Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/28/24
Area Forecast Discussion
National Weather Service Binghamton NY
1038 PM EST Wed Nov 27 2024
.SYNOPSIS...
After a dry evening, the next storm system moves into the
region late tonight. Rain and wet snow will impact the area
through Thanksgiving Day with little accumulation in valley
areas, but several inches of snow expected in the higher
terrain of Central New York. Some lake effect snow showers
develop Friday with the arrival of cold air.
&&
.NEAR TERM /THROUGH THURSDAY NIGHT/...
1030 PM Update...
Upgrade advisories in Oneida, Otsego, Madison, Cortland,
Chenango and Delaware counties to Winter Storm Warnings based on
the latest 00z CAMs and in collaboration with NWS Albany. 18z
ensembles had an area of 90% for 6 inches or more of snow
centered on the warning zones. 00z HRRR and 3km NAM show a
widespread 4-9, locally 10 inches over the new warning zones
using the Kuchera snow ratio method (less than 10:1 ratio). 00z
12km NAM shows 7-11 inches over the new warning zones...overall
confidence increased in higher snowfall totals, especially over
the higher elevations. Snow amounts are still questionable in
the deep valleys, and will depend on rates. Guidance shows a
strong band of frontogenesis developing from near Utica SW to
Binghamton Thursday morning and afternoon...this may become the
focal point for 1-2 inch per hour snowfall rates. WPC`s HREF
based snow band visualization page shows numerous members with
0.10-0.15"/hr snow QPF; which would equate to 1-1.5 inch per
hour snowfall rates at a 10:1 ratio. The latest 00z HREF shows
peak snowfall rates generally between 0.5 to 1.0" per hour, but
mean 24 hour snowfall is a little lower in the 4 to 8 inch range
over the warning area. Caveats to the forecast will be if the
surface wet bulb temperatures can get down to 30-32 degrees
during the day on Thursday when the potential for heavy snow
banding is over the region...just a degree or two warmer would
certainly result in less snow accumulation.
Also expanded the winter weather advisory into S. Cayuga and
Onondaga counties, being on the NW side of of the low and also
in favored location for banding...there will be significant
differences in snowfall amounts based on elevation...with the
city of Syracuse potentially not seeing much accumulation and
much higher 3-7 inch amounts in the hills south of the city.
730 PM Update...
Temperatures were able to drop into the 30s fairly quickly this
evening with partial clearing. Updated the forecast weather
grids through Thursday based on the latest HRRR/3km NAM
nest...also updated QPF with a blend of WPC, ECMWF, 18z NAM and
18z NAM nest. Snow ratios were amended based on WPC as a start,
then raised/lowered based on elevation. Latest snowfall amounts
were also updated with a significant nod to the 18z through 22z
HRRR...wet under 10:1 ratios, closer to the positive snow depth
change in the guidance. Snow amounts were increased
north/northeast of Binghamton...with some of the higher totals
between 3 to 8 inches expected over the higher elevations of
Cortland, Chenango, Madison, Otsego and Delaware counties. The
key to the forecast will be the surface low track and how far
the 850mb 0C line makes it north/northwest. Did include a
changeover to rain for several hours across the immediate NY
southern tier, northeast toward Norwich, Cooperstown, Oneonta,
Walton and Monticello....NE PA will almost certainly go above 0C
at 850mb with mainly rain after 10 AM Thursday....however could
see some lingering pockets of freezing rain over the highest
elevations here (> 1900 feet or so). Winter Weather Advisories
left as it, and will evaluate the 00z CAMS as they come in.
415 PM Update...
Quiet conditions remain in place this evening with increasing
clouds as high pressure slides to the east. This will give way
to a tricky forecast for the area late tonight through
Thanksgiving as a shortwave trough ejecting out over the central
Plains phases with a northern branch feature over the Midwest
and Ohio Valley with a developing surface low. Guidance this
afternoon has held onto the northern trend with this surface low
and has trended stronger with the low as well as it passes over
SE PA Thursday morning and toward southern New England Thursday
afternoon. A mix of rain and snow is expected to spread north
across the area after midnight tonight and changes over to snow
for most areas, which will continue into Thanksgiving morning.
Lows tonight will be mainly in the low 30s.
Late tomorrow morning and into the afternoon, rain is expected
to mix in and even a changeover to plain rain is possible in the
lower elevations. With the shift north in the low track, there
is also a push northward of warmer air, especially at 850mb,
over NE PA and into the southern Catskills, so a changeover to
plain rain is most likely in the lower elevations here. There is
some uncertainty as to how far north this surge of warmer air
gets over the eastern part of the CWA which can have a big
impact on snow totals in this area. With this being another
marginal temperature event like last week with high temperatures
in the low 30s above 1500 feet and in the mid and upper 30s
elsewhere, elevation is going to play a big role in snow
accumulations once again. With the stronger surface low and
vertical motion projected, precipitation rates can be heavy at
times, and in the higher elevations especially, above 1500 feet,
a heavy, dense wet snow is expected to accumulate upwards of 5
to 7 inches over CNY and 2 to 5 inches in NE PA. As a result,
winter weather advisories have been issued with this forecast
update. Valley areas across the Twin Tiers and NE PA will
generally see less than an inch while the lower elevations of
CNY and the Catskills see a slushy 1 to 3 inches.
While there remains some uncertainty regarding the Thanksgiving
storm, it remains quick hitting overall, and then the focus
changes to lake effect snow and colder conditions. As the storm
moves away Thursday evening, some lake effect snow is expected
to develop around the northern Finger Lakes and push northward
as a more defined band of snow over northern Oneida County
before daybreak Friday. Lows Thursday night fall back into the
20s.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
355 PM Update...
Colder air will continue to fill into the region Friday as westerly
flow will support lake effect snow showers east of Lakes Erie and
Ontario. A short wave will drop south and support a band of snow
showers that will extend from Lake Erie through Eastern NY. Guidance
is showing some weak instability, around 50 J/kg of CAPE. Soundings
show fairly steep 0-3km lapse rates and the potential for some gusty
winds to mix down, all while the snow showers are ongoing. This will
lead to gusty snow showers or weak snow squalls developing during
the daytime hours on Friday. These will be quick to diminish during
the evening hours as the environment becomes more stable. The band
of snow will exit Central NY overnight as lake effect snow will
continue through Saturday night. Model guidance keep these bands
mainly west and north of the region, but these bands will move
around. This will mostly favor snow for N. Oneida though light snow
cannot be ruled out along the NYS Thruway. Also, the eastern extent
of Lake Erie bands may expand into Central NY resulting in light
accumulations for a western portions of the Southern Tier.
Snowfall totals for this time period will generally be light. The
narrow band of snow that moves through on Friday will result in
totals up to 3 inches. N. Oneida could see localized amounts of 3+
inches from the lake effect snow off of Lake Ontario. A blend of WPC
guidance and CMC was used for snow ratios for Saturday. Unlike the
last couple of systems, colder conditions will favor drier snow.
Temperatures will finish out the work week in the mid 30s to low
40s. They will crash into the upper teens and 20s Friday night
before rebounding back into the 30s Saturday, though some may stay
below freezing. Another chilly night is then expected Saturday night
as most will see temps fall into the teens. The Finger Lakes region
is expected to stay in the 20s.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
355 PM Update...
The active lake effect pattern will continue through the end of the
longer term period as cold air remains in place. While the lake
effect will stay north of the region Sunday, flow becomes
west/northwest by Sunday night, allowing for those bands to drift
south back into Central New York. There will be a brief period where
there will be a multi-lake connection from the Georgian Bay to Lake
Ontario on Monday. This would potentially favor snow extending well
inland. Lake effect snow showers will linger into Tuesday, but do
drift back northward as flow becomes more westerly. By midweek,
there may be some lingering lake effect snow showers, but there is
also another system that begins to approach the region. Additional
snowfall accumulations will be possible during this forecast period,
but it is too early to pinpoint exact amounts as there is
uncertainty where lake effect bands will set up. Given the pattern
on Monday, that would likely be the best day for accumulating snow
over Central NY.
&&
.AVIATION /03Z THURSDAY THROUGH MONDAY/...
VFR conditions will last through around local midnight, then
quickly go down hill as precipitation overspreads the region.
Generally speaking, precip will start as a rain-snow mix before
changing to mostly snow before dawn (AVP may remain a mix).
High confidence in IFR or LIFR ceilings, and the likely lowest
visibilities will be during the morning hours before warmer air
changes precip back to a mix and then rain, starting in the
lower elevations, with snow levels slowly creeping up. Winds
will start south to southeasterly then back around to the east
and north through the day, remaining light throughout the day.
Winds will become steadier out of the N to NW by late afternoon,
but will remain under 10 knots. Visibility will improve as snow
changes to rain, and then as precip ends in the afternoon, but
lower ceilings (IFR to fuel alt) will prevail in the wake of the
departing system.
Outlook...
Thursday Night...Low ceilings will persist through the night,
with further restrictions as lake effect snow bands begin
setting up, mainly in north-central NY.
Friday and Monday...Restrictions possible in scattered lake
effect snow showers, especially for the CNY terminal sites.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...Winter Weather Advisory until 10 PM EST Thursday for
PAZ038>040.
NY...Winter Storm Warning until 10 PM EST Thursday for NYZ009-036-
037-044>046-057.
Winter Weather Advisory until 10 PM EST Thursday for NYZ017-
018-022>025-055-056-062.
&&
$$
SYNOPSIS...DK
NEAR TERM...DK/MJM
SHORT TERM...BTL
LONG TERM...BTL/ES
AVIATION...BTL/MPH
Area Forecast Discussion
National Weather Service Columbia SC
1012 PM EST Wed Nov 27 2024
.SYNOPSIS...
A strong cold front will move through the area Thanksgiving Day
with showers and scattered thunderstorms. Some thunderstorms
could be strong to severe. Behind this front, below to well
below normal temperatures are expected for the weekend into
early next week as the coldest air mass of the season blankets
the region.
&&
.NEAR TERM /UNTIL 7 AM THURSDAY MORNING/...
Key Message(s):
- Moisture is steadily increasing ahead of the approaching front
with isolated thunderstorms possible in the northern Midlands
and Pee Dee near sunrise.
- Wind gusts over 25 mph possible after 5am Thursday.
The strong cold front is continuing its push eastward this evening
with associated WAA and moisture advection from strengthening
southwesterly winds. Showers will start to push into the western
Midlands and CSRA by about 5am and then shift eastward over the
subsequent few hours. The HRRR and other hi-res guidance brings
a band of likely elevated convection across the Pee Dee and
northern Midlands around 12z; the profiles show a consistent
strong low level inversion and despite some increasing shear
profiles thanks to the strengthening low level jet, this
inversion should limit severe potential. Wind gust potential
however has trended upward with the HREF, GEFS, ECE, and HRRR
updates all suggesting 30- 40 mph gusts during the frontal
passage Thanksgiving morning. But these gusts will start
generally after 7am and then shift into the short term period.
&&
.SHORT TERM /7 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/...
Key Message(s):
- A strong cold front is expected on Thanksgiving, bringing
scattered showers and possibly thunderstorms.
- Gusty winds expected along the front over 30 mph.
- A few thunderstorms could become strong to severe.
Models continue to make adjustments with the cold front with the
latest guidance indicating the cold front moving into the
western portions of the forecast area shortly after daybreak
then across the remainder of the forecast area by mid afternoon.
Although there is potential for strong to severe thunderstorms
given the ingredients there are also concerns which would limit
convective potential. Hi-res and global guidance have backed
off considerably on precip amount and convective coverage due to
a lack of moisture convergence and synoptic scale forcing.
Still with CAPE values forecast the 500-1000 J/kg range and deep
level shear is also anticipated to be around 60 kts or greater
there is potential for strong to severe thunderstorms on
Thanksgiving, partially dependent on the timing of the front.
SPC has kept the area under a Marginal Risk (category 1 of 5)
for severe weather due to these factors. Should a strong to
severe storm develop, damaging winds are the main threat with an
isolated tornado possible. High temperatures will be in the low
to mid 70s with lows ranging from the upper 30s in the west to
mid 40s in the east. Regardless of severe potential, gusty winds
along the front starting early Thursday are expected. Gusts
over 30 mph are likely across much of the area and a Lake Wind
Advisory is in effect from 7am through 4pm.
Friday and Friday night will be a much calmer period as high
pressure will be building into the region however this will also
begin an extended period of colder to much colder than normal
temperatures. Cold air advection will be kept in place by
northerly winds and even with mostly sunny skies high
temperatures Friday will be held in the mid to upper 50s. With
winds diminishing Friday evening and clear skies overnight
radiational cooling conditions will be excellent resulting in
overnight lows in the upper 20s to around 30.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
Key Message(s):
- Confidence continues to increase in the coldest air of the
season.
High pressure along with cold air will continue building into
much of the central and eastern US through the weekend and
remain over the region through the middle of next week.
Temperatures will steadily fall through the weekend with
overnight lows Monday and Tuesday night ranging from the low to
mid 20s. Even with mostly sunny skies each day high temperatures
Saturday and Sunday will be in the low to mid 50s and mid 40s to
low 50s Monday and Tuesday. As mentioned in previous
discussions, the growing season is very likely (>95% chance)
to end for the remaining counties of the forecast area this
weekend.
&&
.AVIATION /03Z THURSDAY THROUGH MONDAY/...
VFR conditions expected through 06z then increasing
probabilities of cig restrictions as a cold front approaches the
region.
Satellite imagery currently showing mainly high clouds moving
over the region and this is expected through around 06z.
Increasing moisture on southerly low level flow ahead of an
approaching cold front will support possible stratus arriving
before 12z but most terminals should develop MVFR cigs by 12z.
Winds will be light through around 09z before really picking up
from the south to around 10 knots with some gusts up to 20
knots. Strong low level winds above the boundary layer will be
around 40 knots or higher late tonight so included a period of
low level wind shear. Scattered showers with isolated
thunderstorms will be possible just ahead of the front during
the mid morning into early afternoon hours and have included a
PROB30 group for this from 13z to 18z. Winds are expected to
increase and gradually shift to the southwest and west as the
front moves through by early afternoon. Much colder and drier
air will build in behind the front with continued gusty winds
through sunset before wind gusts diminish after 00z. Cigs
expected to return to VFR behind the front as drier air builds
in during the afternoon.
EXTENDED AVIATION OUTLOOK... No significant aviation hazards
are currently anticipated as strong high pressure builds into
the region on Friday and remains in place through at least early
next week.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...Lake Wind Advisory from 7 AM to 4 PM EST Thursday for SCZ016-
018-020>022-025>031-035-037-038-041-115-116-135>137.
GA...Lake Wind Advisory from 7 AM to 4 PM EST Thursday for GAZ040-
063>065-077.
&&
$$
SYNOPSIS...
NEAR TERM...
SHORT TERM...
LONG TERM...
AVIATION...
Area Forecast Discussion
National Weather Service Cheyenne WY
818 PM MST Wed Nov 27 2024
.KEY MESSAGES...
- Snow showers are winding down this afternoon, but winds
increasing in the wind prone areas tonight into Thursday AM
may lead to areas of blowing snow.
- Mostly dry and occasionally breezy to windy days will occur
for Friday through Tuesday, with temperatures remaining near
or above normal.
&&
.UPDATE...
Issued at 815 PM MST Wed Nov 27 2024
No major changes to the forecast as of 03Z. Decreased overnight
low temperatures at Laramie and Alliance a few degrees due to
clear skies and most models running too warm. Laramie was
already below the previously forecast low by 03Z and will likely
keep cooling overnight with clear skies. Decreased dewpoints a
little as well, following HRRR guidance as the HRRR was the best
initiated hires model. Increased cloud cover a little to
account for the clouds drifting across the center of the CWA.
&&
.SHORT TERM /THROUGH FRIDAY/...
Issued at 200 PM MST Wed Nov 27 2024
Snow showers activity has mostly come to an end across the area as
the shortwave responsible for the recent snow shifts east into
Kansas. Much drier air in the mid to upper atmosphere has worked in
aloft, but low-level moisture remains decent. Steep lapse rates in
the lowest part of the atmosphere below about 650-mb are resulting
in fairly good cumulus cloud coverage continuing this afternoon.
Radar is picking up some echos stemming from this, particularly in
the usual convergence zone south of Wheatland that forms in the wake
of the northern Laramie Range in northwest flow periods. This
activity is probably mostly virga, but some flurries or brief
visibility drops due to snow showers will remain possible until
about sunset.
Precipitation will be out of the picture for a while after today,
but attention will have to turn to increasing winds. The lack of mid
to upper level cloud cover and subsidence in the wake of today`s
shortwave trough will help increase surface pressure over the
Colorado Rockies. At the same time, a weak vort-max diving over the
northern Plains will carry with it a subtle surface trough. The
combination of both will result in increasing MSLP gradients across
the our gap areas. The period of strong gradients looks to be fairly
short. In addition, in-house guidance is only showing about a 20-30%
probability of high winds, but elevated winds look like a good bet.
Cross-barrier MSLP gradients don`t look quite strong enough to give
confidence in any high wind headlines, but will need to keep an eye
on this through Thursday morning. Winds should be strong enough to
kick up some patchy blowing snow, which may lead to a few travel
headaches along I-80 tonight into Thursday morning.
The dominant weather pattern for quite a while will set in tomorrow,
characterized by a western ridge, eastern trough, and northwest flow
over our area. Thanksgiving day looks fairly nice, with mostly sunny
skies along I-80. More cloud cover along US-20 associated with the
passing shortwave to the northeast will keep things a little cooler,
but most locations should end up about 5F cooler than average for
this time of year. Another round of nocturnal increasing winds is
looking likely for Thursday night again thanks to a local pressure
increase over the interior Rockies. A developing surface trough just
east of the terrain boundary ahead of another vort-max moving
through the northwest flow over the northern Rockies will keep winds
going through the day Friday. Parameters are marginal right now for
high winds, with in-house guidance currently showing about a 30-40%
probability of high winds. Cross-barrier MSLP gradients, 700-mb
winds, and 700-mb height gradients are all just short of usual
thresholds in current model guidance.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
Issued at 200 PM MST Wed Nov 27 2024
Long term forecast focuses on prolonged periods of cold and dry
conditions with an upper level ridge developing across the Western
Seaboard and slowly making its way inland, as a series of upper
level closed lows stall out just north of the Great Lakes. Under
this setup, northwesterly flow is expected to take hold across the
region, bringing temperatures into seasonable averages. Really good
model agreement with the overall pattern and evolution of the upper
level features, as the NAEFS have continued to mirrored the
seasonable temperatures keeping the mean 700mb temperatures in the
climatological averages through next week.
Main concerns will remain with the stronger wind speeds possibly
this weekend, and even into next week, as weak shortwave
disturbances propagating within the flow that will be enough to kick
up wind speeds along the Laramie Range and some spill over into
Laramie county. At this time, not expecting the winds to reach high
wind criteria with local in-house model guidance hovering around 30%
probabilities for 58 mph wind gusts. Regardless, will need to
monitor throughout the remainder of the week for stronger wind
potentials with the NBM v4.2 Probability of Exceeding 34 knots
around 70% to 90% across the Central and South Laramie Range and
around 50% probabilities of those speeds to push east into Laramie
County, including the city of Cheyenne, on Saturday as this guidance
is normally under-representative for Wyoming. Not much relief in
sight as gusty to strong winds are expected to persist through the
majority of next week with the flow maintaining generally
northwesterly flow aloft and increased gradients increasing wind
speeds for Wyoming. In addition to the gusty to strong winds,
expecting precipitation chances to remain quite low throughout the
forecast. Although, latest model guidance has been trying to
indicate that there could be some breakdown of the upper level ridge
with a closed low developing across the Western Seaboard and pushing
south into the Four Corners. However, confidence is low at this time
to add any additional PoPs for the region and will maintain a dry
forecast.
&&
.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 446 PM MST Wed Nov 27 2024
Winds easing this evening with VFR conditions overnight. Some
concern with fog overnight...especially in areas that received
snow this morning (KLAR/KCYS). Given the downsloping winds
however...decided to hold off on lower conditions and will
continue to monitor for any development.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...None.
&&
$$
UPDATE...AM
SHORT TERM...MN
LONG TERM...MRD
AVIATION...GCC
Area Forecast Discussion...Updated
National Weather Service Lincoln IL
549 PM CST Wed Nov 27 2024
.KEY MESSAGES...
- Snow accumulation with the current storm system should largely
be minimal if anything. However, there remains some potential
(30-40% chance) for an inch of slushy accumulation in a narrow
band over east central Illinois.
- The upcoming cold spell will result in temperatures 10-20
degrees below normal from Friday through Tuesday, with slowly
warming temperatures by midweek.
- The weekend clipper system will likely just graze central
Illinois, with about a 30-40% chance of seeing more than an inch
of snow south of a Jacksonville to Lawrenceville line.
&&
.UPDATE...
Issued at 546 PM CST Wed Nov 27 2024
A band of strong frontogenetical forcing is in place roughly along
the I-72 corridor early this evening producing light rain across
the area. Obs along the I-72 corridor continue to indicate
temps/dew points several degrees above freezing. Dew points are
running generally 37-38 degrees with temps up to 1-3 degrees
warmer. While some of the hi-res guidance such as the HRRR and RAP
suggest light snow accumulations should already be occurring near
I-72 in east central Illinois, the transition to snow has yet to
occur. Latest runs of the RAP and HRRR are also around 2-3 degrees
too low with dew points. Meanwhile, while the RAP does have good
placement of the FGen currently in place, it has it slowly
migrating to the I-70 corridor through 7/8pm CST and weakening
rapidly thereafter. Given the current obs and the expectation for
weakening forcing after the next few hours, it is seeming
increasingly unlikely that there will be any accumulations across
east central Illinois this evening, though that`s not to say that
there still couldn`t be a mix or brief changeover to snow as
dynamic cooling within the area of strongest forcing drives down
temp/dew points within the column.
Deubelbeiss
&&
.SHORT TERM... (Through Thanksgiving Day)
Issued at 222 PM CST Wed Nov 27 2024
Rain has been expanding east along the I-72 corridor early this
afternoon, with some bright banding evident on radar. Mosaics show
the rain extending west to the Kansas City area, and the northern
edge of the rain shield should begin to pivot more southwest-
northeast as the upper wave over South Dakota/Nebraska continues
to push southeast. By midnight, the precipitation should mainly be
confined to areas south of a Danville-St. Louis line, exiting the
far southeast CWA toward 3-4 am. Little adjustment was needed in
the overall precip chances, from the changes that were made on the
late morning update.
In terms of the mesoscale snow potential, focus remains in a
narrow corridor generally along US-36 from Decatur to south of
Danville. Recent HRRR runs continue to struggle with when and how
long a rain/snow switch occurs. Forecast grids will go with a few
hour period of prevailing snow this evening in that area. Ground
temperatures are currently running in the lower 40s per Illinois
and Indiana DOT sensors, so unless the snow falls extremely hard,
travel impacts should not get out of hand. HREF guidance suggests
snowfall rates of 0.1 to 0.2 inches per hour in that area.
Quiet weather is expected for Thanksgiving Day, as skies become
mostly sunny during the morning. While temperatures will be in the
mid 30s to lower 40s, breezy northwest winds will mark the start
of a significant pattern shift.
Geelhart
.LONG TERM... (Friday through next Wednesday)
Issued at 222 PM CST Wed Nov 27 2024
The early season taste of Arctic air is still on schedule. ECMWF
Extreme Forecast Index remains in the -0.7 range for both Saturday
and Sunday. 850 mb temperatures are progged to drop down to -10C
this weekend, which puts it below the 10th percentile in our
sounding climatology for the start of December. Highs in the 20s
are expected as early as Friday north of I-72, and will cover much
of the forecast area through the weekend. Wind chills in the
single digits are likely each night from Friday night through
Sunday night. Some slow moderation takes place early next week as
the upper ridge over the western U.S. amplifies a bit and nudges
eastward, though highs by midweek should still be below normal
(mainly upper 30s to near 40).
The weekend clipper system continues to favor more of a glancing
blow against us, with most of the snow from Missouri into southern
Illinois. Minor accumulations in our area are most likely south of
a Jacksonville to Lawrenceville line.
Geelhart
&&
.AVIATION... (For the 00z TAFs through 00z Thursday Evening)
Issued at 523 PM CST Wed Nov 27 2024
A band of showers is lingering over the I-72 corridor, impacting
SPI, CMI, and DEC. IFR vis and MVFR ceilings are forecast for CMI
and DEC, and MVFR conditions at SPI. DEC and CMI could see a further
drop in ceilings, down to LIFR as the band of rain transitions to a
RASN mix or SN. Once precipitation ends tonight, a progression back
to VFR conditions is expected, along with winds out of the NW around
10 knots.
PIA will remain VFR for the TAF period. BMI MVFR ceilings should
rise before midnight.
Copple
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Area Forecast Discussion
National Weather Service Memphis TN
839 PM CST Wed Nov 27 2024
...New UPDATE...
.UPDATE...
Issued at 828 PM CST Wed Nov 27 2024
The cold front has passed through Memphis and Tunica and should
move through Jackson, TN in the next hour or so. Only isolated
lightning strikes have been observed in the narrow line of
showers along the front and any positive instability remains well
south of the Midsouth. Most high resolution guidance has the
front into middle Tennessee and Alabama by 07Z. A cold airmass
will be the main weather headline for the next 7 days. We could
see morning lows in the teens Saturday into early next week,
although for now we have most of the region in the 20s. High
temperatures through the weekend into next week will remain mostly
in the 40s.
&&
.SYNOPSIS...
Issued at 347 PM CST Wed Nov 27 2024
Low pressure and an associated cold front will move through the
Mid-South tonight with scattered to numerous showers and a few
thunderstorms. A few strong to severe storms are possible over
northeast Mississippi. Much colder air will filter into the region
behind the front marking the beginning of a period of much below
normal temperatures that will last into next week.
&&
.DISCUSSION...
(This evening through next Tuesday)
Issued at 347 PM CST Wed Nov 27 2024
Currently...A 1002 mb surface low is pushing into the Arklatex
this afternoon with a cold front trailing to the SW into TX.
Meanwhile, a potent mid level trough with an 80 kt 500 mb speed
max is pushing quickly into the Southern Plains. A few light
showers and patches of drizzle and fog are occurring across the
Mid-South due to the WAA regime in place ahead of the approaching
system.
Low pressure will track across the Mid-South tonight, roughly
along the I-40 corridor. Strong lift from mid level trough will
overspread the region this evening and showers will expand across
the area. The warm front stretching from central LA eastward
along the Gulf Coast will lift north this evening. It will be a
race as to whether the more unstable air can make it into NE MS.
Latest data shows a window, from about 10 pm to 2 am, when strong
shear and at least some instability will overlap across area
south and east of TUP. Model soundings hold on to a low level
inversion for much of the window indicating that most of the
convection will be elevated with minimal tornado threat. If some
deeper elevated convection can develop along the front, as the
HRRR suggests, perhaps some large hail is possible and some strong
winds could be tapped. The other CAMs are not as bullish. All in
all, this marginal risk is exactly that.
The system will race ENE and the associated cold front will exit
NE MS by 3 am. Cold air will filter into the region on brisk NW
winds during Thanksgiving. The Mid-South will enter into a period
of much below normal temperatures that will continue through the
weekend into next week as a large upper low will be centered over
eastern U.S. and northwesterly flow prevails across the Mid-South.
A couple reinforcing airmasses from western Canada will drop
south into the region late Saturday and again late Monday. A few
flakes are possible along the KY border late Saturday with that
reinforcing front. Expect highs in the 40s and lows mostly in the
20s from Thanksgiving through Tuesday.
&&
.AVIATION...
(00Z TAFS)
Issued at 555 PM CST Wed Nov 27 2024
Messy TAF set this issuance. A cold front will shift winds
north/northwest around 03Z with gusts up to 25 kts. Associated
MVFR/IFR conditions along with light rain and mist will continue
as this front pushes through each terminal. Showers with a few
possible pops of lightning will move through TUP overnight,
clearing the terminal by 07Z. Gusts look to drop out by 13Z as
north winds remain around 10 kts across all terminals and
conditions slowly improve to VFR.
AEH
&&
.MEG WATCHES/WARNINGS/ADVISORIES...
AR...None.
MO...None.
MS...None.
TN...None.
&&
$$
PUBLIC FORECAST...JDS
AVIATION...AEH
Area Forecast Discussion
National Weather Service Marquette MI
527 PM EST Wed Nov 27 2024
.KEY MESSAGES...
- Winter Storm Watches have been issued for the eastern and western
portions of Upper Michigan for Heavy Lake Effect Snow in the
northwesterly wind snowbands. This long-duration event is likely (80-
90%) to bring over a foot of snow to the Munising to Grand Marais
stretch north of M-28 Thursday through Saturday and in the high
terrain between Houghton and Ironwood. Hazardous travel is expected,
impacting Thanksgiving holiday travel Thursday through at least
Saturday and potentially through Monday.
- Winds gusting to near gale-force in combination with the fluffy
nature of the heavy snow will create patchy blowing snow conditions
along the shores of Lake Superior, further adding to travel hazards.
- Temperatures will be slightly below normal, with highs mainly in
the 20s and low temperatures by the middle of next week likely
(50+%) to reach the single digits in the interior west.
&&
.SHORT TERM /THROUGH TONIGHT/...
Issued at 104 PM EST Wed Nov 27 2024
GOES water vapor imagery and RAP analysis highlight a nearly stacked
closed upper level low in the process of retrograding westward
toward James Bay. The expansive circulation across Quebec, southern
Ontario, and the Great Lakes positions Upper Michigan within
prevailing northwest flow which is sustaining an airmass overhead
characterized by 850mb temps between -11 and -9C, per SPC
mesoanalysis. At the surface, troughing across eastern Lake Superior
has sustained shallow lake effect snow shower activity, which has
been observed streaming into Alger, northern Schoolcraft, and Luce
counties via our radar and CASMR in Ontario. Showers have been
mostly broken cells which, from webcams, have yielded little
accumulation. There have also been a few freezing drizzle
observations. Mostly cloudy skies were also noted with temperatures
in the 20s with some 30s by Lake Superior.
Lake effect shower activity will continue for the remainder of today
and tonight. No notable changes are expected to the synoptic
pattern save for the slow southern migration of the closed low
feature near James Bay. Inversion heights across the east between 7
and 8k feet may be able to yield more residence within the DGZ then
today, but still only expecting 1 to 3 inches in the northwest wind
snow belts. Less snow, mostly an inch or less, is expected in the
west/Keweenaw due to slightly lower inversion heights and more
limited fetch. Overnight lows should dip to near 20 or into the
teens away from the immediate lakeshores, while the Great Lakes
moderate near surface temps enough to keep overnight lows in 20s.
&&
.LONG TERM /THURSDAY THROUGH WEDNESDAY/...
Issued at 416 PM EST Wed Nov 27 2024
The pattern aloft consists of an omega block centered over southern
Greenland, leaving a trough and associated surface low parked over
James Bay. The 12Z GEFS suggests an expansive surface high pressure
over much of central North America, with mid 1030s mb over southern
Saskatchewan Friday night building south to the Dakotas by Monday
morning. This sets up persistent strong northwesterly flow over the
UP through at least next Monday. The cold Canadian airmass flowing
into the region will support 850mb temperatures to -14 C, which is
plenty supportive of pure lake effect snowfall to persist throughout
much of this forecast period. The blocking pattern looks to break up
next week when a clipper trough swings around the base of the James
Bay trough, sweeping it up and eroding the base of the Omega block
in the Monday to Tuesday timeframe. Ensemble guidance then hints at
a clipper low arriving in the UP sometime in the middle of next
week, though spread is high given the timeframe.
Beginning Thanksgiving, northwesterly lake effect is expected to
already be ongoing across both halves of the UP. The east half is
preferred in this setup with more convergent cyclonic flow (being
closer to the main surface low), more moisture wrapping around the
low, Lake Nipigon enhancement, and slightly warmer waters giving a
better thermal profile. These factors combine for QPF totals in
bands of near a quarter inch per 6 hours with 20-30% chances of up
to a half inch in the strongest bands. Despite not all of the
benefits of the east, the west half will get terrain enhancement as
the winds will be pushing directly uphill, so the west half will
still see QPF of a tenth to a quarter inch at times late this week.
This QPF combined with SLRs in the mid teens to 1 (given good lift
and saturation in the DGZ) will lead to 6-hourly snowfall rates of 2-
4 inches in the high terrain of the west and in the east half north
of M-28, with near 50% chances of bands reaching 1+ inch/hr rates in
the east by Friday morning per HREF reflectivity. These conditions
look to continue through Sunday as well, but uncertainty in QPF and
placement of features increases too much to be certain on snow
totals at this time. For now, Winter Storm Watches have been issued
for portions of the east Thursday afternoon through Saturday evening
and portions of the west Thursday evening through Saturday morning,
though either one may be extended if or when certainty in the late
weekend/early next week conditions improves. Wind gusts near gale-
force along the Lake Superior shores along with high-SLR snow will
create conditions ripe for patchy blowing snow along the shorelines,
adding "low visibility" to a growing list of travel hazards this
Thanksgiving and following weekend. One interesting thing to watch
will be the potential for thundersnow, as the GFS resolves over 100
J/kg of surface CAPE over eastern Lake Superior Friday and the HREF
also shows some lightning potential. For now, thunder has been
removed from this forecast package but future packages may include
an area of 15% thunder over far eastern Lake Superior and the shores
if this trend continues.
Moving into next week, uncertainty begins to increase as ensembles
diverge in their solutions on the breakup of the northern Atlantic
omega block and clipper lows over the Great Lakes that follow. A
general backing of the winds is expected by Tuesday that should
allow for some of the lake effect bands to move offshore from the
typical NW band placement, though westerly bands have been known to
climatologically support some heavier snow over the Keweenaw
Peninsula. Otherwise, the continuing buildup of cooler air will
allow for some overnight lows early next week in the interior west
to fall to their coldest yet of this season, with the NBM showing
some single-digit lows for Tuesday and Wednesday mornings. In
conjunction with 10-25 mph gusts, the wind chills could fall to the
single digits early next week to provide an even cooler feel to the
air. High temperatures will generally be around the 20s, which is
around 5-10 degrees cooler than normal for this time of year.
&&
.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 527 PM EST Wed Nov 27 2024
Lake effect pattern will continue for all terminals in this period,
with lake induced cloud cover prevailing over all terminals in this
period. Generally expecting MVFR conditions with spotty shower
activity into this evening at KCMX/KIWD. This should change Thursday
morning as showers become more widespread and gusty winds of 20 to
25kts support blowing snow risks. For KSAW, MVFR conditions will
continue through the period.
&&
.MARINE...
Issued at 416 PM EST Wed Nov 27 2024
The weather pattern through the beginning of next week will be
dominated by a near-stationary low pressure over James Bay with
expansive high pressure over the central to western CONUS, leading
to persistent northwesterly winds through nearly the entire forecast
period, save for some variance to north-northwest and west-
northwest. Ongoing northwesterly wind gusts of 20-25 kt will build
to near 30 kt through tonight and Thursday. Gales around 35 kt are
likely (up to 70% chance) late Thursday through Saturday mainly over
the west-central to east-central portions of the lake, though a few
gale force gusts remain possible (up to 50%) downslope of the
Minnesota arrowhead and west of Whitefish Point. Waves through this
period will be highest in the southern portions of the eastern half
of the lake and near Ontonagon Thursday through this weekend at 7-10
ft.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
Winter Storm Watch from Thursday evening through Saturday
morning for MIZ001>004-009-084.
Winter Storm Watch from Thursday afternoon through Saturday
evening for MIZ006-007-085.
Lake Superior...
Gale Warning from 1 AM EST /midnight CST/ to 7 PM EST /6 PM
CST/ Friday for LSZ240>244-263-264.
Gale Warning from 1 AM to 10 PM EST Friday for LSZ248>250-265-
266.
Lake Michigan...
None.
&&
$$
SHORT TERM...JTP
LONG TERM...GS
AVIATION...07
MARINE...GS
Area Forecast Discussion
National Weather Service Nashville TN
808 PM CST Wed Nov 27 2024
...New UPDATE...
.UPDATE...
Issued at 805 PM CST Wed Nov 27 2024
Surface low is currently situated over West Tennessee, with a warm
from extending northeastward from the low into Middle Tennessee,
and a cold front trailing behind the low center. Scattered showers
have developed across the mid state, and we expect these to
persist over the next several hours as the surface low tracks
toward the ENE across Middle Tennessee and drags the cold front
through. We don`t expect the showers to be heavy, perhaps a few
pockets of moderate rainfall, but most of the activity will be
light. The 00Z HRRR shows all precipitation exiting the mid state
by 12Z.
&&
.SHORT TERM...
(Rest of today through Thanksgiving Night)
Issued at 1127 AM CST Wed Nov 27 2024
Thanksgiving Eve is upon us and while I smell a lot of turkey, it
ain`t coming from this forecast. Are we going to get some rain
tonight and maybe a rumble of thunder (south of I-40)? Yes, but
models are in very good agreement precipitation will be out of the
mid-state and into East TN before breakfast tomorrow with no severe
threat and none of that white stuff. In fact, the progressive nature
of this system is also causing QPFs to continue to dwindle. A few
spots east of I-65 might see 1/2", but the bulk of the area will be
lucky to see 1/4".
&&
.LONG TERM...
(Friday through next Wednesday)
Issued at 1127 AM CST Wed Nov 27 2024
The bigger story with tonight`s frontal passage will be temperatures,
as we will get multiple shots of CP air over the next several
days. The first one will drive lows Friday morning into the low
30s and upper 20s and this will be the one everybody will be
interested in because it could be the first time BNA reaches the
freezing mark this fall. Current probs have BNA being 32 or
colder around an 80% chance, so it`s a pretty good bet, but
there`s also a 20% chance it doesn`t get there. If the mercury
reaches 32, we`ll beat the record by two days. If it doesn`t,
Saturday morning will be a slam dunk as morning lows are expected
to be in the upper teens and low 20s.
If you saw our socials yesterday, I posted a probability graphic of
a tenth of inch of snow or more Saturday night. They`re still pretty
meager with a clipper system expected to swing through the region
after sunset Saturday. Clipper aren`t usually prolific snow
producers in Middle TN. However, ensembles increased the chance of
a tenth or two of snow on the far Upper Cumberland Plateau to
about 40-50% with counties along the KY state line at about a
20-30% chance of dusting. If the Upper Plateau sees any of the
white stuff, impacts should be pretty minimal, but keep this
potential in mind if you`re going to be traveling through this
area on Sunday.
What this clipper will also bring with it is another shot of colder
air. Monday and Tuesday mornings might see widespread teens across
Middle TN, so once you get those parkas out for Saturday morning,
don`t put them up. CPC shows high chances of below normal
temperatures well into the 8-14 day window. Fall might just be here
for good.
&&
.AVIATION...
(00Z TAFS)
Issued at 512 PM CST Wed Nov 27 2024
A warm front sits just to the NW of Middle Tennessee as we head
into the evening. A surface low currently centered near Texarkana
will race toward the ENE during the evening and pull a cold front
through Middle Tennessee. So look for showers to become more
prevalent during the next few hours while ceilings drop through
the MVFR category all the way down to IFR/LIFR. Winds will be
gusty at times as they shift around to the NW with the fropa.
Showers will likely be gone prior to 12Z, but low ceilings are
likely to stick around throughout Thanksgiving Day.
&&
.PRELIMINARY POINT TEMPS/POPS...
Nashville 43 49 31 46 / 90 30 0 0
Clarksville 40 48 27 43 / 90 20 0 0
Crossville 39 46 26 40 / 100 80 0 0
Columbia 42 50 29 46 / 90 30 0 0
Cookeville 40 46 28 41 / 100 80 0 0
Jamestown 38 46 27 40 / 100 90 0 0
Lawrenceburg 42 48 29 45 / 90 40 0 0
Murfreesboro 42 49 29 45 / 90 50 0 0
Waverly 40 49 29 43 / 90 20 0 0
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE.......Rose
SHORT TERM...Unger
LONG TERM....Unger
AVIATION.....Rose
Area Forecast Discussion
National Weather Service Springfield MO
836 PM CST Wed Nov 27 2024
.KEY MESSAGES...
- Light rain, drizzle, and patchy fog will move across the area
this afternoon and evening with the highest chances across
central Missouri. Rainfall amounts will generally remain below
0.15".
- There is a very low-end chance (<10%) for a brief period of
light drizzle, potentially freezing, along and north of I-44
between 3-10 AM Thursday morning. If this worst-case scenario
occurs, no ice accumulation is expected.
- Much colder temperatures will occur from Thanksgiving through
the weekend into early next week.
- A quick moving clipper type system will push through the
region on Saturday bringing a chance of light snow to
portions of the area.
&&
.UPDATE...
Issued at 836 PM CST Wed Nov 27 2024
Very light rain to make its way across the northern CWA this
evening as cold advection interacts with weak lift from a jet
streak. Lift weakens after midnight which should bring an end to
any accumulating precipitation.
23z RAP offers a period of sub freezing temperatures from
11-14z mainly to the north of I-44 and while 0-1Km RH climbs
it fails to reach saturation so without low level lift the
potential of freezing drizzle will be low though this will
continue to be monitored. Should drizzle/freezing drizzle
form...amounts will be very light.
&&
.SHORT TERM /THROUGH FRIDAY/...
Issued at 230 PM CST Wed Nov 27 2024
Current radar imagery depicts a large swath of drizzle south of
I-44, and light rain north of I-44. These are a result of a
low-amplitude mid- and upper-level trough moving through the
region. This wave is moving overtop a WSW-ENE oriented cold
front dropping through southern MO.
Light rain, drizzle, and patchy fog through this evening:
As the front pushes south through the day, the drizzle (and
patchy fog out in the eastern Ozarks and Branson area) will
retreat to our southern border, and the light rain will move
through from the north. The light nature of the rain will keep
amounts less than 0.15", with amounts closer to 0.15" toward
central MO. However, some "heavier" bands may develop as strong
650 mb frontogenesis parallel to the mid-level temperature
gradient is occurring with the precipitation in north MO. Models
forecast this to continue into our northern CWA. So, some
localized areas could see amounts up to 0.25" since the term
"heavier" really means, "less light" rain.
<10% chance for freezing drizzle early Thursday morning:
As the front clears through the region, colder air will quickly
dive in, bringing temperatures below freezing along and north of
I-44 around sunrise Thanksgiving Day. While most models clear
clouds out as the sun rises, RAP and 30-60% of the HREF model
members keep low-level stratus clouds through at least 11 AM.
Particularly, RAP forecast soundings depict saturated low-
levels below an inversion, indicating warm-rain processes. This
may be enough for drizzle to develop along and north of I-44
between 3-10 AM. With freezing temperatures, this could be
freezing drizzle. However, we want to stress that this is a very
low-end chance/confidence worst-case scenario and just wanted
to message as a lot of people will be traveling Thursday
morning. Additionally, road temperatures could inhibit any
impact if it does occur, but bridges and overpasses could still
be impacted at the least.
The main uncertainties are in low-level rising motion. Behind
the front, upward motion is forecast to be meager, however,
northerly flow up the Ozark Plateau could compensate a bit.
Additionally, only a select few models depict this low-level
saturation. Notably, the NAM (which has a moist bias) does not
depict such high low-level saturation, pointing to a much lower
chance for drizzle. Conditions will continue to be monitored,
but this is what we know at the moment.
Otherwise, the cold air will keep highs around 40 F with lows
Thursday night dipping into the lower to middle 20s.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
Issued at 230 PM CST Wed Nov 27 2024
Colder temperatures through the weekend and early next week:
The longwave pattern will keep a trough churning over the east
CONUS with the height gradient edging into our region. This
will allow <0 C 850 mb temperatures to hang around for an
extended period of time. This will keep below normal
temperatures to be locked into our region through the weekend
and into early next week. Highs will range from the middle 30s
to the middle 40s across the region through Tuesday. Cooler
temperatures will be in our northern CWA with warmer
temperatures toward the south MO border. Lows will generally be
in the 20s, but Saturday night/Sunday morning could see
temperatures as low as the middle teens. There`s a 25% chance
lows are in the middle teens Saturday through Monday.
Ensemble cluster analysis then points to a return to near normal
temperatures as the longwave pattern slowly exits the eastern
CONUS with current forecast highs near 50 F next week.
Clipper system to bring 10-50% chance of light snow Saturday:
Within the longwave pattern over the east CONUS, a subtle
shortwave trough will sprint through the region from the
northwest. This will be a clipper system with limited moisture
thanks to the cold front from today diving to the Gulf. With the
wave being small and embedded in faster upper-level flow, the
system will be quick as well. However, since cold temperatures
will be locked in place, this system is likely to produce light,
fluffy snow. Accumulations should stay toward central MO, with
advertisement of up to 0.5-1 inches in our northeast CWA at the
moment. However, recent trends point to increasing confidence in
a bit stronger ascent within the dendritic growth zone which
could support some sneaky heavier snow, especially if a
mesoscale band is able to set up. Higher-end ensemble members do
point to 2" clipping into counties such as Morgan, Miller, and
Maries counties. The best chance for a scenario like this will
be toward central MO, largely outside of our area. Trends will
continue to be monitored.
&&
.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 530 PM CST Wed Nov 27 2024
IFR Stratus and patchy drizzle with lowered visibilities to be
noted overnight. Current LIFR conditions along the MO/AR border
influenced by moisture convergence along a exiting surface
front...whereas ceiling north of the front closer to I-44
improve rapidly to VFR. This will be short lived as low level
lift and cold advection arrives causing the moist layer just
above the surface to be lifted and saturate mid to late evening
as evidenced by IFR conditions along I-35.
Models generally support the second IFR band to be rather
short-lived at 3-6 hours, with a few lasting the saturation
through daybreak.
&&
.SGF WATCHES/WARNINGS/ADVISORIES...
KS...None.
MO...None.
&&
$$
UPDATE...Runnels
SHORT TERM...Price
LONG TERM...Price
AVIATION...Runnels