Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/21/23
Area Forecast Discussion
National Weather Service La Crosse WI
1005 PM CDT Sat May 20 2023
.DISCUSSION...(This evening through Saturday)
Issued at 150 PM CDT Sat May 20 2023
Key Messages:
- Seasonable to warm, mainly dry weather expected into next week.
Northwest flow aloft will persist through the weekend as expansive
surface high pressure extends from the plains/central Canada through
the MS Valley/Great Lakes. This will result in light winds and
gradually warming temps. The RAP indicates the return of some
smoke aloft later Sunday into early next week from Canadian
wildfires which could add a hazy look to the sky.
Heading into early in new work week, mid-level ridging is forecast
to build across the central US yielding mainly dry, seasonably warm
weather for the local area. Tuesday is expected to be the warmest
(upper 70s to mid 80s) of the next several days with southwest
low-level flow and 925 mb temps climbing above 20C. An amplifying
trough across eastern Canada looks to drag a cold front south
through the area on Tuesday night/Wednesday with broad, dry
surface high pressure in its wake. Some cooling is expected behind
the mid-week front for a time, but generally near to above
average temps are expected with warming temps through late week.
Some low (20-30%) shower/storm chances persist in the forecast
heading into next weekend for now, but the higher chances for
showers/storms remain west of the area where moisture return
upstream from the low-level ridge is a bit stronger. However, there
is some uncertainty with the strength of the mid-level ridge and
placement of any subtle shortwave troughs. Given the modest
moisture/weak flow aloft, prospects for any organized strong/severe
storms appear very low during this time.
&&
.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1005 PM CDT Sat May 20 2023
CIGS: some hints in a few models that some diurnally driven cu could
pop up late morning/afternoon Sun...but would be VFR. Generally
though, expecting SKC conditions as the area continues under the
influence of high pressure.
WX/vsby: no impacts anticipated.
WINDS: light winds through the period with a southwest to southeast
direction favored.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
DISCUSSION...JM
AVIATION...Rieck
AREA FORECAST DISCUSSION
National Weather Service Bismarck ND
851 PM CDT Sat May 20 2023
.UPDATE...
Issued at 851 PM CDT Sat May 20 2023
A cluster of showers has expanded mainly over west central North
Dakota. A few thunderstorms have wound up developing on the back
side of these showers, mostly in McKenzie County. Although, a few
lightning strikes have been observed in Dunn County as well.
Expect thunder probably won`t last too long, but adjusted slight
chances of thunder a bit further east over the next couple hours.
Also adjusted PoPs based on latest radar and model forecast
trends.
UPDATE Issued at 643 PM CDT Sat May 20 2023
A line of showers in the northwestern corner of the state
continues to gradually move eastward. There have been some brief
rain observations with these showers. Don`t expect too much rain
is reaching the ground at this point with lots of dry air still in
place, although the ASOS at Williston briefly dropped down to 6SM
visibility. Though the drop in visibility may have been at least
partially caused by near-surface smoke.
The potential for an occasional rumble of thunder with these
showers appears to be decreasing. Limited instability in the far
northwest appears present based on the latest SPC mesoscale
analysis, although the atmosphere looks more likely than not to
remain capped. For now, left inherited PoPs and thunder mentions
in place and will re-evaluate later this evening.
In regard to the smoke, elevated smoke continues filtering into
the area. However, the 21Z RAPSmoke model continues the trend
mentioned earlier today in keeping the most impactful near-surface
smoke west of the state. Still, slight visibility reductions due
to smoke appear present in the very far northwestern corner of the
state and may continue filtering further south and east through
the night.
&&
.SHORT TERM...(This Evening through Sunday)
Issued at 122 PM CDT Sat May 20 2023
Current surface analysis places high stretching from the upper
Midwest into the southern plains, while a trough stretches through
the southern Canadian prairies dipping into the northern plains.
Upper level analysis places northwest flow over our area, but a
rather stout and compact low sliding through the broad northwest
flow is now situated over southern Saskatchewan. Ahead of this
feature, some light returns are showing up on radar, but expect
little reaching the ground given the relatively dry atmosphere.
What also is going on given the aforementioned features is
Canadian wildfire smoke is making a return as noted in satellite
and also being reflected in air quality sensor measurements over
the west. Readings are not near what was experienced earlier this
week, but it is still being noted.
For the rest of today into tonight, a few light rain showers and
maybe a few rumbles of thunder will be possible (mainly west) as
the little compact low continues on its way, but should fizzle out
by late tonight. Coverage will be quite sparse. What remains the
main concern, though, is the smoke. Expect this to continue
settling in, but some question on how dense this could be. Last
few runs of the RAP keep the brunt of the smoke off to our west,
but still still working some into our area. Therefore, will
continue patchy smoke over most locations, but will bump the west
up in coverage a bit more in case some of the denser smoke makes
it further east than though.
On Sunday, will keep smoke in the forecast through the day into
the evening, but with winds switching southeasterly there is a
chance that things could end up clearing out quicker than thought.
With that said, though the impact is not much have continue the
trend of shaving a couple degrees off high temps given the smoke
in the atmosphere. With that said, temperatures will be quite mild
with highs about 5 to 10 degrees above average.
.LONG TERM...(Monday through Saturday)
Issued at 122 PM CDT Sat May 20 2023
Monday looks to be the warmest day as ridge passes over, with 80s
expected for highs over most locations. Ridge then starts to
move off to the east with flow becoming southwesterly. This will
lead to a more active weather pattern resulting in a near daily
chance for precipitation.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday Evening)
Issued at 643 PM CDT Sat May 20 2023
VFR ceilings and visibility are expected through the period. The
one fly in the ointment is whether or not near-surface smoke will
impactfully reduce visibility. Based on the latest model trends,
it appears the most impactful smoke will remain west of the
state. That said, a drop to MVFR visibility, most likely at KDIK
or KXWA, remains a possibility tonight and through the day Sunday.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...Telken
SHORT TERM...JJS
LONG TERM...JJS
AVIATION...Telken
Area Forecast Discussion
National Weather Service Denver/Boulder CO
800 PM MDT Sat May 20 2023
.UPDATE...
Issued at 754 PM MDT Sat May 20 2023
A few lingering showers and storms were over srn portions of
Lincoln county this evening but should end in the next hour
or so. Otherwise, lingering haze due to smoke will continue
overnight. Latest data suggest another surge of smoke from
Canadian fires will occur Sun aftn into Sun evening.
&&
.SHORT TERM...(This evening through Sunday)
Issued at 245 PM MDT Sat May 20 2023
Thunderstorms continue to gradually increase over the mountains,
with cloud cover limiting their progress. Little change in the
thinking on convection this evening as the current activity should
drift southeast. Storms over Rocky Mountain National Park should
struggle as they move into more stable air, but remnants could
make it off the foothills so we`ll hang on to low PoPs for that.
Given the amount of cloudiness, we could be running out of time
for strong updrafts and heavy rain. This may just turn into a big
light rain blob southwest and south of Denver in the late
afternoon and early evening.
Cloud cover will keep temps up tonight. We already raised
tonight`s lows a couple of degrees which looks fine
On Sunday, there`s very light northerly flow aloft which should
keep mountain convection from spreading eastward. We`ve got low
PoPs for areas east of Akron and Limon late in the day, but if
that happens, it`s probably not until evening. The remaining
storms should be fewer and weaker than today so even though
they`re slow moving the flood threat should be pretty low.
There`s still lots of smoke across all of eastern Colorado, so
visibilities may stay around 6 miles overnight in most areas.
We`re still hoping for some improvement around Denver from
mountain shower outflow this evening. If that does happen, we may
be able to hold on to that clean air overnight. Mixing should
continue to provide very gradual improvement overall on Sunday,
but we`ll still have noticeable smoke. Whatever`s in the Platte
valley will drift back into Denver in the afternoon as light north
winds develop.
.LONG TERM...(Sunday night through Saturday)
Issued at 245 PM MDT Sat May 20 2023
A large ridge aloft will be over the center part of the US for
the majority of the long term period. This will lead to very light
flow aloft over Colorado on Monday and Tuesday. By Wednesday and
into the latter half of next week, a trough will move onshore over
the west coast of the US. This will increase southwesterly flow
aloft and will bring in extra moisture.
Going through each day chronologically, it appears Monday will see
an increase in smoke across the plains as northeasterly winds around
700 mb will bring in the smoke from Canada. The RAP smoke model
suggests this although it is uncertain if this smoke will remain
aloft or come down to the surface. There will be decent instability
and moisture over the mountains and showers and storms will form
as a result. It appears the plains will struggle to develop
instability and the smoke will not help things become more
unstable. Therefore, the plains will stay mostly dry and the PoPs
were lowered as a result. Highs will be near normal.
Tuesday will be slightly warmer than Monday and the moisture will
increase slightly as well. This will increase instability and
showers and storms coverage will also increase as a result. The
showers and storms will favor the higher terrain again. With it
being so wet recently, the NBM has been training itself off of a
wet period. Therefore, PoPs seemed quite high over the plains
as it does not seem like there will be widespread coverage of
storms so PoPs were lowered.
The increased flow aloft will add some bulk wind shear to the
environment from Wednesday through the end of the week. This will
allow storms to become a bit stronger than previous days. However,
the 500 mb winds are never forecast to get above 30 knots in our CWA
on any day in the long term period so it will limit the bulk shear
and severe potential. Nonetheless, the CIPS analogs are very
excited about severe weather Wednesday through Saturday. The
pattern recognition for severe weather is there as southeast winds
will draw in moisture at the surface with southwest winds aloft
containing shortwaves from time to time will add lift and shear.
This type of pattern would favor hailstorms over any tornadoes or
severe wind gusts. Another result of these stronger storms will
be flash flooding in the burn areas which is discussed further
below. Otherwise, temperatures will remain near or slightly above
normal. Winds will be on the weaker side with the exception being
a gusty outflow from a thunderstorm.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 754 PM MDT Sat May 20 2023
Still dealing with some haze/smoke this evening. This will
probably continue overnight but visibility may rise above 6sm
after 04z. Another surge of smoke may occur Sun aftn with
visibility dropping to 5-6sm. Winds will switch to more SSW in
the next few hours and remain that direction overnight.
&&
.HYDROLOGY...
Issued at 245 PM MDT Sat May 20 2023
Drier air should result in less numerous and less intense
thunderstorms over the mountains on Sunday. Since storm motions
will be slow, there`s still a threat of minor burn area flooding
but the threat of anything more significant looks very low.
The long term period unfortunately looks to be quite active for
flash flooding in the recent burn areas. Storms that form Monday
and Tuesday will not be very strong but since there is very
minimal flow aloft, they will be moving very slowly. There will be
more flow aloft Wednesday through the end of the week which will
allow storms to become stronger and have heavier rain rates. This
also means they will be moving a little bit quicker than on
Monday and Tuesday. Overall, there will at least be a limited risk
of flash flooding in the recent burn areas Monday through next
weekend and there could be a few days with an elevated risk.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...RPK
SHORT TERM...Gimmestad
LONG TERM...Danielson
AVIATION...RPK
HYDROLOGY...Danielson/Gimmestad
Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
640 PM CDT Sat May 20 2023
...New AVIATION...
.SHORT TERM...
(Tonight through Sunday night)
Issued at 141 PM CDT Sat May 20 2023
Locally heavy rain, damaging winds, and hail all remain possible
this afternoon and evening as a weak cold front slides into the
region.
A strong H5 shortwave is passing overhead, which has sparked several
showers and thunderstorms across the Sierra Madre and Mexican
Plateau this afternoon. These storms are moseying east off the
terrain and forming new showers and storms along a line from just
southwest of Falfurrias to Falcon Lake as of 1:45PM CDT. The
environment is somewhat favorable for damaging winds (60+ mph) and
hail (1"+) thanks to CAPE values exceeding 2000 J/kg, mid-level
lapse rates near 7 C/km, and Downdraft CAPE (DCAPE) near 1000 J/kg
per the latest RAP analysis. As a result, the Storm Prediction
Center (SPC) has maintained a Marginal Risk (Level 1 of 5) for
Severe Weather this afternoon for most of the County Warning Area
(CWA) away from the immediate coast.
Additionally, the steering currents for these storms are quite weak,
as highlighted by the LCL-EL mean wind around 10 knots. Add in the
fact Precipitable Water values (PWATs) are generally between 1.6"
and 1.8", or above the 75th percentile for May 20th, and there`s the
potential for localized flooding. The Weather Prediction Center
(WPC) has nudged their Marginal Risk (Level 1 of 4) for Excessive
Rainfall a little east with their latest update to include all but
the immediate coast.
That`s all later this afternoon into tonight. Another H5 shortwave
is forecast to pass a little more to the northwest of the CWA than
today`s and may help spark another round of showers and
thunderstorms along the higher terrain of Mexico. With the H5
shortwave a little farther away, the H5 ridge a little stronger, and
the passage of a weak cold front tonight, rain chances are better
across our northwestern CWA. Currently, rain chances are forecast to
be 30 to 40 percent across the Rio Grande Plains and Brush Country
with a 10 to 20 percent chance for everyone else on Sunday.
Temperatures are expected to dip into the lower 70s across the CWA
tonight before rebounding into the middle to upper 80s Sunday
afternoon. A bit of clearing coupled with a weak northerly to
northeasterly breeze Sunday night should allow temperatures across
the Northern Ranchlands to sneak into the upper 60s while those
along the Rio Grande remain in the lower 70s.
&&
.LONG TERM...
(Monday through next Saturday)
Issued at 141 PM CDT Sat May 20 2023
The mid-level low works from Texas to the Southeast early this
week before pairing with a system dropping into the eastern Great
Lakes to deepen and strengthen a 500mb trough across the eastern
CONUS through next weekend. This setup should maintain a ridge of
high pressure across Texas through the long term period, finally
dulling the active severe weather pattern locally. While the NBM
and most model guidance sticks to near zero rain chances, ripples
of vorticity in the northwest flow around the mid-level ridge and
daily seabreeze boundaries may be enough to occasionally dust up a
couple of showers or storms. Drier air aloft could be a big
limiting factor. Confidence remains low, so have kept POPs below
10 percent at this time. Persistent southeasterly flow will help
warm temperatures gradually through the period.
&&
.AVIATION...
(00Z TAFS)
Issued at 629 PM CDT Sat May 20 2023
Some scattered showers and thunderstorms have mostly dissipated
across the area early this evening. Light north to northeasterly
winds and VFR conditions are expected to persist through this
evening and overnight. A weak cold front will move through on
Sunday morning, and with low to mid level moisture increasing,
MVFR ceilings are expected to develop by mid morning. Shower and
thunderstorm chances are on the low-end, along with our confidence
on timing and locations that may be impacted.
&&
.MARINE...
Issued at 141 PM CDT Sat May 20 2023
Now through Sunday Night...A weak cold front crawls into the region
tonight and will cause winds to briefly turn northerly to
northeasterly later tonight into Sunday. Winds turn more easterly to
southeasterly Sunday afternoon into Sunday night, but remain light.
Seas will generally run less than 2 feet through the period. While a
shower or thunderstorm is possible along the Lower Texas Coast, that
chances remains generally less than 20 percent.
Monday through Saturday...Light to moderate onshore southeasterly
flow is expected to continue into next weekend, with generally
favorable marine conditions across coastal waters. Seas may build
by late week due to persistent southeasterly swell, generally
remaining below 3 to 4 feet.
&&
.PRELIMINARY POINT TEMPS/POPS...
BROWNSVILLE 73 86 72 87 / 10 20 10 10
HARLINGEN 70 86 70 89 / 10 20 10 10
MCALLEN 73 87 71 89 / 50 20 10 10
RIO GRANDE CITY 71 86 71 89 / 70 20 10 10
SOUTH PADRE ISLAND 75 81 74 82 / 10 20 10 0
BAYVIEW/PORT ISABEL 73 84 72 85 / 10 20 10 10
&&
.BRO WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...None.
&&
$$
SHORT TERM...58-Reese
LONG TERM....56-Hallman
AVIATION...69-Farris
Area Forecast Discussion
National Weather Service Cheyenne WY
528 PM MDT Sat May 20 2023
.SHORT TERM...(This evening through Sunday)
Issued at 159 PM MDT Sat May 20 2023
Key Messages:
1) Limited weather impacts today with slowly increasing isolated
to scattered rain showers and isolated thunderstorms Sunday into
Monday. Most activity will be confined to the higher terrain west
of the Laramie mountain range.
2) Additional snowmelt will continue to aid runoff in the
mountains leading to localized flooding in area creeks and rivers.
Select locations are in action stage and will rise to minor flood
stage this week. See Hydrology section for more details below.
3) Temperatures will be slightly above normal today into Monday
over climate averages by 2-5F degrees. Overall, pleasant
conditions this weekend, minus the lingering smoke.
Weather Discussion: A closed, yet weak, upper-level low over
northwest to central Colorado is noted on water vapor and RAP
analysis combo panels this afternoon. Higher terrain instability
could yield a few isolated showers in the mountains west of the
Laramie Range today but a bulk of the activity will remain
farther south in Colorado where greater moisture depth exists.
Limited instability and capping across the region along with
embedded drier air will preclude rain shower development across
the High Plains today. Precipitable water amounts over SE WY are
only 0.3-0.4" and are 0.6"-0.7" farther south in CO. In addition,
areas of smoke from Canadian wildfires will linger through next
24-36 hours. Poor air quality has resulted and have issued a
special weather statement highlighting this impact. Limiting
outdoor activity for sensitive groups is advised.
The closed low will slowly open up Sunday with a shortwave trough
pivoting southeastward across the northern Plains. This pattern
will shift slightly deeper moisture farther north with PWATs
increasing to 0.4-0.6" next 24 hours. However, low-levels will
remain dry as evident by lower dewpoints in the 30s and inverted
"v" soundings. Enough moisture should be present in the high
terrain for slightly greater shower to brief weak thunderstorm
activity over the SE WY Mountains with limited coverage elsewhere.
Monday will similar to Sunday with mostly tranquil conditions
other then isolated showers/weak thunderstorms in the mountains.
Can`t fully rule out a brief isolated rain shower over the High
Plains but low-level dry air will be the nemesis of any possible
concentrated updraft with 500 J/Kg MUCAPE present. A weak H5 ridge
will occur across WY into the northern Plains ahead of a stronger
closed low shifting into the Pacific NW but remain too far away on
Monday to have sensible weather implications across SE WY/W NE.
See long term for more active period mid to late week in
conjunction to this system and influx of moisture.
.LONG TERM...(Sunday night through Saturday)
Issued at 159 PM MDT Sat May 20 2023
No major changes were made with this forecast cycle. An unsettled
pattern is expected next week with daily chances for afternoon
showers and thunderstorms. A warming trend is expected throughout
the week, with several locations seeing the 80 degree mark.
An upper-level ridge builds into the western CONUS on Tuesday and
slowly progresses easterly throughout the long term. The ridge is
being blocked by an upper-level low to the east, which is preventing
the ridge from quickly progressing easterly. An upper-level trough
builds over northern California on Tuesday and continues to
strengthen through Wednesday when it becomes well-developed.
However, this trough is progged to sit over California for several
days before slowly progressing southerly and then northeasterly
towards the CWA Friday evening. While the slow-moving upper-level
ridge sits over the central CONUS, several disturbances traverse
through the ridge and bring daily chances for showers and
thunderstorms across the CWA.
The best chances for potentially sustained, stronger convection
looks to begin on Thursday. Up until Thursday, shear is relatively
lacking across the CWA. Most days prior to Thursday only support
shear values of 10-20 or 20-30 kts. On Thursday and Friday, shear
values increase to 30-40 kts. SBCAPE values both days will be above
1000 J/kg. Coupled with stronger shear values, storms on Thursday
and Friday will likely be stronger and longer lasting than storms
from previous days. There is some uncertainty in the exact shear
values, and potential CIN values, for later in the long term, but
trends will continue to be monitored over the next several days.
Temperatures are expected to warm throughout the long term with
Saturday likely being the warmest day. However, several locations
will start seeing the 80s Tuesday with upper 80s to near-90s
possible at some locations Saturday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 524 PM MDT Sat May 20 2023
Wyoming TAFS...Smoke from wildfires will reduce visibilities to
5 miles this evening at Laramie. Only some high clouds around
15000 feet AGL will affect the terminals.
Nebraska TAFS...Smoke from wildfires will reduce visibilities to
3 to 6 miles at times through Sunday morning. Only some high
clouds around 15000 feet AGL will affect the terminals.
&&
.FIRE WEATHER...
Issued at 159 PM MDT Sat May 20 2023
Relative humidity values will drop into the low 20 to upper
teen percentiles this afternoon across Converse and Carbon
Counties. Winds will remain below criteria along with fuels
being not ready as vegetation is in full green up. Minimum
humidity will fall to the upper teens again Sunday in Carbon
County but winds will remain low. Overall fire weather impacts
will be minimal through the weekend into early next week.
Isolated to scattered light showers over the high terrain
Sunday with increased wetting rain chances early to mid week.
&&
.HYDROLOGY...
Issued at 159 PM MDT Sat May 20 2023
A warming trend this weekend into next week will increase the snow melt
runoff from the higher elevations. Rainfall from scattered afternoon
and evening showers and thunderstorms much of next week will also add
to the runoff. Minor flooding will continue along the Little
Snake River near Dixon and at Baggs, and near flood stage near
Savery until further notice. The Flood Watch remains in effect
until further notice for the North Platte River at Saratoga and
near Sinclair, forecast to rise above flood stage and approach
flood stage, respectively later next week. Water levels will
remain elevated along the Laramie and Encampment Rivers. The Mouth
of the Encampment River near Encampment will continue above
action stage for the next several days. Chances for burn scar
flooding remain low this weekend, but may increase next week with
a greater coverage of afternoon and evening showers and
thunderstorms.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...None.
&&
$$
SHORT TERM...JSA
LONG TERM...AM
AVIATION...RUBIN
FIRE WEATHER...JSA
HYDROLOGY...JSA/MAJ
Area Forecast Discussion
National Weather Service Duluth MN
631 PM CDT Sat May 20 2023
.DISCUSSION...(This evening through Friday)
Issued at 240 PM CDT Sat May 20 2023
Summary: Beautiful day out there this afternoon as a surface high
pressure retreats to the south. We will see some hazy skies
returning tonight and lingering through tomorrow due to the
wildfires in NW Canada. A cold front will drop from the north
tomorrow and could bring some sprinkles across northern MN. Better
chances for widespread rain and a few thunderstorms will return
late Tuesday through Wednesday as another cold front drops south
out of Ontario.
Surface high pressure has been retreating to the south today
allowing for westerly winds to dominate the flow across the region.
An upper level ridge over the Rockies is providing NW flow aloft and
satellite shows some of the elevated smoke from the Canadian
Wildfires intruding once again. Leaning heavily on the available RAP
guidance we have increased cloud cover across the region for the
next 52 hrs. While we maintain NW flow aloft there is an upper level
low forecasted to enter the Pacific NW to start the work week which
may disrupt the lofted smoke connection later in the forecast
period.
A cold front will be dropping out of Ontario tomorrow morning
bringing with it some cooler northeast winds. This will also allow
for the Lake breeze to expand farther inland then what was observed
today. While some ensemble members are pointing to some very light
QPF amounts associated with the front the CAMs suggest a dry
forecast. looking at the model soundings shows dry low levels as
well. A few sprinkles with virga aloft seems the most likely
scenario at this time.
The Northland will find itself between a high pressure over the
eastern Great Lakes and a Low over southern Alberta to start the
work week. This tightened pressure gradient across the region will
lead to some breezy days with winds primarily out of the south. We
will also see high temps soar into the low 80s by Tuesday, with some
cooler temps near the Lake.
Another cold front is projected to slide south out of Ontario late
Tuesday. The NBM seems to be a bit fast on the overall progression
when compared to the the Euro and GEFs ensemble suites.
Thunderstorm parameters associated with this frontal passage are not
overly exciting. Weak instability and lack of shear along and ahead
of the line will keep storms that do develop sub severe. The front
will continue it`s southward push throughout Wednesday bringing
widespread rain chances. Upper level ridging will build in for a
quiet Thursday before a warm front brings additional rain chances
for Friday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 629 PM CDT Sat May 20 2023
VFR conditions will prevail this TAF period. Light westerly gusts
to 20 knots early this evening decrease by 03Z. A lake breeze will
affect DLH tomorrow and shift winds easterly, along with any other
terminals along the shorelines.
&&
.MARINE...
Issued at 240 PM CDT Sat May 20 2023
Westerly winds continue to stream across the lake this afternoon
with speeds around 10 to 15 kts. Winds are expected to increase out
of the northeast tomorrow with building waves at the head of the
Lake. Small Craft Advisories have been issued for portions of the
nearshore waters.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 49 66 41 69 / 0 0 0 0
INL 47 70 45 81 / 0 10 0 0
BRD 47 76 48 80 / 0 0 0 0
HYR 46 74 46 78 / 0 0 0 10
ASX 48 63 39 71 / 0 0 0 0
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
LS...Small Craft Advisory from noon to 7 PM CDT Sunday for LSZ142-143-
146.
Small Craft Advisory from noon to 10 PM CDT Sunday for LSZ144-
145-150.
&&
$$
DISCUSSION...Britt
AVIATION...NLY
MARINE...Britt
Area Forecast Discussion
National Weather Service Des Moines IA
623 PM CDT Sat May 20 2023
...Updated for the 00z Aviation Discussion...
.DISCUSSION.../Tonight through Saturday/
Issued at 216 PM CDT Sat May 20 2023
Key messaging highlights:
* Warm temps just above normal through much of the period
* Mainly dry with only token slight chances Wed afternoon and
Fri/Sat west.
* Smoke aloft may return late Sun night into Monday
There isn`t a whole lot to say about the weather through next
week and this forecast cycle. Iowa will remain under weak
northwest flow with a very dry airmass in place through early
next week. This will be followed by upper level ridging building
through the MO Valley and even Canada by the middle of next week
keeping our weather generally inactive. In the short term the
only feature of note will be the current compact PV anomaly over
southern Alberta/Saskatchewan, which is expected to weaken as it
reaches the mid MO Valley Sun night. Some weak thermodynamic and
kinematic forcing will accompany its passage, but with little
sensible weather expected beyond some increase in clouds due to
very limited moisture. The surface ridge noted just to our west
per the 18z analysis will be past our forecast area by tomorrow
morning, with gradual warming into next week after one last
somewhat cool night tonight.
Smoke guidance is currently limited to the RAP runs, and the
latest extended 15Z run suggests some increase at least aloft is
likely later Sun night into Monday. There is also a weak hint that
it may reach the surface, but confidence isn`t sufficient to
mention anything in the weather element that far out.
For the middle to latter periods of next week there appears to be a
minimal potential for precipitation west starting late Wednesday,
and then again to end the week. Examination of the GEFS and EPS
median QPF and 500 J/kg CAPE percentiles remain low however so if
any precipitation does develop it would appear to be light with
only spotty coverage. There really aren`t too many forcing
mechanisms apparent with the H7/H5 ridge still overhead. The
latest NBM guidance suggests this as well with PoPs a touch lower
than the previous cycle. The primary weather story will likely
remain warm temperatures, with the latest 8 to 14 day outlook
still suggesting this will persist through the end of the month.
&&
.AVIATION.../For the 00Z TAFS through 00Z Sunday evening/
Issued at 620 PM CDT Sat May 20 2023
VFR conditions expected through the period with winds remaining
light and generally out of the southwest.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
DISCUSSION...Small
AVIATION...Jimenez
Area Forecast Discussion
National Weather Service Quad Cities IA IL
550 PM CDT Sat May 20 2023
...AVIATION UPDATE...
.SYNOPSIS...
Issued at 215 PM CDT Sat May 20 2023
Nice start to the weekend with high pressure over the Central
U.S., bringing clear skies and light winds to the local area.
Early afternoon temperatures were in the upper 60s to low 70s
across eastern Iowa and northwest Illinois.
&&
.SHORT TERM...(This evening through Sunday)
Issued at 215 PM CDT Sat May 20 2023
Quiet and cool tonight as high pressure remains over the area.
Expect light and variable winds and lows in the upper 40s to low
50s. It will be a little warmer on Sunday (mid/upper 70s) thanks
to plenty of sun and light southwest winds.
.LONG TERM...(Sunday night through Saturday)
Issued at 215 PM CDT Sat May 20 2023
Early Next Week:
Beautiful late May weather in store with highs in the low/mid 80s
and continued low humidity. Another round of elevated Canadian
wildfire smoke may overspread the area on Monday per latest runs
of the RAP integrated smoke.
Mid to Late Next Week:
A low chance for a few showers and thunderstorms Wed afternoon in
the far south as return flow moisture advection(although
currently appears marginal) looks to intercept a re-enforcing
backdoor- style front slipping southward down the western GRT LKS.
A potential temp fcst bust scenario depending on timing and speed
of southwestward push a backdoor cold front and eventual cooling
northeasterly boundary layer fetch. The NBM has loaded temps well
up in the 80s, but an earlier FROPA or east flow arrival like the
GFS and ECMWF suggest that these temps will be optimistically too
warm. Possible cloud cover with any precip may also be a warm up
potential limiter. The latest run ensembles maintain this east
fetch back from the GRT LKS and thermal profiles supportive more
of 70s for the late week period. Whatever the temp regime, it
appears mainly dry for Thursday through next Saturday. ..12..
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 550 PM CDT Sat May 20 2023
VFR conditions will prevail through the TAF period. No sig wx is
expected.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
SYNOPSIS...Uttech
SHORT TERM...Uttech
LONG TERM...Uttech/12
AVIATION...Gunkel
Area Forecast Discussion
National Weather Service Glasgow MT
751 PM MDT Sat May 20 2023
.DISCUSSION...
Evening Update:
Smoke has moved into the lower levels of the atmosphere in the
western half of the CWA. Have adjusted visibility grids lower to
match up with Great Falls and have issued a Dense Smoke Advisory
until 9am Sunday for the the western half of the CWA as well.
-Bernhart
Previous Discussion:
This afternoon, a surface low over southern Saskatchewan is moving
to the south/southeast toward the International Border and into
the CWA. This system already produced brief rain showers with
minimal thunder earlier this morning. Latest CAM models are
highlighting that there will be an increase in showers and
isolated thunderstorms, especially near Sheridan and Daniels
Counties. Latest radar imagery shows that showers north of the
Port of Scobey crossing. Increased PoPs in this area.
Behind the frontal system this morning, a clear push of smoke from
Alberta is moving down into Montana. The lowest visibility has
dropped has been slightly above 1 mile near Swift Current, SK. As
such, lowered visibilities due to smoke/haze for our CWA, which
better matches up with with Great Falls WFO has done for their
CWA. Latest RAP smoke model guidance suggests that the thickest of
the smoke/haze concentration will be in north central Montana. We
will continue to monitor this hourly and adjust the grids as
needed.
The surface low will continue to moving toward the Dakotas
tomorrow, with a 500 hPa ridge still in place. This will bring
temperatures into the upper 80s across the CWA Sunday, and into
the low 90s by Monday. ECMWF EFI Shift of Tales indicate that the
most anomalous of this warm up will be in southern Alberta, and
into north central Montana. Meanwhile on Monday, a quasi-
stationary 500 hPa low in the Gulf of Alaska will drop a trough
into the Pacific Northwest. This will change our upper level winds
more from the southwest. This pattern will push the ridge axis
towards central North Dakota and keep southwest flow for the
upcoming week. This trough will develop more into a closed low by
Tuesday, allowing disturbances to continue rounding out the low
and ejecting into the CWA with the southwest flow. Best chances
for thunderstorms will be on Monday, though some short-range
models have backed off slightly on coverage of thunderstorm in our
CWA on Monday night, with greater confidence in Great Falls` CWA.
Regardless, increased QPF can be expected for our far western
zones.
A Lake Wind Advisory will likely be needed beginning Monday night,
but will discuss with the midnight crew to determine the
appropriate valid time.
Our next greatest chance for wetting rain will be Wednesday
through Thursday for most of the CWA. SREF plumes still show low
confidence on amounts, but mainly staying under one inch for now.
Still something that will need to be monitored.
-Enriquez
&&
.AVIATION...
LAST UPDATE: 0200Z
FLIGHT CAT: MVFR-IFR
DISCUSSION: Smoke continues to move in from the
Alberta/Saskatchewan, bringing VFR conditions down to MVFR and
even IFR at times as smoke settles during the nighttime hours.
Smoke and haze should improve to MVFR or VFR by Sunday afternoon.
SFC WIND: Light and variable overnight, becoming E-SE 10kts
around noon Sunday.
-Bernhart
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...
Dense Smoke Advisory until 9 AM MDT Sunday for Central and
Southeast Phillips...Central and Southern Valley...Daniels...
Garfield...Northern Phillips...Northern Valley...Petroleum...
Southwest Phillips...Western Roosevelt.
&&
$$
weather.gov/glasgow
Area Forecast Discussion
National Weather Service Goodland KS
455 PM MDT Sat May 20 2023
.SHORT TERM...(This evening through Monday Night)
Issued at 234 PM MDT Sat May 20 2023
At the start of the short term period, the latest upper air RAP
analysis shows that the CWA has a mostly westerly flow aloft being
underneath a subtropical ridge with an upper air low over
northwestern CO. Current surface observations show dry conditions
along with some reductions in visibility in western portions due to
Canadian wildfire smoke. Going into the evening, the pattern aloft
looks to stay mostly the same for the CWA though there is a
shortwave disturbance seen to the west of the CWA. At the surface,
mostly dry conditions are expected for most of the CWA though there
is a slight chance for light showers during the evening in the
far western portions of the CWA due to the aforementioned
shortwave disturbance. The southerly surface winds seen during the
day looks to continue through the night as well. Overnight lows
expect to be in the middle 40s to lower 50s.
On Sunday, forecast guidance shows the CWA having a mostly westerly
flow aloft with an upper air ridge in the northwest, an upper air
trough to the southwest, and an upper air low over western CO.
During the evening hours, models show the CWA staying below the
split upper air flow for the rest of the day with a shortwave
disturbance seen in the flow over the southern portions of the CWA.
At the surface, most of the CWA looks to see chances of showers
and thunderstorms beginning in the afternoon and lasting into the
night with a surface trough residing in CO. Better chances look to
be in the CO and KS counties with lower chances in the NE
counties. Severe weather continues to not be anticipated with
these precipitation chances as model convective parameters do not
support it at this time. Current QPF totals look to range from a
trace to around a few tenths though locally higher amounts may be
possible as well with the latest forecast PWAT values just above 1
inch. Will continue to monitor these chances going forward.
Daytime highs look to range between the middle 70s and the lower
80s on Sunday with overnight lows being in the upper 40s to middle
50s range.
On Monday, models show both the ridge and the trough moving eastward
keeping the CWA between both features. In the evening, model
guidance shows an upper air low moving into the Pacific Northwest as
a shortwave disturbance travels through the flow over the CWA. At
the surface, models appear to show more chances for showers and
thunderstorms during the afternoon and evening hours with another
surface trough in CO. Again, chances for precipitation look to be
better in the CO and KS counties though there are still some chances
seen in NE. Once again, severe weather is not expected on Monday and
will continue to monitor this day`s potential in upcoming forecasts.
Current QPF values look to be a bit lower than Sunday`s QPF ranging
from a trace to around a tenth or two. Surface winds expect to be
out of the southeast during the day and a bit quicker than
previous days` winds with gusts up to around 20 mph. Monday`s
daytime highs look to be a bit cooler in the lower to middle 70s
due to a good amount of cloud cover inhibiting daytime heating.
Overnight low on Monday night are forecasted to be in the lower to
middle 50s range.
.LONG TERM...(Tuesday through Saturday)
Issued at 220 PM MDT Sat May 20 2023
Long range guidance indicates that a pronounced omega block --
the center (ridge) of which will be situated directly over the
central CONUS -- will prevail for the majority of the long term
period. While operational runs of the GFS/ECMWF both suggest that
shortwave energy rounding the base of an upper level trough over
the Pacific Coast and Intermountain West may gradually erode the
western periphery of the central CONUS ridge.. allowing SW-SSW
flow aloft to envelope portions of the central Rockies and adjacent
High Plains late this week into next weekend (Fri-Sun).. they
disagree w/regard to the eastern extent to which the ridge will
erode.
With the above in mind, expect predominately dry conditions and a
warming trend by mid-late week. While ridging aloft will tend to
suppress in-situ convective development.. one would expect an
increasing potential for (1) upstream development along the CO
Front Range and (2) downstream propagation into the Tri-State area
late this week into next weekend.. as SW-SSW flow aloft
overspreads the central Rockies and encroaches on the High Plains.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 455 PM MDT Sat May 20 2023
Both terminals to see mainly VFR conditions for the forecast
period. KGLD could see periods of 6sm in smoke through 03z
Sunday, but no major impacts expected.
Winds for KGLD, south-southeast around 10kts. Gusts to 20kts
possible from 07z-21z Sunday. Winds for KMCK, light/variable
through 14z Sunday, then south-southeast around 10kts.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...076
LONG TERM...Vincent
AVIATION...JN
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
625 PM CDT Sat May 20 2023
.SHORT TERM...
Issued at 227 PM CDT Sat May 20 2023
Through Sunday night...
Surface high pressure will dominate our weather through the
remainder o the weekend. This will result in dry and rather
pleasant weather through the period. Inland portions of northern
IL will see temperatures top out around 70 degrees this afternoon,
through onshore winds with a lake breeze will keep temperatures
in the upper 50s to around 60 at the lakeshore. Following a cool
and clear night tonight, we should see a similar weather day for
Sunday, albeit a bit warmer as inland temperatures climb into the
mid to upper 70s under mainly sunny skies. Light surface under the
surface high will set the stage for another lake breeze Sunday
afternoon. Onshore winds associated with this will thus result in
much cooler afternoon temperatures near the lake.
KJB
&&
.LONG TERM...
Issued at 227 PM CDT Sat May 20 2023
Monday through Saturday...
A dry and quiet weather pattern will continue through the long
term period. Inland temperatures are expected to continue on a
warming trend for Monday and Tuesday as readings likely reach into
the 80s (cooler along the lakeshore). However, by mid-week there
is strong support that a decent cold front will shift southward
down Lake Michigan late Tuesday night and across our area into
Wednesday morning. Breezy north-northwesterly winds in the wake of
the front is likely to result in trend towards a couple of days
of cooler weather (lower to mid 70s inland and around 60 along the
lakeshore) for the second half of the work week. A rather
substantial surface high then looks to shift over the Great Lakes
later in the week into at least the first portion of the upcoming
Holiday weekend. This should generally support rather quiet and
pleasant weather during the later portion of the forecast period.
KJB
&&
.AVIATION...
For the 00Z TAFs...
Only aviation weather concern through the period is timing of lake
breeze passage across ORD and MDW and associated wind shifts.
Early evening surface analysis depicts high pressure from the
Central Plains to the Mid-Mississippi Valley. Despite full
sunshine, relatively light surface winds and a nearly 20 degree
difference between air temps over Lake Michigan and inland parts
of the Chicago metro area, the lake breeze has been slow to spread
inland this afternoon and has become diffuse in radar reflectivity
across ORD over the past few hours. This has led to light wind
directions varying across O`Hare Field from north-northwest to
southeast per the different ORD runway wind sensors. Current
mosaic of LOT/TMDW/TORD radars does indicate the lake breeze
boundary is starting to shift west (at least north and south of
ORD), and latest HRRR runs also indicate lake breeze will push
west of the field in the next 1-2 hours, resulting in light east-
southeast winds for both ORD and MDW this evening.
High-res guidance continues to be in good agreement in winds then
becoming light west-southwest overnight, and light westerly on
Sunday. Decreasing westerly flow above the boundary layer should
allow for a better inland push of the lake breeze Sunday
afternoon, with a wind shift to the east expected at MDW around
20Z and at ORD around 21Z.
Otherwise, VFR conditions are expected with nearly cloudless skies
through the period.
Ratzer
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.
&&
$$
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Area Forecast Discussion
National Weather Service Morristown TN
916 PM EDT Sat May 20 2023
...New UPDATE...
.UPDATE...
Issued at 912 PM EDT Sat May 20 2023
No lightning has been observed over our area this evening, and am
removing the remaining evening thunder from the forecast with
this update. Showers are winding down on schedule from west to
east, and overall forecast looks to be in decent shape. Will tweak
hourly temps and dew points in addition to removing the thunder,
but no other changes planned at this time.
&&
.SHORT TERM...
(This evening through Sunday)
Issued at 304 PM EDT Sat May 20 2023
Key Messages:
1. Mostly showers, will continue to move across the forecast area
through this evening. Best chances for an isolated storm will be
across the extreme southern TN Valley and southwest NC.
2. Clouds clear tomorrow morning with a beautiful day
expected.
Discussion:
At the current hour, a cold front is located across the Cumberland
Plateau and will move east of our area by this evening. Showers are
currently ongoing ahead of and along the front and will continue
across our area until the front clears east. A few isolated storms
are still possible across the extreme southern TN Valley and
southwest NC late this afternoon through early evening. Partial
clearing can be seen on VIS satellite along the front across
portions of Alabama. This is where instability has developed this
afternoon and isolated to scattered showers storms are expected
over the next few hours. Currently, the southern TN Valley is on
the eastern edge of this instability gradient. The RAP on SPC`s
MESO page shows this area of instability expanding into the
Southern TN Valley over the next few hours with roughly 1000 J/kg
SBCAPE and 500 J/kg MLCAPE. Shear parameters are still on the low
end but enough shear is in place that we will have to monitor the
potential for a few strong storms. Due to marginal instability in
place, the main threat with any stronger storm would be from wind
damage. Overall, chances of any strong storms are very low across
the southern TN Valley and southwest NC.
Showers come to and end this evening when the cold front passes
east. Expect clouds to hang around through most of the night with
clearing conditions by tomorrow morning. It looks like we should
keep a decent north wind overnight so widespread fog shouldn`t be a
concern but some patchy fog is still possible. A very nice day is
expected tomorrow with lower RH, plenty of sunshine and near normal
temperatures.
&&
.LONG TERM...
(Sunday night through next Saturday)
Issued at 304 PM EDT Sat May 20 2023
Key Messages:
1. Little precip for next week, with temperatures near seasonal to
slightly above normal.
2. Possible return of an omega block pattern late in period.
Discussion:
Overall, a messy synoptic pattern throughout the extended period
with low confidence in overall evolution and development of omega
block pattern late in the period.
For Monday, Models continue to show a short-wave across the lower
Mississippi River Valley with scattered showers and possibly
thunderstorms over middle Tennessee into the Gulf Coast states. Some
of this activity may move into the Plateau and southeast Tennessee.
Overall, dry conditions. Instability is limited with MLCAPES of 500
or less.
For Tuesday and Wednesday, surface ridging into the Appalachians
with drier air advecting into the region will keep most of the
convection south of the region. Also, for Wednesday boundary layer
flow becomes more easterly producing downsloping winds into the
valley.
For Thursday, a front moves south toward the Tennessee valley.
Deterministic models are in disagreement with how much convection
can be expected with this boundary. Ensembles are relatively dry
which is probably due to the dry airmass over the region limiting
CAPE/instability.
For Friday and Saturday, a trough digs into the central and southern
Appalachian with increasing chances of mainly afternoon/evening
convection. Confidence is quite low on the overall evolution of the
synoptic pattern.
&&
.AVIATION...
(00Z TAFS)
Issued at 703 PM EDT Sat May 20 2023
Some showers and MVFR cigs around early all sites, possibly
briefly IFR, then trending to VFR TYS/CHA overnight with VFR
conditions continuing through the end of the period. At TRI,
conditions are expected to trend to VFR but fog development is
likely later tonight. The details are uncertain, but for now will
include MVFR vsby for several hours, before the fog dissipates and
VFR conditions return for the daytime hours.
&&
.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN 59 81 60 82 / 50 10 0 30
Knoxville McGhee Tyson Airport, TN 57 79 56 81 / 50 10 0 20
Oak Ridge, TN 55 79 56 82 / 30 0 0 10
Tri Cities Airport, TN 52 76 52 80 / 60 10 0 10
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...NONE.
VA...NONE.
&&
$$
SHORT TERM...
LONG TERM....DH
AVIATION...
...Updated Aviation Forecast Discussion...
.DISCUSSION...
Issued at 207 PM CDT Sat May 20 2023
Key Messages:
- Very pleasant conditions expected through this weekend, with
above-normal highs forecast into next week.
- Reasonable shower and storm chances return Thursday through
Friday night.
Today:
Few clouds interrupt a beautiful afternoon across eastern Nebraska
and southwest Iowa. Mid-level water vapor imagery depicts the system
that cooled the area down yesterday continuing its journey to the
east and slowly loosening its grip on the area. To the west, a broad
ridge continues to build with a few shortwaves found over the
Colorado Rockies, while the rest of the meaningful atmospheric
moisture staying well off to the south. Low-to-mid 70s are where we
will end up today max temperature wise with winds generally staying
at less than 10 mph out of the south. Air quality should stay on the
better side as upstream trajectories move the Canadian wildfire
smoke away from Nebraska and Iowa.
Sunday through Wednesday:
Seasonably warm temperatures dominate the rest of the forecast
period, with dry weather continuing through at least mid-week. Model
solutions across the board are in good agreement in the progression
of the broad ridge across the west to continue moving eastward over
the next few days. Highs on Sunday reach the upper 70s to low 80s,
while the remainder of the forecast sees highs squarely in the 80s.
Looking at the latest extended run of the RAP smoke fields, we
should dodge the significant smoke that we saw earlier this week,
though we will see another push of smoke overhead beginning late
Sunday (which could make for a dazzling sunsets and sunrises going
into next week).
Thursday and Friday:
By Thursday, the main upper ridge will have centered itself just to
he east of the area, leaving a diffluent flow over the area starting
from just east of the front range of the Rockies. Increasing wind
speeds aloft will try and bring shortwaves through the area for the
late work week, and could result in evening thunderstorms with
better chances for them over the western two-thirds of Nebraska.
Ensemble members also pick up on the increased forcing, resulting in
many members giving eastern Nebraska and western Iowa some kind of
moisture by next weekend. In the meantime, we`ll enjoy this early
preview of summer through the foreseeable future.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 615 PM CDT Sat May 20 2023
VFR conditions through the end of the TAF period under mostly
clear skies. Winds will remain out of the south, possibly turning
more southwesterly overnight as winds slack off. Winds will
increase again Sunday morning to around 8 to 10 kt.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...None.
IA...None.
&&
$$
DISCUSSION...Petersen
AVIATION...McCoy
Area Forecast Discussion
National Weather Service Pueblo CO
256 PM MDT Sat May 20 2023
.SHORT TERM...(This evening through Sunday)
Issued at 241 PM MDT Sat May 20 2023
Key messages:
1) Scattered showers and thunderstorms across the higher terrain and
adjacent plains this evening, then again Sunday afternoon.
2) Areas of smoke will linger across the plains and I-25 Corridor
this evening through Sunday.
Currently...Thunderstorms have developed across the high country
today, producing cloud to ground lightning, some gusts up to around
35-40 mph and pea-sized hail. Areas of smoke this morning produced
some very low visibilities across the plains, especially in El Paso
County, and though that has eased, smoke and cloud cover has slowed
the heating process across the plains which in turn slowed storm
development. As of 2 PM temps have climbed into the 50s to around
60F for the high valleys, and 60s to lower 70s for the plains.
An upper low over the CA Baja is expected to continue drawing up
moisture into the Desert SW and Four Corners through the short term.
Abundant llvl moisture and diurnal heating under weak flow aloft
will mean a shot of afternoon and evening showers and thunderstorms,
mainly tied to the higher terrain but gradually crossing the I-25
Corridor and onto the eastern plains late in the cycle.
Tonight...Scattered to numerous showers and thunderstorms currently
over the higher terrain will continue to gradually push east across
the I-25 Corridor this evening, and hi-res models paint a couple of
areas where the highest potential for storm development and heavier
rain will occur. One will be over Teller County stretching down into
northern El Paso County, and the other being along the Arkansas
River Valley stretching from Canon City east across Pueblo into
Crowley and Otero counties. If these models are correct, then those
areas will likely see periods of moderate to even heavy rain at
times from 4 PM and lasting until around 9 PM. Elsewhere, scattered
convection will continue until late tonight, and the main threat
from any of these storms will be cloud to ground lightning, wind
gusts up to around 45 mph, small hail and brief heavy rain. Another
concern is wildfire smoke from Canada, as the particulate matter in
the air latches onto llvl moisture and heightens visibility
restrictions. Visibility has improved this afternoon due to
atmospheric mixing, but as convection wanes late tonight and winds
ease up, feel that patchy fog, even dense fog, is a real
possibility. As for overnight lows, expect mid 30s to mid 40s for
the high valleys, and mid 40s to lower 50s for the plains.
Tomorrow...All indications point to a repeat for Sunday as
convection initially fires over the mts and high valleys, then
crosses on the plains by mid-afternoon. Models do point to better
CAPE tomorrow across the eastern plains, but with continued weak
bulk shear. Therefore, there should be better coverage of convection
along the I-25 Corridor and southern border during the late
afternoon and evening, but nothing is anticipated to become a severe
threat. RAP smoke models still show the intrusion of Canadian smoke
to be a problem through at least the morning hours, though the
densest smoke will be north of the Palmer Divide. Therefore, plan on
patchy smoke/haze/fog across El Paso County and northern Pueblo
County through 10 AM to noon. Look for high temps in the 70s across
the plains, and 60s to around 70F for the high valleys. Moore
.LONG TERM...(Sunday night through Saturday)
Issued at 241 PM MDT Sat May 20 2023
Models overall in good agreement through much of the extended
period, with differences late in the work week. Active weather
looks to continue, with possible severe weather chances from mid
to late week.
Sunday nigh through Tuesday...messy upper level ridging will
prevail for the first part of the work week across southern
Colorado, with several vort maxes stuck underneath. Lack of
steering flow, weak instability and deep moisture across the
region will lead to daily afternoon and evening showers and
thunderstorms. Initial development is expected over the Mountains,
with storms drifting east into the Plains by evening. Storms
should be efficient rain producers and when combined with slow
storm movements, could lead to pockets of moderate to heavy
rainfall along with an elevated risk of flash flooding, especially
in flood prone areas and burn scars. Temperatures will be warm,
with 70s to lower 80s across the region for highs, and lows mainly
in the 40s and 50s.
Wednesday through Saturday...the upper ridge is forecast to shift
eastward, with upper troughing along the west coast. This will
lead to southwesterly flow across Colorado for mid to late week.
Multiple embedded disturbances will bring continued afternoon and
evening showers and thunderstorms to the region. Instability will
be on the increase, along with better shear. Southeast, moist low
level flow is expected on the Plains. A few storms could become
strong to severe Wednesday, Thursday and Friday. Areas along the
Eastern Mountains into the I-25 corridor will see possible strong
storms Wednesday, with the focus shifting east to out near the
Kansas border for Thursday and Friday. PWAT values over an inch
and deep moisture will mean storms will be efficient rain
producers, and continued risks of flash flooding through the end
of the week.
By late week, models differ on how strong and quickly they want to
eject the upper system across the Rockies. Most guidance has it by
Saturday, with continued shower and thunderstorm chances across
the region heading into the weekend.
Temperatures will warm from mid to late week, with most of the
lower elevations seeing highs reach into the upper 70s to upper
80s. Overnight lows will remain in the 40s and 50s. Mozley
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 241 PM MDT Sat May 20 2023
Ongoing convection over the higher terrain will cross adjacent
plains through the evening. Areas of smoke from Canadian wildfires
has produced reduced vsby across portions of the I-25 Corridor and
eastern plains, and at times has combined with low T/Td spread to
produce patchy dense fog, especially across El paso County and
northern Pueblo County. Vsby is expected to likely drop again
overnight.
KCOS: VFR/MVFR conditions with vcts through 03z, then vcsh until
07z. Return of patchy fog/smoke/haze after 07z.
KPUB: VFR/MVFR conditions. vcts through 02z, then vcsh until 06z.
Return of patchy fog/smoke/haze after 09z.
KALS: MVFR/VFR conditions anticipated. vcts through 02z, then vcsh
until 07z.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...MOORE
LONG TERM...MOZLEY
AVIATION...MOORE
Area Forecast Discussion
National Weather Service Blacksburg VA
1046 PM EDT Sat May 20 2023
.SYNOPSIS...
A frontal boundary shifts east to the coast tonight. Dry high
pressure is then expected to control the weather pattern for most
of next week.
&&
.NEAR TERM /THROUGH SUNDAY/...
As of 1040 PM EDT Saturday...
Front late this evening exiting the piedmont of VA, but
stretching southwest into the NC foothills/mountains. Showers
fade overnight and removed thunder chances as airmass is stable.
Fog may become an issue as we start to clear out a bit
overnight, especially in the mountain valleys.
Previous early evening discussion...
Reduced pops and thunder chances this evening...
Latest trends have lighter showers, with limited instability.
Cannot rule out a few cloud to ground strikes east of the
mountains this evening but overall expect mainly light to at
times moderate showers.
Latest HRRR had decent handle on this trend and most will be dry
by midnight, with clouds starting to decrease in the west.
Previous discussion from early this afternoon...
Rain showers with possible thunderstorms this evening, clear
skies tomorrow...
A line of showers is approaching from the west, with some
isolated showers ahead of the front reaching the western slopes
of the Blue Ridge. The main line of showers will reach southeast
West Virginia within the next hour or two, and crossing the
area through the remainder of today and into tonight. Mostly
light to moderate rain showers are likely, with some localized
areas of heavier rain possible. Some thunderstorms are possible
within this line. The most likely area for any convective
development today will be east of the mountains, in the
Foothills and Piedmont, where clouds have cleared enough for
temperatures to warm into the low to mid 70s, helping to
generate some instability. There is plenty of moisture, with the
morning sounding at RNK showing precipitable water near 1.0
inches, and is forecast to increase through the afternoon.
However, thinking that the severe thunderstorm threat will be
limited, given the relatively modest instability and slow speed
of the line.
Rain showers will move east and out of the area by midnight
tonight, and surface high pressure will start to expand into the
area from the Midwest. This will help skies clear out, and winds
turn to the northwest. Some low and mid clouds may remain banked
against the western slopes of the mountains given the
northwesterly flow, but even those will clear around daybreak
tomorrow.
After the passage of this front, the weather will be dry through
the remainder of this forecast period.
Temperatures tonight will be in the upper 40s in the west and
upper 50s in the east. Tomorrow, expecting similar temperatures
as today, with highs in the upper 60s in the west and upper 70s
in the east.
Forecast confidence is average.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/...
As of 135 PM EDT Saturday...
Dry and seasonable temperatures...
A short wave axis moves east Sunday night. We remain in weak overall
upper level troughing while a blocking ridge over the north Atlantic
keeps the trough in place over the eastern third of the country. At
the surface, strong surface high pressure builds south from Canada
and will be the main weather-maker for several days.
Each day will be in the 70s for highs, with a chance for
temperatures around 80 for the Piedmont of VA and NC. Lows will be
seasonable and in the 40s and 50s. Skies will become cloudier
Tuesday as a weak short wave shifts south through the area, but no
rain is expected.
Confidence in the short term is high.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
As of 155 PM EDT Saturday...
Warm with periods of clouds, but rain chances may return for
Memorial Day weekend...
In the long term, a more prominent trough digs over the east coast
as the blocking ridge remains over the Atlantic. A weak backdoor
front drops into the area in the late Wednesday to Thursday time
frame, and may bring a few light showers or thunderstorms for
midweek, but it is more likely we will remain dry and just see
increasing clouds. Surface high pressure builds down once again from
Canada and remains over the area for Friday and into Saturday.
Sometime over the weekend, double-barreled upper lows may form
along the east coast as Atlantic blocking high pressure still
remains in place. Therefore the weather looks more active for
the last half of Memorial Day weekend, with an increasing
possibility of showers and thunderstorms.
Confidence in the long term is moderate to high through the work
week, with low confidence for next weekend.
&&
.AVIATION /03Z SUNDAY THROUGH THURSDAY/...
As of 723 PM EDT Saturday...
Showers will impact LYH/DAN this evening til 01-02z with sub-
VFR ceilings/vsbys. A few showers are across the mountains but
for the most part light and should not impact vsbys.
Looking at mainly VFR east of the mountains to MVFR becoming IFR
in the west. With clearing skies late think fog develops across
the west, with dense fog likely at LWB and perhaps BCB/BLF.
Could see IFR or lower cigs as well.
Dry air moving in Sunday will bring VFR area wide with north to
northeast winds under 10kts.
Forecast confidence is average on showers/vsbys/cigs this
evening and slightly above average for late tonight and well
above average after 13z Sunday for VFR.
EXTENDED AVIATION OUTLOOK...
Expect mostly dry conditions for much of the coming week as
high pressure to the north becomes the dominant weather feature
across the lower Mid-Atlantic. May see patches of morning fog,
otherwise good flying weather and VFR conditions are expected
through much of next week.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...None.
NC...None.
WV...None.
&&
$$
SYNOPSIS...WP/AS
NEAR TERM...WP/AS
SHORT TERM...SH
LONG TERM...SH
AVIATION...NF/WP/AS
Area Forecast Discussion
National Weather Service San Diego CA
214 PM PDT Sat May 20 2023
.SYNOPSIS...
Persistent low clouds will occur each night and morning across
the coast and valleys through next week, with minimal clearing for
the coast each day. Thunderstorms will be possible over the
mountains and deserts each afternoon through Monday, with the most
widespread activity occurring today. Longwave troughing returns
early next week, with cooling, a deepening marine layer and drier
conditions expected.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
Scattered thunderstorms are anticipated mainly over the San
Bernardino Mountains and High Desert area from late this afternoon
through middle evening. Activity over far Northeastern San
Bernardino continues to progress southwest towards the San
Bernardino Mountains this afternoon and we anticipate outflow from
that cluster of thunderstorms to reignite convection late this
afternoon along the upslope north portion of the mountains
including the Big Bear area.
Daytime heating will contribute to moderately conducive
conditions for updrafts but again easterly wind shear will be
difficult to combat at least with the initial convection. Thus the
best chance of showers and thunderstorms will be late afternoon
through mid- evening across the mountains. The latest HRRR is
targeting the San Bernardino Mountains and the High Desert for the
best chances, as well, and that makes sense given the better
heating and less debris cloud cover.
Good storm movement should limit torrential downpours although
some training is possible due to the persistent storm motion.
Instability is also maximized over San Bernardino County this
afternoon, with lesser indices over the Riverside Mountains, and
especially in San Diego County which was limited earlier today by
debris cloudiness from nocturnal convection ended earlier this
morning. The debris clouds could limit instability over the San
Diego County Mountains but could help to scour out some of the low
clouds near the coast as previous mornings.
Convection will die off by late this evening, certainly most
activity before midnight, with the late convection today should
preclude nocturnal convection tonight until perhaps very late in
the evening.
For Sunday afternoon and evening, remnant boundaries, diurnal
heating and persistent mid-level moisture will contribute to
another round of scattered showers and thunderstorms once again.
The chances for convection on Sunday will be very similar to
today, most likely.
Long Term Discussion:
Lesser chances for convection on Monday due to declining
instability and mid level moisture advection, with the pattern
finally shifting to a drier westerly flow for Tuesday onward. A
baggy trough will settle over SoCal for mid to late next week,
bringing a healthy onshore flow each day, but otherwise benign
weather and slightly cooler conditions for inland areas, should be
expected through the end of next week, with good continuity in
the ensemble and deterministic forecasts.
&&
.AVIATION...
202030Z...Coast/Valleys...Areas of BKN/OVC low clouds will continue
this afternoon within 5-10 miles of coast with bases 1300-1700 ft
MSL with tops to 2200 ft MSL. BKN/OVC low clouds with similar
bases/tops will spread to 10-15 miles inland 00Z-04Z Sun and
eventually through most valleys by 10Z Sun, with higher terrain
obscured at times and local VIS below 1 mile in BR/FG in the
valleys. Clearing will occur 16Z-19Z Sun except for areas of stratus
lingering within 5 miles of the coast Sun afternoon.
Mountains/Deserts...ISO-SCT TSRA will occur through 04Z Sun over the
mountains and deserts, with greatest coverage in San Bernardino
County. CB bases will be 9000-10000 ft MSL and tops to 35000 ft MSL.
Otherwise, SCT-BKN clouds at/above 10000 ft MSL will prevail with
mostly unrestricted VIS. There is a chance of TSRA in the mountains
and deserts again Sun afternoon.
&&
.MARINE...
No hazardous marine conditions are forecast through Thursday.
&&
.BEACHES...
The long-period southerly swell will continue to dissipate this
afternoon, with most surf below 6 feet. The rip current risk will
remain high this afternoon but then decrease Sunday.
&&
.SKYWARN...
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...None.
&&
$$
PUBLIC...Brotherton
AVIATION/MARINE/BEACHES...Maxwell