Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/24/20

Area Forecast Discussion

National Weather Service La Crosse WI

 745 PM CDT Sun Aug 23 2020

.UPDATE...
Issued at 745 PM CDT Sun Aug 23 2020

Evaluating the latest incoming guidance, in combination with
todays high temperatures, decided to move Monday`s highs up a few
degrees south of I-94. Felt there was enough confidence with a
plume of warmer air heading in in the low-levels /1.5-3C warmer
at 925mb/ south of the I-94 frontal boundary in the afternoon,
today`s warmer-than-forecast highs, and what looks like a capped
and clean afternoon.

It isnt perfect, and a few items are working against an
overachieve: watching the Dakotas convection to shift east and
probably not make it to the area, but bring in some morning
clouds. The shortwave trough that the convection is currently
associated with will shift through in the morning in MN/WI. Also,
the thicker smoke will arrive overnight and this might intercept
some radiation.

Evaluated Monday evening severe weather and it is definitely on
track. Has some signals like June 2 of this year with a front
moving in from the north, while very warm and capped south of the
front (June 2 was the hottest day of summer thus far). Lapse rates
aloft are not explosive like June 2 Monday evening, but in the
7.5-8C/km range which is favorable and normalized CAPE is around
0.30 (big hail!). Large hail parameter suggests 2-3" hail possible
in the I-90 to I-94 corridor per RAP - seems reasonable. Drier
soundings would also support some higher-end wind gusts. The wind
shear is a bit better on the front too (versus June 2) with some
looping to the hodograph, but low- level shear is lacking so any
tornadic activity should be limited. An enhanced risk area from
SPC would not be surprising.

Current thinking is initiation will happen near MSP, east along
I-94(ish) in the later afternoon and storms will shift east-
southeastward into WI. HRRR/HRRRX/RAP solutions keep the buggers
north of I-94 with a stronger cap in place vs NAMNest 18Z run
which convects the front near MSP and drops storms southeast.
Definitely an afternoon and evening to be weather aware!

&&

.SHORT TERM...(This evening through Monday)
Issued at 225 PM CDT Sun Aug 23 2020

Steepening lapse rates due to diurnal heating combined with weak
moisture transport have allowed a few showers/storms to pop up
across north-central WI. These should continue to move southeast
over the next few hours, diminishing with the loss of daytime
heating and increasing ridging aloft. The main hazards are lightning
and perhaps some gusty winds and small hail given fairly steep low-
level lapse rates near 7 C/km and marginal mid-level lapse rates
around 6 C/km.

For tonight, mid-level ridging should provide fairly quiet
conditions, with light winds and lows in the 60s. There could be
some patchy fog in the Mississippi River tributaries, but increasing
wind above the surface as the night wears on should preclude much
fog development in the mainstem. There might also be some patchy fog
across north-central Wisconsin given recent wetter conditions and
decent radiational cooling.

A small 500 mb perturbation then looks to approach from the west
early Monday morning, likely associated with overnight convection in
Minnesota. There are some placement differences with this feature,
but wouldn`t be totally surprised to see some showers/storms hold
together with the forcing, especially across north-central Wisconsin
where there is weaker ridging and less low-level dry air to contend
with. Given the time of day, lightning and small hail would seem to
be the main threats.

Heat and storm chances are then the focus for the rest of the day. A
subtle boundary layed out across the area will shift northward as a
warm front, with increasing WAA/frontogenesis by late afternoon,
strongest to the west/just into the northwest portions of the area.
Given increasingly warm and moist air, NAM/GFS suggest MLCAPE values
well above 3000 J/kg during the afternoon, likely due to dewpoints
in the mid 70s in both models. This may be a bit overdone, as 50th
percentile dewpoints are in the low 70s, but there should still be a
decent amount of instability that builds. There is fairly good
agreement that stout capping will be in place, however, which may be
tough for any potential convection to overcome until moisture
transport ramps up in the evening. Capping should be weakest across
north-central Wisconsin where air aloft isn`t so warm, so that area
would seem to have the best shot at an isolated shower/storm during
the daytime. Thus, it`s currently looking like much of the day
should end up dry, humid, and hot (emphasis on that last word). 925
mb temperatures approaching +25C to +30C should translate to
widespread afternoon temperatures in the 80s and 90s, with dewpoints
in the 70s pushing heat indices near heat advisory criteria in the
mid to upper 90s. A few of the warmer valley locations could hit
heat indices around 100, but at this time this doesn`t look to be
widespread enough to warrant heat headlines.

.LONG TERM...(Monday night through Sunday)
Issued at 225 PM CDT Sun Aug 23 2020

The 23.12Z models have continued the trend started with previous
runs of suggesting a MCS to impact portions of the area Monday
night. A short wave trough riding up and over the large upper
level ridge looks to move across the Upper Midwest Monday night
and produce some weak to moderate pv advection in the 500-300 mb
layer. A warm front currently extending across central Minnesota
into northern Wisconsin is not expected to move much and will
provide a focus for convective development as the wave moves over
the area. With good warm air advection south of the front, the
baroclinic zone is expected to tighten up resulting in a weak to
moderate band of frontogenesis in the 1000-500 mb layer along and
north of the warm front. The warm air advection should result in
strong isentropic upglide over the warm front with the 23.12Z NAM
showing 6 to 12+ ubar/s on the 310K isentropic surface. With this
forcing, have increased the rain chances to around 60 percent and
these may need to go higher if model signals continue with later
data sets.

There will also be a risk for severe storms with this activity. A
band of 1500-2500 J/kg of ML CAPE is expected to form in the
vicinity of the front. Deep layer shear looks to be on the order
of 40 to 45 knots along and north of the front, with most of this
residing in the 0-3 km layer. As the low level jet/moisture
transport increases Monday evening, the shear in the 0-1 km layer
will ramp up to maybe as much as 30 knots along and south of the
front. This would suggest a threat for damaging winds and large
hail and maybe an isolated tornado near the boundary where the low
level and deep layer shear can overlap. Locally heavy rains will
be possible as well with precipitable water amounts expected to be
around 2 inches north of the front and warm cloud depths
increasing to around 3.5 km during the evening.

The next best chance for more rain looks to come Thursday night
into Friday morning. Similar to Monday night, a short wave trough
looks to run along the top of the upper level ridge and across the
Upper Midwest. However, agreement between the 23.12Z ECMWF and GFS
remains poor on the strength of this wave with the GFS being much
stronger than the ECMWF. For now, the rain chances have generally
been bumped up into the 40 to 50 percent chance range with this
system until the models start to show some better agreement. This
system will have to be watched for another severe threat as well.
Very similar set up to Monday night with a decent CAPE pool
developing along the stationary front with good deep layer shear
along and north of it and low level shear along and south of the
front. Precipitable water axis along the front looks to be between
1.5 and 2 inches as well for another locally heavy rain threat.

&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday)
Issued at 745 PM CDT Sun Aug 23 2020

VFR conditions are expected through the period. However, Monday
later afternoon and evening, storms should develop to the north of
the airfields. Thunderstorms could affect both airfields in the
evening, although KLSE has slightly higher probabilities.
&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&

$$

UPDATE...Baumgardt
SHORT TERM...Lee
LONG TERM...04
AVIATION...Baumgardt




Area Forecast Discussion

National Weather Service Bismarck ND

 923 PM CDT Sun Aug 23 2020

.MESOSCALE DISCUSSION...
Issued at 915 PM CDT Sun Aug 23 2020

Thunderstorms were increasing and building back toward the west
along ND Highway 36 running from northwest of Jamestown to north
of Bismarck, an east to west oriented line. Another line of
storms extended also east to west from northern Foster County to
near Fessenden in Wells County. These storms are north of the
surface boundary that pushed through late this afternoon.

These storms were in an area of 2-3,000 J/Kg MUCAPE, 700-500MB
lapse rates of about 7.5 C and deep layer moisture flux
convergence oriented east to west in the area where the storms
formed.

Earlier CAMS, specifically the HRRR did show this line
developing so it is now followed as the CAM of choice. This would
bring weak convection just to the west of Bismarck and Mandan so a
low pop was introduced for the next several hours.

&&

.UPDATE...
Issued at 550 PM CDT Sun Aug 23 2020

Updated pops and expanded severe risk over the southeast part of
the forecast area.

Two outflow boundaries were pushing south from the convection near
Jamestown. Between the tow, near the North and South Dakota border
in Dickey County a thunderstorm formed and underwent explosive
growth. A new Storm was now forming on the north side of the
original Storm.

&&

.SHORT TERM...(This evening through Monday)
Issued at 220 PM CDT Sun Aug 23 2020

Thunderstorms forming and propagating along and behind a cold
frontal boundary in moving through central and southwest North
Dakota. Frontogenetic forcing continues to extend across into the
cold air side of the baroclinic zone late this afternoon.

We expect storms to primarily be elevated along and north of the
cold front. Strong warm advection across the frontal boundary
this evening will feed the convection, and if it aligns into an
east west convective line there will be some training
possibilities, which suggests a potential for heavy rain this
evening in the central James river Valley. We have messaged this
in the Weather Story and Hazardous Weather outlook for tonight.

Tonights lows will be in the lower 50s north and the lower 60s
south.

On Monday dry weather is expected. We used the smoke information
from the HRRR model which keeps considerable elevated smoke
across the region tonight and Monday. Highs will be in the 80s to
lower 90s.

.LONG TERM...(Monday night through Sunday)
Issued at 220 PM CDT Sun Aug 23 2020

The initial H500 pattern with a ridge across the western US will
gradually flatten as shortwave energy moves through the northern
plains this coming week.

This will tend to bing an active pattern with chances for
thunderstorms Tuesday through Thursday, and again Saturday and
Sunday.

There is the potential for strong to severe thunderstorms Tuesday
and Tuesday night with better CAPE and Shear with a cold frontal
passage.

Temperatures will be above normal through Tuesday, then normal or
slightly below normal Thursday and Friday. Although warmer
temperatures may be seen next weekend, some extended analogues
are starting to hint at much cooler weather in the 6 to 10 day
period.

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 915 PM CDT Sun Aug 23 2020

KDIK-KXWA-KMOT will be VFR. Scattered to numerous thunderstorms
are forecast from just north of KBIS through KJMS until about
24/08Z. Then MVFR ceilings possible at KJMS between 08Z and 15Z.

&&

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

$$

MESOSCALE...JPM
UPDATE...JPM
SHORT TERM...WAA
LONG TERM...WAA
AVIATION...JPM




Area Forecast Discussion

National Weather Service Columbia SC

 752 PM EDT Sun Aug 23 2020

.SYNOPSIS...
An upper trough axis to our west will continue to bring deep
moist southwesterly flow over the region through tonight. An
upper ridge over the western Atlantic will build into the area
early next week. Tropical Storms Laura and Marco are forecast to
move through the Gulf of Mexico early next week.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
Light showers streaming over mainly the southeastern forecast area
with PWATs around 2 inches and both the offshore ridge and trough to
the west promoting deep SW flow with an influx of moisture along the
Gulf Coast courtesy of Hurricane Marco approaching the central Gulf
of Mexico. Expect a break in shower activity after sunset. Later
tonight, a channel of positive vorticity advection, mainly in
the NW forecast area, will keep chances of showers overnight
with any precipitation generally light. With continued moisture
streaming into the mid and upper levels overnight as well,
expect clouds to continue to overspread the forecast area.
Temperatures tonight drop to around 70.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY/...
The Midlands and CSRA will be between a Bermuda High off the
East Coast and TC Marco moving into the northern Gulf Coast.
Deep tropical moisture will continue to stream into the region
with southwest flow as PW values remain in the 2.0 to 2.3 inch
range early this week. This will result in scattered to numerous
showers and thunderstorms Monday and Tuesday. WPC places
portions of The Midlands and CSRA in a Marginal Risk of
excessive rainfall Monday through Tuesday.

Convective activity noticeably decreases due to subsidence north of
TC Laura on Wednesday. High temperatures will be below normal Monday
and Tuesday due to extensive cloud cover and rainfall with near
normal temperatures expected on Wednesday.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
High pressure aloft builds over The Midlands and CSRA Thursday
through Friday in between an upper trough over the Northeast and TC
Laura moving into the Western Gulf Coast. Increasing H5 heights will
lead to above normal temperatures with highs in the lower to mid 90s
and lows in the lower to mid 70s. We should also experience a late
summer diurnal scattered shower and thunderstorm pattern.

A strong upper trough moving into the Ohio River Valley absorbs the
remnants of TC Laura Friday Night through Saturday. The GFS phases
the remnants with the upper trough while the EC does not. At this
time the TC Laura remnants appear to stay north of the region with a
continued chance of showers and thunderstorms through next weekend.

&&

.AVIATION /00Z MONDAY THROUGH FRIDAY/...
VFR conditions through the evening then restrictions toward
morning with stratus expected to develop.

Deep moisture remains in place across the area with ridge
offshore and south flow moisture transport in to the area. Still
some light rain in the area but likely not to impact terminals
this evening. Models suggest higher low-level moisture and a
greater potential for more widespread IFR/MVFR stratus toward
morning. This is supported by latest HRRR and Lamp. MVFR
strato-cumulus may continue through late morning or early
afternoon before scattering out by 18z. Moist and weakly to
moderately unstable air mass Monday. Guidance indicating
scattered to possibly numerous showers and a few thunderstorms
may develop near the coast and spread inland during the
afternoon. These showers may impact terminals with restrictions
at times after 18z.

EXTENDED AVIATION OUTLOOK...Scattered mainly diurnal shower and
thunderstorm activity through the period. Patchy late
night/early morning fog/stratus possible.

&&

.CAE WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.

&&

$$



Area Forecast Discussion

National Weather Service Des Moines IA

 629 PM CDT Sun Aug 23 2020


...Updated for the 00z Aviation Discussion...

.DISCUSSION.../Tonight through Sunday/
Issued at 253 PM CDT Sun Aug 23 2020

Continued focus on the heat throughout the work week with just
some patchy fog possible across the north-northeast early Monday
morning. The other concern or uncertainty is the impacts of the
wildfire smoke streaming in from the west on Monday and Tuesday.

Weak flow and enough low level moisture around to have a mention
of patchy fog across the northeast by Monday morning. Similar
trend to this morning with the fog developing.

Large thermal ridge continues to strengthen over the western two-
thirds of the country and keeping Iowa hot through Thursday before
the ridge begins to break down by the end of the week. 850mb
temperatures by Monday warm to around +25C and there is some
mixing that develops tomorrow afternoon. Confident with the mid
to upper 90s for highs Monday but with the last several runs of
the HRRR continually bringing in the wildfire smoke, uncertainty
with how much of an impact his plays on temperatures as well as
air quality. Can already see hints of smoke over the Dakotas and
western Nebraska via GOESEast satellite trends and it doesn`t
appear to be impacting current temperatures attm. At any rate,
hot, dry, and a little breezy in the afternoons Monday through
Wednesday.

Friday through the weekend...a much needed cool down is
anticipated during this period but low confidence with any
significant precipitation maker with the lingering tropical
systems hoarding the main moisture source.

&&

.AVIATION.../For the 00Z TAFS through 00Z Monday evening/
Issued at 627 PM CDT Sun Aug 23 2020

Some potential for fog over northern TAF sites late tonight mainly
in the KMCW/KALO vicinities. Otherwise light winds tonight
becoming breezy at times on Monday with VFR conditions forecast.

&&

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

$$

DISCUSSION...Podrazik
AVIATION...Donavon



AREA FORECAST DISCUSSION

National Weather Service Eureka CA

 253 PM PDT Sun Aug 23 2020

.SYNOPSIS...Warm to locally hot temperatures will occur across
interior valleys during the next week. Otherwise, scattered,
mostly dry thunderstorms will be possible across the region
tonight through Monday evening. Afternoon and evening
thunderstorms will remain possible over the far eastern interior
through mid-week.

&&

.DISCUSSION...The primary concern through Monday continues to be
potential thunderstorm development...particularly late this evening
through Monday evening. A decayed tropical system and a mid-level
disturbance off the southern California coast will spread moisture
north over the region this evening and overnight.

The surface to 850 mb layer will be dry, but moistening is forecast
to occur near 700 mb, which, when combined with steep mid to upper
level lapse rates, will aid in MUCAPE values from 100 to 500 J/kg.
Model guidance shows mid-level ascent and an associated moist plume
spreading north across Lake and Mendocino counties during the
late evening hours, then Humboldt and Trinity counties after midnight,
followed by Del Norte county Monday morning. Isolated to scattered
thunderstorm development is forecast to be embedded within this plume
of moisture. Due to the warm and dry low- level airmass and
progressive northerly storm motion, most lightning strikes will be on
dry ground and pose a threat for new fire starts. Additionally, due
to the dry low- levels, gusty and erratic winds beneath any storms
will be possible. Reference the Red Flag Warning and fire weather
discussion below for more information.

Another concern during the next few days will be high temperatures
in southern Mendocino and Lake counties where highs Monday are
expected to reach near 100 degrees in valley locations. However, the
smoke across many inland areas will act to mitigate high temperatures
a bit. Coverage and impacts still do not appear to warrant a heat
advisory.

The last concern today through Tuesday will be impacts from wildfire
smoke. Mid level flow will be rather persistent out of the south-
southeast. This should push smoke from fires east and south of the
area into most interior locations. Smoke may be dense at times which
will impact visibility. Health concerns from the smoke are dealt with
by the air quality management districts.

Beyond Tuesday, the weather will become more tranquil with
temperatures running a few degrees above normal. Isolated
thunderstorms will remain possible across the Trinity horn for both
Tuesday and Wednesday afternoons. /JMG&SEC

&&

.AVIATION...The stratus proved to be a worthy adversary today in
regards to predicting its movement. By midday, the cloud layer began
to pull back over the ocean in Humboldt county with IFR conditions
at KACV, while coastal Del Norte and KCEC clung on to LIFR Cigs and
visibility. For the remainder of the afternoon, the stratus would
surge back in before the terminals could improve better than IFR
during brief receding movement. Another round of low clouds and LIFR
conditions is expected to return once again to coastal terminals
this evening. Farther to the south, KUKI experienced some passing
smoke with reduction in visibility. More periodic passing smoke can
expected through this evening. HRRR Experimental Smoke guidance did
fairly well at depicting this, and shows another round possible
beginning early this morning. Elevated thunderstorms should form in
the vicinity of KUKI this evening, and then progress north and
northeast across the forecast area.

&&

.MARINE...Breezy northerly winds will continue across the outer
waters overnight, strongest in the Northern Outer waters through
Monday. These winds will generally continue through the forecast
period, generating widespread steep seas of 8 to 9 feet. Advisory
level northerly winds and seas are expected to continue for the
outer waters for the foreseeable future. Northerly winds and steep
seas will begin ticking up beginning overnight Monday.

&&

.FIRE WEATHER...Isolated to scattered thunderstorms are expected to
spread north across the area late this evening though Monday evening.
Very dry low levels and moderately fast northerly storm motions will
support dry storms. Activity is expected to reach Lake and Mendocino
counties late this evening, then Humboldt and Trinity counties after
midnight, followed by Del Norte county Monday morning.

Have continued the existing Red Flag Warning which runs from late
this evening through Monday evening. Storms are possible across the
Trinity horn for Tuesday and Wednesday afternoons. After Wednesday,
storm chances will decrease significantly. /JMG&SEC

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...Red Flag Warning from 11 PM this evening to 11 PM Monday
      for CAZ201>204-211-212-264-276-277-283.

NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory until 3 PM Tuesday for PZZ470-475.

$$

Visit us at https://www.weather.gov/eureka

Follow us on Facebook and Twitter at:
https://www.facebook.com/NWSEureka
https://www.twitter.com/NWSEureka

For forecast zone information
see the forecast zone map online:
https://www.weather.gov/images/eka/zonemap.png



Area Forecast Discussion

National Weather Service Glasgow MT

 840 PM MDT Sun Aug 23 2020

.DISCUSSION...

EVENING UPDATE:
Going forecast looks fine. Changes were minimal this evening. GAH

AFTERNOON DISCUSSION:
Zonal flow across the region will maintain warm and dry conditions
throughout the area. High temperatures on Monday will be well
into the 90s as a brief ridge emerges ahead of trough to the west.
Winds stay below critical fire weather criteria, but with fuels
still dry and relative humidity staying fairly low, the area is
still not free of fire weather concerns. HRRR Smoke model
indicates haze from wildfire smoke will clear from NW to SE
throughout the rest of the day but will return tomorrow. The Hill
Fire by Fort Peck Lake appears to not be as hot on satellite and
spot requests and DSS for this fire has decreased significantly.

Moisture from the remnants of a tropical system in the eastern
Pacific will ride along southwesterly flow aloft, providing much
needed relief to the western US, but could also provide the
amount of moisture necessary for a few thunderstorms to develop by
the time it reaches Montana through midweek. The trough from the
west arrives late Monday night and a series of weak shortwaves
will mean a few opportunities for moisture this week, but also the
chance of dry lightning as the boundary layer remains relatively
dry. Monday night low temperatures will be warmer and depending on
the time of arrival for the front, could be anywhere from upper
60s to upper 70s. Storm Prediction Center has categorically
general thunderstorms for Monday, but marginal chances for severe
on Tuesday. Given the temperatures and the limited moisture, the
main threat appears to be wind driven.

After midweek, temperatures will gradually decrease toward more
seasonable temperatures by the end of the week. Lack of model
consensus disrupts accuracy in timing and placement of future
troughs, however, there is some confidence in the continuation of
weak disturbances before the potential of much larger Alaskan low
pressure system that may arrive sometime next weekend and last
through the weekend.

Roxy


&&

.AVIATION...
FLIGHT CATEGORY: VFR

DISCUSSION: Mainly clear skies and dry conditions will prevail
over the area with the exception of some haze caused by smoke
coming in from the south due to the fires in California. The smoke
is not expected to greatly reduce visibilities at any of the
terminals.

WINDS: Light and variable overnight into Monday morning, becoming
southeasterly at 10 to 15 knots during the afternoon.

RMB


&&

.GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.


&&

$$

weather.gov/glasgow




Area Forecast Discussion...UPDATED

National Weather Service North Platte NE

 915 PM CDT Sun Aug 23 2020

.UPDATE...
Issued at 915 PM CDT Sun Aug 23 2020

A stray thunderstorm may affect nrn Nebraska overnight. These
storms are ongoing across SD this evening. An increase in the low
level jet to about 30kts as shown by the RAP model may support a
southward turn in the storm motion causing activity to brush
northern Nebraska.

A forecast update is in place for isolated thunderstorms along
and north of highway 20 tonight.

&&

.SHORT TERM...(This evening through Monday night)
Issued at 237 PM CDT Sun Aug 23 2020

A slight chance exists for convective thunderstorms early this
evening, but confidence is low for widespread storm activity. A
surface trough axis, extending through western Nebraska, is the
primary focus for uplift. GFS soundings show 850-500 mb lapse rates
of about 9 C/km, which indicates the possibility for strong
thunderstorms. Aside from the trough and lapse rates, there are few
other factors that appear promising for thunderstorm development
over the forecast area. Farther north, a cold front moves moves
through the Dakotas, but this will be too far out of reach to
influence weather in Nebraska. Forecast soundings from the NAM show
less than 1000 J/kg of ML CAPE and deep layer shear between 20 and
30 knots. After the trough passes, dew points in the Sandhills and
southwest Nebraska will drop to the 50s, with 40s present in the far
western edge of the CWA. The eastern Panhandle and northern
Sandhills have the greatest chances for precipitation in the early
evening. Any storms that do develop will be isolated and are not
expected to be severe.

The main weather concern for Monday is high temperatures. A ridge
currently centered over the Four Corners will build north today and
tomorrow. H850 mb temperatures Monday will reach 34C in the western
forecast area, translating to temperatures nearing 100F at the
surface. Normal highs for late August in the region are in the mid
80s. Meanwhile, smoke from wildfires in the western U.S. will
continue to move into Nebraska. While it will not necessarily reduce
temperature, it will create hazy conditions throughout the region.

.LONG TERM...(Tuesday through Sunday)
Issued at 237 PM CDT Sun Aug 23 2020

Hot temperatures will continue Tuesday and Wednesday as the upper
level ridge remains settled over the western U.S.  Heat index values
will be in the upper 90s on Tuesday and the mid 90s on Wednesday. On
Thursday, a cold front will move south across the Dakotas into
Nebraska, bringing cooler temperatures to the region. Temperatures
will be in the 80s through the weekend. Chances for precipitation
will also return next weekend as southerly winds bring moisture
northward to the Great Plains from the Gulf of Mexico.

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 613 PM CDT Sun Aug 23 2020

Isolated thunderstorms may affect nrn Nebraska until 05z this
evening. The area of concern is along and north of highway 20
west of Valentine.

Otherwise, a strong upper level ridge of high pressure will
remain anchored across the Four Corners region of the western
U.S.. VFR should prevail across western and north central Nebraska
tonight and Monday.


&&

.LBF WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

UPDATE...CDC
SHORT TERM...Meltzer
LONG TERM...Meltzer
AVIATION...CDC




Area Forecast Discussion

National Weather Service Newport/Morehead City NC

 1006 PM EDT Sun Aug 23 2020

.SYNOPSIS...
High pressure will slowly strengthen and build in from the east
through early next week, before shifting a bit further south by
mid week.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
As of 10 PM Sunday...Veil of mostly mid with some level clouds
continue to stream northeast from the Gulf of Mexico into the
Carolinas late this evening. Scattered showers and a couple of
thunderstorms from earlier in the afternoon dissipated with loss
of heating before dark. Another warm muggy night upcoming with
lows mainly in the low/mid 70s. The HRRR model tries to depict
some showers approaching the southern coast toward morning, but
most of the other high-resolution is dry. Will remove PoPs as
think any activity would likely be after 12z in the morning. No
other changes to the current forecast.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/...
As of 330 PM Sunday...Not a huge different from today with a
fair amount of mid and high level clouds still expect with highs
mainly in the 80s. Highest threat for showers and storms will be
roughly in the same area as today, along the southwest part of
our area.

&&

.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
As of 300 AM Sun...High pressure expected to be the main
influence in the long term, with hot conditions expected by mid
week. Mostly dry weather expected through the beginning of next
weekend, when low pressure or a cold front move into the region.

Monday and Tuesday...Strong high pressure will be centered off
the SE coast Monday and Tuesday, with subsidence and dry air
keeping the area mostly dry. However, mid to upper level
moisture will continue to stream into the area from the Tropical
Cyclones in the Gulf of Mexico, which will lead to some overcast
skies (filtered sunshine at best), and chances for some
occasional sprinkles. Despite low level heights building,
aforementioned cloud cover will limit highs to the upper 80s to
around 90. Tuesday could get a little warmer depending on how
quickly the high level moisture clears out of the area, and if
unfiltered sunshine returns before the afternoon is over.

Wednesday through Saturday...An approaching upper level trough
over Great Lake/Northeast will squeeze high pressure southwestward
on Wednesday, and then high pressure rebuilds over the SE
Atlantic Thursday through Saturday. Low level heights will
continue to increase during this period and hot temperatures are
expected with afternoon highs in the low to mid 90s. With high
humidity, heat index values of 100-105 are possible as well.
Despite hot temps mostly dry conditions are expected Wednesday
and Thursday, with increasing (scattered) chances expected
Friday and Saturday as a upper level trough moves across the
Great Lakes and a cold front approaches from the NW. There is
some chance that the remnants of Laura could push across the
area, but there is still high uncertainty with the evolution of
that.

&&

.AVIATION /02Z MONDAY THROUGH FRIDAY/...
Short Term /through 00Z Tuesday/...
As of 705 PM Sunday...With any very light precipitation ending
soon, conditions will be VFR through the overnight hours and
through the end of the TAF cycle at 18Z Monday. Overnight
model guidance suggests some MVFR cigs possible briefly prior to
sunrise. Given the abundance of mid and high clouds, will
continue to leave out of the forecast.

Winds near calm tonight, becoming southwest 5 to 10 kts again
Monday.

Long Term /Monday night through Friday/...
As of 315 AM Sun...Mostly VFR conditions expected through the
long term as high pressure builds in. Some isolated bouts of
early morning fog/stratus will be possible though.

&&

.MARINE...
Short Term /through Tonight/...
As of 1005 PM Sunday...Winds remain a bit gustier over the
Pamlico Sound and some of the central waters, but winds are
generally SW 5-15 knots with seas 2-3 feet at late evening. A
few 4-footers may be possible over the outer waters overnight.
Similar winds Monday with southwest winds 10 to 15 kts, but
some gusts toward 20 kts possible late afternoon/evening. As we
begin to see the fringe swell from Laura, seas will build to 3
to 5 feet late in the day into the evening.

Long Term /Monday through Thursday/...
As of 315 AM Sun...Decent boating conditions expected this
week, with winds remaining light. Only wildcard will be how much
swell builds into the area from distant Tropical Storm (and
possibly Hurricane) Laura. Right now, seas are expected to peak
at 3-5 feet Monday through Wednesday, with a brief period of 6
feet possible during the peak on Tuesday. Winds will be mostly
out of the SW at 5-15 kts, though could briefly increase to
15-20 kts Tuesday night/Wednesday morning, before becoming SW
10-15 the rest of Wednesday and Thursday.

&&

.MHX WATCHES/WARNINGS/ADVISORIES...
NC...Beach Hazards Statement from 8 AM EDT Monday through Monday
     evening for NCZ196-204-205.
MARINE...None.

&&

$$

SYNOPSIS...MHX
NEAR TERM...CTC
SHORT TERM...
LONG TERM...SGK
AVIATION...EH/CTC/SGK
MARINE...EH/CTC/SGK



Area Forecast Discussion

National Weather Service Marquette MI

 627 PM EDT Sun Aug 23 2020

.SHORT TERM...(This evening through Monday)
Issued at 409 PM EDT SUN AUG 23 2020

WV imagery and RAP analysis indicated a mid/upper level ridge from
the Southern Rockies through the Central Plains toward the Upper
Mississippi Valley resulting in wnw flow into the northern Great
Lakes. Farther north, a mid level low was sliding east into
northern Manitoba. At the surface, a weak gradient prevailed with
weak frontal boundaries northeast of Lake Superior and through
north central WI. A weak shrtwv along with MLCAPE values into the
1000- 1500 J/Kg range supported sct shra/tsra through portions of
western/central Upper Michigan. With relatively weak 0-6km shear
near 20 knots and unfavorable mid level lapse rates, the TS have
remained relatively shallow/weak. However, with PWAT values around
1.5 inches, brief heavy rain will be possible along with some
small hail.

Tonight, expect that the sct shra/tsra slowly moving through central
Upper Michigan will gradually weaken this evening with the loss of
daytime heating/instability. Otherwise, with abundant low level
moisture remaining, dewpoints in the mid 60s, areas of fog are
likely to develop again overnight. Min temps should also only fall
off into the low to mid 60s.

Monday, models suggest that as a shortwave trough and surface low
slides through northern Ontario it will drag a weak cold front into
Upper Michigan. There is less agreement with the potential for
another shrtwv moving into the area from the northern Plains.
Nevertheless, expect another round of sct diurnal shra/tsra. With
slightly stronger 0-6km shear to 30 knots and MLCAPE values
again to near 1500 J/Kg, some stronger or locally svr tsra may be
possible.

.LONG TERM...(Monday night through Sunday)
Issued at 325 PM EDT SUN AUG 23 2020

12z guidance continues to be in good agreement on the dominate upper
level features determining flow across the CONUS. Ridging over the
western CONUS and the western Atlantic will continue this week and
subtle changes in these features will impact how tropical systems in
the Gulf of Mexico will impact the southern US and perhaps our
region. As these ridges vary in extent and magnitude, the Upper
Great Lakes will find itself sandwiched between the western ridge
and a deepening trough over eastern North America by mid-week. The
pattern looks to flatten out some Thursday, before ridging and
troughing amplifies over central and eastern Canada, respectfully,
in response to an upper level low digging into the Canadian Rockies
for the weekend. Overall, this will allow the muggy conditions to
linger, as well as bring a few systems into the region this week. By
the weekend, a cooler airmass will filter in.

Monday night, early showers and thunderstorms associated with the
transiting cold front should be trending downward at around the time
the log term period begins. As the front moves through, expect the
activity to shift south and any severe threat to come to an end.
Until the showers/thunderstorms exit the region, expect localized
heavy downpours to still be possible. The front will stall over
central WI overnight, which will keep at least low-end chance PoPs
in the forecast for the far south into Tuesday morning. Lows should
bottom out in the 50s away from the lakeshores, but remain in the
low 60s by the water.

Tuesday, high pressure will sink southeast over Ontario, landing
just northeast of Lake Superior by Tuesday night. This will allow
for brief height rises and a break in the humidity. Expect highs to
climb into the 70s with maybe stray low 80s in the interior west and
interior south.

Next round of showers and thunderstorms comes Tuesday
evening into Wednesday, as a surface warm front lifts through the
region, aided by a few upper level impulses. Accompanied by strong
isentropic lift, expecting a good chance of widespread rain across
the region to begin overnight Tuesday and continue into Wednesday.
As the front lifts through and WAA increases early on, low level cap
in the model soundings looks to prevent much in the way of surface-
based convection, but elevated values of 500-1000 j/kg could still
enable the development of some thunderstorms, especially if the deep
shear values of 40-50kts are realized. As the front lifts through
Wednesday, theta-e advection and instability look to increase in the
afternoon, allowing for some redevelopment along the boundary in the
afternoon into the evening, especially in the east. PWATS among the
guidance is around 1.5-1.75", with the GFS and EC showing
potentially widespread 0.5-1" 24hr QPF and the forecast reflects
this general thinking.

Thursday, high pressure building southeast over Ontario into Lake
Superior behind the outgoing system looks to keep the region dry.
However this will be short lived, as upper level troughing looks to
begin reestablishing itself over the region. The details are still a
little uncertain as the guidance varies, but expecting another
shortwave within this flow to move into the region. At the surface,
low pressure moving out of the Plains could have some dynamic
reenforcement aloft as it moves into the Great Lakes region. Further
south, the remains of Laura could be over the middle-Mississippi
Valley. Guidance suggesting this position also suggests possible
phasing between these systems. Given the uncertain nature and model
spread of these features, confidence is low on the evolution of this
Thursday night into Friday event. While confidence is low on the
details of this event, confidence is high on a cooler Saturday, as
the upper level trough allows 850mb temps to fall at or below 10C.
&&

.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 626 PM EDT SUN AUG 23 2020

Fog will return overnight and take conditions back down to IFR/MVFR
at all sites. Conditions improve again Mon morning.
&&

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 409 PM EDT SUN AUG 23 2020

Winds across Lake Superior will remain mostly under 20kt Mon thru
midweek. A humid air mass over the area combined with some showers
moving across the lake has supported fog development across much of
Lake Superior early this morning. Will continue the Marine Dense Fog
Advisory across much of the lake through 13z.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&

$$

SHORT TERM...JLB
LONG TERM...JP
AVIATION...07
MARINE...JLB