Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/08/21

Area Forecast Discussion

National Weather Service La Crosse WI

 1000 PM CDT Sat Aug 7 2021

.UPDATE...
Issued at 949 PM CDT Sat Aug 7 2021

At 9pm...the surface front was located near Rochester toward
Preston to near Boscobel and Lone Rock. South of this front,
SBCAPE was around 4000 J/kg. Deep layer shear was noted 35 to
45kts over parts of central MN and also eastern Neb. The low level
jet is forecast to increase overnight and this combined with the
favorable moisture and instability environment should result in
additional thunderstorm re-development. The 88-D mosaic is already
showing an uptick across Clark Co and we have been seeing
convection across Adams and Juneau Co. Look for westward
development along and north of the front with efficient storm
producers of 1 to 2 inch rainfall rates. Due to the heavy rainfall
from Saturday - widespread 1 to 3 inch amounts and several
counties with 3 to 5+ inch amounts. A flash flood watch is in
effect for areas most prone to flash flooding. We will continue to
have a severe weather risk as well with the moderate instability
overnight and 0-3km shear vectors from IA into SE MN and Wrn WI of
35 to 45kts Sunday morning.

&&

.SHORT TERM...(This evening through Sunday)
Issued at 236 PM CDT Sat Aug 7 2021

TODAY...Current satellite imagery places the meridionally
elongated positively tilter upper-level trough over eastern WY
into western NE. Primary convection has been focused downstream of
the trough axis from eastern NE into northern IA and southeastern
MN/western WI. This morning`s lingering precipitation has
appeared to temporarily halt northerly progression of the surface
frontal boundary based on repeated post frontal convection firing
in northeast IA. If/when the warm front progresses, low-level
moisture transport concentrates into central MN and western WI.
Similarly, the NAM & RAP take higher CAPE values further north
than the GFS/ECMWF based on the warm sector inclusion. The
concavity of the hodographs within the warm sector increase into
the afternoon favoring right moving supercells containing max
helicity values ~375 m2/s2. RAP 0-3km shear has increased for this
afternoon to >40 kts with 0-6km shear remaining at 40-50kts. A
few storms could produce large hail and localized flooding with
precipitable water values nearing 2.00 inches. Isolated tornadic
activity also remains possible, dependent on frontal set up and
the ability of elevated convection to become surface-based.

TONIGHT...The upper level trough continues it`s eastward
progression overnight, bringing our forecast area into a primary
area for synoptic ascent. Surface boundaries are forecasted to
continue their north and eastward progression associated with the
upper & mid-level forcing. Moisture transport increases across
central IA into SE MN near midnight local time tonight.
Precipitable water values increase to >2 inches along this
moisture transport axis, progressing eastward in the early morning
hours directed towards central WI. Convective allowing models
continue evening convection through the overnight hours, with the
HRRR and NAM4km including a training area of higher reflectivity
in our forecast area. While the exact location of localized heavy
rainfall remains more variable, the synoptic-level variables such
as absolute vorticity advection remain favorable for increased
convective activity in the early morning tomorrow. The combination
of synoptic-level forcing with such high precipitable water
values can result in anomalous precipitation in the early morning
hours. Currently, RAP shear remains 20-30kt at 0-3kt and minimal
0-6km shear indicating smalled likelihood for organized convection
at this time. Will still be important to keep an eye on set up
overnight for the possibility of storms repeating over the same
areas.

.LONG TERM...(Sunday night through Saturday)
Issued at 236 PM CDT Sat Aug 7 2021

Water vapor satellite today indicates the approaching long wave
trough extended from the wester Dakotas into northern Colorado and
was working east toward the region. The pattern ahead of this
trough continues to look to be very messy with numerous short wave
troughs out ahead of and embedded in the long wave trough.
Depending on how tonight`s convection evolves, will have an impact
on where the boundaries will set up for Sunday. At this time,
there is good agreement from the hi-res meso-scale models that the
convection that develops tonight should exit/end early Sunday
morning. The attention then looks to be focused on a stronger
short wave trough embedded in the equatorial end of the long wave
trough that should be swinging across far southern Iowa and
Missouri in the late afternoon and evening and translating into
Illinois overnight. The low level moisture transport axis will
gradually shift east ahead of the short wave trough and looks to
briefly be focused into southwest Wisconsin in the late afternoon
before shifting farther south closer to the main short wave
trough. With only around 25 knots of shear in the 0- 3 km layer,
would not expect much potential for hail or winds with the
activity that develops in the moisture transport axis across the
eastern parts of the area. The bigger threat will be for heavy
rains with warm cloud depths in the 3.5 to 4 km range and
precipitable water amounts approaching 2 inches. This activity
should primarily be southeast of where most of the
convection/heavy rains are expected to occur tonight. Thus not
anticipating the need for a flash flood watch at this time, but of
course, that can change based on what happens during the
overnight.

Attention will then quickly turn to Tuesday with the next system
coming in and the potential for severe weather. The system
currently just off the western British Columbia coast will quickly
rotate across the northern Rockies and should be entering the
Upper Midwest Tuesday afternoon. This system looks to have a
rather potent short wave trough embedded in the equatorial end of
the long wave trough that will be entering western Minnesota by
late in the day. In the low levels, the surface boundary looks to
possibly be a bit out ahead of the upper level support but an area
of low pressure could be moving along the front and be over or
near the local area. This type of set up looks to put the best
deep layer shear behind the front but there could still be around
30 knots in the 0-3 km layer over the boundary. Ample CAPE looks
to be in place ahead of the front with the possibility of 3000+
J/kg MLCAPE. Some signals of enhanced 0-1km shear along a warm
front extending from western Wisconsin into the southeastern part
of the state. These signals would suggest that all severe threats
could be in play Tuesday afternoon along with the potential for
another heavy rain episode. The low level moisture transport looks
to be focused into the warm front with warm cloud depths of 3.5
to 4 km and precipitable water amounts again around 2 inches.

&&

.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 629 PM CDT Sat Aug 7 2021

As of now, all the convection has moved off to the east of both
airports. More convection is expected to develop later this
evening into the overnight. The front has remained nearly
stationary and will not move much overnight. As the low level jet
ramps up overnight and intersects the front, a east/west line of
convection is expected to form in the Interstate 90 corridor. This
will likely impact both airports with MVFR/IFR conditions. This
should hopefully end around sunrise with VFR conditions developing
by mid to late morning.


&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...Flash Flood Watch through Sunday morning for WIZ029-032>034-
     041>044-053>055.

MN...Flash Flood Watch through Sunday morning for MNZ079-087-088-095-
     096.

IA...Flash Flood Watch through Sunday morning for IAZ010-011.

&&

$$

UPDATE...Zapotocny
SHORT TERM...JAR
LONG TERM...04
AVIATION...04



Area Forecast Discussion

National Weather Service Bismarck ND

 937 PM CDT Sat Aug 7 2021

.UPDATE...
Issued at 937 PM CDT Sat Aug 7 2021

We added areas of fog to the forecast from 09-15 UTC roughly along
and east of a Harvey-Steele-Ashley line with this update based on
a residual moist boundary layer with dewpoints in the 60s F, light
winds, and evening precipitation. Recent HRRR and GLAMP cycles all
support that. Otherwise, the convection associated with the MCV in
the James River valley as of 0230 UTC has gradually been weakening
and that trend is expected to continue given its upscale growth,
decreasing bouyancy with the onset of nocturnal cooling, and the
absence of a notable low-level jet. Moreover, the MCV is steadily
shifting eastward and extrapolation suggests precipitation chances
in our forecast area should end by about 06 UTC, if not earlier.

UPDATE Issued at 623 PM CDT Sat Aug 7 2021

New convection has initiated on the eastern and northern arcs of
ascent downstream of the long-lived, slow-moving MCV centered in
far south central ND as of 2315 UTC. The convective environment
is characterized by moderate instability with MLCAPE of 1500-2500
J/kg, but poor midlevel lapse rates around 6 C/km and effective-
layer shear on the order of 20 kt per recent VWP hodographs and
RAP-based objective analyses suggests the severe-storm risk will
continue to be minimized. This scenario was already well-handled
in the current forecast, with precipitation chances highlighted
along and east of the MCV through the evening, mainly along and
south of I-94 and along and east of ND Highway 6. Thus, while we
did refresh forecast fields through Sunday using the most recent
NBM cycles, little overall change was needed with this update.

&&

.SHORT TERM...(This evening through Sunday)
Issued at 202 PM CDT Sat Aug 7 2021

An MCV continues churning very slowly along the ND/SD border near
the Missouri River. Not a lot of thunder remains with the system
as of now, although CAMs are fairly consistent in the idea that it
will redevelop as it moves further east this afternoon and the
environment becomes more unstable. Even with a bit more unstable
environment, more favorable wind shear is progged to remain
further south and east of this system. Thus, while strong
thunderstorms are possible and a storm or two could pulse to
severe levels near or over the James River Valley, severe weather
is generally not expected this afternoon. Cloud cover continues to
clear out behind this system with smoke still blocking out the
blue of the sky over most of the area. Conditions dry out for the
day Sunday with hot temperatures returning and highs reaching the
low to mid 90s for most of the forecast area.

.LONG TERM...(Sunday night through Saturday)
Issued at 202 PM CDT Sat Aug 7 2021

Another trough begins to enter the area Sunday night with the best
precipitation chances during the day Monday, especially for the
northern third of North Dakota. By Tuesday afternoon, any
remaining remnants of the system will likely have moved out of the
area and the remainder of the extended period looks dry. High
temperatures on Monday range from the mid 70s in the northwest to
the low 90s in the southeast. Otherwise, high temperatures look
seasonable for this time of the year as northwest flow persists
over the region Tuesday through the remainder of the workweek.

&&

.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 937 PM CDT Sat Aug 7 2021

Showers and thunderstorms with local MVFR to IFR conditions in the
James River valley should end and/or move out of the area before
06 UTC. However, confidence continues to increase in development
of fog and stratus with potential MVFR to IFR conditions in parts
of south central ND into the James River valley between 09 and 15
UTC, likely impacting KJMS. Elsewhere, VFR conditions in the west
and north will continue through the 00 UTC TAF cycle.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

UPDATE...CJS
SHORT TERM...Telken
LONG TERM...Telken
AVIATION...CJS



Area Forecast Discussion

National Weather Service Denver/Boulder CO

 655 PM MDT Sat Aug 7 2021

.UPDATE...
Issued at 650 PM MDT Sat Aug 7 2021

Thunderstorms have cleared out of the forecast area completely so
have updated to drop them from the grids the rest of evening.
Smoke will be the prevalent issue overnight and into Sunday. No
other changes needed at this time.

&&

.SHORT TERM...(This evening through Sunday)
Issued at 247 PM MDT Sat Aug 7 2021

The passage of the upper level trough can be seen on water vapor
progressing across the northern boundary and into the northeastern
plains counties. This progression and the associated vort max are
helping to drive some convection across Morgan and northeast into
Logan, Phillips, and Sedgwick counties over the next few hours.
Pressure rises across the northern mountains and into Weld will
continue to progress through the forecast area increasing subsidence
behind the upper trough. A boundary across Elbert and into northern
Lincoln counties helped to fire off some convection that will bring
hail, wind and lightning over the next few hours. CAMs have
struggled with the convection today as instability has been hampered
by smoke impacts with most areas struggling to reach convective
temperatures. The added lift provided by the trough and boundary
have helped in this department but maintain it will not be
widespread and continue to impact areas mainly east of I-25. Dropped
temperatures a few more degrees given that solar insolation is
nearly at its max and we are still sitting in the upper 70s to lower
80s in most areas. Will maintain lows overnight in the lower 60s
with smoke impacts continuing.

For Sunday, the upper ridge increases and elongates across the
southwest bringing zonal flow over the region. There will be a
slight reprieve from smoke during the morning hours before it
increases again during the late afternoon to evening per latest HRRR
smoke guidance. Post-trough subsidence will help to bring more
stable conditions and keep areas dry. High temperatures will be
slightly warmer than today but still muted slightly by smoke so
reduced a few degrees into the lower to mid-90s for the plains and
mostly 70s for the high country.

.LONG TERM...(Sunday night through Saturday)
Issued at 247 PM MDT Sat Aug 7 2021

Westerly flow aloft will continue through Monday as an upper
trough moves across the northern Rockies. This will push a cold
front through sometime Monday. Temperatures Monday will depend on
the timing of the front and how thick the smoke is. There will
likely be another batch of smoke concentrated along the
front/trough, though there could be cleaner low level air behind
the surface front since that air will likely be coming from less
smoky areas of the northern Rockies. The current forecast of mid
90s looks alright for now, but it might not get that warm.

For the middle and later parts of the week, we`ll have decreasing
northwest flow aloft. It will be quite dry for a couple of days,
and highs will likely still be in the 90s. Our air will be coming
more from the northwest border areas, so the smoke will depend on
fire activity in that region. There will be some, it`s just a
matter of how much. By the end of the week, there should be
gradual moistening after another weak surface front about Thursday
combined with mid level moisture creeping up into the ridge from
the southwest. At this point it still looks like limited moisture
and still warm aloft, so a gradual increase in convection is in
order. Since we`ll be sitting under the ridge axis, we could start
to see a burn area flood threat again by Friday or Saturday.

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 650 PM MDT Sat Aug 7 2021

Smoke will result in ILS approaches and reduced visibility through
midday Sunday. Visibility anywhere from 4 to 7 SM expected.
North/northeast winds early this evening will return to normal
drainage winds 03Z-06Z.


&&

.FIRE WEATHER...
Issued at 247 PM MDT Sat Aug 7 2021

Fire danger will be elevated in most areas through Sunday with
humidity levels dropping into the 10-18% range in lower
elevations, with 20-30% above 8000 feet. Currently however winds
are expected to remain below criteria with some increased gusting
up to 25 mph across the northern mountains and high mountain
valleys.

There will be some enhancement of fire danger on Monday afternoon
with stronger winds over the mountains and low humidities. Fuels
are pretty green for this time of year in the windier areas
though. Tuesday will likely see a bit less wind but quite low
humidities over the northern mountains.

&&

.HYDROLOGY...
Issued at 247 PM MDT Sat Aug 7 2021

No hydro concerns for the burn areas through Sunday with no
significant rainfall expected.

A small flood threat for the burn areas may return by Friday or
Saturday as moisture increases with slow storm motions likely.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

UPDATE...Cooper
SHORT TERM...Bowen
LONG TERM...Gimmestad
AVIATION...Cooper
FIRE WEATHER...Bowen
HYDROLOGY...Bowen/Gimmestad



Area Forecast Discussion

National Weather Service Des Moines IA

 640 PM CDT Sat Aug 7 2021

...Updated Aviation Discussion...

.DISCUSSION.../Tonight through Saturday/
Issued at 326 PM CDT Sat Aug 7 2021

The primary messaging highlights through the period include...

* Convective trends and severe weather potential into tonight,
  and again Tuesday
* Heat and humidity Monday
* Convective trends and severe weather potential Tuesday
* Cooler, drier, pleasant weather to end the week

The immediate concern will be convective trends into the night,
and is a waiting game for the moment. The current situation has
three areas of concern west to east: a surface cold front across
central NE, weaker elevated convection approaching the MO River
across NE, and a warm front across southern MN into northeast IA.
The weak upstream elevated convection across NE certainly has
inhibition limits keeping that essentially steady-state as it
moves into western IA early this evening and is not a severe
weather concern. Similar inhibition concerns exist farther
upstream along the cold front, but the convection allowing hi-res
models (CAMs) continue to suggest this will be our primary event
with the combination of synoptic forcing, low level convergence,
and a maturing low level jet blossoming an MCS across NE this
evening, and reaching western IA just after midnight. The latest
RAP suggests plenty of available instability into the evening,
maintaining 2500-3500+ j/kg MLCAPEs. Deep shear will be the
limiting factor, but most CAMs suggest an eventual QLCS mode
leaving strong winds and possibly a transient tornado or two as
0-1km shear and SRH increase with the low level let. As mentioned
above, 3-6km winds are less favorable however, limiting sufficient
3km shear to maintain healthy QLCS tor conditions for long, if at
all. Farther north along the warm front right now, the tornado
parameter space is much more favorable with elevated effective
shear, ESRH, 0-3km CAPE and reduced LCLs. Moisture convergence has
been steadily increasing near the front all afternoon, with
objective RAP analysis indicating CINH has all but eroded. However
examination of several GOES-16 images and RGB composites has
shown little cloud top cooling or phases changes yet suggesting
convective initiation isn`t eminent. If anything happens to form
it would likely just brush our northern/northeast counties based
on WSW Bunkers supercell projections. Much like the aforementioned
upstream convection, this may also wait to activate until larger
scale and low level jet influences with similar pluses and minus
as noted with the evolution of the NE MCS.

By tomorrow morning, upper air and surface features will become
further disconnected. Mid level forcing will be crossing the MS
River with lower based 850/700 QG forcing still lingering south
and east by afternoon. There will be little surface reflection
however with a southerly wind component to some degree
anticipated, outside of lingering convective boundaries. MLCAPEs
are again expected to surge into the 2500-3500 j/kg range, but
with low level focus and deep shear lacking, the severe weather
potential should be reduced. The low level jet and associated
moisture convergence should be south and east of the area by
Sunday Night, but lingering support along and ahead of the 1-3km
trough may keep spotty weaker convection going into the night as
well, especially east.

For Monday, the primary theme will be heat and humidity as the
the upper trough now approaching BC/WA reaches the northern
Rockies and begins to be our primary influencer. A developing warm
front across northern IA associated with the aforementioned low
may limit the northward extent of the warm conditions, but highs
are still expected to reach the lower 90s area wide. However with
oppressive dewpoints well through the 70s, peak heat indices
should still reach 100-105 central and south even with temps not
being extreme.

The northern Rockies trough should be into the Dakotas by midday
Tuesday with the associated surface trough/weak front and synoptic
scale lift into central and southeast Iowa during the afternoon.
Low level convergence and large scale support should develop at
least scattered convection into the evening, but there is some
inhibition concern due to warm 1.5km temps. If anything develops
there will certainly be adequate instability available with
2500-3000 j/kg MLCAPEs and steep lapse rates aloft leading to
some hail and wind potential, but the wind profile is unimpressive
with weaker low and mid level flow resulting in corresponding
lower shear values. Thus any severe threat seems brief seems
somewhat limited to a degree.

A pattern change will be the main weather story for the end of
the period as a Canadian mean trough matures and pushes a cold
front through late Thursday. This environment will again include
moderate to high instability, but the severe potential offset by
inhibition and continued lack of deep shear. Subsidence and
cooler, drier northerly flow should finally usher in pleasant
weather and a refreshing airmass change for the weekend.

&&

.AVIATION.../For the 00Z TAFS through 00Z Sunday evening/
Issued at 627 PM CDT Sat Aug 7 2021

Still anticipating convection overnight into Sunday morning, but
the latest hires models suggest less coverage and duration across
central Iowa. Thus shrunk the window for convection to mainly from
06-10z and then another chance b/t 13-17z Sunday. Low confidence
with any MVFR visibility or ceilings and left out mention attm.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

DISCUSSION...Small
AVIATION...Podrazik



Area Forecast Discussion

National Weather Service Grand Junction CO

 538 PM MDT Sat Aug 7 2021

.SHORT TERM...(Tonight through Sunday night)
Issued at 202 PM MDT Sat Aug 7 2021

Hot topic of the day continues to be the dense smoke that has
engulfed our forecast area from wildfires burning across
California, Oregon, Washington, Idaho and Montana. What should
have been a bluebird day has deteriorated into the grey abyss. No
real good news at this point with poor air quality likely to
persist as high pressure over the Great Basin continues to guide
the dense smoke across the Great Basin and then driving it
southeast across Eastern Utah and Colorado. Latest HRRR smoke runs
indicate some subtle improvement late tonight and Sunday, so
backed off definite smoke wording into more of the "areas of"
wording. The good news about the smoke is that it`s helped to
knock temps down a few more degrees off the already cooler
forecast temps for today. Expect mild conditions tonight and for
max temps on Sunday to nudge up a few degrees with a bit more sun
expected and significant warming at the h7 level.

Otherwise, this is a dry forecast for the next 36 hours with
locally gusty winds during the late afternoon/early evening hours,
especially in areas of clearing or thinning smoke.

.LONG TERM...(Monday through Saturday)
Issued at 202 PM MDT Sat Aug 7 2021

A closed low will move east across the Northern Rockies Monday,
increasing the pressure gradient over much of the Intermountain
West. This will lead to breezy conditions across northeastern Utah
and northwest Colorado, and potential critical fire weather
conditions. High pressure will build into the Great Basin following
the passage of the closed low, keeping the region under clear skies
and generally dry conditions. Temperatures will run 5-10 degrees
above average through this period. The bulk of the moisture looks to
remain to the south, although enough may sneak north into the Four
Corners region that a slight chance of late-day showers or
thunderstorms will be possible from mid-week onward, mainly along
the Continental Divide. By late week, models are hinting at a return
of monsoonal moisture to western Colorado and eastern Utah.
Confidence is still very low, as there is quite a lot of model
disagreement. Stay tuned.

&&

.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 536 PM MDT Sat Aug 7 2021

Obviously, the big story is the smoke and restrictions to
visibility it`s bringing. Currently, vis has dropped to between 3
to 5SM across the area. These MVFR conditions will continue
through 03Z and should then lift to 6SM but the smoke does look to
linger. Similar conditions tomorrow with a few gusty afternoon
winds mixed in as well.

&&

.FIRE WEATHER...
Issued at 202 PM MDT Sat Aug 7 2021

High pressure centered over the Great Basin will continue to sweep
widespread smoke from Western Wildfires across the region with
significantly reduced visibility at times. These conditions are
expected to persist through at least midweek. There will be a few
weak disturbances passing to the north, increasing winds a bit and
resulting in heightened fire weather concerns Monday. Next chance
for more moisture and showers moving back in looks to hold off until
late in the week when another push of monsoonal moisture will
attempt to lift northward across Arizona.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...None.
UT...None.
&&

$$

SHORT TERM...JDC
LONG TERM...BGB
AVIATION...TGJT
FIRE WEATHER...JDC



Area Forecast Discussion

National Weather Service Goodland KS

 945 PM MDT Sat Aug 7 2021

.UPDATE...
Issued at 703 PM MDT Sat Aug 7 2021

Conditions have improved in Gove, Greeley, Logan, and Wichita counties
allowing the Severe Thunderstorm watch to be cancelled.

&&

.SHORT TERM...(This evening through Tuesday)
Issued at 200 PM MDT Sat Aug 7 2021

Tonight...strong to severe thunderstorms are expected generally east
of the Colorado Kansas border this evening as a weather disturbance
moves off of the Palmer Divide and into the area this evening,
exiting the area before midnight. It appears that a line of storms
will develop along and south of the interstate with an east then
northeast movement. DCAPE values early this afternoon are in the
1500-1700 range and support the last few runs of the HRRR wind gust
forecast in excess of 75 mph. Hail up to the size of golf balls and
locally heavy rainfall will also be possible. Smoke will also be
possible for much of the night producing some reduced visibilities
and unhealthy air quality.

Sunday-Sunday night...a sunny sky is expected during the day with a
clear sky overnight. High temperatures are expected to be in the low
to upper 90s with low temperatures in the low to upper 60s.

Monday-Monday night...some mid and high level clouds move in during
the afternoon, moving east and out of the area during the night.
There is a slight chance for showers and thunderstorms near the
KS/NE border. High temperatures rise back into the mid 90s to around
102 degrees with low temperatures in the upper 50s to around 70.

Tuesday...an upper level trough moves across the northern plains
with its cold front moving through during the day. High temperatures
arent quite as hot as Monday with readings in the low to mid 90s.
No precipitation is currently expected.

.LONG TERM...(Tuesday night through Saturday)
Issued at 131 PM MDT Sat Aug 7 2021

The extended period continues to trend hot and dry for majority of
the period thanks to the ridge over much of the western CONUS. There
is concern for elevated to near-critical fire weather conditions
Wednesday and Thursday in the northwest corner of the area due to
low relative humidity values. The current forecast keeps the winds
peaking around 20 mph during the afternoon hours. Overnight lows
on Tuesday are expected to be in the upper 50s to mid 60s.
Temperatures appear to briefly increase in the middle of the week
with values in the 90s across much of the area and a few locales
along and west of US 83 approaching 100 degrees Wednesday.
Thursday is currently expected to be slightly warmer, ranging from
the mid 90s to 100 degrees. Overnight lows are forecast to remain
in the upper 50s to upper 60s both nights.

A cold front is expected to move south across the area Friday
morning. With the front, temperatures are expected to cool into the
upper 80s to lower 90s for afternoon highs. Behind the front,
guidance suggests a few weak disturbances will move across the High
Plains providing an opportunity for showers and storms to develop
Friday afternoon and continue through Saturday morning. This far out
confidence is not very high, so PoPs are less than 20%. Overnight
lows are expected to be in the upper 50s to mid 60s. Saturday, both
the GFS and ECMWF have a shortwave trough traveling along the edge
of the ridge, which will help strengthen a lee trough along the
Front Range. This could provide yet another opportunity for
showers/storms to develop off the Front Range and move across the
Tri-State area during the afternoon and evening hours. Temperatures
are currently forecast to be close to normal in the mid 80s to lower
90s for afternoon highs and the upper 50s to lower 60s overnight.

&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 935 PM MDT Sat Aug 7 2021

KGLD begins the 06Z TAF period with MVFR conditions with
visibility at 5SM due to smoke from the western wildfires
residing over the terminal along with westerly winds at 6 kts. By
10Z, VFR conditions come to KGLD as the smoke clears and
visibility improves with winds increasing to 9 kts before turning
northwesterly at 14Z. At 18Z, KGLD winds slow to around 4 kts then
become southerly around 6 kts by 00Z.

KMCK expects to see VFR conditions throughout the 06Z TAF period
starting with westerly winds around 5kts. At 14Z, KMCK sees winds
turning northwesterly before turning southerly at 23Z and then
becoming southeasterly around 7 kts at 03Z.

&&

.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&

$$

UPDATE...MRC
SHORT TERM...99
LONG TERM...KMK
AVIATION...076



Area Forecast Discussion

National Weather Service Gray ME

 1037 PM EDT Sat Aug 7 2021

.SYNOPSIS...
A weak cold front will settle into the region tonight with a few
showers and thunderstorms. This front will stall over the region
tonight and serve as a focus for additional shower and
thunderstorm activity on Sunday with locally heavy downpours
possible. After temperatures cool somewhat for Sunday and
Monday...the remainder of the coming week is looking
increasingly warm and humid with shower and thunderstorm chances
gradually increasing.

&&

.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
High Impact Weather Potential:
    *Patchy dense fog possible tonight.

1035 PM...Convection associated with the weakening and slowing
sfc front is winding down to a few showers late this evening and
should be done by midnight. Expecting fog to develop in the
valleys, and in places across nrn NH where it rained this
evening. Temps in the S a touch warmer than forecast, but
overall mins will come pretty close to prev forecast, generally
65-70 outside the mountains, and in the low 60s in the mtns,
and some spots on the mid-coast.

7 PM...Previous forecast working out fairly well as to coverage
and location of SH?RA, with a few TSRA as well. The mid-lvl
cap /weak lapse rates/ has held fairly well with cells of only
moderate vertical extent at best, so mainly just a few heavy
downpours and some isolated lightning expected through about
00-01Z in the N zones. To the S, increasing cirrus and mid
level clouds expected later tonight, and Tds will only drop off
a bit, so lows range from the low 60s in the mtns to the mid-
upper 60s in the south.

Pattern: Water vapor imagery shows a shortwave trough extending from
the Great Lakes region south into the Ohio Valley.  East of this
trough...we see confluent mid level flow between larger scale
troughing east of Hudson Bay and ridging off the Atlantic coast.
Through the near term...the larger scale trough to our north will
push east while the shortwave to our west cuts off from the stronger
westerlies to its north.  A cold front associated with the northern
trough has moved towards our northern zones with shower/embedded
thunderstorm activity.  The progression of this feature as it slowly
drops south /becoming increasingly parallel to the mid level flow/
will be our focus for the overnight forecast.

Through this evening: Showers have very slowly increased in coverage
over the past two hours and expect this to continue into the evening
with a couple of thunderstorms possible.  Some gusty winds remain
possible given modest DCAPE values especially over interior western
ME...but feel the severe threat is rather low.  By 8pm...expect
temperatures to fall back into the 70s for most spots...with MHT-ASH-
PSM likely remaining at or above 80.

Tonight: Waning instability should allow shower/storm activity along
the front to weaken with the front slowly moving towards southern NH
by daybreak Sunday. Interestingly...recent runs of the HRRR and the
07.12Z NAM are more robust with wave of low pressure forming off the
Delmarva overnight.  While this feature will remain well south of
our forecast area...it may help to back the llevel flow to more
southerly across southern New England towards daybreak
Sunday...potentially providing for lift over the stalled frontal
boundary. Thus...will carry a small chance for a shower towards
daybreak in this area.  The other potential sensible weather impact
will be fog....which is likely across the northern valleys where
there will be some partial clearing north of the front.  Depending
on frontal timing...some fog is possible along the coast of ME
before the flow turns northerly...but the window for this is pretty
short.  Cloud cover and the stalled front over southern areas will
lead to a warm and muggy night with a few spots potentially not
falling below 70...with 60s expected elsewhere.

&&

.SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/...
High Impact Weather Potential:
* Localized flood potential Sunday due to slow moving storms.
* Dense fog possible Sunday Night.

Sunday:  Stalled frontal boundary remains over southern zones with
the llevel boundary layer flow turning more southerly over New York
and western New England.  At the same time...weak area of surface
low pressure south of New England will sit and spin as it/s parent
wave remains cut off from the stronger mid level flow to the north.
The focus of our attention will be along the boundary and some
implied lift over it in the midst of very weak mid/upper level flow
given the cutoff to our south.   Temperatures aloft will be just a
bit lower than on Saturday with mid level lapse rates improving /H7-
5 lapse rates nearing 6C/km /  Thus...expect a decent amount of
instability /500-1000 J/kg MLCAPE/...but in the presence of less
than 10kts of deep layer shear.  Triggering mechanism will likely be
the residual frontal boundary likely draped somewhere across the
southern half of NH with the CAMs pinpointing this area as well as
the mountains as locations for convective initiation.  Slow moving-
pulse storms would be the favored mode which naturally suggests
flooding as the greatest concern.  CAPE profiles look skinny with
PWATs at or a bit above 1.5" with wet bulb zero heights over 11kft.
Thus...completely agree with WPC`s day 2 marginal risk of
excessive rainfall given what looks to be the potential for
isolated areas where flash flooding is possible. As for
temperatures...T8s will drop just a bit from today with upper
70s north to lower/middle 80s south. Despite the somewhat cooler
air aloft...llevel dewpoints look to pool some along the
stalled frontal boundary and therefore push over the 70F mark
over southern areas which may allow heat indices to again reach
the 90F mark in parts of southern NH.

Sunday Night: As mid level cutoff moves east over southern New
England...heights will actually rise over the Gulf of Maine.  This
will bring a building influence of high pressure over the Canadian
maritimes with marine air making a decided push west.  See little in
the way of forcing through the overnight for shower/storm activity
and thus...outside of dwindling PoPs in the evening given the loss
of instability will keep the night mostly dry.  What the marine
influence will likely encourage is fog development and will include
mention throughout the forecast area.  The setup favors the
potential for dense fog again in the northern valleys...but also
along the ME coast from PWM north to RKD and up to AUG. Another
relatively mild night will be in store...but a good bit cooler than
on Saturday night over the southern part of the forecast area given
the marine push.  Expect lows generally in the lower 60s.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
The main story next week will be increasing heat and humidity
over the region with bouts of showers and storms. We can thank
the synoptic/hemispheric pattern for this trend, with the
Bermuda high in place expanding west into the southeast
CONUS... which in turn sets up deep southwest flow into the
Northeast. Looking at ensemble anomalies and extremes, warm and
humid conditions peak late in the week... around Thursday into
Friday. This is well supported by CPC outlooks calling for a
60+ percent chance of above normal temperatures in the 6-10 day
period, indicative of the grander scale trend.

The coolest day next week will be the first one... on Monday, a
steady onshore flow will continue as cut off low pressure
crosses south of New England. As mentioned in the short term
discussion... the marine layer will be actively pushing into the
area with morning fog and possibly a stratus deck... in
addition to the higher clouds present from the upper level low.
Thus am expecting temperatures to be limited to the 70s over
Maine, warming to the low-80s by the time you get to the
Merrimack and Connecticut River Valleys. Coolest conditions
will be felt along the coast, particularly the Midcoast where
temperatures may struggle to hit 70. Cloud cover will have major
bearing on temperatures, so those trends are what we`ll look to
for the temperature forecast. A few showers are possible as the
cut- off low makes its closest approach later in the day.

Ridging behind the eastward- drifting cut off low will suppress
showers and storms through Tuesday, except for possibly over
the mountains and Connecticut River Valley with continued
S/SErly flow transporting a humid airmass upslope to where
better heating and instability can be realized. Still only have
just a slight chance of a shower or storm there however. The
remainder of the work week comes down to timing out subtle waves
generating showers and storms in westerly to southwesterly
upper level flow. Little confidence is offered in terms of
timing these waves, however the ever warming and moistening
atmosphere will almost certainly offer the instability to
produce diurnally driven shower and storm activity, enhanced and
prolonged into the overnight hours when forcing is nearby.

As mentioned previously the main story will be temperatures...
h850 temperatures are progged to trend steadily warmer Wednesday
through Friday with readings of +20C possible by early Friday
(and an ensemble mean a little closer to +18C). This may be
somewhat moderated by clouds from increasing convective
activity however. High temperatures thus increase to the 80s to
near 90 Wednesday to Friday, although it could go as warm as the
mid-90s where better mixing occurs (southern interior) by Friday.
When combined with dew points around 70 degrees, give or take,
conditions may warrant heat advisories across the southern
interior. On the flip side onshore flow will keep conditions a
little more hospitable along the Midcoast of Maine with highs in
the 70s to low-80s. Warm overnights may be the more impactful,
only cooling into the mid/upper-60s... closer to 70 for our
population centers, indicative of the humid air mass.

Toward the end of the week, there is deterministic model consensus
signaling a late-week cold front that will deliver relief from the
heat along with more showers and storms. Will curb my enthusiasm for
now since cold fronts that far out in model guidance tend to slow
and weaken as initialization nears the event... but the upper
level wave is there regardless. Just a matter of surface front
progression, which will be tricky since the front will be near
the international border for much of the latter half of the
week, waffling north and south as weaker waves pass aloft.

&&

.AVIATION /03Z SUNDAY THROUGH THURSDAY/...
Short Term...

Summary:  A cold front will settle into the region tonight with a
few showers and thunderstorms and some patchy overnight fog
developing.  Another round of isolated afternoon showers and
thunderstorms is expected on Sunday before more widespread stratus
and fog develop Sunday night.

Restrictions: VFR attm all sites and this will generally continue
through this evening outside of a few showers and embedded
thunderstorms which may impact LEB-HIE late this afternoon and early
evening.  Tonight...LIFR/IFR fog is likely at these terminals with
some fog possible at RKD/AUG as well.  On Sunday...isolated
restrictions in SHRA/TSRA possible away from the coast...with more
widespread IFR fog/low stratus for HIE/LEB and our ME terminals
Sunday night.

Winds: South and southwesterly winds around 10kts will diminish to
light and variable overnight and remain less than 10kts from the
south on Sunday before going calm/light-variable Sunday night.

Lightning: Isolated TSRA possible LEB-HIE through this evening and
again Sunday afternoon in all areas away from the coast on Sunday.

LLWS: No LLWS is expected through Sunday night.

Long Term...While VFR is expected to prevail for most of next
week, periodic restrictions are likely for all terminals with
little confidence in timing. MVFR/local IFR is possible in FG/BR
and low ceilings over the coastal plain early Monday. Tuesday
looks to be VFR except for perhaps some patchy fog early in the
morning. Wednesday through the end of the week features more
unsettled weather with daily restrictions chances in -SHRA/TSRA
and overnight BR/FG.

&&

.MARINE...
Short Term...Winds and waves are expected to remain below small
craft levels through Sunday night as a weak cold front settles
into the region and dissipates over the waters. Marine stratus
and fog is likely Sunday night as easterly flow begins to
develop.

Long Term...Next week starts with high pressure firmly in place
over the waters. While there will be steady pressure falls
through the week, culminating in what may be a late-week cold
frontal passage, conditions should remain fairly quiescent in
terms of winds and waves. Rain showers and a few storms will be
possible at times, but am not expecting a ton of activity over
the waters... with the most consequential weather conditions
likely being periods of fog.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...None.

&&

$$
SYNOPSIS...Arnott
NEAR TERM...Arnott/Cempa
SHORT TERM...Arnott
LONG TERM...Casey
AVIATION...Arnott/Casey
MARINE...Arnott/Casey



Area Forecast Discussion...UPDATED

National Weather Service Twin Cities/Chanhassen MN

 1058 PM CDT Sat Aug 7 2021

.UPDATE...
Issued at 724 PM CDT Sat Aug 7 2021

A Flash Flood Watch has been issued for parts of west central WI due
to the likelihood of training thunderstorms tonight into early
Sunday. A line that has since diminished had produced 2 to 4 inches
in the vicinity of Eau Claire earlier this evening. Similar
occurrences could unfold later this evening as another batch of
thunderstorms develops late. Otherwise, PoPs were reduced
substantially elsewhere this evening. Little forcing has prevented
development so far and it may wait until the compact, potent wave
over north central SD begins to approach.

&&

.SHORT TERM...(This evening through Sunday night)
Issued at 230 PM CDT Sat Aug 7 2021

Short term concerns haven`t changed much, and continue to focus on
potential for convection (possibly severe) this afternoon into
tonight. Latest mesoanalysis and satellite imagery show the surface
warm front near the Minnesota Valley at the current time. It
continues to make some progress northward, and should get near the
south metro by later this afternoon. MLCAPE south of the boundary is
in excess of 3000 J/Kg, but decent values exist on the "cool side" of
the boundary as well given the high dewpoints north of the front. The
best deep layer shear (per effective bulk shear) is mainly north/east
of the surface boundary, but there is some overlap where greater than
35 kt is available to storms. The best low level shear (per 0-1 km
bulk shear) is to the south in western Iowa and to the southeast of
the area. However, there is a ribbon along the frontal boundary where
winds are backed and values near 20 kt are indicated. So, there is
certainly sufficient instability for some severe storms capable of
large hail and downburst winds, and there is also at least a portion
of the area where supercells could produce isolated tornadoes late
this afternoon into this evening. The CAMs have struggled, as usual,
with much of the elevated convection we`ve seen, which makes it tough
to rely on their handling of redevelopment of boundary layer-rooted
convection this afternoon/evening. The HRRR has been reasonably
consistent in its runs today, and does manage to generate isolated
storms near the warm frontal boundary around/after 22Z, with more
widespread activity near and after sunset as the low-level jet
increases with the upper trough to the west getting closer. Given
that heights are currently rising a bit in southwest Minnesota ahead
of that trough (and the cap is strengthening per model soundings in
that area), it seems later timing make sense (other than perhaps some
isolated earlier storms forced along the boundary. All of the CAMs
increase the coverage of activity later this evening into the
overnight, so everything could certainly evolve more toward a heavy
rain scenario as the night progresses. The best chance for storms on
Sunday will be over the eastern portion of the area, but some low
PoPs seem warranted across most of the area given lingering
instability.

.LONG TERM...(Monday through Saturday)
Issued at 230 PM CDT Sat Aug 7 2021

Although we currently have an upper trough moving through it, the
large scale flow across the CONUS is predominantly zonal and looks to
remain that way through Tuesday. At that point, the upper low along
the British Columbia coast will be making its way into our region,
and looks to push through late Tuesday into early Wednesday, bringing
a renewed chance for precipitation as it drags a cold front through
the area. Ridging builds in the western CONUS and Canada in the wake
of that system, setting up northwest flow our area, which looks to
linger into next weekend. This should bring warm and dry weather for
the second half of the week in to next weekend with any precip
chances looking too low to mention at this point (tied to weak
shortwave troughs dropping southeast with the upper flow).

&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1058 PM CDT Sat Aug 7 2021

IFR cigs overnight across central and western Minnesota overnight.
Continued to leave -TSRA out of most TAF sites through the period
due to such low confidence in occurrence, however did add a tempo in
for MKT and EAU. Cigs will improve Sunday morning.

KMSP...IFR likely into early Sunday. Thunderstorms are still possible
toward sunrise, but confidence is low enough to keep mention from
this TAF issuance.

/OUTLOOK FOR KMSP/
Mon...VFR. Wind SE 5 kts.
Tue...VFR. Chc -TSRA. Wind S 5-10 kts becoming W.
Wed...VFR. Wind W 5-10 kts.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...None.
WI...Flash Flood Watch until 10 AM CDT Sunday for Chippewa-Dunn-Eau
     Claire-Pepin.

&&

$$

UPDATE...Borghoff
SHORT TERM...
LONG TERM...
AVIATION...Borghoff



Area Forecast Discussion

National Weather Service San Francisco Bay Area

 841 PM PDT Sat Aug 7 2021

.SYNOPSIS...Onshore flow during the afternoon and evenings this
weekend should help improve air quality from yesterday`s smoke.
Gradually cooler and wetter conditions over the coming days and
into early next week, then, warmer and drier late next week.

&&

.DISCUSSION...as of 08:41 PM PDT Saturday...Much of the state
remains blanketed in smoke from various wildfires while satellite
imagery shows low clouds along much of the coastline. Expect low
clouds to move inland to the valleys overnight and persist through
mid to late tomorrow morning before dissipating. The marine
layer is still sitting at about 1,500 ft AGL per the Fort Ord
Profiler. Humidity values along the coast are quite high between
about 70 and 90 percent where inland locations and areas above the
marine layer are still fairly dry in the 20s and 30s. Temperatures
this evening are about 5 or so degrees cooler than yesterday as an
upper trough sits off the coast of the Pacific Northwest. The
forecast remains on track with continued cooling tomorrow by about
5 or so degrees. Expect afternoon highs in the 60s to low 70s
along the coast, 70s to low 80s around the Bay Shoreline, and mid
80s to mid 90s inland. Gradual warming is then in store for next
week as high pressure builds over the eastern Pacific and over the
Great Basin simultaneously. Triple digit heat may be headed our
way late next week and into the weekend across the interior. Will
have more details over the coming days.

The latest HRRR smoke model forecast shows gradually improving
total and near surface smoke tomorrow afternoon and evening as we
get another good push of onshore winds. Smoky conditions look to
linger a bit longer at the far eastern boundaries of the forecast
area into tomorrow night, but should still be an overall
improvement compared to the past couple of days. For additional
details please see the previous discussion.

&&

.PREV DISCUSSION...as of 01:45 PM PDT Saturday...Early afternoon
satellite imagery definitely does not show clear skies across the
state for us today. Instead, a vast swath of wildfire smoke exists
throughout most of non-coastal Northern and Central California
and remnant marine stratus and stratus eddy circulations but less
smoke populate the coastal areas. This smoke is sourced from a
number of wildfires, including the Dixie, River Complex, Monument,
and McFarland, but it is primarily the smoke that was transported
southward on the lee of Thursday night`s trough from the Siskiyou
and Trinity county fires that have resulted in our local hazy to
smoky conditions yesterday and again today. While we are not
directly receiving smoke from the Dixie fire as it is transporting
S-SE, it is worth noting at the state level that this fire has
become historic in size/impacts and has prompted to closure of
Lassen National Park and damaged or destroyed communities near
Lake Almanor.

Thus far, the wildfire smoke has been modeled fairly well by the
HRRR, both at the near-surface and total column data levels. The
HRRR may not have completely nailed the timing or coverage, but
the main message was spot on. This message indicated that most
smoke would remain suspended aloft above the marine layer, some
would filter down midday prior to the arrival of the sea breeze,
and then the afternoon/evening seabreeze would push the smoke
deeper inland without completely clearing it out. This scenario
played out yesterday and is expected to play out again today, and
once more tomorrow. Each smoke day has/will see successively more
onshore flow and lower smoke concentrations between yesterday and
tomorrow. Latest HRRR near surface/vertically integrated datasets
indicate that tomorrow`s onshore seabreeze should be sufficient in
evacuating most of the smoke out of the coastal and bayshore
areas, while some may continue to linger in the deeper reaches of
the interior valleys. Additional pulses of more smoke from the
north is possible over the coming days, but given a tendency
towards weaker fire growth in the fires to the north, and more of
easterly component to the the transport winds, the worst looks
behind us...at least for this event, by tomorrow evening.

Please use this event as a reminder that the state is in a
significant drought and more wildfires are likely. This is the
perfect opportunity to consider your plans to mitigate the impacts
of worse smoke events or potential wildfires in your area.

Smoke aside, today is running 3 to 10 degrees cooler than the same
time yesterday as a cooler, moister air mass settles in to place
behind the retreating high pressure influence to the south. This
trend will continue into Sunday with further cooling and deepening
of the marine layer expected for tonight into tomorrow as low
pressure troughing nudges nearer from the northwest.

Looking ahead to the coming week, seasonable conditions will
become gradually warmer and drier as ensemble cluster analysis are
all in good agreement that strengthening high pressure along our
periphery is in our future. Both an eastern Pacific/Gulf of Alaska
high and Great Basin high are looking increasingly likely to
build to our north and east and could both eventually strengthen
and merge into a more robust high pressure system along our
borders by mid to late next week. Surprisingly, not seeing a lot
of higher temperatures associated with this potential scenario in
the ensembles members just yet, but given that NBM percentiles
show possibilities of record temperatures just along and offshore
of the Central Coast... have decided to nudge days 5-7 closer to
the hottest 90th percentile of members in order to at least
account for the possibility of warmer conditions. That said, could
see triple digit air temperatures throughout the interior by late
next week. It remains to be seen what these potential warmer (and
drier) conditions could do to fire behavior... and production of
smoke. Smoke trapped under any possible heat ridge would be tougher
to scour out than it would be under neutral flow or troughing.

&&

.AVIATION...as of 05:05 PM PDT Saturday...For the 00z TAFs.
Satellite imagery shows stratus has cleared back to the coast,
though wildfire smoke is pervasive. This will reduce slant range
vis through the period. As onshore breezes pick up this afternoon,
smoke may collect downwind in interior valley locations,
potentially reducing surface vis at terminals such as KLVK. HZ
should also be pervasive, at least until onshore winds help clear
out suspended particulates closer to the coast. Stratus will
return tonight as the marine layer should rise to around
1500-2000ft. Potential for MVFR/IFR/local LIFR CIGs and reduced
vis from HZ/BR. Cigs will lift with lingering HZ as smoke exits
the region.

Vicinity of KSFO...VFR. Stratus remains offshore, with a few
remnant low clouds around the terminal. Hazy skies are observed on
area webcams, which will likely impact slant-range vis throughout
the day. Typical onshore winds build this afternoon. Medium
chance for CIGs returning overnight into Sunday morning around the
terminal, with potential MVFR/IFR conditions. HZ will begin to
mix out by the end of the TAF period as smoke exits.

KSFO Bridge Approach...Similar to KSFO.

Monterey Bay...IFR/VFR. Satellite imagery shows stratus over the
Bay, Monterey Peninsula and coastal areas. KMRY/KSNS currently VFR
but IFR at KOAR/KWVI. These terminals may see CIGs through early
afternoon with lingering FEW/SCT through the day. Slant-range vis
impacts possible through the day due to FU/HZ. Early return of
low CIGs this evening, reducing to IFR/LIFR conditions under
stratus and BR/HZ. Cigs will then lift by 16-18Z with lingering HZ
through the early afternoon.

&&

.MARINE...as of 08:35 PM PDT Saturday...Gusty northwest winds
will continue over the northern outer waters through the rest of
the weekend with light to moderate breezes across the rest of the
waters. Additionally, gusty westerly winds are expected in the
afternoons and evenings through the Golden Gate gap and into the
Delta. These winds will generate steep waves which may be
hazardous for smaller vessels. The sea state remains dominated by
steep short period northwest waves at 7 to 9 seconds along with a
moderate period southerly swell.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .Tngt...SCA...Pt Arena to Pigeon Pt 10-60 nm
             SCA...SF Bay until 9 PM

&&

$$

PUBLIC FORECAST: AS/DRP
AVIATION: Diaz
MARINE: Diaz

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Area Forecast Discussion

National Weather Service New York NY

 942 PM EDT Sat Aug 7 2021

.SYNOPSIS...
A weak low slowly tracks towards Long Island tonight and then
offshore on Sunday. The low then drifts away from the region and
dissipates later Monday and Monday night. High pressure remains
over the western Atlantic for much of the week. A cold front
approaches very late in the week.

&&

.NEAR TERM /THROUGH SUNDAY NIGHT/...
A weak low pressure was located near Wallops Island as of 9 pm.
Showers are located on the northern quadrant of the low, moving
along the Delaware and southern New Jersey coastline. Regional
radar mosaic shows some of this activity approaching the Long
Island coastline and the NYC metro. However, rain has only been
reported as far north as Atlantic City so far.

The 00z OKX RAOB shows a significant amount of dry air between
500 and 625 mb with RH below 5%. There is also dry air below 625
mb down to the surface. This dry air is going to make it
difficult initially for anything more than a few sprinkles to
make it down to the surface. Some the returns out there may also
diminish as well until the low pressure and stronger lift are
able to saturate the column. Subsidence to the north of the low
will also aid in making it difficult for rain to spread
northward tonight. Have adjusted PoPs to account for the latest
trends. There remains a fair amount of spread in the model
guidance, but the latest 00z HRRR seems to be initializing fairy
well to the current environment.

The latest thinking is that the Lower Hudson Valley and
southern Connecticut should largely be dry tonight with just
mostly cloudy to overcast conditions. A few sprinkles are
possible near the NYC metro and Long Island coast around or just
after midnight with some showers possible towards day break. Do
not anticipate any of this activity to be on the heavy side as
the lingering dry air and subsidence north of the low is going
to be make it difficult, especially given the compact nature of
the low. There could be a few moderate showers that make it
across Long Island in the morning, but largely the bulk of the
substantial showers should stay just south of the coast.

Otherwise, for Sunday a light onshore flow for the most part,
along with a good deal of cloud cover will keep temperatures at
bay. Expect temperatures overall to average touch below normal
with middle and upper 70s across southeastern most coastal
sections, to the lower 80s further inland. Clouds will be locked
in once again, and the synoptic set up will favor more stable
conditions in the lower part of the column. Thus have gone with
mainly showers as wx, and have kept out mention of thunder for
the most part for now. The exception cloud be for northern parts
of the Hudson Valley where an isolated t- storm is possible
with more breaks of sunshine, but the overall chances are low
for Sunday afternoon and evening. QPF amounts for the low
pressure system nudging up from the south should be on the order
of a half inch or so across extreme southeastern sections,
otherwise look for a few hundredths of an inch elsewhere.

For Sunday night look for decreasing clouds very gradually from
west to east across the area. Dew point readings overall should
remain well into the 60s, thus it will remain humid with night
time temperatures continuing to run near normal. As the low
slowly pushes northeast look for the ongoing chance of showers
across eastern most sections, with mainly dry conditions
elsewhere.

&&

.SHORT TERM /MONDAY THROUGH MONDAY NIGHT/...
On Monday with little in the way of a pressure gradient look for
light winds mainly onshore to begin the day, but then veering to the
southeast, then south into Monday night. With more sunshine on
average across the area, especially west on Monday look for
temperatures to be a few degrees warmer with mainly 80s, with a few
upper 70s across eastern coastal sections. More instability is
expected by later Monday afternoon, especially further inland so a
slight chance of a thunderstorm was included for Monday afternoon
and the early evening across the northwestern interior. Any activity
should be weak. As far as temps and humidity levels, forecast
highs for now have been kept the same with mainly middle and
upper 80s for today with a few metro spots hitting 90 across NE
NJ. Dewpoint readings indicate moderate humidity with mainly
lower and middle 60s through the day.speed shear. The moderately
humid conditions will continue into Monday night with dew
points remaining mostly well into the 60s, and night time
minimum temperatures in the middle 60s to the lower 70s.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
High pressure over the western Atlantic will result in a typical
summertime airmass with increasingly hot and humid conditions. This
comes from a continuous south to southwest flow that will be in
place as a result of the region being on the western periphery of
surface high pressure that will be anchored out in the Western
Atlantic.

With respect to temperatures, which will be the main highlight for
the week, continued to run with the, NBM 50th percentile which
continued to be slightly warmer than other guidance sources. Models
are showing a consensus of warming 850mb temperatures to 16 to 18
degrees C Tuesday through Thursday. With temperatures rising well
into the 80s and low to mid 90s, coupled with dew points in the
upper 60s and lower 70s, heat indices should warm into the mid 90s
to lower 100s, with the warmest day on Thursday. For now, Friday
should be slightly cooler, but still warm with heat index values in
the 90s.

As we typically see here in our area, the highest temperatures and
heat indices will occur in the NYC Metro, urban Northeast NJ
corridor extending into Nassau and southern parts of Lower Hudson
Valley into SW CT. For now, it appears the best days for any
potential heat advisory criteria to be met would be Tuesday through
Thursday, and potentially Friday.

There will be a chance each afternoon for showers and thunderstorms
each afternoon as daytime surface troughs development. Chances each
afternoon will gradually increase through the week. A cold front
approaches late in the work week into the first half of the
weekend.

&&

.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
High pressure slowly weakens tonight as weak low pressure
approaches from the Middle Atlantic coast late tonight into
Sunday. The low should remain just south of Long Island Sunday.

VFR tonight. MVFR may develop early Sunday morning as some
mainly light showers occur near the coast. Showers are possible
near NYC and coastal terminals the rest of the morning, then
possibly continuing over Long Island terminals in the afternoon.
MVFR ceilings are most likely to occur in the morning, with
some improvement to VFR in the afternoon. KISP should see MVFR
conditions last the longest into Sunday evening.

S-SW winds around 10 kt or less this evening will diminish
overnight. Winds will be light and/or variable overnight. The
wind direction should become NE- ENE late tonight and continue
into Sunday, 5-10 kt.

     NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...

Amendments likely for showers and flight categories tonight
into Sunday morning.

.OUTLOOK FOR 00Z MONDAY THROUGH THURSDAY...
.Sunday night...VFR, MVFR is possible early. A chance of
showers in the evening.
.Monday...VFR. An isolated shower possible with local MVFR.
.Tuesday...VFR. A slight chance of thunderstorms in the afternoon
and early evening north and west of the NYC terminals.
.Wednesday...VFR. Chance of showers and thunderstorms in the
afternoon and evening with MVFR possible.
.Thursday...VFR. A chance of showers and thunderstorms, likely
across the lower Hudson Valley, in the afternoon with MVFR
possible.

Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90

&&

.MARINE...
Wind gusts at times tonight will approach 20 kt across some of
the southern most near shore waters and the ocean, but sub-SCA
conditions should still prevail. Ocean seas may approach 4 ft at
times through Monday, otherwise sub-SCA conditions are expected
through the remainder of the forecast period Tuesday through
Thursday.

&&

.HYDROLOGY...
No hydrologic impacts are expected through the forecast period.

&&

.TIDES/COASTAL FLOODING...
There is a moderate rip current risk thru Monday.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...None.

&&

$$
SYNOPSIS...BC/JE
NEAR TERM...JE/DS
SHORT TERM...JE
LONG TERM...BC/JE
AVIATION...DS
MARINE...BC/JE
HYDROLOGY...BC/JE
TIDES/COASTAL FLOODING...



Area Forecast Discussion

National Weather Service Phoenix AZ

 407 PM MST Sat Aug 7 2021

.UPDATE...Updated Aviation Discussion.


&&

.SYNOPSIS...
Temperatures will remain near normal this weekend with little
chance of rain. High pressure lifting north of the region early
next week will allow deeper moisture to return to the Desert
Southwest. Conditions will become more favorable for showers and
storms along with higher chances of below normal temperatures.

&&

.DISCUSSION...
Latest RAP streamline analysis depicts a well-defined mid-
latitude trough moving steadily eastward into the northern Plains.
This has suppressed the Monsoon High into southern Arizona,
generally resulting in a westerly flow across the Desert
Southwest. While conditions remain moist at the surface with
dewpoints in the lower 60s, water vapor imagery reveals dry air
aloft overspreading much of the region.

Latest mesoanalysis indicates PWATs of only 1.3 inches across
central Arizona. This mornings 12z PSR sounding also showed a
mid-level subsidence inversion, which is hindering convection this
afternoon. The only exception has been across far eastern Gila
County, where isolated storms have developed along the tail end of
the aforementioned trough. Latest CAM ensemble indicates little
potential for activity late this afternoon and this evening and
PoPs generally remain below 5 percent. Time-lagged HRRR also
suggests very low probabilities for outflow winds above 35 mph.

The anticyclone will weaken somewhat Sunday, however dry westerly
flow will persist and conditions will generally remain
unfavorable for showers and storms. Latest HREF indicates perhaps
an isolated cell across Pinal County, though maximum winds will
likely remain below 40 mph. Thereafter, models continue to suggest
an increased chance of convection Monday, owing to an increase in
moisture associated with an approaching inverted trough. An
increase in clouds will also temper the heat with forecast high
temperatures likely dropping into the lower 100s, which is a few
degrees below normal for this time of year.

&&

.PREVIOUS DISCUSSION...
Beginning Tuesday a balanced mix of the Cluster family start to show
some signals of increasing QPF and storm chances. This is the
result of Clusters favoring anomalous high pressure repositioning
further to the N and NW of the region which should give easterly
waves and inverted troughs in N MX better access to S-Cent AZ.
However there is still plenty of uncertainty on the timing and
position of any storm intrusions into the region. For now NBM POPS
favor 20-40% by Tue-Wed while WPC QPF remains mainly on the
modest side. GEFS plumes mean QPF favors fairly diurnal rainfall
amounts around Phoenix of approx 0.05-0.07"/day beginning Tue
through late in the week. NBM POPs have also nudged up into the
low double digits (10-20%) for SW AZ and SE CA by the middle of
the week.

What is more certain is the moderating effect that the increase in
moisture will have on temperatures next week. Highs are favored
to fall to below normal by Monday. After that below normal high
temperatures remain favored through late next week with highs
mostly in the low 100s around Phoenix and 105-110 degrees out west.

&&

.AVIATION...Updated at 2310z.

South-Central Arizona including KPHX, KIWA, KSDL, and KDVT: Current
stronger than typical westerly winds will continue into the
evening, with gusts of 18-22 kt likely. West winds are likely to
persist overnight at weaker speeds, with low confidence in any
easterly shift occurring at KPHX, while outlying terminals are
more likely to see a shift to easterly closer to sunrise. Chances
for thunderstorms in the terminal area are low, below 10%, but a
few storms could develop close enough to the terminal area giving
a 10-20% chance for outflow winds from the south or east. Chances
for blowing dust capable of reducing visibility cannot be ruled
out, with chances around 10%. On Sunday, westerly winds will
increase during the daytime hours, similar to what was seen today.
Thunderstorms are not expected.

Southeast California/Southwest Arizona including KIPL and KBLH:
There are no major aviation weather concerns. At KIPL, light
southerly winds will shift back to southeasterly winds overnight
and continue into Sunday. At KBLH, winds will favor the south to
southwest at speeds of 9-14 kts and early evening gusts nearing
25 kts.


&&

.FIRE WEATHER...
Monday through Friday:
Highs over S-cent AZ will settle a few degrees below normal and
near to slightly above normal in western areas. Storm chances
increase Monday and especially Tuesday and Wednesday, with an
increasing signal for possibly locally heavier rainfall over
south-central Arizona by the middle of next week. Humidity values
also improve Tuesday and beyond with the increasing moisture and
slightly cooler temperatures. Min RH will remain above 20% in all
areas except for the drier parts of SE CA where they will
occasionally fall into the upper teens. Apart from thunderstorms,
anticipate diurnal southerly breeziness over southeast CA and
southwest AZ during the afternoon and evenings (lighter
overnight/morning hours). Lighter diurnal winds are favored
elsewhere including westerly directions in the afternoon and
evening (modest breeziness at times), then favoring downvalley
patterns in the overnight and morning hours.

&&

.SPOTTER INFORMATION STATEMENT...
Spotters should follow standard reporting procedures.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&

$$

DISCUSSION...Hirsch
PREVIOUS DISCUSSION...Sawtelle
AVIATION...Hodges/Rogers
FIRE WEATHER...Sawtelle



For frequently asked questions about the Area Forecast Discussion

visit...

 http://weather.gov/saltlakecity/general/afd_faqs.php



Area Forecast Discussion

National Weather Service Las Vegas NV

 840 PM PDT Sat Aug 7 2021

Updated Aviation Section

.SYNOPSIS...Smoky skies will persist in areas along and northwest of
Interstate 15 through the weekend, and perhaps beyond. Dry weather
and minor breezes are expected this weekend with near to slightly
above average temperatures. Looking ahead to next week, a return of
monsoonal moisture looks likely, especially for northwest Arizona.
Chances for showers and thunderstorms return to the forecast for the
middle of next week and possibly into the weekend.
&&

.UPDATE...Smoke continued to plague much of southern Nevada,
northern Inyo County, and far northern Mohave County this afternoon.
Area webcams and surface observations have shown some improvement in
the smoke this evening, with visibility slowly increasing as the
smoke plume retreats to the north. Think this trend will continue
through early tonight as northerly flow diminishes slightly. This
also matches up with HRRRSmoke trends through tonight, which shows
near surface smokes lifting out of Clark, Nye, and Esmeralda
counties. However, as the flow turns more west, additional smoke
from central California will likely spread over the region from west
to east. So it is likely that, while there may be improvement in
conditions tonight, smoke will move back in by Sunday morning to
many of the same areas that dealt with smoke and haze today.

Other than the smoke issues, quiet weather is expected tonight.
Light winds, clear skies (where not obscured by smoke), and dry
conditions are expected. Overnight lows should be comparable to
last night.
&&

.PREVIOUS DISCUSSION...145 PM PDT Sat Aug 7 2021
.SHORT TERM...through Sunday night. Visible satellite loop showed
very few clouds areawide, with thick smoke blanketing the southern
Great Basin and northern Mojave Desert, roughly along and north of a
line from Olancha to Las Vegas to Mount Trumbull. Most of the smoke
originated from the wildfires in northern California, most notably
the Dixie Fire. The 18Z run of the HRRR Smoke model shows very
slight erosion from the south through the early evening, but then
another slug of smoke west of the Sierra makes it to the Tehachapi
Gap, catches the typical evening westerly wind push in that area,
and makes it all the way to Las Vegas and the Colorado River by
early Sunday morning. The smoke has held temperatures down below
forecast highs today, and with another murky day in store for all
but the southeast third of our area tomorrow, manually adjusted
forecast highs down for Sunday as well.

.LONG TERM...Monday through Saturday.
Models continue to show a more active weather pattern developing
across the region next week. Both the EC and GEFS show a broad
high developing over the four corners region early in the week.
This high will then gradually shift westward and elongate during
the second half of the week. Both models are also hinting at a
series of inverted troughs passing south off the area across the
Sonoran Desert on Tuesday and again on Saturday. The combination
of these features should result in increasing southeasterly flow
aloft that will bring higher moisture levels from northern
Mexico. The chance of thunderstorms should return to Mohave county
as early as Monday, with daily chances likely continuing into
next weekend. Storm chances should also return to higher
elevations of southern Nevada and the Mojave Preserve by Tuesday
and the Sierra on Wednesday. Initially the activity in these
areas will be more isolated, but coverage should increase as the
week progresses. With the increase in moisture and cloud cover
next week, temperatures are expected to stay within a few degrees
of normal.
&&

.AVIATION...For McCarran...Smoke clearing to the north overnight
will be replaced by additional smoke coming in from around
Bakersfield early Sunday morning about 12Z. The latest indications
are that the smoke will not be as dense as Saturday morning and
visibility will most likely drop no lower than around 4SM between
14Z and 19Z. However, there is a slight chance it could drop to near
2SM. Partial clearing in the afternoon should improve visibility to
around 6SM or higher followed by further clearing Sunday evening.

For the rest of southern Nevada, northwest Arizona and southeast
California...Smoke and haze due to wildfires will be the primary
concern through Sunday evening. Brief clearing at KBIH this evening
and overnight will give way to another smoke influx around 14Z
Sunday with VSBY values likely around 2SM Sunday morning then
improving to 4SM Sunday afternoon. Southern NV will see clearing
overnight before smoke returns early Sunday from the west with VSBY
generally 4-6SM. Fairly dense smoke should remain near and north I-
15 which may limited VSBY at DAG to around 6SM at time, but
should stay north of IFP and EED.
&&

.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any significant weather or impacts according to standard operating
procedures.
&&

$$

UPDATE...Nickerson
SHORT TERM...Morgan
LONG TERM...TB3
AVIATION...Adair

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