Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/27/22
Area Forecast Discussion
National Weather Service Denver/Boulder CO
859 PM MST Wed Jan 26 2022
.UPDATE...
Issued at 858 PM MST Wed Jan 26 2022
Not the easiest forecast regarding snowfall and impacts for
tomorrow. The short wave is dropping southward across Montana this
evening, but also shearing to the southwest. We will have a decent
batch of weak to moderate QG ascent coming toward us, and most of
it should pass nearly overhead. Looking toward frontogenesis,
there`s nothing terribly well defined yet, although there is
definite mid level mass convergence over us by Thursday morning.
Just those two factors alone should give us a nice mid level cloud
deck which should start to precipitate, but very lightly, late
tonight across the plains. Looks like most of this would be just
east of I-25 in the wee morning hours. Then, winds begin to turn
into the Front Range, and even moreso behind the cold frontal
passage expected around 7-8 am.
Snow is expected to fill in rather quickly across the Front Range
I-25 Corridor and Foothills behind this frontal surge, thanks to
the stronger upslope component and continued forcing. Lapse rates
turn neutral, so the response should be pretty decent. We have
increased the snow amounts just slightly, but they`re still shy of
Winter Weather Advisory, with generally 1-4" amounts across the
I-25 Corridor (heaviest south Denver Metro and near the
foothills). Those types of amounts and sufficiently cold road
temps would yield an Advisory if we were certain the snow would
start during the rush hour, but there`s still considerable
uncertainty here as to the exact timing. We`ll message the
potential accordingly, and the second half of the commute could
still get slow and hazardous. The NAMNEST was especially
concerning (heavier and faster), and the EC also seemed a little
faster with snow development. However, the trough is shearing and
that`s what gives us pause as to exactly how fast the front and
stronger upslope arrive. HRRR and RAP appear to be slowest, but
they sometimes have a slight late bias.
Other factors like dendritic growth look decent, a little deeper
through the best vertical motion zone than Tuesday. However, moisture
is less with PW closer to 0.2-0.25 inch, versus 0.30 inch
Tuesday.
&&
.SHORT TERM...(This evening through Thursday)
Issued at 129 PM MST Wed Jan 26 2022
Very similar scenario through tomorrow as what we had on Tuesday,
with northwest flow over the forecast area and a shortwave trough
dropping down into the Four Corners area by mid day Thursday. At
the surface, southerly drainage flow along the front range tonight
will turn back northerly after sunrise Thursday as a cold front
moves through the area. On the northeast plains northwesterly
surface winds overnight will carry through the morning. This
system will be a few hours later to evolve, with snow beginning
around 6 am along the Wyoming border on the plains, and spread
southward later that morning. Differences are slower timing, and
lower potential for snow on the plains.
QG fields show best ascent closer to the forecast area than with
Tuesday`s trough, with center of max upward motion traversing the
western portion Jackson/Grand/Summit/Park counties. In addition to
the mid tropospheric ascent, in the lower levels frontogenesis
associated with the cold front will provide upward motion below
600 mb. Best upward motion is in the mid levels associated with
the upper trough, with the low level frontogenetical forcing a
little weaker.
The favored dendritic growth zone of -12 to -18C aligns with the
higher RH, however overall moisture content in the atmosphere this
time around is lower than previous. Precipitable forecast
precipitable water Thursday is near 0.2 inch, compared with near
0.3 inch on Tuesday. Additionally, low levels of the atmosphere
start out quite dry, and so several hours of alignment of ascent,
RH, and -12-18c layer will be spent moistening the boundary layer
to overcome evaporation/sublimation of the falling snow. Period of
heaviest snowfall, roughly 1/2 inch per hour rates, 8 to 11 am on
the northern plains, 10 am to 1 pm in the Denver metro, and mid
day to early afternoon south along the Palmer divide.
Forecast snowfall about 1/2 what we had Tuesday, with lower
precipitable water yielding lower QPF and snow. 1-3 inches across
the metro and I-25 south corridor, and 2-5 inches in the foothills
where mid-level upslope flow will help give a boost to snow
production. Given the light snowfall amounts and timing later in
the morning outside the morning commute, will hold off on any
headlines.
In the mountains, chances for snow pick up overnight with the
approaching upper low, and the higher elevations and passes
gaining a couple inches.
Temperatures...warmer tonight than last night as wind increases
ahead of next approaching system to mix out the boundary layer and
reduce radiational cooling. Colder daytime temperatures Thursday
behind the front, near freezing along the I-25 corridor to upper
30s northeast plains, and teens to near 20 in the mountains.
.LONG TERM...(Thursday night through Wednesday)
Issued at 129 PM MST Wed Jan 26 2022
Latest storm system exiting Colorado Thursday night with clearing
skies and cold temperatures. For Friday through much of the weekend,
a high amplitude ridge of high pressure builds in across much of
the west with a dry and warming trend. Temperatures will rise into
the 40s on Friday, then a period of 50s for the weekend across
the plains. 700mb temperatures will range from 0C-2C over the
weekend which would support these warming temperatures. There is
a weak upper low that moves across New Mexico on Sunday but this
placement is too far south for any impacts for Northern Colorado.
The next storm system to impact Colorado will be next Tuesday through
early Wednesday time frame with colder temperatures and a chance of
snow. Long range models trends line up a little better today as
both the GFS/European solutions deepens the low into Utah on
Tuesday before the GFS continues to deepen it into Arizona on
Wednesday while European solution keeps the low a bit further
north. Will maintain colder temperatures and increase snow chances
a bit higher with today`s forecast but certainly solutions will
see more changes before the event.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 459 PM MST Wed Jan 26 2022
Main concern will be development of lower ceilings and snow. Cloud
decks will gradually lower overnight, but be of insignificance
until closer 09Z-13Z when ceilings are expected to drop to around
5000-6000 feet with virga and a low chance of a light flurry
developing. Cold front is expected to push through around 15Z with
snow and IFR ceilings and visibility developing shortly
thereafter. Main snow period is expected 16Z-20Z, with a brief
period of moderate snow and VLIFR conditions in that window.
Winds expected to gust to 15-20 knots from the north/northeast
with the front, and then weaken through late afternoon. Conditions
should gradually improve 20Z-22Z with snow moving out of the area
and flight conditions improving to MVFR.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...Barjenbruch
SHORT TERM...Hanson
LONG TERM...Entrekin
AVIATION...Barjenbruch
Area Forecast Discussion
National Weather Service Grand Forks ND
1001 PM CST Wed Jan 26 2022
.UPDATE...
Issued at 1001 PM CST Wed Jan 26 2022
Getting some reports of freezing drizzle in the Fargo area, so
adjusted weather grids to include a mention. Winds have been less
impressive than expected, with most of the restrictions of
visibility with the falling snow in heavier snow showers. However,
given the freezing drizzle and the likelihood of more blowing
snow later tonight as the reinforcing cold front drops down, will
leave headlines as they are for now. Strong cold air advection
bringing colder temperatures, as well as the valley component to
the winds should again bring some blowing snow into the Thursday
morning commute.
UPDATE Issued at 651 PM CST Wed Jan 26 2022
Adjusted POPs for snow showers continuing to move their way down
the Red River Valley as the first cold front pushes down. Expanded
POPs and broadbrushed them a bit more as there seems to be more
snow activity further west and south than originally thought.
Blowing snow decreases quickly as the falling snow ends thanks to
fairly warm temps, but the main push of arctic air is still to
come, so think vis will go back down later tonight into tomorrow
morning. At this point will keep headlines going, emphasizing a
lull in bad conditions this evening after the first front and
before the second.
&&
.SHORT TERM...(This evening through Thursday night)
Issued at 300 PM CST Wed Jan 26 2022
The main forecast emphasis is on the near blizzard potential from
gusty northwest to north winds and convective streamers (even snow
squalls?) tonight into Thursday morning. Have issued a Winter
Weather Advisory to cover these impacts, and will be monitoring
through the night to see whether any additional updates are
needed.
As of 2 pm this afternoon, the warm front was pushing through
portions of the Red River Valley. Grand Forks had warmed to 32
degrees, Langdon 30 degrees, and Jamestown 36 degrees, with the
westerly wind push. This warm spell will be very short lived, as
the next cold front is already poised along the Canadian border.
This cold front will sweep southward into the northern FA by early
evening. Wind speeds at Brandon and Winnipeg Manitoba were in the
33 to 37 knot range, with some blowing snow. Upstream Canadian
radars were showing a steady band of snow just north of the
International border. As this drops into the FA late this
afternoon and evening (combined with the gusty northwest winds),
near blizzard conditions are possible, especially in open country
along and west of the Red River Valley. Other regional radars and
satellite imagery were showing convective streamer clouds forming
over north central North Dakota. This shows the potential for snow
squalls as well, where visibilities can drop to zero over short
distances. Last Friday was a somewhat similar set up, and
Interstate 29 was closed from Grand Forks to the Canadian border.
Since temperatures are quite warm initially, without falling snow,
it will be hard to get really low visibilities. However, as
mentioned above, there is some upstream falling snow. Moving a
little later into tonight, a secondary cold front is expected to
drop from the northern toward southern Red River Valley. This will
bring a surge of 925mb cold advection, good pressure rises, and
straight north winds. Since temperatures will be much colder by
then, snow becomes easier to loft. The RAP show 925mb wind speeds
at least 35 knots well into tonight and Thursday morning.
Therefore, think lofted snow will combine with these winds to keep
areas of low visibility throughout this time frame. Will use noon
Thursday as an end time for now, later shifts can adjust as need
be.
.LONG TERM...(Friday through Wednesday)
Issued at 300 PM CST Wed Jan 26 2022
A short period of quieter weather settles into the northern plains
over the weekend, with the possibility of more snow heading into the
start of next week. Synoptically, we will be under the influence of
a ridge starting early next week, where our flow will turn westerly
and temperatures will warm. After that period, more NW flow sets up
and we return back to colder temperatures.
Ending the week, we will see warming temperatures for a few days,
thanks to southerly flow ahead of our next system. Saturday will see
highs in the mid to upper 20s, and partly cloudy skies. Saturday
afternoon into evening, our winds will shift to be out of the west
and eventually the south for Sunday. This will allow warmer air to
move into the area, making Monday an unseasonably "warm" day with
temperatures hovering around freezing.
There is the possibility in the ensembles for another system to move
through as we transition back into NW flow towards the middle of
next week, however, guidance remains murky. Confidence is low on
timing, track, amounts, and effects we could see, but we will keep
an eye on it as it gets closer temporally. Temperatures are expected
to sink right back down mid-week, with Wednesday calling for single
digit highs above and below zero right now. We could see some wind
chill concerns heading into mid-week as well, so we will continue to
monitor this as well. Enjoy the quieter weather while you can!
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 543 PM CST Wed Jan 26 2022
Band of snow showers moving into KGFK have brought vis down to
1/2SM, but should be pretty short lived, maybe gone even before
00Z. The snow showers as well as blowing snow will periodically
reduce vis through this evening, but will be mostly in the 1 to 5
mile range. Will watch for some lower vis as the secondary cold
front comes down later tonight into tomorrow morning, but not
confident enough to include very low vis with blowing snow at this
point. Ceilings will be bouncing between MVFR and VFR for the most
part. Some improvement by the end of the period as winds and
clouds decrease by Thursday afternoon.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...Winter Weather Advisory until noon CST Thursday for NDZ006>008-
014>016-024-026>030-038-039-054.
Winter Weather Advisory until noon CST Thursday for NDZ053.
MN...Winter Weather Advisory until noon CST Thursday for MNZ001>005-
007-008-013>015.
Winter Weather Advisory until noon CST Thursday for MNZ029.
$$
UPDATE...JR
SHORT TERM...Godon
LONG TERM...AK
AVIATION...JR
AREA FORECAST DISCUSSION...UPDATED
National Weather Service Morristown TN
919 PM EST Wed Jan 26 2022
.UPDATE...
EVENING UPDATE.
&&
.DISCUSSION...
No significant changes for the evening update. Temperatures are
perhaps a touch warmer than forecast, which is honestly a little
perplexing given the calm winds, clear skies, and very dry air in
place. The last several runs of the RAP and HRRR have trended
warmer with temperatures tonight. Given hourly temperatures
running warmer than previously expected, it seems hard to ignore
this trend in rapidly updating CAM guidance so adjusted overnight
lows upward just a touch. Still expect to see lows in the teens in
southwest Virginia, along with portions of the northern plateau
and in the TN valley near the VA border. Otherwise, no changes
made to the forecast.
CD
&&
.AVIATION...
00Z TAF DISCUSSION.
VFR conditions will prevail through the period, with only some
high clouds passing through at times. High pressure shifts east of
the Appalachians tonight so expect light NELY winds tonight to
veer around to light SWLY by midday or so tomorrow.
CD
&&
.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN 25 52 35 43 19 / 0 0 0 20 0
Knoxville McGhee Tyson Airport, TN 21 48 32 40 15 / 0 0 0 50 20
Oak Ridge, TN 21 47 32 40 15 / 0 0 0 40 10
Tri Cities Airport, TN 17 45 29 38 14 / 0 0 0 70 50
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...NONE.
VA...NONE.
&&
$$
Area Forecast Discussion
National Weather Service Norman OK
455 PM CST Wed Jan 26 2022
...New AVIATION...
.SHORT TERM...
(This evening through Thursday)
Issued at 1219 PM CST Wed Jan 26 2022
The short term issue will be snow precipitation today during the
afternoon through the evening hours. Energy from a shortwave trough
over the Southern Rockies had been producing bands of snow this
morning east of the troughs axis across the Texas Panhandle with
some heavy amounts. Expecting the upper wave to continue digging
across the Southern High Plains this afternoon with the snow moving
into western and southwestern Oklahoma and western north Texas.
Latest radar mosaic showing the first round of up to moderate
intensity snow off the high plains starting to move into
southwestern Oklahoma. Latest model runs have been increasing the
total snow accumulations, with the HRRR & GFS a little more
representative. Could expect to see accumulations from 1.5 up to 3.0
inches in our current advisory area of westcentral and southwest
Oklahoma and portions of western north Texas. Travel along I-40
between Oklahoma City and the Texas Panhandle may be hampered by the
snow and its reduced visibilities. Expecting this area of snow to
begin moving into central Oklahoma toward early evening hours with
lighter accumulations up to a half an inch. By late evening, most
of our area should lie west of the trough axis with the mid-level
ascent weakening and the snow concluding.
Although will keep it out of the grids for now, forecast soundings
suggesting dense fog possible early Thursday across portions of
western Oklahoma. Did go slightly cooler than NBM with the CONSRAW
Thursday afternoons MaxT due to a likely snowpack, especially across
our west.
&&
.LONG TERM...
(Thursday night through next Tuesday)
Issued at 254 PM CST Wed Jan 26 2022
Friday morning our area will be on the back side of a cold front as
a dry upper trough moves through. However, will see the cold air
quickly retreating back to the north as the Southern Plains will be
on the eastern periphery of an upper ridge building across the
western U.S. With ridging, we should see a warming trend through
early next week with above seasonably average daytime temperatures.
Models are consistent with a shortwave trough out in the Pacific
coming ashore across the western U.S. and breaking down the ridge,
eventually reaching the Southern Plains by Monday. Both GFS and
ECMWF bring the upper low across northern Texas, although a slightly
more northerly track taking it across Oklahoma using the Canadian NH
model solution. With a return of south winds on Monday and
increasing low-level flow and gulf moisture transport, cannot rule
out POPs for rain across southeast Oklahoma during the afternoon.
However will keep the rain POPs very low with better chances more
east of our forecast area. It will be more windy on Tuesday as the
surface isobars tighten and south winds increase. As a result, had
to populate the afternoon wind grids using a more robust NBM 90th
percentile.
The bigger weather show may be more toward the middle of next week,
generally late Tuesday into Wednesday as another but more deeper
amplitude wave sets up across the western U.S. Weak shortwaves
propagating through the trough may initiate rain Tuesday afternoon
across eastcentral & southeast portions of Oklahoma, with POPs
increasing further westward across our area as our next really
strong cold front starts to push through. However, the models this
far out are in disagreement temporally with the ECMWF & Canadian
models pushing it through early Tuesday, yet much later with the GFS.
The 1000-850 thickness fields are showing frigid Canadian based air
behind this mid-week frontal boundary. Either way, could see a
wintery mix of precipitation by Tuesday evening and overnight into
Wednesday.
&&
.AVIATION...
(00Z TAFS)
Issued at 450 PM CST Wed Jan 26 2022
Band of snow will move east across many of the TAF sites over the
next 2 to 3 hours before shifting east. With the snow will come
mainly MVFR ceilings and visibility but could see a brief period
of IFR. Otherwise, expect to see a return of VFR conditions
overnight with light south/southwest winds. There is a chance for
some fog toward morning across parts of western into northern
Oklahoma. Mainly some high clouds during the day Thursday with a
weak surface boundary working south across the area which will
shift the winds to the north during the latter part of the
forecast.
&&
.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK 24 44 24 48 / 40 0 0 0
Hobart OK 18 45 21 51 / 60 0 0 0
Wichita Falls TX 27 49 26 52 / 70 0 0 0
Gage OK 16 44 18 54 / 0 0 0 0
Ponca City OK 22 45 20 49 / 40 0 0 0
Durant OK 32 51 29 52 / 30 0 0 0
&&
.OUN WATCHES/WARNINGS/ADVISORIES...
OK...Winter Weather Advisory until midnight CST tonight for
OKZ014>018-021>024-027-033>039-044.
TX...Winter Weather Advisory until midnight CST tonight for
TXZ083>086.
&&
$$
SHORT TERM...68
LONG TERM....68
AVIATION...30
Area Forecast Discussion
National Weather Service Paducah KY
909 PM CST Wed Jan 26 2022
.UPDATE...
Issued at 908 PM CST Wed Jan 26 2022
Some minor first (period) tweaks to reflect some
temperature/dewpoint/wind adjustments with observations. Having
the the WFO PAH forecast area being split by the high pressure
axis from southwest to northeast at the surface makes
temperature/dewpoint/wind forecasts tricky. Subtle micro-scale and
topographical variability this evening will make hourly
temperature adjustments a nightmare, until the mid-deck of cloud
cover filters across the area overnight. Most of the moisture
still appears to be confined in the 295-300 Kelvin Isentropic
layer (with the leading edge 8-10kft agl) with sharp delineation
between clear and overcast skies.
Another issue is how much of the precipitation will actually reach
the surface and provide any observable/impactful issue between
midnight tonight and noon, especially across the northern third of
the WFO PAH forecast area.
Precipitation schemes from NSSL-WRFARW-4km, NAM 4km NAMest, High
Resolution FV3 favor a more robust saturation/precipitation
loading of the mid-cloud layer. Although reasonable, the
precipitation loading from the aforementioned models may be
somewhat overdone compared to observations. From surface and
radar observations in Oklahoma early this evening, combined with
differential water vapor imagery, suggest that significant forcing
is need to generate sufficient snow production aloft to overcome
drying further down the atmospheric column. Little in the way of
significant wet-bulb adjustments are taking place except under the
area of maximum lift.
With this in mind, leaned closer to the Canadian, HRRR, RAP
guidance for PoPs/QPF through 12z Thursday (6 am CST Thursday).
All were similar in increasing any measurable snowfall footprint
(albeit low, less than a tenth of an inch between the Perry MO/IL
county areas after 3am Thursday). Between 2 am and 9 am Thursday appears
to be about the best window for focused deformation and lift over
the northern third of the WFO PAH for any noticeable snow
production.
At this point, the current forecast trends for snow
flurries/isolated pockets of measurable snowfall look on target
early Thursday. This should not create any hazardous weather
impact for the WFO PAH forecast area overnight or early Thursday.
&&
.SHORT TERM...(Tonight through Friday night)
Issued at 103 PM CST Wed Jan 26 2022
High pressure over the area continued to result in mostly clear
skies and cold conditions today. A shortwave over New Mexico is
forecast to move toward the area tonight and weaken as it
encounters decent confluence. This weakening and lack of overall
moisture (most of which is aoa 700mb) means we will go with just a
small chance of flurries, or slight chance PoPs for light snow from
SEMO into southern IL and southwest IN late tonight into midday
Thursday. Held on to some flurries over the KY Pennyrile region
Thursday night for continuity. High temperatures will be 10 to 15
degrees higher Thursday vs. today.
A longer wave trof will move across the area Friday. There could
be a fair amount of clouds east of the MS River, and possibly
flurries from SW IN into the KY Pennyrile region. Something to
monitor for now. Otherwise another cold day, with mostly clear and
cold conditions on tap for Friday night.
.LONG TERM...(Saturday through Wednesday)
Issued at 103 PM CST Wed Jan 26 2022
Saturday through Monday should be dry with milder temperatures.
Other than a fropa without fanfare Sunday, return southerly flow
and rising heights will promote the escape from the colder than
average temperatures.
The pattern becomes unsettled Tuesday through Wednesday. A trof is
forecast to dig from the Pacific NW across the Four Corners,
eventually ending up over the Plains by late Wednesday night. As
is typically the case, the EC/CMC solutions are in respectable
agreement with the GFS again an outlier. It develops a second
lower out west, ejecting energy from the main trof toward the
Great Lakes and much faster with the overall movement. Will
discount the latest GFS and keep with NBM and the consensus model
output including their ensemble mean solutions. Rain chances ramp
up Tuesday and continue through Wednesday night. At this time,
the Wed-Wed night time frame seems to be the focus. The pattern
has that locally heavy rain possible look. Temperatures will be
on the mild side through the period, for this time of year.
&&
.AVIATION...
Issued at 533 PM CST Wed Jan 26 2022
With the WFO PAH 00z Thursday WFO PAH TAF issuance, ceilings
should remain VFR for the entire forecast period, as well as the
surface visibilities.
Kept the mention of vicinity (VC) showers (in this case, snow
showers) during the period of highest probability of precipitation
in each of the TAF locations. The majority of the precipitation
will likely come out of 8-10kft AGL altostratus/cumulus deck
arcing its way from the the western Gulf of Mexico through Texas,
Oklahoma, Arkansas, and Missouri tonight into tomorrow.
Condensation pressure deficits of 10-20 mb from the NAM-WRF FV3
High resolution guidance correspond well with the timing and
location of the best precipitation chances.
There may be some lowering of the cloud layer to lower VFR
categories (4-8kft agl) near 12z- 15z Thursday, until warm air
advection aloft takes effect.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...None.
MO...None.
IN...None.
KY...None.
&&
$$
UPDATE...Smith
AVIATION...Smith