Forecast Discussions mentioning any of "ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 11/13/22

Area Forecast Discussion

National Weather Service Quad Cities IA IL

 747 PM CST Sat Nov 12 2022

.UPDATE...
Issued at 743 PM CST Sat Nov 12 2022

Clearing trends have not started, and models are at least 12 hours
off on this developing. Models has suggested clearing through
central Iowa this afternoon and evening, and it`s barely touching
southwest tip of the state. So, for tonight, I`ve warmed
temperatures to the 90th percentile NBM, which is mid to upper 20s
for lows, and gone cloudy through the night. Tomorrow, I have
begun taking a sunny forecast to a one at least starting with
plenty of clouds. This may end up holding tomorrows highs several
degrees colder than currently forecast if we battle cloud cover
all day. This is certainly my most traditional forecast update
issued in November.

ERVIN

&&

.SYNOPSIS...
Issued at 245 PM CST Sat Nov 12 2022

Upper level trough and embedded disturbances within cyclonic flow
has led to periodic bouts of mainly flurries and snow showers
with minor accums on grassy/elevated areas, and even very minimal
freezing drizzle earlier this morning along with some graupel
recently as GOES-16 cloud top phase and snow/ice bands and ACARS
soundings depicting presence of largely supercooled water droplets
with some ice with cloud tops in that range of -5c to -10c. In
addition, radar shows a concentrated band of enhanced returns into
lower RI county, NE Mercer county and far SW Henry county in IL,
which we believe is attributed to river effect snow given
favorable WNW fetch in strong CAA (850 hPa temps -13c) along that
portion of Miss River and also Lake George with also some
orographic lift from bluffs. Earlier pics showed over half inch of
snow, and given longevity we could be over 1 inch or a bit more
in this band, mainly on grass and elevated surfaces. Aside from
this, it`s a winter day with temps struggling into the 30s and
gusty winds making it feel more like the teens and 20s.

&&

.SHORT TERM...(This evening through Sunday)
Issued at 245 PM CST Sat Nov 12 2022

Key Messages:

1) Flurries/Snow Showers end this evening with some partial
clearing possible.

2) Unseasonably cold to persist.

Discussion:

Snow showers and flurries should diminish this evening with the
passage of an upper level trough. Subsidence may lead to at
least partial clearing later tonight in wake of passing upper
trough and incoming surface ridge. The nature of the clouds
on visible satellite would look to support the potential for some
increase in breaks especially through the heart of the service
area, but it`s possible clouds hold on longer in more persistent
stratus west/south. Forecast lows will be dependent on the cloud
trends, and due to the uncertainty have kept it near 50th
percentile of NBM. Areas that clear out and see winds diminish
can expect to drop into the teens, while any areas that keep the
clouds could only drop into the mid/upper 20s.

Sunday will remain unseasonably cold, but the presence of some
sunshine likely and the lack of wind should make it feel a
bit better. Highs should get back into the mid/upper 30s, and
possibly near 40F in a few spots especially south with any full
solar insolation.


.LONG TERM...(Sunday night through Saturday)
Issued at 245 PM CST Sat Nov 12 2022

Key messages:

1. Turning active early next week with increasing confidence on
first widespread accumulating snow Monday night-Tuesday.

2. Another round of snow possible Wednesday.

3. Well below normal temperatures and dry conditions Friday and into
the weekend.

Sunday night-Tuesday...broad ridging aloft moving east will make for
a quiet start to the period with clear skies and light southeast
winds Sunday night. This will allow lows to drop into the lower 20s.
Attention then turns to the wave interaction between strong southern
stream wave and northern Great Plains wave. Latest 12z models now
show phasing not occurring until Tuesday. The southern stream
wave will be the primary system to impact the CWA Monday night-
Tuesday. While the bulk of the moisture and lift will remain south
in Missouri, a portion of the precip shield should reach our
southern half of the CWA. Thermal profiles all support snow as the
dominant ptype overnight and on Tuesday for some light snow
accumulating on elevated and grassy surfaces. With air temps just
below freezing and pavement temps above freezing, not anticipating
more than a dusting on roads at this time. That said, slick spots
will still be possible during the Tuesday morning commute and
with it being the first chance of measurable snow, motorists will
need to remember their winter driving skills and take it slow.
Additional light snow showers will be possible through the day
Tuesday especially over northern IL. Total amounts are still
uncertain at this juncture, but NBM 1" probs have increased
slightly and now are in the 25-40% range. With occasional snow
showers and overcast clouds, lowered highs near the 10th
percentile for Tuesday which results in readings in the mid to
upper 30s.

Tuesday night-Wednesday night...Another chance of snow will be
possible Tuesday night as a secondary wave rotates around the
longwave trough overhead. There are differences in the strength and
speed of this system and for now will keep slight chance to chance
PoPs for snow in the forecast.

Thursday-Saturday...this period will be characterized by colder
temperatures and mainly dry conditions resulting from a re-
enforcing shot of arctic air dropping south out of Canada. 850mb
temps in the -17 to -20C range in the northwest flow aloft will
bring highs only in the 20s Friday and Saturday with lows in the
single digits.

&&

.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 515 PM CST Sat Nov 12 2022

Flurries and snow showers continue to drop south to southeast over
eastern Iowa and northwest Illinois at the start of the period.
Outside of the showers, generally VFR cigs are found, but this
will be a variable period through 02Z with brief periods of IFR
visibility possible, mainly at MLI and DBQ. Otherwise, a general
trend toward VFR is indicated by all models, but a look at
observations shows the west edge of stratus to the west of here,
with cigs of 1500 to 3500 ft, so there may be another period of
lower cigs later tonight, and will monitor that trend.


&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&

$$

UPDATE...Ervin
SYNOPSIS...McClure
SHORT TERM...McClure
LONG TERM...Gross
AVIATION...Ervin