Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/05/23
Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
801 PM CST Sat Mar 4 2023
.UPDATE...
Issued at 759 PM CST Sat Mar 4 2023
Only minor updates this evening. Will be interesting to see what
00z CAMS look like considering the incoming storm. The latest HRRR
remains much more bullish over ND for snowfall. Hopefully the
models will come together or at least converge some tnt.
&&
.SHORT TERM...(This Evening through Monday Afternoon)
Issued at 302 PM CST Sat Mar 4 2023
Some troubling developments today concerning the storm system
impacting us Sunday and Monday. CAMs/hi-res guidance has come in
much further north with snowfall, nearly to the point where not much
more snow falls after the initial warm air advection push of snow
Sunday morning. Interesting to note the 18Z HRRR has most of the
snow along and north of I-94! These recent developments are
worrisome, although the global models/ensembles maintain their
further south solutions and still bring northern parts of the CWA
moderate to heavy accumulations of snow. It was generally agreed
upon to lean more towards the global solutions and not buy much into
this sudden northward shift, although it`s a development to be
closely monitored. Generally went with WPC QPF, but NBM QPF is much
lower, and if these northern trends continue, we`re forecasting too
much snow. 18Z NAM coming in and it`s back south again from its
northward 12Z run and bringing snowfall back into northern SD again.
For this forecast, generally went with a 50/50 WPC/NBM QPF blend
while also blending with neighbors, just to bring in some degree of
this potential northward/drier trend, even though it`s somewhat in
doubt. Even with blending in lower QPF, snow accums still give
warning, or near warning criteria over north central SD, so upgraded
to a warning there. Left the watch in place further east in hopes
models settle down overnight and a decision can be made on advisory
or warning.
.LONG TERM...(Monday Evening through Saturday)
Issued at 302 PM CST Sat Mar 4 2023
The long term is going to be pretty active with a constant chance
for light snowfall.
Starting with a brief overview of the atmosphere, Monday night,
upper level (300-200mb) flow hints at a slight ridge pattern. This
ridge continues to amplify through Friday when it starts to move out
and a trough moves in. This upper level low becomes cut off Saturday
morning. The GFS keeps the ridge over our area through Saturday
afternoon and moves a deep low into the region Sunday. Moving down
to the 500mb level, Monday has a lot of shortwave energy from a low
centered over our CWA (the EC has the center slightly farther east
over MN). This low moves east quickly while still trailing energy
behind it. A ridge move in Tuesday but is much more amplified over
ND than our area. On the upwind side of this ridge, there is
abundant energy reaching up from WY. This combines Tuesday night and
into Wednesday with energy from a negatively tilted trough from
southern Canada. We then transition to a southwesterly to southerly
flow pattern for Thursday and Friday, but there will continue to be
energy flowing into the region from the south and west. Down at
700mb the air is pretty dry from Monday evening through Tuesday
morning. Moisture moves in through the day Tuesday and the air stays
relatively moist through Saturday morning. The GFS moves in some
drier air Wednesday night through Thursday morning, but this would
be consistent with the ridge lingering a little longer. The rest of
the period stays dry at 700mb. At 850mb, the air stays relatively
moist through Saturday morning. then the EC dries out a lot, but the
Canadian is a little slower to move in the dry air. There is also a
low that moves to our south on Friday. Models are not consistent on
its placement as of right now. Finally, 925mb. Moisture will be
abundant throughout the whole period. The EC and Canadian models
have the surface low centered over KS on Friday morning.
Now for some details with snow. Right now it looks like there will
be a break Monday night into Tuesday morning. Once the mid layers
saturate, the chance for light snow returns. Tuesday, the highest
snow accumulations are currently expected for areas along and west
of the James River. Thursday through Friday, expect heavier snowfall
amounts across southern and western counties.
On the wind side of things, Monday evening is looking to be pretty
breezy with gusts up to 35kts east of the MO. This could cause
blowing snow to be an issue. After Tuesday morning, the long term
period is not expected to be any windier than normal. Temperatures
will be 10 to 15 degrees below average for this time of year.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday Evening)
Issued at 508 PM CST Sat Mar 4 2023
Terminals KABR,KATY,KPIR,KMBG
VFR skies/vsbys will gradually be replaced with areas of IFR/MVFR
cigs/vsbys after midnight as a band of snow develops eastward over
the forecast area.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...Winter Storm Watch from Sunday morning through Monday morning
for SDZ006>008-011.
Winter Storm Warning from 3 AM CST /2 AM MST/ Sunday to noon CST
/11 AM MST/ Monday for SDZ003>005-009-010.
MN...Winter Storm Watch from Sunday morning through Monday morning
for MNZ039.
&&
$$
UPDATE...TDK
SHORT TERM...TMT
LONG TERM...KK
AVIATION...TDK
AREA FORECAST DISCUSSION
National Weather Service Albany NY
940 PM EST Sat Mar 4 2023
.SYNOPSIS...
Rain and snow showers this afternoon finally come to an end
tonight. Mostly cloudy and seasonably mild conditions continue
into tomorrow with winds turning breezy. There may be a few
isolated rain or snow showers, mainly in the higher terrain.
Then, the sun finally returns on Monday as high pressure builds
overhead. Another weak disturbance is possible Monday night
into Tuesday but there remains uncertainty.
&&
.NEAR TERM /THROUGH SUNDAY/...
.UPDATE...As of 940 PM EST, area of low level convergence now
shifting slightly eastward, mainly from the immediate Hudson
River Valley east into western New England. These areas will
remain susceptible to patchy light snow or flurries through
midnight, and with cloud depths relatively shallow, lack of ice
in the clouds could also allow for some patchy drizzle/freezing
drizzle during this time, so added some mention and will also
address through an SPS. Low level convergence should slowly
decrease after midnight, allowing for decreasing coverage of any
light precipitation.
Temps have been slow to drop thus far due to the cloud cover,
however still expecting temps to gradually drop off after
midnight, although some valley areas could remain elevated (in
the lower 30s).
Otherwise, boundary layer remains quite moist, and with
persistent low level inversion in place, low clouds are expected
to persist much of the night. However, should any breaks
develop, there could be some patchy dense fog developing, and
will therefore watch trends through this evening.
PREVIOUS [408 PM EST]...Temperatures have warmed as expected
into the low to mid 30s through much of the region with some
lingering snow or rain/snow showers as moisture from the parent
cyclone continues overhead. Between the marginal temperatures,
weak shower intensity and that pesky March sun angle, additional
snow accumulations have been minimal in the higher terrain and
nearly nothing in the valley. We therefore have cancelled all
winter storm warnings and winter weather advisories.
As we approach the late afternoon and head into early evening,
an additional shortwave on the backside of the parent cyclone
will likely produce one last period of more organize precipitation
through 03 UTC, especially in the southern/western Adirondacks,
southern Greens, Mohawk Valley and Upper Hudson Valley. However,
given marginal temperatures in the low to mid 30s through
sunset, any additional accumulations should hold off until after
dark and even then only amount to coatings up to 1 inch.
Beside the incoming shortwave, latest observations show winds
down the Hudson River are oriented from the north-northeast
while winds down the Mohawk River appear to be from the west.
This set-up in the wake of an exiting open shortwave suggests
that some MHC (Mohawk Hudson Convergence) is possible and earlier
runs of the RAP actually hinted at this in the 21 UTC SAT to 00
UTC SUN timeframe. We will continue to monitor observations.
After 03 UTC, winds shift to the northwest in the wake of the
shortwave so some additional upslope snow showers are possible,
especially along the spine of the southern Greens.
Otherwise, mostly cloudy skies continue overnight with
temperatures not turning too chilly thanks to the clouds. Lows
only expected to drop into the mid to upper 20s.
Morning clouds on Sunday could break for some partial afternoon
sunshine but with additional mid-level moisture tracking into
the area along with some weak upper level forcing, breaks of
sun should be limited to just valley areas. With high pressure
building to our west, sfc winds turn rather breezy with sustained
winds 8 - 15kts and gusts up to 25kts. The increased winds
should enhance boundary layer mixing and assist temperatures
turn mild again with highs reaching into the low to mid 40s in
the valley with mid to upper 30s elsewhere. A few rain/snow
showers are possible as well from the incoming weak impulse and
moisture but any showers should mainly be reserved to the higher
terrain in the southern Greens, northern/eastern Catskills and
southern Adirondacks.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/...
High pressure continues building eastward Sunday night allowing
clouds to finally clear towards morning with temperatures
turning a bit cooler. However, with northwest winds stay a bit
breezy, temperatures should stay elevated with lows only in the
mid to upper 20s.
Monday will be a pleasant day with morning sunshine fading
behind some increasing afternoons. Otherwise, temperatures
should be mild once again with highs in the mid to upper 40s in
the valley and mid to upper 30s elsewhere. We will be monitoring
our next potential disturbance arriving Monday night into
Tuesday morning but there remains uncertainty in the
deterministic guidance so this remains a low confidence
forecast. Latest forecast shows the potential for a weak clipper
type low to track across PA/NJ with its northern fringe
possibly grazing the southern half of our forecast area (I-90
southward). The GFS, CMC and ECWMF are in decent agreement with
this solution but the NAM shows the system tracking further
north into our area but as of now is the outlier.
Depending on the exact timing, some wintry mix looks possible
from this clipper. Still uncertainty though as the best forcing
looks limited to the mid-levels while the better moisture is in
the low-levels. Forecast soundings suggest if the mid-levels
are dry and sfc temperatures cold enough, some freezing rain is
possible due to the lack of ice nuclei in the clouds. Will
continue to monitor trends but given ongoing uncertainty,
removed any wintry mix wording from the Mon night - Tues A.M
forecast and maintained rain/snow wording. We trended POPs
downward Tuesday afternoon as the clipper looks to exit but
temperatures should be turn colder in comparison to the mild
start to the week. Highs only rise into the mid to upper 30s
with 20s in the hill towns and high terrain.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
The long term forecast period will feature mainly dry weather with
high pressure in control over the area. Will have to continue to
monitor trends and keep close tabs on a storm system that could
bring precipitation to the region next weekend.
Temperatures are expected to run near normal levels during this
period with daytime highs in the upper 30s to lower 40s and
overnight lows in the mid 20s to lower 30s (cooler higher
elevations).
&&
.AVIATION /03Z SUNDAY THROUGH THURSDAY/...
Through 00Z Monday...Current KENX radar shows a light band of
rain/snow showers moving across the KALB terminal. Mixed
precipitation in the form of drizzle is currently being reported
from the ASOS which will likely continue for the next hour or
so. Elsewhere, light snow that was previously reported at KGFL
and KPSF has dissipated, restoring unrestricted visibility. KGFL
still holds IFR ceilings and KPSF has MVFR ceilings, though KGFL
will likely improve within the next hour. KPSF will likely have
light snow as the band of showers moves into its terminal from
the northwest, brining the brief return of potential IFR
ceilings.
Throughout the 00z TAF period, ceilings will teeter on the
border between low VFR and high MVFR due to left over enhanced
low level moisture trapped at the surface due to the current
inversion. While stratus are not likely to break at any point
during the period, multiple guidance resources hinted that KGFL
could experience reduced visibility at some point over night due
to mist. So, added a brief TEMPO group between 05-08z with 6SM
visibility in order to account for the possibility. Elsewhere,
visibility will be unrestricted.
Winds throughout this period will be out of the west/northwest
at magnitudes ranging from 5-10 kt.
Outlook...
Sunday Night: No Operational Impact. NO SIG WX.
Monday: Low Operational Impact. Breezy. NO SIG WX.
Monday Night: Moderate Operational Impact. Chance of SHSN.
Tuesday: Moderate Operational Impact. Breezy. Chance of SHRA...SHSN.
Tuesday Night: Low Operational Impact. Breezy. NO SIG WX.
Wednesday: No Operational Impact. NO SIG WX.
Wednesday Night: No Operational Impact. NO SIG WX.
Thursday: No Operational Impact. NO SIG WX.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
MA...None.
VT...None.
&&
$$
SYNOPSIS...Speciale
NEAR TERM...KL/Speciale
SHORT TERM...Speciale
LONG TERM...Evbuoma
AVIATION...Gant
AREA FORECAST DISCUSSION
National Weather Service Bismarck ND
616 PM CST Sat Mar 4 2023
.UPDATE...
Issued at 616 PM CST Sat Mar 4 2023
Quiet weather this evening, with broad zonal flow aloft ahead of
the approaching system. No changes needed to the near term
forecast with this update, and will be working on evaluating any
changes needed for short term winter storm forecast.
&&
.SHORT TERM...(This Evening through Monday)
Issued at 307 PM CST Sat Mar 4 2023
The main forecast issue in the short term period will be the
upcoming winter storm.
Unfortunately there remains quite a bit of uncertainty with this
system. The main culprit seems to be the differences between the
NAM/CAMS compared to the global models. Global models are continuing
to keep the system farther south, and pretty much within our current
watch area. Meanwhile, the CAMS are consistent in tracking the
system farther to the north. For example, the latest RAP shows the
highest snow totals along the far northern edge of our watch, and
northward into Canada. The 12Z NAM did come back south just a bit,
but is still a good deal north of the consensus of the Global model
track. A 12Z NAM solution would certainly add another row of
counties onto any headline. The ECMWF is probably the farthest
south with the system, keeping highest qpf and resulting snow
totals over southwest and far south central ND. However, the
latest 18Z NAM looks to be coming back to the south, and closer
to the Global model solution.
Conceptually, it seems like a global solution seems more
reasonable with a progressive wave tracking east across SD, and
the 70H low tracking along the ND/SD border. This would place the
heaviest snow amounts over our current watch area. I`ve seen
times when the NAM/CAMs verify better than the global models, but
to me it seems like it`s generally a case with a slower moving
closed system, where it better depicts the moisture transport and
northward extent of the warm air.
We ended up upgrading the watch to a warning for all but the far
western part of the watch. In the west, we upgraded the watch to
a winter weather advisory. Lesser snow amounts are anticipated in
the far west. Also, winds in the southwest are not expected to be
too strong. As far as snow amounts, it`s difficult when there is
such a wide discrepancy between the CAMS and the Global Models.
While leaning towards the global solution, the NBM is being
influenced by the short term models and placing more snow into
northern North Dakota. We ended up relying heavily upon the WPC
solution which was a nod to the global models. With that said, we
want to message that even this close to the event, there is a lot
of uncertainty in snow amounts. That can be seen in our 25th/75th
percentile snowfall map with quite a range in snow totals along
the northern and eastern periphery of our hazard. We went with
snow totals of 3-5 inches for the advisory area in the far west.
We kept the 5 to 10 inches over the areas west of the Missouri
River, and 5 to 9 inches east of the Missouri River. Snow amounts
within the current warning have remained pretty stable. We
considered an Advisory to the north of the current warning, and we
certainly may still need one, However, with snow not beginning
here until probably Sunday afternoon, and so much uncertainty in
snow totals, we felt there was enough time to see how the 00Z
models handle things. If trends continue south, we may be fine
with no hazards here, but if the northern trends of the CAMS
verify, we could need to add another row of counties, possibly
two.
Winds with this system will be similar to our last event in that
winds will be mainly out of the east. There is a strong gradient
between the surface low over the central Plains, and high pressure
over Canada, but in general, winds are expected to be in the 15
to 30 mph range with gusts to 35 mph. There is a surge of winds
Monday night into Tuesday morning as the system wraps us and
tracks to our east, but the snow should be tapering off by then.
Currently headlines end around midday on Monday. Expect that
western areas ND can be cancelled early. Depending on how much
snow we see in eastern portions of central ND and if blowing snow
remains in an issue, it`s possible the headlines may need to be
extended through the afternoon over the James River Valley. In
general however, things should be winding down by Monday
afternoon.
.LONG TERM...(Monday Night through Saturday)
Issued at 307 PM CST Sat Mar 4 2023
Beyond the storm ending on Monday, we remain active through the
extended period. An upper level trough is sitting over the eastern
Pacific early in the period with impulses moving through the mean
trough position and into the northern and central Rockies.
Initially over the Northern Plains there looks to be a period of
shortwave ridging late Monday into early Tuesday. We then begin to
see the initial shortwave energy rotating through the
aforementioned upper trough. At this time there is reasonable
agreement in the deterministic models with this lead shortwave
energy bringing a swath of light accumulating snows into the
forecast area Tuesday through early Wednesday.
Forecast uncertainty increases significantly beyond this as the main
upper low either ejects eastward towards the central and northern
Plains mid to late in the work week, or digs south along the western
U.S. coast and potentially ejects into the region late in the work
week and into the weekend. Needless to say, we will need to
monitor closely while we continue to deal with our short term
system.
As far as temperatures are concerned, we will see a shot of
colder air behind our initial storm late Monday into Tuesday, with
morning lows in the single digits above or below zero Tuesday
morning and afternoon highs mainly in the teens. We moderate a
little mid to late week, but remain near to below normal through
the extended period with daytime highs mid to late week in the mid
teens to mid 20s and overnight lows in the single digits to lower
teens.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday Evening)
Issued at 616 PM CST Sat Mar 4 2023
VFR conditions to start the 00Z TAF period before a winter storm
begins impacting the area early Sunday morning. Snow is expected
to move north through the forecast area, bringing MVFR ceilings
and visibilities to KDIK/KBIS by 12Z. From there, expecting
widespread low MVFR to IFR ceilings and visibilities with snow
and blowing snow through the end of the TAF period and beyond.
Light and variable winds tonight becoming breezy and southeasterly
in the morning, before becoming stronger and more east-northeast
toward the end of the period.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from 6 AM CST /5 AM MST/ Sunday to noon
CST /11 AM MST/ Monday for NDZ017.
Winter Storm Warning from 6 AM CST /5 AM MST/ Sunday to noon CST
/11 AM MST/ Monday for NDZ018>020-032>034-041-042-044>046.
Winter Storm Warning from 9 AM Sunday to noon CST Monday for
NDZ021>023-025-035>037-047-048-050-051.
Winter Weather Advisory from 2 AM Sunday to 11 AM MST Monday for
NDZ031-040-043.
&&
$$
UPDATE...Jones
SHORT TERM...TWH
LONG TERM...TWH
AVIATION...Jones
Area Forecast Discussion
National Weather Service Lincoln IL
900 PM CST Sat Mar 4 2023
.SYNOPSIS...
Issued at 251 PM CST Sat Mar 4 2023
A few sprinkles are possible north of I-72 through early evening,
then cloud cover diminishes, with patchy fog possible once again
overnight into mid Sunday morning. Cloud cover increases on
Sunday, with southeasterly winds gusting over 20 mph during the
afternoon. Monday will be breezy and mild, with highs in the 60s.
Then a cold front moves through Monday evening, resulting in
slightly below normal temperatures for the rest of the work week,
with highs in the mid 40s.
&&
.UPDATE...
Issued at 855 PM CST Sat Mar 4 2023
A narrow band of spotty light rain showers and sprinkles was over
central parts of Champaign and Vermilion counties at mid evening
with broken cloud bases of 4-8k ft. These associated with a weak
cold front approaching I-72. These spotty pcpn should
diminish/exit east central IL late this evening, as weak front
moves se through southeast IL overnight. Weak 1020 mb high
pressure over IA will strengthen to 1025 mb by dawn as it drifts
over central/ne IL and IN. Light winds to veer NE to ENE overnight
with a few patches of clouds lingering. Continued mention of some
fog overnight into mid Sunday morning, and added areas of fog to
areas ne of I-74 later tonight and early Sunday morning where CAMs
showing more agreement with more fog development closer to high
pressure ridge and lighter winds, along with a wet/damp ground
from recent moderate/heavy rainfall yesterday. Lows in the low to
mid 30s look on track by dawn with coolest lows northern CWA.
&&
.SHORT TERM...(This evening through Sunday)
ISSUED AT 251 PM CST Sat Mar 4 2023
The immediate short term forecast has been tracking well, with the
line of showers that was noted across KS/MO this morning
dissipating as anticipated. Weak low-level f-gen and upper level
ascent have resulted in a band of light rain pushing into the far
NW counties of the CWA as of 245pm Sat. As this corridor of
forcing tracks east over the next several hours it will be the
primary source of any light rain this afternoon. It is worth
noting though that after a brief lull behind that line, vis
satellite does show modestly agitated Cu from near Des Moines to
Cedar Rapids, and CAMs do indicate a stray sprinkle or two could
form within that corridor as it tracks east this evening. By about
8pm, any linger rain should dissipate/depart the CWA.
Tonight, another round of at least patchy fog appears likely. As
the shortwave moves away, an elongated sfc ridge will be draped
near or just north of the area overnight and cloud cover will
diminish. The combination of clear skies and light winds once
again sets the stage for favorable radiational cooling.
Additionally, soils remain damp from recent rains/snowfall, with
CREST soil moisture showing values greater than 60% east of the IL
River. Lows below freezing north of I-72 may lead to fog
freezing, resulting in isolated slick spots on elevated surfaces
such as bridges. Dense fog is a possibility, although a lack of
confidence in where dense fog would develop has prevented any
headlines with this package. NBM probabilities favor the I-74
corridor, with a 20% chance of vis below 1 mile between
Bloomington and Danville, while the percentage of CAMs with dense
fog is greatest in the SE CWA.
Into the day on Sun, winds quickly turn southeasterly as the broad
sfc high shifts east and lee cyclogenesis results in sfc pressure
falls over the western Plains. Forecast soundings suggest gusts of
25-30 mph by late afternoon. The southerly flow will boost high
temps into the 50s area-wide, perhaps approaching 60F along the
southern fringes of the CWA border. No precip is expected during
the day.
.LONG TERM...(Sunday night through Saturday)
ISSUED AT 251 PM CST Sat Mar 4 2023
The main forecast highlights of the upcoming work week include:
1) A chance for showers late Sun night into Monday morning north
of I-72
2) Above normal temperatures and breezy southwest winds for much
of Monday, until a cold front moves in late afternoon.
3) Near to slightly below normal temperatures for the rest of the
work week. Occasional precip chances (15-30%) will exist for much
of the week, but higher precip chances will be positioned west of
the CWA
4) A stronger system appears likely late week, though considerable
uncertainty remains in the timing and track. Precipitation type is
low confidence at this range, but snow is a possibility.
The sfc low that develops in the lee of the Rockies on Sun will
lift quickly northeast overnight into Mon. Light rain showers and
perhaps an isolated storm are possible in the WAA regime,
primarily near the warm front, near/north of the IL River.
Forecast soundings do show a narrow sliver of instability, around
100 J/kg of MUCAPE, so it wouldn`t be a total surprise to hear a
rumble of thunder with this precip activity, but it also doesn`t
appear particularly likely either.
The position/track of this low is such that winds will shift from
southerly Mon AM to southwesterly by midday, then turn to
northwesterly during the late afternoon/evening as a cold front
drops through the area. It will be breezy, with daytime gusts
around 30 mph. When out of the south, those winds will help boost
temperatures, with highs on Monday climbing into the 60s.
For the mid-week, a broad upper level ridge axis will slowly shift
east across the Midwest/Great Lakes, with a strong sfc high
pressure well north of the Canadian border. Tuesday looks dry,
then guidance keeps sporadic low precip chances across the
western/southern portions of the CWA Tues night-Thurs, likely in
response to a shortwave depicted as lifting across the northern
Plains. The deterministic GFS is stronger with this upper wave,
and accordingly more aggressive in the coverage/eastward extent of
precip. Temps will be cooler after the cold front passes Mon,
with highs only in the mid 40s (as opposed to normal temps in the
mid 40s) and lows near freezing. For any precip that does occur
Tues night-Thurs, it could wind up being a tricky p-type forecast.
Forecast soundings show low-level wet-bulb temps near freezing,
and a temperature profile that is often within a degree or two of
freezing through the lowest 6-7 kft. The good news is that QPF
amounts during this timeframe are expected to be on the light
side, with ensemble mean QPF amounts in the 0.10-0.25" range west
of I-55.
Late in the week, the longwave trough over the western US is
progged to eject onto the central Plains, resulting in another
low pressure system sweeping through the Midwest. Considerable
uncertainty remains in the timing of this system, with the
deterministic GFS/ECMWF nearly 500 miles apart in sfc low
placement by Sat AM. Ensemble member low positions paint similar
uncertain, with forecast lows broadly scattered across the eastern
Plains/Midwest on Fri-Sat. This system is not expected to as
deep/intense as last Friday`s low pressure system, with most
ensemble members forecasting a low with MSLP in the 990s (as
opposed to near 980mb), but that doesn`t mean it won`t bring
impactful weather to the Midwest. It`s just too early to determine
exactly what those impacts will be, and when they`ll arrive to
central IL.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 550 PM CST Sat Mar 4 2023
Carried VCSH at BMI til 01z and may get close to CMI early this
evening, otherwise scattered 4-7k ft clouds and broken 8-10k ft
clouds to diminish from west to east during early and mid evening.
VFR conditions should generally continue across the central IL
terminals next 24 hours through 00Z/Monday. Though MVFR vsbys
could occur with patchy fog between 08-14Z with light winds and a
wet ground from recent moderate to heavy rains yesterday. The
latest CAMs (HRRR, RAP and GFSLamp) mainly show some fog that
could get dense in spots developing overnight north of PIA and
from I-70 south, while the more aggressive NAMnest shows fog
appearing east of the IL river during overnight. Will keep vsbys
at 4-5 miles for now and monitor. Mid/high clouds to track east
into central IL late tonight and Sunday morning and may offset
fog formation especially western terminals. SW winds 5-10 kts at
00Z could shift west/NW for a time this evening as weak cold
front near IL river passes through. But generally winds become
light and variable by mid/late evening and overnight as high
pressure settles into IL by dawn from Iowa. Winds shift ENE late
tonight and veer SE and increase to 10-14 kts with gusts 18-22 kts
during mid/late Sunday afternoon as high pressure shifts east of
IL over Lake Huron.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...07
SYNOPSIS...Erwin
SHORT TERM...Erwin
LONG TERM...Erwin
AVIATION...07
Area Forecast Discussion
National Weather Service Marquette MI
640 PM EST Sat Mar 4 2023
.SHORT TERM...(Tonight)
Issued at 150 PM EST SAT MAR 4 2023
Water vapor imagery and RAP analysis show a well-defined shortwave
moving east through northern IA this afternoon. There has been an
increase in cloud cover ahead of and north of this feature but so
far only pcpn being reported has been rain showers over portions of
eastern IA. Have not seen anything yet upstream of our area over MN
and northwest WI based on radar imagery and sfc obs. Weak ridging
and fairly abundant sunshine thus far today has allowed temps to
rise to into the upper 30s to even mid 40s in a few spots south
central. Temps could maybe rise a degree or two the rest of the
afternoon but that should be about it as increasing cloud cover
spreading in from Wisconsin should put a lid on any further heating.
Tonight, shortwave currently over northern IA will reach the western
Great Lakes this evening. A decent band of deep layer forcing will
spread across the area as noted on deep-layer q-vector convergence
fields, and some fgen will also move in as well. While the better
chc of pcpn should pass by to the s along the main track of the vort
max, opted to keep schc mention of -shsn across the central and e
this evening into the early overnight. Skies should clear out over
the w overnight behind the shortwave. With light winds/calm
conditions in that area late, favored some of the lower guidance
there with temps dropping near 10F over the favored interior cold
spots. Temps will range up into the mid 20s F east and along the
Great Lakes.
.LONG TERM...(Sunday through Saturday)
Issued at 301 PM EST SAT MAR 4 2023
The primary focus of the long term forecast period is the potential
for widespread wet snow accumulations late Sunday night through
Monday. We`re also monitoring a large and slow-moving closed low
that may bring a prolonged period of lake-enhanced snow and strong
winds next weekend. Overall, above-normal temperatures trend to near-
normal values by mid-week then perhaps below-normal by late next
week if the closed low tracks close enough. Confidence in
precipitation amounts over the next week is comparatively low, but
near-normal values across the interior and above-normal values near
Lake Superior are favored at this time.
Beginning with Sunday, ridging at the surface and aloft is likely to
make for a beautiful day with abundant sunshine. Sunny skies and
light winds suggests potential for temperatures to exceed all
available model guidance due to the low albedo jack pines. Light
winds limits mixing and downsloping potential, but also introduces
potential for a super-adiabatic boundary layer. The maximum of
available non-NBM guidance indicates high temps within a few degrees
of 40F, which was similar to the NBM 50th percentile. The current
forecast represents a 50/50 blend of the max of non-NBM guidance and
NBM 50th percentile guidance. Clouds increase late on Sunday as the
well-advertised wet snow event approaches.
Overall, the approaching winter storm is quite similar to many of
the wet snow events we`ve had this winter. The heaviest precip
appears to be focused within the leading WAA side of the storm late
Sunday night and Monday. Then lighter lake-enhanced precip for
northeast to north wind snow belts in the trailing CAA side of the
storm Monday night and maybe into Tuesday. The post-system air mass
has 850mb temps between -10C and -12C, which is a smidgen too warm
for lake effect indicating QPF/snowfall will be focused within the
period of deeper moisture and synoptic lift. Overall, ensemble means
indicate storm total QPF will be maximized (1/2" to 1") across the
central UP where generally easterly flow north of the surface low
results in persistent upslope and some lake enhancement off Lake MI
cannot be ruled out either. ECMWF guidance continues to be bearish
with QPF amounts, with the 12z operational run struggling to get
1/2" anywhere in our CWA perhaps because of convective feedback
issues farther south. GEFS means show a decreasing/southward trend
in QPF for our area too while most non-global models (RAP, NAM, FV3,
etc) are trending toward increasing QPF. All in all, positioning of
a potentially heavy band of wet snow remains about as clear as mud
and forecast snow amounts are hovering just below winter storm watch
criteria.
Given the model uncertainty it may be wise to step away from model
guidance and consider the established snow cover gradient and
associated baroclinic zone that extends approximately between Sioux
City, IA and Sheboygan, WI. Model solutions that track the surface
low substantially north of that line are probably out-to-lunch since
upper level flow is approximately parallel to the baroclinic zone.
In theory, snowfall should be maximized about 150 miles north of the
snow cover gradient suggesting the heaviest snow stays in GRBs area,
but theory and practice often differ. Another tricky aspect of this
storm is there`s likely to be two periods of cyclogenesis lee of the
Rockies. 12z EPS low tracks suggest the first occurs in the vicinity
of Rapid City, SD during the day on Sunday as 500mb height falls
begin. However, a secondary surface low develops near the CO/KS
state line at 00z Monday as a 150+kt 300mb jet streak ejects onto
the Plains. These surface lows phase on Monday with a surface low
near southern Lake MI by Monday afternoon. The jet streak crests the
ridge axis Monday evening suggesting weakening and SE motion Monday
night into Tuesday as lake enhancement winds down.
By Tuesday afternoon, an impressive 1050+ mb surface ridge centered
over Northern Manitoba extends a very dry (pwats at or below 0.15")
ridge axis south across our area that persists into Thursday/Friday.
Since 850 mb temps only cool to around -10C lake effect snow is
likely off the table, but a diurnal pattern of lake effect
clouds/flurries (more at night) seems likely. There should be just
enough clouds and wind to make temperatures an absolute pain to
forecast, but given ridging large diurnal temperature ranges (cool
nights, warm days) are favored. This could mean good maple tapping
conditions farther from Lake Superior. Attention then turns to the
next system ejecting onto the Southern Plains late on Thursday.
Overall, the late week system is reminiscent of the long-duration,
high-impact winter storms that brought heavy lake-enhanced snow and
strong winds to the UP in October and December. While large scale
similarities don`t guarantee similar local impacts, the potential
should be monitored closely. If a similar storm materializes then
impacts could be much greater than early-season storms since late-
season snow banks could result in deep drifting across roadways. 12z
EPS probabilities of QPF suggest deteriorating conditions on Friday,
the height of the storm between Friday night and Sunday morning,
then slow improvement through Monday evening. Ensemble median 850mb
temps appear to be just cold enough for pure lake effect as the
storm departs. Naturally, that general overview is subject to major
changes, but weekend travelers should consider altering plans to
earlier this week or next week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 640 PM EST SAT MAR 4 2023
Will trend toward VFR for the duration of the TAF period. A
disturbance could result in some brief snow showers and MVFR cigs at
SAW this evening into tonight, but confidence is not high enough at
this time to insert mention in TAF. Look for a wind shift from WNW
to southeast tomorrow afternoon, but winds will be light.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 301 PM EST SAT MAR 4 2023
Winds across the lake stay below 20 knots until an approaching low
pressure brings increasing easterly winds Sunday night. Easterly
gales to 35 knots develop Monday morning then increase to 40 knots
during Monday before diminishing to between 25 to 30 knots Monday
night as winds back northeasterly. Winds back northerly on Tuesday
while diminishing to between 20 and 25 knots. Northerly winds
gusting to around 20 knots are expected to persist through Thursday,
but some veering to northeasterly winds is expected by Wednesday
night. Uncertainty grows near the end of the week as a large and
slow moving low pressure tracks toward the Great Lakes region.
There is potential for a prolonged periods of strong north to
northeast winds and large waves.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
Gale Watch from late Sunday night through Monday evening for
LSZ162-240>242-263.
Gale Watch from Monday morning through Monday evening for
LSZ243>251-264>267.
Lake Michigan...
None.
&&
$$
SHORT TERM...Voss
LONG TERM...EK
AVIATION...TDUD
MARINE...EK
Area Forecast Discussion
National Weather Service San Francisco Bay Area
342 PM PST Sat Mar 4 2023
.SYNOPSIS...Rainy conditions is expected to continue through
Sunday as a cold air mass descends over the Bay Area. This system
will also provide a slight chance for thunderstorms, higher
elevation snow, gusty winds and below normal temperatures. Low
temperatures Tuesday through Thursday next week will be nearing
record lows. Unsettled weather forecast to continue through mid-
month.
&&
.DISCUSSION...as of 1:26 PM PST Saturday...A line of
thunderstorms moved through the Bay Area this morning as seen on
radar and reported via social media. The Santa Cruz Mountains were
the first to report pea sized hail from a small cell out ahead of
the initial boundary. But as the line approached the Golden Gate
bridge, reflectivity intensified, lightning activity increased,
and places such as Pacifica, Burlingame, Moss Beach, North Berkley
and Downtown San Francisco received pea sized hail. The office
issued numerous special weather statements as a result of the
hail. The line has weakened, but is still moving southward,
providing rain to San Benito and Monterey Counties Saturday
afternoon.
Today`s excited was only the leading edge of the system. Rain
showers will continue through Saturday, but higher resolution
models are keying in on the midnight timeframe for the surface
front to push through the area. Both HRRR and NAM models keep
MUCAPE over the ocean for the next 24 hours with additional
scattered swaths over the land. The overnight hours will be the
best probability for another band of heavier convective showers
and the potential for lightning activity and small hail. While
instability will be present through Sunday, most of the storms
will be scattered in nature. Isolated cells may intensify, but
will only impact small areas and are hard to pinpoint. That being
said, thunderstorms with the risk of lightning and the potential
for small hail will remain in the forecast through overnight
Sunday night.
Winds were gusty and out of the southwest this morning along the
boundary, with surface winds gusting between 20 to 25 mph. Higher
elevations have been gusting at 35 to 40 mph, but isolated areas
have been higher, with the Altamont Pass reaching 55 mph. Winds
will subside Saturday evening, but then quickly strength overnight
with the next front. Similar wind gusts can be expected overnight
with the lower valleys receiving 25 to 35 mph and higher
elevations 35 to 45 mph.
After tonight`s frontal passage, winds will turn to the northwest
and cold air advection will increase. This colder air mass will
gradually lower snow levels to 1,500 feet in the North Bay, and
between 2,000 feet to 2,500 feet in the East Bay. The North Bay
interior mountains have been in a Weather Weather Advisory, but
today it was decided to add the East Bay Hills and Santa Clara
Hills to the advisory as well. Many locations between 2,100 to
2,400 feet will only see a dusting but the higher peaks above
2,500 feet could see 3 to 5 inches and locally up to 7. Taking
the fact that it is the weekend when more people are out
travelling and possibly recreating, it was decided that being
cautious and placing them in an advisory was the best course of
action.
Weak instability will linger around the Bay Area through the
middle part of next week keeping weakly scattered showers in
forecast through at least Wednesday. However, what will slowly
become the bigger impact will be the gradual reduction in morning
low temperatures. The afternoon temperatures will likely stay
below normal and be in the low to mid 50s each day. But morning
lows will slowly drop toward the freezing mark mid week. For those
that have been following our forecasts each day, this should stand
out as a change in our forecast. For a while, it was looking like
Tuesday was going to be the coldest day of the week. Latest
guidance from the blend is now depicting it to be around Wednesday
or Thursday. This is large part is due to the slow progression
that ensemble models are showing from the movement of the upper
level long wave trough that is driving this system. As it
progresses eastward, colder air will descend down and
probabilities are increasing for interior areas to fall below 35
degrees Fahrenheit.
There is a chance that late Wednesday might provide a break in
the rain, but it will only be a brief respite. Ensemble models are
still projecting the next system to move toward the Bay Area late
next week. The problem is, many of the ensembles are still
disagreeing in timing and location. However, the moisture
available with this system is trending wetter. The GEFS has a 20
to 30 percent chance for precipitable water (PWAT) amounts
greater than an inch, with the Euro ensemble at 50 to 60 percent
chance. But if there was ever an example of why there is so little
confidence in long range models, just yesterday the GEFS was
stronger than the Euro, and today`s it literally flipped with the
Euro stronger. It is hard to distill confidence in that.
Regardless, the signal is there that next weekend could have a
system with the potential for heavier precip amounts, but there is
just way to much uncertainty for a stout forecast.
&&
.AVIATION...as of 3:35 PM Saturday...For the 0Z TAFs. MVFR ceilings
and brief IFR visibilities along a band of rain going through
Monterey and San Benito counties just south of MRY and over SNS.
Otherwise, generally VFR with localized MVFR in showers, including a
secondary band located along a line through LVK and SJC. Gusty
southwest flow prevails, with the chance for valley drainage flows
when the winds diminish overnight. With newer model guidance showing
a slower front, have pushed back the timing of the next rain band to
around 7-9Z for the North Bay, 9-12Z for the SF Bay Area, and 11-13Z
for the Monterey Bay terminals. Winds turning to the west after the
front passes, remaining gusty.
Vicinity of SFO...VFR should prevail with gusty southwest winds and
perhaps periods of MVFR ceilings if a shower passes overhead. Expect
the rainband coming through around 9-11Z to bring MVFR conditions,
with gusty west-southwest winds continuing through Sunday. Current
model guidance suggests winds diminishing on Sunday night.
SFO Bridge Approach...Similar to SFO.
Monterey Bay Terminals...The main rain band is leaving the MRY
terminal area and will pass SNS by within the hour. Expect generally
VFR conditions for the rest of the day and into the overnight hours,
with gusty southwest winds continuing into the night. SNS may see a
drainage flow pattern develop after midnight. Currently expecting
the front to come through around 11-13Z for the Monterey Bay
terminals, bringing MVFR ceilings, with winds turning to the west
and becoming moderate after the frontal passage.
&&
.MARINE...as of 1:09 PM PST Saturday...Scattered showers will
continue into early next week along with the slight chance for
thunderstorms. Winds have already turned to the northwest
creating hazardous seas conditions. The Gale Watch was removed
from the forecast due to the lack of confidence in winds reaching
that magnitude, but the main message is that strong wind gusts
will prevail and continue to generate steep seas through Sunday.
A northwest swell will gradually diminish through the week.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
.Tday...Winter Weather Advisory...CAZ504-514-515
SCA...SF Bay
SCA...Mry Bay
SCA...Pt Arena to Pt Reyes 0-10 nm
SCA...Pt Reyes to Pigeon Pt 0-10 nm
SCA...Pigeon Pt to Pt Pinos 0-10 nm
SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm
SCA...Pt Arena to Pigeon Pt 10-60 nm
SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm
&&
$$
PUBLIC FORECAST: DK
AVIATION: DialH
MARINE: DK
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Area Forecast Discussion
National Weather Service Pueblo CO
318 PM MST Sat Mar 4 2023
.SHORT TERM...(This evening through Sunday)
Issued at 247 PM MST Sat Mar 4 2023
...Very strong damaging winds and Red Flag conditions are likely
over portions of Southeast Colorado tomorrow...
Key messages:
1) Very strong and damaging winds are likely over much of southeast
Colorado beginning early tomorrow. There will be areas of blowing
dust possible, which may temporarily reduce visibilities.
2) Severe crosswinds could make travel dangerous over portions of
the southern I-25 corridor for high profile vehicles by late morning
and through the afternoon tomorrow.
2) Very strong and gusty winds afternoon tomorrow, along with low
relative humidity, will result in extreme critical fire weather
conditions being likely over the plains and Palmer Divide.
3) Snow will continue to increase over the ContDvd later tonight and
tomorrow. Blowing snow will make travel tricky to dangerous at times
across some of the higher mountain passes.
Detailed discussion:
Tonight...
A longwave trough upstream is continuing to propagate towards the
region. This has allowed higher level clouds to move over and keep
temperatures on the cooler side. However, as winds continue to
increase towards the early morning hours over most of southeast
Colorado, this will allow for overnight temperatures to remain
modified and relatively warmer due to mixing. The warmest areas will
be over portions of the plains where downsloping winds are the
strongest, especially in and around areas susceptible to gap flow
winds. Downwind from La Veta pass and Raton Mesa, some of the lows
may only make it down into the low 40s because of this. Snow showers
will begin to increase across the higher terrain through the night.
The higher terrain will also see relatively warmer lows for tonight,
ranging anywhere from the teens to low 20s for most areas, and only
a few single digits for the highest peaks. Snow will begin over the
ContDvd later tonight, mainly over the Sawatch Range.
Tomorrow...
As a stronger jet at the 500 mb level begins to make its way over
southeast Colorado, some winds mixing down to 600 mb and below will
create very strong winds over the higher peaks of the Sawatch and
Sangre de Cristo Mountains, and maybe a few spotty areas of High
Wind criteria over portions of the La Garita and San Juan Mountains.
There will be some strong winds across the higher peaks of the
Mosquito and Rampart Ranges, as well as the Pikes Peak area,
although not expected to reach High Wind criteria as gusts should
remain below 75 mph. With brute forcing, these winds will continue
to mix down to the surface and increase winds over the San Luis
Valley, Wet Mountains, Wet Mountain Valley, and southern I-25
corridor, mainly south of Colorado City to Trinidad. Winds will
increase through the morning, becoming very strong with high gusts
that could be damaging to smaller trees and loose objects at times.
There could also be areas of blowing dust possible, which may
temporarily reduce visibilities. Due to snow over some of the higher
elevations and very strong winds, there could be areas of blowing
snow which could temporarily reduced visibilities and result in
dangerous driving conditions at times, especially through some of
the higher passes. Areas of most concern will be Monarch Pass and
Cottonwood Pass.
Strongest winds will be in the Walsenburg area, with gap flow winds
through La Veta Pass further enhancing some of the stronger gusts.
Severe crosswinds could make travel dangerous over portions of the
southern I-25 corridor for high profile vehicles during the late
morning hours and through the afternoon tomorrow. Some of the higher
resolution models, such as the NAMNest and HRRR have the strongest
winds also begin just downwind of the southern Sangres. Along with
these winds and possibly areas of blowing dust will be dropping
relative humidities as drier air mixes down to the surface and also
simultaneously warms up adiabatically over the plains. This will
result in widespread extreme fire weather conditions across the
plains and Palmer Divide by late tomorrow morning and through the
afternoon hours. These downsloping winds will also cause
temperatures to warm up considerably for the lower elevations
downwind of mountain ranges, and across the plains. Some locations
over the eastern plains and within the lower Arkansas River Valley
could see temperatures getting into the low to mid 70s. -Stewey
.LONG TERM...(Sunday night through Saturday)
Issued at 247 PM MST Sat Mar 4 2023
Fast westerly flow still in place Sunday night, with highest mid
level wind speeds noted along the NM border. Appears risk of high
winds may continue through the night in/near the lee of the srn
Sangres, where mountain wave sets up and 700 mb speeds remain in
the 50-60 kt range. Have thus extended a portion of the high wind
warning until early morning Mon to account for this possibility.
During the day Mon, wly flow aloft continues, while cold front
backs westward across the plains during the day. Max temps along
and east of the mountains problematic, with potential for rather
sharp gradient ending up somewhere near I-25 in the afternoon. In
general, went colder than NBM for much of the plains, with warmest
temps along the srn I-25 corridor. Some snow showers will linger
over the central mountains through the day, though not expecting
much in the way of accumulation.
Cold air deepens Mon night/Tue morning, with at least some hints
of freezing drizzle near the Palmer Divide as saturation never
reaches minus 10c level. Haven`t included a mention in the
forecast yet, but possibility certainly needs monitoring. Max
temps again problematic Tue, as NBM looks too warm given deepening
cold air on the plains. Undercut guidance by several degf, but
may need to go even colder in subsequent forecasts. Again, small
sliver of the srn I-25 corridor/ern slopes of the Sangres could
mix out into the warmer air Tue afternoon, but it will likely be
brief.
Still a lot of uncertainty regarding timing and eventual track of
ejecting western trough in the Wed-Fri time period, though general
message of today`s GEFS/EPS seems to point to a quicker/more nrn
system with less in the way of precip for srn CO. Overall,
forecast is still rather broadbrush for now, with pops for rain
and snow showers most areas from Wed into Fri, though QPF is low
through the period. Temps will remain cool, with coldest readings
likely Friday as cold air surges south behind departing system.
&&
.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1039 AM MST Sat Mar 4 2023
VFR conditions are expected to prevail for all TAF sites (KALS,
KCOS, and KPUB) throughout the forecast period. Winds will be
initially diurnally influenced for the first 18 hours or so of the
forecast period, and then become synoptically influenced at all
terminals due to another approaching system. Expect SW`ly winds to
increase significantly at KALS after about 15Z, with gusts by the
end of the forecast period being as high as 50 kts after 21Z. There
could also be some BLDU on station at KALS at times after 15Z, which
could temporarily reduce VIS down to IFR/LIFR conditions at times.
Winds will begin to increase out of the SW at both KCOS and KPUB
after 16Z late tomorrow morning, and continue to increase towards
the end of the forecast period, with gusts as high as 40 kts by 20Z
at KPUB and 21Z at KCOS. BLDU will also possible at both KCOS and
KPUB after such time and throughout the rest of the forecast period.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
High Wind Warning from 8 AM to 7 PM MST Sunday for COZ060-061-
069>073-078>080-086.
High Wind Warning from midnight tonight to 8 AM MST Monday for
COZ074-075-087-088.
Red Flag Warning from 11 AM to 7 PM MST Sunday for COZ226>237.
&&
$$
SHORT TERM...STEWARD
LONG TERM...PETERSEN
AVIATION...STEWARD