Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/19/21
Area Forecast Discussion
National Weather Service La Crosse WI
603 PM CST Sat Dec 18 2021
.SHORT TERM...(This evening through Sunday)
Issued at 235 PM CST Sat Dec 18 2021
-Quiet weather rounds out the weekend with seasonal temperatures.
It`s been a wild last week of weather and a well deserved break
continues for the rest of the weekend. A shallow upper level
trough brought light snow to the region this morning, but has
since shifted east of the forecast area. Low stratus/stratocumulus
persists well into the overnight hours within the northwesterly
flow in place over the Upper Mississippi River Valley. Surface
ridging over the eastern Dakotas meanders eastward for tonight and
departs by sunrise. Southerly flow increases during the day ahead
of the next frontal system ejecting across the Northern High
Plains.
The biggest question in the forecast revolves around low-level
cloud cover, especially on the backside of the ridge axis. RAP
forecast profiles are quite robust on keeping the low clouds
around while over solutions are not as bullish. The best chance of
clearer skies will be over the southern forecast area during the
day on Sunday. Modest WAA during the day should nudge highs on
Sunday back into the low to mid 30s area-wide.
.LONG TERM...(Sunday night through Saturday)
Issued at 235 PM CST Sat Dec 18 2021
-Weak weather systems move through during the week with the
impactful snow threat on the low side.
-Keep an eye on the forecast for around the Christmas holiday.
A progressive upper level pattern ushers multiple weak
disturbances over the region, the first of which will be on Sunday
night into Monday. Forecast soundings and EPS progs are quite dry
with its passage, with the best chance of any light flurries
being over northern Wisconsin. High pressure builds in for late
Monday into Monday night, with the next undulation rippling
through on Tuesday. The track of this system follows a similar
course to its predecessor, mainly north of the forecast area with
the best chance of snow residing over northern Wisconsin and the
Minnesota Arrowhead.
The next system in the caravan comes through Wednesday night, but
again will suffer from a lack of moisture and will be rather
transient in nature. Confidence in the forecast going into the
Christmas holiday degrades, but a deepening upper tropospheric
trough across the Pacific NW could eject several shortwaves over
the region during the holiday weekend that may have a better
chance of producing impactful precipitation.
The temperature forecast for the first half of the week varies
little with highs in the 30s, but there are hints that warmer air
returns for the end of the week. Most of the ensemble guidance is
pushing into the 40s for that timeframe.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 555 PM CST Sat Dec 18 2021
Variable MVFR/VFR ceilings tonight with weak low level flow and
patches of cloud-free areas. Light northwest winds become south
Sunday and increase 12 to 18kts with gusts 20 to 30kts. Some
flurries possible, however confidence in timing too low to
include. Ceilings improve to VFR 16-20Z with high clouds in the
area. Potential for low level wind shear increases after 22Z.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&
$$
SHORT TERM...Skow
LONG TERM...Skow
AVIATION...Zapotocny
Area Forecast Discussion
National Weather Service Lincoln IL
734 PM CST Sat Dec 18 2021
.SYNOPSIS...
Issued at 145 PM CST Sat Dec 18 2021
Dry weather is expected the rest of the weekend and through most
of next week, with chilly temperatures through tomorrow. However,
warmer conditions are expected through the new week.
&&
.UPDATE...
Issued at 733 PM CST Sat Dec 18 2021
Main forecast issue tonight will be with the clouds. Stratocumulus
is mostly limited to areas near/east of I-55 early this evening,
with some renewed development just southwest of Peoria. Additional
clouds around 2,000 feet are oozing south from northern Illinois.
While some holes are developing upstream over parts of Wisconsin
and Iowa, the latest HRRR model shows these clouds spreading over
much of the CWA west of I-57 after midnight. This is supported on
RAP soundings by a pinch of moisture around 900 mb increasing
after midnight, though the new NAM is showing a slower arrival of
said moisture. Did some beefing up of the sky cover in the grids,
though this did not have an appreciable effect on the worded
forecast.
&&
.SHORT TERM...(This evening through Sunday)
ISSUED AT 145 PM CST Sat Dec 18 2021
High pressure will drop into the area by tomorrow morning with dry
conditions. Chilly temperatures are expected through Sunday with
overnight lows in the middle to upper 20s followed by Sunday highs
only in the middle to upper 30s.
&&
.LONG TERM...(Sunday night through Saturday)
ISSUED AT 145 PM CST Sat Dec 18 2021
Dry weather is expected through most of the period despite a cold
front moving through the state middle of the week. The next chance
of rain will be Friday afternoon through Friday night, but there
is some considerable spread with model solutions at this point.
Therefore, an ensemble forecast looks good for now, with pops
in the slight chance category over most of the CWA and chance pops
in far eastern IL for Friday evening. Hopefully a better consensus
will be seen with later model runs. Most of the precip that does
occur during that period will be rain, but a mix of rain and snow
might occur in far northern parts of the CWA Friday night.
The main focus in the extended period is temperatures. All
extended model ensembles agree that warmer than normal temps will
occur Thur through Sat. A large area of unseasonably warm air is
expected to build across the middle of the US from middle of the
week into the Christmas weekend and this will include central IL.
After normal temps for Wed, behind that dry cold front, temps are
expected to reach into the 50s by Fri and Sat, which is around 15
degrees above normal for this time of year. These warm conditions
in December do occur in central Illinois at times, but will be
nowhere near records, as those are in the 60s.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 522 PM CST Sat Dec 18 2021
While much of central Illinois is still seeing ceilings below
3,000 feet early this evening, a clear area was located in western
Illinois and adjacent areas across the Mississippi River. Some
concern as to how much of this is going to remain clear, as
stratocumulus oozes south from Iowa/northern Illinois. HRRR
ceiling plot suggests potential for southward expansion,
especially after 06Z. Will need to monitor this closely, but for
now, am thinking all terminals should be VFR by about 03Z.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Geelhart
SYNOPSIS...Auten
SHORT TERM...Auten
LONG TERM...Auten
AVIATION...Geelhart
Area Forecast Discussion
National Weather Service North Platte NE
548 PM CST Sat Dec 18 2021
.SHORT TERM...(This evening through Sunday night)
Issued at 337 PM CST Sat Dec 18 2021
The models are in very good agreement warming h850mb temperatures
to around 10C Sunday. This should support highs in the mid 50s or
warmer and the temperature forecast leans on the warmer RAP model
for highs. This is near the 50th percentile of the NBM but a few
degrees cooler than the very warm guidance blend. Given that high
clouds will remain mostly north of the region, the temperature
forecast Sunday could be too cool.
The guidance blend plus bias correction is in place for lows in
teens and single digits tonight, and teens and 20s Sunday night. A
southerly low level jet develops tonight in tandem with low level
warm air advection. A back door cold front will begin moving through
wrn and ncntl Nebraska Sunday night. Thus, neither tonight nor
Sunday night appear to be strong radiational cooling events,
especially given the SREF indicates stratus will form along the cold
front Sunday night.
.LONG TERM...(Monday through Saturday)
Issued at 337 PM CST Sat Dec 18 2021
There is little change in the extended forecast philosophy today.
A Pacific cold front will move through wrn and ncntl Nebraska
Tuesday followed by a protracted period of warm air advection
Wednesday through Saturday. The ECM and GEM suggest the potential
for a back door cold front Friday night but it would appear the
front will hold up and become stationary across the Missouri river
valley, just north and east of wrn and ncntl Nebraska. WPC, like
the GFS, supports this forecast.
The models are in very good agreement developing a long wave trof
off the West Coast next week and place a 984-994 mb sfc low off the
coast of Washington state by Friday. The associated long wave trof
off the West Coast should support a surge of warm desert air across
the Rockies and into Nebraska Tuesday and beyond. Highs in the 40s
and 50s are in place Tuesday through Saturday- cool air and stratus
hold down highs Monday to the 20 and 30s.
The temperature forecast Tuesday and beyond is middle-of-the-road
for one reason-bouts of high level cloudiness at times will affect
the very short daytime heating cycle. If the high clouds can hold
off presenting a clear day, highs in the upper 50s and 60s could
result according to the 90 percentile of the NBM. Later forecasts
may mark up highs several degrees as the predictability of high
cloudiness will improve.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 546 PM CST Sat Dec 18 2021
VFR conditions should prevail over the next 24 hours. Winds will
gradually shift from the southeast this evening to the south
overnight, then to the southwest tomorrow morning. Winds may become
gusty across the area tomorrow afternoon, peaking between 20 and
25 knots. Skies should be mostly clear aside from some high
clouds.
&&
.FIRE WEATHER...
Issued at 337 PM CST Sat Dec 18 2021
Little change was noted in the wind and humidity forecast Sunday.
Fire weather conditions are expected to be elevated across
western Nebraska Sunday afternoon.
The predicted single digits to near 10F dew points and temperatures
in the 50s result in humidity in the 15 to 20 percent range. The
lowest values are expected across swrn Nebraska and the srn
Panhandle and winds are in the 10 to 20 mph range in this area.
North, generally along and north of highway 2, humidity increases to
around 20 percent and winds increase to 20 to 25 mph. Much of this
area received significant rain and snow Wednesday, and in some
cases, snow is still on the ground melting.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...CDC
LONG TERM...CDC
AVIATION...Meltzer
FIRE WEATHER...CDC