Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/21/17

Area Forecast Discussion

National Weather Service La Crosse WI

 533 PM CST Mon Nov 20 2017

.SHORT TERM...(Tonight through Tuesday)
Issued at 215 PM CST Mon Nov 20 2017

Models have been in good agreement with taking an upper level
shortwave trough (currently churning across southern Canada)
southeast across the Upper Mississippi River Valley tonight through
Tue. Accompanying sfc cold front will slide across the local area
overnight, exiting southeast by 12z Tue. Not a lot of forcing with
the boundary, with most of the models` qpf tied to the shortwave and
deeper saturation in the north. That said, with strong low level
cold air advection post the front, low level lapse rates favor
cu/shower potential - if there would be enough saturation to play
with. Latest bufkit soundings suggest there isn`t. Will keep the
area "dry" for now - but monitor the passage of the front late
tonight and any percolation for Tue.

While the surge of cold likely won`t lead to shower activity, the
steepening lapse rates will promote mixing and enhanced wind gusts.
Couple this with a tightening sfc pressure gradient tonight through
Tue morning and it looks to be a blustery period for the local area.
Wind gusts upwards 35 mph possible in the open/unsheltered areas.
With very little daytime bump in the temps from the morning lows
Tue, wind chills in the teens will be common. Don`t see a need for a
wind advisory at this time.

.LONG TERM...(Wednesday through Monday)
Issued at 215 PM CST Mon Nov 20 2017

Start of the long Thanksgiving weekend will be rather nice...the
end? Not so much.

Shortwave upper level ridging and a southerly fetch will usher in
some seasonable to mild air for Thu and Fri. 850 mb temps will
rebound from the chilly -12C at 18z Tue to +14C by 18z Fri. NAEFS
850 mb temp anomalies are +1/+2.  Fri should see highs in the 50s -
but if the EC is correct, a few locations will flirt with 60. Going
to hold with consensus blend for temps for the moment. Too many
questions with cloud cover/frontal passage.

While still a few differences in strength, etc...the GFS and EC
coming into better agreement (at least within the last couple runs)
with a shortwave trough/sfc front combo slated to drive across the
region Friday afternoon/evening. Both dig the trough across northern
parts of the region, but extend the upper level forcing southward to
the local forecast area - working with the sfc front that slides
through by 00z Sat. Some aid in the lift from left exit region of
the upper level jet also looking likely. The deeper saturation is
still holding to the north, but models do suggest some low level
moisture transport ahead of the front - helping with pcpn potential
in the south. As it stands, trends in the GFS and EC suggest
increasing chances for showers (rain) for Friday afternoon, mostly
north of I-90. The bulk of the system`s qpf still well north.

Cold air drops southward across the Upper Mississippi River Valley
for Sat and Sun - post the departing shortwave trough. 850mb temps
tumble back to -10C by 18z Sat and highs in the 30s for most Sat/Sun
are expected. Looks a little blustery on Sat too - so wind chills
will add bit to the air.

&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 533 PM CST Mon Nov 20 2017

The winds will be the major concern during the entire period. An
area of low pressure over southwest Ontario will move east into
Quebec through the period. A pre-frontal trough will pass through
the area overnight swinging the winds around to the west. This
will be followed by the cold front late tonight when the winds
will shift to the northwest and become quite gusty. Good low level
lapse rates behind the front will allow gusts into the upper 20s
to lower 30s knot range to be common for much of the day after
sunrise Tuesday. The 20.18Z NAM and 20.22Z RAP are both showing a
band of higher moisture behind the front at 850 mb that will swing
across the area Tuesday morning. Have included this with a period
of lower VFR ceilings for both airports but will have to watch
this for a possible period of MVFR ceilings.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&

$$

SHORT TERM...Rieck
LONG TERM....Rieck
AVIATION...04



Area Forecast Discussion

National Weather Service Melbourne FL

 920 PM EST Mon Nov 20 2017

.DISCUSSION...

Relatively quiet WX pattern overnight as hi pres over the ern
seaboard pushes into the W Atlc and maintains a steady easterly flow
acrs central FL. Frontal boundary extending from the srn GOMex acrs
the FL Straits will dissipate, though its remnant H100-H70 moisture
band/H85-H70 theta-e ridge will begin to drift back to the north as
mid lvl winds veer to the SE.

Evng KXMR/KTBW RAOBs continue to show a very dry/stable airmass over
central FL with PWat values arnd 0.75", avg H85-H50 dewpoint
depressions btwn 20-30C over the Treasure Coast/Lake-O region, and a
sharp subsidence inversion in the H85-H70 lyr. PWat increases to
arnd 1.50" at KMFL/KEYW, much of which is trapped blo the same mid
lvl subsidence inversion, albeit in a much weaker state. Latest
radar images from KMFL do show banding precip moving onshore, but
limited to points south of Broward Co and showing no sign of any
northward drift.

While H100-H70 moisture is expected to increase as hi pres builds
over the W Atlc, the dry/stable air over central FL will require
significant modification before it can support any precip. Indeed,
the HRRR and lcl WRF models are quite bearish on precip dvlpg over
the Treasure Coast overnight, and even then, more in the predawn hrs
than overnight.  As such, will cull PoPs back to 20pct aft 09Z with
the evng update. Onshore flow will keep overnight min temps abv
avg...L/M60s inland and M/U60s along the coast.

&&

.AVIATION...Thru 22/00Z.
Sfc Winds: Thru 21/06Z...Coastal sites E/NE 8-12KTS...interior sites
4-8KTS. Btwn 21/06Z-21/12Z...E/NE 4-8KTS. Btwn 21/13Z-21/16Z...bcmg
E/SE 7-11KTS. Btwn 21/21Z-21/24Z...N of KMLB-KISM bcmg E/NE 5-
9KTS...S of KMLB-KISM bcmg SE 4-8KTS.

Vsbys/WX/Cigs...Thru 21/13Z prevailing VFR SCT-BKN040-050...aft
21/06Z bcmg multilayered BKN-OVC btwn FL080-120. Btwn 21/13Z-
21/16Z...S of KMLB-KISM areas MVFR cigs/vsbys in -RA/RA/BR...N of
KMLB lcl MVFR cigs/vsbys in -RA/BR. Aft 21/16Z...prevailing cigs
btwn FL060-080...areas MVFR cigs/vsbys and lcl IFR cigs/vsbys in +RA
all sites...slgt chc TSRA.

&&

.MARINE...
The center of a large hi pres ridge blanketing the ern CONUS will
drift off the Carolina Coast overnight, maintaining a gentle to
moderate easterly breeze while doing so...ocnl G20KTs. Latest buoy
obs are indicating 4-6FT seas in the shelf waters, 5-7FT in the Gulf
Stream...dominant pds btwn 6-7sec resulting in rough conditions with
steep wave faces. While winds are expected to diminish slightly
overnight as the ridge pushes into W Atlc, overall conditions will
remain poor enough to continue latest advisory/cautionary statements
overnight.

&&

.MLB WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...Small Craft Advisory until 4 PM EST Tuesday for Sebastian Inlet
     to Jupiter Inlet 20-60 nm-Volusia-Brevard County Line to
     Sebastian Inlet 20-60 nm.

     Small Craft Advisory until 10 AM EST Tuesday for Sebastian Inlet
     to Jupiter Inlet 0-20 nm.

&&

$$

Short Term/Aviation...Bragaw
Impact Wx/Radar.......Sedlock




Area Forecast Discussion

National Weather Service Marquette MI

 912 PM EST Mon Nov 20 2017

.UPDATE...
Issued at 912 PM EST MON NOV 20 2017

Most notable update to fcst revolves around strong/gusty winds.
Water vapor imagery and RAP analysis show a vigorous shortwave
moving across southern Manitoba into far northern MN. At the sfc,
associated 987mb low pres is over northern Ontario to the sw of
Pickle Lake with trailing cold front cutting across MN. Dry
prefrontal environment noted on regional 00z RAOBS supports dry fcst
until arrival of post frontal low-level moisture and colder air to
kick in lake effect processes very late tonight into Tue morning.

Of more importance is wind. Upstream, a number of sfc obs just ahead
of 6mb/3hr pres rise have indicated peak gusts in excess of 40kt
across ne ND/southern Manitoba/nw MN this evening. Highest gust from
obs was 53kt at Pilot Mound, Manitoba. With positive part of the
pres rise/fall couplet fcst to increase to +8 to 10mb/3hr as it
approaches nw Lake Superior late tonight and then shifts over
western Lake Superior in the morning, the 40+kt gusts currently
being observed upstream are a very good indicator of what will be
seen over the Keweenaw Peninsula late tonight/Tue morning. Rather
vigorous CAA will also support enhanced mixing as air mass moves
over the relatively warm lake waters. Have thus opted to issue wind
advy for Keweenaw/northern Houghton counties for 07z to 18z. Peak
winds up to 50mph, perhaps as high as 55mph, will occur in 09-13z
time frame. Will also include Ontonagon county for 07z-15z, lakeside
locations in particular. Probably won`t see much in the way of
snowfall during the wind advy period as strong winds will displace
orographic enhancement to developing LES farther downstream.

It appears strongest winds will occur in the w or wnw flow in the
wake of first cold front and ahead of secondary trof that drops
across the area on Tue. As a result, eastern counties bordering Lake
Superior may miss out on the more widespread advy level winds.
However, this will be reevaluated thru the night as additional
guidance arrives.
&&

.SHORT TERM...(This evening through Tuesday)
Issued at 302 PM EST MON NOV 20 2017

Main concerns revolve around strong winds that are expected to
develop tonight and continue through Tuesday. A 988hPa surface low
in response to a potent shortwave trough near Winnipeg will track
just north of Lake Superior tonight. An associated trough will swing
SE across the CWA late tonight into Tuesday, ushering in blustery
conditions.

An initial push of strong southerly winds aloft may mix down to the
surface at times this evening, especially for downslope locations
near Lake Superior. 850hPa temps will then quickly drop behind the
trough across the west overnight and the east on Tuesday. The
combination of cold air advection and an increasing pressure
gradient between thermally enhanced troughing over eastern Lake
Superior and a 1032hPa high building over the Northern Plains will
promote blustery conditions across the CWA, especially along Lake
Superior. NW gusts to 40mph, possibly 45mph, should affect most of
the Lake Superior shore in the NW wind belts. Resultant waves of 12-
15ft along the Lake Superior shore from Shot Point to around Grand
Marais Tuesday afternoon warrants a Lakeshore Flood Advisory for
Alger County due to minor flooding and beach erosion. Additionally,
those traveling to/from downstate should monitor the status of
traffic on the Mackinac Bridge as stronger crosswinds are expected
there overnight through Tuesday.

As for snow, strong winds, modest inversion heights, and fairly dry
air will limit accumulations of expected LES. Snow amounts should
remain below advisory levels for the typical W to NW wind snow belts
across the west overnight into Tuesday, and across the east on
Tuesday. Though winds will be strong, a rather solid/frozen snow
pack in these locations should limit blowing snow to only that which
falls during this event. For that reason, will hold off on any
headlines or Special Weather Statements.

.LONG TERM...(Tuesday night through Monday)
Issued at 302 PM EST MON NOV 20 2017

The mid-upper level pattern will remain fairly progressive into
early next week across the northern CONUS between mean troughing
over the Gulf of Alaska/NE Pacific and troughing over eastern Canada
and the NE CONUS.

Tue night into Wed, nw gradient flow should be gradually weakening
as a shortwave trough pushes e and strong ridging builds in from the
w. 850 mb temps near -15c should equate to a lake-h85 delta-t of
around 20C. Dry air should limit nw flow LES accumulation from 2 to
5 inches Tue night into Wed with the greatest amounts east. A few
spots could reach borderline advisory criteria during the event.
Warming temps and winds becoming w to sw should end any lingering
LES Wed afternoon over the far eastern shoreline.

Another clipper shortwave is progged by models to move from northern
Manitoba into northern Ontario Wed night and Thu bringing another
cold front and quick shot of colder air across the Upper Great Lakes
on Thu. Models differ on how cold the airmass will be with the 12Z
GFS and NAM coming in about 5 degree Celsius colder than either the
12Z Canadian or the 00z ECMWF. Even with the colder GFS/NAM
solutions not expecting much more than 2-3" of nw flow LES
accumulation Thu into Thu evening as again large scale anticyclonic
flow and dry air will limit accumulations.  Backing flow and
moderating temperatures will end any lingering LES Thu night.

Friday into Sunday, both the GFS and ECMWF advertise another strong
shortwave moving across the Upper Great Lakes with a 982 mb sfc low
tracking e through northern Ontario just north of Lake Superior Fri
afternoon and evening. Elevated warm layer in strong warm air
advection ahead of this low pressure system could lead to some mixed
precipitation late Thu night/early Fri in form of light snow/light
fzra before pcpn changes over to mostly rain late Fri morning.
Bigger story with this system will be the wind as ssw wind gusts
ahead of the system could approach advisory criteria over a few of
the eastern counties on Fri. Behind the cold front as winds shift w-
nw, gusts could reach advisory criteria at a few of the more exposed
spots along Lake Superior Fri night into Sat. Looks like a decent
shot of cold air moving in behind the system coincident with the
main shortwave trough and secondary cold front as 850 mb temps drop
near -16c per 12z GFS by late Sat into Sat night. With colder air,
expect light to moderate LES in the NW wind snowbelts. Accumulation
will be likely be limited by dry air beneath lowering subsidence
inversion in large scale anticyclonic flow. LES will taper off from
w to e on Sun as sfc high pres builds in from the w and temps slowly
moderate.

Model uncertainty increases out to next Mon but the 12z ECMWF and to
a lesser extent the 12z Canadian show another shortwave and
associated sfc low moving through Ontario and glancing northern Lake
Superior. This could bring some light mixed pcpn to the area.
&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 659 PM EST MON NOV 20 2017

VFR conditions are expected at KIWD/KCMX/KSAW thru this evening
under a dry air mass ahead of an approaching cold front. Tight pres
gradient ahead of the front and relatively stable sfc based layer
will support LLWS thru the evening as well. After the front passes,
expect MVFR conditions and -shsn to develop late tonight into Tue
morning. Strong/gusty w to nw winds, frequently 30-40kt at KIWD/KCMX
(strongest at KCMX), will also lead to some blsn at KIWD/KCMX. While
MVFR conditions should prevail, will probably see some brief periods
of IFR at KIWD and especially at KCMX where winds will be strongest,
kicking up more blsn.
&&

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 302 PM EST MON NOV 20 2017

A strong low pressure system will track eastward just north of Lake
Superior tonight. Southerly winds to 30 knots through early evening
will becoming NW gales of 35 to 40 knots across much of Lake
Superior late tonight through Tuesday. Winds will diminish to under
25 knots while becoming westerly through Wednesday morning, before
backing to SW winds of 20 to 30 knots Wednesday night. Westerly
winds of 20 to 30 knots Thursday will back to the south on Friday.
Another strong low pressure system will then bring the potential for
northwest gales of 35 to 40 knots Friday night into Saturday.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
  Wind Advisory from 2 AM to 1 PM EST Tuesday for MIZ001-003.

  Lakeshore Flood Advisory from 11 AM to 9 PM EST Tuesday for
     MIZ006.

  Wind Advisory from 2 AM to 10 AM EST Tuesday for MIZ002.

Lake Superior...
  Gale Warning from 6 AM to 10 PM EST Tuesday for LSZ248>251-267.

  Gale Warning from 4 AM to 10 PM EST Tuesday for LSZ265-266.

  Gale Warning until 10 PM EST Tuesday for LSZ243>245-264.

  Gale Warning from 4 AM to 4 PM EST Tuesday for LSZ246-247.

  Gale Warning until 5 PM EST /4 PM CST/ Tuesday for LSZ162-
     240>242-263.

Lake Michigan...
  Gale Warning until 6 AM EST Tuesday for LMZ248-250.

&&

$$

UPDATE...Rolfson
SHORT TERM...Kluber
LONG TERM...Voss
AVIATION...Rolfson
MARINE...Kluber



Area Forecast Discussion

National Weather Service San Diego CA

 200 PM PST Mon Nov 20 2017

.SYNOPSIS...
High pressure aloft along the West Coast will bring unseasonably
warm weather this week and mostly clear skies except for periodic
high clouds. High temperatures will be 15 to 25 degrees above
average Wednesday and Thanksgiving. A slow cooling trend will begin
Friday and continue through early next week, but temperatures will
remain above average.

&&

.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...

High clouds were drifting over the region, and the patches of fog
over the coastal waters dissipated late this morning. Warmest areas
had temperatures in the upper 70s to lower 80s, mainly in the
valleys west of the mountains. Except for the high clouds, skies
should be clear tonight, especially with HRRR solutions showing few
to no low clouds in the coastal waters versus earlier solutions
which had some.

Upper level high will build from off the west coast of Baja north
into southern California/Arizona through Wednesday, continuing
Thursday, then gradually shift east Friday through the weekend. Weak
offshore flow will prevail at the surface. Local WRF has a gradual
lowering of near-surface RH over the coastal waters through tonight,
so the chance of any fog at the coast will be very low
tonight/Tuesday. The profile gets quite warm Tuesday through
Thursday, with 850 MB temps reaching 22-23 deg C in some areas west
of the mountains Wednesday, which is near the late-November record
of 22.7 deg C for NKX. Hence, we will likely not only have record
highs Tue-Thu but we could approach highest temps for this late in
the year. However, with low sun angles and low humidity, the heat
will be more bearable, especially in wind-sheltered areas which will
still have cool nights with lows in the 40s and 50s. Moderate
offshore flow will bring locally gusty northeast winds to the
southwest of mountain crests and through and below passes/canyons,
but with limited support aloft, most gusts will be 40 MPH or less.

A trough in the northeast Pac will gradually shift east during the
weekend and bring a cooling trend Friday through the weekend.
However, temps will remain above average. There could be a period of
dense fog in coastal areas when the marine layer returns, though
timing is far from certain as this probably will not be until at
least Saturday. No precipitation is expected through the weekend,
with only a small chance early next week when the trough moves
through northern California.

&&

.AVIATION...
202055Z...P6SM vis and SCT-BKN clouds AOA 20000 ft msl expected to
continue for all areas through Tuesday morning, with only a very
small chance for dense fog developing within 3 sm of the coast
during the 21/0300-1500 UTC time-frame.

&&

.MARINE...
Small chance of patchy dense fog developing over the coastal waters
late tonight into Tuesday morning. Otherwise, No hazardous marine
conditions are expected through Saturday.

&&

.FIRE WEATHER...
Elevated fire weather conditions area expected along the coastal
slopes in San Diego County and below the passes and canyons in
Riverside and San Bernardino Counties Wednesday and Thursday.
Conditions shouldn`t be extreme, but relative humidity values of 10-
15% and wind gusts of 25-40 mph will bring the elevated fire weather
conditions.

&&

.SKYWARN...
Skywarn activation will not be needed this week.


&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...NONE.
&&

$$

PUBLIC/FIRE WEATHER...Maxwell
AVIATION/MARINE...Harrison