Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/03/24
Area Forecast Discussion
National Weather Service La Crosse WI
1000 PM CDT Mon Sep 2 2024
.KEY MESSAGES...
- Dry & seasonable conditions are expected through the middle of
the week with high temperatures in the 70s to lower 80s
- Rain returns on Thursday with the highest chances (40-60%)
being along and north of I-94. Some lingering showers will be
possible (15-20% chance) for Friday.
- Unseasonably cool Friday and into the weekend with
temperatures 10 to 15 degrees below average. Low temperatures
on Sunday morning may fall into the 30s for portions of west-
central Wisconsin.
&&
.DISCUSSION...
Issued at 230 PM CDT Mon Sep 2 2024
Rest of Today - Wednesday: Dry, Slight Warming Trend
GOES-16 water vapor imagery and 02.14z RAP 500mb heights show the
general picture of our synoptic setup today with a trough situated
to the east and a upper-level ridge positioned to our west,
subjecting our region to northwest flow. Consequently, conditions
will remain fairly similar to yesterday with surface high pressure
slowly moving to the east with high temperatures in the 70s and
minimal sky cover. As we head towards the middle of the week, the
eastward progression of the aforementioned upper-level ridge will
aid in moving surface high pressure eastbound subsequently
tightening the surface pressure gradient over our region. As a
result, expecting breezy conditions with winds increasing to around
10-20 mph during the afternoon hours on Tuesday and Wednesday.
Slightly higher gusts will be possible across unsheltered portions
of southeast MN/northeast IA.
Additionally, with the upper-level ridge moving westward and
flattening as it approaches the region, expecting a subtle warming
of temperatures into Wednesday with highs reaching into the upper
70s and lower 80s. Sky cover will remain relatively clear with weak
subsidence in the overall ridging pattern. However, given the 02.12z
HRRR Vertically-integrated smoke fields moving smoke in aloft by
Tuesday morning and into Wednesday, hazy skies appear likely with
little indication of any smoke becoming surface based.
Thursday: Rain Returns, Highest Chances North of I-94
Looking into Thursday, a broad 500mb trough will swing out of
Central Canada into the Upper Midwest, dragging a surface cold front
along with it. As a result, lift with the overall system combined
with precipitable waters across the 02.12z grand ensemble (GEFS/EC
ensemble/Canadian ensemble) between 1.25" and 1.5", a noticeable
increase from yesterday, with slightly more favorable 850mb moisture
transport in the 02.12z NAM/GFS. Consequently, have noticed some
increase in the ensemble probabilities for greater than 0.1",
particularly in the 02.06z EC ensemble (70-90% along and north of I-
94, 50-70% elsewhere). However, with limited instability shown in
the 02.12z NAM/GFS (around 200 J/kg MLCAPE) to aid heavier rainfall
rates, rainfall amounts still appear on the lower end at this time.
Friday - Sunday: Much Cooler Temperatures & Lingering Rain Chances
A fairly substantial pattern shift occurs for late week and into the
weekend with a strong signal for our first dose of fall-like
temperatures moving into the area. By late week, the aforementioned
broad synoptic trough closes off into an upper-low that situates
itself in the vicinity of Lake Michigan. This pattern shift will
subject our local area to strong north/northwesterly flow ushering
in a colder and drier Canadian airmass. With the cyclonic flow and
weak diurnal instability on Friday and possibly Saturday, could see
some isolated showers (15-20% chance) pop up during the daytime
hours. However, the larger story will be the cooler shift in
temperatures with many ensemble groups show a strong signal for
below normal temperatures with the 02.00z ECMWF extreme forecast
index showing values of minus 0.8 to 0.9 across our area for
Saturday suggesting temperatures well below model climatology. As a
result, expecting high temperatures on Saturday to trend in the
upper 50s to middle 60s with the 02.12z grand ensemble showing inter-
quartile range for maximum temperatures generally falling in this
range for most locations. Sunday morning appears to be the coolest
period with the lows generally in the upper 30s to middle 40s.
Depending on cloud cover trends, would not be able to rule out some
areas seeing their first frost with the recent NBM 50th percentile
minimum temperatures in the middle to upper 30s east of the
Mississippi River. Regardless, aside from some uncertainty remaining
for any lingering showers into Saturday, conditions certainly look
to be on the cool side for our open house this Saturday!
&&
.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1000 PM CDT Mon Sep 2 2024
CIGS: as high pressure gradually eases east Tue, SKC/SCT conditions
will continue to dominate. Not anticipating cigs until Thu morning
when an upper level trough is currently progged to move across the
region.
WX/vsby: RAP/HRRR bufkit soundings keep winds stirred in the
boundary layer tonight - roughly around 20 kts by 500 ft. This will
work against any river valley fog impacting KLSE. Otherwise, next
rain chances for both TAF sites holds off until Thu when an upper
level trough/sfc front are expected to slide through the local area.
WINDS: light south/southeast tonight. Some uptick Tue with
tightening pressure gradient and low level mixing upwards of 3500
ft. Sustained southerly breezes in the low teens with a few gusts
around 20 kts expected.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&
$$
DISCUSSION...Naylor
AVIATION.....Rieck
Area Forecast Discussion
National Weather Service Bismarck ND
1002 PM CDT Mon Sep 2 2024
.KEY MESSAGES...
- Hot temperatures are expected Tuesday with widespread highs in
the mid 80s to 90s. A few lower triple digit readings are
possible southwest.
- Smoke aloft from distant wildfires will continue to increase
across the region and could possibly hang around through
Wednesday.
- There`s a low chance (20 percent) for showers and storms
Tuesday night through Wednesday morning and a low chance (20
to 30 percent) for showers Wednesday night.
- A cooling trend is expected mid week with below average highs
likely by the end of the week and possibly into the weekend.
&&
.UPDATE...
Issued at 1002 PM CDT Mon Sep 2 2024
Scattered clouds and a few light radar returns are moving
through north central North Dakota, but not expecting any
precipitation/impacts from these echoes. Otherwise expecting a
quiet night ahead, with lows in the mid 50s to mid 60s,
potentially some lower 50s in the far northwest.
UPDATE
Issued at 636 PM CDT Mon Sep 2 2024
Many locations in the southwest peaked at or above 100 degrees F
this afternoon, with areas north and east of the Missouri River
generally staying in the 80s. Scattered mid to high clouds have
increased across the west and north central early this evening,
along with a thick layer of smoke aloft that is leading to hazy
skies across much of the area. No major changes needed with
this update.
&&
.DISCUSSION...
Issued at 200 PM CDT Mon Sep 2 2024
A mid level ridge axis continues to move into western North
Dakota early this afternoon. Thus far, temperatures have been a
bit slow to rise but now that winds are increasing, they are
starting to mix some of that warmer air down to the surface.
Several sites have risen into the upper 80s across the southwest
and we should continue warming through much of the afternoon. A
weak mid level shortwave cresting the ridge will pass through
the state today, which will bring in some mid level clouds, but
they shouldn`t be widespread enough to really impact highs.
There is one culprit that could impact the high temperature
forecast, however, and that will be in the increasing smoke
aloft from distant wild fires. The HRRR and RAP smoke models
both suggest smoke aloft should increase through the day and
tonight. The RAP suggests that this smoke will hang around until
at least Wednesday. For now, we will keep sky coverage at a
minimum of 30 percent through Tuesday afternoon in the gridded
forecast. If smoke aloft does end up getting thick enough, highs
could end up falling a bit short of the forecast (upper 70s and
lower 80s east, to upper 80s northwest, to upper 90s
southwest).
The ridge axis starts to move east on Tuesday with western and
central North Dakota gradually transitioning back into northwest
flow aloft. This will mean another hot day with highs ranging
from the mid to upper 80s east, to the low to mid 90s central
and northwest, and to the upper 90s southwest. A few triple
digit readings are not out of the question. Again, smoke aloft
could end up making the forecast tricky. The good news is that
dewpoints will not be overly high this afternoon or Tuesday
afternoon, so apparent temperatures should only top out in the
mid 90s across the southwest.
By Tuesday evening, a weak shortwave trough and surface cold
front will be approaching the west from Montana. Some
convection will likely initiate across the higher terrain over
central/southeast Montana and northern Wyoming in the afternoon.
Some models having these isolated showers and storms
approaching western North Dakota in the evening hours in a
weakening phase, and moving into the central overnight as
isolated showers along and behind the front. Chances for any one
location seeing measurable rain is low (20 percent). In the
early evening, a strong storm or two could lead to some gusty
winds across the southwest but the severe weather threat is low.
The parent trough moves through on Wednesday and the next weak
wave moves into the west in the evening. Highs will be cooler
on Wednesday behind the front, ranging from the upper 70s north
to the mid/upper 80s across portions of the south. As the next
wave moves through in the evening, we will see another low
chance of precipitation (20 to 30 percent) across the west,
expanding into the central overnight. The lack of any
appreciable instability will keep thunder chances low, so
precipitation type is expected to be rain showers.
After the trough moves out to the east, we transition into
northwest flow aloft which will help contribute to more
seasonably cool high temperatures through the rest of the week
and into the weekend. Highs on Thursday and Friday are forecast
to range from the lower 60s to lower 70s with some more
widespread readings in the mid 70s possibly returning Saturday.
We could see warming temperatures on Sunday as the next western
ridge axis approaches but quite a bit of uncertainty remains
regarding timing differences of synoptic features and eventual
pattern evolution. This uncertainty is illustrated nicely in the
large NBM temperature spreads Friday through Sunday.
as
&&
.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 636 PM CDT Mon Sep 2 2024
VFR conditions are expected at all terminals through the period.
Breezy south winds will diminish across western and north
central North Dakota through the night, while across the
south central and east they will stay somewhat breezy around 10
to 15 knots. Some enhanced low level wind shear will also be
possible this evening and overnight at KBIS and KJMS. Wildfire
smoke aloft will continue through the TAF period.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...Jones
DISCUSSION...ZH
AVIATION...Jones
Area Forecast Discussion
National Weather Service Columbia SC
810 PM EDT Mon Sep 2 2024
.SYNOPSIS...
A cold front will spread cooler and drier air into the area
Tuesday and Wednesday. Weak low pressure in the Gulf of Mexico
and along the Carolina coast may spread showers into the area
later this week.
&&
.NEAR TERM /UNTIL 7 AM TUESDAY MORNING/...
Key Message(s):
- Showers and thunderstorms diminishing this evening.
-Drier air spreading south late tonight.
Isolated showers and thunderstorms are focused in the CSRA at
00z. A pre-frontal trough/moisture boundary appears to be in the
central Midlands moving to the southeast. Drier air in the
Upstate region. Surface based CAPE 1500-2000 J/kg in the south
Midlands and CSRA. Rap shows CAPE weakening over the next couple
of hours. HRRR suggests convection will continue to diminish.
Overnight lows a little cooler with mid 60s north to near 70
south. Much drier air will spread south most likely after 12z,
associated with the cold front as strong high pressure to the
north builds south across the Carolina into Georgia.
&&
.SHORT TERM /7 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/...
Key Message(s):
- Much cooler temperatures expected.
- Dry conditions through Wednesday evening.
Finally, cooler temperatures move into the region behind the
cold front. In addition, pwat values drop down to around 1 inch,
bringing drier air to the forecast area also. These conditions
will last pretty much through Wednesday night as clouds and
low-level wedge pattern take hold. Can not rule out an isolated
shower late Wednesday as easterly flow off the Atlantic takes
hold ahead of the next approaching shortwave. Day time highs
through the period range from the upper 70s north, to the
low/mid 80s south. Overnight lows mainly in the middle 60s.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
Key Message(s):
- Below normal temperatures expected to continue.
- Increased chances of rain late week into the weekend.
Cooler temperatures continue into the weekend as clouds and
wedge pattern remain. There will be an increase in rain chances
though due to an area of low pressure that moves south of the
cwa along the old front Thursday and Friday. Additional upper
energy will pass through the area as upper trough moves through.
Once this low passes, another cold front is expected to be
moving towards the region through the weekend. This approaching
front will keep scattered showers/storms in the forecast through
the weekend. Temperatures during this period should be below
normal.
&&
.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
Lingering Convection Diminishes this Evening, Possible Low
Clouds Move in Towards Daybreak....
Showers are gradually diminishing this evening but continue to
linger just east of AGS/DNL so the TEMPO group has been extended
another hour. Once the rain ends, the primary concern tonight
will be the potential for low clouds to move into the terminals
from the northeast. Latest guidance suggests these clouds will
miss CAE/CUB but trends will need to be monitored. OGB is most
likely to see ceiling restrictions from the cloudiness and a
TEMPO for low MVFR ceilings is in place there towards daybreak.
Clouds should lift behind the front Tuesday morning giving away
to clearing skies with gusty northeast winds in the afternoon.
EXTENDED AVIATION OUTLOOK...No significant restrictions are
expected through Wednesday. Moisture returns for the second
half of the week leading to showers, thunderstorms, and
associated restrictions along with early morning fog or stratus.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...None.
GA...None.
&&
$$
AREA FORECAST DISCUSSION
National Weather Service Eureka CA
231 PM PDT Mon Sep 2 2024
.SYNOPSIS...Conditions are clearing out this afternoon through
evening with the return of marine stratus very likely tonight.
Warmer weather is expected through the week with the peek highs
being felt Wednesday. High pressure will promote breezy to gusty
northeast winds over the ridges tonight and Tuesday evening.
&&
.DISCUSSION...Mild conditions today for NW California as offshore
flow and dry air mix into the region, clearing out coastal stratus.
The passing of an upper level trough and cyclonic motion will
pronounce offshore flow, bringing in drier air and lowering relative
humidity as the continental air mass gets entrained locally.
Temperatures are a bit lower than what seasonal climatology shows
but that will be short lived as warm air advection is being signaled
by 850mb height models, partially as a result of counter clockwise
flow with the backside of the low passing low exposed. Heat risks
potential will progressively increase through the end of the work
week with moderate categories filling into most areas and a few
interior locations reaching the major category. Coverage does not
meet criteria at this time to warrant issuing Heat products.
High pressure will begin to build quickly in the wake of the trough.
Offshore northeast component flow is expected to develop later this
evening and increase tonight over the exposed ridges especially in
Del Norte County where gusts up to around 25 mph are likely. This
will yield clear skies along much the coast late tonight and
Tuesday.
The upper-level heights will begin to rise across the Pacific
Northwest tomorrow. This will bring a warming trend through mid to
late week. High temperatures are expected to reach or exceed the
100F degrees across the warmer locations of interior Humboldt,
Mendocino, Trinity and Lake counties on Wednesday. NBM probabilities
indicate a 60% chance of Big Bar reaching or exceeding 107F degrees
Wednesday. Even the coastal areas are expected to warm up with highs
in the 70`s before the seas breezes developed, while adjacent
coastal areas reaching the low 80`s.
In addition, winds will diminish on the ridges Tuesday morning, but
some winds may mix down into the valleys. Tuesday night into
Wednesday offshore flow will slightly strengthen over the ridges,
mainly in Del Norte County, and may keep the coast clear from
stratus again. Mid to late week, weaker offshore flow is expected
overnight.
This warm up will be short lived with around 70% of ensemble members
showing another trough by next Sunday. The ensemble spread has
generally drifted towards the wetter results with 30% - 60% of
models now showing wetting rain around September 9th. /ZVS /EYS
&&
.AVIATION...Today`s forecast challenges include determining how much
and for how long coastal stratus linger this morning, when/how
strong it will be tonight, and visibility impacts late
tonight/Tuesday morning. A deepened marine layer at around 3.5-4kft
AGL is forming in response to the negatively tilted trough/closed
low moving into our area from the west. These dynamics support a
good chance of a stratus layer with VFR visibility along the coast.
HRRR supports the existence of this stratus along the coast until
potentially around 21/22Z , then mixing out behind the upper level
trough as it migrates inland towards the east. NBM probabilities
indicate the chance of ceilings at 3kft AGL for KACV to drop
steadily to 20% at 20Z and 10% at 23Z, for example. Coastal stratus
should return with 60% chance of MVFR stratus or lower by 7Z. Wind
speeds will increase somewhat this afternoon as wind shifts to a
more northwest direction, however wind shear at the marine layer
boundary should be minimal, only a few knots difference between the
upper and lower sections of the atmosphere through the night.
Chances of reduced visibility increase for tonight into Tuesday
morning with coastal sites at about 50% chance of <5Sm and 30%
chance of <1SM of visibility at dawn at KACV. KUKI, being an
interior valley terminal should be VFR for this forecast with
moderate winds in the afternoon calming around sunset.
&&
.MARINE...Conditions will steadily degrade due to a pick up of
stronger northerly winds from tonight the evening through Wednesday.
After this current weak, dry upper level trof leaves our vicinity, a
ridge in the upper atmosphere builds back into our area, increasing
interior temperatures, leading to a reformation of the thermal trof
pattern at the surface. Sustained winds are forecasted to peak near
25kts with gusts up to 35kts possible tomorrow afternoon. These
strong northerlies will flow in the outer waters producing steep
wind waves with heights around 7-10ft by tomorrow. These wind waves,
in addition to an ongoing NW swells of 4ft@11s will create conditions
that are hazardous to small crafts will be present in the outer
waters tonight through Wednesday morning at the earliest. This
thermal trof pattern should weaken slightly through the remainder of
the work week.
&&
.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
None.
NORTHWEST CALIFORNIA COASTAL WATERS...
Small Craft Advisory from 9 AM Tuesday to 9 AM PDT
Wednesday for PZZ470.
Small Craft Advisory from 9 PM this evening to 9 AM PDT
Wednesday for PZZ475.
&&
$$
Visit us at https://www.weather.gov/eureka
Follow us on Facebook and Twitter at:
https://www.facebook.com/NWSEureka
https://www.twitter.com/NWSEureka
For forecast zone information
see the forecast zone map online:
https://www.weather.gov/images/eka/zonemap.png
Area Forecast Discussion
National Weather Service Green Bay WI
1025 PM CDT Mon Sep 2 2024
Updated aviation portion for 06Z TAF issuance
.KEY MESSAGES...
- Dry and seasonal weather is expected through Wednesday.
- Showers and thunderstorms are possible Thursday into Friday as
a cold front moves across the region.
&&
.DISCUSSION...
Issued at 225 PM CDT Mon Sep 2 2024
Those with outdoor plans this Labor Day afternoon should find
little in the way of weather impacts as a well established high
sits over the region. With winds backing around to the south
tonight overnight lows will trend a few degrees warmer than last
night with most of the area ranging from the low 40s to low 50s. A
few patchy areas of ground fog may develop, mainly across
northern WI, after midnight, but should disperse quickly after
sunrise Tuesday morning. Tuesday will trend similarly to today
with mostly clear skies and temperatures at or just slightly
above normal. Southerly winds are expected to increase Tuesday as
the pressure gradient tightens on the back side of the surface
high. Gusts may reach near 20 mph Tuesday afternoon, strongest
across northern and central WI.
There may also be a push of elevated smoke from Canadian
wildfires Tuesday. Currently don`t expect much in the way of
surface impacts, but skies may appear hazy.
Wednesday looks to be the last dry day of this week as the upper
level-pattern transitions toward the pattern half of the week.
This transition will be marked by a cold frontal passage Thursday
late morning/afternoon that will bring the next chance for rain
showers and a few thunderstorms to the region. The threat for
severe weather appears rather low at the moment, with the better
instability currently forecast to be shunted south of the Fox
Valley. The heavy rain threat is also limited as long range
ensembles have just a 20-30% for greater than 0.25" of rain
Thursday into Friday.
On and off periods of rain and breezy northerly winds may linger
into the weekend as long range models currently shows a cut-off
low stalling out south of Hudson Bay. The upper-level pattern also
supports much cooler temperatures for next weekend with highs on
Saturday currently forecast to range from the middle 50s to low
60s. Will need to monitor the need for frost/freeze headlines
Saturday night into Sunday with current lows forecast in the
middle 30s to low 40s for most locations.
&&
.AVIATION...for 06Z TAF Issuance
Issued at 1025 PM CDT Mon Sep 2 2024
Mostly clear skies will prevail overnight with only a few fair
weather cumulus and high clouds expected on Tuesday. Can`t rule
out some patchy ground fog overnight (10-20% chance), but overall
prospects for fog look low due to 10-20 kt of winds just off the
surface which will help keep the low levels mixed. If any fog
develops, it will mix out soon after sunrise Tuesday morning. Will
only include a TEMPO group at RHI for some MVFR visibilities.
Winds will remain light overnight, then southwest/south winds will
gust to 15-20 kts late Tuesday morning and afternoon.
Afternoon GOES Geocolor showed a large area of smoke across
western Minnesota, the Dakotas and Montana. HRRR vertically
integrated smoke forecast shows the smoke spreading across the
western Great Lakes overnight into Tuesday, making for hazy skies.
HRRR/RAP not showing any near-surface smoke, so no reductions in
visibilities are expected at the surface.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
DISCUSSION.....GK
AVIATION.......Bersch
Area Forecast Discussion
National Weather Service Grand Rapids MI
838 PM EDT Mon Sep 2 2024
.KEY MESSAGES...
- Tranquil weather continues
- Another warm up, another cool down
&&
.DISCUSSION...
Issued at 240 PM EDT Mon Sep 2 2024
- Tranquil weather continues
High pressure is in control of our weather, leading to cool
mornings and mild afternoons. Lows tonight look to once again be
in the 40s, though upper 30s can`t be ruled out across interior
central Lower MI. Tuesday will feature slightly warmer daytime
temperatures as 850 mb temps rise a few degrees to around 10C-11C.
This will yield highs in the mid 70s across the region. As the
surface high migrates eastward on Tuesday, light winds are still
expected though a lake breeze will almost certainly develop and
push into the lakeshore counties. That said, the breeze itself
should only be around 10 mph per the latest HRRR guidance.
- Another warm up, another cool down
September tends to be a roller coaster type of month as the Great
Lakes transitions from the hot summer temperatures to much cooler
fall temperatures. This week will be emblematic of that.
High pressure that`s over us right now will be centered over the Mid
Atlantic coast by mid week. That will place the cwa squarely in
south flow. AH8 temperatures are progd to rise from 14c to 16c Wed-
Thu. Most likely, that will give us highs in the mid 80s by
Thursday. Dewpoint will be back in the 60s Wednesday, Thursday, and
part of Friday.
A seasonally strong cold front will plow through the region Thursday
night/Friday, supported by a sharp upper trough swinging through the
Great Lakes. We`ll likely see showers and storms along/ahead of the
front. Wouldn`t be surprised to see a few strong storms either,
given progd shear values of 35-45kts and the strength of the
supporting short wave.
Much cooler air will flow in behind the front and h8 temperatures
will fall to 1c by late Saturday. The cold temperatures will create
fairly high instability over the lake, resulting in lake effect rain
showers and perhaps some waterspouts given the upper low nearby.
Highs Saturday and Sunday will only be in the upper 50s to lower
60s.
&&
.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 840 PM EDT Mon Sep 2 2024
Light winds will continue with a light south wind Tuesday. VFR
conditions will continue to dominate the pattern through the
period.
&&
.MARINE...
Issued at 240 PM EDT Mon Sep 2 2024
Waves of 1 to 2 ft are expected Tuesday as a surface high pressure
system slowly moves east of the region and southerly flow develops
on the back side of it. No significant waves are expected on the
lake until late in the week after the passage of a cold front.
This could lead to gusty winds over the waters and hazardous wave
action to small craft Friday into Saturday.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...None.
&&
$$
DISCUSSION...04/Hoving
AVIATION...Ceru
MARINE...Hoving
Area Forecast Discussion
National Weather Service North Platte NE
623 PM CDT Mon Sep 2 2024
.KEY MESSAGES...
- Hot and windy conditions continue into Tuesday, leading to
critical fire weather conditions across portions of the Sandhills. A
Red Flag Warning remains in effect through Tuesday night. See Fire
Weather Discussion below for further information.
- One more day of above normal temperatures in the 80s on Wednesday
before falling back to seasonal values in the 70s into the weekend.
- Cold front passage Wednesday will bring the next chance of showers
and thunderstorms to the area. However, dry conditions quickly
return through the rest of the week, persisting into early next week
and beyond.
&&
.SYNOPSIS...
Issued at 213 PM CDT Mon Sep 2 2024
Recent GOES-16 WV imagery and RAP 500-mb showed a trough of low
pressure pushing onshore across northern California/southern Oregon.
Southeast of this feature, upper-level high pressure was centered
over the Desert Southwest with a ridge extending northward into
northern Canada and the ridge axis bisecting portions of the local
area. An elongated upper-level trough of low pressure was situated
across Newfoundland and Labrador, extending south across New England.
At the surface, low pressure was noted across eastern Montana with a
trough extending south along the leeside of the Rockies and an
associated warm front living northward across the northern Plains.
Surface high pressure was centered across the Great Lakes. A surface
pressure gradient (SPG) has tightened in between the two surface
features with strengthening southerly flow on the western periphery
of the high pressure. As a result, southerly winds have become gusty
with recent area observations of 25 to 35 mph. Abundant sunshine
persists across the area for Labor Day with 2 PM CT temperatures
ranging from 77 degrees at Broken Bow to 88 degrees at Gordon.
&&
.SHORT TERM /THROUGH TUESDAY NIGHT/...
Issued at 213 PM CDT Mon Sep 2 2024
As the low-level jet (LLJ) strengthens tonight, near surface winds
will remain strong with widespread southerly gusts of 25 to 35 mph
through the overnight. The strongest winds nearing 40 mph will be
felt for locations in vicinity of the Nebraska/South Dakota border
where the LLJ will be maximized. With greater mixing and warm air
advection (WAA), low temperatures will remain in the above normal
range from the mid-50s to 60 degrees. As we head into Tuesday,
temperatures will trend a few degrees warmer than today as the upper-
level ridge axis will be directly overhead. Daytime temperatures
will range from the mid-80s across north central Nebraska to near
100 degrees across far northwest Nebraska. With such hot
temperatures and gusty winds continuing through the day, critical
fire weather conditions will set up across the Sandhills and western
Panhandle on Tuesday, refer to Fire Weather Discussion for more
information. Similar to tonight, the LLJ will re-intensify across
portions of the area Tuesday night with continued overnight gusts of
25 to 35 mph. Overnight lows will remain in the upper-50s to mid-60s
across western and north central Nebraska which is 5 to 10 degrees
above normal for the beginning of September.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Issued at 213 PM CDT Mon Sep 2 2024
The upper-level ridge will be forced to breakdown as the disturbance
currently pushing onshore across northern California advances across
the Great Basin into the northern Rockies on Wednesday. This will
drive a surface cold front into the area through Wednesday evening,
bringing our next and really only shot at precipitation through the
long term period. Meager moisture with dew points in the mid-50s to
near 60 degrees combined with daytime heating in the upper-80s will
result in modest destabilization (MLCAPE < 1,000 J/kg). Isolated to
widely scattered thunderstorms are expected to initiate along the
frontal boundary Wednesday afternoon and night. Deep layer shear is
rather impressive, however, the limited instability will result in a
relatively low severe threat across western and north central
Nebraska. Unfortunately, this system will likely not result in much
in the way for widespread meaningful precipitation across the area.
Forecaster confidence is rather low on the overall severe threat at
this time given variability amongst model solutions. Will continue
to monitor this potential as CAMs get into this time range. On the
bright side, the frontal passage on Wednesday will bring our first
taste at autumn-like temperatures with highs generally in the 70s
continuing through the remainder of the week into the weekend. The
pesky upper-level ridge builds back in across the western CONUS
through the weekend which will favor dry conditions to continue and
a return to above normal temperatures in the 80s next week.
&&
.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 622 PM CDT Mon Sep 2 2024
Strong, gusty southerly winds will persist throughout the effective
TAF period. Gusts will generally remain stronger across portions of
north central Nebraska, the northern Panhandle, and the northern
Sandhills. Overnight, a low level jet is expected to develop,
bringing LLWS concerns across southwest Nebraska into north central
Nebraska, as well as across portions of the southern Panhandle.
Skies are expected to remain mostly clear, as VFR conditions
prevail, though a few high clouds cannot be completely ruled
out.
&&
.FIRE WEATHER...
Issued at 213 PM CDT Mon Sep 2 2024
As the upper-level ridge continues to breakdown, critical fire
weather conditions will continue into Tuesday across the Sandhills
and western Nebraska. Temperatures have quickly climbed into the
upper-90s to low-90s which is helping drive humidity values below
20% across the northwest Sandhills. With gusty southerly winds of 30
to 35 mph, stations have begun flirting with Red Flag conditions.
The expectation is that humidity values will continue to fall
near 15% through the evening for northern portions of Fire
Weather Zone 204. Poor overnight humidity recovery (60-70%) is
anticipated with winds remaining gusty through the night
tonight. As the upper-level ridge axis bisects the area on
Tuesday, high temperatures will climb to near 100 degrees across
the Sandhills, supporting afternoon humidity values to fall to
15% or lower. Combined with continued southerly wind gusts up
to 40 mph, critical fire weather conditions are likely Tuesday
across the eastern Panhandle and Sandhills. Overnight humidity
recovery will be poor (60-70%) again Tuesday night. Given this,
the Red Flag Warning remains in effect through Tuesday night
for Fire Weather Zone 204.
A cold front will track across the area through the day on
Wednesday, signaling a wind shift to the north and a return of
rain and thunderstorm chances. Despite these chances, widespread
wetting moisture is not anticipated with this system. Though dry
conditions return for Thursday and beyond, minimum humidity
values should remain well above critical thresholds as
temperatures dip to near or below normal in the 70s, and winds
generally remain under 25 mph.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning until midnight MDT Tuesday night for NEZ204.
&&
$$
SYNOPSIS...Viken
SHORT TERM...Viken
LONG TERM...Viken
AVIATION...Richie
FIRE WEATHER...Viken
Area Forecast Discussion
National Weather Service Spokane WA
352 PM PDT Mon Sep 2 2024
.SYNOPSIS...
A low pressure system will spread an increase in showers and
isolated thunderstorms tonight across southeast Washington,
Lewiston area, and Central Panhandle Mountains. Gusty outflow
winds are expected near thunderstorms. Hot temperatures look to
return over the Inland Northwest for the latter half of next week
as the ridge of high pressure rebounds.
&&
.DISCUSSION...
Tonight through Tuesday Night: A closed low over south central
Oregon will track into northeast Oregon overnight, and then across
central Idaho Tuesday morning. The low track will result in
increasing large scale lift over SE Washington into the Central ID
Panhandle during the evening and overnight hours. This combined
with elevated instability with 700-500mb MU CAPE of 300-500 J/KG
will trigger increase coverage of showers and isolated
thunderstorms in these areas (mainly south of Spokane and Coeur
d`Alene). With precipitable water values increasing to around 180%
of normal storms will be capable of producing moderate rain. Yet
any lightning initially striking dry fuels could result in new
fire starts. This afternoon the cloud cover has limited daytime
heating over much of the region. But this is not the case around
the Walla Walla area and portions of NE Oregon with temperatures
in the 90s, and dewpoints in the 40s. This large spread will favor
the potential for strong, gusty outflow winds from storms and
potentially more limited rain initially. The Storm Prediction
Center has portions of the Blue Mountains into the Camas Prairie
under a marginal risk for severe thunderstorms. The HRRR is
showing the potential for wind gusts of 40-50 MPH in this area,
with outflow gusts weakening considerably as they propogate north
into a less favorable convective environment. This activity will
be monitored closely this evening. A second area of weaker
convection over the Cascades into the Okanogan Valley could
produce isolated storms this evening as an axis of instability
lingers.
As the low moves off to the east Tuesday afternoon the mid levels
begin to dry out and warmup which should limit the afternoon
convection cycle with mainly flat to moderate cumulus over the
higher terrain of the Camas Prairie and Shoshone county. Tuesday
Night the region will clear out as strong high pressure begins to
build over the region. JW
Wednesday through Sunday: A ridge pattern will fuel a snap back of
above normal temperatures across the region. It will bring a warm,
dry pattern through the weekend. While this will keep fire concerns
elevated, the winds will be light and threat of rapid spread will be
minimal. A southerly flow pattern could continue to bring smoke and
haze from wildfires and Oregon and Idaho into the Inland Northwest.
High temperatures through weekend will in the upper 80s and 90s.
Overnight lows will be in the 50s and low 60s. Model trends are
keeping the ridge over the region through the weekend. /JDC
&&
.AVIATION...
00Z TAFS: An upper low moving will move from south central Oregon
into northeast Oregon tonight. The low will bring an increasing
chance for showers and thunderstorms through the night around
Lewiston and Pullman, with a 10-20% chance of storms reaching as
far north at Spokane and Coeur d`Alene. These storms will bring
the potential for brief downpours and gusty outflow winds as well
as lightning. Current models show the bulk of this activity
beginning to near KPUW/KLWS near 02z-05z this evening with
additional development through the overnight hours.
FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: Given a dry sub
cloud layer over NE Oregon, confidence is high that storms will
produce gusty outflow winds. But confidence is low on precise
timing and magnitude of the gusts reaching Lewiston and Pullman.
Rain cooled air over SE Washington could also result in a
southerly wind gust reaching KGEG/KSFF with moderate confidence of
this occurring per high resolution CAM models, but low confidence
on the precise timing. Given the moderate confidence did indicate
some gusty winds for these sites. JW
-----------------------
Confidence descriptors:
Low - Less than a 30 percent chance
Moderate - 30 to 70 percent
chance High - Greater than a 70 percent chance
For additional probabilistic information for NWS Spokane airports,
please refer to the Aviation Dashboard on our webpage:
https:/www.weather.gov/otx/avndashboard
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 57 83 55 88 57 91 / 10 10 0 0 0 0
Coeur d`Alene 56 80 55 86 56 89 / 20 10 0 0 0 0
Pullman 56 77 51 86 53 89 / 40 40 0 0 0 0
Lewiston 64 85 61 92 62 97 / 70 50 0 0 0 0
Colville 48 85 47 88 49 91 / 10 0 0 0 0 0
Sandpoint 53 78 51 83 52 86 / 10 10 0 0 0 0
Kellogg 57 77 57 83 59 87 / 20 30 0 0 0 0
Moses Lake 56 86 53 90 56 95 / 10 0 0 0 0 0
Wenatchee 64 87 62 91 65 94 / 10 0 0 0 0 0
Omak 60 91 59 91 59 95 / 20 0 0 0 0 0
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$