Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/23/18
Area Forecast Discussion
National Weather Service Bismarck ND
926 PM CST Thu Nov 22 2018
.UPDATE...
Issued at 918 PM CST Thu Nov 22 2018
03Z surface observations and NDDOT road cameras show dense fog
becoming more widespread from the James River Valley west to the
Missouri River. Expanded the Dense Fog Advisory to include
Burleigh/Emmons/Kidder counties.
Through the early morning hours, a west to east deterioration of
dense fog is likely as the weak surface trough moves east. Hi-res
models indicate fog coverage decreasing in Burleigh/Emmons
counties by 12Z and our areas of the James River Valley by the
late morning hours.
UPDATE Issued at 545 PM CST Thu Nov 22 2018
Blended observations with going forecast, otherwise no other
changes.
UPDATE Issued at 413 PM CST Thu Nov 22 2018
Update to issue a Dense Fog Advisory for our southeast, mostly the
James River Valley area. Visibilities have dropped below one mile
at KJMS and are decreasing on NDDOT road cameras near Ashley and
Kulm. Expect conditions to continue to deteriorate through the
night.
&&
.SHORT TERM...(This evening through Friday)
Issued at 220 PM CST Thu Nov 22 2018
Forecast highlights in the short term period will be lingering fog
south central and east.
Currently, upper level ridge continues to push east with southwest
flow aloft across the region. Despite ample mid level WAA, strong
low level inversion/low mixing heights preventing the warm air
aloft from reaching the surface for all but the higher terrain of
southwest North Dakota. Thus widespread upper 20s to low 30s with
the exception of the southwest where temperatures are currently in
the mid 40s to low 50s. High res models this morning showed the
fog lingering across the James River Valley, but did not depict
the fog persisting as long as it has south central. Adjusted
accordingly using a blend of the RAP and CONSSHORT. This keeps the
fog across south central and southeast through the evening, then
slowly pushing the fog east overnight through mid morning Friday.
Flow aloft becomes westerly Friday with another shortwave and
surface cold front starting to push through. 850mb isotherms are
packed together a bit more with northwest winds and cold air
advection taking control Friday afternoon. The NAM having the
stronger shortwave is the only model that develops precipitation
Friday. For now, have maintained a dry forecast based on all other
guidance being dry. Highs Friday will range from the mid 30s
north to the mid 40s southwest.
.LONG TERM...(Friday night through Thursday)
Issued at 220 PM CST Thu Nov 22 2018
A stronger cold front moves from north to south late Friday night
through Saturday morning. Behind this frontal passage, much
stronger cold air advection along with a chance of snow. Highs
will mainly be in the 20s.
Following the passage of Saturday mornings shortwave/surface cold
front, a northwest flow aloft becomes established through
Tuesday night as deep low pressure forms over southern Ontario
then slowly moves south over the Great Lakes mid-week. Embedded
S/WV`s rotating around the low will bring chances for light snow
to the area until a shortwave ridge builds into the region
Wednesday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 545 PM CST Thu Nov 22 2018
LIFR to IFR conditions at KBIS will improve to VFR by 10Z. KJMS
will stay LIFR into Friday morning. Expect VFR cigs/vsbys through
the TAF period at KISN/KDIK/KMOT. A weak cold front will push
through after 06z Friday with a subtle wind shift to the west.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
Dense Fog Advisory until 8 AM CST Friday for NDZ035>037-046>048-
050-051.
&&
$$
UPDATE...AE
SHORT TERM...NH
LONG TERM...NH
AVIATION...AE
Area Forecast Discussion
National Weather Service Melbourne FL
1015 PM EST Thu Nov 22 2018
.DISCUSSION...
Analysis of the H100-H70 mean wind over FL reveals a weak trof
extending from just south of the Panhandle to just off the Volusia
County coast, with a weak closed circulation centered btwn Tampa Bay
and The Big Bend. Position of this trof axis suggests the ascending
flank is now over north FL, leaving little in the way of dynamic
support over central FL.
Indeed, the precip wedge over the Gulf Stream waters north of Cape
Canaveral has been experiencing significant trouble advecting
onshore this evng, most likely due to the limited support, as well
as a combination of low instability over the cooler shelf waters
north of the Cape. Furthermore, the onshore flow has shallowed over
the past several hrs...dropping from arnd 5KFT early this aftn to
arnd 3KFT at present, according to lcl wind profilers. In addition,
the 23/00Z KXMR/KTBW RAOBs show a very dry H85-H70 lyr with avg
dewpoint depressions btwn 15-20C...embedded within a 10KT S/SW flow
that will only advect this dry layer northward, further impeding any
precip from moving onshore.
A sharp precip gradient will persist overnight, but given the abv
scenario, PoPs over land will need to be reduced blo 50pct. Indeed,
neither the 6KM WRF or the 1KM HRRR are particularly bullish on
precip overnight. Will keep chc PoPs in the fcst from Cape
Canaveral/Coastal Volusia, slgt chc elsewhere. QPF also will need to
be reduced a bit. Min temp fcst arnd 60F looks reasonable given
mid/late evng readings largely in the M60s.
&&
.AVIATION...Thru 24/00Z.
Sfc Winds: Thru 23/12Z...N/NW bcmg N/NE 4-7KTS xcpt E/NE 5-8KTS
coastal sites N of KTIX. Btwn 23/12Z-23/15Z...bcmg E/NE 8-12KTS.
Btwn 23/15Z-23/18Z...bcmg E/SE 8-12KTS...coastal sites N of KTIX
ocnl sfc G18-22KTS. Btwn 23/21Z-23/24Z...N of KISM-KMLB bcmg E/NE 4-
7KTS...S of KISM-KMLB bcmg E/SE 3-6KTS.
WX/Vsbys/Cigs: Thru 23/12Z...VFR all sites cigs AOA FL120. Btwn
23/12Z-23/18Z...coastal sites cigs btwn FL040-060 slgt chc MVFR
shras. Aft 23/18Z...all sites cigs btwn FL040-060 chc MVFR shras.
&&
.MARINE...
Latest data buoy/C-Man obs indicate the wind surge impinging on the
lcl Atlc...St. Aug E/NE 15G25KTS, Buoy010 E/NE 25G30KTS, Daytona
Beach E/NE 10KTS, and Buoy009 N/NW 8KTS. Furthermore, the fcst high
seas have yet to advance as far west as advertised as Buoy009 was
still blo 4FT on the latest obs. Still anticipate large swells
pushing into the lcl Atlc overnight, but will need to cull the seas
back a bit into the predawn hrs. Winds also will need a downward
adjustment thru early AM, but will bring them up to arnd 20 knots
north of Sebastian Inlet by daybreak. No changes to the current
SCA/Gale warning configuration given the close proximity of the
strong winds just north and east of the lcl Atlc.
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...Small Craft Advisory until 4 AM EST Friday for Flagler Beach to
Volusia-Brevard County Line 0-20 nm-Flagler Beach to
Volusia-Brevard County Line 20-60 nm.
Small Craft Advisory from 7 PM Friday to 4 PM EST Saturday for
Flagler Beach to Volusia-Brevard County Line 0-20 nm-
Flagler Beach to Volusia-Brevard County Line 20-60 nm-
Volusia-Brevard County Line to Sebastian Inlet 0-20 nm-
Volusia-Brevard County Line to Sebastian Inlet 20-60 nm.
Gale Warning from 4 AM to 7 PM EST Friday for Flagler Beach to
Volusia-Brevard County Line 0-20 nm-Flagler Beach to
Volusia-Brevard County Line 20-60 nm-Volusia-Brevard County
Line to Sebastian Inlet 0-20 nm-Volusia-Brevard County Line
to Sebastian Inlet 20-60 nm.
Small Craft Advisory from 7 PM this evening to 4 AM EST Friday
for Volusia-Brevard County Line to Sebastian Inlet 0-20 nm-
Volusia-Brevard County Line to Sebastian Inlet 20-60 nm.
Small Craft Advisory from 4 AM Friday to 4 PM EST Saturday for
Sebastian Inlet to Jupiter Inlet 0-20 nm-Sebastian Inlet to
Jupiter Inlet 20-60 nm.
&&
$$
Bragaw/Weitlich
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
548 PM CST Thu Nov 22 2018
.SHORT TERM...(This evening through Friday)
Issued at 245 PM CST Thu Nov 22 2018
Main concern tonight is cloud trends and then timing of light rain
moving in mainly Friday afternoon.
Watching satellite and seeing continued erosion/drying of the
boundary layer to the southeast and southwest. We do like the
the latest HRRR which continues this clearing trend into the
evening. We may yet see clearing over most of central/southern
CWA into the early evening. Lower clouds will be slowest to clear
into the northern CWA. Highs clouds will work in from the west
overnight so becoming mainly cloudy again after midnight most
areas. Temperatures may drop a degree or two from late afternoon
readings but will likely steady to slowly rise overnight.
May see some fog develop before thicker clouds arrive over the
area late tonight but we are not expecting anything widespread or
dense at this time. The next trough moving across Idaho this
afternoon will move into the Dakotas by Friday morning. Moisture
increases from the south during the morning and we should see
light rain work in from the south through about midday. Will
continue categorical PoPs over the eastern CWA during the
afternoon. Warming is expected ahead of the through with Friday
highs ranging from 40 to 45 across the area.
.LONG TERM...(Friday night through Thursday)
Issued at 245 PM CST Thu Nov 22 2018
The extended period remains active, especially for the southern jet
stream which takes most of the active weather south of the Upper
Midwest. The split flow regime will continue to support uncertainty
in the forecast based on the consistencies in the models. These
uncertainties build further in time and hold onto the persistent
changes in the precipitation probabilities past Saturday.
There remains high confidence that precipitation will hold across
most of eastern Minnesota and western Wisconsin Friday night.
Thermal profiler in the lowest 5k in the atmosphere supports rain
vs. snow during the onset, and lasting through Friday evening. Not
until late Friday evening, and Saturday morning will temperatures
cool enough to support snow.
As the system on Friday night begins to slow down as it moves into
the Great Lakes, residual moisture wrapping around it will produce
lingering chances of light snow/drizzle or freezing drizzle Saturday
in central/east central Minnesota, as well as west central
Wisconsin. I wouldn`t be surprised to see further challenges for
Saturday night/Sunday if this system begins to get cut off from the
main jet stream to the south. This system will also lead to a
further southerly track of the storm system that will affect the
central CONUS Saturday/Sunday. Models have supported more run to run
consistency in the track of the heavy snow band from northern
Missouri/southern Iowa, and into northern Illinois.
The split flow regime may change some next week as a strong west to
east jet stream begins to develop across the Pacific Ocean, eastward
into the United States. Overall, temperatures will hold near or
slightly below normal through the middle of next week. Precipitation
chances will be highest Friday/Friday night.
The teleconnections still support a colder pattern through the first
week of December. The negative AO has a strong signal for this
support.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 548 PM CST Thu Nov 22 2018
Main uncertainty revolves around how far north clearing will make
it tonight. It`s got a pretty good head of steam, so brought VFR
conditions to all terminals, though AXN is the one place that may
hold on to them. MVFR and lower cigs will return Friday morning
ahead of a cold front. Rain will follow along the front during the
afternoon, though expect this rain to miss RWF/STC/AXN. Where rain
does occur, expect cigs to drop back to IFR.
KMSP...There will be some wind shear through the night, but looks
marginal, with 2k foot winds at about 40 kts, with around 40 degs
of directional change. Confidence is high in VFR conditions
remaining through the night, with a return to MVFR expected
between 14z and 18z.
/OUTLOOK FOR KMSP/
Sat...MVFR cigs. Wind WNW at 10 kts.
Sun...Mainly MVFR. Wind NNW 15G25kts.
Mon...MVFR. Wind NW 10G20kts
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
&&
$$
SHORT TERM...DWE
LONG TERM...JLT
AVIATION...MPG
Area Forecast Discussion
National Weather Service Marquette MI
641 PM EST Thu Nov 22 2018
.SHORT TERM...(This evening through Friday)
Issued at 255 PM EST THU NOV 22 2018
Water vapor imagery and RAP analysis show that the strong, mean
ridge that had been in the vcnty of the w coast of N America has
finally shifted e and is now over central N America in a weakened
state. As a result, waa regime is underway across the Upper Lakes
today. This waa/isentropic ascent has managed to squeeze out
-sn/flurries across the central and eastern fcst area. In
addition, retreating cold has still been sufficiently cold to
generate some light LES off Lake MI into portions of central Upper
MI under shallow se flow today. Temps have risen into the 20s
across the board. On a side note, Raco had a low of -21F this
morning, the lowest observed temp in Upper MI so far this cold
season.
Band of mid-level, moist isentropic ascent producing the
-sn/flurries will shift e of the area over the next few hrs. This
will result in the mid levels drying out from w to e. Meanwhile,
shallow low-level, moist isentropic ascent will continue tonight,
aided by moisture off Lake MI under shallow sse flow. With temps in
this low-level moist layer rising above -10C, lack of ice nuclei
means ptype will transition to only -fzdz from w to e for any pcpn
that occurs late aftn thru tonight. It`s uncertain how widespread
the -fzdz might be or what the intensity will be, but believe models
generating several hundredths of an inch of pcpn are likely
overdone. Fcst will maintain -fzdz mention across the central and
eastern fcst area tonight, but no headline. If it becomes apparent
that -fzdz will become widespread as the evening progresses,
headline will need to be reassessed. Downsloping near the Lake
Superior shore will likely prevent any pcpn concerns at locations
such as Marquette and Munising. Low clouds and continued waa will
result in slowly rising temps thru the night. Most locations will
likely be just above freezing at sunrise Fri.
With low-levels continuing to warm, moisture added by flow across
Lake MI will gradually diminish overnight thru Fri, and with fcst
soundings showing the low-level moisture becoming increasingly
shallow, any lingering -dz/-fzdz will end early Fri morning. Then,
it looks like a dry day under rather pronounced dry column above the
moisture confined to the bottom 2-3kft of the troposphere. Remains
to be seen if shallow low clouds will scatter out, but best
potential of seeing some sunshine develop will be in areas where
southerly winds are a downsloping wind. Shortwave trof moving out
across the Plains will spread forcing/deepening moisture toward the
area late in the day. Might see some -ra reach the far just before
00z Sat. Although it will be a warmer day with temps rising into the
upper 30s to mid 40s, gusty winds will keep conditions from
feeling as warm as temps indicate.
.LONG TERM...(Friday night through Thursday)
Issued at 315 PM EST THU NOV 22 2018
After a brief period of warmer weather Friday into Saturday, large
scale troughing is likely to dominate the Upper Great Lakes through
the majority of the longer term. Temperatures will return to below
normal Sunday through much of next week, and little if any sunshine
is expected. There are some hints in the GFS and CMC of a brief
period of ridging and subsequent warming late next week, but the
ECMWF has not latched onto this solution just yet.
A shortwave approaching the region from the west will bring
precipitation into the far western CWA Friday evening, overspreading
much of the area overnight and gradually exiting during the day
Saturday. Temperatures will be warm enough to support rain at most
locations, but some snow is likely to mix in over the interior west
with minor accumulations near the WI border. A strong LLJ will be in
place, and some breeziness is likely Friday night over the east
half, especially along the Lake Michigan shoreline, however a strong
inversion is likely to limit mixing potential until it weakens in
the late evening.
Sunday morning, 850 mb temperatures will begin to cool and inversion
heights will rise, and eventually the environment will become
supportive of NW flow lake effect. A secondary shortwave rotating
around the low centered over Ontario may also enhance lift through
the AM hours. Current forecast soundings are leaning towards the
moist layer remaining too warm for ice nucleation over much of the
interior west Saturday night and Sunday, so some light freezing
drizzle has been added to the forecast. When precip initiates and
just how much falls will depend on the track of the vigorous low
expected to pass to our south and east. Despite the GEFS ensemble
mean still bringing significant precip to the eastern UP with this
system, the deterministic GFS (and EC/CMC) have trended away and we
will likely miss out on system snow here in Upper Michigan.
Heading into Monday and Tuesday, N to NW flow LES will become a
little more vigorous. Headlines during this time frame cannot be
ruled out. Some moisture may wrap around the aforementioned low
later on Tuesday and enhance the snowfall over the area, but there
is still ample uncertainty in this period and is is possible that
moisture all gets carried too far east. The evolution of the wind
field into the middle of next week will have a profound effect on
where snow sets up as well as whether or not LES continues into
Wednesday, but there is some general agreement in diminishing
snowfall chances through the day Wednesday as ridging tries to
creep eastward into the region.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 641 PM EST THU NOV 22 2018
Ceilings borderline MVFR/IFR at KIWD and low-end MVFR at KCMX this
evening. With SE flow early on at KIWD shifting S, IFR conditions
will be limited due to downslope flow, however cannot completely
rule out brief periods of IFR ceilings there over the next few
hours. KCMX should escape IFR ceilings due to winds shifting more
southerly with time, which is not favorable for IFR ceilings. IFR
cigs are likely to develop at KSAW thanks to weak but moist upslope
flow. Some -FZDZ may develop at KSAW later this evening and continue
into the early daytime hours Friday. Kept mention of LLWS at KIWD
where inversion will be lower, but will continue to monitor KCMX and
KSAW for potential of adding in LLWS at those sites later tonight.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 255 PM EST THU NOV 22 2018
Tight pres gradient btwn strong high pres to the e and a low pres
trof moving out over the Plains will result in southerly gales of 35-
40kt over the e half of Lake Superior tonight. Winds over the w half
should mostly be in the 20-30kt range, though some gale gusts may
occur btwn the Keweenaw and Isle Royale. Winds will diminish a
little on Fri, but some gale gusts may linger over the e half of the
lake. Winds will then diminish to mostly under 20kt on Sat as the
Plains low pres trof arrives. As the trof departs, winds will
increase again Sat night/Sun out of the N to NW, probably into the
20-30kt range. As low pres moves ne toward the Lower Great Lakes on
Mon, winds will increase some, with possible gale force gusts at
least over the e half of Lake Superior. Winds will then diminish
slightly on Tue.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
Gale Warning until 4 AM EST Friday for LSZ267.
Gale Warning until 4 AM EST Friday for LSZ244-245-264>266.
Lake Michigan...
None.
&&
$$
SHORT TERM...Rolfson
LONG TERM...KCW
AVIATION...RJT
MARINE...Rolfson
Area Forecast Discussion
National Weather Service San Francisco Bay Area
334 PM PST Thu Nov 22 2018
.SYNOPSIS...Scattered showers tapering off this morning with a
brief period of dry weather expected late morning. The next
system is then expected to bring additional rainfall to the area
beginning this evening and continuing through Friday, and will
bring gusty winds to parts of the area. Dry weather is expected
over the weekend before rain chances return by the middle part of
next week.
&&
.DISCUSSION...as of 1:36 PM PST Thursday...KMUX radar is still
showing a couple of echos across Santa Cruz county but there are
fewer than earlier. Off to the north, the precursors to next
system can be seen over the coastal waters north of Point Reyes.
Rainfall from this next system is on track to arrive in the North
Bay later this afternoon and this evening, and spread across the
Bay Area tonight, and farther south into Monterey and San Benito
counties on Friday. Ahead of this system, southerly winds will
ramp up, especially across the North Bay where a wind advisory has
been posted beginning this evening. he strongest winds are
forecast to occur across the Sonoma and Marin coasts, as well as
the North Bay Mountains where sustained southerly winds are
forecast to reach 20 to 30 mph with gusts of 35 to 50 mph. Winds
won`t be as strong in the North Bay Valleys, but nonetheless
impactful at 15 to 25 mph with gusts of 30 to 35 mph.
The higher elevations are expected to see the most rainfall with
an additional 2-4 inches in the North Bay Mountains, 1.5-3 inches
in the Santa Cruz Mountains, and 0.75-1.5 inches in the Santa
Lucias. For the population centers, the North Bay Valleys can
expect about 1-2 inches of new rainfall, around 0.75-1.25 inches
along the San Francisco Peninsula, 0.5-1.25 inches in the East
Bay, and generally less than 0.5 inches in the rain-shadowed Santa
Clara and Salinas Valleys.
High pressure will build in over the state bringing dry weather to
the area over the weekend and into early next week. More rain is
expected beginning on Tuesday when more storms move through.
Unsettled weather is expected to continue across the region into
the final week of November.
&&
.AVIATION...As of 03:34 PM PST Thursday...For 00z tafs. Radar
shows showers over the North Bay with cigs currently between 2,000
and 10,000 feet across the region. Expect reduced cig heights and
vis to MVFR/IFR with passing heavy showers this afternoon and
evening before cigs lower overall tonight. Shower chances will
continue on and off through the forecast period. Gusty southerly
winds are expected tonight and into tomorrow morning with possible
LLWS at the North Bay taf sites when surface winds weaken but
remain gusty aloft.
Vicinity of KSFO...Currently VFR. Cigs will gradually lower
heading into this evening and overnight with increasing southerly
winds and rain. The latest HRRR run shows a period of heavy rain
possible between 03Z-09Z tonight. Gusty winds are expected
tomorrow afternoon.
SFO Bridge Approach...Similar to KSFO.
Monterey Bay Terminals...VFR through the evening before gradually
lowering cigs and increasing winds. Rain is expected on and off
starting late tonight.
&&
.MARINE...as of 01:43 PM PST Thursday...A second storm system
will rapidly descend across the coastal waters this afternoon and
evening in the wake of yesterdays storm system. Expect increasing
south to southwest winds ahead of the frontal passage through the
coming hours. Occasional gale force gusts will also be possible
through the Golden Gate Gap and into the northern San Francisco
Bay through tomorrow afternoon. Moderate westnorthwest swell today
with steep fresh swell from the gusty southerly winds.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
.Tngt...Wind Advisory...CAZ505>507
SCA...Pigeon Pt to Pt Pinos 0-10 nm from 6 PM
SCA...Pt Arena to Pt Reyes 0-10 nm
SCA...Pt Arena to Pigeon Pt 10-60 nm
SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm from 6 PM
SCA...Pt Reyes to Pigeon Pt 0-10 nm
SCA...SF Bay until 4 PM
SCA...SF Bay from 3 AM
GLW...SF Bay until 3 AM
&&
$$
PUBLIC FORECAST: Sims
AVIATION: AS
MARINE: DRP
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Area Forecast Discussion
National Weather Service Spokane WA
448 PM PST Thu Nov 22 2018
.SYNOPSIS...
Rain and mountain snow will arrive across the Pacific Northwest in
time to impact travel for the Thanksgiving holiday. Mountain
passes will likely experience accumulating snow tonight and
Friday. The potential for heavy mountain accumulations Friday
night into Saturday has prompted Winter Storm Watches for many
passes across the Pacific Northwest.
&&
.DISCUSSION...
Late afternoon update: Updated the forecast to lower snow levels
around Wenatchee, Ephrata, and Quincy where web cameras and
observations show snow as the dominante precipitation type. Could
see up to an inch of wet snow in these areas. Meanwhile
rain/freezing rain is occurring in Moses Lake so the wet/white
line lies just to the north and west of Moses Lake. The HRRR shows
this band of precipitation lifting north and east of these areas
between 6 and 7 PM. JW
&&
.AVIATION...
00Z TAFs: The next weather system will bring increasing
precipitation to Central WA through 03z and then across Eastern
WA/N Idaho 02-06z. This will mostly fall as rain at the TAF sites
although lingering cold air at KEAT/KMWH will result in freezing
rain, mixed with snow at KEAT. With pavement temperatures in the
area above freezing per WADOT road temperatures the runways may
remain wet but icing on some surfaces is possible with air
temperatures near 32F. After precipitation ends a moist boundary
layer and light surface winds could allow fog to redevelop at
KEAT/KMWH while upslope southwest boundary layer winds should
result in MVFR stratus at KGEG/KSFF/KCOE. Strong downslope flow
off area mountains into KLWS is expected to keep conditions VFR.
JW
&&
.PREV DISCUSSION... /issued 351 PM PST Thu Nov 22 2018/
Tonight and early Friday...The next in a series of weather
disturbances will move across the forecast area tonight. Moisture
along the warm front will increase to above normal, but not much
more. There is some consistency that a surface low will spin up
east of the Cascades and this will increase up-sloping flow into
the east slopes of the Cascades at about the same time as the best
forcing moves across the area. Between 06-12z the low moves up
around Colville and will shift the focus of the best precipitation
up to that area. It looks like moderate snow for the east slope
valleys with areas like Plain, Lake Wenatchee, The Methow valley,
Loup Loup Pass and Blewett Pass getting 2-5 inches of snow. The
mountains will see much more with 6-12 inches above 4500 feet
possible. The Okanogan Highlands and northeast valleys don`t look
like they will get as much, but still 1-3 inches are possible.
Sherman Pass may see 4-6 inches of snow by Friday afternoon. With
that in mind a Winter Weather Advisory for snow was issued for the
East Slopes of the Cascades for tonight through Friday. Another
forecast challenge for tonight will be the precipitation type in
the deep basin. Fog and stratus developed behind the precipitation
from overnight and satellite imagery is showing an area of
fog/stratus from just east of Moses lake east to the Waterville
Plateau. Temperatures in this are at or just below freezing now
and any more warming will be quite limited now that the upper
clouds are moving into the region. As such, some light freezing
rain was added to the deep basin zone. Accumulations are not
expected to be very much and this will be monitored in case there
is a need for a short fused advisory. One other thing of note,
winds will be on the increase for the Basin, Palouse and up
towards the West Plains. The timing for very gusty winds is not
the best, but there will be gusts 25-30 mph and locally to 35 mph.
Tobin
Friday:
A rather robust shortwave trough currently over the Gulf of Alaska
will move through the region. Precipitation should start to spread
inland around midday, with the most intense bands of precipitation
expected late Friday afternoon through Friday night. These intense
rain / snow bands might be a bit spotty in nature, and hi-res
guidance suggests they will set up generally in far eastern WA,
but especially the Idaho Panhandle. Snow levels should start
between 3000-4000 ft with snow impacting Lookout Pass, and will
lower to potentially around 2000 ft as precipitation diminishes
Friday night. As such, upwards of a foot of snow is expected at
pass level, with potentially a dusting down into the city of
Spokane. Winter Storm Warnings and Advisories have been posted to
reflect these likely impacts to holiday travel.
Southwest winds are also likely to increase over the Palouse as
the front passes through. Cold and wet conditions are also
expected as the winds pick up Friday evening.
Saturday and Sunday:
Conditions will begin to dry out during the day Saturday as drier
northerly flow aloft moves over the region. The upper level ridge
axis then moves overhead the region late Saturday through Sunday,
bringing fair weather for most of the weekend. Much of the area
could clear out on Saturday, with increasing clouds Saturday night
into Sunday. Look for high temperatures in the mid 30s to around
40 degrees in the Valleys, which is within a few degrees of normal
for this time of year.
Monday through Thursday:
Unsettled weather returns to the region as a series of storm
systems takes aim at the Pacific Northwest. The first appears to
arrive on Monday, and has the making of an atmospheric river
system with moisture tap originating in the subtropics. Integrated
Vapor Transport (IVT) values are projected to reach near 1000
kg/m/s off the coast on Monday, with PW values up to 0.9"
extending inland east of the Cascades. This warm tap of moisture
will eventually scour out the cold air (though it may take a bit
of time to do so), and snow levels may eventually arise above most
major Cascade and Idaho pass levels. Current projections have snow
levels lowering again toward the middle of or late next week,
with periods of unsettled weather continuing through the week.
Dang
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 35 42 29 37 27 38 / 100 60 70 10 10 10
Coeur d`Alene 35 41 30 37 27 39 / 90 70 80 20 10 10
Pullman 36 44 31 39 26 39 / 70 70 90 30 0 10
Lewiston 39 49 36 45 28 43 / 60 60 80 20 0 10
Colville 33 41 26 40 25 40 / 100 70 50 10 10 20
Sandpoint 34 39 28 38 28 38 / 90 70 70 10 20 20
Kellogg 35 39 32 35 28 36 / 100 70 90 40 10 10
Moses Lake 31 45 25 43 25 41 / 80 30 40 0 0 10
Wenatchee 31 41 29 42 29 38 / 90 30 20 0 10 20
Omak 30 39 25 40 25 38 / 90 50 40 10 10 10
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...Winter Storm Warning from 4 PM Friday to 10 AM PST Saturday for
Central Panhandle Mountains.
Winter Weather Advisory from 4 PM Friday to 10 AM PST Saturday
for Idaho Palouse-Lewis and Southern Nez Perce Counties.
WA...Winter Weather Advisory until 4 PM PST Friday for East Slopes
Northern Cascades.
&&
$$