Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/03/25
Area Forecast Discussion
National Weather Service Boston/Norton MA
1003 PM EST Thu Jan 2 2025
.SYNOPSIS...
Strong winds will slowly diminish overnight, although breezy
conditions will continue Friday and Saturday. Outside of a few
snow flurries across parts of Connecticut and western
Massachusetts this evening, dry weather will prevail. A cold and
dry weather pattern will set in for the weekend. A system should
track to our south early next week, although there is a chance
it brushes southern coastal areas with light snowfall. Below
normal temperatures continue for next week.
&&
.NEAR TERM /THROUGH FRIDAY/...
Still monitoring the lake effect snow band from Lake Ontario
that had made it east of the Berkshires. Seems mainly like
clouds at this point in time, with surface dew point
depressions of 15-20 degrees F. That a lot of low level dry air
to be overcome to generate much snowfall. Expecting drier
conditions to develop overnight. Used the last few runs of the
HRRR to tweak precipitation chances this evening, but further
adjustments will likely be needed.
West winds will continue to diminish as well, but it will remain
gusty into Friday.
Minor tweaks to temperatures, which looked to be good overall.
640 pm update...
still seeing the Lake Ontario streamer making its way into
southern New England. For the most part, its denoted by patchy
clouds and a spot flurry here and there. Appears to also be a
weak vort max across northern NY that is generating some
additional clouds and light flurries that are getting getting
into southern VT. None of the hi-res models are handling that
feature all that well, perhaps the 21z HRRR is the best. It
shows a little bit of flurry activity scooting across southern
NH and clipping the North Shore of MA, just north of Boston.
Tried to fold some of that into the forecast, showing a period
of mostly cloudy skies and a few flurries up along the NH border
between 04-07z.
On the wind aspect of the forecast, latest observations showing
the winds diminishing faster than forecast. Thus have taken the
wind advisory. It will still be breezy overnight, with west
winds still gusting 25-35 mph for most areas.
230 pm update...
Key Messages...
* Gusty winds will slowly diminish
* A few snow showers and flurries this evening for western
portions of southern New England
No big changes with the latest model guidance, and thus no real
big changes to the forecast. For most of us, the main weather
story are the gusty winds. The core of the low level jet aloft
is starting to move off to our east, and with sunset the
boundary layer mixing is weakening. So the trend in wind speeds
is downward. Still a pretty steep pressure gradient, so breezy
to windy conditions will continue all night. Will maintain the
wind advisory until 10pm, but that might be generous as the
chance of seeing gusts over 45-50 mph that late is pretty low.
Exposed high terrain locations (ie: Worcester Airport) will
remain windiest overnight.
A streamer from Lake Ontario is producing some flurries/light
snow showers across western MA. Radar showing some returns
making it as far east as Rhode Island, but given the very dry
boundary layer (RH values 25-35%) across the eastern half of the
area, most of what shows on radar is virga with only the
heartiest of rogue snowflakes making its way to the ground.
Spotter report also suggest a little graupel mixed in as well.
Hi-res guidance suggests the band will maintain itself across
New York overnight, however rapidly break up as it gets into
western MA. The westerly winds downsloping off the Berkshires
will also speed up that dissipation process. Have painted in
PoPs around 30% for the highest elevations of Hampshire and
Franklin counties. Perhaps some minor accumulations, but they
would be localized and not be of any significant impact.
With the breezy conditions overnight, low temperatures will be
fairly uniform. Stuck with a model blend to depict lows in the
lower 20s in the higher elevations to upper 20s at lower
elevations.
&&
.SHORT TERM /FRIDAY NIGHT/...
230 pm update...
Key Messages...
* Remaining breezy
Cold air advection continues as the west/northwest winds around
the large low pressure in eastern Canada will continue. 850mb
temperatures will fall to about -11C, which is fairly typical
for this point of the winter. Highs should be near normal. Winds
will still be breezy, but much less than today. Expect frequent
gusts 20-30 mph for much of the day. Airmass is pretty dry, so
outside of a few shallow daytime heating clouds, it should be
sunny. Exception will be across the Berkshires where residual
clouds from the Lake Ontario lake effect snow band will likely
be found. Can`t rule out a few more flurries in that part of the
area, but chances are less than 15% for measurable snow, so the
forecast is for dry weather. Fairly clear and getting more
chilly as colder airmass continues to move in. Look for lows in
the teens to lower 20s.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
230 pm update...
Key Messages:
* Below normal temperatures for the weekend, continuing through
next week.
* Low chance for a system to graze southern MA, RI, CT early
next week bringing light snowfall.
Weekend:
An upper level low rotates over Quebec for the weekend with a
broad trough settling across the northeast. A reinforcing shot
of colder air pushes across southern New England Friday night
into Saturday. This will result in a trend toward below normal
temperatures for the weekend with high temperatures in the upper
20s to low 30s. Cold air advection will supply steep lapse
rates to help mix down gusty NW winds aloft to the surface. Most
guidance shows gusts in the 20-35 mph range, although there are
some members showing higher gusts (35- 45mph) for the usual
windy spots (Worcester Hills, Cape).
This period will stay mainly dry with little moisture available
in the flow. Can`t rule out some ocean effect snow showers
across the Cape and Islands, mainly Sunday.
Next Week:
For early next week, models continue to show a system that moves
across the central U.S. toward the east coast. Ensemble means
track the low pressure center to the south of our region.
However, there are a chunk of ensemble members that show the
system track north enough to brush southern MA, CT, and RI with
light precipitation. This puts a low chance (< 25%) for light
snow showers in those areas. Could see a light accumulation
(< 1") in the mentioned areas if this were to track north
enough. There is some uncertainty in timing, but these chances
should fall in the Monday-Monday Night timeframe.
Upper level troughing stays put across the region next week
which will continue the pattern of high temperatures around
5-10 degrees below normal in the upper 20s to low 30s. There is
a chance for ocean effect showers across the Cape/Islands
Tues/Weds otherwise mainly dry conditions through late week.
&&
.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
Forecast Confidence Levels:
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Overall high confidence.
Generally VFR conditions areawide, however there are a few
spotty flurries/light snow showers extending from western MA
eastward to northern RI. These represent the edge of a lake
effect snow band extending from Lake Ontario. Not expecting any
reductions to visibility. Radar also showing developing
flurries/light snow showers moving into southern Vermont.
Models aren`t handling this light precipitation well, but it`s
possible that some flurries will skim across northeast MA
between 04-07z. Should miss BOS.
For the day Friday and Friday night, VFR conditions will exist
at all terminals. Otherwise gusty west winds continue to slowly
diminish, but we should still see 20-30kt gusts in many
locations overnight. Winds will drop to 20-25kt for Friday.
Friday night we will continue to see VFR conditions.
KBOS TAF...High confidence in TAF.
KBDL TAF...High confidence in TAF.
Outlook /Friday Night through Monday/
Saturday: VFR. Windy with local gusts up to 30 kt.
Saturday Night through Sunday: Mainly VFR, with local MVFR
possible. Breezy.
Sunday Night: VFR. Breezy.
Monday: VFR.
Monday Night through Tuesday: VFR. Breezy.
&&
.MARINE...
Forecaster Confidence Levels:
Low - less than 30 percent.
Medium - 30 to 60 percent.
High- greater than 60 percent.
High confidence.
Winds will be diminishing slowly overnight. Expect to have
Small Craft Advisories (SCA) issued as we pull down the Gale
Warnings, and those SCAs will likely continue well into this
weekend as model guidance shows gusty winds continuing for the
next several days. Given all the wind, wave heights will remain
elevated for quite awhile as well.
Outlook /Saturday through Tuesday/...
Saturday: Moderate risk for Small Craft Advisory winds with
gusts up to 30 kt. Seas up to 5 ft.
Saturday Night: Strong winds with gusts up to 30 kt. Areas of
rough seas. Slight chance of snow.
Sunday: Moderate risk for Small Craft Advisory winds with gusts
up to 25 kt. Areas of rough seas.
Sunday Night: Low risk for Small Craft Advisory winds with
gusts up to 25 kt. Local rough seas.
Monday: Winds less than 25 kt. Seas locally approaching 5 ft.
Slight chance of snow.
Monday Night: Low risk for Small Craft Advisory winds with
gusts up to 25 kt. Areas of seas approaching 5 ft. Slight
chance of snow.
Tuesday: Moderate risk for Small Craft Advisory winds with
gusts up to 25 kt. Areas of rough seas.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Gale Warning until 10 PM EST this evening for ANZ230-236.
Small Craft Advisory until 1 PM EST Friday for ANZ230.
Gale Warning until 3 AM EST Friday for ANZ231>235-237.
Small Craft Advisory until 1 AM EST Friday for ANZ236.
Gale Warning until 7 AM EST Friday for ANZ250-251-254>256.
&&
$$
SYNOPSIS...Mensch/Nash
NEAR TERM...Belk/Nash
SHORT TERM...Nash
LONG TERM...Mensch
AVIATION...Belk/Mensch/Nash
MARINE...Belk/Mensch/Nash
Area Forecast Discussion
National Weather Service State College PA
1042 PM EST Thu Jan 2 2025
.SYNOPSIS...
Upper level troughing will remain over Pennsylvania through the
next week. A weak wave of low pressure will dive southeastward
across the region Friday, then a stronger wave will track south
of the state Sunday night into early Monday. Both should
generate snowfall, mainly across southern Pennsylvania. The
Sunday night-Monday system will carry much more moisture,
forcing and last longer, resulting in more snowfall.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
Snow shower activity continues to wane late this evening, and
this should be the trend continuing through the early overnight
hours.
The lull will be short-lived, however, as a compact wave with
little reflection at the sfc moves into the Upper OH Valley
overnight. This system may push snow into the Laurel Highlands
by sunrise on Friday.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...
Main concern for Friday continues to be centered around the
expected snowfall and what impacts it will have on the area.
Guidance from meso models and ensembles continues to spread
precip/snowfall across the region Fri aftn, associated with the
aforementioned compact low. The morning rush hour could be
impacted in the Laurel Highlands, while the late aftn/early
evening rush hour could see impacts across the Lower Susq
Valley.
For the aftn/eve impacts, the HRRR produces a brief burst of
heavy precip (most likely snow if the intensities verify) for
locations mainly along and south of the PA Turnpike. Temps will
be marginal at first in the Lower Susq Valley, but may drop a
bit as precip begins. The interesting hours appear to be 3-7PM,
when frontogenesis increases and some meager CAPE bubbles up.
The SNSQ parameter is relatively low during this time frame,
and it may be more of a CSI-banded feature that occurs as the
strongest forcing passes overhead. Regardless, the precip
appears as a relatively thin band that could result in a
relatively short period of heavier snow. The associated drop in
temps could causes concerns for the roads to ice up as the snow
initially melts then refreezes during the heavier snow rates.
While accums may only be an inch or so, and generally sub-advy
(advy amounts are >=2" for the SErn cos), the possibility of a
quick inch and the temp drop may result in travel troubles for
the Lower Susq Valley metro areas, esp along and S of Route 30
and east of I-81. At this point, we`ll hold off on an advy due
to the lack of countywide 2"+ signals and the expected brevity
of the heaviest snow. This may be better handled by an SQW or
SPS than a broad advy, but we`ll continue to weigh these
factors as the event nears.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
Falling inversion heights will translate to dwindling snow/snow
showers by Saturday. However, a cold WNW flow will keep light
lake effect snow going over the NW Mtns. Winds will become
gusty again Friday night into Saturday, which could result in
areas of blowing/drifting over the Laurel Highlands and NW Mtns.
An extended period of upper level troughing will result in
below normal temps, with 850mb temps supportive of highs
ranging from the upper teens in the Laurels to around 30F in the
Susq Valley this weekend.
Attention then turns to a larger low pressure system moving
eastward from the Four Corners region of the Western US, set to
impact parts of the Eastern US Sunday night into Monday. Model
consensus continues to track the low across the Carolinas,
putting central PA on the cold side of the storm, but the
question will be how far north moisture will make it. It is
worth noting that most long range models keep the wave pretty
flat as it approaches the coast, and scoot it out to sea with
little or no strengthening.
Ensemble guidance is relatively tightly clustered, given this
event is still out on Day 5. Cluster analysis reveals that the
most likely scenario, represented by 75% of ensemble members,
keeps the wave between the trough approaching from Mississippi
Valley, the ridge over New England, and the deeper trough over
the Canadian Maritimes (which has origins in Friday`s clipper
system) on the flatter side, yielding less moisture advection
and lower snow totals, with accums ranging from an inch or 2
along I-80 to 3-5 inches along the southern tier.
The worst case (snowiest) scenario is shown by about 25% of
ensemble members (mostly GFS/Canadian members with very little
representation from the European ensemble system). In the
snowier solution, the wave packet is more amplified, allowing
moisture to advect farther northward and jet forcing to be
stronger. This could force the heaviest snow axis to land within
our CWA.
PoPs (all snow) were raised Sunday night into early Monday,
with snow likely winding down through the latter half of Monday.
This storm is still just beyond the range of deterministic QPF
and snow forecasts.
Behind the departing storm system Tue-Thu, lake effect and
upslope snow is expected in NWerly flow. Temperatures will run
5-10 degrees below average Mon-Wed, and may bottom out at 10-15
degrees below average for Thursday.
&&
.AVIATION /04Z FRIDAY THROUGH TUESDAY/...
Atmos forcing is being temporarily enhanced over the entire
forecast area by a weak shortwave trough. This enhancement is
competing with very dry air in most places, but, vsbys have
dipped to MVFR at AOO and JST with room for lowering with
stronger snow showers. We think this change to also be possible
at UNV and IPT over the next 3hrs (60% chc). Will add a TEMPO
mention there for the time being, not expecting it to be a long-
lasting issue.
The broader pattern is still mainly for lake effect and upslope
snows accompanied by MVFR or temporarily lower cigs. That means
poor flying conditions for BFD and JST. Not enough confidence
to dip AOO or UNV into IFR during the overnight. In fact, the
conditions will be VFR for most of the time with partial to full
clearing possible in the middle of the night. But, by morning,
clouds move in from the west due to our next weather-maker. A
clipper- type system zipping along from IA/IL into the area for
Friday. Mainly light snow over most of the area will bring
widespread MVFR to all the srn terminals, and there is a strong
(80%) possibility of LIFR snow for a very brief period at
AOO/MDT and LNS as the little system deepens rapidly as it
crosses PA. The effects of this compact system will be low in
UNV and IPT. JST and BFD will hardly miss a beat due to the
broader pattern.
Improvement occurs for UNV/AOO in mid aftn, and MDT and LNS by 7
PM. Expect then the normal IFR N/W, MVFR middle and VFR SE to
rule for the next two days.
Outlook...
Sat-Sun...Periods of -SHSN and restrictions across primarily
N/W PA. Otherwise, cold with gusty westerly winds areawide.
Mon...Widespread snow possible, especially south with impacts.
Tue...Lake effect NW, mainly MVFR elsewhere.
&&
.CLIMATE...
2024 was one of the warmest years on record for most of
Pennsylvania. Here is where 2024 ended up in terms of average
temperature at several climate sites in our forecast area:
SITE 2024 Avg Temp Rank Previous Record (Year)
Altoona 53.7F 2 54.1F (1998)
Bradford 50.2F 1 49.4F (2023)
Harrisburg (MDT) 56.7F T-1 56.7F (2021, 2023)
State College 53.0F 1 52.9F (2023)
Williamsport (IPT) 54.3F 1 54.0F (2023)
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
Lake Effect Snow Warning until 1 PM EST Sunday for PAZ004.
Winter Weather Advisory until 1 PM EST Sunday for PAZ005.
Winter Weather Advisory from 5 AM Friday to 10 AM EST Saturday
for PAZ024-033.
&&
$$
SYNOPSIS...Dangelo/Evanego
NEAR TERM...Evanego
SHORT TERM...Dangelo/Evanego
LONG TERM...Fitzgerald/Evanego/Colbert
AVIATION...Dangelo/Gartner
CLIMATE...Banghoff
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
827 PM EST Thu Jan 2 2025
.KEY MESSAGES...
- Scattered to numerous light snow showers will develop Friday. A
dusting of accumulation possible.
- Extended period of colder conditions will exist through early next
week. Minimum morning wind chill of single digits both Saturday and
Sunday.
&&
.UPDATE...
A mid level short wave feature now over the MN/WI border will slide
across srn Lower Mi Friday morning. There has been some light
snow/flurries across northern Wisconsin in advance of this wave.
Model soundings indicate a deepening of the convective depths into
the dendritic growth layer Friday morning with the passage of this
wave. Increasing moisture depth will also contribute to some Lake
Michigan enhancement. These factors, with some support of the latest
RAP and HRRR, warrant an increase in snow shower chances Friday
morning. The better larger scale ascent will remain focused south of
the state. Nonetheless, a dusting of accumulation Friday morning
looks probable.
&&
.PREV DISCUSSION...
Issued at 550 PM EST Thu Jan 2 2025
AVIATION...
Despite the majority of guidance indicating a lifting of the cloud
bases around 00Z, observational trends suggest a persistence
forecast of MVFR conditions will be more appropriate. Little overall
change in the inversion height and a persistent westerly flow off
Lake Michigan will also support this. A mid level short wave is
forecast to track across Se Mi between 12Z and 15Z Fri morning. This
wave will drive a little better moisture across the area and will
lift the inversion base considerably. This will support snow showers
and flurries. The short wave will also result in a veering of the
winds toward the northwest early Fri morning.
For DTW...A dusting of accumulation will be possible between 12Z and
16Z Friday as the short wave tracks across the region. A few brief
intervals of higher intensity snow showers can not be ruled out
during this time period.
DTW THRESHOLD PROBABILITIES...
* High in ceilings at or below 5000 feet tonight and Friday morning.
Moderate Friday afternoon and evening.
PREV DISCUSSION...
Issued at 339 PM EST Thu Jan 2 2025
DISCUSSION...
Prototypical early January conditions entrenched locally late this
afternoon. Prevailing cold low level westerly flow held within the
background of broader mid level troughing ensuring a high coverage
of stratus with intermittent flurries as the cloud layer lingers
within the dgz under modest downstream lake moisture flux. Low level
thermal trough defined by 850mb temperatures near -14C maintains a
resident thermal profile edged on the colder side of average. Little
variation in overall conditions going forward through early tonight.
Restricted convective depth both locally and upstream will maintain
meager coverage and rates to any light snow production, with no
accumulation expected. Nocturnal temperatures holding in the 20s.
A weak clipper system noted on water vapor cruising across the upper
Miss valley will then translate across the region Friday morning.
Stripe of greater forced ascent with this feature still projected to
hold just south of the area. A period of modest height falls with
renewed cold air advection will provide at least a brief window of
greater convective depth and moisture quality to generate an isolated
to scattered coverage of snow showers. No real signal to suggest
convergence will provide a more focused, higher intensity corridor of
activity, as mean low level flow veers toward the northwest within
the immediate wake of this system. This points to limited overall
accumulation potential with activity characterized by lower intensity
and limited duration - a localized dusting possible in some areas.
Initial stages of the advective process simply fortifies the below
average conditions, holding temperatures in the 20s throughout
Friday.
Weekend conditions noted by the well below average temperatures as
deep layer northwest flow takes residence within the upstream flank
of amplifying east coast troughing. This higher magnitude downturn
in temperatures defined by a minimum morning wind chill of single
digits both Saturday and Sunday, with daylight wind chill readings
topping out in the teens. Higher degree of stability persists within
the model solution space regarding the west to east track of the
pending winter storm across the Tennessee/Ohio valley region for the
latter half of the weekend, leaving southeast Michigan still just outside
of the influence of this system. Overall pattern suggests perhaps
some intervals of flurries or brief snow showers at times as long as
sufficient moisture depth remains fixated within the dendritic growth
zone, but no meaningful accumulation potential expected at this stage.
Higher amplitude longwave upper level troughing maintains control
heading into early next week. This will continue to solidify a
thermal profile of arctic origin, as intervals of renewed cold air
advection emerge with each passing lower amplitude impulse in
prevailing north to northwest flow. Coldest air of this forecast
period /850 mb temps below -20c/ likely to await the arrival of a
southward ejecting arctic lobe toward Wednesday period. A generally
drier pattern overall given northwest flow trajectory, but with some
light snow potential plausible should more focused ascent materialize
as weak clipper systems anchor within this pattern.
MARINE...
The Great Lakes is positioned between a low pressure system over New
England and an area of high pressure sliding down through the Plains
into the southeast conus. Though the low will drift northwest slowly
in time, this pattern will largely hold through the weekend.
Northwesterly flow will continually bring in colder air keeping lake
effect clouds and snow active through this stretch. In addition, the
gradient and unstable airmass will keep winds elevated at or above
25 knots through this time. There will be a period of possible gales
late Friday into Saturday as a trough swings through ushering a
pocket of even colder air across the lakes. Otherwise, a long
duration Small Craft Advisory is in effect as the nearshore waters
remain open and waves remain elevated.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...Small Craft Advisory until 10 AM EST Sunday for LHZ421-441.
Small Craft Advisory from 1 PM Friday to 4 AM EST Sunday for LHZ422.
Small Craft Advisory from 1 PM Friday to 4 PM EST Saturday for
LHZ442.
Lake St Clair...None.
Michigan waters of Lake Erie...None.
&&
$$
UPDATE.......SC
AVIATION.....SC
DISCUSSION...MR
MARINE.......DRK
You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.
Area Forecast Discussion
National Weather Service Indianapolis IN
1002 PM EST Thu Jan 2 2025
.KEY MESSAGES...
- Snow tonight, with light accumulations of up to 2 inches,
primarily over north central Indiana.
- Below normal temperatures arrive for the foreseeable future
tonight. Bitterly cold conditions likely by mid week next week.
- WINTER STORM WATCH for a winter storm expected to impact the
region Sunday - Monday, growing but still low to moderate confidence
at best on exact location details of precipitation types and totals,
particularly across southern Indiana.
&&
.FORECAST UPDATE...
Issued at 1002 PM EST Thu Jan 2 2025
Weather is evolving similar to what has been expected, so no
significant changes were made with this update.
Radar shows precipitation covering much of the northern half of
central Indiana this evening. Thanks to dry low levels, the leading
edge of the radar echoes isn`t quite reaching the ground in many
areas. However, surface obs show at least 6-7SM in light snow within
much of the remainder of the solid echoes.
Tweaked PoPs to reflect the above. Farther south, echoes are more
scattered in nature and so far have missed most observing stations.
However, feel that some of these are reaching the ground as well.
Snow has been the precipitation type across the north, with even
light snow being reported at Indy with 36 degrees. Farther south,
where temperatures are in the upper 30s (Terre Haute, Bloomington),
precipitation will likely be a mix of rain and snow. The ongoing
forecast reflected this well, so no significant changes were made to
precipitation type.
Given the recent trends seen on radar as well as snowfall reports
upstream (around 1 inch in Illinois), current snowfall forecast
looks good. Tweaked low temperatures, but no significant changes
were made.
&&
.SHORT TERM (This evening through Friday)...
Issued at 322 PM EST Thu Jan 2 2025
A quick moving clipper system will arrive this evening with snowfall
through 3AM in our NE and 5AM in our SE. Earlier observations of a
warming trend out ahead of the clipper have come to fruition, with
widespread temperatures in the upper 30s to low 40s currently over
most of central Indiana. This should lead to mostly rain initially
along and south of I-74, with a mix north of I-74 through 9PM. A
multitude of cooling (Dynamic, Evaporational and Diurnal) will act
to quickly transition any mix north of I-74 to all snow, with a
slower transition along and south of I074 where dew points are
slightly higher. This warmer antecedent airmass should lead to a
greater snowfall gradient across central Indiana, leading to some
uncertainty on snow totals along the I-74 corridor.
Current expectation is for 1-2" along and north of HWY-26, with snow
totals of 0.5-1" along the I-74 corridor. Snowfall should begin to
leave central Indiana between 4-5AM, limiting impacts to the Friday
morning commute.
Tomorrow, CAA in combination with cooling impacts of a 1-2" snow
pack over N/NE central Indiana will likely lead to well below normal
highs over this region. Currently went with values closer to the
10th percentile of the NBM to incorporate this line of thinking.
Also of note will be blustery conditions tomorrow afternoon as the
near surface becomes unstable and greater mixing occurs. The
combination of windy and cold conditions will likely lead to single
digit wind chill values over Lafayette, Kokomo and Muncie tomorrow.
Tonight -
Changeable weather is expected tonight. In the wake of the departing
high pressure system a quick moving clipper system is expected to
sweep across Indiana this evening and will exit overnight. Aloft,
this system does not appear to have much support as the models just
show a weak wave within the amplifying NW flow aloft. Within the
lower levels, a cool front boundary provides good lower level
convergence as the earlier high departs east. This frontal boundary,
as it passes, will be the triggering onset for the arrival of much
colder temperatures that will last for the foreseeable future.
Temperatures above freezing will not arrive for at least the next 7
days, likely more. But I digress, back to tonight`s system. Forecast
soundings tonight show good saturation within the mid and lower
levels by 06Z at IND, including within the DGZ. Pwats for this
system do not appear too large, with values only near 0.3-0.4. HRRR
shows areas of snow showers pushing across Central Indiana between
03Z and 09Z, in conjunction with the frontal passage. Thus will
include best pops during this time. Best forcing and moisture
appears to be mainly north of I-70, thus highest pops and higher
amounts should be found at those locations. However it does appear
that most of the forecast area will be impacted. Snow falling late
overnight and during the early morning hours may result in a
slippery roads and surfaces if untreated during the Friday morning
commute. Snow amounts should be less around 2 inches across northern
parts of Central Indiana, including Kokomo, Anderson and Muncie. One
inch amounts will be more likely along the I-70 corridor with lesser
amounts south. As always with these systems, isolated higher amounts
cannot be ruled out. With the onset of strong cold air advection in
the wake of the front, expect lows in the lower 20s.
&&
.LONG TERM (Friday night through Thursday)...
Issued at 322 PM EST Thu Jan 2 2025
OVERVIEW -
The primary concerns for the long term forecast are twofold.
1) WINTER STORM WATCH for a winter storm expected Sunday into
Monday, with potential for significant to major impacts, in
the form of heavy snow, sleet/ice accumulations, and gusty
winds/blowing and drifting.
2) Bitterly cold conditions arriving in the wake of this storm,
likely persisting well into the week 2 period before
improvement.
WINTER STORM SUNDAY INTO MONDAY -
Though the guidance suite continues to display decent agreement on
the synoptic situation for the coming winter storm Sunday into
Monday, mesoscale details remain relatively uncertain, particularly
across the southern half of the area, and especially given run-to-
run trends which have brought the warm nose aloft further north in
the past 24 hours, placing precipitation type concerns much more in
play south of the I-70 corridor.
Widespread mid and upper level saturation will likely arrive by late
Saturday night into early Sunday morning across central Indiana, but
a substantial low level dry layer will take several hours to erode
via evaporative processes as snow is generated aloft and falls into
a 5-10KFT deep dry layer.
Snow onset is likely by or a bit before daybreak Sunday in the far
southwest, with snow progressively overspreading the area - arriving
in the Indy metro area by mid morning and the Muncie area by early
to mid afternoon.
Models have trended stronger with the system and banding concerns
are high, which could produce periods of very heavy snow with rates
of 1-2 inches per hour and/or high sleet/freezing rain rates across
the south in the period when type concerns are heightened (primarily
Sunday afternoon and evening). That said, dynamic cooling may help
to counteract the advective component bringing the warm nose
northward, which could lead to a sharp gradient between all snow and
a mixed precipitation event. Based on current data and trends,
Indianapolis northward should remain all snow, with mixing concerns
south of the I-70 corridor, and especially across the far southern
forecast area.
Snow will likely continue at least into late Sunday night and Monday
morning, though it will begin to taper off as the system departs to
the east, dry advection aloft begins, and forcing quickly weakens,
but light accumulations may continue into Monday.
Given the strong forcing, plentiful moisture, and long duration of
the event due to the orientation and motion of the primary
precipitation band with the system, probabilities are moderate and
rapidly growing for warning criteria snows of 5 inches or greater,
and will issue a Winter Storm Watch for all of central Indiana
beginning Sunday morning at 12Z and continuing through Monday
evening/00Z Tuesday.
Winds will also be a concern, particularly Sunday night into Monday,
with blowing and drifting likely becoming at least a moderate
concern in that time frame, with frequent gusts in the 30-35 MPH
range and locally higher gusts.
BITTER COLD -
Guidance strongly suggests the arrival and fairly lengthy
persistence of a potent Arctic airmass in the wake of the winter
storm. Well below normal temperatures are expected from Tuesday -
Wednesday and into the week 2 period, with strong potential for
multiple nights of subzero low temperatures and wind chills well
below zero. This is, in fact, a fairly classic setup for subzero
temperatures in the area, as an antecedent snowpack is nearly a
requirement to get below zero, from a climatological standpoint. Sub-
zero minimum temperatures with zero snow depth has only occurred 6
times in the period of record that includes daily snow observation
(1884-present).
MISCELLANEOUS -
Toward the middle of next week and beyond, guidance not only
strongly suggests the aforementioned persistence of a potent Arctic
airmass, but also the passage of one or more upper level shortwave
troughs within the much larger longwave trough/upper low over the
eastern Canadian provinces and the northeastern CONUS. While
moisture is very often difficult to come by for these waves,
cyclonic flow in Arctic airmasses is notorious for producing
persistent flurries or light snow showers, and depending upon the
orientation of the flow, may allow somewhat more substantial lake
enhanced activity to make it down into portions of central Indiana
at times. While these more minor snows are far less predictable,
particularly several days or more in advance, we are likely to see
at least a few periods of light snow across some portions of central
Indiana at times toward the end of the forecast period and beyond,
despite the official forecast remaining dry for now.
SUMMARY -
Confidence is extremely high in impactful winter weather across
central Indiana Sunday into Monday, and growing though still
substantially lower in the exact details with respect to
precipitation types and amounts, especially across the south.
Residents of central Indiana should prepare for significant winter
weather impacts Sunday into Monday and monitor forecast updates in
the coming days as details become clearer.
&&
.AVIATION (00Z TAF Issuance)...
Issued at 617 PM EST Thu Jan 2 2025
Impacts:
- A period of SN expected at KLAF, mainly SN with some RA at KIND
- Areas of RASN for KHUF/KBMG
- MVFR with pockets of IFR within SN/RASN.
- Wind gusts to around 25kt Friday
Discussion:
Precipitation will occur this evening into the mid-overnight hours
before tapering off. Most coverage of precipitation will be at KLAF
and KIND, with lower coverage south.
Snow is expected at KLAF, but some uncertainty exists with type
(snow vs rain) at KIND where warmer temperatures will exist early
on. A mix of rain/snow will occur at the southern sites.
Winds will shift to the northwest overnight as a cold front moves
through. Gusty winds will occur on Friday. There could be a period
with broken MVFR ceilings Friday morning, but not confident enough
to include at this time.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
Winter Storm Watch from Sunday morning through Monday evening
for INZ021-028>031-035>049-051>057-060>065-067>072.
&&
$$
UPDATE...50
SHORT TERM...Updike
LONG TERM...Nield
AVIATION...50
Area Forecast Discussion
National Weather Service North Platte NE
533 PM CST Thu Jan 2 2025
.KEY MESSAGES...
- Fog development tonight into Friday morning across portions of
southwest Nebraska into the western Sandhills this morning.
Areas of dense fog are possible.
- Storm system crosses the central and southern plains this
weekend. While the greatest impacts are expected to remain
southeast of the area, light snow is expected across our area
Saturday into Sunday morning.
- Below normal temperatures are expected for about the next
week or so. The coldest temperatures will be across parts of
north central Nebraska where highs may struggle into the teens
Sunday through Tuesday.
&&
.SYNOPSIS...
Issued at 242 PM CST Thu Jan 2 2025
Stratus extended across much of western and north central
Nebraska this afternoon. Flurries were occurring across the
southeast panhandle and southwest Nebraska. Temperatures ranged
from 25 to around 30 most locations.
&&
.SHORT TERM /THROUGH FRIDAY NIGHT/...
Issued at 242 PM CST Thu Jan 2 2025
Tonight, surface high pressure builds in with lows from 7 to 15
above. Continued a mention of fog across portions of the southwest
into the western Sandhills where the HRRR and RAP13 show the best
potential. Could even see areas of dense fog develop including the
I80 corridor across Lincoln County.
Friday, morning fog across portions of the southwest into the
western Sandhills should lift by late morning. Much of western
Nebraska will see stratus through the day as arctic high pressure
extends from Saskatchewan Canada down through the Mid Missouri
Valley. A slight chance for light snow across the western half of
north central Nebraska. The GFS bufkit sounding shows a nearly
saturated layer from H85 through H5 and within the DGZ. Will see
isentropic upglide increase through the day across the north
central. Adjusted highs down slightly with the presence of arctic
air and stratus and light easterly winds. Coldest in the upper teens
far northeast. Mid 30s southeast panhandle and far southwest.
Friday night, chances for light snow will increase across the north
central as isentropic upglide continues and saturation increases.
The GFS, NAM and ECMWF and HRRR all indicate light QPFs. At least a
dusting of snow is probable at 50 to 90 percent near and north of of
Highway 20. A half inch of snowfall from 20 to 50 percent
probability. Lows from 7 to 15 above, coldest across the
northeast.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
Issued at 242 PM CST Thu Jan 2 2025
Saturday into Sunday an upper trough will cross the region bringing
increased chances for light to moderate snow accumulations. On
Saturday, the upper trough will move across the Intermountain West
to eastern MT and CO by late afternoon. Have 30 to 50 POPs for light
snow across all areas by afternoon. Bufkit soundings show a dry
layer from H75 to H5, though very saturated in the lowest levels.
Temperatures in the saturated lower levels is from -5C to -9C, which
supports a very fine light snow. Probabilities for a tenth of
an inch are from 50 to 90 percent, except for the eastern
panhandle, where little or no snow expected. Highs Saturday will
be colder from near 25 far western areas to near 15 in the
northeast. Will also see an increase in east-southeasterly winds
to 10 to 20 mph.
Saturday night, surface low pressure will track from the Texas
panhandle into eastern Oklahoma as the upper trough axis moves
through the Central Plains. A closed low will also develop and move
into south central Kansas by 12Z Sunday. Soundings show deep
saturation and POPS 70 to 90 percent. The main deformation zone to
the north and east of the closed upper low will develop across
central and eastern Kansas into southeast Nebraska and Missouri
overnight, where the threat or freezing rain, sleet and snow will be
greatest. Much colder air will keep the precipitation type as all
snow across western and north central Nebraska. Forecast snowfall
amounts are from 1 to 3 inches Saturday night.
Snow chances from 30-50 percent continue Sunday morning, diminishing
and ending in the afternoon as the closed upper low moves into
western MO. Storm total snowfall is from 1 to 4 inches, with the
higher 2 to 4 inch amounts possible near and east of Highway 83.
Uncertainties on the track and timing of this system continue to
result in below average confidence on snowfall amounts.
Cold temperatures will persist Saturday into Tuesday in the teens
and 20s as arctic high pressure persists across the region. Wind
chill values Monday and Tuesday morning as low 5 below to 15
below across the east. A warmup expected next Wednesday and
Thursday as upper ridging begins to build in and 30s return to
the west.
&&
.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 517 PM CST Thu Jan 2 2025
IFR CIGs persist across northwest into north central Nebraska
(VTN, GRN, ONL, BBW) this evening. The stratus will expand
southward through tonight with widespread IFR CIGs and LIFR
CIGs over north central. Fog development is likely, extending
from northwest Nebraska into southwest Nebraska (impacting LBF)
with vsbys falling down to 2SM or less around 06Z through 15Z
Friday. CIGs will improve some Friday afternoon with low-end VFR
on the fringe of the stratus deck and MVFR conditions
persisting for LBF and VTN through the remainder of the period.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Roberg
SHORT TERM...Roberg
LONG TERM...Roberg
AVIATION...Viken
Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
901 PM EST Thu Jan 2 2025
.SYNOPSIS...
High pressure builds in today before another clipper system
brings additional snow chances and colder temperatures to the
area Friday. Mountain snow showers, gusty winds, and even colder
temperatures are expected Saturday as brief high pressure
builds over the area. A more potent low pressure system looks to
bring the threat of more widespread wintry weather Sunday into
early next week.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
EVENING UPDATE...
The stratocu deck from earlier continues to linger this evening,
and has even expanded slightly east over the last few hours.
Most guidance has struggled to capture the very thin cloud
layer, but hi-res guidance such as the HRRR at least suggest it
could persist for a few more hours. Clouds increase regardless
late tonight into tomorrow morning ahead of the next system.
The Gale Watch has been upgraded to a Gale Warning for our
southern waters Friday night into Saturday morning. Otherwise,
forecast is on track.
PREVIOUS DISCUSSION FOLLOWS...
Winds will gradually decrease into this evening as high
pressure builds towards the region. Clouds have been pretty
widespread for much of the day, owing to a stubborn
stratocumulus deck. However, cloud cover will further increase
this evening and tonight ahead of an approaching clipper low
moving towards the region from the Ohio Valley.
Lows tonight will fall back into the lower to middle 20s west
of the Blue Ridge with middle to upper 20s further east.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/...
A very impactful mountain snowstorm is taking shape Friday with
the arrival of a powerful clipper low with an abundance of
moisture transport off the Great Lakes. Snow begins early in the
morning and will likely continue through Saturday morning. The
heaviest snow looks to fall during the late morning hours
through Friday afternoon, where some snow squalls will likely
bump totals up in isolated spots. Snow squall parameters nearly
max out the scale moving into the Allegheny Front during this
timeframe. Temperatures will be well into the 20s by this point,
so expecting some very low SLRs paired with the enhanced QPF
from the squalls. For the climo-favored areas, Winter Storm
Warnings were issued for anywhere from 6 to 10 inches of
snowfall. Winter Weather Advisories were issued generally along
the periphery of that for lesser amounts of 2 to 4 inches.
Winds could also have an impact Friday afternoon and evening
along the higher ridges. Near-blizzard conditions are expected
at times with the heaviest snow squalls.
Snow chances will then spread east toward the Blue Ridge and
metros Friday afternoon/evening as the trough axis pivots east.
Some light accumulations are possible generally along and north
of I-66/US-50 during the afternoon/evening hours. However,
highest confidence in potential heavier snow showers that could
accumulate in the 1 to 2 inch range is up along the MD/PA
border. Winter Weather Advisories were issued for that area as
well, primarily driven by the timing being during the evening
commute. Ground temperatures will generally be too warm for
accumulation, but where rates are higher that could be overcome.
Snow showers will quickly diminish east of the mountains
Friday evening. Upslope flow will continue over the Alleghenies
through early Saturday morning before diminishing as high
pressure briefly builds back into the region. Lows will fall
into the teens and 20s.
Winds could potentially push Wind Advisory criteria over the
higher ridges Saturday as the clipper departs the region. Will
continue to monitor this situation as it gets closer especially
with antecedent cold air leading up to the event. Highs in the
teens over the mountains on Saturday paired with those winds
could lead to Cold Weather headlines as well. Elsewhere, highs
are expected in the upper 20s to low 30s on Saturday.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
The biggest area of focus of the the long term will be an area of
low pressure tracking from the Mississippi River Valley towards New
England, bringing wintry weather to the region Sunday evening
through Monday. There remains a good bit of model discrepancy
regarding the track and timing of the low pressure system, therefore
leading to uncertainty when it comes to a snowfall amount and
precipitation type forecast. While temperatures at the surface are
expected to stay near or below freezing, model soundings indicate a
prolonged warm nose leading to precipitation type transitioning from
snow to sleet/freezing rain. This will lead to lower snow totals
than some models are currently indicating. 12Z model guidance is
showing a light shift north for the low pressure system, with
accumulation amounts continuing to show a good bit of discrepancy.
precipitation onset will likely be Sunday afternoon through Sunday
night with precipitation moving out of the area early Tuesday
morning.
Upslope snow showers continue for the Alleghenies through the end of
the long term period, with dry conditions expected elsewhere.
Temperatures will be cold each day with highs in the 20s to low 30s
(teens in the Alleghenies). Overnight low temperatures will be in
the teens to 20s with those at higher elevations dipping into single
digits.
&&
.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
Breezy WNW winds continue through the early/mid afternoon today,
but will taper off later this afternoon into this evening. VFR
conditions are expected during this time. A stubborn stratocu
deck remains over the region, but will be scattered to broken,
and CIGs will generally be in the 5-6 kft range.
Sub-VFR conditions return to the area Friday as another clipper
system takes aim at the region. Snow chances will increase
across the Alleghenies Friday morning before spreading eastward
toward the I-95 corridor Friday afternoon and evening. Highest
confidence for snow impacts looks to remain west of KMRB
although some impacts are possible over the corridor Friday
afternoon and evening with any snow showers that pass through.
Did introduce snow or rain/snow mix at all terminals aside from
CHO with the afternoon update. Not to say it will necessarily
stick everywhere, but some spots may see a brief burst of
heavier snow which could lead to a quick slushy accumulation.
Snow shower activity will quickly diminish over terminals east
of the mountains Friday night with snow showers lingering over
the mountains through Saturday morning. VFR conditions and gusty
northwesterly winds are expected on Saturday. Gusts may reach
around 30 knots at times.
An area of low pressure brings wintry precipitation to all terminals
beginning Sunday night and through Monday. Mixed precipitation types
are possible across the area, with the greatest chances at KCHO.
Flight restrictions are likely. Westerly winds on Sunday shift to
northerly on Monday.
&&
.MARINE...
Winds remain gusty through this evening before quickly tapering off
tonight from west to east across the waters. Small Craft Advisories
are being allowed to expire tonight with lighter winds expected.
Winds pick up out of the SW on Friday, which have necessitated the
issuance of another SCA, starting Friday afternoon. Winds then shift
out of the WNW Friday night into Saturday, increasing in intensity.
A Gale Watch has been issued for the lower Chesapeake Bay zones and
the lower tidal Potomac. SCAs continue elsewhere through at least
Saturday night.
Winds are expected to stay below SCA criteria on Sunday. As an area
of low pressure impacts the waters on Monday, northwesterly winds
increase to SCA criteria.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...Small Craft Advisory until 1 AM EST Friday for MDZ008.
Small Craft Advisory from 1 PM Friday to 6 AM EST Saturday for
MDZ008.
Winter Weather Advisory from 1 PM to 7 PM EST Friday for
MDZ004>006-008-011-505>508.
Winter Storm Warning from 6 AM Friday to 10 AM EST Saturday
for MDZ001.
Winter Weather Advisory from 6 AM Friday to midnight EST
Friday night for MDZ501.
VA...Winter Weather Advisory from 6 AM Friday to midnight EST
Friday night for VAZ503.
WV...Winter Storm Warning from 6 AM Friday to 10 AM EST Saturday
for WVZ501-505.
Winter Weather Advisory from 6 AM Friday to midnight EST
Friday night for WVZ503.
MARINE...Small Craft Advisory until 1 AM EST Friday for ANZ530>534-
539>541-543.
Small Craft Advisory from 1 PM Friday to 6 AM EST Saturday for
ANZ530>532-535-536-538>540.
Winter Weather Advisory from 1 PM to 7 PM EST Friday for
ANZ530.
Small Craft Advisory from 1 PM to 6 PM EST Friday for ANZ533-
534-537-541>543.
Gale Warning from 6 PM Friday to 6 AM EST Saturday for ANZ533-
534-537-541>543.
&&
$$
SYNOPSIS...EST
NEAR TERM...CJL/CAS
SHORT TERM...CJL/ADM
LONG TERM...AVS/CJL
AVIATION...AVS/CJL/ADM
MARINE...AVS/CJL
Area Forecast Discussion
National Weather Service Raleigh NC
939 PM EST Thu Jan 2 2025
.SYNOPSIS...
High pressure will extend into the region through early Friday. An
Arctic cold front will move through the area Friday evening,
ushering in much colder air for the weekend. A storm system is
expected to move across the region late Sunday into Monday.
&&
.NEAR TERM /THROUGH FRIDAY/...
As of 935 PM Thursday...
Tonight: Widespread mid/high clouds over the TN/OH Valley will spill
east of the mountains and overspread all of central NC through
tonight. Surface observations from 02z show the center of 1026mb
surface high pressure centered over eastern TN with a weak pressure
gradient edging into southern Piedmont, Sandhills, and
central/southern Coastal Plain. Combined with a steepening surface
inversion and initially mostly clear skies, temperatures have
already dropped into the low/mid 30s with isolated spots across the
Piedmont already in the upper 20s. Although cloud cover will
increase, mostly high clouds through 10z should promote continued
radiational cooling through roughly 10z when cloud cover should
thicken/lower to below 10k feet and contribute to downward IR
warming at the surface. Lows will bottom out in the mid 20s in most
locations with upper 20s to around 30 in urban areas.
As a surface low moves from Ohio off the New Jersey coast by Friday
night, the associated cold front will move across North Carolina in
the afternoon. There will be minimal deep moisture across the area
for the front to work with, and only have a small area with a chance
for precipitation north and east of Raleigh. Most of the area should
be little more than scattered sprinkles, but do think there`s a
slight area that could manage 1 or 2 hundredths of an inch of rain.
Highs will be a touch warmer than today, with highs ranging from the
upper 40s to the mid 50s. Think that temperatures should still
follow a diurnal curve tomorrow despite the front moving through
during the day; the fall in temperatures should not occur until
Friday night. However, wind gusts will pick up, ranging from 20 mph
in the east to 30 mph in the west during the afternoon.
&&
.SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY/...
As of 140 PM Thursday...
Troughing and northwest flow Fri evening will persist into most of
Sat, after which ridging will build into the TN valley by early Sun
morning. At the surface, a strong cold front will move through Fri
night as a surface low to our north tracks offshore Sat morning.
Arctic high pressure over the Upper MS Valley will extend into the
area Sat, after which high pressure over the TN valley slides east
Sat night.
With the frontal passage Fri night, some isolated or spotty showers
are possible over our northeast Piedmont and northern Coastal Plain.
Forecast soundings show fairly steep low-level lapse rates and some
weak instability for this. The HRRR also shows this scattered
activity - would not be surprised if some isolated graupel occurs
with the instability in the -12 to -18 degC temp range. Any activity
should shift east by 8-9 pm. It will turn colder behind the front
with lows in the low to middle 20s. Combined with expected NW winds
gusting at times to 25-30 mph and some infrequent gusts to 35 mph,
will make for some cold wind chills in the lower to middle teens
across the north and upper teens in the south.
On Sat, it is all about the cold, with highs some 8-12 degrees below
normal in the upper 30s north and west to low 40s in the south and
east. Gusts out of the NW will be in the 15 to 25 mph range,
decreasing in the afternoon. With high pressure settling in Sat
night, winds should become light, although may not completely turn
calm. Nevertheless, good radiational cooling will make for cold
overnight lows in the upper teens to lower 20s.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
As of 430 PM Thursday...
A mid/upper low will move east from the Southern Plains on Sunday
morning into the Southern Appalachians on Monday, then off the Mid-
Atlantic coast on Monday night as it opens up into a wave. At the
surface, an associated surface low will move into the TN Valley on
Sunday night, with a secondary low developing over the southern Mid-
Atlantic on Monday, moving offshore on Monday night. Strong 1040-
1045 mb high pressure will remain anchored over southern Manitoba
and ND. A band of isentropic lift induced precipitation looks to
push NE through central NC from late Sunday afternoon into Sunday
night. While surface temperatures will initially be in the 40s,
ample dry air will be in place with dew points in the teens, so
temperatures will initially cool into the 30s. It remains uncertain
where exactly the wet bulb zero line will be, with the latest hours
of the 18z NAM run indicating upper-20s over the far northern
Piedmont, the GFS keeping the freezing line confined to near the
NC/VA border, and the ECMWF somewhere in between. The GFS has
trended warmer and farther north with the surface low in recent
runs, and its soundings largely indicate rain for the area. But with
other guidance cooler, the forecast has a slight chance to chance of
freezing rain across a good portion of the northern Piedmont and
northern Coastal Plain on Sunday evening/night. Southerly winds
ahead of the low and a lack of high pressure to the north, combined
with freezing rain being a self-limiting process, mean the window
for freezing rain should be fairly brief, with temperatures rising
above freezing everywhere by late Sunday night and early Monday
morning. At this time soundings appear too warm aloft for snow, and
this Miller B type setup is usually unfavorable for it, so only have
rain or freezing rain in the wx grids at this time. Impacts look to
be pretty minor with very light ice accumulations over the far north
if any. But models have been inconsistent and it only takes a slight
shift in track to make a big difference in impacts, so stay tuned
for future updates.
A warm front will push north through central NC on Monday morning,
before the secondary low tracks through the area in the early
afternoon and a cold front pushes through in the late afternoon and
early evening. This will bring a heavier more widespread area of
precipitation Monday morning and afternoon, ending from SW to NE in
the late afternoon and early evening. Temperatures will be warm
enough by this point for all liquid, and total amounts of around a
quarter to half an inch are expected (highest north). SW winds may
also gust from 20-30 mph at times. Monday`s forecast highs range
from mid-40s far north to upper-50s far south. Skies will clear
Monday night and it will stay breezy with NW winds behind the cold
front bringing down lows into the 20s.
Much drier weather is expected from Tuesday through Thursday, but it
will be quite chilly as the Canadian surface high builds down into
the Plains and Midwest. Highs on Tuesday and Wednesday will only be
in the upper-30s to lower-40s, with lows in the upper-teens to lower-
20s. Another shot of cold air on Wednesday night will bring even
colder weather on Thursday with highs in the mid-30s to 40, and dew
points possibly in the single digits.
&&
.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
As of 720 PM Thursday...
Dry, surface high pressure will maintain VFR conditions in cntl NC
as it builds across and offshore the Southeast. However, mid-level
ceilings will overspread cntl NC Fri morning ahead of a couple of
vigorous mid/upper-level troughs and an accompanying, Arctic surface
cold front that will sweep across the region Fri afternoon-evening.
Swly/Wswly surface winds will strengthen and become gusty through
the 20s to around 30 kts ahead of the front Fri afternoon. A period
of even stronger wind gusts up to 30-40 kts will probably result
from west to east between 20Z Fri-05Z Sat, both beneath virga/widely
scattered sprinkles that will accompany the Arctic front and in the
several hours immediately following its passage, when the brunt of
the Arctic air surges across the region.
Outlook: A quick-moving frontal system will result in a high
probability of flight restrictions and precipitation Sunday night-
early Mon, including some wintry precipitation at Piedmont sites and
RWI early Sunday night.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Kren/Badgett
NEAR TERM...Swiggett/Green
SHORT TERM...Kren
LONG TERM...Danco
AVIATION...MWS