Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 07/05/23
Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
839 PM CDT Tue Jul 4 2023
.UPDATE...
Issued at 835 PM CDT Tue Jul 4 2023
Cold front continues to make its way across the CWA, having
recently passed ABR. Over the past hour or so, we`ve seen a broken
line of showers develop along this front, just to the east of ABR.
Had to introduce POPs to the forecast for this evening for the
eastern CWA. HRRR actually has been showing this for the past
several runs and it seems to be panning out. Will watch radar
trends this evening and adjust POPs as needed.
&&
.SHORT TERM...(This Evening through Wednesday Night)
Issued at 306 PM CDT Tue Jul 4 2023
The main forecast challenge in the near term revolves around
additional chances for precipitation across the far southeastern CWA
this evening. The frontal boundary that brought rain to the area
late night and this morning currently extends from central Minnesota
to central Nebraska. Most of the activity this afternoon so far has
remained south and east of the CWA, but may see a stray shower or
storm still develop as far north as the Deuel/Hamlin county area, so
will keep small POPs going into the early evening hours. High
pressure will drop over the Northern Plains later tonight
through Wednesday night, with dry and cooler conditions expected.
Low temperatures tonight will be in the upper 40s to lower 50s. High
temperatures on Wednesday will be in the upper 60s to lower 70s.
Lows Wednesday night will again be in the upper 40s to lower 50s.
.LONG TERM...(Thursday through Tuesday)
Issued at 306 PM CDT Tue Jul 4 2023
Not much overall change in the extended with dry conditions as the
upper trough migrates east with weak ridging upstream and northwest
flow overhead. A northwest flow wave is still on the books for
Friday, a little earlier than previously forecast. There will be a
vary narrow axis of modest instability ahead of the wave with a cool
dry high pressure by then over Minnesota...and Gulf of Mexico
moisture is still cut off by that point. Shear between deterministic
GFS/NAM is about 25 to 35kts with 1 to 2k j/kg MLCAPE...so maybe a
narrow axis of potential severe weather but confidence on timing is
low and much will depend on where this narrow axis of instability
ends up being during peak heating. After that, another area of
Canadian high pressure moves across the region. Next system after
that is later in the weekend with another wave pivoting around the
base of the upper trough, but will hash out those details in
upcoming runs given uncertainty. As for temperatures, it will remain
slightly below normal for the next several days.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday Evening)
Issued at 625 PM CDT Tue Jul 4 2023
Terminals KABR,KATY,KPIR,KMBG
VFR conditions are forecast through the TAF period. A -SHRA may
affect KMBG this evening, with conditions expected to remain VFR.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
&&
$$
UPDATE...TMT
SHORT TERM...Parkin
LONG TERM...Connelly
AVIATION...TMT
Area Forecast Discussion
National Weather Service La Crosse WI
1056 PM CDT Tue Jul 4 2023
.DISCUSSION...(This evening through Tuesday)
Issued at 238 PM CDT Tue Jul 4 2023
Key Messages:
- The areal extent of the severe storm risk has shifted slightly
northwest and decreased overall. Storms should develop and
move into northcentral WI, northeast IA and southeast MN this
evening, an isolated severe storm is still possible.
- As storms shift east, later in the evening, a decrease in
strength and coverage is expect, with mainly a lightning risk.
- More comfortable weather takes over with temperatures near or below
normal and periodic shower chances Saturday through Tuesday.
Overview:
Thunderstorms developed over parts of Minnesota and northern
Wisconsin Monday night and dropped south overnight. An outflow
boundary developed ahead of the storms and storm developed and east
to west line. Tapping into instability and moisture and a wind field
that fed into the storms along with some upper level support, storms
trained, but the cluster was also progressive, resulting in a
convective complex that continued southward producing nature`s own
fireworks and a good soaking rain for some. Parts of northern
Rochester reported over an inch of rain, while the airport only had
a trace! The La Crosse airport had 1.46 inches, here at the NWS
office we had 1.35 inches. Stoddard 5 NNE had 1.64 inches and
Onalaska also had 1.35 inches.
Water vapor satellite imagery, heights, and lightning showed a
broad trough from Manitoba through the northern Rockies. A
shortwave trough was moving through parts of MN/SD late in the
morning with a couple of clusters of storms and some isolated
storm activity ahead of it. Trailing farther west...some lightning
was noted across parts of Wyoming with the next more pronounced
shortwave.
At 11am at the surface, a pre-frontal trough was noted from just
west of Red Wing, MN to near Mankato with southwest flow and
dewpoints in the 60s to low 70s. farther west, the cold front had
pushed through parts of western Minnesota. SPC meso-graphics has
MLCAPE building had of the trough and cold from 1000-2000K/kg with
stronger de-stabilization southwestward toward northwest Iowa and
Nebraska.
Scattered Thunderstorms, Potentially Strong to Severe:
Isolated to scattered storms were ongoing early this afternoon
over Wisconsin with additional storms over parts of northwest
Iowa. The CAMS, at least the ARW/HRRR/RAP take these storms into
north central Wisconsin, but are not picking up on the storms
farther south. The storms farther north have a little more
organization as this is also tapping into a local instability
maximum. The storms farther south are partly in the thickness
diffluent region and with the wave lifting east across the area
along with destabilization of around 1500 to 2000 MLCAPE.
Convective debris and rains have limited destabilization thus far
over parts of MN/IA. This does bring into question how the
convection will evolve. The short range deterministic NAM/GFS
have more of a splitting in the convection with one area affecting
northern WI and another area over Neb/WI. The EC is in-between
with convection moving eastward into the forecast area this
evening with most of the short term models continuing showers and
a few storms overnight into Wednesday. The CAMs are similar with
these differences with the HRRR being more aggressive with the
convection moving in this evening. With these differences, have
maintained higher precipitation chances with the cold front for
showers and scattered storms increasing this evening as MLCAPE
increases 1500 to 2500 J/kg across the western portions of the
forecast area through 00Z...but weakens to 1500J/kg by 03Z. The
severe risk has been shifted slightly west and this seems
reasonable with the greater instability farther west.
Wednesday
There is good model consensus on convectively enhanced shortwave
trough activity shifting across the area late morning into mid-day
on Wednesday stemming from front range convection tonight. There is
some weak-moderate QVector convergence forcing through the
troposphere with this activity (not bad for July!). The overall
consensus in the CAMS and latest deterministic models is to shift
the front and boundary layer instability southeast of the area by
Wednesday afternoon, but lingering elevated instability /CAPE < 200
J/Kg/ above the frontal surface will be worked on by this lift.
Would think showers are likely from central WI into far northeast
Iowa and southwest WI, possibly a storm around late morning and
early afternoon. So, have generally slowed the timing of the rain
chances moving east/out into late afternoon Wednesday and increase
rain chances. The severe storm threat Wednesday is to the southeast
of the area. Cooler temperatures will be noticeable, and some
clearing is expected in the afternoon north and west of La Crosse.
Comfortable Period with Periodic Showers Thursday-Tuesday
Thursday through Tuesday will dominated by northwest flow and large
scale troughing over the northcentral U.S...building into the
northeast by late in the period. As shortwave troughs rotate through
this flow, periodic rain chances will occur as diurnal instability
is throttled up a touch for showers beginning Saturday. The latest
grand ensemble (ECMWF/GEFS/Canadian) suggests only 25-40% chances of
exceeding 0.25"/24 hours Sunday into Monday. Instability in this
flow pattern is quite low /as expected/ with less than a 30% chance
of reaching 500 J/Kg of SBCAPE in that same time frame /across
northeast IA and southwest WI/. CAPE values increase south of the
area toward I-80 where the trough isnt such as influence. But, there
is enough instability to cause low rain chances /20-40%/ beginning
Saturday and continuing into Monday. As this time frame approaches,
more tuning on the timing and chances will occur. Temperatures will
begin below normal mid-week and rise to near normal for the weekend.
&&
.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1056 PM CDT Tue Jul 4 2023
A cold front was moving slowly across the area this evening with
some scattered convection along it. With the best forcing passing
by to the south, the CAMs are suggesting the convection will
remain scattered and will have VCTS/VCSH for both sites for a few
hours overnight. Some MVFR ceilings are in place behind the front
and these should spread over both airports behind the front before
moving off to the east by late Wednesday morning. Once they do,
VFR conditions then expected for the Wednesday afternoon and
evening.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
DISCUSSION...Zapotocny/Baumgardt
AVIATION...04
Area Forecast Discussion
National Weather Service Columbia SC
940 PM EDT Tue Jul 4 2023
.SYNOPSIS...
Expect hot and humid conditions again today, with a chance of
mainly afternoon and evening thunderstorms. A shortwave trough
combined with a remnant surface bounday will support increased
shower and thunderstorm chances on Wednesday. Temperatures are
expected to return to near normal values with daily chances of
mainly afternoon and evening thunderstorms, on Thursday and into
the weekend.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
Boundary collisions may keep convection going overnight as
multiple outflows intersect over central SC and the CSRA with
elevated instability present. Expect isolated showers and
thunderstorms to continue beyond midnight. The threat of severe
weather has diminished with little surface based instability
remaining. The RAP suggests a weak shortwave may move over the
forecast area in the early morning, although CAMs do not show
re development. Convective debris clouds and humidity will keep
lows seasonable in the low to mid 70s.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/...
The upper ridge will continue to flatten out Wednesday which will
keep temperatures a few degrees cooler, although near seasonal
average with highs in the low 90s. HREF mean indicates deep layer
moisture will increase further with PWATs above 2 inches for much of
the area and near 2.2 inches in the southeast portion of the
forecast area. Do expect better forcing Wednesday with global models
indicating a stronger shortwave moving into the northern portion of
the forecast area in the afternoon and evening. There may be a bit
of a capping inversion early but forecast soundings are consistent
in eroding the cap with moderate to strong destabilization across
the area. The highest chances for thunderstorms will be along the
sea breeze with the best surface convergence and across the northern
portion of the forecast area where the shortwave will move near.
Shear will be limited but with moderate to strong DCAPE, a marginal
risk for damaging wind gusts in place across the entire area
tomorrow. There will also be at least a low end flash flood concern
as warm rain processes will dominate tomorrow and PWATs approaching
near the 90th percentile. Convection may linger into Wednesday night
depending on the timing of the shortwave. Low temperatures near
average in the low to mid 70s.
A bit of northwest flow may develop aloft Thursday behind the
shortwave axis which forecast soundings indicate may bring in some
drier air aloft during the day Thursday. Not as obvious of a trigger
for Thursday but moderate instability and some surface convergence
along a weak surface trough in the east will likely promote
scattered thunderstorms. Similar temperatures to Wednesday, near
seasonal average for both highs and lows.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
A fairly typical summertime synoptic pattern expected for the
long term as the flow remains zonal with ensemble means
indicating near average heights and near average PWATs. This
will lead to a forecast each day that will mostly favor
climatology with highs in the low 90s and lows in the low 70s
each day through the extended. Scattered thunderstorms will be
possible each day, keeping them in the chance category each day
generally forced by mesoscale features such as the sea breeze
and lingering outflows from other storms.
&&
.AVIATION /02Z WEDNESDAY THROUGH SUNDAY/...
Generally VFR conditions are expected through the TAF period.
ISOLD-SCT -SHRA/-TSRA mainly east of the terminals except for OGB.
Cloud bases generally 5-8kft MSL with cirrus above. SFC winds
generally light and variable, but may increase directionally with
any storm outflows which could reach 20 kts. This may also trigger
new development of -SHRA/-TSRA through late this evening, but
confidence too low to include in TAFs. Convective debris clouds
expected overnight then diminishing Wednesday morning as the cu
field redevelops. Low confidence in VSBY restrictions around
daybreak. Another round of SCT -SHRA/-TSRA expected Wednesday
afternoon.
EXTENDED AVIATION OUTLOOK...Brief restrictions are possible
daily through Saturday from showers and thunderstorms, mainly
during the afternoon and evening hours. Hazy conditions and
areas of patchy early morning fog are also possible each day.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
&&
$$
Area Forecast Discussion
National Weather Service Dodge City KS
615 PM CDT Tue Jul 4 2023
...UPDATE TO AVIATION...
.SHORT TERM...(This evening through Wednesday night)
Issued at 1225 PM CDT Tue Jul 4 2023
17z observations show a large upper high centered in southeast
Arizona and a longwave trough centered in the northern plains.
This has led to generally westerly upper level winds in our area
with a shortwave developing just west of Denver. At the surface a
cold front is located in northeast Colorado through southwest and
central Nebraska and will be the focus of our thunderstorm event
tonight.
We should see thunderstorms start to develop very late this
afternoon along the cold front as the upper level energy moves in
from the west. CAM models have trended more with a later arrival
into southwest Kansas and the main threat being some strong
outflow winds ahead of the storms which could top 70+ mph. NAM
and RAP models show some health post frontal moisture with 65-68 F
dewpoints wrapping in behind the cold front which should keep the
thunderstorms going as they progress to the south and east. The
main concern will be the timing of the storms as they will likely
coincide with 4th of July fireworks displays and most of the
models showing a good line of storms around 10 pm from Syracuse to
Hays. Overall think the higher end wind threat that SPC has put
out in our northern zones is warranted with a lesser hail and
almost nil tornado threat given the high LCL levels.
Wednesday could be a potential forecast challenge given how
tonight`s convection evolves. Most short term models think that
the storms should give the momentum needed to push the cold front
into Oklahoma which would likely diminish the severe threat with
the exception of the far southeast. Overall it should be a cooler
day as we will have post storm clouds in the morning along with
northeast winds for much of the day. Model guidance has most of
southwest Kansas seeing highs in the mid to upper 70s with the
exception of the far southeast where the front looks to stall out
and perhaps lift a bit farther north by afternoon.
Wednesday night we should see another MCS develop in the front
range of the Rockies which will enter southwest Kansas after
midnight. NAM, HRRR and RAP display a fairly healthy shortwave
with the convection and good moisture fields with QPF outputs of
up to an inch. Given this signal I kept POPs in the likely
category. These storms should just be rain makers as the CAPE
values will be diminished when they arrive after midnight which
will mitigate the severe risk.
.LONG TERM...(Thursday through Tuesday)
Issued at 154 PM CDT Tue Jul 4 2023
Active weather continues into Thursday as we should see another
MCS develop in northeast Colorado and dive to the south and east
during the night. By the time it reaches southwest Kansas most of
the severe threat should start to wind down however we could once
again see locally heavier rainfall with QPF output from the
various ensembles showing a range of 0.5 to 1.5 inches.
Friday a sharp baroclinic zone develops as a warm front will lift
into southwest Kansas and the cooler more stable air with clouds
will stay entrenched in the north and east. Highs will range from
the lower 80s in the northeast to the lower and mid 90s around
Elkhart. With the frontal boundary in place we should have another
shortwave kick up convection in eastern Colorado and ride into
western Kansas during the night giving us a good chance of another
soaking.
Long term ensembles keep us in an active weather pattern for the
rest of the weekend with another overnight MCS Saturday night into
Sunday morning. Temperatures are on an upward trend into next week
with 90s degree highs returning.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 615 PM CDT Tue Jul 4 2023
Ongoing developing thunderstorms will move east-southeast across
west central Kansas into northern portions of southwest Kansas
through late evening, potentially affecting KHYS and KGCK generally
after 02-04Z. Otherwise, VFR conditions will prevail elsewhere
through late evening. Low level stratus developing along and behind
a cold front pushing southeast through western Kansas overnight is
expected to result in MVFR cigs in vicinity of KHYS, KGCK, and KDDC
generally after 08-10Z. Southerly winds around 15 to 25kt through
late evening are forecast to turn north-northeasterly around 15
to 25kt behind the aforementioned cold front as it moves through
western Kansas overnight.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 66 76 59 77 / 30 20 80 20
GCK 64 73 58 75 / 40 10 80 10
EHA 63 75 59 79 / 30 10 60 10
LBL 65 78 59 76 / 20 10 60 10
HYS 64 75 57 78 / 70 20 30 20
P28 70 86 62 79 / 10 20 60 30
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Tatro
LONG TERM...Tatro
AVIATION...JJohnson
Area Forecast Discussion
National Weather Service Duluth MN
632 PM CDT Tue Jul 4 2023
.DISCUSSION...(This evening through Monday)
Issued at 337 PM CDT Tue Jul 4 2023
Key Messages:
1) Scattered showers and storms continue the rest of today, with a
few strong storms possible through mid-evening over NW Wisconsin.
2) Additional shower and thunderstorm chances late Friday into
Saturday
3) Several more rounds of rain from Sunday into the middle of next
week, but there doesn`t appear to be a signal for heavy
rain/flooding. This will be accompanied by much cooler weather.
Rest of the Afternoon - This Evening:
The MCV from morning convection over Minnesota that is now over NW
Wisconsin has kept an area of scattered thunderstorms ongoing over
Ashland, Price, and Iron Counties as of 330 PM CDT. These storms
are expected to remain sub-severe, with small hail and up to 30-40
mph wind gusts as they push across north-central Wisconsin
through the next couple hours.
As for our severe weather risk for the remainder of this afternoon
into evening, the ongoing convection over NW Wisconsin, lingering
showers over the remainder of the CWA, and expansive cloud cover
have drastically hampered our daytime heating. As a result, MLCAPE
is almost non-existent over all of northeast Minnesota and only
about 500-1500 J/kg over NW Wisconsin. High resolution model
guidance has struggled to pick up on convective trends for most of
the day, with the last two runs of the HRRR finally picking up on
the Wisconsin convection. The trend in these model runs does point
to additional development of scattered thunderstorms by late
afternoon (5-6pm or so) near east-central Minnesota/far west-
central Wisconsin border, with scattered storms persisting over NW
Wisconsin through the evening. However, despite 0-6km bulk shear
of 30-35 knots, MLCAPE drops to <500 J/kg north of a Danbury to
Hayward to Mercer, WI line. South of this line could see around
500-750 J/kg of MLCAPE. With this in mind, a few storms over NW
Wisconsin may become strong through mid-evening with a few wind
gusts up to 50 mph, hail up to penny to quarter size, and locally
heavy rain where thunderstorms repeatedly move overhead, but most
storms will be weaker.
Tonight - Wednesday Morning:
Scattered elevated thunderstorms over NW Wisconsin may persist
into the overnight hours, but instability will continue to
decrease, so storm intensities will also be on a downward trend.
Some light rain showers will linger into the morning hours on
Wednesday, generally east of a line from Spooner to Ashland as a
cold front slides southeast across Wisconsin.
Wednesday - Early Friday:
Surface high pressure will dominate this timeframe, leading to dry
weather and noticeably cooler temperatures through the second half
of the workweek. High temperatures in the mid-60s to low-70s are
expected Wednesday, with low- to mid-70s on Thursday, and mid- to
upper-70s on Friday.
Late Friday - Saturday:
The next round of showers and thunderstorms is forecast to arrive
by late Friday afternoon into Saturday associated with lift from
an upper-level shortwave traversing southern Manitoba through
Central Ontario and a surface-cold front moving southeast across
the Northland. Uncertainty with regards to the intensity and
coverage of storms still exists during this timeframe.
Sunday - Middle of Next Week:
Global ensemble model guidance hints at a series of shortwaves
clipping portions of the Upper Midwest and Upper Great Lakes
regions as they travel around a closed low over northern Manitoba
and northern Ontario, but models differ in the depth and strength
of these shortwave features. Therefore, confidence in pinpointing
precipitation timing and strength remains low during this
timeframe. Have opted to stay with the NBM guidance, which
broadbrushed several periods of 20-40% precipitation chances over
our region through the middle of next week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 632 PM CDT Tue Jul 4 2023
Active weather continues across the Northland this evening with
scattered showers and a few embedded thunderstorms. The severe risk
has greatly diminished but a few elevated stronger storms can`t be
ruled out for later tonight. An additional shot of rain will enter
from the NW tonight as a cold front drops across the region.
Confidence is not extremely high on whether or not there will be
enough moisture left for this boundary to produce rain showers as it
passes. Expected winds to turn to out of the northwest as the front
passes through tomorrow.
&&
.MARINE...
Issued at 337 PM CDT Tue Jul 4 2023
Severe thunderstorm potential has dropped off over Lake Superior
for the remainder of the day due to lingering cloud cover. Could
still see a few isolated storms over the South Shore waters
through this evening, but mainly expect lingering showers. Hazards
with any storms would be winds over 25 knots, small hail, and
occasional cloud-to-water lightning. Winds will shift to the west
to northwest after the cold front moves through late this
evening. Wind speeds and gusts are expected to . Wind speeds and
gusts are expected to remain around 15 kts or lower through
Thursday, and then gust to around 15 to 20 knots along the North
Shore on Friday afternoon as winds turn out of the southwest.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 57 69 49 73 / 50 10 0 0
INL 50 65 44 73 / 20 10 0 0
BRD 55 69 47 74 / 20 0 0 0
HYR 59 73 46 73 / 70 20 0 0
ASX 59 73 50 73 / 70 20 10 0
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
LS...None.
&&
$$
DISCUSSION...Rothstein
AVIATION...Britt
MARINE...Rothstein
Area Forecast Discussion
National Weather Service North Platte NE
618 PM CDT Tue Jul 4 2023
...Aviation discussion...
.SYNOPSIS...
Issued at 236 PM CDT Tue Jul 4 2023
Key Messages:
- Scattered showers and thunderstorms are possible this evening
into tonight across much of western and north central Nebraska.
The greatest severe risk area is across far southwest and
central Nebraska where a Slight Risk of Severe Thunderstorms
exists. Large hail and damaging winds are the primary threats.
- Much cooler conditions arrive Wednesday with temperatures
falling 15 to 20 degrees below the climatological normal. These
cooler conditions continue into the weekend, gradually
returning to near seasonal normals early next week.
- Another round of severe weather is possible on Thursday for
areas west of Highway 83 with large hail being the primary
concern.
- Unsettled weather continues into early next week with daily
shower and thunderstorm chances. The severe potential remains
uncertain at this time.
Recent GOES-16 WV and RAP 500-mb analysis showed a ridge of high
pressure across the Desert Southwest. Further southeast of this
feature, another area of high pressure was noted across the
southwestern Florida into the southern Gulf of Mexico. Further north
of this feature, a broad, positively-tilted trough of low
pressure was centered over northern Manitoba with a trough
extending over the Northern Rockies. At the surface, a trough
extending from Montana was pushing south across Wyoming into the
Panhandle of Nebraska. A deepening surface low was apparent across
far southeastern Colorado. A strong cold front swept across the
forecast area earlier this morning and will be a focus for
thunderstorm development across the area late this afternoon. A
wide range of temperatures and breezy winds has developed across
the area in the front`s wake. At 2 PM CT, temperatures ranged from
65 degrees at Gordon to 83 degrees at Broken Bow. Recent area
observations of 20 to 25 mph have been common across western and
north central Nebraska.
&&
.SHORT TERM...(This evening through Wednesday night)
Issued at 236 PM CDT Tue Jul 4 2023
The main focus in the short-term surrounds shower and
thunderstorm chances across western and north central Nebraska
late this afternoon into tonight. There are two areas of storms
expected to evolve across the area, eventually merging together
later tonight.
The first area of storms surrounds the ongoing development across
the Laramie Range and Front Range. A weak upper-level shortwave
is currently crossing east of the Front Range, directly behind the
advancing cold front leading to increased surface convergence.
This has resulted scattered development across this area.
sufficient low-level moisture and daytime heating across the area
will allow CAPE values to continue to increase this afternoon
into the evening with a finger bisecting portions of Panhandle
into the Sandhills and far southwest Nebraska. The expectation is
that these thunderstorms will continue to track east from the
higher terrain across Wyoming into the Sandhills and portions of
southwest Nebraska late this evening. The severe threat is not
near as robust as what is anticipated with the second area of
storms. However, given that DCAPE values of 500 to 750 J/kg are
present, strong to severe wind gusts and hail cannot be ruled out.
The second area is scattered development along the aforementioned
cold front that is currently tracking southeast across central
Nebraska into northern Kansas. Strong mid-level frontogenetical
forcing and lift has increased directly along and ahead of the
frontal boundary. Surface temperatures along and ahead of the front
in southwest and central Nebraska in the 80s will support
sufficient instability (MLCAPE 1,000 to 3,000 J/kg). Though shear
profiles are marginal at < 30-35kts, with mid-level lapse rates
of ~7C/km, the environment will support storm organization and an
isolated strong to briefly severe thunderstorms across portions of
far southwest and central Nebraska. The environment is supportive
of damaging winds and large hail. Any strong to severe storms
will be rather short lived before diurnal heating gradually
concludes and the frontal boundary pushes further south and east,
limiting overall lift/forcing and instability. The window of
timing of the greatest severe threat is from 5 to 11 PM CT.
Both of these areas of storms will eventually merge into a messy MCS
later tonight, primarily around midnight. These storms will
continue into the night and will eventually be shunted off to the
southeast as the cold front continues it`s journey early
Wednesday. Lingering showers and embedded thunderstorms may linger
into the early morning hours on Wednesday, however, additional
disturbances tracking across the area will result in scattered
showers to redevelop across portions of the local area on
Wednesday.
As the aforementioned upper-level trough of low pressure tracks
eastward across Manitoba and the Upper Midwest, nearly zonal flow
aloft will develop across the area early Wednesday. Multiple
disturbances will eject across the local area, bringing periodic
scattered precipitation chances through the bulk of the day on
Wednesday. Lack of diurnal heating due to anomalously cool
temperatures and persistent cloud cover will result in little to no
instability across the area. This combined with lack of lift and
forcing will lead to scattered showers across western and north
central Nebraska. In regards to temperatures on Wednesday, highs are
expected to remain in the mid to upper 60s across northwest Nebraska
to the mid 70s across southwest Nebraska. These fall like
temperatures are anomalous for the beginning of July, to say the
least. In fact, both the NAEFS and ENS ensemble guidance suggests
that the mean temperature at H85-5 will approach the 10th percentile
of climatological percentile on Wednesday. Even the EFI (Extreme
Forecast Index) is continuing to suggest increased confidence of
this anomalous event, such that the SoT (Shift of Tails) is greater
than zero.
.LONG TERM...(Thursday through Tuesday)
Issued at 236 PM CDT Tue Jul 4 2023
Thursday...The upper-level trough of low pressure will continue it`s
eastward progression across the Great Lakes region on Thursday. A
shortwave trough will push onshore across northern California and
southern Oregon Thursday afternoon with a deepening low pressure
system to the north across British Columbia. Within the flow aloft,
multiple shortwaves embedded within the mean flow look to eject east
from the Rockies across the Northern Plains come Thursday afternoon.
This will coincide with a surface of low-level moisture from the
Gulf, combining with daytime heating, will result in increased
instability across portions of the Panhandle and western Nebraska.
The environment will be supportive of isolated severe
thunderstorms with the potential for large hail and strong winds.
At this time, the greatest risk area for severe weather is for
areas along and west of Highway 83. However, the risk area will
likely change with subsequent forecasts as models get a better
handle on the environment. In regards to Thursday`s temperatures,
highs will continue to remain anomalously cool for the beginning
of July. Highs will be a few degrees warmer than Wednesday, though
remaining in the 70s across the area.
Friday and beyond...Multiple disturbances embedded within the flow
aloft and surface boundaries tracking across the area will keep the
unsettled weather persisting into early next week. This will result
in sufficient lifting and forcing to support isolated and scattered
shower and thunderstorm chances across much of the area. Confidence
in the severe weather threat and coverage remains low at this time
given variability amongst deterministic and ensemble solutions. Will
continue to monitor this with subsequent forecasts. Temperatures
will gradually warm back into the 80s through the weekend into
early next week, though still remaining at or slightly below
normal for the middle of July. All of this is in agreement with
the CPC 6-10 Day Temperature Outlook favoring below normal
temperatures for the region and the CPC 6-10 Day Precipitation
Outlook favoring above normal precipitation.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 617 PM CDT Tue Jul 4 2023
Will use radar trends to time early precipitation at KLBF, but do
not expect precipitation near KVTN will warrant more than a VCSH.
Expect another round of more substantial showers/thunder at KLBF
closer to Midnight, followed by lingering showers/VCTS through the
overnight and into Wednesday morning, though KVTN looks to be
generally dry. CIGS will remain VFR early though may TEMPO below
VFR if KLBF has a heavier shower go directly overhead. Expect a
trend to MVFR later tonight at KLBF with sub-VFR persisting well
into Wednesday morning. KVTN will hold VFR longer with a period of
sub-VFR conditions around midday Wednesday.
Winds may be a bit gusty to 25kt through this evening, then are
expected to remain generally 10kt or less thereafter. However erratic
gusts are possible near any thunderstorms.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...Viken
SHORT TERM...Viken
LONG TERM...Viken
AVIATION...MBS
Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1040 PM CDT Tue Jul 4 2023
.SHORT TERM... (Through Late Wednesday Night)
Issued at 326 PM CDT Tue Jul 4 2023
Scattered thunderstorms have developed this afternoon in a
largely uncapped atmosphere where MLCAPES are 1000-2500+ J/kg.
While deep layer shear is lacking, the RAP forecast soundings and
SPC mesoanalysis is showing potential for microbursts and hail
this afternoon over southeast Missouri and southwest Illinois.
These storms will eventually diminish by early this evening with
loss of daytime heating.
Water vapor imagery is showing a shortwave trough currently over the
Rockies that will move into the Upper Midwest by late tomorrow. A
MCS is expected to develop over the Plains tonight that repeated
runs of the convective allowing models weaken and move southwest of
the CWA tonight. Lift associated with the trough and weak
convergence with the associated attendant front will be enough to
keep likely PoPS tomorrow. There remains the risk for a few strong
to severe storms over the area tomorrow afternoon/evening given
expected MLCAPES of 1500-2500 J/kg with somewhat marginal deep layer
shear of 30-40 knots. The primary risk will be damaging winds with
large hail also possible.
The chance for showers and thunderstorms will linger into Wednesday
night as the front continues to move southeast and out of the CWA.
Will reflect this with decreasing PoPs for showers and thunderstorms
during the period.
Lows tonight will be near normal and highs tomorrow will show a
contrast with the front with mid 80s over northeast Missouri
compared to lower to mid 90s in St. Louis and areas to the south and
east.
Britt
.LONG TERM... (Thursday through Next Tuesday)
Issued at 326 PM CDT Tue Jul 4 2023
Will hold on to a chance of showers and thunderstorms over the
eastern and southern CWA on Thursday which will remain in close
proximity to the front and within an unstable airmass. Rain chances
will be low as a surface high moves across the area. There is
reasonable agreement between the ensembles that a upper trough will
move from the northern Plains into the Great Lakes Friday night into
Saturday which will bring another cold front through Missouri and
Illinois on Saturday. This is enough to keep high chance or likely
PoPs over much of the CWA this weekend. Will continue with low
chance PoPs into early next week as the ensembles are showing the
upper flow becoming northwesterly by early next week with another
front moving across the area.
Temperatures will fall a bit below normal Thursday into Saturday
with north to easterly surface winds and ensemble 850mb temperatures
will be around 15C. They will climb back to near normal early next
week as 850mb temperatures will climb closer to 20C and surface flow
turns to the south. This is reflected well in the deterministic NBM
temperatures.
Britt
&&
.AVIATION... (For the 06z TAFs through 06z Wednesday Night)
Issued at 1035 PM CDT Tue Jul 4 2023
VFR conditions are expected to prevail over the majority of the TAF
period. Confidence in fog development tonight is waning, but can`t
rule out rain soaked and low-lying areas seeing patchy fog early
Wednesday morning. Otherwise, winds will shift from southerly to
northwesterly as a cold front passes each terminal. This front will
bring the potential for showers and thunderstorms to each terminal
as it passes, with highest confidence in convection impacting KUIN
and the St. Louis metropolitan terminals in the afternoon. KCOU and
KJEF may be missed by this round as convection is likely to initiate
to the east of these sites. Tried to narrow a window for the most
likely time to see showers and thunderstorms at each site, but
timing will likely be tweaked in future issuances.
Jaja
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&
$$
WFO LSX
Area Forecast Discussion
National Weather Service Marquette MI
922 PM EDT Tue Jul 4 2023
.SHORT TERM...(The rest of today and tonight)
Issued at 256 PM EDT TUE JUL 4 2023
Mostly sunny skies dominate the UP early this afternoon. However,
satellite imagery shows a diurnal cu field beginning to develop over
the west ahead of a line of showers and storms currently over NE MN
and western WI. With CAPE values are projected to get above 1000
J/kg across the area this afternoon, we may see some showers and
thunderstorms develop over the western UP and move into the north
central UP late this afternoon into early this evening ahead of the
main line IF the cap around 7 kft is overcome. Given that model
soundings show some dry air in the mid levels, we could see some
gusty/sub-severe damaging winds with these storms. However, with
shearing really lacking ahead of the main line (0-6 km bulk shear is
only around 20 to 25 kts), these storms will likely have a hard time
producing any severe hail, although some small sub-severe hail looks
possible. These storms and showers may pop-up, core dump, weaken,
restrengthen, then core dump again late this afternoon until just
after sunset as there should be enough instability to keep them
going until the sun goes down. As for the main line of storms, we
could see it roll into the west around 8-10 PM EDT this evening. We
could see some strong to possibly marginally severe hail and wind
with this line, particularly in the far west where the kinematics
and instability are better (will have sunlight longer too). As this
line moves east in the central UP, expect it to weaken as it moves
into more stable air. Now, one thing worth mentioning, though, is
that the most recent HRRR model has the line being much weaker than
anticipated; it even shows the line not arriving into the UP
until late tonight. Will need to keep an eye on this development
as this could pretty much get rid of any severe weather chances
this evening/tonight. Behind the line of storms, expect scattered
showers and storms to traverse the UP.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 303 PM EDT TUE JUL 4 2023
By 18Z Wednesday, the cold front will already have proceeded to be
draped across the south-central to eastern UP. Recent NAM runs had
the cold front position at 18Z as far west as Ironwood, so this
faster frontal progression will leave much of the west half with
lesser precip than previously forecast. It is still probable that
the east half sees half an inch to an inch of rain given the lift
from the surface front, impulse shortwaves in the 500mb layer, and
jet layer divergence from an approximately 110 kt jet over northern
Ontario and the prevalence of moisture as PWATs are as high as 1.5
inches and NAEFS climo percentiles for vapor transport, humidity,
and PWAT are all in the 90th percentile. However, with even
1-hour flash flood guidance well in excess of an inch for most of
the UP, flash flooding will likely not be a concern as training
storms are not expected and the soils are unlikely to be primed
from today`s convection affecting the west half.
Abnormally cool temperatures follow in the wake of the cold fropa,
with highs only in the 60s and 70s Thursday. A surface high
pressure in the high 1010s mb will advance over the Upper Great
Lakes, leaving dry weather for Thursday afternoon through Friday
evening. As the main 500mb trough stalls over the Hudson Bay, even
retrograding some, quick shortwave trough/ridge successions will
characterize the weather for the weekend and beyond. To give an
idea of how quickly these shortwaves are passing, the 12Z GFS
shows shortwave tropa Saturday afternoon, Sunday evening, Monday
morning, Tuesday evening, Wednesday afternoon, and Friday morning.
The ensembles show even more variability in when each trough
passes and at what intensity, so confidence in the details is a
bit low. Not all of these troughs will support precipitation and
there is not much signal in any of the ensembles that any of the
rain will be particularly intense, but most members of the
ensembles show the UP ending up with 1-2 inches of total precip by
the end of next week. Ensemble surface temperature anomaly
analysis shows that temperatures are expected to be below normal
to near normal next week, with NBM high temperatures being
confined to the 70s for the most part. &&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 845 PM EDT TUE JUL 4 2023
The early evening showers and t-storms have moved east and there
should be a period of quiet weather through the rest of the
evening hours. CMX will have lowered conditions to IFR/LIFR in
stratus/fog at times into the overnight hours. IWD could see some
showers/t-storms and MVFR cigs move in 04-06Z with the approach
of the cold front from the west, CMX should see some isolated
showers and MVFR/IFR conditions develop around 09Z and SAW will
see showers/isolated t-storms and MVFR conditions develop around
12Z. As the cold front gradually shifts e through the day, the
threat of showers/isolated t-storms will be confined to SAW.
Expect improvement to VFR behind the front by 18Z at IWD and CMX
and by 21Z at SAW.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 303 PM EDT TUE JUL 4 2023
With weak pressure gradients for much of the CONUS and Canada east
of the Rockies, winds will remain below 20 knots for the entire
forecast period. The highest winds will be following a cold front on
Wednesday into Thursday, where wind gusts may briefly exceed 20
knots in some areas of Lake Superior, especially on elevated
platforms. Chances for scattered thunderstorms return to western
Lake Superior this evening, and some isolated convection may be able
to reach central and eastern Lake Superior overnight. Strong to
severe storms are possible in western Lake Superior this afternoon
and evening. The cold front slowly passing through Wednesday will
touch off a next round of showers and storms in western Lake
Superior early in the morning, spreading eastward the rest of the
day before exiting east into the night. Some patchy dense fog is
currently over the lake, and the additional moisture provided by the
showers and thunderstorms may allow for further fog development into
the late week period.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...TAP
LONG TERM...GS
AVIATION...Voss
MARINE...GS
Area Forecast Discussion
National Weather Service Pocatello ID
200 PM MDT Tue Jul 4 2023
.SHORT TERM...Tonight through Wednesday night. Early afternoon
satellite imagery was showing a low pressure center across CNTRL
Canada with the trough axis extending southwestward into ERN
Montana. Rotating through this axis across SE Montana was a fairly
well defined disturbance and associated backdoor frontal boundary
settling over SE Idaho where we were seeing NE winds satisfying Lake
Wind criteria across American Falls Reservoir. Hires models suggest
that these winds will begin to diminish by mid-afternoon. Further
west, the models were showing a secondary disturbance rotating
through the SRN Panhandle into the SW Montana border area late this
afternoon/early this evening. This feature was not clearly evident
on satellite imagery but there does appear to some fairly strong
subsidence going on across ERN Oregon in the SW quadrant of a faint
circulation working through the Salmon area. It is this feature that
the models key on, producing isolated to scattered thunderstorms
across the upper valley and Montana border region later this
afternoon and evening. Jet support appears to be a bit lacking so
there isn`t any real expectation of severe activity but with dry
lower levels, the models are highlighting the potential for
impressive outflow boundaries from the convection across the upper
valley. Windex values are only peaking around 35-40kts...so again,
not really in the severe category but something to watch
nonetheless. By Wednesday, the Canadian low pushes further east
while a mostly dry and stable WNW flow develops across SE Idaho. An
area of instability and moisture lingers from Galena Summit to
Dillon MT Wednesday afternoon/evening but not enough for any of the
models to bite off on any thunderstorm activity at this time. Also,
the surface pressure gradient continues to support downvalley flow
through the morning hours with afternoon mixing bringing light
southwest flow. Nothing strong enough here to suggest a need for any
Lake Wind highlights. Daytime temperatures begin to recover a little
with the southwest winds Wednesday afternoon. Huston
.LONG TERM...Thursday through next Tuesday.
With an area of low pressure situated off the British Columbia Coast
and two areas of high pressure centered over the Desert SW and ERN
Alaska for Thursday, isolated chances for afternoon showers and
thunderstorms return as we enter a slight warming trend each day
through the weekend. Best chances for storms on Thursday will remain
confined to the CNTRL Mountains, along the Continental Divide, and
South Hills region with afternoon highs in the 70s to low 90s. Gone
ahead and Increased POPs over the NBM to account for a better
precipitation consensus on the GFS and ECMWF. As that WRN Canadian
low tracks south for Friday and Saturday closer to Washington,
chances for precipitation increase in coverage for the CNTRL
Mountains and along the Idaho/Wyoming border region. Those two
aforementioned areas of high pressure are favored to strengthen
starting Sunday eventually combining as the ridge axis now extending
well into NRN Canada supports a return to drier and even warmer
conditions. Coverage of afternoon highs in the mid 90s will increase
for the Sunday through Tuesday period across the Snake Plain as
conditions remain dry with highs in the mountain valleys in the 80s
to low 90s. Zonal flow returns midweek next week keeping conditions
predominantly dry as moisture remains confined north of our area.
MacKay
&&
.AVIATION...For the 18Z TAFS through 18Z Wednesday.
Predominant VFR and SKC conditions continue across SE Idaho as a
shortwave trough descending through SW Montana brings increased
clouds and isolated showers and thunderstorms across the ERN CNTRL
Mountains and Upper Snake Plain. KPIH and KIDA will maintain a
downvalley flow component throughout the day with gusts to around 20
to 25 kts as other terminals follow typical diurnal patterns. Best
chances for thunderstorms will be from the Lost River Range to
Continental Divide late this afternoon shifting SE as isolated
chances for showers with occasional embedded lightning work SE
through the evening hours. Have maintained dry conditions outside of
VCSH at KIDA and KDIJ to account for lingering energy from the
shortwave working into Wyoming by late this evening. Stronger
thunderstorm outflow boundaries will support gusts in excess of 25
kts particularly between 0/4Z at KPIH, KIDA, and KDIJ. SKC and
lighter winds return tonight with dry conditions outside of a
isolated chances along the Continental Divide and clear skies
expected for Wednesday. The HRRR Smoke model also maintains light
smoke concentrations over SE Idaho into tomorrow associated with
Canadian wildfire smoke with limited impacts expected. MacKay
&&
.FIRE WEATHER...Temperatures are noticeably cooler for Independence
Day behind the cold front that moved through yesterday with another
shortwave trough working through SW Montana today supporting
isolated chances for showers and thunderstorms across the CNTRL
Mountains and Upper Snake Plain. Best chances for stronger
thunderstorms will be across FWZ 410 and 476 where outflow wind
gusts could exceed 35 mph. Outside of convective based winds,
downvalley winds have been slightly breezy across the Snake Plain
with gusts to around 20 to 30 mph with quieter winds favored to
return overnight regionwide as the trough works into Wyoming for
Wednesday. The HRRR Smoke model also maintains light smoke
concentrations over SE Idaho into tomorrow associated with Canadian
wildfire smoke with limited impacts expected.
Transitory zonal flow will keep conditions dry tomorrow with near
critical afternoon humidities across FWZ 425 and 427 with non-
critical winds. There could be a very isolated storm or two in the
CNTRL Mountains tomorrow but conditions will remain predominantly
dry. Our next shortwave trough works south for Thursday with
isolated showers and thunderstorms in the mountains as temperatures
begin to see a slight warming trend each day through the weekend as
high pressure intensifies to the south. Friday and Saturday will
look much the same to Thursday with isolated to scattered showers
and thunderstorms in the afternoon hours mostly confined to the
mountains north and east of the Snake Plain. That now amplified
ridge of high pressure takes control of the weather pattern starting
Sunday through early next week as afternoon highs return to the 80s
to mid 90s across the valleys with increasing coverage of near
critical to critical afternoon humidities outside of FWZ 411. MacKay
&&
.PIH WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Area Forecast Discussion
National Weather Service Pueblo CO
818 PM MDT Tue Jul 4 2023
.UPDATE...
Issued at 813 PM MDT Tue Jul 4 2023
Have canceled the severe thunderstorm watch for the entire area.
Still a risk of an isolated/weak storm over the southeast plains
and along the Palmer Divide through the evening, along with a few
sprinkles over the higher terrain, though overall, storm chances
for many areas have ended for the evening.
&&
.SHORT TERM...(This evening through Wednesday)
Issued at 349 PM MDT Tue Jul 4 2023
Key messages:
1) The Potential of severe storms will be over the eastern plains
through the early evening hours. A few showers and storms could be
possible elsewhere, but everything should diminish by around 9 PM or
shortly thereafter.
2) Low clouds will fill in over the plains throughout the night and
there could be some areas of patchy fog developing over the Palmer
Divide area during the early morning hours.
3) Strong to severe storms will be possible again tomorrow over the
plains during the late afternoon hours and through the evening.
4) Notably cooler tomorrow over the plains with temperatures being
in the upper 60s and 70s, and around 15 degrees below the seasonal
average.
Detailed discussion:
Currently and through tonight...
The major shortwave trough that is propagating over north-central
CONUS and an associated low pressure system to the northeast is
currently forcing a cold frontal boundary through the CWA. As the
boundary continues to push southward, the cold pool will advect in
higher dewpoints over 50 degrees, yet there will also be increase
convective inhibition (CIN) as well and therefore the lower levels
may become too stable for additional storms to materialize behind
the front. Ahead of it, as the front moves through the eastern
plains, with increasing CAPE and shear later this evening of values
of 2000 J/kg or greater, along with higher dewpoints with southerly
winds may cause storms to develop and become severe if the the
convective temperature breaks the cap. This looks to be mainly north
of Highway 50, over eastern Kiowa County where the potential of
severe storms will be, although the NAMNest has been consistent with
some storms forming further south over Prowers and Baca counties.
The HRRR now also shows there being a line of storms forming along
the Bent/Prowers and Las Animas/Baca county lines and then becoming
a line echo wave pattern (LEWP) as storms merge and move eastward
into Kansas. A stronger or severe storm could also develop over the
Lamar area later in this evening, right along the theta-e axis.
Hodographs are still relatively straight-lined and therefore the
storms will have a possibility of splitting and continue to be
mainly wind and hail producers. If the LEWP does come to fruition,
this could also pose a strong straight-line wind threat over the far
eastern plains to the CO/KS border. Over the rest of the CWA will
exist the chance of showers and possibly a very isolated
thunderstorm through the rest of the evening, although with the
lower levels much more stabilized, confidence is low of any storm
becoming strong. Showers should continue to dissipate, especially
after 9 PM. Skies will continue to clear over the higher terrain and
low stratus will form and fill over the plains through the night,
there could also be some areas of patchy fog over the Palmer Divide
as soundings show saturation occurring all the way down to the
surface by the early morning hours tomorrow. Lows will drop into the
upper 50s to low 60s over the plains, and in the 48s and 50s for
high country.
Tomorrow...
The easterly low-level flow over the plains is going to continue to
advect in cooler and more saturated air with dewpoints in the 50s
banking up against the southeastern mountains and Pikes Peak/Rampart
Range. This will allow for the plains to become conditionally
unstable with a "classic day 2" setup in place as belt of CAPE
develops along the I-25 corridor with values shooting up above 2000
J/kg for some areas over the southern part. The challenge will be
how long the low levels stick around in the morning hours depending
on how long it takes for them to mix out that will determine if
things become unstable enough to support intensification of storms
as they move over. If it clears out enough, then the convective
temperature could break the cap over some locations of the plains
and result in rapid intensification of thunderstorms as they move
over and could become severe. However, most locations could remain
too capped over the plains.
Storms will initially develop over the eastern mountains, but there
could also be some storms developing over the central mountains and
perhaps a few storms over the southwest mountains that move over
into the San Luis Valley, although the environment looks to be much
less favorable over these areas. Another contributing factor to
storms rapidly intensifying over the plains will be very strong
effective bulk shear of up to 60 kts over southern portions of the
Sangre de Cristo Mountains and downwind over the southern I-25
corridor. Right now, most CAMs are showing this area, near the Raton
Mesa and eastward over Las Animas and Baca counties with having the
best chance of stronger updraft development, which makes sense since
this area is the most conditionally unstable. There could also be
stronger storms that form and move off the Pike`s Peak area and over
Colorado Springs. With inverted V soundings and relatively high
DCAPE values, if a storm does become severe over the plains, the
main threat will be gusty outflow winds. There could also be some
large hail, possibly up to 2 inches in diameter over the southern I-
25 corridor and southeastern plains. It will be notably cooler over
the plains, around 15 degrees below the seasonal average, with the
easterly flow in place. Although for the higher terrain, highs will
top out at or even slightly above the seasonal average where
northwesterly flow dominates. -Stewey
.LONG TERM...(Wednesday night through Tuesday)
Issued at 349 PM MDT Tue Jul 4 2023
Wednesday night-Friday night...Models continue to indicate minor
waves embedded within moderate westerly flow aloft across the
Intermountain West through the Northern High Plains through the end
of the work, as upper level high pressure builds across the Southern
High Plains through the Southern Rockies and into the Desert
Southwest. This will keep generally dry, warm and breezy conditions
across western portions of the area through this period, with
meteorological critical fire conditions likely through the afternoon
and evenings. The latest fuel status from land management agencies
remains non critical, however, will need to continue to monitor as
said warm and breezy conditions prevail. Further east, we will
continue to see daily chances of showers and storms, with severe
weather possible, as low level moisture ebbs and flows across the
southeast Plains. SPC has the southeast plains in a marginal to
slight risk of severe storms on Thursday, with similar conditions
expected on Friday. Temperatures across western portions of the area
to be at to slightly above seasonal levels through the period, with
near to below seasonal temperatures expected across eastern
Colorado.
Saturday-Tuesday...The upper high remains progged to build across
the Great Basin and into central Rockies through the weekend,
leading to a warming and drying trend areawide. The ridge over the
Rockies flattens again into early next week, leading to a slow
increase in available moisture and increasing chances of showers
and storms, especially across eastern Colorado.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 349 PM MDT Tue Jul 4 2023
VFR conditions are expected to prevail for KALS throughout the
forecast period. At KCOS and KPUB, VFR conditions are expected to
persist for the most part until around 01Z at KCOS and 07Z at KPUB,
then will deteriorate to IFR and possibly LIFR criteria as low CIGs
move in, along with reduced VIS in BR and remain that way until
around 15Z, then CIGs should begin to lift back to at least MVFR
criteria, but could still be IFR criteria at times. SHRA and
possibly TSRA may still be in the vicinity of KCOS and KPUB through
the rest of the evening until around 05Z at KCOS and 07Z at KPUB.
SHRA and TSRA are expected to be in and around the vicinity of KCOS
and KPUB, and possibly KALS in the afternoon tomorrow, primarily
after 18Z and for the rest of the forecast period. VCTS was left out
the TAF for KALS due to there being lesser confidence of this
occurring at this station. If SHRA/TSRA does develop, it could
temporarily reduce CIGs and VIS to MVFR/IFR criteria at any one of
the stations later this afternoon/evening. It could also result in
periodic windshifts and increased wind speeds at for all terminals.
Winds will be synoptically influenced at all terminals due to a
disturbance moving over Colorado. NE`ly winds will continue at both
KCOS and KPUB, where there could be gusts as high as 25 kts, then
they will continue to veer towards the E-ESE by tomorrow morning and
remain that way through tomorrow. At KALS, winds will be
predominantly out of the SW this afternoon and gust as high as 22
kts this evening, then begin to become more diurnally influenced as
they weaken tonight and increase again and become gusty out of the
SW by late tomorrow morning, towards the end of the forecast period.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...PETERSEN
SHORT TERM...STEWARD
LONG TERM...MW
AVIATION...STEWARD
Area Forecast Discussion
National Weather Service Seattle WA
852 PM PDT Tue Jul 4 2023
.UPDATE...No changes have been made to the forecast. Above average
warmth and dry weather will continue the threat for elevated fire
weather concerns here in the short-term forecast. The previous
discussion remains below along with an updated marine/aviation
section.
&&
.SYNOPSIS...Dry and warm conditions continue across Western
Washington as high pressure remains over the region, maintaining
heightened fire weather concerns. Temperatures peak across
interior areas Wednesday before cooling to near normal this
weekend as a weak upper trough arrives. Dry conditions will
prevail except for a chance of showers and thunderstorms across
the North Cascades with the upper trough late this week.
&&
.SHORT TERM /TONIGHT THROUGH FRIDAY/...Warm and dry conditions
continue across Western Washington this 4th of July afternoon as
the region remains on the periphery of a strong upper ridge
centered offshore. The low level flow is weakly
offshore...allowing even coastal sites to warm into the lower 80s
as of midday. The thermally induced surface trough responsible for
this will begin to shift inland this afternoon...allowing a sea
breeze to cool the immediate coastline. As for interior areas,
well above normal temperatures continue with locations away from
the water reaching the 80s to lower 90s. Skies will remain hazy
into this evening as smoke aloft drifts down from Canada.
The surface thermal trough will remain in place over the Puget
Sound lowlands on Wednesday with temperatures rising another
degree or two over todays readings. The coast will be noticeably
cooler on Wednesday...likely by some 10 to 20 degrees. HRRR
integrated smoke runs show the smoke beginning to thin somewhat on
Wednesday as northwesterly flow aloft gives it a nudge eastward.
A weak ripple in the aforementioned northwest flow aloft may
trigger some elevated convection near the crest of the North
Cascades, but, as of this writing, the better potential will be
eastward. As the thermal trough shifts toward the Cascades
Wednesday evening, this will initiate a bit more of a shallow
marine push. This will bring a more solid marine layer to coastal
areas on Thursday morning and perhaps extending at least part way
inland. This will also herald further cooling for the coast and
knock around 10 degrees off Thursdays high temperatures for much
of the interior. Fire weather concerns (discussed below) will
begin to ease as the seepage of marine air brings better RH
recoveries.
A weak upper trough will begin to settle southward from British
Columbia on Friday with temperatures dropping back to near
seasonal norms and morning clouds likely for most of the lowlands.
The arrival of the trough will also bring some instability to the
North Cascades with daytime heating for a slight chance of
thunder.
.LONG TERM /SATURDAY THROUGH TUESDAY/...A mean upper trough will
settle over the region this weekend. Dry conditions will prevail
with the exception of some Cascade convection and temperatures
will be near normal. Ensembles hint at some weak upper troughing
remaining just offshore early next week, but 500 millibar heights
over the area look to remain the vicinity of 580 dam with light
onshore flow. This points toward temperatures a little above
normal and continuing dry conditions. 27
&&
.AVIATION...Northwesterly flow aloft becoming northerly Wednesday
afternoon as a weak upper level trough moves over the area. In the
lower levels thermally induced trough over the area will shift
inland Wednesday with increasing onshore flow along the coast.
Just some high clouds and smoke aloft through Wednesday.
KSEA...A few high clouds at times. Northerly wind 4 to 8 knots
increasing to around 10 knots Wednesday afternoon. Felton
&&
.MARINE...Surface high pressure will persist well offshore over
the next several days. A thermally induced surface trough over the
waters will shift inland Wednesday with increasing onshore flow
along the coast. North to northwesterly winds will persist for the
majority of the area waters, with winds expected to increase
across the Coastal Waters tonight. Strongest winds look to be over
the outer waters from 10-60NM offshore, where a Small Craft
Advisory remains in effect. Stronger onshore flow will return
Wednesday night and then again Thursday night, with marine pushes
likely bringing a strong push of westerly winds down the Strait of
Juan de Fuca. Additional headlines look likely, with guidance
indicating the potential for gales along the central and eastern
portions of the Strait Thursday night into Friday.
Seas across the coastal waters continue to hover at about 5-7
feet into Wednesday, before building to 6-9 feet by Thursday.
Seas may be steep at times over the next several days. Seas then
look to subside down to 3-5 feet over the weekend. 14/Felton
&&
.FIRE WEATHER...Elevated to critical fire weather conditions
continue today with the warm, dry, and unstable conditions across
the region. The Red Flag Warning continues for zones 655 (Black
Hills/Chehalis River Valley) and 659 (West Slopes of the Central
Cascades) and RHs continue to dip toward/into the critical
thresholds. Expect daytime humidities to bottom out generally in the
15 to 20 percent range throughout these zones, along with mid-level
Haines 6. Despite some decent recovery overnight, a repeat of
conditions is expected again tomorrow, from the eastern part of 655
and through 659, and so no changes to the current RFW timing. It`s
also worth noting that while only these zones are expected to see
critical conditions develop, elevated fire weather conditions will
continue in several other zones - particularly, 657 and 658.
Furthermore, afternoon and evening winds will likely be breezy but
short of wind criteria.
Thus, both Tuesday and Wednesday will be the days of primary concern
this week. Two zones that aren`t included in the warning but still
with elevated concern are the northern Cascades [zone 659] (where a
passing disturbance will likely boost RHs) and zone 657 where
humidities will likely approach critical thresholds. These will
continue to be evaluated for potential inclusion on Wednesday, but
the expected good humidity recovery is also a mitigating factor in
657. There is some potential (around a 15-20%) chance of an isolated
thunderstorm late tomorrow afternoon in the far North Cascades, but
even if one develops the lightning coverage is expected to be
minimal/isolated at best.
Looking ahead to Thursday, the strengthening of onshore flow may
lead to cooler and more humid air reaching far western portions of
655. However, another warm and dry day is likely for many areas to
the east into the foothills and Cascades. At this point, enough
boost in humidity is likely to preclude a third day of critical
conditions but will need to closely monitor this trend. By Friday,
cooler and more humid air then arrives more fully through the
region, ending this round of concern. A few isolated thunderstorms
may develop over the Cascades over the weekend each afternoon and
evening.
Cullen
&&
.HYDROLOGY...The daily hydrology discussion has ended until the
start of the next rainy season; it will only be updated as needed.
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...Red Flag Warning until 7 PM PDT Wednesday for Black Hills and
Southwest Interior Lowlands-West Slopes of the Central
Cascades Generally above 1500 Feet.
PZ...Small Craft Advisory until 5 AM PDT Thursday for Coastal Waters
From Cape Flattery To James Island 10 To 60 Nm-Coastal
Waters From James Island To Point Grenville 10 To 60 Nm-
Coastal Waters From Point Grenville To Cape Shoalwater 10
To 60 Nm.
&&
$$
Area Forecast Discussion
National Weather Service Springfield MO
619 PM CDT Tue Jul 4 2023
Key Messages:
1. Scattered showers and thunderstorms this afternoon and
evening, mainly east of Highway 65 corridor.
2. Potential thunderstorm complex moving into the area late
tonight into Wednesday morning.
3. Redevelopment of strong to severe storms over the area ahead of
a cold front Wednesday afternoon and evening.
4. Daily shower and thunderstorm chances from Thursday through
Tuesday.
.SHORT TERM...(This evening through Wednesday)
Issued at 200 PM CDT Tue Jul 4 2023
Temperatures have warmed into the upper 80s to mid 90s across the
area with a decent cumulus field and some scattered storms in our
eastern CWA. Surface based CAPES in that area have risen to around
1500 j/kg in an environment with little to no shear. While we are
not expecting any severe storms with this activity, some stronger
storms may produce some small hail and wind gusts up to 50 mph. PW
values of 1.3 to 1.5 in and slow moving convection will also cause
heavy rain and possibly some localized flooding to occur.
An upper level low over Montana and associated trough that
extended southward into the Rockies is expected to shift eastward
the remainder of today and tonight. This upper wave will help to
kick a surface cold front southeast into the plains and eventually
our western CWA late tonight into Wednesday. As a low level jet
begins to develop this evening, strong to severe thunderstorms are
expected near the front from the central plains into the upper
Mississippi valley. Many of the CAMS are bringing some semblance
of the MCS that develops into our area late tonight into Wednesday
morning. How it evolves from there will be the biggest question
and how much redevelopment will occur later in the day if it holds
together. Many of the models start to decay the MCS in the morning
with better chances at redevelopment later in the afternoon and
evening. The HRRR mainly plows it right through throughout the
morning into the early afternoon with lesser redevelopment later
in the day. We have decided to up our pops in the morning a bit
and keep the higher pops in the afternoon and evening for now and
play the waiting game to see how this evolves this
evening/tonight.
The scenarios will also have an impact on temperatures for
Wednesday. An MCS that moves through will likely keep temperatures
down a bit. We are continuing with low to mid 90s for highs for
now with heat index values from around 98 to 103.
.LONG TERM...(Wednesday Night through Tuesday)
Issued at 200 PM CDT Tue Jul 4 2023
A zonal pattern aloft will set up over the area with the cold
front stalling out just to our south. Several waves of energy will
push through from Thursday through early next week bringing daily
thunderstorm chances. High PW values will continue to support
heavy rain through the long term period and we may see some
localized areas of flooding with stronger convection.
Temperatures will be cooler initially behind the front through
Saturday, but a warming trend towards more normal temperatures by
late in the weekend into early next week with an upper ridge
starting to build to our southwest.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 613 PM CDT Tue Jul 4 2023
Shower and storm activity across the region should diminish by
this evening. A few lingering clouds may remain bur VFR conditions
are expected.
A thunderstorm complex may develop out in the plains and push
into the area late tonight into Wednesday morning. Though confidence
is low at this time in the models, have opted for PROB30 groups
for overnight into the day Wednesday. If the complex develops, may
need to introduce more coverage and confidence with Tempo or
prevailing conditions. Watch for later forecasts as trends become
more clear.
&&
.SGF WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&
$$
SHORT TERM...Lindenberg
LONG TERM...Lindenberg
AVIATION...Hatch
...Update to aviation forecast discussion...
.DISCUSSION...
Issued at 238 PM CDT Tue Jul 4 2023
Key Points:
- Hot Fourth of July with Severe Weather possible this evening and
overnight
- Cool temperatures expected for the remainder of the week with a
warming trend by the weekend.
- Overnight rain chances will be something to watch Thursday into
Friday and Saturday morning. Some storms could be strong to severe.
Taking a look at afternoon water vapor imagery, a closed low is
still situated over central Canada with a trough axis extending
southwestward, weak ridging over the desert Southwest, and a few
shortwaves embedded in zonal flow over the central Plains. Clear
skies and southerly flow have warmed temperatures quickly across
northeastern Kansas with mid 90s common area-wide by 1 PM. Continued
WAA, afternoon mixing, and warm 850/700mb temperatures will continue
to push afternoon high temperatures into the upper 90s and low 100s.
Luckily, surface moisture is fairly shallow and dewpoints are
staying in the low to mid 60s keeping heat indicies just below Heat
Advisory criteria. That said, with the holiday, heat could quickly
cause issues for people that are susceptible, so make sure to find
shade and drink plenty of hydrating fluids this afternoon.
The main focus in addition to the heat will be evening and overnight
strong/severe thunderstorms along a southeast-moving frontal
boundary. Currently, mid-level vorticity maximums advecting east off
the Rockies are providing sufficient support for convection over the
high plains and along a surface trough axis draped across central
Nebraska. This will be the main focal point for strong to severe
storms in northeastern Kansas later this evening and overnight. By
this evening, convection along the frontal boundary will continue
southeast, growing upscale quickly. Deep shear across Nebraska this
afternoon appears much more supportive of organized convection as
guidance keeps only 25-35 knots of shear along the boundary as it
moves into the northern Kansas. The marginal shear should not be
much of a deterrent for convection as lapse rates will be 7.5-8
degrees in the mid-levels with 2500 J/kg of MUCAPE ahead of the
frontal boundary. That said, RAP convective parameters show the best
area for the strongest and most organized convection to be in north-
central and central Kansas before the line of convection outruns
shortwave energy to its north. Storms will be capable of producing
damaging winds and occasional large hail. CAMs have come more into
agreement with the timing of the line as well with convection making
its way into north-central Kansas between 7-9 PM, I-70 by around
midnight, and east-central Kansas by 2-5 AM Wednesday morning. Heavy
rain will also be a concern as well as PWATs will be high (1.5-2")
and training rain and storms behind the boundary will remain
possible.
By around sunrise Wednesday, the surface boundary should be south of
the area. PoPs remain elevated through much of the day Wednesday as
the the 850 front stalls over the area. Expecting only rain and a
few elevated storms, but with cloud cover and CAA behind the
boundary, instability will not be very impressive for strong storms.
High temperatures should be much more pleasant and in the low 80s.
By the late afternoon, CAMs depict convection to redevelop along the
stalled frontal boundary along the OK/KS border. With very large
CAPE values and increasing upper level support from an approaching
mid-level perturbation, a few of these storms could become severe
with damaging winds, and large hail being the main concern. At the
moment, most of the convection appears to stay south of the area
where better instability resides, but cannot rule out a storm or two
south of the Kansas Turnpike.
Surface ridging builds further into the area Thursday, resulting in
mostly dry weather with highs in the low to mid 80s. It is not until
Thursday evening and into Friday morning that low-level flow returns
from the south and begins to bring warm and moisture-rich air back.
A few mid-level vorticity maximums move across the central Plains
early Friday AM with an increasing LLJ. Increasing deep shear to
40-50 knots overhead with elevated instability could result in
elevated supercells capable of large hail and damaging winds
Friday AM. Guidance appears to keep the bullseye for QPF over
central Kansas, but the exact location of the QPF will continue to
be monitored over the coming forecast periods. Regardless,
continued heavy rainfall over areas that will have received a good
rainfall the previous days could lead to localized flooding. A
similar setup overnight into Saturday AM will be possible with
heavy rainfall again a concern across central and east-central
Kansas.
By Sunday and into next week, temperatures warm up closer to the
climate average as weak upper-level ridging slides east.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 633 PM CDT Tue Jul 4 2023
The main hazard for the period will be with storms that move into
the area later this evening into the overnight period. Winds will
be the main hazard for aviation. Have tried to indicate the time
frame with a TEMPO group. This could be changed if the line of
storms developing over north central into eastern Nebraska gain
forward speed and arrive earlier than currently forecast. Showers
linger into the morning and eventual clearing takes place by late
morning into midday with the next risk of storms near the end of
the period.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
DISCUSSION...Griesemer
AVIATION...Drake
Area Forecast Discussion
National Weather Service Tulsa OK
919 PM CDT Tue Jul 4 2023
...New SHORT TERM...
.SHORT TERM...
(The rest of tonight)
Issued at 919 PM CDT Tue Jul 4 2023
Isolated convection across WC AR has dissipated as of mid
evening. Focus now turns to convection along a cold front
currently across northern sections of Kansas. This convection
will move off the boundary and move southeast towards NE OK later
tonight. Latest HRRR runs have supported a stronger signal moving
into the area in the 08z-09z timeframe before dissipating between
12z-15z. Have raised PoPs across NE OK/NW AR after 09z to the
likely/chance categories. Have also broadened a lower chance PoP
between 12z-15z in the same area. Have upped sky coverage as well
across NE OK/NW AR. Temperatures look reasonable for the overnight
period and will leave as is. Remainder of first period element
look good as well.
Updated ZFP/PFM/AFM out shortly.
&&
.LONG TERM...
(Tonight through Tuesday)
Issued at 145 PM CDT Tue Jul 4 2023
Northwest flow aloft remains in place tonight. Current CAM guidance
brings another MCS north of the area overnight, but its southern
end may (20-30% chance) clip far northeast OK and northwest AR,
bringing brief heavy rain and gusty winds to these areas.
Beginning Wednesday, a few adjustments to the pattern will take
place, leading to a more active weather pattern. Flat upper level
ridging will nudge into the Desert Southwest. At the same time,
troughing will intensify across the central-northern Great Plains.
This will extend the subtropical jet from the Pacific into the
region, resulting in anomalous mid level northwesterly flow for
this time of year. Meanwhile, solid low level southerly flow will
transport deep moisture into the lower levels. In fact, the EPS
climatology shows that moisture in the 925-850 hPa layer will be
in the 90th-99th percentile for the second half of this week. The
EPS EFI value for CAPE-shear of 0.6 to 0.7 is also highlighting
the somewhat unusual nature of this pattern. These factors will
promote the potential for multiple MCSs to move through the area,
especially north of I-40.
Looking at the day-by-day, a cold front will slide into KS during
the day Wednesday. Model guidance shows widespread convection ahead
of the front. With ample moisture/instability and sufficient shear
strong to severe storms could develop. Additional storms, some of
which could be strong, may develop overnight as the cold front
moves through the area. Assuming this timing and progression, this
could mean a bit more of a down day Thursday. Even so, south to
southeasterly flow will quickly become reestablished on Thursday,
increasing the low level moisture, temperature, and instability
once again. Robust northwest flow will then allow for several
rounds of storms into the weekend, the timing and intensity of
which is impossible to pin down at this stage. However,
climatology would suggest the evening through the early morning
hours being the preferred window of activity. Additionally, the
areas of heavy rain will tend to move around a bit, and likely not
train over the exact same areas every day.
Moving into next week, the ridge will gradually flex northwards over
the Desert Southwest, slowly forcing the ridge to the north.
Ensemble cluster analysis reveals that about 60% of ensemble
guidance keeps the jet close enough that PoPs would not go to
zero, but a shift towards drier and hotter weather is likely next
week in either scenario. Undercut NBM temperature guidance given
its propensity to overzealously increase temperatures in this
pattern. Regardless, potentially dangerously high heat indices
would likely follow given the recent rains.
&&
.AVIATION...
(00Z TAFS)
Issued at 633 PM CDT Tue Jul 4 2023
Mainly VFR conditions will prevail through the forecast period. A
thunderstorm complex may move into parts of northeast Oklahoma and
northwest Arkansas late tonight into Wednesday morning. In
addition, thunderstorms may form late Wednesday afternoon near a
cold front moving into northeast Oklahoma.
&&
.PRELIMINARY POINT TEMPS/POPS...
TUL 74 95 69 84 / 20 30 60 40
FSM 74 96 72 88 / 20 30 30 50
MLC 74 96 71 86 / 10 20 30 50
BVO 70 92 66 83 / 30 30 60 40
FYV 70 92 67 83 / 30 40 50 50
BYV 70 91 67 82 / 30 50 50 60
MKO 72 94 69 84 / 20 30 40 40
MIO 72 92 67 83 / 60 40 60 40
F10 72 94 70 83 / 10 20 40 40
HHW 72 95 72 90 / 10 10 20 40
&&
.TSA WATCHES/WARNINGS/ADVISORIES...
OK...None.
AR...None.
&&
$$
SHORT TERM...23
LONG TERM....06
AVIATION...05