Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/27/17

AREA FORECAST DISCUSSION

National Weather Service Eureka CA

225 PM PST Sun Nov 26 2017

.SYNOPSIS...A shortwave trough will pass through the region
tonight. High pressure will then build and bring drier weather to
the area.

.DISCUSSION...Conditions will remain wet and breezy for northwest
California this afternoon and evening as the last shortwave trough
passes through the region. Winds will gradually diminish tonight
while showers and isolated thunderstorms taper off early tomorrow
morning. Thunderstorms should be confined to the southern coastal
areas, but the northern outer waters may score a few storms. High
pressure will then take over the forecast and keep the majority
of the CWA dry for the work week; however, a weak frontal system
will skirt over northern California on Tuesday. Any rain that is
received will stay north of Mendocino County with the bulk of it
(a quarter inch or less) falling in Del Norte County. Following
that, the next chance for rain will be over the weekend. Models
agree that a trough will dig over the West Coast, but not on its
placement. Temperatures are expected to be cool and conditions
look to be wet during this period.

.AVIATION...A round of stronger showers moved through around
Midday along the coast bringing gusty winds. Some localized wind
shear was reported at KACV. This continues to move to the east
this afternoon. There a few isolated showers off the coast that
may move onshore onshore later this afternoon and evening.

Vis satellite shows another round of heavier showers well off the
coast. HRRR simulated radar shows this moving onshore around 04Z
to 07Z depending on the location. There is the potential for
thunder with these showers, the best chance looks to be coastal
Mendocino county. For now have left them out of the TAFS. These
showers are expected to start moving out of the area late tonight.
Monday there may be some valley low clouds in the morning, but
otherwise light to moderate northerly winds and VFR conditions
are expected. MKK

.MARINE...This afternoon showers continue to move through the
waters. Increased instability may result in occasional strong
wind gusts this afternoon and evening, particularly near any
strong showers that develop. There is also the potential for
an isolated thunderstorm or two this evening. Tonight, a low
pressure system will pass through the waters, causing winds to
veer to the west, and then north, with occasional strong wind
gusts as well...especially in the southern waters. While winds
won`t be light by any means, the changing wind direction will lead
to an overall subsiding of steeper, wind- driven seas. However,
westerly and northwesterly swell will build in its place,
maintaining an elevated and somewhat mixed sea state through
Monday, even though overall wave heights will very slowly
decrease.

A weak weather system will weaken diminish the northerly winds and
bring some light southerly winds Monday night and Tuesday. This
will also bring lower seas. Seas late Monday and early Tuesday
will likely be the lowest of the entire weak.

Northerly winds will increase once again late Tuesday and
Wednesday, and at the same time, a large northwest swell will
build into the waters. As a result, seas will become large, mixed,
and hazardous by mid- week.

Thursday through Saturday winds will be fairly light, however seas
will remain around 10 to 12 as several northwest swells move
through the waters. MKK/BRC

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...None.
NORTHWEST CALIFORNIA COASTAL WATERS...Small Craft Advisory until 9 PM PST Monday for PZZ450-455-470-
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 Marquette MI

647 PM EST Sun Nov 26 2017

.SHORT TERM...(This evening through Monday)
Issued at 304 PM EST SUN NOV 26 2017

...Breezy into early evening then again Mon aftn...

Clipper shortwave/sfc low in northwest flow aloft tracked north and
east of Lk Superior into this aftn. Actually ended up being warmer
as skies are only now clouding up over northern Upper Michigan.
Highest temps thus far have been into the upper 40s vcnty of Iron
Mountain. Has also been breezy, especially on the Keweenaw with peak
gusts there around 45 mph. As the clipper low moves away this
evening expect winds to diminish. Skies will continue to cloud over
from north to south, with most of Upper Michigan in mostly cloudy
skies by the evening. Still looks like there may be a few rain and
snow showers or drizzle over far east to east of Munising but should
not be big issue as it is marginally cold for any lake effect. Some
question in extent of cloud cover later tonight. Followed RAP 950-
900mb RH progs as they have shown low clouds upstream well through
the day. Expect low clouds to stay locked in especially east half
with north winds off Lk Superior and temps at top of moist layer
around -8c which is good enough for lake effect clouds. Inversion
building in only will trap the moisture. Clouds should partially
clear over west half late tonight as sfc-H9 ridge slides overhead.
Wherever breaks in the clouds occur temps may drop into to around
20F.

On Monday, expect fair amount of clouds either due to lingering
low clouds or mid clouds spilling across top of upper ridge sliding
over Great Lakes. Clouds will be due to strong shortwave trough and
sub 990mb sfc low crossing central Saskatchewan in the aftn. S to SE
winds will increase ahead of the low and breezy conditions with
gusts up to 30 mph should develop over forecast area. High temps
will depend on how much low clouds are around and how deep we can
mix, but after the warmer than expected day today and thermal ridge
moving in during Mon aftn, nudged highs up toward higher end of
guidance (40s to around 50F) warmest west where there should be
less low cloud potential with downsloping south flow developing in
the afternoon.

.LONG TERM...(Monday night through Sunday)
Issued at 309 PM EST SUN NOV 26 2017

The weather through the extended forecast will be pretty tranquil
for late November standards. Generally zonal upper flow with
embedded low amplitude disturbances will be the theme for the week.
One disturbance will lead to some post frontal gusty westerly winds
for the Keweenaw on Tuesday...similar to today. Cooling behind that
front will be modest with 85H temps only falling back to -8C or so.
Thus...lake effect processes will have a tough time getting going
and don`t anticipate anything more than a few flurries for the
Keweenaw Tuesday night.

Surface ridging will be over the Great Lakes on Wednesday as next
disturbance/front quickly approach the Upper Great Lakes late
Wednesday night into Thursday. There will be a bit more moisture
with this feature but all in all still pretty paltry. Only looking
at a few hundreths of liquid precipitation for central and eastern
areas that will fall as a mix of rain and snow. This will be the
best chance for precipitation over the next seven days.

There are some signs the upper pattern will begin to buckle and
become more amplified by early next week, but prior to that the
weather for Friday through next weekend will stay quiet with
temperatures running 5-10 degrees above normal.
&&

.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 646 PM EST SUN NOV 26 2017

Expect MVFR cigs to persist at KCMX and KSAW, hovering in the 015-
025 range. Ceilings may scatter out late tonight at KCMX, but expect
them to hang on into most of Monday at KSAW. MVFR conditions could
also develop at KIWD late this evening or overnight, but confidence
is low. So, maintained a VFR forecast at this time. More strong
southerly winds are possible at all TAF sites Monday afternoon but
could end up being more LLWS depending on how much mixing occurs.
&&

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 304 PM EST SUN NOV 26 2017

Active Fall weather continues on Lake Superior. Winds diminish
tonight but south winds increase to gales again Mon aftn into Mon
night. North central and eastern sections will be favored for
strongest winds. Gale warning has been issued. Winds shift to
northwest gales late Tue afternoon into Tue night. This looks to be
the last gale event seen this forecast period, with winds staying
15-30 kts Wed into Fri.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
Gale Warning from 3 PM Monday to 1 AM EST Tuesday for LSZ264>267.

Lake Michigan...
None.
&&

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

Area Forecast Discussion

National Weather Service Portland OR

145 PM PST Sun Nov 26 2017

.SYNOPSIS...Snow levels will lower to near the Cascade passes late
this afternoon and early this evening. Post-frontal showers will
continue into early Monday morning. Another frontal system will
produce rain and mountain snow Monday night and Tuesday with snow
levels remaining near the Cascade passes. Drier conditions are
expected for Wednesday before the next front arrives on Thursday.
Active weather continues into next weekend.

.SHORT TERM...Tonight through Wednesday...A cold front is over the
Cascades this afternoon, and should move east of the Cascades late
this evening. There is a slight chance for isolated thunderstorms
late this afternoon through this evening along the coast and the
coastal waters as isolated lightning strikes have been observed in
the offshore waters.

Snow levels are lowering behind the front, and will be down to near
the Cascade passes around or shortly after sunset tonight. Showers
will continue tonight into Monday morning as an upper trough moves
over the region. Orographic effects will result in the showers
favoring the higher terrain. Rain totals should remain below 0.20
inch in most areas tonight with slightly higher amounts for the
coastal mountains and the Cascades. Expect localized 2-4 inches of
new snow for the south Washington Cascades tonight with 1 to 3
inches for the north Oregon Cascades.

Showers will decrease overnight, but at least a slight chance for
showers will continue north of Salem most of Monday. Any clearing
early Monday morning will likely lead to patchy fog in the interior
valleys, with the best chance south of Salem. Showers will end for a
few hours Monday evening before the next front brings additional rain
and mountain snow late Monday night through Tuesday night.

Snow levels will start around 5000 feet with the initial
precipitation early Tuesday morning, then lower down to 3500-4000
feet behind the front. This front is rather quick moving which
should limit rain and snow totals. Expect 0.75 to 1 inch of rain for
the coast and northern Cascades with around 0.50 inch of rain for
the south and the interior valleys from late Monday night through
Tuesday night. The Oregon Cascades could see half of an inch or so
every 6 hours with the Washington Cascades seeing 1 to 2 inches
every 6 hours. Therefore localized 4 to 8 inches 24 hour snow totals
are possible for the Cascades.

Showers will end early Wednesday morning and the rest of the day
should remain dry. ~TJ

.LONG TERM...Wednesday night through Sunday...A weak shortwave ridge
aloft will keep conditions mostly dry through Wednesday night, with
areas of fog redeveloping overnight over portions of the CWA. Gusty
east winds near the Columbia River Gorge will likely keep fog away
from the Portland Metro Wednesday night. Models then show the next
frontal system moving across the forecast area on Thursday. This
system will mark the beginning of another period of active weather,
with another frontal system moving across the region late Friday.
Conditions look to become showery on Saturday as the upper level
trough dives south across the region, with snow levels falling to
around 2000 ft by Saturday night. Lingering instability will keep
some showers going into Sunday, but chances are low. Temperatures
during the long term period will generally be a few degrees below
normal, with overnight lows in the mid 30s and afternoon highs in
the mid 40s. /64
&&

.AVIATION...Secondary narrow frontal band moved through the
interior valleys 19-20Z. This feature produced IFR to MVFR vis
conditions and wind gusts 25-35 kt. Generally VFR across the area
at 21Z in the post frontal air mass. VFR likely to prevail
through Mon morning, with areas of MVFR. Models show another
weak surface trough moving across Western Washington and NW
Oregon 06Z-12Z Mon, which may produce areas of MVFR. There is the
potential for IFR vis to develop at KEUG and KHIO late tonight.

KPDX AND APPROACHES...VFR at the terminal at 21Z and expect this
to be the predominant category through Mon morning, although
there will be brief periods of MVFR. Another surface trough
moves over the area late tonight, which will increase the risk of
MVFR cigs. Weishaar

.MARINE...Wind speeds have dropped off significantly since early
this morning. Northern waters getting some gusts 15-20 kt early
this afternoon, with a peak gusts of 23 kt at buoy 089. 12Z
models show another surface trough moving across the north waters
late tonight. GFS has stronger boundary layer wind speeds than
the NAM and ECMWF, with 25-30 kt clipping the far north part of
PZZ270 12Z Mon. Higher-resolution models not as robust showing
generally 20 kt. Prefer the NAM and HRRR solutions. Will keep the
small craft advisory for wind in the north waters, although it
may be marginal late tonight and early Mon morning.

Another frontal system is expected Mon night into Tue, but the
brunt of the energy will stay well north of the waters. The 12Z
models suggest solid small craft advisory speeds Mon night, with
gales possible over the north waters. Once again, prefer the NAM
for this system, with 35 kt gusts 06Z-14Z Tue. High pres builds
into the waters late Tue and remains for much of the rest of the
week.

Seas have eased into the mid teens early this afternoon. There is
a mix of8 to 10 ft longer-period swell and a secondary set of SW
11-13 ft waves. Seas fall close to 10 ft late tonight or Mon
morning. Models continue to waffle on the large swell set due
into the waters Tue night. Latest ENP showing a much broader area
of 20-23 ft seas compared to the past couple of runs. Highest
energy remains focused in the Washington waters. Unlike the past
couple 20 ft plus events that were primarily wind-wave driven,
the Tue night event will be large W-NW swell with long periods.
Seas settle down late Wed, but remain above 10 ft through the
week. Weishaar

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
PZ...Small Craft Advisory for winds until 1 AM PST Monday for
Coastal Waters from Cape Shoalwater WA to Cascade Head OR
out 60 NM.

Small Craft Advisory for hazardous seas until 4 PM PST Monday
for Coastal Waters from Cape Shoalwater WA to Florence OR
out 60 NM.

Small Craft Advisory for Rough Columbia River Bar until 10 AM
PST Monday.

&&
$$

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This discussion is for Northwest Oregon and Southwest Washington
from the Cascade crest to 60 nautical miles offshore. This area is
commonly referred to as the CWA, or forecast area.

Area Forecast Discussion

National Weather Service Sacramento CA

234 PM PST Sun Nov 26 2017

.Synopsis...
Rain and breezy winds continue through early Monday. Mountain
travel impacts tonight into Monday as snow levels drop. Drier
weather Tuesday through Friday with patchy morning fog in the
valley Tuesday morning.

.Discussion...
Cold front continues to make its way across the area this
afternoon with rain stretching from the Sierra back to the Bay
Area. A few thunderstorms become embedded in the line of rain,
with strikes from the Sacramento area up into the foothills.
Showers are also popping up behind the front in the northern Sac
Valley with a band of heavier showers in Tehama county. HRRR
hinting at Shasta County convergence band forming in typical spot
NW of Redding which could also drop some locally heavy rainfall.
Along with the rain, breezy winds occurring across the northern
Sac Valley with gusts of 35-45 mph currently. Have covered with a
short-duration wind advisory in that area. Gusts of 50-75 mph
also being reported on western side of the Sierra crest. Winds
should decrease throughout the night.

Showers will continue across the area through the evening hours,
before a secondary wave moves onshore. This will bring another
burst of rain to the valley and better chances for snow across
higher elevations. Models still showing some instability in the
valley late this evening into the overnight hours, but confidence
not super high in the occurrence of additional thunderstorms.
Have left out of the forecast for now but will leave for evening
shift to monitor trends.

As mentioned previously, snow level forecast remains tricky as
models don`t typically handle snow levels well when heavier
frontal precipitation occurs. Winter storm advisory remains intact
as snow levels may temporarily drop below pass levels sometime
this afternoon - evening, before a bigger drop off tonight. This
may also affect how much snow accumulates. Given increased traffic
from the holiday weekend and strong winds, chain controls will be
possible with some travel delays. Those with travel plans over
the passes should keep on road conditions as things could change
rapidly later today.

Precipitation tapers off by around daybreak Monday with dry
weather for the rest of Monday into Tuesday. Patchy valley fog
may develop Tuesday morning with clear skies and lingering surface
moisture. Models show a weak shortwave skirting the northern
portions of the state late Tuesday, but bulk of energy and
moisture remains over the Pacific NW. Have kept dry forecast for
now. Northerly flow will increase on Wednesday with some breezy
winds along the coastal range and western side of the Sacramento
Valley. This may affect fog formation Wednesday morning somewhat,
but it remains to be seen to what extent.

CEO

.EXTENDED DISCUSSION (Thursday THROUGH Sunday)
Stable conditions over northern California for Thursday with
slightly above normal temperatures for this time of year. The next
weather system will drop southward out of the Gulf of Alaska
sometime late Friday into next Saturday. Model forecasts differ
slightly as to the arrival of the upper level trough of low
pressure with the ECMWF a bit faster than the GFS...but otherwise
the amplitude of the disturbance looks similar between the two
forecasts. Early projections have between 4 and 8 inches of snow
for the higher elevations with some accumulations as low as 3000
feet into early next Sunday. Widespread precipitation across
interior northern California between 0.25 and 0.50 inches is
possible with temperatures dropping to near to slightly below
normal.

.AVIATION...
Frontal band moves through Norcal today and tonight. Light
showers this morning with rain and high elevation snow later this
morning through tonight. Mainly MVFR at TAF sites occasional IFR
in heavier showers. Slight chance of thunderstorms Sacramento
valley this afternoon and evening. Southerly wind gusts to 25 mph
Sacramento valley. Gusts to 60 mph this afternoon and evening over
the Sierra crest.

.STO WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 10 AM PST Monday for West Slope
Northern Sierra Nevada-Western Plumas County/Lassen Park.

Wind Advisory until 5 PM PST this afternoon for Northeast
Foothills/Sacramento Valley-Northern Sacramento Valley.

Area Forecast Discussion

National Weather Service Topeka KS

500 PM CST Sun Nov 26 2017

...AVIATION UPDATE...

.SHORT TERM...(This evening through Monday)
Issued at 242 PM CST Sun Nov 26 2017

The region was under northwesterly flow aloft this afternoon due to
a broad mid-level ridge stretched across the western U.S. With
surface high pressure continuing to shift into the southeastern U.S.
and with low pressure centered over the Rockies, southwesterly
surface winds prevailed. These winds combined with mostly sunny
skies led to another unseasonably mild day with afternoon
temperatures in the mid/upper 60s. Despite mostly clear skies
tonight, the southerly wind component should keep temperatures
"mild" overnight with lows in the upper 30s to low/mid 40s.

A mid-level trough will move into the Pacific Northwest tonight and
quickly deepen across the western U.S. on Monday. This quickly-
advancing trough will help to push the surface low pressure over the
Rockies further eastward into Kansas, resulting in a tightening
pressure gradient developing over the CWA through the day. With
model soundings showing a strong low-level temperature inversion
present Monday morning, expect the gusty southwesterly winds to aid
in mixing down some of these warmer conditions. Have continued to
trend warmer with temperatures for tomorrow, with near or above
record high temperatures possible as readings soar into the 70s.
Refer to the Climate discussion below for details on the record high
temperatures. Have also continued to trend higher with the wind
gusts through the day, and the combination of these gusty winds with
dry conditions in place will result in very high fire danger
conditions across much of the outlook area. Refer to the Fire
Weather discussion below for further details.

.LONG TERM...(Monday night through Sunday)
Issued at 242 PM CST Sun Nov 26 2017

Lee cyclogenesis occurs off the higher terrain Monday night as the
upper trough deepens southeast across Colorado. Strong sfc southerly
winds are noted along with a 60 to 70 kt low level jet overnight,
translating to winds at 20 to 25 mph sustained. All guidance is
consistent with frontal timing occurring after midnight in north
central Kansas, quickly arriving in the Emporia/Topeka area by mid
morning Tuesday. Convergence increases along the front as the upper
forcing with the closed low skims the Oklahoma and Kansas border.
Being in the northeast quadrant of the upper low is not conducive
for prolonged moisture advection so have a low end chance of
scattered rain showers during the afternoon and evening hours. QPF
amounts are around a tenth of an inch at best. Temperatures drop
down into the 30s Tuesday night behind the front, however timing
with the precipitation and forecast soundings suggest precip type to
remain all rain with lows in the upper 30s. In addition to the
precip, drier air arrives into north central Kansas by early
afternoon Tuesday, combining with the gusty winds could spell
another elevated fire weather day. Details are mentioned below in
the fire discussion.

The remainder of the extended is fairly uneventful after Wednesday
night. The GFS and Canadian models translate a progressive, upper
shortwave trough through the central plains at this time. Precip
occurs along and just behind the frontal boundary over far eastern
KS where temperatures remain above freezing in the upper 30s so have
just a mention for rain showers. The ECMWF on the other hand has
been consistently further north with this system and therefore dry
for our area so will maintain the slight pops this far out. Lack of
a strong, cooler airmass behind these fronts deviates temps little,
remaining above normal in the 50s for highs throughout the week.

.AVIATION...(For the 00Z TAFS through 00Z Tuesday)
Issued at 500 PM CST Sun Nov 26 2017

Dry air remains in place, so VFR conditions are expected to
continue. Models develop a low level jet across southeast KS with
RAP and NAM forecast soundings developing a steep nocturnal
inversion. With objective MOS guidance showing the boundary layer
decoupling, think the low level jet could be close enough for some
LLWS early this evening and through Monday morning.

.FIRE WEATHER...
Issued at 242 PM CST Sun Nov 26 2017

For the remainder of this afternoon, some localized areas of very
high fire danger will be possible, primarily across central to east
central KS, where RH values were dropping into the low/mid 20
percent range with sustained winds of 15-20mph and gusts to 25mph.

Breezy southwesterly winds are expected on Monday as the pressure
gradient increases across the CWA due to the approaching low
pressure system. These winds will quickly increase by late morning
with sustained winds of 15-25mph and gusts of 30-35mph likely. Feel
that models are not trending dry enough with dewpoints on Monday, so
have also trended lower with these values during the afternoon hours
(into the low/mid 40s). These dewpoints combined with near-record
high temperatures in the 70s will result in minimum RH values
dropping into the mid 20 to mid 30 percent range. As a result, very
high fire danger conditions are expected across the entire outlook
area Monday afternoon.

On Tuesday afternoon across north central Kansas, winds shift
towards the north remaining steady at 15 to 25 mph sustained, with
gusts occasionally in excess of 30 mph in the afternoon. Dry air
advection behind the boundary will likely drop dewpoints into the
low 20s, translating to minimum RH values in the mid to upper 20
percentile. Very high fire danger conditions are expected over north
central Kansas, with moderate to high fire danger elsewhere as cloud
cover and slightly higher RH values counter the gusty winds.

.CLIMATE...
Issued at 242 PM CST Sun Nov 26 2017

Record Highs Monday

Topeka: 71 degrees set back in 1998 (Forecast: 73)
Concordia: 69 degrees set back in 1933 (Forecast: 75)

.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

SHORT TERM...Hennecke
LONG TERM...Prieto
AVIATION...Wolters
FIRE WEATHER...Hennecke/Prieto
CLIMATE...Hennecke