Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/30/17
Area Forecast Discussion
National Weather Service Denver/Boulder CO
826 PM MST Fri Dec 29 2017
.UPDATE...
Issued at 806 PM MST Fri Dec 29 2017
Surface cold front has sludged through much of northeast Colorado
this evening with a brisk east to northeast winds over the area.
With the shallow upslope in place, GOES16 night imagery showing
stratus deck rapidly developing from Denver northward to the
Wyoming border. Expect the low clouds to envelope much of the
plains. High resolution models are not doing well with this low
cloud development except the NAMNest which seems to have the most
accurate depiction as it evolves this evening. Will be making
some adjustments in cloud cover and fog development based on
evening trends. Even more complicated is how much clearing and
scouring out of the cloud deck happens later tonight and Saturday
morning. Models are quite varied on this but for now going to
lean on the later morning clearing based on latest HRRR as areas
Denver northward not going to see much downslope flow developing
until later morning.
Still expect strong and gusty west winds but mainly confined to
mountain passes and higher exposed east slopes. Winds this evening
have been in the 30-45 mph range and this should hold through much
of the night and then some increase Saturday morning. Not
expecting high winds as lack of stability and increasing shear
will not allow deep wave amplification.
&&
.SHORT TERM...(This evening through Saturday)
Issued at 300 PM MST Fri Dec 29 2017
Most wind in the higher terrain have slowed in speeds, with the
exception of Berthoud Pass and areas around Georgetown where gusts
of 65 to 80 mph still occur. With the exception of Berthoud Pass
weather station at almost 12500 feet, expect all other areas to be
below warning criteria within the next hour, so an expiration of
3pm will be fine. Winds will remain elevated along the east slopes
of the Front Range mountains and foothills through the night, with
gusts of 30 to 50 mph still possible. This will keep temperatures
moderated in these areas, with minimums likely to the 25 to 35
degree range.
An arctic airmass is pushing southwest over the northeastern
plains currently, with temperatures falling quickly into the teens
to 20s. Areas of stratus and fog will follow later this evening.
At this time, the arctic push is expected to push through the
northern urban corridor down to around Broomfield then out to
Denver International Airport arcing around into Lincoln County
initially. Then a surface trough will build in and the airmass
will likely retreat slightly east. There is a very slight chance
to see some light freezing drizzle or flurries over the far
northeastern corner according to forecast soundings, but the lower
levels aren`t as wet as Id want, so did not add this to the
forecast at this time. Minimum temperatures in this arctic airmass
will be in the teens to single digits, and even below zero over
the far northeast corner.
Tomorrow, flow aloft turns slightly more westerly to bring warmer
temperatures at 700 mb. However, with the cold airmass over the
most of plains, temperatures will likely be similar or maybe a few
degrees cooler than today`s readings along the southern urban
corridor where the arctic airmass will either have very little lag
time to none. Further north and east, temperatures will be much
colder as the airmass will be slow to scour out, if at all. Late
in the afternoon, a jet max will approach to bring a slight chance
of snow to the far northern mountains.
.LONG TERM...(Saturday night through Friday)
Issued at 300 PM MST Fri Dec 29 2017
Northwest flow continues over the state with an upper ridge in
place over the western coast. By Saturday night the shallow stratus
deck will be in place over the plains. Persistent cold
temperatures and cloud cover will continue through Sunday.
Mountains will see light snow through the afternoon on Sunday with
just a few inches in accumulation possible. For the plains upper
air soundings show a mostly dry profile but with enough ice
nucleation to bring light snow by Sunday afternoon with flurries
possible into Sunday night. A drier airmass will move in for the
mid to upper levels with the column will remain cold enough for
the formation of flurries on the plains into Monday morning.
Temperatures on Sunday will stay below normal with highs in the
20s. For Sunday night into Monday temperatures will dip into the
single digits and well below zero on the eastern plains. These
temperatures combined with winds from 5 to 10 mph will create wind
chill readings of -22 to -28 degrees. These conditions could
cause frostbite for individuals that are outside and uncovered in
less than 10 minutes.
Clouds and cool temperatures will persist through the day Monday
with some light flurries possible over the plains. Highs will stay
in the 20s with overnight lows continuing to be in the low single
digits. Tuesday will see a slight pattern shift as the upper ridge
moves further into the Great Basin and a trough drops out of the
north. This dry feature will not produce much precipitation and
will seeing greatly increasing subsidence behind it helping to
increase temperatures back to normal. NW flow will return on
Wednesday with weak moisture in the Northern mountains helping to
bring a slight chance of snow to the higher elevations Wednesday
into Thursday. A cold front on Thursday could help to increase
chances of snow over the urban corridor but will have to see how
models resolve these features.
&&
.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 806 PM MST Fri Dec 29 2017
With early evening frontal passage winds have shifted northeast at
KDEN and more north and northeast at BJC/APA. Stratus deck has
been rapidly developing and just into KDEN and will soon be in
BJC and APA. Confidence is on the lower side on fog
development(how dense?) and stratus dissipation Saturday morning.
For now will lean on the later clearing at DEN with lack of
downslope component until Saturday afternoon. Will have some
temporary conditions of 1/4 FZFG at Denver but overall confidence
is low to medium.
&&
.FIRE WEATHER...
Issued at 300 PM MST Fri Dec 29 2017
In terms of weather conditions, there is concern tomorrow for
South Park, the southern foothills and onto the Palmer Divide,
zones 214, 216 and 241. Humidity will be in the low teens with
gusty west winds of 25 to 40 mph. However, in terms of fuels
conditions, South Park looks to have good enough snow cover via
webcams. As for southern foothills and Palmer Divide and looking
at fire indices, only one RAWS station is at a Very High rating,
where the rest are at Moderate and Low ratings. Therefore, decided
not to issue a Red Flag Warning for those zones.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...Entrekin
SHORT TERM...Kriederman
LONG TERM...Bowen
AVIATION...Entrekin
FIRE WEATHER...Kriederman
Area Forecast Discussion
National Weather Service Burlington VT
917 PM EST Fri Dec 29 2017
.SYNOPSIS...
Below normal temperatures will continue through this weekend
and into much of next week. Winds will not be as strong as the
past couple of days and as a result wind chills will not be a
concern. However, there will be two periods of gusty northwest
winds and very cold temperatures, this Sunday and Monday and
again for the middle part of next week, that will result in wind
chill issues.
&&
.NEAR TERM /THROUGH SATURDAY NIGHT/...
As of 908 PM EST Friday...1027mb sfc high pres over SLV/Western
Dacks has resulted in clear skies and light winds...with
temperatures quickly reaching expected low temps already. Have
updated to adjust temps down by 2 to 4 degrees...along with
parts of central/southern VT...where Rutland is already at -9F.
Meanwhile...both Ogdensburg and Edwards are near -20f with slk
at -10f. Expect as clouds increase after 04z...temps will level
off and slowly rise after midnight across slv/western dacks. Difficult
to adjust some areas which are experiencing rapidly falling
temps...while clouds/winds prevail over northern VT and parts of
the eastern cpv near BTV holding temps btwn 0f and
-5f. Bottom line most locations between -10f and
-20f with some slightly lower and higher values possible. Very
light snow/flurries continue near BTV and MPV...from lake effect
moisture/instability...but latest RAP 13 and BTV 4km soundings
show low level moisture decreasing btwn 04z-06z tonight. Have
continued to mention chc pops for light snow thru 04z...then
tapered off. Only a dusting of new snow is expected.
Previous discussion below:
Light snow will be ending this evening as upper level shortwave
pushes East of the north country. Skies will gradually clear.
Overnight lows will range from the negative single digits to
negative twenties. Clouds will increase across the region on
Saturday with another upper low crossing our Northern zones.
Better shortwave energy will stay south of our forecast area,
but do have a chance of light snow mentioned in the forecast.
Maximum temperatures Saturday will range from the single digits
to teens above zero. Clouds remain in place Saturday night
though light snow should be ending. Overnight min temps will
range from the single digits below zero in the Champlain valley
to teens below zero. MPV has a shot at breaking min temp records
tonight and tomorrow night, and MSS may reach the min temp
record tomorrow night.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY/...
As of 321 PM EST Friday...Northwesterly flow will commence once
again Saturday night into Sunday, bringing yet another shot of
cold air into the North Country to end 2017. As the upper-level
shortwave departs to the east, expect some peaks of sunshine
Sunday. The sun will be deceiving however, as daytime high
temperatures will cap in the low single digits in valley
locations and remain below zero elsewhere. In addition to the
increasingly colder air, expect some higher momentum
northwesterly winds to mix down to the surface Sunday through
Monday. This will create some wind chill concerns as even fairly
light winds in temperatures this cold can create bitter wind
chills. Decreasing cloud cover will allow temperatures to drop
down to the negative teens Sunday night (New Years Eve). Those
with outdoors New Years Eve/New Years Day plans should be
prepared for bitter cold and plan in advance to wear many layers
and take precautions against frostbite. Monday (New Years Day)
will bring similar temperatures to Sunday, if not a few degrees
colder.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
As of 321 PM EST Friday...Tuesday and Wednesday will feature
a brief respite from the widespread below zero temperatures,
although temperatures will still be around ten degrees below
seasonal norms. The better chances for some snow return
Thursday, followed by another surge of arctic air that will
bring a return of the bitterly cold temperatures by the end of
next week.
Details...A fairly potent shortwave over western Canada will
dive down to the Mississippi River Valley Wednesday, amplifying
and sharpening the broader longwave trough over the eastern US.
Ahead of the wave, a weak southwesterly low-level jet will
transport some warmer air northward to New England. This will
allow for a slight warming trend Tuesday and Wednesday with
daytime high temperatures climbing a few degrees each day. By
Wednesday, high temperatures will be in the teens above zero,
which will feel quite warm compared to the recent frigid spell.
Some light snow showers are possible Tuesday and Wednesday as
weak disturbances rotate through the flow, however moisture is
very limited and any accumulations will be minimal.
By Wednesday evening, the forecast becomes more complex and
uncertain. The sharpened trough will take on a slight negative
tilt as it moves over the Eastern Seaboard. At the same time,
southern stream energy will rotate northeastward out of Florida.
There is some potential for the two systems to phase and spin
up a coastal low Thursday, however recent model runs are
trending away from this solution. Current thinking is that the
southern shortwave will generate a surface low pressure system,
however the low will stay too far east in the Atlantic to be of
much impact to the North Country. If the coastal low does
indeed miss us completely, we will still see some chances for
precipitation Thursday as a weak clipper moves through from the
west.
Once the trough axis moves off the coast Thursday night, we`ll
see yet another push of cold air into New England and
temperatures will return to 20 to 30 degrees below normal by
Friday.
&&
.AVIATION /02Z SATURDAY THROUGH WEDNESDAY/...
Through 00Z Sunday...VFR conditions with local MVFR at BTV and
RUT will prevail through much of the overnight hours. Light snow
and ceilings around 2500 ft will persist at BTV and RUT through
approximately 05z, then expect all sites will be VFR through 15Z
Saturday. Another round of light snow will bring the threat of
MVFR conditions, particularly to SLK and RUT, from 16z Saturday
on. Winds will be light and variable much of the period.
Outlook...
Saturday Night: Mainly VFR, with local MVFR possible. Chance
SHSN.
Sunday: VFR. NO SIG WX.
Sunday Night: VFR. NO SIG WX.
New Years Day: VFR. NO SIG WX.
Monday Night: Mainly VFR, with local IFR possible. NO SIG WX.
Tuesday: Mainly MVFR, with local IFR possible. Chance SHSN.
Tuesday Night: Mainly MVFR, with local VFR possible. Chance SHSN.
Wednesday: Mainly VFR, with areas MVFR possible. Chance SHSN.
&&
.EQUIPMENT...
The KTYX (Montague NY) radar will be out of service into the
weekend and possibly early next week as a motor and power
supply have failed. Parts are on order and are scheduled to
arrive tomorrow.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...None.
NY...None.
&&
$$
SYNOPSIS...Evenson
NEAR TERM...Neiles/Taber
SHORT TERM...RSD
LONG TERM...RSD
AVIATION...Hastings
EQUIPMENT...WFO BTV
Area Forecast Discussion
National Weather Service State College PA
1014 PM EST Fri Dec 29 2017
.SYNOPSIS...
Multiple arctic intrusions will ensure well below normal
temperatures continue into the first week of 2018. A quick-
hitting, fluffy snowfall is expected tonight into Saturday,
followed by occasional intrusions of lake effect snow.
&&
.NEAR TERM /THROUGH SATURDAY/...
The anemic clipper is working its way across eastern Ohio and
western Pennsylvania. Best IR enhancements are in Ohio and West
Virginia at 0300 UTC. Some of the coldest tops since the wave
was in IL/IN.
The HRRR and RAP continue to produce about 0.10 inches of QPF
across most of the southern 2/3 of our forecast area. Some spots
in 0.20 in the southwest mountains and a few location mainly in
south-central areas. This event will probably support 16 to 20
to ratios. So light fluffy snow spreading west to east
overnight. Most locations should see 1 to 2 inches of fluff by
about midday.
RAP/HRRR would imply snow around midnight in Somerset county
reaching the Harrisburg/York areas in the 6 AM range.
With the clipper the higher QPF is in the southwest mountains in
the 0.2 to 0.3 range. Most other areas are in the general 0.1
range. So advisories with clipper are for 3-5 or so in the
southwest mountains and around 2 inches or so in the southern
tier counties. Similar snow expected in central areas but
advisory requires 3 inches of snow.
In the northwest a longer lasting LES event will bring snow
over a longer period of time.
Roads in the southeast probably will be snow covered by 7-8 AM
for Saturday commute which is pretty low and shoppers.
Snow tapers off outside LES and upslope areas pretty fast.
One hour snow in the HRRR and RAP is pretty much over outside of
Lancaster County and the Laurels. And of course there is LES
issues in Warren county.
&&
.SHORT TERM /SATURDAY NIGHT/...
LES continues in NW PA. Cold/arctic air poised to move in and
overnight lows below 0F likely along our northern tier. Mainly
single digits central areas. Possible some isolated 0F reading
with the fresh snow SW mountains.
Southeastern areas too will get in on the cold act with lows
mainly in the lower teens. Rural areas that catch 2 inches of
snow could dip below 10F!
There may be a windchill advisory issue by Sunday morning and on
into Sunday. But not at this time as we have a WSW up so it can
wait.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
As the ridge build over the western United states an amplified
trough will continue to deepen. this elongated trough will
extend westward. this will maintain the unseasonable cold
temperatures which at times will be subzero, with dangerously
low wind chill values during periods of strong persistent wind
gradient over the region.
Persistent lake effect and orographic snow showers are expected
to continue next week. The ensemble mean and deterministic
models are in fair agreement on the position of a low over
Hudson Ba and a deepening trough bring another weather system
through the region mid to late week. The best moisture remains
off shore but a clipper type system could bring another period
of snow showers through the later half of next week.
High temperature departures on Sunday will range from 20 to 30
degrees below normal. Lows Sunday night will be in the negative
and positive single digits with -5F to -20F wind chills into
Monday morning.
&&
.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
For 00Z TAF package, some minor changes, but mainly just
more groups added after 18Z Saturday.
System to the west of PA will quickly bring light snow
to the area late tonight into Saturday afternoon. VFR conditions
will give way to MVFR and IFR conditions later tonight. As the
system pulls east of the area Saturday afternoon, winds will
shift to the west and become gusty. While eastern areas will
clear out across the east later Saturday afternoon, cold air
aloft and winds aloft from the northwest, will result in some
snow showers across the mountains, mainly at BFD and JST. Sites
like AOO and UNV may see some, but most likely after 00Z Sunday,
as wind shift line aloft shifts eastward.
Outlook...
Sun...Scattered snow showers and areas of reduced cigs and
vsbys, mainly across the northern and western mountains of PA.
Mon-Tue...VFR most of the area, but chance of snow showers
across the northwest.
Wed...No sig wx.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 6 PM EST Saturday for PAZ004-005.
Winter Weather Advisory from 3 AM to 1 PM EST Saturday for
PAZ010-017-024-033>036-056-057-059-063>066.
&&
$$
SYNOPSIS...RXR
NEAR TERM...Grumm
SHORT TERM...Grumm
LONG TERM...Ceru/Steinbugl
AVIATION...Martin
Area Forecast Discussion
National Weather Service Grand Forks ND
923 PM CST Fri Dec 29 2017
.UPDATE...
Issued at 921 PM CST Fri Dec 29 2017
Minor adjustments made to ambient and apparent temperatures...wind
chill warning criteria being met across portions of northeastern
North Dakota and will increase in coverage over next several
hours. Reduced sky cover across the region. Re-issued WSW to
remove advisory wording from earlier in the day.
UPDATE Issued at 640 PM CST Fri Dec 29 2017
Solid wind chill advisory criteria across the CWA as temperatures
begin to plummet toward wind chill warning criteria, which should
be met for most of the area by late evening. Already seeing
temperatures across the north in the 15 to 20 below range...with
12 mph winds. Have made minor adjustments to next three hours of
temps with no change to MinT grid...as well as updating winds
with latest RAP guidance and re-calculating Apparent Ts. Light
snow over FAR at beginning of shift is to the south now and should
end within the next hour.
&&
.SHORT TERM...(This evening through Saturday)
Issued at 309 PM CST Fri Dec 29 2017
Main concern in the short term is dangerous wind chill values
developing overnight and into Saturday, persisting through the
weekend. Wind Chill Warning is in effect for tonight through Monday
morning. While this is not an unusual airmass for the Northern
Plains, this stretch and magnitude of extreme cold is more typical
of the mid January to February timeframe and has not occurred for
the past few years. Aided by persistent northwest flow aloft, a dry,
frigid Arctic airmass and strong high pressure build into the
Dakotas and Montana tonight. This airmass remains entrenched in the
area through the weekend. Saturday looks to be the coldest day of
the stretch, as a strong jet streak digs the upper level trough over
the Great Lakes. Despite increased sunshine on Saturday, diurnal
heating is weak this time of year and the atmospheric pattern will
very much inhibit warming, allowing for highs to only reach the
teens below zero.
.LONG TERM...(Saturday night through Friday)
Issued at 309 PM CST Fri Dec 29 2017
Upper level northwesterly flow is expected to continue through the
extended forecast period. With a strong blocking high pressure ridge
over the western CONUS, only weak shortwave troughs are likely to
impact the region. These will bring quick surges of colder, arctic
air and light precipitation chances. Model guidance agrees on the
overall pattern, but differences in timing and surface low track
brings low confidence to any precipitation chances over the extended
outlook.
Surface ridging is expected over the Dakotas and Montana Saturday
night into Sunday. This will push colder arctic air southward into
the region. Morning lows in the -25 to -30 range are expected for
Sunday morning with dangerous wind chill values from
-40 to -50. Sunday afternoon highs from -10 to -15 are likely,
dropping to overnight lows near the -20 mark. Dangerous wind chills
will continue through Monday morning until temperatures begin to
climb near the zero mark across the region.
A gradual warming trend is expected mid week as winds turn more
southwesterly and advect in warmer air. An upper level shortwave on
Tuesday will bring a cold front through the region, dropping
temperatures back down below zero and bringing light snow chances to
northwest Minnesota.
After a cooler Wednesday, temperatures will likely rebound again for
Thursday into the single digits as winds turn more southerly ahead
of another clipper low dropping out of Canada. This shortwave will
bring light snow chances to the region, though model guidance
disagreement gives low confidence in the placement and timing of any
precipitation. Regardless, overall impacts are expected to be low at
this time with the more impactful weather coming over the New Year`s
weekend with the dangerously cold temperatures.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 640 PM CST Fri Dec 29 2017
VFR. Extreme cold will have impacts on starting small aircraft
throughout the weekend, pre-heating engines will be necessary.
Removing aircraft from heated hangars will result in some
immediate light frost developing on skin. General aviators should
treat wind chill warning this weekend the same as if traveling by
ground transportation, with appropriate emergency gear available
in case of an emergency.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...Wind Chill Warning until 9 AM CST Monday for NDZ006>008-014>016-
024-026>030-038-039-049-052>054.
MN...Wind Chill Warning until 9 AM CST Monday for MNZ001>009-013>017-
022>024-027>032-040.
&&
$$
UPDATE...Speicher
SHORT TERM...BP
LONG TERM...AM
AVIATION...Speicher
AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
1010 PM EST Fri Dec 29 2017
.UPDATE...
Issued at 1010 PM EST FRI DEC 29 2017
Have updated the forecast based on radar trends and latest near
term model guidance - particularly from the HRRR and NAM12.
Accordingly, have backed off on the snow showers and flurries
through the rest of the night. Have also updated the temperatures
with the latest blended model data and current obs/trends. The
updated grids have been sent to the NDFD and web servers. A fresh
set of zones and updated HWO have also been issued.
UPDATE Issued at 700 PM EST FRI DEC 29 2017
23z sfc analysis shows relatively weak low pressure throughout
the area with a mid level shortwave crossing the Ohio Valley
along with some limited moisture this evening. This has already
brought a band of snow to locations generally along and north of
Interstate 64. With a fleeting shot at whitening the roads in the
far north - pavement temperatures in the low 30s - did issue a
briefs SPS tracking the healthier parts of this snow band.
Additional light snow showers will be possible through the night,
but mainly confined to just flurries. Temperatures currently are
sub freezing for most of the area - generally in the mid to upper
20s. Dewpoints, meanwhile vary from the low 20s north, with the
snow, to the mid teens elsewhere as the winds are generally light
and variable. Updated the grids to adjust the PoPs and Wx
forecast with this initial snow band and in its wake - per radar
trends and latest HRRR guidance. Also tweaked the near term T and
Td grids to incorporate the latest obs and trends. These have
been sent to the NDFD and web servers.
&&
.SHORT TERM...(This evening through Saturday night)
Issued at 345 PM EST FRI DEC 29 2017
An upper level shortwave is currently passing through the northern
extent of the Great Lakes this afternoon, exiting overnight. At
the surface, this will translate to a low pressure system which
will be located over the Lower Great Lakes. This low pressure
system is expected to remain nearly stationary through tomorrow
(Saturday) afternoon before finally shifting eastward. A cold
front is trailing southeast of this low, currently located just
along and north of the Ohio River and through the state of Ohio.
This front will shift southeast into our region this evening and
overnight, where it will become stationary through Saturday
morning. It will lose considerable strength at this point, with
the majority of the precip still forecast to remain closer to the
parent low and northern extent of the cold front. Forecast models
are all in good agreement that there will be a sharp cutoff line
of QPF across north KY, with most of the QPF being centered over
Ohio. The question is how much of this QPF will actually make it
into our northern counties. While models are in good agreement,
any slight shift north or south could result in our northern
counties seeing an inch or more or snow, or no snow at all. As it
is now, tried to match up with neighboring offices to our north,
as well as latest hi-res and long range model guidance for QPF. If
anything, models are trending down across our region, which would
result in no snow, so ended up hand drawing some low end amounts
which equated to between a dusting and 0.7 inches of snow (highest
amounts closest to ILN and RLX borders). This is still a bit lower
than the previous forecast. Evening shift will continue to monitor
as the snow moves into the region in case any updates in these
amounts need to be made, including any issuances for an SPS or
greater headlines. Given low confidence and impacts, only included
mention in HWO at this time.
Lingering snow and snow flurries will be possible into the day
tomorrow, shifting to far eastern KY before exiting as the cold
front shifts southeast of the region. An upper level low will
traverse the Great Lakes during the day tomorrow, resulting in
lowering heights across the region and strengthening NW flow,
pulling much colder air from Canada into the Ohio Valley.
Meanwhile, at the surface, a strong area of high pressure will
move southeast from Canada and into the Dakotas. Its expanse will
be very broad, encompassing much of the Ohio Valley and Kentucky
behind the exiting cold front Saturday afternoon. Winds will
become more northerly across KY on the front edge of this high
pressure system, combining with the ongoing NW flow to pull more
arctic air into the region. As such, expect temps to start
bottoming out once again as we head into Saturday night, with
lows expected to be in the single digits to low teens across the
CWA despite some lingering cloud cover across the region.
.LONG TERM...(Sunday through Friday)
Issued at 411 PM EST FRI DEC 29 2017
Expansive high pressure that originated in Canada will continue to
slowly shift southward, with its influence eventually spanning
much of the central and eastern Conus throughout the course of the
extended period. Generally northern flow will be in place across
Kentucky during this time, as we will be placed on its SE fringes.
Meanwhile, aloft, a digging trough will be in place across the
Great Lakes and Ohio Valley, slowly shifting eastward throughout
the extended, with nearly meridional flow in place at times. This
will result in a strong pull of arctic air straight southward
into the state and some of the coldest temperatures we have seen
since last January. Unfortunately it appears as though the
coldest temperatures will also coincide with the New Years
holiday. Lows New Years Eve into New Years morning will be in the
single digits, with lows the following night possibly even a few
degrees colder. Highs most days during the extended will be in the
teens and low 20s.
By Wednesday of next week, a surface low will develop behind the
high pressure system, shifting southeast under the continued
influence of NW flow aloft. This will result in a developing cold
front which will also shift southeast and move into the Ohio
Valley, traversing KY Wednesday night. While ultimately this
system will weaken in the face of such a strong area of high
pressure, with no weather impacts other than some passing clouds
across the region, it will result in more Srly flow and warmer
temps in the upper 20s and low 30s during the day Wednesday. NW
flow behind the passing system will then quickly bottom out
temperatures once again Wednesday night back into the single
digits and low teens. The cold snap and arctic airmass will then
continue into the remainder of the extended forecast and even
after.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
ISSUED AT 725 PM EST FRI DEC 29 2017
High clouds will remain in place across the region through the
night, stemming from a weather system located to our north. Light
snow will be possible on our northern and eastern fringes from
this through the night. Look for some slight chances of light
snow for the rest of the area during the day Saturday as a cold
front presses through eastern Kentucky. Have included some VCSH
for this in the TAFs but expect only very brief and limited vis
restrictions. MVFR cigs, though, are expected to move in on
Saturday along with and ahead of that front and remain in place
until near the end of the TAF period for most spots. Winds will
generally be light and variable, under 5 knots into Saturday
morning before switching to the west and northwest at up to 10 kts
by mid afternoon following FROPA.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...GREIF
SHORT TERM...JMW
LONG TERM...JMW
AVIATION...JMW
Area Forecast Discussion
National Weather Service Lake Charles LA
1000 PM CST Fri Dec 29 2017
.DISCUSSION...
Latest high res runs indicate a gradual increase in light shower
activity later tonight as WAA develops on increasing srly flow
ahead of coastal trof along the TX coast...however local 00z
sounding showed a fair amount of low-level dry air, at least in
relation to recent moisture trends. In the end, have elected to go
against the HRRR and stay with inherited slim POPs only for parts
of sern TX. Elsewhere, inherited grids/zones look in good shape as
well based on latest obs/trends...thus no update is planned for
this evening.
25
&&
.PREV DISCUSSION... /issued 603 PM CST Fri Dec 29 2017/
DISCUSSION...
For 00z TAF issuance.
AVIATION...
VFR conditions have persisted this afternoon and are forecast to
continue through this evening as the cloud deck builds in from the
west. CIGS are progged to gradually lower to MVFR overnight into
Saturday in response to increasing low-level moisture. Winds will
be light and variable overnight, becoming easterly tomorrow.
Saturday, areas of drizzle will overspread the area from west to
east beginning around sunrise as a weak trough of low pressure
moves over the Texas coast and stalls over the area. Hires
guidance indicates fog development as early as tomorrow
afternoon, so expect visibilities reduced to IFR at all sites
beginning in the afternoon hours and continuing through the
evening.
RACKLEY
PREV DISCUSSION... /issued 341 PM CST Fri Dec 29 2017/
DISCUSSION...
A ridge of high pressure continues to be located to our north,
while a cold front is across the central Plains states, and a
frontal boundary is across the southern Gulf of Mexico. A weak
wave or trough of low pressure is trying to develop off the south
Texas coast, and it will move up the Texas coast tonight,
eventually bringing scattered rain showers into southeast Texas
after midnight tonight or tomorrow morning. This system will stall
out over our coast, keeping rain chances in the forecast Saturday
and Saturday night, before a strong high pressure system starts
to move south out of the northern Plains, and pushes it back
further out in the Gulf.
So the rain ends Sunday, before the freezing temperatures kick in
late Sunday night into Monday morning. Expect to see a hard freeze
Monday through Thursday mornings across much of the forecast area,
thanks to the strong high pressure system parking over the central
US. With these cold temperatures, expect to see hard freeze
warnings, and likely wind chill advisories as well.
The cold air will affect the coastal waters as well, where gale
conditions are possible by Sunday night into Monday. In addition,
with such strong northerly flow, a low water advisory may be
required for the Sabine-Neches and Calcasieu ship channels during
periods of low tides.
Erickson
&&
.PRELIMINARY POINT TEMPS/POPS...
AEX 40 53 39 41 / 10 30 40 30
LCH 46 58 47 52 / 10 50 40 30
LFT 44 56 47 50 / 10 50 40 40
BPT 48 60 49 53 / 20 50 40 30
&&
.LCH WATCHES/WARNINGS/ADVISORIES...
LA...None.
TX...None.
GM...None.
&&
$$
Area Forecast Discussion
National Weather Service Norman OK
959 PM CST Fri Dec 29 2017
.UPDATE...
Lowered forecast low temperatures slightly, and quickened cooling
in the hourly temperature grids.
&&
.DISCUSSION...
The cold front has arrived into northwestern Oklahoma.
Temperatures have dropped quickly down to 24-25 degrees in
Garfield, Major and Alfalfa Counties where winds are relatively
light. These temperatures may rise a bit again as northerly winds
increase and mix slightly warmer temperatures to the surface (as
occurred farther northwest at Buffalo and May Ranch mesonets),
but that will only be temporary as cold advection will continue
overnight. Have quickened the pace of cooling with the frontal
passage by trending hourly temperature grids toward the HRRR
forecast. Overall, this adjustment lowers the forecast min
temperature slightly in general. Of note, the forecast low
temperature grids are technically valid for the low temperature
through 15Z (or 9 AM CST). Some areas may actually reach slightly
lower temperatures just after 9 AM on Saturday morning.
&&
.PREV DISCUSSION... /issued 555 PM CST Fri Dec 29 2017/
DISCUSSION...
AVIATION...
VFR ceilings in northwestern Oklahoma and MVFR ceilings in
central and southern OKlahoma will likely lower to IFR later
tonight after the arrival of a cold front and shift to north
winds. Fog is expected in southwestern Oklahoma and adjacent parts
of northern Texas. Light freezing drizzle is expected at times
Saturday morning. Any freezing drizzle, fog, and low cloud
conditions will clear from the north on Saturday afternoon across
the northern part of Oklahoma.
PREV DISCUSSION... /issued 342 PM CST Fri Dec 29 2017/
DISCUSSION...
Overall not a lot of changes were made to the forecast.
Low clouds remain across roughly the eastern two-thirds of
Oklahoma and parts of western north Texas this afternoon. Further
clearing may occur this afternoon, especially across western
Oklahoma. This evening, areas of fog may develop across southwest
Oklahoma and western north Texas as winds decrease ahead of a
strong cold front. Some of the fog may be dense. A little unsure
about freezing fog or what impact the fog may cause as
temperatures fall below freezing in west central Oklahoma by
midnight. For now will leave as areas of fog. As the front moves
across the area tonight, any dense fog will dissipate by sunrise
Saturday.
Model soundings continue to show a rather shallow moist layer behind
the front. Perhaps enough lift will occur that patchy freezing
drizzle may develop late tonight into Saturday. Enough cooling
across roughly the northern half of Oklahoma may result in mainly
snow with better chances of freezing drizzle across southern
Oklahoma and north Texas.
As a trough moves across the Pacific Northwest and into the northern
and central Rockies, the bulk of a very cold airmass will build
southward into the central and southern Plains Sunday into Monday.
Wintry precipitation chances should increase again Saturday night
into Sunday. Soundings indicate the best opportunity for freezing
drizzle or light snow will be across the southern third of
Oklahoma and northwest Texas where a deeper moist layer is
expected. By Sunday afternoon/evening, dry weather is expected
with very cold temperatures.
The main story this weekend into early next week will be well below
average temperatures. On Sunday into Monday, the very cold air
will combine with rather breezy conditions to produce bitterly
cold wind chill values. At this time, it appears that a Wind
Chill Advisory will be required for the north half/two-thirds of
Oklahoma (Sunday into Monday).
Dry and cold weather is expected to prevail Tuesday into at least
Thursday of next week.
&&
.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK 25 29 15 20 / 0 10 10 0
Hobart OK 24 30 15 23 / 0 10 10 0
Wichita Falls TX 31 33 22 27 / 10 10 20 0
Gage OK 16 26 9 18 / 0 10 10 0
Ponca City OK 18 26 9 17 / 0 10 10 0
Durant OK 37 39 26 28 / 10 10 20 10
&&
.OUN WATCHES/WARNINGS/ADVISORIES...
OK...None.
TX...None.
&&
$$
Area Forecast Discussion
National Weather Service Topeka KS
723 PM CST Fri Dec 29 2017
.UPDATE...
Issued at 723 PM CST Fri Dec 29 2017
Updated the forecast to include a mention of very light freezing
drizzle or flurries this evening. Radar is picking up on some
light returns along the KS river. Additionally a few OBS are
showing visibilities of 2 to 3 miles. After a few calls, the light
returns on radar appears to be some light mist or fog. I don`t
think this should last for very long as the models show downglide
increasing behind the front. However there potentially could be a
few slick spots develop on untreated roads.
&&
.SHORT TERM...(This evening through Saturday)
Issued at 230 PM CST Fri Dec 29 2017
Isentropic lift concentrated across northeastern Kansas has produced
a few areas of flurries/sprinkles which were noted on radar mostly
across western Missouri, although a few areas across far eastern
Kansas also saw some precipitation. Kept this mention of flurries
in far northeastern Kansas through the early evening. With
temperatures struggling to reach above freezing, a few spritz of
freezing drizzle may also occur in this area. With roadways well
below freezing, this could cause hazardous driving conditions
wherever this occurs. Any chances for this precipitation are
expected to end by early evening with dry conditions for the rest of
the period.
For tonight, winds shift from the north and temperatures plummet
back to the single digits with the exception of east central Kansas.
Gusty winds behind the front tonight bring wind chills down between
-1 to -14 across the entire area. Temperatures do not recover much
during the day, with highs ranging still from the single digits
in northern Kansas to the teens in east central Kansas. One the
light of the forecast for tomorrow is that skies may briefly
clear during the afternoon hours.
.LONG TERM...(Saturday night through Friday)
Issued at 230 PM CST Fri Dec 29 2017
Bitterly cold and dry conditions still look to be the main story of
the beginning of the extended forecast period.
The first shot comes Saturday night where low temperatures range
from +1 to -5 across the area. Wind chills across the entire area
will range from -12 to -19 degrees by Sunday morning. Surface high
pressure of 1055mb continues to work its way into the area Sunday.
Temperatures barely nudge up into the single digits on New Year`s
Eve with enhanced cold air advection continuing to spill into the
area. Sunday night into Monday morning looks to be the coldest of
the period with low temperatures ranging from -8 to -15 across
northeastern Kansas. When accounting for wind chills, values of -24
to -31 are likely making this cold snap potentially dangerous. For
now, have issued a Wind Chill Watch for the entire outlook area from
Saturday night through Monday morning to highlight this threat.
New Year`s Day also looks to be in the single digits, with the
aforementioned high pressure sliding over eastern Kansas by Monday
night. Monday night looks to be the last of the nights with some
wind chills below -15. From here, temperatures rebound into the 20s
for the rest of the week with no precipitation to speak of.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday)
Issued at 457 PM CST Fri Dec 29 2017
Main question is when MVFR CIGS will lift above 3 KFT. RAP and NAM
are fairly progressive with improving CIGS, but obs indicate a
rather broad MVFR deck across most of NEB and into southern SD.
Because of this think the RAP and NAM may be a little to quick in
improving CIGS. Chances for precip appear to be pretty small so
once the CIGS improve, think VFR conditions will prevail through
the afternoon Saturday.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
Wind Chill Watch from late Saturday night through Monday morning
for KSZ008>012-020>024-026-034>040-054>056-058-059.
&&
$$
UPDATE...Wolters
SHORT TERM...Heller
LONG TERM...Heller
AVIATION...Wolters
Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
434 PM MST Fri Dec 29 2017
.DISCUSSION...(This Evening Through Friday)
Issued at 209 PM MST Fri Dec 29 2017
Broad cyclonic flow continues across much of the CONUS as very cold
air sits across the northern Plains into the Great Lakes region and
Northeast. Northwest flow aloft persists across the region, with a
series of weak waves pushing through. Surface analysis shows arctic
high pressure across Alberta sliding southeast toward the Dakotas.
Temperatures have been steady or falling across the CWA. KUDX radar
has been showing snowfall persisting through the day across the
southern Black Hills. Snow has been increasing over the last hours
across the northern Black Hills and adjacent plains. Models show
leeside convergence enhancing the snowfall through the rest of the
afternoon across the southeastern to eastern portions of the Black
Hills and foothills. With snow already falling across portions of
the Hills, will move up to the start time of the Winter Weather
Advisory to when the afternoon package is issued. Rest of the
headlines are in good shape at this point. Snow will increase in
coverage this evening and continue through Saturday afternoon. The
best snowfall rates are expected to be tomorrow late morning into
the afternoon as a strong upper waves pushes through the Dakotas.
Additional snowfall amounts ranging from 2 to 6 inches are expected
across much of northeast Wyoming and western South Dakota. Behind
the departing wave, dry weather will move into the region and
continue through much of next week. Very cold temperatures are also
expected through Monday. Sunday is still expected to be the coldest
day, with highs ranging from 5 above to 10 below. The coldest night
for most locations will be Monday morning, with lows ranging from 10
below to 30 below zero. Wind chills that morning could range from 20
below to 45 below zero. Will have to continue to monitor for
possible future headlines. Much warmer air will advect in by Tuesday
with highs much closer to seasonal averages but still slightly
below. These temps will generally continue through much of next
week.
&&
.AVIATION...(For the 00Z TAFS Through 00Z Saturday Evening)
Issued At 434 PM MST Fri Dec 29 2017
Through the overnight hours, MVFR/IFR conditions are expected
within a broken band of snow oriented northwest to southeast
across our area. For now, have GCC with IFR VSBYS through most of
the night, though there will likely be some periods where snow
weakens and VSBYS temporarily improve. Generally expect snow band
to lift northeastward away from GCC as we approach daybreak,
leading to improved conditions on Saturday. Given short-term
model agreement, suspect that RAP will see a brief lull/weakening
in snow over the next two or three hours before returning to
MVFR/IFR conditions later tonight through much of Saturday.
&&
.UNR WATCHES/WARNINGS/ADVISORIES...
SD...Winter Weather Advisory until 11 PM MST Saturday for SDZ001-002-
012-024>026-028>030-072-074.
Wind Chill Advisory from 11 PM MST /midnight CST/ this evening
to 11 AM MST /noon CST/ Saturday for SDZ027-041>044-046-047-
049.
Winter Weather Advisory from 11 PM this evening to 11 PM MST
Saturday for SDZ013-014-031-032-073.
WY...Winter Weather Advisory until 11 PM MST Saturday for WYZ054-056-
057-071.
Wind Chill Advisory from 11 PM this evening to 11 AM MST
Saturday for WYZ055-058.
&&
$$
DISCUSSION...13
AVIATION...Sherburn