Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/27/21
Area Forecast Discussion
National Weather Service Binghamton NY
1032 PM EST Sun Dec 26 2021
A weak system will bring a wintry mix to the region Monday and
Monday night with light ice accumulations likely. For the rest
of the week, a series of systems will bring multiple chances
for rain and snow.
.NEAR TERM /THROUGH MONDAY NIGHT/...
930 pm update...
Little change again. Radars showing next to nothing for showers.
Satellite showing the connection to Lake Huron gone with clear
skies over Lake Ontario. Still will be many hours before the
lake clouds over the cwa to go away. By that time clouds from
the next system will be here. With the clouds, temperatures
warmer than forecast so adjusted.
630 pm update...
Just minor changes. Isolated lake effect showers will end by 9
PM. Temperatures and winds in line with forecast. Biggest
changes was to increase cloud cover to cloudy for most of the
area this evening. Low level lake moisture from Lakes Ontario
and Huron will be hard to erode with light winds despite the
ridge of high pressure that moves in tonight.
500 pm Update...
Lake enhanced showers continue to develop as a mix. As
temperatures continue to cool late this afternoon and evening,
snow will be the main ptype. Following CMC Reg and HRRR
guidance, there is a broad area that could see some light snow
showers as narrow bands develop. This area includes the Finger
Lakes and extends southeastward into the northern portions of
the Catskills. Late this evening, flow becomes more northerly as
high pressure moves in. This high will will bring drier air and
cuts off any lingering lake effect snow showers. Generally, a
half inch or less is expected but up to an inch locally would be
possible in Onondaga and Madison Counties. Skies will remain
cloudy during the overnight as low-level moisture hangs around.
Temperatures will be mainly in the 20s but teens will be
possible in higher elevations and northern Oneida County.
Dry conditions are expected through the early morning hours on
Monday. A surface ridge will pass through on Monday. To start,
light snow showers are expected as far east as I-81 in CNY and
the Poconos in NEPA. Light accumulations are expected at this
time as the snow will quickly transition to a wintery mix by the
afternoon. This system continues to pass through during the
afternoon, bringing a wintry mix across the entire region. Areas
that manage to get into the mid 30s will have just rain by the
evening, but that will mainly be isolated to the lower
elevations. By late evening, freezing rain becomes a bit more
widespread which will lead to ice accumulations, especially in
higher elevations and locations that remain around freezing at
the surface. As such, a Winter Weather Advisory has been issued
for the entire forecast area. Ice accumulations are anticipated
to be up to one tenth of an inch with lower amounts more likely
towards the Finger Lakes. During the overnight hours, warmer
and drier air fills in with precipitation on the back end
transition to just rain. By the early morning hours on Tuesday,
most of the region will be dry but a wintry mix would still be
possible from Onondaga County across to Oneida County.
Temperatures during the day will warm up into the upper 20s and
mid 30s. Temperatures cool slightly in the first part of the
night before warming up through the overnight hours with most
locations in the 30s and parts of the northern Finger Lakes near
.SHORT TERM /TUESDAY THROUGH WEDNESDAY/...
315 PM Update:
The active pattern will continue during the short term period
with yet another wave expected to move through the region,
mainly Tuesday night into Wednesday morning. However,
temperatures will also continue to be on the mild side for this
time of the year.
A brief break is expected Tuesday morning through at least
midday, before this next wave begins to move into the area from
the southwest. Some model guidance has backed off a bit on the
start time slightly with drier air to overcome and therefore,
while the first chance for precipitation will be during the
afternoon across Northeast PA-Southern Tier of NY, the bulk of
the precipitation likely holds off until Tuesday evening. The
right entrance region of jet aloft will favor forced ascent.
Precipitation initially starts as mainly rain or snow, before a
weak warm nose may allow for some freezing rain to mix in
Tuesday night/Wednesday morning (especially east of I-81). At
this point, any snow or ice accumulations look rather light with
marginal surface temperatures (lows Tuesday night are currently
only expected to be in the lower to mid 30s after highs Tuesday
in the upper 30s to mid 40s).
The system begins to depart the area on Wednesday, therefore
allowing precipitation to gradually end. However, skies will
remain mostly cloudy. Temperatures will continue to be above
normal with a warm west-southwest flow, with highs expected to
mainly be in the 40s.
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
315 PM Update...
Still a lot of uncertainty (more than usual) with the long term
forecast with uncertainty regarding the timing of the next
disturbance to move through the area within zonal flow and if
there will be enough moisture in place. Continued to stick
closely to the NBM (National Blend of Models) due to the
uncertainty. A more amplified pattern still looks to develop
sometime next weekend, with increasing precipitation chances,
especially towards the Sunday period. Temperatures will continue
to be mild, but colder air looks to move into the region by the
end of the weekend into the beginning of next week with the more
345 AM Update...
Temperatures will settle slightly down closer to average as flow
becomes more zonal during the second half of the week.
Precipitation chances ramp up next weekend, but before then dry
weather will be more dominant.
The models disagree on whether another wave Thursday will
contain enough moisture for a quick shot of mixed snow-rain.
However, they generally do have the pattern trending more zonal
behind that wave, with drier air overall. Precipitation cannot
totally be ruled out from late Thursday through early Saturday,
but it is fair to say it is below climatological average chances
and could turn out to be a dry window.
Pattern appears to trend more amplified over the weekend, with a
rather deep trough ejecting out of the western U.S. and perhaps
sending a strengthening low pressure system out of Plains and
in time to the East Coast. A lot remains to be sorted out in
coming days, but this does at least support a ramping up of
precipitation chances next weekend, especially Saturday night-
Sunday. Amplifying patterns often end up evolving more slowly
than the models initially suggest, so it would not be surprising
to see things skew a bit later.
.AVIATION /04Z MONDAY THROUGH FRIDAY/...
Low lake enhanced clouds continue to blanket CNY and NEPA. Cigs
are generally hovering around 3000ft on either side of MVFR.
Latest RAP trends suggest the moisture should be lowering
however also eroding from the top of the cloud layer. Thus
shortly after 10z most of the MVFR if any should scatter with
thick high clouds aloft. The high clouds begin to rapidly lower
to MVFR by Monday night as the next round of showers and mixed
precipitation enters the region.
Northwest winds will remain gusty although starting to become
calmer this evening. Winds will be light and variable early
Monday morning before becoming west- southwesterly by Monday
Monday Night-Friday...Additional chances for rain and snow
showers with associated occasional restrictions.
PA...Winter Weather Advisory from 11 AM Monday to 1 AM EST Tuesday
NY...Winter Weather Advisory from 1 PM Monday to 1 AM EST Tuesday
Winter Weather Advisory from 11 AM Monday to 1 AM EST Tuesday
Winter Weather Advisory from 1 PM Monday to 7 AM EST Tuesday
Area Forecast Discussion
National Weather Service State College PA
1034 PM EST Sun Dec 26 2021
A weak low pressure and a warm front will bring the likelihood
of a period of light mixed precipitation or rain on Monday.
Other than Monday, when temperatures will be close to normal,
we`ll be above normal for the new week with several weather
systems bringing periods of mainly rain. Some very light
amounts of snow could mix with the rain across the far north
Another warm surge will be possible at the start of next
weekend, before colder weather follows for late next weekend.
.NEAR TERM /UNTIL 8 AM MONDAY MORNING/...
Radiational cooling is not ideal, but is occurring slowly at
this time. Temps will likely level off in a few hours. Light
north wind is allowing slightly drier air to come in from the
north. The drier air is notable since that may help the wet-bulb
effect at the onset of precip to cool things off even more than
expected and thus allow for a slightly longer period of
Temps falling as scheduled for the time being, but clouds are
already thickening up a bit faster than expected. Have raised
temps a deg or two for the overnight. However, it`s already 32F
at all our nrn tier METARs, so no need to panic that temps won`t
get down and stay down below freezing overnight in the north
and Laurels as Somerset is also 32F.
NW flow continues, as do the typical/resultant stratocu.
Everything is on track for the daytime and early night. A warm
front will be lifting NE thru the OH Vally. WAA strong late
tonight as the nose of a 50KT LLJet moves over OH and into wrn
PA. Wind goes light for a short time tonight, and clouds stay
about the same until high clouds move in after midnight. This
should allow temps to drop into the 20s in the nrn mtns and
L30s elsewhere. This sets the stage for some light snow and
mixed precip to start later tonight in the SW. Timing is very
similar to the last few runs, arriving before sunrise in the
Laurels, but wait until after sunrise elsewhere.
.SHORT TERM /8 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
Recent HRRR output does make a slightly enhanced band of snow
lift north/east through the Alleghenies in the morning. HREF
Prob 1"/hr rates start to show up for an hour or two near UNV.
So, we may see a decent snow rate for just a brief time. Have
kept snow/sleet numbers as is for now, though...about an inch to
two in the Alleghenies and Blair/Hunt counties...and less than
an inch elsewhere. The snow will probably be a little too late
to impact most people`s morning commute - but the Laurels and
wrn mtns will see snow/mix begin around sunrise, maybe an hour
before in Somerset and Johnstown.
It`s all about precip type forecast-wise this shift. Warm air
moving in over CAD/cold wedge in place will mean a period of
frozen then freezing precip is likely until temps warm during
the daylight hours and also from SW to NE with the WAA and
diurnal heating working together despite the very shallow sun
angle. In general, most locations will receive a 2-4 hr period
of mix, and some locations will have FZRA stick around longer
as they struggle to get above freezing. Temp profiles from NAM
yield a fairly deep (2-3kft) sub-freezing layer until the aftn
for UNV, later for IPT and all day for the NE mtns. Thus, there
could be more sleet/PL than FZRA overall. Considering an advy
for ZR for much of the area, but the Lower Susq/srn tier and
also far NW/Warren Co, where the effects of CAD go away quickly.
Something else going against FZRA is the abnormal warmth we
have/are experiencing. Despite air temps going below freezing
tonight everywhere, it may take a few more hours of below
freezing temps to really make FZRA a /serious/ threat rather
than nuisance/advy level. QPF is also pretty light during the
most- probable time for FZRA. Thus, ice accums should not get
into the warning (0.25/0.50") range anywhere in the CWA. Most
likely course of action is issuance of a winter wx advy (for
FZRA) for much of the area, time-stepped/segmented somewhat for
timing. Don`t want to get too cute with timing, though.
Uncertainty with the amount of heating we can muster, and
intensity of the precip. Only a light accum of snow and sleet is
likely, but again, some uncertainty exists with the depth of
cold wedge and eventual amount of PL. Again, temps should get
above freezing by day`s end in the NE, but pretty early in the
day for the SW. The highest elevations may stay coldest longest
since the wedge is that deep (2-3kft). Thus, the valleys may
warm and dump the FZRA threat before the hill tops.
Temps remain mild Mon night. As the rain tapers off to some DZ,
the temps should stay (mainly) above freezing. While a little
mix may again become possible in the NE as temps cool to near
freezing, it will likely be dry.
.LONG TERM /TUESDAY THROUGH SUNDAY/...
Fast moving systems this week will make for mainly some rain
at times this week, with perhaps a bit of snow across the far
north mixed in at times. Timing of systems could result in
changes to the forecast very far out in time.
The main change this evening was a bit of a milder solution to
the start of next weekend. This has been the trend this season,
a warm up about every 6 to 7 days. See no reason not to buy into
the next warm up.
Colder air likely to follow late next weekend. By then, it
may end up not being quite as significant of cool down as
some models have it.
Earlier discussion below.
Another system will quickly follow on the heels of Monday`s,
with precipitation arriving Tuesday morning into the afternoon
as a warm front approaches central PA. Given the lack of a cold
antecedent airmass before the arrival of the precipitation, not
currently expecting significant wintry precipitation.
Transient/weak surface ridging will not have much residence time
across the Commonwealth prior to warm/moist advection filtering
in from the southwest on Tuesday, so have opted to keep the
prevailing weather grids comprised of only rain/snow at this
time. Very possible that we could see a brief period of light
freezing rain/sleet as wet-bulb cooling takes place, but again,
the lack of a deeper and more significant cold dome should
preclude greater concerns. Could see up to 1-2 inches of snow in
spots across the northern tier by the time warm air advection
sweeps through all of PA into Tuesday night. Look for mainly
rain Tuesday night, with portions of the northeast continuing to
see a mix with some snow.
Conditions should dry out through the day on Wednesday as a
frontal boundary slowly sags off to the south of PA. Southwest
flow aloft, in response to troughing to our west, will keep
things unsettled for late week as temperatures remain above
normal. An embedded disturbance should knock temperatures down a
bit for Thursday, but still expecting above normal readings in
the upper 30s north to upper 40s south. Passing rain/snow
showers with no real impact will therefore be possible
Thursday/Friday, before a potentially more significant
precipitation event sets up for later New Year`s Day into the
second half of next weekend. Still a great deal of uncertainty
in all aspects of this system`s development at this time.
.AVIATION /04Z MONDAY THROUGH FRIDAY/...
At 00z, MVFR cigs persist over the northwest mountains (BFD),
with generally VFR conds elsewhere. The low clouds over the
northwest could briefly scour out during the predawn hours,
before returning along with wintry precip around daybreak.
Light snow will overspread the remainder of central PA from
west to east Monday morning. As warmer air arrives aloft, the
precip gradually change over to an icy mix and then to plain
light rain during the afternoon. Restrictions will accompany the
precip, with conditions deteriorating to IFR for most of
central PA by Mon afternoon.
Lingering light rain will gradually taper off Monday evening
into Mon night.
Mon night...IFR early, improvement late.
Tues-Tues night...Another round of rain and restrictions will
overspread the area, and a wintry mix is possible north.
Wed...Improvement thru the day.
Wed night-Thurs...Light rain (wintry mix possible north) and
Winter Weather Advisory from 11 AM Monday to midnight EST
Monday night for PAZ037-041-042-053-058.
Winter Weather Advisory from 8 AM to 3 PM EST Monday for
Winter Weather Advisory from 6 AM to 1 PM EST Monday for
Winter Weather Advisory from 9 AM to 6 PM EST Monday for
Area Forecast Discussion
National Weather Service Duluth MN
854 PM CST Sun Dec 26 2021
Issued at 854 PM CST Sun Dec 26 2021
No significant changes to the going forecast are anticipated this
evening as the storm in on track to impact the Northland tonight
Area radar and satellite show widespread snow from North Dakota
through northern and central Minnesota into west central to
northern Wisconsin. IR and water vapor imagery have shown cooling
cloud tops through the evening and as saturation has occurred
moderate to at times heavy snow has developed. Several
observations were showing a half mile visibility, including KBRD
and K04W. The RAP seems to be doing a decent job indicating
saturation and its forecast sounding suggests saturation and snow
commencement in the Twin Ports around or shortly after 11 pm with
the snow continuing north through the night. It may not reach
Grand Marais and Grand Portage until 3 AM or after. A tight
pressure gradient between high pressure in Ontario and the low
that stretched from the Northern Plains into the Central Plains
was leading to gusty winds. Pressure falls ahead of the low were
also aiding in stronger winds over the lake. There is a concern
that blizzard or near blizzard conditions may develop in the Twin
Ports. We added a mention of near white-out conditions to the
Winter Storm Warning and we`ll monitor for a possible upgrade to a
Blizzard Warning. The worst conditions in the Twin Ports area will
occur after midnight through 8 AM.
.DISCUSSION...(This evening through Saturday)
Issued at 444 PM CST Sun Dec 26 2021
Summary: A winter storm is set to move in across the Northland this
evening. Widespread impactful snow accumulations are expected.
Snowfall rates will be heavy at times with gusty winds causing
blowing snow. The highest winds and worse conditions are expected to
be after midnight along the North Shore where a Blizzard Warning has
been issued. Snow chances will begin to taper off tomorrow evening
with some freezing drizzle populating over northern WI. There is a
brief lull in weather systems Monday night before another round of
snow arrives Tuesday bringing a couple of additional inches of new
Surface high pressure over southern Canada is slowly being ushered
off to the northeast today as a 170kt jet barrels over the Front
Range. Return flow on the backside of the departing high pressure is
advecting low level moisture over the relatively warm lake waters.
Satellite showcases this as low stratus that has penetrated inland
through the Arrowhead and portions of Bayfield. As the flow
continues we may see some early onset of snow along the North Shore
where the terrain enhancement is common. Further to our west lee
cyclogenesis was beginning to take shape this morning with a surface
low developing over the Northern Plains. This low will be the focal
point for our inbound winter storm this evening.
As the low advances on the region it will first have to overcome the
dry air in place over the region. Both upstream stations of MPX and
ABR highlight a dry slot of air from 850mb up to the mid levels. As
the system eats away at the dry air that will likely put the early
onset of snow falling in Brainerd by this evening. The latest high
resolution model guidance suggests that this initial burst could be
quite heavy at times with snowfall rates between 1 to 1.5 inches an
hour at times. The broad scale forcing highlighted by a deep omega
corridor will rotate northeast out ahead of the surface low.
Snowfall will spread northeast lock in step with this feature with
even higher snowfall rates and amounts expected along the North
Shore. The lake and terrain enhancement could see snowfall rates of
of 1.5 to 2 inches per hour in the early morning hours. In addition
to the snowfall there is a concern for some stronger winds to
accompany this system as well. The strongest winds will likely be
along the North Shore with winds out of the east initially.With this
in mind we have issued a Blizzard Warning for southern Lake and Cook
Counties. This warning may need to be expanded further north
depending on how the conditions trend. Elsewhere we have kept the
Winter Storm Warnings going. There could be an argument to be
made in changing Burnett, Washburn, and Sawyer to Warnings as
well, but we will hold off for now.
Monday morning the center of the low will be moving overhead with
mostly snow still ongoing across the region. NW WI may have a
change in precipitation type as most of the soundings are indicating
a loss of ice crystals aloft. This will likely result in freezing
drizzle on the backside of this system for a couple hours.
Accumulations at this time are expected to be minimal with values of
around 0.05 inches in NW WI. The bulk of the moisture is set to
move off monday afternoon leaving the region with a fresh snowpack.
We have just a brief lull in our snow activity Monday night before
another system is projected to slide across the region once again.
Additional snow accumulations will be abound across the Northland
with plenty of cold air in place for dendrites to grow. However,
this system does not pack quite the punch of the previous low due to
lack of strong synoptic drivers. Nevertheless and additional couple
of inches will be tacked on across the Northland.
Wednesday surface high pressure ridges in from the west ushering out
any remaining precipitation. Colder temperatures will have settled
in across much of the region with highs in the single digits for
northern MN and teens for northern WI. A few shortwaves are
advertised in the extended forecast and could bring some additional
snowfall Thursday and Friday but at this time there are no strong
signals for any significant weather.
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 538 PM CST Sun Dec 26 2021
A large winter storm is set to make its way across the Northland
this evening. Out ahead of this system remains an MVFR stratus deck
over DLH/HIB/INL. The MVFR ceilings may dissipate for a time at
DLH as low level winds veer slightly and these lake induced
ceilings push north. The system will first enter the BRD area
with heavy to moderate snowfall rates and conditions likely
dropping to VLIFR. These high snowfall rates will spread east and
north overnight impacting HYR/DLH and possibly HIB. Overall snow
totals are expected to be at least 5 inches at most the terminals
with DLH/BRD possibly seeing 8-12 inches. Gusty easterly winds
will occur tonight, highest around Lake Superior, and will cause
blowing and drifting. On the backside of this system some freezing
drizzle will be possible over HYR Monday morning.
Issued at 819 PM CST Sun Dec 26 2021
A strengthening pressure gradient was occurring over Lake Superior
with high pressure over Ontario and low pressure stretching from
the Central Plains into the Northern Plains. Pressure falls across
Minnesota, North Dakota, and Iowa were aiding in producing
stronger winds this evening. Gusts in the Twin Ports were from 30
to 35 knots per KDYT observations. We issued a Gale Warning now
that goes into Monday evening for the Twin Ports area. A decrease
in winds is expected late tonight into Monday morning before they
veer to southwest and increase again. Winds will then veer to
west to northwest Monday night, decreasing through the night. We
changed some of the other headlines around as well to try and
better reflect the forecast with the rest of the nearshore waters
under Gale Warnings or Small Craft Advisories. The low pressure
area will lift north tonight moving over Lake Superior Monday
evening then continuing east to northeast Monday night. Strong
west to southwest winds will occur as the low passes by with gusts
of 40 to 45 knots.
In addition to the strong wind, snow will be developing from south
to north tonight, continuing into Monday. Snow will be heavy at
times reducing the visibility to less than a half mile at times,
this will be most likely along the North Shore.
.PRELIMINARY POINT TEMPS/POPS...
DLH 21 28 0 22 / 100 90 0 60
INL 10 24 -4 13 / 80 90 10 30
BRD 20 27 -6 17 / 100 80 0 80
HYR 21 31 -2 25 / 100 70 0 70
ASX 21 32 5 27 / 100 80 10 60
WI...Winter Storm Warning until 6 PM CST Monday for WIZ001-002.
Winter Weather Advisory until 6 PM CST Monday for WIZ003-004-
MN...Winter Storm Warning from midnight tonight to 6 PM CST Monday
Winter Storm Warning until 6 PM CST Monday for MNZ010-011-018-
Blizzard Warning from midnight tonight to 6 PM CST Monday for
LS...Gale Warning until 2 AM CST Tuesday for LSZ150.
Small Craft Advisory until 10 AM CST Monday for LSZ121-147-148.
Gale Warning from 10 AM Monday to 2 AM CST Tuesday for LSZ121-
Small Craft Advisory until 1 PM CST Monday for LSZ143-146.
Gale Warning from 1 PM Monday to midnight CST Monday night for
Gale Warning until midnight CST Monday night for LSZ144-145.
Gale Warning until 10 AM CST Monday for LSZ140>142.
Area Forecast Discussion
National Weather Service Grand Rapids MI
1015 PM EST Sun Dec 26 2021
Issued at 949 PM EST Sun Dec 26 2021
The past couple of runs of the HRRR have been showing a sizable
area of 3 plus inches of snow for the morning commute in central
and northern parts of our CWA with southern zones seeing a tenth
or so of an inch of freezing rain. Upstream an expanding area of
precipitation has been developing for northeast IA into IL and WI.
There has even been a few thunderstorms. Most location in our CWA
have fallen below freezing with the surface dewpoints several
degrees lower. Thus as this precipitation moves into MI it will
likely be heavy at times. Trends in the guidance/forecast
soundings suggest we will see more snow than thought previously.
We trended the forecast in that direction. Since the bulk of it
starts up before the morning commute and continues through the
commute...we issued a headline for nearly all of our CWA.
Interstate 94 should be just south of the main snow axis...but
that is the region which could see the most freezing rain. Sleet
is certainly possible as well. The main area of precipitation
departs to the northeast of Lansing and Mt Pleasant by mid
morning. Temperatures will climb above freezing during the
.DISCUSSION...(This evening through next Sunday)
Issued at 315 PM EST Sun Dec 26 2021
- Wintry Mix tonight and again Tuesday evening
After digesting the range of model data from last night and this
morning, and after collaborating with surrounding offices, the
consensus is that we will not issue Winter Weather Advisory for
tonight`s quick burst of snow/mixed precipitation as the duration
and precip amounts are limited.
Generally, our forecast for precip amounts and types are close to
the 12Z deterministic GFS forecast, showing snow amounts of an
inch or two across the northern half of the forecast area with
less than an inch south and about 0.05 ice accumulation. The 12Z
ECMWF is colder, with 2 to 3 inches of snow, while the NAM is
warmer with a mix of sleet and freezing rain. All models show a
quick change to freezing drizzle or drizzle as the dry slot moves
The scenario we see unfolding is similar to what we have seen
several times in the last month as warm advection begins with a
wedge of dry air below cloud base slowly being saturated by
evaporating snow...leading to cooling of the column and eventually
a quick burst of snow or mixed precip reaching the surface
followed by dry slotting with the DGZ drying out and precip
tapering off to freezing drizzle and drizzle.
There could be slick roads for a couple hours before surface
temperatures climb above freezing, especially across the northern
forecast area, but this can be handled via messaging and a Special
A similar event is forecast for Tuesday evening with a quick burst
of snow changing to rain or drizzle. Once again, impacts to travel
should be minor as snow amounts are forecast to be less than an
inch and air temperatures rise above freezing in southerly flow.
- New Year`s Day storm potential
The first significant winter storm of the season is taking shape
for the weekend as a deep western CONUS trough moves east and
surface cyclone tracks over or just south of Lower Michigan with
plenty of Gulf Moisture. Cold surface ridging is anchored to the
north, with model soundings showing heavy snow potential across
much of the forecast area as dynamical cooling occurs and cold air
is drawn into the storm. THere is still ensemble spread on the
track, which will pinned down better during the week.
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 636 PM EST Sun Dec 26 2021
An impactful weather system is to track through the TAF sites
later tonight into Monday. A wintry mix will arrive from west to
east after midnight with conditions expected to go IFR or lower at
times. A general snow to freezing rain/sleet to rain/dz scenario
is forecast. In addition...easterly wind gusts could top 25 knots.
By mid morning temperatures should be above freezing at all TAF
sites in Southwest Lower MI but IFR cloud cover and VSBYs look
likely into the afternoon. A wind shift from east to west
southwest is predicted in the mid to late afternoon hours as the
wave of low pressure tracks overhead. Conditions could improve to
MVFR by 00z Tue.
Issued at 315 PM EST Sun Dec 26 2021
No changes to the Small Craft Advisory. Offshore winds will gust
to 30 knots at times tonight with the higher winds and waves out
towards the 5 mile mark offshore.
MI...Winter Weather Advisory from 1 AM to 9 AM EST Monday for
LM...Small Craft Advisory until 7 AM EST Tuesday for LMZ844>849.
Area Forecast Discussion
National Weather Service Jackson MS
957 PM CST Sun Dec 26 2021
Updated for evening discussion.
Very few changes overall as warm and humid air remains in place
over the region. Southerly winds will continue to reinforce that
warm air through the overnight hours. Best chances for fog will
remain in the Pine Belt...and HRRR continues what amounts to be a
persistence forecast with low clouds developing and spreading
across the forecast area after 06Z.
Prior discussion below:
Tonight and Monday: See the forecast for today and copy and paste
for tomorrow. With not much change in the weather pattern we will
see much of the same conditions for the ArkLaMiss tomorrow. Upper
ridging will remain in place across the northern Gulf, which will
continue to keep a hold on our region. Southerly winds will
continue to bring warm, moist air north. A front will remain to
our north but warm conditions will occur across our region. The
day will begin similarly to today with stratus and some patchy fog
in place. The fog is most likely to occur in the Pine Belt, with
low stratus elsewhere. Overnight lows will be warm once again with
readings in the 60s, with mid 60s in the west. The clouds will be
slow to break up once again tomorrow, with likely overcast skies
through much of the morning into the early afternoon. Dry
conditions are expected with highs in the upper 70s to around 80
degrees possible again. /28/
Monday night through New Years Day: Monday evening the first of
three cold fronts to drop into our region through the period will be
stalling across north Mississippi while ridging surface and aloft
centered southeast of our CWA tries to remain dominant. Monday
evening is still expected to remain dry but model consensus now
suggests a few showers may develop across our southern zones prior
to sunrise. Rain chances will expand over the remainder of the CWA
Tuesday as our anomalously moist airmass heats up through the day.
Near record high temperatures are expected again Tuesday as many
sites top out in the lower 80s.
Warmer than normal temperatures and moisture will continue areawide
into Wednesday ahead of the second cold front that will be
approaching our CWA from the northwest. Overall, thoughts on
severe storm potential for Wednesday afternoon and evening in our
CWA hasn`t changed much from yesterday. Wl still have an
anomalously warm and moist airmass in place while unidirectional
deep layer shear increases over our region. The cold front will be
nearly parallel to the flow aloft leaving it to drift into the
northwest portions of our CWA toward sunrise Thursday. There
remain some differences in the models with this system so wl
continue to mention the potential for a few severe storms in our
HWO Wednesday afternoon and evening. With the winds aloft
remaining southwesterly, the cold front is expected to stall
across our southern zones Thursday night. The stalled front will
remain the focus for precipitation development through Friday
night when it moves back north of the CWA as a warm front.
Saturday rain chances will increase across our CWA downstream of a
shortwave trough moving over the southern Plains. There are
differences in timing and strength with this system but model
consensus shows a greater potential for severe storms in our CWA
Saturday and Saturday night than with the Wednesday system. A
return to more seasonal temperatures looks likely Sunday in the
wake of the third cold front Saturday night into Sunday morning.
00Z TAF discussion:
Similar pattern expected... VFR for now, deteriorating conditions
overnight with warm and moist air advecting into the region. Fog
development in the south...and MVFR/IFR cigs btwn 06-12Z. Winds
picking up some gusts midday as cigs break up and improve.
.PRELIMINARY POINT TEMPS/POPS...
Jackson 63 80 61 80 / 0 2 13 52
Meridian 61 79 61 78 / 0 3 14 56
Vicksburg 65 80 62 82 / 1 3 12 36
Hattiesburg 60 80 61 80 / 0 4 20 58
Natchez 65 80 63 81 / 1 3 13 40
Greenville 65 79 63 78 / 2 9 13 41
Greenwood 65 78 63 79 / 3 7 12 46
Area Forecast Discussion
National Weather Service Blacksburg VA
1043 PM EST Sun Dec 26 2021
Low pressure moving from the central and northern Plains through the
Great Lakes will push a warm front north through the Mid Atlantic
region tonight and Monday, with light rain ahead of the front from
the Ohio Valley into southeast West Virginia and the Alleghany
Highlands. The cold front with this system will reach the area
Tuesday night resulting in chance of rain by Wednesday. Another low
pressure system will approach the area by the end of the the week
with a better probability of widespread precipitation.
.NEAR TERM /THROUGH MONDAY/...
As of 1035 PM EST Sunday...
High clouds moving and causing temperature drop to slow over
most of the area. Will likely see some low level moisture moving
in/developing overnight as flow turns more easterly and wedge
sets up. Ascent with warm front may start to produce light rain
across the WV mountains late tonight, creeping into the
Alleghanys of VA but majority of solutions keep bulk of precip
further north across the upper Ohio Valley.
Previous discussion from early this evening...
Surface high over the Great Lakes will work east tonight into
Monday while stalled out front across the TN Valley/Carolinas
remains in that vicinity through the night. Overall, not seeing
much threat of rain until after daybreak Monday. Should see
increasing clouds overnight. Forecast temperatures tricky as we
start off with clear skies and light winds allowing temps to
fall quickly this evening, but should steady out in the upper
30s to mid 40s late tonight.
Lowered temperatures for tonight and Monday.
Little change is expected in the synoptic pattern with deep
troughing in the central and western United States and broad ridging
over the southeast. At 850mb winds back from the northwest to
southwest tonight then increase on Monday. Models were showing some
low level convergence as early as midnight in the mountains tonight,
then stronger forcing farther west and north by Monday morning.
Winds will diminish tonight so will have the opportunity for
temperatures to drop quickly in the evening before the clouds fill
back in. Leaning toward colder guidance for lows tonight and
expecting temperatures to become steady or slowly warm once the
clouds arrive. ill keep the highest probability of precipitation in
southeast West Virginia. Low clouds fill in this evening north of
At the surface the front stalled over North Carolina and Tennessee
will return slowly north on Monday. The Alleghnay Highlands may not
get to the warm side of the front by the end of the day. Lifted
index forecasts from the NAMNest, GFS and RAP suggest only
Bluefield into western Watauga County may be firmly on the warm
side of the front by late Monday. Will be leaning toward the much
cooler of what is an unusually large spread in guidance for
temperatures Monday. Have lowered highs around five degrees for
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/...
As of 200 PM EST Sunday...
Increasing chances of rain through the period with isolated
thunderstorms possible Wednesday afternoon.
During this portion of the forecast, our part of the country will be
between the center of a slowly parting upper low to our southeast,
and an approaching/building upper trough to the west. The result
will be a persistent southwest flow across the area, with periodic
shortwave troughs riding northeast from the Lower Mississippi Valley
toward and into the Ohio Valley. This scenario places our western
sections within the eastern extent of precipitation associated with
these waves, along with their associated warm and cold fronts.
As time progresses, the influence of the upper high to our southeast
lessens, and repeated weak systems with the southwest flow gradually
spread more and more into and across our region.
The most significant occurrence of this trend is expected to occur
on Wednesday, when a cold front will move into our region and stall.
This should bring the best coverage to rain to the area than we have
seen for a while. Also, there may be enough weak instability across
the far southern and southeastern sections of the region for an
isolated late day thunderstorm just in advance of this front.
Wednesday night, coverage of precipitation should lessen a bit after
sunset, but yet another disturbance is expected to head northeast
along this front towards the region by daybreak Thursday. Look for
increasing coverage again during this time.
Temperatures during this portion of the forecast will continue to be
very mild for this time of year.
Confidence in the above weather scenario is moderate.
.LONG TERM /THURSDAY THROUGH SUNDAY/...
As of 1245 PM EST Sunday...
A potent cold front may cross our region on Sunday.
On Thursday, the transition to a more zonal pattern across our
region will continue as a shortwave trough moves through the
Tennessee Valley. This feature will help to shunt the upper
ridge/high farther southeast, with the resultant pattern after its
passage being zonal by Thursday night. We will need to keep an eye
on the expected track of this system. Currently, the most robust
dynamics and instability, possibly hefty thunderstorms, look to
remain southeast of the forecast area with a broader shield of rain
across our region. However, if the track of the system trends more
northward, southeast parts of our region could start being candidates
for the showery, potentially stormy, weather.
Thursday night into Friday look to be a period of transition. The
zonal flow looks to be only short lived. By Friday night, another
transition may take place that will have a strong influence on our
weather for the weekend. Model guidance varies on the timing of
these features, but we will be watching two upper lows, both with
Pacific origins. The one is expected to transition from the Pacific
Northwest into the Rockies. The other is expected to lift northeast
from the region of Baja California, and in some capacity interact
with the first low in central CONUS around Saturday morning. The
challenge currently will be timing/speed of each system and to what
degree each interact. Some solutions have a merging with notable
positive amplification of the two, while other solutions have more
of brushing of each system, but with both, as separate systems,
ejecting eastward and impacting our area in more of a one, two
punch, rather than a single blow.
Regardless of the merging versus little or no merging, trend over
our region will be for the low level flow to again back southwest,
and thus advect both increasing temperatures and more moisture back
into the region. The result for our area will be increasing chance
of rain heading into next weekend. While timing varies among various
deterministic models, each to some degree have the final upper low,
or the merged lows as a single entity, sweeping an impressive cold
front across our region. Depending upon the model, this could occur
as early as Sunday afternoon, or as late as Sunday night. Again, as
we get closer to the days in question, the answer should be come
clearer, but for now if timing of the best instability and shear come
together just right, along and ahead of the front, we will would
likely see at least robust showers, and isolated thunderstorms for
parts of the area, would not be a far stretch. However, for now, we
will limit the forecast to only showers on Sunday.
Temperatures during this portion of the forecast will continue to be
above normal for this time of year. Thursday or Friday will be the
warmest day during this period with Sunday the coolest.
Confidence in the above forecast scenario averages low to moderate.
There is better confidence in the overall, broader-view, expected
transitions in the synoptic pattern. There is lower confidence in
the more specific details such as timing of specific round of
heavier showers, or the potential for storms on the days noted above.
.AVIATION /04Z MONDAY THROUGH FRIDAY/...
As of 545 PM EST Sunday...
Will see VFR through the night til about 12-14z, when cigs drop
to MVFR, with a wedge taking up shop in the foothills/piedmont.
At least sub-VFR at most sites Monday with limited threat of
rain west of the LWB/BLF corridor, and attm left it out of the
Above average confidence for wind and visibility.. Average
confidence for ceilings.
.Extended Aviation Discussion...
MVFR ceilings may persist east of the Blue Ridge through Monday
Another period of MVFR clouds and a chance of precipitation for
the mountains is expected Tuesday night and Wednesday, along
with the potential for gusty winds.
Sub-VFR may impact most sites into Thursday as a frontal
boundary moves across. Thursday night and Friday look to be in
between weather systems with dry and VFR conditions.
As of 540 PM EST Sunday...
No record highs were set today.