Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 07/17/21
Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
925 PM CDT Fri Jul 16 2021
.UPDATE...
Issued at 923 PM CDT Fri Jul 16 2021
Area of showers and thunderstorms beginning to move through Jones
county at this hour, and may hold together long enough to make it
to Lyman county. Have increased the POPs for the next few hours
for that area. Otherwise, no changes made to the forecast at this
time.
&&
.SHORT TERM...(This Evening through Saturday Night)
Issued at 228 PM CDT Fri Jul 16 2021
Convection chances/coverage are the main challenges for the short
term. For this evening very evident s/w moving into central South
Dakota will remain the main focus for convection into the evening
hours. A developing LLJ may help maintain activity into the evening
hours post sunset. The main threat for severe is probably located
mainly west river, where a little stronger winds aloft are progged
overtop higher instability. Latest HRRR maintains development of an
MCS forming over southwest SD, and then moving southeast overnight.
For the most part Saturday will be dry, but as moisture/instability
increase again over the central/western part of the state, more
storms are expected. Once again shear appears modest, but MLCAPE
progs suggest pretty unstable atmosphere toward evening. CAMS are a
tad more aggressive in bringing some convection east of the Missouri
river during the mid to late evening hours Saturday. As mid-level
heights build over the region this weekend, temperatures will be on
the uptick.
.LONG TERM...(Sunday through Friday)
Issued at 228 PM CDT Fri Jul 16 2021
The tale of the extended period is very warm temperatures where
highs will be in the 90s for most of the region most days. Sunday is
the main exception as showers/thunderstorms may be ongoing from a
passing shortwave. Once this system clears out by Sunday night,
high pressure builds into the region. Combined with southerly flow
at the surface, temperatures will shoot right back into the 90s for
Monday through the remainder of the workweek for most areas.
Conditions will be very unpleasant as daytime dewpoints will be in
the 60s for most of the area through Monday and remain in the 60s
for most areas east river for the remainder of the period. Breezy
conditions are possible at times during the middle of next week.
Combined with slightly lower RH values in the middle of the week,
this will lead to elevated fire weather conditions for much of the
forecast area.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday Evening)
Issued at 624 PM CDT Fri Jul 16 2021
Terminals KABR,KATY,KPIR,KMBG
For the most part, VFR conditions will prevail across the area
tonight and Saturday. There is a small chance for some
thunderstorm activity to affect the far southwestern part of the
area later this evening, but this activity should remain south of
KPIR. By mid to late afternoon Saturday, may see some scattered
thunderstorm development over central South Dakota, but will not
mention in the KMBG or KPIR TAFs at this time due to the
uncertainty.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
&&
$$
UPDATE...Parkin
SHORT TERM...TDK
LONG TERM...Telken
AVIATION...Parkin
Area Forecast Discussion
National Weather Service Bismarck ND
944 PM CDT Fri Jul 16 2021
.UPDATE...
Issued at 936 PM CDT Fri Jul 16 2021
The main show this evening has been a storm that formed near
Beulah which has dropped south-southwest and is now passing
between Richardton and Hebron. This storm has produced hen egg
size hail, but has pulsed up and down in strength a few times. The
area it has been moving through is a more or less north to south
corridor of elevated instability, but it is getting into an area
of a little less deep layer shear. With that said, it still
remains severe though with the loss of shear intensity may be
easing.
For the remainder of tonight, still concerned with some
thunderstorms developing with the low level jet increasing.
Enough instability will be around for some storms to get strong,
with maybe a severe storm or two.
UPDATE Issued at 638 PM CDT Fri Jul 16 2021
Some storm shave developed over the southwest, though recently a
new storm has developed near Hazen. The southwestern storms have
remained tame as lower instability is noted over that area, but as
you go east, instability increases until you reach near the
Highway 83 corridor. High-res models have been increasing
coverage some as we go through the evening and overnight over this
aforementioned area, but with how crummy they did earlier in the
day will have to wait and see a bit to see how this pans out. With
that said, have expanded the low storm chances further east as we
get into the overnight hours.
&&
.SHORT TERM...(This evening through Saturday)
Issued at 345 PM CDT Fri Jul 16 2021
Chances for thunderstorms increase this evening and then again
overnight tonight for portions of western and central North
Dakota. A few thunderstorms may become severe with quarter size
hail and 60 mph wind gusts possible. Another round of
thunderstorms is possible again late Saturday afternoon and
evening.
A building upper level ridge over a broad surface low, located
over eastern Montana, was evident on water vapor imagery this
afternoon with a series of weak impulses moving through the axis.
At the surface, dew points have climbed into the mid 60s across
central North Dakota, with a sharp drop-off in dew points near the
Montana border. Coinciding with the eastward progression of the
ridge, mid level lapse rates are steeping from west to east, with
7.5 C/km to near 8.5 C/km over the west. Moderate to strong
instability is developing this afternoon with the overlap of
richer boundary layer moisture and lapse rates aloft.
Despite rising mid level heights with the building ridge, good
agreement exists in the elimination of convective inhibition near
the surface low over western North Dakota as the boundary layer
mixes out this afternoon. Overall ascent is modest but
convergence and differential heating should be adequate for some
convective initiation. Effective bulk shear is on the weaker side
for organized convection, but should be enough to combine with
1500-2500 J/kg of MLCAPE to encourage a few potentially severe
thunderstorms. Quarter size hail and localized 60 mph wind gusts
will be possible with stronger thunderstorms.
Then overnight the focus for ascent shifts towards elevated based
nocturnal initiation, on the nose of warm air advection in the
850-700mb layer. Though the various convection allowing model
cores are scattered in placement, most are producing some sort of
overnight convection. MUCAPE may remain high enough with cloud
layer shear of around 30 kts to allow some storms to produce hail
nearing severe criteria.
After lingering convection Saturday morning, the persistent
pattern may produce another round of thunderstorms near the
western surface low in the late afternoon. A discrepancy in
solutions remains between CAMs, though the main outlier continues
to be the HRRR which keeps tomorrow dry compared to other
available models. Forecast soundings across the board look
uncapped for the most part, with the HRRR producing a deeper mixed
boundary layer (a known tendency) which may be preventing
initiation within the model. Thus the reasonable outcome is more
likely thunderstorm initiation tomorrow evening, though with some
question about coverage considering the mid-level height rises.
Again the CAPE/shear parameter space should provide an environment
for isolated severe thunderstorms if conditions align.
Temperatures Saturday become hot in the afternoon with highs in
the 90s across the west and central with a few points of the far
west possibly reaching 100.
.LONG TERM...(Saturday night through Friday)
Issued at 345 PM CDT Fri Jul 16 2021
The persistence of above normal temperatures highlights the long
term forecast period.
Into next week, the upper level pattern is highlighted by the
amplified ridge over the Rockies, with climatologically high mid-
level heights over the Northern Plains. This pattern will maintain
above normal temperatures with a few low predictability chances
for convection as impulses run through the ridge axis. Each day
will feature widespread highs in the 90s, with hottest
temperatures in the west through mid-week. Several days of highs
crossing the 100 F threshold are possible for some areas as well,
for the west during the first portion of the period and then
possibly in the central later in the week. Though forecast max
heat indices remain below advisory criteria due to relatively
lower humidity, the prolonged period of hot temperatures is still
notable.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 638 PM CDT Fri Jul 16 2021
Isolated thunderstorms are possible over the area overnight. Have
mentioned VCTS in the KDIK and KBIS TAFs where confidence is a bit
higher. Over other locations, will withhold mentioning for now.
Some storms may linger into the morning hours over the north.
Thunderstorm chances return from west to east again Saturday
afternoon. Did not mention this in current TAF package given there
is still a fair amount of uncertainty on timing and coverage.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...JJS
SHORT TERM...AE
LONG TERM...AE
AVIATION...JJS
Area Forecast Discussion
National Weather Service Dodge City KS
608 PM CDT Fri Jul 16 2021
...updated aviation section...
.SHORT TERM...(This afternoon through Saturday)
Issued at 111 PM CDT Fri Jul 16 2021
A mostly quiet weather night is expected across the FA. The main exception
to this is across Hamilton and Kearny counties, perhaps up to Scott
county and points southward. There will be a chance of mid evening
storms in this area. Storms are expected to develop along the higher
terrain of eastern Colorado and then slowly propagate to the south
or perhaps south-southeast. Bulk shear is slightly stronger today around
30-35 kt. The main threats with the storms will be damaging convective
outflows of 60-70 mph and heavy rainfall. Perhaps some hail too with
the slightly stronger shear that is in place. Have the highest pops
during the evening across Hamilton and Kearny counties to account for
this anticipated storm evolution. It should be a mid to late evening
event, so prior to 6 or 7 pm, much of the FA should remain storm free.
Since anticipated storm motion is to the S or SSE, much of the rest
of the area should be in the clear. There was a secondary concern of
storms forming across the Nebraska panhandle and then drifting towards
central Kansas, however, confidence on this actually occurring is low.
Otherwise, the rest of the forecast is ho-hum weather. Overnight lows
look to be seasonal with values mainly in the 60s.
For Saturday, a mid level ridge starts to amplify across the Central
Rockies. The net result is even weaker flow at the mid and upper levels
of the atmosphere. PWATs will continue to remain over an inch, so there
will be moisture and instability in place for storms. Confidence on
exact placement of storms in the weak flow regime is low. As a result,
have broad brush pops across the FA. Activity should remain isolated
to widely scattered, so there is a higher chance you`ll remain dry
than seeing a storm over you.
Otherwise, near normal highs are expected with values in the 90s.
.LONG TERM...(Saturday night through Thursday)
Issued at 111 PM CDT Fri Jul 16 2021
The center of the mid level ridge on Sunday starts to head north during
the day. This may help us with a slightly higher areal coverage of
storms. The slight chance to chance pops looks reasonable for now.
Temperatures will continue to remain near or perhaps a few degrees
below normal to close out the weekend. It will still be warm nonetheless.
For Monday, the mean center of the mid level ridge is still expected
to be northwest of the FA. Again, a similar weather pattern is expected
to continue with warm temperatures and isolated storms.
As the ridge heads north, low level northeastern flow may develop on
the eastern side of the ridge. This may help to keep temperatures more
in the 80s versus the 90s for Monday through Wednesday. The main caveat
to this is the intense July Sun, which could offset this cooler low
level flow. Regardless if its in the 80s or the 90s, the end result
is still the same with the Summer weather continuing for the rest of
the extended period.
There still is a trend in the long range models to shift the ridge closer
to our area by the end of the business week. This could result in dry
conditions and seasonally hot highs dominating.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 606 PM CDT Fri Jul 16 2021
The challenge for the overnight is where the opportunity exists for
convection. The forecast area is downstream from ongoing surface
based convection over eastern Colorado. The atmosphere will decouple
with time this evening however steep mid level lapse rates and
instability should support several model solutions which allow
clusters of thunderstorms to continue southeast across the heart of
west central and southwest Kansas. This shouldn`t offer much of a
severe threat but rather locally moderate to heavy rains and
frequent lightning. Hopefully The 00 model runs will offer more
clarity for the convection late this evening and overnight as the
HRRR at this time is at odds on location with everything else.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 68 93 68 92 / 30 30 20 30
GCK 65 92 66 90 / 30 20 20 30
EHA 67 94 67 92 / 20 20 20 20
LBL 68 93 67 91 / 20 20 20 30
HYS 66 90 67 88 / 30 20 20 40
P28 70 93 70 91 / 10 20 20 40
&&
.DDC WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...Sugden
LONG TERM...Sugden
AVIATION...Russell
AREA FORECAST DISCUSSION
National Weather Service Hastings NE
629 PM CDT Fri Jul 16 2021
...AVIATION UPDATE...
.DISCUSSION...(This evening through Friday)
Issued at 320 PM CDT Fri Jul 16 2021
Clouds continue to slowly diminish this afternoon. Temperatures have
been a little slow to warm, but as there is more sunshine, they
should rebound.
Thunderstorms are expected to develop later this afternoon on the
high plains, then move to the southeast during the evening hours.
Models all have a little different location and timing for the
thunderstorms, as well as the path that they will take. All of the
models have the convection diminishing as it moves to the east, but
just how far to the east does it get and what it looks like when it
does get to the forecast area are a little questionable. Have kept
some low PoPs mainly in the northwest and north through the night. A
few of these storms could be strong, but should weaken as they get
into the forecast area. There is a small chance there could be a few
showers and thunderstorms in the far north/northeast during the
morning hours on Saturday. Otherwise, clouds should diminish during
the day on Saturday and temperatures warm into the 80s.
The next upper level wave moves into the area Saturday night. This
convection will also start on the high plains and move into the area
during the evening and overnight, but this will be a little further
to the east and models all put some convection across the forecast
area Saturday night through Monday. Not expecting there to be
precipitation all of the time through the entire weekend, but there
could be some on and off thunderstorms. These have the potential to
be strong to severe at times, but timing them is still a little bit
of a challenge. Saturday night into Sunday night have the best
chance for there to be rain and most locations should see some
rainfall from this system. Temperatures through Monday will be
mainly in the 80s.
Monday night through Friday appears to be a dry period. An upper
level ridge to the west builds into the area and an upper level low
develops in the southern plains. Expect dry conditions as the ridge
moves over and the temperatures should be on a steady increase from
the lower to mid 80s on Tuesday to the lower to mid 90s by Friday.
&&
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Sunday)
Issued at 625 PM CDT Fri Jul 16 2021
Main concern this period is whether or not the terminals will see
some shower/thunderstorm activity overnight. Right now confidence
is fairly low because based on model data, a lot will depend on
what forms (or doesn`t form) over the NE Panhandle in the next few
hours. If the HRRR is to be believed then both terminals could
see some activity after about 08Z. Should things stay calm in the
Panhandle, then most of the area will likely remain dry.
Winds are expected to remain rather light and variable through the
end of the period, and VFR conditions are expected to remain.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
DISCUSSION...JCB
AVIATION...Shawkey
Area Forecast Discussion
National Weather Service Wichita KS
1001 PM CDT Fri Jul 16 2021
.UPDATE...
Issued at 1000 PM CDT Fri Jul 16 2021
Isolated diurnally driven storms have waned across south central KS,
or have shifted southwest into OK. But as the late evening
continues, latest RAP model shows 850-700h moisture transport looks
to gradually increase across south central KS. This will lead to
renewed convection developing across south central KS, late this
evening and overnight. Already seeing signs of this development,
with some isolated showers/storms developing just to the southeast
of KICT. Think this renewed convection is just the start, with
widely scattered showers and storms expected to keep developing
overnight. The moisture transport isn`t as strong as last nights, so
do not think the storms will be as widespread as last night.
Ketcham
&&
.SHORT TERM...(This evening through Monday night)
Issued at 349 PM CDT Fri Jul 16 2021
Main forecast challenge: Thunderstorm chances over the next few
days.
As of late this afternoon, a weak surface front extended from
near the Oklahoma Panhandle across east-central Kansas to central
Missouri. Will maintain a 20-30% chance of thunderstorms in
south-central/southeast Kansas Tonight where modest 925-850 mb
convergence is progged with higher precipitable water of 1.5-1.75
inches. Even though any storms that manage to develop are expected
to be isolated to widely separated in coverage, they would be
high-efficiency rainfall producers. Other convection clusters are
expected to continue developing over the central High Plains
through this evening, with a south-southeastward propagation
overnight. Will maintain a 15-20% probability for thunderstorms
in central KS for late tonight into Saturday morning, although
better chances for storms should be over the High Plains.
Otherwise not much change expected for Saturday-Saturday night with
the front lingering over southern Kansas, with humid conditions and
slight chances for a thunderstorm.
The short-medium range guidance indicates that upper level high
pressure will develop and strengthen over the Rockies Sunday into
Monday, with a mean longwave upper trough in the eastern CONUS. A
shortwave is progged to slide south-southeastward along the
eastern periphery of the Rockies High, across the Central Plains
Sunday into Monday. This shortwave will encounter anomalously high
moisture across the Central Plains and should lead to higher
chances of a thunderstorm complex or two moving through our
forecast area. At this juncture, Sunday night appears to have the
highest storm chances. This wave should also push the front
southward out of Kansas by Monday.
.LONG TERM...(Tuesday through Friday)
Issued at 349 PM CDT Fri Jul 16 2021
Medium range models are in good agreement indicating that the
Rockies upper-level high will tend to persist. After some modest
relief from the heat and humdity early in the week, temperatures
will slowly modify back to around seasonal climatology by
Thursday/Friday. Will maintain dry weather during this period.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 821 PM CDT Fri Jul 16 2021
VFR conditions are expected for the first 6 to 10 hours. Lots of
level moisture continues to linger across the forecast area, with
this tropical airmass expected to linger into Sat as well. So as the
early morning on Sat progresses, expect some MVFR cigs to develop
across much of the forecast from 10-14z/Sat. Surface moisture
remains high as well, which may lead to some MVFR vsbys developing
across portions of central KS for Sat morning as well.
Ketcham
&&
.PRELIMINARY POINT TEMPS/POPS...
Wichita-KICT 71 89 70 88 / 20 20 20 40
Hutchinson 69 90 68 89 / 20 20 20 40
Newton 69 88 69 87 / 20 20 20 40
ElDorado 69 88 69 87 / 20 20 20 40
Winfield-KWLD 70 90 70 89 / 30 20 20 40
Russell 67 90 68 88 / 20 20 40 40
Great Bend 69 89 68 87 / 20 20 30 40
Salina 68 91 68 90 / 10 20 30 40
McPherson 68 89 68 87 / 10 20 20 40
Coffeyville 69 88 70 89 / 30 20 20 30
Chanute 70 87 70 87 / 20 20 20 30
Iola 69 87 69 85 / 10 20 20 30
Parsons-KPPF 70 88 70 88 / 30 20 20 30
&&
.ICT WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...Ketcham
SHORT TERM...JMC
LONG TERM...JMC
AVIATION...Ketcham
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1022 PM CDT Fri Jul 16 2021
.UPDATE...
Issued at 1022 PM CDT Fri Jul 16 2021
Updated for aviation discussion below.
&&
.SHORT TERM...(This evening through Saturday night)
Issued at 210 PM CDT Fri Jul 16 2021
Benign weather is expected this period as we remain under the
influence of high pressure centered over the Great Lakes. Given the
light winds and clear skies expected, to go along with a slight
increase in surface dewpoints, did add a mention for some patchy fog
tonight over south central and southeast MN up into western WI. This
looks to be mainly confined to valleys and near bodies of water.
Given the light south/southeast winds expected this period, expect
smoke from Canadian wildfires to remain elevated and do nothing more
than continue to offer us milky colored skies and colorful sunrises
and sunsets. For highs tomorrow, stuck with something close to the
NBM. It`s a couple of degrees warmer than today, which makes sense as
little in the way of airmass change is expected, which means we`ll
just be slowly warming things up on a daily basis.
.LONG TERM...(Sunday through Friday)
Issued at 210 PM CDT Fri Jul 16 2021
The extended period continues to look like a lot of nothing as far as
active weather concerns, with the biggest thing of note being
steadily increasing temperatures next week. The only chance we have
of seeing any precipitation whatsoever would be with a back door cold
front late Tuesday through Thursday, with the 12Z ECMWF much more
apprehensive about the chance than the GFS/NBM. This front does
already favor central MN and Duluth`s CWA instead of us, and I would
not be surprised if subsequent model runs begin to remove this
chance. We keep our northwest flow aloft, with temperatures reaching
the upper 80s on Sunday, low 90s on Monday and Tuesday, with a chance
for mid 90s in the metro and western MN on Wednesday/Thursday. Hazy
skies will continue to remain a possibility due to upstream
wildfires, however this will continue to remain an upper level
feature and shouldn`t affect things at surface level. This trend of
hot temperatures and lack of precipitation unfortunately looks to
continue until the end of the month, with the large scale pattern not
looking to change.
&&
.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1022 PM CDT Fri Jul 16 2021
Main issue remains potential for fog late tonight. Light winds and
maybe some residual moisture from the rain on Wednesday could lead to
some fog for 2-4 hours, especially in eastern MN and western WI.
Surface high pressure centered over eastern Lake Superior, with its
influence extending almost to western MN, where return south-
southeast flow is taking place.
Also, smoke may eventually become more prevalent at the surface, so
will need to watch for any reduced visibility similar to what
happened last weekend. The HRRR smoke forecast indicates that to be a
distinct possibility, but again, it is uncertain at this time whether
visibility will be reduced.
KMSP...There will probably be some fog in the Minnesota River valley
in the morning, but otherwise, quiet weather is expected. Will have
to watch to see if any of the smoke causes a visibility reduction on
Saturday.
/OUTLOOK FOR KMSP/
Sun...VFR. Wind SE 5-10 kts.
Mon...VFR. Wind SW 5 kts.
Tue...VFR. Wind SW 5 kts.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...None.
WI...None.
&&
$$
UPDATE...TDK
SHORT TERM...MPG
LONG TERM...TDH
AVIATION...TDK
Area Forecast Discussion
National Weather Service Pocatello ID
151 PM MDT Fri Jul 16 2021
.DISCUSSION...Satellite imagery showing afternoon build-ups
beginning across higher elevations of East Idaho early this
afternoon. A few cells already developing into something the radar
can see, and expect development to continue for the next several
hours. Have maintained thunderstorm coverage in line with blend of
the high-res models for the afternoon, with coverage dropping off
after sunset. Dry low levels should be conducive for another round
of strong gust potential. One more shortwave feature rotates
through the Great Basin on Saturday, so East Idaho could see
another round of afternoon/evening thunderstorms, mainly across
southern portions of the region. Smoke has been less of a concern
with good air quality across much of the Snake Plain and areas
south. HRRR Smoke fields hold smoke to the central mountains, due
to both fires there and being within the trajectory of the smoke
from Oregon/California. Have allowed the HRRR smoke fields to
populate that portion of the forecast without broad-brushing
patchy values over the rest of the area. Moving into Sunday and
Monday, center of upper high anchors over southwest Wyoming. South
flow into East Idaho still indicative of a temperature increase.
Interestingly, models are still picking up on a bit of mid-level
moisture flow through the Great Basin for Sunday, and the 12Z NAM
now showing a few thunderstorms Sunday afternoon. Numerical
guidance still pushing 100+ temperatures for a large chunk of the
area, with overnight temperatures trending upwards as well.
Ensemble blends still trending below guidance, so kept the numbers
a little above the blend, but below the higher guidance values.
The additional moisture, and onset of the deeper monsoon moisture
for Monday are a concern for limiting the top end of temperature
potential. Heat Risk still quite elevated, so will keep the
Excessive Heat Watch in place. Speaking of the monsoonal moisture,
ensemble PWAT values spike up sharply in most if not all members
starting Monday. Thunderstorm activity is expected to become more
widespread through the middle of the week, potentially continuing
through the end of the week as there is not much in the way of
features to push the moisture stream away to the east.
Temperatures are expected to moderate somewhat for Tuesday and
beyond. DMH
&&
.AVIATION...
Have vicinity thunder at DIJ, BYI and PIH. Think coverage not as
widespread as yesterday but will still have isolated development.
Only have smoke visibility restrictions at SUN but keep at 6 statue
miles. Other sites seem to have mainly gone to 10 miles or more for
the most part and kept no visibility restrictions any longer. Winds
generally light and 10 knots or less unless near any thunderstorm
outflow.
GK
&&
.FIRE WEATHER...
High Haines index red flag warning is in effect through tonight in
zones 475 and 422. Mud Lick does not look as active today. Did
not extend the warning so will let next shifts decide on Saturday
into the weekend. Expect isolated thunderstorms today with some
possible outflow over 30 mph but should not be as widespread as
yesterday. Hot conditions will intensify over the weekend with the
persistent Haines index of 6 continuing. Next week monsoonal flow
will be the main feature and the threat for thunderstorms will be
more extensive with a better chance for precipitation.
GK
&&
.PIH WATCHES/WARNINGS/ADVISORIES...
Excessive Heat Watch from Sunday afternoon through Monday
evening for IDZ051>059.
Red Flag Warning until 7 AM MDT Saturday for IDZ422-475.
&&
$$
Area Forecast Discussion
National Weather Service Portland OR
207 PM PDT Fri Jul 16 2021
.SYNOPSIS...A broad upper level trough remains over the Pacific
Northwest through tonight. High pressure centered over The Great
Basin will gradually expands north and west this weekend resulting in
a gradual warming trend. Southwest flow aloft prevails the first half
of next week, which will maintain dry conditions and slightly above
normal afternoon temperatures.
&&
.SHORT TERM...Tonight through Monday...IR Water Vapor imagery via GOES
17 shows a broad 550 mb upper level low in the Gulf of Alaska, with
a broad upper level ridge across The Great Basin. These two systems
will be the main synoptic systems which will dictate the weather
through at least Monday. Model families are in good agreement that
the low currently in the Gulf of Alaska will continue moving
southeast along the Canadian coast, at the same time the upper level
ridge across The Great Basin will build towards The Cascades.
However, there are discrepancies within the model family ensembles as
to just how these two systems will interact. The GFS, NAM, Canadian
and NBM models have the upper level ridge becoming stronger, with the
ridge axis pushing across the Cascades. The ECMWF and RAP on the
other hand has the ridge axis staying further east of The Cascades,
which would allow the low from the Gulf of Alaska to dig deeper into
the Pacific NW. What should be noted is that both of these solutions
will likely not result in any precipitation across the CWA. However,
as the low moves closer to the Olympic Peninsula, there is a slight
chance of some drizzle along the coast in the morning.
Given that most model run are showing The Great Basin ridge becoming
the more dominate feature through the start of next week, have chosen
to keep daytime high temperatures in the mid to upper 80s inland and
low to mid 60s along the coast. Also, expect the nighttime marine
surges to become stronger as the low in the Gulf of Alaska slowly
travels south. This will result in cloud cover along the Coast which
will persist along the northern Oregon and southern Washington coast
as well as push inland along the Columbia River Gorge towards the
Portland/Vancouver metro area.
One more thing to note is that the overall upper level flow will be
from the south/southwest, this will result in some haze/smoke from
the Jack Fire located in eastern Douglass County to impact portions
of the Lane and Linn County Cascades for the foreseeable future. At
this time am not expecting a significant wind shift which would cause
smoke/haze from the Southern Oregon and Northern California fires to
impact the Willamette Valley. /42
.LONG TERM...Monday night through Saturday...Little chance in the GFS
and ECMWF deterministic runs and their ensembles through the
upcoming week. The upper low along the Canadian Coast will continue
to battle with the large-scale upper ridge firmly planted from
the Great Basin to the Upper Midwest. Models show that the upper low
will continue to get little closer to the Pac NW Tuesday and
Wednesday, which will likely result in a slight cooling trend during
the middle of the week.
Models finally have the upper low moving into British Columbia
Thursday. As we start getting into the latter part of the week,
models have a period of zonal upper level flow developing Friday.
However, models are showing the potential for a strong low from the
Gulf of Alaska starting to exert influence across the Pacific NW as
early as Sunday. The GFS has this system as a much stronger trough,
while the ECMWF has a compact low over the same area. /42
&&
.AVIATION...Stable westerly flow aloft continues. Weakening front
will push onshore later this afternoon, with another weak front
arriving later tonight. Overall, not much in way of mid or upper
clouds, but expect another surge of lower VFR and MVFR stratus
along the coast this evening, persisting into Sat am. Will see
patchy drizzle or light rain again, mainly north of Tillamook.
Further inland, VFR this tonight, as residual scattered 3500 to
4500 ft clouds dissipate by 00Z. With the continued onshore flow,
and remains of another front arriving later tonight, will see
stratus with CIGS 030 to 040 reforming over the interior later
this evening, mainly north of KSLE. This stratus will break up
and dissipate later Sat am.
For detailed regional Pac NW aviation weather information, go
online to: https://weather.gov/zse
KPDX AND APPROACHES...VFR with scattered clouds into early
evening, then clearing. But, onshore flow continues, so will
expect lower VFR deck reforming after 07Z. This stratus will
persist into Sat am, breaking up after 18Z.
&&
.MARINE...Weak front offshore will push onshore towards early
evening. Another weak front farther offshore will push across the
coastal waters later tonight. But, S to SW winds will stay under
15 kt for the most part, with seas 3 to 5 ft.
High pres will rebuild across the offshore waters on Sat, and
remain anchored in that position through the weekend into early
next week. Meanwhile, thermal trough will hug the far south
Oregon coast. This setup will maintain northerly winds on the
coastal waters, with 10 to 20 kt. Strongest winds will be south
of Cascade Head, and primarily in the afternoons/evenings.
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
PZ...None.
&&
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Area Forecast Discussion
National Weather Service Phoenix AZ
459 PM MST Fri Jul 16 2021
.UPDATE...
Updated Aviation section.
&&
.SYNOPSIS...
Abundant monsoon moisture will continue to bring daily chances for
showers and thunderstorms across south-central and eastern Arizona
with a tendency to favor the higher terrain of eastern Arizona.
Storms will be capable of producing both locally heavy rain and
strong winds. Temperatures overall will remain close to average
through the middle of next week.
&&
.DISCUSSION...
Parts of Phoenix saw a fairly active start to the day this morning
as isolated to scattered showers and thunderstorms developed across
parts of the metro this morning. The majority of this activity was
confined to central and eastern parts of the Valley, though a few
spots in the west Valley did get in on some of the shower activity
as well. Rainfall amounts generally remained below 0.25" inches for
most locations while a few isolated locations saw upwards of 0.50"
to locally close to 1" in parts of the southeast Valley. Officially,
Phoenix Sky Harbor recorded 0.01" of rainfall this morning, bringing
the total for the monsoon season so far up to 0.54". Currently,
temperatures across the metro continue to warm up as current highs
across the west Valley have climbed above 100 degrees and low to
mid 90s across the east Valley (due to this morning`s rainfall).
Meanwhile, visible satellite imagery shows mostly clear skies
over the Phoenix metro this afternoon while strong convection
continues over the high terrain to the east.
The environment remains quite saturated across the region with
16.12Z PHX sounding recording a PWAT value of 1.92" and 1.93" on the
16.12Z TUS sounding, which are near or above record territory values
for these sites on this date. Radar this afternoon shows strong
convection over the high terrain east of Phoenix pushing through
eastern portions of southern Gila County. Storms are slowly
pushing toward the southwest under the influence of weak
northeasterly steering flow. The main threat with these storms as
they progress through Gila County this afternoon will be flash
flooding, especially for burn scar areas. A Flash Flood Watch
remains in effect until 11 PM MST for southern Gila County and
portions of northeastern Maricopa County. Additional threats going
forward through the afternoon across the high terrain will be
strong, gusty winds and perhaps hail. Objective analysis this
afternoon shows DCAPE values around 1,000 J/kg with the highest
values situated to the west over south-central Arizona. HREF
probabilities shows about a 50-60% chance for outflow winds to
exceed 35 mph and less than a 10% chance for gusts to exceed 60
mph.
Forecast uncertainty increases this evening with the westward
progression of the ongoing convection into the lower deserts.
Many of the 12Z HREF members show convection over Gila County
dying off as it gets into the Valley. However, given the
instability in place, with HREF guidance show MUCAPE values in
excess of 1,000 J/kg, and little convective inhibition, the
potential for getting showers and thunderstorms into the Valley
will be possible with strong enough outflows. The HRRR continues
to be one of the more aggressive CAMs with showing convection
getting into the Phoenix area this evening. Strong, gusty winds,
locally heavy rainfall, and lightning will be the primary threats
with any convection that makes it into the metro area this
evening. Additional shower activity can`t be ruled out going into
tomorrow morning as well.
.PREVIOUS DISCUSSION...
Saturday will see a westward expansion of the monsoon moisture,
mainly due to the increasing southeasterly flow from the upper
level high repositioning itself to our northeast and the vort
max/inverted trough continuing to track westward reaching
southeast California Saturday afternoon. Subsidence behind the
inverted trough is likely to limit storm chances across south-
central Arizona initially on Saturday, while also bringing chances
for some isolated storms as far west as southeast California. The
stronger southeasterly flow may be enough for a complex of storms
later in the day to track northwestward through southeast Arizona
and maybe into south-central Arizona Saturday night, as hinted by
the 06Z HRRR.
A favorable southeasterly flow should persist across much of the
region Sunday into Monday resulting in a northward expansion of
monsoon moisture well into the Great Basin. Daily storm chances
will exist across most of Arizona through at least early next
week, favoring the typical high terrain areas each day. There will
likely be at least a day or two where the lower deserts will be
active, especially if the mid level easterly flow increases like
what models continue to show for next Tuesday and Wednesday.
Through next week, there are no signs of the monsoon letting up,
in fact it will likely be more active than the current week has
been.
The temperature forecast is mostly an afterthought at this time,
taking a backseat to our daily storm chances. NBM guidance has not
changed much supporting near normal temperatures across the
western deserts to slightly below normal across south-central
Arizona.
&&
.AVIATION...Updated at 0000Z.
South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
Thunderstorms have been slowly progressing westward across Gila
and Pinal Counties. Given available moisture and associated
instability, it is expected the outflows/gust fronts will be able
to generate new storms progressively westward toward metro
Phoenix. Key question is whether or not that propagation process
will continue across the Valley floor this evening. Model guidance
is something of a mixed bag with some indicating that process
sustaining itself and others indicating storms falling apart away
from the higher terrain. However, a mid afternoon sounding
suggests that outflows will be able to overcome the remaining
convective inhibition - if they are strong enough. There is
relatively high confidence that outflows will overspread the
Valley floor from the northeast and east roughly between 01Z and
04Z. In turn, it is anticipated that at least isolated storm
activity will happen roughly between 02Z and 05Z. Thus, inserted
TEMPO TSRA in the Phoenix area TAFs during that time. Anticipate
ceilings will remain above 6kft AGL but it could be lower
underneath a strong thundershower.
Surface winds are anticipated to favor southeasterly but there may
be a short time of variable directions but with speeds anticipated
to be below 10kts. Then, outflows from the northeast and east are
anticipated with gusts of 25-35kts. But, with subsequent storm
development in the vicinity, there would be a period of highly
variable and strong winds. It is highly dependent upon how robust
that development winds up being which remains uncertain.
Anticipate much more mild conditions by 06Z (if not sooner) with
relatively light winds.
Southeast California/Southwest Arizona including KIPL and KBLH:
Winds will continue to favor south and southeasterly directions
tonight and Saturday. At KIPL, anticipate a period of south-
southwesterly this evening along with some gusts of 15-20kts
before resuming southeasterly. Anticipate little cloudiness though
there could be some cirrus from thunderstorm remnants emanating
far to the east.
&&
.FIRE WEATHER...
Monday through Friday:
Temperatures will generally be near seasonal averages as monsoon
moisture remains in place over the region. Storm activity is
anticipated to spread as far west as southeast California by early
next week. Any storms that form will have good potential to
produce wetting rain. Threats from storms will continue to involve
locally heavy rainfall and flooding while an increase in strong
gusty winds looks possible starting Sunday or Monday. Significant
flooding may be experienced on previously burned areas of Gila
County. Min RH levels are expected to remain in the 20-30% range
most areas (30-50% higher terrain of south-central AZ). Max RH
levels will be 35-60% most places (60-90% higher terrain of south-central
AZ). Apart from thunderstorms, winds will favor familiar diurnal
patterns.
&&
.SPOTTER INFORMATION STATEMENT...
Spotters should follow standard reporting procedures.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Flash Flood Watch until 11 PM MST this evening for AZZ545-547-
552-555>558-560>563.
CA...None.
&&
$$
DISCUSSION...Smith
PREVIOUS DISCUSSION...Kuhlman
AVIATION...AJ
FIRE WEATHER...Smith/AJ/Kuhlman
...Update to aviation forecast discussion...
.DISCUSSION...
Issued at 350 PM CDT Fri Jul 16 2021
Cloud cover has been a little slow to dissipate, but per satellite
it has been scattering more quickly in the last hour or so and
should continue to do so this afternoon. As a result temperatures
are still only around 80 degrees, but with increasing sunshine the
next few hours they should rebound to the mid 80s, a few degrees
warmer on the southwest edge of the CWA. Main challenges for this
forecast package are timing and placing the weak shortwaves and
associated shower/storm chances within the northwest flow rounding
the edge of the upper ridge that remains stuck over the southwest
US. Generally speaking, model guidance appears to have backed off on
precip chances through tomorrow, at least for our area. The best
chances this evening and tonight look to remain in southeast KS
where a weak frontal boundary hangs around, although a few CAMs
bring some storms pretty close to our east central KS areas. Also
won`t completely rule out some fog redeveloping in eastern KS close
to sunrise as forecast soundings keep enough BL moisture with
morning lows close to crossover temps, but this could end up being
mainly stratus for a brief period in the morning. RAP soundings seem
to be more aggressive with fog, so will need to continue monitoring
trends for better consistency.
The next wave coming out of NE tonight into tomorrow appears to keep
the better forcing toward central KS into the morning hours, with
only slight chances for storms through the afternoon. There may be
just enough of a cap for the majority of the area to preclude any
precip, but have maintained small PoPs along the southwest edge of
the area where it looks just a bit weaker. Rain chances improve
somewhat Sunday into Monday with the next perturbation, which looks
to be a bit stronger and more focused over northeast KS. As these
disturbances move through the flow, the ridge will continue to
amplify over the western US and eventually the axis should move east
toward the Plains. This keeps a dry forecast for the rest of next
week beyond Monday. These rising heights will allow for a slight
warm-up into the end of next week, but in the meantime expect temps
to hold fairly steady with highs in the 80s and lows in the 60s.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 630 PM CDT Fri Jul 16 2021
VFR conditions now through at least part of the overnight period.
There appears to be a good enough level of confidence in a few
hour period where at least patchy fog develops and could impact
the terminals through 12Z time frame and through 13-14Z before
scattering out and lifting to a stratus deck that lingers into the
early afternoon.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
DISCUSSION...Picha
AVIATION...Drake
Area Forecast Discussion
National Weather Service Las Vegas NV
820 PM PDT Fri Jul 16 2021
.SYNOPSIS...A brief dry period for most of the area tonight and
Saturday before showers and thunderstorms begin to return on
Sunday and remain a concern through the week. More seasonal
temperatures expected through the period as well.
&&
.UPDATE...Thunderstorm activity is drawing to an close this
evening as the sun sets. At 8 pm, a cluster of storms east of
Phoenix remained quite active. The HRRR brings an outflow
boundary generated from this activity into southern Mohave County
after 9 pm this evening with gusty winds of 20-30 mph. The winds
move north along the Colorado River Valley and across southern and
central Mohave County into Clark County by 1 am where the
boundary is then forecast to dissipate. There is also a small
chance that a thunderstorm develops along the boundary as it
moves into southern Mohave County but confidence is low. Elsewhere
in our area, expect a mostly clear and quiet night. The forecast
with an updated overnight period is out.
&&
.PREVIOUSLY ISSUED DISCUSSION...
.SHORT TERM...Tonight through Sunday
The next few days will see reduced thunderstorm activity for a
large portion of the CWA. Mohave County being the exception. This
will essentially be one day of rest before a surge of moisture
and upper level disturbance from the south brings the threat of
more impactful thunderstorms on Sunday. Activity may begin as
early as Sunday around midnight in southern portions of the CWA
around Lake Havasu, Laughlin and Bullhead City. This moisture
flows north during the day bringing a chance of thunderstorms with
increased rain rates to the entire area by Sunday afternoon.
.LONG TERM...
Much of this afore mentioned moisture will loiter over the area on
Monday through the end of the week. However, Monday through
Wednesday are likely to see more isolated development across the
area due to lack of real forcing and no reinforcing moisture
surges from the south.
This changes some on Thursday through Friday. Most ensemble model
guidance are indicating a healthy moisture surge on these days.
Storm activity will pick up as a result and we are likely to see
an impactful end to the work week.
&&
.FIRE WEATHER...Dry conditions along the eastern Sierra combined
with potential thunderstorm development on Sunday prompted the
issuance of a Fire Weather Watch for Fire Weather Zone 226 Sunday
through Sunday night. Fuel values are historically dry in the
Sierra. There are also a number of wildfires ongoing. With
potential effects on resources the early notification of these
conditions is warranted.
&&
.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any significant weather or impacts according to standard operating
procedures.
&&
$$
UPDATE...Salmen
DISCUSSION/AVIATION...Lericos
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