Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/18/23
Area Forecast Discussion
National Weather Service Billings MT
143 PM MDT Fri Mar 17 2023
.DISCUSSION...
Tonight through Saturday night...
As of 1pm, there remains a band of light snow/flurries from Miles
City to the southeast corner of MT. This is within an axis of weak
850mb frontogenesis, which is waning, thus the very light precip
should finally taper off over the next couple hours. Surface
analysis shows a 1034mb high over northeast MT and this will sag
slowly to the south tonight. Light winds, clearing skies and some
boundary layer moistening from snow melt could lead to localized
fog especially east of Billings tonight...though this is of very
low confidence at this time. The HRRR is suggestive of fog near
Miles City tonight but shows much greater coverage over northeast
MT. Something to keep an eye on.
Otherwise, ridge building from the west will bring us quiet
weather over the next 36 hours...along with a gradual warming
trend after what will be a chilly night tonight. Lows tonight
should fall below zero at Baker (it is only 13F currently), with
single digits and teens elsewhere. No chance of any record lows
though. Highs tomorrow should range from near 30F at Baker to the
mid-upper 40s across our west. Saturday night will be milder, w/
a modest increase in downslope winds along our western foothills
as a lee side trof develops. Strongest winds on Saturday itself
should be in Carbon County per Bighorn Basin drainage (25-35 mph
gusts). In all, we should finally be seeing more rapid lower
elevation snow melt these next couple days.
By the way, today is day #135 without reaching 57 degrees at the
Billings airport. This has now eclipsed the old record by 7 days.
JKL
Sunday through Friday...
Sunday will be mostly sunny with highs in the 40s to low 50s
across the region, wrapping up a beautiful, and seasonal, weekend.
A weak back door cold front will drop in from the northeast late
Sunday bringing slightly cooler temperatures to the region to
start the work week. Precipitation chances will then return for
the mountains and lower elevations during the week as a trough
moves inland over the west coast, providing energy and moisture
across our region. Lots of uncertainty remains in how the trough
will evolve as it moves inland though, which will impact how the
precipitation sets up. Right now, it looks like snow will move
into the mountains during the day Monday, before spreading across
the lower elevations and plains Tuesday into Wednesday. The
mountains have a 60% chance for 2 inches of snow. The lower
elevations and plains will be more complicated as deep cold air is
not expected with this event, so snow will be wet, lowering
possible accumulations. After Wednesday, the coldest day of the
week with highs potentially in the low to mid 30s, temperatures
will increase into the 40s allowing scattered rain showers to mix
in east of Billings. Since uncertainty remains in how the trough
will form, a lot of uncertainty also remains in how quickly the
trough and precipitation will move out Thursday into Friday. A
slower trough will result in precipitation chances sticking around
through the week, but a faster trough will allow for clearing by
the end of week. Arends
&&
.AVIATION...
Band of light snow over KMLS to the southeast corner of MT (w/
MVFR-IFR conditions) will dissipate thru the remainder of this
afternoon. Building high pressure will bring widespread VFR over
the next 24 hours...though there is a slight risk of fog near KMLS
& KBHK late tonight into early Saturday (from roughly 10-15z). NW
winds gusting 15-25 knots east of KBIL will diminish quickly after
00z this evening. JKL
&&
.PRELIMINARY POINT TEMP/POPS...
Sat Sun Mon Tue Wed Thu Fri
-----------------------------------------------------------
BIL 018/047 029/054 027/047 026/039 026/038 027/047 030/049
00/U 00/U 01/E 23/S 45/S 42/O 11/B
LVM 012/046 026/049 029/046 028/041 026/040 028/044 028/043
00/U 00/N 02/O 33/S 45/S 43/S 22/S
HDN 011/047 020/054 022/049 022/041 024/040 023/046 025/049
00/U 00/U 00/E 13/S 55/S 53/O 22/R
MLS 005/038 019/044 019/039 022/038 025/036 024/037 023/043
00/U 00/B 00/E 02/S 45/S 53/S 11/B
4BQ 006/039 019/051 022/048 026/042 028/039 027/042 027/046
00/U 00/B 00/B 12/S 45/O 53/S 21/B
BHK 906/030 013/040 013/031 014/031 018/033 020/034 017/038
00/U 00/B 00/E 12/S 46/S 54/S 21/B
SHR 007/041 015/047 019/045 020/039 021/037 021/041 023/043
00/U 00/U 00/E 13/O 56/O 53/S 22/S
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...None.
WY...None.
&&
$$
weather.gov/billings
Area Forecast Discussion
National Weather Service Columbia SC
753 PM EDT Fri Mar 17 2023
.SYNOPSIS...
Cold front and shower activity will push through the forecast
area tonight. Cool and very dry air returns for the weekend
into early next week, including the potential for a frost or
freeze. Air mass will moderate beginning Tuesday with above
average temperatures by the end of the week.
&&
.NEAR TERM /THROUGH TONIGHT/...
Cold front and associated area of showers will move through the
forecast area tonight. Limited instability so not expecting
thunder. Precipitation is expected to move out of our FA by
daybreak. Expect a wind shift to NW behind the front, with
diminishing speeds, with drier low level air filtering in. Lows
in the middle 40s north to low 50s south and east.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
The front will be slowly shifting off the coast early Saturday
morning with lingering moisture gradient in place, although HREF
indicates that PWATs will be less than an inch across most of
the area except for possibly the far southeastern forecast area.
Pops continue to decrease through the morning as drier air will
continue to push into the forecast area, especially in the low
levels. Cooler with lower 500mb heights although cold advection
likely won`t begin in earnest until Saturday night. Highs will
be in the upper 50s to low 60s. HiRes models indicate the
potential for some light rain in the southeastern forecast area
Saturday evening into Saturday night as a shortwave moves
through but soundings indicate a significant dry layer in the
low levels so kept the forecast dry. Temperatures dropping into
the 30s overnight Saturday, although blended guidance shows the
highest probability for freeze remains in the Upstate of SC so
have no freeze watch for early Sunday morning at this point.
Cooler Sunday with 850mb temps below 0C as highs will struggle to
rise, in the low to mid 50s even with only a few passing high clouds
over the area. Higher chance for a freeze Sunday night into Monday
morning across much of the area as the surface high will be centered
just NW of the forecast area with better radiational cooling
conditions.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
Colder than average temperatures continue for Monday as blended
guidance indicates highest probability for a freeze once again in
the northern half of the forecast area. Ridging will begin to build
over the area Tuesday as GEFS mean has been trending stronger with
upper ridging. The NAEFS mean similarly indicates 500mb heights will
exceed the 90th percentile leading to further confidence in
temperatures well above average by the end of the week. EC and GEFS
members continue to support a dry airmass in place through at least
Wednesday with high probability of PWATs remaining below an inch. A
bit more uncertainty late in the period as to the degree of moisture
but with ensemble generally supporting rising heights through
Thursday, kept the forecast dry through at least Thursday with a bit
more uncertainty for Friday.
&&
.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
MVFR Ceilings and visibilities arriving at all terminals
associated with rainshowers and an arriving cold front.
Improvement expected towards Saturday morning.
METARs, radar and satellite indicating a fairly wide frontal
band of weather moving into the region at 00Z, arriving at KAGS
and KDNL now, then KCAE/KCUB and KOGB by 02-03Z. Upstream
observations in GA show isolated IFR in heavier showers, but
predominately widespread MVFR. Models are mixed on ceiling
heights, with latest HRRR guidance indicating IFR overnight, but
it is the outlier. Moderately confident primary impacts will be
MVFR and am watching closely through the next 9-10 hours. Band
of active weather associated with the front expected to push
southward through our terminals by 09-11Z, but as frontal band
stalls along the Coastal Plain impacts may linger slightly longer.
High pressure and drier air pushes in after 16-19Z, expect
improvement to VFR after sunrise as the day progresses.
EXTENDED AVIATION OUTLOOK...No aviation impacts expected Sunday
through Tuesday. Morning visibility impacts possible on
Wednesday.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
&&
$$
Area Forecast Discussion
National Weather Service Dodge City KS
420 PM CDT Fri Mar 17 2023
...Updated Aviation...
.SHORT TERM...(This evening through Saturday night)
Issued at 1223 PM CDT Fri Mar 17 2023
Water vapor satellite imagery and RAP upper air analysis at midday
depict a powerful upper level cut-off low centered over the far
northern Midwest, resulting in longwave troughing over the
majority of the CONUS. At the surface, gusty north-northwest winds
will continue across the area through the afternoon today as high
pressure builds into the central plains in the wake of yesterday`s
cold front. However, the strong mid-March sun combined with the
weakly downsloping winds will help to offset the effects of the
cold front as temperatures peak in the upper 40s to low 50s this
afternoon. Overnight tonight, vorticity maxima rotating around
the upper level cut-off low will send another, albeit weaker cold
front through southwest KS, giving our area another shot of cold
air and supporting lows dropping into the teens to low 20s by
sunrise.
Daytime Saturday, gusty north-northwest winds will continue on the
southern periphery of a ~1038-mb surface ridge centered over the
northern plains. Despite the strong sun and weak downsloping
winds, the reinforced cold airmass over the central plains will
limit afternoon highs to the upper 30s to mid 40s.
.LONG TERM...(Sunday through Friday)
Issued at 217 PM CDT Fri Mar 17 2023
Medium range guidance is in agreement regarding the upper level
pattern at the beginning of the long term period, suggesting an
upper level ridge will build into the Intermountain West in the
wake of the strong cut-off low that will be moving into the
northeast CONUS/southeast Canada. In response, surface ridging
will advance into the southern plains/western Dixie Alley region,
resulting in southerly winds resuming across southwest KS and
initiating a warming trend. 850-mb temperatures warming into the
2-9C range will translate to afternoon highs in the low 50s near
central KS to the mid/upper 50s near the KS/CO border.
Upper level ridging will eject into the High Plains and dampen
during the day Monday ahead of the next upper level trough moving
ashore over California. The surface pressure field consisting of
high pressure over Dixie Alley and lee troughing across eastern
CO/WY will result in increasing S/SSW winds throughout the central
plains, supporting the continuation of the warming trend with
afternoon highs in the low to mid 60s. Early Tuesday, a passing
upper level shortwave trough will bring an outside chance of
precipitation for the eastern zones, however ensemble means
indicate the majority of the precipitation will fall over central
and eastern KS as per usual, with only a hundredth or two within
our CWA. Otherwise, the aforementioned upper level trough will
take its time moving eastward, leaving southwest KS in roughly the
same pattern as temperatures continue to rise into the upper
60s/low 70s Tuesday, and the upper 70s/low 80s Wednesday.
On Thursday, latest runs of the EPS/GEFS predict the upper level
trough will finally make significant progress eastward. Ensemble
meteograms show some slight signal of precipitation chances with
this feature and the associated cold frontal passage sometime
Thursday, however confidence is very low at the moment.
Regardless, cold advection behind the front will knock
temperatures back down into the 50s and 60s by the end of the
period.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 420 PM CDT Fri Mar 17 2023
Excellent flying weather is expected through this TAF cycle.
Stratocumulus field currently will dissipate quickly at sunset.
VFR/SKC is expected tonight through Saturday. Elevated gusty
NW winds currently will diminish rapidly around sunset, with light
northwest winds < 10 kts prevailing through 15z Sat. After
15z Sat, NW winds will increase once again, with modest gusts
of 23-25 kts.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 17 43 12 51 / 0 0 0 0
GCK 17 43 13 53 / 0 0 0 0
EHA 19 45 16 55 / 0 0 0 0
LBL 17 46 14 55 / 0 0 0 0
HYS 16 38 10 50 / 0 0 0 0
P28 21 44 15 50 / 0 0 0 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Springer
LONG TERM...Springer
AVIATION...Turner
Area Forecast Discussion
National Weather Service Duluth MN
1021 PM CDT Fri Mar 17 2023
.UPDATE...
Issued at 1019 PM CDT Fri Mar 17 2023
Extended the Winter Weather Advisory across the MN Arrowhead
overnight due to lower visibilities in blowing snow as seen on
area webcams and observed at automated weather stations. Winds
should pick up a little overnight adding to the visibility
restrictions caused by blowing snow.
&&
.DISCUSSION...(This evening through Thursday)
Issued at 315 PM CDT Fri Mar 17 2023
Summary: Light to moderate snow continued this afternoon but will
diminish for most later tonight except along the South Shore
where heavy lake effect snow will occur. High pressure builds in
later Saturday and will cause drying into Sunday. There will be a
couple more opportunities for snow or a mix from mid to late week.
Light to moderate snow continued over much of the Northland this
afternoon with an area of heavier snow showers from the Bayfield
Peninsula west-northwest into the Iron Range. These were occurring
in an area of steeper low level lapse rates and some low level
FGEN forcing. The steeper lapse rates/FGEN will continue and move
south into this evening. Although not likely, a few snow squalls
will be possible into this evening with brief visibility
reductions to a quarter mile possible. Most of the snow will
diminish or end later tonight except along portions of the South
Shore, more on this below. Additional snowfall outside of far
northern Wisconsin will range from a dusting to 2 inches with 2 to
5 inches from the Iron Range into the Arrowhead. We extended the
Winter Weather Advisory for the Arrowhead to 5 AM Saturday.
As far as far northern Wisconsin and particularly the South
Shore, low level winds have backed to more west to northwest today
but will veer to northerly tonight. Conditions for significant
lake effect snow will become very favorable overnight with a long
fetch, very favorable delta-T values, and rising inversion
heights. We increased snow amounts some tonight from east-central
Ashland County into northern Iron County. Snowfall rates will
approach an inch per hour in the snowbelt. A bit further west, a
gravity wave may again form tonight as depicted by the higher
resolution models. The RAP does show drier air moving in though so
that may offset the expected lift some. We forecast another 6 to
13 inches of snow in the snow belt of Ashland/Iron Counties
tonight with 3 to 7 inches from east-central Douglas County into
the Bayfield Peninsula. The Winter Storm Warnings from
Douglas/Bayfield County were extended to 7 AM Saturday and to 1
PM Saturday for Ashland/Iron Counties. Drier air and backing low
level winds should shut off the snow Saturday afternoon or
evening.
Dry conditions are then expected Sunday and Monday with warmer
temperatures moving in. Highs Saturday in the lower to middle
twenties will warm into the thirties Sunday and Monday.
Another low pressure system will bring chances for snow or a
rain/snow mix to the region mid-week. A few inches of snow will be
possible mid-week. Yet another stronger area of low pressure may
bring significant snow to the region late week. Take a deep
breath...there is still quite a bit of uncertainty regarding the
late week system. The models are showing plenty of differences in
the track and the ECMWF ensemble members show very little
clustering. It`s much to early to speculate on snow amounts with
the late week system.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 644 PM CDT Fri Mar 17 2023
Remnants of the departing system linger with wrap around flow
bringing IFR conditions and squally snow showers temporarily have
lowered flight cats to VLIFR. These should taper down as the
evening wears on and forcing exits. Until then, plenty of IFR in
snow showers. Gusty winds overnight will also cause visibility
reductions in BLSN. Eventually an improvement to VFR Saturday.
&&
.MARINE...
Issued at 315 PM CDT Fri Mar 17 2023
Northwest winds this afternoon will veer to north tonight and
increase building waves further, mainly along the South Shore.
Gales around 35 knots will be possible, both along parts of North
Shore and around the Outer Apostle Islands. The wind will decrease
a bit through the day Saturday and back to northwest late in the
day then to west Saturday night. Winds will increase again Sunday.
Conditions will remain hazardous through the weekend and Small
Craft Advisories will likely be needed into early next week.
The cold temperatures and waves will create areas of heavy
freezing spray tonight into Saturday along the South Shore. Low
visibility will also be likely into Saturday morning in snow
showers.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 7 23 7 34 / 60 10 0 0
INL 6 25 5 35 / 60 0 0 0
BRD 8 24 3 33 / 60 10 0 0
HYR 8 25 6 35 / 80 30 0 0
ASX 11 25 10 37 / 90 60 0 0
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
WI...Winter Storm Warning until 7 AM CDT Saturday for WIZ001-002.
Winter Storm Warning until 1 PM CDT Saturday for WIZ003-004.
MN...Winter Weather Advisory until 5 AM CDT Saturday for MNZ011-012-
019>021.
LS...Gale Warning until 4 AM CDT Sunday for LSZ140-141.
Small Craft Advisory until 10 PM CDT Sunday for LSZ142>148.
Heavy Freezing Spray Warning until 10 AM CDT Saturday for LSZ145.
Heavy Freezing Spray Warning until 4 PM CDT Saturday for
LSZ146>148-150.
Gale Warning until 4 PM CDT Saturday for LSZ150.
&&
$$
UPDATE...Wolfe
DISCUSSION...Melde
AVIATION...Wolfe
MARINE...Melde
Area Forecast Discussion
National Weather Service Quad Cities IA IL
633 PM CDT Fri Mar 17 2023
...00Z AVIATION UPDATE...
.SYNOPSIS...
Issued at 158 PM CDT Fri Mar 17 2023
An upper level low is evident on water vapor sinking southward
across the Dakotas and Minnesota. Closer to home, yesterdays frontal
boundary sits to our south and east with clear skies across the
area. Gusty northwest winds of 15 to 25 MPH and gusts up to 35 MPH
continue. Temperatures at 1 PM range from 22 degrees at Cedar Rapids
to 32 degrees at Macomb and Keokuk.
&&
.SHORT TERM...(This evening through Saturday)
Issued at 158 PM CDT Fri Mar 17 2023
Key Messages:
1. Flurries possible tonight and Saturday.
2. Continued cold and windy through Saturday.
Discussion:
The main forecast concerns were winds and chances of precipitation.
Models differ slightly in the placement of different features.
A southeastward digging trough and closed 500 MB low will be the
main driver for the weather this weekend. Two disturbances rotating
through the trough will bring rounds of flurries to the area late
this afternoon into tonight and again on Saturday afternoon. Subtle
surface troughs will also accompany each shortwave. Model time
series and soundings do not show very good saturation but there is
enough for ice crystals and thus flurries as the energy moves
across the area. The HRRR and RAP do show some 0 to 3 km CAPE up
to 30 J/KG during these periods so there may be bursts of flurries
instead of widespread flurries both tonight and Saturday. We are
not expecting any accumulation from these shortwaves. Models do
differ on the placement of QPF with the ECWMF and GFS being far to
the east than other models. Low level dry air may work to limit
the overall potential.
The tight pressure gradient will remain across the area as high
pressure remains to our northwest through the period. There will be
some relaxing of the gradient on Saturday, but winds will remain
breezy at 15 to 25 MPH. Temperatures will remain well below normal
this weekend with low temperatures on Saturday morning ranging from
10 to 15 degrees. When factoring in the wind speed, wind chills on
Saturday morning will be in the single digits below zero.
Saturday`s high temperatures will be in the mid to upper 20s with
the wind making it feel like it is 5 to 15 degrees above zero.
.LONG TERM...(Saturday night through Friday)
Issued at 158 PM CDT Fri Mar 17 2023
Key Messages...
1) A chilly night is expected Saturday night before gradually
warming temperatures develop through Thursday
2) After an expected dry period, chances of precipitation return by
mid-week, with perhaps some strong storms possible
The long-term forecast period starts off with a chilly night
Saturday night, with overnight lows in the lower to middle teens,
and wind chills falling to the single digits - above and below zero.
This will be due to a cold-core upper-level low that is progged to
be located over far eastern Ontario Canada Saturday night. Our
region continues to be under the cold air advection/cyclonic flow
portion of the low, resulting in the colder conditions. Northwest
winds will continue to be gusty Saturday evening, with gusts between
25 to 35 mph before slowly tapering off into Sunday morning.
A pattern change is expected Sunday, as high pressure builds in from
the northwest. The high pressure system will remain in control at
least through the day Monday, with dry conditions. Winds will
gradually turn more southerly Sunday, supporting warm air advection.
High temperatures on Sunday will warm to the upper 30s, which is
still below seasonal average, but will be welcomed warmth compared
to the conditions for tonight and Saturday.
Conditions become more active by mid-week, with a push of moisture
off the Gulf of Mexico per wind streamlines. The global models and
NBM suggest chances of rain to increase Tuesday night, ahead of a 35
to 45 knot low-level jet. Instability appears to be lacking, so only
some light rain showers are expected for Tuesday night into
Wednesday. Things might be more active on Thursday, as both the GFS
and ECMWF deterministic and ensembles suggest a sharp baroclinic
zone setting up somewhere along and southeast of our region.
Instability appears to increase during this time, with the GEFS
ensemble plumes suggesting SBCAPE values on the order of 200 to 700
J/kg across our south, although the ECMWF ensembles aren`t as
bullish on instability. There should be plenty of moisture to work
with along the boundary, with both the GEFS and ECMWF ensembles
suggesting Pwat values 150 to 200% of average (average value for DVN
being 0.42"). The ECMWF EFI for CAPE-Shear indicates a lower-end
potential for strong to severe storms in our forecast area, with
values around 0.5 to 0.7 for Thursday. The Storm Prediction Center
has mentioned a potential for strong to severe storms in our region
Thursday, but uncertainty remains regarding the ejection of the
upper-level trough, and placement of related surface features.
Definitely something to keep an eye on as we approach mid-week.
Temperatures will gradually warm up into Thursday, with highs
warming into the upper 50s and some 60s!
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 631 PM CDT Fri Mar 17 2023
Gusty NW winds 15-30 kts and bouts of VFR to MVFR stratus and
flurries expected during the period.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
SYNOPSIS...Cousins
SHORT TERM...Cousins
LONG TERM...Schultz
AVIATION...McClure
Area Forecast Discussion
National Weather Service Lincoln IL
907 PM CDT Fri Mar 17 2023
.SYNOPSIS...
Issued at 241 PM CDT Fri Mar 17 2023
Cooler than normal weather sticks around through the weekend, with
wind chills overnight expected to be near or below zero north of
I-72 with values in the single digits south of there. A weather
system will bring scattered snow showers or flurries late tonight
into Saturday. Temperatures look to rebound back to near normal
values by early next week, with above normal temperatures
returning by the middle of next week.
&&
.UPDATE...
Issued at 907 PM CDT Fri Mar 17 2023
After coordinating with neighboring office, snow chances have been
increased further for tonight with potential for some light
accumulations around a half inch or so north of I-74.
Upstream observations show numerous snow showers advancing across
central Iowa, with the leading edge now about to cross the
southeast Iowa border with Illinois. RAP snow squall parameter is
focusing on a period between about 11 pm and 4 am as steep low
level lapse rates slide just south of the I-74 corridor. Winds
will be increasing again after midnight and some low visibility
will accompany the stronger showers.
UPDATE Issued at 740 PM CDT Fri Mar 17 2023
Evening water vapor imagery continues to show an upper wave
swinging across Iowa. Regional radar mosaics show numerous snow
showers ahead of this wave, with the latest HRRR showing these
reaching west central Illinois toward 9-10 pm. Additional snow
showers should increase through midnight and focus on the east
half of the forecast area through about 4-5 am. With another upper
lobe swinging through the region on Saturday, along with steep
low level lapse rates, additional flurries and snow showers are
likely.
Snow trends have been updated through Saturday to increase PoP`s
some, generally to about 30% tonight and also increasing them
Saturday afternoon to around 20%. Temperature and winds largely
look on track.
&&
.SHORT TERM...(This evening through Saturday night)
ISSUED AT 241 PM CDT Fri Mar 17 2023
Clearing has just about made its way to the IL/IN state line just
after 2 pm as surface ridging continues to nose further eastward.
The sunshine sure is deceiving though as temperatures this
afternoon are sitting in the 30s, which is 10-15 degrees below
normal for mid March. This paired with a stiff northwest winds is
making it feel even colder with wind chill readings in the 20s
this afternoon.
A 500 mb upper trough will swing through the Great Lakes Region
later today, pushing a lobe of vorticity through central IL tonight.
Clouds will increase with the wave, with forecast soundings showing
just enough moisture and lift to support a few flurries or light
snow showers overnight tonight, with on/off chances continuing
through the daytime hours of Saturday as cyclonic flow remains
positioned overhead. Although overall moisture will be starved with
this system, there may be just enough to squeeze out a quick dusting
of snow in some spots.
Overnight lows tonight will be unseasonably cold with lows dipping
down into the teens to low 20s. With winds remaining breezy
overnight, wind chills will make it feel even colder with values
expected to be near/below zero north of I-72. Values south of there
will be in the single digits. Similar lows will be seen on Saturday
night into Sunday morning, but decreasing winds will keep wind
chills in the single digits to teens.
&&
.LONG TERM...(Sunday through Friday)
ISSUED AT 241 PM CDT Fri Mar 17 2023
Surface ridging slides into the area on Sunday, though temperatures
will still be cold to close out the weekend. Southerly return flow
sets up going into the start of the new week, with seasonable
temperatures returning for Monday. Temperatures will continue to
climb through the week, possibly peaking in the 60s or near 70 by
Thursday. A couple of upper shortwaves look to bring precipitation
back into the area by the middle of the week, with a stronger
system/upper wave progged to move through Thursday into Friday.
Sufficient moisture looks to advect back northward ahead of the late
week system, which should be enough to support storms, possibly
severe. It is still a little early to discern the details of this
system, but something to keep our eyes on.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 617 PM CDT Fri Mar 17 2023
Main aviation the next 24 hours will remain with the winds, as
west/northwest winds will continue to gust 25 to 35 knots much of
the time. There will be a period this evening where the winds drop
off, but then pick up again 06-08Z as a cold front swings through
the area. This front will also bring ceilings getting close to
3,000 feet, though HREF ensembles suggest that KSPI/KDEC will have
the best shot of dipping into MVFR territory for a time. Snow
showers with the front have the potential for some brief
visibility dips, but not enough to warrant a mention in the TAF`s
at this point.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Geelhart
SYNOPSIS...NMA
SHORT TERM...NMA
LONG TERM...NMA
AVIATION...Geelhart
Area Forecast Discussion...UPDATED
National Weather Service Indianapolis IN
953 PM EDT Fri Mar 17 2023
.Forecast Update...
Issued at 953 PM EDT Fri Mar 17 2023
The near-term forecast is in good shape with minimal adjustments
needed. Satellite shows a general decrease in stratus across the
area this evening. MSLP gradient is tight enough for winds to only
decrease some tonight as mixing lessens. It is worth noting that
cold advection and winds will be sufficient for single-digit wind
chill values across roughly the northern two-thirds of the area
tonight, with some near-zero values possible.
Embedded within an eastward migrating deepening midlevel low is a
fairly pronounced vort max progressing toward our area. Water vapor
channel imagery shows this feature over Iowa now, and short term
models show associated fairly strong DCVA moving into central
Indiana during the predawn hours and progressing eastward through
early morning. Upstream observations over Iowa show both pre- and
post-frontal snow showers, and as the vorticity lobe
sharpens/strengthens some overnight, the preceding snow band may
organize further. Although forcing may not result in a classic snow
squall scenario, steepening low-level lapse rates and small (but
vertically confined) positive area (i.e., up to around 50 J/kg
MLCAPE) evolve during the early morning hours, and drive snow squall
parameter up to nonzero values. Current thinking is that brief
visibility reduction in moderate to heavy snow along the DCVA
forcing and surface frontal reflection should progress across
central Indiana roughly in the 5:00am to 10:00am window. Its
progressive/quick-moving nature should limit accumulation potential
but up to one half inch may occur, especially north of roughly I-70.
Steep low-level lapse rates persist into the afternoon and with even
minimal surface warming/destabilization, renewed development of more
PBL flow-parallel bands of snow showers may occur. A few hi-res
models (i.e., HRRR are most aggressive) while others, including
global models are more subdued, likely owing to differences in
residual PBL moisture. We expect the most prevalent snow shower
coverage during the afternoon diurnal convective cycle to be
downwind of Lake Michigan north of our service area. However, at
least enough convective instability within a vertically confined
layer below a particularly low tropopause, and optimal placement
within the dendritic temperature range should result in at least
periodic flurries for most of our area. A reasonable worst case
scenario would be heavy enough bursts of snow from snow showers to
add a few tenths of an inch of snow accumulation, particularly
across roughly the northern half of the area. The overnight shift
will look closer at the afternoon potential and refine the forecast
accordingly.
&&
.Short Term...(This evening through Saturday)
Issued at 259 PM EDT Fri Mar 17 2023
Main impacts through Tomorrow:
- Cloud coverage and winds lessen overnight
- Secondary arctic cold front approaches tomorrow morning
- Isolated snow showers and scattered flurries for Saturday
- Gusty winds and cloud coverage increase as well
Rest of Today and Tonight: With the cold front well past the
forecast area, current satellite imagery and METARs across Eastern
Illinois and Western Indiana have captured the gradual weaning of
the cloud deck that is anticipated through the overnight hours.
Winds have correspondingly shifted to more westerly and
northwesterly components across the forecast area, helping to advect
drier air in at the surface. This corresponds to the dry slot of the
parent low attached to this morning`s cold front, which will bring
an end to PoPs this evening and a minor rebound in temperatures in
the early portions of the evening. This advection of dry air at the
surface will further promote the lifting of today`s persistent cloud
shield overnight.
After sunset, temperatures really begin to plummet and winds begin
to drop in speeds. Due to the upper trough ejecting eastward into
the Ohio Valley, expect the pressure to reduce overnight and allow
for winds to weaken. Gusts in the 15-20 mph range may persist
overnight, but conditions will not be as windy as they have been for
the past 36 hours. Low temperatures will drop to below 20 in areas
north of I-70 overnight, with the Indianapolis metropolitan area
averaging around 22 and the southern tier counties closer to 25.
Tomorrow: A well-defined arctic backdoor cold front is anticipated
in the forecast area Saturday morning, bringing brisk air and a
return to gusty winds/increased cloud coverage with it. Higher-
resolution guidance continues to depict the development of a few
snow showers. A deepening and broadening upper level low displaced
to the north of the forecast area in the Great Lakes region will
advect positive vorticity into the area, and modeled BUFKIT
soundings portray lift in the areas immediately ahead of the front.
However, the very dry air that advected in behind Friday`s initial
cold front should limit the amount of snowflakes that reach the
ground. Moisture levels remain the primary limiting factor in the
set up for this particular event. Accumulations, if any, should not
exceed more than a dusFlurries to some lgt snow possible overnight ting,
but localized higher amounts are possible if the potential for
enhanced low-level instability is realized. Therefore, the
forecast will stick with isolated snow shower verbiage, with the
potential for scattered low-impact flurries across the majority of
the area noted.
Temperature across the area will be limited by both the return of
more widespread cloud coverage and the advection of a continental
polar airmass into the area by increasing northwesterly winds in the
wake of this secondary FROPA. While mixing from aloft will not be as
pertinent as in past days this week, gusts may rise to 30 mph at the
surface by tomorrow afternoon. Maximum temperatures tomorrow will
struggle to rise above freezing, and wind chills will be quite
potent heading into the overnight hours on Saturday.
&&
.Long Term...(Saturday night through Friday)
Issued at 259 PM EDT Fri Mar 17 2023
* Well-below normal temperatures through Sunday night
* Warming trend beginning Monday
* Rain likely by mid to late next week
Saturday night through Sunday night...
Some isolated flurries cannot be ruled out early Saturday evening
with lingering low-level moisture, but confidence is low as upper
ridging and surface high pressure begin to build in. Low clouds will
initially limit diurnal cooling. However, well below normal
temperatures are still expected with cold air advection and clearing
skies later in the night. Look for lows in the upper teens across
most areas and wind chills around 5-10F. Temperatures will warm into
the mid 30s under mainly sunny skies on Sunday. Some diurnal
cumulus/stratocu is expected as forecast soundings show lingering
low-level moisture. Clear skies should allow for efficient diurnal
cooling Sunday night, but winds will become southwesterly late as
surface high pressure begins to move east. This may limit cooling
slightly with temperatures in the low 20s.
Next Week...
Return flow around the back side of the surface high will lead to a
significant shift in the weather pattern with temperatures warming
up quickly. This warming trend will be aided by increasing heights
aloft and strengthening south/southwesterly flow ahead of an
approaching system Wednesday into Thursday. Precip chances return on
Wednesday, associated with strong warm advective isentropic ascent.
Although QPF amounts will likely be light on Wednesday due to a lack
of upper level support. Heavier precipitation is expected late next
week as guidance is in decent agreement that a low pressure system
will move through the region. It is too early to determine rainfall
amounts, but favorable dynamics combined with above normal PWAT
anomalies should bring widespread rain to central Indiana. Precip
chances persist through the end of the period as this system`s cold
front likely sweeps across central IN late in the week.
&&
.Aviation...(00Z TAF Issuance)
Issued at 700 PM EDT Fri Mar 17 2023
Impacts:
* A return to VFR is expected early this evening based on
satellite/ob trends
* Winds will lessen overnight but increase again with the front in
the predawn hours
* Low probability of snow showers Saturday morning
Discussion:
Dry advection is eroding the stratus deck, though enough low-level
moisture remains in place that an upstream vort max will probably
result in stratus on the margins of MVFR/VFR in the predawn hours.
Enough ascent may be present for some flurries or light snow
showers. The probability of significant visibility reductions
appears low at this time given expected intensity, though we will
need to monitor trends.
Post-frontal environment and mixing will cause winds to increase
again and veer slightly to west-northwesterly. They will remain
gusty through the diurnal mixing period. Stratus will likely fill
back in but should remain just above VFR thresholds, with ceiling
restrictions being unlikely, but possible in a reasonable worst case
scenario. Accompanying this stratus could be some flurries or snow
showers through the afternoon, though this is conditional on
sufficient low-level moisture, which models are currently giving
mixed signals on.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Update...BRB
Short Term...Marcus/KH
Long Term...Melo
Aviation...BRB
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
847 PM CDT Fri Mar 17 2023
.UPDATE...
Issued at 847 PM CDT Fri Mar 17 2023
Quick update this evening to greatly boost snow chances,
particularly south of I-80 later this evening and overnight with
increasing concern for more significant coverage of strong/gusty
snow showers/squalls.
Moisture channel loops depict a robust shortwave trough axis
making quick progress across Iowa late this evening. At the base
of this trough, intense DCVA is ongoing across parts of central
and southeast Iowa where a gradual increase in coverage of
snow/snow showers has been noted over the last 1-2 hours. While
the 00z DVN RAOB sampled quite a bit of dry air, guidance
continues to indicate a more substantial reservoir of low-level
moisture exists to the south and at the leading edge of more
intense height falls. RAP forecast soundings indicate surface to
750 mb lapse rates will continue to steepen incrementally over the
next few hours along with sufficient saturation through a roughly
3-4 kft layer to support decent coverage of convective snow
showers. Greatest coverage looks to exist south of I-80, and
particularly along/south of the Kankakee River and peaking in the
midnight to 5 AM timeframe. With boundary layer flow still fairly
robust, the potential exists for brief wind gusts perhaps in
excess of 40 mph within any more robust cores which may also
facilitate brief visibility drops under a half mile.
With temperatures in the 20s and falling, any more intense bursts
will readily accumulate on roadways leading to a potential for
slick and hazardous travel. Will also work to message this threat
a bit more heavily in our graphical suite.
Carlaw
&&
.SHORT TERM...
Issued at 300 PM CDT Fri Mar 17 2023
Through Saturday night...
The key messages for the short term period:
* Continued blustery conditions and turning much colder tonight,
with wind chills down into the single digits to below zero by
daybreak Saturday.
* Quick hit of accumulating snow showers (generally under an
inch) tonight south of the Kankakee River.
* Occasional flurries likely for most areas on Saturday, with
some lake enhanced snow showers possible Saturday afternoon and
evening over northern Porter County IN.
Water vapor imagery early this afternoon depicts the next upper
level PV anomaly now shifting south-southeastward across the
eastern Dakotas. This feature is expected to dig southeastward
through the larger scale upper trough into southern WI and
northern IL tonight. As it does so, it will drive an impressively
cold arctic airmass, more reminiscent of January, into the area
late tonight and on Saturday.
While conditions will continue to be blustery and chilly this
afternoon, temperatures will only get colder tonight as the
aforementioned shot of cold arctic air sweeps into the area.
Current air temperatures upstream of the area are hovering in the
single digits to low teens above zero across a good chuck of Upper
Midwest, and this same airmass is headed our way tonight. Locally,
this airmass should result in low to mid teen surface
temperatures by early Saturday morning, but continued blustery
northwest winds will make it feel more like zero into daybreak
Saturday! Thereafter, continued blustery conditions during the day
will only allow temperatures to warm into the mid to upper 20s, a
good 20 degrees below normal. One last very cold night will follow
Saturday night before things begin to warm up later in the
weekend. Expect temperatures Saturday night to once again drop
back into the teens for overnight lows.
While the unseasonably cold conditions tonight and on Saturday
will be the primary weather story, there is also a good chance for
a period of snow showers with the approaching PV anomaly tonight,
particularly for areas south of the Kankakee River including
central parts of IL into IN. Steep low-level lapse rates and
somewhat better lower-level moisture in this area may even
support a period of more vigorous snow showers, and potentially
some snow accumulations under an inch. Elsewhere, we should see a
good deal of strato cu developing under this cold upper trough
tonight and on Saturday, and with this cloud layer looking to
reside right in the DGZ, occasional flurries can be expected.
Lake effect snow is also expected to kick up over and downstream
of Lake Michigan on Saturday. While some of this could impact
parts of northern Porter County with some minor accumulations
under an inch, it appears the primary focus will remain east of
the area.
KJB
&&
.LONG TERM...
Issued at 323 PM CDT Fri Mar 17 2023
Sunday through Friday...
After an unseasonably cold Saturday, temperatures will be on the
mend through the first half of next week beginning on Sunday.
However, we will remain on the cooler side of average to wrap up the
weekend. Height rises behind the trough axis progged to swing
through Saturday afternoon will promote WAA aloft and allow highs to
reach the middle and upper 30s on Sunday. An awfully dry profile
with synoptic-scale subsidence at play should allow for lots of
sunshine throughout the day. A few more clouds should roll in on
Monday with some mid level moisture flooding in on the backside of a
high departing to our southeast. At the surface, breezy return flow
will help pull highs on Monday back into the middle and upper 40s,
right on par with climatological norms. The breeziness stems from a
tight pressure gradient on the backside of the high and a notable
LLJ moving overhead. Steep lapse rates through the lowest 100mb or
so could allow us to mix down some 30-40 kt gusts through the
afternoon. The continued warm advection looks to bring 50s area-wide
on Tuesday with clouds building in anticipation of our next storm
system.
The first of two centers of low pressure stemming from the same
upper jet max will pass through the region Tuesday night into
Wednesday. Most guidance has scattered showers developing along and
behind the storm`s loosely organized warm front, call it more of a
baroclinic zone, and falling on the area as early as Tuesday evening
and continuing on through Wednesday. Rain chances will improve
through the day on Thursday as the trough approaches the Midwest.
It`s at this time that the second, more robust, more concerning low
will make its way into the region. A lot has changed among guidance
between last night`s 00Z runs and today`s 12Z runs, namely a drastic
shift southeastward in the track of this storm. The Euro now tracks
the storm through the southern part of the CWA Thursday night into
Friday and the GFS through the central CWA. The Euro`s solution
confines the footprint of instability, and therefore the thunder
potential, to the southeastern half or so of the CWA. The GFS
continues to suggest that thunder is possible area-wide, but the
greatest potential exists across the southern periphery of the CWA
where it`s cooking up over 1,000 J/kg of MUCAPE. The shear profile,
especially south of the warm front, continues to raise eyebrows with
a strong low level vertical wind gradient and notable veering
through the lowest few kilometers. Over an inch of PWAT also
suggests a healthy amount of rain is likely across areas that spend
a good amount of time in the warm sector. There is a lot more to be
said with this storm, but with such dramatic changes taking place
from run to run and it still being a week away, I`ll leave it at
that. Nonetheless, this will be one to keep a close eye on over the
next several days.
Doom
&&
.AVIATION...
For the 00Z TAFs...
645 PM...Forecast concerns include...
Strong/gusty west/northwest winds through the period.
Chance of flurries/snow showers tonight and again Saturday.
Winds will remain west/northwest with gusts into the 25-30kt range
through the period. Winds will begin to diminish Saturday evening.
There will be a chance of snow showers later this evening into the
early overnight hours, mainly south of the terminals where there
will likely be some visibility reductions. Confidence is low for
snow showers over the terminals tonight. There is a better chance
for snow showers across the entire area Saturday, from late
morning through mid afternoon and added tempo mention during this
time. These are expected to be isolated to scattered and short in
duration. Thus, some areas may only see flurries. Cigs are
expected to remain low vfr through Saturday evening, then begin to
scatter out. Some mvfr cigs will be possible with any snow
showers. cms
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...Small Craft Advisory...IN nearshore waters until 10 AM Sunday.
Small Craft Advisory...IL nearshore waters until 1 AM Sunday.
&&
$$
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