Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 02/03/17
Area Forecast Discussion
National Weather Service Albany NY
954 PM EST Thu Feb 2 2017
.SYNOPSIS...
A cyclonic flow will result in brisk and colder conditions to
persist tonight into the weekend, with multiple upper level
disturbances passing through the region. Periods of heavy lake
effect snow will affect mainly the western and southern Adirondacks
and western Mohawk Valley, with isolated to scattered snow showers
possible elsewhere.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
Lake Effect Snow Warning for Hamilton and northern Herkimer counties
from through 7 PM EST Saturday.
Lake Effect Snow Advisory for southern Herkimer county and
northern Fulton county through 6 AM Friday.
As of 954 PM EST...Lake snowband continues to impact western
Adirondacks eastward into the Lake George Region into Southern
VT. At one point this band extended around 175 miles inland an
and SPS was issued for the Lake George Region since it was
crossing I-87 between exits 23 and 24. The band has weakened a
bit over the past hour and become narrower. The heaviest snows
continue to fall over central Herkimer Co...south of Route 28
towards Route 8 in the Atwell corridor. Snow rates of an inch or
an hour are possible. The band still may reach far enough south
to graze southern Herkimer and northern Fulton Counties for a
few hours, so we will leave the advisory up for now...but it may
be dropped later.
The band may lift more northward overnight with the flow
backing more to the west to southwest /250-270 degrees/ before
the next impulse arrives. The latest HRRR shows a weakening of
the downstream extension overnight likely due to a lowering
inversion indicative on the upstream model soundings.
This should allow for Lake Effect snow bands initially along
the northern Mohawk Valley and southwest Adirondacks currently
drift slowly back northward into central/northern parts of
Herkimer/Hamilton counties overnight. However, the Warning
will continue for northern Herkimer/Hamilton counties into the
weekend. Expect accumulations overnight in the warning area to
reach 3-6 inches. Greatest totals should be south of Route 28
this up to around midnight, and closer to the Route 28 corridor
after midnight.
Temperatures are expected to fall into the teens to around 20
for most areas.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/...
Lake Effect Snow Warning continues for northern Herkimer and
Hamilton counties through 7 pm Saturday.
The main issue will continue to be a rather long-duration lake
effect snow event during this time, with an upper level trough and
cyclonic flow regime persisting through Saturday with a multi-lake
connection through much of the period.
On Friday, lake effect snow bands will continue to affect
northern Herkimer and Hamilton counties, mainly along the Route
28 corridor with the flow trajectory forecast to shift from
around 260 to 270 degrees during the day.
With the passage of yet another surface trough and upper level short
wave, the flow will once again shift to more of a west-northwest
direction Friday night, which will send lake effect snow bands
southward once again into the extreme southern Adirondacks and
Mohawk Valley. Additional lake effect headlines will be possible for
mainly southern Herkimer and Fulton counties during this time and
will mention the potential in the HWO. However, there is some
suggestion that low level wind shear could also disrupt the
snowbands and inland extent Friday night, hence the uncertainty.
Will continue to maintain Lake Effect Snow Warning for northern
Herkimer/Hamilton counties through Saturday. So while there will
likely be a short break in the lake effect across the western
Adirondacks Friday night, we will continue the warning as snow bands
are expected to move back into this area on Saturday as the flow
trajectory is expected to shift back to a westerly direction. Warning
times were well-coordinated with neighbors to the west (BUF/BGM) to
highlight this long-duration lake effect event. Generally 6 to 12
inches of snow is expected in much of the warning area from central
Hamilton county westward, with 12 to 18 inches in the most
persistent bands.
Outside of the main lake effect snow activity, just isolated to
widely scattered snow showers are expected. There is a chance for at
least fragments of lake effect snow bands to reach down the Mohawk
Valley and possibly into the Capital District late Friday into
Friday night, but should be brief with only minor accumulations.
Overnight lows should mainly be in the single digits and teens,
with daytime highs in the teens to lower 20s for higher
elevations, and mid/upper 20s in valley areas.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
Active period of weather as we transition from broad cyclonic flow
to zonal then progress into higher amplitude toward the later
portions of the long term period.
For the weekend, the cyclonic flow transitions toward a zonal flow
and increasing baroclinicity as pv-anomaly transverses along the
US/Canadian border. This will assist with a weak surface low
reflection that global model consensus favors a track well to the
west and north of the local region through Sunday. Due to this,
overall lift remains meager as PoPs will range from slight chance
from the Capital Region to south and east with higher chance PoPs to
the north and west of Albany.
The baroclinicity magnitudes increase further for Monday as mainly
clouds and a few snow showers or flurries (mainly downwind of Lake
Ontario) as we closely watch the approach of a strong Pacific Jet
coming ashore. This will be the system to monitor for Tuesday into
Wednesday.
While the details will be sure to evolve leading into the event, the
combination of a strengthening surface high across northern New
England and deepening trough over the center of the nation with
potentially rapidly deepening surface low, we appear to set the
stage for an overrunning event Tuesday. Thermal profiles point
toward mainly snow at the onset of the precipitation. Then as this
storm matures upstream, increasing low level jet magnitudes will
advect warmer air in the mid levels for a transition of
precipitation types from snow to sleet and a period of freezing
rain. Depending on how strong the low level ageostrophic flow does
occur will dictate how much sleet and/or freezing rain will occur
Tuesday night.
The ECMWF points toward the potential of a meteorological bomb
developing over the Great Lakes Region with the GFS somewhat weaker.
Regardless of solution, seems the strength of the warm
advection will allow for a transition to mainly rain for most
areas on Wednesday. Would not be surprised to see convection
potential increase for southern portions of the region
(especially if the ECWMF is more correct). Then strong cold
advection and a transition back to snow showers and squalls
Wednesday night. We will continue to highlight the active period
of weather in the HWO.
&&
.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
Cyclonic flow continues over eastern NY and western New England
with variable amounts of cloud cover tonight through tomorrow.
The clouds will be most persistent associated with the lake
bands and near the westerly upslope regions of the western New
England terrain.
Forecasted mainly VFR conditions the next 24 hours at
KGFL/KALB/KPOU/KPSF. There could be brief lapses to MVFR
conditions in any snow showers at KPSF and KGFL in terms cigs
and vsbys especially tonight and tomorrow afternoon. Cloud bases
will mainly be few-sct early tonight...and then sct-bkn at
3.5-5 kft AGL btwn 02Z-08Z especially north of KPOU. The skies
could partially clear towards 12Z...but redeveloping
stratocumulus is likely at all the sites tomorrow morning into
the afternoon with some cirrus around with the next upper level
disturbance. Clouds bases continue at the 3.5-5 kft AGL range.
The winds will be west to southwest at 5-10 kts early
tonight...then decrease to 4-8 kts overnight. The winds will be
west to northwest at around 10 kts late tomorrow morning into
the afternoon with some gusts close to 20 kts at KPSF.
Outlook...
Friday Night: Moderate Operational Impact. Scattered SHSN.
Saturday: Low Operational Impact. Isolated SHSN.
Saturday Night: No Operational Impact. NO SIG WX.
Sunday: Low Operational Impact. Slight Chance of SN.
Sunday Night: No Operational Impact. NO SIG WX.
Monday: No Operational Impact. NO SIG WX.
Monday Night: Low Operational Impact. Slight Chance of SN.
Tuesday: High Operational Impact. Likely SN.
&&
.HYDROLOGY...
Little change in river levels or flow is expected through early next
week.
A gradual cooling trend with seasonable temperatures is forecast
through weekend. Any precipitation will be in the form of snow.
River ice will form and thicken due to cold temperatures especially
across the northern basins in the Hydro Service Area.
Lake Effect snow will persist across mainly the western Adirondacks
and western Mohawk Valley through much of the weekend.
A storm system may bring significant amounts of precipitation to the
region towards the middle of next week. Precipitation types and
amounts are uncertain at this time, although frozen and/or liquid
precip may occur. Stay tuned for further updates as the even draws
nearer.
For details on specific area rivers and lakes, including
observed and forecast river stages and lake elevations, please
visit the Advanced Hydrologic Prediction Service /AHPS/ graphs
on our website.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...Lake Effect Snow Warning until 7 PM EST Saturday for NYZ032-
033.
Lake Effect Snow Advisory until 6 AM EST Friday for NYZ038-082.
MA...None.
VT...None.
&&
$$
SYNOPSIS...KL/JPV/Wasula
NEAR TERM...KL/Wasula
SHORT TERM...KL/JPV
LONG TERM...BGM
AVIATION...Wasula
HYDROLOGY...KL/JPV
Area Forecast Discussion
National Weather Service Billings MT
318 PM MST Thu Feb 2 2017
.SHORT TERM...valid for Fri and Sat...
Snow was winding down as KBLX radar was showing drying trends
from the north and west. All the models keep this trend in tact
early this evening. Snow was tapering off in Billings and would
expect just a few light snow showers or flurries the rest of the
afternoon and early this evening. Calls to Red Lodge and
surrounding locations within the snow advisory indicate only 1-2
inches of snowfall. Less than an inch expected the rest of the
day. Decided to drop advisories as models indicate snow will taper
off quickly this evening. Clouds are expected to break up this
evening with a clearing trend overnight. Temperatures should drop
quickly when this happens. Due to a cold day, would expect plenty
of lows below zero tonight. Temperature/dewpoint spreads get close
to zero in spots. The possibility of fog is in play, but the HRRR
was very patchy with it, and mainly just along the river valleys.
MAV and MET guidance did not give strong signals for fog. Will
leave it out for now, and let the evening crew take a closer look.
Ridging will build in for Friday but will get flattened by energy
streaming across the Pacific northwest Friday night and Saturday.
This energy will induce surface pressure falls over the northern
Rockies and will allow winds to increase over the western valleys.
Increasing winds will likely interact with fresh snow cover for
areas of blowing snow over western locations. A strong signal does
not exist for really strong winds Friday into Saturday, so will
not issue any highlights at this time, but will monitor closely.
Increasing downslope flow will cause warmer temperatures the next
couple of days. Have aligned PoPs over the west and north where
the strongest energy influx and best mid level warm air advection
exists. Bumped PoPs and snow amounts over the mountains with a
decent moisture feed Friday and Saturday, along with weak energy
streaming through. Should see several inches of snowfall over the
mountains over the two day period. Accumulations do not look big
enough for any highlights however. TWH
.LONG TERM...valid for Sun...Mon...Tue...Wed...Thu...
Only made minor adjustments to the extended forecast as models
looked similar to their previous runs. Noted that the GEFS and
ECMWF ensembles did show some degree of uncertainty with the
pattern through most of the period, so details of the forecast
will likely change with time.
A Pacific jet will push N into Canada from the NW U.S. on Sunday,
while moisture streams through N MT and into the W mountains. A
warm front will lift N with the jet during the day, allowing
temperatures to climb through the 40s. Had low PoPs across the N,
mainly in the morning, and had a chance of snow over the western
mountains. A strong SW flow will set up over the western zones,
bringing windy conditions. The moisture will remain mainly N of
the area Sun. night, except for over the western mountains, which
will receive some more snow. Jet divergence and difluence will
increase over the area on Monday, as another Pacific jet pushes
into the western U.S.. A shortwave will approach from the W and
moisture will get pulled back S into the area ahead of the old
warm front which will become a cold front. Had a slight chance of
snow over the N half of the area with higher PoPs over the western
mountains. Temperatures will be a little lower than Sunday`s
readings.
As the jet dives SE Mon. night, the shortwave will move into the
region, and the cold front will push quickly SE, ushering in snow
showers. Kept PoPs scattered for now due to some model
differences. Steep lapse rates will accompany the system which
will likely cause heavier snow with some of the showers. The
GFS/ECMWF showed strong pressure rises behind the front, on the
order of 6-8mb/3 hrs. The rises combined with subsidence and
instability behind the front could bring a period of strong gusty
winds. On the other hand, the climatologically unfavorable time
for gusty winds may help to inhibit the strength of the gusts.
Will need to watch this period as it gets closer in time.
From Tuesday onward, the forecast details were more uncertain due
to model disagreement. Will generally have a flat NW flow,
transitioning to upper ridging at the end of the period. Kept
slight chance PoPs in until Wed. night, then went generally dry.
It will be colder, with highs from the single digits E to the 30s
W, with warmer conditions expected for Thursday. Arthur
&&
.AVIATION...
Snow, from the Beartooths/Absarokas to KBIL S, will diminish from
N to S through this evening. Expect MVFR to IFR conditions with
the snow, and mountain obscurations over the Beartooth, Absarokas
and NE Bighorns. Otherwise, VFR will prevail tonight, however,
patchy fog will develop around KBIL NE along the river valley.
Patchy fog is also possible around KSHR. Any fog will dissipate by
late Fri. morning. SW surface winds will increase over KLVM late
tonight and remain gusty on Friday. Mountain obscurations will
increase over the Crazys, Beartooth and Absarokas on Friday, with
some lower conditions possible over KLVM. Otherwise, VFR will
prevail on Friday. Arthur
&&
.PRELIMINARY POINT TEMP/POPS...
Fri Sat Sun Mon Tue Wed Thu
-----------------------------------------------------------
BIL 904/025 019/032 021/041 020/032 012/020 005/020 009/033
20/B 01/E 02/S 12/S 42/J 32/S 11/B
LVM 903/035 029/044 034/048 032/044 018/032 014/031 017/038
12/J 24/W 32/O 13/R 42/J 22/S 22/J
HDN 912/023 013/027 010/040 016/030 006/018 000/018 001/031
30/B 01/E 01/E 11/B 42/J 32/S 11/B
MLS 907/019 012/023 007/030 013/026 003/011 906/010 903/025
10/U 23/J 22/S 12/S 42/J 22/S 11/B
4BQ 912/024 015/028 009/040 016/034 006/018 902/017 000/030
40/U 01/E 11/E 01/B 42/J 22/S 11/U
BHK 910/018 010/021 005/030 011/024 003/010 909/008 904/023
00/U 03/J 22/S 12/S 42/J 22/S 11/B
SHR 910/026 020/038 019/043 023/039 012/024 005/023 006/034
70/B 11/B 01/B 01/B 32/J 22/S 21/U
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...None.
WY...None.
&&
$$
weather.gov/billings
Area Forecast Discussion
National Weather Service State College PA
1020 PM EST Thu Feb 2 2017
.SYNOPSIS...
A persistent cool-moist west to northwesterly flow will bring
periods of snow showers, mainly to the Northwest Mountains and
Laurel Highlands tonight into Saturday. Meanwhile, the mean
upper trough over eastern North America will support a period of
below normal temperatures for a change. There could be some
light snow on Sunday, as a weak cold front moves across the
region. The next chance for widespread precipitation will hold
off until late Monday night into Wednesday, as a deep storm
system lifting across the central Great Lakes brings in much
warmer air.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
Skies have cleared out across most of central Pa this evening,
as dry air has arrived in wake of cold front. Dewpoints at 03Z
mainly in the single digits. Seasonably cold westerly flow will
generate some lake effect stratocu/flurries across the NW Mtns
tonight, and perhaps scattered snow showers later tonight, when
models show inversion height rise slightly. Elsewhere, it looks
like a fair and cold night, as surface ridge builds across Pa.
Varying amounts of cirrus will drift over southern Pa associated
with jet streak approaching from the midwest.
Temps should bottom out from the teens in most locations, to
the low 20s across the Lower Susq Valley. However, suspect a
few of the normally colder snow-covered valleys of the north
will dip into the single digits as the latest HRRR depicts.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/...
A shortwave charging southeast across the Grt Lks should support
increased lake effect activity during Friday afternoon and early
evening. However, model inversion heights only rise to around
800mb, suggesting any accums across the NW Mtns will be minimal.
Elsewhere, expect a dry and cold Friday, as weak surface low
associated with shortwave is progged to remain well south of Pa.
However, a good deal of mid level cloudiness is indicated by
afternoon across central and southern Pa.
High temps Friday will range from only upper teens across the NW
Mtns, to the lower 30s in the SE.
&&
.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
High pressure builds into the area on Saturday. Winds are more
northwest early on than today, thus have a chance of snow
showers across the northwest.
Still looking at a chance of some light snow on Sunday, as a
cold front moves across the area late.
Weak high pressure builds into the area on Monday. Main changes
were to cut back on snow showers Sunday night, more claring on
Monday, and slow down precipitation Monday night, and lower
temperatures some Monday night.
Models still show a deep storm lifting northeast across the
central Great Lakes on Wenesday. Did adjust timing and
temperatures some. Also did edge POPS up some. Potential for
thunder, if the system is as deep as the models have it. Still
plenty of time for adding thunder.
Temperatures cool off again after this, but models not as cold
today, as in recent days.
&&
.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
WNW flow will keep orographic/Lake effect snow showers across
the NW Mountains and Laurel Highlands with mainly MVFR
conditions with snow showers bringing periods of IFR.
Central terminals will be mainly VFR, again with a passing snow
shower occasionally reducing local conditions.
Not much change is expected into Friday, with the exception of
a slow diminishing in snow shower coverage over the west and
northwest.
Outlook...
Fri-Sat...VFR, with scattered restrictions in snow showers NW.
Sun...No sig wx early, MVFR with scattered snow showers PM.
Mon...Mainly VFR. Snow showers and reduced conditions possible
NW.
Tue...widespread MVFR/IFR associated with an approaching frontal
system.
&&
.EQUIPMENT...
KFIG surface observation will be off line for an extended
period of time due to failed power feed to the DCP.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...La Corte/Martin
NEAR TERM...Fitzgerald
SHORT TERM...Fitzgerald/La Corte
LONG TERM...Martin
AVIATION...La Corte
EQUIPMENT...
Area Forecast Discussion
National Weather Service Peachtree City GA
618 PM EST Thu Feb 2 2017
.UPDATE...
Updated for the 00Z Aviation Discussion
&&
.PREV DISCUSSION... /Issued 351 PM EST Thu Feb 2 2017/
UPDATE...
Area of rain across north GA and north AL continues to expand
eastward and southward. Have therefore raised pops to likely
across all of north GA late this afternoon and into the early
evening hours. Have also raised pops across the western parts of
central GA as new showers have developed between Montgomery and
Columbus.
PREV DISCUSSION... /Issued 225 PM EST Thu Feb 2 2017/
SHORT TERM /Tonight through Friday Night/...
Main feature affecting our sensible weather this afternoon is a weak
sfc frontal boundary that has been slowly migrating south with time.
As of 19z this frontal boundary was draped roughly from NE Georgia
SW to Adairsville to Cedartown and into Central AL and MS. A few
notable sfc waves are located along this boundary to the west of the
state...and have been responsible for shower activity across MS and
AL...the eastern edge of which is now bleeding into western Ga. The
upper levels are rather quiet with a few perturbations across the
Gulf of Mexico as well as several confined within northern stream
flow. This should keep precip more scattered vs widespread.
Rest of today and tonight: Not super confident on coverage of
showers. HRRR was somewhat bullish in its morning trends but it has
begun to backoff with the 4kmWRF now seeming to have a better
handle. Do think enough lift along the weak front combined with a
somewhat moist airmass ahead of it will be able to develop/sustain
scattered showers across west Georgia in towards metro ATL for most
of the afternoon. Seeing a few hundred J/Kg CAPE ahead of the front
so not entirely out of the question we could see an isolated
lightning strike...tho not really seeing enough energy extend into
the ice crystal layer. SPC mesoanalysis showing decent 925mb
frontogensis across north MS associated with another batch of rain.
This batch /assuming FGen can sustain itself/ will move into
northwest and north central Ga tonight. Not expecting much in the
way of QPF today and tonight...less than a half an inch overall.
Highs 70s south of front...50s north. Lows upper 30s north 40s
south with increasing clouds.
Friday: Potential for some early morning fog...especially central
zones. Aside from that...front will still be pushing across the
southern portion of the CWA...where a few showers may linger
along/behind. Will see a glancing blow from a quick moving...weak
shortwave /currently over Nevada and Utah/ just to our north which
will allow for weak H5 height falls. Potential this could aid lower
level Fgen to produce a few more showers than currently
forecast...basically from I-20 south...but lack of more impressive
dynamics will likely inhibit widespread activity. Highs slightly
cooler Friday with low 70s central to upper 40s mountains. Will
clear out Friday night with more winter-like lows...upper 20s
mountains to low 40s far south CWA.
Kovacik
LONG TERM /Saturday through Thursday/...
Only minor adjustments made to the extended forecast grids with this
cycle. Medium range models continue to show the region under a
relatively flat and fast upper-level flow pattern through the
majority of the period which continues to result in model-to-model
and run-to-run variations in the timing and strength of the various
waves zipping through the flow. Sunday system is now looking to have
a drier and shorter-lived impact on the forecast area. Model blend
POPs much lower and confined to almost exclusively far north
Georgia. Later system is now trending a bit quicker with highest
POPs across north Georgia by late in the day Tuesday through Tuesday
night. Instability/shear still appears to be waning as the system
moves into north Georgia, but sufficient to merit watching for the
possibility of at least a small chance of severe weather. GFS and
ECMWF seem to have flipped a bit with the GFS now shallower and
weaker and the ECMWF deeper/stronger.
20
&&
.AVIATION...
00Z Update...
MVFR cigs will spread across the forecast area this
evening...reaching the MCN area around or just after 06z. Areas of
light rain will continue across mainly the ATL/AHN area early this
evening before shifting south into the CSG/MCN and diminishing.
Cigs will improve Friday with most areas VFR by 18Z Friday. Winds
will be light northwest to north tonight...increasing to 5 to 10
kts by Friday afternoon.
//ATL Confidence...00Z Update...
Medium on timing and height of clouds.
High on remaining elements.
17
&&
.PRELIMINARY POINT TEMPS/POPS...
Athens 45 56 33 52 / 60 30 5 0
Atlanta 43 56 32 52 / 50 30 5 0
Blairsville 36 49 25 48 / 60 20 5 0
Cartersville 39 52 29 52 / 60 20 0 0
Columbus 49 64 37 57 / 40 20 0 0
Gainesville 42 54 31 50 / 60 20 5 0
Macon 49 66 38 55 / 30 20 5 0
Rome 38 53 27 53 / 60 20 5 0
Peachtree City 41 57 30 54 / 50 30 5 0
Vidalia 51 71 43 57 / 10 10 10 0
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...17
LONG TERM....BDL
AVIATION...17
Area Forecast Discussion
National Weather Service Sioux Falls SD
507 PM CST Thu Feb 2 2017
.SHORT TERM...(This evening through Friday)
Issued at 312 PM CST Thu Feb 2 2017
Upper wave crossing the northern Rockies into far western Montana
will slide east-southeast across the forecast area late this evening
through early Friday morning. Moisture looks to remain quite sparse
north of the low level ridge axis, which remains situated from
northwest South Dakota into eastern Nebraska as the wave passes
through the region. So, while the wave should bring an increase in
mid-high level clouds, it will be difficult for precipitation to
reach the surface through the dry layer. Thus, will keep low chance
pops confined to the extreme southwest corner of the forecast area
in Gregory County, where HRRR and some other hi-res models indicate
better saturation and potential for some very light accumulations.
Passage of the wave will be followed by a strong push of drying in
the mid levels, which should allow for abundant sunshine throughout
the area on Friday. Clearing may come soon enough for some decent
radiational cooling late tonight, so have dropped forecast lows a
couple of degrees from previous forecast. Temperatures will remain
on the cool side Friday, but given lack of appreciable snow cover,
have hedged toward the warmer guidance solutions with highs in the
20s most areas.
.LONG TERM...(Friday night through Thursday)
Issued at 312 PM CST Thu Feb 2 2017
Increasing southerly flow will allow winds to become gusty
overnight, as the pressure gradient tightens and low level winds
increase drastically. Went ahead and bumped up the given blended
winds towards the CONSMOS guidance through Saturday morning. Expect
gusts of 30 to 35 mph at times through the night. With increasing
low level moisture and clouds, along with the southerly flow,
overnight temperatures will reach a low in the evening, then slowly
rise in the early morning hours Saturday. Gusty conditions continue
into Saturday, with a cold front moving through the region in the
afternoon and evening. Despite the cloud and snow cover, mixing will
allow high temperatures to warm into the mid 30s to lower 40s.
Quasi-zonal flow on Sunday will stave off much of a cold air push,
resulting in only a few degrees drop in the highs. Monday will
transition into southwest upper level flow ahead of the next storm
system slated to impact the Mississippi Valley and upper Midwest.
The GFS is by far the furthest south and most intense with its storm
evolution, making a large jump southward from the previous run. The
GEM is similarly fast moving, like the GFS, but further north and a
more broad open wave. The ECMWF has a slower and more split flow,
however the northern stream wave could bring some light snowfall to
the area. Confidence remains pretty low with this system, however it
does look like the GFS jump may be more of an outlying solution.
Given the differing solutions, the most likely areas to see impact
in our area would be north of I-90 and into northwest Iowa, with
gusty winds likely areawide. Will leave the chance pops going in the
forecast for now. Snowfall looks to be the main precipitation type,
with colder air pushing southward on the back side of the system. If
we do see accumulating snow develop...blowing snow will be a
concern.
The roller coaster ride of temperatures continues into Wednesday and
Thursday with highs in the teens and 20s.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 506 PM CST Thu Feb 2 2017
VFR conditions expected through the TAF period.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
IA...None.
NE...None.
&&
$$
SHORT TERM...JH
LONG TERM...
AVIATION...JM
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
936 PM EST Thu Feb 2 2017
.SYNOPSIS...
A cold front will move south of the region tonight setting us up for
a cooler Friday, and into the weekend, as high pressure settles in.
Temperatures rebound to normal and above normal through the middle
of next week as southerly flow returns in advance of a moist cold
front approaching from the west.
&&
.NEAR TERM /THROUGH FRIDAY/...
As of 935 PM EST: Precip moving back in from the west ahead of a
wave of low pressure. This precip will continue through the night,
but with low QPF values. High elevation temps have actually warmed
with the WWA ahead of this wave. May still be some wintry mix above
5000 feet, but no significant accums. Colder air filters in late
tonight and early tomorrow behind the wave bringing a wintry mix
back in across portions of the NC Mountains and I-40 corridor. Still
unsure whether it will be more freezing rain/drizzle or snow/sleet.
With the expected low QPF values, any wintry precip amounts would be
low as well. Confidence is still low on any significant accums.
Therefore, will just keep the HWO mention for now.
Otherwise...a slowly passing surface cold front continues to slip
southeast across the lower piedmont of the western Carolinas and
northeast Georgia. Meanwhile, quasi-zonal flow continues aloft, with
a pool of slightly deeper moisture poised to move over the region
from the west tonight. Low level moist upglide will get
reestablished over the surface boundary late this evening, maximize
overnight, then gradually wane through Friday morning as the 850 mb
flow turns westerly. In response, the latest HRRR depicts areas of
rain increasing at times across the southern tier of the forecast
area starting this evening. A complicating factor in the forecast is
that the northern tier, generally along and north of I-40, will have
marginally cold thicknesses for some mixed ptype potential. But,
lower PoP and QPF is indicated in northern sections and the colder
profiles supporting more snow/sleet occur Friday morning as the
precipitation potential and amounts are winding down. There could be
just enough overlap of light precipitation and cooling thicknesses
for minor snow/ice issues along the northern Blue Ridge Friday
morning. However, confidence is too low for any advisory products.
An HWO mention is likely.
Mid levels will dry out from the west through Friday and 850 mb
winds will acquire a westerly direction to help end lingering light
precipitation from west to east through the day. However, a weak
embedded vorticity lobe will cross the northern tier of the forecast
area, so PoP will not be removed too quickly. Low level moisture
could well linger through much of the day in southeast sections,
with some persistent drizzle possible before the downsloping gets
better established. Max temps have been shaded to the cool side of
guidance for Friday afternoon.
&&
.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
As of 200 PM EST Thursday: The short term fcst period kicks off
on Friday evening amidst H5 troughing atop the east/central CONUS,
while a more focused region of quasizonal flow along the base of
said trough prevails across the Southern Appalachians further into
the southeast states. At the surface, an old frontal axis looks
to slide out to sea off the Carolina coastline, while cold/dry
Canadian high pressure fills in across the OH Valley, stretching
southward into the gulf coast.
Pattern evolution through the period will be highlighted by the
dominance of said high pressure ridge which will extend southward in
the lee of the Apps into Western NC overnight into Saturday morning
as a reinforcing back door front. With that, expecting t/td to
fall off back to near/below normal levels for Saturday as weak
hybrid/in-situ wedging prevails beneath H5 confluence. However,
said confluent region will progress on Saturday night out to sea,
likely taking the wedged high pressure along with it. As such,
surface flow will veer southerly into Sunday morning while a region
of weak upglide initiates light shower activity westward across the
MS/TN valleys. Previous guidance runs have suggested the potential
for light mtn precipitation on Sunday morning when low/mid lvl
thermal profiles would favor mixed wintry ptypes, however later
runs have dried up warranting only low end pops for such through
mid/late morning Sunday before waa dominates into Sunday afternoon
allowing for moderation of temperatures to just below normal. Thus,
the fcst will reflect a mix of rain/snow/sleet across the NC/GA/SC
mtns early Sunday morning, with snow being the dominant ptype north
of I40 and a greater chance for mixing southward, all derived via
topdownwx with accums being minimal to non existent given low qpf.
Lastly, although current fcst winds aren`t all that strong, the dry
nature of the airmass to consume the region on Saturday does present
the threat for heightened fire danger as RH levels across much of
Western NC and the SC Upstate fall into the teens to lower 20s.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
As of 200 PM EST Thursday...The medium range starts at 00z Monday
with highly zonal upper level flow across the CONUS. The flow will
begin to amplify somewhat Tuesday into Wednesday, as a shortwave
digs across the Great Plains and a ridge builds upstream along the
East Coast. The deterministic models disagree on how deep the
shortwave trough gets as it crosses the eastern states. But the
timing of an associated cold front is fairly good, crossing the CWFA
Wednesday morning. PoPs gradually ramp up to high-end CHC to low-end
likely in the mountains by Tuesday night. The GFS and EC both have a
few hundred J/kg of sbCAPE with the front, so I will mention slight
CHC of thunder. Given the overnight timing of the front, the severe
threat should remain low. But 0-6 km bulk shear looks to be 50+ kts,
so the severe threat will probably be non-zero, assuming there is
some CAPE. Temps will be about 10 degrees above normal during the day
and 15 or so above normal at night ahead of the front.
Wednesday night into Friday, the models agree that a longwave trough
will dig across the eastern CONUS, with strong low-level NWLY CAA
flow ushering in normal to below normal temps by the end of the
medium range. With the upper trough axis remain along the
Appalachians, it doesn`t look like a good set up for NW flow snow
showers. However, the GFS spins up a southern low pressure system,
which would be interesting for potential heavy snow across the
mountains. The 12z EC is completely dry. For now I will keep a CHC
pop in there for Thursday.
&&
.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
At KCLT...Anticipate cigs lowering through low VFR this evening then
through MVFR after midnight as deeper moisture arrives from the
west. Low level moist upglide will continue over a surface boundary
south of the airfield tonight, with areas of light rain continuing.
A period of IFR ceilings is likely from after daybreak through late
afternoon along with patchy rain or drizzle. Precip should be light
enough to keep vsby restrictions to a minimum, but MVFR cannot be
ruled out. Cigs lift to MVFR by late afternoon as precip ends and
low level flow begins to turn NW. NE winds continue through the
period with highest speeds, and possible low end gusts overnight.
Elsewhere...similar trends to KCLT. Timing of restrictions are
earlier for SC sites. KAVL and KHKY have less chance of IFR cigs.
Winds remain N through the period at KAVL with NW winds developing
during the afternoon at KAND/KHKY. Any precipitation should remain
quite light around KAVL, but nearby sleet cannot be ruled out Friday
morning before the precipitation ends.
Outlook: Drying high pressure will build overhead through Saturday.
A brief period of light precipitation could occur across the
mountains on Sunday. Dry conditions are expected Monday before
deeper moisture returns through Tuesday.
Confidence Table...
02-08Z 08-14Z 14-20Z 20-00Z
KCLT High 100% High 86% Med 77% Med 71%
KGSP High 100% High 87% Med 71% Med 61%
KAVL High 100% High 86% High 91% High 82%
KHKY High 100% High 90% High 90% High 89%
KGMU High 100% Med 78% Low 54% Med 72%
KAND High 100% Med 71% Med 68% High 93%
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
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...None.
SC...None.
&&
$$
SYNOPSIS...CSH
NEAR TERM...HG/RWH
SHORT TERM...CDG
LONG TERM...ARK
AVIATION...RWH
Area Forecast Discussion
National Weather Service Marquette MI
710 PM EST Thu Feb 2 2017
.SHORT TERM...(This evening through Friday)
Issued at 418 PM EST THU FEB 2 2017
Water vapor imagery and RAP analysis show a deep trof over
eastern Canada. Across the much of the CONUS, flow is more zonally
oriented downstream of split flow convergence over the western
CONUS. The Upper Lakes are currently on the periphery of the
arctic air mass that has settled s and e in association with the
eastern Canada trof. Although 850mb temps are around -20C,
upstream 12Z KINL sounding showed that the air mass is dry, and
the inversion was around 2kft AGL. As a result, LES today has been
on the lighter side. However, gusty winds and resulting blsn have
led to very poor vis, especially over the Keweenaw where winds
have been gusting to around 40mph. Winds have been slowly backing
today as another shortwave swinging thru the eastern Canada trof
approaches the Upper Lakes. As a result, LES bands have been
shifting slowly northward today. Dry air mass and backing winds
have also allowed sunny skies to develop from the far w around
KIWD into central Upper MI.
Not alot of change expected over the next 24hrs. Approaching
shortwave will give LES a boost tonight, mainly during the
evening. Fcst soundings only show a minor boost of 1-2kft to the
inversion heights. So, while some increase in LES will occur, not
expecting a major increase from what has been seen today. Passage
of shortwave will result in some veering of winds, shifting LES to
affect more of western Upper MI and more of the eastern fcst
area. LES will then continue thru Fri. Increasing subsidence thru
the morning hrs in the wake of tonight`s shortwave will lead to
some weakening of LES before another weak shortwave approaches in
the aftn. However, given the overall dry arctic air mass
dominating tonight/Fri, accumulations will be kept in check. In
general for the tonight/Fri period, expect snow accumulations of
3-5 inches northwest and 4 to 8 inches e. No changes to headlines
were needed.
With winds remaining up tonight and lake effect clouds likely
expanding in coverage as winds veer a bit, temps shouldn`t
plummet. Expect seasonably cold readings into the 0 to -5F range
over the interior central and w. Wind chills may fall to as low as
-20F, falling short of warranting any wind chill headlines. Highs
on Fri will generally be in the teens with some lwr 20s s central.
.LONG TERM...(Friday night through Thursday)
Issued at 401 PM EST THU FEB 2 2017
The main issues for the extended will be a quick moving clipper
system expected to bring light snow into the weekend along with
light to moderate snow on the back side of the clipper. Eyes will
also be on a potential winter storm/lake enhancement for early next
week, depending on the exact track of a low pressure system progged
to develop. There are definitely a lot of variances in model
solutions to this point.
Friday night: The CWA will be on the southwestern edge of, slowly
departing, broad upper-level troughing over the eastern U.S. while
the western U.S. remains under weak/broad upper level ridging. The
trough over the eastern U.S. will help to keep 850mb temperatures
generally between -15C and -18C, which will be more than enough to
keep lake effect potential in the forecast. Winds through Friday
night will generally be out of the west to west-northwest, which
would keep the lake effect snow potential over the Keweenaw
Peninsula and areas mainly to the east of Munising. A shortwave is
expected to slide across the area, which will allow snowfall
intensity and flake size to increase to some extent as inversion
heights jump up to around 6-7kft with added lift and lake induced
instability. Generally, expecting between 2 and 5 inches in the west
to west-northwest wind snow belts. Areas outside of the
aforementioned lake effect snow belts can expect partly cloudy skies
with no more than flurries through this time period.
Saturday into Saturday night: A surface high pressure ridge will
slide across the Upper Great Lakes region, along with drier air,
which will help to reduce lake effect snow chances in the morning. A
quick moving clipper system will slide into the area from the west
Saturday afternoon into Saturday night bringing a widespread area of
light snow. Overall moisture will be limited with this system and
the fast moving nature of the clipper will keep snowfall totals at
generally 1 to 3 inches Saturday afternoon into Saturday night. The
only area that may see increased totals, due to lake enhancement,
would be over the eastern U.P. with southwest flow off Lake
Michigan. This would be short-lived and limited to Saturday evening
as winds quickly shift to the west.
Sunday and Sunday night: As the aforementioned clipper system slides
to the east of the area, winds will become northwesterly. This,
along with 850mb dropping back to -18C to -20C will allow for
increased lake effect snow potential for the northwest wind snow
belts. A shortwave is also progged to slide through the area at the
same time, which will help increase inversion heights up to around 7-
8kft. This will act to enhance the snowfall rates across the
aforementioned snow belts, with light to moderate accumulations
possible. Snow ratios will not be overly impressive as the DGZ is
fairly shallow.
The next area of concern in the extended will be the potential for a
stronger winter storm system to slide through the area late Monday
night through Wednesday. There, of course, continues to be a lot of
uncertainty on timing and details of this system with it being so
far out and due to the limited sampling, but it is definitely
something to keep an eye on as the EC/GEM/GFS are showing similar a
low pressure system sliding through the Upper Great Lakes region.
The storm track and intensity is still uncertain as the GFS is
farther west and a bit warmer, while the EC is farther to the east
keeping the system a bit cooler and mainly snow. If the EC/GFS are
correct, there would be lake enhancement downwind of Lake Superior,
which would also boost totals up. If the Canadian solution is
correct, the low pressure center would slide across the central or
eastern portion of the U.P. bringing a mix of precipitation for the
eastern U.P. The latest Canadian solution is much farther north and
west than previous solutions, and more out of line with the GFS/EC.
Stay tuned as the models converge on a better solution.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 709 PM EST THU FEB 2 2017
Under westerly winds gusting over 30kt, blsn and persistent lake
effect will impact KCMX, keeping conditions LIFR, probably for most
of the fcst period. There may be some improvement Fri morning as
winds diminish a bit. At KIWD, although VFR conditions will be the
rule this aftn, BLSN may reduce vis to MVFR at times. Prevailing
MVFR or near MVFR conditions may then set in tonight as slight
veering of winds bring lake effect clouds/-shsn to the terminal.
Improvement to VFR expected Fri morning. At KSAW, VFR conditions
will mostly prevail, though MVFR cigs and flurries may develop
tonight.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 418 PM EST THU FEB 2 2017
W to NW gales and heavy freezing spray will continue tonight over
much of Lake Superior. While gales will end over the w Fri
morning, gales won`t end over the e until Fri night. Winds will
remain brisk, frequently in the 20-30kt range over the weekend as
a low pres trof passes. Lightest winds of the period will occur
late Sun night/Mon morning as a high pres ridge passes. Then, a
low pres system moving e into the Great Lakes region will bring
increasing winds, eventually to 20-30kt, late Mon/Tue.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
Lake Effect Snow Advisory until 7 AM EST Saturday for MIZ001-003-
006-007.
Lake Superior...
Heavy Freezing Spray Warning until 5 PM EST Friday for
LSZ263>267.
Gale Warning until midnight EST Friday night for LSZ264>267.
Heavy Freezing Spray Warning until 7 AM EST /6 AM CST/ Friday
for LSZ162.
Gale Warning until 7 AM EST /6 AM CST/ Friday for LSZ162-263.
Lake Michigan...
None.
&&
$$
SHORT TERM...Rolfson
LONG TERM...KEC
AVIATION...JLB
MARINE...Rolfson
Area Forecast Discussion
National Weather Service Blacksburg VA
942 PM EST Thu Feb 2 2017
.SYNOPSIS...
A weak front across the eastern Carolinas will remain about
stationary overnight into early Friday before sliding well south
of the area by Friday night. Weak low pressure tracking along
the boundary may bring a few sprinkles or flurries to southern
sections late tonight into early Friday. Otherwise a large dome
of cold high pressure will shift east into the area Friday into
Saturday resulting in drier and colder weather through early
this weekend.
&&
.NEAR TERM /THROUGH FRIDAY/...
As of 930 PM EST Thursday...
Analysis showing that very dry air has filtered south to near
the VA/NC border this evening with dewpoints now into the teens
across much of the region. Axis of mostly mid deck clouds
holding moisture in to some degree across northern NC where
just north of the front and within a region of weak lift ahead
of a faint surface wave over the western Carolinas. Latest HRRR
suggests that perhaps a few sprinkles or flurries could clip
the southernmost counties overnight, so leaving in a mention
after midnight into early Friday despite dry air that may keep
most precip aloft. Otherwise with clouds staying farther south
to start, and things perhaps remaining clear longer north half
given very dry air per evening RNK raob, have lowered lows a bit
as could even see a few teens far northwest if clouds/mixing
are less. Elsewhere range from 20s north/west to low/mid 30s
southern sections appears on track.
Previous update as of 710 PM EST Thursday...
Ridge of high pressure building in north of an elongated low-
level baroclinic zone from the Deep South into the central
Carolinas. Extensive low/mid-level cloud shield presently
extends along the boundary, with low-level dry advection taking
is place on northwest winds across the northern two-thirds of
the forecast area.
Isentropic ascent should begin late tonight ahead of a weak
vort max that ripples across the Ohio Valley. It should at
least induce some northeastward increase in the cloud shield. As
far as PoPs/Wx go, though it`s worth noting the 18z GFS came in
a little wetter in northwest North Carolina, the presence of
dry low-level air below the cloud layer off most model BUFKIT
soundings is a question mark. Recent high-res simulated
reflectivity guidance such as the HRRR and the NMM display a
mottled/blotchy appearance from the Virginia Southside and into
northwest North Carolina, while the ARW shows nothing affecting
our area. I think the indication from the hi-res models is
toward something of sprinkles (or flurries in the North Carolina
high country where 2-m temps should be cold enough). With the
drier air in place at low levels, that seems like a reasonable
outcome. So I`ve sided that way with this update vs the wetter
GFS with scattered sprinkles or flurries introduced across the
southside into northwest North Carolina, dependent on
temperatures. Rest of the forecast area stays dry. Other than
that small change, the forecast remains unchanged.
Previous discussion follows...
The surface boundary over North Carolina has drifted further
south this afternoon and is near the NC/SC border. The surface
reflection that was over North Carolina is now in South Carolina
and may become a bonafide wave tonight. If this wave does
strength, it will push low level moisture/theta-E boundary north
of the NC/VA border. Isentropic lift is expected to increase
over the piedmont after midnight with light precipitation
falling by sunrise. Only the GFS advances this precipitation
north of the NC/VA border, therefore went with the consensus
only having low pops for our North Carolina counties. Model
sounding showing an isothermal profile at Boone NC with
precipitation being mainly snow. If the environment is drier at
the onset, evaporative cooling may lead to a brief period of
sleet before changing over to snow. Profiles are warmer east of
the Blue Ridge for rain, but a few minutes of sleet is not out
of the question. Bulk of the wetting rain should stay with the
wave and fall in central and eastern North Carolina tomorrow
morning. This wave will exit the outer banks by noon with drier
cold air coming in during the afternoon.
Cool northerly flow tonight will send temperatures down to
normal levels (in the 20s) for most of the area. Portions of
northern North Carolina will only fall into the low to mid 30s
as clouds from the surface wave blankets the area. Once this
wave moves off the coast, more cold air will over take the area.
Friday`s high temperatures will be 4F-8F degrees colder than
normal. High Friday will range from the 30s across the mountains
to low to mid 40s east.
&&
.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/...
As of 255 PM EST Thursday...
Forecast models agree on cold/dry high pressure moving across
late Friday night into Saturday. Next upstream system appears
weaker/drier and with strong westerly flow is not expected to
bring much in the way of precip amounts Sunday. As such have
lowered pops across the board limiting low chance pops to the
mountains. Not out of the question to get sprinkles across the
piedmont by midday Sunday. As far as ptype looks mainly snow to
rain...some sleet possible. Amounts of snow looks under an inch
over SE WV to the NC high country.
Temperatures running close to or below normal Friday night-
Sunday, then, heights/8h temps build Sunday night, with lows in
the 30s.
Any precip Sunday should be gone by dusk.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
As Of 150 PM EST Thursday...
Definitely looking more active weather wise this period. Wave
moving along frontal boundary draped from the southern Plains to
the Gulf coast arrives by Monday night with a threat of rain,
as temperatures stay above freezing. The front lifts north as a
warm front Tuesday with increasing chances of showers. Strong
low level jet starts to feed moisture more to the mountains by
Tuesday night, and models have sped up timing of front for
Wednesday and looks like best threat of showers will be Tuesday
night into early Wednesday before colder air works in Wednesday
afternoon into Wednesday evening with airmass drying out. The
thunder threat will be small given timing of front now. However,
wind energy will be strong and winds along and behind front the
front could reach advisory levels per latest model trends
Wednesday in the mountains. Have increased gusts to account for
this trend. After a mild Monday-Tuesday with above normal
temperatures should still see temps at or above normal Wednesday
before the colder air works in, but could be a case where
temperatures drop in the west in the afternoon. Some quick
upslope snow showers Wed night before ending.
The 12z GFS appears to be curving a shortwave and sfc low
across the southern U.S. Thursday while the EC is drier and
colder with high pressure across the Ohio Valley into the
mountains. A low threat of snow possible Thursday across our
southern tier of counties, but will bear watching trends, though
pattern favors a quick system.
&&
.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
As of 710 PM EST Thursday...
VFR conditions should generally be the rule. A northward
increase in BKN to OVC ceilings should begin tonight mainly at
DAN and after midnight/into Friday for BCB, BLF, LYH and ROA.
Wouldn`t rule out an MVFR ceiling at DAN into early Friday but
feel VFR should predominate. Any precipitation should remain
south of the terminals through the period, with clearing taking
place Friday afternoon.
Northwest winds 4-10 kts (highest at ROA) become light and
variable tonight, before trending light northwesterly Fri
afternoon.
Extended Aviation Discussion...
VFR conditions are expected Friday night and Saturday under
high pressure. Lower ceilings and precipitation will return
Sunday as the low pressure tracks into the Ohio Valley. The best
probability of precipitation will be in the mountains. Weak
high pressure follows this system for early next week with
mainly VFR expected Monday except for possible lingering MVFR
cigs across the mountains early on.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...None.
NC...None.
WV...None.
&&
$$
SYNOPSIS...JH
NEAR TERM...AL/JH/RCS
SHORT TERM...WP
LONG TERM...WP
AVIATION...AL/RCS
Area Forecast Discussion
National Weather Service Sacramento CA
327 PM PST Thu Feb 2 2017
.Synopsis...
Wet pattern with rain and mountain snow today into Saturday.
Gusty winds Friday. Showers Saturday will be followed by another
round of heavier precipitation late Sunday. Wet pattern continuing
through next week.
&&
.Discussion...
Although chain controls were necessary earlier this morning over
the Sierra, snow levels later rose and chain controls were lifted.
There have only been light scattered showers moving across the
region this afternoon. Because of that, we stopped the Winter
Storm Warning for today and have it resuming tonight at 10 pm
through early Saturday morning.
The HRRR model hourly runs have been consistently showing that the
next organized wave of widespread precipitation will move inland
late tonight continuing into Friday. This next wave will bring
another round of rain and snow, but also strong winds for most of
Friday with gusts 40 to 45 mph in the valley and foothills. With
those winds, white-out conditions are possible over the Sierra
which will make mountain travel dangerous. Please check with
CalTrans before any plans to drive over the Sierra. There may
also be thunderstorm development in the afternoon if conditions
align together at the right time. If they do, some of those storms
may have severe potential in the valley and into the foothills.
Residents should keep an eye on the sky and take shelter if they
hear thunder tomorrow.
Flat, moist southwest flow continues on Saturday for a continued
shower threat during the day Saturday. Sunday could start out dry
but next Pacific system moves quickly to the coast by Sunday
afternoon. Moderate precipitation is likely to return to Norcal by
Sunday night with another round of moderately strong winds.
&&
.EXTENDED DISCUSSION (Monday THROUGH Thursday)
A series of storms will impact the forecast area during the
extended period. The first one will be a Pacific frontal system
moving across interior NorCal. This front will spread precipitation
Sunday night into Monday. Brief break in precipitation Monday
night into early Tuesday before the next system moves in. Long
range forecasts in general agreement that a deep moisture plume
will approach the area Tuesday into Wednesday with the GFS being
the wettest solution this far out. Snow levels expected around
5000 to 6000 feet Monday, rising above pass levels on Tuesday
under warm air advection. The next cold front will move across the
forecast area Thursday into Friday with another round of
widespread precipitation.
&&
.AVIATION...
Low pressure system approaches interior NorCal with associated
frontal system moving through. Showers in the evening before the
next round of precipitation moves through mainly after 10z Friday.
For interior NorCal MVFR/IFR conditions possible nxt 24 hrs with
local LIFR over Wrn Plumas/Siernev fthls/mtns. In Cntrl Vly, areas
SEly sfc wnd gsts to 25-30 kts after 12z Friday. Chance of
thunderstorms in the Valley after 18z Friday.
&&
.STO WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning from 10 PM this evening to 4 AM PST
Saturday for West Slope Northern Sierra Nevada-Western Plumas
County/Lassen Park.
Wind Advisory from 4 AM to 10 PM PST Friday for Central
Sacramento Valley-Northeast Foothills/Sacramento Valley-Northern
Sacramento Valley-Southern Sacramento Valley.
&&
$$