Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 07/27/23
See below for an aviation forecast discussion for the 00Z TAFs.
&&
.SHORT TERM...(This Evening through Thursday Night)
Issued at 326 PM CDT Wed Jul 26 2023
The main forecast challenge in the near term revolves around the
potential for thunderstorms this evening, a few of which may be
severe. An upper level ridge and associated warm air aloft has made
for another very warm day across the region. This ridge will break
down tonight as shortwave energy moves through and flattens out the
flow. This more zonal flow pattern will then remain in place
Thursday and Thursday night, with more shortwave energy moving
through Thursday night.
At the surface, a frontal boundary will slide across the region this
evening and may become the focus for shower and thunderstorm
activity. The biggest factor that may hinder development is the
presence of a capping inversion aloft. H7 temps will generally be in
the +12C to +15C range. The better shear and instability look to
occur across the eastern CWA during the 00Z to 03Z time frame, so
that area and time period may be the best chance for a stronger
storm or two to develop. The front will drift southward and set up
over the southern part of South Dakota on Thursday. This will keep
the warmest temperatures along that region, though temps to the
north will be just slightly cooler. A weak boundary will track over
the northwestern part of the CWA and the cap will weaken in that
area, so there may be some shower and thunderstorm development
Thursday night. None of the CAMs are too excited about this
potential, but will keep some small POPs in just in case.
Low temperatures tonight will be mainly in the 60s. High
temperatures on Thursday will range from the lower to mid 90s
across northern South Dakota and west central Minnesota, to the
upper 90s to around 100 across the across south central South
Dakota. Lows Thursday night will again be in the 60s.
.LONG TERM...(Friday through Wednesday)
Issued at 326 PM CDT Wed Jul 26 2023
This period looks to feature cooler and more comfortable conditions
setting up for the end of the week through the upcoming weekend as
the highest heat and humidity gets shunted south of our area. Most
of the deterministic and ensemble guidance is in fair agreement on
showing a broad upper ridge splayed out across the southern half of
the CONUS. Zonal flow will be the setup across our region of the
Northern Plains initially through the first portion of the period.
Sfc low pressure is progged to be positioned to our south with a
trailing backdoor cold front draped west to east across the central
and southern portions of SD by Friday morning. We could see some
post-frontal showers and storms Friday as s/w trough energy will be
working through the region. Best severe parameters(highest
instability and best deep layer shear) will be setup across southern
SD and perhaps as far north into our southern zones on Friday. The
current Day 3 severe weather outlook from SPC has a "marginal" risk
across a fair portion of our CWA(minus some northern zones) which
seems reasonable given the setup.
Going through the upcoming weekend, sfc high pressure poised to our
north across Canada will inch south and southeastward into parts of
the Northern Plains and Upper Midwest. This should suppress the hot
temperatures and high humidity values across our forecast area.
Conditions look more seasonal through the weekend with highs in the
80s to a few low 90s and overnight lows in the 50s to low 60s. The
upper ridge is progged to amplify across the Northern High Plains
and Northern Rockies over the course of the weekend into early next
week. This will lead to northwesterly flow aloft across our region.
Ridge riding s/w trough energy will continue to slide east and
southeast over the crest and on the downstream side across our
region giving us periodic chances for showers and thunderstorms
through the latter half of the period. Difficult this far out to
time the passage and track of these waves so a broadbrush of
scattered PoPs continue through the extended portion of the
forecast.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday Evening)
Issued at 708 PM CDT Wed Jul 26 2023
Terminals KABR,KATY,KPIR,KMBG
For the most part, VFR conditions will prevail across the area
through the TAF period. The exception will be through late this
evening into the overnight hours when showers and thunderstorms
will track from west to the east across the area. Periods of sub-VFR
vsbys in rain will be possible with the thunderstorms. A few of
the storms may become strong to severe, with hail and strong wind
gusts being the main threats. At the start of the TAF valid
period, a supercell was impacting the KPIR terminal with heavy
rain, some hail/wind potentially. Showers and storms were
developing/moving all around the KMBG terminal as well. That
convective potential should wane by 01Z. But, later this evening
between 03Z and 07Z, additional showers and thunderstorms may
develop/move across KABR/KATY terminal airspace as a low level jet
will refocus convective potential across northeast South Dakota.
There could be additional isolated/widely scattered showers/weak
thunderstorms rolling through the region between 09Z and 15Z.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
&&
$$
UPDATE...Dorn
SHORT TERM...Parkin
LONG TERM...Vipond
AVIATION...Dorn
Area Forecast Discussion
National Weather Service Binghamton NY
944 PM EDT Wed Jul 26 2023
.SYNOPSIS...
Very warm and humid conditions Thursday will be accompanied by
scattered showers and thunderstorms, some strong to severe. Hot
and humid weather continues for Friday, but a cold front will
bring some relief for the upcoming weekend.
&&
.NEAR TERM /THROUGH THURSDAY NIGHT/...
935 PM Update:
Showers and thunderstorms off to the west continue to approach
the far western counties a little quicker than most guidance
shows, so PoPs were again adjusted and taken up a bit for the
far western CWA late this evening. Even though this area of
showers and thunderstorms is expected to weaken overnight,
isolated showers may try to hold together overnight and very
early Thursday morning and reach NE PA, so slight chance PoPs
were introduced in that area. During the late morning hours
Thursday, it does look like the clouds should break for some sun
and the chance for any convection wanes for a few hours across
the northern counties, so those areas were brightened up a
little and PoPs lowered before a better chance of showers or
t-storms returns in the afternoon. Latest obs were again blended
in over the next several hours for some minor temperature
adjustments.
635 PM Update:
A MCV that is racing across Lake Erie, NE Ohio and into far NW
PA early this evening is moving along faster than most of the
CAMS are showing. The HRRR and the time lag HRRR models seem to
be handling this feature the best so PoPs were adjusted a bit
heading into the overnight through early tomorrow morning using
a blend of the official forecast and these two, which raised
PoPs close to and just after midnight in our far western
counties in particular. Also blended in the latest obs for some
minor temperature adjustments over the next several hours.
335 Update:
For the most part, the forecast in the immediate near term
remains on track. An isolated shower did pop-up along the
Pike/Sullivan county border, but the rest of the area remains
dry.
A shortwave will approach the region late tonight into Thursday
morning. This will once again bring another chance of showers
and thunderstorms, possibly in the form of an MCS, through
early Thursday morning. The track and timing of this potential
MCS on Thursday will likely play a huge role on what happens
later that day with thunderstorm development. It is possible
that cloud debris from this cluster of showers and thunderstorms
may limit instability for Thursday afternoon. If that happens,
coverage of afternoon thunderstorms will be rather isolated,
likely resulting in minimal impacts. However, if enough clearing
can occur, instability and shear will be plentiful for showers
and thunderstorms to develop, some which may contain damaging
winds and heavy rainfall. SPC continues to have areas east of
I-81 highlighted in a Slight Risk for severe thunderstorms, with
a marginal risk elsewhere. Otherwise, it will be very warm and
humid with highs mainly in the 80s.
Showers and thunderstorms quickly diminish in coverage Thursday
night with instability waning and high pressure moving in. Lows
are expected to be in the 60s to near 70.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
350 PM Update...
A short-lived bubble of higher pressure on Friday will allow
temperatures to increase to the highest of the week. Deep
southwesterly flow will bring temperatures into the low- to
mid-90s for the majority of the region. Dewpoints in the
high-60s/low-70s will create humid conditions for the day. As
mentioned previously, these hot and humid conditions will be
constrained to Friday as an approaching cold front from the
north pushes into the area overnight Friday, expecting to bring
showers and storms into the area Saturday early morning.
With a lot of available moisture and some instability overnight
Friday, more short-lived pulse thunderstorms are likely. Though,
with a deep warm cloud layer, PWATs between 1.5 and 1.8 inches,
and long, skinny CAPE, some of these storms may produce heavy
rainfall where they develop, producing a potential chance for
localized flash flooding. The best chance for storms will start
Friday after sunset and last through Saturday morning. From
Saturday morning through the evening, the main front will push
through the region, bringing more widespread rain showers and
chances for storms. This front will drop temperatures into the
high-70s/low-80s for Central NY. For NE PA and the Twin Tiers,
high temperatures will occur earlier in the day Saturday, before
the main front moves through, and will likely reach low- to
upper-80s before the front moves through these areas in the
afternoon timeframe.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
350 PM Update...
After Saturday, a relatively-anchored low pressure far north of
the region in Canada will be the main driver of weather for our
area through next week. Temperatures will be in the mid- to
high-70s most of the week, with some areas in the valleys
possibly reaching in the low-80s. There are no strong signals of
shortwaves or fronts coming through the area the rest of the
week, but afternoon diurnally-driven showers and/or storms are
possible through the week.
&&
.AVIATION /02Z THURSDAY THROUGH MONDAY/...
VFR conditions are still expected through the rest of this
evening along with dry/quiet weather. However, after 04Z
scattered rain showers are expected to push through mainly
central NY through 14Z. There should be a window of roughly 3-5
hours from 15-19Z where conditions are relatively quiet, but
with MFVR or low-end VFR ceilings. Then after 18Z, more
scattered rain showers will develop with isolated/scattered
thunderstorms filling in as well. The most favorable area for TS
should be from ITH south to AVP. Confidence is still on the low
end in any particular terminal seeing TS...so have added a
PROB30 group for MVFR and TS in the afternoon.
South winds will increase tonight around 10 to 20 kt and then
shift to the southwest Thu morning before becoming w/nwly Thu
afternoon and gradually diminishing. Weak low level wind shear
is still also expected to develop late tonight/early Thursday
morning.
Outlook...
Thursday night through Friday...Mostly VFR with some morning
valley fog possible.
Friday night into Saturday...Chance of thunderstorms and
associated occasional restrictions.
Sunday through Monday...Mainly VFR.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...None.
NY...None.
&&
$$
SYNOPSIS...BJG
NEAR TERM...DK
SHORT TERM...KL
LONG TERM...KL
AVIATION...BJG/BJT
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
630 PM CDT Wed Jul 26 2023
...New AVIATION...
.SHORT TERM...
(Tonight through Thursday night)
Issued at 1253 PM CDT Wed Jul 26 2023
The latest RAP 500mb heights depict a nearly 600 dm ridge centered
over northern New Mexico this afternoon. The ridge has flattened
just a bit and moved a smidge further northwest over the last couple
days, hence the "slightly" cooler temperatures and lack of heat
headlines so far this week. With weak ENE flow on the eastern
periphery of the ridge, we may see some seabreeze showers and
isolated thunderstorms work inland over the Coastal Plains and
perhaps as far north and west as Wilson and and Gonzales counties.
Unfortunately, any precip will be limited to sporadic occurrences
and result in less than 1/10th an inch at best. Elevated fire weather
conditions may continue as well as winds remain breezy and RH values
fall to between 20-30%. Overall, expect more of the same on Friday,
with temperatures in the upper 90s to around 100 once again. A few
isolated storms may develop over the Coastal Plains again, but are
unlikely to work far enough westward to impact the more populated I-
35 corridor.
&&
.LONG TERM...
(Friday through Wednesday)
Issued at 1253 PM CDT Wed Jul 26 2023
An inverted trough is still progged to be near the TX coast on
Friday. Unfortunately, other than a possible slight enhancement of
the seabreeze showers and storms in the afternoon, models continue
to keep things dry with this feature. Otherwise, the mid and upper
ridge will remain steady near the Four Corners region through the
end of the work week before beginning to drift slowly east and
becoming more centered over the Southern Plains for early next week.
This will result in a slight warming trend in our temperatures
again, with many areas along and S/E of the I-35 corridor likely
meeting Heat Advisory criteria by Monday afternoon. Some good news
though is this uptick in temperatures could be relatively short
lived as guidance indicates temperatures may drop a couple degrees
again for the middle of next week, likely due to a slight weakening
of the ridge. Overall, the continued presence of subsidence should
keep much of the area dry, though a few isolated showers and storms
associated with the seabreeze cannot be ruled out for most
afternoons across far southeastern portions of the Coastal Plains.
&&
.AVIATION...
(00Z TAFS)
Issued at 623 PM CDT Wed Jul 26 2023
VFR conditions prevail through the TAF period. Few to sct low and
mid-level clouds will be possible, mainly from late overnight into
early Thursday morning. Skies otherwise remain mostly clear. Wind
speeds will generally remain of 12 knots or less from the south-
southeast at the I-35 TAF sites (KAUS, KSAT and KSSF) and from the
east-southeast at KDRT.
&&
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 77 102 76 102 / 0 0 0 0
Austin Bergstrom Intl Airport 77 99 75 99 / 0 0 0 0
New Braunfels Muni Airport 76 100 75 100 / 0 0 0 0
Burnet Muni Airport 76 100 75 100 / 0 0 0 0
Del Rio Intl Airport 79 103 78 102 / 0 0 0 0
Georgetown Muni Airport 77 101 75 100 / 0 0 0 0
Hondo Muni Airport 74 99 73 99 / 0 0 0 0
San Marcos Muni Airport 76 100 74 100 / 0 0 0 0
La Grange - Fayette Regional 76 98 75 98 / 10 10 0 10
San Antonio Intl Airport 77 99 76 100 / 0 0 0 0
Stinson Muni Airport 77 101 76 100 / 0 0 0 0
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Short-Term...MMM
Long-Term...Gale
Aviation...Brady
Area Forecast Discussion
National Weather Service Grand Forks ND
704 PM CDT Wed Jul 26 2023
.UPDATE...
Issued at 657 PM CDT Wed Jul 26 2023
A few storms formed in area south of Bismarck earlier in area
where sfc temps reached just over 100F. Most of the storms
remained elevated and not severe, exception is one left moving one
which got supercell characteristics with strong tilt and some
rotation. SPC meso page does have a little area where left moving
supercells were favored in this zone. Otherwise MLCAPE is
considerbly less as it moves north of Jamestown. So uncertain how
long it will maintain supercell characteristics with hail and 60
mph wind threat. Otherwise other activity along the SD border is
quite weak but should move into SE ND along the border into our
cwa 02z or so. Not anticipating much intensification.
&&
.SHORT TERM...(This afternoon through Thursday)
Issued at 311 PM CDT Wed Jul 26 2023
-Heat index values near 100F are occuring ahead of an approaching
front. These are brief/localized in nature so an advisory is not
being considered at this time.
-Isolated severe thunderstorms are possible this evening, possibly
into the early overnight period. Early in the event supercells may
support large hail around golf ball size or larger, along with
strong winds 60 mph. The tendency though will be for less organized
clusters and more common severe impacts in the 1"/60 mph range.
A surface trough axis (possible dry line) is moving towards our
forecast area this afternoon with a 10F spread in Td values on
either side of this boundary. Convergence is relative weak, so to
break the strong cap in place it will likely take help from the mid
level waves approaching the region. One wave of interest is in
western SD where a shallow CU field is starting to develop upstream.
As this wave moves east towards the SD border additional height PVA
occurs as a stronger wave/jet streak moves into southern Manitoba
(this evening-overnight). The main cold front arrive later tonight
into Thursday morning. Between these features it is possible we have
just enough support to break the CAP before sunset. Any activity
then becomes elevated as the main wave tracks east after sunset and
forcing increases with the main frontal passage. This scenarios is
most favored toward the southern PV area on WV as shown by RAP to
track towards SE ND. HRRR/WRF had been consistent in showing a
cluster forming towards our south and tracking east, but once the
CAP breaks I would rule out additional clusters forming due to
outflow/cold pool interactions.
Very unstable air mass (MLCAPE 3000+ J/KG) is in place along the
moist Td axis in the RRV. Combined with effective values 35kt, we
may initially see supercells, but with weaker low level shear and
higher bases where development occurs this would mainly result in
larger hail (1.75"+) and 60mph+ wind potential (particularly with
higher DCAPE in our south). As thunderstorms cluster up or
eventually become elevated, the threats should transition to 1"
hail/60 mph winds for the remainder of the event.
.LONG TERM...(Friday through Wednesday)
Issued at 311 PM CDT Wed Jul 26 2023
-There should be a trend towards seasonal temperatures Friday
through much of next week.
-Progressive waves keep shower and thunderstorm chances in the
forecast through the middle of next week, however there is higher
variability in coverage/impacts due to the nature of these waves.
There is a lower probability (less than 5%) for severe potential
Monday and Tuesday.
There is strong consensus and clustering regarding the evolution of
the larger scale pattern through the long range periods, with the
southern CONUS ridge "flattening" and quasi-zonal flow developing
across the Northern Plains/Upper Midwest. This pattern keeps higher
heights and stronger southerly flow south and tends to favor
seasonal temperatures (within 5F of averages). This pattern also
supports progressive shortwave passages that are much more variable
in nature between ensemble members/systems. This keeps near daily
potential for showers/storms, but lowers confidence on details. GEFS
based machine learning does show a 5% severe potential Monday and
Tuesday next week, however NBM CWASP which reflects a combination of
ensemble systems does not highly any specific period for severe
potential which makes sense considering the larger spread between
details in these fast moving waves.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 657 PM CDT Wed Jul 26 2023
VFR thru the pd with scattered mid cloud or cirrus. Winds south to
west in MN tonight and mainly west wind in ND into Thursday, but
10 kts or less. High uncertainity in coverage of any storms later
on as they move into the valley so did not include VCTS at any
site.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.
&&
$$
UPDATE...Riddle
SHORT TERM...DJR
LONG TERM...DJR
AVIATION...Riddle
AREA FORECAST DISCUSSION
National Weather Service Hastings NE
600 PM CDT Wed Jul 26 2023
...Aviation Update...
.DISCUSSION...(This evening through Wednesday)
Issued at 408 PM CDT Wed Jul 26 2023
Key Messages:
* The Heat Advisory will remain in effect through Friday
* There is a small chance (20-30%) for isolated to scattered
showers and thunderstorms to move into south central Nebraska
this evening before diminishing.
* Upper level ridging will persist - keeping it hot through out
the forecast.
Temperatures are hot today - they have been hot and they will
continue to be hot. Dewpoint temperatures are rather juicy as
well, especially for areas along the Highway 81 corridor and into
the areas between Aurora to York, NE. The transpiration from crops
keep dewpoints up and also limits temperatures. Thus, where
dewpoint temperatures are the highest (75-80 degrees),
temperatures will struggle into the mid 90s. However, elsewhere
dewpoint temperatures have dropped into the 60s for the most part,
allowing temperatures to reach closer to 100 with those in north
central Kansas exceeding it already at 3pm.
Models have really struggled today with the moisture - dewpoints
and thus in turn are struggling with the high temperatures.
Overall, they are all too low, the closest model I could find for
dewpoint temps compared to observations this afternoon was the RAP
and it was still largely about 10 degrees to low. Highs are close
to what was anticipated, with maybe some locations in central
Nebraska getting a bit warmer, as dewpoints are slightly lower.
I expect the models to continue to struggle with the moisture and
thus highs into the next few days.
As far as storms tonight. The high resolution guidance continues
to indicate that thunderstorms will develop across southwest
Nebraska and the High Plains and move across southwest Nebraska.
This activity is expected this evening (4-10pm). Some early
activity just west of Cozad has developed as of 4pm, and will
likely move east a bit into our area. As this activity continues
to move eastward, we expect the strength of it to wane the further
to the east it moves. Strong winds are possible with relatively
large dCAPE is present. Hail is also possible with a rotating
storm, but effective shear is relatively low (25-30kts) and much
of this activity is diurnally driven. Activity will primarily
remain along and south of I-80 and west of Hwy 281.
Outside of today, the ridge continues to dominate through the
remainder of the forecast and beyond with not much pattern change
happening through the next 10 days or so. That being said,
Saturday looks to be the coolest day (but still warm) as the
boundary resides across the area. Precipitation chances will also
be a daily well really nightly possibility.
&&
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Friday)
Issued at 545 PM CDT Wed Jul 26 2023
A midlevel disturbance is moving out of the Rockies this evening
and is spreading mid and high clouds across the area.Models try to
bring something around EAR around 5z, but current radar trends
show EAR could be brushed with a VCSH. A SFC trough will move
across the TAF sites overnight which will swing the winds from
ESE to SW when it moves through. VFR is expected through the
period.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...Heat Advisory until 9 PM CDT Friday for NEZ039>041-046>049-
060>064-072>077-082>087.
KS...Heat Advisory until 9 PM CDT Friday for KSZ005>007-017>019.
&&
$$
DISCUSSION...Billings Wright
AVIATION...Beda
Area Forecast Discussion
National Weather Service Goodland KS
811 PM MDT Wed Jul 26 2023
.UPDATE...
Issued at 809 PM MDT Wed Jul 26 2023
Have allowed the Heat Advisory to expire for Norton and Graham
counties this evening. Temperatures falling at sunset have
decreased the heat indices below criteria.
Still monitoring the severe wx across the CWA. Winds around 70-75
mph as well as blowing dust on the leading edge of the storms is
reducing visibility to a mile or less at times.
&&
.SHORT TERM...(This evening through Saturday night)
Issued at 230 PM MDT Wed Jul 26 2023
Tonight...there is rather good agreement amongst numerous models for
isolated to scattered thunderstorms to move into far eastern
Colorado by 3 PM MDT, continuing east into western Kansas and
extreme southwest Nebraska around 6 PM MDT (7 PM CDT), continuing
east this evening then dissipating or moving out of the area around
4 AM MDT (5 AM CDT).
Locally developed blowing dust/dust storm parameters are being met
from the GFS with some support from the HRRR and lesser extent the
NAM. This would occur on the leading edge of the gust front from the
organized convection generally west of Kansas Highway 27. However,
the full impact may be negated some as the convection is moving over
areas that received some sufficient rainfall over the past 24 hours.
Low temperatures are forecast to be in the lower 60s to lower 70s.
Thursday-Thursday night...Lots of sunshine expected for much of the
day until another weather system moves in during the mid to late
afternoon hours, supporting another chance for showers and
thunderstorms, primarily across far eastern Colorado. There is a bit
more uncertainty regarding how far east the thunderstorms will go
before dissipating. The HRRR is the most optimistic with at least
chance pops across western Kansas and extreme southwest Nebraska.
High temperatures are forecast to range from the middle 90s to
around 102 degrees. Low temperatures are forecast to be in the lower
60s to lower 70s.
Friday-Friday night...similar scenario to Thursday. Another weather
system moves across the area from the Colorado front range,
supporting slight chance/low chance pops during the evening hours.
High temperatures are forecast to be in the middle 90s to around 103
degrees. Low temperatures are forecast to be in the lower to upper
60s.
Saturday-Saturday night...the forecast area remains under northwest
flow aloft, in between an upper level ridge centered over the Palmer
Divide and low pressure over eastern Canada. It appears there will
be another weather system moving through parts of the area from the
northwest during the evening/midnight hours, supporting a slight
chance for thunderstorms. High temperatures finally cool a bit with
middle 80s to middle 90s forecast. Low temperatures fall into the
lower to upper 60s.
.LONG TERM...(Sunday through Wednesday)
Issued at 230 PM MDT Wed Jul 26 2023
Sunday...upper level ridging strengthens over the area with
limited chances for thunderstorms. High temperatures are forecast
to be in the lower to middle 90s with low temperatures in the
middle 60s to lower 70s.
Monday...the upper ridge axis slides east a bit as some troughing
approaches from the west. This opens the door to some increasing
moisture, enough to support some overnight showers and
thunderstorms. High temperatures rise back into the middle 90s to
around 103 with low temperatures in the middle 60s to middle 70s.
Tuesday...the upper level pattern shifts to one featuring a more
monsoonal pattern with an upper level ridge to our southeast and
troughing to our west. This will favor moisture moving into the area
from the south. Slight chance and chance pops for
showers/thunderstorms advertised in the afternoon and overnight
hours. High temperatures are forecast to remain hot with lower 90s
to around 102 and low temperatures in the lower 60s to middle 70s.
Wednesday...little chance in the upper level pattern so we`ll
continue with afternoon and overnight thunderstorms. High
temperatures are currently forecast to be in the upper 80s to upper
90s with low temperatures in the lower 60s to around 70.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 453 PM MDT Wed Jul 26 2023
For KGLD, mainly VFR conditions expected for the forecast period.
From 01z-04z, down to 6sm -TSRA BLDU possible. Winds, southeast
around 10kts through 04z Thursday, then light/variable. By 09z,
west 5-10kts becoming southeast by 18z. If thunder occurs, then
tempo 01z-04z west 30-45kts.
For KMCK, mainly VFR conditions expected for the forecast period.
From 03z-05z, VCTS possible. Winds, southeast 5-10kts through 03z
Thursday, then southwest. From 06z onward west-southwest around
10kts, with some light/variable after 09z. If thunder occurs,
then tempo 03z-05z west 30-45kts.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...Heat Advisory from 1 PM to 9 PM CDT Thursday for KSZ003-004-015-
016-029.
CO...NONE.
NE...Heat Advisory from 1 PM to 9 PM CDT Thursday for NEZ081.
&&
$$
UPDATE...JN
SHORT TERM...99
LONG TERM...99
AVIATION...JN
Area Forecast Discussion...Updated
National Weather Service Lincoln IL
708 PM CDT Wed Jul 26 2023
.SYNOPSIS...
Issued at 707 PM CDT Wed Jul 26 2023
Hot weather will continue for a few more days, with the heat index
expected to reach the 105 to 110 degree range both Thursday and
Friday. Little relief is expected at night, as the heat index only
falls into the mid to upper 70s. A cold front will bring some
showers and thunderstorms back into the area Friday night, but the
rain will diminish Saturday morning.
&&
.UPDATE...
Issued at 707 PM CDT Wed Jul 26 2023
Main forecast concern through the evening will be monitoring the
potential for a few thunderstorms, but confidence has waned from
earlier. Water vapor imagery reveals a strong shortwave trough over
NW IN with strong subsidence noted in its wake from central WI into
central IL. Cumulus was noted earlier along a slow moving frontal
boundary sagging south into central Illinois which is currently
located roughly Bloomington to Macomb, IL. Cloud cover along this
boundary has faded, though, in response to the subsidence behind the
departing upper wave and gradual cooling of the boundary layer as we
continue to lose the higher sun angle. Despite these observations,
HRRR continues to show an uptick in convective activity through
around 04Z/11PM CDT this evening, and an increase in SWerly flow
associated with a developing low level jet may give sufficient
forcing for this to materialize. That said, given the observational
trends and support for a dry evening from some models such as the
RAP, have lowered PoPs to just a slight chance for the remainder
of the evening, and confined the area of the slight chance PoPs
closer to the aforementioned frontal boundary.
Deubelbeiss
&&
.DISCUSSION...
Issued at 250 PM CDT Wed Jul 26 2023
Key Messages:
* Heat index of 105 to 110 degrees expected the next couple days,
highest on Friday
* Heat issues lingering into Saturday south of I-72
* Upper pattern favors thunderstorm clusters moving in from the
northwest early next week, though timing is uncertain
While we missed the main MCS that rolled across northern Illinois
early this morning, a decent line of storms did develop toward
midday and has slipped south of I-72. This has been weakening as
of late, and clearing skies behind it have allowed temperatures to
still reach the 90s. Next surface boundary has just passed the
Quad Cities, and continues to be progged by the high-resolution
models to develop some additional convection across the northern
half of the forecast area toward sunset or shortly thereafter.
Will be maintaining 30-ish PoP`s through the evening over most of
the forecast area, except toward Peoria and northward.
The heat remains a challenge the next couple days. Based on
observed dew points today, model guidance appears to be mixing
the air too much. While heat index values are still expected to
be 105-110 degrees, the question is whether it`s from a much
higher dew point coming at the expense of potential triple-digit
temperatures. The NBM temperature guidance continues its bias due
to the excessively hot GFS, which continues to pump in 105-110
degree temperatures both Thursday and Friday. Temperatures closer
to the European MOS guidance may be more realistic, which is also
keeping the dew points higher. For now, will go with highs in the
mid-upper 90s on Thursday and around 100 on Friday. While a
boundary comes through on Saturday, cooler air behind it doesn`t
make significant progress until later in the weekend. Thus, the
later expiration of the Heat Advisory across central/southern
portions of the forecast area still looks good.
The highest rain chances over the upcoming 7 days still appears to
be Friday night as the front comes through. Getting into next
week, the building ridge over the Rockies will favor clusters of
thunderstorms to slide southeast along its periphery. Timing of
such mesoscale clusters is tricky this far in advance, and much
will depend on how much the ridge stays in place. The GFS is more
aggressive with flattening it by Tuesday, as a shortwave tracks
across the Canadian prairies, while the international models only
edge the ridge just east of the Rockies by mid week. That slower
solution would also build the heat risk once again, and longer
range ensembles indicate a 40-60% chance of highs back above 90 by
Wednesday.
Geelhart
&&
.AVIATION... (For the 00z TAFs through 00z Thursday Evening)
Issued at 619 PM CDT Wed Jul 26 2023
A weak trough will settle south across central Illinois overnight.
Breezy SW winds ahead of the trough will become light and variable
under the trough axis overnight, then set up out of the E/SE
Thursday. A few widely scattered showers and storms are possible
this evening, mainly between PIA/BMI and SPI/DEC, though
confidence of any precip on station precludes more than a VCSH
mention at this time. Barring any thunderstorms on station, VFR
conditions are expected through the period.
Deubelbeiss
&&
.CLIMATE...
Issued at 250 PM CDT Wed Jul 26 2023
Record warm low temperatures for Thursday and Friday:
Location Thursday Friday
Champaign 77 (1930) 79 (1930)
Charleston 77 (1936) 80 (1930)
Decatur 78 (1936) 77 (1941)
Jacksonville 78 (1936) 75 (2011)
Lincoln 79 (1936) 75 (1952)
Normal 78 (1997) 76 (1952)
Olney 78 (1936) 76 (1997)
Peoria 77 (1941) 79 (2011)
Springfield 79 (1930) 79 (1941)
Last occurrences of highs 100 degrees or above:
Champaign 8/02/2012 (101 degrees)
Charleston 7/26/2012 (100 degrees)
Decatur 7/25/2012 (101 degrees)
Jacksonville 7/26/2012 (101 degrees)
Lincoln 7/25/2012 (101 degrees)
Normal 6/15/2022 (102 degrees)
Olney 8/02/2012 (100 degrees)
Peoria 7/25/2012 (102 degrees)
Springfield 7/31/2012 (101 degrees)
Geelhart
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
Heat Advisory until 7 PM CDT Friday for ILZ027>031-037-038.
Heat Advisory until 7 PM CDT Saturday for ILZ036-040>057-061>063-
066>068-071>073.
&&
$$
Area Forecast Discussion
National Weather Service Jackson MS
1009 PM CDT Wed Jul 26 2023
...New MESOSCALE UPDATE...
.MESOSCALE UPDATE...
Issued at 1009 PM CDT Wed Jul 26 2023
Rest of tonight...
A quiet night is on tap tonight. Center of 599DM ridge is parked
near the Four Corners to West Texas, with the Gulf Coast to Mid
South remaining on the eastern periphery. Subsident flow is
evident across the region, with regional PWs around 1.4 inches or
less, but GOES East total PWs indicate deeper moisture across the
NW Delta, where increased ascent/increased mid-high level
cloudiness resides. Expect clouds to persist but thin to the north,
but cloud free night elsewhere. With sfc ridge over the area &
dewpoints falling into the mid-upper 60s, temps will radiate,
falling near seasonable lows in the low 70s. No major changes to
the going forecast were needed. Updates are out. /DC/
&&
.DISCUSSION...
Issued at 257 PM CDT Wed Jul 26 2023
This Afternoon through Tomorrow:
High pressure and upper-level ridging will prevail over the region
today into tomorrow - resulting in mostly dry conditions through at
least tomorrow morning. The driest PWAT values today will remain
concentrated mainly south of Interstate 20, but low-level flow will
begin to spread better moisture from the south and east heading into
tomorrow. Latest HRRR still tries to indicate some isolated
convection in southeast MS this afternoon, but visible satellite
shows fairly stable fair weather cu field down to the Gulf Coast.
Tomorrow may be more supportive for at least some isolated shower or
thunderstorm activity, so added slight chance POPs for tomorrow
afternoon south of a Natchez-Jackson-Meridian line. /NF/
Friday through Wednesday:
The longterm forecast continues with the persistent pattern of hot
and humid conditions. A stout 598 dam 500mb high still looms over
the southwestern states. In addition a low level 1020mb high placed
over the Blue Ridge mountain region will extend southwest over our
CWA. Rain chances will be low Saturday through through Wednesday
with the best chances below the I-20 corridor as PWATs and
dewpoints will steadily increase as the period progresses. Some
thunderstorms will be possible for Saturday on but will be far and
few between. Increasing heat stress into the weekend is our main
concern as we continue with limited heat stress possible on Friday
with elevated heat stress possible Saturday and Sunday.
Temperatures will top out Monday with temperatures in the high 90s
to low 100s and will cause the heat index to near 115 degrees. A
Heat Advisory is likely to be needed for this weekend and the
beginning of next week as temperatures steadily increase.
&&
.AVIATION...
(00Z TAFS)
Issued at 701 PM CDT Wed Jul 26 2023
VFR flight categories & light southerly sfc winds, at most around
10mph with brief higher gusts, will prevail at all TAF sites
through the next 24 hours. Some mid-high level SCT-BKN clouds/cigs
around 15-25kft are ongoing at northern TAF sites while more
scattered cumulus/ceilings around 6-7kft elsewhere. Expect most
clouds to dissipate into the evening, but some high clouds to
persist. /DC/
&&
.PRELIMINARY POINT TEMPS/POPS...
Jackson 73 98 74 97 / 0 20 0 10
Meridian 73 98 74 97 / 0 20 0 10
Vicksburg 73 97 74 97 / 0 10 0 10
Hattiesburg 73 97 73 97 / 0 20 0 10
Natchez 72 96 73 96 / 0 20 0 10
Greenville 73 97 75 96 / 0 0 0 0
Greenwood 74 98 76 98 / 0 0 0 0
&&
.JAN WATCHES/WARNINGS/ADVISORIES...
MS...None.
LA...None.
AR...None.
&&
$$
DC/KP/DC
...UPDATED AVIATION FORECAST DISCUSSION...
.SYNOPSIS...
Issued at 247 PM CDT Wed Jul 26 2023
Key Messages:
- Heat advisory conditions are likely this afternoon and again
Thursday across parts of southwest and north central Nebraska.
- Severe weather is possible tonight, Thursday and again Friday.
Storm coverage is generally expected to remain isolated and the
main concern is wind damage.
- Heat advisory conditions are possible Friday.
&&
.SHORT TERM...(This evening through Thursday night)
Issued at 247 PM CDT Wed Jul 26 2023
A short fused Heat advisory is in place this afternoon across parts
of southwest and north central Nebraska where at 2 pm CDT,
temperatures and humidity have breached the 100F heat advisory
criteria.
Satellite shows a weak but billowing upper level disturbance moving
along I-80 across wrn Nebraska this afternoon. This feature could
activate shortly. Another potential focus for storms is a dryline
which has surged east into wrn Nebraska and sharpened up. Farther
west, storms are underway across the Colorado Front Range/Palmer
Divide and it is in this area and areas to east that upscale growth
is shown to occur in the HRRR model.
The instability is about half of what it was Tuesday afternoon
suggesting less intense storm development. This is backed by the
HRRR which predicts storm tops less than Tuesday`s forecast. The
storms across wrn/ncntl Nebraska, if they develop, should exit east
around 02z while the system predicted by the HRRR across swrn
Nebraska departs around 05z. Wind damage is the primary hazard.
POPs for this forecast lean on the Short term model blend plus the
HRRR. The POP forecast is limited to a 30 percent chance.
The next chance for thunderstorms arrives late Thursday. The models
are very quiet with development leaning on the Laramie, Big Horns
and Front Range for initiation. There may be upper level support
back across srn CA this afternoon which will move northeast through
WY Thursday afternoon. The storm activity from this disturbance
would likely get carried into wrn SD. Across wrn and ncntl Nebraska,
the models suggest less moisture with PWAT around an inch vs this
afternoon`s 1.25 inches. The super-heated sfc air suggests wind
damage as the main severe weather concern.
The temperature forecast suggested by the short term model blend
suggested highs in the 90s to near 100F Thursday. The same dew point
forecast nudged up using the 90th percentile NBM, plus a degree or
two for good measure places areas near and east of highway 83 in
heat advisory conditions. A Heat Advisory will be issued for these
areas from 1 pm to 9 pm Thursday.
.LONG TERM...(Friday through Wednesday)
Issued at 247 PM CDT Wed Jul 26 2023
There continues to be little change in the extended forecast philosophy.
Wrn and ncntl Nebraska will remain under a plume of subtropical
moisture operating around the periphery of a strong upper level
ridge of high pressure located over NM. The ridge will slowly
migrate east into the srn Plains this week and next. Isolated to
low-end scattered POPs are in place during the next 7 days.
Moisture will be plentiful during this time but rain chances will
be dependent upon upper level forcing. A strong cap will be in
place through Friday which could certainly limit rain chances. The
cap will weaken this morning and then restrengthen next week.
The model consensus suggests modest cooling will occur Saturday and
perhaps last into Sunday before the onset of another heat wave
Monday and beyond. The heat wave next week is the result of the
upper level ridge migrating east into the srn Plains and a long wave
trof impinging upon srn CA. This should flush a fresh batch of hot
air across the Rockies and into Nebraska.
For Friday, heat advisory conditions are contingent on the dew point
forecast. Thus far, forecast skill in handling the 70F+ dew points
has been problematic with a wide range of solutions in the models.
If dew points rise into the upper 60s Friday, a heat advisory would
likely be needed. The strong cap in place during this time could
certainly trap moisture presenting humid weather to the region.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 623 PM CDT Wed Jul 26 2023
The main aviation concern in the short-term period is the
potential for isolated to scattered thunderstorms this evening for
areas across southwest and portions of north central Nebraska.
Confidence is low on direct impacts to the KLBF, thus did include
a VCTS mention for a brief period from 03Z to 06Z. For KVTN and
northern terminals, thunderstorms are anticipated to remain south
of the area, thus did not include mention with this TAF issuance.
Any thunderstorms that do develop will be capable of strong,
erratic wind gusts and large hail. The thunderstorm activity is
expected to exit the area around midnight. Outside of any
thunderstorms, VFR conditions are expected to prevail through the
TAF period.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
Heat Advisory from 1 PM CDT /noon MDT/ to 9 PM CDT /8 PM MDT/
Thursday for NEZ006>010-026>029-069>071.
Heat Advisory until 9 PM CDT Thursday for NEZ037-038-059.
&&
$$
SYNOPSIS...CDC
SHORT TERM...CDC
LONG TERM...CDC
AVIATION...Viken
Area Forecast Discussion
National Weather Service Marquette MI
634 PM EDT Wed Jul 26 2023
.SHORT TERM...(The rest of this afternoon through tonight)
Issued at 222 PM EDT WED JUL 26 2023
As an MCS over southern Lower MI continues southeastward this
afternoon, some showers and thunderstorms over our area are leaving
with it, with satellite imagery already showing the western UP dry
and partly cloudy now. With CAMs showing the precip ending quickly
over the next few hours over the central and east, expect the temps
to begin rising again behind it late this afternoon, as observations
are already showing this in the west. Moving into the evening and
early night hours, expect generally calm conditions. However, as
warm, moist air remains over the saturated ground, expect some
areas of fog to form across the interior areas late tonight,
particularly over the eastern half due to less evaporation from
this afternoon`s sunlight. In addition, as a cold front approaches
from northern Ontario late tonight, there is a slight chance for
some showers and thunderstorms to effect the western portions of the
CWA near Lake Superior by Thursday morning.
.LONG TERM...(Thursday night through Wednesday)
Issued at 419 PM EDT WED JUL 26 2023
Thursday, a surface trough passing just north of Lake Superior will
help kick off some showers and sub-severe thunderstorms in the
morning along the spine of the Keweenaw and over the western third
of the UP. As the cold front sags south through the day, lapse rates
steepen significantly and instability surges. 12Z HREF guidance
shows mean SBCAPE values exceeding 2,000 J/kg along the MI/WI line
with the max SBCAPE values showing the potential for up to 4,000
J/kg of CAPE. Minimum SBCAPE values however are 0, showing that
there is some capping involved that may limit some afternoon storm
development. The NAM Nest, for once, is actually the HREF member
with the least thunderstorm coverage, showing the potential for a
holding cap. If the morning is particularly foggy and/or the first
round of morning showers limits diurnal heating, the cap may be too
strong to overcome. However, more than likely, local lifting
mechanisms, diurnal heating, or the front will provide the lift
necessary to initiate thunderstorms. Plentiful shear exists, with
bulk shear values of 30-40 knots expected and a fairly direct
westerly storm motion expected. Timing-wise, by the HREF maximum
helicity tracks, the window for strongest thunderstorms is expected
to be around 22Z-02Z. Overall, this is a fairly similar setup to the
July 10th convection over the UP that caused a few severe hail and
wind reports, and those are also the expected severe threats for
Thursday. An isolated heavy rain threat is also not out of the
question depending on the orientation of upscale growth. The HREF
CAMs differ on the orientation of whatever linear formation
develops, with the 12Z HRRR showing a fairly NNE/SSW orientation
while the WRF ARW shows a nearly perfect E/W orientation, with the
other WRFs falling somewhere in between. If the orientation is more
parallel with the bulk shear vector, some training could lead to
multiple inches of rain for a few spots, but otherwise, half an inch
to an inch of precip is expected. While it will be a warmer day,
only a couple spots are expected to hit 90 as thunderstorm outflow
may keep surface temperatures from climbing too much.
Friday, lingering convection is possible over the southern portions
of the UP as the boundary stalls a bit and another shortwave passes
in the early afternoon. This will be supported by a 250-300mb 100kt
jet over northern Ontario, with the UP being in the right entrance
region for upper level divergence and subsequent lift. However, it
is possible the jet may be too far north to be useful for convection
over the southern UP. Especially given the previous day`s showers
and thunderstorms, severe thunderstorms are not expected for Friday
and QPF values should remain at a quarter inch or less except for
Menominee itself which has a NBM 50th percentile daily QPF of a
third of an inch.
After a bit of a break from the broad troughing over the eastern
CONUS and ridging over the Rockies, that setup builds back again for
the weekend. Most GEFS ensemble members keep the UP dry over the
weekend but not all. This is not terribly surprising as the
northwest flow pattern aloft has been noteworthy for weak diurnal
showers in the afternoon/evening hours, but for now, this forecast
package only increases the precip chances for Saturday evening. GEFS
pressure centers show a 1020mb surface high residing over the Upper
Midwest Sunday afternoon, likely keeping showers at bay through
Monday as well, though some diurnal showers are possible Monday.
Into next week, the GEFS shows a weak surface low passing through
northern Ontario late Tuesday, but significant ensemble spread
exists regarding the path and timing of the low passage. The
deterministic global guidance varies significantly into the mid week
period, with the GFS taking a trough making landfall over Vancouver
early in the week and sending it through Canada by midweek, while
the Canadian has a trough sinking south from the Hudson Bay
dramatically in the mid to late week time period, while the Euro
keeps the pattern stable into next weekend with only subtle
shortwaves in the flow. With a lack of agreement between the global
deterministic guidance, the ensembles, and even run-to-run
inconsistency, uncertainty is high, but temperatures should
generally be closer to normal under Canadian flow.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 634 PM EDT WED JUL 26 2023
VFR conditions will continue at IWD through the forecast period. At
CMX and SAW, fog will develop overnight and will get down to
LIFR/VLIFR conditions before returning to VFR conditions Thu morning.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 419 PM EDT WED JUL 26 2023
Winds are expected to largely remain at or below 20 knots for the
forecast period. Some marine fog is expected tonight into Thursday
morning but should dissipate with an approaching cold front.
Thunderstorms are expected Thursday, especially near the Lake
Superior lakeshores, with some potential for locally damaging winds
or hail.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...TAP
LONG TERM...GS
AVIATION...07
MARINE...GS
Area Forecast Discussion
National Weather Service Pueblo CO
352 PM MDT Wed Jul 26 2023
.SHORT TERM...(This evening through Thursday)
Issued at 314 PM MDT Wed Jul 26 2023
Key Messages:
1) Strong to severe thunderstorms possible this evening
southeast plains with a similar scenario expected for Thursday.
Westerly flow aloft will continue to bring increasing mid and high
level monsoon moisture across southern Colorado with elevated CAPE
and inverted V soundings favoring damaging wind gusts 60+ mph as
storms move off the mountains and across the adjacent lower
elevations. DCAPE across the plains will remain quite high...in the
1500+ J/kg range. In spite of that, some storms have been capable of
producing locally heavy rainfall given the subtly increasing PWATs
within the modest monsoon plume, especially where outflow boundary
interactions occur. As storms move east into the southeast plains,
better low level moisture and higher elevated CAPE will allow for
hail over 1 inch in diameter as they propagate into a more favorable
environment...however they are likely to become quickly outflow
dominant given the dry subcloud layer. Stronger flow aloft to the
north will keep the best deep layer shear to the north of highway
50, where the best chance for severe storms will continue into this
evening. Thunderstorms will diminish towards 9 PM.
A similar pattern exists for Thursday with a subtle increase in
PWATs. Surface winds look a little more westerly tomorrow which may
keep higher CAPE farther to the east of the I-25 corridor counties.
Again, gusty outflow winds to 50-60 mph could occur anywhere across
southern CO given the inverted V soundings. A hail risk will exist
for the eastern most plains counties where CAPEs will be greatest in
the late afternoon and early evening. The mountains will see an
uptick in thunderstorm chances as well, with pockets of heavy
rainfall possible, though these are expected to remain localized as
storm motions should be a respectable speed...to the east at 20 to
25 mph. This should reduce but not eliminate the risk of flash
flooding on burn scars.
Given more convective cloud cover, temperatures tomorrow will be
cooler which should limit the duration and coverage of Heat Advisory
criteria. Therefore no highlights will be issued as clouds will
likely offset the heat some. Didn`t stray far from model blends for
high temperatures. -KT
.LONG TERM...(Thursday night through Wednesday)
Issued at 314 PM MDT Wed Jul 26 2023
Key messages:
1) Strong to severe thunderstorms will be possible Thursday evening,
mainly over the far eastern plains. Main threats will be strong
gusty winds of 60 mph or greater and hail up to 2 inches in diameter.
2) Afternoon storms over the mountains and evening storms over the
plains will be possible from Friday through Saturday. Severe storms
will be possible over the eastern plains.
3) Afternoon and evening thunderstorms will be more confined over
the mountains from Sunday through Tuesday, and drier over the
eastern plains.
4) Afternoon and evening thunderstorms will have more widespread
coverage next Wednesday with a better chance of precip over the
plains.
5) Overall temperature trend will be a slight cooldown but remaining
above the seasonal average through next Tuesday. Then, notably
cooler next Wednesday, and slightly below the seasonal average.
Detailed discussion:
Thursday night...
Stronger, and potentially severe thunderstorms, will be possible
tomorrow evening, mainly over the far eastern plains. The latest CAM
model data suggests that most of the storms over the far eastern
plains will likely begin to merge by around this time which could
morph into a linear echo wave pattern (LEWP) towards the later
evening hours. If this comes to fruition, there could be a very
strong and gusty FFD ahead of it, which may produce straight-line
damaging winds greater than 60 mph. The HRRR picks up on this the
best, with severe strength winds moving through Bent and Prowers
County right around 6 PM, and then through eastern Kiowa County
between 7 and 8 PM. In addition, there will also be very high areas
of DCAPE, greater than 2000 J/kg over the far eastern plains between
6 to 8 PM, therefore storms that move into this environment, which
could also aid in the production of very strong outflow winds that
could be in excess of 70 mph. Other threats will be large and
damaging hail of possibly 2 inches or greater in diameter. The NAM
3km and WRF-ARW are also picking up on some areas of very high 0-1
km SRH along the leading line of the convection of nearly 400 m2s2,
so there also exists the possibility of a few landspouts or even an
isolated weak tornado or two, especially embedded within the LEWP.
As the evening progresses and the lower levels continue to become
more stabilized, any remaining storm should begin to weaken and
dissipate with all precip likely coming to an end over the CWA by
midnight. Lows will drop mid to upper 60s over the plains, and
generally be in the upper 40s and 50s for high country.
Friday through Saturday...
Models continue to display that the overall longwave pattern will
not see much change through the course of this period in the
forecast. A well-established ridge over the Colorado will nearly
remain stationary with only a slight weakening in the ridge as it
slowly propagates towards the east. There will be slightly drier air
in place on Friday, but then increasing moisture in the mid-levels
on Saturday as the monsoonal pattern continues to become more
pronounced and the southwesterly flow over Arizona helps to advect
moisture over Colorado with the characteristics of a "dirty ridge."
Orographic lifting, with the monsoonal moisture will allow for the
development of convection over the higher terrain by early afternoon
and then the southwest to westerly flow will force storms to move
off the mountains and into the I-25 corridor by late afternoon.
There will also continue to be higher dewpoints and more instability
further east which will cause storms the move over these areas by
later during the evening to become stronger to severe for Friday as
some higher dewpoints and better instability remain in place.
As the ridge continues to slightly weaken overhead and propagate
further east, it will allow for temperatures to only slightly cool
for both days, but remain above the seasonal average for most areas.
Plains will remain the hottest, where there will also be downsloping
westerly winds in place. Many locations over the plains will top the
100 degree mark for Friday, but should remain in the 90s by Saturday.
Sunday through Wednesday...
The ridge will establish itself with the position of the upper level
high being centered over Kansas/Oklahoma by Sunday. This will keep
the monsoonal moisture plume along with development of afternoon and
evening thunderstorms more confined to the mountains with the mid
level flow being more southerly rather than westerly. There could be
a few storms that make it out into the adjacent plains but the
majority of the plains, and especially the eastern plains should
remain mostly dry through Tuesday. On Wednesday, there is some
general agreement between the deterministic models of an upper level
low propagating northeastward from Baja California towards the great
basin, although the timing of this differs between the models.
This could help influence and increase in the coverage of
thunderstorms over the region depending on whether this
materializes and how this low tracks. Models have been consistent
in showing this feature, although it is still subject to change
since it is a week out. PWAT values with ensembles have been
displaying an uptick in precip over the area as well. This
approaching trough will also help to cool temperatures below the
seasonal average on Wednesday. -Stewey
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 314 PM MDT Wed Jul 26 2023
Thunderstorms will be possible at the terminals through early
evening before activity pushes eastward. The main risk will
transition from VCTS to outflow dominated winds 20 to 30 kts before
winds subside during the 02-04z timeframe. Expect clearing skies
with VFR conditions overnight. Thunderstorms will redevelop over
the mountains around 18z and spread off into the adjacent valleys
and plains during the afternoon. Erratic gusty outflow winds will
be possible at all three terminals Thursday afternoon and VCTS will
likely be necessary for all three terminals after 20-21z. -KT
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
Heat Advisory until 8 PM MDT this evening for COZ069>071-087-088.
&&
$$
SHORT TERM...KT
LONG TERM...STEWARD
AVIATION...KT