Forecast Discussions mentioning any of
"ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 11/12/22
Area Forecast Discussion
National Weather Service Indianapolis IN
1015 PM EST Fri Nov 11 2022
.Forecast Update...
Issued at 1015 PM EST Fri Nov 11 2022
* Chance of snow for much of Central Indiana Saturday Morning
Little changes made to the immediate forecast this evening. Cold
front has passed and temperatures have quickly dropped into the low
to mid 30s along and north of I-70 as of 10 PM. Cold air advection
will continue through the overnight hours with most locations
dipping down into the upper 20s to low 30s.
Majority of the changes made to the short term forecast were for
Saturday morning when snow is expected to move in across much of the
area. Short term guidance as well as the NBM have all come into good
agreement with the set up for the morning. Upper wave and associated
jet streak are currently rounding the base of a deep trough around
Arkansas this evening, as evident on current satellite imagery. Left
exit region of the jet pushed NE into Kentucky later this morning
placing Central Indiana in an area of enhanced upper divergence and
lift. While there is no real surface reflection, much of the
moisture and lift are associated with energy around and above 700mb.
GOES16 Simple Water Vapor imagery and current ACARS soundings from
the mid south currently show a plume of moisture ahead of the
incoming wave pushing northeast towards the Ohio Valley. With dew
points already falling into the lower 20s and cold air advection
continuing, confidence is high that the atmospheric column will
support snow as the system approaches. Current 03z IND ACARS
soundings does show a warm nose around 700mb, however with continued
cold air advection over the next 12 hours, expect wet bulb
temperatures to drop below freezing. Short term guidance shows lift
within a saturated DGZ between 6am and noon for much of Central
Indiana, so confidence remains high that snow will be likely across
the region during the mid morning hours, especially after sunrise.
Have increased PoPs to "likely" wording for areas along and south of
I-70, including the Indy Metro area and most of Eastern Indiana from
7am to around 11am. Since this is a quick moving, weak system with
not much moisture to work with, any accumulations will be light.
Surfaces remain above freezing due to such warm conditions earlier
this week, so most snowfall will only accumulate on grassy areas and
elevated surfaces. Around a dusting to an inch of snow is expected,
with the highest totals in Southern Central and Southern Indiana
where the strongest lift is expected to occur within the DGZ. Due to
the snow occurring through the morning, temperatures will likely
hover around freezing for much of the day until precipitation exits
to the east. Lowered highs a few degrees to account for this... with
max temps in the mid 30s (upper 30s in areas that receive less
snow). Since this will likely be the first measurable snowfall of
the season for much of the state, an SPS has been issued for Central
Indiana highlighting the threat for minor snow accumulations.
&&
.Short Term...(This evening through Saturday)
Issued at 252 PM EST Fri Nov 11 2022
The long awaited cold front talked about over the last few days has
now made it into the eastern part of the forecast area as of
18Z...held up somewhat by the remnants of Nicole off to the east.
Already seeing quite a temperature spread across the front
locally...with upper 50s and lower 60s ahead of it while readings
have largely held in the 40s all day in western portions of the
forecast area. The back edge of the rain shield associated with
Nicole has pivoted out of our eastern counties and will move away o
the northeast.
The party is over in respect to the unseasonable warmth enjoyed
across central Indiana over the first third of the month. The
passage of the cold front today will shift all of that warmth well
off to the east and transition not just the Ohio Valley but much of
the eastern half of the country to a substantially colder regime
that will settle across the area over the next few days and is not
likely to depart...possibly until after the Thanksgiving weekend.
The initial transition is already ongoing as winds have veered to
northwest behind the front and have become gusty across the Wabash
Valley over the last few hours. Expect this to expand east over the
rest of the afternoon as cold advection strengthens in the
postfrontal airmass and temperatures steadily fall. There remains an
axis of lower stratus trailing the boundary but low level RH progs
do suggest this should mix out over the next couple hours with the
potential for some clearing from the west towards sunset as a noted
dry punch of air advects into the region from the west and aided by
subtle surface ridging behind the departing Nicole remnants.
Focus then shifts late tonight towards a fast moving but potent wave
aloft tracking out of the southern Rockies and eventually through
the front part of the expanding longwave trough across the upper
Midwest and Plains. The model suite has been playing catchup in
handling this feature over the last 24-36 hours...but its track and
strength are likely to support a swath of lighter precipitation from
southwest to northeast across the Ohio Valley beginning in the
predawn hours and extending through midday Saturday. More
importantly...confidence is high in snow as the primary
precipitation type with light accumulations likely to add to the
increasing chill to create a very winterlike feel to Saturday just
36-48 hours after 70s graced the area.
Mid and high level cloud cover will begin to increase in advance of
the wave aloft late this evening and overspread the forecast area
after midnight. Model trends have pulled the track of this feature
back to the northwest from previous runs...likely due to the greater
amplified nature of the parent trough diving out of the upper
Midwest. Initially...drier air noted on model soundings primarily
below 700mb will limit precipitation until more substantial lift can
overspread the region closer to daybreak Saturday. Expect though
that the lift and surge of moisture will help to moisten the
boundary layer fairly quickly across the southeast half of the
forecast area and set the stage for a 4-5 hour window with light
precipitation largely in the form of snow. Overall rates should be
held down but an axis of frontogenesis noted at 700mb will pivot
across the region during the morning and may enable brief periods
with heavier snowfall rates. Much of the best forcing will remain
beneath the dendritic growth zone through much of the event and with
increasingly drier air aloft advecting in as the system passes
through...expect a wet and sloppy nature to snowflakes on Saturday
morning.
The structure to the snowflakes mentioned above in tandem with
ground temps that remain warm (albeit drier than normal) will likely
limit any road issues from light accums Saturday morning. Definitely
see potential for accums to focus on elevated surfaces and in grassy
areas with bridges/ overpasses in particular being susceptible to
slick spots as air temps fall into the 30-32 range Saturday morning.
Have focused best potential for accums across the southeast portions
of the forecast area with some locations seeing up to a half inch.
This will drop back to just a couple tenths along the I-70 and I-69
corridors to nothing more than flurries in the northern Wabash
Valley. As air temps warm and rates lighten...much of the accums
will melt. With this being an early season snow threat with light
accums possible...will be introducing an SPS.
A second component will follow for the afternoon as the longwave
trough amplifies over the region behind the morning system with
strengthening cold advection under stronger mid level forcing. Model
soundings develop steep lapse rates beneath an inversion with drier
air above. That may be just enough to generate isolated to scattered
light convective showers in the afternoon over the northern 2/3 of
the forecast area in particular. Precipitation type will be sloppy
with a varied combination of rain...snow and graupel likely. Rates
will not be heavy and impacts are not anticipated as temps settle in
the mid to upper 30s. the light showers will diminish towards sunset.
Temps...welcome to the cold season. Lows will drop into the upper
20s and lower 30s tonight with our coldest night across central
INdiana in about 3 weeks. Low level thermals are strongly supportive
of the coldest day of the Fall to date on Saturday. Expect mid and
upper 30s for highs. Combined with the morning snow...chilly
northwest winds and damp conditions...an all around lousy day for
the area.
&&
.Long Term...(Saturday night through Friday)
Issued at 252 PM EST Fri Nov 11 2022
* Cool temperature push continues through the long term.
* Chances for rain and snow on Tuesday. Confidence in amounts is low
at this time.
Surface high pressure will continue to build over the Ohio Valley
Sunday and Sunday night beneath moderate 850-700mb CAA. This along
with anticyclonic upper level flow will lead to broad subsidence and
dry conditions over the region. Expect mostly clear skies by Sunday
morning. The source of this airmass is out of the Canadian Plains,
leading to below normal temperatures. Current expectations are for
highs in the low 40s Sunday and Monday.
The main system of concern will be a negatively tilted shortwave
arriving Tuesday morning, with precipitation chances for most of
Tuesday. There is still plenty of uncertainty with this event, but
ensemble members are starting to come to an agreement on timing
leading to a slight increase in PoPs for late Tuesday morning into
the afternoon. Still with a highly dynamic shortwave, slight
differences in jet placement can have major ramifications in
progression. Margin of error should decrease over the next few
forecast cycles as the parent trough arrives over the western CONUS
allowing for better model ingestion of observations. With that being
said, this does look have some chances for frozen precipitation,
given the cool air mass and lack of warm air return out ahead of the
system. Snow accumulation cannot be ruled out, with best chances
over NW portions of central Indiana.
The meridional pattern will continue through next week with high
pressure and dry conditions in the wake of the wave and more below
normal temperatures. Some ensemble members have picked up on another
system over next weekend. Although, there is still widespread
solutions and run to run inconsistency, but something to continue to
monitor nonetheless.
&&
.Aviation...(00Z TAF Issuance)
Issued at 634 PM EST Fri Nov 11 2022
Impacts:
* Gusty NW winds diminishing later this evening
* Light snow developing with vis and ceiling restrictions at KBMG
and KIND Saturday morning
Discussion:
As the remnants of Tropical Storm Nicole move off to the north and
east, ceilings will rapidly improve to VFR over the next couple
hours. Gusty NW winds to 25 kts behind the cold front are expected
to diminish later this evening but still remain elevated around 10
kts overnight.
High pressure will briefly take hold tonight prior to a fast moving
upper wave lifting into the region from the southwest during the
predawn hours. Confidence has grown in an area of light
precipitation accompanying the wave and impacting KBMG, KIND, and
possibly KHUF for 3-5 hours Saturday morning, likely in the form of
light snow. Highest confidence in timing for MVFR ceilings and vis
from snowfall is between 11z and 16z for much of Central Indiana.
All light precipitation will move off to the east by midday Saturday
with the potential for scattered areas of wraparound showers with
snow and rain Saturday afternoon. Expect improving ceiling and vis
through Saturday afternoon and evening.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Update...CM
Short Term...Ryan
Long Term...Updike
Aviation...CM
Area Forecast Discussion
National Weather Service Phoenix AZ
400 PM MST Fri Nov 11 2022
.UPDATE...
Updated Aviation
&&
.SYNOPSIS...
Mainly tranquil weather conditions will prevail through the next
several days. Below normal temperatures with highs in the upper 60s
to around 70 degrees are expected through next week with Saturday
being the warmest day with highs in the low 70s. A mostly dry
weather system will move across the region Sunday into early Monday,
only bringing another round of breezy conditions. Otherwise,
precipitation chances will essentially remain zero through at least
the next 7 days.
&&
.DISCUSSION...
Latest RAP streamline analysis depicts a shortwave ridge migrating
steadily eastward across the Desert Southwest. Early afternoon ACARS
KPHX soundings reveal relatively cool and dry air resides in the
lower levels below a well-defined subsidence inversion at 600 mb.
Despite the nearly full sunshine, temperatures are running roughly
10 degrees below average for this time of year.
Further upstream, a well-defined low pressure system is evident
across the Pacific Northwest. Ahead of this system, latest HREF
indicates high clouds will overspread the area late this afternoon
and tonight. Mostly sunny skies are anticipated again Saturday along
with slightly warmer conditions. However, temperatures will remain
roughly 5 degrees below average.
A cooling trend is likely Sunday as the aforementioned low pressure
system drops southeastward into northern Arizona. Given the dearth
of adequate moisture transport, multi-model ensemble remains
consistent indicating only a chance of very light precipitation
across northern Arizona. Biggest sensible impact instead across the
lower deserts will be an increase in wind, particularly across
portions of southeastern California and southwestern Arizona where
gusts up to 30 mph will be possible. Across the Phoenix area, latest
experimental NBM suggests gusts will likely reach 25 mph during the
afternoon. In the wake of the system, high temperatures Monday will
struggle to reach the mid 60s across the lower deserts of central
Arizona. Low temperatures in the 30s are also anticipated in the
Globe/Miami area Sunday night and Monday night, though the
probability of freezing temperatures remains below 15 percent, per
the latest experimental NBM. However, with overnight RHs likely
reaching 60 percent, there is a somewhat higher probability of frost
in these areas.
&&
.PREVIOUS DISCUSSION...
As we head into next week, the overall weather pattern across North
America will be characterized by a robust blocking ridge being
established over the eastern Pacific into Alaska. This will result
in broad troughing across much of the CONUS and thus the
continuation of below normal temperatures. As a result, temperatures
through next week will remain on the cool side with highs in the
upper 60s to around 70 degrees and overnight lows in the 40s across
the lower deserts. These values will be a good 7-10 degrees below
normal. In addition to the cool temperatures, dry conditions will
continue with no noticeable weather features on the horizon to
result in the potential for precipitation.
&&
.AVIATION...Updated 2300Z.
South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
No weather concerns will exist through Saturday afternoon under
periods of high clouds. While the typical nocturnal easterly winds
and diurnal west winds will arrive, speeds will be under 8kt and
prolonged periods of nearly calm conditions will be common.
Southeast California/Southwest Arizona including KIPL and KBLH:
No weather issues will exist through Saturday as high cirrus clouds
slowly clear. Light N/NW winds will be preferred through the
overnight with extended periods of variable directions more common
Saturday afternoon.
&&
.FIRE WEATHER...
Mainly dry weather conditions will prevail through at least the next
7 days with temperatures remaining well below normal, with highs
generally in the upper 60s to around 70 degrees across the lower
deserts. Winds will remain fairly light today and Saturday, however,
a fast moving weather system moving through Sunday into early Monday
will result in another round of breezy conditions, especially across
portions of southeast California and the Lower Colorado River
Valley. MinRH values during the next several days will generally
range between 15 and 25% areawide.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&
$$
DISCUSSION...Hirsch
PREVIOUS DISCUSSION...Lojero
AVIATION...18
FIRE WEATHER...Lojero
Area Forecast Discussion
National Weather Service Great Falls MT
801 PM MST Fri Nov 11 2022
.SYNOPSIS...
Fair weather continues on Saturday, though increasing clouds will
be noticed across the area as some high level clouds pass through.
Clouds will lower and thicken on Sunday as a weak disturbance
moves in from the north, and a few light snow showers are
expected, mainly over the higher terrain.
&&
.UPDATE...
A tighter surface pressure gradient along The Rocky Mountain Front
favors some stronger winds than originally forecast. Additionally,
surface high pressure to our south southeast, in association with an
upstream approaching surface low, favors stronger winds across
southwest Montana. Have increased wind/wind gust values, and then,
interpolated out to 12/06Z, as pressure gradient should gradually
relax over the next few hours, favoring reduced wind/wind gust
speeds, by then. No further updates are required, at this time.
- Fogleman
&&
.DISCUSSION...
Current satellite imagery this afternoon reveals that a sun-
filled bluebird winter day is underway for most of North-Central
and Southwestern Montana, with the only exception to this sun-
filled day being the area in and around West Yellowstone. Thanks
in part to the abundant sunshine today, many areas have warmed
into the 20s, though the cold is being stubborn in a few of the
valleys and keeping temperatures in the teens.
Clouds will begin to move into the area this evening, which will
help keep temperatures from getting quite as cold as they have
been in recent nights. However, given the still fairly-fresh
snowpack, temperatures will likely drop rather quickly after
sunset, then stabilize a bit once the clouds move int. Overnight
lows will range from a few degrees below zero in the Milk River
Valley to the upper teens in the downslope areas along the Rocky
Mountain Front and on the northern slopes of the Little Belt and
Snowy Mountains.
Our weather will become slightly more active late Saturday and
Sunday as a weak upper level disturbance moves in from the north.
This disturbance will mainly bring a few clouds to the area for
the day on Sunday, but a few isolated to scattered snow showers
will be possible, especially in the higher terrain and along the
north slopes of the Little Belt and Snowy Mountains. Any snowfall
accumulations will be on the light side, but they may be able to
make roads slick as they pass through.
Looking into the work week, upper level flow will remain out of
the northwest, keeping us noticeably cooler than average for this
time of year, along with occasional light snow chances. The best
of these chances will arrive late next week as a cold front pushes
through the area, bringing the chance for more widespread
snowfall and another round of colder air to the region. Ludwig
&&
.AVIATION...
525 PM MST Fri Nov 11 2022 (12/00Z TAF period)
VFR conditions are forecast, with some airfields experiencing
possible reduced visibility in mist; however, due to low confidence,
have not included MVFR/IFR conditions in TAFs. Having said this,
confidence is high that mist/fog will develop through some mountain
valleys/passes, favoring reduced visibility, and impacting light
aircraft ops. Also impacting light aircraft, expect some
breezy/gusty funneled winds through some north/south oriented
mountain valleys/passes of southwest Montana in association with
southerly winds.
- Fogleman
Refer to weather.gov/zlc for more detailed regional
aviation weather and hazard information.
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 30 6 31 10 / 0 0 0 10
CTB 30 6 32 10 / 0 0 0 10
HLN 28 6 31 12 / 0 0 0 0
BZN 26 -2 29 6 / 0 0 0 0
WYS 23 -11 30 0 / 0 0 0 0
DLN 22 3 28 8 / 0 0 0 0
HVR 14 -10 21 5 / 0 0 0 10
LWT 32 6 35 12 / 0 0 0 10
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
http://www.weather.gov/greatfalls