Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/19/16
Area Forecast Discussion
National Weather Service Burlington VT
944 PM EST Fri Nov 18 2016
.SYNOPSIS...
Ridge of high pressure will crest overhead today keeping the
North Country dry with above normal temperatures through
Saturday. Late on Saturday a deep trough with an associated
cold front will bring rain and terrain driven snow showers
Saturday night and Sunday. The chance for precipitation will
continue through Monday night, with persistent cold air
advection seeing the rain transition to snow late in the weekend
and into Monday morning.
&&
.NEAR TERM /UNTIL 6 PM SATURDAY EVENING/...
As of 944 PM EST Friday...Just some additional minor tweaks to
sky/weather across the northern tier of NY into far northwestern
VT through the overnight hours per latest hi-res modelled cloud
cover and visibility progs. Patchy dense fog has bled down into
portions of the northern Champlain Valley as of 900 pm and per
HRRR output this could hang on a few hours longer before
developing southerly flow on back side of departing ridge leads
to dissipation. Stubborn low stratus still making a run at
northern SLV as well, though outside this immediate area mainly
clear skies are expected with some customary mist/fog developing
across eastern VT counties later tonight. Current forecast has
this well covered. Low temperatures a bit trick per radiational
effects and building warm thermal advection aloft. Case in point
is Mt. Mansfield summit which current sits at 57F while
Whiteface summit near 4900 feet sits at 54F. Meanwhile lower
elevations dropping into the 30s to around 40 in most spots.
The fog should lift quickly tomorrow as we mix during day break
and tomorrow afternoon should be another pleasant day through
the afternoon with clouds increasing from the west during the
late afternoon. High temperatures again running quite mild from
the upper 50s to around 60 in eastern VT, and in the lower to
mid 60s from the Champlain Valley west. Get out and enjoy it.
This will be the last mild weather for quite some time.
&&
.SHORT TERM /6 PM SATURDAY EVENING THROUGH SUNDAY NIGHT/...
As of 304 PM EST Friday...Winter storm watches have been posted
for late in the weekend across portions of the North Country,
including the Northern Adirondacks, St. Lawrence Valley, and
central VT, including the western slopes of the Green Mountains.
Snow levels expected to drop during the day Sunday, with
potential moderate snow accumulations areawide during Sunday
night.
Active period of weather as large upper level low shifts from
Southeastern Ontario and the ern Great Lakes early Saturday
night, and then slowly across northern New York and northern New
England through 12Z Monday. Widespread precipitation will
develop from west to east across the area during Saturday night
and continue into Sunday before slowly becoming more terrain
driven Sunday night. Precipitation will initially fall as rain
given very mild air mass in advance of the upper trough.
However, associated surface frontal zone shifts east of the
Adirondacks by midnight Saturday night, and gradually allows
colder air to filter in across nrn NY, and eventually across VT
during the daylight hrs Sunday. This will allow snow levels to
gradually fall across the region.
By 06Z Sunday, snow levels should drop to around 1500-2000ft,
which allows for a change over to snow across nearly all of the
nrn Adirondack Region. Should see at least a couple of inches of
snow accumulation by mid-morning Sunday in the Adirondacks.
Elsewhere in nrn NY, will see some wet snow mixing in Sunday
morning, and snow levels falling to the valley floors by
early Sunday afternoon. A bit slower transition in VT with
slower arrival of colder air, but should see accumulating snow
above 1000` Sunday in VT. As the upper level low moves east-
northeast Sunday night that will put the area in a more
favorable northwest flow pattern and orographic snows should
really develop at that point and increase snowfall rates. At
the same time...colder air will finally make it down to the
lower elevations in VT, and just about everyone will have the
potential to see accumulating snowfall during Sunday night. This
will be the first snowfall of the season on some valley
roadways, and absence of antecedent road treatment will leave
most paved surfaces quite prone to becoming snow covered/icy.
Thus, the Monday morning commute could be very slow across the
region, including in the Champlain Valley.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
As of 304 PM EST Friday...Long-duration orographic snowfall
expected to continue Monday into Monday night. Vertically
stacked low pressure will move very slowly ewd across central
and nrn ME during the period, with a persistent moist NW flow
regime across nrn NY and Vermont. Snowfall will be intermittent
in the valleys, but orographic/upslope forcing should result in
continued frequent snow showers along the wrn slopes of the
Green Mtns, nrn Adirondacks, and adjacent areas thru Monday
night. Storm total snowfall amts could reach 12"+ for the
higher summits of nrn Adirondacks and central/nrn VT. Generally
4-8" across the wrn slopes of the Green Mtns and in the
immediate St. Lawrence Valley. Lower snowfall amts in the
Champlain Valley, but again, Monday morning commute will likely
be very slow with slick, snow covered roadways even with lower
accumulations.
The vertically stacked low eventually shifts into the Canadian
Maritimes, with higher elevation snow showers diminishing late
Monday night into Tuesday. High pressure should bring a quieter
period of weather later Tuesday through Wednesday. Progressive
mid-upr level flow pattern brings next frontal system ewd from
the Great Lakes Wednesday night into Thanksgiving day. Still
considerable differences in low track between 12z GFS and ECMWF,
with ECMWF suggesting less direct impacts to the North Country,
while the GFS suggests mixed wintry precipitation is possible
with some travel impacts later Wednesday night and Thanksgiving
Day. Current forecast is for 40-50PoPs during the period. Will
continue to monitor this possible system for the holiday period.
&&
.AVIATION /03Z Saturday THROUGH Wednesday/...
Through 00Z Sunday...Mix of flight categories is expected over
the next 24 hours with primarily VFR at KBTV/KPBG/KRUT. At KMPV
and KSLK, like last night expect VLIFR radiational fog to
develop around 06Z give or take an hour, and continue through
12-14z. At KMSS, upstream near Montreal low IFR stratus deck has
developed and hi-res model progs show it slowly building
southwestward on light northeast flow into the northern St.
Lawrence Valley. Time of arrival is around 06z, and when it
builds in it should last until 12-14Z accompanied by some MVFR
vsby. After 14z, all site trend back to VFR.
Outlook 00Z Sunday through Wednesday...
00Z Sun - 12Z Tue: VFR trending to MVFR/IFR as a strong cold
front brings rain/snow showers to the region. Gusty winds and
LLWS possible.
12Z Tue - 00Z Wed: MVFR trending to VFR with high pressure
returning.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...Winter Storm Watch from Sunday morning through Monday evening
for VTZ003-006-008-016>019.
NY...Winter Storm Watch from late Saturday night through Monday
evening for NYZ026-027-029>031-034-087.
&&
$$
SYNOPSIS...Deal
NEAR TERM...JMG/Deal
SHORT TERM...Banacos
LONG TERM...Banacos
AVIATION...Lahiff
Area Forecast Discussion
National Weather Service Cleveland OH
715 PM EST Fri Nov 18 2016
.SYNOPSIS...
Low pressure over the western Great Lakes will move east and reach
Maine by early Sunday. A strong cold front associated with this
low will sweep east across the local area late tonight and early
Saturday. High pressure will begin to build over the region from
the southwest on Sunday.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
Regional radars depict a line of showers and thunderstorms moving
east across Indiana early this evening. Several severe
thunderstorm warnings have been issued with peak wind gusts in the
60-65 mph range. The stronger part of the line of convection is
expected to move northeast into Michigan. The airmass east of the
line becomes increasingly less favorable for convection with a
cap aloft and dewpoints in the 40s. Storms are both expected to
continue weakening as they approach the area with the near surface
environment becoming less conducive for strong wind gusts to reach
the surface. Whatever stable layer develops will be shallow
however so we will continue to monitor convection closely as it
moves into the area over the next couple hours. Wind gusts to 40
mph seem the more likely scenario but can not rule out an isolated
stronger gust. Sheer aloft is tremendous with the VAD wind profile
off the IWX radar showing 50 knots near 4000 feet.
Previous discussion...
Clear skies to begin this evening but clouds will increase from
the west during the evening. Have rain moving into western
counties after 8pm. The nam12 shows capes of 200to 800j.kg get
into the western counties this evening and lightning data shows a
decent amount of lightning along the front in eastern Illinois so
will have a slight chance of thunder west half through the
evening. Temps at 850mb will drop below freezing after 09z in the
western counties so all precip should be rain. will have
categorical pops for all and attempted to move the band of rain
east across the area through the night in the grids. Temps ahead
of the boundary will be quite mild into the night with warm
advection ahead of the system. Used HRRR and rap13 for insight
into hours temps with cold advection moving in from the west after
06z.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY NIGHT/...
Cold air will continue to fill in saturday behind a strong cold
front that will be exiting the area around sunrise.
Initially...slightly drier air and subsidence will fill in behind
the front but wrap around moisture will fill back in during the
day so will keep pops high chance to categorical with best chance
north. Precip type should be all rain to start but -8c air at
850mb fills in quickly from the west during the morning. This
should allow snow to mix in from the west during the morning with
the transition shifting east through the day reaching eastern
counties mid/late afternoon. Accums should not be much of anything
as ground temps will remain above freezing and air temps as well
should remain above freezing through the day. Saturday night most
precip will be snow except possibly over the lake where low level
warmth off the lake will change the snow to rain near the surface.
Based on Bufkit forecast soundings and coordinating with WPC and
surrounding offices...best snow accums should occur across NWRN PA
inland with the lakeshore likely too close to the warm Lake Erie
to accumulate warning criteria snow. Inland however...expect the
event to drop upwards of around a foot in the highest elevations
east. Have issued a Lake Effect Snow Watch. Started it at 21z
Saturday to cover any mix or transition but best chance for lake
effect snow comes after midnight. Lake/850mb instability reaches
extreme and winds stop consistent from the northwest after
midnight Saturday continuing into Sunday night before tapering
early Monday so will continue the watch through Monday morning.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
Cold air will continue to flow across the warmer waters of Lake Erie
on Monday. So this will keep Lake Effect snow showers going through
the day across NE OH in NW PA. They will likely linger the longest
over the higher terrain of inland NW PA. The snow should end at some
point Monday evening as high pressure increases its influence. This
area of high pressure will then become the dominant feature through
Tuesday afternoon. Models are then in good agreement on the movement
of another strong storm system that will emerge from the Southern
Plains. All locations will warm ahead of this low Tuesday into
Wednesday. Locations that do not get significant snow this weekend
will warm to near or slightly above seasonal levels. The cold front
will sweep across the area Wednesday night with another round of
showers. Winds will again increase with this storm system.
&&
.AVIATION /00Z Saturday THROUGH Wednesday/...
A season changing low pressure system will move across the Great
Lakes tonight...with multiple aviation concerns. Convective line
across eastern IN has run out ahead of the cold front and will
pose a threat to TOL/FDY. There are stronger elements within the
line where a gust in excess of 40 knots is possible...with 30
knots more likely. The line will continue to the northeast...with
expected diminishment over the next couple of hours. Outside of
the showers VFR conditions will continue through the early evening
hours. Additional showers possible overnight with the frontal
passage. Best estimate on timing would be around 06Z TOL to 10 or
11Z CLE. Non- VFR possible again with the showers and likely for a
couple of hours behind it. Winds will abruptly shift to the west
with the passage of the front and gusts will commence...continuing
through Saturday. Gusts to 40 knots possible. Lesser confidence on
what ceilings will do for the daytime Saturday...but thought is
that we will see a period of VFR before wrap around moisture
overspreads the entire area from midday through the late
afternoon. The transition to scattered snow showers reaches
western terminals late afternoon and evening across central
terminals.
OUTLOOK...Non-VFR conditions in showers will change to snow
Saturday night and linger into Monday...primarily across extreme
NE OH and NW PA. Non-VFR possible again Wednesday.
&&
.MARINE...
Strong area of low pressure will move across the western Great Lakes
tonight then redevelop over southern Ontario on Saturday. Expect the
pressure gradient to increase ahead of this storm system tonight but
the strongest winds will develop as the cold front passes. Strong
cold advection in the wake of the front will assist in bringing
stronger winds down to the surface. It appears gale conditions will
develop late Saturday morning into the afternoon then continue into
Sunday. Will go ahead and change the Gale Watch to a Gale Warning
shortly. Winds will decrease Sunday night with an extended period of
small craft conditions expected into Monday night. High pressure
will then briefly take control of the region Monday night into
Tuesday.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...None.
PA...Lake Effect Snow Watch from Saturday afternoon through Monday
morning for PAZ002-003.
MARINE...Gale Warning from 1 PM Saturday to 4 AM EST Monday for LEZ061-
145>149-165>169.
Gale Warning from 10 AM Saturday to 4 PM EST Sunday for
LEZ142>144-162>164.
&&
$$
SYNOPSIS...TK
NEAR TERM...KEC/TK
SHORT TERM...TK
LONG TERM...Mullen
AVIATION...Oudeman
MARINE...Mullen
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
948 PM EST Fri Nov 18 2016
.SYNOPSIS...
A strong cold front will move across the Carolinas from the west
on Saturday, bringing increased rain chances along the North Carolina
and Tennessee border. Temperatures in the wake of the front will drop
to approximately ten to fifteen degrees below normal on Sunday and
Monday before moderating through midweek. Another cold front will
approach the area by the middle of next week.
&&
.NEAR TERM /THROUGH SATURDAY/...
(Please also see updated Fire Wx section below.)
As of 930 PM: A vigorous upper level trough will lift NE out of
the lower MS Valley tonight and across the CWFA on Saturday. It
will take on a negative tilt and bring only a brief shot of
strong DPVA and some moisture along the TN/NC border Saturday
morning. Guidance is in good agreement on a weakening line of
showers crossing the TN Valley overnight and reaching the Smokies
just before daybreak. 00z NAM is generally a little drier than the
18z; QPF has trended down over the past few HRRR runs, which is
an even worse sign as it so often overdoes precip. So there still
appears no need for mentionable PoPs east of the mountains. Temps
will be above normal tonight, as SWLY flow increases. Expect good
radiative conditions to persist thru the early morning hours before
cloud cover ramps up and winds start to stir up the PBL.
On Saturday the big concern will be winds and fire danger (see
fire weather section below). As the upper trough axis shifts east,
a trailing NWLY upper jet will punch into the CWFA, and push a
dry cold front thru the area early in the morning. 18z NAM/GFS did
not trend significantly earlier/later with the frontal depiction
than the 12z runs, so timing of the effects still looks good. At
850 mb, winds will increase and veer to NW at about 35 to 45
kts behind the front by early afternoon. A tight temp gradient
will result in very strong CAA, with 850 mb temps plummeting from
around 10-12C at 12z to -5c by 00z Sunday along the northern Blue
Ridge escarpment. Gusty winds will approach wind advisory criteria
across the highest peaks of the NC mountains, generally along and
NE of the French Broad Valley. The gusty winds will continue into
Saturday night (3rd period), and given some uncertainty, I will
hold off on any wind headlines with this forecast package. Temps
will have a non-diurnal trend in the mountains due to the CAA,
with highs around mid-late morning, then falling temps in the
afternoon. Temps in the Piedmont will be tricky in the afternoon,
as well, but still expecting low-mid 60s, which is near normal.
&&
.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
As of 215 PM Friday, An anomalously strong long wave trough along
the East Coast will result in unseasonably cool and very dry
conditions across the forecast area through the short term. These
conditions will create very low afternoon RH across the area Sun and
Mon. Fire Wx concerns will therefore persist through the period.
Please see the Fire Wx discussion for details.
Wind concerns become amplified on Sat night, mainly along the
eastern escarpment of the Blue Ridge, as deep/unidirectional and
strong NW flow, with attendant strong mountain wave signal depicted
in model cross-sections. H8 winds in the latest NAM guidance are as
high as 55 kts near the Blue Ridge Sunday morning. This is still
quite strong, but about 10 kts less than yesterday`s guidance. There
is still concern that a nocturnal downslope/mtn wave high wind event
could occur along/near the eastern escarpment during this time, but
considering the trends in guidance, do not plan to issue a High Wind
Watch at this time.
Otherwise, winds will gradually diminish on Sunday, while cool temps
will prevail through the period, with temps averaging 5-10 degrees
below climo.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
As of 215 PM EST Friday, no significant changes to earlier thinking
with regard to Monday night and Tuesday, as models show an upper
ridge to the west and high pressure at the surface. This should keep
dry weather in place thru the end of Tuesday. Then, our attention
turns to the next system expected during the middle of the week.
Once again, the model guidance strongly suggests that precip will
not reach the fcst area before daybreak Wednesday. The new ECMWF has
the leading edge no closer than middle TN at 12Z Wednesday, and the
GEFS has NO members with precip at KAVL by that time. Even the
faster op-GFS does not have precip reaching the mtns until after 18Z
Wednesday, so like yesterday, the onset was pushed back until later
in the day. As for precip potential, the models have taken a
slightly more encouraging trend with better moisture transport from
the Gulf, altho forcing looks a bit weaker. Right now, think the
moisture is the more important factor. At least the downward and
drier trend has been halted, so precip probability still ramps up to
the chance range everywhere Wednesday evening. That being said,
there will probably be a lot of losers with this one, at least E of
the Blue Ridge. Precip amts are likely to be on the order of a
quarter-inch for those lucky ones. The precip should move east
quickly as the front passes in the early morning hours Thursday.
Will hold onto a slight chance over the Piedmont zones into Thursday
morning in deference to the slower ECMWF, altho the timing of the
GFS is preferred. Some light precip should linger on the TN border
of the nrn mountains into early Thursday afternoon. The rest of the
fcst will be dry as the next high pressure air mass moves in from
the west. Temps should remain fairly close to normal thru the period
as the air mass change behind the front will be offset with
downslope warming, with the expected nearly zonal flow aloft.
&&
.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
At KCLT and Elsewhere: Though the area will remain dry overnight,
pressures fall ahead of a swift cold front that will move through
in the morning. Winds will continue out of the SW, generally being
light overnight, but picking up rapidly after daybreak. KAVL may
see a westerly crosswind for a time near daybreak before the low
level flow veers solidly NW. WSHFT should reach KCLT by around
noon. A brief period of low VFR cigs is expected near the wind
shift line. Otherwise, the only restrictions (if any) around the
region will be due to smoke, with relatively dry and increasingly
breezy conditions precluding AM fog development. Smoke from the
foothills wildfires will linger near KAVL/KHKY tonight. These
plumes should be carried downwind into the eastern Piedmont (and
KCLT) in the late morning; strengthening winds and deeper mixing
should improve vsbys at midday.
Outlook: High pressure basically prevails into next week, with
fire wx conditions worsening as cold and dry Canadian air pushes
in Saturday and keeps humidity exceptionally low for several
days. Winds will remain strong over the high terrain Saturday night,
with gusty conditions returning to the Piedmont Sunday. Smoke
concentrations across the region will remain a concern for the
foreseeable future, especially during nights, when vsbys fall into
the MVFR range in some spots as the boundary layer decouples.
Confidence Table...
02-08Z 08-14Z 14-20Z 20-00Z
KCLT High 100% High 100% High 100% High 100%
KGSP High 100% High 100% High 100% High 100%
KAVL High 83% High 83% High 98% High 100%
KHKY High 83% High 100% Med 70% High 100%
KGMU High 100% High 100% High 100% High 100%
KAND High 100% High 100% High 100% High 100%
The percentage reflects the number of guidance members agreeing
with the scheduled TAF issuance flight rule category. Complete hourly
experimental aviation forecast consistency tables and ensemble forecasts
are available at the following link:
www.weather.gov/gsp/aviation
&&
.FIRE WEATHER...
Red Flag Warning in effect for Upstate SC Saturday. Fire Danger
Statement for the remainder of our area Sat through Sunday.
A cold front will cross the region from the west Saturday morning.
The area with the best chance of rain will be the NC mountain
counties along the TN border, with some snow possible on the
high peaks and ridge tops of the Smokies. Even in these areas,
any precipitation will be very light. Winds will come up sharply
from the northwest behind the front. Wind gusts of 25 to 40
mph are likely across much of the area Saturday, and across
the mountains Saturday night. Winds may even be stronger in
locations along the Blue Ridge, esp Sat night. Gusty conditions
will gradually diminish Sunday. Although RH is not quite expected
to reach criteria on Saturday (25-30 percent across the Upstate
and generally 30-45 percent across much of western NC, based
upon the volatile conditions re: fuels, collaboration with the
USFS, SCFC, and the Pinnacle Mountain Incident Command Team has
resulted in a decision to issue a Red Flag Warning for Upstate
SC for tomorrow. A Fire Danger Statement will be issued for the
remainder of the forecast area Sat through Sunday.
Very dry high pressure building into the area early in the
week will result in very low afternoon RH Sunday through at
least Tue. Meanwhile, winds will remain gusty across the mtns
through part of the day Sunday. While the current forecast does
not feature an overlap between RFW criteria winds and RH, it will
be close. Hence, a Fire Danger Statement has already been issued
valid at that time. Some offices/agencies are already interested
in an "impact-based" Fire Wx Watch for at least the NC Mountains,
and parts of Georgia. Rather than make a decision on such a watch
this evening without being able to consult land managers and fire
officials, we opted to let the Fire Danger Statement ride for now,
and will advise next shift to reach out to those representatives.
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...Fire Danger Statement from 9 AM EST Saturday through Sunday
evening for GAZ010-017-018-026-028-029.
NC...Fire Danger Statement from 9 AM EST Saturday through Sunday
evening for NCZ033-035>037-048>053-056>059-062>065-
068>072-082-501>510.
SC...Red Flag Warning from 11 AM to 8 PM EST Saturday for
SCZ001>008-010>013-019.
&&
$$
SYNOPSIS...JPT
NEAR TERM...ARK/Wimberley
SHORT TERM...JDL
LONG TERM...PM
AVIATION...Wimberley
FIRE WEATHER...JDL/Wimberley
Area Forecast Discussion
National Weather Service Wilmington OH
1013 PM EST Fri Nov 18 2016
.SYNOPSIS...
A cold front will push through tonight, bringing showers and
gusty winds. Colder air will settle in behind this front for the
rest of the weekend with bluster conditions, along with the
possibility of the first snow flakes of the season.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
Cold front is just west of the CWFA this evening. Showers continue
along and behind the front. Latest 00Z NAM and 02Z HRRR indicate
that the front will become more anafront in nature, with
precipitation along and mainly behind frontal passage. This is in
part to digging s/wv energy within a large scale mid level trough,
along with upper level divergence from a the RR quad of an upper
level jet. So, will maintain categorical PoPs overnight with
showers. Winds will shift to the west and will become gusty with
gusts in the 25 to 30 knots. Much colder air will filter in behind
the front, with lows ranging from the upper 30s west to the lower
40s east by sunrise.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/...
Mid/Upper level trof to pivot east through the Great Lakes
Saturday/Saturday night. In the wake of the overnight cold frontal
passage strong CAA will be ongoing Saturday morning. Expect near
steady temperatures on Saturday. In strong CAA pattern low level
lapse rates steepen leading to scattered showers with the best
chance of showers north. The rain will showers transition to snow
showers late in the afternoon into early evening. Looking at
forecast soundings and using the momentum transfer technique
expect wind gusts up to 40 mph.
As the upper trof axis pivots east, surface high pressure will
begin to southwest Ohio. Precipitation will diminish, ending from
sw to ne Saturday night. Expect lows from the mid 20s sw to near
30 ne.
Northwest flow aloft with surface high pressure building southeast
into the region Sunday. Cold temperatures Sunday with highs from
the upper 30s ne to the lower 40s sw.
Light winds, clear skies and dry airmass will allow for cold
temperatures Sunday night. Expect lows in the lower and middle 20s
by Monday morning.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
Monday will have dry weather under high pressure. Dry conditions
will continue through Tuesday as the high gradually moves east,
though clouds will increase well ahead of the next low pressure
system. Vigorous low pressure and its associated cold front will
bring the likelihood for showers on Wednesday. A few showers will
linger into Thursday in the chilly northwest flow behind the low.
High pressure centered to the southwest should provide dry weather
for Friday.
Temperatures will start a bit below normal, with highs Monday in the
low to mid 40s. Modest warm advection will allow near normal to
slightly above normal highs in the mid 40s to mid 50s for Tuesday
through Friday.
&&
.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
As low pressure rotates northeast into the Great Lakes tonight, a
trailing cold front will push east through the region. It appears
that instability will wane this evening that showers/storms
associated along and ahead of the front will be just showers as
they affect the terminals.
MVFR ceilings and visibilities can be expected with showers
overnight. Once behind frontal passage, a dry slot will move into
the region. Any wrap around precipitation will be of low coverage,
and probability, across the northern terminals as not to mention.
Winds will veer to the west behind the front with gusts in the 25
to 30 knot range.
On Saturday, surface low pressure and its parent mid level low
will occlude and rotate southeast across the eastern Great Lakes.
Predominate MVFR ceilings can be expected at the terminals until
the 18Z to 20Z time frame, when ceilings should lift to VFR. The
combination of a tight pressure gradient at the surface and
diurnal mixing will push winds gusts into the upper 20s to the
lower 30s by this time.
For Saturday night, clouds may scatter near the southwest
terminals of KCVG/KLUK while they linger across the north. A few
snow showers will be possible downwind of Lake Michigan near the
northern terminals. Gusty winds will gradually lower overnight.
OUTLOOK...MVFR ceilings and visibilities possible on Wednesday.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...None.
KY...None.
IN...None.
&&
$$
SYNOPSIS...Hickman/AR
NEAR TERM...Hickman
SHORT TERM...AR
LONG TERM...Coniglio
AVIATION...Hickman
Area Forecast Discussion
National Weather Service New Orleans LA
956 PM CST Fri Nov 18 2016
.UPDATE...
We made some changes to the precipitation field to fit the
ongoing trend. As stated in an earlier sounding discussion, this
evening sounding revealed strong cap with temp increase with
height of 4C from 830mb to 810mb. Line of convection pushing into
the area struggled to hold and weakened as forecast. We lowered
rain chances but maintained a slight chance for most points
overnight.
&&
.PREV DISCUSSION... /issued 705 PM CST Fri Nov 18 2016/
SOUNDING DISCUSSION...
Routine release terminated near Interstate 10 mile marker 40 in
Harrison County Mississippi at a height of 107,400 feet or 20.3
miles above the surface.
A little more moisture in tonight`s sounding with the
precipitable water value at 0.90 inches. There is some moisture
below an inversion based near 825 mb, as well as above 400 mb,
with very dry air in between. Moisture levels will increase during
the evening, as the 00Z LCH sounding has a precipitable water
value around 1.4 inches. The dry layer on the LCH sounding is only
between 700 and 550 mb.
The inversion on the LIX sounding has things capped presently, but
this is expected to erode as the front nears. With the loss of
surface heating, however, we should lose some of the instability.
Anticipate a weakening trend to the thunderstorms approaching the
west end of our CWA. Freezing level tonight is near 13,800 feet
with a wet bulb zero level at 8,000 feet. The -20C level is near
22,500 feet.
Southeast winds at the surface became southwest by 925 mb, then
westerly through 800 mb, then primarily southwest through 50 mb
with a brief exception between 340 and 270 mb. Peak wind through
50 mb was a 50 knot wind near 47,000 feet. 35
PREV DISCUSSION... /issued 351 PM CST Fri Nov 18 2016/
SHORT TERM...
The upper level ridge that was over the area is quickly
progressing east today while a trough is moving across the
central/high plains. A strong cold front on the leading edge of
the trough is currently moving across north Louisiana Friday and
should entering the northwestern CWA between sunset and 03z.
Shouldn`t take but about 6 hours for the front to move completely
across the forecast area. In terms of rain, radar trends over the
last few hours shows some filling in of the line as it moved from
TX into LA. The HRRR and even medium range models shows this
holding together through the northwestern third of the CWA before
breaking up and diminishing in coverage from there southeastward.
The latest forecast pops were adjusted to attempt to show this
with near 50% chance of rain NW of BTR down to 20-30% along the LA
coast.
LONG TERM...
Post frontal air mass will be the coldest temperatures the region
has seen since last spring. Highs over the weekend will barely reach
into the lower 60s. Elevated winds behind the front will keep temps
from falling too much Saturday night, but still likely to see mid to
upper 30s in the northern half of the CWA (40-50 south). Monday
morning will be the coldest and dropped forecast lows a couple more
degrees from the previous forecast. MAV/MET guidance looks to better
capture the clear/calm conditions compared to blended models, so
thinking lows in the lower to mid 30s along and north of I-12 in LA
and I-10 in MS with a handful of locations dropping to freezing or
even just below 30. Widespread frost is expected in those areas.
Temperatures will then begin to moderate Monday and Tuesday as a
weak upper ridge slides across the northern Gulf Coast. Following
on its heels, a more southerly oriented trough will pass across the
Rockies Tuesday and shoot off to the northeast Wednesday. This will
bring another front to the forecast area but with the upper trough
moving away from the area then, the front will likely washout as it
gets here. Some rain expected but should be fairly weak convection
an decreasing in coverage as the boundary moves in.
Meffer
AVIATION...
mostly VFR conditions are expected through Saturday. The exception
will be as a convective band of isolated to scattered SHRA and a few
TSRA, associated with a strong cold front, move through southeast LA
and south MS from northwest to southeast between 03z and 11z
Saturday. Isolated SHRA could also develop late this afternoon and
early this evening in advance of the main band. Some lower MVFR
category conditions due to CIGS and/or VSBY may impact the
terminals, so have indicated VCSH or PROB30 -SHRA. Stronger and
gusty northwest to north winds will follow cold frontal passage late
tonight into Saturday. 22/TD
MARINE...
Strong cold front is expected to move through Lakes Maurepas and
Pontchartrain between 2 and 3 am tonight and the sounds and coastal
waters between 3 am and 9 am Saturday. Small Craft Advisory (SCA)
conditions with occasional gusts to near gale force are expected to
develop fairly quickly behind the front, so the timing of the start
of SCA headline has been set accordingly. SCA conditions are then to
continue through at least mid morning on Sunday as colder air and
high pressure build into the region. The exception is Lakes
Pontchartrain and Maurepas where there should be a drop below SCA
Saturday afternoon before winds and waves pick back up in the
evening and overnight hours Saturday night.
High pressure will build in closer to the coast Sunday afternoon,
then gradually move east Monday into Tuesday. Winds and seas are
expected to subside from late Sunday morning through Monday. Another
weaker cold front is expected to move through the marine area
Wednesday night shifting winds from southerly back to northerly
again, but staying below SCA criteria. 22/TD
DECISION SUPPORT...
DSS code: Blue
Deployed: None.
Activation: None.
Activities: Drought Monitoring, Enhanced Fire Danger Risk Saturday,
and Small Craft Advisory late tonight through Sunday morning.
Decision Support Services (DSS) Code Legend
Green = No weather impacts that require action.
Blue = Long-fused watch, warning, or advisory in effect or
high visibility event.
Yellow = Heightened impacts with short-fused watch, warning or
advisory issuances; radar support.
Orange = High Impacts; Slight to Moderate risk severe; nearby
tropical events; HazMat or other large episodes.
Red = Full engagement for Moderate risk of severe and/or
direct tropical threats; Events of National Significance.
&&
.PRELIMINARY POINT TEMPS/POPS...
MCB 47 61 34 63 / 50 0 0 0
BTR 50 62 35 62 / 50 0 0 0
ASD 53 63 37 63 / 20 0 0 0
MSY 56 62 45 62 / 30 0 0 0
GPT 56 65 38 62 / 20 10 0 0
PQL 55 65 36 63 / 20 10 0 0
&&
.LIX WATCHES/WARNINGS/ADVISORIES...
LA...None.
GM...Small Craft Advisory from 6 AM Saturday to noon CST Sunday for
GMZ532-534-536-538-550-552-555-557-570-572-575-577.
Small Craft Advisory from 3 AM to noon CST Saturday for GMZ530.
MS...None.
GM...Small Craft Advisory from 6 AM Saturday to noon CST Sunday for
GMZ534-536-538-550-552-555-557-570-572-575-577.
&&
$$
Area Forecast Discussion
National Weather Service San Francisco Bay Area
337 PM PST Fri Nov 18 2016
...Widespread Rain Expected Over the Weekend...
.SYNOPSIS...Widespread rain is forecast to spread from north to
south across the district beginning tonight through Saturday.
Periods of rain will continue on Sunday. Dry weather will likely
return by Monday, but rain is possible once again by the middle of
next week.
&&
.DISCUSSION...As of 3:00 PM PST Friday...In general everything
appears to be coming together for a substantial change in the
weather this weekend as a Pacific Storm System continues to
approach the West Coast. Currently the center of circulation is
around 750 miles west of Seattle while a longwave trough stretches
southwestward. At the same time a substantial cold front ahead and
south of the low will advance to the coast later today with
associated rainfall forecast to move into the North Bay starting
this evening. KBHX radar nicely shows the leading edge of
precipitation which the HRRR appears to have initialized close to
reality.
Rainfall will move to the NW Sonoma coast close to 8 PM and then
down to San Francisco around 4 AM. Rain will continue to progress
to the south and be in the Monterey Bay Region just after sunrise.
Rain rates will pick up during the day as the cold front moves to
our CWA which could lead to moderate or even briefly heavy
rainfall at times. Behind the front rain is still expected to
continue through Sunday, although coverage and amounts will be
considerably less. Totals are only slightly different from
yesterday and the overnight shift with the greatest numbers still
forecast for the North Bay. Still looking at 2-4" for the North
Bay Mountains with 1-2" for the rest of the North Bay and the
Santa Cruz Mountains. Around SF Bay generally 2/3" to 1 1/3" can
be expected with lesser amounts to the south.
Winds will be the other story with gusty southerly winds forecast
just ahead of the front. Based off of latest guidance which now
has speeds near 50 KT just above the surface both along the coast
and some of the higher elevation spots, a wind advisory is now in
effect (please see SFONPWMTR for details). Even locations around
San Francisco Bay will see gusty conditions -- possibly to around
40 MPH on Saturday.
After a dry Monday and Tuesday the models indicate that two more
systems will move through the remainder of next week. Timing has
gotten a bit better with most of the solutions now brining rain
through on Wednesday and Friday. Neither of these systems appear
strong.
Both the 6 to 10 and 8 to 14 day outlooks continue to favor wetter
than normal conditions.
&&
.AVIATION...As of 3:35 PM PST Friday...For 00z tafs. Approaching
storm system will bring deteriorating ceilings, rain, and
increasing southerly winds through tonight and into Saturday.
Cigs generally VFR this evening then decreasing down to MVFR
from north to south tonight and Saturday morning as front
approaches. Rain will begin to move into the North Bay as early
as 04Z Sat before spreading southward through the remainder of
Friday Night and Saturday. In addition, southerly wind gusts will
strengthen as the front approaches with local gusts up to 35 mph
expected late tonight and through much of Saturday.
Vicinity of KSFO...VFR through the evening rush. Then becoming
MVFR late tonight into Saturday morning as front approaches. Rain
will begin after midnight and continue through much of Saturday.
Visibility and cigs will likely decrease briefly during periods
of heavier rain, mostly likely on Saturday morning. Southerly
winds will gradually increase overnight with gusts up to 30 KT
possible late Friday Night and through much of Saturday.
Confidence moderate.
SFO Bridge Approach...Similar to KSFO.
Monterey Bay Terminals...VFR expected through Friday night.
MVFR cigs likely to develop by late Saturday morning as frontal
rain band approaches. Rain will then continue through Saturday
afternoon with brief reduced visibility and lower cigs with
heavier rain on Saturday afternoon. Southerly winds will increase
on Saturday morning and continue gusty through Saturday afternoon.
Confidence moderate.
&&
.MARINE...as of 02:21 PM PST Friday...Southerly winds will
increase significantly tonight and into tomorrow ahead of an
approaching storm system. gale force gusts and periodically
moderate to heavy rain are expected as the front moves into the
area. gusts will generally range from 35 to 45 kt with localized
bursts to 50 kt possible. winds will veer northerly behind the
front by sunday with a building nw swell.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
.Tngt...Wind Advisory...Coastal sections as well as the East
Bay Hills and Santa Cruz Mountains.
SCA...Pigeon Pt to Pt Pinos 0-10 nm
SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm
GLW...Pigeon Pt to Pt Pinos 0-10 nm from 4 AM
GLW...Pt Pinos to Pt Piedras Blancas 0-10 nm from 4 AM
GLW...Pt Arena to Pigeon Pt 10-60 nm
SCA...Mry Bay until 1 AM
SCA...Pt Reyes to Pigeon Pt 0-10 nm until 1 AM
SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm until 1 AM
GLW...Pt Reyes to Pigeon Pt 0-10 nm from 1 AM
GLW...Pigeon Pt to Pt Piedras Blancas 10-60 nm from 1 AM
SCA...Pt Arena to Pt Reyes 0-10 nm until 7 PM
GLW...Pt Arena to Pt Reyes 0-10 nm from 7 PM
SCA...SF Bay from 1 AM
&&
$$
PUBLIC FORECAST: Bell
AVIATION: Dykema
MARINE: DRP
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Area Forecast Discussion
National Weather Service Mount Holly NJ
923 PM EST Fri Nov 18 2016
.SYNOPSIS...
High pressure will remain across the area tonight before moving
offshore saturday morning. A strong cold front will cross the area
Saturday evening as low pressure strengthens over eastern Canada.
The low will influence our weather into early next week. High
pressure will build across the area Tuesday and Wednesday. Another
disturbance will approach the region later next week.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
Surface high pressure/upper ridge will remain positioned along the
eastern U.S. seaboard through tonight. During this time, the
forecast area will remain situated between a downstream low located
about 500 miles east of the mid-Atlantic coast and an upstream low
that will be moving through the Upper Midwest.
Under clear skies, temperatures will drop quickly once the the
sun sets and the boundary layer decouples. Undercut stat guidance,
especially in the usual locales that radiate effectively (e.g.,
rural areas, sheltered valleys, Pine Barrens), by several degrees.
Conversely, raised temperatures for tonight from stat guidance
along the ridges of northeastern PA and northwestern NJ. The
presence of a shallow thermal inversion near the surface will
result in overnight temperatures at these higher elevations (above
1000 ft ASL) that area 10F or more higher than the nearby valleys.
Temperatures in these locations have been quite variable this
evening and may trend a few degrees up or down overnight.
Bufkit analysis of the RAP and NAM both show the potential for
for the surface to become saturated toward sunrise for most of the
region. With light winds, some patchy fog is likely to form.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/...
Low pressure is forecast to track northeastward toward the St.
Lawrence Valley on Saturday. Meanwhile, a strong cold front with
this system will cross the Appalachians in the morning and then move
in from the west during the mid to late afternoon.
Saturday looks to be the last mild day in the foreseeable future
with the region situated in the warm sector ahead of the cold front.
Although temperatures will drop quickly in wake of the fropa, the
front looks to arrive late enough in the day to allow temperatures
across the forecast area to climb well into the 60s during the
afternoon. Temperatures in the low 70s are reachable, especially in
the coastal plain, where thicker cloud cover has the best chance to
hold off until after peak heating.
A band of showers are likely to accompany the front late in the day.
Despite a limited moisture feed, strong low-level convergence along
the front and DPVA with an upper shortwave trough will provide
enough lift for precip. Model soundings show meager instability in
the warm sector, so thunderstorms were not put in the forecast.
S-SE winds ahead of the front will increase during the day and could
gust to around 20 mph during the afternoon. Winds sharply veer out
of the NW behind the front and quickly become breezy late in the day
(initially across E PA and E MD).
&&
.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
The big changes that have been advertised for the past few days will
arrive at the beginning of the long term. A sharp cold front will be
in the process of crossing the area Wednesday evening. Strong gusty
winds and colder temperatures will push across the area.
Temperatures will plummet through the 50s and 40s overnight and
eventually bottom out in the 30s across the region. The gusty winds
will create a unpleasant wind chill by Sunday morning in the 20s
area-wide. The best chc for showers with the front will be across
the srn Poconos and nrn NJ with some likely pops there, elsewhere
pops will only be in the chc range with more limited moisture and
dynamics in those areas. Winds will shift to W or NW behind the
front and gust to 30-40 mph for the overnight period and into Sunday
morning. A wind advisory may be needed if speeds a few more mph are
indicated in future fcsts. The rain showers across the north may
change over to snow showers by Sunday across the srn Poconos and
Sussex county NJ with the colder air arriving.
The gusty winds and cold conditions will continue Sunday and into
Monday across the area. Showers will be confined to the nrn areas
where rain and snow showers will occur. It`s possible that some
small accumulations and some lower visibilities with snow showers
may occur up north. We will keep the mention of that in the HWO for
now. Highs both Sunday and Monday will be in the 40s for most areas
and 30s across the north. These temps are some 20 to 25 less than
what will occur on Saturday.
High pressure will build across the area later Monday and remain in
control of the weather into the middle of next week. We will have
fair weather in this period with temperatures continuing to run
several degrees below normal. Winds will remain gusty Monday, but
should be quieter Tuesday.
Another disturbance will approach towards the end of next week.
Presently the latest 12z ECMWF is slower with the system compared to
the 12Z GFS. We will continue with slight chc pops for Wed night and
Chc pops for Thu into Friday. Temperatures will continue seasonably
cool this period, the precip should be rain over most areas, but
could be some nighttime snow showers across the climatologically
cooler areas (Srn Poconos and nrn NJ).
&&
.AVIATION /02Z SATURDAY THROUGH WEDNESDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY and surrounding areas.
Patchy ground fog may develop toward sunrise at most TAF sites.
Have only included MVFR visibilities in the TAFs of KRDG, KABE and
KMIV where the risk is the highest in these fog prone terminals.
SE winds increase to 5-10 kt during the late morning and afternoon.
A few gusts of 15-20 kt are possible during the afternoon. Winds
sharply veer out of the NW behind the front and quickly become
breezy from west to east between 21Z Saturday and 00Z Sunday.
Showers become more likely by 22z for KRDG and after 00Z E of
KPHL.
OUTLOOK...
Sat evening...Restrictions in showers possible early. Gusty W/NW
winds.
Sunday thru Monday...VFR and gusty winds. Few showers far N/W.
Monday night thru Wed...VFR expected.
&&
.MARINE...
Light and variable winds through tonight. Seas will be below 3 ft.
Southeasterly winds will strengthen on Saturday ahead of a cold
front. Poor lapse-rates should inhibit stronger winds aloft from
mixing down to the surface except maybe right along the coast. Gusts
to near 25 kt may develop in these near-shore waters later in the
afternoon but did not issue a short-duration SCA with a Gale Warning
going into effect Saturday evening.
OUTLOOK...
Sat night thru Sun night...Gale warning. Sct showers Sat evening.
Monday thru Tue evening...SCA conditions with fair weather.
&&
.TIDES/COASTAL FLOODING...
Strong northwesterly flow developing Sat night/Sunday with a
chance of blowout tides with the Sunday Evening high tide,
primarily on the bay where funneling effects will increase the
risk. However, the wind direction isn`t directly down-bay, so
there remains uncertainty of exactly how low the water levels will
be. We will continue to monitor as we get closer.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...Gale Warning from 6 PM Saturday to 6 AM EST Monday for ANZ430-
431-450>455.
&&
$$
Synopsis...O`Hara
Near Term...Gaines/Klein
Short Term...Johnson
Long Term...O`Hara
Aviation...Gaines/Klein/O`Hara
Marine...Klein/O`Hara
Tides/Coastal Flooding...
Area Forecast Discussion
National Weather Service Denver/Boulder CO
207 AM MST Sat Nov 19 2016
.SHORT TERM...(Today and tonight)
Issued at 207 AM MST Sat Nov 19 2016
The mid and upper-level ridge axis will shift over the state of
Colorado throughout the day and will keep us dry today and
tonight. At the surface, high pressure over the Central Plains
states will continue to shift east. Combined with weak lee
troughing caused by westerly flow over the mountains, southerly
flow across the eastern quarter of Colorado will prevail.
One pretty significant change to today`s forecast is the expected
high temperatures. With lingering snow cover across the NE
quadrant of Colorado, a very strong low-level temperature
inversion has developed. Downslope flow is not expected to
penetrate this inversion, instead we expect the warming flow to be
confined to the foothills and higher terrain. There does not
appear to be any well-defined mechanism to mix out the low-level
inversion as surface winds will be light and out of the ESE in
between the Cheyenne Ridge and Palmer Divide and points to the
east across much of Weld County. All the high res models keep the
inversion in place, with the NAM the coldest of all guidance. Am
inclined to follow the HRRR and RAP solutions with upper 30s for
highs across the snow cover areas and where the inversion is
strongest, roughly just west of I-25...to north of the C-470
beltway and I-70...and east to the Kansas Border. The foothills
and Palmer Divide should warm into the low 50s.
Tonight we expect wave clouds to develop which would keep min
temperatures in the low 30s across the plains adjacent to the
foothills and across the urban corridor. Across the plains of NE
CO after an expected cold day with little snow melt, lows could
dip into the upper teens across the favored locations of Weld,
Morgan, and Logan Counties. Expect low to mid 20s elsewhere across
the Eastern plains. The mountains should see lows in the 20s.
.LONG TERM...(Sunday through Friday)
Issued at 207 AM MST Sat Nov 19 2016
The upper ridge will begin flattening and moving east Sunday as a
system digs into the western Great Basin overnight. Forecast
cross sections and soundings show wave clouds likely over the area
starting in the morning, which should limit how cold we start the
day out. 700 mb temperatures won`t be changing much over today,
yet expecting some warming with the inversion not being so
strong, but may be impacted by the wave clouds. The system should
push moisture into southwestern Colorado Sunday night, but should
stay out of the northern and central mountains. The NAM is the
slowest with the incoming system, though takes a piece of jet
energy and shows precipitation over the northern mountains already
after midnight. For now will ignore the outlier.
The upper trough will push into the state Monday with snow
beginning over the northern and central mountains. Could see some
banding of snow with this as the southwest-northeast oriented jet
moves east across the area. Snow levels look to be around 9-9.5kft
during the day. A surface low will deepen over the central to
southeastern plains, which will likely start pulling in cooler air
from the north during the afternoon. With some weak to moderate
upward QG motion over the area, could see some rain and possible
snow mixed in over the plains. The surface low heads out
southeast and into Kansas overnight which may downslope some of
the southern metro and foothills areas, but the QG may be able to
overcome this. Snow levels are progged anywhere between 4000 ft on
the CMC to 7000 feet on the EC, with the NAM and GFS closer to
6000 ft Monday night. Tough to decide at this point with the
model variability. Modeled snow accumulation shows mainly less
than an inch over most of the plains except 2-4 inches over the
areas closer to the foothills and Palmer Divide. Not confident in
amounts however due to potential downsloping. Over the mountains
however, more impactful amounts are possible, with several inches
at higher elevations. Possible banding could produce more in
localized areas. May need a highlight for Monday afternoon through
Tuesday morning, will continue to assess.
Strong north to northwesterly winds are expected after midnight
and into Tuesday afternoon before they decrease quickly. As the
upper trough pushes into Kansas, moisture on the backside will
keep snow going over the mountains most of the day while areas of
rain and snow and much cooler temperatures over the plains should
push east out of the area by the afternoon. Skies should clear
overnight for cold minimum temperatures.
Upper ridging re- establishes itself for Wednesday, then a couple
weak shortwaves pass through the almost zonal flow aloft for
Thursday and Friday with little impact, both in moisture and
temperature, though the northern mountains may see a few snow
showers. Saturday will have the best shot of seeing any moisture
as a deeper trough is expected to push in from the west, but this
should stay in the mountains.
&&
.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 207 AM MST Sat Nov 19 2016
VFR conditions expected through Saturday night and into Sunday
morning. Winds should be 10 kts or less all terminals. At KDEN
expect the wind direction out of the ESE this afternoon then
going to southerly after 02Z.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...Schlatter
LONG TERM...Kriederman
AVIATION...Schlatter
Area Forecast Discussion
National Weather Service Lincoln IL
315 AM CST Sat Nov 19 2016
.SHORT TERM...(Today and tonight)
ISSUED AT 315 AM CST Sat Nov 19 2016
The pressure gradient between a 996mb low over Lake Superior and a
1037mb high across western Kansas will remain sufficiently tight to
produce wind gusts of 35 to 40mph through the morning. Even though
sustained winds and gusts will likely remain just shy of advisory
criteria, decided to extend the Wind Advisory through noon
along/north of a Rushville to Bloomington line. As the low slowly
shifts further northeastward and the gradient begins to relax, wind
gusts will drop to less than 30mph this afternoon. Skies will
initially be overcast early this morning: however, low clouds will
steadily advect/dissipate from west to east across the region as the
day progresses. Latest HRRR suggests skies will become mostly sunny
across all but the far E/NE KILX CWA from Bloomington to Paris by
midday...then everywhere by late afternoon. Thanks to strong CAA,
high temperatures will be considerably colder than yesterday...with
readings ranging from the upper 30s north of I-74 to the middle 40s
far southwest around Jacksonville. Winds will continue to decrease
tonight, although with the Plains high remaining west of the
Mississippi River through 12z Sun, think 8-12mph winds will continue
throughout the night. This will help keep the atmosphere mixed and
limit maximum radiational cooling, resulting in lows remaining in
the lower to middle 20s.
&&
.LONG TERM...(Sunday through Friday)
ISSUED AT 315 AM CST Sat Nov 19 2016
Cool/dry weather will prevail through Monday, before the next storm
system approaches Illinois by mid-week. 00z Nov 19 models have
continued the recent trend of slowing the system and tracking it
slightly further north...with both the GFS and ECMWF now developing
a surface low in the lee of the Rockies across eastern Colorado
Monday night, then tracking it E/NE into northeast Iowa by 12z Wed.
This particular track will put central Illinois in the warm sector
of the storm, with profiles supporting all rain. Given slower
arrival, have removed PoPs entirely for Tuesday morning with rain
developing across the area mainly Tuesday afternoon and evening. GFS
MUCAPE values remain negligible at this point, but given track of
surface low to the W/NW, isolated thunder may be possible. Once the
low lifts into the Great Lakes, wrap-around moisture will bring a
continued chance for rain showers into Wednesday before conditions
dry out for the end of the forecast period.
&&
.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1124 PM CST Fri Nov 18 2016
West winds trying to diminish a bit late this evening, but the
pressure gradient remains tight enough that frequent gusts of
25-30 knots are likely into much of Saturday, before finally
diminishing late afternoon. Large stratocumulus area has been on
the low end of the VFR range, but the western fringes are showing
some brief dips to near or below 3,000 feet. Have included TEMPO
periods at all sites late in the night as the back edge of the
cloud shield arrives. General clearing trend will take place mid
to late morning at all TAF sites.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
Wind Advisory until noon CST today for ILZ027>031-036>038-041.
&&
$$
SHORT TERM...Barnes
LONG TERM...Barnes
AVIATION...Geelhart
Area Forecast Discussion
National Weather Service Midland/Odessa TX
1140 PM CST Fri Nov 18 2016
.UPDATE...
Issued update to include Gaines County in the Hard Freeze Warning.
&&
.DISCUSSION...
Temperatures are already in the mid 30s in Gaines County and are
expected to decrease throughout the night. The RAP13 model is
showing temperatures in the mid 20s by 12z and the HRRR is showing
temperatures of lower to mid 20s across western sections of Gaines
County. With temperatures likely to reach 28 degrees or below for
a good portion of Gaines County, the Freeze Warning has been
upgraded to a Hard Freeze Warning.
&&
PREV DISCUSSION... /issued 229 PM CST Fri Nov 18 2016/
DISCUSSION...
A strong cold front moved through the area this morning and it
will bring the first freeze of the season to many areas north of
I-10 tonight. Brisk north winds will subside after sunset and
combined with clear skies will provide optimal conditions for
radiational cooling. A hard freeze is possible across much of
southeast New Mexico and the Davis Mountains which would require a
little extra precaution, mainly in the protection of exposed
outdoor pipes.
Cold air behind the front will dam against the Guadalupe Mountains
causing strong northeast winds at Guadalupe Pass tonight and
tomorrow morning. Wind speeds may briefly reach high wind warning
criteria but the event will be marginal and very localized so
opted against issuing a warning at this time.
The upper air pattern is progressive so the cold air will not last
long with warmer temperatures expected Sunday and Monday before
the next upper trough arrives Tuesday. This trough will move
across the Rockies and into the Central Plains in a trajectory
that is unfavorable for precipitation. Winds ahead of the trough
will push most moisture east of our area before the upper lift
arrives making rain doubtful, so have only gone with slight chance
PoPs for Tue. The trough will bring our next front on Wednesday
which will not be as strong as the one seen today with lows
holding above freezing and highs near normal for this time of
year.
Hennig
&&
.PRELIMINARY POINT TEMPS/POPS...
Big Spring 30 56 37 67 / 0 0 0 0
Carlsbad 27 56 29 69 / 0 0 0 0
Dryden 39 60 37 66 / 0 0 0 0
Fort Stockton 33 59 40 74 / 0 0 0 0
Guadalupe Pass 30 52 37 65 / 0 0 0 0
Hobbs 27 54 31 67 / 0 0 0 0
Marfa 26 56 26 67 / 0 0 0 0
Midland Intl Airport 30 56 36 67 / 0 0 0 0
Odessa 31 56 36 67 / 0 0 0 0
Wink 31 58 32 69 / 0 0 0 0
&&
.MAF WATCHES/WARNINGS/ADVISORIES...
NM...Freeze Warning until 8 AM MST Saturday for Guadalupe Mountains
of Eddy County-Southern Lea County.
Hard Freeze Warning until 8 AM MST Saturday for Central Lea
County-Eddy County Plains-Northern Lea County.
TX...Freeze Warning until 9 AM CST /8 AM MST/ Saturday for Andrews-
Borden-Crane-Dawson-Ector-Glasscock-Guadalupe Mountains-
Howard-Loving-Martin-Midland-Mitchell-Reagan-Reeves County
and Upper Trans Pecos-Scurry-Upton-Van Horn and Highway 54
Corridor-Ward-Winkler.
Hard Freeze Warning until 9 AM CST Saturday for Davis/Apache
Mountains Area-Gaines-Marfa Plateau.
&&
$$
99/99
Please see the previous forecast discussion below for more details
on this winter storm and the active weather pattern through the
week.
&&
.AVIATION...19/06Z TAF cycle...Rain continues to overspread the area
from the southwest as a front approaches this evening. Flight
conditions will be a mix of VFR and MVFR through the evening, then
lowering to IFR at times as heavier precipitation associated with
the front itself moves through late tonight and early tomorrow. The
most likely locations for the lower conditions will be along the
coast and in the mountains as well as near Mt. Shasta where snow is
expected to develop overnight. Low level wind shear will also be an
issue as the front approaches, especially along the coast. Strong
winds have already developed in the Shasta Valley and east side and
will continue until through Saturday. Therefore, turbulence will be
increasing over California, near and to the north of the Siskiyous
and east of the Cascades. -Wright/SK
Note: The ceilometer at FAA site KOTH is out of service, so there
will be no ceiling observations available generally between the
hours of 04Z and 14Z.
&&
.MARINE...Updated 1030 PM PST Friday 18 November 2016...A strong cold
front is moving through the waters this evening. Gales will continue
through the evening most areas, then winds will drop below gales
later tonight as the front moves onshore, but seas will remain very
steep due to a mix of wind wave and fresh swell. Gales will
redevelop tomorrow afternoon and evening as another low pressure
system moves inside 130W and pushes a front toward the coast.
We will see a break in winds and seas Monday, but another front
brings south gales and very steep seas Tuesday. The stormy pattern
continues for the foreseeable future with cold fronts roughly every
other day all the way into next weekend. -Wright
&&
.PREV DISCUSSION... /Issued 320 PM PST Fri Nov 18 2016/
SHORT TERM...A front is located about 150 miles off the Southern
Oregon coast. This front will gradually move inland across the
area tonight and Saturday morning. Ahead of and with the frontal
passage expect strong gusty winds over portions of the area. Also
southwest portions of the area, mainly Curry and Siskiyou
counties, will see moderate to heavy precipitation.
South winds have increased this afternoon in the Shasta Valley,
over the mountains and for areas east of the Cascades. South winds
have also begun to increase in the southern Rogue Valley. As a jet
aloft moves into the area this evening and tonight and the surface
pressure gradient increases, expect winds gusts up to 65 mph in
the southern Shasta Valley with winds gusting to 45-50 mph in the
Rogue Valley. Winds will increase during the evening and remain
strong overnight and into Saturday morning. Winds are expected to
lower behind the front late Saturday morning and Saturday
afternoon but remain breezy. East of the Cascades strong gusty
winds are likely over the mountains, including the Warners, Hart
Mountains and Summer Rim area, and in the Paisley to Silver Lake
area with winds peaking late this evening through Saturday
morning then continued gusty winds into Saturday night and Sunday
morning as another weaker jet max move into the area. For details
on the winds see the NPWMFR.
As the front moves inland tonight, moderate to heavy precipitation
is forecast into Curry and Siskiyou counties. Heavy precipitation
amounts around the Mount Shasta in south central Siskiyou county
combined with lowering snow levels will bring winter storm
conditions. Due to upslope effects from very moist air and a mid
level jet, snow levels are expected to lower to 4000 feet in the
Mount Shasta area during the evening then down to near 3500 feet
elevation late tonight and early Saturday morning. Snow
accumulation of 5 to 10 inches is expected above 3500 feet
elevation for southern Siskiyou County with higher amounts above
6000 feet elevation. Of note, a heavy wet snow is expected for
the 3500 to 4000 ft elevations and snow accumulations may vary
significantly with some areas seeing more and other less. This may
be of most concern near Mount Shasta City where snow accumulations
around 4 to 7 inches are possible. For mountain passes such as
near Snowmans Summit on highway 89, expect greater snow
accumulations tonight through Saturday with accumulations around 6
to 12 inches. For details on the winter storm warning conditions
see the WSWMFR for details.
West of the Cascades in Southern Oregon expect snow levels to
remain fairly high around 5000 to 5500 feet with a mix of light to
moderate precipitation. Over the Siskiyous and from the Cascades
east in Southern Oregon as well as into Modoc County expect snow
levels to lower to around 4000 to 4500 feet tonight and Saturday
morning with light precipitation. This will result some light snow
accumulation possible especially over the mountains.
Behind the front, an upper level trough moves into the region
Saturday afternoon through Sunday night. Shortwaves embedded in
this trough will move into the region late Saturday through Sunday
bringing additional precipitation with snow levels varying from
around 4500 to 5500 feet. During this period expect the focus for
precipitation to be from the coast into Siskiyou County for this
period but all areas will see period of light or moderate
precipitation.
Lastly, behind the frontal passage and with the upper trough
expect instability over the coastal waters with a slight chance
for thunderstorms tonight through Saturday.
Early next week, expect a break in the pattern with a shortwave
upper level ridge moving into the region late Monday with
diminishing shower chances over the area. This break in the active
pattern is expected to be brief though.
LONG TERM...Tuesday through Friday Night...Models are in good
agreement regarding the wet and active pattern during the long term.
While there are some variations in the strength and timing of the
individual features, there is much less uncertainty regarding the
overall pattern. It would be very safe to say that the area will see
a continuation of the wet weather through the remainder of next
week.
Very deep troughing over Siberia will throw off several waves
during the week, each passing across the north Pacific in quick
succession. The first of the three systems expected during the long
term will arrive on Tuesday, followed by another Wednesday night
into Thanksgiving, and yet another Friday night. Each system will
have a brief break in between, but in some cases, this will be
barely noticeable. There are no particularly telling features
appearing in any of the model suites that would single out any of
these system as particularly strong or exceptional, but this could
easily change in coming model runs. For now, have trended the wind
and rain forecasts during each system towards values typical with
our normal wet season storms, with heavy rain and gusty winds at the
coast, and strong winds across the East Side and in the Shasta
Valley.
One item of note will be snow levels, which are expected to hover
between 3000 and 4000 feet throughout the week. This would mean that
each system will likely produce snow at most of our area passes.
This is particularly concerning when considering the upcoming busy
holiday travel. Those planning on traversing the area next week
would do well to stay up to date with the latest forecasts and make
the necessary plans to account for the likelihood of wintry weather.
-BPN
&&
.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Wind Advisory until 10 AM PST Sunday for ORZ026-030-031.
Wind Advisory until 1 PM PST Saturday for ORZ029.
CA...Wind Advisory until 10 AM PST Sunday for CAZ081-085.
Winter Storm Warning until 10 AM PST Saturday ABOVE 3500 FEET
for for CAZ080>083.
High Wind Warning until noon PST Saturday for CAZ081.
Pacific Coastal Waters...Small Craft Advisory until 4 AM PST Sunday
for PZZ356. Gale Warning until 4 AM PST Sunday for PZZ350-356-
370-376.
$$
NSK/BPN/TRW
Area Forecast Discussion
National Weather Service Lincoln IL
511 AM CST Sat Nov 19 2016
.SHORT TERM...(Today and tonight)
ISSUED AT 315 AM CST Sat Nov 19 2016
The pressure gradient between a 996mb low over Lake Superior and a
1037mb high across western Kansas will remain sufficiently tight to
produce wind gusts of 35 to 40mph through the morning. Even though
sustained winds and gusts will likely remain just shy of advisory
criteria, decided to extend the Wind Advisory through noon
along/north of a Rushville to Bloomington line. As the low slowly
shifts further northeastward and the gradient begins to relax, wind
gusts will drop to less than 30mph this afternoon. Skies will
initially be overcast early this morning: however, low clouds will
steadily advect/dissipate from west to east across the region as the
day progresses. Latest HRRR suggests skies will become mostly sunny
across all but the far E/NE KILX CWA from Bloomington to Paris by
midday...then everywhere by late afternoon. Thanks to strong CAA,
high temperatures will be considerably colder than yesterday...with
readings ranging from the upper 30s north of I-74 to the middle 40s
far southwest around Jacksonville. Winds will continue to decrease
tonight, although with the Plains high remaining west of the
Mississippi River through 12z Sun, think 8-12mph winds will continue
throughout the night. This will help keep the atmosphere mixed and
limit maximum radiational cooling, resulting in lows remaining in
the lower to middle 20s.
.LONG TERM...(Sunday through Friday)
ISSUED AT 315 AM CST Sat Nov 19 2016
Cool/dry weather will prevail through Monday, before the next storm
system approaches Illinois by mid-week. 00z Nov 19 models have
continued the recent trend of slowing the system and tracking it
slightly further north...with both the GFS and ECMWF now developing
a surface low in the lee of the Rockies across eastern Colorado
Monday night, then tracking it E/NE into northeast Iowa by 12z Wed.
This particular track will put central Illinois in the warm sector
of the storm, with profiles supporting all rain. Given slower
arrival, have removed PoPs entirely for Tuesday morning with rain
developing across the area mainly Tuesday afternoon and evening. GFS
MUCAPE values remain negligible at this point, but given track of
surface low to the W/NW, isolated thunder may be possible. Once the
low lifts into the Great Lakes, wrap-around moisture will bring a
continued chance for rain showers into Wednesday before conditions
dry out for the end of the forecast period.
&&
.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
Issued at 502 AM CST Sat Nov 19 2016
Gusty west to northwest winds are expected to slowly diminish this
afternoon as the storm system that affected the area yesterday
continues to shift well off to our north and east. Low VFR cigs
have dominated the area during the early morning hours with the
latest satellite data and surface observations indicating a
narrow band of MVFR cigs pushing in from the northwest over the
past several hours. Forecast soundings have trended slower with
the clearing across the TAF sites, especially across the east
for this afternoon. Low VFR with occasional cigs dropping to
MVFR category, around 2500 feet this morning, will slowly scatter
out this afternoon with a mostly clear sky expected tonight as
high pressure moves in from the west.
Surface winds will be out of the west to northwest and range from
25 to 30 kts, with an occasional gust up to 40 kts this morning,
before northwest winds begin to diminish this afternoon to between
15 and 25 kts. Tonight northwest winds will range from 10 to 15
kts.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
Wind Advisory until noon CST today for ILZ027>031-036>038-041.
&&
$$
SHORT TERM...Barnes
LONG TERM...Barnes
AVIATION...Smith
Area Forecast Discussion
National Weather Service Melbourne FL
927 AM EST Sat Nov 19 2016
.UPDATE...
Today...High pressure ridge that has been slow moving along the
eastern seaboard was shifting south ahead of an approaching cold
front. The axis of the ridge across central Florida will provide a
northwest-north wind flow. This will maintain the capped, dry and
stable air mass we currently have over the area. The area of
stratocumulus across southern sections has been diminishing so it
will be a mostly sunny day. With primarily an offshore wind flow and
plenty of sunshine, max temps will reach to around 80 across the
area.
Tonight...The latest guidance is showing a dry cold front reaching
northern sections a little after sunset and then shift into south
Florida before sunrise Sunday. The HRRR simulated IR satellite
image showed very little frontal band cloudiness remaining as it
traverses the local area. MOS guidance is showing cooling into the
mid/upper 40s working down the peninsula behind the front though
there is some disagreement amongst the models of how far south this
occurs. Some places should have there coolest temps of the season.
&&
.AVIATION...VFR.
&&
.MARINE...
Today...A high pressure ridge axis has settled across the waters,
which should keep the flow out of the northwest from about Canaveral
northward. South of there the winds will be out of the north.
Speeds look 10 knots or less except maybe 10-15 knots offshore. This
will result in good conditions for small craft near shore with seas
1-3 feet, but it will be a little more bumpy offshore at 3-4 feet.
Tonight...A cold front will surge through the waters during the late
evening in the north and a little after midnight in the south. A
period of winds around 25 knots is likely right behind the front.
Seas will build quickly to 5-7 feet and up to 9 feet in the Gulf
Stream. No changes to the current forecast.
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...Small Craft Advisory from 9 PM this evening to 7 AM EST Monday
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 11 PM this evening to 7 AM EST Monday
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 1 AM Sunday to 7 AM EST Monday for
Sebastian Inlet to Jupiter Inlet 0-20 nm-Sebastian Inlet to
Jupiter Inlet 20-60 nm.
&&
$$
Forecasts...Lascody
Impact Wx...Spratt
Area Forecast Discussion
National Weather Service San Francisco Bay Area
406 AM PST Sat Nov 19 2016
...Widespread Rain and Breezy Conditions Today...
.SYNOPSIS...Widespread rain is forecast to spread from north to
south across the district through the day. Periods of rain will
then continue from tonight through Sunday Evening. Dry weather
will likely return by Monday, but rain is possible once again by
the middle of next week.
&&
.DISCUSSION...As of 3:20 AM PST Saturday...As forecast, rain is
currently moving across the North Bay at this hour with amounts
since last evening ranging from just a few tips to all of the way
over an inch near Venado. KMUX radar has nicely picked up the
rain as it approached and eventually moved into our CWA with a
few echoes exceeding 45 DBZ. The HRRR (both operational and
experimental) initialized well starting yesterday afternoon and
both locked on solutions that area varying only small amounts run-
to-run. Therefore, confidence is higher than normal during a storm
with timing and the overall forecast in the short term. The band
of rain will work its way south to around SF starting around 4 AM,
to Santa Cruz 8-9 AM and then finally to the remainder of the
Monterey Bay region up to Santa Clara Valley early in the
afternoon. The rain will works its way down to the southern
portion of our CWA during the afternoon or early evening hours.
At the same time, a strong surface cold front (clearly indicated
on satellite this morning) will move into our CWA and eventually
sweep across our entire region. Associated with this feature will
be cooler, more unstable air, plus higher wind speeds (925 MB
speeds likely to exceed 50 KT) associated with it. As the front
nears, winds will ramp up at many spots with southerly winds
expected to gust over 35 mph in many locations. A few higher
elevation and coastal spots will likely see gusts to around 50
mph. The wind advisory will be continued and unchanged with the
morning package.
As cooler and more unstable air moves in behind the front, showers
will be triggered across our region along with a slight chance for
thunderstorms. MUCAPE value are forecast to possibly exceed 700
J/KG with zero CIN on Sunday suggesting that small hail will be a
concern as well. Also appears that the rain will be focused more
to the south for Sunday. If any moderate convective cells happen
to go over the Sobranes burn scar, it will be a cause for concern.
Rain will mostly come to an end the second half of Monday with
rainfall totals still expected to be 1-3" for higher elevation
locations and generally .5" to 1.5" for urban spots. Depending on
how fast clearing occurs Monday night, temperatures Tuesday
morning could be on the chilly side.
Three additional systems are lined up beyond Monday (favoring
Wednesday, late Thursday into Friday, and late Saturday into
Sunday). All three appear fairly weak, although the three together
could provide a nice boost in our rainfall totals. Thanksgiving
right now appears it will start dry with highs mostly in the 60s.
Longer range guidance through December 2nd favors wetter than
normal conditions. ECMWF ensemble mean indicates around 2/3" in
San Francisco for that period.
&&
.AVIATION...As of 03:52 AM PST Saturday...For 12z TAFs. Currently
seeing some showers across the North Bay along with increasing
southerly winds. Will begin to see cigs lower over the next few
hours as rain moves further south. Expect showers and gusty winds
to continue throughout the day.
Vicinity of KSFO...VFR cigs will gradually lower to MVFR early
this morning as the front approaches. Rain will begin early this
morning and continue through much of today. Visibility and cigs
will likely decrease briefly during periods of heavier rain.
Southerly winds will gradually increase with gusts up to 25 KT
possible. Confidence moderate.
SFO Bridge Approach...Similar to KSFO.
Monterey Bay Terminals...VFR cigs will gradually lower to MVFR
by late this morning as the front approaches. Rain will begin
early this afternoon continuing throughout the day with brief
reduced visibility and lower cigs with heavier rain. Southerly
winds will increase this morning and continue to be gusty through
this afternoon. Confidence moderate.
&&
.MARINE...as of 03:51 AM PST Saturday...Strong southerly winds
will impact the waters today as a storm system approaches. gale
force gusts and periods of moderate to heavy rain are expected as
the front moves through. gusts will range from 35 to 45 kt with
localized bursts to 50kt possible. winds will become northerly
behind the front by sunday night with a building nw swell.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
.Tday...Wind Advisory...Most of the San Francisco and Monterey
Bay Region
GLW...Pt Reyes to Pigeon Pt 0-10 nm until 3 PM
GLW...Pigeon Pt to Pt Pinos 0-10 nm until 3 PM
GLW...Pt Pinos to Pt Piedras Blancas 0-10 nm until 3 PM
GLW...Pigeon Pt to Pt Piedras Blancas 10-60 nm until 3 PM
SCA...Pt Arena to Pigeon Pt 10-60 nm
SCA...Pt Arena to Pt Reyes 0-10 nm until 12 PM
SCA...Rough Bar Advisory for SF Bar until 3 PM
SCA...Mry Bay from 12 PM
SCA...SF Bay until 3 PM
&&
$$
PUBLIC FORECAST: Bell
AVIATION: Anna
MARINE: Anna
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Area Forecast Discussion
National Weather Service Bismarck ND
223 PM CST Sat Nov 19 2016
.SHORT TERM...(This evening through Sunday)
Issued at 223 PM CST Sat Nov 19 2016
The main concern in the short term period will be stratus and fog
potential tonight into Sunday. Surface high pressure was in
control of the region`s weather this afternoon. The high will
gradually shift east tonight with low level south to southeast
flow taking hold. The latest short term models suggest some
potential for stratus and fog development tonight into Sunday,
especially across parts of western North Dakota. The HRRR has been
fairly consistent with this from run to run, and have opted to add
patchy fog for tonight. The HRRR suggests visibilities could drop
to well below 1 mile, so this will be something for later shifts
to monitor.
The low clouds and fog should diminish on Sunday, though NAM BUFR
soundings suggest the clouds could be slow to erode, especially
from central North Dakota towards the James River Valley. The
clouds could also have some impact on temperatures if they are
slow to leave. For now, have gone with highs from the lower 30s
east, to the 40s west.
Another potential concern for tonight is a weak upper wave moving
across southern Canada. Some of the short term models hint at the
potential for light precipitation, but for now did not add into
the forecast with not enough consensus amongst the models.
.LONG TERM...(Sunday night through Saturday)
Issued at 223 PM CST Sat Nov 19 2016
The primary concern in the long term period will be the passage
of an upper trough early next week. The 12z global suite continues
to advertise this system, but there remains some disagreement in
the details. Will center the best precipitation chances from
Monday night into Tuesday which seems to line up with most
guidance. Precipitation type remains a potential concern with
thermal profiles suggesting warm enough air aloft for a potential
wintry mix to start. There are also some signs wet-bulb effects
could also play a role as the precipitation begins. Snow ratios
remain low through the event which could help limit snow amounts.
&&
.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 223 PM CST Sat Nov 19 2016
VFR conditions are forecast for this afternoon. MVFR-IFR stratus
and fog is being advertised by most forecast models developing
into southwest North Dakota this evening first impacting KDIK,
then spreading north to KISN by 06Z, then shifting east impacting
KBIS between 10-13Z Sunday morning. KMOT more uncertain, with KJMS
remaining VFR through the 18Z period. Low clouds expected to burn
off for KDIK mid morning around 15-16Z, but perhaps lingering
through 18Z for KISN and perhaps more so for KBIS.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...CK
LONG TERM...CK
AVIATION...NH
Area Forecast Discussion
National Weather Service Denver/Boulder CO
229 PM MST Sat Nov 19 2016
.SHORT TERM...(This evening through Sunday)
Issued at 219 PM MST Sat Nov 19 2016
Main issue to contend with tonight into Sunday will be a
developing mountain wave in the Front Range Mountains and
Foothills. The upper level ridge axis will be over central CO at
00z with a moderate westerly flow aloft. The mdls shift this axis
east overnight with a moderate west-southwesterly flow over CO.
The RAP and NAM12 mdls both indicate an amplified wave developing
after 03z, strongest at 12z Sunday, it then breaks down by 18z.
Lee side surface trough over eastern CO 06z to 12z then the
feature shifts further south by 18z, shifting the surface
pressure gradient In the mountains, winds around 650 mb at 40
kts, which appear to translate downslope in the foothills
overnight. It does not appear to be strong enough for highlights
but gusts in the 45-60 mph range more likely. Temperatures in and
near the foothills will also moderate with the gusty winds in
place overnight. On Sunday, better temperature recovery progged
for the Urban Corridor and Northeast Plains, but a lingering
snowfield should keep it a little cooler north and east of Akron.
In the mountains and foothills, stronger winds in the mountains
and foothills will decrease as the wave break down by Sunday
afternoon.
.LONG TERM...(Sunday night through Saturday)
Issued at 219 PM MST Sat Nov 19 2016
A southwest flow aloft will prevail over Colorado Sunday night as
an upper level trough moves across California. This trough will
move into the Desert southwest Monday. Moisture will increase
through the day. This combined with orographic lift and a jet
overhead, is expected to produce snow showers in the mountains.
Snow should become widespread over the mountains Monday night as
the trough moves across the Central Rockies. Precipitation will
then spread onto the Front Range and eastern plains through the
night. Temperatures look to be just warm enough for mainly rain
along the Front Range Urban Corridor. The upper level low/trough
and a surface low reform over western Kansas late Monday night.
Northerly winds on the back side of this system will help pull
cooler air into the area. This will likely cause the rain to
change to snow over the plains, especially where precipitation is
moderate to heavy.
Northwest flow behind the exiting trough will usher in colder
air. This cold air advection combined with a moist airmass is
expected to produce snow showers over the mountains most of
Tuesday. By Tuesday evening snow will be light and eventually end.
Rain/snow over the plains is expected to end Tuesday afternoon as
the trough exits the region.
A ridge in the westerly flow aloft will move across Colorado
Wednesday. Dry conditions will return to the area. Temperatures
will be cool with highs in the 40s. On the heels of this ridge, a
trough will race across Wyoming and northern Colorado Wednesday
night and early Thursday. Will have low pops in the mountains for
this system. For the Front Range and eastern plains, this will
likely bring dry and windy conditions.
A progressive westerly flow aloft will remain over the Central
Rockies Friday and Saturday. Temperatures will be near normal
under this pattern. The next wave is progged to affect the
mountains Friday night and early Saturday. Will have low pops in
the mountains for this system.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 219 PM MST Sat Nov 19 2016
VFR with light and variable winds this evening. weak easterly
winds this aftn then southerly winds developing this evening at
KDEN and KAPA. Downslope winds are expected near the foothills
after 03z, so could see a window of gusty westerly winds at KBJC
depending on how well the mountain wave forms.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...Cooper
LONG TERM...Meier
AVIATION...Cooper
Area Forecast Discussion
National Weather Service State College PA
258 PM EST Sat Nov 19 2016
.SYNOPSIS...
Strengthening low pressure will track north of Pennsylvania this
afternoon. A cold front trailing south from this low will plow
east across Central and Eastern Pennsylvania during the mid to
late afternoon hours. Temperatures will drop sharply by 20 to 25
degrees within just 2 to 3 hours of the frontal passage, and west
to northwest winds will gust between 35 and 45 mph through
tonight. The deep, cold upper low will pivot over the region
Sunday with unseasonably cold air, snow showers, and occasional
wind gusts around 50 mph lasting into Monday. this weather feature
will slowly lift out to the northeast of the region early next
week. Low pressure will likely track north of Pennsylvania late
next week.
&&
.NEAR TERM /UNTIL 8 PM THIS EVENING/...
130 pm update...
Cold front shows up nicely on regional 88D mosaic as a fine line
in the reflectivity field (likely attributed to dust stirred
up/concentrated right along the boundary). The front was nearing a
line from KELM to KIPT and KHGR at 1830Z.
Frequent wind gusts from the West of 35 to 45 mph will be
common through dusk...but will likely stay just under Wind
Advisory Criteria, then slacken by 5-10 kts early tonight as the
primary area of significant sfc pressure rises slides east of the
region, with about 30-40 deg of directional shear between the sfc
and 850 mb.
Area of precip lags the actual sfc cfropa by about 40NM and will
occur initially in the form of a chilly rain, before quickly
mixing with or changing to a few hour period of snow with a
coating to 2 inches likely by 00Z Sunday across the higher
terrain of northern and western PA. The precip shield is forecast
by the latest...17Z HRRR to hold together fairly well as it slides
across the Central Mtns late this afternoon...and early this
evening across the Middle and Lower Susq Valley.
Slick travel and a quick freeze-up is likely late today and this
evening west of the I-99/Route 220 corridor.
Temps that reached the 50s in most areas late this morning...and 60s
to Lower 70s in the Susq Valley will likely not be seen
accompanying nearly full sunshine until later this winter or early
in the Spring. Temp drop in the wake of the cold front was on the
order of about 25 deg F in just 2-3 hours.
If you plan to travel west on I-80 from Berwick to Dubois this
afternoon, hold onto the wheel (considering the 35 to 45 mph
headwind) and plan to take a winter coat as you`ll experience a 35
to 40 deg temp drop by the end of your 2-2.5 hour trip.
&&
.SHORT TERM /8 PM THIS EVENING THROUGH 6 PM SUNDAY/...
Considering the nose of very deep cold air with -7 to -9C 850
temps spreading across the region (and still warm Lower Glakes
with temps of 10-13C), there will be very steep low-mid level
lapse rates and an excellent setup for an early season significant
Lake Effect and orographic moderate to heavy snow event across
the NW Mtns and Laurels. NCAR ensemble indicating a general 3-6
inch snowfall across the Allegheny Plateau by 00Z Monday.
However, believe higher amounts are likely across the snowbelt of
NW Warren county. Downsloping flow and warmer blyr temps should
limit any accumulations to a coating in the ridge/valley region
and no accumulation expected across the Susq Valley.
Very tight llvl pressure gradient will result in strong, gusty
west to northwest winds, causing considerable blowing/drifting
snow in open/exposed locations of the NW Mtns and Laurel
Highlands. Bufkit soundings suggest the best mixing and strongest
wgusts will occur across the southeast part of the state during
the daylight hours of Sunday, with gusts in excess of 40kts
likely. Have therefore issued a wind advisory for this region 12Z
Sunday through 05Z Monday.
&&
.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
Accumulating lake effect snow will persist Sunday night across the
Allegheny Plateau. However, the intensity is likely to diminish
as inversion heights begin to lower. Northwest flow will persist
into Monday with lingering snow showers downstream of Lake Erie, but
dry and cold in the S/E. The Strong NW flow ushering in cold air
will continue on the backside of the storm system that came
through Saturday as long as the storm`s low pressure center is
deepening. Low is finally forecast to start filling late Monday up
over Maine.
A strong ridge of high pressure moves in across PA Tuesday into early
Wednesday bringing fair weather and warming temperatures. A warm front
will move through Wednesday afternoon as the next storm system moves
into the Great Lake Region.
GFS and ECMWF differ on how fast the precip and cold or occluded front
associated with this storm moves into PA with the GFS beingthe
fast one bringing it in early Wednesday night and the euro
moretoward Thursday morning. Temperatures have warmed enough that
anyprecipitation Wednesdaynight and Thursday will be rain.
Both models hen develop a secondary low on the VA Coast
whichdeepens as it moves off to the northeast. This will help to
bringsome colder air in by Thursday night to northern PA with just
aslight chance of mix rain and snow showers there. A clipper
systemmoves quickly through Friday night and Saturday with a
better chanceacross the north for mix rain and snow showers with
snow chances inthe higher elevations. Cold air sweeps in behind
this and some lakeenhancement could change over to snow showers by
Saturday afternoon.
&&
.AVIATION /20Z SATURDAY THROUGH THURSDAY/...
Big changes are on the way!
The last vestiges of sunny skies and light wind are seen east of
the Susq mainstem at mid afternoon.
West winds will sharply increase over the eastern PA airfields as
a strong cold front pushes across the region between
19-22Z...while winds continue to frequently gust between 32-37 kts
across the central and western part of the state through 00Z.
This front will bring a big change in weather regime. Initially,
gusty rain showers (as winds increase and turn to the west) reach
the central terminals 18-20z, and the Susq River Valley 20-23Z.
Colder air surging in behind the front will bring a brief period
of light to moderate rain, then a quick change to mixed rain and
snow (or even all snow for an hour or so across the nrn mtns of
PA).
Cig and vsby reductions into the low MVFR or IFR range are
expected for a few hours in the Central ridge and valley region
and Susq Valley late this afternoon and evening...before climbing
back to mainly MVFR or VFR SE of a KAOO to KIPT and KAVP line.
Over the NW mtns and Laurel Highlands...expect more solid IFR
conditions in frequent snow showers/upslope stratus with brief
increases to MVFR between the snow showers.
Starting later tonight, a period of even stronger and gusty WNW
winds will develop - peaking Sun into Sun night with frequent
surface gusts of 40-50mph. A period of more intense/widespread
lake effect snow showers with IFR cigs/vsby likely at KBFD/KJST by
mid evening and continuing right into Mon. Generally lighter snow
showers will spread into central mtns (KUNV/KAOO) Sun night into
Mon.
Outlook...
Tonight-Mon...Strong/gusty NW winds. Gusts frequently between
35-45 mph later tonight through Sunday night. Snow
showers/IFR reductions likely at KBFD/KJST. Ocnl MVFR cigs with
flurries and brief snow showers across the Central Mtn airfields -
KAOO, KUNV and KIPT with mainly VFR invof KMDT, KLNS and KTHV.
Tues...Morning MVFR cigs possible across the northern and western
mtns of PA...otherwise decreasing wind and improving conditions to
mainly VFR.
Wed...No significant weather expected.
Wed night and Thursday...MVFR to IFR conditions as periods of rain
spread east across the state. Mixed precipitation possible across
the northern and western mountains of PA.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
Wind Advisory from 7 AM Sunday to midnight EST Sunday night
for PAZ019-025>028-034>036-041-042-045-046-049>053-056>059-
063>066.
Winter Weather Advisory until 7 AM EST Monday for PAZ012-017-
018-024-033.
Lake Effect Snow Advisory until 7 AM EST Monday for PAZ005-006-
010-011.
Lake Effect Snow Warning until 7 AM EST Monday for PAZ004.
&&
$$
SYNOPSIS...Fitzgerald/Lambert
NEAR TERM...Lambert
SHORT TERM...Fitzgerald/Lambert
LONG TERM...Watson
AVIATION...Lambert/RXR
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
240 PM CST Sat Nov 19 2016
.SHORT TERM...
152 PM CST
Through Sunday night...
Winter is making a brief though abrupt appearance here across the
region in wake of the first real storm system of the season. While
winter precipitation impacts were low with this one, today is our
first day of below normal highs in quite some time with readings
holding in the 30s and wind chills in the 20s.
The strong low will continue northeast through Quebec tonight and
the high pressure ridge across the plains will also edge closer to
the area tonight. This will maintain northwest winds across the
area though with a gradual decaying trend. Rap lower level
moisture progs suggest a quick clearing to the cloud deck later
this afternoon and evening. This should set up a colder night area
wide, with upper teens to lower 20s common and near single digit
wind chill readings. Evening wind chills fall into the teens to
low 20s.
The surface high will move overhead tomorrow afternoon, providing
for plentiful sunshine in spite of some passing higher clouds,
along with much lighter winds. While highs will be similar to
today, the light winds and sunshine will make it feel quite a bit
better. One more cold night is in store for Sunday night as high
pressure remains in place.
KMD
&&
.LONG TERM...
152 PM CST
Monday through Friday...
The coming holiday week will start off with dry and seasonal
conditions (mid to upper 40s) as an upper level ridge moves
overhead. Light winds will become easterly as low pressure
organizes in the southern Rockies in response to a southern stream
trough axis.
Tuesday/Wednesday appears to be the most active portion of the
extended period. The broad upper trough will eject out of the
Rockies on Tuesday and then slowly progress east through the
midwest on Wednesday. Several guidance sources bring a weak wave
through ahead of the trough late Monday night into Tuesday but
keep it dry. If any wet bulbing were to occur or forcing stronger
there could be some light mixed precipitation initially, and the
GFS is a bit more aggressive with the low level warm advection
ahead of this system, depicting surface wet bulb temps just below
freezing and actual surface temps close to freezing. At this
point will stick closer to the full suite of models given the
antecedent dry conditions and precipitation likely being lost to
evaporation, plus this suite still largely maintains a drier
solution for Tuesday morning. Feel confident in breezy southeast
winds developing Tuesday as this trough organizes a surface low in
the central/southern plains.
Better combined forcing and moisture arrives later Tuesday into
Wednesday which looks to be a wet period as the surface and upper
lows move overhead and get seasonally elevated precipitable water
values advected in on a modest low level jet, so expect wet roads
for the busy travel day.
The low will pull away Wednesday night, with some wrap around
precipitation expected to largely remain liquid. This will also
make way for dry conditions and once again seasonal temperatures
for the Thanksgiving Holiday. A progressive upper level pattern
remains in place for Thursday night/Friday as a shortwave moves
through, but some significant differences in extended guidance
regarding the track of the corresponding low and surface
temperatures during the period of interest. Fortunately precip
looks on the lighter side.
KMD
&&
.AVIATION...
For the 18Z TAFs...
We find ourselves sandwiched between departing low pressure across
southeastern Quebec and strong high pressure across the plains.
Pressure rises behind the low coupled with strong cold advection
is resulting in decent mixing, though somewhat regulated by the
cloud deck in place. Gusts have generally settled into the upper
20s to lower 30s with some higher gusts mixed in, with earlier
gusts to 40 kt. Have held onto the lower 30 kt gusts which are
the most common and these should likely hold for a good portion of
the afternoon. Gustiness will continue this evening, though some
decrease is anticipated late this afternoon, then more so
overnight. Winds will be shifting to more northwesterly through
the period. The low VFR deck will also erode from west to east,
lingering a bit longer across the eastern half of Lake Michigan
and into parts of NW Indiana.
KMD
&&
.MARINE...
240 PM CST
Low pressure continues to pull off to the northeast this afternoon
as high pressure builds across the plains and midwest. A strong
pressure gradient still exists between these two features with
solid gales across the south half of Lake Michigan and 10-13 ft
waves. Several observations across the northern tier of the lake
are also near storm force (along the shore, so likely higher
across the open waters), and this supports no immmediate change to
current headlines across Lake Michigan quite yet. Once storm force
winds ease across the north, it is likely gales will continue for
at least another 6 hours if not a bit longer, with gales finally
easing Sunday morning. Winds do weaken more Sunday afternoon but
waves will take a bit longer to subside. High pressure will
translate over the lake Sunday night and Monday.
Another weaker low will take aim at the southern tip of Lake
Michigan Wednesday, with breezy southeast winds ahead of the low
expected Tuesday and Tuesday night. Winds look to remain below
gale levels, but this will build waves across the west side of
the lake.
KMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...Wind Advisory...ILZ005-ILZ006-ILZ012-ILZ013-ILZ014-ILZ020-ILZ021-
ILZ022-ILZ023-ILZ032-ILZ033-ILZ039 UNTIL 3 PM Saturday.
IN...Wind Advisory...INZ001-INZ002-INZ010-INZ011-INZ019 UNTIL 3 PM
Saturday.
LM...Gale Warning...NEARSHORE WATERS UNTIL
MIDNIGHT Sunday.
Gale Warning...LMZ777-LMZ779 UNTIL 9 AM Sunday.
&&
$$
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Area Forecast Discussion
National Weather Service Marquette MI
425 PM EST Sat Nov 19 2016
.SHORT TERM...(This evening through Sunday)
Issued at 425 PM EST SAT NOV 19 2016
Water vapor imagery and RAP analysis show a sharp mid/upper level
trof over the Great Lakes. Lingering deep layer forcing associated
with the trof is still over eastern Lake Superior. Combined with
850mb temps around -12C, lake enhanced snow is ongoing into the e
half of the fcst area. To the w, subsidence and much drier air noted
on the 12z CYPL sounding and in particular the 12z KINL sounding
along with inversion down around 850mb have strongly limited LES
today off western Lake Superior. Combined with the strong winds,
there has not really been much in the way of shsn activity until
well inland from the lake where orographic lift becomes sufficient.
With inversion steady around 4kft over the w tonight, not expecting
anything more than sct -shsn into the western fcst area. Coverage
may increase a bit during the night as nocturnal cooling around the
lake and increasing land breeze component to wind increase low-level
convergence. However, any additional snow accumulations should only
be an inch or less. To the e, lingering deep layer forcing pulls out
this evening and is replaced by strong deep layer qvector
divergence/subsidence with inversion falling to around 5kft. So, the
current widespread lake enhanced snow over the e will evolve into a
more typical multi-band les scenario by late evening. After this
occurs, the main point of interest will be banding connected to Lake
Nipigon preconditioning. Should see a dominant band set up into
western Alger County tonight. High res model output is all fairly
well clustered on this scenario with all also showing this band
drifting w into Marquette county during the night into Sun morning
though with different timing. Depending on how quickly the band
shifts and how organized it becomes, it could produce a few inches
of snow accumulation in a short period of time. Will be something to
monitor. As for headlines, all headlines w of Marquette/Delta
counties have been dropped. Maintained ongoing headlines elsewhere
with the exception of dropping Marquette to winter wx advy.
Nighttime snow accumulations should be on the order of 1 to 4 inches
in the headline areas, with perhaps as much as 5 inches in far
western Alger County associated with aforementioned band that
develops from Lake Nipigon preconditioning. Winds will continue to
diminish.
Light les will continue on Sun, but will slowly diminish from w to e
during the day. There may be some locally mdt/hvy snow in eastern
Marquette county in the morning as discussed above.
.LONG TERM...(Sunday night through Saturday)
Issued at 316 PM EST SAT NOV 19 2016
Only significant weather in the long term is mid-week with potential
for advisory (or possibly low end warning) level snow.
An upper trough is modeled to move through the area mid-week,
bringing a 1007mb SFC low from southern WI through central lower MI
Wed and Wed night. Widespread precip may move into the W or SW by
late Wednesday, and the bulk move out by Wed night. Models are in
good agreement overall, but the GFS has the most QPF at up to 0.75"
while the ECMWF only has up to around a half inch. Most of the
precip falls as snow, with the exception possibly of the south-
central where a transition to rain is more likely. If the events
plays out as currently modeled, winter weather advisories would be
needed over a good portion of the area, with potential for some
warning amounts if the GFS amounts verify. For now, given the
inherent uncertainty at that time frame with this type of system,
will just mention of the HWO. Definitely will have to keep a close
eye on the system given the high-impact travel day.
Lighter snow is possible Thursday and Friday, but certainly not
looking at any significant amounts right now.
&&
.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1231 PM EST SAT NOV 19 2016
In the wake of the strong storm system that has moved across the
Upper Great Lakes, cold air mass will generate lake effect shsn thru
this fcst period with MVFR conditions generally prevailing at
KIWD/KCMX/KSAW. Some periods of IFR are possible, especially at KSAW
thru mid aftn. Influx of drier air will result in diminishing shsn
with time so that periods without shsn become more frequent and
longer duration. Meanwhile, the strong/gusty winds will gradually
diminish from w to e. During the aftn, expect winds to gust to 30-
40kt, strongest at KCMX/KSAW.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 425 PM EST SAT NOV 19 2016
As pres gradient weakens as low pres moves farther away and high
pres ridge approaches, ongoing gales over central and eastern Lake
Superior will end tonight. While the high pres ridge and light winds
will reach western Lake Superior Sun aftn, the ridge won`t reach
eastern Lake Superior until Mon night. As a result, winds on eastern
Lake Superior will remain in the 20-30kt range during Sun and won`t
fall blo 20kt until later Sun night/Mon. Winds will increase across
the lake later Tue into Wed as the next low pres system moves into
the Great Lakes region. The strongest winds, 20-30kt, will occur
over central and eastern Lake Superior on Wed.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
Winter Weather Advisory until 1 AM EST Sunday for MIZ005-013-014-
085.
Coastal Flood Warning until 1 AM EST Sunday for MIZ006-007.
Winter Storm Warning until 1 AM EST Sunday for MIZ006-007.
Coastal Flood Warning until 7 PM EST this evening for MIZ005.
Lake Superior...
Gale Warning until 4 AM EST Sunday for LSZ248>251-265>267.
Gale Warning until 1 AM EST Sunday for LSZ243>245-264.
Gale Warning until 7 PM EST /6 PM CST/ this evening for
LSZ240>242-246-247-263.
Lake Michigan...
Gale Warning until 4 AM EST Sunday for LMZ221-248-250.
&&
$$
SHORT TERM...Rolfson
LONG TERM...Titus
AVIATION...Rolfson
MARINE...Rolfson
Area Forecast Discussion
National Weather Service Portland Oregon
256 PM PST Sat Nov 19 2016
.SYNOPSIS...Broad low pressure will linger off the Pac NW coast into
Sunday, producing showers and isolated thunderstorms...especially
near the coast. The low will weaken and lift north into BC Sunday and
Monday, with showers decreasing Mon/Mon night as transitory high
pressure moves across the region. The next front moves in on Tuesday,
bringing another round of rain and some coastal wind, followed by
more showers Wednesday. Another Pacific frontal system is expected
Thanksgiving Day. Snow levels will remain near the Cascade passes
through Monday, then each frontal system will bring progressively
colder air and lower snow levels through the end of the week.
&&
.SHORT TERM...Tonight through Tuesday...WPC-analyzed 982 mb low
pressure centered near 45N/130W is beginning to drift northward per
latest satellite imagery, while pushing a secondary cold front into
the Pac NW coastal waters this afternoon. Instability appears to be
best over the coastal waters due to the relatively mild sea surface
temperatures, driving a line of showers and thunderstorms along the
cold front. With tops up to 22-24 kft, some of the cells are tall
enough to produce a few lightning strikes, and this should continue
to be the case as the front approaches shore. KLGX VAD wind profile
seems to indicate winds are fairly unidirectional with height aside
from some decent E-SE flow in the lowest 1-2 kft...which seems
consistent with the idea that the best shear may have passed with the
shortwave and occluded front that moved through this morning. While a
stray spinup of a waterspout is possible with the cold front this
afternoon and evening, the environment does not look quite as
favorable as it did this morning despite the decent line of showers/
t-storms moving toward the coast.
Convective-allowing models seem to hold the majority of showers and
thunderstorms over water this evening...which makes sense considering
the loss of daytime heating and the resulting stabilization over
land. Some debris from convection firing off the S OR/N CA coast may
hold together enough to bring some decent showers N-NE into our CWA
overnight just ahead of the front...though it appears the latest HRRR
and WRF and may be a little overdone in holding convection together
over inland areas tonight. Decided to keep thunder mention restricted
to the coast and waters, with a chance of showers east of the Coast
Range overnight.
Weakening front and upper level trough axis will drift through
western WA/OR Sunday, keeping us unstable enough for plenty of
showers. 1000-500 mb thicknesses and 850 mb temps remain marginal for
snow at the Cascade passes...suspect there may be a wet coating from
time to time during the night and morning hours, then melting during
the day. It is interesting to note that there was a dusting of snow
as low as 2000-2500` around Trout Lake and Parkdale this morning,
with temps lingering in the mid to upper 30s through the day.
Easterly gradients ahead of the cold front will continue to lock this
cool air in place until - ironically - the cold front moves through
Sunday to mix out the cool air. Fairly typical pattern for that part
of our forecast area in the wintertime. Impacts should be negligible
this time around, but this type of pattern may come into play again
as the week progresses.
Showers will decrease Mon/Mon night as the upper trough weakens and
transitory high pressure moves across the Pac NW. Skies may clear
enough for a chilly night with lows dropping toward the upper 30s in
cooler portions of the Willamette Valley. It will likely be cooler in
the Hood River Valley and near Trout Lake, which may result in some
precipitation-type issues in those cooler valleys if precipitation
arrives early enough with the next front Tuesday. However, 12z
ECMWF/GFS suggest precip will arrive late enough in the day to allow
temps to rise above freezing Tuesday...likely resulting in a similar
event to today. Front will likely be splitting as it moves onshore,
capping winds around 40-50 mph near beaches and headlands. East winds
will be blustery through the Columbia Gorge and across the PDX Metro
as the front approaches the coast. Weagle
.LONG TERM...Tuesday night through Saturday...The above-mentioned
Pacific frontal system will move across the district Tue night, with
some modest precipitation and lowering snow levels. 18z GFS and 12z
ECMWF suggest 850 mb temps will drop to around -2 deg C, which would
correspond to a general snow level around 3000` through Wednesday as
the associated upper trough swings through the region for more
showers. This will be enough to set the stage for wintry driving
conditions across the Cascade passes for the upcoming holiday
weekend. Similar to Tuesday, there is also an outside chance of some
precipitation-type issues in the Columbia Gorge Thanksgiving Day due
to cold air east of the Cascades, depending on timing of the next
front Thursday. Cool and unsettled weather will likely continue
through the holiday weekend, with snow levels remaining near or below
the Cascade passes and another potent front possible next weekend.
Those with travel plans across the Cascades or Siskiyous during the
upcoming holiday weekend should stay tuned to the weather, as there
is decent potential for at least some weather impacts in the upcoming
cool and unsettled pattern. Weagle
&&
.AVIATION...Primarily VFR across the area, with the possible
exception of localized MVFR in the Cascades. Little change in
overall flight conditions through tonight, with the primary
frontal zone remaining offshore. Instability will lead to a
threat of thunderstorms over the coastal areas through Sun. The
weakening frontal zone drifts Sun, with an increasing chance of
MVFR for the coastal TAF sites. East wind 20 to 30 kt with gusts
to 40 kt will continue at the west end of the Columbia Gorge
through this evening.
KPDX AND APPROACHES...VFR expected through Sun afternoon. More
frequent shower activity Sun afternoon, but cigs to remain VFR.
East wind 20 to 30 kt with gusts to 40 kt will continue near KTTD
and the west end of the Columbia Gorge through this evening. This
may result in localized LLWS. Weishaar
&&
.MARINE...A 982 mb low pres area located near 45N and 130W early
this afternoon will continue to track N to NE through tonight.
Convective line along the frontal zone near 126W has had some
lightning strikes early this afternoon. ASCAT pass indicated 35 kt
wind along the convective line supporting the current gale
warning. 12Z NAM valid 21Z today matched reasonably well with the
ASCAT data. However, the GFS boundary layer wind speeds seemed to
be a little strong.
Gale force wind will continue over the outer waters through
tonight. Opted to end the gale 14Z Sun, a little earlier than
previous forecasts. NAM indicates 25 kt boundary layer wind speeds
12Z Sun. It will be tough to get gale force wind gusts into the
inner waters due to the surface pressure orientation...but gusts
to 35 kt a good bet near the 10 nm boundary through tonight. Wind
direction will veer south to southwest over the outer waters
tonight and more toward the south over the inner waters late
tonight.
Models show wind speeds falling below 15 kt late Sun night and
continuing through Mon evening. Looks like another potential gale
event late Mon night through Tue, followed by yet another possible
gale Thu.
Seas over the outer waters expected to peak in the 16 to 19 ft
range by this evening, with localized 20 ft not out of the
question. Seas over the inner waters will not be as high,
generally 14 to 17 feet. There will be mix of primary SW swell, a
large south fresh-swell and then a lower but longer-period west
swell from a distant source region. Seas gradually ease Sun,
falling to around 12 feet by late Sun afternoon. However, guidance
suggests seas building to the upper teens Wed night and Thu, then
possibly exceeding 20 ft next Fri. Weishaar
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
PZ...Gale Warning until 6 AM PST Sunday for Waters from Cape
Shoalwater WA to Florence OR from 10 to 60 nm.
Small Craft Advisory until 4 PM PST this afternoon for Coastal
Waters from Cape Shoalwater WA to Florence OR out 10 nm.
Gale Warning until 6 AM PST Sunday for Coastal Waters from Cape
Shoalwater WA to Florence OR out 10 nm.
Small Craft Advisory for Rough Columbia River Bar until 1 PM
PST Sunday.
&&
$$
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This discussion is for Northwest Oregon and Southwest Washington
from the Cascade crest to 60 nautical miles offshore. The area is
commonly referred to as the forecast area.
Area Forecast Discussion
National Weather Service Charleston WV
146 PM EST Sat Nov 19 2016
.SYNOPSIS...
Upslope snow lingers into Sunday night in strong, cold northwest
flow. High pressure early next week. Another front mid week.
&&
.NEAR TERM /THROUGH SUNDAY/...
As of 130 PM Saturday...
Winter making its first appearance this weekend, in the wake of a
strong cold front that whipped through the area this morning.
Large upper level short wave trough swinging through the area this
afternoon takes on a negative tilt tonight, and then closes off
over the northeast U.S. atop surface low pressure, as a stacked
system.
Strong cold advection west to northwest flow on the back side of
the system will continue to drive temperatures down. This will
transition wrap around rain showers over to snow showers from west
to east and high terrain to lower terrain by tonight, and then the
precipitation transitions into an upslope event tonight, as the
upper level trough axis pushes east of the area.
Upslope precipitation will be enhanced by plume off lake Michigan
across northern portion of forecast area, which may enhance
snowfall amounts in the northern mountains. This is already
reflected in the forecast, and overall no changes were needed to
the snow amounts. Have a borderline advisory event for snow,
along with a solid wind advisory event, for the higher terrain
portions of Randolph, Webster and Pocahontas counties. Wind gusts
may actually trough 50 kts across the very highest terrain
overnight tonight.
The upslope snow showers start to wane late Sunday, as approaching
high pressure starts to slacken the pressure gradient.
Temperatures similar to previous, fine tuned / updated via the
HRRR, RAP and NAM.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
As of 145 PM Saturday...
Still a few light upslope snow showers lingering across the northern
mountains Sunday night, but overall, will be tapering off, as flow
starts to back and become less favorable, as high pressure gradually
builds into the region. Sunday night will continue to be cold, and
windy, with wind chills in the teens to single digits across the
higher terrain, particularly across eastern zones where tighter
pressure gradient will exist as high gradually tries to nudge east.
Dry, with gradually warming conditions Monday and Tuesday, as high
pressure surface and aloft continues to take hold.
&&
.LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/...
As of 145 PM Saturday...
Clouds will be on the increase across the area on Tuesday, as a warm
frontal boundary lifts north across the region. Showers will
overspread the area again by Wednesday as low pressure, and
associated cold front approach from the west, but enough warm air
should be in place owing to strong southerly flow, that bulk of
precipitation will be in the form of rain. Another system approaches
the area next weekend. At this point, the exact track, and thus
precipitation type is very uncertain, but could be at least a light
snowfall for the higher terrain, along with the possibility for a
rain/snow mix at times across some lower elevation locations.
&&
.AVIATION /19Z SATURDAY THROUGH THURSDAY/...
As of 130 PM Saturday...
Strong west to northwest flow will continue this period, in the
wake of a cold front that blew through the area this morning.
Winds will strengthen this evening, with gusts of 30 to 35 kts
across the lowlands, and 30 to 35 kts in the mountains. These
strong winds will start to slowly diminish Sunday morning.
MVFR ceilings will be prevalent, lifting to VFR at times across
the lowlands this afternoon, and in ernest across the lowlands
late Sunday morning. VFR visibility may drop to brief MVFR in
rain showers this afternoon, and to MVFR or IFR in snow showers in
the mountains tonight, when MVFR visibility may be more persistent
at EKN amidst occasional IFR visibility in heavier snow showers.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z SUNDAY...
FORECAST CONFIDENCE: Medium
ALTERNATE SCENARIOS: Ceilings and Visibilities will be highly
variable in snow showers in the mountains. The strong gusty winds
will fluctuate.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
UTC 1HRLY 18 19 20 21 22 23 00 01 02 03 04 05
EST 1HRLY 13 14 15 16 17 18 19 20 21 22 23 00
CRW CONSISTENCY H H H H H H M H L M M L
HTS CONSISTENCY H H H H H H H H H H H M
BKW CONSISTENCY L L L L L L L L L L L L
EKN CONSISTENCY L L L L L L L L L L L L
PKB CONSISTENCY L M H H H M M M M L M L
CKB CONSISTENCY M H H H M H M L M L L L
AFTER 18Z SUNDAY...
IFR possible within upslope snow showers into Sunday night across
the mountains.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...Winter Weather Advisory until 4 AM EST Monday for WVZ522-523-
526.
OH...None.
KY...None.
VA...None.
&&
$$
SYNOPSIS...TRM/SL
NEAR TERM...TRM
SHORT TERM...SL
LONG TERM...SL
AVIATION...TRM