Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 06/23/21
Area Forecast Discussion
National Weather Service Denver/Boulder CO
941 PM MDT Tue Jun 22 2021
.UPDATE...
Issued at 932 PM MDT Tue Jun 22 2021
No big changes this evening. Made some adjustments to smoke
coverage as the Muddy Slide fire near Yampa and the Oil Springs
fire south of Rangely are the big smoke producers this evening.
Those plumes will come over Boulder and Denver, favoring the north
side of the metro area, overnight. How much smoke we see in the
morning will largely depend on how long the plume dominated fire
behavior goes during the night. The plumes should be diminishing
and drifting east by morning, again with most of the smoke staying
aloft. The area that could have a lot of low level smoke would be
the valleys of Grand county (and areas near the fire in Routt
county too).
&&
.SHORT TERM...(This evening through Wednesday)
Issued at 236 PM MDT Tue Jun 22 2021
RAP analysis this afternoon shows the upper level ridge
continuing to build across the area. There`s a little embedded
moisture aloft which has led to some scattered cloud cover across
the higher terrain, though we`re still cloud free across most of
the plains. Temperatures in the low 90s are common across the
plains and in the 80s for the Foothills and high valleys. Winds
have increased a tad over the plains but a more notable pickup in
gusts has been noted over Middle and North Park. Red Flag
conditions will likely continue into the early evening hours
tonight before winds decouple and humidity increases. Tonight
should be fairly quiet and mild for the Denver metro, with lows in
the upper 50s to low 60s. Cloud cover should gradually decrease
overnight tonight as surface temperatures cool.
Hot and dry weather will continue for Wednesday with 700mb
temperatures near 18-19C along with light downslope winds through
the day. Forecast highs are a couple degrees warmer than today,
with plenty of mid to upper 90s across the plains. The only
wildcard tomorrow will be the potential for high cloud cover
and/or smoke, but for now I`m not convinced this will be enough to
keep us "cool" in the afternoon. Models do show some very weak
instability in the afternoon as well, with at least a slight
chance of thunderstorms for the southern Foothills and South Park.
Almost no moisture to work with, so rainfall amounts would be
minimal.
The main concern will continue to be elevated and critical fire
danger across Middle and North Park, where Fire Weather Watches
remain in effect. Smoke could also be an issue during the day with
generally westerly flow aloft, which should advect smoke into the
area either tonight or tomorrow morning. HRRR Smoke forecasts
continue to bring in a decent area of smoke aloft, but this will
be highly dependent on how the ongoing fires behave this evening.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 236 PM MDT Tue Jun 22 2021
On Wednesday night into Thursday, models are showing the upper
ridging to push south and eastward away from Colorado as weak
upper troughing develops over the western United States. Troughing
is in place over the CWA Friday and Friday night. The QG Omega
fields show weak upward vertical velocity in place over the
forecast area Wednesday night through Friday. In the lower levels,
a cold front is expected to push across the area Thursday afternoon
then another, more significant one, on Friday.
Moisture is progged to increase over the forecast area with the
upper troughing. Precipitable water value progs range from 0.80-
1.20 inches for the plains to 0.50-0.90 inch in the mountains
Thursday through Friday night. There is fairly decent CAPE noted
on Thursday into Friday, with the highest amounts over the
northeast corner late in the day. There could be some severe
weather there around 00Z Friday; mainly hail and wind. Some areas
could see decent rainfall Thursday into Friday. Later Friday and
Friday night, the precipitation could be more stratiform in nature
behind the front.
Temperatures should be around seasonal normals on Thursday, then well
below on Friday. That will continue for the later periods with
cooler than normal readings Saturday through Monday. Tuesday`s
highs look to be near normals. So no 90s F plus temperatures are
expected for Denver Thursday through Tuesday.
Weather-wise, in the extended period, Saturday through Tuesday,
upper troughing is in place Saturday, then northerly flow aloft
Sunday into Monday. Upper ridging gets back over us by Tuesday.
Saturday still looks like some rainfall is possible. Sunday and
Monday are pretty dry, with Tuesday looking like no precipitation
will fall at all.
&&
.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 932 PM MDT Tue Jun 22 2021
Wildfire smoke plumes will be over the Denver area again tonight,
but little impact on surface visibility is expected. This smoke
will likely diminish Wednesday morning with new plumes developing
mainly southwest through northwest of Denver Wednesday afternoon.
The smoke layers and poor slant visibility may affect KDEN
approaches, mainly before 12z Wednesday and again after 22z.
No other weather impacts are expected with only isolated high
based showers Wednesday afternoon.
&&
.FIRE WEATHER...
Issued at 236 PM MDT Tue Jun 22 2021
Critical fire danger will continue into the early evening hours
across North and Middle Park, but conditions will quickly ease
through the evening hours. Near-critical or critical fire danger
is likely again tomorrow across the same areas with RH near
10-15%. There are two factors that limit confidence in meeting
criteria - (1) the potential for smoke and high cloud cover
limiting heating, and (2) weaker boundary layer winds. Due to
these concerns we`ll hold off on making a decision for the Fire
Weather Watch.
A cooler, more moist airmass should be in place over all the
forecast area Thursday into the weekend; critical fire danger is
not expected.
&&
.HYDROLOGY...
Issued at 236 PM MDT Tue Jun 22 2021
No hydro concerns tonight and tomorrow. There is a slight chance
of thunderstorms tomorrow afternoon, mainly for the southern
Foothills and South Park. Any rainfall from storms would be very
light.
Some areas of heavy rainfall are possible across the northeastern
corner of the CWA Thursday afternoon and evening. The burn scars
in the foothills could also see brief heavy rainfall Thursday, Friday
and Saturday afternoon and evening.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
Fire Weather Watch from Wednesday morning through Wednesday
evening for COZ211-213-217.
&&
$$
UPDATE...Gimmestad
SHORT TERM.....Hiris
LONG TERM......RJK
AVIATION...Gimmestad
FIRE WEATHER...Hiris/RJK
HYDROLOGY......Hiris/RJK
Area Forecast Discussion
National Weather Service Grand Forks ND
1030 PM CDT Tue Jun 22 2021
.UPDATE...
Issued at 1026 PM CDT Tue Jun 22 2021
Southwesterly winds are beginning to subside this evening, and
turn a bit more southerly as they decrease in magnitude. There is
an increase in mid-level moisture across southern MN and into
north central MN, and will adjust skies if needed although I did
bump up coverage on the 7 PM update. One change will be to add a
brief period where a shower or elevated cell may develop along
the intl border. A H850 LLJ develops around midnight in western ND
and increases in intensity as it approaches SE MB...with HRRR
showing 50+ kts across far SE MN and LOW around 12Z. HRRRTL and
ARW guidance POPs best aligned with when nose of the jet moves
into SE MB, so used that blend for timing, but the best increase
in intensity is as the LLJ moves into western Ontario. Would think
somewhere across SE MB and along our MN/MB border a shower could
easily develop, especially across LOW near sunrise.
UPDATE Issued at 637 PM CDT Tue Jun 22 2021
Southwest winds to continue tonight and actually pick up after
midnight, mainly across eastern North Dakota. The late night
mixing will keep overnight lows near sixty across the Devils Lake
basing while west central MN sites will drop into the lower 50s.
Did increase cloud cover for mid/high cloud over Sask/MB that will
translate across area tonight as NW flow aloft continues.
&&
.SHORT TERM...(This evening through Wednesday night)
Issued at 305 PM CDT Tue Jun 22 2021
Impacts are not expected through the remainder of today into the
evening and overnight. Low temperatures will fall into the middle
50s to near 60 degrees. Looking into Thursday morning, cloud
cover increases early for areas north of hwy 2. Areas to the south
will see sunny skies through at least midday. H5 thermal ridging
allows temperatures to climb sharply with highs expected to soar
into the middle 90s, with perhaps upper 90s for the southern Red
River Valley.
A cold front pushes through the area during Wednesday evening,
bringing a chance for showers and thunderstorms to the region.
There is a marginal chance for severe thunderstorms, primarily for
northwest and north-central Minnesota, as well as the northern Red
River Valley. Soundings indicate CAPE as high as 1500 J/Kg, as
well as favorable deep layer shear. As such, we are looking at the
potential for damaging wind gusts and hail upwards of one inch. We
could see impactful weather through the evening in association
with these thunderstorms.
.LONG TERM...(Thursday through Tuesday)
Issued at 305 PM CDT Tue Jun 22 2021
Impacts throughout the long term period will be tethered to the
potential for showers and thunderstorms during the late week period
and into weekend with shortwaves progressing through northwesterly
flow aloft. A drier air mass is then expected to settle in moving
into next week with temperatures warming from near normal over the
weekend back to above normal by early next week.
Thursday through Sunday...
As an upper level ridge builds in over the western CONUS, induced
northwesterly flow aloft is expected across the northern Plains.
This flow pattern will be conducive to increased shortwave potential
moving into the late week and weekend period. An interesting setup
is being depicted within ensemble guidance for Thursday as a split
flow pattern over the Plains looks to introduce a primary shortwave
from the northwest and secondary wave moving in from the south. This
will in turn bring about the potential for some fairly widespread
light rain to the area late Thursday into Friday. There are still
some ensemble discrepancies with regards to the magnitude of
precipitation potential, but overall confidence is increasing in
this system. Moving into the weekend, the potential is there for a
shortwave or two to ride the northwesterly flow into the area, but
confidence at this time is low. Otherwise, temperatures look to
remain relatively steady in the upper 70s to 80s for the weekend.
Next week...
The upper level ridge over the western CONUS is progged to slowly
travel eastward by the early week period. Cluster analysis generally
agrees on this solution, although the exact magnitude and eastern
extent of the ridge within guidance is the main question mark at
this time. Regardless, this will effectively stymie precipitation
potential while also introducing a warming trend for the week ahead.
&&
.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1026 PM CDT Tue Jun 22 2021
There is increasing confidence for a period of LLWS tonight as a
LLJ ramps up across western ND and turns more southwesterly as it
flows along the border and into southeastern MB. Should mainly
impact DVL/GFK/TVF and bumpy conditions can be expected north of
Hwy 200 (see aviationweather.gov for official low level turbulence
charts). Strongest 850 mb winds should across the northern valley
and northwestern MN. For the last six hours of this TAF period,
will see increasing chances for TS across NW MN (TVF/BJI) tomorrow
evening. Other than LLWS tonight and TS potential tomorrow eve,
CAVOK throughout TAF period.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.
$$
UPDATE...Speicher
SHORT TERM...Lynch
LONG TERM...Rick
AVIATION...Speicher
AREA FORECAST DISCUSSION
National Weather Service Sioux Falls SD
707 PM CDT Tue Jun 22 2021
.SHORT TERM...(This Evening through Wednesday)
Issued at 233 PM CDT Tue Jun 22 2021
Mid afternoon objective analysis shows a relatively stationary
boundary roughly draped along the SD/NE border eastward toward Le
Mars and eventually southeastward toward Storm Lake. Along and south
of it, a notable agitated Cu field has developed along with
festering weak convection. Biggest question regarding today`s
convection continues to be the quality and depth of moisture and
thus the resultant instability. Surface obs across the region show
dewpoints largely in the mid to upper 50s with some pooling of
moisture noted along the front with a few lower 60 dewpoints. This
has resulted in 500-1000 J/kg of MLCAPE via RAP mesoanalysis. Should
established deep convection result, effective shear around or in
excess of 45 kts will be more than sufficient for rotating updrafts.
High res CAMs in decent agreement for more robust convective
development in the 3-5 pm time frame just a bit north of Hwy 20 with
Bunkers RM vectors taking storms quickly off to the south/southeast.
With relatively straight and enlarged hodographs in the mid to upper
levels, may see a tendency for a few cell splits as well. Despite
the rather skinny and meager instability profiles, this enhanced
deep layer shear may compensate to allow for a hail report up to
ping pong ball size and damaging wind up to 60 mph. While the
presence of a boundary would typically spark some tornado concern,
LCLs likely too high for a higher concern with regards to that.
Any severe potential would likely be confined to prior to 8 pm with
perhaps some lingering elevated convection through the remainder of
the evening. Otherwise, quiet overnight period expected with some
hint at fog or lower stratus late tonight into Wednesday morning,
given the dry ambient conditions and lack of support by SREF
probabilities, not sold on this idea just yet.
A very warm day for Wednesday as 850 mb temperatures warm into the
upper 10th percentile of climatology. Would expect widespread 90s
for afternoon highs with a few locations near and west of the James
River perhaps exceeding the century mark. Dewpoints won`t be overly
oppressive so any Heat Advisory criteria may be a bit more localized
and thus have opted against an advisory.
Mid level lapse rates will also begin to steepen through the
afternoon and evening Wednesday with a wave likely sparking at least
isolated to scattered convection over the High Plains. Guidance in
fair agreement with taking this convection eastward through the
evening and early overnight hours with consensus for any stronger
activity to remain south of the MO River. With this said, not
impossible to get a stronger wind gust into our MO River counties
with forecast soundings showing a strong inverted V characteristic.
This is covered by a Marginal Risk from SPC.
.LONG TERM...(Wednesday Night through Tuesday)
Issued at 233 PM CDT Tue Jun 22 2021
Thursday forecast remains a question mark with a strong dependence
on any convective evolution from Wednesday night and the eventual
placement of the synoptic boundary for the daytime hours Thursday.
Along and ahead of this boundary, moderate to perhaps strong
instability will remain in place and while deep layer effective
shear may be somewhat limited, will continue to carry a
strong/severe thunderstorm risk. SPC has highlighted the southeast
half of our coverage area in a Marginal/Slight which seems like a
reasonable start and will likely evolve as higher confidence in
boundary placement occurs. Currently, NW IA and surrounding areas
likely carry the highest precipitation and severe weather potential.
Temperatures Thursday also in flux but roughly mid 80s to lower 90s
seem reasonable for now.
Upper level troughing carves in for Friday with some continued
precipitation chances. Still some model discrepancy on where this
trough axis sets up but some pairing from the GFS/ECMWF for a
favorable placement for our area for occasional bouts of
precipitation through the weekend. This will also keep temperatures
near or below normal.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 705 PM CDT Tue Jun 22 2021
Scattered thunderstorms will continue around the KSUX area over
the next couple of hours, but should be mainly north/east of KSUX.
Otherwise, will continue VFR through 00z Thu.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
SHORT TERM...Kalin
LONG TERM...Kalin
AVIATION...Chapman
Area Forecast Discussion
National Weather Service Wilmington NC
721 PM EDT Tue Jun 22 2021
.SYNOPSIS...
A cold front will sweep across the area tonight, accompanied by
some showers and thunderstorms. Cool and dry high pressure will
build in from the north Wednesday into Thursday with below
normal temperatures. The lingering front offshore will move
inland on Friday with increasing warmth and chances of showers
or thunderstorms increasing through the weekend.
&&
.UPDATE...
The line of convection along the front is moving through
Elizabethtown, Dillon, and Darlington currently and should be
in Wilmington, Whiteville, and Florence in just a couple hours.
I`m keeping PoPs in the 60-80 percent range across the area.
The HRRR shows the line breaking up as it dips farther south
toward Myrtle Beach and Georgetown overnight due to the cooling
boundary layer, but I`m maintaining 30-50 PoPs even here given
the good convergence continuing along the front. Low level cold
advection behind the front could generate a layer of low stratus
late tonight into Wednesday morning. Changes this update mainly
centered on PoPs, weather, and clouds. No changes to forecast
low temps.
&&
.NEAR TERM /THROUGH WEDNESDAY NIGHT/...
Moisture rich environment ahead of approaching cold front this
afternoon, with pcp water values up over 2 inches, but lacking
in the sfc heating with such extensive cloud cover and shower
activity. The front was draped from SW to NE across the Raleigh
area around 3pm this aftn, evident by a line of convection. Overall,
expect best potential for stronger storm development associated
with lift along the front and enhanced by shortwave energy
rotating around main mid to upper trough into early this
evening. Increasing low level winds up to 45 kts with mainly
unidirectional shear out of the SW will help to create limited
potential for damaging wind gusts with the convection through
this evening. Convection will weaken and diminish as heating of
the day cuts off, tapering off once front moves through and
winds shift from SW to N-NE. SPC keeps our local area in
marginal risk of severe weather through this evening with a few
strong to severe storms possible, with main threat of damaging
wind gusts.
Cold front will drop into the area between 10p and midnight,
clearing the coast by daybreak. Lingering moisture and clouds
should move off the coast through Wed morning as sfc high builds
down from the north, but mid to upper trough will flatten out
and lift north leaving front lingering in the offshore waters as
high pressure builds down from the north. Winds will shift
around from SW to NE as front moves through. Soundings and
moisture profiles show deep drying through the column with some
lingering low level moisture which dries out by Wed aftn, drying
out further into Wed night. Pcp water values drop from 1.6
inches before daybreak Wed down less than an inch by midnight
and possibly down to a half inch by Thurs morning.
Overall, expect clearing skies and increasing sunshine through
Wed with relatively cool and dry air keeping temps near 80, over
5 to 10 degrees below normal. Overnight lows will be closer to
normal tonight, but by Thurs morning, lows will drop down near
60 inland. Should see some fog around inland but as dewpoints
drop, any fog should clear into the morning. Dewpoint temps
close to 70 this evening will be down in the 50s by Wed night.
&&
.SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/...
A weakening wedge of surface high pressure will be in place through
the period. Models have trended much drier with the forecast, now
suppressing the measurable rain offshore, a trend we were starting
yesterday. Clouds may linger along the coast however while inland
locales see breaks of sunshine. This will likely suppress highs by a
few degrees below their inland counterparts; both inland and coastal
locations remaining below climatology.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
Weak flow aloft on Friday while a weak warm front/trough moves
ashore. Morning showers along the coast will spread inland along
with the boundary. With highs still only in the lower 80s
instability may be meager enough for only isolated thunder. Fairly
deep but weak onshore flow becomes established Saturday which should
wind up fairly seasonable and with just a slightly elevated coverage
of mainly diurnal storms. The deep onshore flow remains Sunday but
subtle height rises from the northeast should tend to trim
convective coverage back to normal (30 percent-ish). The upper level
ridge to our northeast strengthens further Monday into Tuesday. The
deep layer onshore flow will thus continue and keep the area
susceptible to diurnal showers and isolated thunderstorms as the
deep layer of marine air contains only very weak lapse rates.
&&
.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
A cold front moving across the eastern Carolinas tonight is
outlined by convective showers and some embedded thunderstorms.
This activity should move southeastward this evening, affecting
the FLO and ILM airports as early as 01-02z with the potential
for lowered visibility and variable winds. Convective activity
is expected to weaken later this evening as the line dips into
the MYR/CRE vicinity after 04z, however visibility restrictions
remain possible in moderate rain. Low stratus is expected to
develop behind the front overnight with MVFR/IFR ceilings
anticipated to overspread the area between 04-08z. Conditions
may not improve until Wednesday afternoon in the ILM vicinity.
Surface winds should become northeasterly behind the front
overnight, with wind speeds increasing to 10-12 knots during the
day Wednesday.
Extended Outlook...Predominantly VFR Wednesday night through
Friday morning. Convective showers and thunderstorms may return
Friday through Sunday as the front moves back onshore
&&
.MARINE...
Through Wednesday night...
SCA conditions will continue into tonight in gusty SW winds
ahead of a cold front. SW wind speeds are 25 to 30 kt
sustained. Expect the CFP to occur during the pre-dawn Wed hrs,
sinking SE- ward to just offshore before stalling during Wed.
Winds will back to the NE-ENE after FROPA and actually may be
underdone by guidance. The post cold frontal NE surge will lie
just below SCA thresholds but the seas will be slow to subside
due to the stalled front in close proximity and the continued
pseudo/fresh swell feed. SCA thresholds will be borderline
during Wed, especially the waters off Cape Fear. Seas generally
5 to 8 ft at the start, subsiding to 3 to 5 ft at the end of the
fcst period but subject to change especially toward the end.
Potential SMW type convection by midday today and continuing
into the evening with potential for 34+ kt wind gusts and
occasional/frequent reduced vsby below 1nm at times from the
heavy rain.
Thursday through Sunday...E to NE winds Thursday as high pressure
wedging in from the north starts to weaken/break down. Flow turns
more southerly on Friday as the continuation of this process allows
a warm front to move ashore. Over the weekend the gradient remains
weaker than normal as Atlantic high pressure is displaced north and
east of its more normal June position closer to Bermuda. The short
period wind wave will dominate seas through the period but there
will be a few longer period wave components, primarily out of the
southeast. One will have a 7-8 second period and the other 12-13
seconds.
&&
.TIDES/COASTAL FLOODING...
Abnormally low tides, below -1 ft MLLW, will continue for the
next several tide cycles as we approach the full moon on
Thursday.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...High Rip Current Risk until 8 PM EDT this evening for SCZ054.
Beach Hazards Statement until 8 PM EDT this evening for SCZ056.
NC...High Rip Current Risk until 8 PM EDT this evening for NCZ106-
108-110.
Beach Hazards Statement from 6 AM EDT Wednesday through
Wednesday evening for NCZ106-108.
MARINE...Small Craft Advisory until 1 AM EDT Wednesday for AMZ250-252-
254-256.
&&
$$
SYNOPSIS...ILM
UPDATE...TRA
NEAR TERM...RGZ
SHORT TERM...MBB
LONG TERM...MBB
AVIATION...43
MARINE...MBB/RGZ
TIDES/COASTAL FLOODING...RGZ
Area Forecast Discussion
National Weather Service Lincoln IL
816 PM CDT Tue Jun 22 2021
.SYNOPSIS...
Issued at 244 PM CDT Tue Jun 22 2021
A few showers or storms could affect areas north of a Canton to
Bloomington line tonight, with drier conditions toward morning.
Dry weather will prevail farther south. Strengthening south winds
on Wednesday, will push high temperatures into the lower 80s.
&&
.UPDATE...
Issued at 814 PM CDT Tue Jun 22 2021
Light to moderate rain is moving into Galesburg and other areas
north of the Illinois River Valley this hour. Further west, a few
severe storms are noted, moving generally towards the south.
Latest RAP shows instability gradient set up just to our west and
not expected to shift east much at all this evening. Thus, precip
should be in a diminishing state as it moves into the forecast
area as it outruns the instability and encounters a more dry air
mass per the 00Z KILX raob, which shows a deep layer of dry air
in the lower and mid levels. Do not anticipate the stronger storms
to move into the forecast area at this time.
&&
.SHORT TERM...(This evening through Wednesday)
ISSUED AT 244 PM CDT Tue Jun 22 2021
Early this afternoon high pressure stretched from Arkansas
northeast through southeast IL and to the eastern Great Lakes.
This brought pleasant early summer weather to the region today
with plenty of sunshine and readings several degrees below normal
in the low to mid 70s.
Scattered showers and storms over western and central Iowa,
associated with sheared shortwave in 500 mb NW flow and developing
warm/moist advection aloft, will increase this evening as a 45 kt
925 mb jet strengthens from southern IA into western IL. This
could bring a few strong storms to our west before weakening
activity works across the northwest CWA this evening and
overnight. Better low level moisture advection remains to the
northwest, leaving conditions fairly dry below 800 mb this far
east. A few thunderstorms could affect areas northwest of Peoria
this evening, but primarily scattered showers expected as far
south as a Canton to Bloomington line overnight. Light southeast
return flow on the back side of the high will keep lows several
degrees higher than last night, in the upper 50s to lower 60s
(coolest south of I-70).
A few showers will linger over the northern CWA into Wednesday
morning, before the warm advection wing lifts northeast of the
area. A tightening pressure gradient will result in breezy south
winds, gusting up to 30 mph during the afternoon. This will push
highs to more seasonable levels in the lower 80s.
.LONG TERM...(Thursday through Tuesday)
ISSUED AT 244 PM CDT Tue Jun 22 2021
Active weather looks to dominate the extended forecast, as a
slowly amplifying upper trof tracks into the central U.S. for
Thursday through the upcoming weekend. This pushes a cold front
into the Midwest on Thursday, when the SPC day 3 outlook
highlights a slight risk of severe storms just to our west.
Marginal risk extends east through the IL River Valley, primarily
for evening strong storm potential. Assuming most of the storms
stay to our west thought the afternoon this would be the warmest
day of the week with highs in the mid to upper 80s.
While many details are unclear for Friday through Sunday, the
general theme among the medium range models is that the front will
be very slow to move across the region, as it becomes parallel to
the mid level flow. This will result in periods of showers and
thunderstorms. With the upper level jet aligned from the Plains
into the Great Lakes, and very high precipitable water values near
2", severe storms and heavy rainfall will be a threat. Again hard
to pin down details at this range in regards to severe wx, but
QPF of 2-5" would bring in flooding concerns, primarily in areas
that are repeatedly hit with heavy rain.
Some signs the upper trof could close off across the upper
Midwest early next week, keeping the unsettled weather pattern in
place with lesser chances of heavy rain or severe storms. Highs
should generally be in the 80s with 850 mb temps consistently in
the upper teens C, though the humid airmass will trend lows above
normal in the upper 60s to lower 70s.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 615 PM CDT Tue Jun 22 2021
South to southeast winds will prevail this evening and overnight,
then winds will veer to the S/SSW and become gusty into the low
to mid 20 kt range during the day Wednesday. A few spotty showers
or storms are possible overnight, with the best chance of anything
on station at PIA and BMI. The overall chance is low though as
showers should decay as they encounter drier air in place over the
state. Outside of any precip, VFR conditions will prevail.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Deubelbeiss
SYNOPSIS...25
SHORT TERM...25
LONG TERM...25
AVIATION...Deubelbeiss
Area Forecast Discussion...UPDATED
National Weather Service North Platte NE
900 PM CDT Tue Jun 22 2021
.UPDATE...
Issued at 900 PM CDT Tue Jun 22 2021
With the loss of daytime heating, thunderstorm chances across
ncntl Nebraska appear to have diminished. A forecast update is in
place for dry weather in this region and wrn Nebraska the rest of
tonight.
&&
.SHORT TERM...(This evening through Wednesday night)
Issued at 342 PM CDT Tue Jun 22 2021
A weak disturbance is pushing across SD this afternoon. A weak
surface low reflection is noted across far northeast portions of
north central Nebraska to the north of O`Neill. A warm front extends
east-southeast from the low across northeast NE and a trailing
surface trough extends southwest across the southern Sandhills into
the southern Panhandle. Most CAMS and the last few runs of the HRRR
keep most of the convection focused east of the area near the warm
front. There is some chance however that the initial development
could occur across eastern Holt and Wheeler county in area of low-
level convergence just east of the weak surface low. Overnight the
low will weaken and dissipate with the training surface trough
across the area washing out.
Attention then turns to Wednesday afternoon. There are two main
concerns Wednesday afternoon 1) hot temperatures and humidity and 2)
thunderstorm development. First the hot temperatures. A plume of
very warm air aloft with H7 temps around 17C and H85 temps of 27-31C
will spread across the area. A surge of low-level Gulf moisture will
also accompany the heat with dew points rising into the mid and
perhaps upper 60s by late Wednesday afternoon along and east of
Highway 83. The combination of heat and humidity will cause heat
index values to reach into the 100-105 degree range. Will issue a
heat advisory to cover the heat and humidity combo. Farther west the
air will be much drier with heat index values in the mid 90s and
will forgo headlines for these areas.
As far as thunderstorm potential late Wednesday afternoon and
evening...the very warm mid-level temperatures are a concern.
Nevertheless a weak disturbance will approach the western High
Plains during peak heating. Weak large scale lift ahead of this
feature will probably lead to widely scattered thunderstorm
development along a leeward surface trough within a well mixed and
relatively dry boundary layer. A reservoir of very high CAPE will
reside just to the east of the initial development due to increasing
low-level moisture and very steep mid-level lapse rates. Within this
area the NAM suggest SFC based CAPE values nearing 4000 J/KG and 30-
40 kts of 0-6km deep layer shear. Several HREF members grow the
activity upscale as it moves east into the moist and unstable
environment across northern Nebraska. This seems possible as a
southerly low-level jet intensifies helping to maintain, but as
mentioned very warm mid-level temperatures could limit coverage. As
far as threats, the very steep mid-level lapse rates could enhance
hail potential, and large temperature/dew point spreads could
enhance wind potential (especially early on across western NE within
a well mixed drier boundary layer).
.LONG TERM...(Thursday through Tuesday)
Issued at 342 PM CDT Tue Jun 22 2021
Upper level ridging will be replaced by long wave troughing that
develops from central Canada through the Central Plains. This occurs
as upper level ridging develops along both coasts. This will bring
an increase in cloud cover as well as a chance for rainfall. Models
have been struggling with this overall scenario and it is unclear
how much precipitation may fall. More certain is that it will be
cooler with highs generally in the 70s Friday and 70s to lower 80s
Saturday into Sunday. Could locally be cooler if more precipitation
materializes.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 643 PM CDT Tue Jun 22 2021
VFR conditions will prevail over the next 24 hours with mostly
clear skies. Winds will remain light over the next 24 hours,
generally out of the south to southwest.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
Heat Advisory from noon CDT /11 AM MDT/ to 8 PM CDT /7 PM MDT/
Wednesday for NEZ005>010-025>029-036>038-057>059-069>071.
&&
$$
UPDATE...CDC
SHORT TERM...Taylor
LONG TERM...Taylor
AVIATION...Gomez
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
1020 PM CDT Tue Jun 22 2021
.UPDATE...
1020 PM CDT
Modest adjustments to the going forecast tonight through Wednesday
night, mainly to increase winds/gusts a bit from later tonight
onward as Wednesday into Thursday look fairly breezy/windy. Also
tweaked pops a bit through late evening, with best chances of
showers/isolated thunderstorms largely after midnight even across
our western counties.
Low-amplitude short wave was evident tracking southeast across
western IA this evening, with an associated enhancement of the
more broad scale southwesterly low level flow across the central
and southern Plains. Scattered thunderstorms which had formed this
afternoon across central and eastern IA continue on the nose of
a southwesterly 35 kt H8 jet, with a gradual weakening trend
as cells propagate southeast into western IL and away from the
better MUCAPE axis per RAP mesoanalysis data. This has kept the
WFO LOT cwa fairly quiet through the evening, except for a few
decaying light showers west of I-39. Expectation is that showers
will later develop and expand in coverage eastward into northern
IL as the low level jet veers into the area and the mid-level wave
tracks to the east. Forecast soundings do indicate some weak
elevated instability overnight, which will likely allow for some
isolated/embedded thunder late tonight into early Wednesday though
coverage should be limited (with scattered showers more
widespread) and without a severe weather threat. Tweaked pops
downward across the area through midnight, but maintained likelys
late tonight into Wednesday morning based on these trends. Precip
potential should diminish across the area by midday/early
afternoon as increasing southwesterly flow lifts the elevated warm
front north of the forecast area.
As the 30-35 kt low level jet shifts across the are late tonight
and Wednesday breezy conditions are expected to develop,
especially from mid-morning on as diurnal warming deepens the
mixed layer. Gusts around 30 mph are likely. Breezy conditions
will likely continue Wednesday night and into Thursday as well,
with strong southwest flow persisting above the boundary layer.
Updated digital and text forecast products are available.
Ratzer
&&
.SHORT TERM...
317 PM CDT
Through Wednesday night...
It was another pleasant - cooler than normal - summer day today
with highs in the lower to mid 70s with the local area under the
surface ridge axis.
Off and on warm advective showers are expected to push into the
area overnight along the nose of the low-level jet, potentially
aided by a weak mid-level disturbance. These showers are expected
to expand in coverage overnight into Wednesday morning but should
be rather intermittent, rather than raining all night and through
the morning. There is a period where guidance shows a weak axis
of MUCAPE moves overhead which would support at least mention of
embedded thunder possible.
The upper trough axis shifts off to the east on Wednesday with
warmer air lifting back into the area behind the showers. This
will allow temperatures to warm back into the lower 80s for most
areas. This will also be aided by mixing down of gusty winds
through the afternoon with gusts up to 25-30 mph possible. There
could be a few isolated showers that linger into the afternoon
period, but for now will maintain a dry forecast for that period.
The strong low level jet remains overhead into Wednesday night
which could allow for sporadic stronger gusts to persist into the
evening and overnight hours.
Petr
&&
.LONG TERM...
333 PM CDT
Thursday through Tuesday...
Main long term forecast focus continues to be on thunderstorm
chances and coverage Thursday into Saturday along with the potential
for locally heavy rainfall and severe weather.
Areas of convection are likely west and northwest of the cwa later
Wednesday night into early Thursday morning. Guidance continues to
indicate a minor amplitude short wave trough will ripple through
westerly mid-level flow, while the nose of a southwesterly low level
jet orients warm/moist advection into far northern IL/southern WI
Thursday morning. This suggests at least some potential for upstream
convection to work into especially north central IL and the IL/WI
state line after sunrise Thursday, though perhaps in a decaying mode
by that time. Confidence remains fairly low on evolution into the
cwa, but chance pops continue to appear warranted for the northwest
cwa Thursday. Its possible that precip chances will remain
isolated/scattered Thursday afternoon/evening.
Medium-range guidance is in reasonably good agreement in bringing
another somewhat more amplified mid-level trough across the area
late Thursday night into Friday, before a large upper trough digs
across the upper Midwest and Great Lakes region into the weekend. A
pair of surface lows accompany these upper features, which slowly
trail a surface cold front into the area Friday night through
Sunday. Some timing/locations differences remain, which along with
any modulation of MCS outflow boundaries and effects on instability
during the the period, but strong, possibly severe thunderstorms are
certainly possible. In addition, precipitable water values approach
2 inches on Thursday but on Friday with lower 70s dewpoints,
possible mid 70s dewpoints pooling along the frontal boundary,
precipitable water values push into the 2 to 2.30 inch range. Thus,
torrential rain and localized flooding would be possible. Model qpf
amounts vary quite a bit regarding the placement of the heaviest
axis, but in general, the models are showing the potential for
several inches of rain nearby. High pops from the blended guidance
still look fine for this time period.
With the upper trough expected to be over the region through at
least early next week, possibly closing off as an upper low for a
time as the ECMWF and GEM are indicating, at least chance pops are
needed for the rest of the extended period. Its likely that as these
time periods approach, pops can be trimmed at night with mainly
diurnally driven activity but too early for that detail yet. And the
front may be strong enough to clear precip from the area for part of
the time this weekend.
Better moisture and frontal focus moves east/southeast of the area
into early next week, though upper low wobbling in the vicinity as
indicated in EC/GEM solutions may warrant at least some chance
pops into Monday/Tuesday.
cms/Ratzer
Ratzer
&&
.AVIATION...
For the 00Z TAFs...
Aviation Forecast Concerns:
* Showers and perhaps an isolated thunderstorm or two developing
late tonight and persisting into Wednesday morning.
* South-southwest winds become somewhat gusty late tonight and
more so Wednesday, with gusts near 30 kts possible Wednesday
afternoon.
* Breezy conditions persist Wednesday evening, maintaining some
degree of surface gusts. 40-45 kt low level jet will result in
LLWS potential especially if surface gusts remain on the lower
side.
A mid-level disturbance digging southeast from the upper Missouri
Valley was inducing south-southwesterly return flow west of the
Mississippi River late this afternoon. The resulting low level jet
was producing elevated showers and thunderstorms within the region
of moist ascent focused across IA early this evening. This
activity is expected to develop east-southeast into parts of
northern IL later this evening, with showers and a few isolated
thunderstorms persisting through Wednesday morning as the low
level axis shifts east. The best chance of thunderstorms is expected
to remain mainly to the west and southwest of the terminals during
this period, though an isolated thunderstorm can`t be ruled out
especially early Wednesday morning. KRFD may have the best
potential for isolated thunder, and have included a tempo mention
there later tonight. It does appear that a period of scattered
showers will affect the terminals however. Cloud bases and
prevailing visibilities are expected to remain VFR.
Light winds will back south-southwest this evening, and will
increase a bit overnight as warm advection strengthens. Some gusts
around 20 kts are possible late despite the nocturnally stabilized
boundary layer as flow increases aloft. Southwest winds will
increase Wednesday, with gusts around 30 kt possible by afternoon
as the surface pressure gradient tightens and 850 mb flow
increases into the 30-35 kt range. Winds will likely remain
somewhat gusty even after sunset Wednesday night, though some
potential for LLWS will exist as the low level jet increases to
40-45 kts.
Ratzer
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...Small Craft Advisory...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
LMZ745...7 AM Wednesday to 10 PM Thursday.
&&
$$
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Area Forecast Discussion
National Weather Service Pendleton OR
754 PM PDT Tue Jun 22 2021
.UPDATE...The latest radar was showing showers and thunderstorms
mostly over se Oregon with another area over central Oregon near
rdm. At first the hrr and rap models did not handle the area of
pcpn around central Oregon as well and have expanded area of
thunderstorms for this evening. Otherwise these models have come
into better agreement and bring the pcpn over se Oregon further
north into portions of the Blue Mountains and Union/Wallowa
counties before lessening toward morning and the forecast has been
updated to reflect this.
Other than some changes to sky and pops and pcpn amounts the
present short term forecast appears on track.
Further ahead into the extended forecast it appears our area of
south central Washington and North Central Oregon will be under a
strong high pressure system by this weekend. The current models
were indicating a very warm...and hot temperatures and the
confidence in the forecast is increasing. Therefore stay informed
by listening to NOAA weather radio...internet...social media for
possible later statements regarding this potentially extreme
hot temperature event.
&&
.PREV DISCUSSION... /issued 454 PM PDT Tue Jun 22 2021/
SHORT TERM...Tonight through Thursday night...Upper low off of
California coast and southwest flow over the region has brought
increased moisture over the area. As several shortwaves move
through the flow, the region, especially Central and eastern
Oregon have been primed for thunderstorm development. However,
satellite imagery continues to show abundant cloud cover over a
good portion of eastern Oregon, with the Bend/Redmond area just
breaking out and these clouds clearly have inhibited thunderstorm
development. Latest radar shows a few showers across the central
and eastern Oregon highlands. There are occasional lightning
strikes but not much has gotten going. As the afternoon progresses
and temperatures warm, will thunderstorms begin to initiate across
areas where clouds break. The guidance differs on this, but there
is obvious support for some development.
Whatever showers and thunderstorms do develop this afternoon and
evening will come to an end overnight. Additional development is
expected on Wednesday, though likely with less areal coverage with
rising heights.
RH values will be lower on Wednesday and winds will be similar to
today. Also expect less cloud cover temps will be similar if not
a tad warmer. Therefore, extended the red flag warning through
Wednesday evening for a combination of RH, wind and thunderstorms.
Its possible winds across the Basin may necessitate the RFW be
extended further north, but at this time it is marginal and
thunderstorms are not expected in the Basin.
Once we get past Wednesday, precip chances end, and winds will
decrease but it remains dry and increasingly hot for the
foreseeable future.
High temperatures will range from the upper 80s to the upper 90s
in the Basin on Wednesday. Highs Thursday will be a similar though
perhaps a couple degrees cooler in the Basin. Overnight lows will
be in the 50s and 60s.
LONG TERM...Friday through Wednesday...The main story and concern
in the extended period will be the intense heat wave that is
expected to begin on Friday, and increase in intensity on
Saturday through the beginning of next week. All of the longer
range models and their ensembles are in good agreement in the
development of a large and strong upper high pressure system over
the PacNW, which will persist through the weekend into at least
early next week. At this time, these deterministic models and
their ensembles, as well as the NBM, are indicating that the
hottest days will be Saturday - Monday, with record temperatures
(both record high maximums and record high minimums) expected.
After several days of the models advertising this intense heat
wave, with little change in trend, confidence is high that this
will occur. The GFS deterministic model and the GEFS (GFS
ensemble) was originally the hottest, but now the new ECMWF and
Canadian models have come in line with the GFS/GEFS forecast
values.
If the upper end of the range of possible temperatures by the
models pan out, then we are looking at all time record high
temperatures for many or most areas of the CWA. However, the more
realistic values of the NBM 1D Viewer temperature forecasts would
still bring record heat, but perhaps not all time record highs.
However, cannot rule out the upper end forecast values by both
the deterministic and ensembles since they are all in much better
agreement with each other now with 850 mb temperatures rising
into the lower to mid 30s deg C at 850 mb by Sunday and Monday. If
this does actually occur, the Pendleton Airport, for example,
would reach temperatures in the neighborhood of 115 degree F,
which would be an all time record high temperature. The previous
all time high was 113, which was set in August, rather than June,
which makes this possible scenario even more significant. For
now, will go with the more realistic NBM forecast temperature
values based on climatology and the lower likelihood of seeing
temperatures in the upper end of the probabilistic range of
high temperature values by both the NBM and the resultant max
temperatures by using the forecast 850 mb temperatures in both the
deterministic and ensemble forecasts. This will bring the
Pendleton Airport to a maximum reading of 110 deg F on Monday as
the hottest day, which has occurred, or nearly occurred, several
times in the last 25 years. In any case, an Excessive Heat Watch
will be in effect from Friday afternoon through at least Tuesday
evening, and this will be issued this afternoon`s forecast
package.
There is some hit of a weak shortwave trough topping over the
high pressure ridge sometime early next week, which would cause
possible afternoon/evening thunderstorms, which would likely be
high based and mostly dry. Confidence is low on this occurrence,
so will keep the entire extended period dry with no precipitation
expected for now. Winds, for the most part, will be light, except
for the usual locally breezy areas in the afternoons and evenings,
mainly along the Cascades gaps, passes, eastern valleys, the
eastern Columbia River Gorge, and the Lower Columbia Basin. The
winds will also largely depend on where the position of the
surface thermally induce low pressure trough will be located each
day during this heat wave, especially wind direction. 88
AVIATION...Isold tsra will develop in and near taf sites krdm and
kbdn that may produce lcl mvfr conditions with vsby and ceilings
along with brief wind gusts to 30kts until 06z. Meanwhile taf sites
kalw and kpdt may experience brief wind gusts to 30 kts through 04z
and rain showers are possible. Otherwise the remainder of the taf
sites should experience mainly vfr conditions for the next 24 hours.
&&
.PRELIMINARY POINT TEMPS/POPS...
PDT 62 94 59 92 / 10 0 0 0
ALW 67 97 63 92 / 10 0 0 0
PSC 65 99 62 96 / 0 0 0 0
YKM 63 97 62 96 / 0 0 0 0
HRI 66 98 62 96 / 10 0 0 0
ELN 64 89 62 90 / 0 0 0 0
RDM 52 91 50 91 / 20 20 10 0
LGD 55 91 52 86 / 40 10 10 0
GCD 57 90 57 89 / 20 20 10 0
DLS 63 91 62 92 / 0 0 0 0
&&
.PDT WATCHES/WARNINGS/ADVISORIES...
OR...Excessive Heat Watch from Friday afternoon through Tuesday
evening for ORZ041-044-049-050-502-503-505>511.
Red Flag Warning until 11 PM PDT Wednesday for ORZ611-640-642-
644-645.
WA...Excessive Heat Watch from Friday afternoon through Tuesday
evening for WAZ024-026>030-520-521.
&&
$$
SHORT TERM...97
LONG TERM....99
AVIATION...97
Area Forecast Discussion
National Weather Service Tucson AZ
220 PM MST Tue Jun 22 2021
.SYNOPSIS...A moisture increase from the south will bring a
chance of showers and a few thunderstorms to the area tonight and
Wednesday. Thereafter, the heat will return for the upcoming
weekend. The good news is that it will not be as hot or prolonged as
the recent record breaking heat wave. This will be due, in part, to
the increase in deeper moisture across the area starting early next
week. This moisture increase will moderate temperatures a bit and
result in the prospects of more areawide isolated to scattered
showers and thunderstorms most of next week.
&&
.DISCUSSION...Moisture will continue to increase across the area
tonight into tomorrow with a chance of showers and a few
thunderstorms in the forecast. Guidance from the UArizona WRF model
and NOAA`s HRRR were in overall agreement with shower and some
thunderstorm activity increasing tonight through Wednesday. The best
chance for this activity will be around Tucson and Nogales westward.
Thereafter, ensembles favored a drying trend as a more westerly flow
aloft develops during the latter one-half of the week. This drying
trend in combination with a ridge of high pressure aloft
strengthening over the western United States will result in a brief
period of hotter temperatures this weekend. The good news is that it
won`t be as hot and prolonged as the most recent record breaking
heat wave. This time the upper high becomes centered over the
Pacific Northwest bringing excessive heat to that region. Farther
south, though, this position of the upper high will eventually favor
an influx of moisture from the east and southeast as a surface cold
front dropping south through the Plains pushes westward into eastern
AZ. The timing of this feature and subsequent moisture advection
still remained somewhat uncertain but ensembles point to Sunday
night or next Monday for the start. Once this moisture advances into
eastern sections, daily shower and thunderstorm activity should be
on the increase and spread farther west during the week. In a
nutsell, the prospects of rain showers and thunderstorms will be on
the increase next week.
&&
.AVIATION...Valid through 24/00Z.
SCT-BKN clouds 10-14k ft MSL into tomorrow with periods of isolated
-SHRA/-TSRA, especially west of KTUS. Surface winds WLY/NWLY at 8-14
kts with a few gusts to near 25 kts both this afternoon and tomorrow
afternoon. Winds decrease light and variable at other times.
Aviation discussion not updated for TAF amendments.
&&
.FIRE WEATHER...A brief period of increased moisture will last
through Wednesday, returning again Sunday into early next week
resulting in scattered shower and thunderstorm activity. Any
thunderstorms that do develop may result in gusty outflow winds up
to 40 mph. Minimum relative humidity values will generally be in the
10-15 percent range in the valleys and 15-25 percent in the
mountains. 20-ft winds will be less than 15 mph, with typical
afternoon gustiness due to strong surface heating.
&&
.TWC WATCHES/WARNINGS/ADVISORIES...None.
&&
$$
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