Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/11/17
Area Forecast Discussion
National Weather Service La Crosse WI
836 PM CST Tue Jan 10 2017
Issued at 833 PM CST Tue Jan 10 2017
Based on diminishing winds and reports across the advisory area,
things are improving. Still slick roads overnight but not quite
as bad as early evening with enhanced blowing snow/whiteout. Will
be updating services to match this expiration.
Have updated the forecast to include a snow chance overnight as
the current radar echoes near Omaha head toward the area. The
forcing looks like 700-800mb frontogenesis and 11.01Z RAP takes
this narrow region and shifts it through in the the 06-12Z time
frame tonight. NW-SE oriented band should shift from SW to NE
through the forecast area. Not getting too excited about it as
Omaha RAOB wasnt hog wild on saturation IN the forcing area around
00Z and the air mass is dry out ahead of it. forcing is moderate
and lapse rates at mid-levels are favorable. Will continue to
monitor it but 30-50% chances have been added - mainly north of a
KCCY-KISW line. Maybe a dusting of snow?
Next weather to investigate will be Wednesdays SW-NE snow band
UPDATE Issued at 701 PM CST Tue Jan 10 2017
Have extended the winter weather advisory based on too many
impacts in the gusting winds in the 30 to 40 mph range. reports of
whiteouts and accidents in southeast minnesota prompted the
extension. but...with the wind gusting in the 30 mph range in
wisconsin and the fresh snow...decided hazardous travel due to
covered roads and isolated whiteouts /kbrf and keau reporting haze
= BLSN/ would warrant the extension there too. MPX matched this
area up with the extension.
we think the winds will diminish over the next hours and the
whiteout pockets will subside. roads will still be messy overnight with
a tantalizing slushy from your favorite store turning to pretty
solid ice with temperatures falling to into the 8-15F range
as soon as things settle down with these hazards...will be
evaluating the morning snow and ensuring the forecast is on
.SHORT TERM...(Tonight through Wednesday night)
Issued at 230 PM CST Tue Jan 10 2017
Main concerns this period are winds this evening, snow chances with
the next wave and round of lift later tonight into Wed evening,
18z data analysis had a roughly 990mb low over SW WI, lifting rather
quickly NE. Liquid precip over all but the far SE/east ends of the
fcst area has changed to snow. Rather impressive display of silver-
dollar sized snowflakes at the ARX office when it changed over
between 1015-11 AM. Deformation band of snow around the north/west
side of the sfc-mid level low/trough was translating rather quickly
east across the area. Vsbys in the heart of the band in the 1/4 to
3/4 mile range. Vsbys already improving to 1 to 2 miles across the
west/SW ends of the fcst area. Brisk NW winds on the back side of
the low spreading across the area, with colder air/falling temps
already spreading across the west 1/3 of the fcst area.
Model runs of 10.12z initialized well. Solutions in good agreement
on the vigorous mid level shortwave/trough axis moving quickly east
of the area late this afternoon/early this evening. Decent agreement
continues Wed/Wed night as a northern stream wave passes across the
north end of the region, while energy coming out of the west coast
troughing arrives into the Upper Midwest Wed night. Short-term fcst
confidence is good this cycle.
For the short term, sfc low-700mb trough moves quickly NE to the
east end of the MI U.P. by 00z, taking the snow with it. Any
lingering -SN near/after 00z down to sct flurries as colder/drier
air and post low/trough subsidence spread quickly across the area.
Distance-speed tool has the west edge of the post-low cloud deck to
near the MS river by 00z. Tightest pressure gradient moves across
the area later this afternoon into early this evening. So far, NW
winds in this tighter gradient area over SW MN into western IA have
mainly been 20-30mph gusting 30-40mph. Considered a wind advisory
for at least the west 1/3 to 1/2 of the fcst area thru early this
evening, but with winds sub-advisory to this point, will hold off
for now. Will continue with the winter weather advisory thru 00z for
the winds, some drifting/blowing snow and the refreeze on untreated
roads/walkways as temps fall into the teens to mid 20s.
Respite from the snow rather brief across the north 1/2 to 2/3 of
the fcst area. Next round of stronger lower/mid level warm
advection/isentropic lift is already into the north end of the fcst
area after midnight, with this forcing/lift maximized around the -
15C level. Concern later tonight is how quickly with the roughly 925-
800mb layer re-saturate and allow snow to reach the ground. Greater
of the 925-800mb saturation progged over the north 1/4 to 1/3 of the
fcst area by later tonight, with a deep dry 925 to nearly 700mb
layer remaining over the south side of the fcst area. Consensus snow
chances back in the 50-70% range across the north of the fcst area
to remaining dry across the south half by 12z Wed quite reasonable.
Stronger/deeper lift spreads across the north 1/3 to 1/2 of the fcst
area Wed. Continued with snow chances 50-70% across the north end of
the fcst area much of Wed. These blend well with neighboring grids,
but may not be high enough. Potential for another 1 to 2 inches of
snow along/north of hwy 29 across WI. Yet another round of
increasing mid/upper level forcing/lift, ahead of the energy
ejecting out of the west coast troughing, spreads across mainly the
central/south parts of the fcst area late Wed night. Continued -SN
chances mainly along/south of I-90 thru Wed night good for now.
Blend of the guidance lows/highs for tonight thru Wed night looks
well trended at this time.
.LONG TERM...(Thursday through Tuesday)
Issued at 230 PM CST Tue Jan 10 2017
For Thursday thru Friday night: main fcst concerns this period are
lingering -SN chances Thu morning, -SN chances again Fri night.
Model runs of 10.12z in good agreement as a cold trough settles over
the northern great lakes Thu, then quickly giving way to more
westerly flow aloft by Fri. Decent agreement for yet another W-NW
flow shortwave to come across the northern plains and approach the
region Fri night. Fcst confidence in the Thu thru Fri night period
is generally good this cycle.
Moisture/lift over the south end of the fcst area from later Wed
night exits rather quickly Thu morning. Rather deep/dry airmass to
then settle across the region for Thu afternoon thru Fri as hgts
rise and arctic high pressure settles across the region. With the
arctic high overhead and what should be clear skies and light winds,
along with 925mb in the -12c to -18c range, Thu night/Friday shaping
up to be a very cold period. Consensus lows mostly 0F to -15F Thu
night and highs Fri mostly 5F to 15F. With a fast zonal flow and an
approaching shortwave Fri night, the next round of lower level warm
advection/isentropic lift, along with an increase of mid/high level
moisture spreads across the area by later Fri night. The small
consensus -SN chance for much of the area by later Fri night looks
good at this time. With an increase of clouds and a return of south
flow/warm advection, the consensus lows near normal for Fri night
look good as well.
For Saturday thru Tuesday (days 4 to 7): main fcst concerns this
period are -SN chance Sat, precip chances Sun night into Tue,
temperatures thru the period.
Medium range model runs of 10.00z/10.12z in reasonable agreement for
a weaker NW flow shortwave to pass across the region Sat. Detail
differences on handling of waves in the flow increases for Sun, even
more so for Mon into Tue. Bigger differences by Mon/Tue concern the
phasing, or not, of northern/southern stream features over the
mid/upper MS valley for early next week. Fcst confidence average for
Sat, then below average by Mon/Tue.
Northwest flow wave passing to pass on Sat looking to spread a round
of weaker mid/upper level lift across the area. With sfc high
pressure over the area, questions concern the amount of moisture
available for snow production. Some small -SN chances on Sat okay
for now. Sunday would be a between systems day with sfc high
pressure ridging over the area, for what should be a dry/seasonable
day. For early next week, less phased model runs offer a drier
solution for Mon/Tue as the southern stream portion moves east thru
the mid MS valley. More phased runs pull the southern stream energy
toward/into the upper MS valley and spread precip chances northward
and across much of the area as early as Sun night and continuing as
late as Tue. Lower level warm advection ahead of whatever form the
trough ends up taking spreads across the region for Mon/Tue. Enough
so for precip type issues with any potential system for early next
week. Given low confidence in the details, will stay with the
model/ensemble consensus for these day 6/7 periods. Somewhat better
confidence that temps for Sun-Tue will be above normal.
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 700 PM CST Tue Jan 10 2017
Satellite would indicate an area of clearing is heading in before
clouds try to reform and lower by morning. Confidence is not high
on the details of the morning forecast into Wednesday. it appears
a snow band will be around and could affect the taf sites
Wednesday with ifr snow.
winds are gusting in the 30-40 mph range with BLSN now. the winds
will diminish as the evening continues.
WI...Winter Weather Advisory until 9 PM CST this evening for WIZ017-
MN...Winter Weather Advisory until 9 PM CST this evening for MNZ079-
Area Forecast Discussion
National Weather Service State College PA
1041 PM EST Tue Jan 10 2017
Low pressure will track northward through the Great Lakes tonight,
pushing a dying cold front/occluded front through Pennsylvania
overnight. An anomalous upper level ridge will build over the
southeast United States later this week and this weekend. At the
surface, a quasi-stationary frontal boundary will oscillate in the
vicinity of Pa through the period.
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
No real changes to the previous reasoning. Precip is ongoing with
the far northern counties seeing a mix of sleet and freezing rain.
Low level ageostrophic component to the flow is about 80kt out of
the northeast, helping support the strong cold air damming
scenario in place. Temperatures have been very slow to start
rising and there is no reason to expect much change in that
overnight. As they grudgingly top freezing, the threat for icing
will diminish accordingly.
Will maintain the Winter Weather Advisory, but still keep a very
close eye on precip trends and the potential to upgrade to an Ice
Storm Warning over the far northeast.
RAP shows very strong winds just above the surface over most of
Pa. The strong low level inversion is pretty much shielding us
from the worst, with the possible exception of some of the highest
ridgetops. A Wind Advisory remains up for the Northwest Mountains
for wind gusts around or slightly in excess of 45 mph, mainly on
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/...
Latest models have slowed the timing of the showers so there
could be some lingering precipitation through the eastern and
northern portion of the area. Any lingering precipitation will be
rain. Daytime Wednesday will see large scale subsidence
overspreading the region as the mid level shortwave passes east
of the state. Much milder air will flow into the region behind
occluded front, as a mid level negatively tilted ridge will allow
for drier air. This will allow for some clearing skies and
warming temperatures. Expect readings likely topping out between
45-50F over most of the area. Model soundings support a good deal
of sunshine east of the Mtns. However, some orographic low clouds
appear possible in the morning over the Alleghenies.
.LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...
Moisture transport aloft from southern CA will stream into the
Ohio Valley, bringing a shot of rain Wed night into Thu night.
Another wave should ride along a SW-NE oriented frontal boundary.
East of the precip band, mild air will work up the Appalachians
into the region, bringing a period of temperatures 15-20 degrees
above normal as highs reach the 50s on Thursday and into Friday in
The front pushes across the region on Friday. Colder air will
gradually filter back in as 1045mb high slides across NY state. A
quasi stationary boundary will setup the temperature profile on a
west to east line with the northern half of the state on the edge
of shallow cold air Sat- Mon. This stalled frontal boundary with
moist flow should keep our PoPs higher than normal. Thus some
GEFS members have ice pellets and freezing rain as a potential
issue next weekend. Have adjusted the POPS and the P-type which
should shift as the models come in agreement. Have kept either
snow or rain currently but next weekend has a lot of uncertainty
and will depend on how strong the high is and how far south the
shallow arctic air slides Sat-Mon.
.AVIATION /04Z WEDNESDAY THROUGH SUNDAY/...
A very strong core of SSW wind in the 2-5 KFT AGL layer will
shift eastward across the state late this evening into the
overnight, helping to create widespread LLWS (reaching as high as
60KT at KBFD and 35-45KT elsewhere), and a few waves of mainly
freezing rain along with cigs lowering to MVFR/IFR as below
freezing surface temperatures continue for much of central PA.
Temperatures will slowly inch up to slightly above freezing with
the precip ending primarily as rain late tonight into Wednesday
morning. After that, conditions should improve to VFR areawide,
with the western areas taking the longest.
Another wave slides in later Wed into Wed night, bringing a
return of restrictions and an area of rain - mainly to the western
half of cwa.
Wed...Sub-VFR likely. Rain exits southeast airspace in the
morning then returns 00-06z Thu. LLWS likely Wed ngt-Thu.
Thu...Sub-VFR/LLWS likely with rain NW 1/2 airspace.
Fri night-Sat...Sub-VFR likely with snow or mixed precipitation.
Sunday...Areas of MVFR to IFR cigs with periods of light snow or
snow showers...mainly across the southern half of the state.
Winter Weather Advisory until 4 AM EST Wednesday FOR PAZ006-
Winter Weather Advisory until midnight EST tonight FOR PAZ005-
Wind Advisory until 1 AM EST Wednesday FOR PAZ004-005.
Near Term...La Corte
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
935 PM EST Tue Jan 10 2017
The high wind warning will remain in effect through the evening with
no changes as solid mid 40 knot wind gusts, with a few peak 50s,
continue to be reported from SE Wisconsin (01Z at SBM and 02Z at
FWA) through northern Indiana. There remains a few more hours of
damaging wind gusts for SE Michigan in this scenario then
diminishing to advisory levels shortly after midnight.
The damaging wind field is being supported by strong low pressure
that continues to deepen during the mid evening while exiting
eastern Lake Superior. There were a few surges of mid 50 mph gusts
and isolated power outages in the warm sector with showers and as
temperatures rose into the mid and upper 40s throughout the
region. Now, the associated cold front is on the way through SE
Michigan as of this writing. Dynamic forcing with the front and strong
cold advection immediately behind will steepen lapse rates below
800-850 mb where a mid 50 knot wind field continues to reside
based on the latest RAP model soundings and radar VWP. Wind gusts
in the 40 to 50 knot range will then remain possible at all
locations through about 1 AM as the low level thermal trough
surges into the region. The wind field will then quickly diminish
as the low continues to move rapidly toward James Bay. The low
level thermal trough will also lift north of the region and leave
more neutral thermal and shallow boundary layer conditions over
SE Michigan. This may allow a downgrade to advisory by then,
especially in the Detroit area.
Issued at 717 PM EST Tue Jan 10 2017
A strong cold front will bring a westerly wind shift to the terminal
corridor during early evening. Gusts will frequently be around 40
knots with a stray near 50 knots possible until about midnight.
Gusts will then diminish steadily to around 20 knots by sunrise.
Maintained the mention of low level wind shear due to the
exceptionally high wind speed just off the surface shown in model
soundings, 60-70 knots in the 1500-2000 ft layer.
As the wind diminishes, the effects of colder and drier air will be
seen in a clearing trend overnight. Expect just a short window of
lake effect activation augmenting MVFR clouds early in the overnight
before the core of coldest air shifts back northward toward sunrise.
Much lighter south wind will then help maintain VFR through
For DTW...Strong wind gusts remain the primary concern through
evening due to frequent gusts running around 40 knots with
increasing support from 250 degree direction. A stray gust near 50
knots remains possible through about midnight with low level wind
shear 60-70 knots up to 2000 ft. Otherwise, temperatures surging
into the upper 40s will maintain precipitation as all rain until
the pattern shifts eastward with the cold front.
//DTW Threshold Probabilities...
* High for ceilings below 5k ft through evening then low late
tonight into Wednesday.
* Moderate for exceeding cross wind threshold from 250/G40
Issued at 300 PM EST Tue Jan 10 2017
Strong cyclone, impressive in appearance on water vapor imagery, is
rapidly deepening over the western Great Lakes at press time. At
approximately 986mb, RAP13 progs suggest another 10mb to go in the
next 9 hours or so. Accompanying wind field has ramped up
considerably over the last couple of hours and will continue to
rapidly strengthen over the next several hours.
Radar mosaic indicates to well-defined lines of showers. The first
is along the convergent right side of the 80kt low-level jet. The
second is positioned immediately along a strong cold front that is
anchored firmly to the left side of the LLJ. The corridor in between
will contain the greatest threat for wind gusts to approach 60 mph
through approximately 02z. 0-1km Richardson numbers of 0.2 to 0.35
indicating a stability balance capable of supporting eddies that
will mix down bursts of higher momentum. Mean wind within this layer
will increase to 50 to 55kts between now and fropa. Widespread
upstream peak wind gusts of 40 to 45 kts offer certainty in meeting
wind advisory criteria this evening. However, increasing
availability of higher winds within the column along with some
potential for deeper mixing associated with cold fropa and/or
attendant convection warrant issuance of the High Wind Warning.
Confidence is highest along and east of the glacial ridge where most
favorable Ri values and strongest mean winds will be juxtaposed.
Post-fropa environment will be characterized by a slightly weaker
wind field, but far more favorable dynamic forcing. Once again,
confidence is high in meeting high-end advisory level winds through
at least 06z. Given existing HWW headline, simply extended it
through this period. Isolated wind gust reaching warning criteria
post-fropa not out of the question. Best chance north of M59.
Cold advection will drive temps into the 20s tonight. Persistent jet
over the great lakes will strengthen existing baroclinic zone as
another shortwave ejects out of the west. Gradient will respond by
turning southerly as the boundary wavers to the north. High temps
easily approach 40 on Wednesday. Isentropic ascent on the warm side
of the frontal zone will increase Wednesday afternoon into Wednesday
night. Surface-850mb layer fgen will favor a corridor of enhanced
precip rates, but attm vast majority appears to fall as rain.
Departure of the wave will force the front south...any lingering
precip falling as sleet/fzra across the far NW CWA late Wednesday
night. Similar scenario unfolds on Thursday, but nudged further
south. Higher chance for fzn precip, but QPF likely to remain on
the lower side.
A high pressure system pushing in from the Northern Central Plains
into the Great Lakes region Thursday into Friday will keep
conditions dry throughout the day on Friday, as winds remain light.
For the weekend, a stationary front will set up across the Ohio
Valley, which will keep the bulk of the precipitation south of
Michigan, however, overrunning along the front will bring the chance
light snow across the southern half of Michigan throughout Saturday
morning and afternoon. The better chance for precipitation will come
during the early part of next week as low pressure pushing from
Texas moves northeast into the Great Lakes region. Much like
yesterday, there are still large variations across the long range
models regarding the timing of the low. The GFS model pushes the low
over Michigan throughout Tuesday, while ECMWF model runs now push
the low over us by Wednesday. Both models still exhibit decent WAA
as above freezing 850 mb temperatures are ushered into the region.
As this potential event is still a week out, convergence between new
model runs will be needed to solidify timing and precipitation type.
The existing gusty conditions expected to steadily increase through
the evening, enhanced by developing cold air advection accompanying
a strong frontal passage. This will lead to an extended period of
high end gales across a large portion of Lake Huron. Potential for
gusts to approach storm force tonight, particularly from Saginaw Bay
into central Lake Huron. Rapid reduction in wind gust magnitude
then expected by the mid morning hours on Wednesday. Moderate
southerly flow throughout Wednesday, but with gust potential limited
by an increasingly warm and stable overlake environment. Winds turn
northwesterly by Thursday as a frontal boundary sags across the
region. This may provide a period of stronger winds by the end of
the week as colder works back in.
Issued at 946 AM EST Tue Jan 10 2017
Winter Weather Advisory will be expiring on schedule this morning as
ptype transition through sleet/fzra to rain is occuring on schedule.
Focus for this afternoon will be on wind potential. High Wind Watch
still looks good based on latest data. Surface low over Iowa is
progged to deepen at a rate of about 1mb/hr for the next 12 hours,
reaching 980mb just north of the straits. Wind field will be very
strong, with the NAM/RAP modeling nearly 90kts at 850mb. Common
ingredient often missing in potential high wind scenarios is dynamic
forcing. However, ARW/RAP/EC all indicating very strong isentropic
descent associated with incoming cold advection. Continue to shy
away from NAM/NMM due to terrible handling of the surface layer due
to snowpack and resultant erroneously high boundary layer stability.
High wind warning criteria of 50kts reasonably attainable within the
frontal zone itself followed by either warning or high-end advisory
thereafter. In addition, convective showers leading the front will
provide another mechanism by which warning criteria may be reached.
Plan to hang on to the high wind watch until aftn package.
MI...High Wind Warning until 4 AM EST Wednesday FOR MIZ047>049-053>055-
Lake Huron...Storm Warning until 7 AM EST Wednesday FOR LHZ363-421-422-441-462.
Gale Warning until 7 AM EST Wednesday FOR LHZ361-362-463-464.
Gale Warning until 4 AM EST Wednesday FOR LHZ442-443.
Lake St Clair...Gale Warning until 1 AM EST Wednesday FOR LCZ460.
Michigan waters of Lake Erie...Gale Warning until 1 AM EST Wednesday FOR LEZ444.
You can obtain your latest National Weather Service forecasts online
Area Forecast Discussion
National Weather Service Grand Rapids MI
922 PM EST Tue Jan 10 2017
Issued at 325 PM EST Tue Jan 10 2017
Very windy conditions will develop late this afternoon through
this evening which will likely result in scattered power outages.
Another low pressure system will bring a mix of rain snow and even
a little sleet and light freezing rain Wednesday afternoon through
Wednesday night into Thursday. Snow accumulations will be very
light. Tranquil weather will return Thursday night through Friday
as high pressure builds in.
Issued at 921 PM EST Tue Jan 10 2017
No real changes needed to the forecast for tonight. Wind advisory
is working out nicely with many locations seeing wind gusts up to
around 55 mph or so with the passage and immediately behind the
cold front. The cold front has moved through most of the area,
having just moved through Jackson just before 02z. We will hold on
to it at least for a couple of more hours with wind gusts still up
enough. We may be able to cancel it before midnight if winds come
Pcpn is holding on a bit behind the front, but is now in the
process of diminishing. We have seen some snow mixing in with
times, mainly near KGRR and areas west. The pcpn will diminish before
enough cold air comes in to produce any appreciable accumulations.
.SHORT TERM...(This evening through Thursday night)
Issued at 325 PM EST Tue Jan 10 2017
Primary short term fcst concerns involve determining how windy it
will become late this aftn/tonight and assessment of potential
for mixed pcpn Wednesday afternoon through midday Thursday.
Windy conditions will develop late this afternoon through tonight
as the 988 mb low near Madison WI continues to intensify and move
ne. A polling of 00Z/12Z bufkit wind profiles and mixing w/height
suggests wind gusts will reach 50 to 55 mph across our fcst area
this evening. Latest HRRR higher res wind gust fcst guidance
suggests highest gusts to around 45 kts will occur over our
southern fcst area around to shortly after 00Z this evening.
Based on all the aforementioned data we see this as a high end
wind advisory event and will run the wind advisory from 5 pm this
afternoon through 3 am Wednesday. It seems that the peak wind
gusts will already occur during the early to mid evening hours.
This will likely result in scattered power outages and some downed
tree limbs. Thx for extensive coord on headline decisions
In addition given that several locations across our northern fcst
area have already received 5 to near 6 inches of snow and that
some mixed pcpn is still being reported across our northern
counties we will leave the winter wx advisory unchanged and let it
run it`s course thru 7 pm for our northern two tiers. Even as
pcpn gradually transitions to liquid form hazardous travel
conditions will continue for several more hours up there.
The next low pressure system will cause mixed pcpn to develop
Wednesday afternoon. P-type will be rain near to south of I-96
and a mix of rain and wet snow is expected across our northern
Pcpn will continue Wednesday night and the rain/snow line will
slowly shift south overnight as thermal profiles slowly cool. A
brief period of sleet/very light freezing rain is also possible.
Pcpn will linger into Thursday before tapering off Thursday
afternoon. Any snow/sleet/fzra accums would be really light with
around an inch or less of snow mainly well north of I-96.
Tranquil wx will return late Thursday afternoon through Thursday
night as high pressure begins to build in from the northwest.
.LONG TERM...(Friday through Tuesday)
Issued at 325 PM EST Tue Jan 10 2017
Active weather pattern will continue into the weekend and
beyond...with mid level energy rotating across Canada and the Great
Lakes region and a closed low off developing off of the California
coast. The northern stream energy will be the primary driver of the
local weather...with a weaker impulse affecting the weather on
Saturday. The system off of the California coast will move east
over the weekend...and cause another precipitation event Monday and
Precipitation type will be the main concern in the extended portions
of the forecast. Cold high pressure will be in place Friday through
the weekend. The weak wave that will pass through on Saturday
should produce light snow...but the fast movement of the system and
limited moisture should reduce the impacts of this precipitation.
The event early next week may start as a wintry mix...but the
majority of the precipitation looks to be liquid for this event.
Friday will be the coldest day...with highs from the middle teens in
north central Michigan...to the middle 20s in the I-94 corridor.
Temperatures warm a few degrees each day...with highs on Tuesday in
the upper 30s to near 40 degrees. Lows will range from the single
digits in north central Michigan to the middle teens south on
Saturday morning...warming to around freezing for Tuesday morning.
Thanks to LOT/APX/DTX/IWX for coordination/collaboration this
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 650 PM EST Tue Jan 10 2017
Main impacts to aviation interests this evening are initially the
strong winds and MVFR conditions. The front is pressing through
the area, being just east of KGRR and near KAZO at 2345Z. This
front will likely bring a wind shift to the WSW and the highest
wind gusts to around 45-48 knots.
The rain will diminish an hour or two after the front moves
through with CIGS and VSBYS coming up. Can not rule out some
showers changing over to a little light snow before ending by
around 05z. Winds will then steadily diminish after about 02z or
We will see the CIGS go VFR around or just after 06z tonight, and
last through much of the day on Wed. Rain will move back in later
in the period with MVFR-IFR conditions likely returning by the
end of this fcst period.
Issued at 325 PM EST Tue Jan 10 2017
A gale warning is now in effect through 7 am Wednesday. Southerly
winds will continue to increase to 40 to 45 gales and veer to the
southwest and then west this evening. Gales will continue
Issued at 1147 AM EST Tue Jan 10 2017
Various ice jams on area rivers continue to be monitored. Warmer
temperatures, rainfall, and snow melt will combine to elevate
river levels for the remainder of the week. It is uncertain if
the ice jams will release given these circumstances. Typically we
need temperatures closer to 50 degrees for a few days to break
them up, if the ice is thick enough. Currently the jam downstream
of Robinson Township appears to be holding but the readings at
Robinson have been unchanged in the last 3 days, with stable ice
covering the river. Added flow behind the jam may back up river
levels if the jam doesn`t break up. A Flood Watch has been issued
given the uncertainty in how the river will respond over the next
few days, with the possibility that a rise above flood stage may
occur. Another jam on the Grand River has occurred near the Fish
Ladder at Grand Rapids, which is backing up flow a bit. Currently
this backwater has reached Comstock Park. No flooding is occurring
at this time though rises above bankfull may occur as rain and
snow melt add to the levels.
Other jams are likely occurring on the Flat River near Smyrna and
also the Looking Glass River near Eagle. Combined rainfall and
snow melt will add to these river stages and further rises above
bankfull are likely.
MI...Wind Advisory until 3 AM EST Wednesday for MIZ037>040-043>046-
LM...Gale Warning until 7 AM EST Wednesday for LMZ844>849.
Area Forecast Discussion
National Weather Service Wilmington NC
1045 PM EST Tue Jan 10 2017
A significant warming trend will begin on Wednesday. A back
door cold front will bring cooler weather for the weekend, with
a gradual warming trend for the beginning of next week.
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
As of 1000 PM Tuesday...Coastal trough and its associated light
rain will continue to slowly shift offshore overnight. A potent
mid-level shortwave will lift out across the mid west and into
the northeast by morning. Organized showers were weakening as
they crossed the Appalachians late this eve. Will add a very
small POP for a shower or two north of a BBP to LBT line toward
An extremely pronounced, but shallow surface inversion will
develop as milder and more moist air continues to feed into the
area atop cold ground. This is a very stable environment. The
first 300-600 ft of the column is completely saturated. Yet,
winds above the boundary layer do increase up to 20 to 30 kt
through the night. However, this is more of a case of advection
fog rather than radiational fog and we expect low stratus
stratus and fog to fill in. Will include patchy to areas of fog
across the Forecast Area overnight.
Temperatures reached their lows earlier and should fluctuate
through the night, increasing when the wind picks up and then
falling when the wind diminishes. Overall, the column is warming
overnight which will help to buoy temps. Certainly a drastic
change in airmass from just 12 hours ago as the Arctic air has
completely scoured out.
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/...
As of 230 PM Tuesday...Surface high ridging back from the
western Atlantic and building weak mid level ridge will be the
dominant features during the period. Low level southerly flow in
conjunction with increasing mid level subsidence will result in
temperatures above to well above climo through the period.
Exception will be high temps along the coast where onshore flow,
especially on Wed, will work to keep areas within a few miles
of the coast several degrees cooler. On Thu low level winds may
have more of a southwest component, keeping the Brunswick county
coast and southern New Hanover county coolest.
.LONG TERM /FRIDAY THROUGH TUESDAY/...
As of 230 PM Tuesday...A broad H/5 ridge will build across
eastern CONUS through much of the period, with a mid-level
trough moving in beginning late Monday/early Tuesday. At the
surface a back- door cold front will drop south across the
eastern Carolinas late on Friday with a wedge-style pattern
briefly developing in its wake. A Canadian high will pass to our
north late on Sunday with WAA from later Monday through Tuesday
preceding the arrival of the next system beyond the Long Term.
Unseasonably mild temperatures on Friday will give way to more
climatologically normal temperatures Saturday, with a gradually
warm-up Sunday through Monday as the airmass modifies. A more
pronounced warming is on tap for Monday night through Tuesday as
magnitude of WAA increases. There is the slight chance for
light rain late Friday into Saturday associated with FROPA/wedge
pattern set-up but in general the long term looks dry with only
ample cirrus moving overhead through the period.
.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
As of 23z...still feeling the affects of a weak coastal trough
spreading light rain mainly across KILM at times. Ceilings have
been up and down at KILM, KCRE and KMYR with passing waves of
precipitation and fog. HRRR has done a good job with the
precipitation and continues with on and off light rain across
KILM through about 04z. Will forecast mainly VFR with tempo MVFR
across the coastal terminals through 12Z. Will go down to IFR
across KFLO and KLBT in fog between 08z-12z. Confidence is
moderate in fog and ceilings through the period. After 12z-13z
conditions improve as ceilings and vsby lift to VFR all
terminals. Winds light and variable becoming SW then S during
the day on Wednesday under 10 kts.
Extended outlook...MVFR possible with showers Wednesday morning.
Otherwise expect VFR.
NEAR TERM /THROUGH TONIGHT/...
As of 1000 PM Tuesday...A coastal trough will be shunted to the
N and E overnight. South to southwest winds will develop as a
coastal trough lifts to the N and E overnight. The gradient
will relax slightly as the trough moves away. Wind speeds after
midnight will generally be 10 kt or less, but 10 to 15 kt across
the outer waters of North Carolina. Seas of 2 to 4 ft will
subside to 2 to 3 ft toward morning.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
As of 230 PM Tuesday...Surface high over the western Atlantic
will maintain southerly flow through the period. Gradient will
remain ill- defined with speeds generally 10 kt or less. Light
winds will keep seas 2 to 3 ft through the period.
LONG TERM /FRIDAY THROUGH SUNDAY/...
As of 230 PM Tuesday...A cold front will drop south across the
waters late on Friday, followed by a coastal trough briefly
developing on Saturday. High pressure will move north of the
waters late on Sunday. A relatively slack gradient through the
long term means winds should not exceed the 10 to 15 kt range,
with seas of around 2 or 3 ft. No headlines or advisories
expected during this period.
AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
1030 PM EST Tue Jan 10 2017
Issued at 1030 PM EST TUE JAN 10 2017
Went ahead and extended the Wind Advisory through 2 am est for the
entire area based on upstream winds and convection developing. It
looks like the strongest wind gusts will be pulled down by the
showers as they pass. Updated the PoPs and Wx grids to reflect the
latest radar trends and the most recent HRRR data. Matched up the
highest PoPs with the highest wind gusts as the main threat timing
the highest winds across the area through the early morning
hours. Also fine tuned the T and Td grids to account for the
current obs and trends. The updated grid package has been sent to
the NDFD and web servers. Also, issued updated NPW, HWO, and ZFP
with this issuance.
UPDATE Issued at 730 PM EST TUE JAN 10 2017
00z sfc analysis shows a tight pressure gradient over the area
from a deep low pressure center moving through the Great Lakes and
high pressure along the East Coast. This is prompting south to
southwest wind gusts of 30 to 40 mph across eastern Kentucky -
mainly on the ridges - with even higher speeds possible in the
most elevated terrain near the Virginia border. For all this, a
Wind Advisory is in effect through 10 pm est for the entire JKL
CWA. Look for the winds to settle down a bit later in the evening
and continue to diminish through the rest of the night. A band of
light to moderate showers will continue to press east through the
area this evening before stalling and allowing the showers/stray
thunderstorms associated with the actual cold front to catch up
and overtake eastern Kentucky. Have continued the slight chance
of thunder into the overnight hours from this. For temperatures -
readings are rather mild throughout the area - running in the
upper 40s to lower 50s while dewpoints are generally in the mid to
upper 30s east and upper 30s to lower 40s west. Have updated the
grids to reflect the latest timing on the showers and stray
thunderstorms, as well, as adjusting the near term T and Td grids
per the latest obs and trends. These grids have been sent to the
NDFD and web servers.
.SHORT TERM...(This evening through Wednesday night)
Issued at 322 PM EST TUE JAN 10 2017
The afternoon surface analysis shows a surface low continuing to
deepen, as it continues to eject into the western Great Lakes.
Meanwhile a cold front resides along the Central and Southern
Mississippi River Valley with thunderstorms forming across
Southern IL and SE MO. Ahead of the cold front is a strong LLJ at
the 850 and 925mb levels in a area of tightening pressure
gradient. This will keep the region gusty through the evening
hours till the core of the LLJ moves NE of the region. Most the
short term guidance has this happening about around 03Z and
therefore will keep the NPW going at this stage of the game. The
precip ahead of the cold front still looks to be related to the
strong LLJ pulling moisture into the region in a more top down
saturation scenario. This line of showers and perhaps a
thunderstorm will progress across the region this evening through
tonight, with again overall good agreement with the latest short
term models. It is possible the second line developing across
IL/MO catches up to the downstream line we are seeing in west and
central KY. Given the chance of seeing measurable precip went
definite POPs and only slight on the Thunder. The reason for that
is the models are struggling to show much if any elevated
instability, but the strong jet alone could lead to a few rubbles.
That said, kept the slight thunder going this evening into
This boundary that comes through this evening will hang up across
the Tennessee Valley tonight into early Wednesday. The actual cold
front slows and only makes it just SE of the Ohio River by
Wednesday morning. Therefore POPs become more difficult to nail
down, but this should all lift north by Wednesday Afternoon ahead
of next lee side low. The question is will this lead to any
thunder at all and right now leaning away from that. Just not sure
we will see enough instability and SPC keeps the general thunder
west of the region as well. The POPs will wane through the
evening, as boundary moves north of the region. Matter of fact the
SE portions of the CWA could very well dry out before wavering
baroclinic zone moves slightly closer to the region. There is
still some uncertainty how much if any POPs would be seen given
the placement of the better lift. Therefore blended POPs will be
fine in the slight to chance CAT at this point.
.LONG TERM...(Thursday through Tuesday)
Issued at 416 PM EST TUE JAN 10 2017
An unsettled and overall warm period will be in store from late week
into next week. A split flow pattern will be in place with cyclonic
flow migrating through eastern Canada and the northern United
States, while an upper level low digs across California toward Baja.
An upper high parked across Florida and the southeast portion of
the country looks to keep the heaviest rainfall axis northwest of
much of eastern Kentucky, likely lining up somewhere near the Ohio
River Valley. However, positioning of this axis remains variable
given several passing disturbances and lingering subsequent
Surface low pressure sliding northeast out of the Missouri Valley
into the Great Lakes Thursday may allow for a few showers locally in
the warm sector, prior to an upper low plowing through Ontario and
sending a cold front into eastern Kentucky Thursday evening/night.
This will bring a better chance for rain showers through Friday as
the front hangs up across the region downstream of another wave
migrating northeast of the Baja cutoff low. Following anomalous
warmth with high temperatures in the mid 60s Thursday, a cooldown
will be in store for Friday behind the front with highs topping out
in the low-mid 40s for most locales with low-mid 50s south of Hal
Rogers Parkway/Highway 80.
A warm front will then lift through the Tennessee Valley and eastern
Kentucky Friday evening and night on increasing west/southwest flow.
This will lead to another widespread round of rainfall as opposed to
any mix with freezing rain as a substantial warm nose develops.
Still expecting surface temperatures to mostly remain above freezing
as well given surface ridging sliding eastward across the Great
Lakes, therefore keeping the brunt of the cold dome north of eastern
Kentucky. Warm air/moisture advection should quickly bring
temperatures back above freezing in the northern Bluegrass region
Friday night if they do indeed drop below freezing beforehand.
Rain chances will continue through the weekend into next week as
passing northern stream energy combines with the previous cutoff low
finally tracking northeast. Well above normal temperatures will
continue, until a cold front pushes through sometime early-mid next
week pending evolution/movement of the looming upper low.
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
ISSUED AT 645 PM EST TUE JAN 10 2017
VFR conditions are holding on over eastern Kentucky early this
evening, however an MVFR deck resides just to the west and is
approaching. This will move into the Bluegrass and Lake
Cumberland regions early this evening from forcing ahead of an
cold front that remains further out to the west. This is all
leading to a tight pressure gradient along with a strong LLJ in
place across the region. Therefore, winds will be gusty through
the early evening at most sites. The highest gusts will generally
be at LOZ/SME/SYM with lesser ones expected to the east. Winds are
expected to peak at 25 to 30 knots at least with locally higher
values possible for the next several hours. These winds are
expected to lessen through the rest of the evening. Then they will
remain out of the south and southwest through the TAF period even
as they diminish. Showers will progress deeper into the area
through the rest of the evening from west to east. Will also keep
a mention of thunder in the TAFs for the late evening and most of
the overnight hours. MVFR conditions and continued chances of rain
then last into the day Wednesday.
Wind Advisory until 2 AM EST Wednesday for KYZ044-050>052-
Area Forecast Discussion
National Weather Service Louisville KY
852 PM EST Tue Jan 10 2017
Issued at 854 PM EST Tue Jan 10 2017
A couple lines of thunder showers have tracked across central KY and
southern IN this evening. Wind gusts ahead of these lines (gradient
winds) and within the thunder showers have ranged from 35 to 45 mph,
with some isolated reports of near 50 mph. Not expecting severe wind
gusts with the activity across southeast Indiana.
HRRR model doing a reasonable job showing these lines quickly
marching east/southeast over the next 1 to 3 hours, giving way to
mostly dry conditions across the area after midnight. Have updated
the precip chances in the near term.
Still think the wind gusts will relax under 40 mph by 10 PM EST to
let the Wind Advisory expire as planned. May need to issue a SPS to
cover 30 to 35 mph winds for portions of the area.
Issued at 610 PM EST Tue Jan 10 2017
Still observing 35 to 40 mph wind gusts ahead of the line of showers
across the area, and hi-res and near-term model guidance still
points to occasional 40 mph gusts through mid-evening. Decided to
extend the advisory for areas along/east of I-65 which stand the
highest chances of seeing these 40 mph gusts into the mid-evening
Otherwise, made adjustments to the POPs in the near term and some
minor adjustments to temperatures. The forecast remains on track.
.Short Term (Now through Wednesday Night)...
Issued at 250 PM EST Tue Jan 10 2017
A low pressure system over Wisconsin this afternoon will continue to
track off to the northeast tonight. A cold front will sink through
the region tonight. This front will then quickly push back to the
north Wednesday as a warm front.
For the remainder of the afternoon showers will be on the increase
as the front approaches. Soundings do continue to indicate there
will be a bit of instability develop tonight between 0-6Z, so will
continue to mention a slight chance for thunderstorms. After 06Z the
instability wanes as the front pushes through. Showers will end from
north to south tonight as well as the front pushes south. Most areas
should see a dry period early Wednesday before the front starts
moving back northward. A few thunderstorms will be possible once
again Wednesday. Showers will once again decrease tomorrow night as
the warm front moves north of the area.
Gusty winds will continue this afternoon. Sustained winds have been
in the 25-30 mph range with gusts generally 40-45 mph. However, a
few locations have seen gusts up to 50 mph and this may continue
over the next couple of hours. The Wind Advisory expiration time
still looks good as gusts should be decreasing by then. Winds should
become relatively calm at the surface behind the front tonight, but
winds aloft look to stay up. This should keep the atmosphere mixy
enough to keep much fog from developing. Winds will once again be on
the increase Wednesday night as the pressure gradient tightens up
again ahead of the next front.
.Long Term (Thursday through Tuesday)...
Issued at 303 PM EST Tue Jan 10 2017
Thursday - Saturday...
Another cold front will slowly work its way south across the lower
Ohio Valley Thursday afternoon into the overnight hours. It will
then stall out and become quasi-stationary near the KY-TN border
through Friday and Friday night before lifting back to the north on
Winds for Thursday will once again be gusty ahead of the front
passing through. Showers will develop again ahead of the front and
continue off and on as it sinks southward. The concern through this
time frame will be the potential for any freezing rain as the cold
air behind the front tries to undercut the warm air aloft. The
latest model runs suggest there could be a few hours of freezing
rain on Friday morning before temperatures warm back up above
freezing. There will then be another potential window for freezing
rain on Saturday morning. For both of these days, the best chance
for freezing rain will along and north of the I-64 corridor. South
of this area, temps should remain warm enough that freezing rain
will not be a concern. The good news is temperatures on Saturday
should warm into the low 40s across southern IN and mid 50s across
south central KY, so any impacts from the wintry precipitation
Sunday - Tuesday...
The boundary will remain in the vicinity through the end of the
weekend with rounds of showers possible. It then may pull far
enough north we could get a break in the rain for a period before a
low pressure system ejecting out of the southwest moves through late
Monday or Tuesday. Temperatures will be warming again into early
next week with highs back into the 60s on Monday.
.Aviation (00Z TAF Update)...
Updated at 610 PM EST Tue Jan 10 2017
Plan on gusty winds 30-35 kts through mid evening as the pressure
gradient ahead of the cold front remains very tight. A line of
showers will approach central Kentucky between 00-03z. There`s a
slight chance of a rumble of thunder, but not enough confidence to
include in the TAF right now.
That front will orient itself more east/west and hang up around
southern KY tonight. Moisture pooling and lighter winds will bring
IFR ceilings to BWG around daybreak, meanwhile clouds could scatter
out completely at SDF and possibly LEX. If so, then there`s a chance
of light fog but winds just off the surface look to be strong enough
to prevent any restrictions there.
That stationary front will gradually lift back north tomorrow as a
warm front, and with it there`s a high chance of IFR to fuel
alternate ceilings with it across all of central Kentucky.
Additionally, there should be some showers along the front as well.
South to southwest winds will become gusty again in the
afternoon, in the 20 to 25 kt range.
KY...Wind Advisory until 10 PM EST /9 PM CST/ this evening for
IN...Wind Advisory until 10 PM EST this evening for INZ078-079-091-
Area Forecast Discussion
National Weather Service Medford OR
250 PM PST Tue Jan 10 2017
.DISCUSSION...The latest visible image shows a dry slot moving
towards southwest Oregon. This has put an end to steady heavy
precipitation and we may catch a brief break in the weather for many
westside valleys early this evening. However radar returns are
showing precipitation becoming convective in nature and I still
could not rule out moderate to heavy showers along the Coast Range
into this evening. The RAP is handling this well and actually shows
precipitation decreasing in coverage area this evening and tonight
and keeps it mainly confined to the south Coast Range. Meanwhile
it`s still windy along the coast south of Cape Blanco, but they have
been decreasing over the last few hours and the end time of the high
wind warning looks good, thus we`ll allow that to expire.
The models are in pretty good agreement with precipitation rates
gradually decreasing tonight. The exception will be along the
Cascades where a moist onshore flow will allow showers to persist
there. Snow levels will be at their highest early this evening
(between 5000-5500 feet), then lowering later this evening and
tonight. Therefore areas along and east of the Cascades that have
seen a changeover from snow to rain will probably see a changeover
back to snow. Because of the above mentioned reasoning, have decided
to extend the end time of the winter storm warning for the Cascades
and winter storm warnings and advisories for northern Klamath
County. See WSWMFR for more details.
Right now were not expecting accumulating snow for the passes north
of Grants Pass tonight. Could not rule out occasional snow showers,
but most should be light.
An upper low will move overhead on Wednesday with scattered showers
and snow levels near 2500 feet. However most showers should be
light, thus limiting the impact on the roads. -Petrucelli
.LONG TERM...Thursday through Tuesday...The upper trough
responsible for all the unsettled weather earlier this week will
finally push south of the area on Thursday allowing drier air
to move in from the north. This will give SW Oregon and northern
California a much-needed break from the onslaught of
precipitation. Any snow showers/flurries around Thursday morning
across the south and east should end by midday yielding to at least
partial sunshine for most of the area. However, with colder air
moving in, any remaining snow/slush/moisture left on roads will
re-freeze, so beware of black ice Thursday morning. Overall, expect
highs Thursday to be about 10 degrees below normal with the highest
anomalies east of the Cascades. The good news is that water levels
on area streams, creeks and rivers should also continue to recede.
With high pressure in control, Thursday night will be frigid east
of the Cascades and cold over the west side. Lows will be 5 degrees
below to 5 degrees above zero over the east side with 20s in the
valleys west of the Cascades. Frost/freeze headlines are likely
again along the coast. Some low clouds and freezing fog are also
possible in the valleys, especially the west side late Thursday night
and into Friday morning.
Models have come into line with respect to a weak upper trough
crossing the region Friday night into Saturday morning. It appears
there won`t be enough moisture associated with this system to
produce much more than some cloud-cover during this period, so we
have continued the dry forecast and removed all mention of
precipitation. Fog and low clouds will still likely be an issue for
the west side valleys.
Saturday night to Monday next week, models are showing short wave
disturbances moving mostly to our north with a ridge axis extending
from California to the Great Basin and the northern Rockies. This
will bring a chance of rain to the coast and Umpqua at times, but no
big storms are expected (yet). However, this will change next week
and the door will open for a strong Pacific jet to extend all the way
to the West Coast beginning next Tuesday. A lot can change between
now and then, but this scenario may lead to our next atmospheric
river event with a return of wet, windy weather, higher snow levels
and a renewed threat of flooding. -Spilde
.AVIATION...0/18Z TAF CYCLE...From the Cascades west...Widespread
MVFR/IFR cigs/vis with terrain obscured today with periods of
moderate to heavy rain and snow. The heavier precipitation will
become more showery overnight into Wednesday, but the lower
conditions will persist. Snow levels up near 5000 feet through this
evening will lower down to 2000 feet by Wednesday morning.
East of the Cascades....Areas of MVFR cigs/vis in light to
moderate snow with mountains obscured. Snow will change to rain
below 5000 feet this afternoon. South winds will increase in the
afternoon and KLMT could see wind gusts to near 30 knots. -Spilde
.MARINE...Updated 209 PM PST Tuesday 10 January 2017...Strong low
pressure is moving into the waters this afternoon and will make
landfall near Cape Blanco late this evening. South gales will
continue to the south of the low with shifting but less intense
winds to the north of the low. Just behind this low is what we call
the bent-back occlusion, which is sometimes associated with a brief
burst of strong winds. Strong winds do not always occur with bent-
back occlusions, but this feature will track across the northern
waters just behind the surface low, so we`ll keep a close eye on
that. Even though gales are currently confined to the southern
waters, mariners should not let down their guard over the northern
waters this evening. Seas will remain hazardous from a combination
of wind waves and swell through this evening, and then into
Wednesday mostly from short period fresh swell.
Seas will diminish tomorrow night, then we`ll enter of a period of
relatively calmer weather with lighter north winds and subdued seas
from Thursday into the weekend. -Wright
OR...Winter Weather Advisory until 10 AM PST Wednesday for
Winter Storm Warning until 10 AM PST Wednesday for ORZ029>031.
Winter Storm Warning until 10 AM PST Wednesday ABOVE 3000 FEET
for for ORZ025-027-028.
High Wind Warning until 3 PM PST this afternoon for ORZ022.
Wind Advisory until 7 PM PST this evening for ORZ026.
CA...Winter Weather Advisory until 10 AM PST Wednesday for
Winter Storm Warning until 10 AM PST Wednesday for CAZ084-085.
Winter Storm Warning until 10 PM PST this evening ABOVE 4000
FEET for for CAZ082-083.
High Wind Warning until 10 PM PST this evening for CAZ081.
Wind Advisory until 10 PM PST this evening for CAZ081.
Pacific Coastal Waters...Gale Warning until 8 PM PST this evening for PZZ356-376.
Hazardous Seas Warning until 10 PM PST Wednesday for
Area Forecast Discussion
National Weather Service Charleston WV
948 PM EST Tue Jan 10 2017
Weak cold front washes out as it arrives tonight. A new warm
front pushes north on Tuesday. A cold front crosses Thursday
night, but stalls nearby this weekend.
.NEAR TERM /THROUGH WEDNESDAY/...
As of 945 PM Tuesday...
Issued a wind advisory for western half of the CWA. Current obs
over western OH ranging from 45 to 60 mph. These should decrease
some, but with a bit of convective enhancement still expect some
gusts of 45-50 mph will be possible. There is some thunder with
the western line now, but it has been decreasing...a trend that is
expected to continue, so did not add thunder to weather. Suppose
an isolated rumble may be possible across northwest CWA.
As of 640 PM Tuesday...
Updated forecast, mainly based on recent runs of the HRRR and RAP.
Those two were the closest on current temps and rain location.
This blend resulted in a bit warmer temperatures across the
northern mountains tonight, there still looks like a brief window
of possible freezing rain, but have reduced ice accretion to only
a few hundredths of an inch. That would come from this first band
of precip that is approaching the Ohio River now. The secondary
area -- moving into western Ohio now -- should be all rain as it
moves across the forecast area. Initially have some separation
between these two area, but think the second area will catch up
As of 200 PM Tuesday...
The thaw began this morning and looks to carry on for the
foreseeable future. That doesn`t mean we cannot get wintry precip
from time to time, and tonight is one of those times for
Pocahontas County. A s/w trof and associated cold front will move
through tonight with the boundary becoming frontolytic as it does
so. As such rain will work back into the region this evening from
west to east. There is enough lingering cold air at the surface
across the Greenbrier Valley for a period of freezing rain this
evening. QPF amounts to near two tenths are progged by most of the short
term models. Most of this would fall as freezing rain across that
location. Even if temps do climb above freezing /33 to 34/ at the
height of the precipitation, ice accretion is still likely given
the very cold ground. After coordinating with neighboring offices,
have hoisted a freezing rain advisory for one to two tenths of ice
accretion. I have also included the high elevation zone of
Pocahontas County as model soundings suggest a brief period of
freezing rain there as well despite being very close to the warm
nose. This should be a relatively short duration event centered in
the 8 to midnight time frame. Elsewhere, temperatures will be well
above normal tonight.
Winds will continue to pick up into early this evening as a stout
low level jet remains in the vicinity. Still do not foresee
criteria gusts at most locations given the WAA upglide nature,
but the highest ridges in the mountains could see some gusts to 45
Mid level drying quickly works in behind this system late tonight,
but with abundant low level moisture in place and a slackening
boundary layer flow, think low stratus will be the rule into the
first half of Wednesday. After which, a developing warm front to
the south will move north in the afternoon, reintroducing showers
to the area. It will remain warm though, with many places soaring
well into the 50s, if not touching 60 in a few locales.
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
As of 230 PM Tuesday...
Models are in agreement with strong H850 southwesterly flow, 50-60
knots, Wednesday and early Thursday to bring warm air advection for
temperatures to climb into the mid 60s lowlands. Wind gusts up to 30
knots can be expected over higher elevations. A warm front will lift
north under southwest flow bringing rain showers likely. A cold
front brings another batch of showers Thursday night into Friday
morning. The front stalls south of the area keeping chances for rain
showers. Horizontal flow at H500 brings a series of short waves
Saturday to keep unsettled conditions.
Colder air mass moves behind the cold front for temperatures
slightly above normal. Freezing temperatures will return Friday
night mainly across the northern half of the area.
Colder low level air may result in mixed wintry precipitation,
including freezing rain, in the middle Ohio valley and the northern
tier of the forecast area Friday night, and perhaps down the eastern
slopes of the northern WV mountains by Saturday morning, as the cold
air damming wedge develops.
.LONG TERM /SATURDAY THROUGH TUESDAY/...
As of 230 PM Tuesday...
Front will oscillate north to south this weekend. Moisture is
limited with this front providing light rain showers. The front
pushes north as a warm front Sunday night and Monday, as upper level
ridging builds. This may bring a break in the chance for showers.
Another cold front approaches Monday night, with the chance for
showers, as the upper ridge moves east of the area. An upper level
short wave trough then pushes the front through on Tuesday.
This should bring an end to any rain showers from west to east.
The GFS is the model of choice, opting out of the colder, drier
solution for late in the weekend depicted by the ECMWF, that
then evolves into timing differences early next week.
Temperatures are closest to GFS based guidance, fluctuating but
above normal through the period.
.AVIATION /03Z WEDNESDAY THROUGH SUNDAY/...
As of 945 PM Tuesday...
A quick moving cold front moves through tonight with showers.
Models pretty insistent on only isolated MVFR visibilities with
these, so kept things mainly VFR visibility. Did bring in some
MVFR ceilings overnight. Some question whether fog will form in
the Ohio River Valley by dawn. Some models show this area clearing
out with fog formation. Did include some MVFR, but low confidence
on this -- could even be LIFR. Alternatively, clouds could hang
tough and may lower to IFR levels.
Should see mainly VFR Wednesday, but do have some showers as a
warm front lifts through...which could contain MVFR.
Gusty southerly winds expected into tonight -- could get some
gusts of 35-45 kts, then decreasing and becoming westerly by
Wednesday morning. As warm front lifts through, winds should turn
back to southerly.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z THURSDAY...
FORECAST CONFIDENCE: Medium.
ALTERNATE SCENARIOS: Timing of showers may vary, and could need
amendment for MVFR visibility. Low stratus and/or dense fog
possible across western half of CWA overnight.
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.
DATE WED 01/11/17
UTC 1HRLY 03 04 05 06 07 08 09 10 11 12 13 14
EST 1HRLY 22 23 00 01 02 03 04 05 06 07 08 09
CRW CONSISTENCY H H M H L H M L M M M M
HTS CONSISTENCY M M M L M M M M M M L L
BKW CONSISTENCY H H L H H M M M H H M L
EKN CONSISTENCY M M L L L M M M H M H M
PKB CONSISTENCY M H M H H H H H M M H L
CKB CONSISTENCY M M M M M H M M M H M L
AFTER 00Z THURSDAY...
IFR possible in low cigs and rain late Wednesday through
WV...Freezing Rain Advisory until 1 AM EST Wednesday for WVZ523-524.
Wind Advisory until 4 AM EST Wednesday for WVZ005>010-013>017-
OH...Wind Advisory until 4 AM EST Wednesday for OHZ066-067-075-076-
KY...Wind Advisory until 4 AM EST Wednesday for KYZ101>103-105.
Area Forecast Discussion
National Weather Service Blacksburg VA
919 PM EST Tue Jan 10 2017
Low pressure will deepen and move northeast into the Great Lakes
tonight as high pressure moves off the southeast coast. A warm front
will lift north across the region tonight into Wednesday. Another
low will form in the Rockies on Wednesday which will track northeast
through Thursday resulting in milder temperatures and
occasional rain for our area through the end of the week.
.NEAR TERM /THROUGH WEDNESDAY/...
As of 911 PM EST Tuesday...
Sent an update to further slow down the onset of precip across
the west given very dry air between the surface and 700 mb seen
off evening soundings and current dewpoints in the teens to low
20s. Appears will take the second band of showers now nearing
the Ohio River to moisten things up enough for rain to reach the
surface per latest HRRR/RAP. However this may be as surface
temps are rising enough to preclude much icing except for the
deeper valleys across the north. Latest models still show the
potential for some spotty/brief icing across the far north and
even along the southern Blue Ridge so keeping the headline going
despite lack of precip attm. Other issue is with strong
southwest winds now mixing down across the western ridges as the
850 mb jet ahead of the front looks to max out at 50-60 kts
through midnight. Therefore upped gusts to just below advisory
levels for a few hours before the combination of the weakening
jet and arrival of deeper moisture should aid in less mixing to
below the inversion. Temps remain cold enough and even below
freezing in some of the valleys to aid spotty icing given the
cold ground and future wet bulbing. Thus lowered in spots to
start before going with a non diurnal rise espcly after
Previous discussion as of 657 PM EST Tuesday...
Freezing rain advisory for light ice accretion and slippery
road/sidewalks for eastern Greenbrier County in West Virginia
and most of our northern tier of Virginia counties remains
valid. However with this update I did opt to make a few changes
to PoPs/Wx and hourly T`s, as well as a rather short-lived (over
next 3-5 hrs) reduction in dewpoints.
Lingering CAD/ridge continues to impart a cool and dry thermal
and moisture profile early this evening, with temperatures
hovering mainly in the mid/upper 30s with dewpoints largely in
the teens. Accordingly, 2-m wet-bulb temperatures are all below
freezing. These conditions precede strong pre-frontal warm
advection regime with composite radar revealing a solid line of
showers along a cold front now extending into eastern KY and OH.
This is currently well-handled by preponderance of CAM model
output; however, only the HRRR shows any appreciable eastward
advance along/east of the Blue Ridge overnight. So I`ve
increased PoPs for areas west of the Blue Ridge toward the
Likely/Categorical range but reduced them to some extent east.
Dewpoints do stand to surge from south to north particularly
late evening/midnight as low- level flow veers to
south/southeast and taps into higher moisture airmass now
developing over the Carolinas (Td`s observed in the mid 20s-
30s). In the near-term, however, anticipate there being some
wet-bulb cooling by a couple degrees before temperatures
steadily rise on/after midnight. While temperatures as
precipitation begins elsewhere should be mild enough for rain,
it sets the stage for areas of light freezing rain along our
northern counties. Timing of cessation of freezing rain around 1
am still appears reasonable. Still don`t feel amounts will be
anything more than a few hundreths but that is all it can take
to cause travel problems. Lows tonight should occur rather early
in the 30s before steadily rising overnight.
Previous near-term discussion issued at 332 PM follows...
Posted a freezing rain advisory across the north this evening until
1 AM Wednesday morning.
High pressure will slide east into the Atlantic ocean tonight into
Wednesday. A southwest flow on the backside of the high will push
warm air into our region. Used a non-diurnal temperature trend
tonight. As precipitation begins...there may be a brief period when
evaporative cooling as the air mass saturated lowers temperatures
but the overall trend will be steady or rising tonight into
Highres models like the HRRR and Hiresw-arw East showed the arrival
of precipitation this evening between 23Z/6PM and 03Z/10PM. There is
still enough cold air at the onset of the precipitation for freezing
rain for northern portions of forecast area including the Alleghany
Highlands, Greenbrier County, Rockbridge and Amherst counties. If
the model temperature profiles are correct, by 1 or 2 AM
temperatures across the area will be above freezing mark. Rain will
spread southeast and continue for the rest of tonight into Wednesday
morning. Any ice accumulations will be less than a tenth of an inch.
Expect areas of fog tonight where dew points rise above freezing
over the snow cover.
On Wednesday, the upper level pattern will transition to a split
flow regime with a closed low sinking over the Baja peninsula and
weak southern stream ridging over the southeast. This will keep the
Appalachians in a warm and moist southwesterly flow aloft. The warm
front will continue traveling north resulting in clouds and chance
of rain. Temperatures will be quite tricky as precipitation and
lingering snow cover will want to lock in some cool in-situ wedging
as thickness values surge. High temperatures should vary from around
40 degrees in the colder locations to the lower 50s in the southwest
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
AS OF 330 PM EST Tuesday...
Noticeably milder as we head through this period with southwest flow
aloft and increasing heights. However, will see less sunshine and
some rain at times. One batch will be moving across and out of the
forecast area Wed night, as piece of energy and low level jet move
across the Central Appalachians. Best chance will be north of I-64
with less in the southeast.
Thursday will be mainly dry through frontal boundary will be
situated from Lake Erie, southwest to the southern Plains Thursday
morning and should approach the Central Appalachians by Thursday
evening. Will advertise low chance pops WV to slight chance as far
east as I-81.
Not changing much into Friday with threat of showers increasing late
Thu night into Friday with front pushing southeast to the Carolinas.
Models overall showing best lift/forcing splitting with deeper
moisture swing south into the TN valley and dynamics racing north
toward New England. May be a case where the WV mountains to NC
mountains will have the higher threat of showers while the southeast
maintains low chance.
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
.AS OF 320 PM EST Tuesday...
Expect this period to stay milder than normal though strong high
moving across New England Saturday will keep it cool/damp, with sfc
front/low situated from the KY/TN area southwest to Texas. This
frontal boundary will stay in the vicinity of our area into Monday
then lift northward as a warm front into the Northeast by Tuesday as
strong upper low pushes east and north into the Plains. The
southwest flow aloft will keep the moisture streaming in and will
see temps about 10-20 degrees above normal early next week.
.AVIATION /02Z WEDNESDAY THROUGH SUNDAY/...
As of 657 PM EST Tuesday...
VFR conditions through the next 3 hrs with developing low-
level wind shear as southwesterly winds increase to near 45 kts.
Flight categories then start to deteriorate, with a gradual
VFR/MVFR as frontal boundary lowers ceilings and brings light
rain especially western TAFs. Potential for slick runways at LWB
due to initial freezing rain. As dewpoints begin to climb to
values above freezing over at least a light cold snowpack,
potential for MVFR fog to develop over the snow is possible and
feel the best chance at this would be at DAN. South winds 6-11 kts
should predominate with gusts to 25 kts at BLF through
Precipitation into early Wednesday may prove spotty at best.
However as southern end of frontal boundary sags southward but
still hangs around by late in the day Wednesday ceilings will
begin to lower to an eventual IFR/LIFR. South winds on Wednesday
4-8 kts eventually become light and variable by late Wednesday
Extended Aviation Discussion...
Moisture returns back north Wednesday night ahead of a stronger
frontal system and associated low pressure to the west. This
likely to maintain areas of sub-VFR within lower cigs and patchy
rain showers Wednesday evening into Wednesday night before
seeing improvement back to VFR on Thursday ahead of the next
This second frontal system will work its way into the region
Friday into Saturday, maintaining the threat for additional sub-
VFR in low cigs along with light rain and/or drizzle. Unsettled
weather will continue into early next week.
VA...Freezing Rain Advisory until 1 AM EST Wednesday for VAZ019-020-
WV...Freezing Rain Advisory until 1 AM EST Wednesday for WVZ507.