Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/23/22
AREA FORECAST DISCUSSION
National Weather Service Hastings NE
952 PM CST Tue Nov 22 2022
...Short Term Update...
Issued at 951 PM CST Tue Nov 22 2022
-- Regarding at least limited (in area) fog/dense fog potential
Wed AM...especially between 7-10 AM:
- The basics:
By far the main change to the very short term forecast since the
main afternoon issuance has been the addition of "patchy" to
"areas" of fog to parts of our southeastern coverage area (CWA)
for Wed AM...perhaps affecting the AM commute. Given that high-res
models such as HRRR continue hinting that at least some potential
exists for localized dense fog (reducing visibility to 1/4 mile or
less), have introduced this mention to our Hazardous Weather
Outlook (HWOGID) to heighten awareness a bit. This fog/dense fog
potential would mainly impact areas near/east of Hwy 281 in our KS
zones along with Nebraska areas mainly south of a Geneva-Blue Hill
- More details:
Concern is gradually increasing that at least a small portion of
our CWA could deal with a round of at least brief fog/dense fog on
Wed AM...particularly between 7-10 AM. There is a pretty decent
low level moisture disparity at this time within our CWA, noted by
dewpoints of 14 at Hastings...versus 30 at Hebron/34 at Concordia
KS. As temps continue to cool overnight and breezes remain light,
enhanced relative humidity along/near this weak boundary
("moisture front" if you will) could support at least a narrow
zone of fog/dense fog. Leaning pretty heavily on HRRR/SREF
visibility progs, any potential fog should be mainly confined to
the southeast 1/4 of our CWA ("safely" southeast of the Tri
Cities), and mainly be a 7-10 AM issue. Do not have enough
forecast confidence in coverage/duration of truly dense fog to
hoist a formal Advisory at this time, but enough potential exists
for introduction to our HWO. This is not a "slam dunk" dense fog
setup by any means, as for one thing, increasing high level cirrus
clouds overnight into Wed AM could hinder fog development. At the
very least, something upcoming overnight/day shifts will need to
.DISCUSSION...(This evening through Tuesday)
Issued at 314 PM CST Tue Nov 22 2022
* Possible drizzle Wednesday night into early Thursday morning
southeast of the Tri-Cities.
* Thanksgiving will likely be the coolest day of the week and
rather breezy, but highs should still be in the 40s.
* Next storm system should pass to our southeast on Saturday, but
there could be a little light rain in our far southeastern
* Another storm system on Tuesday November 29th could bring wintry
precipitation to the area, but low confidence on storm track
this far out.
Rest of Today...
Get outside and enjoy what remains of the afternoon as it`s the
nicest day of the upcoming week with most locations hovering
around 60 degrees at 3 PM. The airmass is dry and thus it will
quickly cool down this evening once the sun gets low and
Wednesday into Wednesday night...
Forecast models indicate increasing clouds and especially low
clouds by late day into Wednesday night particularly across our
southeastern zones. The 18Z NAM is probably the most aggressive
with a drizzle signature in its soundings and QPF field, but
probably too aggressive. Temperatures aloft are too warm for snow
and all of the moisture is in the low levels generally from
around and below 850 MB. Temperatures might actually warm towards
Thursday/Thanksgiving morning. So if any precipitation falls it
will be either drizzle or freezing drizzle, but believe surface
temperatures should climb to just above freezing if drizzle starts
to fall. Therefore, drizzle is the most likely precipitation type
Wednesday night into early Thursday morning.
It`s a case of bad frontal timing that will lead to a rather
unpleasant Thanksgiving day with cooler air moving in along with
blustery northwest winds gusting 20-25 MPH behind a late
Wednesday night/early Thursday morning cold front. Forecast model
temperature spread is rather low allowing for high confidence in
highs being stuck in the 40s for Thanksgiving.
Friday and Saturday...
After the cool down on Thanksgiving Day, model ensembles indicate
that Friday and Saturday should be the best two days of the
remaining weekend, but not as warm as we have been. At this point
it appears we will likely be in the lower 50s, but some ensemble
members keep us in the upper 40s. One thing to watch will be a
closed upper low that will track across the southern plains. It
could swing just far enough north under more northerly model
solutions to bring some light rain to our far southeastern
counties on Saturday.
Sunday through Tuesday...
We`ll be between storm systems on Sunday and Monday, with the next
storm system currently expected to enter the plains by around
Tuesday, but the track is rather uncertain being 7 days out.
Will really need to keep an eye on Tuesday as wintry
precipitation could be possible across portions of our area
depending on the storm track.
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Thursday)
Issued at 611 PM CST Tue Nov 22 2022
-- General overview (including winds):
Very high confidence in VFR ceiling/visibility through at least
the vast majority of the period (only some high level clouds), and
very high confidence in precipitation-free conditions throughout.
The only "catch" is a very outside chance that a possible area of
fog and/or very low stratus could try flirting with especially
KGRI for a few hours Wed AM (more on this below).
As for winds, no big issues to speak of. These next 16 hours or so
will see speeds average mainly near-to-under 5KT, with direction
eventually becoming a bit more established from the south late
tonight into Wed AM. Around and especially after 16Z, southerly
speeds will pick up modestly, but still only average around
sustained 10KT (perhaps some few gusts to around 15KT).
- Slight uncertainty/concern with ceiling/visibility:
Particularly between 12-17Z, various models/guidance are
suggestive that the extreme north-northwest edges of an area of
fog and/or very low stratus could advance within perhaps as little
as 25-30 miles of mainly KGRI (KEAR currently appears to be less
of a "close call"). At least for now, KGRI appears "safely" VFR,
but should this area of fog and/or stratus advect a bit farther
north-northwest than currently anticipated, the going VFR forecast
could really fall off the rails fast, so this certainly bears
watching...just in case.
Area Forecast Discussion
National Weather Service Indianapolis IN
1004 PM EST Tue Nov 22 2022
Issued at 1002 PM EST Tue Nov 22 2022
Looking at the latest observations this evening, temperatures appear
to be highly dependent on topography and local wind conditions.
Readings from near 30 to around 40 degrees were common across the
area. Large differences in temperature across short distances were
apparent as well, with 5 to 10 degree variations within 10 or so
miles. Made slight adjustments given the current obs and continued
stabilization of the boundary layer, clear skies, and decreasing
winds. Kept low temperatures largely the same for most locations,
but added weight to hi-res models such as the HRRR which seem to
have a better grasp on the finer details seen in obs. Adding more
weight to the hi-res guidance allows forecast temps in features
such as river valleys to be a tad cooler than surrounding areas.
Vice versa for slightly elevated areas. Such adjustments should
help better capture the localized variability, as is common under
temperature patterns driven primarily by radiational cooling.
Aside from that, sky and wind grids look good with no changes
.Short Term...(This evening through Wednesday)
Issued at 250 PM EST Tue Nov 22 2022
* Warming trend continues through midweek with highs nearing 60F
* Very dry conditions persist
.This evening and tonight...
Current surface analysis shows surface high pressure stretching from
Texas towards the Mid Atlantic with lower pressure across the
Northern Plains and along the Front range. Clear skies are found
across the entire state as a very dry atmosphere and subsidence
under the high are keeping any clouds and precipitation away. 18z
IND ACARS soundings shows a very similar picture this afternoon as
the past few days with a shallow mixed layer near the surface
bringing down slightly drier air and stronger winds aloft. Today,
the LLJ is much weaker than yesterday resulting in sustained winds
only around 10-15 kts with gusts remaining under 20 kts so far. With
such a dry environment, temperatures have soared with ample sunshine
well above NBM 90th percentile high. Have continued to bump highs up
into the mid and even upper 50s across the region for this afternoon
Expect temperatures to plummet once again tonight as conditions will
be conducive for radiational cooling to take place. Despite the
center of the high south and east of the region, the pressure
gradient is still weak enough for winds to relax and even go calm in
a few wind sheltered areas. With dew points in the lower 20s this
afternoon, would not be surprised to see many areas reach the mid to
upper 20s by tomorrow morning. Lower 30s likely around the Indy
Metro due to the urban heat island.
Very similar synoptic set up tomorrow with high pressure remaining
across the Mid Atlantic states and low pressure continuing to
develop across the western Plains in response to a deepening upper
trough. Southerly flow continues to slowly advect a warmer airmass
into the region as highs have been a few degrees warmer than the
previous day each day this week. With increasing upper heights and
temperatures aloft at 850mb rising from around 2C today to up to 6C
tomorrow, max temperatures will likely be pushing 60 degrees,
especially in known warmer areas such as the Indy Metro. Forecast
soundings show mixing heights up around 2-3 kft, so expect dry air
and stronger winds to mix down to the surface again during peak
heating of the day. With weak moist air advection taking place with
persistent southerly flow, dew points and RH will be slightly higher
than the previous day. Still, with such dry conditions at the
surface, expect RH values to significantly drop during the afternoon
making for a slightly elevated fire threat. Winds are not expected
to be strong with max gusts around 10-15 kts according to forecast
Did similar forecast techniques as the past few days since it has
been verifying well and the pattern is remaining largely the same.
For max temperatures and winds going above NBM 90th percentile,
while trending towards the lowest end of guidance for Dew Point and
RH values due to afternoon mixing and very dry antecedent
.Long Term...(Wednesday night through Tuesday)
Issued at 250 PM EST Tue Nov 22 2022
* Mild and Dry through Thanksgiving
* Rain Chances return late Thursday Night through Sunday
A ridge axis over the Mountain West will progress eastward,
supported by moderate 850-750mb WAA within SW flow. This flow will
also provide some moisture return, with a saturating moisture
profile above 800mb. Thursday morning will still be rather dry with
mostly clear conditions outside of upper level cirrus within a
strong upper level jet. Clouds will fill in throughout the day as
the upper atmosphere saturates. The PBL should be well mixed with
the near surface layer remaining dry. This should promote efficient
warming, with a slight cap on the afternoon with increasing cloud
cover. Expect afternoon highs in the upper 50s to low 60s.
Thursday Night through Friday...
An upper level trough will near from the west/northwest Thursday
night. The main vorticity lobe in the trough apex will separate from
the polar jet, leaving a weakly forced upper to mid level trough
over the upper Midwest. Precipitation over the Tennessee Valley will
limit surface moisture return, but the upper to mid levels will be
saturated. A seeder feeder effect within weak ascent should be
enough for light rain to occur overnight. QPF will be marginal, with
current expectations of less than 0.20". The trough axis will exit
Friday morning, with increasing heights promoting large scale
subsidence by Friday afternoon. Temperatures will remain mild with
little to no CAA behind the trough.
Saturday and Sunday...
The aforementioned vort max displaced from the polar jet will
progress to the NE later this week within a strong subtropical jet
streak on its eastern flank. This will once again push warm air over
the Ohio Valley, keeping conditions mild even with sustained cloud
cover. As the upper level low pushes NW, surface cyclogenesis is
likely to occur to its NE, quickly occluding as the Dry Conveyor
Belt wraps around. This should place a vertically stacked low over
the Western Ohio Valley late Saturday into Saturday night. Surface
moisture return should be much more sufficient for this event, and
with strong ascent within CVA, bands of moderate rain will likely
form. This should lead to higher QPF within this event (0.5-1.0").
There is still a lot of uncertainty with the track of the closed
low, leading to a wide array of precipitation solutions both timing
and amounts. By Sunday night, the low should be out of the region,
with precipitation chances decreasing rapidly.
.Aviation...(00Z TAF Issuance)
Issued at 618 PM EST Tue Nov 22 2022
VFR conditions are expected through the TAF period at all terminals.
Broad surface high pressure to our southeast will allow winds to
retain a south-southwesterly component through tonight and most of
tomorrow. A decaying cold front approaching from the northwest will
cause the surface pressure gradient to weaken a bit, so lighter
winds are expected tomorrow compared to today. Nevertheless, some
occasional gusts to around 10kts are possible at times during the
afternoon. No sensible weather is expected with the weakening front,
but some high clouds may begin to stream in from the southwest after
about 21z. Winds remain light into Wednesday evening, but slowly
become southeasterly after 00z as the surface high moves to the
...Updated Aviation Forecast Discussion...
Issued at 333 PM CST Tue Nov 22 2022
- Mild weather, highs in the 40s and 50s, sticks around through
- Thanksgiving travel should be free of significant weather
related disruptions in eastern Nebraska and western Iowa.
At 2 PM, fair skies prevailed across Iowa and Nebraska. A weak
surface front was hanging out just north of Interstate 80. South
of the front temperatures over preformed today, with both Lincoln
and Omaha cracking the 60 degree barrier.
Tonight & Wednesday:
A weak frontal boundary will be draped along the Interstate 80
Corridor tonight. North of the boundary skies should be fair and
overnight lows should dip into the upper teens or twenties. South
of the boundary there is a small chance (10%) of fog developing
by sunrise Wednesday due to low level moisture advection. Right
now the NAM with its tendency towards a wet bias remains the most
aggressive guidance, but there are hints of near surface
saturation in the HRRR and WRF ARW. If fog forms, it would be
most likely from Beatrice to Falls City to Shenandoah.
A upper level trough over the Rockies and developing lee trough over
the High Plains will bring steady southerly winds back to the Plains
on Wednesday. This should keep weak low level WAA and moisture
advection going through the day and push afternoon highs into the
50s. Increasing clouds are expected Wednesday evening.
Wednesday Night through Friday:
During this period the trough over the Rockies will dig south, and
evolve into a cutoff low over Texas. Meanwhile a cold front should
push east through Nebraska and Iowa. Northwest winds behind the
front will usher a cooler airmass into our region and we expect
temperature declines of about 10 degrees on Thanksgiving (compared
to Wednesday). Our going forecast has afternoon highs in the 41 to
46 degree range.
Low level moisture should continue to deepen Wednesday night. This
could lead to a 2,000 to 4,000 ft saturated layer by Thursday
morning, and result patchy drizzle develop along and south of
Interstate 80. For now the majority of the guidance keeps surface
temperatures above freezing Thursday morning and so any drizzle
should be a travel nuisance rather than a frozen problem. We will
continue to monitor just in case a narrow window for freezing
drizzle develops behind the front.
Drizzle chances should fall through the day on Thanksgiving as the
surface front pushes eastward. Winds behind the front will be breezy
from the north, with occasional gusts near 35 mph. The drier
weather pattern should linger through the day on Friday.
Over the Weekend:
Ensemble and deterministic guidance continue to struggle with the
closed low lifting out of Texas on Saturday. Overall the trend has
been towards a slight northern shift in track over the last 36
hours. This places southeast Nebraska and southwest Iowa on the
northern periphery of the system Saturday afternoon. If some
precipitation does occur, it would likely be rain given the
diurnal timing. We will continue to monitor, but for now the
greatest precipitation chances remain over Kansas and Missouri.
Temperatures over the weekend should be close to seasonal averages
with highs in the 40s.
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 520 PM CST Tue Nov 22 2022
Quiet TAF period with VFR conditions prevailing. Winds are
becoming light and variable now and will become SSE by Wednesday
morning. They`ll slowly gain speed from about 5 knots to about 11
knots by Wednesday evening.
Area Forecast Discussion
National Weather Service Reno NV
110 PM PST Tue Nov 22 2022
Quiet weather will continue through Thanksgiving Day with mainly
light easterly winds and near to slightly below normal
temperatures. Friday into the weekend, temperatures will warm with
a turn to more southwesterly winds, ahead of what could be a
series of winter storms Sunday into mid next week. While
confidence in specific scenarios is low, periods of wind, rain, or
snow are possible for travelers heading home from the holiday
A dry cold front moving through the Great Basin tonight will help
kick up NW winds aloft on ridgelines to around 20-30 MPH but with
only minimal increase in wind for lower elevation valleys. With
main cold air off to our east, temperatures over the Sierra & W
Nevada don`t cool off that much such that lower valley inversions
may persist into Wednesday. That means some haze or patchy dense
fog is possible again, such as around Mono Lake, but confidence is
lower than last couple nights. Current thick high clouds likely to
continue at least through the evening per HRRR guidance.
By sundown Wednesday into early Thursday morning, winds aloft shift
to more of a E/NE direction which favors some strong gusts over the
Sierra crest, but nothing too bad given 700mb wind speeds of only
15- 25 knots in latest GFS. We might see some of that easterly
flow surface around Lake Tahoe Wednesday afternoon and evening,
per latest HRRR and NAM 3km, but not nearly enough for lake wind
advisory conditions. Otherwise most valleys will remain light and
variable on the winds with near to just below normal temperatures.
.LONG TERM...Thanksgiving Day onward...
Expect dry and mild conditions to continue on Thanksgiving day, as
the ridge axis amplifies over the CA/NV border. Skies will be mostly
clear, with some haze from valley inversions lingering in urban
locations. Near-average temperatures and light winds will continue.
We will see similar conditions persisting through Friday as the
ridge lingers over the western US, though temperatures will run a
few degrees above-average. Perfect conditions to get outside and
enjoy the holiday weekend with loved ones!
A trough will begin to deepen off the coast of British Columbia on
Saturday afternoon, subsequently nudging the ridge east and opening
the door to more active weather for the end of the weekend into
early next week. Our next main storm system looks to arrive Sunday,
and here`s what we know and don`t know so far:
* WINDS: There are some discrepancies between models at this time
regarding the potential for gusty winds ahead of the main storm
system. The ECMWF ensemble shows the aforementioned trough
splitting off the coast of the Pacific Northwest and ejecting a
shortwave into northern CA/NV. If this scenario verifies, gusty
winds could develop as early as Saturday morning. Instead of
splitting the trough, the GFS ensemble suggests the trough will
continue to drift eastward over Canada. This scenario would
produce no impact to our region, with lighter winds continuing
until the main storm system arrives on Sunday. Confidence is
higher in terms of winds for this main system, with gusty winds
developing across the region on Sunday afternoon. Winds are
expected to peak Monday morning as a cold front pushes through our
region. Ridge wind gusts in excess of 60 mph are possible, and
valleys will see gusts between 15-25 mph.
* RAIN/SNOW: Given the ECMWF trough splitting scenario, we can`t
rule out some light precipitation along the Sierra crest on
Saturday morning. However, chances for this scenario are lower
(10% chance). The main system brings a more promising chances
for measurable precipitation Sunday afternoon through Tuesday
morning as models are generally trending wetter. Snow showers
are likely (70% chance) to begin along the Sierra crest on
Sunday night and continue through Monday. Precipitation looks to
begin in valley locations early Monday morning, though
precipitation type is uncertain at this time. However, nearly
all ensemble members have at least a trace of snow down to the
valley floors, so it looks likely that precip could change to
snow at some point as the cold front passes through.
Precipitation is expected to wind down overnight on Monday, with
some lingering mountain snow showers through Tuesday morning.
Another day of strong valley inversions with haze and light winds
today. Brush-by dry cold front tonight will help increase NW
winds aloft but only minimal wind increases in valley locations.
Thick high clouds will move over the area through at least this
Flow on Wednesday turns more E/NE. This pattern typically results
in only limited wind increases for valleys except around CXP
which responds well to E/NE patterns. A few strong gusts over the
Sierra crest from Tahoe south to near Mammoth are a good bet, with
that increased E/NE flow, there could be some wind shear issues
near TRK/TVL Wednesday evening and night.