Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/13/22

AREA FORECAST DISCUSSION

National Weather Service Bismarck ND

 922 PM CDT Fri Aug 12 2022

.UPDATE...
Issued at 919 PM CDT Fri Aug 12 2022

Models are in pretty good agreement with fog developing northwest,
central, and east tonight, so did go with areas versus patchy.
Also increased sky cover this evening with no signs of the low
stratus going anywhere across my east, with an expansion west
expected overnight.

UPDATE Issued at 639 PM CDT Fri Aug 12 2022

The forecast for this evening remains on track. Low clouds linger
across much of the eastern half of the state. Should see some
improvement northeast, but latest RAP and HRRR keep the sky mainly
cloudy across the James Valley through much of the night and into
Sat morning. Didn`t go all in with these models, but did trend sky
cover upwards. Still on track for fog development late tonight.
For now will keep patchy wording, but I may up the coverage with
the next update based on the RAP and HRRR model solutions, the
rich boundary layer moisture in place, and light winds projected
from the highway 83 corridor and east.

&&

.SHORT TERM...(This Evening through Saturday)
Issued at 234 PM CDT Fri Aug 12 2022

The primary concerns in the short term period will be fog
potential tonight and thunderstorm chances Saturday.

Afternoon visible satellite imagery shows mainly high clouds in
western parts of the state with stratus still lingering in the
central and east. Short term models still suggest the stratus
should diminish this afternoon, however there has been a fairly
persistent signal in the HRRR that low clouds and fog are possible
again later tonight. This makes sense with a surface ridge axis
in place from across the central and eastern parts of the state,
though there is a bit more of a pressure gradient in the west. NBM
point forecasts even suggest IFR and / or LIFR are possible,
especially central and east. Will introduce patchy fog for tonight
as a start and see how things progress.

Tonight should be dry, though a weak wave moving across Montana
in the upper ridge could trigger a few showers / thunderstorms to
our west. In general CAMS suggest those should weaken / die out
before reaching North Dakota tonight.

That changes on Saturday with HREF paintball composite
reflectivity greater than 40 dbz showing more short term model
solutions bringing at least isolated activity into the western
parts of the state. It appears those should not have much
instability to work with at least initially, but MUCAPE values do
approach 1000 J/kg in parts of the west during the afternoon.
Deep layer shear values also increase by afternoon, and SPC has
now placed parts of western North Dakota into a Marginal Risk for
Day 2 (Saturday). We plan to acknowledge that in the updated
Hazardous Weather Outlook by introducing the mention of a
potentially strong to severe storm Saturday afternoon and evening
in parts of the west.

.LONG TERM...(Saturday Night through Friday)
Issued at 234 PM CDT Fri Aug 12 2022

A stronger wave appears to move through the upper ridge Saturday
night with an increasing model consensus for the better chances of
showers / thunderstorms in the northern part of the state. Beyond
Saturday night, the rest of the long term period will generally
feature an H5 ridge across the western / central United States
with waves riding across it at times in the Northern Plains.
Though the big picture is fairly clear in regards to the overall
pattern, details regarding the small waves moving through the
ridge are difficult to time. Will continue to follow along with
the NBM overall in the later periods which seems to capture the
trends. One thing to note towards next weekend (and a little
beyond) is that some model solutions begin to suggest a break down
in the upper ridge. That being said, cluster analysis would
suggest that is a lower probability scenario than the ridge
persisting.

&&

.AVIATION...(For the 00Z TAFS through 00Z Saturday Evening)
Issued at 639 PM CDT Fri Aug 12 2022

Low clouds still slow to clear in the east, mainly for KJMS where
MVFR conditions remain and will likely persist. Low clouds and
fog are forecast to redevelop tonight, impacting KBIS, KMOT, and
KJMS. Some short term model solutions would suggest IFR conditions
in low clouds and fog possible as well. Conditions should improve
with time Sunday morning after 14Z or so. Chance for thunderstorms
increase mainly across the northwest (KXWA) after 12Z. Low
probability so did not introduce this for the TAF with this
issuance.


&&

.BIS WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

UPDATE...NH
SHORT TERM...King
LONG TERM...King
AVIATION...NH



Area Forecast Discussion

National Weather Service Boston/Norton MA

 1042 PM EDT Fri Aug 12 2022

.SYNOPSIS...
Dry and quiet weather for the most part as high pressure builds
in from the Great Lakes area. Low chance of an isolated shower
overnight and early Saturday morning as a weak boundary passes
east of Cape Cod. Comfortable temperatures with low humidity
values expected this weekend along with mainly sunny skies. An
unsettled and slow-evolving weather pattern then develops into
the middle of next week. While not yet set in stone, the
potential exists for welcomed rains Tuesday through Thursday.
Near to below normal temperatures are likely this weekend into
midweek.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...

10:30pm Update...

No major changes to the forecast. currently watching a couple of
showers in southern RI that should dissipate in the next hour
or so. Also monitoring a precip shield south of the region that
may clip Nantucket and the Cape overnight.


Previous Discussion...

7:50pm Update...


* Very low chance of an isolated shower this evening, especially
  near seabreeze boundaries across eastern MA.

* Elevated fire weather concerns for Massachusetts through this
  evening as a result of lower humidity and ongoing drought
  conditions.

No major changes to the forecast this evening. Watching a pair
of isolated showers across portions of eastern MA. These showers
developed along the seabreeze front. With the loss of daytime
heating, expecting these showers to dissipate quickly over the
next hour or so.

The rest of tonight should feature mainly dry weather across
southern New England. Just starting to see the northern edge of
an area of rainfall approaching the Cape and islands on radar.
The current trajectory of this rainfall looks like it will
remain mostly offshore, but will continue to monitor trends
through this evening. The last couple runs of the HRRR captured
the isolated showers rather well, so used it as the basis for
this forecast update.

4:00PM Update...

Dry weather prevails through Friday evening as surface high
pressure extends out of the Great Lakes area. Clouds do linger
across southeast Massachusetts, Cape Cod, and the Islands as
seen on visible satellite. Shower activity has been suppressed
much of today south of Block Island, Martha`s Vineyard, and
Nantucket as a weak cold front sits off shore. Aloft a mid-level
trough digs south with short wave energy along the eastern
periphery in tandem with a weak low pressure system. It`s not
out of the question an isolated shower may develop south of the
Route 44 in Massachusetts and south of I-95 in Rhode Island,
POPs here are generally less than 20 percent through midnight.
Not good for the drought and for potential fire weather.

A dry airmass combined with severe to extreme drought conditions
will result in elevated fire weather concerns through this evening.
Relative humidity values drop to between 25 and 35 percent across
much of the interior with northwest winds 10 to 15 mph.

Overnight and into early Saturday POPs will increase, slightly,
between 20 and 30 percent across the islands and immediate south
coast of Rhode Island and Massachusetts. The purpose of having POPs
here during the overnight hours is due to a weak low passing off
shore. Moving away from the coast cloud cover should thin and given
fairly weak winds during the overnight hours, went with the cooler
guidance of the NBM. Generally most have temperatures in the upper
50s to low 50s with the hills of western Massachusetts having
temperatures in the low to mid 50s. Wouldn`t be shocked to see a
few upper 40s across the higher western terrain of Franklin,
Hampshire, and Hampden Counties.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...
Highlights...

* Stunning start to the weekend with mainly dry conditions,
  comfortable temperatures, and low humidity.

Mid-level trough exits the northeast and surface high pressure
from the Great Lakes region extends into the northeast. Outside
of an isolated morning shower on south shore of Rhode Island,
Massachusetts, Cape Cod, and Islands we are dry! Beautiful
conditions for Saturday afternoon because of the drier air mass.
PWATs fall and are between 40 and 60 percent of normal for mid
August. For cloud cover went with HREF, a few fair weather
cumulus clouds but otherwise a mostly sunny day. Because of the
drier air mass our dew points will remain lower then normal,
possibly feeling more like early fall as the dew point
temperatures are upper 40s to low 50s across the interior and
upper 50s to low 60s at the coast.

Look for high temperatures in the mid and upper 70s, a few
locations that may reach 80F or 82F include the Connecticut
River Valley from Hartford to Springfield. Saturday night is
dry and expect clear sky cover, because of this went with the
cooler of the guidance once again as radiational cooling is
expected. Coolest locations will be felt in the east slope
communities in the Berkshires and northwestern Worcester Hills.
Else where, temperatures will fall to the mid and upper 50s.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
Highlights:

* Generally dry Sunday with below normal temperatures.

* Unsettled early to midweek, and while not yet set in stone,
  potential continues for rainy conditions Tue-Thu.

* Below normal temperatures continue into most of the upcoming week,
  with lower humidity levels continuing.

Details:

The latest guidance suite has not added much confidence to the
forecast. Significant detail differences remain regarding the
track of a low pressure moving north along the coast next week.
How close this low pressure can track to southern New England
will play a major role in determining how much rainfall can
actually fall from this system. Some guidance sources bring a
decent amount of rainfall, while others continue to have us
remain dry.Most of the modeled solutions do tend to draw this
low pressure closer to the coast Wednesday into Thursday, but
through the Gulf of Maine.

Southern New England could really use significant rainfall to
help alleviate drought conditions. Unfortunately, at this time,
only looking at a 15-20 percent chance of one half inch or more
of rain in any 24-hour period Tuesday into Thursday. The odds
are generally less than 10 percent for one inch of rain in a
24-hour period during this same portion of the week. While there
is a chance for some wet weather next week, it is not looking
to be very heavy overall. These details will take some time to
come into better focus.

Temperatures through next week are expected to be generally
near normal low temperatures with below normal high
temperatures, owing to increased clouds and possible showers.
NBM temperatures looked reasonable.

&&

.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
Forecaster Confidence Levels:

Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.

Tonight...High confidence.

Mostly VFR. Best chance for MVFR/IFR ceilings and patchy fog across
southeast MA. N winds at 5 to 10 kt.

Saturday...High confidence.

Mostly VFR. Best chance for MVFR/IFR ceilings across southeast
MA, improvement during early afternoon. N/NE winds at 5 to 10
kt.

Saturday Night...High confidence.

VFR. Winds are light and variable.

KBOS...High confidence.

KBDL...High confidence.

Outlook /Sunday through Wednesday/...

Sunday through Sunday Night: VFR.

Monday through Monday Night: VFR. Slight chance SHRA.

Tuesday through Wednesday: VFR. Breezy. Chance SHRA.

&&

.MARINE...
Forecaster Confidence Levels:

Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.

Through Saturday Night...High confidence.

Mostly cool and cloudy with seas and winds below SCA thresholds.
There will be periods of light showers at times, especially this
evening and then on Saturday morning. Winds becoming north
overnight and remain through Saturday night.

Outlook /Sunday through Wednesday/...

Sunday through Sunday Night: Winds less than 25 kt.

Monday through Monday Night: Winds less than 25 kt. Slight
chance of rain showers.

Tuesday: Winds less than 25 kt. Seas locally approaching 5 ft.
Chance of rain showers.

Tuesday Night through Wednesday: Winds less than 25 kt. Seas up
to 5 ft. Chance of rain showers.

&&

.TIDES/COASTAL FLOODING...
There is a limited threat for minor splashover due to the high
astro tides, for the high tide around midnight, for those
communities along the east coast of Massachusetts, this includes
Cape Cod and Nantucket.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...None.

&&

$$
SYNOPSIS...Belk/Gaucher
NEAR TERM...Belk/Gaucher/Pederson
SHORT TERM...Gaucher
LONG TERM...Belk
AVIATION...Belk/Gaucher
MARINE...Belk/Gaucher
TIDES/COASTAL
FLOODING...



Area Forecast Discussion...Updated

National Weather Service Billings MT

 852 PM MDT Fri Aug 12 2022

.UPDATE...

Tweaked PoPs through the rest of the evening and overnight. The
latest runs of the HRRR have continued to take a line of
thunderstorms across the Musselshell River Valley and across into
Custer County. This will likely be the southern end of the line of
storms across North Central Montana. Wind gust swaths from the
HRRR have been trending downward in strength, so still not
expecting any widespread issues. With the strongest activity early
this afternoon only saw gusts into the lower 40s, which was lower
than the guidance had been showing. Reimer

&&

.DISCUSSION...

This afternoon through Sunday night...

Upper level flow will remain southwesterly with a jet cutting
across western and northern Montana, through the weekend. This
flow and associated upper level energy will tap into a steady
Monsoonal moisture fetch to bring isolated to scattered afternoon
and evening showers/thunderstorms to the lower elevations.
Mountain locations can expect even better chances for
precipitation, and locally heavy rainfall will be possible. Will
continue to keep an eye on burn areas for possible flash
flooding/debris flows in this pattern, but right now storm
coverage doesn`t look to warrant flood watches at this time.

Temperatures will remain above average through the weekend with
highs in the 90s and lows in well into the 60s. Chambers

Monday through Friday...

Ridging looks to remain in place through the extended period,
with some degree of monsoonal moisture hanging around, although
most of it will be suppressed to the south. This will result in
temperatures in the upper 80s to middle 90s most days, with a
slight chance of thunderstorms, mainly over the southern
mountains. Humidity values from the upper teens to 20s are
forecast most days, with no significant wind at this time. STP

&&

.AVIATION...

In general, VFR conditions will prevail through the period.
Expect isolated to scattered shower and thunderstorm to continue
into the overnight for some areas, mainly form KRPX to KMLS and
north. Localized heavy rain and gusty winds are possible. Reimer

&&

.PRELIMINARY POINT TEMP/POPS...

    Sat     Sun     Mon     Tue     Wed     Thu     Fri
-----------------------------------------------------------
BIL 067/096 067/091 064/091 063/093 063/092 062/091 063/090
    23/T    33/T    21/U    00/U    00/U    01/U    12/W
LVM 058/094 057/091 054/091 054/093 055/092 054/091 056/090
    34/T    33/T    11/U    01/U    01/U    12/W    22/T
HDN 064/098 064/092 061/093 059/094 058/093 058/093 058/091
    22/T    33/T    21/U    10/U    00/U    00/U    11/U
MLS 069/098 069/095 064/092 063/093 063/093 062/090 061/091
    12/T    32/T    21/U    10/U    00/U    00/U    01/U
4BQ 068/095 067/091 064/089 062/090 062/090 059/089 060/088
    12/T    43/T    32/T    11/U    11/U    01/U    11/U
BHK 065/095 066/093 063/089 060/089 060/089 059/087 059/088
    02/T    42/T    22/T    11/U    11/U    00/U    11/U
SHR 063/095 062/087 059/089 057/090 057/091 056/090 057/088
    24/T    45/T    43/T    11/U    11/U    11/U    12/T

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...None.
WY...None.

&&

$$
weather.gov/billings



Area Forecast Discussion

National Weather Service Grand Forks ND

 1000 PM CDT Fri Aug 12 2022

.UPDATE...
Issued at 956 PM CDT Fri Aug 12 2022

cloud cover remains the issue in terms of updates tonight.
Clearing area is slowly progressing south thru the northern Red
Red River valley and far NW MN. Cloud bases have risen in most
areas, exception being Bemidji area where IFR clouds remain, and
looks like IFR lower clouds are trying to push back west. So
overall idea of a mostly cloudy, but some clearing pockets remain
ok for messaging overnight. Some fog potential as well, but where
remains uncertain. Earlier it was indicating more central ND.

UPDATE Issued at 652 PM CDT Fri Aug 12 2022

Tonight forecast challenges will be clouds and fog development.
HRRR and CONSHORT indicate substantial fog development in central
ND into DVL basin, if area clears of clouds. Rest of the area
seeing clouds, some lower IFR/MVFR Devils Lake to Bemidji, with
some clearing far northern RRV to Warroad. This mess of sky cover
will be a problem tonight with low confidence on how cloud cover
turns out overnight. Dew pts are high in the mid 60s and winds
light so lots of questions about how much clearing will occur. Did
add fog to the forecast using vsbys forecast from CONSHORT and
will need to extend cloud cover area longer.

&&

.SHORT TERM...(This afternoon through Saturday night)
Issued at 333 PM CDT Fri Aug 12 2022

Minimal sensible weather impacts are anticipated through Saturday
night.

The stationary front is lingering near our southern CWA and north of
this low stratus is lingering. This did act to supress high
temperatures and beside aviation impacts it would mainly influence
radiational cooling/overnight lows due to insulation if it lingers.
This cloud layer hasn`t been handled well, but there should be
a trend with drier air arriving as surface ridging builds southeast.

Saturday-Saturday night: Most of Saturday should remain dry and mild
though clouds will again play a role in potential highs (70s vs
lower 80s). By Saturday night a weak shortwave and associated upper
jet streak may bring showers and weaker thunderstorms back into the
region from the northwest with most activity shown by CAMs to
develop near a surface trough in proximity of the Devils Lake Basin.
There isn`t a lot of movement eastward so where it develops, so we
eastern extent of this activity Saturday night is more uncertain.
Instability is limited so besides light rain (current consensus keeps
amounts 0.25" or less).

.LONG TERM...(Sunday through Friday)
Issued at 333 PM CDT Fri Aug 12 2022

Saturday through Tuesday: We remain on the back-half of the 500mb
ridge setup over the Central Plains as the low pressure system
regenerates over the Great Lakes. Saturday remains in North to
Northeast flow over eastern North Dakota and northwestern Minnesota.
Sunday transitions into a Southerly flow that persists through
Tuesday. High temperatures are going to remain fairly consistent in
the mid 80`s for this period. The greatest chance (45%) for rain is
going to be Sunday afternoon over the Devils Lake basin. This is due
to a mid-level shortwave riding the ridge over the northern plains.
Accumulation up to half an inch of precipitation is expected to
occur with this event.

Tuesday through Thursday:  Tuesday, another mid-level shortwave
moves itself over Ontario. Temperatures will drop slightly into the
mid 70`s on Tuesday. This temperature trend will remain until
Thursday as the shortwave helps form an area of low pressure in the
Northeastern United States. Wednesday into Thursday the winds
gradually shift from a Southerly flow into a Northerly flow. There`s
a slight chance of precipitation during this transition but POPs
remain under 30% Wednesday into Thursday.

&&

.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 652 PM CDT Fri Aug 12 2022

In comparision to the last several days, a much more tricky
aviation forecast. Tonight clouds and fog development hold the
key. Light winds in central ND and if area can clear then fog
formation is most likely there into DVL basin. Low clouds may hang
on much of the night Grand Forks to Bemidji and may spread south.
So for the overnight low confidence in how cloud bases and vsbys
will be thru 12z Sat. Would expect any morning clouds/fog to burn
off and scatter out daytime Saturday.


&&

.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.
$$

UPDATE...Riddle
SHORT TERM...DJR
LONG TERM...MM/Perroux
AVIATION...Riddle



Area Forecast Discussion

National Weather Service Greenville-Spartanburg SC

 1012 PM EDT Fri Aug 12 2022

.SYNOPSIS...
Canadian high pressure will bring cooler and drier air to the region
through the weekend. Gradually increasing moisture is expected next
week. Other than a brief warm-up early next week, temperatures are
and expected to remain cooler than normal for much of the week.

&&

.NEAR TERM /THROUGH SATURDAY/...
As of 1000 PM EDT Friday: There is a small line of tstms look to be
weakening as they track southwestward across Newberry County. They
might skirt parts of Laurens and Greenwood counties, but otherwise,
just a few stray showers are expected for the rest of the evening
and overnight. Plenty of mid clouds or high-based stratocu are
expanding along the Blue Ridge escarpment and Piedmont thanks to
easterly flow. But cooler/drier is filtering in from the north,
and so we should see slightly below normal min temps, despite the
clouds. Fog is unlikely except maybe in the normally more foggy
locations. Lows should end up about 5 degrees below normal.

Even the low level moisture moves out on Saturday and cooler and
drier high pressure finally builds more fully into the area. That
said, there may be enough moisture and weak instability for
isolated showers over the Smokies. Highs will be about 5 degrees
below normal with dew points dropping into the 50s across much of
the area leading to a refreshingly low humidity day.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
As of 235 PM EDT Friday: the short-term fcst picks up at 00z on
Sunday with extensive upper ridging still dominating the western
2/3 of the CONUS while fairly deep/broad upper trofing remains
over the mid-Atlantic states. Over the next couple of days, the
trof axis is expected to lift northeast of New England, yet upper
trofing will remain largely in place across the region thru the
end of the period late Monday. At the sfc, the center of broad
high pressure will be translating eastward and over the Atlantic
Coast as the period begins. By late Sunday, another cold front
will approach our fcst area from the NW and bring an increase in
moisture with it. The frontal bndy is not expected to actually
move thru our CWA until late Monday as the period is ending.
As for the sensible fcst, both PoPs and QPF have been increased
late Sunday thru the end of the period late Monday. However, QPF
is still not expected to be excessive and should not cause any
significant hydro issues. Temps should remain just below normal
both Sunday and Monday.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
As of 225 PM EDT Friday: the extended fcst picks up at 00z
on Tuesday with broad upper trofing still in place over the
Eastern CONUS and extensive ridging to the west. Over the next
24 to 48 hrs, the upper trof is expected to morph into a large,
closed upper low and then expand further westward. By the end
of the period late next week, the trof is expected to cover
roughly the eastern half of the CONUS. At the sfc, a weak cold
front will be moving east of our CWA as the period begins. In
the front`s wake, weak high pressure tries to spread back into
the area from the north, however the latest long-range guidance
has it making less southward progress into our area. At the same
time, the synoptic pattern is looking more chaotic/uncertain
with the operational models trying to develop multiple sfc lows
over the Southeast and then move them eastward and off the SE
Coast. Overall, the pattern is trending more active with the
above-mentioned high not exerting as much influence over our
area with solid-chance PoPs each day thru day 7. Temps are also
trending cooler thru most of the period, with highs expected to
start out about a category below normal on Tues, and remain 1
to 2 categories below normal thru day 7.

&&

.AVIATION /02Z SATURDAY THROUGH WEDNESDAY/...
At KCLT and elsewhere: Isolated showers (and possibly a tstm or two)
will linger across mainly the Upstate and NE GA this evening. The
HRRR continues to show showers continuing in these areas overnight,
as easterly flow lifts some moisture. However, the coverage looks
to isolated to warrant any shower mention in the TAFs. Overall, the
clouds are expected to be VFR, but some MVFR or lower cigs will be
possible in the mountains. Will mention some MVFR cigs at KAVL for
early Saturday morning. Drier air works into the area Saturday,
with just high-based cu expected at all TAF sites. Winds will
be NE thru the period at the Piedmont sites. At KAVL, winds will
favor a N direction until around 14z Saturday, then toggle to S/SE.

Outlook: Moisture slowly returns Sunday into early next week. Expect
diurnal convective chances to slowly increase as well. Fog and
low stratus may develop each morning in the mtn valleys.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...None.
SC...None.

&&

$$
SYNOPSIS...DEO
NEAR TERM...ARK/RWH
SHORT TERM...JPT
LONG TERM...JPT
AVIATION...ARK



...Updated Aviation Forecast Discussion...



 .DISCUSSION...
Issued at 255 PM CDT Fri Aug 12 2022

Key Messages:

 - Hot Saturday, warm to hot Sunday, a little cooler for next week.

 - Rain chances Sunday night into Tuesday.

Quiet across the region this afternoon as mid to upper level
ridging remained firmly in control. Decent southerly flow
associated with surface low pressure over the Dakotas and plenty
of sunshine helped to keep us rather warm, with temperatures as of
3 PM in the 90s for most of the area. Also of note at the surface
was a cold front stretching southwestward across SD that will
edge into northeast NE by this evening. Many CAMs suggest
potential for some showers and perhaps an isolated storm or 2
along the boundary as it moves through into Saturday morning.
Still a few questions on how far south any associated precip makes
it, with the HRRR being the most aggressive and indicating at
least some potential as far south as I- 80. However, anything that
develops looks to remain quite spotty and not amount to much.

Ridging stays in place Saturday and Sunday keeping us rather
quiet, but warm to hot. Despite northerly flow behind the front on
Saturday, guidance still suggests widespread 90s with a few spots
perhaps making a run at 100. In addition, there will be a touch
more humidity, as dewpoints get into the mid to upper 60s for
many, which will lead to heat index values topping 100 for many.
Sunday should be a touch cooler with persistent easterly to
northeasterly surface flow, though still expecting highs in the
mid 80s to mid 90s, warmest in southeast NE.

The eastern periphery of the ridge starts to break down by Sunday
evening as various bits of shortwave energy round the ridge and
slide through the forecast area. This will bring persistent rain
chances to the area Sunday night into Tuesday. Instability looks
to be lacking, so wouldn`t expect much in the way of thunderstorms
dumping heavy rainfall, but even a persistent light rain would
likely be welcome for most. While questions remain on exact
placement of the "heaviest" rainfall, it`s looking like a fairly
good bet a majority of the forecast area sees at least some
precip. Interestingly, the recently wet-biased GEFS guidance is
much drier than EPS guidance, with the 12.12Z GEFS showing a
10-30% chance for 0.5" across the area through Tuesday and the
12.12Z EPS showing a 50- 80% chance. For what it`s worth, current
forecast is for 0.25" to 0.75" for many, with some spots getting
over 1". Again, still quite a bit of spread in guidance, but
potential is there for some widespread rain for a change.

In addition to the rain chances, we`ll see some relief from the
heat, with temperatures through next week progged to top out in
the 80s each day. Areas that receive more rain on Monday/Tuesday
could also stay in the 70s those days. May see some additional
spotty rain chances through the remainder of the week as more bits
of shortwave energy slide through, but spread in guidance remains
quite large to narrow it down to any one favored timeframe.

&&

.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 544 PM CDT Fri Aug 12 2022

LLWS threat will increase at all terminals after midnight ahead of
cold front/wind shift. Otherwise, VFR conditions expected to
prevail.

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...None.
IA...None.
&&

$$

DISCUSSION...CA
AVIATION...DEE



Area Forecast Discussion

National Weather Service San Diego CA

 900 PM PDT Fri Aug 12 2022

.SYNOPSIS...
Heat and humidity will continue into the weekend, while increasing
monsoonal moisture fuels more shower and thunderstorm development,
mainly over the mountains and deserts. Moisture levels will decrease
slightly early next week with less thunderstorm coverage expected
then. No major changes to our warm and humid, monsoon pattern is
likely through next week.

&&

.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...

Moisture, pumped high into the atmosphere from an active monsoon
day, remained over SoCal this evening, noticeably punctuating our
sunset. There was still some active thunderstorms at 9 PM PDT near
and just north of Twentynine Palms. This will need to be watched if
it starts to expand westward. Our 00Z Miramar sounding continued to
moisten throughout the column, recording 1.42 inch. A shallow dry
layer remained below 5K FT. The sfc pressure gradients were weak,
and wind reports mostly light. It was quite warm inland across the
I.E. and the deserts where temperatures climbed above the century
mark, along with noticeable humidity. A Heat Advisory remains in
effect for the I.E. tomorrow.

Strong thunderstorms were concentrated along the east slope of the
San Diego Mts, and locally into the deserts late this afternoon.
Biggest Radar estimated storm totals were over the San Diego County
deserts, ranging from 1.5 to locally 3 inches. Flash flooding likely
occurred in some of these remote desert areas near the Fish Creek
Wash.

A weak easterly wave has arrived across NW MX and SoCal and likely
contributed to the strong thunderstorm development. More are
marching slowly westward across western AZ this evening and will
only contribute to the available moisture across the area tomorrow.
Saturday should be an active thunderstorm day if our WRF and HRRR
models are correct, and with PW values near two inches, local flash
flooding will be a concern.

High pressure over the West will be shifting around over the next
week or so, but remain far enough north to make us eligible for
bouts of monsoonal moisture through at least next week. A look at
the ensemble clusters of the two main global models show enough
drying by some of the clusters, to expect a decrease in the
afternoon shwr/t-storm chances, but little confidence it will end.
So low POPS remain in the forecast each afternoon through next week,
especially over the mountains. It will remain seasonally warm and
humid now that sea surface temperatures are in the upper 60s and 70s
over a good chunk of the CA Bight.

&&

.AVIATION...
130310Z...Coast/Valleys...SCT-BKN clouds at/above 10,000-20,000 feet
MSL with unrestricted vis will prevail today and tonight. Slight
chance of intermittent SCT-BKN cigs tonight 600-1000 ft MSL with
varying visibility near the coast 13-16Z Saturday morning.

Mountains/Deserts...SCT-BKN clouds at/above 10,000 feet MSL with
unrestricted vis will generally prevail through tonight. Slight chc
for ISO-SCT TSRA between 05-09z Sat as outflow from storms over
eastern Riverside/San Bernardino Counties enters the area. Bases
would be around 8,000-10,000 feet MSL and tops to 35,000 feet MSL
with strong up/downdrafts, gusty winds, and downpours with any
storms.

&&

.MARINE...
No hazardous marine weather is expected through Wednesday.

&&

.BEACHES...
High tides to around 7 feet again this evening may lead to minor
tidal overflow of beaches and exposed parking lots around the times
of the evening high tides. Surf will remain low, so no significant
damage is expected.

&&

.SKYWARN...
Skywarn activation may be needed on Saturday.

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Heat Advisory until 8 PM PDT Saturday for San Bernardino and
     Riverside County Valleys-The Inland Empire.

PZ...None.

&&

$$

PUBLIC...10
AVIATION/MARINE/BEACHES...Adams



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Area Forecast Discussion

National Weather Service Las Vegas NV

 235 PM PDT Fri Aug 12 2022

.SYNOPSIS...Moist monsoonal flow will remain in place through
next week leading to the potential for thunderstorms with heavy rain
over the eastern Mojave Desert and southern Great Basin. Further
west across the Sierra and Western Mojave Desert, generally dry
weather expected over the weekend with increasing storm chances next
week.
&&

.SHORT TERM...through Sunday.

Thunderstorms got going a little early today. There was a
circulation over Lincoln and northern Clark Counties and a also one
lifting up from southwest Arizona in addition to the surface heating
and the moist and unstable air mass that remains in place over
southern Nevada, northwest Arizona and far southeast California.
Boundary interaction will come into play with additional storm
development through the late afternoon and early evening. The latest
HRRR indicates the potential for thunderstorms converging over the
Las Vegas area this afternoon then propagating southward this
evening. Storms should dissipate late this evening and overnight
then conditions Saturday look quite similar to today, though any
storm induced circulations are a wildcard. The Flash Flood Watch was
extended through Saturday evening for zones where it is currently in
effect. We should see similar thunderstorm development with
scattered to numerous slow-moving storms with the potential heavy
rain. There is not much change in expectation with storm development
through Sunday, so plan on more of the through the weekend.

.LONG TERM...Monday through Friday.

As we head into next week, the monsoon shows little sign of slowing
down with rich moisture locked in place across the Mojave Desert and
southern Great Basin. Meanwhile, high pressure builds into the
northern Great Basin which could shift the steering flow to a more
north or northeasterly direction for a few days, a favorable pattern
for thunderstorm complexes moving into the lower deserts. Aside from
the daily storm chances, temperatures will remain at or below normal
through the period, with the greatest departures from normal across
the eastern Mojave Desert where deeper monsoonal moisture will be
hanging around.
&&

.AVIATION...For Harry Reid...Scattered thunderstorms are forecast
for the area once again this afternoon.  The best chances of seeing
direct impacts on the field are between 22Z and 02Z, with primary
impacts being gusty outflow winds, brief heavy rainfall, and
lightning.  Outside of thunderstorm activity, light southerly winds
and skies FEW-SCT AOA 10kft are expected.  Little change in the
overall pattern is expected over the weekend keeping the chance of
afternoon and evening storms in place through at least Sunday.

For the rest of southern Nevada, northwest Arizona and southeast
California...Scattered thunderstorms are expected at all TAF sites
today with the exception of KBIH. The best chance of seeing storms
will be mainly after 22Z and any storms will be capable of producing
gusty winds, brief heavy rain and lightning.  Outside of
thunderstorm activity expect light winds favoring typical diurnal
variations and FEW-SCT skies AOA 10kft. Little change in the overall
pattern is expected over the weekend maintaining the threat of
afternoon and evening storms through at least Sunday.
&&

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

$$

SHORT TERM...Adair
LONG TERM...Outler
AVIATION...Planz

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