Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/27/24
Area Forecast Discussion
National Weather Service Charleston SC
912 PM EST Tue Nov 26 2024
...DENSE FOG POSSIBLE OVERNIGHT...
.SYNOPSIS...
A cold front will move through tonight, followed by a stronger
cold front Thursday night. Cold high pressure will build across
the area Friday through Tuesday.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
Lingering shower activity ahead of a weak cold front pushing off
the coast is poised to clear the coast by 10 PM. Expect rain-
free conditions to prevail for the remainder of the night.
A secondary, backdoor front looks to drop south through North
Carolina and the Pee Dee of South Carolina overnight and will
ooze into the southern South Carolina counties prior to daybreak
Wednesday. A pronounced pooling of low-level moisture is noted,
especially in the near term high-res models such as the RAP and
H3R. Widespread stratus is expected to form ahead of the front
with guidance now beginning to trend towards more of a stratus
build-down scenario with areas of fog developing overnight. It
is not exactly clear how widespread this fog will become, but
with the boundary layer now decoupled and both the RAP and H3R
now showing pretty favorable 1000 hPa condensation pressure
deficits developing, it does appear fog is becoming increasingly
likely. In fact, mid-evening AWOS observations confirmed by
local warning point reports out of Bulloch and Screven Counties
show patchy dense fog has already formed across interior parts
of Southeast Georgia. This will likely expand over the coming
hours and could become dense enough that a Dense Fog Advisory
may be needed for some areas overnight.
For the late evening update, "patchy" to "areas of fog" were
introduced for most areas with greatest potential for dense fog
setting up somewhere in a corridor from roughly Walterboro
south to Statesboro and Springfield down to near Hinesville and
Claxton. Again, confidence remains low on exactly how the fog
situation will unfold, but the evening update has started a
foggier trend. Lows from the lower-mid 50s inland to the upper
50s/lower 60s at the coast look on track.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY/...
Wednesday: High pressure will briefly reside across the local area
with a nearly stationary front draped over southern areas of just
south of the Altamaha River during the day that eventually lifts
north as a warm front late day into early night. This will favor dry
conditions with a light south/southwest flow supporting afternoon
highs in the low-mid 70s (warmest across Southeast Georgia).
Overnight lows will also remain mild with a southerly flow in place,
generally only dipping into the mid-upper 50s inland and north to
lower 60s near the coast and along/south of I-16 across Southeast
Georgia.
Thursday (Thanksgiving Day): This will likely be the most
active weather day in regards to precip chances. Aloft, a large
mid- upper lvl trough will dive across the East Conus with a
leading h5 shortwave sweeping across the Mid-Atlantic and
Southeast States late day. At the sfc, a strong cold front will
progress east, likely to impact the local area early night.
Ahead of the front, south- southwest flow will help advect
warmer air and greater moisture to the region with sfc temps
approaching the mid-upper 70s and PWATs near 1.5 inches during
the afternoon. This should lead to a modestly unstable
environment while 0-6km bulk shear approaches 50-60 kt. However,
a severe weather risk will remain somewhat conditional based on
cloud cover potentially limiting instability across the region
during the day and the arrival of greatest forcing with the sfc
front occurring during night-time hours. Given recent trends,
scattered showers along with a few thunderstorms should begin to
arrive across inland areas late day, then make progress
eastward during the evening. A few of these thunderstorms could
be strong and/or severe with damaging wind gusts being the
primary concern given stronger low-lvl wind fields near the
timing of fropa. However, thunderstorm activity will likely need
to have developed upstream to the local area during daylight
hours, then move into the area before nightfall to maintain
stronger characteristics. Once fropa occurs, any potential for
severe weather will come to an end. Overnight lows should dip
into the mid-upper 40s inland to lower 50s closer to the coast.
Friday: A considerably drier and cooler day will be in place as
high pressure builds across the region behind a cold front well
offshore. Expect dry conditions under mostly sunny skies by the
afternoon, but cold air advection leading to afternoon highs
only in the upper 50s to lower 60s.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
Cold high pressure will prevail Friday night through Sunday,
followed by reinforcing high pressure early next week. A period of
well below normal temperatures is in store. Friday night could see
temps dip just below freezing over inland areas, with widespread
frost for much of the rest of the area due to calm winds and low/mid
30s low temps. A similar setup is expected Saturday night, Sunday
night and Monday night where we could see low temps in the low to
mid 20s with a hard freeze in many areas, especially Monday night
when the local area is positioned along the base of a mid-lvl trough.
&&
.AVIATION /02Z WEDNESDAY THROUGH SUNDAY/...
27/00z TAF Discussion:
KCHS/KJZI: VFR will prevail for much of the 00z TAF period.
There are low probabilities that a period of MVFR cigs could
occur, mainly 08-11z, ahead of southward moving secondary cold
front. Most of the near term guidance keeps the bulk of this
activity south of both KCHS and KJZI so no mention was included
for the 00z TAFs.
KSAV: VFR will give way to MVFR cigs after midnight as low-level
moisture pools ahead of a southward moving secondary cold front.
Cigs were limited to MVFR for now, but some data do suggest a
period of IFR cigs could occur, mainly from 06-10z. Opted to
not include a mention at this time and maintain a scattered deck
around 600 ft given most of the near term statistical guidance
does not show cigs quite that low. Amendments may become
necessary if trends suggest IFR cigs become more likely.
Extended Aviation Outlook: Flight restrictions are possible
Wednesday due to low clouds, followed by additional flight
restrictions due to low clouds and/or showers/thunderstorms late
Thursday afternoon into early Friday. VFR conditions should then
prevail during the weekend.
&&
.MARINE...
Tonight: Southwest winds early this evening will become more
north and northwest overnight following a cold frontal passage.
Despite fropa, winds stay relatively benign, diminishing to 10
knots or less. Seas will subside to 1-2 feet overnight.
Wednesday though Sunday: A nearly stationary front located
across or just south of the region on Wednesday will lift north
as a warm front late Wednesday, leading to conditions that
remain below Small Craft Advisory levels into at least early
Thursday. Low-lvl wind fields should be on the increase heading
into Thursday afternoon well ahead of a cold front arriving
Thursday night. Wind gusts could approach Small Craft Advisory
levels across northern South Carolina waters off the Charleston
County Coast, but warm air advection should limit the potential
of a longer duration event requiring a Small Craft Advisory late
day/early night. However, once the strong cold front pushes
across coastal waters Thursday night, there could be another
wind surge that requires Small Craft Advisories into early
Friday. Conditions are then expected to improve by late morning
Friday and remain below Small Craft Advisory levels through
Sunday as high pressure builds across local waters.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...None.
&&
$$
Area Forecast Discussion
National Weather Service Cleveland OH
1003 PM EST Tue Nov 26 2024
.SYNOPSIS...
High pressure slides through the Ohio Valley tonight before exiting
east on Wednesday. Low pressure tracks through the Ohio Valley
Wednesday night into Thursday. Cold air flows in behind this low
pressure beginning Thursday night and into the weekend.
&&
.NEAR TERM /THROUGH WEDNESDAY NIGHT/...
10:00 PM Update...
Thumbing through the latest 00Z hi-res model data, there seems
to be a slight trend towards a little bit more snow with the low
pressure system as QPF trends upward and temperatures trends
slightly cooler. Model mean suggested a swath of 0.5-1.5" of
snow accumulation southeast of a Erie, PA to Marion, OH line.
Previous Discussion...
Quiet weather tonight into Wednesday morning as weak high pressure
slides through the Ohio Valley. Lows tonight generally in the upper
20s and lower 30s, warmer along the eastern lakeshore. We are
finally seeing a nice window of clearer skies and sunshine this
afternoon, though high clouds will begin to build in and lower
tonight into Wednesday morning.
Weak low pressure will track through the Ohio Valley Wednesday night
into Thursday morning before shifting towards the East Coast on
Thursday. Some light rain showers are possible Wednesday afternoon
within some mid-level warm air advection/isentropic lift ahead of
the approaching shortwave and developing low pressure. However,
greater precip potential is evident beginning Wednesday evening and
into Wednesday night as we get into an expanding shield of light to
moderate precipitation on the northwest side of the developing low
pressure in the Ohio Valley. Models still slightly disagree on how
consolidated pieces of vorticity within the shortwave trough will
be, leading to some disagreement over how strong the low will be, how
intense lift is within the shield of precipitation and how far
northwest the precipitation gets. The difference is evident between
runs such as the 12z ARW/HRRR and 18z NAM, which offer the stronger
solution, and the 12z NAM/RGEM, which offer the relatively weaker
solution. The 12z European model and 18z HRRR offer a bit of a
middle ground solution and are closest to the current forecast.
In terms of what this all means, there`s fairly high-confidence that
much of the area will see a period of light to moderate cold rain
mixed with wet snow late Wednesday through early Thursday. Daytime
highs Wednesday will be in the low to mid 40s, with lows Wednesday
night ranging from the lower to upper 30s, right on the fence of
rain vs snow. Confidence in seeing any precipitation does begin to
lower into the Toledo area. The weaker solution would keep QPF
amounts under 0.25" area-wide, while the stronger option could
yield up to a few tenths of an inch of QPF, especially across our
southern and southeastern counties where the greatest overall QPF is
expected. Models that depict the stronger system depict a band of
mid-level frontogenesis getting into our southern counties, which
could lead to a narrow corridor of banded precipitation. The weaker
solution would generally lead to a lighter precip shield with a
sharper northwest edge to the precip somewhere west of I-71.
In terms of precip type specifics and any snow amounts/impacts,
generally expect snow to be of lower-impact though the forecast
does have some complexity. Surface temperatures will start well-
above freezing and may not get to freezing outside of the highest
terrain. However, 925mb temperatures will fall below 0C 3-6z, with
a bit of room for surface temperatures to wet-bulb as steadier
precip arrives (though dew points won`t be extremely low, so this
won`t be dramatic). This generally gets us to a point where steadier
precip should allow locations above 1000 feet in elevation could see
snow mix in starting 3-6z and then through the night...however,
lower elevation locations seeing any snow and hillier locations
seeing any accumulation would depend on seeing enough banded precip
to get stronger dynamic cooling and greater precipitation rates.
Models such as the 18z NAM and 12z HRRR/ARW, with more amplified
solutions, would support a 1 to 3 inch type accumulation in the
higher terrain of interior Ohio and northwestern Pennsylvania, with
little to no accumulation in the lower terrain (but likely flakes
for most of the area). Weaker solutions, such as the 12z NAM/RGEM,
would probably bring snow flakes to hillier locations but with
little to no accumulation, with the lower elevations staying mainly
or all rain. While one solution is slightly more exciting than the
other for fans of winter weather, neither solution is a huge impact
or accumulation. Given that just slight differences in the handling
of the shortwave energy are what is causing the differing model
solutions, our forecast offers a middle ground that leans on the
conservative side, showing accumulations of up to 1" in the higher
terrain and a rain/snow mix with little to no accumulation below
about 1000 feet in elevation. Trends in upcoming suites of guidance
will be monitored for continued tweaks.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
W`erly flow aloft is expected on Thanksgiving. Within this flow, a
prominent shortwave trough is still expected to advance E`ward
through our CWA during the morning through early afternoon, which
will allow the attendant and deepening surface low to shift NE`ward
from the Mid-Atlantic region toward Cape Cod between daybreak and
nightfall as an occluded front slides E`ward through our region and
ushers-in a much colder air mass, albeit gradually at first.
Widespread precip associated with frontogenetical forcing for ascent
within the low pressure system`s TROWAL and moist isentropic ascent
ahead of the shortwave trough`s axis will exit E`ward during the
morning through early afternoon. A relatively-deep surface-based
melting layer will allow precip to fall mainly as rain, but a few
wet snowflakes may mix-in, especially during the early morning and
early evening. No snow accumulation is expected. In addition, a
sufficiently-cold/moist mean low-level flow over/downwind of ~10C
Lake Erie is expected to back from N`erly to NW`erly and allow lake-
effect precip to impact most of our CWA. Daytime highs are expected
to reach the upper 30`s to mid 40`s.
Behind the aforementioned, prominent shortwave trough, a deep
mid/upper-level longwave trough associated with an unusually-cold
air mass becomes established over eastern Canada and the eastern
United States Thanksgiving night through Friday night, which will
allow cyclonic W`erly to NW`erly flow aloft and additional, embedded
shortwave disturbances to affect the eastern Great Lakes and Upper
OH Valley. At the surface, a trough lingers over/near our region.
Low-level CAA will occur in earnest and allow 850 mb temperatures
initially near -7C to drop to near -10C to -13C over ~10C Lake Erie
and our CWA as low-level moisture remains abundant and deep. Lake-
induced CAPE is expected to increase to at least moderate
magnitudes. Given the aforementioned CAA and wet-bulb effect, lake-
effect precip, mainly in the form of snow, is expected in/near the
snowbelt of NE OH and NW PA as mean low-level flow backs from
NW`erly to W`erly Thursday night and then varies between primarily
WSW`erly and WNW`erly on Friday through Friday night, which will
allow the LES to become focused in/near the primary snowbelt. The
aforementioned shortwave disturbances traversing our area will cause
the mean low-level flow direction to fluctuate. Given the expected
thermodynamics, a projected cloudy DGZ of about 1 km thick, and
expectation for strong/maximized ascent at a lake-effect cloud
temp of ~-10C per model soundings in BUFKIT, efficient snow
production and periods of steady to heavy snow are expected. At
least several inches of snow accumulation are expected where
the heaviest/most-persistent LES occurs, which will likely be
in/near the primary snowbelt. Moist isentropic ascent preceding
shortwave trough axes will allow periods of lighter snow with minor
snow accumulations to occur outside the LES. Stay tuned for forecast
updates, including eventual winter WX alerts. Overnight lows are
expected to reach mainly the mid 20`s to lower 30`s around daybreak
Friday and be followed by Friday afternoon highs in mainly the lower
to mid 30`s. Overnight lows should reach mainly the 15F to 25F range
around daybreak Saturday.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
The deep mid/upper-level longwave trough is expected to persist over
eastern Canada and the eastern United States through the long-term
period. This will allow cyclonic W`erly to NW`erly flow aloft and
embedded shortwave disturbances to continue to affect our CWA as an
unusually-cold air mass remains entrenched across the Great Lakes
and OH Valley. At the surface, a trough lingers over/near the Great
Lakes, including our CWA. Daily afternoon high temperatures are
expected to reach roughly the 25F to 35F range and daily low
temperatures are expected to range from the mid teens to upper 20`s
around daybreak Sunday, Monday, and Tuesday, respectively.
Temperatures at 850 mb near -9C to -13C over/downwind of ~10C Lake
Erie, abundant/deep low-level moisture on the synoptic scale, and
sizable lake-induced CAPE are expected to allow LES, steady to heavy
at times, to persist over/downwind of Lake Erie. Based on the latest
projected evolution of relevant shortwave disturbances, mean low-
level flow should vary between W`erly and SW`erly on Saturday into
the first-half of Sunday. Later on Sunday through Monday night, mean
low-level flow should vary between W`erly and NW`erly before
potentially backing to SW`erly on Tuesday. Periods of steady to
heavy LES are expected to impact the snowbelt of NE OH/NW PA and
vicinity when mean low-level flow is W`erly or NW`erly. Significant
and impactful snow accumulations are possible, but exact snowfall
totals remain uncertain. Stay tuned for forecast updates. Moist
isentropic ascent preceding shortwave trough axes will allow periods
of lighter snow with minor snow accumulations to occur outside the
LES.
&&
.AVIATION /00Z Wednesday THROUGH Sunday/...
VFR will continue through the TAF period as high clouds stream
in tonight as low pressure begins to approach from the west.
Should gradually see thickening of the clouds through the day
Wednesday with some precipitation starting to approach southern
TAF sites such as KFDY, KMFD, and KCAK right towards the end of
the TAF period. KMFD has the best chance at seeing precipitation
first so added a VCSH mention right at 23Z. It should initially
fall as rain, though there is a low chance it falls as a
rain/snow mix.
West-southwest winds of around 8 to 10 will continue through the
next couple hours will generally ease to 5 to 8 knots tonight,
though lakeshore areas, including KERI, will stay a bit windier.
Winds gradually become between south and southwest during the
day Wednesday.
Outlook...Non-VFR likely in rain and/or snow Wednesday night
through Thursday and with a transition to lake effect snow
Thursday night through at least Saturday. Lake effect snow is
most likely in the primary snowbelt of Northeast Ohio and
Northwest Pennsylvania.
&&
.MARINE...
Gale Warning in effect until 10 PM this evening for all U.S. waters
from Conneaut to Buffalo. Small Craft Advisory in effect until 1 AM
Wednesday from Maumee Bay to Vermilion; until 7 AM Wednesday from
Vermilion to Avon Point; until 10 AM EST Wednesday from Avon Point
to Conneaut.
A low meanders near James Bay through tonight as a ridge builds over
Lake Erie from the Lower OH Valley. The interaction between the low
and ridge will allow W`erly winds as strong as 25 to 35 knots
through this early evening to ease to 10 to nearly 20 knots and
become SW`erly to W`erly by daybreak Wednesday. Waves as large as 4
feet in the western basin and as large as 7 to 14 feet farther east
will subside gradually so that by daybreak Wednesday, waves are
expected to subside to 2 feet or less in the western basin and 6
feet or less farther east.
The aforementioned low will weaken and meander near James Bay
through Saturday before drifting E`ward on Sunday. Otherwise, the
aforementioned ridge will exit gradually E`ward on Wednesday through
Wednesday night as a separate low moves from the south-central U.S.
toward the Mid-Atlantic states and strengthens. S`erly to W`erly
winds around 5 to 15 knots on Wednesday are expected to become
variable around 5 to 10 knots Wednesday night as the southern low
begins to extend a weak trough over the Lake Erie region. Waves are
expected to subside to 3 feet or less by sunset Wednesday evening.
An occluded front will sweep E`ward across Lake Erie on Thanksgiving
as the southern low moves NE`ward from the Mid-Atlantic states to
the Canadian Maritimes and deepens further by daybreak Friday.
Behind the occluded front, a trough lingers over Lake Erie through
this Sunday. As the occluded front moves E`ward across Lake Erie on
Thanksgiving, variable winds around 5 to 10 knots ahead of the front
become NW`erly to N`erly around 10 to nearly 20 knots. Waves are
forecast to remain primarily 3 feet or less, but occasional 4
footers are possible in the central basin, where fetch will be
greater. Winds are expected to be primarily WNW`erly to WSW`erly and
around 15 to 25 knots Thursday night through Friday, although winds
are forecast to reach 30 knots at times on Friday. Waves are
expected to build as large as 3 to 6 feet Thursday night and as
large as 5 to 10 feet on Friday through Sunday, especially in the
central and eastern basins. Another Small Craft Advisory will likely
be needed.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...None.
PA...None.
MARINE...Small Craft Advisory until 1 AM EST Wednesday for LEZ143-144.
Small Craft Advisory until 4 AM EST Wednesday for LEZ145.
Small Craft Advisory until 10 AM EST Wednesday for LEZ146>149.
&&
$$
SYNOPSIS...Sullivan
NEAR TERM...Saunders/Sullivan
SHORT TERM...Jaszka
LONG TERM...Jaszka
AVIATION...Saunders
MARINE...Jaszka
Area Forecast Discussion
National Weather Service Quad Cities IA IL
757 PM CST Tue Nov 26 2024
.KEY MESSAGES...
- No travel impacts expected ahead of the Thanksgiving holiday.
- Rain chances decreasing Wednesday, with only a chance (20-40%)
across northeast MO, west central IL, and southeast IA.
- Turning colder late week and into the weekend, with wind chills
in the single digits above and below zero.
- Clipper system Saturday may bring snow to southern IA and
northeast MO.
&&
.UPDATE...
Issued at 751 PM CST Tue Nov 26 2024
Returns on radar up near ALO are associated with a fgen band.
There is strong omega in the DGZ resulting in elevated snow
production. This strong DGZ forcing should continue through 06z
and then slowly taper off and move to the east. Overall cloud
bases remain high and saturation is of question. That said, the
00z RAP does show saturation down to the sfc. A report of
graupel in Story County in an area of weaker forcing suggests
that we may saturate in that heavier snow band along highway 20.
Still not entirely sure but have added schc pops there. The
faster we saturated, the more likely there could be some
accumulations. If this were to occur we could see a few tenths
of an inch of snow. We would expect to see snow in the next hr
or two. Otherwise, maybe a dusting if saturation occurs closer
to 06z.
&&
.SHORT TERM /THROUGH TONIGHT/...
Issued at 205 PM CST Tue Nov 26 2024
Clear skies, light wind, and dry low levels that was evident on
our 00z DVN sounding, allowed temperatures to drop into the
upper teens and lower 20s this morning. This was the coldest
start since late March for the CWA. Water vapor imagery depicted
two upstream shortwaves of interest, one near the US/Canadian
border in MT and another now onshore in northern CA. Visible
satellite loops showed the cirrus shield over the central Plains
making its way into Iowa today. After a cold start,
temperatures at 1 pm have risen into the mid to upper 30s.
Rest of today...increasing clouds to put a damper on temps rising
much more through the afternoon. Highs will top out in the upper
30s and lower 40s.
Tonight...dry and quiet conditions will continue, as high
pressure ridge slides east into the Ohio river valley.
Temperatures will only drop into the upper 20s and lower 30s
overnight given the expected cloud cover.
&&
.LONG TERM /WEDNESDAY THROUGH TUESDAY/...
Issued at 205 PM CST Tue Nov 26 2024
The forecast continues to trend drier and further south with the
storm system Wednesday. The latest 12z deterministic ECMWF has
now come into better agreement with its ensemble mean and the
GFS/NAM/GEM solutions taking the surface low from northeast NM
at 12z Wed to northeast AR at 00z Thu. This track would keep the
bulk of any precipitation to our south and also agrees with the
available 12z CAMs. 1000-500mb RH progs also suggest moisture
depth will be lacking with precipitation struggling to reach the
surface. I have maintained 15-40% PoPs across our far south,
but if models continue to trend south these may still be too
high. Forecast soundings and ground temps show that if precip
occurs, it would be light rain and thus no travel impacts are
expected in the CWA prior to Thanksgiving.
Thanksgiving...high pressure to bring dry conditions and below
normal temperatures in the low to mid 30s. Brisk northwest winds
to make for a rather chilly day outside.
Thursday night-Monday...coldest air of the season still on tap to
move into the region during the period. Ensemble mean 850mb temps
to drop into the -12 to -14C range on Friday and stays below
minus 8C. This will bring a prolonged period of highs below
freezing, which we have not seen since the middle of January!
Wind chills will drop in the single digits above and below zero.
Be sure to bundle up outside! A clipper system will drop south
across the northern Plains Friday night into Saturday bringing a
chance of light snow to portions of IA and MO. At this time,
the highest chances (30-40%) are south of a line from Sigourney,
IA to Macomb, IL. The rest of the extended will be will be cold
and dry.
&&
.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 536 PM CST Tue Nov 26 2024
VFR conditions are expected through the period as clouds will
remain above 3000 feet. Winds will be light as well. No sig wx
impacts to aviation expected.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...None.
IL...None.
MO...None.
&&
$$
UPDATE...Gibbs
SHORT TERM...Gross
LONG TERM...Gross
AVIATION...Gibbs
Area Forecast Discussion
National Weather Service Sioux Falls SD
948 PM CST Tue Nov 26 2024
.KEY MESSAGES...
- Low chances (10%-20%) for light snow Wednesday mostly across
the Hwy-14 corridor. Accumulations up to a tenth or two will
be possible especially across our higher elevations areas.
- Below normal temperatures will continue through the weekend
with highs expected to drop below freezing from Thanksgiving
day onwards.
- Winds will vary from light to slightly breezy. Wind chills
will be cold, in the single digits to teens, through the
weekend.
&&
.DISCUSSION...
Issued at 233 PM CST Tue Nov 26 2024
Current satellite shows clouds flowing in from the southwest. South
of I-90, partly cloudy skies will become mostly cloudy through the
evening. North of I-90, will see mostly sunny skies become partly
cloudy. Overnight lows will fall into the teens to 20s with the
warmest lows south of I-90 in northwestern Iowa.
Wednesday will dawn partly to mostly cloudy. A short wave trough is
expected to pass over the area bringing low (<20%) probabilities for
light snow Wednesday morning through the afternoon. Ensemble trends
have backed off on how far south the snow will penetrate, keeping
the chances for flurries from I-90 north, and light snow along and
north of Highway 14. Any accumulations are expected to remain very
light, a dusting to a tenth or two in total. Light snow is expected
to clear the area by the afternoon. Flow at the surface will
transition from easterly to northerly, bringing south cold air from
the Canadian Plains. Highs are only expected to reach the mid 20s to
30s, with the warmest air lingering along and south of Highway 20
where highs could reach the mid 30s. Though winds overall will
remain light, wind chills will still dip into the teens and 20s.
Overnight lows will once again be cold, in the teens.
The northwesterly pattern aloft continues for Thanksgiving day as we
watch another shortwave round the bend of the upper trough situated
over the northern Great Lakes region. Enough moisture is present in
the midlevels to result in clouds, but is unlikely to produce any
snow beyond a few flurries. It will, however, bring south another
push of cold air advection that will reduce our highs even further,
into the low to mid 20s north of I-90, and mid to upper 20s south.
Northwesterly surface winds are expected to increase through the
morning becoming mildly gusty for the afternoon. Gusts between 20-25
mph will result in wind chills dropping to the single digits to low
teens. Overnight lows will fall into the single digits.
A very similar short wave will pass through Friday, bringing yet
another push of cold air advection and dropping highs even lower, in
the teens to mid 20s. Winds will very gradually taper off overnight
into Saturday morning. For those of you who have plans to go look at
lights around town, wind chills will be cold, in the single digits
to a few degrees below zero along and north of Highway 14. Be sure
you dress accordingly if you are venturing out.
Another shortwave Saturday morning brings low chances for light
snow, this time along and south of Highway 18. General lack of
moisture will keep any accumulations light. Thanks to continued
northwesterly flow at the surface, highs for Saturday and Sunday
will peak in the teens to low 20s. A weak ridge aloft Monday and
Tuesday begins a slight warming trend for the first half of the
week, warming us into the mid to upper 20s. While slightly warmer,
these highs are still around 10 degrees cooler than average for this
time of year, which is generally in the mid to upper 30s.
&&
.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 947 PM CST Tue Nov 26 2024
For the most part VFR conditions are expected through the
taf period. The Nam and Rap are more aggressive in bringing some
IFR to possibly LIFR ceilings to areas north of I-90 and will
include some lower conditions in these areas. The better chances
will be through early tomorrow afternoon. Confidence a little
too low to include at the FSD location and looks like the bulk
will remain north of the airport but suspect areas along and
just south of I-90 will see about a 10-30 percent chance for
these lower conditions, right on the edge, especially from about
11z through 15z. Otherwise some patchy flurries will be
possible north of I-90 on Wednesday morning but the impacts
should be minimal.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
IA...None.
NE...None.
&&
$$
DISCUSSION...AJP
AVIATION...08
Area Forecast Discussion...Updated Aviation
National Weather Service Lincoln IL
500 PM CST Tue Nov 26 2024
.KEY MESSAGES...
- While much of the precipitation on Wednesday will be rain, a
transition to a rain/snow mix is expected after sunset. Some
minor accumulations are expected in east central Illinois, with
potential for a narrow axis of heavier accumulations.
- A long spell of unseasonably cold air will prevail from Friday
into the middle of next week, with high temperatures likely to
remain below 30 degrees during this period.
&&
.SHORT TERM... (Through Thanksgiving Day)
Issued at 235 PM CST Tue Nov 26 2024
Main forecast challenge is with the potential for mixed
precipitation on Wednesday afternoon and night, along with
placement of any mesoscale snow bands.
Early afternoon satellite imagery shows mid and high clouds
streaming into the area, with any heights below 10,000 feet still
back in eastern Nebraska. Forecast soundings keep a rather
prominent dry layer in the lower levels through the night,
with moisture levels saturating from the top down. While the
morning high-res models show periods of precipitation, most
notably the NAM Nest, this appears to be overly generous, and the
small precip chances tonight have been removed from the new
forecast package. The arrival of the rain Wednesday morning has
also been slowed a bit, as the column continues to saturate.
Morning model guidance has shown a bit of a southward shift with
the main precipitation axis on Wednesday, focusing more on the
areas near and south of I-72/Danville. During the daytime, this
would largely be rain. However, there remains concerns for a
narrow axis where dynamic cooling may be enough to overcome the
above-freezing temperatures. Within that narrow band, potential
for a quick inch or two of accumulation is there, mainly in the
evening. Where that sets up is the $64,000 question. Experimental
snowband guidance from WPC focuses on an area from about Decatur
eastward to Danville and Paris, with HREF ensembles just a touch
north of there. Midday runs of the HRRR and NAM Nest are focused
more across Indiana, with some spillage over the border to near
Champaign. For now, minor snow accumulations around a quarter inch
were included in this forecast package along a Decatur to
Danville line.
In terms of precipitation ending, PoP`s were increased across the
eastern CWA after midnight, but dry conditions are expected before
sunrise. Thanksgiving Day travel is not expected to be impacted in
our immediate area.
Geelhart
.LONG TERM... (Friday through Next Tuesday)
Issued at 235 PM CST Tue Nov 26 2024
Main weather story in the longer range remains with the much below
normal temperatures, which will linger into the middle of next
week. No significant changes were noted in the morning model
guidance, with temperatures likely to remain below 30 degrees from
Friday all the way into Tuesday, though some low 30s temperatures
are plausible south of I-70 Friday and Saturday. Wind chills are
likely to drop into the single digits Friday night near and north
of I-74, and over all of the forecast area Saturday night. LREF
probabilities of wind chills zero or below are around 30-40% north
of a Macomb-Bloomington line Saturday night.
In regards to the weekend clipper system, trends continue with
more of a track across Missouri into the lower Ohio Valley.
Higher NBM probabilities of over 1 inch of snow are around 30-40%
from about Quincy into southern Indiana, mainly Saturday afternoon
and evening, and around 20% of over 2 inches. High pressure
building in from the northwest will keep the weather dry for the
Sunday post-holiday travel rush.
Geelhart
&&
.AVIATION... (For the 00z TAFs through 00z Wednesday Evening)
Issued at 500 PM CST Tue Nov 26 2024
High clouds and light southeast winds will dominate the central IL
terminals tonight. By mid-late morning Wed, a weather system
moving in from the southwest will spread rain into the area,
initially with VFR ceilings, lowering to MVFR mid-late afternoon.
There will be a sharp cutoff to the northern edge of the precip
over central IL, with KPIA possibly staying dry and VFR. Towards
00z/Thu we may begin to see a changeover to snow along the I-72
corridor, which will be reflected in the 06z TAFs.
25
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Area Forecast Discussion
National Weather Service Pueblo CO
537 PM MST Tue Nov 26 2024
.KEY MESSAGES...
- Moderate to heavy snow will persist along the mountains tonight.
- Rain and snow expands across the plains Wednesday, with more
impactful snowfall along the Palmer Divide and southern I-25
corridor.
- Snow diminishing Wednesday night with below average
temperatures into early next week.
&&
.UPDATE...
Issued at 522 PM MST Tue Nov 26 2024
Quick update to increase QPF along portions of the I-25 corridor
tonight through Wednesday with the biggest increases occuring
across the southern I-25 corridor (Huerfano and western Las
Animas counties) in latest HRRR and WPC Guidance. Also
increased QPF across portions of southern El Paso and Pueblo
counties where latest high res runs look a little heavier with
QPF and a smidgen colder. El Paso and portions of eastern
Fremont county should see snow levels lower fast enough to
account for some heavier snow accumulations as the precipitation
band develops overnight into Wed AM. Added those locations to
Winter Weather Advisories which should end by 2 PM Thursday.
Greatest impacts in terms of slick roads and heavier snow for
those areas will be in the morning, with gradual improvement in
the afternoon.
Snow bands could be briefly heavy with the baroclinic zone as
it drops southward overnight into early Wednesday morning. Snow
levels will play the biggest roles as to how much accumulation
occurs and there is some uncertainty in that. However NBM looks
way too warm and have leaned towards the higher res model
consensus. For now the greater portion of Pueblo county and
perhaps even Canon City proper look to stay on the lighter side
of the snowfall spectrum due to temperatures near or slightly
above freezing, but near the mountains there could be heavier
amounts to justify further expansions of the advisories into
Pueblo county. Will wait for the 00z runs for better clarity
before making further adjustments. -KT
&&
.SHORT TERM /THROUGH WEDNESDAY/...
Issued at 238 PM MST Tue Nov 26 2024
Tonight: Tuesday night will bring some active weather to portions of
south central and southeastern Colorado. Synoptically, strong
westerly flow will be in place over the area, along with an
atmospheric river streaming well inland over the area. The strong
flow will allow for consistent orographic forcing over the higher
terrain, especially over the Continental Divide. With the enhanced
forcing and abundant moisture, snow will continue along the
mountains tonight, but particularly along the Continental Divide,
where the forcing will be greatest. Snow along the mountains is
expected to be moderate to heavy at times, which could cause impacts
along mountain passes and roads. Along with that, pockets of
precipitation are anticipated to push off of the higher terrain and
move eastward over the valleys. With that said though, temperatures
will be slow to fall given higher moisture content and modest WAA.
Given that, precipitation in the valleys will start off as rain and
rain/snow mix before becoming a rain/snow mix and snow by early
Wednesday morning hours. Elsewhere though, dry conditions are
expected through much of the night, though showers will start to
increase along portions of the plains right around daybreak early
Wednesday. Otherwise, increasing clouds and relatively light winds
are expected for many, with some breezy winds along the mountains
overnight. As for temperatures, as alluded to, cloudy skies and
minor WAA will hinder significant cooling overnight. Given this, the
plains and valleys will fall into the low to mid 30s, and the
mountains will cool into the 10s to low 20s.
Tomorrow: Active weather continues Wednesday for portions of south
central and southeastern Colorado. A shortwave embedded within the
westerly flow will push over the region throughout the day. While
moisture will start to lessen as this wave pushes over, orographic
forcing will continue, along with an increase in broader synoptic
forcing and support. In addition, this wave will shove a cold front
southward early in the day, which will bring enhanced surface
forcing, particularly between the eastern mountains and the I-25
corridor. Given all of that, snow along the central and western
mountains, along with the San Luis and upper Arkansas River Valleys,
will start to decrease in coverage and intensity throughout the day.
As for the eastern mountains and plains, precipitation will increase
in coverage. Surface forcing from the front, in combination with
dynamics from the wave, will allow for precipitation to blossom
early Wednesday and then maintain through much of the day across the
eastern mountains and plains, but especially between the eastern
mountains and I-25 corridor where forcing will be greatest.
Precipitation for the mountains will remain all snow, but elsewhere
will be a bit more messy. Snow levels early in the day will actually
be hovering around 5000-5500 ft, with rain/snow and snow above that
level and rain and rain/snow mix below that. As CAA takes place
throughout the day as the wave passes, snow levels will drop to
around 4000-4500 ft, with most precipitation transitioning to a
rain/snow mix or even all snow for the plains. The heaviest snow for
the "plains" locations will be along the Palmer Divide and southern
I-25 corridor, where cooler temperatures will allow for
predominantly snow and for greater snow accumulations. Beyond all of
that, relatively light winds and cloudy skies are expected for much
of south central and southeastern Colorado. Looking at temperatures,
little warm up is anticipated for the area given the CAA and
increased cloud cover. Given this, the plains and valleys will warm
into the mid 30s to low 40s and the mountains will reach into the
mid 10s to 20s.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...
Issued at 238 PM MST Tue Nov 26 2024
Wednesday Night - Tuesday Night...Snow begins to move out of the
area around 03-06z Thursday. This is due to the upper level trough
shifting to the east, and upper level moisture being filtered out by
dry air. Also, the winds tend to weaken in the lower and upper levels
diminishing some of the upslope that could contribute to moderate
to heavy snowfall.
The rest of Thursday, and the long-term period will be dry with
temperatures below normal. Models do differ on the westward extent
of shortwaves digging down the backside of the upper trough across
the Central Conus, however, most guidance does keep the area dry at
the moment.
&&
.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 424 PM MST Tue Nov 26 2024
Main concerns this period will be for light to moderate,
periodically heavy, snow late tonight through mid morning
Wednesday. At this time, highest chances for the heavier snow
with lower vis and ceilings is at COS. While lower chances for
PUB, can`t completely rule out brief bursts of heavier snow and
if this were to occur, would anticipate vis to fall under one
mile at times. Snow should stay away from ALS for much of the
overnight hours, with development likely increasing through
Wednesday morning though still staying on the lighter side for
much of the period. Given some stronger winds aloft across ALS,
think LLWS will occur for much of tonight and so have added it
at this time. Snow coverage and intensity will likely both lower
by early afternoon on Wednesday, however, periodic light snow
should still occur through the period. MVFR ceilings will remain
in place at all sites through the period, with the exception of
ALS where an improving trend should occur Wednesday afternoon.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning until 5 AM MST Thursday for COZ058-060-
061-066-068-073-075.
Winter Weather Advisory until 5 AM MST Thursday for COZ059-
062>064-072-074-076.
Winter Weather Advisory from 2 AM to 2 PM MST Wednesday for
COZ077-083-085.
Winter Weather Advisory from 5 AM Wednesday to 5 AM MST
Thursday for COZ078-079-087-088.
Winter Storm Warning from 5 AM Wednesday to 5 AM MST Thursday
for COZ080.
Winter Weather Advisory from 11 PM this evening to 11 PM MST
Wednesday for COZ081-082-084.
&&
$$
UPDATE...KT
SHORT TERM...SIMCOE
LONG TERM...CLOUSE
AVIATION...RODRIGUEZ
Area Forecast Discussion
National Weather Service Sacramento CA
200 PM PST Tue Nov 26 2024
.SYNOPSIS...
Precipitation across interior NorCal tapers off by this evening,
with lingering showers until early Wednesday morning. Dry
conditions are expected for Thanksgiving through the holiday
weekend, with cold, frosty mornings.
.DISCUSSION...
The last of a series of shortwave troughs will exit the area to
the southeast by this evening. Precipitation has tapered off with
some lingering light showers continuing across mountains and
foothills this afternoon, with enough instability over Shasta
County to see a few isolated thunderstorms. Lightning detection
and radar showed a weak thunderstorm develop early this afternoon
just northwest of Fall River Mills. The HRRR model suggests a few
more convective cells could form north and east of Redding through
4 pm. The latest satellite loop shows skies largely clearing in
the Sacramento Valley north of I-80. Much of the rest area is
expected to gradually clear overnight. With a fairly quick exiting
of this system, winter weather concerns will be winding down by
this evening, so the Winter Storm Warning for the West Slope of
the Northern Sierra Nevada and for western Plumas County/Lassen
Park now ends at 4pm.
High pressure ridging builds in on Wednesday bringing dry and
mostly sunny conditions through the holiday weekend. Breezy north
to northeast winds should limit fog development Wednesday
morning, but with lingering low level moisture and clear skies
can`t rule out some patchy developing, mainly for sheltered areas
in the eastern portion of the northern San Joaquin Valley. These
winds continue overnight into Thursday and could limit morning
temperatures from getting very cold. The NBM currently shows a 20
to 70% probability of reaching 36 degrees or less for the Valley
on Wednesday, highest on the east side of the Valley. This is the
temperature when frost typically becomes and issue. Some lower,
sheltered areas could see below freezing. Thursday and Friday are
expected to be colder, with a 40-95% chance of lows 36 or below,
again mainly on the east side of the Valley. These cold
temperatures could impact pets, plants, and those without adequate
heating. Prepare for widespread frost. Running events on
Thanksgiving could also be impacted, so if you are a participant
or spectator make sure to dress for cold weather.
.EXTENDED DISCUSSION (Saturday THROUGH Tuesday)...
Ensemble guidance is in generally good agreement on the upper
level pattern through the weekend and into early next week.
Ridging is expected to build over the Pacific Northwest and over
top of a closed low off shore of SoCal, leaving interior NorCal
underneath split flow aloft. Although, there are some notable
discrepancies regarding the strength and persistence of the closed
low. While some ensemble members indicate a few subtle shortwave
ejections from the semi-stalled offshore low, a lack of
appreciable moisture advection into interior NorCal will likely
limit any precipitation potential across the region. Given the
anticipated pattern shift, more or less seasonable temperatures
are anticipated across the extended forecast period, although
Saturday morning low temperatures may still linger in the low to
mid 30s alongside attendant low elevation frost potential.
Otherwise, light to breezy northerly winds are expected across the
Valley and foothills with breezy to occasionally gusty easterly
winds along the Sierra, with gusty winds contingent upon any
shortwave ejections.
&&
.AVIATION...
VFR conditions expected for Valley/foothills locations of
interior NorCal next 24 hours. MVFR/IFR conditions persist in
mountain snow showers through 00z, improving to primarily VFR
after. Generally light and variable Valley/foothills winds today
become breezy up to 12 kts from the north after 06z, with some
gusts up to 25 kts across the Delta. Westerly gusts to 30 kts
along the Sierra continue through 06z, shifting to easterly
downslope winds overnight.
&&
.STO WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning until 4 PM PST this afternoon for West
Slope Northern Sierra Nevada-Western Plumas County/Lassen Park.
&&
$$