Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/08/17
Area Forecast Discussion
National Weather Service Bismarck ND
957 PM CST Sat Jan 7 2017
.UPDATE...
Issued at 950 PM CST Sat Jan 7 2017
For the late evening update we lowered temperatures along and
east of the Highway 83 corridor. Mainly 18 to 22 below zero over a
good portion of central and eastern ND tonight. Temperatures have
risen in the west and are currently zero to five below across the
far west. The warming temperatures will eventually spread eastward
tonight. Temperatures Sunday morning will be warmer than the same
time this morning.
Latest iterations of the experimental HRRR continue to suppress
any fog/stratus south and east of the forecast area, thus took the
mention of fog out of the south central late tonight into Sunday
morning.
UPDATE Issued at 529 PM CST Sat Jan 7 2017
Main forecast issue for the early evening update will be
temperatures. Mostly clear skies over all but the far southwest
corner of North Dakota. Surface high is centered over the James
river Valley southeast to near Aberdeen and then east into the
eastern Dakotas.
This pattern is a near perfect setup for very cold temperatures at
the Bismarck Airport. Had this been the setup this morning we may
have been flirting with a record low (-40F), rather than our -30F
reading. What we are dealing with is rapidly falling early evening
temperatures, from -5F at 3 PM to -16 at 4PM and down to -21F
between 5 and 6 PM. However we expect warm advection to spread
into central ND this evening thus whatever our 6 PM temperature
reading is, could be our overnight low. We could drop a few more
degrees this evening but points along and west of the Highway 83
corridor will be more likely to remain steady or rise, especially
as clouds increase from west to east later this evening and
overnight. Areas east of the Highway 83 corridor will see
temperatures continue to drop quickly this evening before
steadying out and eventually rising late this evening or after
midnight. Needless to say, temperatures will be a bear tonight.
Mesoscale models have been hinting at fog/stratus advecting north
into south central ND late tonight into Sunday morning. The latest
EXPHRRR is not as bullish as other models. For now will bring some
patchy lower ceilings into the south central but not at KBIS as
uncertainty is too great. No changes to current Hazards. Updated
text products will be sent shortly.
&&
.SHORT TERM...(This evening through Sunday)
Issued at 333 PM CST Sat Jan 7 2017
Cold conditions and wind chill concerns are the main highlights in
the short term.
Current surface analysis indicates the arctic high pressure system
centered over eastern SD this afternoon with northwest flow aloft
ovr the Northern Plains. Temperatures have been climbing slowly
today...but are not expected to reach above zero over eastern
portions of central ND, with highs of around 5 to 10 above in the
far southwest.
Tonight the arctic high continues sliding southeast with southerly
winds currently in western ND spreading eastward. However, this will
likely not be enough to scour out the cold arctic air much tonight.
Expect lows again to be below zero across the state...from the
single digits below zero in the southwest and 10 to 15 below mainly
north and east of the Missouri River. We will again need a wind
chill advisory for all but most of the southwest.
On Sunday another arctic high pushes south from the Canadian Front
Range. Highs should reach around 10 above in the far southern
counties, but will barely get above zero in the far north as the
reinforcement of arctic air moves in.
.LONG TERM...(Sunday night through Saturday)
Issued at 333 PM CST Sat Jan 7 2017
Snow chances Sunday night through Tuesday...then a return to cold
conditions with wind chill concerns for the latter half of next
week.
Late Sunday night, the arctic high slides southeast quickly and the
upper level flow flattens and becomes more zonal as a large storm
system moves into the west coast. Strong warm advection moves into
our region aloft from the southwest and will result in strong
isentropic lift developing late Sunday night in conjunction with a
strong upper level impulse moving through the fast-moving zonal flow
aloft...continuing strong Monday morning...and decreasing in
strength Monday afternoon as the strongest push of the system and
lift moves into eastern ND. The latest indications are that we could
get a quick shot of an inch or two of snow from late Sunday night
through Monday afternoon.
A second shortwave moves east across the state Monday night through
Tuesday morning as colder air moves in from the Canadian Front
Range. The latest models indicate the warming between the two arctic
highs may allow snow ratios to be lower than 10:1 in the far
southwest Monday evening before the arctic air arrives. The amount
of resulting snow is a bit more uncertain because of this. However
the latest indications are for another inch or two of snow...mainly
south of highway 2...Monday night through Tuesday morning.
Cold conditions and wind chills will again be the main concern
beginning Tuesday night...with more arctic outbreaks next week. The
coldest time period looks like Wednesday night through Friday...with
highs of zero to 10 below Thursday and lows of 15 to 25 below zero
Thursday night.
&&
.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 950 PM CST Sat Jan 7 2017
VFR conditions to begin the 00Z TAF period and expect mainly VFR
will continue through the TAF period but with lowering VFR
ceilings beginning in the west late tonight and continuing through
the day Sunday. Exception could be around KBIS with areas of
fog/stratus possibly advecting in from the south. This was noted
during the day by various mesoscale models. The latest iterations
of the experimental HRRR continue to suppress fog/stratus south
and east of the forecast area. Will not mention in TAFs.
Southeast flow tonight will shift northwest from west to east
Sunday beginning around 14 UTC at KISN. Did add a mention of LLWS
at KMOT, KBIS and KJMS late tonight into Sunday morning with a
strong warm advection pattern overspreading the central Dakotas.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
Wind Chill Advisory until 9 AM CST /8 AM MST/ Sunday for
NDZ001>005-009>013-017>023-025-033>037-042-045>048-050-051.
&&
$$
UPDATE...TWH
SHORT TERM...JV
LONG TERM...JV
AVIATION...TWH
Area Forecast Discussion
National Weather Service Dodge City KS
938 PM CST Sat Jan 7 2017
...UPDATE TO SYNOPSIS...
.SYNOPSIS...
Issued at 933 PM CST Sat Jan 7 2017
WV imagery indicates a northwesterly flow aloft prevailing across
the Western High Plains as an upper level ridge of high pressure
approaches from the west. Near the surface, high pressure is
shifting slowly eastward across the Upper Midwest.
&&
.SHORT TERM...(This afternoon through Sunday)
Issued at 1133 AM CST Sat Jan 7 2017
Arctic air slowly moderating under a sunny sky this afternoon. Did
an update to undercut guidance and previous forecast by a few
degrees, as melting/reflecting snow will hinder any warmuup. HRRR
temperature guidance actually matches snowcover on visible
satellite well (warmest temperatures on bare ground S/SE of Dodge
City). A clear sky will continue this afternoon, with cirrus
increasing this evening.
Tonight...Increasing clouds and not as cold. Moisture/warm
advection kick in just above the surface, with 850 mb winds
increasing to near 40 kts. Confident on stratus development over
the snowpack, with NAM most aggressive with this. Not as confident
on advection fog development and any resulting reductions in
visibility. High resolution models may be overdoing the injection
of moisture into the boundary layer from snowmelt (or the lack
thereof). For now, after coordinating with WFOs
Goodland/Hastings, added patchy freezing fog in the grids, on the
snowpack after midnight. Something to watch for the next couple of
shifts. With S/SE winds remaining elevated tonight, along with
increasing clouds and dewpoints, temperatures will moderate
tonight compared to last night, mainly in the teens.
Sunday...Becoming mostly sunny and warmer. Temperature forecasts
will be a challenge, as sunshine and strengthening downslope winds
battle remaining snowcover. Atmosphere warms strongly, with 850 mb
temperatures warming to near +7C at 850 mb per GFS/ECMWF. SW
downslope surface winds increase to 10-20 mph during the
afternoon, with the strongest winds east of Dodge City, and the
weakest winds across far SW Kansas. Trying to balance downslope
with snowmelt, took a stab with temperatures near MOS guidance, in
the upper 30s and lower 40s Sunday afternoon. The less snow you
have, the milder you will be.
.LONG TERM...(Sunday night through Saturday)
Issued at 220 PM CST Sat Jan 7 2017
Dry and mild through Wednesday. Interesting question marks arise
by Friday.
Monday...Windy and warmer. Flat ridging aloft spreads over SW KS,
with near zonal flow and lowering surface pressures in NW KS/E CO
leading to strong downslope. 12z ECMWF is very impressive with the
warming, with 850 mb temperatures as high as +20C Monday
afternoon. Remaining snowcover will be history by Monday
afternoon, allowing for afternoon highs ranging from near 50 near
Hays, to near 70 near Elkhart. Forecasting 60 at Dodge/Garden City
and that may not be warm enough.
Tuesday...A weak shortwave in the fast westerly flow aloft zips
through, with an attendant dry cold front offering a bit of
cooling. Still very pleasant for January. With downslope
components maintained, still expecting 50s for most zones.
Wednesday...Continued mild and dry. More weak shortwaves
approaching from the west will allow for more lee cyclogenesis,
with ECMWF placing a 996 mb surface low across the western CWA
Wednesday afternoon. Downslope will bring more 60s to the southern
zones, while a backdoor cold/stationary front will hold tight
across the NE zones, keeping locations near Hays in the 40s.
Thursday...Cooler, but still dry. Backdoor cold front slips
southwest, placing SW KS in more seasonably chilly air. NE zones
will struggle to reach freezing. Increasing clouds, as flow aloft
becomes SWly. Vigorous shortwave trough arrives in the Great
Basin.
Friday...12z ECMWF drops a closed low into Arizona, and incites
tremendous warm/moist advection precipitation across the central
and southern plains by afternoon. ECMWF solution spreads
accumulating snow across SW KS late Friday, with strong diffluence
aloft ahead of incoming upper low. With a wide open gulf moisture
supply, and cold air in place, significant snow is possible
(if convection across Oklahoma/Texas doesn`t grab all the moisture).
On the other hand, the latest GFS runs for late this week are a world
apart, with a much more progressive, open wave, leaving SW KS completely
dry. On Friday, whereas ECMWF has a snowstorm, GFS has nothing.
There were enough components of the superblend supporting
precipitation to place slight snow chances in the grids, but with
such model dichotomy, no collaborative pop increases were done
with the neighboring offices. Gut feeling is GFS is too
progressive in the medium range, and ECMWF is more correct, but
too much uncertainty to fiddle with grids this far out. Also
trended temperatures down on Friday, with ECMWF showing cold
Canadian air wedging southward on the high plains.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 503 PM CST Sat Jan 7 2017
Southeasterly up slope flow at 10 to 15 knots will develop early
tonight and continue through Sunday. This southeasterly flow that
will be developing over the lingering snow pack that exists across
western Kansas which should result in low IFR stratus development
and even some patchy freezing fog. The latest models have backed
off on the freezing fog and stratus but at this time am unable to
completely rule out some fog or low clouds developing towards
daybreak at all three taf sites. Area more favorable for this
appears to be around Garden City. The low clouds that do develop
overnight will be slow to erode Sunday morning but ceilings are
expected to begin to improve after 15z.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 13 39 23 59 / 0 0 0 0
GCK 6 39 23 61 / 0 0 0 0
EHA 10 50 32 66 / 0 0 0 0
LBL 13 43 27 64 / 0 0 0 0
HYS 9 36 21 51 / 0 0 0 0
P28 14 39 21 51 / 0 0 0 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...JJohnson
SHORT TERM...Turner
LONG TERM...Turner
AVIATION...Burgert
Area Forecast Discussion
National Weather Service Wilmington OH
1026 PM EST Sat Jan 7 2017
.SYNOPSIS...
A ridge of Arctic high pressure will continue to extend into the
region today. A weak trough of low pressure will pass across the
Great Lakes tonight. The Arctic high will then become reestablished
on Sunday before moving off to the east by Monday. Rain then returns
to the region starting Tuesday.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
Mid level shortwave dropping southeast, rotating through the
Great Lakes. Low level clouds have overspread the area ahead of
associated surface trof. Radar and surface observations
indicating scattered flurries over the area from this strato-cu
deck. Have continued mention of flurries and hit clouds harder.
With the passage of the s/w and sfc trof winds veer and pick up
some. Also, expect some decrease in clouds expect where favorable
flow off lake Michigan keeps clouds and flurries going. Will
continue SPS though the night for wind chills of zero to near ten
below zero.
Previous Discussion...
Surface high pressure off to our west has allowed for another day of
high temperatures in the teens with an upper level trough currently
moving over northern Michigan. As the shortwave exits east Sunday
morning low level flow will become more parallel to Lake Michigan
with the GFS and NAM trying to hint at some flurries possible across
our northern zones. The RAP also tries to hint at this but low level
saturation is only around 2000 ft. Given this have left mention of
flurries out of the forecast for now. Lows Sunday morning will
likely again be in the single digits. Wind chill reading Sunday
morning are again forecasted to be between zero and 10 degrees below
zero. Looks like winds and wind chill values will be below advisory
thresholds so will continue to advertise hazard with Special Weather
Statement.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY/...
Sunday morning the shortwave trough will quickly be pulling east
with any flurries across our northern zones coming to an end. 850 mb
temperatures behind the shortwave fall back towards 20 degrees below
zero across our eastern zones in the morning before slowly
rebounding Sunday afternoon. Given the snow pack on the ground and
mixing to only ~925mb have kept forecast high temperatures on the
low end of guidance.
Sunday evening Arctic high pressure will start to pull east and move
overhead. By Monday morning the center of the Arctic high will
already be over the eastern seaboard with southwesterly flow
returning to the area. This southwesterly flow will likely help to
keep temperatures from falling to much Monday morning. Monday
afternoon the warm up will be in full swing as the upper level
trough axis exits east and mid level heights starts rising across
Ohio. 850 mb temperatures will respond by rising to only 5 degrees
below zero (on both the GFS and ECMWF). 1000/850 mb thicknesses also
rise to around 1280m (supported on the GFS/ NAM with slightly higher
values on the ECMWF). Clouds will also be on the increase Monday in
the form of cirrus as the upper level jet moves overhead. Even with
cirrus overhead though am expecting high temperatures to reach and
be slightly be above freezing Monday for the first time since
January 4th.
&&
.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
A warm front will lift north across the region Monday Night into
Tuesday in a developing WAA/isentropic lift pattern. The initial shot
of isentropic lift will work its way southwest to northeast across
our area late Monday evening and then into the overnight hours
Monday night. The low levels will start out fairly dry but will
moisten up through the early morning hours. By this time the best
forcing should be across northern portions of our fa so will range
pops from likely north to chance across the south for Monday night.
Ptype will likely be an issue Monday night as we will initially be
cold enough to support primarily snow. This could lead to some light
snow accumulations of mainly less than an inch across our northern
areas. However, as we warm up aloft, expect a transition to liquid
pcpn and this could lead to a period of freezing rain. In the
developing WAA, surface air temperatures will slowly rise above
freezing, but there is some concern that surface objects/roads could
remain below freezing for a longer period due to the extended cold
period preceding this event.
Good moisture advection and isentropic lift will then continue
Tuesday into Tuesday night across the region in the persistent
southwesterly flow pattern. This will result in an extended period
of rain for Tuesday into Tuesday night so will continue with high
pops through that period. A cold front will push in from the west
later Tuesday night and into Wednesday morning. This will allow for
some drier air to briefly work into the area during the day on
Wednesday. Temperatures will be somewhat non diurnal given the WAA
out ahead of the front. Highs on Tuesday will be in the 45-50 degree
range with lows Tuesday night fairly steady until the front moves in
later Tuesday night and into the day on Wednesday. Highs on
Wednesday will range from the mid to upper 30s northwest to the
lower 50s southeast but this will ultimately be dependent on the
timing of the cold front.
We will quickly transition back to a southwesterly flow/WAA pattern
Wednesday into Thursday. This will lead to an increasing chance of
precipitation later Wednesday afternoon into Wednesday night and
then continuing through the day on Thursday. Some model timing and
placement differences arise by this time in the forecast though but
it does look like pcpn chance could even linger into the day on
Friday. This could eventually lead to some flooding concerns as we
get into the later part of next week. Highs on Thursday will be in
the 50s to possibly lower 60s but become more uncertain by Friday
depending on the timing and placement of the next wave of
precipitation.
&&
.AVIATION /03Z SUNDAY THROUGH THURSDAY/...
Mid level shortwave to pivot thru the Great Lakes overnight. Low
level flow will allow low clouds over Indiana to push across the
northern TAF sites overnight. These clouds to result in CIGS
between 2500 and 3500 feet, so expect MVFR conditions at times.
In the wake of this s/w Flow becomes favorable off of Lake
Michigan, which will result in continued clouds across all but
KCVG and KLUK on Sunday. Expect these low clouds to diminish
Sunday afternoon with high level clouds streaming in from the
west.
OUTLOOK...MVFR ceilings and visibilities are possible along with
mixed precipitation from Tuesday through Wednesday.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...None.
KY...None.
IN...None.
&&
$$
SYNOPSIS...Haines
NEAR TERM...Haines/AR
SHORT TERM...Haines
LONG TERM...JGL
AVIATION...AR
Area Forecast Discussion
National Weather Service Marquette MI
656 PM EST Sat Jan 7 2017
.SHORT TERM...(This evening through Sunday)
Issued at 401 PM EST SAT JAN 7 2017
WV imagery and RAP analysis indicated a mid/upper level trough from
Hudson Bay into the western Great Lakes. At the surface, low pres
was located near the Sault with a trough extending to the west
through se Lake Superior. Radar and vis loop indicated nw flow weak
to moderate intensity multiple wind parallel LES bands across the
cwa in the very cold arctic airmass. 700-300 mb qvector conv ahead of
a shrtwv near the mid level trough axis brought an increasein the LES
through the area this morning into the early afternoon, especially
where the low level conv was strongest along the wind shift to nw.
The heavier LES bands remained over the east downwind of the longer
fetch. In addition, gusty winds to 35 mph were producing considerable
blsn in open areas.
Tonight, with the qvector div and subsidence dominating in the wake
of the shrtwv, lowering inversion heights to 4k-5k ft will bring a
decrease in LES intensity. In addition, a relatively shallow DGZ
will also limit accumulations. However, very low vsby and gusty
winds will continue at least through this evening. So, the LES
advisories were extended over the northwest and from Alger eastward
through tonight or early Sunday. The best chance for signficant
accumuations is from P53 eastward where lake induced troughing and
associated low level conv will be strongest. Some locations could see
another 5 to 7 inches, with 2 to 4 inch amounts more common.
Sunday, mid level and sfc ridging sliding through the region will
bring backing winds to the sw and move any remaining LES bands
offshore by early afternoon. With increasing mid/high clouds and
increasing WAA, expect temps to climb back into the teens.
.LONG TERM...(Sunday night through Saturday)
Issued at 408 PM EST SAT JAN 7 2017
Upper trough over eastern Canada across much of the eastern Conus
this weekend lifts more over northern Canada early this week as
strong jet stream pounding in off Pacific temporarily flattens flow
aloft across the Conus. As the trough lifts north, there is one last
shortwave dropping through in NW flow that could bring light snow to
mainly north and east Upper Michigan Sun night. Soundings show deep
dgz may be able to squeeze out a couple inches of snow, especially
north in an overall high pop/low qpf setup.
Next chance of snow arrives Mon night as warm air advection,
especially h85-h7 spreads from the Plains to the western Great Lakes
ahead of shortwave trough sliding over the Rockies and northern
Plains. With strongest low-level warm air advection and isentropic
lift staying south of Upper Michigan, expect the snow Mon night to
stay mainly south as well. Some light snow is possible though.
Better chance for moderate snow will be on Tue as the shortwave and
associated sfc low lift across the Upper Great Lakes. H7-h5 q-vector
convergence with the shortwave and moisture advection with mixing
ratios 3-4g/kg indicate consensus model qpf of 0.25-0.40 inches is
on track. SLRs less than 20:1 along with expected qpf points to
possible advisory event for parts of cwa. Morning commute on Tue
could be affected so there may be higher impact. Once the sfc low
slides by piece of colder air (h85 temps -13c on Tue night down to
-19c on Wed) in mainly W flow aloft will plow across Lk Superior and
Upper Michigan. W-WNW flow lake effect should get going and
increased pops over consensus for those favored flow areas Tue night
into Wed. Also included blowing snow mainly across Keweenaw and
along Lk Superior east of Munising as wind gusts there could reach
40 mph.
Another low pressure system lifts across western Great Lakes Wed
night through Thu. Due to the quick zonal flow in place across the
Conus this system does not look to get too wrapped up and greatest
moisture will stay across lower Great Lakes region. Still could see
light snow accumulations up to a few inches and depending on timing
the morning commute on Thu could be affected by the snow leading to
a higher impact. At least that is how it looks attm. Late in the
week into next weekend another upper low and associated expanding
mass of cold air currently over Arctic Ocean drops south across
central Canada, coming as close as Northern Ontario by Fri and Sat.
Should see a cold shot during that time as h85 temps drop to around
-24c, but bitter cold air with h85 temps lower than -30c should stay
north of Upper Great Lakes. More lake effect expected over most of
the northern U.P. as WNW winds gradually become NNW. Increased pops
over consensus for Thu into Fri for the expected lake effect.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 655 PM EST SAT JAN 7 2017
Lake effect snow showers will diminish and end during this fcst
period as very cold air mass moderates and winds back with passage
of sfc high pres ridge. At KIWD, MVFR conditions, and at times brief
IFR this evening, will give way to VFR late tonight as backing winds
push lake effect to the n of the terminal. VFR conditions will then
prevail thru Sun aftn. At KCMX, LIFR conditions in shsn/blsn should
prevail for much of this evening. Expect improvement to IFR
overnight, MVFR Sun morning, then VFR Sun aftn as backing winds push
lake effect to the n of the terminal. At KSAW, MVFR conditions and
some flurries should return early this evening before returning to
VFR overnight. VFR conditions will prevail during Sun.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 401 PM EST SAT JAN 7 2017
NW gales into the early evening will diminish as the pres gradient
weakens behind an upper disturbance. SW winds will increase again
Sun night to 30 knots with some gale gusts possibl but will then
diminish to less than 25 kts while becoming variable on Mon. SE
winds increase to 30 kts on Tue ahead of a low pressure system
lifting toward the Great Lakes region. Winds shift to NW to 35 kts
later Tue into Wed. Expect heavy freezing spray into Sunday morning.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
Lake Effect Snow Advisory until 7 AM EST Sunday for MIZ001>003.
Lake Effect Snow Advisory until 10 AM EST Sunday for MIZ006-007-
085.
Lake Superior...
Heavy Freezing Spray Warning until 7 AM EST Sunday for
LSZ248>251-265>267.
Gale Warning until 7 PM EST this evening for LSZ248>251-265>267.
Heavy Freezing Spray Warning until 4 AM EST Sunday for LSZ243-
244-264.
Heavy Freezing Spray Warning until 1 AM EST /midnight CST/
Sunday for LSZ241-242-263.
Lake Michigan...
None.
&&
$$
SHORT TERM...JLB
LONG TERM...JLA
AVIATION...Rolfson
MARINE...JLB
Area Forecast Discussion
National Weather Service Spokane WA
623 PM PST Sat Jan 7 2017
.SYNOPSIS...
A more active weather pattern arrives tonight and Sunday, and
continues through the middle of next week, with several rounds of
snow. The snow may mix with rain or a wintry mix at times across
southeastern Washington. Look for dry but potentially chilly weather
to return by Thursday and continuing through the work week. A
chance of snowy weather will then return for next weekend.
&&
.DISCUSSION...
Another update to speed up the timing of the end of the snow even
more. Based on the latest HRRR and NAM runs along with the current
radar, it appears that the snow will end in Wenatchee/Moses Lake
by 7pm, Spokane around 10pm, and most of the Panhandle by 1am.
Forecast snow amounts still look good. RJ
&&
.AVIATION...
00Z TAFS: Widespread IFR conditions are expected to impact all sites
this evening as a broad band of snow moves through the region.
Although it has not started at GEG-SFF-COE yet...it won`t be long as
the radar is filling up quickly with echoes. The one spot which will
likely avoid IFR conditions this evening will be LWS as the snow is
slow to reach the ground due to downslope flow. Nonetheless chances
are good that MVFR conditions will develop as snow becomes more
likely. The snow will end across MWH-EAT between 03-05z and between
06-08z for the remainder of the sites. What happens after that is
low confidence. There are some hints that low clouds which develop
with the snow will persist, especially for GEG-SFF-COE and possibly
MWH resulting in IFR conditions. Dry weather will then persist into
SUN, but the snow should return to all site except PUW/LWS by
afternoon with more IFR conditions. The latter two sites will see
rain rather than snow, so visibility conditions should be much
better than the other sites. fx
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 16 29 29 31 21 29 / 90 70 100 50 40 40
Coeur d`Alene 18 29 29 32 21 31 / 90 60 100 60 50 40
Pullman 20 35 31 34 25 32 / 100 80 90 70 50 40
Lewiston 22 38 34 37 27 35 / 80 50 80 60 30 30
Colville 17 27 25 31 20 27 / 90 50 100 30 40 30
Sandpoint 18 28 28 32 24 29 / 90 50 100 60 60 40
Kellogg 20 32 30 32 22 29 / 90 50 100 80 60 50
Moses Lake 16 27 20 31 16 29 / 100 100 80 20 20 20
Wenatchee 13 20 20 29 18 26 / 100 100 90 20 20 30
Omak 11 22 21 31 16 25 / 80 90 100 20 20 20
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...Winter Weather Advisory until 8 AM PST Monday for Central
Panhandle Mountains-Coeur d`Alene Area-Idaho Palouse-Lewis
and Southern Nez Perce Counties-Lewiston Area-Northern
Panhandle.
WA...Winter Weather Advisory until 8 AM PST Monday for Lower Garfield
and Asotin Counties-Moses Lake Area-Northeast Blue
Mountains-Northeast Mountains-Okanogan Highlands-Spokane
Area-Upper Columbia Basin-Washington Palouse.
Winter Storm Warning until 4 AM PST Monday for East Slopes
Northern Cascades-Okanogan Valley-Waterville Plateau-
Wenatchee Area.
&&
$$
Area Forecast Discussion
National Weather Service Pueblo CO
326 PM MST Sat Jan 7 2017
.SHORT TERM...(This evening through Sunday)
Issued at 326 PM MST Sat Jan 7 2017
Currently...
Temps have warmed up on the lee of the mtns and across the higher
elevations of the mesas/divides. Temps at 2 pm were in the L30s
across the Palmer Divide...mid 30s across eastern Fremont county and
around 30F in Springfield. At lower elevations (lower ark rvr vly)
temps were still in the teens. The Large valleys were quite cold at
Alamosa was still in the low single digits and the Gunnison Valley
was still below zero.
High cloudiness was advancing across the region...and high cirrus
was located at nearly all locations. The cirrus deck was thicker the
farther west you go.
Over the west slope, radar was indicating precip, although this was
likely virga.
A very wet pacific storm system was moving onshore along the CA
coast.
Tonight...
More mtn snows are on the way. Snow showers will develop this
evening and become more widespread along the divide later tonight.
Overall accum will be light, with generally 1-2 amounts likely,
especially across the c mtns. Over the remainder of the region,
expect dry conditions.
Winds will be on the increase tonight specially across the higher
terrain, and this will keep temps up on the east slopes.
Additionally, with the higher clouds moving in, temps will not get
nearly as cold, especially across the San Luis Valley (SLV) were
lows should only reach down to about -10F. If the clouds do thicken
up, then the lows in the SLV may even be warmer.
Some fog will be possible across the plains tonight, especially
along the lower ark rvr valley from PUB eastward to the KS border.
Tomorrow...
Steady light snow is expected to continue across the central mtns
through the day. Gusty west winds will continue across all of the
higher terrain with values reaching into the 35-45 mph range. Winds
in the larger valleys and plains will remain light. Temps will warm
up significantly across the region and expect 40s across all of the
plains with a few 50s on the east slopes of the s mtns. Valleys
should get into the 20s and 30s. /Hodanish
.LONG TERM...(Sunday night through Saturday)
Issued at 326 PM MST Sat Jan 7 2017
Very similar weather pattern in place through the extended period,
but broke up the extended into two groupings to try and better
describe confidence levels.
Sunday Night through Tuesday...As the upper ridge axis crosses the
Four Corners earl Sunday evening, the flow aloft becomes more west
to southwest and moisture pours into western Colorado. Models have
been very consistent in bringing significant snowfall amounts to the
Contdvd from Sunday night through late Monday night, so decided to
hoist a Winter Storm Watch there. Slightly lower elevations of the
central mts and western San Luis Valley will likely see advisory
snowfall amounts, but can hold off for a few more model runs before
making that decision. In addition, increasing westerly flow aloft
coupled with mt-top stability layer indicates a strong potential for
strong, gusty winds across the eastern mts Sunday night through
about midday Tue. Therefore, went ahead and issued a High Wind Watch
for the eastern mts for that time period as gusts of around 75 mph
are possible, and later forecast shifts can modify.
Increasing winds and cloud cover should help to keep the overnight
temps from dropping too low, though the existing snow cover plays a
big part in that. Aftn high temps are forecast to remain in the 30s
to lower 40s for the high valleys, and 50s to around 60F for the
eastern plains.
Wednesday through Saturday...Long range models continue to keep an
unsettled pattern in place for the state, so a nearly constant
stream of moisture and periods of snow for the Contdvd is expected.
There is a system or disturbance that will affect Colorado on
Friday, depending on which model is to be believed. GFS remains
progressive, while the EC digs a system slower and further south for
Fri, offering a good chance for some snow to all of the forecast
area, including the eastern plains. For now will forecast high temps
in the 40s and 50s for the plains, and 30s for the high valleys,
with Fri expected to be the coldest day of the extended period.
Moore
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 326 PM MST Sat Jan 7 2017
KCOS...VFR conditions are anticipated during the next 24h. Winds
will be light.
KPUB and KALS...main concern will be fog potential with some melting
occurring today. HRRR guidance clearly shows fog potential for
tonight. Main concern will be high clouds which may decrease the
chance for fog development. Given the hi-res guidance, will mention
fog tonight.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
High Wind Watch from Sunday evening through Tuesday morning for
COZ072>075-079>082.
Winter Storm Watch from late Sunday night through late Monday
night for COZ058-060-066-068.
&&
$$
SHORT TERM...HODANISH
LONG TERM...MOORE
AVIATION...HODANISH
Area Forecast Discussion
National Weather Service Raleigh NC
925 PM EST Sat Jan 7 2017
.SYNOPSIS...
Arctic high pressure will build across the Middle Atlantic states
tonight through Monday, then move off the coast Monday night into
Tuesday.
&&
.NEAR TERM /THROUGH TONIGHT/...
As of 925 PM Saturday...
...Winter Weather Advisory for Hazardous Travel Conditions in Effect
Through Noon Tuesday...
Our winter storm is long off the Mid-Atlantic coast, leaving a swath
of snow and a snow/sleet mix across much of central NC. The
heaviest snow, anywhere from 4 to 10 inches, fell north and west of
a line from southern Davidson Co to Chapel Hill/Durham to Roanoke
rapids. Trying to figure out how the snowpack will impact overnight
lows has been tough, especially as the SLP gradient weakens in
response a lee trough/ridge downstream of the mountains and
radiation cooling. Winds will be generally be light at 4-8mph,
but may go calm on some areas in the western Piedmont, per RAP
guidance, which will allow temps to reach the single digits. NAM 2m
temps seem to reflect the snowpack the best, although they may be
too low. A blend of NAM and NAM MOS seems to yield the most
reasonable results; 4-8 over the snow covered areas and 10-15
elsewhere. Wind chills values may dip to near 0 or even slightly
below. See the Climate section below for info on record min temps.
&&
.SHORT TERM /Sunday through Monday night/...
As of 230 PM Saturday...
...Bitterly cold air arriving...
A fairly simple weather pattern will have a significant impact as it
brings dangerously cold temps into early next week. Arctic high
pressure will build in from the west, settling overhead early Mon
morning before starting to drift to our east Mon night. The axis of
the mean trough will be situated along the East Coast early Sunday
but will then swing east and offshore, inducing height rises in its
wake over NC. All of this will result in a sinking and very dry
column. The exception will be Sun night into Mon morning when one
last weak shortwave will drop SE through the Carolinas, bringing a
batch of high clouds across the area. The very cold temperatures
will remain the big story for the next few days, with thicknesses of
50-75 m below normal and decent radiational cooling conditions each
night. Expect chilly highs Sun of 24-30. Statistical guidance
supports lows Sun night from around 0 to 14 above, with the coldest
readings in the outlying areas across the north and northeast. (See
climate section below for record lows and record low max temps.)
Projected thicknesses along with guidance trends suggest highs in
the upper 20s to lower 30s Mon, affording little to no melting of
the snow/sleet. Lows will be a bit moderated Mon night as the high
begins to shift offshore with thicknesses climbing out of the abyss.
lows 12-22. -GIH
&&
.LONG TERM /Tuesday through Saturday/...
As of 310 PM Saturday...
A pattern change is on the horizon as the mean longwave trough
dampens and swings out over the Atlantic, supplanted by a building
ridge over and just off the Southeast and FL coast. This will mean a
trend toward warming temps, with above normal readings from mid week
on through the end of the week, as the offshore-tracking ridge and
southwesterly low level flow as it departs draws in milder air.
We`ll see increased overrunning moisture atop the lingering surface-
based cool pool Tue into Tue night with 850 mb SW winds
strengthening to 40-50 kts. This increase in clouds will help hold
temps down in the 40s Tue (except 50-53 extreme SE), but will limit
the typical diurnal drop Tue night, when lows should be in the mid
30s to lower 40s, with a slight chance of light rain possible,
mainly across the NW CWA where upglide will be most pronounced. Most
of the forecast area should get into the warm sector Wed, with the
exit of this initial 850 mb jetlet off the Northeast coast bringing
a lull in overrunning atop the stable pool, rendering it vulnerable
to dissolution from atop and along the edges. But this won`t take
place until later in the day, so have held a bit under ECMWF
statistical guidance for highs, staying with upper 50s to lower 60s.
Much above normal temps, with a periodic risk of showers mainly
across the NW CWA, will continue through Sat as we remain within
southeast to southerly low level flow with above normal heights
aloft. -GIH
&&
.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
As of 715 PM Saturday...
Earlier sub-VFR conditions and precipitation have now moved E of
central NC, as the parent low pressure system has tracked up the
Middle Atlantic coast. Atypically strong arctic high pressure will
build across NC through Mon, with an associated high probability
of dry, VFR conditions through early next week.
Outlook: Return flow around the arctic high, once the high moves
offshore Mon night-Tue, will yield a chance of low stratus and/or
fog Tue morning.
&&
.CLIMATE...
Upcoming record daily minimum temperatures...
Greensboro (KGSO)
January 8...6 set in 2015
January 9...2 set in 1970
Raleigh/Durham (KRDU)
January 8...7 set in 1970
January 9...0 set in 1970
Fayetteville (KFAY)
January 8...13 set in 2015
January 9... 9 set in 1970
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until noon EST Tuesday for NCZ007>011-
021>028-038>043-073>078-083>086-088-089.
&&
$$
SYNOPSIS...MWS
NEAR TERM...Vincent/Smith
SHORT TERM...Hartfield
LONG TERM...Hartfield
AVIATION...MWS
CLIMATE...RAH