Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/28/18
Area Forecast Discussion
National Weather Service Burlington VT
1040 PM EST Tue Nov 27 2018
.SYNOPSIS...
Low pressure over the Maine coast this afternoon will continue to
provide portions of the area with light to moderate snow through
Wednesday with additional accumulations expected. High pressure and
dry weather build briefly into the region for Thursday through
Saturday before the threat of rain and snow return again Saturday
night and Sunday. Temperatures will remain near to slightly below
late November seasonal norms through the period.
&&
.NEAR TERM /THROUGH WEDNESDAY NIGHT/...
As of 1036 PM EST Tuesday...Low stratus and periods of snow
showers continue across the North Country this evening, within
broad cyclonic circulation on wrn periphery of the vertically
stacked low pressure near the mid-coast of Maine at 03Z/Wed.
Froude numbers expected to remain around 0.5 overnight should
maintain orographically blocked flow. Have seen a significant
increase in radar reflectivity (including a few pixels 35-40dBZ)
as deeper moisture/saturation in dendrite growth layer as
pivoted swd from srn Quebec into nwrn VT. Should see best
snowfall accumulation potential in the Champlain Valley between
04-09Z per latest HRRR guidance (1-2"). Otherwise, with
generally NW flow regime, the most frequent snow shower activity
will remain in place across the nrn Adirondacks and central/nrn
Green Mtns, where an additional 2-4" of snowfall is possible
thru Wednesday AM. With the low stratus in place, anticipate
temperatures quasi-steady overnight, with lows generally in the
upper 20s to lower 30s...and 31-32F at BTV.
Previous Discussion...As promised additional changes have been
made to headlines going into tonight and Wednesday with the
threat of upslope snow developing over portions of the region.
Interesting setup we`ll have going on through Wednesday as
vertically stacked low pressure over the Maine coast this
afternoon will very slowly shift north into western Maine
tonight, while around daybreak Wednesday a wave of low pressure
will develop well offshore along a thermal boundary over Gulf
Stream. During the day Wednesday, that wave undergoes explosive
cyclogenesis as is tracks northward towards Newfoundland and
effectively pulls the best forcing east of the region by the
days end.
For this afternoon into early evening, with the primary low sitting
just to our east we`re seeing a break in precipitation though many
stations are still reporting light snow. Spotter reports indicate
snow is mixed with drizzle and/or snizzle, but as the surface low
shifts just slightly northward favorable conditions will develop for
upslope snow to blossom over the Adirondacks and western slopes of
the Green Mountains towards the midnight hour. In addition, per our
locally run 4km WRF model, the surface to low-level flow will be
severely blocked so expect snow to backup into northern portions of
the Champlain Valley as well with snow accumulations through
Wednesday in the 4-8" range below 1500 feet, with up towards another
foot across the higher peaks.
Snow finally winds down Wednesday night with perhaps a couple more
inches across the higher terrain. Temps through the period don`t
really go much of anywhere under a deep cloud layer with lows
tonight and Wednesday night in the mid 20s to low 30s, and highs
Wednesday only in the low to mid 30s.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY/...
As of 248 PM EST Tuesday...A meandering upper level low will be
slowly exiting to our west and mountain snow showers will
finally come to an end on Thursday. Ridging will build in and
we should see dry weather finally over the North Country for
Thursday night into Friday. Clouds will continue across the
region even as the precip comes to an end. The ridging occurs
without much in the way of warm or cold advection so expect
temps to stay fairly similar with highs in the mid 30s and lows
in the 20s.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
As of 248 PM EST Tuesday...The weekend starts another rinse and
repeat of an active pattern. Late Friday night a weak upper
level shortwave lifts north and brings some light snow showers
across the region. That sets the stage for Saturday night into
Sunday when another low pressure system lifts out of the Ohio
Valley region up through the Saint Lawrence Valley bring gusty
winds and warmer temps to the region along with a wintry mix
transitioning to rain for most of the area during the day on
Sunday. Almost all of the medium ranged guidance points to a
modest warm nose and eventual dry slot pushing into the
Adirondacks first spreading into the Champlain Valley and the
rest of Vermont by Sunday afternoon.
The initial 850mb jet max pushes some 40-50kt winds into the
northern Adirondacks and so we may see some modestly gusty winds
especially in the downslope region north of the Adirondacks and
into the Champlain Valley as we see some valley funneling
effects. Still a lot of timing variations and location
differences that will need to be ironed out before specific
details are available.
Temps should be around seasonal norms with highs in the mid to
upper 30s and lows in the upper 20s to low 30s.
&&
.AVIATION /04Z WEDNESDAY THROUGH SUNDAY/...
Through 00Z Thursday...Widespread MVFR with intervals of IFR
conditions in snow showers will persist with slow-moving upper
low near the Maine coast. TRRN OBSCD across most of the North
Country thru the next 18-24hrs. Winds will remain nwly at
5-10kts overnight, increasing to 10-12kt with gusts 18-20kt Wed
afternoon.
Outlook...
Wednesday: Mainly MVFR, with local IFR possible. Likely SHSN,
Definite SN, Likely SHRA.
Wednesday Night: Mainly MVFR, with local VFR possible. Chance
SHSN.
Thursday: Mainly MVFR, with local VFR possible. Slight chance
SHSN.
Thursday Night: Mainly MVFR, with local IFR possible. Slight
chance SHSN.
Friday: Mainly MVFR, with local IFR possible. Slight chance SHSN.
Friday Night: Mainly VFR, with areas MVFR possible. Slight chance
SN, Slight chance SHSN.
Saturday: Mainly MVFR, with areas VFR possible. Slight chance SN.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...Winter Weather Advisory until 7 PM EST Wednesday for
VTZ001>008-010-016>019.
NY...Winter Weather Advisory until 7 PM EST Wednesday for
NYZ028>031-034.
&&
$$
SYNOPSIS...Lahiff
NEAR TERM...Banacos/Lahiff
SHORT TERM...Deal
LONG TERM...Deal
AVIATION...Banacos
Area Forecast Discussion
National Weather Service Lincoln IL
859 PM CST Tue Nov 27 2018
.UPDATE...
Issued at 859 PM CST Tue Nov 27 2018
Main concern overnight is with low temps. Evening temp trend has
been for a rapid fall toward forecast lows, under clearing skies
and weakening winds. Also northwestern areas have a decent snow
pack. High surface pressure will continue to advance into Illinois
overnight, sending the winds toward calm conditions in most areas
by sunrise tomorrow. Cloud cover will be the challenge, with some
mid-level clouds advancing across the northern counties. HRRR
guidance is not handling those clouds well, and neither is the
RAP model. Timing of the clouds based on satellite trends looks
like the clouds are on track to advance east of our counties
before sunrise. Current dewpoints are in the 9-14F range in most
of the CWA, with a bit of recovery expected later tonight. Expect
lows to drop 2 to 3 degrees below forecast lows across the middle
of the cwa, where the largest temp differences between forecast
and obs have occurred. Forecast lows in our NW counties still look
on track for around 6F. Southeast counties look good in the upper
teens. I-55 corridor should bottom out around 11-12F. While winds
will be relatively light in the morning, wind chills will drop
between -5 and +5 in most areas, very cold for this time of year.
Updated forecast info is already available.
&&
.SHORT TERM...(This evening through Wednesday)
ISSUED AT 242 PM CST Tue Nov 27 2018
Upper level rotation was located near Green Bay per water vapor
imagery this afternoon, with a fast moving trough pivoting
southeast across central Illinois. Snow showers over the eastern
CWA picked up a bit in intensity after late morning, with some
visibility reductions to around 2-3 miles. Webcams from Danville
show a noticeable whitening of rooftops, though pavement appears
to be mainly wet. A few flurries were also moving in from the
Galesburg and Macomb areas. Think the snow should move out quickly
late this afternoon as the upper trough exits the area, and will
go dry for tonight.
Main concern will be with tonight`s lows over the deeper snow
pack in the northwest CWA. Have undercut the colder MAV guidance
in that area by a couple degrees, with lows of 5-10 west and north
of Peoria and mid teens elsewhere. As a ridge builds into the
Mississippi Valley, winds will lighten up quite a bit, though wind
chills could still dip below zero northwest of the Illinois
River. As the ridge shifts east on Wednesday, clouds will increase
ahead of a warm front, but lots of dry air above the inversion
will keep the dry weather in place. Some moderation of
temperatures will occur on the back side of the ridge, but much of
the CWA will still be near or just below freezing.
.LONG TERM...(Wednesday night through Tuesday)
ISSUED AT 242 PM CST Tue Nov 27 2018
Upper level pattern becomes more zonal after mid week, bringing a
welcome break from the recent cold weather. By early next week,
the GFS and Canadian models suggest more of a broad upper trough
over the western 2/3 of the CONUS with another cooler trend,
though the European model generally limits it to closer to the
Canadian border.
Main energy with the mid week shortwave will track to our north,
so dry conditions will continue into early Thursday. With more of
a subtle shortwave moving east from the Plains, the models have
more of a disagreement with the Thursday/Friday time frame. The
GFS is the wettest with development north of a warm front Thursday
evening, while the remaining synoptic scale models keep the
majority of the precipitation to the southeast. Will mainly limit
PoP mention to the eastern CWA for Thursday night, with the NAM
agreeing somewhat with the GFS solution. Forecast soundings on
both models show a rather prominent low level warm nose, with the
colder NAM suggesting a potential for freezing rain. However, its
soundings keep areas from Champaign east and south above freezing
throughout the low levels, so any freezing potential will be
limited to closer to Lincoln and Bloomington. With these areas
having only slight chance PoP`s, a mention will not be included in
the worded forecasts at this point.
Rather strong storm system begins to take shape over the western
Plains on Friday, closing off into a large upper low over the
weekend. Morning model suite continues to favor more of a northern
solution with the track, though the speed is more of a factor. The
European model is slowest and strongest of the solutions. Think
the GFS is a bit too fast due to a weaker solution, so will lean
more in the ECMWF direction. In any event, rain will be widespread
late Friday night through Saturday morning. Will maintain a
mention of thunder across the southern half of the forecast area
for this period, with strong low level advection resulting in
around 500 J/kg of CAPE. Track of this system will also bring much
milder air into the area, with upper 50s to mid 60s east of the
Illinois River, but a bit cooler northwest depending on residual
snow cover.
By late weekend, the European model suggests the upper low will
open up and swing across the Midwest Sunday night, while the GFS
tries to form a new system with a track similar to a few days ago.
Blended model solutions lean more toward the GFS trend, but there
isn`t enough continuity to make much changes at this point. Thus,
we`ll keep the precipitation mention for early next week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 544 PM CST Tue Nov 27 2018
a shortwave in the upper level flow has triggered MVFR clouds and
flurries late this afternoon, and those conditions will linger at
DEC and CMI for an hour or two of the 00z TAF period. Beyond that,
VFR conditions should prevail through tomorrow afternoon. An area
of 5K FT clouds are drifting toward our northern TAF sites for
this evening, with PIA, BMI and CMI expected to see those clouds
for several hours before they shift off to the east around
midnight. There may even be a few flurries out of those clouds,
but no major significance to aviation.
Winds will be W-NW tonight, then shift out of the south-SW
tomorrow as a surface ridge axis shifts east of Illinois. The next
wave of clouds is expected to arrive during the afternoon
tomorrow, as a shortwave rotates through northern Illinois. Once
again, a few flurries cloud develop, but no reduction in
visibility is anticipated. The wind speeds should generally remain
less than 10kt through tomorrow, under a weak pressure gradient.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Shimon
SHORT TERM...Geelhart
LONG TERM...Geelhart
AVIATION...Shimon
Area Forecast Discussion
National Weather Service Louisville KY
818 PM EST Tue Nov 27 2018
.Forecast Update...
Issued at 818 PM EST Tue Nov 27 2018
The forecast appears to be on track at this hour as light snow
showers continue to persist along and northeast of a Hartford, KY to
Lake Cumberland line. In other words, we are seeing snow showers
where the stratus deck continues to linger. Recent satellite trends
do show and end in sight as the clearing line is slowly working
northward along with the western edge advecting eastward into the
Wabash River Valley at this hour. As we move through the late
evening, we`ll gradually be able to see a drying trend across
northwest and central parts of the CWA. The Bluegrass region will
have the longest residence time under the stratus deck and
continuing light snow showers so will keep the Winter Weather
Advisory going in that area for light accumulations of snow, and
some impacted roadways. In addition, the current Special Weather
Statement looks good through Midnight in all of the counties not in
the Advisory but still under the stratus deck as it continues to
snow. Slick spots should be more patchy in nature in these areas
along with any light accumulations a half an inch or less. Will
likely be able to trim some counties out of the SPS at Midnight, but
will also probably have to extend some of the counties further north
and east deeper into the overnight.
Overall, the forecast is on track and have only freshened up latest
obs, sky cover, and snow coverage based on the current stratus deck
position. Also lowered temps a degree or two with most spots likely
in the upper teens and lower 20s by dawn.
&&
.Short Term...(This evening through Wednesday)
Issued at 230 PM EST Tue Nov 27 2018
Low-confidence forecast as the models continue to struggle. Broad
and deep cyclonic flow over the eastern CONUS, as a strong closed
low moves into New England, with an older cyclone now starting to
open up as it dives southward from Lake Superior.
As this vort lobe swings through the Ohio Valley this evening, we do
expect it to spawn at least scattered snow showers. This is not
handled well by any of the synoptic models, nor most of the hi-res
models, but neither has most of the precip in the last 24-36 hrs.
However, the HRRR is showing narrow bands of up to 0.04" of QPF in
parts of the northern Bluegrass region, and with a 20-1 snow ratio
that will approach 1 inch of accumulation. There are even some hints
that a few spots could get close to 2 inches. Given that and the
timing after dark, have coordinated with JKL on a Winter Weather
Advisory for the Lexington metro and points northeast. Could see
the whole range from flurries to 1-2 inches even within the
advisory area.
West of Interstate 65 and along the KY/TN border, any flurries and
snow showers will most likely taper off early, and we could see some
partial clearing after midnight.
By Wednesday the upper ridging over the Plains and surface high over
the Tennessee Valley start to win out, but warm advection clouds
will limit the temp recovery and we won`t get out of the 30s.
.Long Term...(Wednesday night through Tuesday)
Issued at 345 PM EST Tue Nov 27 2018
A little bit of weather whiplash lies ahead as Mother Nature tries
to turn back the calendar during the extended period, bringing us
back from the precipice of winter.
Temperatures start to warm first thing Thursday morning as south
winds return on the back side of the cold surface high that will be
moving over us tomorrow. Some of the early warm air advection
associated with the return flow will ride over the top of the cold
air entrenched at the surface and COULD result in a brief period of
wintry mix (1-3 hours) just after sunrise, but with limited moisture
and warming temperatures, this should have limited impact, with only
trace amounts of precipitation expected.
From Thursday morning onward, precipitation chances persist through
the rest of the forecast, save for a 24-hour period from Saturday
evening through Sunday afternoon. Rainfall on Thursday and Friday
will be associated with weak ripples in nearly zonal upper air flow,
with accumulation likely less than a tenth of an inch. By Friday
night though, strong southerly winds ahead of a deepening trof and
associated surface low over the central plains will set the stage
for heavier rainfall - and possibly some thunder - by Saturday. SPC
has identified the potential for severe storms with this system over
the southern Mississippi Valley but it bears keeping an eye on for
our area as well.
Depending on how long the Gulf opens up ahead of this system, and
the strength of the low level wind field, dew points should push
back into the 50s, helping to squeeze out another 1.0" - 1.5" of
rainfall for much of the area. This would be enough to put
Lexington over the top for the wettest year on record (currently in
3rd place, needing 0.78" to take over 1st place). Louisville is
currently in 4th place for annual precip, but needs another 5.2" to
take over the lead...which will NOT happen with this system.
Incoming energy into the western U.S. while the Saturday system
dumps rain on us will serve to reload the upper flow pattern for yet
another southwest-to-northeast moving storm system early next week
to take us out through day 7. This far out, nothing is definite, but
the current progs show it as a middling system - warmer than the one
dumping snow showers on us today, but colder than the anticipated
rain maker coming in Friday night and Saturday. Only time will tell
whether this will pan out.
Temperature-wise, we`ll see a steady rise in daytime highs from the
40s Thursday into the 50s Friday and the 60s on Saturday before the
trend reverses back down to the upper 40s to mid 50s by Tuesday. Low
temperatures in the 20s Wednesday night will warm each night until
only bottoming out in the 50s by Saturday morning (near our normal
highs for the date) before dropping back into the upper 30s and
lower 40s by Tuesday morning.
&&
.Aviation...(00Z TAF Issuance)
Updated at 640 PM EST Tue Nov 27 2018
Starting to see an end in sight for the persistent stratus deck that
has plagued the area with mostly MVFR ceilings and lingering snow
showers. BWG has already cleared out and is expected to stat VFR for
the remainder of this cycle. HNB is expected to see clearing between
8 and 10 PM CST, with VFR prevailing thereafter.
SDF is expected to hold onto lingering light snow and ceilings right
around the VFR/MVFR threshold through 2 AM EST. Thereafter, expect
things to scatter out with VFR prevailing. LEX will hold onto the
stratus deck the longest and will likely see a period of prevailing
MVFR ceilings around 2500 ft agl overnight. LEX could scatter out
around sunrise on Wednesday with VFR prevailing thereafter.
Otherwise, expect steady WNW and W winds to slacken and become light
and variable later tonight into Wednesday. In addition, a Sct-Bkn
mid to upper cloud deck will move overhead later Wednesday.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...None.
KY...Winter Weather Advisory until 4 AM EST Wednesday for KYZ036-037-
041>043-049.
&&
$$
Update...BJS
Short Term...RAS
Long Term...JBS
Aviation...BJS
Area Forecast Discussion
National Weather Service Marquette MI
648 PM EST Tue Nov 27 2018
.SHORT TERM...(This evening through Wednesday)
Issued at 351 PM EST TUE NOV 27 2018
WV imagery and RAP analysis indicated a mid/upper level trough
extending from northern New England into the western Great Lakes.
With 850 mb temps around -15C, northwest flow LES prevailed into
Upper Michigan. The stronger dominant band into western Alger
County, supported by low level conv se of Keweenaw Bay had
diminished leaving mainly light snow showers.
Tonight, high pressure building into the area with mid level ridging
and qvector div will result in dropping inversion heights from 5k-6k
ft to near 3k ft. This should minimized additional LES
accumulations, especially over the west where weak increasingly
anticyclonic flow will develop after the 850-700mb moisture sags to
the south. However, an additional 1-3 inches will still be possible,
mainly into Alger county downstream from the longest fetch and where
low level conv will still be favored.
Wednesday, the surface ridge will build into central Upper Michigan
by the afternoon bringing an end to the light snow showers or
flurries over the west. Some sct -shsn will still linger over the
east but with little accumulation. Otherwise, clouds will persist
with highs only climbing into the upper 20s west and lower 30s east.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 404 PM EST TUE NOV 27 2018
Strong, but weakening positive height anomaly (near 300m at 500mb),
over ne Canada is still fcst to drift a little farther w, becoming
centered vcnty of Hudson Bay during the last half of this week where
it will continue to weaken. To the s of this positive height
anomaly, broad mid-level low currently over the Great Lakes to New
England will already be getting kicked downstream on Wed by a
Pacific shortwave trof which will have reached the Rockies. This
trof will bring a band of -sn across the fcst area late Wed night
thru Thu evening. Being of Pacific origin, air mass following this
trof will not be cold enough to support LES. Thus, dry weather
should mostly prevail Fri thru at least the first part of Sat. Over
the weekend, attention turns to the trof moving onshore over the
western CONUS Thu and reaching the central CONUS Sat. This trof will
generate a southern Plains low pres system that will lift ne into
the Great Lakes on Sun. Still appears that a couple of factors will
influence the track, including the positive height anomaly vcnty of
Hudson Bay, though it will be weakening. It is noted that so far
this anomaly has remained stronger, longer than models indicated at
longer ranges, including trends over the last couple of days for the
late week period. This anomaly, including positive height anomalies
in general across much of Canada, suggest a suppressed storm track.
Opposing the suppressed low track idea is the rather strong trof
reaching the western CONUS over the weekend which would force rising
heights downstream. This in turn would tend to force the central
CONUS wave on a track farther n. Difficult to assess which will have
more influence on the storm track, but CMC/ECMWF trends over the
last 24hrs support the latter idea with a farther n low track and a
rain or snow/mixed ptype event for Upper MI. The GFS continues its
persistent, more suppressed track that is far enough s to keep pcpn
s of Upper MI. Last 24hrs of GFS/CMC ensembles lend more support for
a track n of the operational GFS runs, suggesting the GFS is an
unlikely outcome. In any event, no matter where the eventual track
ends up, the low pres system is likely to reach peak intensity over
the Plains, then weaken as it shears ne due to the building heights
being forced over the central/eastern CONUS by the strong shortwave
trof moving into the western CONUS this weekend. This trof should go
on to produce another southern Plains low pres system early next
week that may lift ne toward the Great Lakes on Tue. With the
passage of the first wave, it`s more likely that the second system
would produce snow rather than mixed ptypes for Upper MI if Upper MI
is impacted by the system at all. As for temps, transition to a more
zonally oriented flow Wed/Thu will lead to warming with temps rising
to around normal or a little above normal Thu into the weekend.
Temps will fall back some early next week, but more so mid and late
next week as what should be temporary building of a ridge vcnty of
the w coast of N America forces a deepening central/eastern N
America trof. Temps should fall back solidly blo normal which will
favor an active LES regime.
Beginning Wed night thru Thu night...shortwave trof will reach the
Upper Lakes late Thu. Zone of waa/isentropic ascent ahead of rather
sharp 850mb trof will yield a band of -sn spreading across the fcst
area from wsw to ene late Wed night thru Thu. From an isentropic
standpoint, mixing ratios of 2.5-3g/kg roughly around 725mb could
support advy level accumulations. However, as was the case
yesterday, all of the guidance continue to show weak isentropic
ascent and weak upward motion thru a high DGZ centered around 13kft.
Thus, snow amounts will be light, probably on the order of 1 to
possibly 2 inches. Should have some lake enhancement off Lake MI Thu
aftn/evening under se to s winds and 850mb temps around -5C to boost
amounts a bit near Lake MI. Not much of a signal in the model
guidance for enhancement, but certainly could see a 1-2 inch boost
in amounts over the synoptic snowfall. As the trof shifts across the
area late Thu aftn/night, pcpn will end. Not out of the question
that there could be some patchy -fzdz as -sn ends with deep moisture
departing.
As previously discussed, it looks generally dry/quiet Fri into at
least Sat morning. Later Sat into Sun, a low pres system is expected
to track ne into the Great Lakes region. At this point, recent days
operational medium range models and GFS/CMC ensembles support pcpn
(snow, rain or mixed ptypes) lifting n into Upper MI Sat aftn/night,
then diminishing/ending on Sun. Although expectation is for a
weakening system as it lifts into the Great Lakes, it still remains
to be seen whether or not this ends up as an advy type event for at
least part of the fcst area.
Considerable lack of run-to-run continuity in model guidance exists
early next week. Some LES will be possible Mon, depending on how
much caa follows the weekend system. May see some snow area wide on
Tue, either from a low lifting out of the southern Plains or from a
shortwave approaching from the nw.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 647 PM EST TUE NOV 27 2018
Northwest flow lake effect snow and flurries continues into
Wednesday. Prevailing vsby will be VFR but could drop to MVFR at
times. MVFR cigs will persist through Wed. May see low cigs start
to scatter out on Wed night. &&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 351 PM EST TUE NOV 27 2018
Northwest winds 15-25 knots will diminish to less than 20 knots
overnight as high pressure builds toward the region. Weak ridging
moving into the area Wed into Thu followed by a weak low pressure
trough Thu night into Fri will generally result in winds less
than 20 knots for the latter half of the week. Low pres lifting
into the Great Lakes over the weekend will result in increasing e
to ne winds. Probably looking at 20-30kt winds, but possible gale
force winds could occur, depending on the strength of the low.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...JLB
LONG TERM...Rolfson
AVIATION...JLA
MARINE...JLB
Area Forecast Discussion
National Weather Service Spokane WA
641 PM PST Tue Nov 27 2018
.SYNOPSIS...
Rain and higher elevation snow showers will linger over the Inland
Northwest overnight into Wednesday and Thursday. A quieter
weather pattern is expected by the end of the week although light
mountain precipitation is possible. A cooler and drier weather
pattern is expected over the weekend into early next week.
&&
.DISCUSSION...
Updated the forecast to increase the mention of fog this evening
and isolated/scattered showers overnight. The high resolution
models indicate a weak wave moving across the Columbia Basin
overnight and into north Idaho by Wed morning. Qpf looks light as
does the mountain snow accumulations. Winds remain southerly
overnight. /rfox.
&&
.AVIATION...
00Z TAFS: The frontal boundary is slowly sagging through the Idaho
Panhandle with a band of post frontal stratus developing. Expect
deteriorating conditions this evening in most locations with ample
boundary layer moisture. HRRR shows the best chance of IFR
conditions near KGEG this evening and spreading toward KSFF and
KCOE, and then westward toward KMWH. Spotty showers return
overnight which may be enough to raise ceilings and improve
visibilities temporarily into early Wednesday morning. KEAT and
KLWS should remain VFR overnight into Wed morning. /rfox.
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 36 42 32 40 32 38 / 30 50 20 20 20 30
Coeur d`Alene 37 42 32 40 31 37 / 30 70 20 20 20 50
Pullman 37 46 33 44 31 38 / 40 60 20 10 30 60
Lewiston 40 51 34 46 34 42 / 60 50 20 10 30 60
Colville 34 43 33 40 31 39 / 30 40 30 30 10 30
Sandpoint 36 41 32 39 31 38 / 40 70 40 30 20 60
Kellogg 36 40 32 39 30 36 / 70 90 20 20 30 80
Moses Lake 32 45 32 43 31 41 / 20 0 30 10 10 10
Wenatchee 34 44 33 40 30 40 / 10 10 40 20 10 10
Omak 33 42 32 40 28 38 / 20 10 40 30 10 10
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
Area Forecast Discussion
National Weather Service Paducah KY
513 PM CST Tue Nov 27 2018
.UPDATE...
Issued at 511 PM CST Tue Nov 27 2018
Updated Aviation discussion for 00Z TAF Issuance.
&&
.SHORT TERM...(Tonight through Thursday night)
Issued at 225 PM CST Tue Nov 27 2018
Looking at satellite trends and 1000-850mb HRRR RH guidance,
clouds and scattered light snow/flurries across southwest Indiana
and portions of southern Illinois and west Kentucky should
continue to move east into this evening. This will result in clear
skies across most of our area by 06z. Our far northeast counties
may take a little longer with the HRRR showing another little
surge of 1000-850mb moisture between 06z and 12z, so some cloud
cover adjustments may be needed this evening. Models show a
surface high moving across our region, and this should give us
decreasing winds tonight.
The high will move southeast of our region by late tonight. Winds
will become southerly for Wednesday. Along with quite a bit of
sunshine at least early in the day, temperatures will begin
moderating with highs on Wednesday in the middle 30s northeast to
the lower 40s southwest.
Models remain in decent general agreement showing a frontal
boundary lifting north toward the PAH forecast area late Wednesday
into Thursday. This will give us increasing clouds by Wednesday
night, with chances of light showers spreading from southeast to
northwest across our region Thursday. The front will continue to
lift north Thursday night, and warm air advection shower coverage
will increase. Went with slight to low chance pops Thursday,
increasing to high chance to likely pops Thursday night, with the
best chances in our southeast counties.
.LONG TERM...(Friday through Tuesday)
Issued at 225 PM CST Tue Nov 27 2018
A relatively mild and active period of weather is expected Friday
through Tuesday. A major storm system will push eastward into the
Plains Friday and then pivot northeast toward the Upper Midwest
Friday night and Saturday. At the surface a weak warm front will be
strung out west to east near our southern border early Friday. As
the tail end of the upper-level storm system pivots through our
area, the warm front will sharpen up and lift rapidly northward
through the region Friday night.
Massive warm, moist advection with widespread showers and some
scattered thunderstorms will accompany the warm front through the
area Friday night. The 12Z GFS indicates precipitable water values
up to 1.5" which is above the climatological max for this time of
year. Although we will see some locally heavy rainfall, the duration
is likely only to be an hour or two, so major flooding issues are
not expected, and the storm total QPF, 1-1.7", is down a bit from
this time yesterday. The convection is expected to lift north and
east of the area by early Saturday, and the trailing pseudo-cold
front is expected to be dry as it moves east through the region
later Saturday afternoon and evening.
Wind fields will be very strong, but mostly meridional which is
typically more of a heavy rain concern for our area. Instability may
be based just above the surface which may further limit any strong
to severe storm potential. However, we will have to watch any storms
near the warm front with the backed surface flow for some supercell
structures with a damaging wind and tornado threat. Will keep with
the general treatment in the current HWO for now.
The medium range models are in slightly better agreement with the
forecast features beyond Saturday. Much of the country including our
area will remain in southwest flow, as more energy drops into the
southwest by 12Z Sunday. The models differ on the extent of ridging
along the east coast, which will impact the progress of the Saturday
system moving eastward. However, it should be far enough north that
it will not have an impact on us beyond Saturday morning.
Saturday night and Sunday will be dry, but low-level warm, moist
advection will bring more showers northward into the region Sunday
night into Monday. There is a reasonable signal for more widespread
showers late Monday and Monday night as a portion of the southwest
upper-level trough ejects northeast through the Plains. Cannot rule
out a rumble of thunder over west Kentucky, but will leave it out
for now. Tuesday should be dry, but if the Monday night system slows
down any at all, showers could linger into Tuesday, especially in
the east.
Temperatures will start off very mild Friday and Saturday and then
gradually drop to near normal levels by Monday. We may finally get
some fresh cool air into the area on Tuesday.
&&
.AVIATION...
Issued at 511 PM CST Tue Nov 27 2018
Low clouds hanging tough KEVV/KOWB...will continue with MVFR bases
this evening...and temporary -SN at KOWB. Overnight, will see
these clouds move out, as High pressure moves in. Then warm
advection mid and high cover advances tmrw as the High shifts
southeastward, but cigs remain VFR thru the course of the day.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...None.
MO...None.
IN...None.
KY...None.
&&
$$
Area Forecast Discussion
National Weather Service Blacksburg VA
755 PM EST Tue Nov 27 2018
.SYNOPSIS...
Persistent northwest flow will prevail across the region overnight
as another strong upper disturbance crosses the area by early
Wednesday. High pressure builds in from the west Wednesday
afternoon and lingers into Thursday. Another weak storm system
arrives Thursday night into Friday followed by a stronger cold
front over the weekend.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
As of 755 PM EST Tuesday...
Adjusted POPs this evening to better reflect current radar
trends and trended towards a blend of HRRR and HiResW-ARW-East
for tonight into Wednesday morning. A shortwave rotating around
the upper trough will enhance the snow showers and snow flurries
tonight in the western mountains. Modified temperatures with the
latest surface obs, their trends and shaped towards GLAMP.
As of 625 PM EST Tuesday...
Made some minor adjustments in temperatures and dew points for
this evening into tonight. More changes later this evening.
As of 210 PM EST Tuesday...
Wintry weather to continue over the next 24 hours as the deep upper
trough spins east with a couple embedded strong shortwaves dropping
through the region by this evening and again later tonight. These
features should act to enhance upslope snowfall early on with the main
lift, while moisture is deepest, around midnight into the early morning
hours as the main wave aloft passes. Expect snow showers to gradually
become more banded later tonight into early Wednesday as moisture
decreases, but also when the coldest air aloft arrives within weak
instability and more uniform northwest flow. Also higher ratios given
the colder/drier air may support more accumulation espcly along the
western spine of the mountains now that things are much colder,
primarily from around BLF north into western Greenbrier where 2-3
inches or so could occur. Therefore upped western pops overnight and
boosted amounts with snow showers possibly making it out and across the
Blue Ridge overnight given the deep/strong northwest trajectory.
Otherwise typical split from clouds west to mainly clear east.
Strong winds and the cold the main concerns as strong cold advection
arrives under the core of the upper trough by morning allowing 850 mb
temps to fall to as cold as -15C over the mountains. This along with a
40-45 kt jet during the favored nocturnal hours when the inversion is
lowering due to the cold air supports wind advisory levels along the
ridges into Wednesday morning. However still some concern given clouds
and only weak subsidence as the colder air only bleeds in, that models
may again be overdone. Therefore confining the wind advisory headline
to only the Blue Ridge at this point. Will also leave the going wind
chill advisory where ongoing despite the latest guidance trends to stay
a bit warmer under clouds and mixing. Still potential for the highest
elevations to see brief wind chill criteria outside of the current
headline locations but too isolated to include at this point. Thus plan
to roll the wind advisory winds into the going wind chill advisory over
the southwest and snowfall over the northwest, while issuing a
separate NPW for winds elsewhere outside of the going
headlines. Otherwise lows in the teens mountains to low/mid 20s
east.
Low level moisture to decrease on Wednesday as high pressure builds in
and subsidence wins out from aloft allowing for the column to quickly
dry from the top per latest forecast soundings. This supports
increasing sunshine west by midday as high pressure builds east with
things becoming mainly sunny in the afternoon, except perhaps across
the far northwest where lower clouds may linger a while longer. However
will stay quite cold given only slow moderation aloft and continued
northwest flow with highs likely staying below freezing far west espcly
where there will be some snow cover. Elsewhere looking at mid/upper 30s
Blue Ridge to perhaps a few lower 40s in the piedmont but under
diminishing winds.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
As of 300 PM EST Tuesday...
The upper pattern will be transitioning to a progressive, zonal regime
with high pressure at the surface sliding through the southeastern US
and eventually off the Atlantic coast. This will allow for a brief
break of fair weather Wednesday night and Thursday before isentropic
lift associated with a warm front brings precipitation back to the
Appalachians and central mid Atlantic region later Thursday night.
While guidance has come in a bit warmer, thermal profiles shown on
Bufkit still indicate there may be some colder air right at the surface
as precipitation moves in with the potential for some freezing rain
generally north of Interstate 64. With the surface high off to our
southeast there may be some in-situ damming but the high will not be in
a good position to keep cold air entrenched for a prolonged period.
Expect any freezing rain will transition to plain rain by Friday
morning after a thin glaze of ice.
Most of the precipitation on Friday looks to be confined to locations
from the mountains of NC, up through the Grayson Highlands, then
continuing across locations along and north of Route 460. There will be
a bit of a decrease in chances of precipitation for a period Friday
night but the progressive pattern will have the next system on our
doorstep by daybreak Saturday.
Temperatures will be below normal through the end of the week, with a
bit of moderation heading into the weekend.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
As of 200 PM EST Tuesday...
An upper trof moving through the mid west will drive a deep low from
the Rockies into the Great Lakes region this weekend. This will push a
warm front into the area on Saturday followed by a cold/occluded front
Saturday night. This will bring a good chance of rain to the area
through Saturday night, followed by a gradual transition to upslope
showers west of the Blue Ridge later on Sunday.
There is some divergence in guidance through early next week, but there
appears to be a consensus for a deep low moving into the Great Lakes
pushing a strong cold front through the region on Tuesday. Overall
expect unsettled conditions to prevail with an eye to a substantial
frontal passage on Tuesday.
Temperatures generally appear warm enough to preclude any wintry
weather into the first part of next week, with readings at or above
normal through the period.
&&
.AVIATION /01Z WEDNESDAY THROUGH SUNDAY/...
As of 630 PM EST Tuesday...
MVFR/IFR cigs will continue in the mountains of West Virginia
and southwest Virginia and North West North Carolina tonight.
While in the east, VFR conditions will prevail tonight into
Wednesday.
As the next disturbance pushes in tonight, snow showers and
flurries will again increase and cigs will drop to MVFR/IFR in
the mountains with mainly VFR east. Visibilities are expected
to stay VFR most of the time, with intervals of MVFR to IFR
possible if bands develop along the KBLF-KLWB corridor. Some of
these narrow bands may also sneak farther east, possibly
affecting KBCB overnight into very early Wednesday.
Gusty Northwest winds will hinder aviation operations tonight
into Wednesday. Stronger wind gusts this evening into overnight
will be at KROA/KBCB where they may exceed 35kts. The strongest
winds will occur in the higher elevations.
High pressure builds in on Wednesday with northwest winds slowly
diminishing by the afternoon. Lingering snow showers should
also decrease with any residual lower ceilings also improving to
VFR outside of KBLF/KLWB where may take until early/mid
afternoon for skies to clear.
Medium confidence in ceilings,visibilities and winds during the
period.
Extended Aviation Discussion...
VFR conditions are expected briefly Thursday before another
weather system with sub-VFR cigs/vsbys moves back into the area
by the end of the week. This looks to bring periods of sub-VFR
Friday with more widespread MVFR to IFR ceilings and vsbys
Saturday within showers/low clouds ahead of a cold front.
Gradual improvement to VFR may occur Sunday behind the front
except across the mountains where northwest flow could keep
sub-VFR ceilings in place.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...Wind Advisory until noon EST Wednesday for VAZ009>014-016>020-
022>024.
Wind Chill Advisory until 8 AM EST Wednesday for VAZ015.
NC...Wind Advisory until noon EST Wednesday for NCZ002.
Wind Chill Advisory until 8 AM EST Wednesday for NCZ001-018.
WV...Wind Chill Advisory until 10 AM EST Wednesday for WVZ508.
&&
$$
SYNOPSIS...JH
NEAR TERM...JH/KK
SHORT TERM...MBS
LONG TERM...MBS
AVIATION...JH/KK