Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/03/21
Area Forecast Discussion
National Weather Service La Crosse WI
1000 PM CDT Mon Aug 2 2021
.SHORT TERM...(This evening through Tuesday)
Issued at 228 PM CDT Mon Aug 2 2021
Continued generally dry and pleasant summer conditions are expected
to persist, with the region remaining entrenched in northerly
flow between upper ridging over the Rockies and broad troughing
over the eastern CONUS.
GOES-16 satellite shows another bout of smoke to our north, which
will work back down across the area. HRRR smoke model suggests
this should remain largely aloft across our service area, thus
limited if any surface impacts anticipated.
Pretty good radiational setup tonight with light winds and
mainly clear skies may foster some more valley fog and a bit of
stratus.
A few sprinkles or stray shower may emerge from some of the deeper
cumulus nearing our north late this afternoon through sunset.
Another chance for a stray shower or storm will be found Tuesday PM
primarily across our far north, with a glancing blow of weak
ascent attendant to a passing wave, and weak instability with
SBCAPEs upwards of around 750 j/kg. Main chances look to reside
further north/northeast of the service area with the main ascent.
.LONG TERM...(Tuesday night through Monday)
Issued at 228 PM CDT Mon Aug 2 2021
Wednesday night a broad upper-level trough east of the Mississippi
River will give way to an active zonal flow pattern aloft. A series
of embedded shortwaves will make for an unsettled stretch with
periodic showers and thunderstorms Thursday afternoon through
Monday. Confidence for PoPs is growing, especially Saturday
afternoon-night.
Temperatures and dewpoints will gradually climb into the weekend
with most of the area reaching the low 90s by Sunday. Heat indices
could reach 90-98 on Saturday and 95-100 on Sunday.
&&
.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1000 PM CDT Mon Aug 2 2021
Cigs: Some potential for a brief period of bkn003 at KLSE with river
valley fog looking likely again tonight. Otherwise, VFR with mostly
afternoon sct-bkn diurnally driven clouds for Tue afternoon.
WX/vsby: mostly clear skies and light winds - decent set up for fog
in the river valleys. T/Td spread fairly large at 03z for dense fog
at KLSE, and less than ideal low level wind field. Still expect the
Mississippi to develop fog, but conditions not looking favorable for
it to spread across the airport. Will hold with BCFG for now and
monitor trends.
Weak shortwave trough looks to slip southward across the area Tue
afternoon. Some instability (very skinny bufkit profile), but not
much RH, plus a bit of a cap near 600 mb. Some isold shra/ts not out
of the question, but not enough coverage or confidence to add to the
forecast.
Winds: mostly light and vrb through the night, becoming more
southwest Tue with a slight uptick.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&
$$
SHORT TERM...McClure
LONG TERM...KAA
AVIATION...Rieck
Area Forecast Discussion
National Weather Service Bismarck ND
959 PM CDT Mon Aug 2 2021
.UPDATE...
Issued at 959 PM CDT Mon Aug 2 2021
No changes are needed for this update. Smoke is reducing
visibility as low as 4 miles at some locations across western and
north central North Dakota.
UPDATE Issued at 637 PM CDT Mon Aug 2 2021
No major changes are needed for this update. Forecast minimum
temperatures for tonight were lowered by a couple degrees at
typical cold spots across central and southwest North Dakota.
&&
.SHORT TERM...(This evening through Tuesday)
Issued at 243 PM CDT Mon Aug 2 2021
Relatively quiet weather will prevail again for the short term
forecast period. An upper ridge will remain in place keeping it
dry with the main question being how much will any smoke impact
low level visibilities. Most locations that had visibility
restrictions early this morning improved today, though a few spots
in the state continue to linger in the 5 to 6 mile range. Smoke
continues to also reduce some visibilities in southern Manitoba
this afternoon and the last few iterations of the HRRR brings an
increase in Near-Surface Smoke across parts of the north and west
tonight. Looking at area web-cams also shows some reduction in
visibilities across the north. Long story short, we will continue
to mention patchy smoke in much of the north and west. Confidence
in exactly where to draw the line is not high, but after after
collaboration with ABR, have decided to generally keep it along
and west of the Missouri River in the southern part of the
forecast area.
Looking at temperatures, have gone close to what we had last
night with mid 50s to lower 60s in most locations. Forecast highs
for Tuesday are also similar to today, but maybe a degree or two
warmer in a few spots.
.LONG TERM...(Tuesday night through Monday)
Issued at 243 PM CDT Mon Aug 2 2021
Rain chances return to the forecast in the long term forecast with
the best chances towards the end of the week / early part of the
weekend. An H5 wave breaks down the ridge to some degree Tuesday
night into Wednesday with a weak cold front moving across the
region. There could be a few showers / thunderstorms as this
occurs, but overall rain chances during this period aren`t too
high. Have generally gone with slight chance pops for most areas,
and could see those being refined if better confidence can be
reached. The better rain chances should arrive later in the week
into the weekend, though there are still differences in model
solutions with cluster analysis suggesting some model solutions
have better rain chances than others. The latest NBM has it`s
highest pops Friday night, which is still in line with the 12Z
ECMWF, but the GFS is now suggesting lesser rain chances during
that period than some of its earlier runs. Overall, stayed with
the blended model outcome since solutions still vary on how this
will all play out. In the end, the good news is that there should
at least be some rain chances in the long term forecast period,
but details are still to be worked out.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 959 PM CDT Mon Aug 2 2021
MVFR visibility reductions due to smoke are possible. Confidence
and predictability in prevailing restrictions are very low.
Otherwise, VFR conditions, smoky skies, and light winds are likely
through the forecast period.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Hollan
SHORT TERM...CK
LONG TERM...CK
AVIATION...Hollan
AREA FORECAST DISCUSSION
National Weather Service Eureka CA
309 PM PDT Mon Aug 2 2021
.SYNOPSIS...Dry and quiet summer weather will last through the
upcoming week. It will be hot and sunny inland, with temperatures
cooling slightly mid to late week. Fairly persistent marine layer
clouds with limited afternoon sunshine will continue at the
coast.
&&
.DISCUSSION...The marine layer remains deep this afternoon in
response to the upper level wave that is moving up the west side
of the ridge that is over the great basin. This brought some
drizzle to the coast this morning and fairly extensive marine
intrusion. Tonight this wave moves past the area and heights
increase once again. This should limit the drizzle tonight and
start to shrink the marine layer. Southeast flow over the interior
areas will bring smoke out to the coast again tonight. The HRRR
smoke model is showing the some getting close to the coast, but
remaining above the marine inversion. Tuesday is expected be the
warmest day in the interior as high pressure builds in. Many areas
across the interior will see highs rising to slightly over 100
degrees in many areas. The marine layer will be slightly shallower
at the coast and clouds may remain out of Ukiah. Wednesday
another trough starts approaching from the southwest. This is
expected to increase the depth of the marine layer and push marine
clouds farther inland. Most areas will see temperatures slightly
cooler on Wednesday, especially in the near coastal areas. This
will bring some instability to the interior areas, but the
profiles look to remain too dry for storms to develop in our area,
although Siskiyou county could see some storms. This will likely
bring additional drizzle to the coastal areas late Wednesday night
into Thursday morning.
Thursday the trough moves overhead bringing cooler conditions to
the interior with highs only in the upper 80s to low 90s. This
cooler air aloft should weaken the inversion and allow the coast
to clear out in the afternoon. There will continue to be
instability on Thursday, but the profiles continue to not look
favorable for convection. There is the potential for some
convection north of the area. This will need to be monitored as it
gets closer. Friday temperatures will start to warm again,
although this will depend on how quickly the trough moves out of
the area.
For the weekend most ensemble clusters show an upper level trough
lingering over the west coast. Temperatures are expected to start
to warm again, but this will generally keep temperatures from
rising above 100. Despite the trough lingering over the area, the
dry southwest flow is generally expected to limit the instability.
MKK
&&
.AVIATION...The marine layer has deepened to 2500-3000 feet deep
along the coast. Low clouds have mostly pulled back off the North
Coast with help from a large offshore eddy. However, some low clouds
linger N of KCEC and from the southern portion of Humboldt Bay to
Cape Mendocino. S of the Cape, clouds continue to hug the coast.
Expect stratus to expand inland again later this evening, with
ceilings and visibilities lowering slowly through the night. Low
clouds made it to KUKI this morning, and this is certainly possible
again Tuesday morning, although the HRRR low-level moisture field
doesn`t indicate it at this time. Winds are expected to remain
light. /SEC
&&
.MARINE...Moderate northerly winds will continue through the period
across the outer waters, with southerly wind reversals possible for
the next couple of days near the coast. Seas will continue to be
predominantly locally generated. Wind speeds in the N outer waters
were marginal for Small Craft Advisory issuance, but seas should
warrant an advisory for that area. Have hoisted one from 3 AM
Tuesday through 9 AM Thursday. Conditions in the S outer waters
should be more marginal, and will not issue an advisory for that
area at this time. /SEC
&&
.FIRE WEATHER...Smoke associated with the McFarland and
Monument Fires will likely expand westward across much of Humboldt
and Del Norte counties again tonight and Tuesday. The marine
inversion is expected to protect the coast from the smoke, but
most other areas in these counties will likely see smoke. Eastern
areas of Trinity county are also expected to see smoke. Tuesday
afternoon the smoke will push mainly to the north of the fires.
Tuesday night into Wednesday morning the smoke will likely come
out towards the coast once again, but the marine inversion should
keep it from the immediate coast.
It is not out of the question that Siskiyou County could see a
stray shower or thunderstorm late Wednesday or Thursday afternoon.
Otherwise, the thunderstorm threat for the vast majority of
northwest California is near zero through early next week.
Tuesday will be the hottest and driest day of the week before a
trough brings slight cooling Wednesday and a subtle rise in
relative humidity. Wednesday afternoon westerly winds will likely
increase from Tuesday. Thursday more substantial cooling and rise
in RH is expected, particularly closer toward the coast as the
marine layer deepens. Winds will be mainly terrain- driven and
relatively light, though more substantial up- valley breezes may
follow that trough on Thursday afternoon. MKK/AAD
&&
.EKA WATCHES/WARNINGS/ADVISORIES...
CA...None.
NORTHWEST CALIFORNIA COASTAL WATERS...Small Craft Advisory from 3
AM Tuesday to 9 AM PDT Thursday for PZZ470.
&&
$$
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For forecast zone information
see the forecast zone map online:
https://www.weather.gov/images/eka/zonemap.png
Area Forecast Discussion
National Weather Service Grand Forks ND
1004 PM CDT Mon Aug 2 2021
.UPDATE...
Issued at 1002 PM CDT Mon Aug 2 2021
No changes needed to fcst. Band of AC from Portage la Prairie MB
thru Cavalier to Grand Forks to Fargo. Otherwise clear east and
west. Seeing a few more spots with smoke/haze with 2 1/2SM in
Cavalier AWOS at 03z. So idea of increased near surface smoke from
nightime inversion seems good. Did re-issue SPS for areas of near
sfc smoke and poor air quality in E ND. AQA from MN Pollution
Control is still in effect thru 3 pm Tuesday.
UPDATE Issued at 642 PM CDT Mon Aug 2 2021
Satellite shows a few Cirrus over the area with some AC. Still
present smoke, but most vsbys 4SM or higher. Will see if nighttime
inversion brings it more to the surface.
&&
.SHORT TERM...(This evening through Tuesday night)
Issued at 247 PM CDT Mon Aug 2 2021
Short term focus remains on the widespread smoke over the area,
some of which continues to impact visibility and air quality.
Heaping amounts of smoke over the what seems to be the majority of
the continent along with continued subsident and dry air
reinforced by ongoing drought keeps us stuck in a rut in terms of
the forecast: smoky and dry. Today`s short term is no different.
Sfc high pressure centered over central MS Valley has a wide
influence across the Upper Midwest and Northern Plains, promoting
weak flow regime in the lower levels. Aloft, northerly flow
continues on the eastern flanks of upper ridging in the West. This
continues to drift smoke aloft out of Canada into the region.
Additionally, yesterday`s plume of smoke lingers mainly within
the Red River Valley into western MN. Daytime mixing appears to be
tapping into both areas of smoke bringing it at the ground level.
As such, impacts from smoke appear to be mostly tied to these
areas: near the international border, the Red River Valley, and
within MN. Impacts from ground level smoke include reduced
visibility and air quality. Smoke throughout the column is also
influencing temps as expected; although somewhat not anticipated
is enough low level westerly flow to drive downslope warming, most
notable through temps nearing 90 in the northern Valley.
With another nocturnal inversion expected to set up tonight under
the influence of sfc high pressure, smoke should again get trapped
near the surface favoring northern and eastern locations. Some
higher level clouds and localized weak downsloping should prevent
bottoming out unlike previous nights, with lows generally in the
50s expected.
Tuesday will be similar to today with lingering widespread smoke
and high pressure influence. It remains unclear whether smoke near
the surface will continue to impact vsby and air quality, but
smoke models from HRRR and Environment Canada indicate the
potential is there. Temps Tuesday will be warmer with most seeing
at least mid to upper 80s due to gradual warming air mass aloft
from the west/northwest. This comes ahead of an approaching front
on Wednesday.
.LONG TERM...(Wednesday through Monday)
Issued at 247 PM CDT Mon Aug 2 2021
Overview...
The main features throughout the long term period will be the
continuation of above normal temperatures as well as a few chances
for some showers and thunderstorms.
Wednesday and Thursday...
By Wednesday, the upper level ridge that has dominated the weather
pattern of late will continue to retreat south and westward as it
weakens. A shift from more northerly flow to northwesterly flow is
then evident within ensemble guidance. This will open up the doors
for the next shortwave to traverse the northern Plains and in turn
introduce the next opportunity for precipitation. There are still
question marks with respect to the magnitude of appreciable moisture
accompanying this system, but nonetheless, some light showers and a
few thunderstorms will be possible across portions of northeastern
North Dakota and northwestern Minnesota. Precipitation aside, warm,
above normal temperatures still look to persist for Wednesday with
near normal temperatures for Thursday following FROPA from the
following day.
Friday into the weekend...
As an upper level trough over the Gulf of Alaska makes its descent
south and eastward, the upper level ridge will flatten, but also
push east a bit. While the incoming trough and leading wave ahead of
it will likely spur some potential for precipitation moving into the
weekend, the main ridge and warm temperatures aloft will aid in
above normal temperatures sticking around through the weekend until
we see a true air mass change.
The initial shortwave in the midlevel is expected to move into
the area late Friday into Saturday and will be the foci for the
first round of precipitation. Ensemble guidance is still showing a
good bit of variance, owing to the more uncertain nature of this
wave, and is indicating showers and thunderstorms that are more
scattered in nature. The longwave trough is then expected to catch
up to the shortwave a bit by the late Saturday into Sunday period
and will provide yet another opportunity for showers and
thunderstorms across the area. It is a bit too soon to begin
postulating about the potential severity of storms, but will need
to keep an eye on the environment leading up to these potential
events. All this in mind, overall consensus is running around a
30-40% chance for precipitation at this time.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 642 PM CDT Mon Aug 2 2021
Vsby reductions due to smoke/haze thru the pd at some locations.
Smoke layer around 10k feet or higher this aftn but may lower
tonight.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.
$$
UPDATE...Riddle
SHORT TERM...CJ
LONG TERM...Rick
AVIATION...Riddle
AREA FORECAST DISCUSSION
National Weather Service Sioux Falls SD
1038 PM CDT Mon Aug 2 2021
.SHORT TERM...(This Evening through Tuesday)
Issued at 324 PM CDT Mon Aug 2 2021
Amplified CONUS pattern has the region perfectly placed in the deep
north to northwest flow aloft across the area, limiting moisture
return and keeping the smoke flowing in, both to a lesser degree
surface and greater degree aloft. Cooler air off-surface and
cyclonic residual to flow has produce a flat diurnal cumulus field
over areas mainly near/east of I-29 this afternoon, with temps a
shade warmer than yesterday. The earlier lighter amount of smoke has
largely ventilated out with visibility at 7 to 10 miles.
Tonight, there is the days-old question of what is going to happen
with the smoke/fog/haze hybrid. There is a weak wave starting to
shear by to the east in the northwesterly flow aloft, and should
pass by early evening. The biggest impact to this feature will be
to increase some off surface flow toward a bit more northerly
component for a while, and potentially spread in some slightly
thicker smoke aloft. At the surface however, the ridge keeping winds
light today will slip a bit off to the east/southeast toward
northern MO and allow a bit more of a southerly component.
Unfortunately, when one combines this feature with the typical
nocturnal stabilization, it seems likely and in agreement with
several late HRRR-smoke runs that there will be return of some lower
visibility and reduced air quality starting later in the evening and
continuing until at least mid-morning on Tuesday. Visibility should
not get too low, perhaps 4-6 miles at lowest. The greatest impacts
from smoke and derivatives should be James valley and east.
Tuesday should present a similar diurnal trend toward improving
visibility. However, there will be a tendency through tonight and
especially Tuesday that high-level smoke will be thickening up a bit
given the persistence of northerly flow. This will tend to offset
some of the warming of the airmass and increased southerly flow on
Tuesday, so likely only subtly warmer with highs in the 80s.
.LONG TERM...(Tuesday Night through Monday)
Issued at 324 PM CDT Mon Aug 2 2021
Somewhat stronger southerly flow by Tuesday night/Wednesday.
Could see some marginal impacts from smoke, but for now will keep
out of the mention until certainty increases. Likely will continue
to see higher amounts of smoke aloft though, which again could
take a couple degrees of high temp expectations on Wednesday.
Still looking for a weak wave to move through late day Wednesday
as ridge begins to flatten. Wave does really stretch out and limit
dynamics, along with having almost no impactful low-level
moisture levels, and a fairly stable mid-level thermal profile
which will limit lift forcing communication of the weak later
afternoon/evening PV advection. Therefore, likely will only see a
very isolated/small threat for some elevated showers/spotty
thunder from very late afternoon into the night. With a bit more
energy heading toward the southern edge of the wave, do get some
increase in warm advection toward northeast NE and northwest IA by
later in the night, and could see a slightly better chance for a
shower/thunderstorm.
One of the things that has changed slightly from the earlier
forecast is consensus toward a much less significant trailing wave
later Thursday into Thursday evening dropping in behind the initial
wave. Exiting wave could leave a little better chance for an
earlier day shower/thunderstorm, especially toward southwest MN, but
still warrants only a small chance at this point. With a bit
quicker exit to clouds and encroachment of warmer air, should see
some lower 90s return to areas from the James River valley and west.
Ridging aloft through Friday over the plains will keep quiet
conditions, and continued expansion of warmer air with some mid to
upper 90s toward south central SD.
Leading wave on Saturday coming at the start of transition to
southwest flow aloft comes in just before temps aloft get too warm,
so with the southern edge of the mainly north-focused decent QG
forcing will likely come with the best chance for some thunderstorms
especially north of Interstate 90 Friday night/early Sat. At this
point, instability/shear would warrant at least some future
attention toward a minimal severe threat.
The big story for the weekend will be the continued trend toward
very warm temperatures, especially on Sunday which picks up a more
distinct westerly component. Even more conservative EC/ensembles
trended warmer, and thus had some confidence in nudging up the
initial blends slightly. Heat indices even Saturday could push
100 degrees with higher dew point readings, and even with some
drying the air temperatures even approaching that on Sunday
through the James/Missouri River corridor. Perhaps a few
thunderstorms Sunday night toward southwest MN/northwest IA along
a frontal boundary sagging southward overnight, but temps aloft
stay warm Monday and the boundary expected to stall, should remain
inert through the day.
&&
.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1037 PM CDT Mon Aug 2 2021
Overall, VFR conditions are expected tonight, with some MVFR
conditions as winds continue to decrease and surface smoke/haze
lingers over the area. HREF guidance this evening hints at some fog
possible across northwestern IA and through the Missouri River
Valley. Thus, could see some very isolated areas of high IFR
conditions should fog develop.
Expect visibility to improve through the late morning and early
afternoon hours, as mixing decreases the amount and impact of smoke
at the surface. Smoke remains across the region aloft though,
keeping somewhat hazy skies in place. Anticipate winds to turn more
southerly and increase with mixing as well.
HRRR near surface smoke model hints again at a slight increase in
surface smoke concentration as mixing wanes toward the end of
this TAF period. Confidence remains fairly low regarding potential
impacts to TAF sites, and will omit at this time.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
SHORT TERM...Chapman
LONG TERM...Chapman
AVIATION...SG
AREA FORECAST DISCUSSION
National Weather Service Hastings NE
650 PM CDT Mon Aug 2 2021
...AVIATION UPDATE...
.DISCUSSION...(This evening through Monday)
Issued at 429 PM CDT Mon Aug 2 2021
General overview/highlights of the entire 7-day forecast:
- Another blast of heat centered on the weekend:
At least for now, the number one concern overall is what appears
to be our next blast of heat and at least somewhat high humidity
centered on Friday- Monday (currently not looking quite as
brutally humid as our last round, but will need to keep an eye on
trends). Although plenty of time for at least small forecast
adjustments, Sunday currently appears to the overall- worst heat
day of the next week, as we already have a decent coverage of
100-105+ heat index in our official forecast especially in our KS
zones and eastern-most NE counties. Actual high temperatures are
currently forecast to feature widespread low-mid 90s for most of
our CWA Fri-Mon, with upper 90s-low 100s more favored near and
especially south of the NE/KS border.
- Limited (but not non-existent) thunderstorm chances:
Our second-biggest thing (and currently not a major concern but
bears watching as always) is at least two chances of
thunderstorms, the first centered late Wed afternoon-overnight,
and the second Friday night. Completely agree with SPC on leaving
out official severe storm chances for now, but a glance at the
first setup Wed afternoon-evening gives this forecaster at least
some impression that a few stronger storms cannot be completely
discounted. Although the aforementioned Wed/Fri chances are
currently the only ones in our official forecast, various 12Z
models suggest that a couple of other time frames may become
candidates for at least small chances (PoPs) in later
forecasts...including Monday (a week from today).
- Continued pesky smoke...mainly aloft but a little near-surface:
A possible third concern is the likelihood of continued, mainly
minor intrusions of near-surface smoke and associated fairly minor
visibility reductions. Of course, we are leaning heavily on the
HRRR-Smoke model for trying to anticipate this ever- evolving
phenomenon, which only officially goes out 48 hours in time, so
there are some temporal limitations. That being said, a glance at
the latest 18Z run suggests that especially the eastern half to
two-thirds of our CWA could get a modest dose of near- surface
based smoky haze mainly later tonight into Tuesday AM, and have a
generic mention of "haze" in the forecast to account for this
(anything beyond Tuesday will be handled in later forecasts, as we
are largely taking things "one day at a time" here). And just to
be clear, this paragraph only addresses NEAR- SURFACE smoke
concerns, as smoky haze aloft in the mid- upper levels is pretty
much a given for several more days, especially as long as we
remain under prevailing northwesterly flow (probably through at
least Thurs or Fri).
With the "big picture" items covered, the rest of this discussion
will focus on current weather and short term details, addressing
only these next 48 hours/4 forecast periods...
Our current/recent weather scene as of 330 PM:
Certainly no big surprises today, as the early-morning forecast
issuance has played out pretty well, although a combo of higher
level smoky haze and some passing real cirrus clouds looks to be
trying to hold high temps perhaps very slightly below expectations
(most areas on track to top out 80-85, with any upper 80s confined
to far southwestern counties such as Furnas/Phillips). Otherwise,
water vapor imagery and short term model data confirm rather
pronounced north-northwesterly flow in the mid-upper levels over
the Central Plains, as our region resides in the "transition zone"
between large scale western ridging and eastern CONUS troughing.
At the surface, the high pressure axis that brought our northerly
breezes yesterday has since slid off to our east (mainly centered
over IA), resulting in fairly light south- southeasterly breezes
locally (speeds mainly around 10 MPH or less). Despite the
directional change in winds, humidity levels remain seasonably-
comfortable thanks to dewpoint only averaging mid 50s-low 60s at
most.
This evening-overnight:
High confidence in a dry night, although various models (including
RAP13) suggest a good chance of not only continued passing high
cirrus but also development of perhaps fairly decent coverage of
mid level clouds (based around 10K ft.). If we had even a little
bit of elevated instability to speak of, this would be a fairly
classic setup for "sneaky" early morning showers/sprinkles, but in
this case it just looks too dry/stable to support it. Otherwise,
as mentioned earlier on, have continued a mention of generic
"haze" drifting back into the majority of our CWA from east-to-
west as the night wears on, due to fairly light near-surface smoke
suggested by the HRRR. Unlike this morning though, do not
currently expect legitimate patchy fog, due to lower boundary
layer relative humidity/slightly stronger boundary layer mixing.
Speaking of which, overnight breezes should generally average 5-10
MPH from the southeast (closer to 5 MPH post-midnight). Low temps
again below average, but not as cool as this morning as have most
areas aimed between 57-60.
Tuesday daytime:
Overall, fairly similar/continued dry conditions to today, but
perhaps a few degrees warmer and with a little bit more breeze. In
the mid-upper levels we remain under the persistent north-
northwesterly flow, while at the surface the pressure gradient
tightens up a bit, fostering sustained south-southeast speeds
10-15 MPH/gusts around 20 MPH. As for sky cover, expect generally
partly cloudy overall, under a varied mix of mid-high level clouds
(and of course the ever-present higher level smoke as well).
Speaking of smoke but in the near-surface layer, could still have
some morning haze mainly in our eastern half (minor visibility
reductions), but this should largely improve/mix out for the
afternoon. Kept high temps a bit conservative given how today
panned out (readings likely held down a bit by combo of
clouds/smoke), but still aiming very slightly warmer than today,
ranging mainly 82-86 northeast half and 85-90 southwest half.
Tuesday night:
Although a weak, very slow moving shortwave trough will approach
western portions of the Central Plains, still calling for a dry
forecast locally. That being said, there could be just enough
meager low- mid level moisture advection/saturation to MAYBE try
popping some late night/early AM sprinkles near our far eastern
CWA border (something to keep an eye on). Otherwise, the warming
trend continued with overnight low temps, as they should hold up
low-mid 60s most areas, owing in part to slightly steadier south-
southeast breezes around 10 MPH.
Wednesday daytime:
Not gonna dive into too much detail at this 36-48 hour range, but
Wednesday afternoon brings our first official rain/thunderstorm
chance of the week, as the aforementioned weak upper disturbance
arrives from the west-northwest, and combines with modest low-
level/surface convergence along a trough axis that arrives near
our far western/northwest CWA by mid-late afternoon to fire up
some convection. Although for now only have slight/20 percent PoPs
confined to our far western NE zones before 7 PM (mainly
Dawson/Gosper/Furnas), various models (NAM/GFS/ECMWF) are all
increasingly-suggestive of isolated to perhaps scattered storms
especially after 4 PM. Although suspect the 18Z NAM is over-doing
instability slightly, the combo of at least a narrow corridor of
at least 1000-1500 J/kg mixed layer CAPE and fairly weak deep
layer shear only around 25 KT at best, could be enough to promote
a few stronger storms (bears watching). Obviously these chances
continue into Wed evening-overnight, but will not get into that
period here. In other Wednesday daytime departments, temps look
fairly similar to Tuesday with mainly mid 80s most Neb zones and
upper 80s/low 90s KS. Ahead of the approaching surface trough,
southerly winds look a touch breezy especially in the eastern 2/3
of the CWA (generally 10-20 MPH with some gusts up to around 25
MPH).
&&
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Wednesday)
Issued at 645 PM CDT Mon Aug 2 2021
Significant weather: Minor VSBY reductions due to smoke/haze
Tonight: Should stay mainly VFR as near-sfc smoke concentrations
haven`t been as high as past few days. Not much for clds this eve,
then perhaps some mid level clds by dawn. Wind will be lgt out of
the SE-SSE. Confidence: High.
Tuesday: Maintained the previously forecast high end MVFR VSBYs
for Tue AM as HRRR indicates slight uptick in sfc smoke. Won`t be
much, though, and even the HRRR slides this E/NE toward midday.
Nonetheless, it`ll be at least a little hazy as mid to high level
smoke continues. Some mid level clds for AM should dissipate for
the aftn as winds incr out of the S around 8-13KT. Confidence:
Medium.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
DISCUSSION...Pfannkuch
AVIATION...Thies
Area Forecast Discussion
National Weather Service Green Bay WI
1022 PM CDT Mon Aug 2 2021
Updated aviation portion for 06Z TAF issuance
.SHORT TERM...Tonight and Tuesday
Issued at 227 PM CDT Mon Aug 2 2021
The main forecast concern will be trying to determine extent of
precipitation later this afternoon and again for Tuesday
afternoon.
The 19Z MSAS surface analysis showed a weak trough over eastern
WI, a cold front draped from southern Ontario into northern MN and
high pressure that extended from the central Plains into central
WI. Visible satellite imagery indicated a scattering of mid and
high-level cumulus clouds, while the radar only showed isolated
light showers along the lake breeze near Lake Michigan.
Still anticipating at least a stray shower or thunderstorm to
develop later this afternoon as a weak shortwave trough drops
southeast through the area. Otherwise, partly sunny skies skies
are expected with temperatures a little below normal.
Any shower or thunderstorm activity will dissipate this evening as
daytime heating wanes and the shortwave trough exits the area.
Otherwise, partly cloudy skies are expected tonight due a plume
of smoke moving across northeast WI through the night. An Air
Quality Advisory has been posted through Noon on Tuesday. Generally
light winds again will allow temperatures to fall into the lower
to middle 50s north, middle 50s to around 60 degrees south.
Another mid-level shortwave trough is progged to drop south
through WI on Tuesday. The atmosphere will be a bit more unstable
with SBCAPES of 1000-1500 J/KG and mid-level lapse rates of 6.0 to
6.5 C/KM. However, shear is negligible (<20 kts) and there is not
much in the way of lift present. Therefore, have kept low chance
pops in the forecast primarily during the afternoon (peak
heating). Do not anticipate any severe storms at this time.
Tuesday will also be a warmer day with readings around 80 degrees
near Lake MI, lower to middle 80s inland.
.LONG TERM...Tuesday Night Through Monday
Issued at 227 PM CDT Mon Aug 2 2021
Fairly quiet weather expected through mid week, then increasing
humidity and unsettled weather toward the end of the week into the
weekend.
Tuesday night through Wednesday night: Northeast Wisconsin will be
on the north/northwestern fringes of a surface ridge, roughly
centered over southern Lake Michigan/southern lower Michigan. Drier
air and weak upper-level ridging is expected to build across the
area through this time period, keeping conditions fairly quiet under
mostly clear skies. It possible that a few showers or isolated
thunderstorms could linger into early Tuesday evening, from Tuesday
afternoon convection, but this will quickly diminish toward sunset.
Overnight lows are expected to be in the mid 50s to low 60s. High
temperatures are forecast to warm into the low to mid 80s.
Thursday through Friday: The aforementioned surface ridge will
continue to drift slowly off to the east of the area, allowing for
return southerly flow. This will help to increase moisture across
the area, creating more muggy/humid conditions. Along with the
increasing moisture, a shortwave is expected to approach the area
from the northwest toward Thursday evening. In fact, current timing
would have the shortwave moving into western WI by 00Z/6th, before
passing directly over northeast Wisconsin between 06Z and 18Z. The
combination of increased moisture and a weak surface trough will
allow for increased chances for showers and thunderstorms. The best
chance for thunderstorm will be during the day Friday and most
likely Friday afternoon as instability increases. Shear values are
fairly weak at 20kts or less, so the severe weather threat is
expected to be low. High temperatures are expected to be in the
upper 70s to mid 80s. Overnight lows are forecast to be in the 60s.
Rest of the extended: Models are pointing toward a warm front
passing through northeast Wisconsin Saturday into Sunday as a
surface low slides across the northern Plains. At the same time, a
closed upper-level low is progged to dig into the northern Plains by
Sunday afternoon. Ahead of the closed low, a shortwave is expected
to pass through the area Saturday night into Sunday morning. The
combination of the front being nearby, the shortwave and the
increased moisture/instability will allow for continued chances of
showers and thunderstorms into the weekend. Some of the storms could
become strong or possibly severe late in the weekend into early next
week; however, exact details (timing/location/instability/shear)
will need to be pinned down over the next several days. Temperatures
will be running above normal through much of this time period.
&&
.AVIATION...for 06Z TAF Issuance
Issued at 1017 PM CDT Mon Aug 2 2021
Generally good flying conditions are expected through the TAF
period as weak northwest upper flow continues and surface high
pressure shifts off to the southeast of the area. Some combination
of smoke/haze/fog could result in some MVFR conditions across the
north overnight. Otherwise, stuck with the HRRR smoke forecast to
account for bands of smoke shifting across the area tomorrow.
That suggests the best chance for smoke to produce a vsby
restriction during the day tomorrow is across about the NW 3/4 of
the forecast area during the day tomorrow. Daytime heating will
continue to produce SCT/BKN clouds, along with a few showers or
sprinkles.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....Kallas
LONG TERM......Cooley
AVIATION.......Skowronski
Area Forecast Discussion...UPDATED
National Weather Service Gray ME
1130 PM EDT Mon Aug 2 2021
.SYNOPSIS...
Low pressure and associated rain showers exit to the east this
evening. High pressure builds in through the middle of the
week, although a stationary front will linger offshore with
unsettled conditions remaining nearby. The storm track may
reorient over our region through the end of the week with
increasing chances for rain showers.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
Update...Clear skies across the area are allowing temps to
radiate quite a bit. Cleaned up the grids by adjusting temps
down a little faster in the next couple of hours.
Previous discussion...An upper level trough will continue to
exit to our east and weaken with time through this evening. The
latest HRRR and HREF do have the clouds and and leftover
isolated showers diminishing around or shortly after sunset.
With clear skies, light winds and drier air filtering into the
area, radiational cooling will kick in across the region. Low
temperatures will drop into the 40s across the north with 50s in
the south.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/...
High pressure will build over the region on Tuesday with any
patchy fog mixing out early. With plenty of sunshine and H8
temperatures around +11C, temperatures will climb through the
70s during the day with readings around 80 over southern New
Hampshire. Winds will be much lighter than today, with a light
southwesterly breeze. This will make for cooler temperatures
along the Midcoast regions as winds will be onshore off the Gulf
of Maine.
Clouds will increase somewhat along and near the coastline
Tuesday night as a frontal system lifts north from the Mid
Atlantic region. Areas of rain will develop, but stay well
offshore in portions of the Gulf of Maine. The cloud cover will
allow for warmer overnight lows right along the coastline.
As we head into the long term portion of the forecast, there are
some discrepancies from model to model and run to run as to how
far north precipitation will fall.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Area remains under the influence of the upper level trough through
late week, with high pressure at the surface. Looking at low
humidity continuing with PWATs <0.75" for much of the week, keeping
rain chances at a minimum. Surface ridging over the W Atlantic will
support a slow warming with increasing heights aloft each day
along with increasing humidity each day. Highs by Friday will
be near 80 for southern counties, and mid to upper 70s across
higher elevations. Lows will start off in the lower 50s with
some upper 40s in the higher terrain, but as the surface
dewpoints creep upward min temps will rise towards 60 by late
week.
Attention will be on the surface frontal boundary lingering off the
Carolina`s extending northeast towards our offshore waters for
much of the week. A series of shortwaves will train along this
boundary, but shouldn`t be close enough to the area to bring in
rainfall until possibly Thursday. The models are split on
whether a shortwave will be able to skirt by the area then, so
have introduced scattered showers for Thursday and Thursday
night with highest chances along the coast. However, these
shortwave features are weak and low confidence on positioning
this far out so will need more run-to-run and model consistency
to raise pops to likely.
The upper level trough will lift northeast late week and a
ridge will build over the east coast over the weekend. This will
favor return sw flow with increasing humidity and rising
heights aloft. Temperatures will be in the 80s and dewpoints
will return to the 60s. Overall the larger scale flow aloft
has a brief trough Sunday, which will favor increasing pops
enhanced by daytime heating Sun/Mon.
&&
.AVIATION /04Z TUESDAY THROUGH SATURDAY/...
Short Term...Any leftover sprinkles or isolated showers will
dissipate this evening by sunset. As winds diminish to calm
under clear skies, radiational cooling will allow for
temperatures to approach their dew points. Patchy fog will
develop, primarily in the Connecticut River Valley and over the
northern valleys with locally IFR conditions. Otherwise, VFR
conditions tonight through Tuesday night.
Long Term...High pressure will keep fair conditions at area terminals
in the long term. Low humidity should limit the potential for low
clouds, and fog chances will be limited to valleys at nighttime,
but no notable moisture surge until late week. Periodic flight
restrictions are likely starting Thursday afternoon, especially
along the coast.
&&
.MARINE...
Short Term...South to southwesterly winds will be on the
increase Tuesday and Tuesday night as a gradient gradually
increases over the waters with gusts reaching 20 kts. Otherwise,
winds and seas will remain below SCA thresholds.
Long Term...Surface high pressure will keep conditions fair across
the coastal waters for much of the forecast. A frontal boundary
located offshore and extending into the Carolina`s will continue to
see weak areas of low pressure training northeast throughout the
week. These features and the boundary are projected to remain
offshore until late week. The NAM/ECMWF bring a wave into the
coastal waters on Thursday into Thursday night producing a wind
shift, but speeds expected below 15kt and seas 1-3 feet. Timing of
these weak shortwaves are low confidence, and the position of the
boundary could likewise shift overtime. For the weekend high
pressure with sw flow will build in from the west. The ECMWF shows
some long period s swells moving in from the high over the western
Atlantic starting Saturday, which could increase seas to around 3-4
feet.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...None.
&&
$$
NEAR TERM...Legro
Area Forecast Discussion
National Weather Service Key West FL
1000 PM EDT Mon Aug 2 2021
.DISCUSSION...
Another quiet evening across the Keys with current temperatures
in the mid to upper 80s and no convection noted on radar, except
for a few showers in the Gulf of Mexico waters from about 40 nm
northwest of Key West eastward to the southwest Florida coast.
Earlier convection that formed along the spine of Cuba moved
northward into the offshore Florida Straits but has since
dissipated. Despite plenty of colliding outflow boundaries on
radar and a moist atmosphere in place as shown by the 1.84 PWAT
on the 00Z KKEY sounding, weak CIN around 850mb along with
considerable dry air between 700-300mb is inhibiting more shower
and thunderstorm development. Thus most areas will stay dry
overnight with just isolated showers around. However, last
several HRRR model runs show considerable convection developing
along the land breeze very late tonight from Biscayne Bay towards
the far Upper Keys and Florida Bay. Based on this, nudged pops up
just a tad for that area. Otherwise, rest of forecast remains on
track with tonight looking very similar to the past few nights.
&&
.MARINE...
No watches, warnings, or advisories are in effect for the Florida
Keys coastal waters. Mainly light southeast to south breezes
prevail across all waters this afternoon. A surface ridge axis
lies just to our north and will maintain light to gentle breezes
through the overnight. Thereafter strengthening high pressure over
the Atlantic could lead to occasional weak nocturnal surges
through the end of the week.
&&
.AVIATION...
VFR conditions will prevail at both EYW and MTH island terminals
through Tuesday evening. Confidence in isolated showers developing
late tonight and early tomorrow is increasing, therefore VCSH has
been introduced at both terminals beginning overnight through early
afternoon. Otherwise, surface winds will remain out of the southeast
to south at 5 to 7 knots.
&&
.CLIMATE...
In 2016, the daily record rainfall of 2.56" was recorded in Key
West. Precipitation records date back to 1871.
&&
.KEY WATCHES/WARNINGS/ADVISORIES...
FL...None.
GM...None.
&&
$$
Public/Marine/Fire...Shamburger
Aviation/Nowcasts....Williams
Data Acquisition.....JAM
Visit us on the web at weather.gov/key
Follow us on Facebook and Twitter at:
www.facebook.com/nwskeywest
www.twitter.com/nwskeywest
Area Forecast Discussion
National Weather Service North Platte NE
617 PM CDT Mon Aug 2 2021
.SHORT TERM...(This evening through Tuesday night)
Issued at 339 PM CDT Mon Aug 2 2021
Sfc high pressure across the Central Plains and Midwest will move
very slowly east tonight through Tuesday night. The temperature
forecast leans on the cooler short term model blend which
indicates a couple of degree increase Tuesday. This is consistent
with the slight rise in the temperatures at h850mb shown by the
models. No dramatic increase in low level moisture is indicated in
the models. Dew points slowly rise from the 40s and 50s Tuesday
to 50s Tuesday night.
There appears to be little end in sight for the haze according to
Satellite analysis and the HRRR smoke forecast which is available
through 12z Wednesday. Definite haze is in the forecast through
Tuesday night. In the longer term, satellite, cameras, and
analysis from AirNow.gov suggest the smoke causing the haze
extends well north into Canada. Some level of haziness can be
expected across wrn and ncntl Nebraska for the foreseeable future.
The amount of haze will depend on the trajectory of the smoke and
mixing processes which becomes increasingly difficult to predict
beyond 48 hours.
Water vapor this afternoon shows and upper level disturbance over
SLC. This disturbance and attendant subtropical moisture plume
should translate east tonight and Tuesday presenting an increase in
mid and high cloudiness across wrn Nebraska Tuesday night.
.LONG TERM...(Wednesday through Monday)
Issued at 339 PM CDT Mon Aug 2 2021
The upper level disturbance near SLC this afternoon will glide
through wrn and ncntl Nebraska Wednesday. The moisture is good but
the forcing is weak and the models suggest just an isolated rain
chance. This might be the result of dry air below h700mb. The ECM
is more moist than the deeply mixed GFS and suggested the
potential for a few 1/4 inch rain totals. The forecast sides with
the drier NAM and GFS models and isolated POPs are in place
Wednesday for this disturbance.
Another thunderstorm chance develops Friday night. Winds aloft will
be strong increasing to 40 to 45 kts at h500mb. This is the
result of a deep upper level low circulating through the Dakotas
as shown by the GFS and ECM. Moisture appears to be on the low
side across wrn and ncntl Nebraska according to the GFS with
precipitable water generally less than 1.25 inches. The strong
winds aloft, resultant shear and limited moisture could limit
storm coverage. Just an isolated thunderstorm is in place for this
event.
Otherwise, heat wave conditions appear likely Thursday through
Saturday and possibly through Monday. This will be a drier heatwave
than the event in late July. The models are in good agreement
driving a dryline through wrn Nebraska into ncntl Nebraska. There
is a chance the dryline will sharpen up across ncntl Nebraska and
this could be the basis for a heat advisory condition near
highway 183 or farther east along highway 281 sometime Friday or
later. A cold front might enter Nebraska Sunday or Monday and this
could cool temperatures a few degrees or more. Nonetheless,
temperatures aloft rise to 15C to 17C at h700mb and to near 30C
at h850mb Friday through Monday. Given the deep mixing expected,
highs in the 90s to near 100F are in place which might be
conservative considering the very dry air below h700mb-
h850-700mb humidity is 20 percent or less in the GFS and ECM
models.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 615 PM CDT Mon Aug 2 2021
VFR conditions are expected through the TAF period. Residual
wildfire smoke is still in the atmosphere, creating some hazy
conditions and VIS down to 6SM. Winds overnight will generally be
from the southeast at or under 10 kts. There are no other concerns
at this time.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...CDC
LONG TERM...CDC
AVIATION...Sinclair
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1041 PM CDT Mon Aug 2 2021
.SHORT TERM...(This evening through Tuesday night)
Issued at 239 PM CDT Mon Aug 2 2021
Dry weather will continue with periods of filtered sunshine due to
the smoke. An Air Quality Advisory has been issued for the northern
half of Wisconsin. Otherwise no significant changes to the previous
forecast.
Today and Tuesday - Upper level height rises will lead to surface
high pressure and dry conditions across the region. Northerly winds
aloft could bring additional smoke across the region. Meanwhile light
winds at the surface will continue through Tuesday. The latest HRRR
guidance shows some reduction in visibility possible, and the
stagnant air mass should keep the low level particulates in place,
so an Air Quality alert was issued for the northern half of
Wisconsin.
Dry conditions are expected, and afternoon highs will be a few
degrees warmer than they were today with winds becoming
southwesterly.
.LONG TERM...(Wednesday through Monday)
Issued at 239 PM CDT Mon Aug 2 2021
The main messages of the forecast in the extended is the small chance
for scattered showers and thunderstorms Wednesday night into Thursday
as a weak cold front moves through. Meanwhile there is a higher
chance for thunderstorms over the weekend.
Wednesday through Friday - A weakening cold front and upper level
trough will move through the region and should provide enough lift
for clouds and a few scattered thunderstorms. Winds will be light
with this system, and mid level lapse rates are only around 5.5 to 6
C/km so the severe threat is fairly low. Afternoon temperatures will
be in the mid to upper 80s depending on cloud cover.
Saturday through Monday - The upper level pattern will transition
from northwest flow to more zonal flow later this week. Forecast
models are in fairly good agreement that a compact shortwave trough
will track eastward from the Dakotas toward the Upper Midwest. Warm
air advection ahead of this system and mid level lapse rates of close
to 8C/km will set the stage for MUCAPE values of at least 2000 J/kg,
and the veered wind profile ahead of the wave will support organized
convection. Continued with the blended guidance in terms of rain
chances, but this event does appear to have the potential to produce
severe weather if things come together. Meanwhile, forecast highs
could reach the low 90s, but again this will depend on clouds and
precipitation.
&&
.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1040 PM CDT Mon Aug 2 2021
No changes to previous TAFs as 3-6SM FU/HZ continues overnight.
Localized IFR vsby may develop but not expected to be widespread.
Winds will be light from the southwest, becoming more west on Tuesday
and back to the south by the evening. Wind speeds will remain under
10 kts.
KMSP...
No additional concerns.
/OUTLOOK FOR KMSP/
Wed...VFR. Wind SW 10-15 kts.
Thu...VFR. Chc TSTM. Wind SW 10-15 kts.
Fri...VFR. Wind S/SSE 5-10 kts.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...None.
WI...None.
&&
$$
SHORT TERM...JRB
LONG TERM...JRB
AVIATION...JLT
Area Forecast Discussion
National Weather Service Norman OK
1049 PM CDT Mon Aug 2 2021
...New UPDATE, AVIATION...
.UPDATE...
Issued at 1048 PM CDT Mon Aug 2 2021
One small shower has developed over Atoka County and is moving
southwest. The RAP and to some extent the high-res NAM both show
a small window of time with some potential showers, but show this
development dissipating soon. The precipitation coverage is not
nor is expected to be very high and with a quick expected
dissipation, do not think it is likely worth adding 20 percent
POPs here.
&&
.SHORT TERM...
(This evening through Tuesday)
Issued at 258 PM CDT Mon Aug 2 2021
Main weather impacts tonight and tomorrow will be reduced
visibilities and air quality due to haze, via residual smoke from
northwest U.S. and western Canada wildfires. Lower level
trajectories and near surface smoke models indicate that similar
conditions will continue through tomorrow and likely into Wednesday
before a more predominant southerly flow pattern returns. Other than
that, unseasonably un-hot conditions expected again tonight and
Tuesday.
&&
.LONG TERM...
(Tuesday night through next Sunday)
Issued at 258 PM CDT Mon Aug 2 2021
The mid-level ridge that is currently centered over the desert
southwest gradually shifts to the east as the broad trough over
the northeast gradually weakens. The HRRR smoke model indicates
that hazy conditions will continue into Wednesday, and possibly
Thursday as upper level flow continues to transport residual
wildfire smoke into our area.
A shortwave traveling along the eastern periphery of the ridge
exits the Rockies late Wednesday and brings increased mid- to
high-level clouds by late Wednesday afternoon. The wave tracks
slowly across the central plains on Thursday morning and
cloudcover is expected to diminish from west to east by Thursday
afternoon. The resulting surface trough will allow winds to shift
to the south on Thursday. The mid-level ridge then begins to shift
east and the low-level thermal ridge enters our CWA on Friday.
H850 temperatures will increase from the teens upwards towards
25-30C, and this will result in hot conditions once again as we
head into the weekend. Rain chances remain very low throughout the
period.
Thompson
&&
.AVIATION...
(06Z TAFS)
Issued at 1048 PM CDT Mon Aug 2 2021
Main issue will continue to be locally reduced visibility with the
areas of smoke that have filtered in to the area from the
wildfires in the Pacific Northwest and British Columbia. May see
some MVFR or localized IFR visibility, mainly around sunrise with
any smoke trapped under the inversion.
&&
.UPPER AIR...
Issued at 1059 PM CDT Sat Jul 31 2021
No upper air flights are planned at this time.
&&
.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK 63 87 64 88 / 0 0 0 0
Hobart OK 61 89 62 90 / 0 0 0 0
Wichita Falls TX 64 88 65 90 / 0 0 0 0
Gage OK 60 88 62 90 / 0 0 0 0
Ponca City OK 61 86 62 87 / 0 0 0 0
Durant OK 68 90 67 91 / 10 0 0 0
&&
.OUN WATCHES/WARNINGS/ADVISORIES...
OK...None.
TX...None.
&&
$$
SHORT TERM...11
LONG TERM....01
AVIATION...26
Area Forecast Discussion
National Weather Service Reno NV
252 PM PDT Mon Aug 2 2021
.SYNOPSIS...
A drier southwest flow will decrease thunderstorm chances and
bring a return to afternoon breezes for the balance of this week.
An upper trough moving across northern California and the
northern Great Basin will enhance breezy winds by mid-week. This
will heighten fire weather concerns Wednesday into Thursday as the
airmass becomes drier under strengthening high pressure.
Temperatures will be near seasonal levels.
&&
.SHORT TERM...
Little needs to be changed for this forecast period except for the
abundant hazy sunshine across the region. The only exception will
be far northern Washoe County and to the south Mono-Mineral
Counties. What remains of instability and moisture from the recent
monsoonal surge could be just enough to produce an errant
thunderstorm or two over those areas into the early evening hours.
Outside this isolated activity high pressure will once again
exert its authority over the Desert Southwest and extend into
western Nevada and the eastern Sierra.
Tuesday will see temperatures rising back to near seasonal levels
for these opening days of August. Three-digit temperatures
reaching into the low 100s will again turn the burners on over the
lower NV valleys Tuesday and again Wednesday afternoon. This
upcoming quiet weather pattern will continue into the weekend.
The dry and stable conditions increasing across the region will
for the most part subdue any cumulus buildups beyond the fair-
weather variety seen each afternoon over higher elevation areas of
the Sierra.
Mid-level warming with the upper ridge building over the region
will put a hold on any thunderstorm development into the weekend.
Look for a return of late-day breezes with most gusts only
reaching into the 20-25 mph range. Wednesday may see higher gusts
to 30 mph over higher terrain areas north of Lake Tahoe. A weak
upper trough passing over the region later Wednesday evening will
increase momentum over higher ridgetops. This will increase fire
weather concerns for any new fire starts over those areas. The
general wind flow should decouple from valley locations and
decrease across Lassen/Washoe County to include higher valley
areas of the Surprise Valley later in the evening.
Smoke from the Dixie Fire may continue depending on fire activity
which could be enhanced Wednesday ahead of an upper short wave
entering later Wednesday. HRRR near-surface smoke simulations will
be watched closely to follow the expanding plume of smoke/haze
into the Basin and Range and Sierra Front overnight as the winds
return from the west and northwest. -Amanda
.LONG TERM...Thursday through the weekend.
Thursday will see a continuation of gusty winds, drier conditions,
and periods of critical fire weather concerns as an upper wave
lifts northeast across western NV. Whether we hit widespread
critical fire weather thresholds is a little more nuanced. Much of
the model guidance still brings the peak mid-level winds through
western Nevada overnight Wednesday into Thursday. This setup
could hinder the alignment of the upper-level winds with the
surface-level gradient winds into Thursday. As a result,
widespread critical fire weather thresholds could be delayed till
late morning and afternoon Thursday. Timing of the upper wave
passage is critical to the peak upper-level winds on Thursday
which will bring widespread critical conditions to the western
Sierra into the far western NV. Model guidance offers little to
the uncertainty regarding the timing of this upcoming event. At
this point, Hi-Res model guidance and short-term ensemble trends
will be important elements.
As for the sensible weather, the rest of the week is looking dry
with usual breezy afternoon winds and temperatures within a few
degrees of typical August levels. The overall zonal pattern over
the west looks like it will keep moisture and precipitation
generally out of the region, at least through the weekend and
into next week. Zach/Amanda
&&
.AVIATION...
A few convective build-ups are likely around the eastern Sierra
and possibly near the Oregon border through early this evening.
Only a slight chance of thunderstorms continues this evening as
drier more stable air moves in. A trough moving through northern
California Wednesday night will bring enhanced mid-level flow with
the possibility of minor to moderate shear, mainly to Sierra
terminals, Wednesday night. Enhancement to typical daily zephyr
winds on Wednesday and Thursday with gusts around 25-30kts.
Smoke from the Dixie Fire will continue to create reduced
visibility near KSVE. Otherwise, outside of wildfire smoke from
the Dixie, expect VFR through the rest of the week and into the
weekend. -Zach/Amanda
&&
.FIRE WEATHER...
Wednesday and Thursday are periods of concern for critical fire
weather conditions as troughing moves inland through northern
California increasing winds across the Sierra and western Nevada.
Previously, models were bringing the trough`s influence into the
region by Wednesday afternoon, but now that time frame has largely
shifted over Wednesday night into Thursday. Projected 700mb winds
show steady flow around 40-60 mph overnight north of Interstate 80
before the jet tracks across northeastern California and western
Nevada. Since the timing has slid and conditions for Wednesday are
more uncertain, we`ll mainly highlight concerns at this time, but
could issue a Fire Weather Watch in the next 24 hours if conditions
warrant.
* Winds: Wednesday winds could briefly reach critical thresholds
mainly for zones 270, 278, 458, and possibly 420. Gusts will
generally be 25-30 mph with 1-3 hours of gusts around 30 mph.
These conditions will also be more isolated, but could show where
lightning holdovers are. Given the expected position of the
trough, surface winds will likely decouple overnight allowing for
valleys and lower mid slopes to drop off following diurnal trends.
However, upper mid slopes and ridge tops above the inversion could
see increasing winds after midnight. This will also increase
ventilation and could increase activity on ongoing fires. Thursday
winds will likely be breezy to gusty for much of the region as the
trough pushes across and lifts; widespread gusts 25-35 mph.
Elevated winds should begin to surface by late morning resulting
in several hours of critical conditions along the Sierra, Sierra
Front, and locations north of Highway 50 in the Basin and Range.
* Temperatures/RH/Instability: Temperatures will be on the rise
early this week with afternoon highs approaching triple digits
while RH drops back to single digits and teens (not out of the
ordinary for early August). As such, surface instability will be
rather higher than the end of last week and cold result in upscale
growth of fire. However, the larger concern for instability
remains tied to the approaching trough for Wednesday and Thursday
where Haines values of 6 are forecast. Surface instability will
couple with deep vertical instability aloft and promote rapid fire
growth.
Winds return to more typical afternoon speeds by Friday, but there
are indications that another trough will move through Oregon over
the weekend into early next week. If this verifies, then another
period of breezy to gusty winds will occur with potential for more
periods of critical winds and RH. Boyd
&&
.REV Watches/Warnings/Advisories...
NV...None.
CA...None.
&&
$$
For more information from the National Weather Service visit...
http://weather.gov/reno
Area Forecast Discussion
National Weather Service Riverton WY
943 PM MDT Mon Aug 2 2021
.SHORT TERM...(This evening through Tuesday night)
Issued at 100 PM MDT Mon Aug 2 2021
Monsoon-type pattern continues to impact western and central
Wyoming today as a shortwave trough slowly moves southeastward
through central Utah. In addition, it appears that there is
another weak shortwave trough over western MT slowly moving
southeastward. Precipitable water values are still quite high
across the area, with 150%+ to the south and west, and 120% here
at the office in Riverton. Weak steering flow continues to be an
influence to high precipitation rates with the heavy/excessive
rainfall a good possibility for some areas across northwest WY as
well as south- central WY this evening. As of noon, thunderstorms
have already developed over the northern Absarokas and around
Star Valley. Most of the storms today will slowly move to the
north. Some areas could see 1-2" of rain over the next 24 hours,
with storms putting down 0.5-1.0" in less than an hour. Models
continue to show heavy precipitation later this afternoon and into
the evening hours, especially as the MT trough moves toward YNP.
While the most intense activity should diminish by midnight, rain
showers with isolated thunderstorms are likely to continue
overnight from NW WY toward Sweetwater County. The eastern half of
Sweetwater County has a good possibility of moderate rain after
sunset. Isolated rain showers could move SE off the higher terrain
and impact the lower elevations as well.
As the troughs move further SE and upper-level ridging strengthens
over the western US on Tuesday, the precipitation area will also
shift from about Cody toward eastern Sweetwater County and east of
the divide. Moderate rainfall is again expected in these area,
with lingering showers continuing into the evening from Johnson
County toward Rawlins. Due to the high pressure to the west, skies
will begin clearing across western WY by mid-morning Tuesday, with
the possibility of fog in the lower elevations due to recent
rainfall. Breezy northwest wind should develop by noon and
continue into the afternoon with gusts around 25 mph possible.
Tuesday night should then see mostly clear to partly cloudy skies
with generally light wind.
East of the divide continues with an Air Quality Alert due to
smoky skies and reduced visibilities. The smoke component of the
HRRR model shows slight improvement Tuesday, but continued
elevated levels. In addition, as the area of precipitation moves
off and the high pressure moves into western WY, areas of smoke
will return to northwest WY by Tuesday morning and spread SE
through the day.
.LONG TERM...(Wednesday through Monday)
Issued at 1218 PM MDT Mon Aug 2 2021
Northwest flow will start the period as an upper-level ridge builds
across the Four Corners; however, we`ll still remain under the
regime of the jetstream. This will keep us around average for
temperatures toward the end of the week. The upper-level ridge gives
way to a shortwave trough late Thursday into Friday. As this trough
and associated low move across the area, widespread precipitation is
expected. Winds are expected to increase ahead of the front. Showers
and storms are expected across the area but moisture is lacking in
the lower elevations and basins; therefore, could see virga showers.
This trough Thursday/Friday will be a precursor to an active weekend
where we`ll see another cold front Saturday into Sunday with similar
effects. Widespread PoP, gusty winds ahead of the front and virga
showers can be expected. After the second system, zonal flow
establishes itself across the region keeping the potential for
afternoon showers and storms across the higher elevations through
the end of the period with near-normal temperatures.
&&
.AVIATION...06Z Issuance
Mainly VFR conditions should prevail around the area through 06Z
Wednesday. A couple of sites that had rain today, mainly KJAC and
KRKS, may see patchy fog, but not enough confidence to include in
the TAFs. Showers will linger through the night in the west,
especially in the mountains where brief mountain obscurations are
possible. A weather system crossing the area will bring another
chance of showers and thunderstorms mainly to terminals East of the
Continental Divide tomorrow afternoon, but activity should be more
scattered than on Monday. Brief MVFR conditions and mountain
obscurations will be possible around any shower or thunderstorm
after 18Z Tuesday. All convection should end by around 04Z Wednesday.
&&
.FIRE WEATHER...
Issued AT 110 PM MDT Mon Aug 2 2021
Active weather pattern continues this afternoon and evening across
most of southwest and western WY. Storms today will produce
frequent lightning and potentially heavy rainfall. Concern today
is mudslides and localized flash flooding due to the heavy
rainfall, especially in areas that have received considerable
precipitation and terrain is steep. Models are focusing heavy
precipitation this afternoon and evening from west-central WY
north into YNP. In addition, Sweetwater County could get stronger
storms this evening and overnight. East of the divide should
remain relatively dry today with smoky skies, with perhaps
isolated showers near the mountains. The area of precipitation
moves slightly eastward on Tuesday, with storms producing heavy
rain possible before noon. During the afternoon and evening
hours, skies will start clearing across western WY with a breezy
northwest wind, and showers and thunderstorms will move east of
the divide. High pressure then moves in Wednesday and Thursday,
with more seasonal temperatures. Humidities will also decrease,
but not to critical levels.
&&
.RIW WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch until 11 PM MDT this evening for WYZ001>003-
012>016-019-023>030.
&&
$$
SHORT TERM...McDonald
LONG TERM...Vorst
AVIATION...Hattings
FIRE WEATHER...McDonald
Area Forecast Discussion
National Weather Service Springfield MO
656 PM CDT Mon Aug 2 2021
.SHORT TERM...(This evening through Tuesday)
Issued at 327 PM CDT Mon Aug 2 2021
Post-frontal surface conditions continue today across the Ozarks
with "cooler" temperatures, low humidity, and northeast surface
winds. Afternoon highs are expected to range from the upper-70s to
low-80s. Forecasted high temperatures today will likely run 5-10
degrees cooler than the climatological normal for August 2nd
across the Ozarks.
Broad troughing across the eastern half of the CONUS is promoting
northwesterly flow aloft across the region. A subtle disturbance
embedded within the flow may aid in additional shower development
through the early evening. To this point, most updrafts (showers)
have struggled to sustain in the presence of limited instability,
shear, and moisture along with dry mid and upper-levels. Given
steep (>7.0 C/km) low-level lapse rates, owing to cold
temperatures aloft, a few showers remain possible across
central/southern Missouri through this evening.
Northwest flow aloft will also continue aiding in the transport of
residual wildfire smoke from the western CONUS into the area.
Skies may be noticeably hazy (especially at sunset/sunrise)
through at least Tuesday. Otherwise, cool and comfortable
conditions can be expected Monday night into early Tuesday.
Overnight lows may dip into the upper-50s across portions of the
eastern CWA, especially in river valleys/bottoms. Low to mid-60s
overnight lows can be expected elsewhere across southern Missouri.
Tuesday will again feature limited chances for a couple of
showers across the CWA as a subtle disturbance overspreads the
area. Continued below normal temperatures are expected on Tuesday,
with highs in the low to mid-80s
.LONG TERM...(Tuesday Night through Monday)
Issued at 327 PM CDT Mon Aug 2 2021
Below normal temperatures sustain into the mid-week, with daily
highs in the mid-80s and overnight lows in the low to mid-60s
through Thursday. Potential exists for lingering hazy skies
into Wednesday, as the area remains squarely in the northwest flow
aloft regime. Limited PoP chances exist for Thursday afternoon/evening
(mainly across the northern CWA) as a weak shortwave trough looks
to move across the southern Corn Belt.
A pattern shift towards warmer and more humid conditions is
looking possible from late week into this weekend.
Ensemble/cluster guidance depicts a rather pronounced disturbance
moving into the Pacific Northwest late this week. This may help to
breakdown/deamplify the western CONUS ridge some, and promote a
more zonal flow across the northern two thirds of the CONUS. With
850 mb temperatures once again warming to 20-23C across the
region, daily highs in the upper-80s to low-90s will be possible
Friday into the weekend. Ensemble guidance currently doesn`t
highlight robust precipitation chances this weekend, though this
will need to be monitored in future forecasts.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 649 PM CDT Mon Aug 2 2021
KSGF/KJLN/KBBG tafs: Hazy/smoky conditions with high end MVFR/low
end VFR cat conditions will continue for much of the period, but
some indications are that the overall visibility may improve
slightly late in the period or just after (trends in HRRR smoke
models). Weak high pressure to the north will help maintain a
general modest northeast sfc flow.
&&
.SGF WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&
$$
SHORT TERM...Ungar
LONG TERM...Ungar
AVIATION...DSA