Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/17/23
AREA FORECAST DISCUSSION
National Weather Service Bismarck ND
950 PM CDT Sat Sep 16 2023
.UPDATE...
Issued at 950 PM CDT Sat Sep 16 2023
Little needing updating late this evening. Smoke has diminished
across central areas, although remains patchy in some western
areas. Made some minor adjustments to patchy smoke mention based
on current trends. Otherwise, cool temperatures in the east
combined with light winds could bring some patchy fog tonight.
Many of the hi-res models are starting to hint that the higher
confidence areas for this right now are in the southeast. Added
some patchy fog mention here as a result. Otherwise the forecast
remains on track.
UPDATE Issued at 640 PM CDT Sat Sep 16 2023
Minimal updates needed early this evening. CIMSS Natural Color RGB
showing remnants of smoke from northwestern ND to south central
ND. Visibilities have been mainly above 6SM, for the most part
although added in some patchy smoke through the evening. Followed
the latest HRRR guidance through Sunday morning for lingering some
patchy smoke across mainly central portions of the state. Clear
skies and an increased southerly wind should then be found for the
rest of the day Sunday, along with dry conditions. Temperatures
tonight will generally be in the 40s, limiting any frost concerns.
&&
.SHORT TERM...(This Afternoon through Sunday)
Issued at 232 PM CDT Sat Sep 16 2023
The short term period is highlighted by diminishing smoke from
distant wildfires and generally quiet weather.
Currently, western and central North Dakota is situated under
northerly flow aloft with a ridge to our west, it`s axis located
over central Montana. At the surface, high pressure is centered
over central North Dakota and the southern Canadian Prairies.
Clouds will continue to erode across the eastern half of the state
through the afternoon and a sunny sky across the west. A ribbon
of at least some near surface smoke remains over the northwest and
into portions of the central, but visibility observations have
continued to improve rapidly over the last couple of hours. These
trends seem to match up well with the most recent HRRR-Smoke model
runs, which suggest that near surface smoke should generally be
out of the area this afternoon. It isn`t out of the question that
some smoke aloft may hang around, which would manifest itself with
some hazy sunshine. However, it doesn`t appear that this haze
will impact the temperature forecast at this time with afternoon
highs ranging from the lower 60s across portions of Rolette
county, to the upper 70s over the far southwest.
Tonight should be mostly clear with lows a touch warmer than last
night, generally in the lower 40s to a few lower 50s.
The ridge axis moves into western and central North Dakota in the
morning and afternoon hours, deamplifying a bit as it moves east.
This will promote plenty of sunshine and warmer temperatures with
Sunday highs in the lower 70s east to the mid 80s west. The
Bismarck to Minot corridor should see highs in the the upper 70s
to lower 80s.
.LONG TERM...(Sunday Night through Saturday)
Issued at 232 PM CDT Sat Sep 16 2023
By Sunday night, the ridge axis will move off into Minnesota as a
shortwave trough approaches the Canadian Prairies, transitioning
us into near zonal flow aloft. Forcing will remain well north of
the International Border, but as the trough skirts the state to
the north, clouds will increase across the northern half of the
state Sunday night through Monday morning, extending down in to
the James River Valley by the afternoon hours. The 12z HRRR-Smoke
model also suggests that we could see a return of some wildfire
smoke to the northwest by Sunday night, so that will be something
to watch as we get closer.
We then turn our attention to Monday afternoon as we will likely
see our warmest and driest day of the period. Highs will generally
range from the upper 70s to mid 80s. Additionally, relative
humidity values will dip into the 18 to 25 percent range across
much of the west. Westerly winds will become quite breezy behind a
weak and dry cold front across the northwest in the afternoon
with sustained values around 20 mph or so. Thus, we could see a
few hours of near critical fire weather conditions over portions
of the northwest Monday afternoon when all is said and done.
Tuesday will be a bit cooler west and into portions of the central
behind the cold front, but we will also transition back into
southwest flow aloft as a broad western US trough starts to
approach. Precipitation chances then return to the forecast
Tuesday night and through the rest of the long term as the western
US trough continues to dig and eventually closes off around the
Great Basin region late in the week. The NBM is currently
highlighting the Thursday night into Friday time period for the
best precipitation chances but cluster analysis still shows quite
a bit of uncertainty regarding timing of the waves ejecting from
the western trough. The various global ensemble members are
struggling with how to resolve the closing off of the western
trough which is to be expected this far out. Still, it does appear
that we may move back into a somewhat active period late in the
week and potentially into the weekend with chances of showers and
possibly a few thunderstorms at times.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday Evening)
Issued at 640 PM CDT Sat Sep 16 2023
Overall look for VFR conditions, with some patchy smoke, through
the forecast period. Tonight into Sunday morning could see some
patchy smoke, possibly reducing visibility to MVFR levels.
However, based on current observations confidence was not high
enough to place these lower visibilities in the TAFs and will need
to be monitored for any amendments. Otherwise look for mainly
clear skies, with some lingering lower clouds in the east this
evening including KJMS. Light winds tonight will become southerly
with a steady light breeze tomorrow.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...Anglin
SHORT TERM...ZH
LONG TERM...ZH
AVIATION...Anglin
Area Forecast Discussion
National Weather Service El Paso Tx/Santa Teresa NM
626 PM MDT Sat Sep 16 2023
...New AVIATION...
.SYNOPSIS...
Issued at 1258 PM MDT Sat Sep 16 2023
Conditions will be somewhat active this weekend, but mostly dry
and quiet for much of next week except for on Thursday. A few
showers and thunderstorms this weekend could be strong to severe.
The temperatures will be below the normal this weekend, but will
warm to above the normal throughout next week across most of the
Borderland.
&&
.DISCUSSION...
Issued at 1258 PM MDT Sat Sep 16 2023
Currently, the skies are mostly sunny with just some clouds
developing across the mountains and a few areas mainly east of
the Rio Grande. As of now the radar does not show much
activities taking place; however, this could change in a few
hours or by the time this discussion is published courtesy of some
instability and moisture in the atmosphere. For tonight, there
maybe a few showers and thunderstorms lingering through midnight
if some of the latest hi-res CAMs verify. There are some
disagreements with the different runs of the HRRR on seeing
storms developing along outflow boundaries and across El Paso and
its surrounding areas. The hi-res NAM suggest a cluster of
thunderstorms moving up from the Chihuahua, Mexico and into the
Borderland this evening and tonight. Due to this uncertainty, a
low chance for showers and thunderstorms were introduced in the
forecast for the overnight hours. The winds will be generally
light except in and around thunderstorms and skies will be partly
to mostly cloudy. With that said, the low temperatures on Sunday
morning will be below the normal for this time of the year despite
a post frontal flow. For Sunday, an upper level ridge will be in
place and with good enough instability and bulk shear, some of
the storms that develop then will be strong to severe. The storm
coverage of Sunday will be more widespread than just being
confined to the the mountains as is expected this afternoon. These
storms will be capable of producing strong winds and hail. There
will be some rain cool air due to these storms; thus, the
temperatures will be below the normal for much of the area except
for the El Paso and the Bootheel areas.
For the rest of the period, active weather conditions will
gradually wane. For Monday, much of the thunderstorms will be
across the mountain areas. The storm parameters will be similar
to that of this weekend; thus, cannot exclude the possibility of
a few strong to severe thunderstorms mainly over the mountains
during the afternoon and evening hours. By Tuesday and during
the day on Wednesday, conditions will be dry with a trough across
the Pacific Southwest and the ridge broken down and shift to our
east. With these two systems in place, a dry southwesterly flow
will move in drying us out and limiting the storm chances across
the area. Overnight Wednesday into Thursday morning, both the GFS
and ECMWF deterministic models disagree on whether or not there
will be any storms across the Borderland. The GFS suggest a line
of storms extending from north central Mexico all the way up
through Otero County overnight Wednesday while the ECMWF suggest
no storms then. However, the ECMWF does suggest a few mountain
storms on early Thursday morning and widespread showers and
thunderstorms into the evening hours. Due to this, a low chance
for showers and thunderstorms was introduced mainly on Thursday
for much of the area. Otherwise, quiet weather is expected the
rest of the week as a trough of low pressure passes to the far
north of our area by the end of the week and early half of the
weekend. The temperatures will be above the normal for most of the
area expect for the Gila Region due to limited coverage and lack
of precipitation across much of the Borderland.
&&
.AVIATION...
(00Z TAFS)
Issued at 510 PM MDT Sat Sep 16 2023
VFR through the period for most terminals. Scattered TS give way
to low chances of storms moving over a terminal this evening until
06Z. Very low chances for TAF terminals. Activity should subside
after 06Z. Light SE/E winds after 12Z. Another round for
afternoon storms after 20Z. Low chances of storms hitting TAF
terminals.
&&
.FIRE WEATHER...
Issued at 1258 PM MDT Sat Sep 16 2023
Some moisture is in place this afternoon that will aide in a few
showers and thunderstorms through the evening hours. Tonight
recovery will be very good to excellent. For Sunday, moisture will
increase in some areas such as the Bootheel and decrease slightly
elsewhere especially in the mountains with a better chance for
showers and thunderstorms areawide. The 20ft winds will be light
and the temperatures below the normal across most of the zones.
Sunday overnight recovery will be good to very good. For Monday,
moisture will decrease significantly that will limit the storm
chances across the Borderland. The 20ft winds will continue to be
light and the temperatures above the normal in the lowlands and
vice versa in the mountains. Monday overnight recovery will be
fair to excellent. With that said, there will be no fire weather
concerns through the period across the entire zones.
The min RHs on Sunday will be between 25 and 35% in the lowlands
and 40 and 65% in the mountains. The min RHs on Monday will
decrease 3 to 10% across much of the area and vice versa along
and west of the Continental Divide. The ventilation rates will be
poor to very good for both Sunday and Monday.
&&
.PRELIMINARY POINT TEMPS/POPS...
El Paso 68 90 68 92 / 30 40 30 10
Sierra Blanca 58 82 59 84 / 30 30 30 20
Las Cruces 63 87 62 89 / 30 40 30 10
Alamogordo 60 85 60 86 / 20 30 30 20
Cloudcroft 44 62 44 64 / 20 40 20 40
Truth or Consequences 62 82 61 85 / 20 30 30 20
Silver City 58 80 57 82 / 20 30 30 30
Deming 64 87 62 90 / 30 30 30 10
Lordsburg 64 87 62 90 / 20 20 20 10
West El Paso Metro 68 89 68 91 / 30 40 30 10
Dell City 61 86 61 88 / 20 20 20 20
Fort Hancock 62 90 64 92 / 30 40 30 20
Loma Linda 59 82 61 83 / 20 30 30 20
Fabens 64 89 66 91 / 30 30 30 10
Santa Teresa 64 87 64 89 / 30 40 30 10
White Sands HQ 64 87 64 89 / 30 40 40 20
Jornada Range 62 85 62 87 / 30 40 40 20
Hatch 63 87 61 90 / 30 40 40 30
Columbus 65 87 64 90 / 30 30 30 0
Orogrande 61 85 61 86 / 20 30 30 20
Mayhill 49 72 49 76 / 20 30 20 40
Mescalero 47 72 49 75 / 20 40 30 40
Timberon 47 71 47 74 / 20 30 20 30
Winston 53 75 52 77 / 20 30 30 40
Hillsboro 58 83 57 86 / 30 40 30 30
Spaceport 61 83 59 86 / 30 40 30 30
Lake Roberts 51 78 50 80 / 20 40 30 40
Hurley 60 84 59 86 / 20 20 20 20
Cliff 55 88 54 90 / 10 30 10 10
Mule Creek 58 83 57 84 / 10 30 20 10
Faywood 61 83 60 85 / 20 30 30 30
Animas 62 88 59 90 / 20 10 20 10
Hachita 62 87 60 90 / 20 20 20 10
Antelope Wells 61 88 60 91 / 20 10 10 0
Cloverdale 60 84 59 85 / 10 10 10 0
&&
.EPZ WATCHES/WARNINGS/ADVISORIES...
TX...None.
NM...None.
&&
$$
FORECASTER...31-Dhuyvetter
Area Forecast Discussion
National Weather Service Goodland KS
1004 PM MDT Sat Sep 16 2023
.SHORT TERM...(This evening through Monday)
Issued at 113 PM MDT Sat Sep 16 2023
Ridging across the Inter-Mountain west is present aloft as a low
pressure system is present over the Midwest. As a result the Tri-
State area remains in NW flow aloft. Visible satellite imagery
does show some smoke aloft over eastern portions of the Dakotas
and working its way into eastern Nebraska. Looking at the HRRR
smoke guidance some may try to work its way into eastern portions
of the CWA around sunset. The concentration of smoke doesn`t
appear to be as unhealthy as a few weeks ago but may be enough to
be noticeable at sunset with a haze. Tonight, a backdoor cold
front moves into the the northeast portion of the area allowing
for light and variable winds to develop. Not seeing seeing any
hints of fog at this time as it looks to be relatively a bit drier
air moving in. This along with clear skies would support
overnight lows to be cooler along and east of the front
especially due to radiational cooling so went ahead and went with
cooler guidance over the east.
Not much to talk about for Sunday other than another warm and dry
day across the area as the ridge moves a bit further east over
the Plains. High temperatures in the upper 70s near the Palmer
Divide to the mid 80s over the east are forecast. Overall sunny
conditions are expected with mid to high clouds moving off of the
Rockies during the late afternoon and evening hours in part to a
shortwave affecting the mountain range. With the increased cloud
cover into Monday morning low temperatures look to be a bit warmer
than the past few days in the 50s.
Warm temperatures again on Monday, will be watching for a chance of
showers and storms to develop across portions of the area during the
afternoon and early evening hours. A surface convergence boundary
looks to be present across the area, along with a subtle shortwave
within the mean flow during the afternoon. 12Z runs of the RRFS and
NAMNEST support a line of storms developing along the boundary
during the afternoon and evening hours. Additional pops support
from the SREF, CONSALL and CONSRAW allowed enough confidence to
stray from the Day 3 NBM and introduce pops into the forecast. GFS
soundings show 1100-1500 j/kg of MUCAPE, DCAPE greater than 1100
j/kg and effective shear around 25-30 knots, and Lapse Rates 8-8.5
c/km would support at least some potential for severe weather to
occur in the form of large hail and damaging winds.
.LONG TERM...(Tuesday through Saturday)
Issued at 127 PM MDT Sat Sep 16 2023
Main focus for this part of the forecast is the potential for severe
weather toward the end of next week into the following weekend.
This part of the forecast will start out rather tranquil. An upper
level ridge will strengthen over the Central Plains as a closed
upper level low deepens over the Pacific Northwest. The deepening
closed low is not anticipated to move much during the workweek.
Downstream of it a minor upper level short wave troughs will move
through the flow over the Central High Plains during the latter half
of the week. These may lead to some rain activity for the northern
and eastern part of the forecast area. The most of the GEFS
ensemble members have the forecast area dry for this part of the
week.
Friday the closed low is forecast to begin moving eastward. As it
does so the trough accompanying it will sweep through the Plains,
forming a dry line. At this time the setup is rather good for
severe weather to occur somewhere on the Plains along/east of the
dry line.
Saturday there could be lingering upper level short wave troughs
that move through the forecast area before the trough axis moves
through. If the closed low is forecast to be this strong, am
doubtful there will be any lingering rainfall behind the dry line
from Friday due to the drier, more stable environment in place.
Am highly skeptical the current forecast for the closed low is slow
enough. Models are almost always too fast with a closed low,
especially a week out. Am thinking a more likely timeframe for
rainfall will be early the following week (the start of the last
full week of the month). Am also highly skeptical the current dry
line position will hold. Am thinking the dry line will more than
likely be east of the forecast area when it sets up since the closed
low is over the Northern Plains, well north of the forecast area.
Regarding temperatures, the forecast highs for the end of the week
may be too cool if the closed low does form as the GFS and ECMWF
show.
If the closed low does form as currently forecast, the forecast area
will be under the subsidence of the storm system. There may be some
isolated storms along the dry line. However the larger impact will
be the potential for critical fire weather conditions over the
forecast area.
&&
.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1000 PM MDT Sat Sep 16 2023
..Optimal Aviation Weather..
VFR conditions /clear skies/ will rule through the TAF period at
both terminals. Light and variable winds will prevail through
mid-late Sunday morning.. becoming southerly (S to SW) and
increasing (slightly) to 8-13 knots during the late morning and
afternoon.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...Trigg
LONG TERM...JTL
AVIATION...Vincent
Area Forecast Discussion
National Weather Service Green Bay WI
957 PM CDT Sat Sep 16 2023
Updated aviation portion for 06Z TAF issuance
.SHORT TERM...Tonight and Sunday
Issued at 243 PM CDT Sat Sep 16 2023
The latest RAP analysis and satellite/radar imagery show a compact
shortwave moving east across southeast Minnesota and northeast
Iowa. This shortwave is pushing a weak cold front across northeast
Wisconsin. This front has been inactive across northeast
Wisconsin (further displaced from the shortwave), but isolated
showers and storms have been developing at times over southeast
Minnesota and southwest Wisconsin so far today. Meanwhile, strato-
cu has been pushing into north-central Wisconsin in a cold
advection regime beneath an upper trough. Forecast concerns mainly
revolve around thunderstorm potential this afternoon and evening
along the cold front.
Fronts & Pressures: The shortwave will continue to move east-
southeast across southern Wisconsin and push the cold front across
the rest of northeast WI by mid to late evening. Meanwhile, a
Canadian high pressure system will build into the region from the
northwest late tonight into Sunday.
Sky and Precip: With increasing instability, the chance of showers
and a few storms will increase through late afternoon, mainly
south of a Wisconsin Rapids to Kewaunee line. Both the HRRR and
the RAP show anywhere from 300-800 j/kg of mixed layer instability
developing later this afternoon with convective allowing models
indicating chances for small clusters of showers and storms
peaking between about 4-9 pm. Forecast soundings indicate a
relatively skinny cape profile, but with low wet-bulb zero heights
and inverted V soundings in the boundary layer, could see small
hail and brief gusty winds to 30 mph develop in the stronger
storms. These showers and storms should be decreasing in
intensity by late evening before tapering off over east- central
WI overnight.
Low level winds will turn to the north behind the front tonight
with conditions becoming unstable over Lake Superior. With ample
cloud cover and low dewpoint depressions upstream, think cloud
cover will generally increase through the night after a
period of clearing skies this evening.
North flow and steep low level lapse rates will promote scattered
to broken cloud cover on Sunday, but no precip is expected.
Temps: Think clouds and winds will keep temps slightly higher than
the NationalBlend tonight. North winds and clouds will support
cooler temps on Sunday, with highs ranging from the upper 50s to
upper 60s.
.LONG TERM...Sunday Night Through Saturday
Issued at 243 PM CDT Sat Sep 16 2023
High pressure will be situated across the region Sunday night into
Monday. Areas of dense fog may form over north central and parts
of far northeast WI late Sunday night, and continue to impact
travel for the early Monday morning commute. Cool temperatures are
also expected, with lows in the middle 30s in north central WI
leading to patchy frost concerns overnight.
The high will shift east Monday night into Tuesday, with
developing south flow resulting in a gradual warmup into the
midweek period. Above normal temperatures are anticipated for the
mid to late part of the week.
Precipitation chances are a bit nebulous at this time, so didn`t
stray away from the model blended forecast. Warm air advection and
a short-wave trough may bring a chance of showers late Monday
night into Tuesday night, but amounts look to be on the light
side. A building upper level ridge should result in a drier period
Wednesday into Thursday, but the GFS shows a weak upper low
drifting north through the region, along with some showers. The
ridge may break down over the northwest part of the area later
in the week, with southwest flow leading to a chance of showers
and storms in north central WI later in the week. Even so, it
appears the more significant rains will stay well west and north
of the forecast area.
&&
.AVIATION...for 06Z TAF Issuance
Issued at 957 PM CDT Sat Sep 16 2023
VFR conditions prevailed at the TAF sites this evening with
mainly mid and high clouds pushing across the area, with most of
the showers/sprinkles coming to an end.
Look for a few sprinkles and showers to linger, mainly over far
eastern WI, into the late evening, as an upper level disturbance
and associated cold front exit the region. A mix of mainly mid and
upper clouds will continue through the TAF period, with a period
of clearing expected to push from north to south later tonight
into Sunday morning. But north winds flowing over Lake Superior
look to generate some clouds later tonight and on Sunday across
far northern WI. Some lower (mainly MVFR) clouds possible at
times, mainly with these lake clouds. Some patchy fog will be
possible over north central WI (RHI) later tonight into early
Sunday, especially if the lake clouds are slower to arrive.
Daytime cu is also expected on Sunday. Can`t rule out a brief
light shower or sprinkle, mainly over northern WI, as well. Fog is
possible Sunday night, especially after 06z, if we can avoid the
stratus.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM.....MPC
LONG TERM......Kieckbusch
AVIATION.......Bersch
Area Forecast Discussion
National Weather Service Grand Rapids MI
930 PM EDT Sat Sep 16 2023
LATEST UPDATE...
Update
.UPDATE...
Issued at 930 PM EDT Sat Sep 16 2023
Have increased precipitation chances overnight based on guidance
and radar trends. An axis of thunderstorms extends from eastern
IA to just south of Milwaukee with evidence of a weak mesolow over
Milwaukee, and we are beginning to see intra-cloud flashes over
mid-lake west of Muskegon. Local VAD Wind profilers indicate a deep
surface layer //greater than 2km// of convergence associated with
the boundary on which thunderstorms have developed. Recent HRRR
runs are supportive of this convection stretching eastward into
the forecast area in the midnight time frame. Precipitation
accumulations should be on the light side, areally averaging a
few hundredths of an inch, but locally could reach a tenth of an
inch or more.
Following up on the marine discussion below, have introduced a
slight chance for waterspouts starting 8 AM Sunday.
&&
.SHORT TERM...(This evening through Sunday night)
Issued at 348 PM EDT Sat Sep 16 2023
The radar is currently showing some low topped isolated convection
across the northwest zones in area of weak instability well ahead
of the surface cold front which is back in central Wisconsin.
LAPs soundings still show a dry wedge below 700 mb to be overcome
but continued low level moisture advection overnight should
result in increased coverage of measurable precip along and ahead
of the cold front by late tonight into Sunday morning.
The sharp upper trough axis arrives on Sunday morning with
sufficient instability for at least isolated thunder across the
southern half of the forecast area. Highest POPs will also be
across the southern zones where deeper moisture and better lift
associated with vort max at the base of the trough will be
located.
The showers will be departing eastern zones by Sunday evening
with thin stratus deck drying and subsidence beginning to break up
the lingering stratus on Sunday night.
.LONG TERM...(Monday through Saturday)
Issued at 348 PM EDT Sat Sep 16 2023
The long term period begins Monday with West Michigan in a northwest
flow pattern associated with the exit of a shortwave that brings
showers in the short term period. Upper level flow then transitions
to zonal mid next week before upper-level ridging builds in for the
late portion of the long term period. Given this, as well as the
surface high pressure that will be in place for much of the time
period, am expecting Monday through Thursday Night to remain dry.
Predictability is a bit lower Friday and Friday night as there is
notable spread in both 500 mb flow patterns, affecting degree of
upper level forcing, and associated precipitation forecasts in
deterministic and ensemble guidance. There are some GEFS/EPS members
that bring precipitation associated with a shortwave driving a cold
front through the area during this timeframe. This weak signal is
leading to low (aob 20 percent) pops in the Friday and Friday night
timeframe in our official forecast due to some of these members
being included in out model blends. GFS 12z run has trended westward
with the shortwave forecasted to move through the area, keeping
lower Michigan away from upper-level forcing and in 500 mb ridging
Friday supporting a dry forecast. This aligns with continued
thinking that the ECMWF solution of continued ridging into the
weekend is the likely pattern. These pops could continue to fall in
coming updates if model trends continue towards the ECMWF/GEM
solution keeping ridging in place.
A warming trend is also expected in the long term period as 850 mb
temps warm from 5-8C Monday to the teens Celsius by late week. This
supports surface temperatures warming from the mid to upper 60s
Monday to near 80 by late week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 735 PM EDT Sat Sep 16 2023
This is still a relatively lower confidence forecast for
prevailing ceilings/visibility and rain shower potential, as there
could be a few showers which develop overnight and Sunday which
could produce temporary IFR. Outside of showers, VFR should be
fairly common, though various short-term models indicate some
potential for lower ceilings around LDM/RQB/MOP. Prior to 12 Z,
there is a potential for isolated heavier shower or thunderstorm
developing near and west of a MKG-GRR-AZO line, though potential
is too low for now to explicitly put into the TAFs. Any showers
that develop over Lake Michigan tonight could produce waterspouts.
&&
.MARINE...
Issued at 348 PM EDT Sat Sep 16 2023
Cold front moving through early Sunday will switch winds from
southwest to north during the morning. Waves will build to 2 to 4
feet in the afternoon. Conditions are marginal for waterspouts to
form on Sunday across the southern half of Lake Michigan. Fair and
mostly tranquil winds and waves are expected for early next week.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...None.
&&
$$
UPDATE...TJT
SHORT TERM...Ostuno
LONG TERM...Ostuno
AVIATION...CAS
MARINE...Ostuno
Area Forecast Discussion...Updated
National Weather Service Lincoln IL
921 PM CDT Sat Sep 16 2023
.SYNOPSIS...
Issued at 921 PM CDT Sat Sep 16 2023
Scattered showers with isolated thunder may persist through the
overnight hours. Patchy fog is possible overnight, primarily west
of I-57. There is a chance for additional showers and storms east
of I-55 on Sunday. High temperatures remain in the 70s through
Monday, then warm into the low 80s for the rest of the work week.
&&
.UPDATE...
Issued at 921 PM CDT Sat Sep 16 2023
Showers and isolated thunderstorms currently from around Wenona
south to near Shelbyville should continue on their weakening trend
as they move into an area of lesser MUCAPE farther east. Outflow
well out ahead of the showers, as well as surface obs, indicate
that westerly wind gusts have come down substantially following a
few ~40 mph wind gusts late this afternoon west of the Illinois
River. Meager instability should keep thunder isolated at best
overnight, but with a 500 mb short wave trough moving out of Iowa
into northern Illinois we may continue to see shower activity
mainly east of I-55 overnight, and precip chances have been
adjusted for this idea.
Fog potential continues to be somewhat uncertain overnight, with
large areas having received rain this evening east of I-55 and
relatively light winds but with some question as to the extent to
which we will clear out. HRRR forecasts show some transient areas
with low visibility, and NBM probabilities for visibility < 5 mi
are around 20-30%. We`ve maintained a mention of fog mainly west
of I-57 where shower coverage will be minimal.
AAT
&&
.DISCUSSION...
Issued at 240 PM CDT Sat Sep 16 2023
---------- Key Messages ------------
1. Scattered thunderstorms, a few strong, are likely (40-60%
chance) this evening, mainly west of the Illinois River.
2. Patchy fog is possible tonight, especially in areas where
clearing occurs, which is more likely west of I-55.
3. Scattered showers and thunderstorms are possible (30-50%
chance) on Sunday. Conditions appear favorable for cold air
funnels.
4. Warmer temperatures are expected after Monday, with highs in
the low 80s. A few precip chances will exist throughout the week,
primarily west of I-55, but much of the work week should be dry.
------------------------------------
A cold front continues to approach the region from the northwest,
and was draped from eastern WI through east-central IA into
northern MO as of 2pm/19z. Thunderstorms have already developed
along the cold front, while vis satellite imagery shows an
agitated Cu field present between the developing thunderstorms and
the cloud shield/stable air currently over central IL.
Additionally, an east- west band of t-storms is bubbling roughly
between St. Joseph, MO, and Quincy, IL, with the satellite
appearance suggesting differential heating is playing a role in
this development. These storms are not captured well in recent
high-res guidance, so while I`m confident the primary line of
storms along the front won`t reach the ILX CWA until around
6pm/23z, I kept a chance of rain/storms present in the grids this
afternoon due to uncertainty around this new development
preceding the front.
In terms of the environment, air within the ILX CWA remains stable
due to cloud cover and a band of light rain (currently located
just east of the IL River Valley). However, RAP mesoanalysis shows
the upstream airmass is unstable, with around 1000 J/kg of
MLCAPE, and the vis satellite appearance certainly supports the
notion that instability is present. Deep layer shear values are
weak, though, so persistent severe storms are unlikely. The main
concern is a stronger updraft or two that could briefly produce
hail or strong wind gusts. Similar to yesterday, the HREF signal
for any stronger storms is primarily focused west of the ILX
CWA, with the storms expected to lose steam as the sunsets, which
will be around the time they`re moving into the ILX CWA. The
threat of strong/severe storms will diminish quickly after
8pm/01z.
As the front progresses through the area tonight, one concern is
the potential for fog. Earlier this morning, a corridor of dense
fog developed across KS/NE/IA behind the front where clearing
occurred. Fog development will likely follow a similar evolution
tonight, with it being most likely in areas that receive rain
today and have clouds clear out overnight. Those criteria are most
likely to be met west of I-55. Dense fog can`t be ruled out, but
with questions about how much clearing occurs, the scattered
nature of rain today, and light, but not calm, winds overnight in
the presence of the weak sfc low, there`s not enough confidence to
issue any products related to the fog. Additionally, high-res
guidance such as the HRRR doesn`t have a strong signal for fog at
this point. Still, will need to keep a close eye on the cloud
cover evolution overnight.
On Sunday, the upper trough/vort max digs through IL. High-res
guidance is rather limited in shower/storm coverage on Sun, but
forecast soundings still show modest, uncapped instability
developing, and with forcing from the upper low isolated to
scattered shower development should occur. This setup still
appears supportive of cold air funnels during the early stages of
shower development, thanks to the combination of cold temps aloft
(as cold as -19 degC at 500mb) and spin from the upper low. Cloud
cover should remain fairly prevalent across eastern IL, confining
highs to the low 70s as opposed to mid-70s across west-central IL.
The start of next week continues to appear dry, as a weak,
elongated sfc high pressure will be positioned over the Midwest
on Monday. A warm front lifts across the area into Tues, boosting
highs into the low 80s for the rest of the work week, but guidance
continues to show any precip associated with that front occurring
north of the area. On Tues, the upper flow across the heart of
the CONUS is temporarily zonal, but a subtle disturbance leads to
a shortwave developing by Wed. While this wave appears set to
produce precip to our west, forecast soundings show considerable
dry air present below 10kft which should largely limit precip
across our area. Deterministic models are starting to come into
better agreement that a closed upper low will meander over the
Pacific Northwest during the latter half of next week, but
uncertainty remains as to when exactly that wave kicks out onto
the Plains (sometime after Friday) and how it evolves from there.
In summary, while some low-end rain chances are present west of
I-55 during the work week, the majority of the work week looks dry
based on current guidance.
Erwin
&&
.AVIATION... (For the 00z TAFs through 00z Sunday Evening)
Issued at 653 PM CDT Sat Sep 16 2023
A line of weakening showers and thunderstorms will shift winds to
westerly as it progresses eastward this evening. Wind speeds
should weaken and lightning coverage/frequency should go down with
time/eastward extent as well. Lightning threat should become quite
low by around 03z. Visibility associated with fog after 06-08z is
somewhat uncertain, with MVFR-IFR range most likely. Largely VFR
conditions are anticipated after 15z Sunday, but some
shower/thunderstorm redevelopment may occur in eastern Illinois
(40-50% chance).
AAT
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Area Forecast Discussion
National Weather Service Indianapolis IN
921 PM EDT Sat Sep 16 2023
.Forecast Update...
Issued at 921 PM EDT Sat Sep 16 2023
- Cloudy overnight
- Sprinkles possible
Surface analysis this evening shows a broad trough of low pressure
stretching from MI, across northern IL to Central MO. This poorly
organized trough was providing weak cyclonic flow across Indiana.
Aloft the upper pattern showed strong ridging in place over the
Rockies with a deep trough in place over the Great Lakes and middle
Mississippi Valley. GOES16 shows extensive cloud cover across
Indiana and Illinois along and ahead of the weak surface low. Radar
showed a few light showers across the area in the past few hours
that have since dissipated. Stronger, more organized, precipitation
was found over western and central IL. Dew point depressions across
the area were still about 10-14F, indicating dry air within the
lower levels.
Overnight the surface low is expected to slowly drift east, but
little in the way of additional forcing looks to be present. With
dry air remaining within the lower levels, confidence for measurable
precipitation is low. HRRR does bring the more organized precip
across Central Indiana after 06Z, but it is suggested to diminish
upon approach. Propagation would suggest best areas to receive rain
would be the northern parts of the forecast area, hence will keep
best pops at those locations. Otherwise, most areas can expect to
remain cloudy overnight with a sprinkle possible.
Given the expected clouds and minimal temperature advection, will
trend lows toward the upper 50s to near 60.
&&
.Short Term...(This evening through Sunday)
Issued at 251 PM EDT Sat Sep 16 2023
A digging northern stream wave will phase with the southern stream
resulting in a broad trough slowly transitioning across our region
through the short term period. Modest moisture return into the
region is ongoing, first in the mid-high levels. Some non-measurable
"sprinkles" may occur through the rest of the afternoon as this
moisture interacts with a lead vorticity maxima. The deeper moisture
conveyor belt will be focused to our east, along the Appalachians,
into the Mid-Atlantic region. The combination of moisture and ascent
should be enough for some light precipitation in Indiana late today
lasting through Sunday.
HREF mean QPF is generally 0.10-0.25" through this period with some
very localized ~1.00" amounts where convection occurs. The window
for convection and locally higher amounts seems confined to the
Sunday afternoon time period when the combination of midlevel
cooling and low level heating of a relatively moist PBL results in a
small amount of instability. Forcing near the center of midlevel low
would focus the convective development, hence the potential for
locally enhanced rates. Instability/shear parameter space will not
favor severe convection.
Temperatures tonight will be warmer than previous nights since
clouds will limit the radiative component. Shallow patchy fog
observed the last few mornings is also less likely. Clouds and
precipitation coverage will regulate temperatures somewhat tomorrow,
keeping us in the 5-10 degree below climo range.
&&
.Long Term...(Sunday night through Saturday)
Issued at 251 PM EDT Sat Sep 16 2023
* Quiet, dry, and pleasant weather returns through this week and
potentially beyond.
In the wake of a departing upper level trough, surface and upper
level ridging will gradually reestablish control over the region,
leading to dry and pleasant weather throughout the week.
After a slightly cooler start to the work week in the wake of the
trough, height rises as the aforementioned ridging builds and a
gradual return of southerly low level flow will allow temperatures
to warm a bit over last week, with highs by mid week generally in
the upper 70s to low 80s. These numbers will then likely persist
through the period.
Any significant weather makers as the period wears on appear likely
to remain west and southeast of the region, with a large closed low
likely to very slowly pivot through the western CONUS into the
northwest or north central portion of the country, with a possible
tropical low developing near the Gulf or southeastern coasts,
depending upon the model of choice, leaving the area sandwiched
between these areas and remaining under the influence of the ridge.
Moisture return will be essentially nil with the Gulf closed off by
the broad surface high, particularly early in the period, leading to
comfortable dewpoints/humidity, and perhaps a couple of days where
fire weather concerns may need a glance, although winds appear
likely to remain modest enough to prevent significant issues. Given
the very dry ground and continued dry ground (even with some light
rain possible in the short term), have blended in some NBM 10th
percentile to account for what are likely some overdone dewpoints
throughout the period.
There appears to be little to no opportunity for substantive
precipitation in the next week to ten days if not beyond.
&&
.Aviation...(00Z TAF Issuance)
Issued at 616 PM EDT Sat Sep 16 2023
Impacts:
* Mainly VFR Conditions are expected this TAF Period
Discussion:
A weak area of low pressure along with an associated upper trough
will push across Central Indiana during the TAF period. Lower level
moisture remains rather inhibited, thus only VFR Clouds will be
expected.
HRRR shows minimal coverage and progression of the ongoing showers
upstream of the TAF over IL. Thus with this poor organization, only
a VCSH for some sprinkles will be used through 12Z.
Better chances for more organized precip is expected after 12Z as
the surface low and upper trough axis arrive over Central Indiana.
HRRR suggests an area of showers pushing across Central Indiana, but
timing and confidence too low for a prevailing mention. Brief MVFR
Cigs will be possible after 12Z as the previously discussed features
arrive.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Update...Puma
Short Term...BRB
Long Term...Nield
Aviation...Puma
Area Forecast Discussion
National Weather Service Northern Indiana
720 PM EDT Sat Sep 16 2023
.SYNOPSIS...
Issued at 239 PM EDT Sat Sep 16 2023
Today`s mild temperatures and dry weather give way to cooler
temperatures and a few showers on Sunday. Temperatures trend
warmer as we head into the work week, reaching the upper 70s to
around 80 degrees at times, but dry weather resumes again.
&&
.SHORT TERM...(This Evening through Sunday)
Issued at 239 PM EDT Sat Sep 16 2023
An upper trough and associated mid level energy swing through the
area between this evening and Sunday. RAP model time-sections
indicate plenty of low level dryness will need to be overcome before
wetting rains can occur so will hold off PoPs into tonight. Some
thunderstorms may be possible over Lake Michigan (where the better
moisture resides) tonight into Sunday, but this may struggle to work
inland due to a limited moisture column as well as cloudiness
limiting instability formation.
The previous few nights have seen lows drop back into the 40s with
the dry air around minimal cloud cover overnight. With dew points
now ranging through the 50s for tonight and expanded cloud cover,
this will keep overnight lows in the 50s across the area. Cloud
cover and times of rain provides a ceiling to our temperature
forecast Sunday, limiting temperatures to the upper 60s and lows
70s. A few breaks in the cloudiness may be possible south of US-24,
where the better chance to see lows 70 lies.&&
&&
.LONG TERM...(Sunday Night through Saturday)
Issued at 239 PM EDT Sat Sep 16 2023
As the aforementioned upper trough traverses east, cooling northwest
upper flow keeps temperatures below average for this time of year on
Monday, still in the upper 60s to low 70s. There is some question
about cloud cover where the upper coolness may be able to create
instability and the normally moist NAM pops a few showers in front
of a final shortwave moving through. Within this extended dry period
will hedge towards silent PoPs for now.
Tuesday, a warm front approaches and both the NAM and the ECMWF pump
out a few showers in Lake MI-adjacent locales. Am still skeptical of
this solution, though, with 40 degree dew points across the area
into the afternoon. As such, will hold onto the silent PoPs there.
Models do transition the upper trough to ridging between later
Monday and Wednesday night as high pressure goes through and heights
build. Model agreement breaks down late week into the weekend as the
tendency for height falls begins in the Gulf of Mexico/Western
Atlantic area. Hard to see PoPs across the area within that kind of
a developing pattern and its potential wave train placement.
Temperatures do look to trend warmer behind the aforementioned warm
frontal passage, reaching the upper 70s to around 80 degrees Tuesday
or Wednesday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday Evening)
Issued at 720 PM EDT Sat Sep 16 2023
Primarily VFR conditions expected to persist this period given
continued low level dry air and very limited moisture advection.
Upstream convection over IL is expected to dissipate before
reaching our area given the loss of diurnal heating and dry/stable
conditions locally. A stray shower is possible at KSBN around 06Z
but the potential for impacts are very low and will therefore
leave out any mention. Better chance for showers arrives later
Sunday morning as mid/upper trough approaches. Isolated thunder is
possible but chances are too low to mention at this range. Similar
story for KFWA but with a later arrival. Very poor moisture return
will limit potential for MVFR ceilings through Sunday evening.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
&&
$$
SYNOPSIS...Roller
SHORT TERM...Roller
LONG TERM...Roller
AVIATION...AGD
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Area Forecast Discussion
National Weather Service Seattle WA
849 PM PDT Sat Sep 16 2023
.UPDATE...Increasing clouds this evening will continue into Sunday
morning, along with increasing stratus for some of the area due to
onshore flow. Have included haze into the forecast through tonight
into portions of the northern Puget Sound and northern Olympics
due to fires in the Olympics. Clouds will clear for some sunshine
Sunday afternoon and cooler temperatures into the 60s and 70s.
&&
.SYNOPSIS...Upper ridging will continue to slide east into Sunday.
Onshore flow will increase into early next week with a few frontal
systems clipping the area into midweek. Temperatures will further
cool with these systems with the potential for showers around
through midweek.
&&
.SHORT TERM /TONIGHT THROUGH TUESDAY/...Elevated fire weather
conditions will linger throughout the afternoon as the ridge
continues to influence the region despite its eastward drift.
Extra attention has been paid to the relative humidity forecast in
the Olympics and Cascades, as observation sites have yielded RH
values in the upper teens to low 20 percent ranges throughout the
day today. It has been noted that the NBM has struggled with
relative humidity values coming in too high. As such, a blend of
the HRRR and UW WRF were utilized to bring the percentages this
afternoon back down closer to what has been observed by crews
tending to fires in both mountain ranges. There will likely be
some smoke and haze in the air through the afternoon, but it is
going to stay aloft and have little to no impact on surface air
quality.
By Sunday, with the ridge more to the east, the door will be open
for some weak frontal systems to move into the area. The first
will arrive early in the afternoon on Sunday and bring the best
chances for light precipitation to the coast and northern parts of
the CWA. Isolated shower activity is possible throughout the rest
of Puget Sound. Both Sunday and Monday will be characterized by
cooler, cloudier conditions with isolated potential for rain.
Another slightly more robust frontal system is poised to move in
from the north on Tuesday. By Tuesday afternoon, there is a
stronger signal for a wetting rain, a quarter of an inch, in the
and central WA Cascades. This would be a welcome change for crews
fighting ongoing fires in the areas.
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...While the pattern will
be changing and there is still some degree of uncertainty on
exactly how late in the week, Wednesday will likely remain on the
cooler and potentially showery side. The clusters support the
trough dropping into the Great Basin come Thursday, with the PNW
being on the upstream side of it. Positioning of the trough will
be crucial in determining whether the cooler conditions linger, or
whether a return to warmer temperatures is in store with a ridge
building on the back end. By Friday and into next Saturday, the
cluster solutions begin to diverge, some bringing ridging back
into the area in a potential rex block pattern, others keeping
another trough on the heels of the one that previously dropped
into the Great Basin. If the ridge becomes the clear solution,
additional days of elevated fire weather concerns may come to
fruition. If ongoing troughing over the area comes to pass,
perhaps cooler and wetter conditions will signal a larger seasonal
change. Stay tuned for updates as the week progresses.
Kristell
&&
.AVIATION...Upper level ridge shifting east tonight with the flow
aloft turning westerly. A very weak frontal system is currently
making its way onshore, though dissipating. In the lower levels,
onshore flow--generally south to southwest at 5 to 10 kt--will occur
tonight into Sunday morning. A solid deck of middle to high clouds
will keep Sunday overcast. Winds will ease up into Sunday afternoon
as a more substantial cold front moves into the area Monday morning.
KSEA...High cloud deck arriving from the northwest with some smoke
aloft tonight. Stratus deck will approach the terminal from the
southwest Sunday morning. The stratus should remain west of the
terminal, however, with a 15% chance of MVFR conditions, have
mentioned a period from 14-16Z of lowered ceilings. Increasing mid-
level clouds into Sunday afternoon. WSW winds will gradually shift
to more SW, around 5-8 kt throughout the TAF period.
Felton/LH
&&
.MARINE...A surface ridge will remain over the coastal waters
through early Sunday producing onshore flow. A weakening frontal
boundary is currently moving towards Western Washington and
producing some showers just west of Neah Bay up towards Vancouver
Island. A surface ridge rebuilds briefly over the coastal waters on
Monday before another trough and associated front arrives late
Tuesday. High pressure rebuilding over the coastal waters Wednesday
and Thursday.
Small Craft Advisory westerly winds in the Central and Eastern
Strait of Juan de Fuca tonight and again late Sunday night behind
the frontal boundary. Gusts could reach up to gale force, though
should remain isolated and hug the Canadian waters.
Increasing activity over the Gulf of Alaska will generate a larger
swell train that is anticipated to arrive on Monday with seas
building to 12-14 feet. Seas will gradually subside Tuesday, with
another incoming northwesterly swell raising seas above 10 feet on
Wednesday. Seas subside to 4-6 ft towards the end of the week.
Felton/LH
&&
.FIRE WEATHER...Elevated fire weather concerns persist into
tonight with relatively fair to poor RH recoveries in some areas
of the Olympics and Cascades. Sunday will bring the next weather
system into the area as well as increasing onshore flow...and
this moderating influence, plus a chance for precipitation, will
help to keep fire weather concerns minimal for the start of next
week.
There is a lot of uncertainty in the forecast beyond the middle of
the coming week. Current forecasts suggest a return to warm and dry
conditions for the second half of the week, but the prospect of
strong easterly winds continues to diminish. Still, with the level
of uncertainty that persists among the models and ensembles, it
would be wise to treat the forecast beyond Wednesday with very low
confidence until a consensus emerges. JD/18
&&
.HYDROLOGY...The daily hydrology discussion has ended until the
start of the next rainy season; it will only be updated as needed.
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory until 5 AM PDT Sunday for Central U.S.
Waters Strait Of Juan De Fuca-East Entrance U.S. Waters
Strait Of Juan De Fuca.
&&
$$