwestern
counties where the air is more unstable, with less activity
expected for areas north of I-20. The storms are not particularly
robust at the moment, but could intensify through the afternoon.
Will need to keep an eye on rain rates as the activity could
propagate across a region which is already well saturated from
rainfall over the past couple of days. A few of the storms could
also produce gusty sub-severe winds, but the tropospheric column
is very saturated with PWATs of 2-2.25 inches which should limit
evaporative cooling and the potential for microbursts. Otherwise,
PoPs were lowered across the northeast where the air should remain
mostly stable behind the rain earlier this morning.
The shortwave trough axis will move east of the area this evening
and dry mid-level air will begin moving in across the north as a
moisture gradient/weak front sets up across the area overnight.
Mean RH looks to drop significantly across much of the area
tomorrow with deeper moisture confined to areas along and south of
I-85. PoPs will focus across our far south as a result with some
scattered showers/storms possible early tomorrow morning in our
south near the moisture gradient and gradually becoming focused
further south of the area throughout the day. Most locations will
be sunny and hot tomorrow afternoon with highs in the lower 90s,
but with the drier air aloft, dewpoints may mix down into the
upper 60s across the northern half of the area and lower to mid
70s in the south, so heat indices look to remain just below Heat
Advisory criteria.
86/Martin
&&
.LONG TERM...
(Sunday night through next Friday)
Issued at 330 PM CDT SAT JUL 15 2023
Made minor changes to rain chances and temperatures in the
extended this afternoon, but overall the trends are the same.
Upper level troughing remains the active player on Monday, and
despite some drier air in place, isolated to scattered
thunderstorms will be possible during the afternoon. Upper level
ridging to our west expands eastward Tuesday and Wednesday. With
heights rising, will see little to no rainfall and warmer
temperatures. Highs will be in the mid to upper 90s Tuesday
through Thursday. This will push heat indices into the 105-109
range each afternoon from Tuesday through Friday.
By the end of the week, ridging weakens and impulses within
northwesterly flow begin to impact the area again.
14
Previous long-term discussion:
(Sunday night through Friday)
Issued at 331 AM CDT SAT JUL 15 2023
Behind a weak front, a relatively drier airmass will be in place
Sunday night particularly across our northern half. Some slight
moistening could occur on Monday with a large-scale trough axis
over the region and an approaching shortwave. For now it appears
that showers and storms should remain isolated especially across
the north and east.
A pattern shift will begin to occur on Tuesday with as a
strengthening and expanding upper-level ridge covers much of the
southern latitudes of the CONUS. Height rises and subsidence are
expected on Tuesday with temperatures reaching at least the mid
90s. Upper 90s are expected on Wednesday and Thursday along with
increasing dewpoints which could drive heat indices into the
105-108 degree range. The ridge should begin to retreat on Friday,
leading to an increasing potential for showers and storms as a
weak front moves into the region.
87/Grantham
&&
.AVIATION...
(00Z TAFS)
Issued at 622 PM CDT SAT JUL 15 2023
Central Alabama will be trending towards a drier period with only
limited convection. Drier mid level air will suppress convection,
but there will be a chance of overnight and Sunday morning
showers and tstms at MGM/TOI. VFR conds expected thru 09Z, but
there will be a 3-4 period of IFR/MVFR cigs from 09Z thru 13Z. The
IFR cigs will mainly impact areas along and north of I-20, with
MVFR cigs across south Alabama. A surface front will push
southward through Central Alabama on Sunday, and sfc winds will
become northwest by 18z.
58/rose
&&
.FIRE WEATHER...
A weak front moves in from the north tomorrow, leading to
northwesterly winds and confining the highest rain chances to our
southern counties. RH values will drop into the 40-55 percent
range Sunday behind the front. 20ft winds become westerly at
5-7 mph Monday afternoon, with low rain chances, and afternoon RH
values in the 38 to 48 range.
&&
.PRELIMINARY POINT TEMPS/POPS...
Gadsden 71 93 67 94 / 10 0 0 20
Anniston 72 92 70 93 / 10 10 0 20
Birmingham 73 94 72 95 / 10 0 0 30
Tuscaloosa 73 94 72 94 / 20 10 0 30
Calera 73 93 72 93 / 20 10 0 30
Auburn 74 91 72 92 / 20 20 10 20
Montgomery 75 93 72 95 / 30 20 10 30
Troy 74 93 72 95 / 20 30 10 30
&&
.BMX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...58/rose
LONG TERM....14
AVIATION...58
Area Forecast Discussion
National Weather Service Denver/Boulder CO
927 PM MDT Sat Jul 15 2023
.UPDATE...
Issued at 926 PM MDT Sat Jul 15 2023
The forecast is performing well with only minor updates this
evening.
We had a few more, and a bit more intense, storms come off the
northern Front Range this afternoon, and the remnants are slowing
moving off southeast across the plains. We had some severe storms
that produced large hail, up to 2 inches.
There are a few weak showers in Wyoming that might clip our
northeast corner (Sedgwick County, maybe a bit of Logan and
Phillips Counties, but not as likely), and no significant impacts
are expected from that. Skies will clear out tonight.
The 00Z synoptic dataset shows the ridge building over the
western states and the upper low moved closer to the Great Lakes,
and Colorado on the front side of the ridge with brisk
northwesterly flow aloft. Upstream soundings have 0.4 to 0.6
inches of precipitable water and GOES imagery shows the dry
airmass on the way for tomorrow and Monday. Expect mostly clear
skies and warming. We maintain our Heat Advisory for the I-25
Urban Corridor on Monday from 10 AM to 8 PM MDT, as high
temperatures Monday will reach the upper 90s and may break 100 F
in some areas, and heat illness will be a danger.
The HRRR and RAP Smoke models show a plume of thick smoke from
the fires in Canada circulating just off our northeast corner in
the short term forecast period. The healthy flow through the ridge
looks to protect us for now.
Our partners at CDPHE have issued and Ozone Action Day Alert for
the Front Range Urban Corridor effective tomorrow, as hot
temperatures and light winds are expected to allow unhealthy
concentrations of ozone.
&&
.SHORT TERM...(This evening through Sunday)
Issued at 227 PM MDT Sat Jul 15 2023
Scattered thunderstorms have formed over the foothills southwest
of Denver and also along the Cheyenne Ridge. RAP shows ML CAPE has
climbed up to 1400 J/kg across the Front Range and eastern
plains. Bulk Shear (0-6km) is 30-40 knots. This is should help
some of the storms to become strong to severe, mainly along the
Urban Corridor and over the eastern plains. Drier air will be
moving into the area. Dew points are in the 30s west of the
Continental Divide. Even in the higher foothills and Front Range
mountains, dew points have fallen into the 30s. As the airmass
continues to dry this evening, convection is expected to end mid
to late evening.
For Sunday, an upper level ridge building over the Desert
Southwest and Great Basin will bring warmer and dry conditions.
Cross sections show the airmass will be fairly dry with only some
high based cumulus clear Sunday afternoon. Temperatures warm into
the upper 80s and lower 90s over northeast Colorado. Northwest
winds will increase over the higher terrain in places Sunday
afternoon with gust to 30 mph. This will elevate the fire weather
conditions.
.LONG TERM...(Sunday night through Saturday)
Issued at 227 PM MDT Sat Jul 15 2023
A subsident and dry airmass associated with a large upper level
ridge of high pressure over the Four Corners region will bring dry
weather and above normal temperatures to North Central and
Northeastern Colorado Sunday night and Monday. Max temperatures on
the plains are expected to climb well into the 90s with a few
locations possibly reaching the century mark. Due to the hot
temperatures, have decided to issue a heat advisory for portions of
the Front Range Urban Corridor, including Metro Denver from late
morning into early evening Monday.
On Tuesday, the upper ridge flattens somewhat in response to an
upper level shortwave moving across the Northern Rockies and Great
Plains States. Some increase in mid level moisture fwf with a weak
shortwave may result in isolated to scattered showers and storms
across the forecast area Tuesday afternoon and evening. Inverted V
soundings suggest gusty winds along with little rain with most of
the storms. The added moisture and convection should bring
temperatures down a few degrees. However, it will still be hot with
max temperatures climbing into the 90s on the plains.
Models are showing the upper ridge amplifying over the Pacific
Northwest and Northern Rockies Wednesday through Friday which should
allow upper level disturbances and weak cool fronts to push across
Northeastern Colorado. Consequently, somewhat cooler and unsettled
weather is expected through this period with scattered afternoon and
evening showers and storms. With PW`s ranging between 1.00" and
1.25" across the plains and Palmer Divide, locally heavy rainfall
will be possible with the stronger storms.
By Saturday, the upper flow becomes more northerly with the best
moisture shifting to the south of the CWA. Therefore, we may see a
downtrend in shower and thunderstorm activity as we start the
weekend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 600 PM MDT Sat Jul 15 2023
Expect VFR conditions through the period with cloud bases to
remain above 6000 feet. Isolated thunder in the vicinity is
possible through early evening but so far DEN has been missed and
it looks like it`s probably safe a while longer. I may soon pull
the thunder entirely from the TAF, but there is a bit more
initiation just upstream, so will wait for now. Passing storms may
bring light precipitation and variable gusts, greater impacts are
not likely. Northeasterly winds this evening should soon come
around easterly then southeasterly, when not variable with
outflow. Drainage wind should take over tonight, then there looks
to be a northerly push in the morning and typical diurnal winds
behind: northeast for the afternoon coming around easterly then
southeasterly again. Mostly clear tomorrow.
&&
.FIRE WEATHER...
Issued at 227 PM MDT Sat Jul 15 2023
High pressure aloft will build over the southwest part of the
country. This will bring warm and dry conditions for Sunday.
Relative humidities will fall into the 10-15 percent range in the
mountain valleys Sunday afternoon. It will become breezy in parts of
the mountains and mountain valleys Sunday afternoon with gusts to 30
mph possible.
Dry, breezy and very warm conditions will produce near Red Flag
Conditions west of the Front Range and in South Park Monday and
Tuesday. Conditions are expected to improve by mid week as
moisture level increase.
&&
.HYDROLOGY...
Issued at 227 PM MDT Sat Jul 15 2023
A few showers and storms will produce brief heavy rainfall through
mid evening. No hydrology issues are expected with this activity.
For Sunday and Monday, it will be dry across the area.
A return to a limited burn area flood threat is expected for the rest
of the week as thunderstorm activity increases. In addition, PW`s
above an inch may result in locally heavy rainfall across
portions of the plains and Palmer Divide Wednesday through Friday.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
Heat Advisory from 10 AM to 8 PM MDT Monday for COZ038>040-043.
&&
$$
UPDATE...EJD
SHORT TERM...Meier
LONG TERM...jk
AVIATION...EJD
FIRE WEATHER...Meier/jk
HYDROLOGY...Meier/jk
Area Forecast Discussion
National Weather Service Boston/Norton MA
955 PM EDT Sat Jul 15 2023
.SYNOPSIS...
Showers and thunderstorms continue this afternoon then diminish
early this evening. A slow moving cold front interacts with an
anomalously strong feed of rich tropical moisture Sunday and
Sunday night, with a renewed risk for showers and thunderstorms
capable of heavy rain and a significant potential for flooding.
Dry weather Monday, before another cold front brings another
round of more progressive showers and thundershowers. Wednesday
is also appearing dry before our active weather pattern then
resumes for late next week.
&&
.NEAR TERM /UNTIL 8 AM SUNDAY MORNING/...
10 PM Update...
As expected, shower activity has subsided significantly
after sunset, with just a few straggling showers across central
and western MA. Widespread stratus and patchy fog has engulfed
much of the region south of I-90 and is expected to increase in
coverage over the next few hours. However, fog will have a tough
time sticking around into the early hours of the morning where
shower activity develops after 05/06Z. Overall, no major
adjustments made to the forecast with this update with all eyes
on the timing and coverage of pre-dawn showers and t-storms.
815 PM Update...
Loss of day time heating will bring an end to showers/storms in
combination with weak mid level ridging. This will be short
lived as a frontal boundary will be in place across portions of
southern New England. The front will lift northward as a warm
front into Sun AM and could bring a few spotty showers and
perhaps a thunderstorm or two, but the thunder risk will really
uptick toward daybreak/Sunday AM.
Dialed back precip chances in the immediate near term as
convective guidance, particularly the HRRR indicates through
roughly 06Z. Still have some low chances, but am thinking
guidance is indicating more drizzle vs showers. Better shot for
the showers is toward and after 06Z as the warm front lifts
northward and we begin to advect in 1.75 to 2+ inch PWATs as we
head toward daybreak. Not of the the question during this
timeframe there are a few thunderstorms, which may produce
locally heavy downpours. Cannot completely rule out a strong
storm or two given the roughly 30-40 kts of deep layer shear and
the HREF is indicating some 2-5 km UH values greater than 75
across western portions of the CWA. Really thinking that the
best shot for the storms comes toward daybreak and especially
Sun AM.
Did make some minor adjustments to the temps as well as we were
running a bit too cool compared to the latest observations. Lows
bottom out tonight in the low/mid 70s for most.
&&
.SHORT TERM /8 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/...
Highlights...
* A renewed flash flood threat due to torrential downpours starting
Sunday morning through Sunday afternoon.
* A secondary concern are a few strong to severe thunderstorms.
Yet another round of soaking rains will reignite a flood threat for
much of southern New England on Sunday. Most of the CWA is under a
Moderate risk for Excessive Rainfall, and the most far southeast
Massachusetts; Plymouth County, Cape Cod, and the Islands under a
Slight threat for Excessive Rainfall. Given low flash flood guidance
and the antecedent conditions we`ve continued the Flood Watch,
effective 2 AM Sunday through 2 AM Monday.
Our setup for Sunday is impressive with PWATs exceeding 200 percent
of normal, with a maxima between 2.4 and 2.8 inches! This is near
the maximum value for model run climatology across the CWA. The
convective allowing models (CAMs) are in fair agreement that a
building line of showers with embedded thunder will approach from the
west, reaching the New York/Massachusetts line around 9z/12z Sunday.
SPC HREF has higher probabilities our effective shear of 30
knots with lower probabilities of that exceeding 40 knots. This
will help keep our storms organized. HREF mean does show a
widespread 1.0 to 2.5 inches, with the max of 3.0 to 5.0 inches.
Since these totals are from convective showers, it becomes
difficult to pinpoint which area will experience the heaviest
rainfall. Overall, most places likely to see between 1.0 and 2.0
inches with locally higher amounts over 3.0 inches. And given
our current Flash Flood Guidance is 1.4 to 1.8 inches, flash
flooding remains our primary concern Sunday morning through the
afternoon.
So in addition to hydro/flooding threat, there is a low threat for a
few strong to severe thunderstorms. The limiting factor will be how
much instability these storms have to tap into, given the abundant
cloud cover. Never the less, this could be a situation where we
trade higher values of shear for instability. In collaboration with
SPC we`ve asked to extend the Marginal severe weather risk east, all
of southern New England has the potential for a severe storm. While
we do not expect widespread severe, a locally strong storm could be
capable of producing gusty straight line winds, SPC putting a 5
percent risk over the area. But given the increasing 925mb low level
jet and 90 percent probability of low level helicity 100m2/s2, we
can not rule out a brief tornado, which SPC placed us in a 2 percent
probability.
The front that brings all this active weather finally shifts east
and off shore followed by drier weather. Temperatures are slightly
cooler in the upper-70s to low-80s, due to more clouds than sun
which will limit how warm we get. While not as warm, it will feel
very humid with dewpoints in the low 70s. Overnight lows are warmer
as well with lows in the upper-60s and low-70s.
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
Highlights
* Daily shots for showers/storms through much of the week. Does
appear much of Mon will be dry and perhaps Wed/Thu.
Monday through Wednesday...
Cyclonic flow in place through much of the extended. Feels like deja
vu as the pattern is quite similar to the past couple of weeks. A
weak mid level ridge will build over the eastern Great
Lakes/southern New England on Mon. This builds into northern New
England by Tue and our next shortwave/trough lifts in from the Mid
Atlantic. This wave should be northeast of the region by early Wed,
when our next shortwave ridge builds in for much of the day. On Mon,
the cold front should be across our eastern areas or just offshore
and a weak high builds in behind it. A cold front swings in on Tue
before another weak high builds in on Wed.
No major adjustments to the forecast through this timeframe as the
NBM seemed quite reasonable. Will have a few lingering
showers/storms early on Mon across eastern areas as the front is
still working its way through. For most will be dry across southern
New England, hot and humid. At this point appearing that 925 hPa
temps will be between 20-25 degrees Celsius with SW/W flow. Should
see fairly widespread upper 80s to low 90s.
Shower and thunderstorm chances return on Tue, but does not look
like a washout at this point in time. Should have better
opportunities for this activity especially across the interior
during the afternoon and heading into the evening. Not out of the
question there are a few stronger thunderstorms and potentially
severe. Will have deep layer shear in the 0-6 km layer around 30-40
kts with MLCAPE of a few hundred to roughly 1200 J/kg. The mid level
lapse rates are around 5-6 degrees Celsius per km and low level
lapse rates around 7-8 degrees Celsius. The main question will be
the timing of the front moving in. If it moves in a bit too late to
realize the instability than the severe risk will be diminished. At
this point think the main risks will be damaging wind gusts, but
hail will also be possible as there is a few hundred J/kg of CAPE
within the hail growth region. There is a brief mention about a
marginal risk across the Northeast in the latest SPC Day 4 outlook,
This is also highlighted per the CSU ML Probs across our region. At
this point it shows a 5 to roughly 30 percent chance with the
highest risks across western areas on Tue. Still hot and humid with
highs in the 80s.
The drier weather returns on Wed as another shortwave ridge builds
in. Will note that the CMC pushes a deep convective low into our
area late in the day, but at this point appears to be an outlier.
Have thrown out the CMC because of this, but will be something to
keep an eye. Have stuck with the NBM, which keeps us dry through
much of the day. We could perhaps feel a bit less muggy as dew
points drop into the low/mid 60s under W/WNW flow aloft. High temps
in the 80s.
Late in the week...
The cyclonic flow persists as we head late into the week. Becomes a
bit more difficult to time fast moving short waves/troughs as we
head late into the week. Given the uncertainty have just stuck with
the NBM at this point, but we could potentially eek out another dry
day on Thu. Will have chances for showers/storms on both days, but
not appearing like a washout at this point. Will be feeling a bit
more muggy as dew points climb back into the mid/upper 60s. Highs
range from the upper 70s to the mid 80s.
&&
.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
Forecast Confidence
Levels:
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Tonight...High confidence in trends moderate in timing.
Confidence moderate across the Cape/Islands.
Gradual deterioration from VFR/MVFR to MVFR/IFR conditions. Have
backed away from LIFR in the latest update, except for along the
immediate south coast where a stationary front may be situated
through approx 06Z. Near term guidance keeping things more
solidly in MVFR/IFR tonight with any showers/storms this evening
tapering off before shower and perhaps a few thunderstorms renew
after 06Z. Though think the better shot for thunder it
closer/after daybreak. Winds may remain a bit too strong for
much visby reduction, so have brought visby up for most tonight.
Less confident across the Cape/Islands where there could be some
improvement after an area of decaying showers/storms move
through. Winds out of the S at 5-10 kts.
Sunday...High confidence in trends, moderate in timing.
Any fog lifts, but MVFR to IFR clouds linger and perhaps some
spotty LIFR. Will have increasing showers/t-storms through at
least the first half of the day. More confident in the
thunderstorm coverage across western terminals where have VCTS
and less certain in the coverage as you move further east where
have PROB30. Utilized HREF thunder timing heavily, but am
thinking best shot with a convective line is from roughly 14-20Z
and coverage becomes more spotty afterward. If a heavier storm
moves over a terminal could see strong wind gusts and heavy
downpours. Winds will be gusty out of the S/SSW as a 20-40 kt
low level jet moves overhead. Winds around 10-15 kts with gusts
of 20-30 kts.
Sunday Night...Moderate confidence
Showers tapering off from west to east with IFR to LIFR
conditions gradually improving to MVFR late. Winds out of the S
at 5-10 kts shifting to the SW/W late. Could see some gusts of
20-25 kts toward daybreak across the Cape/Islands.
KBOS TAF...High confidence in trends, moderate in timing.
Ceilings lowering to IFR and could see some fog as stratus moves
in. Spotty showers possible toward daybreak and into the AM
push. Activity becoming more widespread Sun AM with embedded
thunder mid AM into the afternoon as a line of showers/storms
moves in. Could see briefly higher gusts/heavy downpours if the
line moves over the terminal. Still could have some thunder
during the afternoon, but coverage appearing more spotty in
nature.
KBDL TAF...High confidence in trends, moderate in timing.
VFR to start, but will see ceilings lowering to MVFR/IFR toward
04-06Z. Should see more shower activity late tonight and heavier
showers with embedded thunder roughly 14-18Z. Could have some
strong wind gusts as this line is moving through, but not
confident enough to include in this update other than VCTS at
this point. Could see see activity during the afternoon, but
think it becomes more hit/miss in nature. MVFR/IFR conditions
persist through the day.
Outlook /Monday through Thursday/...
Tuesday: VFR. Breezy. Chance SHRA, slight chance TSRA.
Tuesday Night: VFR. Breezy. Chance SHRA.
Wednesday through Wednesday Night: VFR. Slight chance SHRA.
Thursday through Thursday Night: VFR. Chance SHRA.
Friday: Chance SHRA, isolated TSRA.
&&
.MARINE...
Forecaster Confidence Levels:
Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.
Tonight... High confidence
Increasing southerly winds gusting to 20 knots overnight. Seas begin
to rise to 4ft for the outer water and 2-3 feet for inner waters.
Thunderstorms associated with heavy rain and strong winds are
possible mainly after 2am. Dense fog looks possible to form
overnight.
Sunday...Medium confidence
Continued showers and thunderstorms with heavy rain and gusty winds
are possible through the entire day. Winds stay out of the south
with gusts up to 25 knots. Small Craft advisory will likely be
needed along the outer waters with seas rising to 5-6 feet. Inner
waters likely wont need small crafts with seas only 3-4 feet.
Sunday Night...Medium confidence
Decreasing southerly winds overnight but seas likely remain elevated
at 4-5 feet for the outer waters and 3-4 feet for the inner waters.
Winds begin to shift WSW near daybreak.
Outlook /Monday through Thursday/...
Tuesday: Winds less than 25 kt. Seas locally approaching 5 ft.
Chance of rain showers.
Tuesday Night: Winds less than 25 kt. Areas of seas approaching
5 ft. Chance of rain showers.
Wednesday: Winds less than 25 kt. Seas locally approaching
5 ft. Slight chance of rain showers.
Wednesday Night through Thursday Night: Winds less than 25 kt.
Seas locally approaching 5 ft. Chance of rain showers.
Friday: Winds less than 25 kt. Seas locally approaching 5 ft.
Slight chance of rain showers.
&&
.HYDROLOGY...
Flood Warnings remain in place on the CT River from Hartford,
south. Renewed flooding concerns likely to develop the second
half of the weekend as an additional 1-4" of rain may fall
across southern New England; exacerbating existing flooding, or
lead to new flooding elsewhere.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...Flood Watch from 2 AM EDT Sunday through late Sunday night for
CTZ002>004.
MA...Flood Watch from 2 AM EDT Sunday through late Sunday night for
MAZ002>017-020-026.
RI...Flood Watch from 2 AM EDT Sunday through late Sunday night for
RIZ001>007.
MARINE...Small Craft Advisory from 8 AM Sunday to 8 AM EDT Monday for
ANZ250-254>256.
&&
$$
SYNOPSIS...BL/Dooley
NEAR TERM...BL/Dooley/KS
SHORT TERM...Dooley
LONG TERM...BL
AVIATION...BL
MARINE...BL/KP
HYDROLOGY...
Area Forecast Discussion
National Weather Service Billings MT
220 PM MDT Sat Jul 15 2023
.DISCUSSION...
Through Monday night...
Main impactful weather over the next 48 hours will be the heat
combined with Canadian wildfire smoke impacting outdoor
activities.
Area is currently slotted between a ridge along the west coast and
a trof over the Great Lakes region. This position puts
northwesterly winds over the area through much of the atmosphere
which is advecting thick wildfire smoke into the area from western
Canada. Air Quality alerts remain in effect for most of MT/WY
east of the divide into Sunday, and based on the HRRR near surface
smoke forecast likely into Monday before flow turns westerly and
pushes the smoke east of the area.
There is a disturbance dropping southeast in the upper flow this
afternoon into tonight which could trigger an isolated shower or
weak thunderstorm. However the lower atmosphere is pretty dry and
some mid level warming, possibly due to the wildfire smoke in the
mid levels, will be working to cap convection. While it can`t be
ruled out have current probabilities of any measurable
precipitation (mainly Rosebud county eastward) at 10 percent.
Ridge builds into the area on Sunday. Should see some easing of
wildfire smoke as winds become weaker through the column under the
ridge, but it will still be out there. Ridge will keep conditions
dry Sunday and boost temperatures into the 90s.
Ridge gets compressed by an approaching shortwave trof on Monday.
Increased downslope winds into the surface trof under the ridge
will work to increase temperatures 5 degrees over Sunday,
producing mid to upper 90s in many areas, the warmest temperatures
this summer so far.
As the upper trof crashes the ridge Monday night into Tuesday
will see a chance for precipitation develop for some areas. High
based storms over the west will produce more wind than rain but
convection transitions into wet thunderstorms over the eastern
plains where some Gulf Moisture gets advected northward ahead of
the system. Precipitation chances Monday night are currently in
the 30 to 40 percent range for areas east of Billings.
Smoke and Heat Safety...those with respiratory conditions should
limit time outdoors until smoke clears out, likely Monday into
Tuesday. In addition those with outdoor plans should be prepared
for Hot temperatures going into early next week and take
precautions to prevent heat related illness. Take plenty of
breaks, hydrate, and seek out places with air conditioning to cool
down. Chambers
Tuesday through Saturday...
Cluster analysis shows we will generally be in a ridging pattern
over the next week bringing warmer temperatures and dry
conditions. Tuesday will start off with a cold front exiting the
region and a shortwave trough making its way through. This will
help lower temperatures Tuesday and Wednesday. Even with this
forcing, precipitation is not likely due to PWATS being in the
10th percentile in some locations and a lack of instability with
<50% chance for 500J/KG of CAPE near the Dakotas border. Starting
Thursday and lasting the rest of the forecast period, ridging
will move back into the area and become centered over western
Montana by next weekend. Tuesday will see temperatures in the mid
to upper 80s for most before cooling down about 5 degrees in the
low to mid 80s for Wednesday. Gradual warming will take place
through the rest of the week as the ridge builds back in. By
Saturday, much of the area could see mid to high 90s with low
lying areas along the Yellowstone seeing a 40-60% chance of
getting to 100 degrees. Low temperatures should stay in the 60s
even on the warmest days keeping the heat risk down for now. That
being said, some heat risk can`t be ruled out as the heat will
definitely be uncomfortable for some. Torgerson
&&
.AVIATION...
Smoke will continue to lower visibilities across much of the
area today, especially KMLS and KBHK. We should start to see a
gradual clearing from west to east tonight and into tomorrow.
Outside of smoke, increased northwesterly winds (gusts around 20
knots) will impact eastern Montana during the afternoon today.
Dry conditions will persist. Arends/Torgerson
&&
.PRELIMINARY POINT TEMP/POPS...
Sun Mon Tue Wed Thu Fri Sat
-----------------------------------------------------------
BIL 061/091 062/094 062/087 057/084 059/088 061/093 064/097
00/H 00/B 10/U 00/U 00/U 00/U 00/U
LVM 055/091 057/092 052/085 050/084 052/086 054/092 057/095
00/U 01/B 10/U 00/U 01/U 00/U 00/U
HDN 058/090 060/096 061/088 055/085 056/091 060/095 062/099
10/H 00/B 10/U 00/U 00/U 10/U 00/U
MLS 061/085 060/094 065/087 059/083 056/087 060/092 064/098
11/K 00/B 30/U 00/U 00/U 10/U 00/U
4BQ 061/087 060/095 065/087 059/085 057/088 060/091 063/097
00/K 00/B 20/U 10/U 00/U 20/U 00/U
BHK 055/081 054/089 060/086 054/082 053/084 057/089 060/095
10/K 00/B 30/U 00/U 00/U 10/U 00/U
SHR 056/087 057/095 060/086 053/083 053/087 057/090 058/094
00/H 00/B 10/U 00/U 01/U 11/U 10/U
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...None.
WY...None.
&&
$$
weather.gov/billings
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1142 PM EDT Sat Jul 15 2023
.AVIATION...
Remnant convective clusters across the thumb will lift off to the
northeast overnight. Nocturnal destabilization within weak mid level
subsidence will keep the terminals free of convection through the
night. Based on current temp/dewpoint spreads, MVFR type visibility
restrictions in fog are expected overnight. Canadian wildfire smoke
will overspread the region on Sunday. Based on sfc visibilities
upstream, MVFR based restrictions in haze/smoke are expected through
the afternoon and evening Sunday.
For DTW...There was not much opportunity for diurnal mixing to erode
the low level moisture across metro Detroit today. Given the weak
flow overnight, there are several model solutions which indicate fog
and IFR low clouds developing across the area. With ongoing low
cloud development noted just east, IFR conditions will be mentioned
in the metro TAFs overnight.
.DTW THRESHOLD PROBABILITIES...
* Low in visibilities at/or below 1/2SM or ceilings at/or below 200
ft Sunday morning.
&&
.PREV DISCUSSION...
Issued at 403 PM EDT Sat Jul 15 2023
DISCUSSION...
Heavy rainfall tendencies gained traction in the convective pattern
during early afternoon with a flare-up in the Tri Cities to northern
Thumb. The band formed on the north flank of the short wave/MCV
moving through the central Great Lakes where some extra deformation
capitalized on PW peaking near 1.8 inches. Eastward shearing of the
wave is carrying the banded activity into Lake Huron leaving surface
based storms developing in northern/western Lower Mi. This is where
MLCAPE is peaking in the 1500-2000 J/kg range but where the
resulting convection is being increasingly abandoned in a weak wind
shear profile on the heels of the short wave. The result is expected
to be a more pulsey storm mode still capable of a near severe wind
gust but more due to cores of heavy rainfall and associated
downburst potential than any other greater organization. The pulse
mode also makes convection more vulnerable to loss of daytime
instability leading to a dissipating trend by mid evening.
Today`s short wave system exits eastward late tonight while carrying
the deeper moisture axis along with it. This is shown by decreasing
850-700 mb theta-e projections followed by a more neutral moisture
advection pattern during Sunday. PW decreases from about 1.8 inches
today down toward about 1 inch by Sunday afternoon but it`s not dry
enough to substantially limit instability. Consensus of
deterministic model guidance projects MLCAPE nearing 1500 J/kg
around and ahead of the surface trough/cold front moving in from the
Midwest. The instability profile occurs under a broadly diffluent
mid level flow that still supports westerly shear around 25 knots
but is otherwise more weakly forced compared to recent days.
Scattered peak heating thunderstorm coverage looks good in this case
with an isolated storm on the strong side due to wind gusts. Model
soundings indicate just enough mid level dry air for some negative
buoyancy contributions to any stronger updrafts/precipitation cores.
Also notable with the cold front/trough is the pooling of near
surface wildfire smoke which is very evident in satellite and
surface observations spanning the Plains and Midwest. An Air Quality
Alert has already been issued in Lower Mi for Sunday.
Weaker large scale forcing Sunday afternoon strengthens considerably
Sunday night into Monday as the next short wave trough arrives
around what seems like a central Canadian mid level perma-low. Model
fields depict a sharp backing and strengthening low to mid level
wind trend boosting 700 mb flow to near 40 kts along and ahead of
the height fall center which draws a well-defined elevated
instability axis into Lower Mi late Sunday night. The strong
moisture transport results in 850 mb LI reaching 0 to -3C in RAP and
GFS projections combined with the short wave supplied DCVA and some
right entrance region upper jet support for a strong forcing
profile. These elements are worthy of likely POPs for showers Sunday
night, mainly from midnight to 6 AM, with a chance of sub-severe
thunderstorms.
Passage of the Sunday night mid level trough sweeps moisture out of
the area for dry conditions Monday, or at least for low end chance
POPs confined toward the Ohio/Canadian border. The relative min in
rain potential is then short-lived as another smaller scale trough
feature is advertised in model solutions reaching the area later
Monday night into Tuesday. There is greater model variability on the
depth of the short wave vs progression of the closed low. Taken at
face value, model consensus indicates lower POPs farther north
Tuesday as the long wave blocking pattern breaks down followed by
renewed zonal flow thunderstorm potential through mid week.
MARINE...
A broad upper-level low will continue to meander over western
Ontario and the northern Great Lakes through the remainder of the
weekend bringing periods of showers and thunderstorms to the region.
Scattered thunderstorms will continue to remain possible through the
evening hours across the southern half of the local waters, with a
few storms being strong to possibly isolated severe with gusts in
excess of 34 knots, large hail to 1 inch, and frequent cloud to
ground lightning. A weak cold front will then track across the
region Sunday night into Monday morning, bringing a drier period of
weather. Outside of erratic winds and waves associated with
thunderstorms, light south/southwest winds will prevail, veering
more west/northwesterly Monday.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...None.
Lake St Clair...None.
Michigan waters of Lake Erie...None.
&&
$$
AVIATION.....SC
DISCUSSION...BT
MARINE.......IRL
You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.
AREA FORECAST DISCUSSION
National Weather Service Kansas City/Pleasant Hill MO
643 PM CDT Sat Jul 15 2023
.Discussion...
Issued at 325 PM CDT SAT JUL 15 2023
Key Points:
* Thunderstorms are possible on Sunday, some of which may produce
gusty winds and perhaps hail.
* Warm conditions mid-week with heat indices near 100F across
central Missouri.
Detailed discussion...
Lower that normal confidence on forecast for tomorrow, especially on
thunderstorm timing. On the large scale, cut off upper level low
south of Hudson Bay will remain over the Great Lakes region through
Tuesday leading to northwest flow aloft across the central US. This
may lead to bouts of smoke advecting south originating from Canadian
wild fires. Low level jet is expected to develop across Kansas
tonight leading to broad warm air advection across central Nebraska.
HRRR has been fairly consistent over the last several runs
suggesting the potential of elevated storms developing near 09Z in
south central Nebraska, and building southeast with time.
Deterministic runs are largely dry over this same time frame.
Additional rounds of storms are possible later in the day as a weak
front drops south across the Upper Midwest. Instability really
varies depending on whether the first round of storms even happen,
but broad generalization suggests 1000-1500 J/kg of CAPE. 0-6 km
bulk shear looks to be on the order of 25-35 knots, suggesting the
potential for some organization of storms. Forecast soundings
suggest relatively high based storms, with dry sub cloud layer
indicating the potential for gusty winds with any storms that
develop. Can`t rule out large hail with any storms that develop,
though storms would likely evolve more towards a wind threat later
in the life cycle.
With the potential of storms earlier in the day across northern
Missouri, have lowered forecast highs with the greatest change along
and north of highway 36.
Additional rounds of storms are possible along and ahead of the main
front dropping south through the afternoon and evening hours
focusing on any outflow boundaries.
Storm chances dwindle Sunday evening, but are renewed Monday night
as shortwave moves across the region. Mid and upper level flow
increases with this wave, leading to increased shear and another
chance of severe weather mainly through the overnight hours Monday
night into Tuesday morning.
As upper low across the Great Lakes region begins to break down on
Tuesday, ridge across the west builds east leading to hot and humid
conditions. Potential for heat indicies to approach 100 F,
especially along and south of I-70 Tuesday into Wednesday.
A fairly significant shortwave is expected to move east in southern
Canada, flattening the ridge and possibly leading to seasonal
temperatures late next week.
&&
.Aviation...(For the 00Z TAFS through 00Z Sunday Evening)
Issued at 642 PM CDT SAT JUL 15 2023
Currently VFR at the KC metro terminals but STJ is reporting 3SM
VSBY due to haze from Canadian wildfires. Other than the
occasional mild VSBY reductions from haze, flight categories
should remain VFR through tonight into Sunday. Light winds out of
the WNW will shift to out of the SW by tomorrow morning. Another
chance for showers and thunderstorms will arrive by tomorrow
afternoon, but confidence in exact timing and location are not
high enough at this time to go beyond introducing VCSH. If any
storms do manage to impact any terminals tomorrow, gusty winds up
to 50 mph or higher could be possible.
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
MO...NONE.
&&
$$
Discussion...BT
Aviation...BMW
AREA FORECAST DISCUSSION
National Weather Service Sioux Falls SD
1059 PM CDT Sat Jul 15 2023
.SHORT TERM...(This Evening through Sunday)
Issued at 242 PM CDT Sat Jul 15 2023
Northwest upper flow continues through the first part of the week
and will bring south a lot of smoke from the Canadian wildfires.
Smoke is obscuring the sky for most of the region and will
continue to do so through Sunday night. The RAP and HRRR smoke
models have smoke clearing out after midnight Monday morning as
high pressure builds in. Enough smoke is mixing to the surface
that it is having impacts on visibility. Currently visibilities
range from 2 to 4 miles. Air quality is currently in the unhealthy
category for the Sioux Falls area. Air quality is monitored at the
airnow.gov website, if you are interested in more information
please visit that site. Populations who are sensitive to air
quality may need to use caution the next few days. Even healthy
individuals may begin to notice lung and eye irritation.
TONIGHT: For the rest of the afternoon and evening we are
expecting dry conditions. Winds are well aligned and northwesterly
through most of the troposphere. This indicates efficient mixing
if we can warm enough to erode the cap. Gusts of 20 mph with a few
gusts up to 25 mph are possible. The boundary layer quickly
decouples after sunset and so wind gusts will quickly die down
tonight. Temperatures will be slightly limited due to the smoke,
expect highs to reach the upper 70s to mid 80s. This evening a
weak cold front sags south from Montana through Minnesota and
Wisconsin but it will do little to clear the smoke out. Lows for
tonight will be in the upper 50s and low 60s.
SUNDAY: The front becomes stationary and stalls out just along the
South Dakota and Nebraska border through Sunday evening. A 200 and
500 mb jet max exit region just north of the stationary front
provide synoptic support for some isolated showers focused along the
stationary front Sunday morning. Showers will quickly clear out and
be followed by a pleasant, though smokey day with highs in the
upper 70s to mid 80s. Mixing Sunday will be slightly less
efficient, and so wind gusts will be slightly lower. Especially
along the SD/NE boarder and south where the morning showers will
inhibit erosion of the cap until later in the afternoon. Gusts of
15 to 20 mph are expected until after sunset. Sunday night a mid-
level wave and an area of increased vorticity will trigger another
round of showers and thunderstorms, this time focused east of
I-29. Those quickly move out followed by an unseasonably cool
night with lows in the 50s.
.LONG TERM...(Monday through Saturday) Issued at 242 PM CDT Sat
Jul 15 2023
MONDAY: The weekend`s front sags well south by early Monday with
sfc high pressure building south in its wake. An early look at
smoke potential indicates we may have smoke streaming through
aloft still, but the bulk of the sfc impacts and visibility
reductions should be pushed well south of the forecast area. In
short, it`s looking to be a very pleasant day with light winds and
afternoon high temperatures only reaching the 70s to mid 80s.
A more active, wetter weather pattern sets up mid week as omega
blocking centered over the West finally breaks down and the central
U.S. comes under quasi zonal flow aloft. Confidence is increasing
that a ridge riding shortwave aided by the right entrance region of
a developing jet streak and the nocturnal low level jet looks to
initiate convection in the western and/or central Dakotas late
Monday night. Areas near and west of the James River Valley are most
likely to see convection overnight as storms track southeast. Strong
deep layer shear would support severe weather threat with this
activity, but questions remain regarding how far east storms will
track Tuesday morning.
TUESDAY-WEDNESDAY: Chances for showers and storms continue through
Tuesday and Wednesday as we reside within the developing warm sector
laid through the Northern Plains, but timing of this activity will
depend largely on shortwave disturbances overcoming capping as we
remain far from the best forcing for ascent. There is potential for
severe weather threat if we can get storms and sufficient
instability. During this period, temperatures rise to near to above
normal values with increasing humidity.
THURSDAY-FRIDAY: An early glance at late next week shows another
relatively cooler, dry period with sfc high pressure taking hold in
northwest flow aloft.
&&
.AVIATION...(For the 06Z TAFS through 06Z Sunday Night)
Issued at 1059 PM CDT Sat Jul 15 2023
Smoke is expected to produce MVFR visibility through Sunday
afternoon. As winds turn more to the north behind a cold front,
smoke free air will begin to advect south. VFR visibility will
first reach southwestern Minnesota in the early afternoon and then
spread southwest reaching the Missouri Valley and Sioux City by
sunset.
A weak wave will move along the Nebraska and South Dakota border
tomorrow morning. At this time it appears any instability will
remain south of Hwy 20 ahead of the wave such that any convection
will be between Hwy 20 and I-80 in Nebraska and Iowa. However,
given one or two models, including the HRRR do bring instability
north of Hwy 20 by mid morning and produce isolated convection,
cannot completely rule a couple of storms but the chance remains
less than 20%. Therefore, have not included in the KSUX TAF at
this time. Similarly, models shows 1000-1500 J/kg of MLCAPE along
a cold front which will reach the Missouri Valley and KSUX area by
mid to late afternoon. However, passage of the wave earlier in the
day looks to produce large scale subsidence in this area. Similar
to the morning, cannot completely rule out a couple of storms
developing along the boundary east of a KYKN to KMJQ line but the
probability is only 20% so will keep out of the TAF at this time.
With the frontal passage, winds will gust up to 25 kts at KFSD and
KHON during the afternoon on Sunday with the a small chance of
gusts over 30 kts at KHON where deeper mixing could bring down
higher winds above 800 mb. At this time, we believe the thick
smoke aloft will limit the gust potential below that threshold.
Once smoke clear later in the day VFR conditions are expected
after 00Z.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
IA...None.
NE...None.
&&
$$
SHORT TERM...AJP
LONG TERM...BP
AVIATION...Schumacher
Area Forecast Discussion
National Weather Service Glasgow MT
843 PM MDT Sat Jul 15 2023
.DISCUSSION...
EVENING UPDATE:
Near-term haze grids were updated with the latest model guidance.
Visibility across the region continues to vary between 1 3/4 to 4
miles and is expected to linger through the overnight hours.
Otherwise, no changes were made to the going forecast.
-thor
AFTERNOON UPDATE:
Little improvements have been made with regard to visibility
reductions from smoke, although the overall plume has shifted
slightly southwest. Based on current observations and
smoke/visibility forecasts showing continued periods of 3 mile or
less visibility, the Dense Smoke Advisory was extended for most
areas until 3pm Sunday. Improvements in Sheridan and eastern
Roosevelt counties led to cancellation, while SW Phillips and
Petroleum were added as denser smoke has drifted in that
direction. Once winds begin to pick up and turn more easterly by
Sunday night, at least the near-surface smoke should be mostly
cleared out of the area. The rest of the forecast outlined below
remains in track, with focus on the frontal system arriving Monday
night and heat building by next weekend.
-Zanker
MORNING DISCUSSION:
Synoptic Setup: Forecast begins with a cool cored airmass centered
over central Manitoba and spread out over the central third of
Canada and a hot, high pressure over the Desert Southwest and
Intermountain West. A weak ridge juts north from the Intermountain
West and runs up into the Pacific Northwest and southern British
Columbia. Northeast Montana lies between the two largest
airmasses under quasi-zonal to northwest flow.
Today: Smoke and haze are drifting down in the northwest flow with
higher concentrations lingering along a line from Opheim to Poplar
to Sidney. Visibilities at 2AM appears to have risen this morning
to 6 to 4 miles for most places. But, 2 miles still remains in
places such as Poplar. Unfortunately, the visibility and air
quality will likely drop down again for today after sunrise due to
mixing dragging more of the elevated smoke in the column down to
the ground. 03Z RAP Smoke points towards conditions beginning to
improve Sunday afternoon as smoke thins along the boundary it has
been trapped around.
Sunday night into Monday: Ridge to the west will gain strength
and move eastward exerting more influence and warmth across the
region. Highs should reach into the 90s by Monday and RH will
start to lower down to critical levels and will need watching. A
thermal trough will form under the ridge and allow for afternoon
thunderstorms to form out in western zones and just west of the
ridge axis.
Monday night through Tuesday: Ridge will peak and exit the region.
A thermal surface trough will set up just ahead of the cold front
and become a focus for thunderstorms, especially after the ridge
axis aloft passes over and exits. Then the cold front on its
heels will barrel through. There is a chance for increased PoPs
along with isolated severe weather with this passage. In addition,
a warm sector ahead of the cold front may drop RH across
southwest zones low enough that fire weather concerns could become
critical with the frontal passage and sudden increase in wind
speeds.
Tuesday night to Wednesday night: Expect cool and dry conditions
here. With perhaps a isolated showers or two along the far
northeast International border as the backside of the low tries to
wrap remnant moisture down across the area in northwest flow.
Thursday onward: Expect a slow warm up through this passage of 12
hour periods. Most of which are mostly dry till Saturday. By
Friday 90s for highs may be in store again with possible 100s
rearing their ugly heads around Saturday if the ensembles do not
change. GAH
&&
.AVIATION...
UPDATE: 0230Z
FLIGHT CAT: VFR - IFR
DISCUSSION: SMOKE and HAZE will keep the sky obscured with MVFR
visibility common through the TAF cycle. IFR visibility with MVFR
ceilings (vertical visibility) is likely at times, particularly
for KGGW and KOLF.
WIND: Northwest 10-15 knots through early evening. Then, veering
to the north and decreasing to light and variable after sundown
through the night into Sunday morning.
-Zanker/thor
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...
Dense Smoke Advisory until 3 PM MDT Sunday for Central and
Southeast Phillips...Central and Southern Valley...Daniels...
Dawson...Eastern Roosevelt...Garfield...McCone...Northern
Phillips...Northern Valley...Petroleum...Prairie...Richland...
Southwest Phillips...Western Roosevelt...Wibaux.
&&
$$
weather.gov/glasgow
AREA FORECAST DISCUSSION
National Weather Service Hastings NE
640 PM CDT Sat Jul 15 2023
...Aviation Update...
.DISCUSSION...(This evening through Saturday)
Issued at 442 PM CDT Sat Jul 15 2023
-- KEY MESSAGES FOR THE ENTIRE 7-DAY FORECAST (generally
chronological):
* Our "old friend"...Canadian wildfire smoke...has returned with a
vengeance especially in the upper levels of the atmosphere,
making for a very milky sky in what would otherwise be a very
sunny day. Fortunately, our coverage area (CWA) is only catching
a "glancing blow" of the southern fringes of the more noticeable
surface-level smoke (it is much more concentrated especially
from SD into IA/southern MN), but with a few of our automated
airport sensors reporting mildly-reduced visibility, we
certainly have a minimal amount of surface-level smoke around,
and thus we are carrying "patchy smoke" in the official forecast
for parts of the area through Sunday.
* Although some very spotty/likely weak thunderstorm activity is
possible mainly in our far southern zones through around sunset,
the very late night/early Sun AM hours could bring a round of
elevated thunderstorm development to especially the northeast
1/2 of our CWA, a few of which could produce small hail.
* Although details regarding storm coverage/intensity are
admittedly still a bit "fuzzy" for only being 18-24 hours out,
Sunday daytime-early evening severe storm potential is is
currently our paramount shorter-term focus. Very generally, a
few severe (but likely elevated) storms appear possible during
the morning especially in Neb zones, with perhaps more surface-
based severe possible afternoon-early evening as activity shifts
more toward/south of the KS border. The majority of the CWA is
an SPC Marginal Risk (level 1 of 5) with KS zones "upgraded" to
Slight Risk (level 2) on the latest Day 2 update.
* Following a lull in storm chances late Sunday night through
pretty much all of Monday, another round of late night/early AM
storms appears possible especially in our northeast zones late
Mon night/early Tues AM. SPC already has this area in a Day 3
Marginal Risk area to account for this (likely mainly a hail
threat).
* Although still largely shy of official Heat Advisory criteria of
105+ degrees, heat index readings for both Mon-Tues afternoons
are currently projected to reach "near-Advisory" levels of 100+
especially in our far southern CWA (Rooks/Osborne/Mitchell KS).
This mention continues in our Hazardous Weather Outlook
(HWOGID).
* Getting into the longer term periods (Tues-Sat): Nothing really
notable to "key in on" at this point. There are a variety of
mainly lower-end thunderstorm chances at various/times
locations, but nothing to be particularly confident in.
Temperature-wise: honestly very "typical" for mid-July, highs
mainly mid 80s to low 90s (no real excessive heat concerns
except aforementioned Mon-Tues far south) and lows mainly 60s.
-- MORE DETAILS/FURTHER INFO BUILDING UPON THE KEY MESSAGES ABOVE
(including all further discussion of Monday daytime-Saturday):
- General overview of the large-scale upper air/surface weather
pattern and associated temperature/convective trends:
At least in the "big picture", the latest ECMWF/GFS model
solutions show pretty good agreement through the entire 7-day
forecast, keeping general forecast trend confidence on the higher
side (albeit plenty of question marks especially regarding longer
term rain/thunder chances). Breaking things down into somewhat
logical "chunks:"
- 1) Tonight-Monday night:
Through these next 48-60 hours, our area remains under
persistently and seasonably-strong northwesterly flow aloft, as
we are sandwiched in between prominent upper ridging centered over
the Desert Southwest (driving the recent national news-worthy
heat in that region), and a persistent trough from around the
Great Lakes northward into Canada. While there are no truly
noteworthy small- scale disturbances headed our way within this
flow regime, a series of weak waves interacting with a combination
of moisture advection/low level convergence (mainly late-night
low level jet forcing) and weak surface frontal passages (mainly
daytime) will promote a few distinct opportunities for storms
(some possibly severe)...mainly Sunday daytime-early evening and
again late Mon night.
- 2) Tues-Thurs:
Although no noteworthy changes to speak of in the big picture, if
anything the prominent Desert Southwest ridging edges a bit more
eastward/northward. Even so, our flow aloft will remain
seasonably-strong, albeit a bit more west-northwesterly versus
current northwesterly. Various, still "murky" thunderstorm chances
continue during this time, but confidence in any of them is not
overly-high, and thus PoPs are mainly under 30 percent through
this time.
- 3) Fri-Sat:
These days currently signal what could be the beginning stages of
an upper air shift that could eventually result in an overall-
hotter temperature regime for especially the week of July 24th
(beyond our current 7-day forecast). However, at least during this
time, both the ECMWF/GFS suggest that the western upper ridge will
expand northward into the Intermountain West/Central Rockies,
turning our flow aloft increasingly north-northwesterly. Even so,
the heart of the ridging should remain far enough west of us to
keep temperatures in check (not overly hot) and also keep us prone
to intermittent thunderstorm chances. For those already making
plans for NEXT weekend, at least for now our official forecast
for Saturday is dry, but raw model data/guidance suggests this is
no guarantee to stay this way.
-- SHORTER TERM DETAILS FOCUSED SOLELY ON THESE NEXT 36 HOURS
(through late Sun night/early Mon AM):
- CURRENT/RECENT WEATHER SCENE AS OF 4 PM (including forecast
trends through around sunset):
Overall, no big surprises today. Unfortunately (but as was
becoming apparent 24 hours ago), mainly upper level Canadian
wildfire smoke has sunk southward into our region aggressively
today, marring what would have otherwise been a day with
considerable sunshine most areas. As already hit on above, our CWA
marks the far south-southwestern edges of any lower-level (near
surface-based) smoke within the Central Plains, as we fortunately
remain a few hundred miles south/west of the worst swath of near-
surface smoke centered from northwest SD into IA/MN (that also
catches northern Nebraska). Given that we have just enough low
level smoke to bring minor visibility reductions to some automated
airport sensors (especially in/near our northern CWA), which also
means that that some of this smoke is likely perceptible to the
nose, have opted to continue a formal mention of "patchy smoke" in
our forecast for mainly Nebraska areas where it will remain most
prominent.
Getting on to other current/recent weather topics, in the mid-
upper levels, water vapor satellite and short term model data
confirm broad northwesterly flow aloft, with our region sandwiched
between a prominent southwestern ridge and Great Lakes/southeast
Canada trough. With no noteworthy disturbances embedded within the
flow now or in our very near future, forcing aloft is quite
minimal today. That being said, with an airmass that is only
weakly capped and featuring as much as 1000-2000 J/kg mixed-
layer CAPE (highest in our south), this is one of those summer
afternoon/early evening that are prone to featuring "surprise"
isolated showers/storms especially wherever low level convergence
is slightly maximized. While have maintained a dry forecast for
the majority of the CWA late this afternoon-evening, do have
slight thunderstorm chances extending across much of our KS zones
up into the Furnas County area, as satellite/radar trends and
higher-res model data suggests these southern areas will be most
prone to spotty activity through around 10 PM/sunset. However,
will need to watch another area of shallow cumulus in our far
northeast (Polk County area) just in case something manages to
"pop" there too with afternoon heating. Fortunately, weak mid-
level lapse rates should (in theory) keep any threat for severe
storms to a minimum.
At the surface late this afternoon, no big features to speak of
(other than the limited smoke issues). Breezes are generally 5-15
MPH out of the west-northwest (strongest north-northeast/lightest
south-southwest). Although the upper smoke could hold down highs
slightly from expectations in some areas, overall things working
out fairly well, with the majority of the CWA likely reporting
official highs between 86-91.
- LATER THIS EVENING-SUNRISE SUNDAY (through 7 AM/12Z):
Once any possible early evening (mainly heating-driven) isolated
convection fades away by around nightfall, we should enter a lull
in storm chances for several hours CWA-wide (until at least 3 AM
or so). However, between mainly 3 AM-7 AM, various models
(including the favored HRRR) ignite a northwest-to-southeast swath
of elevated storms mainly within the northeast half of our CWA
(mainly Tri Cities area northward/eastward), with this activity
tied to the exit region of a fairly classic nocturnal low level
jet (increasing to 30-40KT out of the southwest overnight at the
850 millibar level) and the associated surge of low-mid level
moisture advection. Although MOST of this very late night activity
will probably be sub-severe (and SPC has held off on introducing a
formal Marginal Risk up to this point), the combo of elevated CAPE
(mainly 850-700 millibar layer) up to around 1000+ J/kg and decent
deep-layer shear of 30-40 KT could conceivably foster a few strong
to marginally-severe hail cores that bear watching. Otherwise
overnight, patchy low-level smoke with minor visibility reductions
will remain possible especially in our northeast half. Breezes
overnight will be light (mainly under 10 MPH) and trend more
south-southwesterly with time. Low temps were changed little,
ranging from low 60s north to mid-upper 60s south.
- SUNDAY DAYTIME-EARLY EVENING:
This time frame is by far our paramount focus for possible
(probably a few likely?) severe storms, although details still
remain a bit murky. In the big picture, very low amplitude
disturbances will continue working overhead in the northwesterly
aloft, essentially a "glancing blow" from a stronger wave swinging
through northern MN/WI. At the surface, at least two surface
boundaries will likely be in play, one likely outflow-driven from
morning convection, while another, secondary weak cold front
gradually works its way southward across the CWA during the
afternoon-evening. As for convective coverage/intensity, leaning
heavily on the latest 18Z HRRR for trends, scattered to perhaps
numerous elevated storms at daybreak mainly in our northeast 1/2
will likely persist much of the morning into early afternoon,
gradually shifting south-southeast with time. Some of this
activity could be severe initially with mainly a hail threat, but
perhaps taking on more of a wind threat as it becomes more
surface-based by early afternoon. However, of greater concern is
the possibility of more legitimate "true" surface based
development by mid-late afternoon especially near/south of the KS
border, where (assuming that earlier day storms don`t "junk up"
the environment too much), there could be at least 2000-3000 J/kg
mixed-layer CAPE and decent 30-40KT of deep layer shear to support
vigorous storms including some supercell structures (hail to at
least ping pong ball size possible along with damaging winds).
This is certaintly the primary reason for SPC upgrading our KS
zones to a Slight Risk. However, at least small chances for strong
to maybe even marginally-severe spotty storms could linger well
into the afternoon-early evening even in our NORTHERN zones, as
weak convergence along the secondary weak front could spark some
activity mainly north of I-80 (not really depicted by 18Z HRRR but
hinted at by other models such as NAM).
Briefly touching on other Sunday weather elements, there could
still be some minimal low-level smoke around, but likely to less
degree than today-tonight. Confidence in high temperatures is
lower-than-usual for mid-July owing to uncertainties regarding
coverage of convection, associated debris clouds etc, but for now
kept things pretty similar to previous with highs mainly 84-90
most Nebraska zones and more so 90-95 in KS zones (however, heat
index should hold under 100).
- LATER SUNDAY EVENING-OVERNIGHT:
Although probably not "guaranteed" completely dry (latest NAM
hints at some very spotty/weak, high-based activity very late in
the night), opted to maintain an officially dry forecast for this
time frame, once any early evening potentially-severe activity
fades away largely with loss of diurnal heating/weak low level
frontal convergence. Late night breezes will generally average
around 5 MPH out of the east-northeast, and overnight low temps
are aimed similar to very slightly cooler than tonight (most of
the CWA low-mid 60s except for upper 50s far north).
&&
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Monday)
Issued at 632 PM CDT Sat Jul 15 2023
Many upstream obs over northern NE continue to report 5-6SM in
HZ/FU. Looking at the RAP smoke model, thinking we can expect to
see similar conditions overnight, gradually diminishing through
Sunday morning. Started off with 6SM and HZ, then backed off on
that through the day Sunday. Convection has been a tricky
forecast...elected to go VCTS from 12-21Z at the TAF sites,
although confidence is a little higher for KGRI than for KEAR,
based on the latest convective models. Winds tomorrow are all over
the place, so decided to continue with trying to capture the
predominant wind direction for now.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
DISCUSSION...Pfannkuch
AVIATION...Hickford
Area Forecast Discussion
National Weather Service Goodland KS
733 PM MDT Sat Jul 15 2023
.UPDATE...
Issued at 722 PM MDT Sat Jul 15 2023
A subtle shortwave is helping some showers and storms across the
Palmer Divide and into Yuma and Kit Carson county. As it moves
further south and east the atmosphere should be more stable;
anticipating that that as the sun sets and instability drops the
storms should wane in coverage and intensity.
For tomorrow, I did increase pops a bit south of I-70 during the
afternoon as isentropic analysis from the RAP shows an area of
enhanced lift across eastern Wallace through Gove county. This
along with a shortwave and 250mb jet streak aloft should help
support some storms, possibly severe with effective shear of 35-45
knots present and MUCAPE greater than 2000 j/kg. The storms may be
a bit more in coverage especially if this isentropic ascent zone
sets up than what CAMS show as CAMS have recently been struggling
with coverage in subtle setups.
With a high amplitude ridge over the the area on Monday mid to
upper 90s continue to look likely. Newest guidance did increase
dew points across the area which is allowing a corridor of 100+
heat indices to be present across Graham, Gove, Logan, Sheridan
counties. If the trends continue to increase dew points will need
to monitor for potential heat headlines.
&&
.SHORT TERM...(This evening through Monday night)
Issued at 149 PM MDT Sat Jul 15 2023
An upper ridge over the western CONUS has the area under west-
northwesterly flow aloft. Showers are moving east-southeastward
across portions of the area this afternoon. Current visible
satellite shows smoke filtering in over top of the ridge, extending
southward into Nebraska, Iowa, and Missouri.
Current showers are expected to exit the area within the next few
hours with afternoon highs climbing into the 80s and overnight lows
falling into the upper 50s to middle 60s. Slight chance we could see
a few showers pop up briefly again this evening.
The upper ridge continues to shift eastward with flow over the area
becoming increasingly northwesterly into the start of the week. As
another shortwave moves through the area tomorrow, will see chances
for storms to develop along a front during the afternoon before
moving southeast. Given ample moisture and instability over the
area, storms that develop will have potential to become strong to
severe, especially for locations along and east of Highway 25.
Primary hazards include large hail and strong winds, with
approximate timing of storms between 19Z-01Z. Temperatures climb
back into the 90s tomorrow followed by overnight lows in the low to
middle 60s.
On Monday, afternoon highs reach the middle to upper 90s with
overnight lows in the middle 60s to low 70s.
.LONG TERM...(Tuesday through Saturday)
Issued at 109 PM MDT Sat Jul 15 2023
For the extended period, the latest GFS/ECMWF continue to show a
broad upper ridge to be the main focus, driving wx conditions area-
wide. Currently the ridge is elongated through the southern Plains
and to the west, but towards the latter portion of the period, a
shift to more NW flow aloft will occur. Despite this shift, the
midweek timeframe will see near to above normal warmth with 850
temps around +28c to +32c, before shifting lower as chances for
clouds/precip increase as the week progresses.
At the surface, Tuesday will have a low passage in the
afternoon/evening hours, shifting winds to more northerly. This will
be followed by a digging surface ridge from the north. Models trend
this ridge slowly E/SE through the extended period. Low pressure
sets up well south of the cwa, with a front extending across
southern KS into Colorado. As a result of this, surface flow will
trend from mainly northerly on Tuesday to E/SE for the latter half
of the forecast. This wind shift will re-amplify low level moisture
area-wide with PW values 1-1.5". By the end of the week, 1.5-2" is
possible, with dewpts will remaining high in the 60s.
This continued presence of ample low level moisture along the front
will interact with passing 500/700 mb shortwaves, to trigger rw/trw.
Strongest systems look to pass towards the latter portion of the
forecast. Highest pops are focused there, with afternoon/evening
hours best chances for rw/trw. This will continue the threat for
locally heavy rainfall pretty much each day, peaking next Thursday
and Friday. So expecting flooding concerns to remain on top of
strong to severe storm potential.
For temps, near to above normal readings are expected for daytime
highs across the area. On Tuesday, mid 90s to around 100F are
expected. Lower to mid 90s for Wednesday will give way to mid 80s to
lower 90s on Thursday. Slightly lower Friday with mid 80s area-wide.
Going into the beginning of next weekend, slight warmer with upper
80s to lower 90s expected. Heat indices during the hot part of the
day will range near to slightly above normal in spots. For overnight
lows, expecting a range in the 60s with warmest areas east.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 441 PM MDT Sat Jul 15 2023
VFR conditions are currently forecasted at each terminal for this
TAF period. Some CAMS have a long track storm from the Front Range
making it near the KGLD terminal from 02-04Z, overall based on the
lack of convection in obs vs what CAMS show will leave it out of
the TAF for now but will watch through the next few hours. Winds
will remain southerly through mid afternoon Sunday as a
disturbance moves through allowing winds to turn northerly. Some
storms will be possible across the area Sunday, but will leave out
of the TAF for now as they are anticipated to be widely scattered
in nature.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...Trigg
SHORT TERM...CC
LONG TERM...JN
AVIATION...Trigg
Area Forecast Discussion
National Weather Service Green Bay WI
1015 PM CDT Sat Jul 15 2023
Updated aviation portion for 06Z TAF issuance
.SHORT TERM...Tonight and Sunday
Issued at 246 PM CDT Sat Jul 15 2023
The latest RAP analysis and satellite/radar analysis show an upper
level low pressure system spinning across central Canada and weak
cold front moving southeast over northwest Wisconsin and the far
western Upper Peninsula. Convective clouds are building along the
front, and clusters of showers/storms are expected to develop
over north-central WI later this afternoon. Despite surface based
instability of 600-1000 j/kg, long and skinny instability
profiles will keep severe chances low, but could see brief gusty
winds in excess of 30 mph and small hail in any storm.
Elsewhere, convective models have backed off storm chances along
the lake breezes as advection of drier air from the northwest is
forecast to move across the lakeshore areas.
Forecast concerns mainly revolve around thunderstorm potential
through Sunday afternoon.
Tonight...The cold front will move across northeast Wisconsin.
Scattered showers and storms will likely persist along the cold
front into north-central and far northeast WI into the evening.
But with diminishing instability, showers will likely diminish as
well by late evening. Then partial clearing should occur
overnight. Lows ranging from the the lower 50s to lower 60s.
Sunday...The upper low over Canada will drop into the Lake
Superior region. Arrival of the upper in concert with increasing
daytime instability (500-800 j/kg of cape) will lead to a growing
shower/storm threat through the afternoon. Wind fields look quite
impressive (35-40kts of effective shear), so if the instability
can materialize, a few strong storms appear possible. Most likely
looking at a straight line wind threat, but small hail could also
be possible given the low wet bulb zero heights. Cooler highs in
the upper 60s to upper 70s.
.LONG TERM...Sunday Night Through Saturday
Issued at 246 PM CDT Sat Jul 15 2023
The focus of the extended forecast will mainly be on the midweek
system as another frontal boundary crosses the area Wednesday into
Thursday.
There remains a lingering chance for some stronger thunderstorms
Sunday evening into early Sunday night as a fairly vigorous
shortwave rounds the base of the upper low. Wind shear and wind
gusts will be the main concern as forcing appears to be fairly
decent, despite a relative lack of instability. Any storms that
are ongoing early overnight will make a fairly quick departure
however, bringing back quieter conditions for the latter half of
the night into Monday.
Quieter conditions then follow for Monday. Although there is still
enough moisture and forcing around to produce a stray shower or
two across the far north, most of the region will likely see a
return of dry conditions for most of Monday and Tuesday.
Temperatures during this time will also run cooler for Monday,
with highs mainly in the 70s. By Tuesday, as winds begin to turn
southwards again, highs will come back closer to normal in the
80s.
As we get into Wednesday and Wednesday night, temperatures will
continue to warm across the area ahead of the cold front.
Preliminary timing brings the front through the region late in the
day on Wednesday, which could mean this will be our next chance
for some stronger storms if diurnal instability manages to
increase ahead of the front itself. That said, it`s still a little
early to assess severe weather potential, but this will be the
timeframe to watch going forward.
Behind this, high pressure returns for the rest of the extended
forecast Thursday and Friday, bringing back quieter weather to
start off next weekend.
&&
.AVIATION...for 06Z TAF Issuance
Issued at 1004 PM CDT Sat Jul 15 2023
Isolated showers and thunderstorms will end before TAF issuance.
Otherwise expect sct-bkn mid-level clouds overnight, along with
areas of MVFR/local IFR vsbys in smoke. Some patchy IFR fog may
also occur over northern WI and in areas where significant
rainfall occurred overnight. The smoky conditions are expected to
improve from NW to SE Sunday morning, but more smoke may arrive in
C/EC WI in the afternoon. An upper level disturbance will bring
showers and a few thunderstorms Sunday afternoon and early
evening, most numerous over northern WI. Will add a mention of
thunderstorms at RHI/AUW/CWA in the mid to late afternoon, but
confidence is not high enough to add to the eastern TAF sites at
this time.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM.....MPC
LONG TERM......Uhlmann
AVIATION.......Kieckbusch
Area Forecast Discussion
National Weather Service Grand Rapids MI
1003 PM EDT Sat Jul 15 2023
LATEST UPDATE...
Update
.UPDATE...
Issued at 1003 PM EDT Sat Jul 15 2023
Divergent low level flow over wrn Lwr MI has kept things
relatively quiet this evening, with convection remaining on the
outskirts of the GRR CWFA in areas of sfc convergence.
We`ll have to keep an eye on the convection approaching from WI
though which has warranted some Special Weather Statements, but
CAM consensus is for this activity to weaken over the next few
hours as diurnal component fades. That said, a few showers could
still sneak into the lakeshore counties for a time after midnight
before totally dissipating.
Have added some patchy fog to the fcst overnight based on the very
moist look in HRRR soundings between 06Z and 12Z below 500 ft.
This makes sense since winds are light, dew pts are elevated, and
skies are clear (minus the smoke). Any fog or stratus which
develops overnight will mix out very quickly early Sunday as the
winds come up.
&&
.SHORT TERM...(This evening through Sunday night)
Issued at 238 PM EDT Sat Jul 15 2023
- Thunderstorms this afternoon into evening -
Thunderstorms have developed around US-10 ahead of an upper PV max
and along a wind convergence boundary (and attendant deeper moist
convection) extending from Baldwin northeastward to Presque Isle.
Convective intensity has been unimpressive but highly variable.
Severe prospects continue to look fairly low for the limited time
in which this convection will remain in the forecast area.
Remaining thunderstorm chances east of US-131 should decrease
fairly rapidly by this evening thanks to a combination of exiting
convection and a loss of conditional instability.
- Smoke and reduced air quality tonight through Sunday -
As noted previously, an air quality alert is in effect for the
area on Sunday due to entrainment of near-surface smoke from the
west. We already see early indications of smoke at the lakeshore
based on Grand Haven webcams. Recent smoke model runs suggest
that the greatest smoke concentrations will present as a southwest
to northeast oriented plume moving southeast across the forecast
area during the course of the day.
- Showers and thunderstorms Sunday night -
Confidence is high for showers and thunderstorms Sunday night.
Satellite indicates an intensifying PV lobe over north central
Canada that is expected to pivot across the forecast area Sunday
night, bringing with it what should be a solid coverage of showers
and thunderstorms. Precipitation amounts should be on the light
side, generally a tenth of an inch or less, due to a tenuous or
non-existent connection to moisture influx from the Gulf of
Mexico.
.LONG TERM...(Monday through Saturday)
Issued at 311 PM EDT Sat Jul 15 2023
- An overall active pattern in the long term -
The long term period begins with a deep trough centered through the
Great Lakes region Monday morning. The trough moves off to the east
on Tuesday, but it is quickly followed by another shortwave trough
approaching from the Plains Wednesday night into Thursday. A
northwest upper flow then takes over for Friday into Saturday.
Overall the long term period of Monday through Saturday will be a
bit cooler than normal given the upper troughing and precipitation
that will be possible on Monday and again Wednesday night through
Thursday night. Normal highs are in lower 80s this time of year.
Highs in the long term will be slightly cooler than normal in the
upper 70s to near 80.
- Forecast Details regarding precipitation chances -
Precipitation will be focused Sunday night ahead of the shortwave
and associated with max heating as mentioned in the short term.
Chances for showers and storms will linger into Monday however as it
will take until Monday evening to get the front through the forecast
area. At this point we only have small pops in the forecast in the
southeast CWA towards JXN (20-30 percent).
Conditions look to be primarily dry then through Wednesday as
ridging moves through. Chances for showers and storms increase again
late Wednesday night ahead of the next shortwave. Best chances for
showers and storms will be on Thursday with MUCAPE values that are
forecast to be in the 1,000-2,000ft range. Deep layer shear is on
the order of 30-35 knots so some storm organization can be expected.
Any severe threat will hinge on how much cloud and precipitation
lingers into Thursday morning which would affect afternoon
destabilization.
Friday into Saturday look to be mainly dry, but scattered showers
are a possibility given an upper trough nearby and northwest flow in
place. These showers would be diurnally driven and centered on the
afternoon and evening hours.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 813 PM EDT Sat Jul 15 2023
Tstms chances are very low the next 24 hours but do ramp up again
after 00Z Sunday evening. It`s possible that the remnants of the
recently developed storms over WI could survive as a few showers
at MKG later this evening before completely dissipating.
Some fog and/or low stratus is possible after midnight tonight
with light winds and dew pts in the upr 60s. HRRR fcst soundings
show low level inversions setting up overnight and >95 pct RH
below 500 ft. Also the HREF low cloud prog hints at some stratus
between about 06Z and 13Z. For now went with MVFR conditions in
the TAFs but some local IFR or lower conditions are entirely
possible overnight.
After any fog/stratus dissipates early Sunday, vsbys may remain
in the MVFR category due to forest fire smoke. Currently in MI it
is coming in aloft, but the smoke lowers with time and will
likely be near the sfc later tonight into Sunday. Sfc vsby
reductions of generally 3-6 miles are currently noted upstream so
will carry 5 miles in smoke in the all the TAFS, at least to
start the day Sunday.
West winds increase/turn gusty by Noon Sunday as mixing heights
climb, with sustained winds of 12-15 kts and gusts up to 25 kts
expected. These higher winds should help mix out the smoke,
probably leading to mostly VFR vsbys in the afternoon.
&&
.MARINE...
Issued at 238 PM EDT Sat Jul 15 2023
Webcams and buoys indicate lower waves compared to this morning.
Winds and waves will remain below advisory thresholds well into
next week. The only concern would be visibility restrictions due
to smoke/haze/induced fog over Lake Michigan overnight and
Tuesday. Large expected dewpoint depressions should help mitigate
the threat.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...None.
&&
$$
UPDATE...Meade
SHORT TERM...TJT
LONG TERM...Duke
AVIATION...Meade
MARINE...TJT
Area Forecast Discussion
National Weather Service Indianapolis IN
853 PM EDT Sat Jul 15 2023
.Forecast Update...
Issued at 853 PM EDT Sat Jul 15 2023
Subtle waves in northwest flow aloft combined with dry air aloft,
seen as dark channel in H20 vapor imagery, combined with CAPEs to
1500 J/kg has lead to scattered convection with compact 50 DBZ
echoes seen on 0.5 degree base reflectivity. Convection extended
from Howard to Vermillion counties and west into east central
Illinois with movement SE around 20 knots. This activity should hang
around another hour or two before loss of solar heating likely takes
its toll. So, will extend small chance PoPs through 03z to account
for that. Otherwise, light winds, mostly clear skies and dew points
in the 60s support leaving overnight lows in the lower to mid 60s.
&&
.Short Term...(This evening through Sunday)
Issued at 245 PM EDT Sat Jul 15 2023
Rest of Today.
Showers have begun to initiate along a differential heating boundary
along the edge of more robust cloud cover. Expect that these showers
will continue to expand in coverage through the afternoon with
isolated lightning. These showers will push through the area by
later this evening with no severe weather expected. A few
additional showers/storms may form later tonight,
Tonight.
A few additional showers/storms may form later tonight, but
otherwise quiet weather conditions are expected through the
overnight hours. Northwesterly flow aloft will begin to advect
higher levels of smoke during the overnight hours tonight, but the
main push of smoke/haze wont arrive until tomorrow.
Sunday.
The main concern for the daytime hours tomorrow will be the incoming
smoke and haze. The morning HRRR runs show elevated levels of smoke
at the surface ramping up after 18Z with minor visibility
restrictions expected. As of now, these impacts dont look to be as
severe as it was a few weeks ago. Widespread haze is expected with
the majority of the smoke in the mid to upper levels.
This haze will help to keep temperatures more mild than they would
otherwise, but still expect to see temperatures in the mid to upper
80s. The next shortwave within the more broad trough will impact
the area Sunday night, but that will be covered in the long term
section below.
&&
.Long Term...(Sunday night through Saturday)
Issued at 245 PM EDT Sat Jul 15 2023
An active weather pattern should persist through much of the long
term period with mean upper troughing across the eastern CONUS and
multiple shortwaves expected to track across the region. This
pattern will bring daily chances for showers and thunderstorms, but
some guidance suggest drier conditions may return toward the end of
the period. Temperatures are expected to be near or slightly below
normal for this time of year.
A few subtle upper level impulses are expected to move across
central Indiana Sunday night into Monday. Increasing large scale
ascent combined with low-level theta-e advection ahead of an
approaching cold front will likely support showers and
thunderstorms. Guidance shows a deeper plume of theta-e advection
moving in Monday which will help promote moderate destabilization by
the afternoon. Additional thunderstorms may develop during the
afternoon in this warm-moist if sufficient daytime heating occurs.
Effective bulk shear around 30-35 kts and moderate instability could
potentially support a few strong to severe storms. However,
convective overturning earlier in the day leads to uncertainty with
this scenario. In addition, a few models suggest the frontal
boundary will move through by mid-afternoon which would inhibit
additional convection. Confidence in any potential scenarios Monday
afternoon will remain low until models become better aligned.
The active pattern looks to continue through much of the week with
multiple upper waves likely moving through. There may be dry breaks
at times, but its difficult to determine exact timing within this
pattern. Confidence in exact details are low due to smaller
mesoscale processes affecting timing, location, and evolution of
these thunderstorm complexes. Guidance is hinting at a drier airmass
moving in late in the period which may put an end to the more active
pattern.
&&
.Aviation...(00Z TAF Issuance)
Issued at 652 PM EDT Sat Jul 15 2023
Impacts:
- MVFR conditions possible in smoke
- Small chance for a brief thunderstorm and MVFR conditions through
01z
Discussion:
Would not rule out an isolated thunderstorm this evening, with the
best chance at KLAF. Otherwise, should see a bit of a break from the
convection. Meanwhile, the Canadian smoke is returning per CIRA
geocolor satellite loop, and it will linger through the TAF period.
Winds will be WNW less than 10 knots tonight and W Sunday around 10
knots by afternoon.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Update...MK
Short Term...White
Long Term...Melo
Aviation...MK
Area Forecast Discussion
National Weather Service Northern Indiana
711 PM EDT Sat Jul 15 2023
.SYNOPSIS...
Issued at 700 PM EDT Sat Jul 15 2023
A few isolated showers and thunderstorms may still develop this
evening, however activity will trend downward into tonight. Dry
weather is then expected late tonight into Sunday, but there will
be another chance of showers and storms Sunday night into Monday
as a front approaches the Great Lakes.
&&
.SHORT TERM...(This Afternoon through Sunday)
Issued at 240 PM EDT Sat Jul 15 2023
Isolated to widely scattered convection will remain possible for the
remainder of the afternoon into this evening. This activity is
mainly developing along differential heating boundaries on the
western fringe of this morning`s exiting shortwave and deeper
moisture. Clouds have slowed warming, though sfc dewpoints linger in
the mid 60s to low 70s in advance of a weak sfc trough that will
slowly migrate east through the area tonight. CAPE values linger
near 1000 j/kg into tonight, mainly along and west of Interstate 69
where sfc temps have warmed into the upper 70s/near 80. Meager
lapse rates, flow/shear and overall forcing should remain on the
weak side. This should limit storm organization with brief
downpours and gusts 25 mph plus.
Hazy, smoke filled skies from Canadian wildfires then fill in from
west to east overnight into Sunday behind tonight`s weak sfc trough.
Upstream visibility trends and HRRR/RAP smoke fields suggest the
potential for smoke to work its way to the surface with some
restrictions to visibilities and air quality. This could also hold
highs down somewhat tomorrow, though still warmer than today with
the area in between systems.
&&
.LONG TERM...(Sunday Night through Saturday)
Issued at 240 PM EDT Sat Jul 15 2023
A strong pv anomaly will release southeast through southern Ontario
and the northern Great Lakes Sunday night into Monday. This and a
seasonably strong mid-upper jet will steer a cold front through
with renewed shower/storm chances. Deeper moisture and instability
looks to remain locked up southwest of the area, though still
expect decent shower coverage Sunday night given increasing large
scale ascent and enough theta-e advection/convergence within a
developing 30-40 kt low level jet. Showers could linger into
Monday morning, with preference to drier and slightly cooler model
solutions for most by Monday afternoon with the main cold front
clearing to the south.
Weak low level ridging will settle into the lower Great Lakes into
Monday night and Tuesday, likely holding into Wednesday with
mainly dry wx and seasonable temps. Did retain at least a low
chance PoP on Wednesday given close proximity to a Mid MS Valley
to lower OH Valley warm front. A model consensus does lift this
feature and its associated shot of theta-e advection into the area
around Thursday in response to the next mid level shortwave
dropping through the Upper Midwest and Great Lakes. This could
bring a round of convection through during this time, followed by
dry conditions post-frontal into Friday and Saturday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday Evening)
Issued at 700 PM EDT Sat Jul 15 2023
Smoke and haze from Canada wildfires will be the main forecast
issue this TAF period. Conditions look to drop to MVFR category
with VSBYs getting to 4SM on Sunday and perhaps lower however
confidence on VSBYs dropping below 4SM is not high. Hazy
conditions look to spill over into the late afternoon and evening
and perhaps could extend into Monday, will continue to monitor for
this possibility. Growing fine particulate concentrations will
markedly increase, amid strong mid level subsidence inversion
based at 8-10 kft and coupled with a strong morning surface based
inversion. Concern amplified with notably strong Vertical
Integrated Smoke concentration levels planted across northern
Indiana per latest HRRR smoke analysis.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
&&
$$
SYNOPSIS...Andersen
SHORT TERM...Steinwedel
LONG TERM...Steinwedel
AVIATION...Andersen
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Follow us on Facebook...Twitter...and YouTube at:
www.facebook.com/NWSNorthernIndiana
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Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
622 PM CDT Sat Jul 15 2023
.SHORT TERM...
Issued at 313 PM CDT Sat Jul 15 2023
Through Sunday night...
A weak surface boundary continues to advance across the area this
afternoon which is leading to the development of isolated showers
and thunderstorms. The boundary is currently analyzed along a
Kenosha to DeKalb line with a warm moist airmass, characterized by
upper 60s to low 70s dew points, ahead of it. RAP mesoanalysis
indicates that 1500 to 2000 J/kg of MLCAPE is present ahead of
this boundary which should allow isolated to widely scattered
showers and thunderstorms to continue to develop and linger
through early evening. The overall lack of favorable wind shear
should keep any storms below severe limits, however; any more
robust cores could generate locally gusty winds upwards of 40 to
45 mph.
Showers and storms are expected to come to an end shortly after
sunset as we lose diurnal heating and the aforementioned boundary
slides into central Indiana. Though haze from Canadian wildfire
smoke will move in behind the boundary and persist through a good
portion of the day on Sunday. This will lead to poor air quality,
especially for sensitive groups, therefore an Air Quality Alert
remains in effect through Sunday night for all of our Illinois and
Indiana counties. Despite the smoke, most of the day hours of
Sunday looks to be somewhat quiet weather wise with filtered
sunshine and highs topping out in the low to mid-80s during the
afternoon. However, breezy west-southwesterly winds are expected
Sunday afternoon as the atmosphere mixes into stronger winds aloft
which will generate gusts in the 20 to 25 mph range.
While the early part of Sunday looks to be quiet, we will have
chances for storms to return late Sunday afternoon and overnight
as a cold front dives south out of Wisconsin. In addition to the
cold front, guidance continues to show a cluster of storms
developing ahead of a shortwave impulse over Iowa and expanding
into our area Sunday evening. Guidance does show that some
instability would be present across our area as the front arrives,
but there is some discrepancy as to how much and where the
highest quantities will reside. The reason is due to uncertainty
in how low dew points will mix out Sunday afternoon which may keep
the better instability confined to our southern 1/2 to 1/3 of the
forecast area. However, if dew points can hold on, the
combination of instability and 40 to 50 kts of deep layer shear
may allow storms to grow upscale and be capable of producing gusty
winds and possibly some hail. Given this potential we our
outlooked in a marginal (level 1 of 5) severe risk Sunday evening.
Additionally, if better moisture can linger the storms could
become hefty rainfall producers which could lead to localized
flash flooding concerns. However, guidance continue to show the
aforementioned cold front being rather progressive which should
limit the residence time of storms over one area and limit this
threat, but will have to keep an eye on trends just in case.
Yack
&&
.LONG TERM...
Issued at 313 PM CDT Sat Jul 15 2023
Monday through Saturday...
Key Messages:
* Near to slightly below normal high temperatures expected
through the period but still humid
* Off and on shower and thunderstorm chances late Tuesday onward
Heading into Monday morning a few showers and storms may linger
south of I-80 as the system departs the area. High temperatures
will also be a tad cooler on Monday in the wake of the cold front
with highs only in the upper 70s to near 80.
The slightly cooler temps continue through the period with highs
in the lower 80s as the upper trough remains generally overhead
(though 60s to lower 70s dewpoints will still make it feel quite
humid). This places the region under northwest flow and right on
the edge of potentially active weather to our west and south.
Think that much of the daytime hours Tuesday look dry though
shower and thunderstorm chances may begin to increase in the
evening and overnight hours, especially south of I-80. If the pool
of higher moisture nudges north into those areas localized
flooding would be possible. Confidence in exactly where this heavy
rainfall axis sets up is on the lower side but will be generally
along an axis across central IL/IN.
Additional shortwaves move through the upper flow mid to late
next week bringing additional chances for showers and storms.
Something that will be refined with later updates as models come
into better agreement.
Petr
&&
.AVIATION...
For the 00Z TAFs...
622 PM...Forecast concerns include...
Lake breeze/outflow at MDW early this evening.
Chance of thunderstorms Sunday evening.
Canadian wildfire smoke.
A lake breeze/outflow boundary moved inland earlier this afternoon
and is now east of ORD and not expected to impact ORD before it
dissipates this evening. This boundary is near MDW and may shift
winds to the north/northeast for a short time but the boundary
already appears to be slowing and will likely slowly move east as
it dissipates this evening. Westerly winds will continue through
the period, with gusts into the lower 20kt range on Sunday.
A few showers will be possible early this evening mainly south of
MDW and near GYY. Thunder should remain southeast of the
terminals. There are a few storms in northeast IA currently and
this activity is expected to weaken this evening and not impact
northwest IL or RFD but trends will need to be monitored.
There is a chance of thunderstorms late Sunday afternoon into
Sunday evening, especially south of the terminals. Confidence for
location and coverage remains low and have opted to keep this
forecast dry until better trends emerge.
Canadian wildfire smoke has spread across northern IL with mvfr
vis reported at DPA and ARR. Its possible mvfr vis will become
prevailing this evening and it will likely remain through much of
Sunday. The limited smoked guidance available suggests the lowest
vis, possibly into the 2sm range may be Sunday afternoon. This
would be when northwest winds are gusting due to deeper mixing,
possibly bringing more smoke to the surface. cms
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.
&&
$$
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Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1054 PM CDT Sat Jul 15 2023
.SHORT TERM... (Through Late Sunday Night)
Issued at 237 PM CDT Sat Jul 15 2023
A weak surface ridge of high pressure is forecast to move across the
area overnight tonight. The combination of light/variable winds and
a mostly clear sky should lead to favorable conditions for
radiational cooling tonight, and therefore leaned closer to the 25th
percentile of the NBM for tonight`s low temperatures. This resulted
in low to mid 60s across the area or generally a few degrees below
normal for the date. Some isolated upper 50s are even possible in
favored terrain in parts of east central and southeast Missouri such
as river valleys.
Latest CIMSS true color RGB is depicting the Canadian wildfire smoke
well, extending southeastward into northern Missouri now from
southwestern Canada. Both the HRRR and the RAP suggest
concentrations of smoke may get high enough for some slight (4-5
miles) visibility reduction tonight into early Sunday, mainly across
parts of west central and south-central Illinois. By afternoon, any
smoke should exit the area as increasing westerly winds at the
surface help advect it out of the region.
There is likely to be some scattered thunderstorms across the mid-
Missouri Valley Sunday morning. Most CAMs suggest this activity may
weaken slightly with time as the low-level jet abates slightly,
though there is a pretty good signal that outflow from these
thunderstorms will continue to progress east/southeast with time.
This outflow may serve as the focus for the development of
additional showers and thunderstorms by mid afternoon. These
thunderstorms should not be particularly strong, with instability on
the low side due to poor midlevel lapse rates and a dry boundary
layer (surface dewpoints in upper 50s to low 60s). HREF
probabilities for >1000 J/kg of CAPE are only 20-40% late Sunday
afternoon. In addition, the effective shear is weak through the
early evening hours, generally on the order of 15-25 knots.
Soundings do show high LCLs with lots of dry air below the cloud
base so cannot rule some gusty winds in any cores that do gain
sufficient depth.
Additional showers and thunderstorms are forecast to develop further
to the northwest, likely across Iowa along an approaching cold
front. There is better shear with this activity, but the current
thought is by the time those storms get into our area that it would
be near or just after midnight. By this time, storms should be quite
elevated which means the chances of any strong wind gusts getting to
the surface are very small. Most unstable CAPEs are also below 1000
J/kg on most guidance so the chances of severe hail appear low.
Gosselin
.LONG TERM... (Monday through Next Saturday)
Issued at 237 PM CDT Sat Jul 15 2023
The cold front from Sunday night is expected to settle into the mid
south on Monday. Mostly dry weather is forecast, though cannot rule
out a few showers or weak thunderstorms, mainly in parts of
southeast Missouri and southwest Illinois in closer proximity to the
front. Temperatures will be about 5 degrees cooler compared to
Sunday, with highs in the low 80s to near 90 degrees from north to
south.
By late Monday night, there is increasing confidence that widespread
elevated convection will develop along/north of a northwest to
southeast oriented warm front. There is strong low-level moisture
convergence beneath a potent midlevel shortwave trough moving
through in northwest flow aloft. What is uncertain however is the
exact location of the aforementioned warm front and where the focus
for thunderstorms will be heading into early Tuesday. At this
juncture, best chances reside in central and southeast Missouri.
Temperatures on Tuesday are quite uncertain in any given location,
but the general theme will be for cooler values to the northeast and
warmer values to the southwest. Of course, the exact track of the
thunderstorms/MCS early Tuesday will be critical for the exact high
temperatures in any given location. The latest NBM percentiles show
the spread in Tuesday`s highs quite nicely, with differences between
the 25th/75th percentile over 10 degrees in some locations and over
15 degrees between the 10th/90th.
Another round of nocturnal convection/possible MCS is forecast
Tuesday night. This next round should be at least slightly further
to the northeast of its predecessor, but exactly how far is a
question mark and will depend on how far the warm front can retreat
after the morning round on Tuesday. Based on past experience,
subsequent rounds of nocturnal convection tend to be further
southwest than modeled as the boundary struggles to progress
northeast due to antecedent convection. That would suggest the best
chances of showers and thunderstorms Tuesday night more in line with
the Mississippi River.
The temperature uncertainty continues into Wednesday, especially for
those near/east of the Mississippi River due to expected clouds and
possible morning convection. There still appears to be a low threat
for dangerous heat index values (105+) Wednesday afternoon in parts
of central/southeast Missouri as the mid/upper level ridge broadens
into the south-central Plains. However, guidance has trended a bit
further southwest with the ridge itself and with the core of the
heat staying more in the south-central Plains east/southeast into
the mid south.
Any hot/humid conditions look short-lived as ensemble guidance in
the medium range is in good agreement that a longwave trough will
amplify across the eastern half of the CONUS late next week into the
following weekend. All of the 500-hPa height clusters from the WPC
show this pattern, though there are subtle differences with respect
to the strength of the trough. Regardless, at least slightly cooler
temperatures are forecast along with rain chances below
climatological normals for the middle of July.
Gosselin
&&
.AVIATION... (For the 06z TAFs through 06z Sunday Night)
Issued at 1051 PM CDT Sat Jul 15 2023
VFR flight conditions through the forecast period outside of
wildfire smoke and precipitation. Otherwise, light and variable
winds picking up from the west to northwest after 16z Sunday.
Byrd
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&
$$
WFO LSX
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1051 PM CDT Sat Jul 15 2023
.UPDATE...
UPDATE Issued at 725 PM CDT Sat Jul 15 2023
We got one last update today to the Air Quality Advisory from the MN
Pollution Control Agency for the current outbreak of Canadian
wildfire smoke. In coordination with their air quality
meteorologists, the improvements in smoke we`ve see through the
afternoon have made it about as far south as they are going to
tonight. Another thick area of smoke over the Dakotas is posed to
slide east overnight, with air quality expected to decrease again
overnight in southern MN, with reduced air quality expected along and
south of the MN River Valley to start the day on Sunday. Eventually,
24 hours from now, a strong enough push of cleaner northwest winds
will push the low level smoke out of the area by Sunday night.
&&
.DISCUSSION...(This evening through Saturday)
Issued at 304 PM CDT Sat Jul 15 2023
KEY MESSAGES:
- Air quality issues continue this weekend, gradually improving this
evening through Sunday.
- Isolated shower/storm chances over E MN/W WI today. Looking ahead,
the next chance for precipitation is Wednesday.
- Near to below normal temperatures through Tuesday then warmer than
normal through the remainder of the week.
Current surface analysis shows a cold front over northwest Ontario
near James Bay extending southwest across the northern Wisconsin and
central Minnesota. A Cu field has developed along and behind the
frontal boundary with some agitated cu present on visible imagery.
A chance for showers and storms will continue through the evening
hours across E MN and W WI as the boundary continues to sag
southward. Forecast soundings ~1000 to 1500 J/Kg MLCAPE is present
ahead of the front with 25-35kts of effective shear present. Severe
potential is low, but the environment should be capable of producing
a few isolated instances of gusty winds and small hail over W WI.
The more pressing forecast concern has been the anticipated return
of Canadian wildfire smoke. Air quality been unhealthy per the Air
Quality Index. Values are in the 140-160 range across the southern
half of MN and west central WI. The Air Quality Alert has been
extended for all counties in our MN CWA except Douglas (most of
central and southern MN) until 3PM Sunday. MPCA has upgraded the
category to Red and include the unhealthy for all wording to reflect
the current conditions. WI-wide AQA remains in effect until mid-day
Sunday, too. Surface smoke should begin to dissipate behind the
front, but it`ll be gradual improvement through the next 12 to 24
hours. If you`re hoping to see blue skies over the next few days,
you`ll be out of luck. A layer of elevated smoke should linger into
early next week before dissipating. The smoke appears to have had a
marginal impact with temperatures still warming into the lower 80s
ahead of the FROPA.
A similar story will unfold for Sunday as a post-frontal trough
settles in behind the cold front. Isolated to scattered shower/storm
chances return for W WI Sunday afternoon, but the severe chances
remain low. Temperatures cool off with highs in the 70s on Sunday
and Monday. Temperatures return to normal on Tuesday in the low 80s
The mid level ridge over the western CONUS will begin to break down
a bit and shift eastward, allowing for higher heights to build in
mid-week. This will allow temperatures to build back into the mid to
upper 80s for the second half of the week onward. Another shortwave
moves through on Wednesday and will be our next chance for
precipitation. NBM PoPs range between 30 to 50 on Wednesday that
seems agreeable. No widespread drought relief appears in in the next
week as northwesterly flow sticks around throughout the period.
&&
.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1038 PM CDT Sat Jul 15 2023
Did boost cloud cover Sunday based on what we`re seeing from
forecast soundings and the LAV for moisture coming in around 7k-10k
feet. This is the cloud cover that`s over NoDak now that will drop
ESE through the night, reaching central MN by the morning. Some of
the CAMs are spitting out some reflectivity returns with this cloud
cover as well, but expect this to be mainly virga. During the
afternoon, a diurnal cu field will get going, with an isolated TS
possible east of a MKT to RNH line, though again, coverage does not
look to be enough to warrant any sort of precip mention at EAU in the
TAF. Biggest uncertainty this period comes with the smoke. We were
able to clear it out some Saturday, but with winds overnight swinging
back to the WSW, we will be bringing some of the thicker smoke over
SoDak back over southern MN and western WI on Sunday. How bad vsbys
will be and how far north vis restrictions will be observed is quite
uncertain at the moment, but greatest probability of smoke issues
Sunday will be at MKT/RNH, with STC/AXN most likely to avoid it.
KMSP...There are some small precip chances that aren`t high enough to
include in the TAF, first comes between 14z and 18z in the form of
-shra as the wave and associated cloud cover in NoDak swing through.
Afternoon TS activity looks unlikely as far west as MSP. 00z HRRR
smoke output did hint that we could see some low level smoke return
in the morning as well, but there`s not enough confidence in smoke
getting back up here to put it in the TAF.
/OUTLOOK FOR KMSP/
MON...VFR. Wind NW 10-15 kts.
TUE...VFR. Wind SE 5-10 kts.
WED...Mainly VFR. Chc MVFR & aftn TSRA. Wind SE 5-10 kts bcmg W.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...None.
WI...None.
&&
$$
UPDATE...MPG
DISCUSSION...BPH
AVIATION...MPG
Area Forecast Discussion
National Weather Service New York NY
817 PM EDT Sat Jul 15 2023
.SYNOPSIS...
A frontal system approaching from the west tonight will become
nearly stationary across the area on Sunday before moving east
Sunday night. High pressure will then briefly build across the
area on Monday. Unsettled weather is likely to continue through
the rest of the week with the potential for a series of frontal
boundaries.
&&
.NEAR TERM /THROUGH SUNDAY/...
Flood Watch remains up for the entire forecast area late
tonight through Sunday evening.
Leftover stratiform rain showers early this evening from
stronger convection will be across parts of the area from NYC
north/west this evening. Then potential exists for a significant
flood event (possibly major) late tonight through the day
Sunday as a frontal system works into the area ahead of another
shortwave being sent east out of the longwave trough. All the
players are there with record PWAT values of 2.25-2.50 inches,
moderate-high instability, and a slow-moving or at times stalled
out boundary across the area. There remains uncertainty as to
where exactly the boundary puts on its brakes, with the CAMs
varying in the placement of the heaviest rainfall. Some differ
with the highest QPF just NW of the city, to others just east.
Placement of this boundary will be crucial to where the axis of
heaviest rainfall sets up. In addition, the 12Z NAMNest and SPC
HREF mean highest QPF is just NW of the NYC metro from interior
NE NJ into the Lower Hudson Valley and SW CT. The 18Z HRRR is
more progressive and farther east with the rainfall. Thus, there
is no consensus and the model error is such that small changes
are likely even as we get within a few hours of the event.
Rainfall amounts on average across the area are forecast to be
between 1 and 3 inches with localized amounts of 3 to 5 inches
possible. However, putting a cap on rainfall amounts,
especially in such a environment, may not be prudent. SPC HREF
Max QPF was 3 to 5 inches across the area, so this seems like a
reasonable start.
One late minute note, the 18Z NAMNest is showing some more
eastward progression like that seen in some of the other CAMs.
This would keep the rainfall more dispersed across the area,
which would be a better outcome. This trend will have to be
watched through the night and up until the event.
Warm, humid conditions continue through the period. Overnight
lows will be in the 70s, accompanied by dew points of similar
values. Clouds and rainfall on Sunday should result in a cooler
day, with highs around 80.
&&
.SHORT TERM /SUNDAY NIGHT/...
Lingering convection in the evening is forecast to work east of
the area during the early morning hours. The cold front is
expected to clear eastern LI/SE CT toward daybreak. Lows are
forecast to be a few cooler, ranging from the upper 60s inland,
to the lower 70s along the coast.
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
A persistent longwave upper trough will remain in place over eastern
North American through the time frame, with a series of shortwave
impulses riding through every other day or so this week with chances
for showers/tstms. On Mon we will be in between impulses and the day
should be very warm and somewhat humid, with highs mostly from the
upper 80s to lower 90s, and afternoon dewpoints from the mid 60s NYC
north/west to the lower 70s across Long Island and SE CT. The next
chance for organized convection arrives as the longwave trough axis
swings through, with a marginal risk of excessive rainfall fcst for
the Hudson Valley. Slightly cooler high temps (85-90) and slightly
higher dewpoints (upper 60s/lower 70s) on Tue should yield similar
heat index values to those of Monday.
Max heat index values for the two days should be mostly below 95,
with the possible exception of the urban corridor of NE NJ and some
spots along the north shore of Long Island, with only E Union County
meeting local heat advy criteria of two consecutive days of 95+ heat
index.
Some haze may also be possible Mon night into Tue, per extrapolation
of latest HRRR guidance suggesting some smoke from western Canada
wildfires crossing the Appalachians during that time.
Wed looks like a mostly dry day with shortwave ridging briefly
moving across, then the next organized chance of showers/tstms
should arrive Thu-Fri as the longwave upper trough becomes re-
established. Forecast per NBM currently shows dry conditions for Sat
but confidence in this is low especially east of NYC with
deterministic global models showing a wave of low pressure moving
NNE through the adjacent Atlantic waters.
&&
.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
A frontal boundary will remain in the vicinity of the terminals
through tomorrow.
VFR to scattered MVFR/IFR through the late evening with MVFR
cigs already showing across the coastal terminals. Batch of
showers with some embedded IC lightning making its way through
EWR/TEB/LGA/HPN and weakening. Another line of showers and
embedded thunderstorms back to the southwest over southern PA
looks to stay west of the terminals over the next few hours.
More widespread showers and thunderstorms by late tonight, with
heavy rain at times, with MVFR to IFR, and possibly LIFR.
Development may be an hour or two earlier than forecast. Showers
and thunderstorms continue through Sunday afternoon, with
embedded thunder possible through the late afternoon at all
terminals.
A southerly flow is expected through the forecast period. At or
below 10 kt this evening increasing to 10-15kts on Sunday.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Timing of MVFR to possibly IFR stratus moving into KJFK and
KLGA this evening is uncertain. High confidence in low end MVFR
cigs overnight through early tomorrow, lower confidence in IFR.
Uncertainty in end time of SHRA and TSRA on Sunday. There is a
chance for TSRA to linger through the end of the TAF period.
OUTLOOK FOR 18Z SUNDAY THROUGH THURSDAY...
Sunday Afternoon: MVFR to IFR in numerous showers with a chance
of thunder early afternoon.
Monday: Early morning MVFR possible in cigs/vsby, especially
east of the NYC terminals, becoming VFR.
Tuesday: MVFR or lower in chance of showers and thunderstorms.
Wednesday: VFR.
Wednesday Night - Thursday: MVFR or lower in chance of showers
and thunderstorms.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90
&&
.MARINE...
Ahead of an approaching frontal system, southerly winds will
strengthen to around 15 kt on the ocean waters by morning,
increasing seas around 5 ft. A SCA has been issued for Sunday
and Sunday night between Fire Island Inlet and Montauk Point.
Sea up to 5 ft may linger on the ocean waters daytime Mon per NWPS
and GFSwave, especially out east. Confidence in this is low as
sustained winds in the persistent S flow daytime Sunday peak only
briefly between 15-20 kt, and will be lighter out of the SW daytime
Mon, so SCA has not been extended into this time frame.
&&
.HYDROLOGY...
A Flood Watch is in effect for the entire CWA late tonight and
Sunday.
There is the potential for a significant to major flood event on
Sunday as a frontal boundary works across the area. All of the
area except eastern LI is under a Moderate Risk for Excessive
Rainfall. The potential is there for scattered to numerous flash
floods. On average, widespread rainfall of 1 to 3 inches, with
localized amounts of 3 to 5 inches will be possible.
A marginal risk of excessive rainfall is forecast for the Hudson
Valley for Tuesday, as another passing disturbance helps generate
showers/tstms with heavy rainfall. An ongoing risk may continue with
successive systems later this week.
&&
.TIDES/COASTAL FLOODING...
There is a high risk of rip current development at all the ocean
beaches Sunday into Monday as southerly swells increase.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...Flood Watch from midnight EDT tonight through Sunday evening
for CTZ005>012.
NY...Flood Watch from midnight EDT tonight through Sunday evening
for NYZ067>075-078>081-176>179.
Air Quality Alert until 11 PM EDT this evening for NYZ069>075-
176-178.
High Rip Current Risk through Sunday evening for NYZ075-080-
081-178-179.
NJ...Flood Watch from midnight EDT tonight through Sunday evening
for NJZ002-004-006-103>108.
MARINE...Small Craft Advisory from 8 AM Sunday to 6 AM EDT Monday for
ANZ350-353.
&&
$$
SYNOPSIS...BG/DW
NEAR TERM...BG/DW
SHORT TERM...DW
LONG TERM...BG
AVIATION...DBR
MARINE...BG/DW
HYDROLOGY...BG/DW
TIDES/COASTAL FLOODING...BG
Area Forecast Discussion...UPDATED
National Weather Service Paducah KY
556 PM CDT Sat Jul 15 2023
.SHORT TERM...(Tonight through Monday night)
Issued at 237 PM CDT Sat Jul 15 2023
Radar showing a small complex of non-severe thunderstorms moving
southward through the Land Between the Lakes area. After this,
expecting dry conditions the rest of the day and into tomorrow
behind the front that is currently moving through the area. Also
behind this front we`re seeing lower dewpoints which should provide
a little relief from the humidity for now. Overnight tonight expect
lows in the 60s to around 70.
Aloft we`re in northwest flow with a broad trof axis to our east and
a high pressure heat dome over the southwest CONUS. The RAP smoke
model continues to show smoke and haze from the Canadian
wildfires pushing southward tomorrow and will bring at least haze
to mainly northern portions of the area. In this northwest flow we
can expect daily chances for showers and thunderstorms, but with
a couple disturbances moving through a few days look better than
others.
Sunday night will see some precip chances mainly for the northern
half of the area. More widespread and stronger chances come Monday
afternoon across the area. Monday will sport highs in the 80s and
90s with dew points in the upper 60s and lower 70s.
.LONG TERM...(Tuesday through Saturday)
Issued at 237 PM CDT Sat Jul 15 2023
Overall Monday afternoon through Tuesday are the best days for
precip chances. Tuesday will be similar to Monday but with more
morning PoPs and then afternoon PoPs that last through Wednesday
morning (mainly north and east).
By Wednesday the high pressure dome from the southwest edges this
way and pushes temps up. Highs Wednesday will be in the 90s to
around 100 with heat indices ranging from 105-110. Thursday will be
only a touch cooler with highs in the upper 80s and 90s with heat
indices ranging from 100-105. Both days (especially Wednesday) could
possibly need Heat Advisories. This will be something to keep an eye
on.
A broad trof deepens over the region Friday and Saturday pushing the
high back west. A cold front moves through by Friday afternoon and
brings temperatures down slightly with highs in the upper 80s to
around 90 on Friday and in the 80s on Saturday.
&&
.AVIATION...
Issued at 556 PM CDT Sat Jul 15 2023
Light showers over western KY should diminish this evening. Will
be watching for some fog potential through the late overnight.
Canadian wildfire smoke is riding in on light northwesterly winds
and will likely be a factor late tonight and through the day on
Sunday. Visibility to the northwest is MVFR or better but will
need to watch for more concentrated areas as the day progresses.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...None.
MO...None.
IN...None.
KY...None.
&&
$$
SHORT TERM...SHAWKEY
LONG TERM...SHAWKEY
AVIATION...JGG
Area Forecast Discussion
National Weather Service Phoenix AZ
400 PM MST Sat Jul 15 2023
.UPDATE...
Updated Aviation.
&&
.SYNOPSIS...
A strong subtropical ridge will continue to dominate the forecast
through at least early next week, allowing near record to record
temperatures to prevail. An Excessive Heat Warning remains in effect
through Wednesday, as widespread Major HeatRisk increases to Extreme
HeatRisk this weekend. Isolated shower and thunderstorm chances the
next couple days will be confined to higher terrain areas of eastern
and southeastern Arizona with increasing chances expected to extend
into the south-central Arizona lower deserts by early next week.
&&
.DISCUSSION...
The main focus of this forecast will continue to be well advertised
extreme heat heading into this weekend and lasting through much of
next week. We can`t stress enough how dangerous this heatwave is as
temperatures soar to near record levels each day. This extreme heat
is very unusual even for July standards as highs soar 10 degrees
above normal and overnight lows remain very warm in the mid 80s to
low 90s. The HeatRisk will increase to extreme today across the
lower deserts and persist into early next week, resulting in the
potential of seeing increased heat-related health impacts.
Therefore, it is critical to keep heat safety in mind and limit time
spent outdoors as much as possible.
Latest RAP 500 hpa height analysis indicates an impressive 599 dam
high located over the Great Basin region. Mid lvl temperatures are
equally as impressive w/700 hpa temps approaching 18-20C and 850 hpa
temps upwards of 35-36C across much of AZ. The magnitude of this
subtropical ridge is on par with some of the strongest we have
sampled over the past decade as it is very rare to see 500 hpa hghts
approaching 600 dam. Phoenix Sky Harbor reached 110 degrees at 11:14
AM MST today, now bringing the consecutive 110+ day count to 16
days. It is now looking like we will easily break the record streak
of 18 days. The high is forecast to be a record breaking 118F this
afternoon in Phoenix and numerous other locations across the area
should see readings reaching 115F or greater. Another quiet night is
anticipated with very little relief in store as lows settle into the
mid 80s and lower 90s across the lower deserts. Tomorrow will be a
similar story with highs yet again peaking at record levels.
Early next week, hghts aloft will decrease slightly to around 596-
598 dam and the subtropical ridge axis will be migrate closer to the
AZ/NM state line. This pattern shift will help direct mid lvl flow
to more of a southeasterly direction and promote the advection of
low lvl moisture from the Gulf of MX. Thus, we could finally see the
beginning signs of a more favorable monsoonal setup across our area.
NBM PoPs for Monday afternoon/evening are still in the 20-30% range
for the Phoenix metro and around 40% for S Pinal and S Gila
Counties. The major question mark remains if subsidence aloft will
be too strong to overcome during peak heating and thus NBM PoPs may
be a tad overdone attm. Despite the increasing rain chances,
temperatures will still reach dangerous levels on Monday with highs
again soaring above 115F in many locations.
As we head into the middle of next week, the ensemble mean 500 hpa
hght pattern shows the subtropical high centered over NM and far W
TX which will continue to promote S-SE flow over southcentral AZ.
PWATs will fluctuate between 1.3-1.5" from Tuesday onwards, keeping
daily chances for showers and thunderstorms in play. NBM PoPs
continue to range from 20%-40% across the eastern half of the
forecast area through the remainder of next week. Temperatures will
slowly decline through the latter half of the week, but still near
record levels each day unfortunately. However, as the traditional
monsoonal pattern develops, moisture and residual cloud cover each
morning could help reduce high temps by a few degrees overall.
&&
.AVIATION...Updated at 2300Z.
South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
No major weather impacts will exist through Sunday afternoon under
only a few passing mid/high clouds. Some gusty west winds late this
afternoon may be reinvigorated mid/late evening helping hold off the
typical easterly conversion until the overnight. West winds should
return quickly by late morning across the majority of the metro with
somewhat less gustiness than the past several days.
Southeast California/Southwest Arizona including KIPL and KBLH:
No weather issues will continue through Sunday afternoon under only
a few passing high clouds. Winds will remain consistent in
oscillating in a diurnal tendency between a SE and SW direction.
Somewhat occasional brief gustiness would not be uncommon.
&&
.FIRE WEATHER...
Well above average temperatures are expected this weekend and much
of next week with highs reaching 112-120 degrees across the lower
deserts. Overnight relief will be limited with lows only falling to
the mid-80s to mid-90s. Minimum humidity will be around 10-15% this
weekend with overnight recoveries ranging from poor to fair. Low
level moisture will increase early next week as well as the
potential for thunderstorms across the higher terrain of AZ. Gusty
erratic winds and dry lightning will be the main concern with any
thunderstorm that may develop. Winds will tend to follow typical
diurnal and terrain influences, with occasional afternoon gusts up
to 20-25 mph.
&&
.CLIMATE...
...RECORD HIGH TEMPERATURES...
...PHOENIX... ...YUMA... ...EL CENTRO...
July 15 117 (1998) 116 (1998) 116 (2019)
July 16 118 (1925) 116 (1960) 119 (1936)
July 17 116 (2005) 117 (2005) 121 (2005)
July 18 115 (1989) 117 (1960) 117 (2009)
July 19 116 (1989) 115 (2000) 117 (1978)
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Excessive Heat Warning until 8 PM MST Wednesday for AZZ530>544-
546-548>551-553>555-559.
Excessive Heat Warning until 8 PM MST Monday for AZZ545-547-552-
560-561.
Excessive Heat Warning until 8 PM MST Sunday for AZZ556>558-562-
563.
CA...Excessive Heat Warning until 8 PM PDT Wednesday for CAZ560>570.
&&
$$
DISCUSSION...Salerno
AVIATION...18
FIRE WEATHER...Salerno
CLIMATE...Kuhlman
...Update to aviation forecast discussion...
.DISCUSSION...
Issued at 256 PM CDT Sat Jul 15 2023
Key Points:
- Strong to severe storms possible Sunday
- Heating up early next week, especially Tuesday
A much quieter day is taking shape across the area with sfc high
pressure over most of the western US. Upper ridging remains over the
most of the western CONUS as well, with one low off the coast of
British Columbia and the other still circulating in central Canada
southwest of the Hudson Bay. Northwest upper flow has brought in
some smoke aloft as noted on visible satellite, but impacts to the
surface are not anticipated this far south. Subtle perturbations
within the flow have triggered a few isolated showers in western KS,
one of which has made into our western counties early this
afternoon, but otherwise mainly sunny skies and light winds prevail.
Sfc high pressure slowly slides east tonight, keeping light winds as
temperatures fall back to the 60s area-wide.
Main focus this forecast package is on the potential for severe
weather Sunday. By early morning, a weak embedded shortwave along
with an associated sfc boundary looks to trigger convection in
central NE, perhaps as far south as north central KS if recent HRRR
models are correct. The HRRR/RAP continue to be a bit faster with
bringing convection south in the morning compared to other CAMs, but
in any case, PoPs increase throughout the day as the boundary drops
south. These differences in timing lead to questions on how much the
boundary layer will destabilize into the afternoon, as an earlier
arrival of storms would allow for less opportunity to become
unstable. The best instability and shear are across the northern
half of the CWA near the KS/NE border, where the weak front appears
to be set up. However, it should also be noted that any morning
convection could produce an outflow boundary that may set up a
little further south. The 15Z RAP also has shown an increase in
instability compared to its previous runs, but the HREF is not as
robust, with its ensemble mean suggesting we may only see around
1000 J/kg of CAPE. All this to say, there are plenty of remaining
questions on how widespread storms become and how intense they could
get, but if an outflow boundary does set up with greater instability
present, that would lead to a growing concern for severe storms with
damaging wind as the main threat with hail and locally heavy rain
also possible. Forecast soundings along and south of I-70 show an
inverted-V profile, and moisture transport throughout the day looks
to bring Pwat values above 1.5 inches.
Late Monday night into early Tuesday brings another chance for
thunderstorms particularly in far northeast KS, as low pressure
moves out of the Rockies and across the state. A thermal ridge then
looks to move in its wake, bringing heat indices around 105 for
Tuesday and only a slight improvement for Wednesday, albeit still
quite hot. There may be a few other chances for precipitation later
in the week, but subtle forcing leads to differences in models and
lower confidence this far out.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 618 PM CDT Sat Jul 15 2023
VFR at all TAF sites through the TAF period. Thunderstorms are
possible tomorrow morning and afternoon, but confidence in timing
and location is too low at this point to place in the TAF. Winds
will shift out of the north behind a passing cold front during the
afternoon.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
DISCUSSION...Picha
AVIATION...Jones
Area Forecast Discussion
National Weather Service Tulsa OK
656 PM CDT Sat Jul 15 2023
...New UPDATE...
.UPDATE...
Issued at 656 PM CDT Sat Jul 15 2023
Update this evening to forecast will remove PoPs/thunder mention
thru 06Z. The last several runs of the HRRR suggest outflow from
storms on the High Plains will eventually lead to more storms or
a cluster of storms near the Red River late tonight into Sunday
morning. The NBM hourly PoP trend looked good, ramping up to
slight chance over portions of far SE OK up thru 12Z.
Lacy
&&
.SHORT TERM...
(Through tonight )
Issued at 220 PM CDT Sat Jul 15 2023
Weak MCV approaching SE OK will interact with the near stationary
frontal boundary to support isolated to scattered late afternoon
and evening storms primarily across far SE OK. Additional storms
are expected to develop across the southern High Plains this
evening and steadily spread SE overnight with the northern axis of
this convection possibly spreading across far SE OK late tonight
into early Sunday. An isolated severe storm will be possible both
this evening and again late tonight.
&&
.LONG TERM...
(Tomorrow through Saturday)
Issued at 220 PM CDT Sat Jul 15 2023
Early day storms Sunday across SE OK will focus more southward
with time. Extensive cloud cover and minor cooling / drying north
of the frontal boundary should provide more tolerable mid July
conditions. Storms will develop across the central Plains Sunday
evening and spread ESE associated with the next weak cold front.
Majority of guidance currently suggests this convection will be in
a weakening state Sunday night into Monday morning as it moves
into NE OK. The frontal boundary will largely stall and lose
definition across the region on Monday however it may by
sufficient to aid isolated storms across far E OK / NW AR Monday
afternoon. Depending on dewpoint trends a portion of the forecast
area could require a heat advisory for Monday afternoon.
Thereafter upper ridge is expected to strengthen over the southern
Plains with temp / dewpoint forecasts supportive of more widespread
heat headlines. The mid week heat remains in place until the upper
ridge shifts more westward and a weak front and associated storm
chances return by late next week.
&&
.AVIATION...
(00Z TAFS)
Issued at 551 PM CDT Sat Jul 15 2023
Mostly quiet weather is expected across the area tonight with just
a few clouds in the 3-6 kft layer and a few high clouds. Winds out
of the northeast this afternoon will become light and variable for
the overnight hours. South to southwest winds of 5-10 kts will
develop for the daytime hours Sunday with just a few higher gusts.
High clouds will persist through this period.
&&
.PRELIMINARY POINT TEMPS/POPS...
TUL 71 95 72 96 / 0 0 10 10
FSM 73 95 74 97 / 0 10 10 10
MLC 71 90 72 96 / 10 20 10 10
BVO 66 94 68 95 / 0 0 20 10
FYV 66 93 69 94 / 0 0 10 10
BYV 66 95 69 94 / 0 0 20 20
MKO 70 93 72 94 / 0 10 10 10
MIO 68 95 69 94 / 0 0 20 10
F10 68 91 70 95 / 10 10 10 10
HHW 73 87 72 95 / 20 50 10 10
&&
.TSA WATCHES/WARNINGS/ADVISORIES...
OK...None.
AR...None.
&&
$$
SHORT TERM...07
LONG TERM....07
AVIATION...06
Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
505 PM MDT Sat Jul 15 2023
.DISCUSSION...(This Evening Through Saturday)
Issued at 143 PM MDT Sat Jul 15 2023
Main fcst challenge revolves around how much effect the smoke
will have on temps for the remainder of the weekend, and
convective chances late Monday through Monday night.
Currently at the sfc a weak boundary is draped across the nrn part
of SoDak, with high pressure entrenched across the Rockies. 500hpa
low conts to spin across nrn sections of Manitoba with resultant
NW flow continuing to draw Canadian wildfire smoke into the nrn
plains. HRRR and Hi-res NAM cont to show smoke will cont to ooze
into our cwa through the weekend before making a slow retreat back
to the north Monday with return flow as upper ridge sitting to
the west begins to collapse just a bit and shift a bit further to
the east. While the chances of some minor SHRA or TS developing
over the Black Hills through the weekend are not zero, with
limited moisture/shear/instability to play with, will continue
with the non-mention in the forecast. Suspect that the smoke will
also temper highs a little.
Monday will see return flow back to the region with the approach
of 500hpa ridge axis. Sfc flow turns more westerly by days end.
This could be a big convective day with approaching impulse in
flattening flow, 0-6km bulk shear 70+ kts and MUCAPE in the
1500-2000 j/kg range by 00z Tue. Could is the key word however.
700hpa temps increase to +12C across the ern CWA to nearly +18C
across the WY counties by 00z Tuesday. How much of the cap holds
during the afternoon and does stuff fire on the periphery of the
thermal dome is the question. Some of the models are suggesting
that initiation occurs further west in WY along the
Bighorns...then advects into the CWA in the 03z-06z Tue time
frame. Again...with the strong thermal dome pushing activity into
the NW CWA...then SE along the west side of the Missouri River.
Smoke wise, the smoke that had advected south this weekend into
Nebraska will return back to the north with the upper return flow,
so don’t really see an improvement until Tuesday when upper flow
is more westerly.
The remainder of the week looks to have off and on chances of
storms as upper flow returns to a more cyclonic flow with building
inter-mountain ridge. This should result in a return of more
favorable lolvl moisture and shear values. Temps should also be
more July’ish...with 70s in the higher terrain and 90s on the
plains by weeks end.
&&
.AVIATION...(For the 00Z TAFS Through 00Z Sunday Evening)
Issued At 504 PM MDT Sat Jul 15 2023
Smoke/haze will persist into Sunday with MVFR/local IFR
visibility.
&&
.UNR WATCHES/WARNINGS/ADVISORIES...
SD...None.
WY...None.
&&
$$
DISCUSSION...Hintz
AVIATION...7