Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 07/22/21
Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
915 PM CDT Wed Jul 21 2021
.UPDATE...
Issued at 912 PM CDT Wed Jul 21 2021
An area of thunderstorms that developed across the far
southwestern part of the CWA has now begun to dissipate and track
southeastward, and looks to be out of the area in an hour or so.
The showers over the far east are also on their way out of the
CWA, so have removed POPs there for the remainder of the nighttime
hours. No changes made to winds or temperatures at this time.
&&
.SHORT TERM...(This Evening through Thursday)
Issued at 255 PM CDT Wed Jul 21 2021
Still widely scattered showers/sprinkles occurring over parts of
the north central/northeast CWA in response to shortwave energy
aloft. The main shortwave drops southeast out of North Dakota
influencing more of northeast South Dakota and west central
Minnesota tonight. This forcing combined with a 30+ KT low level jet
and theta-e ridge should be enough to increase coverage of showers
and thunderstorms later tonight through early Thursday
morning...mainly east of the James River Valley.
Hot, humid conditions will be the concern going into Thursday. As
per previous forecasts, held back a couple of degrees on the
baseline guidance MaxT output. The forecast has had a slight warm
bias, likely due to influence of smoke, and the HRRR vertically-
integrated smoke is again hinting at a wide swath of smoke streaming
over the region again Thursday afternoon. Dewpoints will be in the
60s pushing apparent temp values to borderline heat advisory
criteria. Due to uncertainly of smoke and mixing potential,
collaboration with surrounding offices was to hold off on a headline
for now.
.LONG TERM...(Thursday Night through Wednesday)
Issued at 255 PM CDT Wed Jul 21 2021
The extended portion of the forecast will remain relatively
unchanged from the previous forecast package. The upper level ridge
that`s been in place for quite some time across the western CONUS
extending ewd into our region will get flattened somewhat on Friday
as an upper level shortwave and frontal boundary push through the
Dakotas. This will bring some precip chances to the area with best
opportunities for seeing something in locales farthest north. So,
not everyone will see rainfall from this system. By early next week,
the ridge builds back in and amplifies across the western CONUS once
again. Temperatures are only expected to remain well above normal
through the entire period. Some areas may stay relatively cooler in
the 80s to around 90 during the upcoming weekend, but more
widespread 90s look to return next week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday Evening)
Issued at 623 PM CDT Wed Jul 21 2021
Terminals KABR,KATY,KPIR,KMBG
For the most part, VFR conditions will prevail across the area
tonight and through the day Thursday. A few scattered showers are
possible tonight across parts of the southern and eastern part of
the CWA.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
&&
$$
UPDATE...Parkin
SHORT TERM...Serr
LONG TERM...Vipond
AVIATION...Parkin
Area Forecast Discussion
National Weather Service Denver/Boulder CO
840 PM MDT Wed Jul 21 2021
.UPDATE...
Issued at 826 PM MDT Wed Jul 21 2021
The strength and coverage of the thunderstorms will continue to
decrease through the evening. Best coverage the rest of the
evening will be south and east of Denver. Lingering showers and
thunderstorms in the mountains as well, with some residual showers
continuing after midnight. The Flash Flood Watch has been allowed
to expire. There are a couple of Flash Flood Warning ongoing, but
those will likely be allowed to expire by 915 pm.
&&
.SHORT TERM...(This evening through Thursday)
Issued at 142 PM MDT Wed Jul 21 2021
Water vapor continues to show a good plume of monsoon moisture
stretching across most of the state, with convection blossoming in
the past couple of hours. An 18z sounding launched just west of
Fort Collins came in with a precipitable water value of 1.18"...
which is a remarkable increase compared to values over the plains
yesterday. In the higher terrain both precipitable water (near 1")
and 700-500mb specific humidity (~7g/kg) are above the 90th
percentile. SPC Mesoanalysis indicates MUCAPE greater than 750
J/kg across the high country, and these two factors have largely
led to widespread showers and thunderstorms this afternoon. There
has been enough flow aloft... roughly 20kt at 500mb... to keep
storms moving just fast enough to avoid heavy precipitation totals
across our burn areas. Not much is expected to change over the
next few hours, with widespread showers and storms over the high
country. Current radar trends and some model guidance does favor
areas along and south of I-70 through the evening, but flash
flooding will continue to be a concern across all of our burn
areas through tonight.
Over the plains... the aforementioned sounding near FNL showed
very little surface-based instability present, but we should see
continued destabilization over the next hour or two and at least a
couple of storms developing along the I-25 corridor. The HRRR has
continued to delay when this will happen, but there`s enough
confidence to have some PoPs into the plains this evening. Briefly
heavy rain, lightning, and some gusty winds would be the primary
impacts for the urban corridor.
Tonight should be fairly quiet, but another round of afternoon
storms is expected tomorrow. The best moisture and instability
will be pushed back to the west of our forecast area... closer to
Grand Junction. This should diminish the heavy rainfall threat a
little bit, though there will be continued concerns for the burn
areas across our high terrain. WPC has maintained a marginal
Excessive Rainfall Outlook for along and west of the divide... and
we could see localized flash flooding issues if storms form over
the wrong spots. Across the plains, it should remain hot and dry,
with highs in the mid 90s. A few showers may attempt the journey
off the Foothills, but otherwise no precipitation is expected
along and east of I-25.
.LONG TERM...(Thursday night through Wednesday)
Issued at 142 PM MDT Wed Jul 21 2021
An elongated upper level ridge of high pressure will stretch from
Central California across Eastern Colorado Thursday night through
Friday as an easterly wave moves west across Southern New Mexico.
The plume of monsoonal moisture will continue to circulate around
the high with PW`s ranging between 0.75" and 1.00" in the high
country. This abundant moisture combined with daytime heating and
an upper level disturbance moving across the area will result in
scattered to numerous slow moving showers and storms in the high
country. Some of the storms will be capable of producing locally
heavy rain and flash flooding, especially across the burn areas.
Further east across the plains PW`s are also high with values
ranging between 1.00" and 1.35" Despite the high moisture values,
meager instability along with a mid level cap should result in
limited precipitation chances.
Over the weekend, the easterly wave over the Desert Southwest tries
to cut off the monsoonal flow into the western half of Colorado.
This may reduce the flash flood threat in the northern mountains
somewhat. However, there could still be pockets of higher PW which
could contribute to some stronger storms and locally heavy
rainfall. A weak frontal surge progged to move across
northeastern Colorado on Saturday may provide a slight upslope
component and slightly cooler temperatures on the plains. The NBM
is forecasting a max temperature of 89 degrees at DIA on Saturday
which would end our 90 degree streak if it verifies. A weaker cap,
combined with better instability and some upslope flow may result
in a better chance for precipitation on the plains.
Early next week, ensembles are showing the upper ridge rebuilding
over Colorado which would result in hotter and drier weather across
the forecast area. This is vastly different than yesterday`s runs
which had shifted the upper high eastward into the Southern Plains
States and had the plume of monsoonal moisture flowing into Colorado
from the Desert Southwest.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 826 PM MDT Wed Jul 21 2021
South/southwest winds will continue the rest of the night, but
should weaken later this evening as the rest of shower activity
south of Denver tapers off. VFR the rest of tonight through
Thursday afternoon.
&&
.HYDROLOGY...
Issued at 826 PM MDT Wed Jul 21 2021
The Flash Flood Watch was allowed to expire at 8 pm this evening.
Weakening showers/thunderstorms the rest of this evening. The
A Flash Flood Warning will continue over the western half of the
East Troublesome burn area until 915 pm mdt this evening, although
the thunderstorm activity does look to have shifted south of the
warning area. Additional rainfall this evening will be light.
Any lingering thunderstorms will diminish this evening, with
quiet conditions overnight.
Thursday will see a limited threat of burn area flash flooding as
the best conditions for heavy rainfall. Monsoon moisture will
still be around the area, though it does decrease somewhat
slightly compared to today. Models generally show less
precipitation, and HREF 6hr maxQPF is not nearly as high as today.
However, storm motions are likely to be a bit slower with weaker
flow aloft. If slow moving thunderstorms develop over the burn
areas, flash flooding would certainly be possible. Stay tuned.
On Friday, there will be high levels of moisture in place as
precipitable water values increase. Moisture levels may decrease
somewhat on Saturday across the northwestern sections of the
forecast area. A shortwave trough moving across the region on
Friday and upslope flow developing on Saturday will aid in the
forcing for storms to form. Scattered storms will form over the
burn areas with slow storm motion. Will probably need to upgrade
some of the burn areas to an elevated threat on Friday.
Sunday and into next week, the chance of storms will decrease with
warmer and drier air moving in. The threat for flash flooding will
decrease as well.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...Cooper
SHORT TERM...Hiris
LONG TERM...Kalina
AVIATION...Cooper
HYDROLOGY...Hiris/Cooper
Area Forecast Discussion
National Weather Service Des Moines IA
636 PM CDT Wed Jul 21 2021
.DISCUSSION.../Tonight through Wednesday/
Issued at 212 PM CDT Wed Jul 21 2021
Forecast Highlights:
-- Isolated showers or storms northeast through early evening
-- Patchy fog possible toward daybreak Thursday
-- Summery conditions with hottest days being Saturday and then
toward middle of next week
-- Not a dry 7 days areawide, but little in the way of high
confidence, widespread rainfall over the period
Details: The flow over the region remains weak with the 12z KOAX
RAOB observing winds at 850, 700, and 500mb somewhere between the
10th and 25th percentile with forecast soundings across central Iowa
showing winds below 600mb less than 10 knots. GOES-East imagery
shows the jet stream flow entering over the west central US and
then moving poleward into Saskatchewan before diving southeastward
into the northern Middle Atlantic States. Iowa is in the light
northerly or northwesterly flow aloft. At the surface, a weak
boundary is stretched from west central Minnesota into
southeastern Iowa with winds over western and central Iowa from
the southwest and over northeastern Iowa generally from the east.
This weak boundary/wind shift has fostered a few isolated showers
and there is a wind gust potential if a storm collapses with low
bulk shear and downdraft CAPE values between 800 and 900 J/kg per
SPC mesoanalysis. This wind shift over our northeast counties is
also one ingredient for potential funnel clouds this afternoon and
early evening, which includes the area around Waterloo. SPC
mesoanalysis is not pinging the non-supercell tornado parameter
and is just starting to showing some enhanced stretching
potential. However, SPC mesoanalysis is showing 0-3km MLCAPE with
75-100 J/kg presently with it expected to increase per RAP
forecast. Further, lapse rates should steep through the afternoon.
The showers/storms and any funnel cloud reports will wane early
this evening and attention will once again turn to fog development.
Most of the fog has been light above 5 miles with isolated
pockets of lower visibility and expect that tomorrow morning as
well. As for high level smoke that has been creating a hazy sky,
the higher concentration of smoke today is over eastern Iowa with
lighter concentrations elsewhere in the state. A wave of higher
concentration of high level smoke arrives late Thursday afternoon
over northwestern Iowa. Highs should still reach well into the
80s to around 90 degrees.
A weak surface boundary will approach the state as a mid-level
trough moves over central Canada with its southern edge into North
Dakota and Minnesota on Friday. Temperatures ahead of this
boundary will be a bit higher than Thursday in the 90s in most
places with heat index values topping well into the 90s to near
100 degrees. This boundary will foster isolated storms along it,
though as it moves toward the Iowa border, it will encounter more
of the warm air aloft associated with the ridge. The deterministic
global models continue to indicate 700mb temperatures around 11C,
which may stunt development into northern Iowa until it cools
slightly overnight Friday. The number of ensemble members pointing
toward light QPF near the Iowa/Minnesota border is growing with
about half of the Canadian members, a third of GFS members, and
most ECMWF members signaling this from last night`s 00z run. For
now, do not see a reason to deviate from initial NBM guidance and
have continue with PoPs over northern Iowa Friday night into early
Saturday. This surface boundary will gradually dissolve as it
slowly slips southward through the state Saturday into Sunday with
whatever is left of this boundary settling near the Iowa/Missouri
border by Monday morning. 700mb temperatures should keep the
precipitation coverage to a minimum over the weekend, but cannot
rule out an isolated storm near the boundary with this shown
amongst some ensemble members of the CMC and GFS. Temperatures
will be well into the 90s on Saturday with heat index values of 95
to near 105 degrees. Will have to watch this day as it will be
near heat headline criteria. Sunday will be slightly less hot over
northern Iowa with similar temperatures elsewhere.
Deterministic models show varying strengths, but agree that a
shortwave trough will be moving into Iowa early next week overtop
the ridge. The placement of the boundary and the shortwave will
dictate where storms will be located, but chances at this point look
highest over southern Iowa Sunday night into Monday. Thereafter, the
western US ridge is expected to build toward Iowa with the 500mb
ensemble mean of the GEFS and ECMWFEns showing the 594dm height
contour building into at least southwest if not southern Iowa by
Thursday with the CMCE just south of the state. Chances for any
storms would be relegated to any wave coming overtop of the ridge
with impact likely over our northeastern or eastern areas, but
that is not likely at this point. 850mb temperatures will rise to
between 22-24C on Wednesday and 24-26C on Thursday, which will
translate to surface temperatures into the 90s and in most cases
well into the 90s. The 75th percentile of NBM would push many
sites to or above 100 degrees. Heat index values will likely be
several degrees either side of 100 given current forecast highs.
This heat, combined with ensemble mean rainfall through the middle
of next week around half an inch, would not be welcome for
ongoing drought conditions.
&&
.AVIATION.../For the 00Z TAFS through 00Z Thursday evening/
Issued at 635 PM CDT Wed Jul 21 2021
Aviation weather continue to be relatively tranquil with
widespread VFR conditions for much of the period. There may be
some very patchy fog overnight with light southeast to south
winds.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
DISCUSSION...Ansorge
AVIATION...Cogil
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1038 PM EDT Wed Jul 21 2021
.SYNOPSIS...
Somewhat drier air arrives from the north on Thursday along
with more sunshine. Temperatures will rebound to near-normal or
even slightly above by late week. Afternoon and evening shower and
thunderstorm chances gradually increase again over the weekend.
&&
.NEAR TERM /THROUGH THURSDAY/...
As of 1030 PM: The forecast looks on track, so no big changes with
the evening update. A smoky haze will likely linger across the North
Carolina zones well into the night, with some fog developing in the
mountain valleys. A couple of showers linger along the escarpment
in Rabun and Oconee counties, but should ash out soon as we become
more stable.
The next 24 hours look uneventful as we should remain under a
dry NW flow that will be inhospitable to deep convection. A sfc
high over the Great Lakes/Midwest should nose down into the area
tonight, with clear sky and light wind that should be conducive
to fog development in the mtn valleys. Low temps will be close to
normal. The sfc high moves a bit to the east on Thursday, but should
keep the deeper moisture suppressed to the south. Will not rule
out an isolated shower over the higher terrain Thursday afternoon,
but expect little chance of deep convection east of the Blue Ridge
as a low level cap should keep the lid on it. High temps should
be a few degrees above normal. The HRRR suggests the smoke plume
will remain aloft through the day, so some near-sfc haze could
come into play again, but for now this was left out of the fcst.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
As of 120 PM EDT Wednesday...A broad east coast trof will slowly
lift and pull northeast thru the period. This will allow a supTrob
high to dominate the pattern and keep a rather suppressive regime in
place. Frontal forcing will remain south of the FA leaving weak flow
thru the column north and not much chance for severe tstms. There
will be general thunderstorms possible each afternoon as moist e/ly
flow interacts with a destabilizing atmos each day, however,
coverage will be limited and favor the higher terrain. The airmass
will not change much, so expect smoke-induced hazy conds to continue
thru the period. With good insol, max temps will have no problem
reaching near normal levels, while mins also hover arnd normal.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
As of 200 PM EDT Wednesday...No major changes were made to the ext
fcst. SubTrop ridging will continue to dominate the pattern and keep
a low shear and suppressed airmass in place. This will limit
convective activity Sun and keep the best chance for pulse storms
across the mtns Sun afternoon. Still expect hazy conds to continue
as the airmass mixes very little. On Mon, the models agree well with
lowering h5 heights and a back door cold front working in from the
north. This front will be weakly forced and have limited moisture to
work with early on. The front now looks to stall across the fcst
area thru Tue, possibly into Wed, while llvl moisture flux increases
off the Atl and the GOM. So, the front shud become more active
possibly leading to localized hydro issues beginning Tue as PWATS
hover arnd 1.75 inches each day. Max and min temps will remain arnd
or a little below normal each day as cloud cover and areal precip
increases.
&&
.AVIATION /03Z THURSDAY THROUGH MONDAY/...
At KCLT and elsewhere: Satellite imagery shows a smoke plume over
the area that will move little thru the period. The HRRR shows some
increase in near-sfc smoke density late tonight into Thursday, so
expect some vsby reduction in HZ possible, especially across the
NC sites and near GSP. Confidence is still low on anything lower
than VFR. The exception is KAVL, where some BR/HZ may form, as
fog develops in the mountain valleys. Similar conditions expected
tomorrow, with few-sct high-based cu and isolated showers and
perhaps a tstm or two in the high terrain. Coverage looks too
low for any TS mention in any of the TAFs. Winds will be light
thru the period, shifting around the dial from NW to NE tonight,
then SE/SW Thursday aftn.
Outlook: Smoke from western wildfires should improve by early
Friday. Dry conditions will continue through late week, but with
early morning fog or low stratus possible. Diurnal thunderstorm
chances will steadily return into the weekend.
Confidence Table...
02-08Z 08-14Z 14-20Z 20-00Z
KCLT High 100% High 100% High 100% High 100%
KGSP High 100% High 100% High 100% High 100%
KAVL High 100% High 93% High 100% High 100%
KHKY High 100% High 100% High 100% High 100%
KGMU High 100% High 100% High 100% High 100%
KAND High 100% High 100% High 100% High 100%
The percentage reflects the number of guidance members agreeing
with the scheduled TAF issuance flight rule category. Complete hourly
experimental aviation forecast consistency tables are available at
the following link:
www.weather.gov/gsp/aviation
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...None.
SC...None.
&&
$$
SYNOPSIS...DEO
NEAR TERM...ARK/PM
SHORT TERM...SBK
LONG TERM...SBK
AVIATION...ARK
Area Forecast Discussion
National Weather Service Indianapolis IN
1140 PM EDT Wed Jul 21 2021
...Updated Aviation Discussion...
.Forecast Update...
Issued at 931 PM EDT Wed Jul 21 2021
Forecast is in good shape. Much of the cumulus are dissipating, but
some will likely linger as stratocumulus overnight. Areas of high
clouds also continue to move through. In addition, smoke continues
across the area, with some stations still reporting 5SM visibility.
With the smoke and aforementioned clouds, will continue with a
partly cloudy forecast. Some patchy ground fog will also likely
develop overnight with light winds, but kept things simple and
continued to only mention haze. Not expecting any widespread dense
fog.
Isolated convection across Illinois is moving south and should
remain west of the area. Temperatures look good so no significant
changes were needed.
&&
.Short Term...(This evening through Thursday night)
Issued at 247 PM EDT Wed Jul 21 2021
Dry weather is expected to continue for several more days as Indiana
remains within an area of northwest flow around a broad ridge across
the Intermountain West. Visibilities have remained generally
between 5 and 7 miles due to smoke moving from fires across the
Western United States and Southern Canada through the jet stream
to central Indiana. The boundary layer today has been up to around
850mb with a cap above it which has further allowed for smoke
aloft to mix to the surface. During the overnight hours, a surface
inversion should limit the downward mixing, but expect that to
pick up again tomorrow.
HRRR vertically-integrated smoke parameters show that estimated
smoke density will be not quite as intense tomorrow, so not
expecting quite as much impact to surface visibility. Afternoon
temperatures and humidity will be fairly reasonable for this time of
the year with highs topping out in the low to mid 80s with dew
points in the low to mid 60s. The aerosols associated with the smoke
may have a minor influence in keeping the temperatures from rising
higher.
During the late overnight hours Thursday night, can`t rule
out a complex of thunderstorms skirting the northern counties as a
weak shortwave moves along the ridge. Best chances look to be later
in the day on Friday when a plume of moisture associated with the
wave moves through. Clouds will also be on the increase ahead of the
wave.
&&
.Long Term...(Friday through Wednesday)
Issued at 247 PM EDT Wed Jul 21 2021
The long term period begins with an upper low off the coast
northeast of Maine, and a broad upper ridge over much of the central
U.S. As the long term wears on, the axis of the upper ridge builds
back toward the intermountain west before again slowly drifting
eastward over the central and northern plains.
At the surface, high pressure over the area on Friday begins to
slide to the east, allowing the tail end of a cold front to eek
through the area Saturday afternoon/Saturday night. Very little
reflection of anything in the upper pattern showing up in the
surface pattern over central Indiana through at least mid week.
Northwesterly to westerly flow aloft will be the rule, with
generally southwesterly component flow at the surface to bring more
heat and humidity into the area. High temperatures will climb into
the upper 80s to lower 90s and heat index values in the upper 90s to
low 100s, and possibly higher. Precipitation chances through the
long term will mainly be driven by diurnal heating for late
afternoon/evening storms, and then by quick hitting shortwaves on
northwest flow that prompt MCS development upstream, and these ride
the periphery of the ridge then into parts of central Indiana. With
this said, the better chances for these more organized ridge riders
appears to be north of the forecast area this set of runs, but will
have to monitor. Confidence is low in precip at any given time given
the overall high pressure pattern and variability in timing of
individual shortwaves, but a bit higher for Saturday night with the
additional forcing of the cold front. Unlikely that coverage would
be more than scattered though.
.
&&
.Aviation...(06Z TAF Issuance)
Issued at 1140 PM EDT Wed Jul 21 2021
IMPACTS:
- Occasional MVFR conditions in smoke/haze/ground fog expected
through the night. Locally IFR visibility in fog possible at some
sites.
- Near MVFR conditions in smoke/haze during the day Thursday.
- Light winds veering to the southeast by Thursday afternoon.
DISCUSSION: Some stratocumulus will linger through the night. More
cumulus will pop up on Thursday.
MVFR visibility should become predominant at all sites overnight as
some fog develops. Lower visibility is possible at mainly the rural
sites. More haze/smoke will keep visibility near MVFR territory on
Thursday.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Update...50
Short Term...White
Long Term...CP
Aviation...50
Area Forecast Discussion
National Weather Service Marquette MI
647 PM EDT Wed Jul 21 2021
.SHORT TERM...(This evening through Thursday)
Issued at 305 PM EDT WED JUL 21 2021
Clear skies are slowly giving way to clouds out west as a shortwave
slowly progs southeastward near the WI border. Otherwise, today has
been fairly calm, with temperatures already reaching 70F at the
office as ridging has limited cloud cover over most of the CWA. This
lack of cloud cover and WAA from the Western U.S. have helped
temperatures be warmer than yesterday. Winds have been fairly light
today, with the lakebreezes from both of the Great Lakes dominating
wind speed and direction for much of the area. Precipitation is
currently staying west out of our area, but that may change come
later tonight as the shortwave continues towards the southeast.
Cloud cover is expected to slowly increase from west to east
throughout the night, with only the far east expected to have sky
conditions less than BKN. Therefore, kept the minimum temperatures
from the previous shift, save for lowering the far eastern lows by 2
degrees to account for the lesser amount of cloud cover. Some
showers and a rumble of thunder or two could be possible late
tonight over the far west near Ironwood as the shortwave slowly
brings some precipitation over the area. Other areas in the west and
central also have a very small chance of precipitation, but, given
that model soundings are showing a decent dry layer that needs to be
overcome, I don`t think that any precipitation that falls will make
it to the ground (save for maybe over the far west), at least during
the overnight hours.
Rain chances should improve across the rest of the area Thursday as
the air above the ground moistens and another shortwave immediately
follows behind the previous one. Thunder also seems possible in the
west during the afternoon hours Thursday; however, there shouldn`t
be anything that is severe, as instability is fairly weak and bulk
shear magnitudes are not too impressive. Temperatures may be a
little warmer Thursday than what they are today; while widespread
cloud cover is expected across the area, there should be some slight
WAA, which, if model guidance is to be trusted, should give us
slightly warmer high temperatures Thursday. The HRRR also has haze
over the west Thursday, but given the chance of rainfall across the
area, decided not to put the haze chances in the grids.
.LONG TERM...(Thursday night through Wednesday)
Issued at 442 PM EDT WED JUL 21 2021
Models indicate that mid/upper level ridging over western North
America will deamplify some during the rest of this week into early
next week. The result will be a more progressive flow regime
developing along the U.S./Canada border region as a series of
shortwaves eject eastward from mean troughing just off the west
coast of Canada and bring periodic chances for showers to the Upper
Great Lakes late this week into next week. As for temps, near to
slightly blo normal temps will trend upward to above normal
beginning Fri and continue into next week. There will probably be
some hot days in the mix through next week, but the overall
progressive flow regime in the vicinity of the U.S./Canada border
should prevent any prolonged periods of hot conditions from setting
up across Upper MI.
The shortwave aiding shower activity over mainly west and south
central portions of the cwa on Thu will shift se of the area by Thu
night, resulting in showers ending for the most part. Although no
apparent shortwave will be approaching during the night, weak
isentropic ascent and some instability along the warm front
lingering to the sw may still support a few showers/maybe some
thunder during the night, mainly over west and south central
portions of the cwa.
Fri into Sat, attention turns to the shortwave moving along the
U.S./Canada border with the associated cold front likely sweeping
across the fcst area late Fri night/Sat. Models still have a good
signal for shra/tsra with this feature. In addition, models indicate
sufficient instability (MUCAPE off NAM soundings generally 1000-1500
J/kg) and deep layer shear (35-40 kts) for severe thunderstorm
potential as well. If front is slow enough and hasn`t exited to the
se by Sat afternoon, additional shra/tsra will likely develop over
the s central/se fcst area in the afternoon where instability could
build near 1500 j/kg through the day along the frontal boundary.
These storms could also pose a severe risk. PWATs fcst up near 2
inches will also result in locally heavy rain, especially with
thunderstorms.
Mainly dry weather should then follow Sun/Mon as sfc high pressure
builds in behind Saturday`s front. High temps will be in the 80s,
but could push 90F on Mon, depending on how quickly WAA develops
into the Upper Lakes ahead of the next shortwave/cold front, which
is due to move in Tue and will bring the next chc of shra/tsra.
Shra/tsra could even linger into Wed from this shortwave/frontal
system.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 647 PM EDT WED JUL 21 2021
VFR conditions are expected at KSAW throughout the period and at
KCMX and KIWD for most of the period. KCMX and KIWD will go
temporarily MVFR late Thu morning into Thu afternoon. Shower
chances are small enough to go with VCSH at this time.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 305 PM EDT WED JUL 21 2021
Expect winds generally to be 20 knots or less throughout the period
across the lake. The only exception may be Friday night, where
southerly winds across the eastern may reach up to 25 knots at most.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...TAP
LONG TERM...Voss
AVIATION...07
MARINE...TAP
AREA FORECAST DISCUSSION
National Weather Service Morristown TN
910 PM EDT Wed Jul 21 2021
.UPDATE...
EVENING UPDATE.
&&
.DISCUSSION...
No changes to the forecast for this evening update. Main weather
story continues to be the smoke/haze lingering around the area
overnight and into tomorrow. Surface observations are still
reporting decreased visibilities in many areas. Some of that
might mix out tonight, but expect another hazy day tomorrow, but
hopefully less so than what we saw today.
ABM
&&
.AVIATION...
00Z TAF DISCUSSION.
Quiet weather expected the rest of the evening with the main
aviation concern being smoke/haze from the fires. Most weather
stations are picking up on very light haze this evening, and think
that smoke will mix out overnight. Should re-intensify tomorrow,
but the heaviest smoke will likely be further west in TN. Kept 6SM
smoke in the TAFs to hint at haze expected all day, but think that
visibilities will hopefully be a bit higher than that most of
tomorrow.
ABM
&&
.PREV DISCUSSION...
/ISSUED 724 PM EDT Wed Jul 21 2021/
SHORT TERM... (Tonight and Thursday)...
Haze will continue to be an issue this period as the high pressure
ridge over MO/IL today will slowly shift east to IL/IN tomorrow. As
a result, a northerly low to midlevel flow will persist, and
continue to spread smoke from wildfires in Canada southward. The
HRRR near-surface smoke concentrations do appear lower for our area
tomorrow, with the highest concentrations shifting to our west over
Middle TN. Some haze will be mentioned in the Wx grids for tonight
and tomorrow morning, particularly across the northern half, and
for the Plateau tomorrow morning. The axis of deformation that
has been a focus for convection today across N GA and N AL will
push southward tomorrow, taking any chance of showers with it. Dry
air aloft and subsidence will result in a dry day tomorrow, with
highs in the upper 80s to lower 90s.
DGS
LONG TERM... (Thursday Night through Wednesday)...
Key Messages...
1. Drier conditions to begin the period. Chances of precipitation
will gradually increase, especially early next week, as moisture
becomes more available and locally heavy rainfall becomes a
possibility.
2. Temperatures will continue to increase into the weekend and early
next week. Increasing moisture by the end of the weekend will bring
very humid and muggy conditions with heat indices approaching the
mid to upper 90s for the Valley.
Discussion...
-Thursday Night through Sunday-
An upper level ridge will be located over the Central Plains with a
positively tilted trough positioned along the far Northeastern
Seaboard to begin the long term period Thursday evening. At this
time, H5 heights will be around 5920m. Additionally, PWAT values
will be around the 1.3-1.5in range. As a result, relatively drier
conditions, sunny skies, and warm temperatures will be the primary
theme for the duration of this period. The potential for
precipitation will be restricted to the higher elevations and far
southern portions of the valley where moisture will be more
favorable. By Friday, the surface high pressure will begin to shift
east from the Ohio Valley with flow aloft out of the northwest.
Models are suggesting a weak shortwave disturbance moving through
the area, however, overall subsidence associated with the high
pressure and the lacking moisture will again keep PoPs more focused
around the southern valley and areas of higher elevation. In far
northeast TN and southwest VA, PWAT values may drop as low as 1.0in
during late Friday night into Saturday morning. This is approaching
the lower 10th percentile according to sounding climatology.
For the end of the weekend, the surface high continues to progress
towards the eastern seaboard as the flow becomes southeasterly and
will aid in providing more moisture into the region overall. The
moisture along with temperatures in the low to mid 90s associated
with the amplifying upper level ridge will favor more of a typical
terrain-driven summer shower and thunderstorm pattern at this time.
-Monday through Wednesday-
Through the latter part of this long term period, the area will
continue to see height rises along with positive thickness
advection. However, an amplifying upper level low northeast of the
Great Lakes region will bring a cold front through the Ohio Valley
at this time. With PWATS approaching 2.0in, better coverage of
showers and thunderstorms are looking more probable out ahead of the
front, especially on Tuesday. Additionally, increasing dewpoint
temperatures will make for more muggy conditions and increasing heat
indices. Depending on how the precip coverage plays out,
temperatures on Tuesday and Wednesday may be a degree or two cooler
than the previous days, although, still very hot.
KRS/DH
&&
.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN 71 92 70 91 71 / 10 10 10 20 0
Knoxville McGhee Tyson Airport, TN 68 90 67 92 69 / 0 10 10 10 0
Oak Ridge, TN 68 91 67 91 68 / 0 10 10 10 0
Tri Cities Airport, TN 62 88 62 90 63 / 0 0 10 10 0
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...NONE.
VA...NONE.
&&
$$
Area Forecast Discussion
National Weather Service Spokane WA
251 PM PDT Wed Jul 21 2021
.SYNOPSIS...
Dry and breezy winds this evening will raise concern for wildfires
and a Red Flag Warning remains in effect through late evening for
much of the Inland Northwest. Thursday and Friday will feature
high temperatures in the 80s and low 90s. Above average readings
will return this weekend and early next week with highs well into
the 90s.
&&
.DISCUSSION...
Tonight through Friday: A dry slot on the south side of an upper
trough passing over British Columbia will sweep across Central
Washington this afternoon before sliding east into the Idaho
Panhandle this evening. Drier air and tight west-east pressure
gradients will promote breezy to locally windy conditions and low
relative humidity this evening with Red Flag Warnings in place
for most of Eastern Washington and North Idaho. Ongoing fires will
likely become increasingly active into the early evening. HRRR
smoke model is showing a LARGE AREA of smoke from fires over the
north Cascades and southern BC tracking southeast into northern
Washington tonight into Thursday morning. The highest smoke
concentrations are projected from Waterville to Coulee City to
Spokane/Coeur d`Alene north to the Canadian border including the
Methow Valley.
Thursday and Friday westerly flow lingers over the area with a
continued dry atmosphere leading to low relative humidity, normal
temperatures, and locally breezy conditions especially near the
Cascade gaps. Smoke models suggest another round of smoke for
northern WA Thursday Night into Friday morning, although possibly
not penetrating as far south as Thursday morning. JW
Saturday and Sunday: Afternoon temperatures in the 90s will return
on Saturday. The upper trough helping cool our region down close
to average will be replaced by a flat ridge of high pressure on
Saturday allowing heat over California and the Great Basin to
return to our region. Sunday will be even warmer with mid to upper
90s expected for central Washington, the Okanogan Valley, Lewiston
area, and the lowlands of northeast Washington. Our temperature
forecast largely assumes that smoke won`t have a significant
effect on temperatures which may not be a viable assumption.
Winds in the low and mid levels are expected to mainly be westerly
this weekend pushing smoke from fires in southwest Oregon and
northern California south of our region. However, the increasing
size of fires in the upper Methow Valley is concerning. Overall,
there should be enough westerly flow to provide decent ventilation
across our region, but locations near fires like Winthrop and Omak
may experience thick smoke at times. We may also be dealing with
some new fires from the lightning that occurred this morning in
southeast Washington and the Idaho Panhandle. Hold over fires may
perk up in the next few days with occasional breeziness and
persistent low humidity.
Monday and Tuesday: We will be keeping a close eye on monsoonal
moisture over the Great Basin and southern Oregon early next week.
At this time, it looks like far southeast Washington and the
southern Idaho Panhandle will be the most likely areas for
scattered showers. Further north, places like central and
northeast Washington look to be under enough dry southwesterly
flow to remain free of showers and potential lightning, but we
will need to watch this closely. Monday and Tuesday will remain
quite warm with widespread 90s for high temperatures. /GKoch
&&
.AVIATION...
18Z TAFS: Thunderstorms have pushed east of the region this
morning although still can not rule out a few strikes this morning
mainly east of KCOE. A tightening pressure gradient with cold
front passage will result in increasing westerly winds through the
afternoon and into this evening with gusts of 20-30 kts expected.
The winds and dry conditions today will also result in increased
fire activity. Established fires in the Methow Valley is expected
to produce thick smoke near the Methow Valley State Airport into
Omak and possibly Republic and Colville as well. Smoke is expected
to push south into Spokane and Coeur d`Alene Thursday morning. Higher
altitude smoke moving northward across southeast Washington and
into the Idaho Panhandle will also produce hazy skies around KLWS
and KPUW. JW
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 52 83 54 87 56 92 / 0 0 0 0 0 0
Coeur d`Alene 51 82 51 86 54 90 / 0 0 0 0 0 0
Pullman 45 79 47 83 50 87 / 0 0 0 0 0 0
Lewiston 59 89 58 92 61 97 / 0 0 0 0 0 0
Colville 43 84 46 88 48 93 / 0 0 0 0 0 0
Sandpoint 47 81 45 84 49 88 / 0 0 0 0 0 0
Kellogg 55 79 56 82 58 87 / 0 0 0 0 0 0
Moses Lake 49 86 53 90 56 94 / 0 0 0 0 0 0
Wenatchee 56 86 59 90 63 94 / 0 0 0 0 0 0
Omak 54 88 56 92 60 97 / 0 0 0 0 0 0
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...Red Flag Warning until 10 PM PDT this evening for Northern and
Central Idaho Panhandle (Zone 101).
WA...Red Flag Warning until 10 PM PDT this evening for East
Washington Okanogan Highlands (Zone 687)-East Washington
Okanogan/Methow Valleys (Zone 684).
Red Flag Warning until 10 PM PDT this evening for East
Washington Palouse and Spokane Area (Zone 674).
Red Flag Warning until 10 PM PDT this evening for East
Washington Northern Columbia Basin (Zone 673).
Red Flag Warning until 10 PM PDT this evening for East
Washington Northeast (Zone 686).
Red Flag Warning until 10 PM PDT this evening for East
Washington North Cascades (Zone 685).
Red Flag Warning until 10 PM PDT this evening for East
Washington Central Cascade Valleys (Zone 677)-East
Washington South Central Cascade Valleys (Zone 676).
&&
$$
Area Forecast Discussion
National Weather Service Norman OK
1018 PM CDT Wed Jul 21 2021
...New AVIATION...
.SHORT TERM...
(This evening through Thursday)
Issued at 200 PM CDT Wed Jul 21 2021
Retrograding closed upper low passing to our south should have
little impact on our weather today. Precipitating diurnal convection
is expected to be closer to the track of this system deeper into
Texas through the rest of the afternoon. But, for our area
diurnal cumulus will be shallow and trapped beneath subsidence
inversion evident on 12z Lamont sounding, and model forecast
soundings.
Visual observations and HRRR smoke model indicate wildfire smoke
moving westward across our area in tandem with the aforementioned
upper low. The smoke will be shunted more easterly into the Ohio
Valley tomorrow, but there will still be a residual ribbon of smoke
contracting within a weak shear axis over northern Oklahoma.
Still some potential for a red sunset as a result, but maybe less
tomorrow than previous days given these synoptic-scale flow
changes.
This morning, several locations saw mostly minor visibility
reductions from radiative fog. The surface high will shift enough
that southerly winds will be slightly stronger tonight, probably
imitating radiative fog potential some compared to this morning.
Moisture advection should be weak at best to start so we should
have less fog coverage than this morning. The best chance for some
radiative fog will be where winds are lightest in south-central
and southeast Oklahoma, but a few patches of light fog can`t be
ruled out further northwest into central and northern Oklahoma.
Similar considerations tomorrow afternoon with regards to
convection, although with slowly increasing moisture and PWAT
values that aren`t as far below climo, some isolated weak
convection may occur near the Red River.
BRB
&&
.LONG TERM...
(Thursday night through next Tuesday)
Issued at 200 PM CDT Wed Jul 21 2021
By Friday afternoon, deep enough moisture may be present that
when coupled with diurnal heating could result in a slightly
better chance of isolated showers across southern Oklahoma and
north Texas. Coverage will still be quite sparse and weak
tropospheric flow will limit convective organization and thus
intensity.
Through the weekend and into early next week, mean ridging builds
across much of the country. The greatest 500-mb height anomalies
will be north of us especially into early next week with highest
height values near the Kansas/Nebraska border. Although this is a
hot pattern, it`s generally not associated with significantly
anomalous heat as would be the case with a more south-southwest
positioned ridge and enhanced southwesterly downslope in our area.
Thus, the most significant heat will be across the northern
Plains into the Midwest. We`ll likely reach above normal by mid-
late July standards by Sunday, and peak only a few degrees above
normal by late week. As of now it appears the combination of these
temperatures and humidity levels will keep heat indices below
traditional Heat Advisory criteria. Furthermore, southerly winds
will persist albeit light. Wet bulb globe temperatures should be
highest across south-central and southeast Oklahoma toward midweek
due to winds being lighter there.
Rain chances will be minimal and generally limited to isolated
convection in an increasingly more moist environment especially
Saturday and Sunday. This may not be entirely diurnal as moisture
magnitudes may be significant enough that even very subtle forcing
in the mid levels could force convection into the nocturnal
period.
BRB
&&
.AVIATION...
(06Z TAFS)
Issued at 1016 PM CDT Wed Jul 21 2021
VFR conditions expected, although we could see brief and minimal
BR toward sunrise, similar to this morning. High altitude smoke
will also keep the overall hazy looking skies going, especially
across the northern- half of Oklahoma. Otherwise, increasing south
winds through the period with gusts around 20KT far western
Oklahoma.
&&
.UPPER AIR...
Issued at 233 AM CDT Mon Jul 19 2021
No upper air flights are planned at this time.
&&
.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK 68 89 71 91 / 0 0 0 0
Hobart OK 68 90 70 92 / 0 0 0 0
Wichita Falls TX 70 92 73 93 / 0 10 10 10
Gage OK 67 90 69 93 / 0 0 0 0
Ponca City OK 67 89 70 92 / 0 0 0 0
Durant OK 72 91 73 93 / 0 20 10 20
&&
.OUN WATCHES/WARNINGS/ADVISORIES...
OK...None.
TX...None.
&&
$$
SHORT TERM...12
LONG TERM....12
AVIATION...11
AREA FORECAST DISCUSSION
National Weather Service Raleigh NC
940 PM EDT Wed Jul 21 2021
.SYNOPSIS...
Another weak cold front will move slowly south through the area
overnight through early Thursday. This front will then stall just
south of the area through Friday before finally pushing into the
Deep South over the weekend.
&&
.NEAR TERM /THROUGH TONIGHT/...
As of 920 PM Wednesday...
00Z surface analysis showed the cold front now pressing south
through central VA, with a few associated showers and storms mostly
confined to the Tidewater region. The western most radar echoes are
not on a trajectory to effect Halifax Co, and there`s no indication
from hires guidance that additional westward development is expected
as nocturnal stabilization continues. Meanwhile, visibility`s across
much of central NC have dropped a little to around 6 miles with haze
owing to the arrival of the western wildfire smoke stream across the
country. HRRR smoke forecasts suggest some improvement as the
front pushes through the area, but the mixing with the weak front
will be limited, and the haze should linger and still be noticeable
on Thursday. An Air Quality Alert for fine particulates has been
issued by NC DENR for all of central NC through midnight Thursday
night.
Otherwise the overnight forecast is on track with lows in the upper
60s and lower 70s.
Despite the frontal passage, lows tonight will be near normal with
readings in the upper 60s/around 70.
&&
.SHORT TERM /THURSDAY AND THURSDAY NIGHT/...
As of 245 PM Wednesday...
Surface cold front is progged to stall out across the far southern
zones Thursday morning, where it is forecast to remain nearly
stationary through Friday. Upstairs, central NC will remain on the
back-side of the long wave trough in place across the Eastern US and
under the influence of deep NWLY flow. Weak upper impulses embedded
in the NW flow will traverse the region. However, given limited
moisture availability, rain chances will remain very low and
generally in proximity to the stalled sfc front across the far
southern counties.
Hi-res model guidance indicates that the smoke plume will become
increasingly diluted throughout the day. Even still, expect the hazy
conditions to persist and spread farther south across central and
southern NC.
Highs Thursday will range from mid/upper 80s north to lower 90s
south. Lows in the mid 60s north to lower 70s south.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
As of 255 PM Wednesday...
Upper level ridge over the northern plains on Friday will weaken and
shift east over the weekend. At the surface, a front will have moved
to our south and a lee trough will have taken place across the
Piedmont. Thus, we wont be able to get out of the summertime pattern
and will have a slight chance of afternoon showers or storms over
the weekend. A cold front will then approach the region Monday into
Tuesday. These days will be our best chance of precipitation during
the long term with slight to chance PoPs in the current forecast.
Uncertainty for Wednesday as we wait and see whether the front
retracts or continues off the coast. Temps will be near or just
above normal with highs in the upper 80s/low 90s on Friday and
Saturday, then increase Sunday and Monday to low/mid 90s then
cooling down a tad thanks to the cold front with highs in the upper
80s/low 90s. Lows will be in the upper 60s/low 70s.
&&
.AVIATION /00Z THURSDAY THROUGH MONDAY/...
As of 725 PM Wednesday...
Areas of smoke associated with wildfires burning in the western
US will result in hazy conditions through the TAF period.
Vsbys have been hovering around 6SM at GSO and INT this afternoon
and have also begun to trend downward at RDU/GSO/INT in the past few
hours. We are not expecting VSBYS to fall to MVFR, though with
nocturnal stabilization this evening, haze should continue. A weak
back-door cold front will move south through the area overnight,
which should help to alleviate some of the haze in otherwise
continued VFR conditions. HRRR smoke guidance indicates the
concentration of smoke over VA will be transported back south across
NC early Thursday, so the haziness may redevelop/continue during the
day Thursday, and thus the TAFs will still reflect some VFR haze.
Looking ahead: Aside from some brief periods of sub-VFR conditions
associated with isolated to widely scattered afternoon showers and
storms, expect predominately VFR conditions through early next week.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...CBL/Blaes
NEAR TERM...Smith
SHORT TERM...CBL
LONG TERM...CA
AVIATION...Smith/CBL
Area Forecast Discussion
National Weather Service Reno NV
320 PM PDT Wed Jul 21 2021
.SYNOPSIS...
Smoke and haze from the Dixie and Tamarack fires will produce areas
of reduced air quality over the next few days. Temperatures will
gradually rise into the weekend with highs pushing above 100 degrees
in most lower valleys by Saturday. Thunderstorms may return to the
region Sunday through the middle of next week.
&&
.DISCUSSION...through next Wednesday...
Smoke Trends:
* Sadly, the smoke is not going to go away this week as both the
Dixie and Tamarack fires continue to grow in size. However, the
amount of smoke from both fires highly depends on fire activity
and suppression efforts. Both wildfires have produced extensive
pyrocumulus this afternoon, leading to more smoke production.
Per the latest HRRR model near-surface smoke guidance, smoke
from the Dixie fire looks to spread into west-central Nevada
(more towards Lovelock-Fallon) tonight through Thursday night.
Smoke from the Tamarack fire looks to continue to push across
southern Carson Valley and into southern Lyon, Mineral, and far
eastern Mono counties through Thursday. For more detailed
information please see our Special Weather Statement.
Heating Up into this Weekend:
* High pressure will continue to strengthen into the weekend over
the region, gradually increasing temperatures near to or above
100 degrees Saturday through Monday for the lower valleys of
western Nevada and northeastern California. Morning lows should
remain in the mid-60s across western Nevada as dry conditions
allow for sufficient radiational cooling. This heat is not too
unusual for mid-late July, though some heat-health impacts for
sensitive groups or those outdoors for extended periods are
expected. Temperatures look to cool next Tuesday and Wednesday
as an upper level low approaches the region.
Typical Afternoon Breezes:
* Slightly enhanced southwesterly afternoon breezes (gusts 20-30
mph) are expected today and Thursday before abating a bit
Friday through early next week (gusts around 20-25 mph). With
the already dry conditions in place, some isolated 1-3 hour
critical fire weather conditions are possible through Thursday.
For more information, please see the fire weather section below.
Thunderstorm Chances increase Sunday-next Wednesday:
* Thunderstorm chances will remain low the next few days as 500 hPa
heights increase over the region. A push of monsoon moisture looks
to work its way into the Sierra and western Nevada by Sunday. This
moisture will increase mid-level instability, which could trigger
isolated showers and thunderstorms across Mono and Mineral
counties by Sunday afternoon, with chances increasing northward
through early next week. Medium range deterministic and ensemble
guidance continues to hint at PWATs between 0.75-1.00" Monday into
Tuesday which could develop more widespread shower and
thunderstorm coverage south of Interstate 80 each day. Localized
heavy rainfall due to higher moisture content and slower-moving
storms could lead to flash flooding potential early next week.
-Johnston
&&
.AVIATION...
Visibility will be impacted by smoke from multiple large fires. Haze
will impact slantwise visibility for much of eastern CA-western NV.
Reduced surface visibility and/or lower smoke ceilings to IFR at
times are most likely at KMEV through at least Thursday. Other
airports in northeast CA and west central NV (including KSVE-KLOL-
KNFL-KHTH) will also experience smoke-related impacts from the large
Tamarack and Dixie fires that continue to burn actively.
Typical afternoon-evening west to southwest wind gusts of 20-25 kt
are expected at the main terminals today and Thursday. -Edan
&&
.FIRE WEATHER...
Typically breezy summer afternoon/evening winds for the next several
days. Most areas in the Sierra and western Nevada will experience
wind gusts in the 20-25 mph range, and some isolated gusts of 30-35
mph will be possible for a few hours each afternoon today and
Thursday.
For eastern Lassen and northern Washoe counties: Plan for single
digit humidity values in the afternoons with poor humidity recovery
overnight for the foothill and ridge locations. Can`t rule out a
handful of hours with critical conditions due to the breezes and low
RH`s the next couple of afternoons, especially across eastern Lassen
and northern Washoe counties.
For Alpine and Mono counties: Humidity values will be in the 10-15%
range this afternoon with southwest gusts mainly around 20-25 mph
and up to 30 mph for wind prone canyons. A few afternoon cumulus
build ups are possible across eastern Mono into southern Lyon and
Mineral counties today, with about a 5-10% chance of a thunderstorm
or two for the White Mountains in SE Mono county.
High pressure expands and strengthens across the West Friday and
into the weekend. Monsoon moisture moves northward into the Sierra
late this weekend with thunderstorm chances returning to Mono and
Mineral counties. Thunderstorm coverage will continue to spread
northward through the week with increasing potential for the Tahoe
Basin and into Western Nevada.
-Edan
&&
.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 Charleston WV
1018 PM EDT Wed Jul 21 2021
.SYNOPSIS...
High pressure crosses through from tonight into the weekend.
Moisture increases Sunday. Cold front crosses Monday.
&&
.NEAR TERM /THROUGH THURSDAY/...
As of 1015 PM Wednesday...
Made a few adjustments to cloud cover as some lower to mid level
clouds are developing over portions of the mountains. Also
bumped up the temperature at EKN a bit based on the current
observation as it is remaining on the warmer side compared to
the previous forecast. This may be due to the cloud cover along
the mountains as the cloudier skies could be preventing this
area from radiating as much, keeping it on the warmer side so
far tonight.
As of 730 PM Wednesday...
Made some adjustments to hourly temperatures to better represent
current observations. The last few showers have dissipated this
evening as the weak front has crossed the area. Overall,
current forecast remains on track.
As of 210 PM Wednesday...
A cold front crossing through the area will continue to bring a
few showers and thunderstorms across the northeast portion of
the CWA through the afternoon. Haze is again present courtesy
of smoke from wildfires in the western US and Canada, but the
HRRR model indicates the highest concentrations will drift south
by tonight.
High pressure begins building into the area from the northwest
tonight and temperatures are expected to lower into the 50s to low
60s across the area. With clearing skies and calm conditions,
river valley fog is likely to develop late tonight into early
Thursday morning.
Thursday is expected to be a rather pleasant and dry day as
high pressure continues to strengthen over the area.
Temperatures should be slightly lower than normal with highs in
the upper 70s to low 80s in the lowlands, and mid 60s to upper
70s in the mountains.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
As of 220 PM Wednesday...
Surface high pressure and the absence of any upper level disturbance
will promote dry weather conditions Thursday and Friday. Models
suggest H500 ripples of vorticity within an upper trough
clipping our northeast mountains Friday and Friday night.
However, believe the high pressure will prevail, and only few
showers will be seen along the eastern mountains during the
afternoon hours.
Tonight should be pleasant with temperatures generally in the 50s
Thursday and Friday nights. It will be hot on Friday, with
temperatures ranging from the upper 80s lowlands, into the low
70s higher elevations. Some spots reach 90 degrees Friday
afternoon. Saturday will be hotter with highs passing the 91
degree mark across the lowlands, and in the mid to lower 80s
higher elevations.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
As of 220 PM Wednesday...
Ripples of vorticity riding along northwest flow aloft will try to
develop few showers or storms mainly along the mountains on
Saturday. Meanwhile at the surface, a weak low pressure system
along with its cold front/warm front, will pass north of the
area Saturday night and Sunday, but weather should remain
relatively dry.
Then, a stronger cold front is progged to reach our western
counties early Monday morning bringing better chances for
showers and thunderstorms. Abundant low level moisture and
diurnal heating could allow for showers and storm development.
However, with the absence of deep layered shear, believe any
convection will be weak, perhaps leading to localized heavy
downpours and strong gusty winds.
Central guidance reflects above normal temperatures, with very
minimal influence from the cold front crossing.
&&
.AVIATION /02Z THURSDAY THROUGH MONDAY/...
As of 740 PM Wednesday...
VFR conditions start the period this evening as any last
isolated showers have dissipated out and some scattered clouds
remain over the area. Some haze remains possible at HTS this
evening but should move out of the area as much of the hazy
conditions from the smoke from the wildfires has moved south of
the area.
High pressure moves into the area tonight which will allow
skies to become more clear, and river valley fog will be
possible tonight at most sites. Visibilities are expected to
drop into the MVFR range later tonight, further dropping to the
IFR/LIFR range for the early morning hours. Any fog that forms
tonight will begin to clear out tomorrow morning, giving way to
dry, VFR conditions for the day with high pressure in control
tomorrow.
Northwesterly winds begin in the period at around 5 to 10 KTs
with a few sites gusting up around 15 KTs. Winds are then
expected to become light to calm tonight, assisting with fog
formation overnight. Northerly/northwesterly winds will then
pick up again during the day tomorrow at around 5 to 10 KTs.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z FRIDAY...
FORECAST CONFIDENCE: High. Medium for fog.
ALTERNATE SCENARIOS: Extent and intensity of river valley fog
tonight may vary from TAFs.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
DATE THU 07/22/21
UTC 1HRLY 00 01 02 03 04 05 06 07 08 09 10 11
EDT 1HRLY 20 21 22 23 00 01 02 03 04 05 06 07
CRW CONSISTENCY H H H H H H H L L L L L
HTS CONSISTENCY H H H H H H H H M M L L
BKW CONSISTENCY H H H H H H H L L L L L
EKN CONSISTENCY H H H H H M M L L M M L
PKB CONSISTENCY H H H H H H H H L L L L
CKB CONSISTENCY H H H H H H M L L L L L
AFTER 00Z FRIDAY...
IFR in early morning valley fog possible through Saturday, and
locally in thunderstorms on Sunday.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...None.
OH...None.
KY...None.
VA...None.
&&
$$
SYNOPSIS...ARJ/JLB
NEAR TERM...CG/JLB
SHORT TERM...ARJ
LONG TERM...ARJ
AVIATION...CG
Area Forecast Discussion
National Weather Service Blacksburg VA
911 PM EDT Wed Jul 21 2021
.SYNOPSIS...
Hazy skies are the result of smoke from the western U.S. and
Canadian wildfires. Aside from the haze, mainly dry and
seasonal weather expected through the remainder of this week.
A cold front will approach the region from the northwest
Sunday...crossing the area Monday. This will be our next
bonafide opportunity for showers and thunderstorms.
&&
.NEAR TERM /THROUGH THURSDAY/...
As of 910 PM EDT Wednesday...
Minor adjustments to the forecast tonight for latest
temperatures and dew points. Winds have already gone calm in
many spots. Winds will be northwesterly and light on Thursday
with high pressure building in. Overnight lows should drop into
the mid 50s in the mountains to the mid 60s over the piedmonts
of NC and VA.
As of 600 PM EDT Wednesday...
A southward-moving front was in the process of pushing through
the forecast area, and has moved through western VA and into
eastern VA and parts of NC. Gusty NW winds developed briefly
just behind the front. This has helped to clear some of the
smoke out from the wildfires to our north, at least in the lower
levels. Made a few changes to sky cover, temperatures, and
winds for this update.
As of 300 PM EDT Wednesday...
...Hazy Skies But Seasonal and Mainly Dry...
An air quality alert was issued for VA/ for the increase in
smoke particulates. Airnow.gov is a great place to check out the
latest numbers with respect to area DEQ sensors. Roanoke
trended into the unhealthy range prompting the alert. The HRRR
smoke model maintains higher concentrations of smoke across the
area until a cold front introduces a change in airmass tonight.
An air quality alert will also be in effect for North Carolina
beginning now and continuing through Thursday, or until such
time there is an airmass change from the front.
Latest satellite imagery indicates haze covering the entire
forecast area. A surface cold front was inbound from the north.
There were a few thunderstorms along the front to our northeast,
but the airmass over our forecast area is not supportive of deep
convention with the exception of maybe areas down to about
I-64. Generally running with less than 20 percent chance for
areas north of I-64 which means no more than isolated coverage.
For the overnight, the front is expected to move south and into
the state of North Carolina. This will introduce a northerly
wind overnight and into the day Thursday. Post frontal drying is
expected with falling dewpoints along with temperatures a degree
or two cooler compared to Wednesday. The increase in northerly
wind is also expected to advect/push the smoke/haze south and
west with times, so anticipating better visibility
Thursday...improving from the north.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/...
As of 200 PM EDT Wednesday...
An upper level trough over the Mid Atlantic region and surface high
pressure over the area, generally looking for fair weather cumulus
to pepper the area Friday. Can not rule out a stray shower in the
late afternoon and evening. A warm front will pass over the area
Saturday and may bring a few drops of rain along with it.
Near normal temperatures expected Friday with upper 70s to mid 80s
across the mountains and mid to upper 80s east of the Blue Ridge.
Following the warm front, heights gradually increase and so do the
temperatures. Highs Saturday will range in the 80s west of the Blue
Ridge to low 90s east. Each night, overnight lows will fall into the
60s.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
As of 200 PM EDT Wednesday...
Heights continue to increase on Sunday, along with temperatures and
humidity. With a lee trough over the piedmont, convergence will help
spark scattered afternoon and evening thunderstorms along the
eastern slopes of the Blue Ridge into the foothills. An approaching
cold front should bring some spotty convection west of the Blue
Ridge late into the afternoon going into the evening. Instabilities
maybe high enough for a few strong storms.
The coverage of strong to severe storms increases on Monday as a
cold front is set to move through the region late in the day. This
front could jump to the lee trough which would put the piedmont in a
higher risk for strong storms. The front should clear the area by
Tuesday morning with high pressure hanging around into Wednesday.
Temperatures ahead of the front will run warmer than normal with the
warmest day being Monday. Following the front, temperatures will
fall back towards normal values Tuesday and Wednesday.
&&
.AVIATION /01Z THURSDAY THROUGH MONDAY/...
As of 900 PM EDT Wednesday...
Smoke/haze had mostly scattered out this evening, at least in
the lower levels, as a cold front pushed south. Winds have
become light and variable and will remain that way overnight,
with a prevailing NW direction once the sun comes up Thursday.
Models indicate fog for BLF/LWB/BCB late tonight.
Forecast confidence is high for winds and sky cover overnight,
but lower for fog development after the frontal passage.
Extended Aviation Discussion...
VFR through Friday with limited if any threat of showers/storms.
A front this weekend will bring an uptick in storm coverage, but
still VFR outside any storms. Always a possibility for the late
night fog at LWB and perhaps BCB especially this weekend.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...None.
NC...None.
WV...None.
&&
$$
SYNOPSIS...PM
NEAR TERM...PM/SH
SHORT TERM...RCS
LONG TERM...RCS
AVIATION...PM
We have mentioned an easterly wave in several forecast discussions
that is expected to move westward across the lower 48 and bring
quite a bit of additional moisture and dynamics into the Desert
Southwest this weekend. With each model run, this wave is trending
slower. Uncertainty surrounding this wave revolves around both
timing and location, which, in turn, provides quite a bit of
uncertainty in the PoP forecast. Compared to the previous run, the
latest run of the NBM has receded a bit eastward with lower PoPs
each afternoon through Sunday than originally anticipated. That
said, pop-up convection will continue each afternoon through the
weekend favoring Mohave County as well as the higher terrain of
Lincoln and Clark counties.
[EARLY NEXT WEEK] As the easterly wave moves across Arizona and gets
sucked around the monsoonal high, the additional moisture and
dynamics that it will bring will result in widespread showers and
thunderstorms across the forecast area. Impacts of this easterly
wave will begin as early as Sunday evening primarily impacting
northwestern Arizona. Flash Flood Watches will be coordinated this
week with neighboring offices as our timing confidence increases
over the next few days. Impacts look to peak on Monday areawide,
with highest chances over Mohave County and the higher elevations of
southern Nevada. Primary concern will be flash flooding, though
winds in excess of 50 mph are possible with associated outflow.
[NEXT WEEK] The easterly wave will dance between an off-shore area
of low pressure and the monsoonal high before getting caught in an
easterly flow aloft and shooting eastward out of our area. As such,
through the week, precipitation chances will be focused in the
northern portions of our CWA, returning each afternoon.
&&
.AVIATION...For McCarran...Isolated thunderstorms are expected to
continue around the region into the early evening. There is the
potential for gusty outflow winds associated with storms that form
around the Las Vegas Valley with gusts to 30 kts possible.
Otherwise, look for a general south to southwest wind this evening
between 10 and 15 kts. Diurnal trends expected overnight.
For the rest of southern Nevada, northwest Arizona and southeast
California...Isolated thunderstorms expected again today, but mainly
confined to Lincoln, Clark, Mohave, and eastern San Bernardino
counties. Storms will be capable of producing gusty outflow winds
and heavy rain from their direction. Outside of thunderstorm
influences, look for winds generally 10 kts or less with diurnal
trends. FEW-SCT 140-160 with lower CIGS near storms.
&&
.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any significant weather or impacts according to standard operating
procedures.
&&
$$
DISCUSSION/AVIATION...Varian
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