Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/07/19
AREA FORECAST DISCUSSION
National Weather Service Binghamton NY
920 PM EST Wed Mar 6 2019
.SYNOPSIS...
Unseasonably cold weather with lake effect snow continues into
Thursday. The heavier snow will be confined to areas southeast
of Lake Ontario, including the Syracuse and Rome areas. Across
the southern tier of New York and northeast Pennsylvania it will
be partly cloudy with scattered snow showers or flurries around.
Not as cold Friday with a period of light snow moving across
northeast Pennsylvania. Warming trend for the weekend with a
wintry mix changing to rain Saturday night and Sunday.
&&
.NEAR TERM /THROUGH THURSDAY NIGHT/...
915 PM Update...The current forecast is generally on track as
the dominant LES band has lifted nearly out of Northern Oneida
county at this time. However, this trend does not equate to an
easy update. Winter warnings and an advisory continue in our
northern zones with essentially nothing going on. Satellite,
radar trends and hi-rez models do indicate signs of the LES
band dropping back south through Oneida...setting up again
across northern Onondaga and Madison within the next 6 hours.
Timing discrepancies are apparent with NAMnest faster than HRRR
by a couple hours. There looks to be some low confidence as the
situation evolves during the 03Z-06Z period, but then an
anticyclonic curved plume on a 280-290 vector becomes more
likely as the night wears on. Disruption in the flow due to the
effects of what looks like a hybrid synoptic and lake induced
thermal low pressure area will begin to disrupt the plume again
after 12Z.
Although I`ve been tempted to throttle back on the winter
headlines, the snow-liquid ratios are still quite high and the
LES plume will still work in a favorable instability environment
tonight to generate significant hourly snowfall rates at times.
I can`t say one area will see an additional warning level of
snow accumulation with any confidence, but at this point, it`s
best not to monkey around too much with the message as this band
lurks around out there. Will make attempts to edit the text
products to fine tune the band evolution, but it may take some
time to get back along the Thruway and metro Syracuse.
Elsewhere...minor short wave aloft will bring broad synoptic
lift and mid-level moisture into the rest of the region
overnight. Forecast increases clouds, which stops the
temperature free fall, and some scattered areas of snow from
late tonight into Thursday morning. Little to no accumulation is
expected from this feature outside the lake bands.
Previous discussion...
Thursday: Lake effect snow continues in the morning hours,
tapering to snow showers in the afternoon. The flow will be more
northwesterly, around 310-320 degrees. Very cold still with
850mb temperatures still -15 to -18C. This equates to daytime
highs in the lower to mid-20s. Additional light snow amounts of
1 to 2 inches will be possible through the day across north-
central NY, with little or snow accumulations form the Twin Tier
south. Winds turn northwest and increase 8-15 mph in the
afternoon with a few higher gusts.
Thursday night: Generally quiet but cold weather as a surface
high pressure center builds over the region. Could still have
some lingering lake effect off the east end of Lake Ontario
across far northern Onondaga and Oneida counties. Perhaps an
additional localized 1-2 inches of fluffy, dry snow up here.
Otherwise dry, under mostly clear skies for most of central NY
and all of NE PA. Winds become light and variable overnight with
lows in the single digits.
&&
.SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/...
A weak area of low pressure will track across the Mid-Atlantic
with an inverted trough extending northward into NE PA. Enough
moisture and lift will be present with these features to form
an area of light snow that moves through in the afternoon and
evening hours Friday. Right now, a fairly good modeling
consensus is in place that this snow will be confined to NE PA
and the Southern Tier of NY. QPF looks rather meager as well but
with ratios of 15-20:1 some spots in NE PA could get an inch or
so of snowfall. Highs should get back into the 30`s with
southern areas a touch cooler than blended model guidance due
to clouds and precipitation. While northern areas will likely
be a touch warmer given less cloud cover.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
Saturday: High pressure will temporarily build southward into the
region for a time. This looks to be a decent shot at at least some
sunshine. As a result, temperatures should creep upward to around 40
in the day after starting out in the teens. Low temperatures
Saturday morning are slightly lower than blended model and ensemble
guidance given the potential for clear skies, light winds and
residual snow cover.
Saturday night through Sunday night:
Our next storm system will take a very familiar track with one low
pressure tracking into the Great Lakes and forming a secondary low
along the east coast. Moisture will be lifted along a warm front
surging northward late Saturday night and Sunday morning. This looks
to be another case of mid-level temperatures warming faster than the
surface. At the time of precipitation onset, temperatures look to
fall into the upper 20`s before rising to around freezing around
sunrise Sunday. Precipitation looks to fall primarily as a mixture of
sleet and freezing rain late Saturday night before changing to rain
as temperatures rise above freezing. Some snow at the onset can not
be ruled out either. Model and ensemble guidance is consistent with
QPF around a quarter of an inch. Current expectations are for a
sleet/snow accumulation up to half an inch with a light glaze of ice
as well under a tenth of an inch for most of the region.
The location of the warm front is still somewhat uncertain during
the day Sunday. Areas south of this front should warm well into the
40`s and perhaps 50`s given a very warm boundary layer modeled.
However, along and north of the front lingering low-level cold
and light precipitation will likely keep temperatures
considerably lower in the 30`s to around 40. Wind gusts will
start to pick up from the south Sunday afternoon given a tighter
pressure gradient.
Precipitation is likely to taper down to just some wrap around
and lake effect rain and snow showers Sunday night. The airmass
behind the passing low pressure is not nearly as cold with
temperatures generally staying in the 30`s.
Monday through Wednesday: Given a west-northwest flow, lake effect
snow showers will be possible into early Tuesday. Colder air will
start to enter the region as well with temperatures back down into
the 20`s and 30`s as surface high pressure builds into the region.
This high pressure system should also turn off the Lake-Effect snow
on Tuesday. This high pressure moves east of the region on Wednesday
with warmer return southerly flow entering the picture. Highs should
get back into the 40`s for most areas. The high pressure system
at this time looks to hang on long enough for a mainly dry day.
&&
.AVIATION /02Z THURSDAY THROUGH MONDAY/...
Primary aviation concern will be in the KSYR-KRME corridor
where a wavering band of moderate to heavy lake effect snow will
bring significant alternate and airport minimums in and out of
these terminals overnight and early Thursday. KRME will be
closest to the band this evening, followed by a southward shift
into KSYR overnight. Timing is illustrated in the TAF, but
confidence is generally low on those specifics.
Elsewhere...VFR no cig is likely much of this evening before an
upper disturbance sweeps through bringing lower end VFR cigs and
scattered snow showers late tonight and Thursday. Confidence in
timing any precip is low, but brief MVFR-IFR visibility
restrictions can be expected from passing snow cells.
Winds west-southwest 5-10 knots, becoming NW 10-15 knots by
Thursday afternoon.
Outlook...
Thursday night...Mainly VFR.
Friday and Saturday...Mainly VFR. Chance of light snow Friday
afternoon and evening near KAVP could bring restrictions.
Saturday night and Sunday...IFR in rain, mixed precipitation
and snow.
Monday...Snow showers with restrictions possible.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...None.
NY...Winter Storm Warning until 10 AM EST Thursday for NYZ018-036.
Winter Weather Advisory until 10 AM EST Thursday for NYZ009-
037.
&&
$$
SYNOPSIS...JAB/MJM
NEAR TERM...JAB/MJM
SHORT TERM...MWG
LONG TERM...MWG
AVIATION...JAB/MJM
Area Forecast Discussion
National Weather Service State College PA
1056 PM EST Wed Mar 6 2019
.SYNOPSIS...
A cold trough of low pressure will remain over the region for
another day, bringing blustery conditions and occasional snow
showers or flurries. A weather system will bring a period of
light snow for southern portions of the area on Friday.
Following this weather system will be a weather pattern change
with milder temperatures for the weekend. A cold front will
bring a chance for rain on Sunday followed by cooler
temperatures for early next week, though much milder then the
weather this week.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
Minor changes to the forecast this evening. HRRR shows another
band of light snow showers will drift SE across NW PA overnight,
making it into central PA before dissipating. Winds have
decreased quite a bit as well.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/...
Upper level trough finally pushes east of the area with a
general decrease in cloud cover Thursday and highs well into
the 20s and lower 30s. Clipper system will approach early Friday
morning. Track looks to be over southern portions of the area
and will bring a period of light snow to the region during the
day. QPF looks fairly light and given that it`s early March with
the light snowfall intensities...accumulations will mainly be
confined to areas that already have snow with little impact to
travel expected. Behind the clipper is ridging with SW flow
brining in milder air aloft that will begin the transition to a
weekend with much milder temperatures.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
330 pm update... Longer range guidance remains consistent,
showing a deep cyclone lifting northward through the western
Great Lakes/upper Midwest later this weekend, with a trailing
cold front crossing the Commonwealth on Sunday. Following this
system, the first half of next week looks mainly dry, aside from
scattered light snow showers/flurries over the northern tier
and the Allegheny ridges.
After a dry day Saturday, the main two questions for the late
weekend system are how much precipitation affects central PA
late Saturday night into Sunday, then how much low-level cold
air gets scoured out of the area Sunday afternoon. Although a
strong and moist southerly low-level jet develops, fairly rapid
system movement should preclude any truly heavy rainfall
amounts, with ensemble guidance mainly in the 0.5-1" range within
a 12-18 hour period. As for temperatures/precipitation type,
the latest model trends indicate that the best chance for an
initial wintry mix late Saturday night is over the northern
tier of the Commonwealth, with generally rain anticipated
otherwise. Recent ensemble trends have also indicated an
increased likelihood that at least portions of south-central PA
could briefly break into the warm sector Sunday afternoon, with
potential highs into the 50s, and even some small amounts of
instability. For this reason, we`ve added a mention of isolated
thunder in the Lower Susquehanna Valley.
As mentioned earlier, Monday-Wednesday looks uneventful, with
an initially deep NW flow, weakening over time as ridging
surface and aloft approaches. The best chance for any
upslope/lake enhanced snow showers will be Monday into Tuesday,
but overall this looks pretty insignificant, given only
marginally cold temperatures and fairly shallow moisture depths.
&&
.AVIATION /04Z THURSDAY THROUGH MONDAY/...
Have observed somewhat of an uptick in snow shower activity
across northern portions of central Pennsylvania between 02z and
04z, as a weak shortwave works through the upper flow. While
most areas remain VFR across the region, still some areas of
MVFR ceilings and visibilities across the northern mountains.
Thursday will feature mainly VFR conditions over much of the
region, except again in the west and north where west to northwest
upslope flow will generate stratus and scattered snow showers.
Winds will again gust to between 15 and 20 knots in most
locations Thursday afternoon.
Outlook...
Thu...Mainly VFR. KBFD and KJST will likely see occasional
restrictions, with lower clouds and snow showers, mainly in the morning.
Fri-Fri Night...More widespread restrictions may develop, with
light snow overspreading the region.
Sat...No sig wx.
Sat Night-Sun...Another round of widespread restrictions with
rain/mixed precipitation event.
Mon...Mainly VFR, but restrictions in the west and north in snow
showers.
&&
.CLIMATE...
The current cold is cold, but we should stay above the records
cold values.
The low in Altoona on Tuesday reached 8 degrees. This tied
the old record low set in 1978 and in 2015.
Mini Maxes:
Wed...(6th) MDT = 16 in 1901, IPT = 22 in 2007
Thu...(7th) MDT = 21 in 1913, IPT = 23 in 1913
Record Mins:
Wed...(6th) MDT = 0 in 2015, IPT = -1 in 1978
Thu...(7th) MDT = -1 in 2015, IPT = 1 in 2003
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Ross
NEAR TERM...Ross
SHORT TERM...Ross
LONG TERM...Jurewicz/Fitzgerald
AVIATION...Jung
CLIMATE...
Area Forecast Discussion
National Weather Service Des Moines IA
537 PM CST Wed Mar 6 2019
.SHORT TERM.../Tonight through Thursday/
Issued at 354 PM CST Wed Mar 6 2019
Mild weather conditions will continue through this evening as Iowa
still remains under the influence of a low-amplitude ridge centered
over the High Plains. Late this evening, mid-level flow will
transition to mainly zonal flow. However there will be a small
disturbance within this flow associated with a PV anomaly that will
move in from the Northern Plains. This will kick off a broad surface
low centered over the OK and TX Panhandle, with surface trough
impacts extended into Iowa. This will be the feature that brings
active weather to the CWA. Overall, this system is not very
organized as the upper-level, mid-level, and surface level features
are not greatly in phase with each other. The start will be weak
isentropic ascent into western and southwestern Iowa. A weak push of
WAA may promote a weak amount of diabatic forcing. Eventually weak
mid-level frontogenetical forcing moves through western and central
Iowa, but it is not necessarily in sync with the isentropic ascent.
During the time of somewhat favorable frontogenetical forcing, NAM,
GFS, and a few of the CAMs show some Q-Vector convergence in the
area. However, values are not very robust. Examining the vertical
profile, GFS-NAM-Euro cross sections show a decently deep saturated
layer with modest lift Thursday morning, but by afternoon depict
drier air moving in between 700 to 500 mb, which is one limiting
factor to snow growth. Additionally, favorable lifting throughout
west-central, central, and southern Iowa will largely occur above
the DGZ, mainly in a layer between -25C to -40C. It will be very
difficult to get sufficient dendrites, as the lift through the DGZ
is expected to be much weaker. Regarding moisture content, NAM and
GFS have come in much lighter on QPF, likely under the influence of
the drier air that will come in. This, in addition to the
unorganized nature of the available forcing, snow amounts have been
reduced in the official forecast. The area has not drastically
changed, still expecting the greatest accumulations along a line
from SUX-CIN-DSM-OTM. Snow totals are expected to be between 2 and 3
inches. Most locations will likely see amounts closer to 2 inches,
at least in our CWA. With the area of dry air, a sharp cut-off on
the north side of the snow gradient should be expected. RAP and
HRRR runs this Wednesday afternoon may be slightly overdone on
QPF, but overall favor this sharp cut-off on the north side of
the snow gradient. Snow activity for central and southwest Iowa
will come to an end late Thursday afternoon as ice introduction is
lost. However there may be enough moisture in the lower levels to
support freezing drizzle. A few hundredths of an inch of ice
accumulation is possible, especially close to the Missouri border.
The main impacts from this event will be slick road conditions
after the snowfall. The impacts from preceding snowfall may help
to slightly mitigate impacts associated with freezing drizzle.
Later into Thursday evening and early Friday Morning, freezing
drizzle may spread into portions of east-central Iowa. This could
present some travel impacts. However, with the drier air that
could be in place, confidence is low in what the magnitude of its
impact will actually be.
Heading into Friday, Iowa will be under the influence of ridging
centered over the High Plains again. There will still be lingering
cloud cover, but no sensible weather in the forecast. Temperatures
will warm up, but will still be below normal for this time of
year.
.LONG TERM.../Thursday night through Wednesday/
Issued at 354 PM CST Wed Mar 6 2019
Warm advection will commence during the day Friday as upper ridge
passes over the state. The biggest challenge on Friday is if the
stratus from Thursday will linger. It is possible though the
moisture is shallow and situated near 925 mb so some clearing should
occur. Overall, this should allow temperatures to warm above
freezing for the southern half of Iowa and be in the upper 20s to
low 30s north.
Surface cyclogenesis will occur late Friday into Friday night over
southeast Colorado and western Kansas. This area of low pressure
will then lift northeast into the southeast half of Iowa by late
Saturday and into southern Wisconsin Saturday night. Still several
precipitation type challenges with this system Friday night and
Saturday as the warm nose aloft and precipitation arrives. Followed
a GFS/ECMWF blend of thermal fields and upper low track. Have
dismissed the farther south and colder NAM solution at this point as
it is a large outlier.
Expect some areas of icing initially even in areas with temperatures
slightly above freezing due to the very cold ground temperatures.
The precipitation should transition to rain across the southern two
thirds of the area but may be all snow over the northern counties.
This could lead to a moderate to heavy band of snow somewhere from
northern Iowa into southern Minnesota. The other factor will be
increasing winds Saturday night into Sunday as the low pressure
passes to the east and cold advection and better mixing develops.
Wind gusts in excess of 40 mph are likely and should the
precipitation remain all snow across the north, another blizzard
with significant drifting and travel impacts may occur. Will begin
trending messaging towards this potential as this would be the
greatest impact with this system. Farther south where rain and above
freezing temperatures occur along with minimal snow, the strong
winds will occur but any remaining snow pack should be locked into
place by rain then freezing as cold advection arrives.
Dew points will again be the driver for surface temperatures as the
saturated low levels will limit mixing potential. Have lowered high
temperatures a bit on Saturday towards blended Raw guidance
temperatures to eliminate any MOS biased mixing warmer values and to
eliminate cold biased corrected values. Have lowered the
flooding/runoff threat with this system with temperatures expected
to remain in the 30s many areas. Any rain may become locked in
storage with the snow pack or in area ditches and should not reach
streams quickly.
A modest warming trend will occur Monday and Tuesday as zonal flow
will transition back to southwest. Conditions will certainly be
much improved over the Arctic cold of this week. Then next strong
upper level system will arrive mid next week. While this system
appears farther northwest than the weekend system and warmer but
indications are that as this system lifts northeast, it will leave
the Midwest in a thermal trough and well below normal
temperatures once again for several days, just beyond the extended
forecast.
&&
.AVIATION.../For the 00Z TAFS through 00Z Thursday evening/
Issued at 537 PM CST Wed Mar 6 2019
Confidence is high in VFR conditions this evening but conditions
are expected to gradually deteriorate early Thu morning as
precipitation develops and ceilings lower, especially south and
west. MVFR conditions are expected at both KDSM and KOTM, possibly
eventually down to IFR by late afternoon. Precipitation type
should initially be snow, but may mix with or switch over to
freezing drizzle as well. Farther north, conditions will likely
remain VFR with nothing beyond flurries.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from midnight tonight to 6 PM CST
Thursday for IAZ033-034-044>047-057>060-070>073-081>084-092>095.
Winter Weather Advisory from 6 AM to 6 PM CST Thursday for
IAZ061-062-074-075-085-086-096-097.
&&
$$
SHORT TERM...Krull
LONG TERM...Donavon
AVIATION...Small
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
607 PM CST Wed Mar 6 2019
.AVIATION... /00Z TAFS/
Gulf moisture return accelerates after 03Z with cigs along I-35
expected to lower quickly between 03Z and 06Z. May need to consider
more ifr cigs along I-35, and have already made a last minute change
to drop DRT into lifr cigs at daybreak, in following the RUC fcst
sounding there and in conseration of the higher elevation. I-35
sites should have slightly more boundary layer winds and with early
evening winds being a little gusty will show a slower cloud lowering
trend. Lifting of cigs back to vfr is forecast to be a bit faster
than typical for an early March morning, but the pressure gradient
tightens considerably between 15Z and 18Z along I-35. Some higher
afternoon/early evening gusts may need to be considered in future
TAF updates. Mvfr cigs should return quickly Thursday evening and a
long period of ifr cigs may need to be considered for late Thursday
evening and beyond.
&&
.PREV DISCUSSION... /ISSUED 313 PM CST Wed Mar 6 2019/
SHORT TERM (Tonight through Thursday Night)...
Moisture is on the increase as a low level cloud deck around 4 Kft to
5 Kft pushes across the Coastal Plains into areas along and east of
Interstate 35 and 37. Dewpoint temperatures across the Coastal
Plains are already in the mid 40s and expected to increase and spread
to the north this evening into the overnight hours. A low level jet
in place across the middle of the Texas coast is forecast to continue
to push low level moisture across the area through Thursday. This
scenario brings slight chances for rain across the Coastal Plains and
east of I-35 in addition to light patchy drizzle overnight/Thursday
morning. Due to the increase of moisture, no more freezing
temperatures expected across the area with lows forecast to range
from the low to upper 40s.
Increased moisture in combination with south to southwest winds across
the area will aid temperatures to rise to the upper 60s and lower 70s
on Thursday afternoon. Mostly cloudy skies are expected across the
area on Thursday night with another round of patchy light drizzle
affecting areas along and east of I-35 during the overnight
hours/Friday morning.
LONG TERM (Friday through Wednesday)...
The warm trend continues on Friday with highs in the mid to upper
70s and even lower 80s along the Rio Grande. There is a slight chance
for showers across the far east counties where higher values of
moisture resides. Late Friday evening into the overnight hours, a
Pacific front is forecast to push from West Texas into the northwest
part of South Central Texas. The frontal passage is expected to move
across the area during the morning hours and exit the area southeast
counties early Saturday afternoon. There are chances for showers and
isolated thunderstorms through that period as the front moves across
South Central Texas. The areas with best chances for showers and
thunderstorms are the northeast part of the Hill Country and areas
along and east of Highway 183. Rainfall amounts expected for the
event to be one quarter inch or less.
Chances for showers are in the forecast for the first part of next
week with the potential for strong thunderstorms across the area
Tuesday night into Wednesday as a strong upper level disturbance
moves across the area. Medium-range guidance differ on the
progression and precipitation amounts at this time, but all suggest
a strong system affecting the area during the Tuesday
night/Wednesday morning time frame. Stay tuned.
&&
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 45 71 60 77 63 / - 0 - 10 50
Austin Bergstrom Intl Airport 44 70 60 76 63 / - - - 10 50
New Braunfels Muni Airport 44 69 59 77 63 / 10 - 10 10 40
Burnet Muni Airport 42 71 57 78 60 / 0 0 0 0 50
Del Rio Intl Airport 41 72 54 80 60 / 0 0 0 - 20
Georgetown Muni Airport 43 71 60 77 62 / - 0 - - 50
Hondo Muni Airport 42 71 58 80 64 / 0 - - - 30
San Marcos Muni Airport 44 70 59 77 63 / 10 - 10 10 40
La Grange - Fayette Regional 48 69 61 76 65 / 10 20 10 20 50
San Antonio Intl Airport 45 69 60 78 64 / - - 10 10 40
Stinson Muni Airport 45 70 60 78 64 / - 10 10 10 30
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Aviation...Oaks
Short-Term/Long-Term...Hampshire
Public Service/Data Collection...33
Area Forecast Discussion...UPDATED
National Weather Service North Platte NE
945 PM CST Wed Mar 6 2019
.SYNOPSIS...
Issued at 305 PM CST Wed Mar 6 2019
An amplified pattern continues across the CONUS and
Canada this morning. A large area of low pressure was present across
eastern Canada and a trough of low pressure extended south of this
feature through Florida. Across the western CONUS, a low amplitude
ridge was present from the four corners north to Montana. West of
this feature, a closed low was noted off the coast of British
Columbia. A strong shortwave trough extended south to off the coast
of southern California. At the surface: High pressure was located
over Arkansas with a second high noted over southern Saskatchewan.
Low pressure was present over sern Wyoming with a stationary front
extending south into west Texas and another stationary front
extending northwest of the low into Idaho. Abundant mid and high
level clouds continue to stream into the forecast area this
afternoon thanks to abundant Pacific moisture from the swrn CONUS.
&&
.UPDATE...
Issued at 945 PM CST Wed Mar 6 2019
A new snowfall forecast is in place using a blend of the previous
forecast, the HRRR model and the RAP model. This moves the
accumulating snow south to areas along Interstate 80 and keeps the
forecast amounts about the same.
&&
.SHORT TERM...(This evening through Thursday night)
Issued at 305 PM CST Wed Mar 6 2019
Tonight through Thursday night...Snow is expected to
develop in the panhandle near sundown and spread to the east
southeast into the overnight hours. Strong mid level frontogenesis
will be the culprit as the system will be mainly upper level in
nature. That being said, not expecting much in the way of wind
overnight with easterly winds mainly on the order of 5 to 10 MPH.
With respect to snowfall amounts and headlines. Inherited forecast
had a broad swath of 3 to 5 inches of snow from the northeastern
Panhandle into the northeastern forecast area. With this morning`s
model runs, the main axis of snow had shifted slightly south. With
this in mind, added another row of counties to the winter weather
advisory which now includes Garden county east to Custer county. As
for snow accumulations they were shifted south to accommodate the
latest model trend from this morning. Further south across far
southwestern Nebraska, mid level moisture will not be as prevalent
with more a setup for freezing drizzle. Currently, there is an area
of mid level drying noted over eastern Colorado and this lends
credibility to the drier mid layer expected over swrn Nebraska this
evening. Snow will exit the northeast forecast area Thursday
morning. Dry conditions are expected thereafter, however clouds will
linger across the forecast area Thursday which will hold highs down
in the 20s. Low pressure will begin to deepen along the front range
of the Rockies Thursday night resulting in increased southerly winds
across the high plains. With expected winds, gave a slight boost to
lows Thursday night. The latest NAM12 is hinting at the threat for
freezing drizzle toward Friday morning. ATTM, this is an outlier
compared to the GFS and Canadian solns and will hold off mention for
now.
.LONG TERM...(Friday through Wednesday)
Issued at 305 PM CST Wed Mar 6 2019
A tandem of powerful upper level lows, will impact the forecast area
Friday night into Saturday night and a second system which could be
even stronger, may impact the central plains by midweek next week.
System #1: Southerly winds will continue to increase during the day
on Friday as an upper level trough of low pressure lifts across the
intermountain west. Surface low pressure will deepen down stream of
the UA trough, across the high plains of Colorado. Increased serly
winds will bring in abundant boundary layer moisture during the day
Friday. With mid level moisture holding back until Friday night,
there will be a threat for fog/drizzle on Friday. ATTM temperatures
will rise into the lower 30s west of highway 83 so the threat for
fzdz appears limited attm. By Friday evening, the upper level trough
will lift northeast. With mid level moistening, precipitation will
begin to develop to the southwest, pushing into the forecast area
Friday night. With a warm layer aloft and a sub freezing boundary
layer, a plethora of precipitation types will impact the forecast
area Friday night. the only portion of the forecast area where the
warm layer will be sub freezing will be in the northwest where all
snow is expected Friday night. For the bulk of the forecast area, a
mix of freezing drizzle, freezing rain, rain or snow is expected
Friday night. Even if temps hold above freezing for a while, frozen
ground conditions could lead to a rapid freeze of precip on the
surface Friday night with a travel mess anticipated. By Saturday
morning, the upper level low lifts across northern Nebraska with
areas of snow impacting the northern half of the forecast area.
Further south, drier air limit snowfall Saturday. As it stands right
now, the greatest threat for significant snowfall accumulations late
Friday night into Saturday are over northern Nebraska. Will start
messaging the weekend storm via social media and on the web but will
hold off on any headlines for now as it is in the 5th/6th period
time frame. Snow will end quickly Saturday evening, but strong
northerly winds will continue into the overnight with a blowing snow
threat carrying over into Sunday morning.
System #2: Another deep trough of low pressure aloft will lift into
the swrn CONUS Monday, lifting into the srn plains on Tuesday. A
strong down stream ridge will negatively tilt the trough of low
pressure by midweek as it lifts north into the central plains. Both
the latest GFS and ECWMF solutions lift this system into eastern
Nebraska next Wednesday with a classic winter storm possibly
impacting western and north central Nebraska next Wednesday. Both
models have very intense surface lows forecast so these systems have
the potential for possible blizzard conditions. The Canadian soln
however is farther south with the upper level low and somewhat
weaker with its surface low. Regardless, this system bears watching
as we head into next week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 524 PM CST Wed Mar 6 2019
MVFR/IFR/local LIFR ceilings and vsby in snow are expected to
spread across wrn Nebraska this evening and into ncntl Nebraska
from around midnight onward. Improvement to MVFR/local IFR is
expected across wrn and ncntl Nebraska Thursday afternoon.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until noon CST /11 AM MST/ Thursday for
NEZ004>010-022>029-035>038-094.
&&
$$
UPDATE...CDC
SYNOPSIS...Buttler
SHORT TERM...Buttler
LONG TERM...Buttler
AVIATION...CDC
Area Forecast Discussion...Updated
National Weather Service Saint Louis MO
943 PM CST Wed Mar 6 2019
.UPDATE...
Issued at 935 PM CST Wed Mar 6 2019
A west-northwest to east-southeast oriented snow band has been
evolving across Nebraska this evening as a result of low-mid
level WAA and the resulting increase in low-mid level frontogenetic
forcing. Observations compared to the regional radar returns
suggest the far eastern portion of the band has more bark than
bite and snow isn`t reaching the ground yet. This band should
continue to get more organized overnight and move into northeast
MO and west central IL. Much of this echo will initially be aloft
associated with mid cloud/moisture, however after 08-09z the lower
levels should eventually moisten coincident with the strongest
forcing. The 00z NAM and latest RAP are in good agreement with
this scenario and the forecast has this well covered. The only
updates needed to the tonight/early morning period were some
tweeks to sky cover and temperatures, and a slight delay in POPS
in the 06-08z time frame. The winter weather advisory for late
night through Thursday continues to highlight the area of primary
impact from measurable snowfall.
Glass
&&
.SHORT TERM... (Through Late Thursday Afternoon)
Issued at 353 PM CST Wed Mar 6 2019
The primary concern for the next 24 hours the potential for
accumulating snow late tonight and into Thursday...primarily across
northeast Missouri and into west central and south central Illinois.
A developing low pressure system over the Great Plains will move
slowly eastward tonight and Thursday, and all models are showing low
level warm advection/moisture convergence over Missouri and Illinois
to a greater or lesser extent ahead of this system. This forcing
really ramps up between 09-12Z tonight over northeast Missouri, and
it is between these times that the models begin to generate QPF.
Additionally, frontogenesis in the 850-700mb really strengthens
after 12Z Thursday morning as the baroclinic zone tightens up
through that layer of the atmosphere. Forecast soundings across the
area indicate that the precipitation will either be rain or snow,
with little if any chance of any mixed precipitation or icing, and
the phase of the precipitation will be largely determined by
boundary layer temperature. In fact, the soundings show a fairly
dry boundary layer for much of the day south of a line from around
Moberly Missouri to around Salem Illinois. There may be some light
rain or snow along and south of that line, but little if any
accumulation is expected at this time. Total daytime accumulations
in northeast Missouri into south central Illinois of 1 to 2 inches
looks likely, with the highest amounts in far northeast Missouri and
west central Illinois...most likely between 600 AM and 1200 PM. With
potential impacts to the morning commute, will go ahead and issue a
winter weather advisory for these areas. Temperatures through
tomorrow will continue on the cold side with overnight lows tonight
in the mid 20s. Daytime highs in the advisory areas are expected to
climb up to near or just above freezing, where areas further south
should get well into the upper 30s to mid 40s.
Carney
.LONG TERM... (Thursday Night through Next Wednesday)
Issued at 353 PM CST Wed Mar 6 2019
The synoptic upper pattern Thursday night and Friday will be in the
process of transitioning to more of a split flow that we typically
see more in the springtime.
Until that is complete, we will get one more upper level disturbance
that will roll through Thursday night and early Friday morning. It
is expected to in effect prolong the wintry event that had already
begun about 12 hours earlier in portions of northeast MO and central
IL and may allow for some level of expansion of wintry precipitation
southward late Thursday night.
Models have minor differences in timing of this upper level
disturbance but it is depicted strong enough to result in fairly
deep and strong WAA early Thursday night with a wave of low pressure
sliding through southern MO and the lower Ohio valley and cyclonic
low level flow across much of the area. The result should be a
flare up in light precipitation areawide Thursday evening and
finally exiting at some point early Friday morning, probably hanging
on the longest after sunrise Friday morning in southeast MO.
Where the Winter Weather Advisory has been issued (northeast MO and
central IL), precipitation types mainly favor snow transitioning to
freezing rain/drizzle. As colder air builds south late Thursday
night, expect the drizzle that will likely already be in place to
become freezing drizzle for areas near and north of I-70. Additional
snow accumulations for Thursday night look to be up to an inch in
the Advisory area, with potential for a light glazing of ice as far
south as I-70. Given the higher uncertainty for icing potential in
central and east-central MO and Metro East, held off an Advisory
there with this issuance.
Attention then turns to what the models depict as a strong
negatively-tilted shortwave on Saturday. There continues to be
disagreements on how much instability will make it this far north
and exact depictions of the storm with respect to fronts and timing.
Some models have an occluded front passing through while others
depict a separate warm front followed by dryline in the afternoon.
It does look like plenty of shear will be available, especially 0-
1km. While a large area of rain with embedded thunderstorms does
seem likely, potential for LEWPs within this larger area of rain
is there with strong to severe storms capable of damaging winds or
isolated tornadoes. The threat area was reduced to near and south
of I-70 for late morning and afternoon Saturday.
Look for a couple days of dry weather behind this system Sunday and
Monday before another strong negatively tilted shortwave attempts to
make another run on our area for the middle of next week, but
preliminary depictions of this have it tracking further west than
the Saturday system.
Temperatures are expected to be generally seasonable from Friday
onward with the exception of Saturday and Wednesday which are the
two days most impacted by the strong storm systems and deep
southerly flow. At the same time, there is also plenty of bust
potential given the extensive high PoP rain shield on Saturday and
to a lesser extent Wednesday. NAM shows temps in the 30s all day
Saturday while the GFS backed off its earlier well into the 60s
depiction for 50s.
TES
&&
.AVIATION... (For the 00z TAFs through 00z Thursday Evening)
Issued at 541 PM CST Wed Mar 6 2019
VFR flight conditions are expected much of this evening and into
the overnight hours with an abundance of high and mid clouds.
Between around 09-12z it appears a west-northwest to east-
southeast band of snow will develop centered across northeast MO
and west central IL impacting KUIN. Present indications are the
southern extent of this snow band will remain north of the other
terminals. Flight conditions should deteriorate to IFR at KUIN with
the snow band, with improvement to MVFR on Thursday afternoon as
the intensity of the snow diminishes. Further south, from the late
afternoon and into Thursday evening a region of stratus will bring
MVFR flight conditions and the threat of some spotty rain showers.
SPECIFICS FOR KSTL:
VFR flight conditions are expected tonight and through the day on
Thursday with mid-high clouds tonight and VFR stratus increasing
on Thursday. Between around 09-12z it appears a west-northwest to
east-southeast band of snow will develop centered across northeast
MO and west central IL impacting KUIN. Present indications are
the southern extent of this snow band will remain north of KSTL.
Spotty rain showers are possible during the later part of Thursday
afternoon, with MVFR flight conditions and the threat of some
spotty rain showers on Thursday evening.
Glass
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...Winter Weather Advisory from 4 AM Thursday to 6 AM CST Friday
for Knox MO-Lewis MO-Marion MO-Shelby MO.
IL...Winter Weather Advisory from 4 AM Thursday to 6 AM CST Friday
for Adams IL-Brown IL-Greene IL-Macoupin IL-Montgomery IL-
Pike IL.
&&
$$
WFO LSX
Area Forecast Discussion
National Weather Service Pocatello ID
232 PM MST Wed Mar 6 2019
.SHORT TERM...This Afternoon Through Saturday.
Unsettled weather continues in the short-term portion of the
forecast. An approaching shortwave trough (rotating through to
the south of a strong and slow-moving low pressure center
positioned near the Washington coast) is already resulting in the
development of widespread showers across the region early this
afternoon (rain and snow, depending on elevation). There may be
just enough instability to generate an embedded/isolated
thunderstorm or two, and we maintain mention of thunder in the
forecast for the afternoon. No severe weather is expected.
Light rain/snow showers may continue Thurs as a cold front
crosses the region. Continued warm temperatures ahead of the
front will support rain in the lower elevations from the Snake
Plain southward. 1-4 inches of snow is possible from this
afternoon through Thurs eve with this activity in our mountains
and highlands. Behind the front, and supported by a potent jet
streak aloft, we continue to monitor the potential for a moderate
to heavy band of snow to develop and slowly work ENE across the
area from early Fri morning through Fri night. Temperatures will
cool and support predominantly snow everywhere by this time. The
NAM and GFS continue to disagree on the exact timing and position
of this band, so uncertainly remains high in how this will play
out. The 18Z NAM run may be trending toward the GFS, supporting a
healthy dose of snow in the eastern Snake Plain Fri afternoon and
eve. At least several inches of snow are possible. With the
continued uncertainty, we continue to highlight this potential
with an SPS vs. considering any advisories at this time. Snow may
linger over portions of the Snake Plain Friday night as well as a
zone of convergence develops, but here too the models disagree on
position, with the GFS favoring north of Idaho Falls and the NAM
favoring locales further south. Strong winds Fri afternoon and eve
may produce blowing and drifting snow and increase travel impacts
in conjunction with the potentially moderate to heavy snow. A
gradual drying trend is expected Sat from west to east with some
light snow showers continuing. - KSmith/Hinsberger
.LONG TERM...Saturday Night Through Next Wednesday.
The 12Z models are in good agreement for much of the long-term
period. Broad upper troughing remains over the Western US. A cut-
off low will drop off the Southern California Coast by Sunday
night, and eventually making landfall over the Baja peninsula
Monday night. Over Idaho, a weak upper flow will result with no
distinct upper dynamics through Monday night. GFS is drawing on a
deep southerly flow to bring some moisture along the Utah border
on Monday, but the ECMWF keeps precip out of Idaho altogether. A
short wave trough will drop in from the northwest on Tuesday with
both models continuing to show good agreement with the timing. The
GFS is slightly deeper with the trough, but is consistent with
the onset of precipitation across the state. - Hinsberger
&&
.AVIATION...
Upper short wave will lift across Idaho today, bringing areas of
rain and snow showers. Isolated thunderstorms cannot be ruled
out, with just enough CAPE in the forecast soundings to make it a
possibility. Left thunder out of the 18Z TAF package given some
bit of uncertainty. Precip type may also be challenging, and will
likely determine visibility category. Went with rain or rain/snow
mix for the sites, but if precip changes over to snow late this
afternoon/evening, KSUN and KDIJ may drop below airfield minimums.
BUFKIT soundings (15Z RAP and particularly the 12Z NAM) support a
heavy band of snow (7" and 9") at KDIJ late this afternoon
through this evening. - Hinsberger
&&
.PIH WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Area Forecast Discussion
National Weather Service Pueblo CO
605 PM MST Wed Mar 6 2019
.UPDATE...
Issued at 603 PM MST Wed Mar 6 2019
Will be updating fcst to include Huerfano county and lower
elevations of western Las Animas county into the high wind
warning. K4V1 was gusting to 55 knts at 5:39 pm. UPdates will be
issued shortly.
&&
.SHORT TERM...(This evening through Thursday)
Issued at 243 PM MST Wed Mar 6 2019
...Wind driven snow will continue along the Continental Divide
tonight and early Thursday...
...Strong winds over the Sangres and adjacent lower elevations
tonight...
Slight lull in snowfall along the Divide this afternoon, though
latest regional radar loop and mesoscale models suggest an upturn in
snowfall rates and coverage as we head into the evening and
overnight hours. Current set of winter highlights look good for the
night, with bursts of heavy snow accompanied by howling west winds,
especially at and above pass level. Farther south and east, winds
have slowly increased over the Wets/Sangres and San Luis Valley,
though gust speeds have been running much lower than rather extreme
HRRR forecasts. Given poor performance of the HRRR so far, will keep
current high wind warning confined mainly to higher elevations, and
let next shift monitor for possible expansion to adjacent plains.
Peaks will certainly remain windy as upper jet moves overhead
through the night into Thu morning. String of upper level energy and
moist orographic flow will keep snow going through midday Thu along
the Divide, before activity wanes from south to north during the
afternoon. Windy conditions will persist over the mountains, I-25
corridor and eastern plains along the NM border Thu, though some
decrease in speeds will begin during the afternoon as heights build
and upper level jet sags south of the state. Temps overnight will
remain rather mild at many locations, coldest readings again over
the far ern plains where easterly winds will keep cooler air in
place. On Thu, mild air will again cover most of the region, with
mountains and far ern plains coldest for another day.
.LONG TERM...(Thursday night through Wednesday)
Issued at 243 PM MST Wed Mar 6 2019
Models and ensembles are in better agreement today through the
extended period, with slight differences in storm track leading to
the only uncertainty at this time. Overall forecast confidence is
higher than average.
Thursday night through Saturday...an upper level disturbance will
be exiting the region Thursday night with snow winding down along
the Continental Divide. Periods of light snow will likely continue
into Friday morning, but accumulations will be minor, and
generally north of Monarch Pass. Winds will also be decreasing
through the overnight period. On Friday, the next upper level
disturbance will shift east across Colorado. This storm system
looks to be much stronger. Snow will be on the increase along the
Continental Divide Friday morning and continue through the
afternoon hours. Snow could be heavy. Winds will also be on the
increase Friday afternoon and evening as the trough base moves
across Colorado. Winds could gust from the west in the 40 to 60
mph range for the Mountains and adjacent foothills. This will need
to be monitored. Across the Plains, models in good agreement with
a band of rain Friday afternoon, changing and mixing with snow
during the evening hours before exiting east into Kansas. Not
anticipating any accumulations over the Plains at this time.
Expect to see snow dissipate along the Continental Divide by
Saturday with just light snow possible throughout the day. Dry
conditions are expected on the Plains. Temperatures will generally
be warm across the Plains on Friday, with upper 50s to lower 60s.
Temperatures on Saturday will be a few degrees cooler with lower
to mid 50s for highs.
Sunday...generally dry conditions are expected on Sunday as
transient high pressure moves across the state. Flow will begin to
turn more southwesterly by Sunday evening as the next upper system
approaches the area. Periods of light snow will remain along the
Continental Divide with minor accumulations possible. Highs across
the region will generally make it into the mid to upper 40s.
Monday through Wednesday...models in good agreement with a strong
upper level storm system moving out of the Desert Southwest early
next week. Abundant moisture is forecast to move northward as the
system strengthens over the region. Expect moderate to heavy snow
to move into the San Juan and Sangre de Cristo ranges by Monday
morning and spread north across the rest of the mountains. Across
the Plains, temperatures will be warm enough for potentially heavy
rainfall, especially near the Kansas border by Tuesday.
Thunderstorms may need to be introduced out east. The main
questions becomes if and when a change over to snow will occur in
the wrap around trowal as the system exits. Currently there could
be the potential for snow on the Plains Tuesday night into
Wednesday across the Plains as the upper system exits the area. It
is still too early for numbers such as snowfall due to differences
in storm track and strength, but this storm has the potential to
be a decent precipitation producer across southern Colorado.
Mozley
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 243 PM MST Wed Mar 6 2019
VFR at all taf sites tonight and Thursday. Very low risk of some
stratus and fog pushing westward on the plains at least getting
close to KPUB and KCOS overnight, though most models keep any cloud
shield east of both terminals, so won`t include in either taf at
this point. Winds diminish this evening, with a period of wind shear
possible at KCOS after 02z as strong winds aloft spill east of the
mountains. On Thu, W-SW winds will re-strengthen with gusts over 30
kts possible at all sites after 18z.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
High Wind Warning until noon MST Thursday for COZ073>075-080-082.
Winter Weather Advisory until 5 PM MST Thursday for COZ058-059-
061-066-068.
Winter Storm Warning until 5 PM MST Thursday for COZ060.
&&
$$
UPDATE...HODANISH
SHORT TERM...PETERSEN
LONG TERM...MOZLEY
AVIATION...PETERSEN