Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/26/22
Area Forecast Discussion
National Weather Service La Crosse WI
647 PM CST Sun Dec 25 2022
.DISCUSSION...(This evening through Sunday)
Issued at 300 PM CST Sun Dec 25 2022
Key Messages:
- A quick-hitting round of snow tonight, mainly for areas along
and west of the Mississippi River. A total of 1-3 inches
expected, which will lead to slick travel conditions.
- Warm-up in the offering starting Tuesday--highs in the 30s by
Wednesday and even low 40s for Thursday!
- Additional rain/snow late in the week still possible.
TONIGHT: Snow, mainly west of the Mississippi River
A well-advertised Alberta Clipper is on its way to affect the
region this evening and overnight. Extrapolation of current radar
and surface observation trends has the leading band of snow
crossing I-35 around 4 pm, reaching the Highway 63 corridor by
6pm, and the Mississippi River before 8pm. The bulk of the snow
should fall before midnight in conjunction with the strongest
isentropic ascent/Fgen forcing, with kinematic lift ahead of the
upper tropospheric trough axis fueling light snow up until
sunrise, ending from north to south as the trough axis swings
through.
The one aspect of this forecast that still presents a degree of
uncertainty is snowfall amounts. Two factors drive this issue,
the degree of forcing through a very deep dendritic growth zone
(8-12 kft deep) and the influx of dry air on the east flank of
the system. The short-term guidance has been steadfast in the
frontogenesis lift waning this evening as the WAA wing of the snow
moves through, but the HREF/GEFS/EPS has underperformed on the
snow up in the Dakotas, where visibilities fell to a quarter of a
mile and snow reports of 3-5 inches have reported. Dprog/Dt trends
with the HREF show that the probability of >1" of snow rapidly
increased over the Dakotas right as the storm arrived compared to
the previous two runs.
The snow has struggled to push east of a Crookston, MN to
Mankato, MN line today, slower than previously forecast and a
signal that the dry lower troposphere is eroding the front edge of
the snow band. This may limit how far east snow advances across
the forecast area, especially east of the Mississippi River. The
latest HRRR runs are reflective of these observations, keeping a
very sharp snowfall gradient along a Winona, MN to Wisconsin Dells,
WI line.
Overall changes to the forecast have been minimal. Have pushed
snow ratios to 20:1 throughout the forecast area given the
anomalously deep DGZ. Have also increased QPF values after
midnight as the system pivots over southern Minnesota, increasing
the residence time of the light snow west of the Mississippi
River. This raises snow amounts to 2.5-3 inches west of a line
from Rochester, MN to Guttenberg, IA. Would not be surprised to
see some 3+ inch reports if the forcing is any stronger than
progged. Have issued a winter weather advisory to cover the
threat.
MONDAY - WEDNESDAY: Warming Up!
Monday will be the last cold day of the stretch as strong
southerly flow ensues behind the passage of a surface high
pressure ridge Monday night. We will see a steady increase in
temperatures over the next 36 hours with highs in the mid-20s
Tuesday afternoon and lows plateauing Tuesday night. By Wednesday,
with a +6 to +9 C warm nose working into the region, highs in the
low to mid 30s are looking to be a good bet. A northern stream
wave passes north of the region and may bring periods of clouds,
but little in the way of impactful weather is forecast.
THURSDAY - SATURDAY: Warm, rain/snow possible
Longwave troughing sets up along the West Coast by Thursday
morning and persists through the end of the forecast period. A
lead shortwave ejects from the base of the trough Thursday or
Friday, though the bulk of the guidance is coming in drier for
PoPs with forecast soundings showing low stratus/drizzle across
the warm sector south of the warm front. Given that forecast
dewpoints would push into the 30s, an advection fog event may
develop Thursday and Friday, which may result in lower highs than
currently forecast. The deterministic progs still show a stronger
system coming out Friday into Sunday as the parent longwave
trough lifts northeastward, but ample variability in the location
of the system and whether or not it even impacts the area keeps us
in a holding pattern for ascertaining any further details.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 647 PM CST Sun Dec 25 2022
Snow will continue moving into the local area this evening,
bringing in low MVFR to IFR conditions consistent with current
upstream observations. However, short periods of LIFR conditions
could be possible within heavier snow. Model guidance suggests
there will be a tight gradient in snowfall, with some uncertainty
on how far east the snow band may reach. This will have impacts on
restrictions at KLSE, with a shift further east bringing a higher
likelihood for IFR conditions and further west possibly keeping
restrictions higher than currently forecast. Will continue to
monitor trends and make updates as necessary. Behind this system
VFR conditions are expected to prevail, with south winds becoming
more north/northwest through the day Monday /around 10kts or
less/.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...Winter Weather Advisory until 3 AM CST Monday for MNZ086-094-095.
IA...Winter Weather Advisory until 6 AM CST Monday for IAZ008>010-018-
019-029-030.
&&
$$
DISCUSSION...Skow
AVIATION...EMS
Area Forecast Discussion
National Weather Service Goodland KS
735 PM MST Sun Dec 25 2022
.UPDATE...
Issued at 735 PM MST Sun Dec 25 2022
00z NAM, RAP and HRRR all show moisture in the 850-500mb layer
increasing through about 09z from Flagler to Tribune and Leoti.
A 140-150kt upper level jet moves over this area supporting at
least slight chance pops for rain showers and snow showers. Low
temperatures through about sunrise are expected to be in the
middle 20s to lower 30s.
On Monday, another weaker shot of arctic air backs into the area,
slowly moving away during the afternoon. We`ll have another wide
range in high temperatures with middle 20s to around 30 from
McCook to Hill City east, middle to upper 40s across Kit Carson
and Cheyenne counties in Colorado. We`ll also have some stratus to
deal with which will impact the hourly temperatures for those
sites its over.
&&
.SHORT TERM...(This evening through Thursday Morning)
Issued at 153 PM MST Sun Dec 25 2022
Ridging over the west and a westerly component to the wind is
allowing temperatures to warm nicely into the 40s and mid 50s. The
exceptions being east areas which are just now making it above
freezing as the linger impacts of the arctic air mass remain along
with cloud cover. Winds will begin to turn northerly into the
evening as a clipper system moves into the area. Water vapor
imagery clearly shows the system as it rides down the east
periphery of the ridge. Sprinkles/virga will be common early as
RAP soundings show dry low levels but fully anticipate this to
saturate into the early evening. Rain is expected to be the
primary precipitation with this system with the better chances
lying to the east; with some filling into the northwest as the
evening progresses which may see some snow briefly mix in. Not
expecting much in precipitation wise as few hundredths are
currently forecast due to the amount of time it takes to saturate
the low levels and the quick moving nature of the system.
Monday, will be a bit trickier temperature wise to the west as the
clipper system will bring in some colder temperatures with it. I
wound up cooling western areas a few degrees as the RAP/NAM/ECMWF
all indicate the freezing line extending just west of the
Kansas/Colorado state line through 18Z. High temperatures look to
range from the upper 20s to the east to the mid 40s west,
although the west may be a few degrees cooler depending on the
final track. Into Monday afternoon winds will again become
westerly allowing the downsloping winds again to rapidly warm
temperatures into west Kansas as the clipper system moves away
from the area. Low temperatures into Tuesday morning are forecast
in the low 20s east to upper 20s west.
Tuesday and Wednesday will again be warm due to southwesterly
flow ahead of a trough over the western CONUS. Some model data
continues to show some locales approaching 70 degrees Tuesday,
given the time of the year having a hard time bumping temperatures
up more than the 50th percentile currently. High temperatures
Wednesday will again be well above average in the low 50s to low
60s. During the day Wednesday, the above mentioned trough moves
into the area bringing the next chance of precipitation. Based on
the current track it appears that the NW portion of the area will
have the relative best chance of precipitation. 850mb temperatures
aren`t overly cold with this system with them averaging just
around freezing. Current expectations are for a rain/snow mix with
perhaps some freezing rain mixing in as forecast soundings over
Yuma County do show a warm nose being present. Low temperatures
into Thursday morning are forecasted from the low 20s to perhaps
the low 30s over the east.
.LONG TERM...(Thursday through Sunday)
Issued at 132 PM MST Sun Dec 25 2022
A progressive pattern will be in place across the CONUS during the
long term period. Several fast moving shortwave troughs are
forecast to move through the area. Precipitation chances appear to
be low through most of the week, with perhaps a stronger system
set to impact the area late in the weekend or early next week.
Temperatures will be near or slightly above normal with highs in
the 40s and 50s and lows in the 20s. If any precipitation were to
occur, it would be light rain during the day and perhaps a light
wintry mix of rain/freezing rain/snow at night. Confidence in any
precipitation materializing before Sunday is low.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 328 PM MST Sun Dec 25 2022
An area of rain has developed and is moving to the SE. Some
uncertainty remains if it will impact the KGLD terminal so opted
for VCSH. Upstream observations has shown sporadic drops in
ceiling to MVFR in the heaviest areas of rain, so went for low end
VFR ceilings for KMCK. LLWS will become of a concern around 06Z
as the effects of a quick moving Clipper system affects the area.
Winds will rapidly become southerly during the early afternoon at
KGLD as the system moves away.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...99
SHORT TERM...Trigg
LONG TERM...024
AVIATION...Trigg
Area Forecast Discussion
National Weather Service Lincoln IL
905 PM CST Sun Dec 25 2022
.SYNOPSIS...
Issued at 256 PM CST Sun Dec 25 2022
A clipper system will bring central Illinois a quick inch or two
of snow Sunday night into Monday. A ridge of upper level high
pressure building in to the region from the west will result in
warming temperatures through the end of the work week, when parts
of the area could experience temperatures in the 60s. Chances for
rain increase by Friday and Saturday ahead of the next system.
&&
.UPDATE...
Issued at 905 PM CST Sun Dec 25 2022
Evening upper air analysis and water vapor imagery indicated a mid
level circulation over southwest MN, with an attendant 1012 mb
surface low over far NW IA. Radar returns ahead of the clipper
have already progressed east of the IL River, though the initial
round of lift in the warm advection sector is working to moisten
the dry low levels as noted on 00z KDVN/KILX soundings. Light snow
was reported in Galesburg within the last half hour, with more
substantial snow located over southeast IA where visibilities
around 1 mile were reported. The light snow will spread southeast
across the CWA overnight, with accumulations around an inch or
less for most areas. After the first round of lift pushes through,
will need to monitor potential for light freezing drizzle as
deeper saturation is lost especially over west central IL late
tonight. A few freezing drizzle obs have been reported over
southern IA this evening. As the surface low tracks into west
central IL after daybreak, a band of frontogenesis north of the
low will bring another round of light snow to the northern CWA,
which will drop southeast across the region during the afternoon.
Any accumulations will be light, again around an inch or less.
Will continue to highlight impacts of light snow with Special
Weather Statement product. Only a few tweaks were made to the
forecast, nudging low temperatures up a degree or two, and
refining PoP timing based on latest trends.
&&
.SHORT TERM...(Through Monday night)
ISSUED AT 247 PM CST Sun Dec 25 2022
Truly, there`s only one forecast concern in the short-term, and that
is the clipper system coming in from the northwest. The
deterministic GFS, ECMWF, CMC, and NAM all show a 500mb vort max
drifting southeast from the northern Plains into IA/IL/MO between
this evening and around noon Monday. HREF forecasts negative omega
at 700mb by 9 PM, GFS suggests Q-vector convergence in the 850-300mb
layer by midnight tonight, and NAM and RAP forecast soundings
suggest more saturation in the dendritic growth zone compared to
what they forecast yesterday, so support for frozen precipitation is
looking promising. The upper feature is forecast to slowly weaken as
it crosses our area though, so snowfall amounts could be a little
lower than what folks upstream see. The HREF suggests precipitation
totals from this event will be generally in the 0.10-0.15" range,
highest in our north and southeast CWA. NBM v4.1 has trended
downward, and suggests around a 30% chance for >1" of snow by 12z
Tuesday morning for most of the CWA, while the probabilities are
higher (around 50-60%) south of I-70. The probability for more than
2" from NBM is around 5% to 15%, again maximized south of I-70. For
now, we`ve decided against issuing an Advisory given (1) the bulk of
the snow will fall overnight when hopefully few folks are
traveling and (2) accumulations are expected to fall so shy of
Advisory criteria (3").
As far as timing goes, we heavily relied on high resolution ensemble
guidance. HREF suggests precipitation will begin to creep into our
NW CWA around 7 to 8 PM and reach Peoria shortly thereafter. The
CAMs suggest the heaviest snow rates with this initial wave will be
across our northern counties between roughly 9 PM and midnight, and
across our southeast counties between 2 and 6 AM tomorrow morning.
Precipitation rates to around 1mm/hr (snow rate ~0.5"/hr, based on
forecast snow ratios) are expected south of I-72 with this activity.
The second round late Monday morning into the early afternoon will
be less widespread with the lack of large-scale forcing, but beneath
the upper feature during this time isolated snow showers will
produce some brief additional accumulations of perhaps another half
inch in spots. The other big weather story will be the warmer
temperatures tomorrow. NBM even suggests a 65% chance that high
temperatures will reach the 30s tomorrow in Lawrenceville.
.LONG TERM...(Tuesday through Sunday)
ISSUED AT 247 PM CST Sun Dec 25 2022
Cluster analysis suggests ensemble consensus is for a ridge to be
situated over the western and central Great Plains and a trough
across the Ohio Valley at the start of the extended period, with
some uncertainty developing by Wednesday and especially Thursday in
the rate of eastward translation of the ridge. At this time, it
appears the EC ensemble is on the whole the slowest of the three
extended-period ensembles, with over 1/3 of its members comprising
the most amplified Thursday 500hPa height cluster; meanwhile, the
CMC ensemble is the primary driver of the fastest cluster, which has
the ridge axis shifting into the northeast and a trough developing
in the Plains by Thursday. The slower and slightly more amplified
solution favored by the EPS would mean a longer period of warming
for our area, while the more progressive solution depicted by the
cluster dominated by the CMCE would suggest warming would be
maximized across the mid Atlantic while our section of the country
remains cooler.
All three deterministic models have a surface low developing and
riding northeastward along the western periphery of the ridge as it
slides east of the region at the end of the week, though there`s
been a tremendous lack of both run-to-run and model-to-model
consistency with the location and strength of this low. Some grand
ensemble members even have a few hundred J/kg of CAPE overspreading
central IL during this time period, but confidence is fairly low in
thunder potential. Confidence is higher, however, in precipitation
targeting our area by late week. Every member of both the EPS and
GEFS has some amount of precipitation in Lawrenceville at some point
Friday through Sunday, and several GEFS members have more than 2" of
QPF there by the time it`s all done. At this time, the means of all
three extended ensembles suggest most of the precipitation will fall
south of our area, though if the system were to shift in its track
our area could get in on those heavier amounts. Fortunately,
precipitation type is not a concern during this period, as
temperatures will be far too warm for wintry weather. NBM suggests a
30% chance for max temps equal to or greater than 60F in Springfield
on Thursday, with above average temperatures likely to continue
through at least the first half of the weekend. Depending on the
track and strength of the low, and hence the location and strength
of warm air advection ahead of it, temperatures could wind up way on
the warm side of NBM`s distribution and forecast changes may be
warranted. For now, though, we`ll let it ride given lack of
confidence in the upper pattern and surface low.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 522 PM CST Sun Dec 25 2022
An Alberta clipper low pressure system will track southeast across
the region over the next 24 hours. This will spread -SN and MVFR
ceilings and visibilities over the terminals tonight. Some IFR
visibilities are possible at times in the more intense areas of
snow. Ceilings are forecast to lower to IFR around 13-14z, before
rising back to MVFR later in the afternoon. Periods of -SN should
gradually diminish during the afternoon. With the center of low
pressure passing just southwest of the terminals, winds will
gradually back from southwest this evening to northwest Monday
afternoon, all near/under 10 kt.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...25
SYNOPSIS...Bumgardner
SHORT TERM...Bumgardner
LONG TERM...Bumgardner
AVIATION...25
Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
537 PM CST Sun Dec 25 2022
.UPDATE...
Issued at 507 PM CST Sun Dec 25 2022
Regional radar reflectivity shows the first wave of snow with an
incoming clipper system entering far northwest Missouri at this
hour. While echos extend further south/east, observations do not
report any precipitation given very dry low-levels. However, more
recent observations show wetbulbing (decreasing temperature,
increasing dew point) is occurring and will likely allow for light
snow to begin in the northern CWA in the next few hours. No
changes to the general timing for snow onset tonight. While
accumulations will be on the light side, any snow will stick to
the cold pavement and cause slick roadways.
The potential remains for a brief window of freezing drizzle
tomorrow morning on the back side of this wave, when DGZ relative
humidity drops below 50% within the system`s dry slot and the
low levels remain saturated. However, lift in that saturated,
sub-freezing layer is very weak if existent according to RAP
soundings. Cloud ice is quickly re- introduced aloft when the
upper-level low passes overhead, making the window for any ice
very narrow. The best chances for any freezing drizzle exist
across the Ozarks, where the DGZ remains drier for a longer period
of time.
MRB
&&
.SHORT TERM... (Through Late Monday Night)
Issued at 302 PM CST Sun Dec 25 2022
Key Short Term Message: The most pressing item of interest in the
short term period continues to be the potential for accumulating
snow between late this evening and late tomorrow afternoon.
Confidence remains high that light snow accumulations will occur
across much of the area during this period, but latest guidance
continues to suggest that snow accumulations will remain light.
In the meantime, it has been a chilly but otherwise quiet Christmas
day throughout the area, as well below normal temperatures remain
firmly in place throughout the region. Considering that temperatures
have not even approached the freezing mark since the last
accumulating snow, very little of it has melted yet, and several
locations woke to a white Christmas this morning (1" of snow depth
or more). While quiet weather will persist for at least several more
hours, increasing high level cloud cover is hinting at the approach
of a fast moving shortwave from the northwest, one that is almost
certain to bring another round of widespread but generally light
accumulating snow to the region. While there have been some minor
tweaks to the forecast this afternoon, the main points remain
largely the same, with confidence gradually increasing in the
potential snow amounts across the region.
Beginning late this evening, perhaps as early as 7 or 8 PM across
northeast Missouri, light snow is expected to encroach upon the area
from the northwest, driven largely by isentropic ascent ahead of the
approaching shortwave. In spite of modest warm air advection,
temperature profiles all resoundingly support snow as the
precipitation type, with a healthy portion of the profile at least
initially within the dendritic growth zone. However, this initial
round of snow is expected to be rather progressive and will likely
sweep through almost the entire area before sunrise tomorrow.
Considering both this and the modest forcing mechanism and modest
moisture available (typical of clipper systems), QPF amounts
continue to look rather low. As such, in spite of moderate to high
snow/liquid ratios, total snow accumulations are expected to be
generally light. On the other hand, the combination of at least
moderate snowfall rates for a brief period (2-3 hours), and cold
ground temperatures will allow snow to readily stick to pavement
quickly overnight tonight, potentially creating slick roads for at
least a short period. This will be especially true where surfaces
are untreated.
As this initial round of WAA snow moves southeast of the area,
drying aloft will likely strip away much of the available cloud ice,
and most of the snow will dissipate for at least a brief period. At
this point, model forecast sounding profiles suggest that a brief
period of light freezing drizzle will be possible in some areas,
particularly across the Ozarks. Any freezing drizzle that manages to
develop would likely be of short duration and low intensity, meaning
that any accumulations would likely be restricted to very light
amounts on elevated surfaces.
Sometime between late tomorrow morning and late afternoon, the
surface low will finally move through the area, bringing with it
another round of light snow that will likely add to the already
existing accumulations in some areas. However, neither the coverage
or intensity of this second round of snow is likely to match the
previous round, and temperatures are likely to be much closer to the
freezing mark. As such, while this additional snow may push
accumulations close to the high end of our forecast range,
particularly across far eastern Missouri and western Illinois, we
don`t anticipate significant impacts from this additional snow.
In summary, light snow accumulations remain likely across much of
the area, spread out across roughly 24 hours but falling within
roughly two concentrated periods overnight tonight and during the
day tomorrow. The 10-90th percentiles representing the "best" and
"worst" case scenarios remain generally between a light dusting and
roughly 2 inches, respectively, with a slight preference for the
higher totals across eastern Missouri and western Illinois where the
surface low remains most likely to track. Still there remains a bit
of uncertainty regarding this last point, as a slight change in the
track if the low would likely impact the location of the highest
snow totals. Meanwhile, impacts are expected to be minimal from
freezing drizzle at this point, but will continue to be monitored.
At this time, this event does not look significant enough to warrant
the issuance of a Winter Weather Advisory locally, but considering
the expected holiday travelers and the relative ease with which snow
will stick to roads, at least some marginal impacts are expected.
BRC
.LONG TERM... (Tuesday through Next Sunday)
Issued at 302 PM CST Sun Dec 25 2022
Key Long Term Message: A significant warming trend remains nearly
certain during the middle of the week, while widespread soaking
rain remains very likely from late Thursday through the end of the
week.
The last of the snow will subside by Monday evening as cold, dry
air fills in behind the departing shortwave. While this parting
shot of cold air will lead to a chilly Tuesday morning in the
teens and high single digits, it will be the last such morning for
the foreseeable future.
That is because a significant warming trend is on the way next week,
driven by a wholesale pattern change across the lower-48. As
tomorrow`s system kicks out to the east, a longwave ridge will build
in earnest across the central U.S. Tuesday, and eventually shift
east of the Mississippi river by Wednesday. Likewise, a longwave
trough will develop across the western U.S., placing the Mississippi
Valley region within a regime of southwest flow aloft that will
persist through the end of the week.
This upper flow pattern will allow for two things to occur. First,
the combination of building heights aloft and robust southerly flow
will bring a significant warming trend to the region beginning
Tuesday and kicking into high gear Wednesday and Thursday. While
afternoon temperatures Tuesday will likely still be 5 to 10
degrees below normal, by Wednesday temperatures will jump 15 to 20
degrees to around 5 to 10 degrees ABOVE normal. This continues
even further into Thursday, with temperatures expected to climb
into the 60s. This is also supported by very narrow temperature
spreads among ensemble guidance, leading to a high confidence
forecast for this mid-week warmup.
Secondly, the persistence of southwesterly flow aloft and the
northward transport of Gulf moisture will bring about the return of
widespread rainfall over the latter half of the week, beginning with
the passage of a shortwave late Thursday. While there remains a non-
trivial amount of spread among ensemble members, confidence is very
high that widespread rainfall will occur across much of the area
between late Thursday and late Saturday, with a slight preference
for the eastern half of Missouri and much of Illinois. While there
will very likely be dry periods within this window, the more
specific timing details within this period remain highly uncertain.
The same applies to potential amounts, but considering the potential
for multiple rounds of rainfall and high precipitable water content
(~90th percentile), soaking rain is very likely for a large portion
of the region.
BRC
&&
.AVIATION... (For the 00z TAFs through 00z Monday Evening)
Issued at 507 PM CST Sun Dec 25 2022
VFR conditions will give way to MVFR ceilings areawide overnight
as a clipper system brings snow to the region. Brief instances of
VSBY reductions down to IFR are likely with the main band of snow
at KUIN and the St. Louis metropolitan terminals overnight. There
will be a definitive break in the precipitation during the morning
on Monday, however another bout of light snow is possible at the
St. Louis terminals during the afternoon with the passage of the
upper-level and surface low. It appears that, other than the pre-
existing MVFR CIGs and a wind shift to the northwest, there will
be no other notable impacts with this final round of
precipitation. CIGs will likely begin to improve during the late
evening on Monday beyond the current TAF period.
MRB
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&
$$
WFO LSX
Area Forecast Discussion
National Weather Service Marquette MI
719 PM EST Sun Dec 25 2022
.SHORT TERM...(This evening through Monday)
Issued at 236 PM EST SUN DEC 25 2022
Water vapor imagery and RAP analysis show a deep mid-level low
centered just e of James Bay. At the sfc, weakening 983mb low is
colocated with the mid-level low. With the system slowly moving
farther away and weakening, winds are slowly gradually relaxing
across Lake Superior and Upper MI this afternoon. Out on the lake,
winds are still gusting to around 35kt across the central and e,
but should diminish blo gales in the next hr or two. KMQT radar
still shows several moderate LES bands from Munising area
eastward, but reflectivities within these bands are weakening and
the bands are becoming more spaced apart due to the increasing
influence of ridging/drier air from north and west of Lake
Superior. Northwest winds will continue to gradually weaken into
this evening and expect LES bands to continue weakening as well
over the nw snow belts. As for headlines, only the eastern zones
of Alger, northern Schoolcraft and Luce have a winter weather
advisory headline thru 00Z and that still looks reasonable. Don`t
think the evening shift will need to extend that headline based on
radar trends, webcams and fcst model soundings.
.LONG TERM...(Tonight through Sunday) Issued at 218 PM EST SUN
DEC 25 2022
Father Christmas` gift to da Yoop is a much quieter period of
weather tonight and into this coming week across the forecast area
then the past few days. Continued lake effect snow showers are
expected through Monday night. More widespread coverage of showers
is expected across the east. Overall, accumulations should be on the
light side, generally 1-3 inches of fluffy snow with a couple areas
potentially seeing a little more in the east. A weak shortwave
moving through the region Monday night may support a synoptic uptick
of snow showers in the east for a few hours, but guidance pushes
these bands offshore through the night as the next system drifts
toward the Upper Great Lakes and southwest flow develops.
Warm front associated with a system approaching the Upper Great
Lakes will lift into the forecast area Tuesday. 0z determinstic`s
differed on where the better forcings will line up, and the 12z
appears to be honing in on a potential solution. Its possible the
forecast area could see a wave of moderate wetter snow Tuesday
evening, with the best chances for impacts being in the eastern U.P.
Guidance suggests the frontal boundary could stall in the vicinity
as another low dissipates to our southwest. At this point, a
majority of the solutions suggest the boundary would settle over
northern Lake Superior or Ontario, suggesting continued WAA ahead of
the next low moving into the region toward the end of the week. This
low is progged to lift northeastward through the region Thursday
night. GEFS, GEPS, and EPS membership haven`t really honed in on
where the low will track, but the ensemble means of each suggest the
low may end up tracking near the Arrowhead. This would put us within
the warm sector of the system, suggesting that rain or a wintry mix
would be the dominate precip type Thursday and Friday.
Another low looks to follow into the Great Lakes the Saturday/Sunday
time period, which could impact New Year`s Eve and Day holiday
plans. Similarly to the preceding low, there`s still a good bit of
spread of where the low could track and potential outcomes. However,
much like the preceding system, there appears to be a potential for
rain or a wintry mix being the predominate precip type if it moves
through the region.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 719 PM EST SUN DEC 25 2022
There has been improvement from IFR to MVFR, but MVFR ceilings will
persist through tomorrow morning at all TAF sites in nw flow.
However, the snow and gusty winds have diminished with 12 to 15 kt
sustained speeds only continuing through Mon 03Z at KIWD and KCMX.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 218 PM EST SUN DEC 25 2022
Vessel observations from those exiting the Duluth Harbor this
morning were mainly ~20kt winds while observations elsewhere were
still blowing 35-50kts. By early afternoon most sites were either
below gale or below 40kts. Expecting continued diminishment of the
winds for the remainder of the afternoon and into next week. By
Monday morning, 10m winds lake-wide are expected to be 25kts or
less. Expecting these light winds to persist until Monday night,
when southwesterly and westerly winds increase ahead of the next
system. Guidance continues to suggest a winds ~30kts and some low
end gale gusts are expected by Tuesday afternoon, mainly across the
eastern half.
As winds continue to improve today, the colder airmass overhead
should persist until southwest flow develops late Monday
night/Tuesday. This should support improving ice accretion rates
across the lake through this period. With this said though, isolated
heavy and more widespread moderate freezing spray potential can`t be
ruled out today/tonight.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...Voss
LONG TERM...JTP
AVIATION...TDUD
MARINE...JTP
Area Forecast Discussion
National Weather Service Nashville TN
831 PM CST Sun Dec 25 2022
...New UPDATE...
.UPDATE...
Issued at 822 PM CST Sun Dec 25 2022
A few of the latest incoming models have amped up the snowfall in
our northwest for tomorrow. Light snow accumulation could occur in
that area as early as the pre dawn hours. Went ahead and updated
the SPS and HWO to hit this a little harder. Latest grid updates
suggest snowfall amounts for Monday of three quarters of an inch
for our northwest...a dusting for our far south...and one half
inch amounts possible elsewhere.
Otherwise, the latest grids look to be in good shape. Current pops
do reach 40% for Stewart county just prior to 12Z. As mentioned
earlier, updated the HWO and SPS to hit this situation a little
harder. Hrrr and Nam nest have ticked upward with those northwest
snow amounts. Will advise midnight shift to examine the latest out
of WPC and issue an advisory if necessary.
&&
.SHORT TERM...
(This afternoon through Monday Night)
Issued at 246 PM CST Sun Dec 25 2022
Mid state will continue to remain dry through evening hours
tonight. Quick clipper type of storm system will move across
our area late tonight into Monday. It should bring some
accumulating snowfall amounts with highest amounts of around one
quarter to around one half of an inch for locations north of I-40,
especially for those locations west of I-24. Temperatures look
like they will finally climb above freezing on Monday. A change
over to rain showers could be possible for locations around and
west of I-65 Corridor during the late afternoon hours. As
temperatures once again go below freezing, isolated snow showers
should continue into evening hours before tapering off from
southwest to northeast as an upper level trough passage follows
behind this upper level disturbance. Lows tonight will be warmer
than those last night mainly spanning mid teens. Highs on Monday
should rise into low to mid 30s west of Cumberland Plateau Region
with temperatures across Plateau still slightly below freezing.
Although continued seasonably cold lows expected Monday night,
the slight warming trend will continue with lows mainly around
20 to lower 20s. A special weather statement was issued earlier
this afternoon to provide additional details on this potential
of accumulating snowfall across our area late tonight into
Monday. Some additional slick spots will be possible, but no
widespread travel issues are expected as of this time.
&&
.LONG TERM...
(Tuesday through next Sunday)
Issued at 246 PM CST Sun Dec 25 2022
Long term forecast period will be highlighted by warming
temperatures and increasing rainfall chances as second half
of week into at least first part of upcoming holiday weekend.
Initially it is looking like one to two inches of rainfall could
occur across our area Thursday through Saturday as shower chances
increase, with isolated to scattered showers continuing across
mid state region Saturday night into New Years Day. The reason
behind this significant change in the atmospheric pattern is that
a surface frontal system will begin to develop across central
contiguous U.S. as Tuesday progresses and slowly shift eastward
as weekend progresses. A possible surface frontal passage late
Saturday night could occur. Development of this pattern will allow
low level warm air advection to become increasingly established
across our area. Deep upper level troughing developing across
western contiguous U.S. by mid week will usher in southwesterly
flow aloft as also this upper level system slowly shifts eastward.
Highs by next Saturday afternoon could be as warm as low to mid
60s, upper 50s Cumberland Plateau Region with just slightly cooler
temperatures expected on New Years Day.
&&
.AVIATION...
(00Z TAFS)
Issued at 511 PM CST Sun Dec 25 2022
VFR conditions will continue through the evening and overnight
hours with light SSW winds. A weak system will bring scattered
light snow showers on Monday (after 12Z). Some episodes of MVFR
cigs/vsbys will occur, but these episodes will be too brief and
transient to include in tafs for BNA and MQY. CKV and CSV are
more likely to keep MVFR and perhaps some brief IFR within some of
the snow showers.
&&
.PRELIMINARY POINT TEMPS/POPS...
Nashville 16 36 23 42 / 10 40 20 0
Clarksville 15 36 20 38 / 40 50 20 0
Crossville 10 31 19 40 / 0 30 20 0
Columbia 14 36 20 42 / 10 30 10 0
Cookeville 12 32 22 40 / 0 40 20 0
Jamestown 10 31 19 40 / 0 40 20 0
Lawrenceburg 14 35 21 43 / 0 30 10 0
Murfreesboro 13 35 21 42 / 10 30 20 0
Waverly 15 35 21 38 / 40 40 20 0
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE.......21
SHORT TERM...JB Wright
LONG TERM....JB Wright
AVIATION.....13