Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/20/16

Area Forecast Discussion

National Weather Service Bismarck ND

947 PM CST Sat Nov 19 2016

.UPDATE...
Issued at 944 PM CST Sat Nov 19 2016

Starting to see low clouds develop in the satellite fog channel
from western Sioux county northwest to near Dickinson. Dickinson
ASOS has 9 hundred scattered clouds at 940 PM CST. With low level
upslope flow should see clouds and areas of fog continue to form
southwest and south central. Will refine teh fog and sky grids to
follow the latest trends.

UPDATE Issued at 639 PM CST Sat Nov 19 2016

Current forecast trending well with no major updates.

.SHORT TERM...(This evening through Sunday)
Issued at 223 PM CST Sat Nov 19 2016

The main concern in the short term period will be stratus and fog
potential tonight into Sunday. Surface high pressure was in
control of the region`s weather this afternoon. The high will
gradually shift east tonight with low level south to southeast
flow taking hold. The latest short term models suggest some
potential for stratus and fog development tonight into Sunday,
especially across parts of western North Dakota. The HRRR has been
fairly consistent with this from run to run, and have opted to add
patchy fog for tonight. The HRRR suggests visibilities could drop
to well below 1 mile, so this will be something for later shifts
to monitor.

The low clouds and fog should diminish on Sunday, though NAM BUFR
soundings suggest the clouds could be slow to erode, especially
from central North Dakota towards the James River Valley. The
clouds could also have some impact on temperatures if they are
slow to leave. For now, have gone with highs from the lower 30s
east, to the 40s west.

Another potential concern for tonight is a weak upper wave moving
across southern Canada. Some of the short term models hint at the
potential for light precipitation, but for now did not add into
the forecast with not enough consensus amongst the models.

.LONG TERM...(Sunday night through Saturday)
Issued at 223 PM CST Sat Nov 19 2016

The primary concern in the long term period will be the passage
of an upper trough early next week. The 12z global suite continues
to advertise this system, but there remains some disagreement in
the details. Will center the best precipitation chances from
Monday night into Tuesday which seems to line up with most
guidance. Precipitation type remains a potential concern with
thermal profiles suggesting warm enough air aloft for a potential
wintry mix to start. There are also some signs wet-bulb effects
could also play a role as the precipitation begins. Snow ratios
remain low through the event which could help limit snow amounts.

.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 639 PM CST Sat Nov 19 2016

Short range models show some low stratus and fog formation across
western and south central North Dakota after midnight tonight.
Latest models have the best fog between Bismarck, Dickinson and
Williston. Expect IFR at KDIK between 10-15z but enough
uncertainty at KBIS and KISN to not include at this time.
Otherwise VFR at all TAF locations.

.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

UPDATE...WAA
SHORT TERM...CK
LONG TERM...CK
AVIATION...WAA

AREA FORECAST DISCUSSION

National Weather Service Eureka CA

336 PM PST Sat Nov 19 2016

.SYNOPSIS...
Showers will continue to develop through Sunday evening, with
isolated thunderstorms also possible along the Redwood coast
tonight, and area-wide Sunday afternoon and evening. Small hail may
accompany the stronger showers or thunderstorms. Showers may persist
through late Monday morning, before a brief dry period of dry air
returns to the region for Monday evening through early Tuesday
morning. Another weather system will bring more widespread rainfall
for the remainder of next week, with snow levels decreasing once
again.

.DISCUSSION...
As an upper trough crosses the region, mid-level lapse rates will
continue to gradually increase through Sunday evening. A few
thunderstorms have been developing over the last few hours, and this
should continue through sunset, or perhaps an hour or two after
that. with freezing levels currently running around 6700 feet, any
shower or thunderstorm of moderate intensity may produce small hail,
as was observed here at the office today around noon.

The better chance for any thunderstorm development will be Sunday
afternoon. During this time, the base of the trough will be
overhead. Diurnal heating (aided by any breaks in the cloud cover)
will be instrumental in increasing updraft potential. Should a
decent updraft get going, the colder air aloft will steepen the mid-
level lapse rates to the 7.5 to 8 deg. C/km range, with total totals
near 60 and lifted indices of -2 (possibly lower), and both SBCAPE
rising above 500 J/kg. For now and after coordinating with the
Medford Forecast Office, thunder mention was confined to locations
along and south of highway 36, where higher confidence in breaks in
the cloud cover reside. Depending on later model runs, this may need
to be expanded area-wide with the afternoon forecast package today.
As our weekend system departs the region, dry advection will
temporarily put the ki-bosh to any rainfall potential. This will be
short-lived though, as the mid afternoon Monday through early
(perhaps mid) morning Tuesday time frame looking to be when this
will occur.

Another strong storm system will start to impact our weather by late
Tuesday morning, as a cold front associated with another incoming
trough and area of low pressure takes aim on the state. Widespread
rainfall will once again develop along and behind this front. This
system is forecast to have much colder air aloft compared to this
weekend`s system, with snow levels forecast to drop to near 4000
feet. In fact, a good majority of the models show these levels being
too high, and it`s possible they may end up about a thousand feet
lower, which is what some of them indicate. However, given their
over-aggression with today`s system and considering this is still
several days out, we didn`t want to go that low just yet. Another
thing we`ll be watching is, if the current parameters end up
verifying, thunderstorm potential will be higher than this weekend,
which could make things a little more interesting. /PD

.AVIATION...
As forecast by the HRRR model, rains became more
widespread along the Redwood Coast earlier today. This rain shield
has spread farther inland since then, although scattered showers
continue to parallel the coast over KACV and just E of KCEC. Models
prog the overall break in the weather to continue over the next 3 to
6 hours with rains expanding again along the coast thereafter. Winds
along the coast will gradually lessen overnight, but gusts to at
least 20 knots remain possible thru much of the day Sunday. Isolated
thunderstorms remain possible offshore thru the night, and a few of
these make make landfall near the coastal TAF sites before
weakening. At KUKI, generally light, isolated to scattered showers
will continue. More widespread showers may return by morning. Winds
at KUKI will be generally light, although some gusts to 20 knots are
possible in heavier showers thru morning. /SEC/TA

.MARINE...
Elevated winds and large steep seas will continue through
the evening as the storm system tracks to the east. Conditions will
start to improve on Sunday as high pressure builds in and weakens
the pressure gradient across the coastal waters. This will allow
winds to decrease substantially on Sunday and then remain light to
moderate through early next week. Additionally, the steep wind
driven waves will begin to settle. The large west swell that has
brought 16 to 18 ft seas to the region will gradually diminish over
the next several days. The lower marine conditions will be
shortlived as another large swell is forecast to bring large seas
for the second half of next week. Otherwise, small craft advisories
replaced gale warnings for the southern waters today. The gale
warning for the northern outer waters continues through 8Z while the
northern inner waters maintains a hazardous seas warning. Small
craft advisories continue for the southern outer waters as planned.
/KML/KAR

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...None.
NORTHWEST CALIFORNIA COASTAL WATERS...Hazardous Seas Warning until midnight PST tonight for PZZ450.

Gale Warning until midnight PST tonight for PZZ470.

Small Craft Advisory until 9 PM PST Sunday for PZZ455-475.

Visit us at http://www.weather.gov/eureka

For forecast zone information
see the forecast zone map online:
http://www.weather.gov/eureka/zonemap.png

Area Forecast Discussion

National Weather Service Greenville-Spartanburg SC

1022 PM EST Sat Nov 19 2016

.SYNOPSIS...
In the wake of a strong cold front, much colder temperatures and windy
conditions will overspread the area this evening. At the same time, dry
high pressure will move into the region and persist into midweek. Another
fast moving cold front will move over the area early Thursday.

.NEAR TERM /THROUGH SUNDAY/...
As of 1000 PM EST...The axis of a sharp and deep upper trough is now
just off the Atlantic coast, and will shift east and close off into
an upper low over southern New England tonight into Sunday. Cold
front has already departed the CWFA and is pushing into the
Lowcountry. Behind the front, dry air and strong low-level CAA
continues. Winds have mostly calmed across the Piedmont, but are
still quite gusty in the high terrain. Another shot of moisture is
moving thru East TN into the mountains, but it is moving across very
dry soils, so it appears unlikely to have a great impact. Nakaya IR
curve does indicate clouds are cold enough to support snow. Still
cannot rule out a few flurries or isolated snow shower between
now and 1-2 AM, but no accums are expected.

Tonight, the NAM and GFS both show a mountain-wave signature on
cross-sections this evening, as strong deep-layer NWLY flow passes
over the southern Appalachians. The GFS is a little stronger than
the NAM, with 50-55 kts at the top of the BL tonight. With one
model showing this, and the other more subdued, that put me on
the fence, but figure it better safe than sorry. Hence High Wind
Warning for the northern mtns. The other concern overnight will be
freezing temps in the Upstate and NE GA, where they haven`t had a
freeze yet this fall. The midnight shift issued a Freeze Warning
for all these zones, and that still looks good.

Sunday, high pressure will slide into the MS Valley, while low
pressure occludes over the Northeast states. The pressure gradient
should relax and llvl winds and CAA should subside somewhat. It
still looks like a breezy day for most of the area, with winds still
approaching wind advisory criteria in the central and northern
NC mountains. Dry conditions will result in critical RH for fire
wx concerns (see Fire Wx section below). But winds will not be as
strong. High temps will be about 8-12 degrees below normal under
full sun.

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
As of 200 PM EST Saturday: Very quiet through the short term with
mainly a fire weather forecast (see discussion below) with a very
dry airmass in place in the wake of today`s front. We`ll be in
northwest flow aloft to start the period as the deep closed upper
low over New England continues to lift north, with ridging in the
center of the country sliding east with the progression of the
wavetrain. Cold Canadian surface high pressure will continue to
build in at the surface from the north with temperatures a handful
of degrees below seasonal normals for highs Monday, after starting
out over 10 degrees colder than normal for lows Monday morning (the
whole area should see another solid freeze but with the freeze
expected tonight, it should shut everything off so the frost/freeze
program will be done for the year...finally). Winds will also
decrease as we move through the period with the reduction in the
pressure gradient. Should see slightly warmer temperatures Monday
night and Tuesday (lows still well below normal, highs a couple of
degrees below), but with a slow warming trend as the surface high
modifies and thicknesses begin to increase as the upper ridge moves
in.

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
As of 245 PM EST Saturday: As the short term upper ridge slides
east, a high-amplitude wave will push off the Rockies but begin to
damp as it lifts northeast into the northern Plains. With it will
come a cold front, sweeping across the central portions of the
country and approaching the Appalachians toward Thanksgiving.
However, as has been the case with every front the past few weeks,
this one is another teaser (kind of a sick sense of humor there) and
new guidance continues to take the stronger dynamics farther north
and leave us with a pitiful-looking front that gets torn apart by
the Southern Appalachians. Of the operational guidance, the GFS is
the "wettest" (it`s all relative, even then it has no more than
1/3") with a slug of moisture that slides up into the southern
mountains Wednesday night, and then dries us up on Thanksgiving Day.
The ECMWF remains a bit slower and is drier, but in the end they`re
all just about equally as depressing.

Temperatures will be on a slow increase to a few degrees above
normal by the time Thanksgiving rolls around, then the front will
knock us back down again, but overall not a lot of change through
the period.

Very very late in the period another upper low will dive into the
mid Mississippi Valley and push east towards our area. Of the long-
range operational models, the GFS gives us some hope, but the 12z
ECMWF trickling in yanks that hope away and has come in much drier.
For now, have sided with the blend bringing in slight chance pops
but wouldn`t be surprised to see downward adjustment with time.

.AVIATION /04Z SUNDAY THROUGH THURSDAY/...
At KCLT and Elsewhere...Gusty northwesterly winds in the wake of a
cold front are beginning to subside across the Piedmont now that the
sun has set, but low-level profiles from NAM and HRRR indicate the
inversion will take some time to develop, given brisk cold advection
occurring aloft. Thus the gusts have been maintained for a few hrs
at the start of the period at all Piedmont sites except KGMU. KAVL
is exposed to stronger CAA as well as channeling up the valley,
and it still appears they will see gusts throughout the period,
slacking off a bit Sunday afternoon. The winds and increasingly
drier air pushing into the region overnight will preclude fog or cig
formation, and continue to keep smoke dispersed. Hence the forecast
is all VFR. Winds will briefly turn WSW across parts of the Piedmont
(including KCLT) near daybreak as the lee trough peaks in magnitude.

Outlook: High pressure prevails into the coming week, with fire
wx conditions worsening as cold and dry Canadian air settles
over the region and keeps humidity exceptionally low for several
days. Gusty NW winds will continue Saturday night, and resume
across the Piedmont (though not as strong at Saturday) by midday
Sunday. With high pressure returning late Sunday thru the middle
of next week, smoke concentrations across the region will remain
a concern, especially during nights, when vsbys fall into the MVFR
range in some spots as the boundary layer decouples.

Confidence Table...

03-09Z 09-15Z 15-21Z 21-00Z
KCLT High 100% High 100% High 100% High 100%
KGSP High 100% High 100% High 100% High 100%
KAVL High 100% High 100% High 100% High 100%
KHKY High 100% High 100% High 100% High 100%
KGMU High 100% High 100% High 100% High 100%
KAND High 100% High 100% High 100% High 100%

The percentage reflects the number of guidance members agreeing
with the scheduled TAF issuance flight rule category. Complete hourly
experimental aviation forecast consistency tables and ensemble forecasts
are available at the following link:

www.weather.gov/gsp/aviation

.FIRE WEATHER...
A Red Flag Warning remains in effect thru midnight for the NC
Mountains where winds are gustiest and dewpoints lowest. A Fire
Danger Statement will continue across the remainder of the area
through Sunday.

The cold front currently crossing the region has swing winds
around to the NW and have picked up sharply, with gusts of 25 to
40 mph across much of the area where a Wind Advisory remains in
effect. The northern mountains may see gusts up to 60 mph where
a High Wind Warning has been posted.

Very dry high pressure building into the area early in the week will
result in very low afternoon RH Sunday through at least Tuesday.
Meanwhile, winds will remain gusty across the mtns through part
of the day Sunday. While the current forecast does not feature an
overlap between RFW criteria winds and RH, it will be close and
will need to be reevaluated overnight in case the pressure gradient
results in wind gusts hanging on longer than currently anticipated.
The Fire Danger Statement will continue across the entire area
through Sunday and may need to be upgraded to a Red Flag Warning
if conditions warrant.

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...Fire Danger Statement through Sunday evening for GAZ010-017-
018-026-028-029.
Freeze Warning until 9 AM EST Sunday for GAZ018-026-028-029.
NC...High Wind Warning until 7 PM EST Sunday for NCZ033-049-050-501-
503-505.
Red Flag Warning until midnight EST tonight for NCZ033-048>053-
058-059-062>065-303-501>510.
Fire Danger Statement through Sunday evening for NCZ033-
048>053-058-059-062>065-501>510.
Fire Danger Statement through Sunday evening for NCZ035>037-
056-057-068>072-082.
Freeze Warning until 9 AM EST Sunday for NCZ082.
Wind Advisory until 7 PM EST Sunday for NCZ048-052-053-064-065-
507-509.
SC...Fire Danger Statement through Sunday evening for SCZ001>014-
019.
Freeze Warning until 9 AM EST Sunday for SCZ004>014-019.

$$
SYNOPSIS...JPT
NEAR TERM...ARK/Wimberley
SHORT TERM...TDP
LONG TERM...TDP
AVIATION...Wimberley
FIRE WEATHER...TDP/Wimberley

Area Forecast Discussion

National Weather Service Chicago/Romeoville, IL

549 PM CST Sat Nov 19 2016

.SHORT TERM...
152 PM CST

Through Sunday night...

Winter is making a brief though abrupt appearance here across the
region in wake of the first real storm system of the season. While
winter precipitation impacts were low with this one, today is our
first day of below normal highs in quite some time with readings
holding in the 30s and wind chills in the 20s.

The strong low will continue northeast through Quebec tonight and
the high pressure ridge across the plains will also edge closer to
the area tonight. This will maintain northwest winds across the
area though with a gradual decaying trend. Rap lower level
moisture progs suggest a quick clearing to the cloud deck later
this afternoon and evening. This should set up a colder night area
wide, with upper teens to lower 20s common and near single digit
wind chill readings. Evening wind chills fall into the teens to
low 20s.

The surface high will move overhead tomorrow afternoon, providing
for plentiful sunshine in spite of some passing higher clouds,
along with much lighter winds. While highs will be similar to
today, the light winds and sunshine will make it feel quite a bit
better. One more cold night is in store for Sunday night as high
pressure remains in place.

KMD

.LONG TERM...
152 PM CST

Monday through Friday...

The coming holiday week will start off with dry and seasonal
conditions (mid to upper 40s) as an upper level ridge moves
overhead. Light winds will become easterly as low pressure
organizes in the southern Rockies in response to a southern stream
trough axis.

Tuesday/Wednesday appears to be the most active portion of the
extended period. The broad upper trough will eject out of the
Rockies on Tuesday and then slowly progress east through the
midwest on Wednesday. Several guidance sources bring a weak wave
through ahead of the trough late Monday night into Tuesday but
keep it dry. If any wet bulbing were to occur or forcing stronger
there could be some light mixed precipitation initially, and the
GFS is a bit more aggressive with the low level warm advection
ahead of this system, depicting surface wet bulb temps just below
freezing and actual surface temps close to freezing. At this
point will stick closer to the full suite of models given the
antecedent dry conditions and precipitation likely being lost to
evaporation, plus this suite still largely maintains a drier
solution for Tuesday morning. Feel confident in breezy southeast
winds developing Tuesday as this trough organizes a surface low in
the central/southern plains.

Better combined forcing and moisture arrives later Tuesday into
Wednesday which looks to be a wet period as the surface and upper
lows move overhead and get seasonally elevated precipitable water
values advected in on a modest low level jet, so expect wet roads
for the busy travel day.

The low will pull away Wednesday night, with some wrap around
precipitation expected to largely remain liquid. This will also
make way for dry conditions and once again seasonal temperatures
for the Thanksgiving Holiday. A progressive upper level pattern
remains in place for Thursday night/Friday as a shortwave moves
through, but some significant differences in extended guidance
regarding the track of the corresponding low and surface
temperatures during the period of interest. Fortunately precip
looks on the lighter side.

KMD

.AVIATION...
For the 00Z TAFs...

VFR conditions expected through the TAF cycle. SCT V BKN100-150
expected Sunday but with little to no impact on operations.

Izzi

.MARINE...
240 PM CST

Low pressure continues to pull off to the northeast this afternoon
as high pressure builds across the plains and midwest. A strong
pressure gradient still exists between these two features with
solid gales across the south half of Lake Michigan and 10-13 ft
waves. Several observations across the northern tier of the lake
are also near storm force (along the shore, so likely higher
across the open waters), and this supports no immmediate change to
current headlines across Lake Michigan quite yet. Once storm force
winds ease across the north, it is likely gales will continue for
at least another 6 hours if not a bit longer, with gales finally
easing Sunday morning. Winds do weaken more Sunday afternoon but
waves will take a bit longer to subside. High pressure will
translate over the lake Sunday night and Monday.

Another weaker low will take aim at the southern tip of Lake
Michigan Wednesday, with breezy southeast winds ahead of the low
expected Tuesday and Tuesday night. Winds look to remain below
gale levels, but this will build waves across the west side of
the lake.

KMD

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...Gale Warning...NEARSHORE WATERS UNTIL
MIDNIGHT Sunday.

Gale Warning...LMZ777-LMZ779 UNTIL 9 AM Sunday.

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
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WWW.YOUTUBE.COM/NWSCHICAGO

Area Forecast Discussion

National Weather Service Marquette MI

630 PM EST Sat Nov 19 2016

.SHORT TERM...(This evening through Sunday)
Issued at 425 PM EST SAT NOV 19 2016

Water vapor imagery and RAP analysis show a sharp mid/upper level
trof over the Great Lakes. Lingering deep layer forcing associated
with the trof is still over eastern Lake Superior. Combined with
850mb temps around -12C, lake enhanced snow is ongoing into the e
half of the fcst area. To the w, subsidence and much drier air noted
on the 12z CYPL sounding and in particular the 12z KINL sounding
along with inversion down around 850mb have strongly limited LES
today off western Lake Superior. Combined with the strong winds,
there has not really been much in the way of shsn activity until
well inland from the lake where orographic lift becomes sufficient.

With inversion steady around 4kft over the w tonight, not expecting
anything more than sct -shsn into the western fcst area. Coverage
may increase a bit during the night as nocturnal cooling around the
lake and increasing land breeze component to wind increase low-level
convergence. However, any additional snow accumulations should only
be an inch or less. To the e, lingering deep layer forcing pulls out
this evening and is replaced by strong deep layer qvector
divergence/subsidence with inversion falling to around 5kft. So, the
current widespread lake enhanced snow over the e will evolve into a
more typical multi-band les scenario by late evening. After this
occurs, the main point of interest will be banding connected to Lake
Nipigon preconditioning. Should see a dominant band set up into
western Alger County tonight. High res model output is all fairly
well clustered on this scenario with all also showing this band
drifting w into Marquette county during the night into Sun morning
though with different timing. Depending on how quickly the band
shifts and how organized it becomes, it could produce a few inches
of snow accumulation in a short period of time. Will be something to
monitor. As for headlines, all headlines w of Marquette/Delta
counties have been dropped. Maintained ongoing headlines elsewhere
with the exception of dropping Marquette to winter wx advy.
Nighttime snow accumulations should be on the order of 1 to 4 inches
in the headline areas, with perhaps as much as 5 inches in far
western Alger County associated with aforementioned band that
develops from Lake Nipigon preconditioning. Winds will continue to
diminish.

Light les will continue on Sun, but will slowly diminish from w to e
during the day. There may be some locally mdt/hvy snow in eastern
Marquette county in the morning as discussed above.

.LONG TERM...(Sunday night through Saturday)
Issued at 316 PM EST SAT NOV 19 2016

Only significant weather in the long term is mid-week with potential
for advisory (or possibly low end warning) level snow.

An upper trough is modeled to move through the area mid-week,
bringing a 1007mb SFC low from southern WI through central lower MI
Wed and Wed night. Widespread precip may move into the W or SW by
late Wednesday, and the bulk move out by Wed night. Models are in
good agreement overall, but the GFS has the most QPF at up to 0.75"
while the ECMWF only has up to around a half inch. Most of the
precip falls as snow, with the exception possibly of the south-
central where a transition to rain is more likely. If the events
plays out as currently modeled, winter weather advisories would be
needed over a good portion of the area, with potential for some
warning amounts if the GFS amounts verify. For now, given the
inherent uncertainty at that time frame with this type of system,
will just mention of the HWO. Definitely will have to keep a close
eye on the system given the high-impact travel day.

Lighter snow is possible Thursday and Friday, but certainly not
looking at any significant amounts right now.
&&

.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 630 PM EST SAT NOV 19 2016

In the wake of the strong storm system that has moved across the
Upper Great Lakes, cold air mass will generate lake effect shsn
for another 12 hours or so with MVFR conditions generally prevailing
at KIWD/KCMX/KSAW. Influx of drier air this evening will result in
diminishing shsn with time so that periods without shsn become more
frequent and longer duration. Meanwhile, the strong/gusty winds will
gradually diminish from w to e overnight tonight into Sunday.
&&

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 425 PM EST SAT NOV 19 2016

As pres gradient weakens as low pres moves farther away and high
pres ridge approaches, ongoing gales over central and eastern Lake
Superior will end tonight. While the high pres ridge and light winds
will reach western Lake Superior Sun aftn, the ridge won`t reach
eastern Lake Superior until Mon night. As a result, winds on eastern
Lake Superior will remain in the 20-30kt range during Sun and won`t
fall blo 20kt until later Sun night/Mon. Winds will increase across
the lake later Tue into Wed as the next low pres system moves into
the Great Lakes region. The strongest winds, 20-30kt, will occur
over central and eastern Lake Superior on Wed.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
Winter Weather Advisory until 1 AM EST Sunday for MIZ005-013-014-
085.

Coastal Flood Warning until 1 AM EST Sunday for MIZ006-007.

Winter Storm Warning until 1 AM EST Sunday for MIZ006-007.

Coastal Flood Warning until 7 PM EST this evening for MIZ005.

Lake Superior...
Gale Warning until 4 AM EST Sunday for LSZ248>251-265>267.

Gale Warning until 1 AM EST Sunday for LSZ243>245-264.

Gale Warning until 7 PM EST /6 PM CST/ this evening for
LSZ240>242-246-247-263.

Lake Michigan...
Gale Warning until 4 AM EST Sunday for LMZ221-248-250.

SHORT TERM...Rolfson
LONG TERM...Titus
AVIATION...MZ
MARINE...Rolfson

Area Forecast Discussion

National Weather Service Charleston WV

652 PM EST Sat Nov 19 2016

.SYNOPSIS...
Upslope snow lingers into Sunday night in strong, cold northwest
flow. High pressure early next week. Another front mid week.

.NEAR TERM /THROUGH SUNDAY/...
As of 630 PM Saturday...Scattered snow showers will be pushing
through the region, mostly north of I64 over the next few hours.
Snow showers will likely become more persistent across the West
Virginia mountains after 00Z. Overall the forecast remains on
track and have decided to make no changes at this time.

As of 130 PM Saturday...

Winter making its first appearance this weekend, in the wake of a
strong cold front that whipped through the area this morning.
Large upper level short wave trough swinging through the area this
afternoon takes on a negative tilt tonight, and then closes off
over the northeast U.S. atop surface low pressure, as a stacked
system.

Strong cold advection west to northwest flow on the back side of
the system will continue to drive temperatures down. This will
transition wrap around rain showers over to snow showers from west
to east and high terrain to lower terrain by tonight, and then the
precipitation transitions into an upslope event tonight, as the
upper level trough axis pushes east of the area.

Upslope precipitation will be enhanced by plume off lake Michigan
across northern portion of forecast area, which may enhance
snowfall amounts in the northern mountains. This is already
reflected in the forecast, and overall no changes were needed to
the snow amounts. Have a borderline advisory event for snow,
along with a solid wind advisory event, for the higher terrain
portions of Randolph, Webster and Pocahontas counties. Wind gusts
may actually trough 50 kts across the very highest terrain
overnight tonight.

The upslope snow showers start to wane late Sunday, as approaching
high pressure starts to slacken the pressure gradient.

Temperatures similar to previous, fine tuned / updated via the
HRRR, RAP and NAM.

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
As of 145 PM Saturday...

Still a few light upslope snow showers lingering across the northern
mountains Sunday night, but overall, will be tapering off, as flow
starts to back and become less favorable, as high pressure gradually
builds into the region. Sunday night will continue to be cold, and
windy, with wind chills in the teens to single digits across the
higher terrain, particularly across eastern zones where tighter
pressure gradient will exist as high gradually tries to nudge east.
Dry, with gradually warming conditions Monday and Tuesday, as high
pressure surface and aloft continues to take hold.

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
As of 145 PM Saturday...

Clouds will be on the increase across the area on Tuesday, as a warm
frontal boundary lifts north across the region. Showers will
overspread the area again by Wednesday as low pressure, and
associated cold front approach from the west, but enough warm air
should be in place owing to strong southerly flow, that bulk of
precipitation will be in the form of rain. Another system approaches
the area next weekend. At this point, the exact track, and thus
precipitation type is very uncertain, but could be at least a light
snowfall for the higher terrain, along with the possibility for a
rain/snow mix at times across some lower elevation locations.

.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
As of 645 PM Saturday...

Strong west to northwest flow continues tonight, with scattered
snow showers mostly pushing across the northern locations. More
persistent snow will continue to develop in favorable upslope
areas in the mountains over the next few hours. Still expecting
gusts of 25 to 35 kts across the lowlands, and 30 to 40 kts in the
mountains. The winds will begin to ease up Sunday morning.

Mostly low end VFR to MVFR ceilings tonight across the lowlands
through Sunday morning. Snow showers will be least likely tonight
at HTS and CRW, so higher confidence that these sites will avoid
brief IFR conditions from snow showers. Latest radar indicates
scattered snow showers that will continue to cross from PKB to CKB
to EKN this evening. Based on upstream stations that these
showers passed over, there is a high possibility for brief IFR
visibilities to occur in these snow showers. Otherwise MVFR for
ceilings will prevail overnight. EKN will likely have the greatest
chance to have impacts from snow and also blowing snow with the
strong winds tonight. Confidence is growing that IFR conditions
will continue through the night at EKN within heavier snow
showers. A little less confident of IFR conditions at BKW, but in
heavier snow showers and strong winds causing blowing snow
conditions, it is very possible that they will be in and out of
IFR conditions for visibility as well.

FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z MONDAY...

FORECAST CONFIDENCE: Medium

ALTERNATE SCENARIOS: Ceilings and Visibilities will be highly
variable to timing and intensity of snow showers. The strong
gusty winds will fluctuate. Any accumulating snow in the mountains
will likely be picked up by the winds and further reduce
visibility.

EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.

DATE SUN
UTC 1HRLY 00 01 02 03 04 05 06 07 08 09 10 11
EST 1HRLY 19 20 21 22 23 00 01 02 03 04 05 06
CRW CONSISTENCY H H M M M M M M M M H L
HTS CONSISTENCY H H H H H H H H H H H M
BKW CONSISTENCY L L L L M M M M L L L L
EKN CONSISTENCY L L L L L L L L M M M L
PKB CONSISTENCY M M L M M M M M M H M M
CKB CONSISTENCY M M L M M H L M M H H L

AFTER 00Z MONDAY...
IFR possible within upslope snow showers into Sunday night across
the mountains.

.RLX WATCHES/WARNINGS/ADVISORIES...
WV...Winter Weather Advisory until 4 AM EST Monday for WVZ522-523-
526.
OH...None.
KY...None.
VA...None.

$$
SYNOPSIS...TRM/SL
NEAR TERM...TRM/MPK
SHORT TERM...SL
LONG TERM...SL
AVIATION...MPK

Area Forecast Discussion

National Weather Service Denver/Boulder CO

928 PM MST Sat Nov 19 2016

.UPDATE...
Issued at 928 PM MST Sat Nov 19 2016

Not much changes needed to the ongoing forecast. Adjusted current
sky cover for less amounts, then increased it through Sunday
afternoon when models are showing more coverage. Also adjusted
minimum temperatures tonight with slightly cooler temps along the
South Platte River Valley and slightly warmer temperatures along
the foothills where winds will remain elevated.

.SHORT TERM...(This evening through Sunday)
Issued at 219 PM MST Sat Nov 19 2016

Main issue to contend with tonight into Sunday will be a
developing mountain wave in the Front Range Mountains and
Foothills. The upper level ridge axis will be over central CO at
00z with a moderate westerly flow aloft. The mdls shift this axis
east overnight with a moderate west-southwesterly flow over CO.
The RAP and NAM12 mdls both indicate an amplified wave developing
after 03z, strongest at 12z Sunday, it then breaks down by 18z.
Lee side surface trough over eastern CO 06z to 12z then the
feature shifts further south by 18z, shifting the surface
pressure gradient In the mountains, winds around 650 mb at 40
kts, which appear to translate downslope in the foothills
overnight. It does not appear to be strong enough for highlights
but gusts in the 45-60 mph range more likely. Temperatures in and
near the foothills will also moderate with the gusty winds in
place overnight. On Sunday, better temperature recovery progged
for the Urban Corridor and Northeast Plains, but a lingering
snowfield should keep it a little cooler north and east of Akron.
In the mountains and foothills, stronger winds in the mountains
and foothills will decrease as the wave break down by Sunday
afternoon.

.LONG TERM...(Sunday night through Saturday)
Issued at 219 PM MST Sat Nov 19 2016

A southwest flow aloft will prevail over Colorado Sunday night as
an upper level trough moves across California. This trough will
move into the Desert southwest Monday. Moisture will increase
through the day. This combined with orographic lift and a jet
overhead, is expected to produce snow showers in the mountains.
Snow should become widespread over the mountains Monday night as
the trough moves across the Central Rockies. Precipitation will
then spread onto the Front Range and eastern plains through the
night. Temperatures look to be just warm enough for mainly rain
along the Front Range Urban Corridor. The upper level low/trough
and a surface low reform over western Kansas late Monday night.
Northerly winds on the back side of this system will help pull
cooler air into the area. This will likely cause the rain to
change to snow over the plains, especially where precipitation is
moderate to heavy.

Northwest flow behind the exiting trough will usher in colder
air. This cold air advection combined with a moist airmass is
expected to produce snow showers over the mountains most of
Tuesday. By Tuesday evening snow will be light and eventually end.
Rain/snow over the plains is expected to end Tuesday afternoon as
the trough exits the region.

A ridge in the westerly flow aloft will move across Colorado
Wednesday. Dry conditions will return to the area. Temperatures
will be cool with highs in the 40s. On the heels of this ridge, a
trough will race across Wyoming and northern Colorado Wednesday
night and early Thursday. Will have low pops in the mountains for
this system. For the Front Range and eastern plains, this will
likely bring dry and windy conditions.

A progressive westerly flow aloft will remain over the Central
Rockies Friday and Saturday. Temperatures will be near normal
under this pattern. The next wave is progged to affect the
mountains Friday night and early Saturday. Will have low pops in
the mountains for this system.

.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 928 PM MST Sat Nov 19 2016

VFR through the period with only high mountain wave clouds
expected. Southerly drainage winds are expected tonight at KDEN
and KAPA. Downslope winds are expected near the foothills
overnight, so could see a window of gusty westerly winds at KBJC
depending on how well the mountain wave forms. Light southeasterly
winds expected Sunday.

.BOU WATCHES/WARNINGS/ADVISORIES...
None.
&&

UPDATE...Kriederman
SHORT TERM...Cooper
LONG TERM...Meier
AVIATION...Cooper

Area Forecast Discussion

National Weather Service Key West FL

455 AM EST Sun Nov 20 2016

.DISCUSSION...In the middle and upper levels,(700-200 mb), latest
available IR satelitte imagery overlaid with model streamline
analysis as of 300 am, depict the main axis of a negatively tilted
polar trough oriented from east of Lake Superior southeast to east of
North Florida. Latest water vapor imagery delineates very dry air
within the middle and upper level deep cyclonic flow (on the
southwestern flank of this trough), that encompasses the Central and
Eastern Gulf of Mexico, the entire Florida Peninsula and the Florida
Keys, and the NW Bahamas.

At the surface and in the lower to middle levels, (Surface to 700
mb), latest available IR imagery overlaid with marine and land
surface observations and analysis detail the center of a large cool
and dry 1030 mb plus anticyclone located over the Arklatex region.
Closer to the Keys, a cold frontal system extends to across Florida
near Lake Ocheochobee from low pressure near Long Island, NY. As a
result, last evenings 00Z sounding at Key West illustrated a gentle
to moderate mainly north flow from the surface up to almost 400 mb,
a weak 2 degree C inversion from 850 to about 800 mb, within a dry
lower to mid column and total PWAT only at .77 inches.

.CURRENTLY...As of 300 am, temperatures across the island chain were
in the upper 60s to the lower 70s with dewpoints in the lower 60s.
Radar was devoid of any echoes attm. C-man stations along the Florida
Reef are recording north to north northeast winds at 15 to 20 knots
in Florida Bay, near 20 knots along the Florida Reef, and near 20
knots at Smith Shoal Light.

.SHORT TERM...Today through Thursday Night, The weak cold frontal
system now approaching the Keys has been consistently shown to bleed
out when it reaches our latitude this morning. Local winds are
already increasing. Very little moisture is available for any surface
convergence, with only a few specks indicated by the HRRR model
across waters just west of the Keys, so we will remain popless here.
Winds will increase up across all waters, even the Bay given the
shallow low level cold thickness advection, so SCAs have been
hoisted. Given that the shallows inside the five fathom line and the
Bay have already dropped into the lower 70s, will see slackening
breezes this afternoon across these waters, the Keys island chain
themselves, and even in Hawk Channel, though SCA advisories or
headlines will remain elsewhere.

The surface high over Arkansas will slowly migrate across the Lower
Mississippi and then Tennessee Valleys today through Tuesday, then
reaching the Carolina Coasts by Tuesday night and offshore into the
Western Atlantic Wednesday thru Thursday Night. As such winds will
remain in a north to northeasterly direction through Monday, then
north to northeast Monday and Monday night. Given the magnitude of
the gradient, breezy conditions will occur during the night and
morning periods with lulling likely in the afternoons given
insolation. Temperatures tonight and Monday Night should fall down to
between 60 and 65 degrees with dewpoints down into the lower to
middle 50s, possibly lower. Then hi and low temperatures return to
normal Tuesday through Thanksgiving night as northeast to east winds
across warmer waters allow daytime highs near 80 and lows near 70,
close to average for late November.

.LONG TERM...Friday and Saturday, Surface ridging appears to set up
across the Florida Peninsula but very dry air in the middle levels
associated 500 mb ridge over the Gulf with continue to disallow any
chances for measurable rainfall. And breezes will be gentle to
moderate, promoting better marine recreational opportunities this
holiday weekend.

.MARINE...SCA hoisted for all waters thru at least this morning. the
SCA may remain in place across Hawk Channel, the Florida Straits and
the offshore Gulf waters but its likely to be a SCEC for the
afternoon. For the density surge again tonight, SCEC conditions looks
likely everywhere including the shallow waters, with the possibility
of SCA conditions again across the Straits and Offshore Gulf waters,
as well as Hawk Channel. The same issue with SCEC conditions
appearing likely will also exist for Monday and Monday Night. The
gradient is progged to increase slightly for Tuesday thru Thursday
Night, so SCA conditions will be likely across the Florida Straits,
with SCEC conditions likely across the rest of the marine district,
with SCA conditions highly possible in Hawk Channel and the Offshore
Gulf waters. Thereafter, winds and seas may let down a bit for the
upcoming weekend.

.AVIATION...
Until 00z/21st, Vfr conditions will prevail at the Key West and
Marathon terminals with cloud bases at 020 and 050 this morning, with
clear skies thereafter. Mostly north winds of 10 to 15 knots will
gusts to between 18 and 23 knots can be expected through early
this afternoon, before slackening some this afternoon especially at
the Marathon airport.

.CLIMATE...
In 1959, the daily record rainfall of 7.71 inches was recorded in
Key West. Temperature records have been kept since 1872.

.KEY WATCHES/WARNINGS/ADVISORIES...
FL...None.
GM...Small Craft Advisory for GMZ031>035- 042>044-052>055-072>075.

Public/Marine/Fire...Futterman
Aviation/Nowcasts....APA

Visit us on the web at weather.gov/key

Area Forecast Discussion

National Weather Service Medford OR

1030 PM PST Sat Nov 19 2016

.Updated aviation and marine discussions.

.DISCUSSION...A wrapped up low pressure system over the Northeast
Pacific Waters is maintaining southwest flow over the forecast
area. Winds are peaking at the coast and south to north pressure
gradients will generally weaken overnight, meaning inland winds
should gradually diminish. The area where gusty winds will linger
longest will be east of the Cascades, where a wind advisory found
at NPW is valid through early Sunday morning.

Precipitation tonight will again focused over Curry and Siskiyou
Counties. We have increased precipitation amounts in Curry County
based on latest HRRR output. Snow levels have risen since last
night, and most snowfall should be at 5000 feet and higher tonight
in the Mount Shasta area, so little to no winter weather impacts
on travel are expected tonight.

Thunderstorms have been observed this afternoon and evening over the
coastal waters, and the instability that`s fueling these storms will
move just inland tomorrow afternoon, so lightning is possible in
portions of Western Josephine and Siskiyou Counties. Strong
thunderstorms are not out of the question for the coastal waters
and coast through tomorrow morning.

Even though some snow is expected in high elevations of Siskiyou
County and in the Cascades tomorrow, wind and winter weather impacts
are generally diminishing this evening, overnight, and tomorrow.

Please see the previous discussion below for more details on the
continued active weather pattern.

.AVIATION...20/00Z TAF cycle...Showers are affecting mostly the west
side this evening with thunderstorms remaining along the coast and
offshore. Conditions are generally VFR at all terminals, but
occasional MVFR conditions can be expected in any showers. Gusty
winds are also certainly possible in and near thunderstorms, but
general winds will decrease tonight. Showery weather is expected to
continue to be the case overnight with showers gradually spreading
to the east side as well where they may be mixed with snow late
tonight. -Wright

Note: The ceilometer at FAA site KOTH is out of service, so there
will be no ceiling observations available generally between the
hours of 04Z and 14Z.

.MARINE...Updated 1030 PM PST Saturday 19 November 2016...Gales
along with the associated very steep seas will continue into
tonight, then diminish as the low moves away. The only exception to
this is near Brookings where winds are lighter, but very steep fresh
swell keep conditions hazardous into tonight there as well. The
other hazard to watch out for over the waters is thunderstorm
potential. We are seeing isolated strikes now and have been all day,
and this potential will continue through the night and into Sunday
morning. The main concern with thunderstorms besides the lightning
is the potential for sudden increases in wind. We already have gales
going, but the added momentum from thunderstorms could push wind
gusts briefly into Storm force.

As low pressure moves away later tomorrow, winds will diminish,
however seas will remain elevated due to fresh swell. This break in
the winds continues Monday, but another front will bring south gales
and very steep seas Tuesday. The stormy pattern continues for the
foreseeable future with cold fronts roughly every other day all the
way into next weekend. In addition, this active storm track will
produce large, powerful swells at times, especially as we get into
later next week. -Wright/SK

.PREV DISCUSSION... /Issued 253 PM PST Sat Nov 19 2016/

SHORT TERM...A low pressure center is located off the Oregon
coast today and will gradually lift northeast tonight into Sunday.
As this low lifts northeast tonight into Sunday, it will bring a
surface trough into area. This will bring increasing showers
tonight, mainly to the coast and portions of Siskiyou County,
with increasing showers across all of the area on Sunday. Sunday
night, the upper level trough will move across the region with
some continued shower activity over the area. On Monday, expect
decreasing showers as models show the upper trough shifting
eastward. A brief period of dry weather is expected Monday evening
into Monday night as a shortwave ridge moves over the region.

Winds have decreased today but will remain strong and gusty over
the mountains east of the Cascades through late tonight and may
reach down to the valley locations in the Summer Lake area at
times. Other areas will see breezy to gusty south winds into
tonight.

Otherwise the main concern is with showers and potential for
thunderstorms. As this trough moves into the area expect
increasing instability and steepening lapse rates combined with a
jet aloft will bring a slight risk for thunderstorms with shower
activity this evening through Sunday. Isolated thunderstorms are
likely over the coastal waters this evening into Sunday. Also
there is a slight chance for thunderstorms and along the coast
this evening into Sunday and over inland areas of southwest Oregon
and western Siskiyou County during the day Sunday. Otherwise
expect increasing showers this evening and tonight with the focus
for shower activity along the coast and into Josephine and
Siskiyou counties. Showers are forecast to spread inland during
the day Sunday.

Snow levels are forecast to be near 5000 to 5500 feet through
Sunday, except locally down to 4500 feet this evening in the
Mount Shasta area of south central Siskiyou County. Light snow
accumulations are possible in the Mount Shasta area above 4500
feet elevation through this evening then expect snow levels to
rise slightly to 5000 feet. As showers increase in Siskiyou County
tonight into Sunday morning, additional moderate snow
accumulations are expected but mainly above 6000 feet elevation
with light snow down to 5000 feet. So have decided not to extend
the winter weather advisory for snow at this time.

With the upper level trough moving into place Sunday night,
expect continued scattered showers with the best chances for
showers over the coastal waters, coast and mountains. Instability
and a slight risk for thunderstorms may continue into Sunday
evening for portions of southwest Oregon, mainly near the coast,
and western Siskiyou County. Then instability and the risk for
thunderstorms will diminish late in the evening.

Light showers and snow showers will linger into Monday as a
shortwave moves through the area in a northwest flow, tapering
off late in the day as a shortwave ridge begins to move inland. The
ridge will move across the area Monday night with west side
valley low clouds and patchy fog. The break in the weather will be
short as another strong cold front is expected to reach the coast
Tuesday afternoon. With very good model agreement, the arrival of
the front was slowed by 3 to 6 hours compared to the inherited
forecast. The front will weaken as it moves inland Tuesday night
with light to moderate rain and snow. The snow level is forecast
to be around 4500 to 5000 feet during the evening then fall to
around 4000 feet overnight. Snowfall amounts of 2 to 5 inches
should be common over the Cascades with up to 3 inches on the east
side. Another weaker disturbance is expected to follow on
Wednesday with scattered light showers and snow showers and a snow
level around 3500 to 4000 feet. -DW

LONG TERM...Wednesday night through Saturday Night...The long term
continues the active weather pattern with the series of troughs
moving over the Pacific Northwest. Models agree that the
Thanksgiving holiday will be rather soggy for areas west of the
Cascades--especially along the coast. Have trended the previous
forecast with a blend of the ECMWF and the GFS.

Snow level forecasts have changed slightly with new guidance
agreeing quite well to bring down snow levels. Snow levels are now
forecast to be between 3500 to 4000 feet Wednesday night meaning
that the higher elevations across the Eastside as well as the
mountain passes, including Siskiyou Summit on Interstate 5; Lake of
the Woods Pass on the Oregon 140; and Black Butte Summit also on
Interstate 5 will have better chances for snow. Although it is too
early to tell just how much precipitation will fall, chances are
that this system will make difficulties for holiday travel.

As the system pushes off to the east on Friday, snow levels will
fall to between 3000 to 3500 feet. This means that some areas that
saw rainfall may see a transition to sleet or even snow on Thursday
night into Friday morning. On Friday, there may be a few brief
breaks in the precipitation--especially for the east side; but
precipitation chances will still remain moderate. As far as the
weekend is concerned, another trough will move Friday night into
Saturday in bringing another shot of precipitation to most of the
forecast area. Snow levels will rise to above 5000 feet west of the
Cascades with some areas in the Umpqua Basin and the coast seeing
freezing levels near 6000 feet. For the Eastside, however, snow
levels will take a little bit longer to rise; and could see snow
levels near 5000 briefly on Saturday night. Once the trough moves
inland, snow levels will plummet to 4000 across the area very early
Sunday morning.

During this time frame, winds may also become strong and gusty--
particularly across our windier spots east of the Cascades on
Thursday and again on Saturday. Saturday is forecast to have the
stronger winds throughout the extended timeframe. These winds could
create visibility issues with blowing snow--particularly on Oregon
highways 140 and Oregon Highway 31 near Summer Lake. -Schaaf

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Wind Advisory until 7 AM PST Sunday for ORZ030-031.

CA...Wind Advisory until 7 AM PST Sunday for CAZ085.
Winter Weather Advisory until 10 PM PST this evening ABOVE 4500
FEET for for CAZ082-083.

Pacific Coastal Waters...Gale Warning until 4 AM PST Sunday for
PZZ350-356-370-376. Hazardous Seas Warning until 4 AM PST
Sunday for PZZ356.

NSK/BMS/TRW

Area Forecast Discussion

National Weather Service Marquette MI

422 AM EST Sun Nov 20 2016

.SHORT TERM...(Today and tonight)
Issued at 421 AM EST SUN NOV 20 2016

00Z raobs/latest wv imagery and RAP analysis show a deep upr trof
stretching fm nw Ontario into the mid Atlantic states shifting
slowly to the e, allowing a broad upr rdg in the Plains to move
grdly to the e, with hgt rises/large scale subsidence and mid lvl
dry air associated with that feature overspreading Upr MI. But cold
sfc-h85 nnw flow ahead of sfc hi pres rdg in MN and departing sfc lo
pres to the e that is advecting 00Z h85 temps as lo as -16C at INL/
-20C at YPL into the Upr Lks is generating nmrs lk effect sn
showers, especially into the central cwa downwind of moistening off
Lk Nipigon. Although the upstream 00Z raobs indicate the larger
scale subsidence has lowered the invrn base aob about h85 and the
upstream airmass is quite dry per the inverted v T/Td profile shown
on the INL/YPL raobs blo the invrn base, the Marquette radar shows a
sharp les band with reflectivies >28dbz over ern Marquette County
and far wrn Alger County extending into nrn Delta County, in an area
where a sfc nw wind land breeze component is enhancing the llvl
cnvgc with the nly gradient flow. The sn has become fluffier in
nature as well as the RAP analysis indicates a 2k ft thick dgz in
the moist lyr just blo the invrn base. Wind gusts over 30 mph are
present near Lk Sup e of Marquette, contributing to some blowing sn.
In the absence of the Lk Nipigon mstng and with the negatives listed
above, les over the wrn cwa and e of Grand Marais appears much
lighter per sfc obs/Cndn and DLH radars. Looking farther to the w,
there is quite a bit of mid lvl cld cover spreading into MN
associated with the waa ahead of a shrtwv riding over the upr rdg
near the Cndn border in the Plains.

Main fcst concerns in the short term focus on les trends/amnts and
need for additional headlines for dominant les band now impacting
ern Marquette/wrn Alger/nrn Delta County.

Today...The larger scale subsidence associated with the slowly
aprchg upr/sfc rdgs is fcst to grdly lower the subsidence invrn
further and cause the llvl flow to weaken and become more acyc.
However, many of the hi res models indicate the dominant band now
impacting areas just to the e of Marquette wl move only slowly to
the w before diminishing somewhat this aftn. Considering the fvrbl
sn/water ratios, opted to post an les advy Marquette County, Alger
County, and Delta County thru this mrng, with emphasis on ern
Marquette County, far wrn Alger County, and nw Delta County. Over
the w, any lingering les wl end during the aftn as the invrn base
lowers aob 3k ft agl by 00Z Mon.

Tngt...The upr rdg axis to the w is fcst to amplify, resulting in
more larger scale subsidence. But the persistent nnw llvl flow is
fcst to maintain h85 temps as lo as -10 to -12C over the e half of
the cwa. So although the slowly lowering invrn base and influx of
some drier air fm n of Lk Sup wl tend to limit sn shower intensity,
maintained some chc pops for the ncentral and e, with some lingering
likely pops thru the evng over the ncentrl downwind of the continued
Lk Nipigon moistening. With the sfc hi pres rdg easing over the wrn
cwa and a lower invrn base under 3k ft agl, there wl be no les. In
fact, the llvl acyc flow may cause the lo clds to break up in that
area. With the lgt winds under the rdg axis and pwat near 0.25 inch,
temps could fall sharply over some sn cover. The only concern with
going too lo on the min temps is the area of mid cld cover now
streaming thru MN. Model h7 rh fcsts sug at least some of this cld
wl impact the w and areas near the WI border, but the larger scale
subsidence ahead of the sharpening upr rdg axis may cause this cld
to at least break up. So lowered fcst min temps a few degrees to
about 10F to better match the Green Bay fcst.

.LONG TERM...(Monday through Saturday)
Issued at 421 AM EST SUN NOV 20 2016

Upper lakes still on the edge of deep troughing aloft on Mon with
heights rising briefly for Tue. Could still be lingering light lake
effect in north flow areas of cntrl Upper Michigan on Mon though
snow amounts will be minor with inversion aob 3kft. Gradual warming
will also remove the DGZ out of the lake cloud layer so the fluff
will be waning. Clouds should decrease most areas in the aftn but
with light north winds persisting the clouds may try to stick around
near Lk Superior. High temps in the low to mid 30s will stay below
normal.

Attn later Tue will be on shortwave trough crossing central plains
and associated sfc low. Though most of Tue stays dry with just
increasing mid clouds, think precip mainly in the form of snow moves
in later Tue night through Wed. Models remain at odds on how much
moisture/qpf occurs mainly Tue Night into Wed as the sfc low lifts
toward the western Great Lakes. GFS still showing qpf up to 0.75
inch which is supported by GEM as well. ECMWF and ensembles suggest
lesser amounts of qpf more on the order of 0.25-0.50 inch.
Near sfc temps in the mid 30s will also be marginal for significant
snow accums unless forcing turns very strong. Overall looks like
snow Tue night going over to mix of rain/snow on Wed with minor snow
accums possible. Therefore travel could be messy depending on sfc
temps for the travel day before Thanksgiving and into Wed night. Not
out of question a headline would be required though it sure is not a
sure thing at this point. Will have to keep watch on it though since
it would occur on the busy travel day. Will keep a mention in
Hazardous weather outlook at this point. Winds should not be an
issue with this next system. Could see wind gusts 20-30 mph across
Keweenaw Peninsula and near Lk Superior east of Marquette late Tue
night into Wed but these values are pretty tame compared to what just
occurred this weekend.

Sfc low drifts across lower Great Lakes into Thanksgiving with an
inverted trough lingering across Upper Great Lakes. Potential for
additional shortwave trough to work in from the northwest and that
along with convergence with the trough and marginal cold air aloft
for lake effect/enhancement leads to increasing to likely pops for
snow over mainly the west half on Thanksgiving. Once again near sfc
temps as they are forecast attm in the mid 30s will be marginal for
much in the way of snow accums and there probably would be some rain
mixed in over parts of the cwa especially in the aftn with gradual
warming temps.

Troughing aloft and weak sfc troughing persisting into Fri should
lead to scattered lake effect snow showers near Lk Superior. Winds
expected to be mainly north to northwest so those snow belts would
see greater chances. Continues to be marginally cold aloft though
may become slightly colder with h85 temps down to -10c on Fri. Once
again snow amounts should be on the light side. Chances of lake
effect should diminish for the weekend as ridging aloft brings in
warm air advection that will take area out of the marginal setup for
lake effect.
&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1227 AM EST SUN NOV 20 2016

As low pressure continues to move eastward into Quebec, high
pressure will move into the Upper Great Lakes. Influx of drier air
and large scale subsidence are already working to decrease overall
lake effect shsn with only KSAW being affected by marginal MVFR
vsbys at times through the night. Ceilings at IWD/CMX/SAW will be on
the MVFR/VFR fence into the morning hours on Sunday before
conditions improve to VFR for all locations through the day. Winds,
while still a little gusty though the overnight, will continue to
slowly diminish into Sunday.
&&

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 421 AM EST SUN NOV 20 2016

Pressure gradient continues to weaken as high pressure ridge to west
of Lk Superior approaches today. Could see a few gale gusts to 35
kts early over the east half. While the high pres ridge and light
winds will reach western Lake Superior this aftn, the ridge won`t
reach eastern Lake Superior until Mon night so winds there will stay
in the 20-30 kt range until later tonight/Mon. Winds will increase
across the lake Tue night into Wed as the next low pres system moves
across the Great Lakes region. The strongest winds, 20-30kt, will
occur over central and eastern Lake Superior late Tue night into Wed.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
Lake Effect Snow Advisory until 1 PM EST this afternoon for
MIZ005-006-013.

Lake Superior...
None.
Lake Michigan...
None.
&&

SHORT TERM...KC
LONG TERM...JLA
AVIATION...MZ
MARINE...JLA

Area Forecast Discussion

National Weather Service State College PA

1027 AM EST Sun Nov 20 2016

.SYNOPSIS...
An upper low over Pennsylvania will slowly drift northeast toward
the Canadian maritimes early next week. Low pressure lifting out
of the Mississippi Valley will likely track just north of
Pennsylvania late Wednesday or Thursday.

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
1015 am Update...
Nice multilake band has set up from Erie to Clearfield into Centre
County. Another band through Pitt making it down into the Laurel
Mountains. Northwest Warren Co. right now missing any significant
snow bands but as wind shifts today the band should rotate into that
area so not going to mess with snow amounts right now. Northeast
Warren and McKean Counties snowing good right now. Bradford has been
reporting moderate snow for a couple hours.

Winds have been strongest across the south this morning with gusts
up around 40 mph with most of the rest of the area gusting into
the lower 30s. Still expecting this to increase as the day
progresses and storm center in New Engaland continues to deepen.

Previous Discusion...
Early AM water vapor loop showing a deep upper level trough
transitioning to a cut off low over Western NY state. Ribbon of
deep moisture associated with deformation zone is progged by
models to pivot over Pa today, resulting in a lake- enhanced
orographic snow event across the Allegheny Plateau. WNW cross-lake
flow should continue to produce generally light snowfall rates
across the Western Mtns today with additional amounts of 1-2
inches between 12Z-00Z. However, latest HRRR and NCAR ensemble
indicate the potential of a heavier single band originating from
Lake Huron affecting somewhere over northern Cambria/Southern
Clearfield county later today. Will have to monitor this area for
a possible increase in snow amounts. Also expecting somewhat
heavier amounts in the favored snowbelt region of NW Warren
county, where an additional 3-5 inches appear likely today based
on higher res models. Drying downsloping flow, combined with above
freezing sfc temps, should limit accums east of the mountains to
no more than a coating in spots.

Increasingly strong/gusty winds will buffet all of Central Pa
today, as gradient tightens in response to strengthening storm
over New England. Bufkit soundings continue to support wind gusts
in excess of 40kts later today, especially over the south central
part of the state. The gusty winds will create areas of
blowing/drifting snow over the Alleghenies.

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/...
Deformation band and associated layer of deepest moisture will
lift north of the state tonight, likely causing the snow showers
to diminish a bit. However, air mass crossing the lakes will
remain plenty cold enough to produce continued light snow
across the Western Mtns. The wind advisory, which is valid
through midnight, may have to be extended into Monday morning
based on a look at model soundings.

Trend of weakening lake effect will continue into Monday, as upper
low pulls away and inversion heights lower. Any additional accums
are likely to be an inch or less over the NW Mtns. Model RH
profiles suggest an increasing amount of sunshine, mainly southeast
of the Mtns Monday. However, ensemble mean 8h temps bottoming out
around -10C indicate readings will struggle to reach 32F over the
high terrain of Central Pa and reach only the low 40s across the
Susq Valley. Bufkit soundings indicating gusty winds just below
advisory criteria, which will add to the chill.

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
All med range guidance indicates surface ridge will build into the
region Tuesday into early Wed, supporting a high confidence
forecast of fair and slightly milder weather. A warm front will
move through Wednesday afternoon as the next storm system moves
into the Great Lake Region.

GFS and ECMWF differ on how fast the precip and cold or occluded front
associated with this storm moves into PA with the GFS being the
fast one bringing it in early Wednesday night and the euro
more toward Thursday morning. Temperatures have warmed enough
that any precipitation Wednesday night and Thursday will be rain.

Both models then develop a secondary low on the VA Coast
which deepens as it moves off to the northeast. This will help to
bring some colder air in by Thursday night to northern PA with
just a slight chance of mix rain and snow showers there. A
clipper system moves quickly through Friday night and Saturday
with a better chance across the north for mix rain and snow
showers with snow chances in the higher elevations. Cold air
sweeps in behind this and some lake enhancement could change over
to snow showers by Saturday afternoon.

.AVIATION /15Z SUNDAY THROUGH THURSDAY/...
Strong WNW upslope flow will keep restrictions in place across
the norther/western TAF sites and portions of the central mtns as
snow showers continue through tonight.

Over the NW mtns and Laurel Highlands, expect more solid IFR
conditions in frequent snow showers/upslope stratus with brief
increases to MVFR between the snow showers. Generally MVFR cigs
will be the rule over the central mtns with occasional incursions
of sct snow showers.

In addition, wind strength/gusts will peak during next 24 hours
with sustained winds of 20-25 mph and frequent surface gusts of
35-50 mph.

Snow showers linger mainly in the NW on Monday, but wind down
elsewhere as low slowly slides further into New England. MVFR cig
restrictions likely continue over the west/north as low-level
inversion persists while high pressure gradually builds in from
the west. Winds remain quite breezy, but not as strong as Sunday.
Gusts up to 40 will remain likely.

Outlook...

Tue...Morning MVFR cigs possible across the northern and western
mtns of PA...otherwise decreasing wind and improving conditions to
mainly VFR.

Wed...No significant weather expected.

Wed night and Thursday...MVFR to IFR conditions as periods of rain
spread east across the state. Mixed precipitation possible across
the northern and western mountains of PA.

.CTP WATCHES/WARNINGS/ADVISORIES...
Wind Advisory until midnight EST tonight for PAZ019-025>028-
034>037-041-042-045-046-049>053-056>059-063>066.
Winter Weather Advisory until 7 AM EST Monday for PAZ012-017-
018-024-033.
Lake Effect Snow Advisory until 7 AM EST Monday for PAZ005-006-
010-011.
Lake Effect Snow Warning until 7 AM EST Monday for PAZ004.

$$
SYNOPSIS...Fitzgerald
NEAR TERM...Watson/Fitzgerald
SHORT TERM...Fitzgerald
LONG TERM...Watson/Fitzgerald
AVIATION...RXR

Area Forecast Discussion

National Weather Service Marquette MI

640 AM EST Sun Nov 20 2016

.SHORT TERM...(Today and tonight)
Issued at 421 AM EST SUN NOV 20 2016

Main fcst concerns in the short term focus on les trends/amnts and
need for additional headlines for dominant les band now impacting
ern Marquette/wrn Alger/nrn Delta County.

.LONG TERM...(Monday through Saturday)
Issued at 421 AM EST SUN NOV 20 2016

.AVIATION...(For the 12Z TAFS through 12Z Monday morning)
Issued at 640 AM EST SUN NOV 20 2016

Lk effect shsn wl impact mainly SAW this fcst period, especially
this mrng, when a dominant band wl bring some LIFR conditions at
times into mid mrng. Even after this band weakens, MVFR conditions
wl predominate at SAW with an upslope nnw wind. MVFR cigs at CMX and
IWD wl likely improve to VFR by later in the day with closer aprch
of sfc hi pres/more acyc llvl flow and less modification of the llvl
dry air upstream of Lk Sup.
&&

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 421 AM EST SUN NOV 20 2016

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
Lake Effect Snow Advisory until 1 PM EST this afternoon for
MIZ005-006-013.

Lake Superior...
None.
Lake Michigan...
None.
&&

SHORT TERM...KC
LONG TERM...JLA
AVIATION...KC
MARINE...JLA

Area Forecast Discussion

National Weather Service Bismarck ND

245 PM CST Sun Nov 20 2016

.SHORT TERM...(This evening through Monday)
Issued at 245 PM CST Sun Nov 20 2016

The main concern tonight into Monday will be the possibility of
another round of stratus and fog. Early afternoon visible
satellite imagery shows a small patch of stratus remaining across
the northwest part of the state, otherwise skies were mostly
sunny. Short term models, and in particular the HRRR suggest
another round of stratus and fog developing tonight. The central
part of the state appears to be the favored location for the lower
visibilities and have gone with areas of fog in that region. Have
some concern the fog could become dense and widespread enough to
warrant an advisory if the HRRR output is on target.

.LONG TERM...(Monday night through Sunday)
Issued at 245 PM CST Sun Nov 20 2016

Attention Monday night into Tuesday shifts to the next in a series
of upper waves that are expected to move across the region
through the week. One of the initial concerns for Monday night
into Tuesday morning is the possibility of a wintry mix,
especially as the precipitation begins. Thermal profiles still
suggest warm enough air aloft to support a period of light
freezing rain before changing to snow. Another complicating factor is
that forecast soundings still also show a dry layer with
potential cooling to the wet-bulb in some locations. Will carry a
mix in the grids, and also mention it in the Hazardous Weather
Outlook this afternoon. Potential snow totals still appear light
with snow ratios remaining low through Tuesday.

The remainder of the week with have periodic chances of mainly light
snow in a fairly progressive pattern. Precipitation amounts with
any of the systems still appears fairly light.

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 245 PM CST Sun Nov 20 2016

Band of MVFR/IFR stratus remains stretched over western into
north central ND impacting only KMOT...west of KBIS and east of
KISN and KDIK now. Stratus should erode/scatter for KMOT over the
next hour or two. VFR conditions thereafter this afternoon all
terminals. MVFR stratus and fog will again be expected across
south central North Dakota and the James River Valley this evening
into Monday morning impacting both KBIS-KJMS and possibly KMOT.

.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

SHORT TERM...CK
LONG TERM...CK
AVIATION...NH

Area Forecast Discussion

National Weather Service State College PA

303 PM EST Sun Nov 20 2016

.NEAR TERM /THROUGH TONIGHT/...
1015 am Update...
Nice multi-lake band has set up from Erie to Clearfield into
Centre County. Another band through Pitt making it down into the
Laurel Mountains. Northwest Warren Co. right now missing any
significant snow bands but as wind shifts today the band should
rotate into that area so not going to mess with snow amounts right
now. Northeast Warren and McKean Counties snowing good right now.
Bradford has been reporting moderate snow for a couple hours.

Previous Discussion...
Early AM water vapor loop showing a deep upper level trough
transitioning to a cut off low over Western NY state. Ribbon of
deep moisture associated with deformation zone is progged by
models to pivot over Pa today, resulting in a lake- enhanced
orographic snow event across the Allegheny Plateau. WNW cross-lake
flow should continue to produce generally light snowfall rates
across the Western Mtns today with additional amounts of 1-2
inches between 12Z-00Z. However, latest HRRR and NCAR ensemble
indicate the potential of a heavier single band originating from
Lake Huron affecting somewhere over northern Cambria/Southern
Clearfield county later today. Will have to monitor this area for
a possible increase in snow amounts. Also expecting somewhat
heavier amounts in the favored snowbelt region of NW Warren
county, where an additional 3-5 inches appear likely today based
on higher res models. Drying downsloping flow, combined with above
freezing sfc temps, should limit accums east of the mountains to
no more than a coating in spots.

.SHORT TERM /MONDAY/...
Deformation band and associated layer of deepest moisture will
lift north of the state tonight, likely causing the snow showers
to diminish a bit. However, air mass crossing the lakes will
remain plenty cold enough to produce continued light snow
across the Western Mtns. The wind advisory, which is valid
through midnight, may have to be extended into Monday morning
based on a look at model soundings.

.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...

Medium range guidance indicates the upper low will continue off to
the Canadian maritimes with rising heights and an upper ridge
building quickly east out of the Midwest by Tuesday.

The fair weather will continue into Wednesday before another weak
upper trough and surface cold front brings the next chance for
widespread precip by later Wednesday into Thursday.

Precipitation type issues could arise ahead of this next system
as air and wet bulb temperatures aloft will be marginally cold
over about the northern half or so of the forecast area. I also
inserted the mention of pockets of freezing rain overnight as
surface temperatures could drop to freezing in some of the normal
cold spots. It doesn`t look like a big QPF event but things could
get slippery later Wednesday into early Thursday. Too early to be
specific.

Some differences arise by Friday with the GFS/GEFS showing a weak
shortwave approaching after a dry start to the day. The 12Z ECMWF
shows a deeper-slower shortwave trough with a surface low that is
made to redevelop near the northern portion of the Chesapeake that
deepens as it tracks toward Long Island. That would have precip
type and amount implications possibly more on the wintry side is
it happens. The 00Z ECENS did not show this stronger development
so I used the latest blended MOS POPs that show generalized
chances for light rain or snow showers.

.AVIATION /19Z SUNDAY THROUGH FRIDAY/...
Strong WNW upslope flow will keep restrictions in place across
the norther/western TAF sites and portions of the central mtns as
snow showers continue through tonight.

In addition, wind strength/gusts will peak during next 24 hours
with sustained winds of 20-25 mph and frequent surface gusts of
35-50 mph.

Outlook...

Tue...Morning MVFR cigs possible across the northern and western
mtns of PA...otherwise decreasing wind and improving conditions to
mainly VFR.

Wed...No significant weather expected.

Wed night and Thursday...MVFR to IFR conditions as periods of rain
spread east across the state. Mixed precipitation possible across
the northern and western mountains of PA.

.CTP WATCHES/WARNINGS/ADVISORIES...
Wind Advisory until 7 PM EST Monday for PAZ019-025>028-034>037-
041-042-045-046-049>053-056>059-063>066.
Winter Weather Advisory until 7 AM EST Monday for PAZ012-017-
018-024-033.
Lake Effect Snow Advisory until 7 AM EST Monday for PAZ005-006-
010-011.
Lake Effect Snow Warning until 7 AM EST Monday for PAZ004.

$$
SYNOPSIS...Watson
NEAR TERM...Watson
SHORT TERM...Watson
LONG TERM...La Corte
AVIATION...Watson/RXR

Area Forecast Discussion

National Weather Service San Joaquin Valley - Hanford CA

202 PM PST Sun Nov 20 2016

.SYNOPSIS...
A storm system will impact the central California interior on
Sunday, bringing the region a chance of rain and mountain snow.
Another system may impact northern parts of the area by mid-week
on Wednesday.

.DISCUSSION...
145 pm PST radar shows a line of precipitation extending along a
cold front from Yosemite National Park south through San Luis
Obispo. Up to a third of an inch of rain has already been observed
in the parts of Merced County. The front will continue to push
east through central California during the afternoon and evening
hours on Sunday, bringing along with it the increased chance of
precipitation as moisture advects from the south. HRRR and high-
res WRF models advertise the rain approaching Fresno by mid-
afternoon to early evening. As the front pushes through, we`ll see
snow levels fall to around 7,000 feet - possibly as low as 6,500
feet - near Yosemite National Park where a Winter Weather
Advisory is in effect through 10 pm PST Sunday.

Showers will linger over the area Monday morning and afternoon,
especially for locations in the mountains, foothills and southern
San Joaquin Valley. While the upper low continues to push into the
North American continent, fog will become a concern in the San
Joaquin Valley for the Tuesday morning commute as a ridge builds
over the West Coast. Right now confidence is medium for fog
development, but its intensity and coverage is still unknown.

Tuesday`s ridge will be short-lived as another system approaches
the West Coast on Wednesday. This system still has some unknowns
with the timing and trajectory. 12Z GFS and ECMWF suggest
precipitation for the northern half of the CWA (Fresno County
northward) with the best potential in Yosemite National Park.

Thanksgiving Day looks to be mainly dry for holiday travelers
across the central California interior, but another storm system
will begin to aim on northern California late Thursday.
Precipitation chances for our area will begin to increase by the
Friday/Saturday time frame. Confidence for the timing and
placement of this storm system is low. Model uncertainty continues
to grow beyond Saturday, but it does appear the pattern will
remain unsettled for the West Coast into the end of November.

.AVIATION...
In the southern Sierra...IFR conditions can be expected in Yosemite
National Park with IFR conditions spreading southward to Kings
Canyon National Park by 03z Monday. Mountain obscurations in heavier
precipitation.

In the Sierra foothills...MVFR conditions in Mariposa and Madera
County with MVFR conditions spreading southward into Tulare County
by 03z Monday.

Areas of MVFR ceilings can be expected along the north facing slopes
of the Tehachapi mountains between 06z and 18z Monday.

In the San Joaquin Valley...areas of MVFR ceilings are possible
between 00z and 18z Monday with local IFR ceilings in Merced County
between 12z and 16z Monday.

.AIR QUALITY ISSUES...
None.

.CERTAINTY...

The level of certainty for days 1 and 2 is medium.
The level of certainty for days 3 through 7 is medium.

Certainty levels include low...medium...and high. Please visit
www.weather.gov/hnx/certainty.php for additional information
an/or to provide feedback.

.HNX Watches/Warnings/Advisories...
Winter Weather Advisory until 10 PM PST this evening ABOVE 7000
FEET FOR THE CAZ096.

public...Rowe
avn/fw...Durfee
synopsis...Rowe

weather.gov/hanford

Area Forecast Discussion

National Weather Service Marquette MI

341 PM EST Sun Nov 20 2016

.SHORT TERM...(This evening through Monday)
Issued at 341 PM EST SUN NOV 20 2016

Water vapor imagery and RAP analysis show a deep, negatively tilted
mid/upper level trof over the ne CONUS with a broad ridge from the
Rockies into the Plains. LES into the n central fcst area held on
with more intensity than expected last night into the morning
despite the overall hostile large scale environment of rather strong
qvector divergence/subsidence in addition to low inversion/dry air
mass per upstream observed soundings. Finally, late morning into
this aftn, LES has really diminished. Drying of the air mass is also
evident on vis satellite imagery with cloud streamers initiating
farther out over the water from the upstream shore of the lake as
well as clouds dissipating northward from northern WI.

Upstream sfc ridge axis over ne MN/western WI will only drift to far
western Lake Superior tonight and only reach far western Upper MI by
late Mon aftn. As a result, northerly flow across Lake Superior will
prevail tonight/Mon, except over far western Upper MI which will see
low-level winds veer more to the ne or e during the day Mon. With
850mb temps tonight only slowly rising to around -7C w and -11C e by
12z Mon, stratocu will probably dominate much of the area tonight,
and light LES/flurries will continue into the n central and eastern
fcst area. Clouds will keep temps from crashing over the w which
will be under light winds closer to the ridge. There is some erosion
of clouds from the s over northern WI into s central Upper MI
currently, and this clearing may sneak farther n and w over the next
hr or two into Iron and perhaps Gogebic counties as weak daytime
heating works to mix out moisture a bit. However, with nocturnal
cooling, lake effect clouds should expand again during the night
under inversion, especially away from the far s central, though
increasing anticyclonic flow may work against the cloud expansion.
Even if low clouds don`t expand, considerable mid/high clouds are
moving across MN toward western Upper MI. In the end, min temps
should range from around 10F interior w to the mid/upper 20s along
Lake Superior central and e. If clouds manage to scatter out for a
time over the w, temps could quickly plunge toward 0F.

Any lingering light LES/flurries will end over the n central and e
by early Mon aftn as air mass continues to moderate and dry. Expect
a gradual decrease in clouds with s central and w having best chc of
becoming mostly sunny during the day. Much of the day will probably
be mostly cloudy n central and e. High temps should be mostly in the
upper 20s/lower 30s.

.LONG TERM...(Monday night through Sunday)
Issued at 245 PM EST SUN NOV 20 2016

Main significant weather in the long term is mid-week with potential
for advisory (or possibly low end warning) level snow.

An upper trough is modeled to move through the area mid-week,
bringing a roughly 1010mb SFC low from northern IL/southern WI
through central lower MI Wed and Wed night. Widespread precip is
modeled to move into the W or SW late Wednesday, and the bulk will
move out Wed night. Models are in good agreement overall, but vary
on QPF. The GFS and GEM at up to 0.70" while the ECMWF only has up
to around 0.40". Most of the precip falls as snow, with the
exception possibly of the south-central where a transition to rain
is more likely. If the event plays out as currently modeled, winter
weather advisories would be needed over at least a portion of the
area, with potential for some warning amounts if the GFS/GEM amounts
verify. For now, given the inherent uncertainty at that time frame
with this type of system, will continue to mention in the HWO.
Definitely will have to keep a close eye on the system given the
high-impact travel day.

Lighter snow is possible Thursday into the weekend, but not looking
at any significant amounts right now.
&&

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 1226 PM EST SUN NOV 20 2016

Chilly air mass over Lake Superior along with northerly winds will
result in bkn-ovc MVFR stratocu prevailing thru this fcst period at
KIWD/KCMX/KSAW. However, with high pres ridge settling over western
Lake Superior tonight/Mon, increasing anticyclonic flow may cause
stratocu to sct out at KIWD Mon morning and at KCMX near the end of
the fcst period. At KSAW, lake effect shsn will continue thru
tonight, though diminishing in intensity/frequency with time. May
see a few periods of MVFR vis this aftn and perhaps very brief IFR
early this aftn.
&&

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 341 PM EST SUN NOV 20 2016

High pres ridge that will settle over western Lake Superior tonight
will very slowly shift e, reaching eastern Lake Superior Tue
morning. This will lead to light winds, mostly under 15kt over the
western part of the lake thru Mon night. Over eastern Lake Superior,
winds will generally remain in the 20-30kt range tonight, slowly
diminish to under 20kt by late Mon aftn, then to under 15kt for Mon
night/Tue. The ridge will then shift e more quickly as a low pres
system emerging over the Plains early Tue tracks ene into the
western Great Lakes by Wed evening. As a result, winds will increase
to 20-25kt across much of the lake Tue night into Wed with the
strongest winds occurring over central and eastern Lake Superior.
Winds will diminish to under 15kt for Thu/Fri as the pres gradient
across the area becomes weak.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&

SHORT TERM...Rolfson
LONG TERM...Titus
AVIATION...Rolfson
MARINE...Rolfson

Area Forecast Discussion

National Weather Service Pittsburgh PA

529 PM EST Sun Nov 20 2016

.SYNOPSIS...
Lake effect snow showers will continue tonight before tapering
off Monday morning. Temperatures will climb back to average by
Wednesday through the end of the week.

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
Snowfall reports in the southern extent of the lake effect snow
advisory have been around one inch. Given flow will be backing
this evening into the overnight shifting bands to be focused
along I-80 and points north, opted to cancel lake effect snow
advisory for Lawrence, Butler, Armstrong, and Indiana. The
remainder of the forecast and headlines look in good shape.
Previous discussion below.

Lake enhanced snow showers will continue through this evening,
with further accumulation likely in a prominent band over Venango
and Forest, as progged by the deterministic and hi res model
guidance since yesterday. The newest runs of the hrrr and nmm/arw
still show this band persisting through at least midnight, so I
did not feel comfortable ending the advisory for the counties
immediately downwind of Venango this evening. Thus, while the
southern tier of advisory counties will still expire at 7pm
tonight, Forest, Clarion, and Jefferson will now run until 7am.

Further south, lake enhanced snow showers will gradually diminish
as subsidence takes place and some dry air mixes to the surface.
Flurries will still be possible but accumulating snow is less
likely. The exception will be the terrain, where the northwest
flow will continue to squeeze out any moisture that is left in the
column. Have made little to no change here, with light snow
expected through tomorrow morning.

Temperatures were tweaked little and will remain cold by mid-late
November standards.

.SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY/...
Deep northwesterly flow will continue through much of Monday
before warm advection ensues. While moisture will be limited for
widespread snow, low chance PoPs were maintained, especially in
the northernmost zones and in the terrain until at least midday.
Regardless, cold advection should hold clouds over much of the
region, until late, which should be a limiting factor to our
highs. An upper ridge will build eastward on Tuesday with dry
conditions expected but below average temperatures continuing.

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
Mid-level ridge axis crosses on Tuesday night, signaling a return
to active weather after a brief dry break. Models are in decent
agreement with the system arriving Wednesday and lingering through
Thanksgiving. Our area is on the warm side as the low passes to
the north, thus expecting mostly rain with this system. Another
shortwave quickly follows from the Great Lakes for Friday into
Saturday, with rain and snow shower chances, possibly followed by
a yet another disturbance, this one from the southern stream, by
the very end of the extended period.

.AVIATION /00Z MONDAY THROUGH FRIDAY/...
General high MVFR/low VFR ceilings will continue through the
afternoon. Expect occasional drops to IFR in continued lake effect
snow showers mainly from PIT on north. FKL and particularly DUJ
are under the gun for LIFR for several more hours. Main snow bands
will slowly shift north with time, ending the IFR threat at
PIT/BVI/LBE but such restrictions will continue near/north of I-80
well into the night. MVFR ceilings will continue through the night
at most terminals as the inversion level drops a bit. Improvement
begins after sunrise as snow showers scatter out and ceilings
begin to lift/break to VFR. Gusty winds will continue to be an
issue through much of the TAF period, with gusts of 25 to 35 knots
possible.

OUTLOOK...
Restrictions are possible Wednesday and Thursday as the next storm
system arrives from the Great Lakes.

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...Winter Weather Advisory until 4 AM EST Monday FOR MDZ001.
OH...None.
PA...Lake Effect Snow Advisory until 7 AM EST Monday FOR PAZ009-015-
016.
Lake Effect Snow Advisory until 7 PM EST this evening FOR
PAZ007.
Lake Effect Snow Warning until 7 AM EST Monday FOR PAZ008.
Winter Weather Advisory until 4 AM EST Monday FOR PAZ074-076.
WV...Winter Weather Advisory until 4 AM EST Monday FOR WVZ510>514.

synopsis...98
near term...98/34