Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/20/23
Area Forecast Discussion...UPDATED
National Weather Service Albuquerque NM
432 PM MST Tue Dec 19 2023
...New AVIATION...
.SYNOPSIS...
Issued at 105 PM MST Tue Dec 19 2023
Clouds will continue to slowly lower tonight with a few areas of
sprinkles or flurries possible, especially south of I-40. Chances
of rain showers or sprinkles with high elevation snow increase
during the day Wednesday. Mostly dry conditions are forecast for
Thursday, but it will be a short break as a stronger and more
moist storm system is forecast to arrive late Friday into Friday
night and Saturday, bringing more substantial and widespread rain
and snow to northern and central Mexico. Snow levels will be quite
high during the daytime hours Friday, reaching 7,500 to 8,00 feet
before dropping closer to 6,000 feet late Saturday and Saturday
night. Much colder conditions are now expected for Christmas Day.
&&
.SHORT TERM...
(This evening through Wednesday night)
Issued at 105 PM MST Tue Dec 19 2023
A weak short-wave trough aloft is currently producing some light
radar returns over NE Arizona, but doubtful how much, if any, of
this activity is reaching ground level, so have maintained only
silent PoP`s over western zones through tonight. Low levels of the
troposphere are likely just too dry, per 12Z soundings. Heading
into tonight, a somewhat sharper trough aloft, now apparent on water-
vapor satellite imagery moving into SW Arizona, approaches and will
begin interacting with subtropical moisture tap in place. Column RH
increases, especially west of the Continental Divide and over the
northern mountains. HRRR continues to suggest very spotty showers
possibly developing over the northwest plateau as early as midnight,
but should be of little consequence. With thickening/lowering cloud
cover, a relatively "warm" December night is in store, with morning
low temps running generally 8-15 degrees F above climo.
For Wednesday, better lift moves in with the aforementioned
shortwave. The west-central part of the CWA will lie in the left-
exit region of a 100-110KT subtropical jet moving into southern NM.
Meanwhile, precipitable water continues to increase, into the 0.4-
0.5 inch range west of the central mountain chain...and perhaps up
to 0.7 inches over Chaves county by Wed evening. Most likely timing
for precip seems to be in the window from 15Z Wed through about 06Z
Thu, with generally scattered rain showers for elevations below 8000
ft. With the warm Pacific origin of this system, and its main
passage during the daytime hours, snow levels will be rather high,
generally 8-9 kft. Mountain peaks above those elevations could pick
up a dusting to perhaps an inch or two of snow by early Thu morning.
A rumble of thunder or two is not out of the question, either,
mainly for SW portions of the CWA. Despite cloud cover and precip,
max temperatures on Wed still run mainly 5-10F above climo, with the
ABQ metro hitting the low-mid 50s.
Rain chances gradually taper off from west-to-east from Wed evening
onward through the night, as the shortwave dampens and short-wave
ridging starts to enter the picture by early Thursday morning. Mid-
elevations could see a light rain/snow mix develop overnight before
precip winds down, leading to some slick spots on roads.
&&
.LONG TERM...
(Thursday through Monday)
Issued at 105 PM MST Tue Dec 19 2023
A "clean" short-wave ridge of high pressure is forecast to move east
over NM on Thursday with light winds forecast areawide. The
ridge`s influence lasts through Friday morning, ahead of a juicy
closed low just west of San Diego, CA. This low will bring another
round of widespread rain and heavy snow above approximately
7,500-8,000 feet to the vast majority of the forecast area Friday
night and Saturday. Global models agree that the precipitation
will begin in earnest for the western two thirds of the state
after midnight Friday night, continuing at times through Saturday.
Differences in where the highest QPF continue with the operational
GFS favoring central NM and the operational ECMWF favoring the
western quarter. National Blend of Models (NBM) is somewhere in
the middle with widespread third to half inch amounts in the lower
elevations and up to an inch and a quarter liquid falling as snow
in in the mountains.
To put precipitation amounts into perspective so far this
December using ABQ as an example, the 1991-2020 climatological
average for ABQ in December is 0.53". 0.52" fell from the last
system with another third to half inch possible Friday night and
Saturday, making 200% of average a real possibility as early as
this weekend. The second, much colder, closed low continues to be
rather moisture starved, but brings the potential for light snow
to Santa and his reindeer on Christmas Eve night. A little light
snow may just hang on Christmas morning, most likely favoring the
central highlands including Clines Corners, Vaughn, Encino and
Corona. After this system, tranquil weather is forecast for much
of next week. Global models then bring multiple winter storms in
from the west during the first week of the New Year.
&&
.AVIATION...
(00Z TAFS)
Issued at 423 PM MST Tue Dec 19 2023
VFR conditions are expected to prevail through at least 20Z
Wednesday, though cigs will gradually lower with time. A weak
shortwave trough will cross the state on Wednesday, bringing rain
and high elevation snow showers initially to western NM, then
spreading eastward through the evening. A few showers will be
possible as early as 15Z or so across far western NM, but better
chances for KFMN and KGUP to receive precipitation will be aftn
or early eve. Winds will generally remain light through the TAF
period, except with another modest northerly drainage wind
expected at KSAF Wednesday morning.
&&
.FIRE WEATHER...
Issued at 105 PM MST Tue Dec 19 2023
No elevated or critical fire weather conditions are expected over
the next seven days. Mostly cloudy skies, abnormally warm
temperatures, and poor ventilation will be the rule through early
Friday, before some improvement in ventilation rates Saturday and
Sunday. There is a decent shot at wetting rains due to the passage
of a disturbance aloft from tomorrow morning through late Wed night.
Best chances of wetting rains are over the western/southern mountains
and highlands, where a tenth of an inch or two of precip may occur.
A dusting of snow, up to an inch or so, may also occur on high
mountain peaks above 8000-9000 ft. Another stronger, wetter system
brings widespread high mountain snow and lowland rain, focused from
Friday to Saturday...with some lingering rain/snow west of the
central mountain chain into Sunday as the snow level falls with the
passage of a second system, which is forecast to be colder but more
moisture-starved. Breezy westerly winds of 15-20mph at 20 ft. may
develop across the eastern plains and central highlands on Saturday
and Sunday, but the moist airmass and precip will keep minimum
relative humidities above 35-40%.
&&
.PRELIMINARY POINT TEMPS/POPS...
Farmington...................... 31 53 32 53 / 5 20 20 0
Dulce........................... 20 53 22 53 / 5 10 20 0
Cuba............................ 28 49 29 49 / 0 40 30 5
Gallup.......................... 25 50 24 53 / 5 60 30 0
El Morro........................ 28 50 26 52 / 5 60 40 5
Grants.......................... 27 50 26 53 / 0 60 30 5
Quemado......................... 29 52 26 55 / 10 60 20 10
Magdalena....................... 35 52 33 53 / 5 40 30 5
Datil........................... 32 50 29 52 / 10 50 30 5
Reserve......................... 28 55 25 61 / 5 60 30 10
Glenwood........................ 41 58 38 61 / 5 60 30 10
Chama........................... 22 48 22 48 / 5 10 20 5
Los Alamos...................... 31 45 31 46 / 0 20 20 5
Pecos........................... 32 51 31 51 / 0 10 20 10
Cerro/Questa.................... 27 43 28 43 / 0 0 10 5
Red River....................... 19 44 20 43 / 0 0 10 5
Angel Fire...................... 14 45 16 44 / 0 0 20 5
Taos............................ 20 46 23 46 / 0 0 10 5
Mora............................ 26 52 26 51 / 0 5 20 5
Espanola........................ 26 51 28 52 / 0 10 20 5
Santa Fe........................ 32 48 32 48 / 0 10 20 10
Santa Fe Airport................ 29 48 30 48 / 0 10 20 5
Albuquerque Foothills........... 36 53 36 53 / 0 30 40 5
Albuquerque Heights............. 34 53 34 54 / 0 30 30 5
Albuquerque Valley.............. 32 54 34 56 / 0 30 30 5
Albuquerque West Mesa........... 34 53 35 55 / 0 30 30 5
Belen........................... 28 53 31 55 / 0 30 40 5
Bernalillo...................... 32 54 34 55 / 0 30 30 5
Bosque Farms.................... 29 53 31 55 / 0 30 40 5
Corrales........................ 32 54 34 56 / 0 30 30 5
Los Lunas....................... 29 53 32 55 / 0 30 40 5
Placitas........................ 35 50 35 51 / 0 30 30 5
Rio Rancho...................... 33 53 34 55 / 0 30 30 5
Socorro......................... 33 56 34 58 / 0 30 30 5
Sandia Park/Cedar Crest......... 35 47 33 47 / 0 30 40 5
Tijeras......................... 34 50 33 50 / 0 30 40 10
Edgewood........................ 28 49 28 50 / 0 20 30 5
Moriarty/Estancia............... 19 49 22 50 / 0 20 30 10
Clines Corners.................. 28 47 29 47 / 0 10 30 10
Mountainair..................... 30 51 30 51 / 0 30 30 10
Gran Quivira.................... 31 53 31 53 / 0 20 40 10
Carrizozo....................... 36 60 37 58 / 0 30 50 10
Ruidoso......................... 37 56 35 53 / 5 30 50 10
Capulin......................... 31 53 29 52 / 0 0 0 5
Raton........................... 25 53 24 54 / 0 0 5 5
Springer........................ 20 50 22 53 / 0 0 0 5
Las Vegas....................... 28 53 28 53 / 0 0 10 5
Clayton......................... 37 60 37 58 / 0 0 0 10
Roy............................. 29 55 31 54 / 0 0 5 10
Conchas......................... 30 62 36 60 / 0 0 10 10
Santa Rosa...................... 35 60 37 59 / 0 5 20 10
Tucumcari....................... 33 63 38 63 / 0 0 10 20
Clovis.......................... 37 65 41 63 / 0 0 20 20
Portales........................ 35 67 42 63 / 0 0 20 20
Fort Sumner..................... 32 63 39 63 / 0 5 20 10
Roswell......................... 37 65 44 63 / 0 10 40 20
Picacho......................... 38 65 39 63 / 0 20 30 10
Elk............................. 37 66 36 63 / 5 20 40 10
&&
.ABQ WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...53
LONG TERM....33
AVIATION...34
Area Forecast Discussion
National Weather Service Hastings NE
525 PM CST Tue Dec 19 2023
.KEY MESSAGES...
- Possible fog issues these next couple of night?:
Although this was not really on our "radar" 24 hours ago,
latest model data supports at least the possibility of localized
dense fog tonight in our eastern zones, and perhaps more
widespread Wed night (fair amount of uncertainty though).
- Chances for light rain back in our south-southeast coverage
area (CWA) for mainly Thurs afternoon-night:
Although a very minor, light rain (a few hundredths of an inch
at most), a slight chance (20%) for light rain has worked its
way back into our forecast.
- Saturday-Tues storm system still our primary longer-term focus
(nuisance travel issues mainly Sunday evening-Mon night?):
We are still at least a FEW DAYS away from having a more
confident handle on this complex/slow-moving storm system.
However, confidence remains very high that it starts out as RAIN
through much of Sunday, before any possible transition to snow
occurs mainly Sun evening-Mon night. Still does not look like a
"major" winter storm, just a poorly-timed nuisance.
- Seasonably-mild temps through at least Saturday before a
modest cool down (still not overly-cold though):
Although plentiful clouds and/or fog could hold us down a bit
these next few days, highs well into the 40s-50s still likely
through at least Sat and probably Sunday, before more 30s work
their way in for Mon-Tues.
&&
.DISCUSSION...
Issued at 410 PM CST Tue Dec 19 2023
-- PRIMARY CHANGES IN THIS 7-DAY "PACKAGE" VERSUS THE PREVIOUS
(EARLY-AM) ONE (chronological order):
1) Although fog is rarely a "sure thing" (and still isn`t),
concerns have increased for at least a narrow corridor of fog
(perhaps dense?) mainly in our eastern zones (east of Highway
281) late tonight into Wed AM, with MAYBE a more widespread area
of fog (some possibly dense?) taking shape Wed evening-Thursday.
2) Due to the expectation of widespread high clouds and possibly
also at least a narrow corridor of lower clouds and/or
lingering fog, high temps for Wed have trended down a few
degrees (more mid-upper 40s instead of upper 40s-low 50s).
3) Low-end chances (PoPs) for light rain chances have worked
their way back into our southeast zones (mainly southeast of a
Geneva-Plainville KS line) for especially Thursday evening-night
(and later forecasts may have to increase PoPs a bit more for
Thursday daytime as well).
4) In a very-not-surprising development, our high temperature
forecast for Mon (Christmas Day) has trended down a solid 5-7
degrees (now mainly upper 30s-low 40s), and raw model data
clearly supports more room for downward adjustments in later
forecasts.
-- PRIMARY FORECAST CHALLENGES/UNCERTAINTIES (including all
further discussion of longer-term periods Thurs daytime-Tues):
1) Just how much of an issue will fog be these next few nights,
and how far into the daylight hours might it linger (and perhaps
mess up high temps)?
Although many will probably welcome the very light winds these
next few days, they are so light through the lowest levels that
there are some ingredients in place for fog issues these next
few nights (mainly east tonight and perhaps more widespread Wed
night). That being said, it`s not a "perfect recipe" either,
with what should be quite a bit of high-level cloud cover
perhaps acting against widespread fog formation. That being
said, raw visibility progs from higher-res models (including
HRRR), which are sometimes overdone and sometimes right-on-the-
mark, have raised enough concern that possible fog issues have
been introduced to our Hazardous Weather Outlook (HWOGID).
2) The "big holiday system":
- Honestly, there have not been any significant changes of note
with things, as we are still a few days away from gaining any
kind of "higher level" confidence in the finer details, and at
least 2-3 days away from tossing out any kind of preliminary
official snowfall amounts/graphics.
- In the basic big picture: At the very least, the latest
ECMWF/GFS solutions (deterministic) agree on a complex system,
as a pair of distinct disturbances located over both the
southwestern CONUS and northwesterly CONUS (as of Sat AM), are
progged to merge/phase together into one, larger-scale upper
low over the Central United States Sunday-Monday, and then
VERY SLOWLY depart east and/or possibly even stall out over
our region Tues-Wed.
- Focusing on higher-confidence items:
1) This system WILL begin as rain (perhaps even a few weak
embedded thunderstorms?) as it moves in especially Sat night-Sun
AM (this forecaster feels our Sat daytime PoPs, although fairly
low, are still too high, too soon).
2) Any changeover to snow (likely from west to east) would most
likely hold off until Sun night-Mon AM, although the latest
ECMWF does bring in cold air a bit sooner and perhaps try to
change at least western zones over to snow already Sun
afternoon.
3) Quite a bit would have to change for this to turn into a
truly major/crippling kind of winter storm. It`s timing over
the Christmas holiday is obviously poor and could easily produce
nuisance travel issues, but at this point it`s just not
"screaming" big-time issues.
4) Leaning on some of the latest 12Z ECMWF ensemble data:this
still looks like a widespread (and ultimately beneficial)
precipitation event, with an impressive 60-80% chance that most
of our CWA receives at least 0.50" total liquid equivalent, and
at least a 20-30% chance that SOME areas receive at least 1.00".
Snowfall-wise, it is worth noting that the ECMWF ensemble is a
bit more bullish than the latest deterministic run, with
probabilities for at least 1" of snow as high as 40-60% in our
northwest half, and non-zero (20-30%) probs for at least 3" of
snow...again mainly in far northern/western local counties.
Fortunately, the surface low pressure system still does not look
particularly deep/wound up, so (at least for now) wind gusts
look to top out closer to 25-30 MPH than say, a "big-time"
system with 50+ MPH gust potential.
Again, we have a ways to go to pin this thing down, so the above
main points are really all we can key on for now. Stay tuned...
-- SHORTER TERM FORECAST DETAILS FOCUSED SOLELY ON THE NEXT 36
HOURS (through late Wed night/Thurs AM):
- Current/recent weather scene as of 345 PM:
As expected, it`s been a dry and overall-uneventful day, but
with a fair amount of passing high level cirrus (skies currently
mostly sunny north/partly to even mostly cloudy south). As
expected, it was a breezier day in our southeastern CWA
(sustained speeds at least 15-20 MPH/gusts 20-30 MPH) versus
especially our far north/west, where the proximity of a surface
trough axis has kept winds lighter at only around 10 MPH. If
anything, high temps have varied a little more than expected, as
most of our central/northeast appears to only make the mid-upper
40s, while at least low-mid 50s dominate our southern zones and
upper 50s to flirting with 60 extreme west (mainly
Dawson/Gosper/Furnas). In the mid-upper levels, water vapor
imagery depicts broad, quasi-zonal (west-east) flow over our
region, well downstream from a large-scale low still well off
the Pacific Coast.
- This evening/tonight:
Although not a "sure thing", especially higher-res models such
as HRRR (and with some support from SREF visibility probs) have
raised concerns over at least a narrow swath of fog (perhaps
localized dense?) forming mainly post-midnight within mainly
counties east of Highway 281. This would focus along the
interface between a very weak surface boundary separating light
northwesterly breezes behind it from light south-southwesterly
breezes ahead of it. Not nearly enough confidence to issue any
kind of Dense Fog headline at this time, but at least introduced
fog to official forecast and Hazardous Weather Outlook.
Otherwise, for the majority of the CWA (especially west half),
where fog should not be an issue, expect a partly-mostly cloudy
night as another push of high clouds arrives. Lows tonight were
changed little, aimed from mid-upper 20s most areas to around 30
southeast.
- Wed daytime:
The main question mark will be how long any possible fog/low
clouds linger into the daylight hours. Latest HRRR visibility
keeps fog going well into the morning but still keeps it mainly
east of Hwy 281. Even if fog and/or low cloud are not extensive
in our east, the ENTIRE CWA will likely see considerable mid-
high level clouds streaming over. The combo of plentiful high
clouds, possible lingering fog, and light winds (no more than
5-10 MPH) from the north/east (weak mixing) is not a great
recipe for warming up. Based on a blend of various guidance,
have lowered highs roughly 3 degrees from previous, with only
mid-40s central/northeast to upper 40s/low 50s far south/west.
- Wed evening-overnight:
At least for now, have kept any precip out of the forecast, but
latest NAM suggests that some very light rain/drizzle could try
creeping into our far southeast zones post-midnight. The overall
bigger concern is whether a more expansive area of fog (some
dense?) could develop in the favorable very light wind regime.
That being said, a fair mount of mid-high clouds could work
against this. For what it`s worth, the latest HRRR visibility
shows an "explosion" of widespread fog over most of our CWA
overnight, which is concerning, but SREF probs are not as
bullish. Fog is a notoriously fickle thing to pin down beyond
especially 12 hours, so for now have simply introduced generic
"patchy fog" to our forecast CWA-wide, and added a mention to
the HWO. Low temps are generally aimed 2-5 degrees warmer than
tonight most areas, aimed mainly 27-30 western half and 30-35
eastern half (possibly holding up upper 30s in Mitchell County
KS area).
&&
.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 516 PM CST Tue Dec 19 2023
A surface trough will slide across the region overnight,
promoting very light winds across the local area. Could see some
moisture pooling near this trough overnight, with the HRRR
indicating a stripe of fog/dense fog just to the east of GRI.
Given the placement of the axis of this trough and associated
band of dense fog, there remains little chance for significant
impacts from fog to reach KEAR, with minimal impacts possible
near KGRI. Due to the uncertainty in the exact location of the
surface trough overnight, opted to continue with a mention of
MVFR VSBYS late tonight at KGRI, with no mention of fog at KEAR.
Overall...winds will be light through the period with mainly
passing high level cloud cover along with light southerly winds
this evening...becoming light and more out of the northwest
behind the surface trough overnight. Northeast winds less than 8
KTS are expected for Wednesday.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...None.
KS...None.
&&
$$
DISCUSSION...Pfannkuch
AVIATION...Rossi
Area Forecast Discussion
National Weather Service North Platte NE
556 PM CST Tue Dec 19 2023
.KEY MESSAGES...
- Dry conditions and unseasonably warm temperatures in the 50s
continue through the end of the week.
- Confidence continues to increase for widespread precipitation
to impact the area Christmas Eve and Christmas Day. However,
uncertainties with the timing and track of this system remains
which will have significant impacts on temperatures and
precipitation type.
- Those with holiday and post-holiday travel plans across area,
especially those traveling west, should plan accordingly and
monitor future forecasts as hazardous travel conditions may be
possible.
&&
.SYNOPSIS...
Issued at 300 PM CST Tue Dec 19 2023
Recent GOES-16 WV and RAP 500-mb showed a deep trough of low
pressure extending across the Hudson Bay, south across northern
Ontario and Quebec. Further south of this feature, an elongated
upper-level trough extending from Lake Ontario, south into the
Carolinas. Upper-level high pressure was centered over the Gulf of
Mexico with broad ridging extending northwest into the northern
Rockies. A weak upper-level shortwave was traversing along the upper-
level ridge axis bringing increased high-level clouds to overspread
the area. A closed, positively-tilted upper-level low was
situated off the coast of northern California. At the surface,
low pressure was noted over northern Montana with a quasi-
stationary front draped southeast across eastern Montana and
western South Dakota to another surface low situated across the
South Dakota/Nebraska border. Surface troughing extending from
the South Dakota/Nebraska border low was apparent across the
Sandhills, south into southeast Colorado. Northwest winds have
increased some this afternoon with recent wind gust observations
of 15 to 20 miles per hour. The high clouds that have filtered
into the region have resulted in temperatures today trending a
few degrees lower than the previous forecast. At 3 PM CT,
temperatures ranged from 50 degrees at O`Neill to 67 degrees at
Imperial (2 degrees short of the daily record high temperature).
&&
.SHORT TERM /THROUGH WEDNESDAY NIGHT/...
Issued at 300 PM CST Tue Dec 19 2023
Tranquil conditions with well-above normal normal temperatures will
continue through the short term period as weak upper-level ridging
continues.
Overnight low temperatures in the 20s set up across western and
north central Nebraska tonight with increasing clouds as the night
wears on. The aforementioned quasi-stationary front will transition
south into a backdoor cold front as surface high pressure currently
situated over northern Manitoba shifts southeastward into the Great
Lakes region. This frontal boundary will reach northern Nebraska
early Wednesday morning, sweeping across the entire forecast area
throughout the day on Wednesday. As a result of the frontal passage
and increased cloudiness, temperatures will trend a bit cooler as
compared to today across the area, though still remaining 10 to 15
degrees above normal. High temperatures ranging from the 40s across
north central and northeastern Nebraska to the mid 50s across the
southern Panhandle are on tap for the day on Wednesday.
&&
.LONG TERM /THURSDAY THROUGH TUESDAY/...
Issued at 300 PM CST Tue Dec 19 2023
The upper-level pattern for the start of the long term period will
be defined by the closed low inching inland just off the coast of
southern California with weak riding across the eastern third
of the CONUS. At the same time, a potent upper-level trough
across the Gulf of Alaska will begin to advance eastward toward
the coast of British Columbia. These two upper-level systems
will set the stage for the potential of widespread precipitation
impacting the area Christmas Eve and Christmas Day.
On Thursday, an upper-level shortwave ejecting ahead of the southern
California closed low will slide across the Plains, however, limited
moisture and forcing will result in dry conditions persisting. These
dry conditions continue Friday and Saturday with above normal
temperatures in the 50s each day.
Attention quickly turns to the potential for widespread
precipitation slated to begin impacting the area late Christmas Eve
(Sunday) and persist through Christmas Day (Monday). While this
system will bring some much needed precipitation to the region,
uncertainties on details in the atmospheric temperature profile
leads to lowered confidence on predominant precipitation type.
This further leads to details surrounding precipitation amounts
and precise location being unresolved. This year is an El Nino
year which is notorious for split flow systems over our portion
of the Northern Hemisphere. Model solutions tend to have a
difficult time resolving split flow regimes which creates
uncertainty and is exactly what is happening with this specific
system. The deterministic ECMWF, GFS, and Canadian continue to
have run-to-run differences that have significant implications
on potential impacts for holiday festivities and travel across
our area.
There are significant differences with the upper-level pattern,
which can be traced back to the northern stream system and it`s
influence on the long wave (or lack thereof). I will give the models
*some* credit as they are in general agreement on the southern
California upper-level closed low pushing onshore over the
northern Baja Peninsula late Friday, lifting east-northeast
across the southwestern CONUS this weekend. Beyond this feature,
model solutions begin to diverge on the evolution of the
northern stream disturbance which is where confidence begins to
wane. When looking at the individual 12Z deterministic runs this
morning from the GFS and ECMWF... the GFS phases the northern
and southern stream systems together across the central Rockies
early Sunday, becoming negatively tilted. On the flip side, the
ECMWF doesn`t have these system phase together until Monday,
becoming positively tilted in the process.
It appears this system will be a rather wet one, which is
highlighted by the Extreme Forecast Index (EFI) which has begun
to show a strong signal of anomalous QPF amounts across western
and north central Nebraska such that the SoT (Shift of Tails) is
greater than 0. Though the greatest winter impacts appear to be
west of the forecast area right now, rain will be cause for
concern for travelers as there will be refreeze potential
overnight Sunday and Monday as colder air with this system
filters in. Current thinking for timing is that this will be a
rather prolonged event with precipitation arriving across
southwest Nebraska Saturday afternoon/evening, pushing northward
Saturday night, persisting through Christmas Day. There are
some implications that precipitation may even linger into the
day on Tuesday. It is too soon to say one way or another on
exact timing of change over from rain to snow or rain/snow mix.
However, the Panhandle and northwestern Sandhills has increased
probabilities of seeing snow with recent NBM Probabilities
indicating 20-30% chance of 4+ inches of snow.
Make sure to stay tuned for future details regarding this
system as holiday travel impacts will be possible.
&&
.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 554 PM CST Tue Dec 19 2023
VFR conditions are expected through the forecast period. Winds
will become light and variable later Tuesday evening and
continue much of the remainder of the period before shifting to
prevailing southeasterlies.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Viken
SHORT TERM...Viken
LONG TERM...Viken
AVIATION...NMJ