Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/18/24
Area Forecast Discussion
National Weather Service Buffalo NY
1029 PM EDT Sun Mar 17 2024
.SYNOPSIS...
Cold air will deepen across the region this week, with several
passing surface troughs producing occasional rounds of snow showers,
graupel, and lake effect snow tonight through Thursday. The greatest
snow accumulations will be found across the higher terrain east of
Lake Erie and Lake Ontario. The snow will most readily stick from
around sunset through mid morning each day, with some melting during
the daylight hours due to the high March sun angle. Temperatures
will run below average through the end of the week.
&&
.NEAR TERM /UNTIL 6 PM MONDAY EVENING/...
Water vapor imagery displays several shortwaves over the Upper
Midwest that will deepen an upper level trough over the Great Lakes
this week. As this trough deepens and slides towards our region, a
deepening cold airmass will generate bands of lake effect snow off
both eastern Great Lakes by Monday morning.
Radar imagery showing a few areas of snow showers late this evening.
The last of the diurnal snow showers are drifting east across the
Finger Lakes and Central NY, gradually diminishing in coverage with
time. Lake enhanced snow showers are expanding across Chautauqua
County, and a few lake effect snow showers are developing southeast
of Lake Ontario from Sodus Bay to southern Oswego County. All of
this is disorganized for the time being.
Continued cold air advection will drop 850 hPa temperatures to -10C
towards Monday morning to allow for lake effect snow to continue to
develop. With the deeper synoptic moisture arriving later tonight,
lake response should be minor with just an inch or two of snow
tonight across the higher terrain east of Lake Erie and across the
Tug Hill Plateau east of Lake Ontario. Confidence is low on this
snow late tonight and Monday morning as we are marginally cold
enough aloft, and the deeper synoptic moisture will just be arriving
over the Lakes. Several operational models, including the 12Z GFS,
Canadian, HRRR as well as the NBM do indicate several inches of snow
falling by Monday morning east of Lake Ontario.
Temperatures aloft may actually warm a degree or two Monday, that
with the March sun angle will trend lake snows to more cellular in
nature as deep diurnal mixing interferes with the delicate
circulations that drive bands of lake effect snow. This will hold
back on snow accumulations through the day to some extent. Expect a
spotty inch or so for the higher terrain east of Lake Erie, and 2-4"
for the Tug Hill Plateau.
By tomorrow night synoptic moisture will have deepen sufficiently
that with strong CAA aloft and steepening lapse rates lake effect
snow should once again increase in intensity east of both Lakes. The
approach of a secondary surface trough from Canada will enhance low
level convergence with greater snow accumulations east of Lake
Ontario, than east of Lake Erie, where some wind shear will allow
the snow bands to oscillate. East of Lake Erie additional snow
should amount to 1 to 3 inches, while additional snow amounts of 4
to 6 inches are possible on the Tug Hill.
Will issue a winter weather advisory for the eastern Lake Ontario
region, mainly for the Tug Hill, from early Monday morning through
early Tuesday morning. Within this broad time window, the best snow
accumulation and greatest impact is expected to be late Monday
afternoon through Monday night.
Overnight lows will be in the 20s, while tomorrow will feature near
and below normal temperatures in the mid to upper 30s. These values
tomorrow will be some 15 to 20 degrees colder than what the region
has averaged the first half of March.
&&
.SHORT TERM /6 PM MONDAY EVENING THROUGH WEDNESDAY NIGHT/...
On and off snow showers and cool weather will be the main theme
moving through mid-week. A shortwave trough will approach the region
on the backside of a departing trough Tuesday. Boundary layer flow
will back to the southwest and will likely cause ongoing lake effect
snow showers to move north towards the Northtowns east of Lake Erie
and the Tug Hill east of Lake Ontario. Warm air advection will take
place ahead of an approaching surface low pressure/surface trough.
While lake induced instability will become marginal east of Lake
Erie by Tuesday afternoon, forcing from the surface low and
approaching trough will intensify snow showers across the region.
Daytime highs will reach the upper 30s to low 40s and any snow
accumulation will likely be confined to the higher terrain east of
the Lakes. Breezy conditions will result in wind chill values in the
20s Tuesday.
The surface reflection will move across the forecast area Tuesday
night. This will disrupt the wind field across the region with
weakening snow bands. Falling temperatures will allow snow to
accumulate across the region, however there is uncertainty in snow
placement Tuesday night. The NAM is showing a stronger surface low
and snow ahead of this system, with lake effect snow forming east of
Lake Erie whereas the RGEM keeps lake effect and upslope snow on the
Tug Hill and lesser amounts east of Lake Erie. The global models and
ensemble systems show a higher probability of snow continuing east
of Lake Ontario. While snowfall amounts could be higher especially
on the Tug Hill Tuesday night, sided with consensus and have minor
accumulations at this time.
Fortunately, there is good agreement that another shot of cold air
moves into the region behind the surface trough Wednesday. The
wintry pattern continues aloft with another, more robust shortwave
trough moving down from the Upper Great Lakes region. Winds will
ramp up across the region with the PV 1.5 pressure surface lowering
to 500mb. Breezy conditions expected with gusts 30-40mph,
potentially higher along the eastern Lake Ontario shoreline.
Temperatures aloft will fall to -12C across the region and unstable
conditions will lead to snow showers across the region. Lake
enhanced snow showers with possible upstream connections could
produce localized heavier snow showers. High temperatures will reach
the low to mid 30s across the higher terrain to the upper 30s across
the lake plains. Highest chance for snowfall accumulation will be
across the higher terrain. Wind chills will stay in the 20s before
falling into the teens by evening. Cold Wednesday night with lows in
the upper teens to low 20s and wind chills in the single digits.
Snow showers will continue within northwest flow across the region.
&&
.LONG TERM /THURSDAY THROUGH SATURDAY/...
Winter like pattern for at least the start of the long term period.
While the long term period won`t be as cold as some days we have had
this winter, it will be among the coolest vs climatology, especially
for Thursday where afternoon highs of 10 to 15 degrees below normal
are expected for most of the area. Temperatures in the mid 20s to
mid 30s for the day on Thursday will slowly warm on Friday to the
upper 20s to low 40s. Still plenty of uncertainty with the weekend
among the guidance and therefore the weekend temperatures, but new
guidance is starting to come in colder, so will take that into
account for the weekend Max Ts and adjust them down some.
Models seem to be in fairly good agreement that lingering lake snow
showers will continue into Thursday south and southeast of the
lakes, tapering off through the day. Thursday afternoon and most of
the night dry out as a weak ridge and quick sfc high pass by before
another batch of showers approach.
A weak warm front tracking across the area brings the next chance
for snow showers (mixing with rain at times) Friday morning, with
the trailing cold front/trough continuing the precip into the
morning on Saturday.
There will be the potential for a lake response off of both lakes
from Saturday morning into Saturday night, but model disagreement
becomes more evident from Saturday morning onward. The GFS brings a
colder airmass with 850H temps dropping to -12 to -18 C for
Saturday, while the Canadian is much warmer only dropping the 850H
temp to around -9C briefly. This is in part because the Canadian
also places the main portion of the mid-level trough and low farther
north and looks to move the main trough through quicker.
&&
.AVIATION /03Z MONDAY THROUGH FRIDAY/...
A few areas of scattered snow showers will continue to drift across
the area from late evening through the early overnight. Most areas
will be VFR, but any of the snow showers will contain brief/local
MVFR to IFR conditions.
Late tonight and Monday cold air will continue to deepen, supporting
increasing lake effect snow east of Lake Erie and Lake Ontario.
Strong diurnal mixing from the high March sun angle will likely
break apart the lake effect snow into convective snow showers from
late morning through early evening, with any of the heavier snow
showers producing brief/local IFR/LIFR VSBY and MVFR CIGS. Outside
of lake effect areas, general snow showers will increase Monday
afternoon with local IFR as a trough and deep moisture cross the
region.
Outlook...
Monday night through Wednesday...Occasional lake effect snow showers
with local/brief IFR conditions. MVFR/VFR outside of lake effect.
Thursday...MVFR/VFR with a chance of snow showers and associated
brief/local IFR.
Friday...Mainly VFR.
&&
.MARINE...
Small craft advisories are in place throughout the Lower Great
Lakes...as a deep cyclonic flow will maintain fresh to strong winds
through at least Monday evening. During this period...gale force
gusts will be possible on the eastern half of Lake Ontario.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...Winter Weather Advisory from 5 AM Monday to 5 AM EDT Tuesday
for NYZ006>008.
MARINE...Small Craft Advisory until 8 PM EDT Tuesday for LEZ040-041.
Small Craft Advisory until 8 PM EDT Tuesday for
LOZ042.
Small Craft Advisory until 5 AM EDT Wednesday for
LOZ043>045.
&&
$$
SYNOPSIS...Hitchcock/Thomas
NEAR TERM...Hitchcock/HSK/Thomas
SHORT TERM...HSK
LONG TERM...SW
AVIATION...Hitchcock
MARINE...Thomas
Area Forecast Discussion
National Weather Service Duluth MN
1051 PM CDT Sun Mar 17 2024
.KEY MESSAGES...
- Scattered snow showers and flurries continue today for mainly
the Arrowhead and northwest Wisconsin. A localized quick
dusting is expected this morning with any snow shower.
- Lake effect snow continues along the South Shore through
Sunday night, ending late Monday morning. A Winter Weather
Advisory continues for Iron County through Monday morning.
Total accumulations of 4 to 8 inches, and locally to around 12
inches are expected for northern Iron County.
- Near-critical fire weather conditions are possible on a daily
basis into the middle of this week due to low humidities and
breezy winds.
&&
.UPDATE...
Issued at 1051 PM CDT Sun Mar 17 2024
We increased snow totals some tonight over the snow belt of Iron
County. Observations have been little help as KIWD hasn`t seen
low visibility so far. Spotters/law enforcement estimate 7 to
perhaps 9" so far in the snow belt. RAP soundings show an
inversion around 3300 feet with that area and a bit aloft in the
DGZ. We thought about going with a Winter Storm Warning for Iron
County but think the heaviest snow is rather localized. We
expect another 3 to 4" overnight with some locally higher
amounts possible. Totals in a few spots could go to a foot but
most of the area will be less. We`ll adjust as new information
comes in overnight if needed. The winds are expected to back
through the morning Monday which will bring the accumulating
snow to an end.
&&
.DISCUSSION...
Issued at 358 PM CDT Sun Mar 17 2024
Scattered snow showers and flurries have continued today, with
lake effect snow showers along the South Shore. So far the
highest reports have been in the 3 to 4 inch range around
northern Iron county as of late morning, with up to 3 inches
along the Bayfield Peninsula. As expected today, the bits of
sunshine that work their way in between the snow showers, snow
has been compacting and melting even as it falls, and we may
have gotten more snowfall than is being measured. Tonight, a
ridge of high pressure should build into the region and cause
winds to finally diminish to less than 10 mph for most locations
by Monday morning. This will also bring in some drier air,
finally cutting off the snow showers and eventually the lake
effect snow by Monday morning. Clouds are also expected to
finally diminish from west to east, but it should not begin
until the ridge axis gets a little closer, during the morning
hours of Monday. Monday to remain chilly, with high temperatures
once again only in the 30s for most locations.
Monday into Tuesday we have a fairly potent shortwave that
dives out of Manitoba, which should bring another fast moving
round of light precipitation. There is not a lot of moisture
available, so we are not expecting much for precipitation, and
we may only see a dusting of snow, though up to an inch is
possible for the tip of the Arrowhead. Of more significance, may
be the stronger northwest winds behind the associated cold
front on Tuesday. Temperatures will still be on the chilly side
with highs only in the 30s to around 40, but the winds will push
wind chill values down into the 20s. Afternoon RH values should
drop into the 30 to 40 percent range as well, so with these RH
values and gusty winds, fire weather conditions will be a
concern. Wednesday will be even drier, so even with the lighter
winds, the fire weather conditions will be even more of a
concern.
There is increasing confidence in a shortwave that slides
across Minnesota and Wisconsin Thursday into Friday. This
shortwave could bring us a period of light snow Thursday through
Thursday night, with a 75% or greater probability of an inch or
more of snow by Friday morning. Most of this system is likely
to pass to the south of the forecast area, but it appears we
should get at least a little bit of precipitation out of it.
Model guidance continues to diverge heading into next weekend
and early the following week. There are signs of a stronger,
Colorado Low like low pressure system/cutoff low which has the
potential to bring significant precipitation to parts of the
Northland next Sunday into early next week. Ensembles show a
fairly strong signal for a strong upper low pressure system
moving across the CONUS early next week. However, with the
spread in the surface low tracks with this system, confidence in
precipitation amounts and placement is low.
&&
.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 640 PM CDT Sun Mar 17 2024
Low VFR ceilings were occurring across the Northland early this
evening and will stick around for most through the night. Some
occasional flurries will be possible. There will be a
diminishing trend to the clouds from northwest to southeast
through the period. Some of the ceilings may dip back into MVFR
overnight. Lake effect snow will continue tonight into Monday
morning along the South Shore with MVFR/IFR conditions,
especially across the snow belt of Iron County. The lake effect
snow should diminish through the day Monday as winds back.
The gusty winds this evening will diminish overnight as high
pressure builds in. Winds will back through the day Monday and
increase in the afternoon. Low level wind shear may develop late
in the period or more so after 00Z due to a developing low level
jet.
&&
.MARINE...
Issued at 358 PM CDT Sun Mar 17 2024
Gusty northwest winds of 15 to around 20 knots with gusts of 25
to 30 knots this afternoon will continue into the evening before
finally diminishing overnight as a ridge of high pressure builds
into the area. Small Craft Advisories remain in effect until
early Monday morning, after which winds will be less than 20
knots Monday morning. Winds become southwest on Monday afternoon
and increase once again, which may produce another period of
hazardous conditions for small craft Monday afternoon and
evening. Winds switch to the northwest early Tuesday. Winds will
become strong and gusty for Tuesday into Wednesday, bringing
another period of hazardous conditions to the lake. There is a
potential (~20%) for gale conditions Tuesday night along the
North Shore. Winds remain northwest but diminish for Wednesday
night into Thursday.
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...None.
WI...Winter Weather Advisory until noon CDT Monday for WIZ004.
MARINE...Small Craft Advisory until 5 AM CDT Monday for LSZ121-140>148-
150.
&&
$$
UPDATE...Melde
DISCUSSION...LE
AVIATION...Melde
MARINE...LE
Area Forecast Discussion
National Weather Service Indianapolis IN
959 PM EDT Sun Mar 17 2024
.KEY MESSAGES...
- Hard freeze likely tonight, Monday night, and possibly Wednesday
night
- Partly cloudy and cool on Monday; Afternoon sprinkles/flurries
possible NE
- Slight warming trend late week and low rain chances by the end of
the week
&&
.FORECAST UPDATE...
Issued at 959 PM EDT Sun Mar 17 2024
Central Indiana continues to sit amid moderate northwesterly surface
flow...with the region aligned between the eastern-extending surface
ridge axis that has now been pushed south to the Ohio Valley...and
an amplified, H500 trough that will slowly arrive tonight while
being positively-tilted from the central Plains to over top
lingering surface low pressure over Quebec. Briefly impressive
virga field earlier this evening, with a few embedded flurries that
managed to last through the dry boundary layer...has since
diminished, with lingering isolated convection along the CWA`s far
northern/far eastern zones.
Forecast is in good shape for the remainder of the night with
upstream ceilings expected to scatter out as the passing trough`s
axis induces negative differential vorticity advection...as well as
slowly diminishing winds that should be sustained to 10 mph or so
after midnight. Main concern overnight is widespread 20s for
several hours after 500 AM...including a hard freeze for about 6
hours across counties north of the I-70 corridor. As noted in SPS,
scattered early vegetation/growth will be damaged, killed, or
stunted by what should be the lowest readings since perhaps February
29th.
&&
.SHORT TERM (This evening through Monday)...
Issued at 258 PM EDT Sun Mar 17 2024
Synopsis:
Surface analysis early this afternoon shows a ridge axis over
southern IL, extending east across northern KY and then northeast to
western PA. This ridge axis was associated with a much larger area
of high pressure that was centered over Saskatchewan, influencing
weather across the plains and into the Ohio valley. Deep low
pressure was found over Quebec. These two systems were providing a
cold northwesterly flow across Central Indiana, with a moderate
pressure gradient. Aloft, water vapor imagery showed a deep area of
low pressure over Ontario and Quebec. This was resulting in a broad
area of cyclonic flow aloft, with a trough within the northern upper
flow dipping across the northern plains to the Ohio Valley and the
middle Atlantic states. GOES16 shows diurnal CU blossoming across
the forecast area, but more widespread cloud cover was found
upstream over the upper Midwest. Dew points across the area were
mainly in the lower 20s. Although subsidence was allowing for some
readings in the teens to appear.
Tonight...
The Canadian high pressure system to west is expected to push
southward into the plains tonight, continuing to influence the
weather there and across points to the east including Central
Indiana. This will keep dry and cold weather in place across Central
Indiana. Aloft, the upper pattern begins to evolved to a high
amplitude pattern, with strong ridging over the western CONUS and a
deep trough across the east. Lee side subsidence from the ridge is
resulting in the strong building high pressure system across the
plains and Ohio Valley. This keeps cold northwest winds in place
across Central Indiana tonight along with ongoing cold air advection
in place as 850mb temps are suggested to fall to near -10C. Forecast
soundings through the night suggest a dry column, however time
heights suggest some lingering lower level saturation overnight.
Some of the may be due to clouds found upstream over the upper
Midwest along with a upper trough axis passing across Central
Indiana late tonight and early on Monday within the broad cyclonic
flow aloft. Thus all of this should add up to partly cloudy skies
as moisture will remain limited.
Given the cold air in place across Central Indiana along with the
very dry dew points in the teens and lower 20s, lows in the mid 20s
appear on the mark. This will result in a hard freeze tonight.
Although the official growing season has yet to begin, recent warm
weather has allowed for isolated to scattered plant growth. A SPS
was issued earlier to address these concerns.
Monday...
Models suggest the previously discussed high amplitude pattern will
remain across the area on Monday. A broad upper trough axis is
expected to be pushing out of Central Indiana today to the Ohio
River by mid-day, allowing a continued flow of cold northerly flow
aloft. Meanwhile at the surface the very strong high pressure system
to the west is expected to settle across the Central Plains. This
will continue to result in ongoing cold air advection through the
day. HRRR suggests some Lake enhanced precipitation blowing off of
Lake Michigan reaching the north and northeast parts of the forecast
area, including Kokomo, Muncie and Winchester. Confidence for this
precipitation is very low, as the past few days of cold subsidence
has resulted in very dry air within the lower levels. Thus
measurable precipitation seems unlikely, but a sprinkle or flurry,
trace amounts, cannot be ruled out. Thus may carry this mention
during the afternoon across points northeast. Otherwise, look for
partly cloudy skies as forecast soundings reveal convective
temperatures that will be reached along with shallow mid level
saturation with an inversion aloft.
Given the cold air advection and colder start on Monday, Highs in
the upper 30s to lower 40s will be expected.
&&
.LONG TERM (Monday night through Sunday)...
Issued at 258 PM EDT Sun Mar 17 2024
A slight early spring cooldown will continue into the week as broad
cyclonic flow aloft is the dominant feature much of the period. That
said, the cold intrusions into the region will primarily be a
glancing blow, leaving temperatures just a bit below seasonal
normals most days, though in stark contrast to the warmth over many
of the past several days.
A weak impulse in the northwest flow aloft will slide through the
Great Lakes Monday night into Tuesday, but a significant lack of
moisture and northward displacement of the forcing associated with
the wave will prevent any precipitation, with high pressure at the
surface to our west and southwest instead promoting a strong
pressure gradient, and potential for wind gusts as high as 35-40
MPH, particularly during the day on Tuesday.
A reinforcing shot of cooler air arrives in the wake of this wave
late Tuesday night into Wednesday, which may leave Wednesday night
competing with tonight and Monday night as the coolest night of the
week, with lows well into the 20s across the area.
Temperatures will moderate slightly later in the week as flow aloft
becomes less amplified and heights build slightly, though
significant warmth appears unlikely given continued cool northerly
or easterly flow at the surface.
Models disagree somewhat on handling of a couple of impulses which
pass to our north and south Thursday night into Friday and the speed
of a much more amplified low pressure system coming off the lee of
the Rockies late weekend into early next week. Will carry some low
(20-40%) PoPs at times Thursday night into Friday and again Saturday
night onward. Conditions may be just cool enough to allow a few
flakes to fly late in the work week, but nothing impactful appears
likely at this time.
&&
.AVIATION (00Z TAF Issuance)...
Issued at 720 PM EDT Sun Mar 17 2024
Impacts:
- Wind gusts 15-20KT this evening...and again Monday after 15Z
Discussion:
Seasonably strong short wave slowly slicing across the Midwest
tonight along with associated adequately strong low level lapse
rates that will allow lake-enhances clouds/virga early this evening.
Suspect boundary layer too dry to allow more than stray precipitation,
so have left out of TAFs. Both clouds and winds to diminish
overnight...from up to 15-20KT this evening around the scattered
virga...to mainly 10-15KT gusts after midnight.
Modest, diurnally-fueled, lake-enhanced convection to return Monday
morning, with most notable feature increasing cumulus. Suspect any
flurries/sprinkles at this time to remain north/ east of terminals...
ahead of supporting, rather amplified upper trough axis crossing TAF
sites by 16Z...with VFR ceilings lingering through late day. Robust
northwesterly flow should gust to mainly 15-20KT during 15Z-00Z.
&&
.IND WATCHES/WARNINGS/ADVISORIES...None.
&&
$$
UPDATE...AGM
SHORT TERM...Puma
LONG TERM...Nield
AVIATION...AGM
Area Forecast Discussion
National Weather Service Northern Indiana
719 PM EDT Sun Mar 17 2024
.KEY MESSAGES...
- Scattered lake effect snow showers and flurries persist overnight
and throughout the day Monday. Highs Monday in the upper 30s to low
40s with wind gusts up to 25 mph.
- For far SW Lower Michigan and the South Bend/Elkhart area: Lake
effect snow showers will increase in coverage and intensity
overnight through early morning Monday (between 2 to 11 AM EDT).
Snow accumulations 1-2" likely, with locally higher amounts possible.
- Dry and seasonable midweek. Several hard freezes likely tonight
through Wednesday night. Lows in the low to mid 20s.
- Low confidence in rain and snow chances late in the week and
into next weekend.
&&
.DISCUSSION...
Issued at 313 PM EDT Sun Mar 17 2024
Happy St Patrick`s Day! If winter weather is your favorite type of
weather, then today is your lucky day! Temperatures are in the upper
30s to low 40s this afternoon with scattered lake effect
snow/graupel showers. As an upper level low over Ontario departs to
the east, flow has become northwesterly off of Lake Michigan.
The attendant trough of the system swings through tonight, with
a 500 mb shortwave passing over Lake Michigan. RAP soundings
show inversion heights rising to around 8 to 10 kft after 06Z
Monday with increasing saturation in the low levels. 850 mb
temperatures fall to around -10C to -12C, and with lake
temperatures between 3-4C, this is a favorable lake and air
temperature difference for lake effect snow showers to
continue. Additionally, the wind direction will become
increasingly favorable overnight as northwesterly winds shift
to become northerly. A northerly wind direction increases the
fetch along Lake Michigan, and there may end up being a Lake
Michigan to Lake Superior connection that enhances this fetch
even more on Monday morning. Briefly heavy bursts of lake effect
snow showers will continue overnight, increasing in coverage
and intensity in far SW Lower Michigan and the South
Bend/Elkhart area. Hi-res model guidance (the HRRR, RAP, and
NAM) is starting to lock in on this; these models depict a band
setting up over far SW Lower Michigan between 06-09Z Monday.
Should this band setup, it will cause reduced visibilities and
slick spots on roadways/pavement, just in time for the Monday
morning commute. Snow accumulations of 1-2" are possible in
Benton Harbor, Cassopolis, Three Rivers [MI], South Bend, and
Elkhart [IN], with locally higher amounts possible. Elsewhere,
accumulations will only be a few tenths at most.
As high pressure settles in to start the new work week, several hard
freezes are likely tonight through Wednesday night. Lows will be in
the low to mid 20s each night (warmer near 30 degrees along Lake
Michigan). Avoid any outdoor planting in the coming days...if you
have any sensitive vegetation already coming up, be sure to cover it
up or bring it inside, if possible.
Cold air advection continues into early next week as winds remain
out of the north/northwest. Temperatures will be near normal for
this time of year in the upper 30s to mid 40s. A brief warmup is
possible Tuesday as a warm front lifts north, but temperatures only
make it to the upper 40s to low 50s for highs. There will be
intermittent sun and clouds around, as dry conditions prevail
through at least Thursday.
Temperatures remain seasonable late week and into the weekend with
highs in the mid 40s to low 50s. Very low confidence exists for rain
chances late in the week and into next weekend. A clipper system may
bring brief chances for a rain/snow mix late Thursday night into
Friday morning. Long range model guidance then diverges on how to
handle any incoming systems, with some having rain chances over the
weekend and others remaining dry until Monday before another cold
front passes through.
&&
.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 714 PM EDT Sun Mar 17 2024
Snow showers will complicate the forecast for much of the next
24 hours and unfortunately, models are not handling the lake
effect well, making it hard to determine exactly when and where
it will snow. That said, mainly VFR conditions, but could drop
to MVFR or lower visibility in snow, especially at KSBN. Colder
temperatures overnight will allow for slightly better
instability and slight increases in the lake effect snow shower
intensity. KFWA will also see a slight uptick, however with the
location further away from Lake Michigan, should become more
diffuse. A shortwave will move through Monday afternoon with
more snow, though this time, mainly impacting KFWA. Continued
breezy northwest winds with gusts at times of 20 to 25 kts.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...Small Craft Advisory until 11 PM EDT Monday for LMZ043-046.
&&
$$
DISCUSSION...Johnson
AVIATION...Andersen/Cobb
AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
1126 PM EDT Sun Mar 17 2024
.KEY MESSAGES...
- A deep trough passing aloft brings a threat of light snow
showers and flurries on Monday afternoon.
- Freezing conditions tonight and a hard freeze Monday night
could kill any cold sensitive vegetation that has emerged
prematurely due to early season warmth.
- Gusty southwest winds transport warmer air into the region on
Tuesday, but dewpoints are slower to rise leading to low
afternoon relative humidity and Fire Weather concerns.
- Temperatures rebound back to near normal for Wed and into next
weekend, with lower confidence in the next potential chance of
precipitation moving in towards the end of the work week.
&&
.UPDATE...
Issued at 1126 PM EDT SUN MAR 17 2024
The forecast remains on track. A surface trough axis has worked
southeast of the area, with an uptick in wind gusts in the 20 to
25 kt range noted at some of the observation sites. These winds
will be diminishing through the overnight, as the better pressure
gradient pushes closer to the Appalachians with time. Forecast
lows in the upper 20s to lower 30s still look on track. Mainly
updated the hourly temperatures and dew points once again through
the overnight. Updates have been sent.
UPDATE Issued at 806 PM EDT SUN MAR 17 2024
Thicker high clouds will exit off to our east early this evening,
with some higher-based cumulus also generally drying up to our
north with sunset. Gustier west winds will also gradually
diminish through the evening, hanging on the longest on ridgetops
and more open areas north. The forecast remains on track early
this evening, and have only freshened up the sky cover through
midnight, as well as adjusted some of the hourly temperatures to
better match the trend in the observations.
&&
.SHORT TERM...(This evening through Monday night)
Issued at 357 PM EDT SUN MAR 17 2024
As of mid afternoon, an upper level low was centered near the
Ontario and Quebec border with an associated upper level trough
extending into the Great Lakes, Upper and mid MS Valley regions, and
much of the eastern Conus. Further west, an upper level ridge
extended from the eastern Pacific into the Northwest, portions of
western Canada, and into portions of the Northern Rockies. A closed
low was centered southwest of the Four Corners region in AZ with
a series of weaker shortwaves in west to southwest flow from
Mexico across the Southern Plains to the Gulf Coast states. At the
sfc, an area of low pressure associated with the upper level low
near the Ontario and Quebec border with a triple point low over
northern ME and a trailing cold front near the eastern seaboard to
the Delmarva and then southwest to northern portions of the Gulf
Coast states to TX. Another boundary was further south from east
of the coast of the Carolinas across the Gulf Coast region to the
lower portions of the Rio Grande valley and then into Mexico.
Meanwhile, a ridge of sfc high pressure was centered near the
Saskatchewan and Manitoba border and extended through the Northern
to Central Plains and also extends east into the Lower OH Valley.
This evening through Monday, the upper level low is progged to track
east and northeast toward the Maritimes while the axis of the 500 mb
trough is expected to rotate across the St Lawrence valley and Great
Lakes to the Northeast Conus to Mid Atlantic states and portions of
the OH Valley and to the southern Appalachians through sunset on
Monday evening. The axis of this trough will shift east of the
area to end the period while mid level height rises occur across
the OH Valley including the Commonwealth. At the same time, the
sfc ridge of high pressure is expected to build south across the
Plains and into the Lower OH Valley and TN Valley as well as the
Lower MS Valley to end the period.
As the 500 mb trough axis/shortwave approaches on Monday and Monday
evening, moisture is expected to increase generally in the 850 mb to
700 mb layer. At the same time, cold air advection that is ongoing
at present will have continued through tonight and through the day
on Monday as well. Daytime heating combined with the gradual cooling
aloft will lead to development of rather high based cumulus and
stratocumulus. Saturation to the DGZ is anticipated with much of
the cloud depth potentially residing within it Monday afternoon
to early Monday evening. A dry subcloud layer and dry adiabatic
lapse rates should support what precipitation that falls from the
rather high based cumulus either sublimating or reaching the
ground as snow flurries despite temperatures that may be near 40
or in the lower 40s in locations below 2500 feet elevation.
Overall, based on the trends in coverage from the 12Z HRRR and 12Z
Namnest, the coverage of potential for flurries was expanded to
include most of the area on Monday afternoon, especially from near
Interstate 75 and points east.
The main forecast concern of the period is anticipated scattering
of clouds and clearing as winds slacken on Monday night. This
should lead to lows well down into the 20s, which ordinarily is
not impactful. However, recent mild weather has led to some
vegetation prematurely emerging and any such vegetation will be
susceptible to the below freezing temperatures. Although the
official start of the growing season has yet to begin, in
consideration of this this threat has been added to the HWO. Some
locations will also experience sub freezing temperatures for the
upcoming night as well. With the cold airmass and 850 mb
temperatures falling from the -5C to around -10C range to about
-7C to -9C on Monday evening, highs Monday will be below normal
and more typical of mid January highs. Normal highs for this time
of year are in the mid to upper 50s.
.LONG TERM...(Tuesday through Sunday)
Issued at 332 PM EDT SUN MAR 17 2024
The primary forecast concerns in the extended will be the potential
for low dewpoints and very dry conditions across the area on Tuesday
and generally above normal temperatures. With winds still expected
to be blustery and perhaps a bit gusty to begin the period, there
could be some fire weather concerns for eastern Kentucky. This
threat has been highlighted in the HWO. A ridge of high pressure
will be the dominant weather system to start, but a weak area of
low pressure passing by to our south, will bring rain chances back
into the picture late in the week and into the upcoming weekend.
The overall large scale upper level pattern to begin the period will
feature a trough of low pressure moving slowly into and across the
Desert Southwest and across the southern CONUS over time. This will
be the system that brings rain to our area toward the end of the
period. High pressure will dominate the weather of the southeastern
CONUS initially, but another expansive trough of low pressure is
forecast to dive southward out of Canada Wednesday and Wednesday
night. Since it appears this system will be moisture starved, we
should see nothing more than scattered clouds across the area as
this system moves through aloft to our north and northeast. The
southern stream trough mentioned earlier, will be our next weather
maker Thursday night through Sunday. Another weak northern stream
system might also be moving through during this time, and could
influence our weather as well, but the southern stream low still
looks like the main show.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
ISSUED AT 806 PM EDT SUN MAR 17 2024
VFR conditions are expected to prevail through the period. Some
higher-based cumulus will diminish through this evening across the
norther portion of our area, affecting mainly KSYM. The rest of
the area will see a general diminishment in the high clouds
through early Monday. A passing deeper upper level disturbance will
move through the region during the day on Monday. This will bring
scattered to broken clouds ranging from 4-6k feet agl, with
perhaps a fleeting sprinkle or flurry possible. Winds will
continue to be the main aviation concern at the terminals. West
winds of 5 to 10 kts, with gusts of 15 to 20 kts, will diminish at
most locations early this evening. The gusts will hang on longer
at KJKL and especially KSYM. Winds will become more northwesterly
with time. Northwest winds will increase to around 10 kts, with
gusts of 15 to 20 kts by mid to late morning, as deeper mixing
commences across the area.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...GEOGERIAN
SHORT TERM...JP
LONG TERM...AR
AVIATION...GEOGERIAN
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
909 PM CDT Sun Mar 17 2024
.KEY MESSAGES...
- Light flurries with wind gusts 20 to 25 mph through this
evening. There is a slight chance (20 percent) for a dusting
of lake effect snow in Porter Co. Indiana
- Breezy and drier conditions on Tuesday
- Period of accumulating snow possible Thursday night into
Friday morning (mainly along/north of I-88)
&&
.UPDATE...
Issued at 909 PM CDT Sun Mar 17 2024
Forecast remains on track this evening with no notable changes
made.
A positively tilted upper-level trough continues to pivot
overhead this evening which has allowed mid-level stratus to
fill in across northeast IL and northwest IN. While light radar
echoes have persisted beneath the stratus, flurries have thus
far struggled to reach the surface due to a large amount of dry
air within the sub-cloud layer. However, recent vapor soundings
out of MDW are showing this low-level dry air eroding which may
allow flurries to become more prevalent over the next couple of
hours. Despite the current near freezing temperatures and mid
to upper 20s forecast overnight, no accumulation is expected
with the flurries as pavement and ground temperatures are likely
to remain above freezing.
Scattered lake effect snow showers are also expected to develop
after midnight across portions of northwest Indiana, mainly
Porter County. Forecast soundings continue to show decent lake
effect parameters developing overnight, but the west-northwest
winds aloft are expected to keep the bulk of the showers into
northern Indiana and Lower Michigan. Nevertheless, the
advertised 20% POPs for portions of Porter County remain
reasonable. Similar to the flurries, accumulations are generally
expected to be nonexistent (at least on paved surfaces) but some
light accums up to a tenth or two on grassy surfaces cannot be
completely ruled out, especially with more robust lake effect
bands.
The lake effect showers should gradually push east of Porter
County shortly after daybreak but a secondary wave pivoting
through the aforementioned trough does look to support
additional chances for flurries areawide through Monday
afternoon. Though no accumulations are expected. Otherwise,
expect another blustery afternoon with highs in the upper 30s
and northwest gusts of 20 to 25 mph.
Yack
&&
.DISCUSSION...
Issued at 239 PM CDT Sun Mar 17 2024
An upper level trough will continue to dig southward overnight
and shift eastward on Monday morning. Lingering flurries are
possible over northeastern IL, but no accumulations are
expected. The focus becomes over northwestern Indiana, primarily
in Porter County, where good northwest fetch, decent lake
induced instability, and equilibrium levels up to 8000 feet can
produce a few additional lake effect snow showers. Temperatures
have been in the upper 30s (a few isolated low 40s) this
afternoon, so most areas are not expected to receive
accumulations. But with temperatures expected into mid 20s
overnight, there is a chance for a tenth or so of snow
accumulations in Northwest Indiana but it will be dependent upon
how quickly surface temperatures can cool overnight. Current
thinking for any banded features that can created higher totals
look to be farther east in Indiana or in Michigan, but will be
monitored through the night.
Another short wave will drop south as the parent long wave
phases and moves east on Monday. Moisture profiles on most
models remain too dry; however, the HRRR and the RAP are the
more aggressive reintroducing snow showers. While they have been
aggressive, even today, they have trended better with handling
moisture profiles. Rather than biting too hard for snow
showers, the slight chance for flurries was introduced for late
tomorrow morning/afternoon with no accumulations expected, but
can always be increased if later model runs come into better
agreement.
Clouds start to move out of the region for better chances for
clearer skies on Tuesday. However, another robust low level jet
is expected to develop Monday night into Tuesday morning over
the region. With deeper mixing this can make for another windy
day with the potential for gusts to be in excess of 30 mph.
Additionally, drier conditions are expected to develop with RH
values into the 40s and upper 30 percent. The combination of
lower relative humidity levels and stronger wind gusts could
set the stage for the potential for an elevated fire risk
threat.
By mid week, northwest flow sets up over the area with cooler
temperatures to the northeast and warmer temperatures to our
southwest. However, models have trended that baroclinic zone
farther south with has translated in cooler yet seasonal normal
high temperatures through the week. By Thursday, a short wave
clipper will drop down out of Canada providing the next chance
for precipitation. There is still uncertainty with the exact
path, but it looks like it could be the next chance for
precipitation. Colder temperatures north of I-88 Thursday night
into Friday provides better chances for snow, while the chance
for slightly warmer temperatures south of I-88 could lead to a
rain snow mix.
Temperatures are slated to warm over the weekend. However, with
the potential for another wave move over the Plains over the
weekend, it looks like the region might be in store for a more
unsettled pattern.
DK
&&
.AVIATION /00Z TAFS THROUGH 06Z MONDAY/...
Issued at 619 PM CDT Sun Mar 17 2024
There are no significant aviation weather concerns through the
period.
Occasionally gusty northwest winds will continue to gradually
ease this evening. While gusts may become fairly infrequent
tonight, gusts around 20 knots should return on Monday.
Otherwise, while a few flurries are possible tonight, low-level
dry air seems to be largely winning out at this time with
most/all flurries sublimating before reaching the ground.
Another weak disturbance will rotate overhead on Monday which
may yield another chance for intermittent flurries, so no
changes were made to the inherited PROB30 groups.
Carlaw
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...Small Craft Advisory until 10 PM CDT this evening for Winthrop
Harbor IL to Gary IN.
Small Craft Advisory until 10 PM CDT Monday for Gary to Burns
Harbor IN-Burns Harbor to Michigan City IN.
&&
$$
Visit us at weather.gov/chicago
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
630 PM CDT Sun Mar 17 2024
.KEY MESSAGES...
- Elevated fire weather conditions will persist through the
middle of the work week (especially on Tuesday).
- Strong winds return Tuesday, with NW gusts up to 40 mph
possible.
- Confidence is increasing in the potential for accumulating
snow across the region Thursday.
&&
.DISCUSSION...
Issued at 254 PM CDT Sun Mar 17 2024
Lucky or not, Winter has returned to the Upper Midwest to close the
weekend. Air temperatures have struggled to break out of the 20s
thanks to persistent northwest flow and widespread stratus overhead.
12z MPX RAOB captured the stratus layer aligned within the DGZ
around 5k ft, which has combined with moderate low-level omega
forcing to squeeze out periodic flurries across the area. Lows will
dip into the teens tonight and wind chills are projected to slide
into the single digits by daybreak. Low clouds will gradually
decrease in coverage tonight into tomorrow, revealing some
sunshine for Monday. Despite this, temperatures are forecast to
remain below normal, in the mid to upper 30s, given the cold
airmass aloft. Minimum RH`s will fall between 20-25%, elevating
weather concerns.
Not much has changed with forecast expectations on Tuesday. A
shortwave originating over south central Canada is progged to drift
southeast into the north central CONUS within the expansive region
of broad northwesterly flow. The associated surface low is expected
to track from roughly northwest Minnesota towards central Wisconsin.
A baroclinic zone will develop west of the surface low, with a
thermal nose set to drift east by way of warm air advection early
Tuesday. This will bring a notable one-day warm up, with highs back
above normal in the mid to upper 40s and low 50s. Surface winds will
turn northwesterly as the low passes to the east, with gusts near 40
mph due to the expected tight pressure gradient. Given the forecast
winds near advisory level, attention will also turn back to fire
weather concerns. The strong winds will combine with low minimum
RH`s and very dry fuels to increase the fire threat Tuesday
afternoon/evening. Cold advection will flip the temperature scenario
back to the cold side of things for Wednesday, with below normal
highs back in the low to mid 30s.
Active weather is set to return in the form of snow on Thursday. As
with any weather system 3-4 days out there is a level of uncertainty
that remains present, however the expected atmospheric scenario
will be favorable for potential accumulating snow. Guidance
advertises a dip in the 500 mb flow over Montana and the Dakotas
heading into Thursday, with an 850 mb shortwave set to eject east of
the Rockies. Warm air advection will increase ahead of the
shortwave, such that a notable mid-level thermal gradient will
develop across the Northern Plains. Forcing associated with the flow
of Pacific moisture and isentropic upglide will aid in the likely
development of a northwest to southeast oriented swath of
precipitation across the Upper Midwest, positioned to the north of
the 850 mb frontal boundary. Blended solutions place this swath of
snow right across central Minnesota, though there are still
north/south solutions on the table that will need to be resolved
before discussing snowfall amounts. QPF expectations remain somewhat
in flux, given significant differences among the Grand Ensemble
membership. The GEFS suite remains the wettest, with several members
in the 0.3"-0.5" range. The EPS and Canadian suites are drier, with
0.1"-0.3" of QPF available to work with. As with any
thermodynamically driven Winter event, there will be a frontogenic
component to the snowfall forecast (where enhanced banding of snow
may occur), however that precise axis will take several more
forecast runs to fine tune. To sum it all up, it appears
increasingly likely that snowflakes will fly and accumulate in some
fashion Thursday, which has been reflected in the latest PoPs from
the NBM (pushing 70% across central Minnesota). Specifics with
regards to snowfall amount, timing, intensity, and impacts will come
into a better picture in the coming days. Should the forecast
continue to trend in this direction, travel impacts will become
likely Thursday. Stay tuned!
As discussed by the midnight shift, Thursday continues to serve as a
prelude for what is to follow. Naturally, this is also the part of
the forecast where the specifics begin to fall off the table, but
guidance suggests next weekend bears watching for a more substantial
round of widespread precipitation and possible wintry weather. There
is good support across the ensembles that a deep trough will move
over the west coast next weekend, followed by the development of a
surface low pressure system in the Great Plains. Notable differences
in the track of the surface low exist, and will have further
implications on things like precipitation type and amount. Despite
the understandable challenges regarding many details, the big
picture idea is impressive and will require further updates
given such a strong signal this far out (NBM already features >
50-70% PoPs next Sunday!). While a large amount of uncertainty
does exist, the more active pattern that appears to be setting
up will benefit ongoing dry conditions. We`ll take what we can
get!
&&
.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 616 PM CDT Sun Mar 17 2024
Based on satellite observations and what we`re seeing with RAP
soundings, we`re going to spend much of the night with SCT-BKN
stratocu between 4k and 5k feet. These clouds will clear out
Monday morning, but be replaced by a batch of mid level clouds
Monday afternoon. Overnight, high pressure will slide south
through the eastern Dakotas, so we`ll never have a period where
we loose the wind, though the gustiness will gradually diminish
through the evening. Given the track of the high, winds will be
trending toward westerly and eventually WSW by Monday
afternoon.
KMSP...Given the forecast wind direction, cross winds will
begin appear in about 24 hours. Some gusts into the low 20s will
be possible with these cross-winds as well.
/OUTLOOK FOR KMSP/
TUE...VFR. Wind NW 20G35kts.
WED...VFR. Winds NW 10-15G20kts.
THU...IFR/-SN likely. Some accumulation likely. Wind E 5-10 kts.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...None.
WI...None.
&&
$$
DISCUSSION...Strus
AVIATION...MPG
Area Forecast Discussion
National Weather Service Pittsburgh PA
802 PM EDT Sun Mar 17 2024
.SYNOPSIS...
Scattered snow showers are expected on and off through Tuesday
morning with a crossing upper trough. Dry weather is then
expected as temperatures will gradually warm mid to late week.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
KEY MESSAGES:
- Lake enhanced showers continue mainly north of Pittsburgh
- Colder temperatures arrive tonight, especially over the
southern half of forecast area
-------------------------------------------------------------------
Deep and cold trough over the Great Lakes will gradually move south
overnight. 500 mb heights will fall another 70 meters or so as
a result. The column will continue to cool and especially the
boundary layer, with 850 mb temps falling from about -4C this
evening to -11C in the PIT area by 12z Monday.
Coverage of snow showers is expected to become more sparse
overnight with the loss of diurnal heating. However, cooling
temperatures and the loss of insolation will increase the
possibility of light accumulations overnight, especially along
and north of I-80. A light dusting to perhaps a brief half inch
is possible for those locations.
Hourly temperatures, PoPs, and sky cover were refreshed with the
latest hi-res blend, but otherwise, no significant changes were
needed for the overnight period.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
KEY MESSAGES:
- Cold and unstable under upper trough with showers of snow and
graupel.
- Potential for light snow accumulation, mainly north of I 80
and in the higher terrain
-------------------------------------------------------------------
Upper trough will start the day over northwest Ohio and Lake
Erie, moving to western PA and WV by the late afternoon.
Strongest height falls of 150 meters will be over VA.
A very cold and unstable airmass is expected given we have mid
March sun angle. 850 mb temps will be around -10C, 700 mb -18C,
and 500 mb dropping to around -35C. RAP soundings show moist and
unstable situation with diurnal heating under trough with
increasing moisture and even 100-300 j/kg of CAPE. Cloud tops
will be in the -20 to -25C range, so vigorous convective snow
showers are expected which certainly could produce brief heavy
snow bursts and graupel. Accumulations outside of ridges will be
limited by March sun angle. However, with convection continuing
into the evening, there is certainly the potential for
accumulations north of I-80 and over the ridges Monday night.
CIPS analogs indicate that the WV ridges have a 30-50% chance of
4" or more in patterns like this. At this point expect 2-3" in
those areas so expect a sub-advisory event especially during the
daylight hours.
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
KEY MESSAGES:
- Near normal temperatures expected Tuesday through Friday
- Mainly dry weekend with moderating temperatures
----------------------------------------------------------------
As heights gradually rise and flow turns from northwest
to westerly aloft, a low pressure area over the Great Lakes
will skirt mainly north of the forecast area as it heads toward
Ontario/Quebec/New England Tuesday into Wednesday. Certainly
could be snow in the northern half, especially Tuesday morning,
but the system will have limited moisture so the precipitation
shield is more likely to impact New York and far northern PA.
Flow gradually tilts from westerly to southwesterly as the week
progresses with gradually rising heights and moderating
temperatures. While near normal readings are expected most of
the week, moderation begins over the weekend with highs in the
50s Saturday and Sunday.
&&
.AVIATION /00Z MONDAY THROUGH FRIDAY/...
General VFR forecast with the exception of FKL and DUJ which
will see occasional MVFR conditions with snow showers. Gusty
winds will continue through the night, but should weaken as the
night progresses.
Snow showers will become more prevalent and widespread on
Monday. Difficult to pinpoint when and where they will hit, with
FKL and DUJ having the highest probabilities to see restrictive
vis/cigs. Winds gusts are again possible on Monday, but not as
strong as today.
.Outlook...
VFR returns Wednesday and Thursday as a ridge of high pressure
builds in
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...None.
OH...None.
WV...None.
&&
$$
SYNOPSIS...Rackley
NEAR TERM...Craven/Rackley
SHORT TERM...Craven
LONG TERM...Craven
AVIATION...Craven
Area Forecast Discussion
National Weather Service Reno NV
119 PM PDT Sun Mar 17 2024
.SYNOPSIS...
Mostly dry conditions and warmer temperatures are expected continue
for the region through the middle of week with the exception of a
slight chance for some isolated non-severe thunderstorms in western
portions of the area on Tuesday. Better wintry precipitation chances
and cooler temperatures look to return to region towards the end of
the week.
&&
.DISCUSSION...
The latest RAP analysis for today shows an upper air high over the
western OR/WA border and an upper air low over AZ placing the CWA
somewhat between these two features. Forecast models depict the high
moving south and departing from WA overnight into Monday with the
low staying in place over AZ. The high`s southward progression
continues through Monday with the high moving over northern portions
of the CWA by the evening hours as the low backs up a bit into
southern CA. For Tuesday, forecast guidance shows the high moving
south across the CWA causing the low to start making its way east by
the late afternoon hours. On Wednesday, models place the CWA
underneath an upper air ridge while a low in the Pacific Northwest
moves south-southwest well off the Northwestern coast of the CONUS.
For Thursday, model guidance has the CWA still underneath the upper
air ridge though the ridge is projected to move east late in the day
with the Pacific low moving eastward towards the coast. By Friday,
models show the CWA taking a southwesterly flow aloft as this low
moves towards the shore of the Northwestern CONUS. However, the
ECMWF is quicker than the GFS in the eastward progress and opens the
low into trough by Friday evening with the trough axis passing over
the CWA on Saturday. The latest run of the GFS delays this evolution
almost by 24 hours by showing the low opening into a trough on
Saturday evening over the coast of OR/WA and having the trough`s
axis pass over the CWA on Sunday morning. Due to these timing
differences, the upper air pattern remains a bit uncertain at this
time and will continued to be monitored for better consistency to
improve on future forecasts.
At the surface, the region is expected stay mostly dry through the
rest of today and on Monday as well with relatively light winds and
not too much cloud cover. The SPC general thunderstorm threat looks
to have shifted well southward and out of the CWA in their latest
outlook for Monday. While Tuesday looks to be similar to the
previous two days with temperatures on a warming trend, there
appears to be a slight chance (10-15%) for an isolated non-severe
thunderstorm for portions of the Tahoe Basin area along with western
Mono County during the afternoon hours due to a low near the AZ/CA
border. The latest NAM run shows middle level lapse rates in these
areas at the time that look supportive of this possibility with some
low CAPE values (less than 500 J/kg), so will continue to monitor
these chances should they change. The latest EFI (Extreme Forecast
Index) for CAPE continues to highlight these areas though more so
areas to the west of the CWA on Tuesday as well. Dry conditions look
to return on Wednesday with the second day of northwestern NV
portions of the region possibly seeing daytime highs reaching the
lower 70s.
Beginning Thursday, cloud cover looks to increase over the area
allowing for some slightly cooler daytime temperatures. Western
portions of Lassen County also have a slight chance (10-15%) for
some precipitation late on Thursday. Better precipitation chances as
well as coverage are expected on Friday with the Sierra Mountain
having a 40-60% chance for precipitation that looks to be a P-type
of snow. The latest NBM probabilities show a 25-50% chance for 2
inches of snow or more particularly in the crests by Saturday
morning. Northwestern NV sees a 10-20% chance for light rain with
some light snow potentially mixed in. Models do show a cold front
passing through the region late Friday/early Saturday though the
exact timing is uncertain. As a result, a cooling trend begins for
the area going through the weekend. Currently, wintry precipitation
chances (around 15-60%) look to continue as well with the Sierra
Crest seeing the higher chances and the eastern portions of the CWA
seeing more towards the lower end of the range. But there are a lot
details on next weekend`s weather that remain uncertain due to the
unsettled upper air pattern mentioned earlier in the discussion.
-078
&&
.AVIATION...
VFR conditions are expected at all terminals within the region for
the rest of today with dry conditions and relatively light winds.
While these conditions looks to continue going into Monday, there
may be some light showers and isolated thunderstorms west of the
Sierra Crest outside of the area later in the day. There is a slight
chance (10-15%) for western portions of the region in the Sierra
Mountain seeing some isolated thunderstorms on Tuesday afternoon
though VFR conditions and light winds are anticipated for most of
the region.
-078
&&
.REV Watches/Warnings/Advisories...
NV...None.
CA...None.
&&
$$