Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/28/22
See below for an aviation forecast discussion for the 00Z TAFs.
&&
.SHORT TERM...(This Evening through Wednesday Night)
Issued at 224 PM CST Tue Dec 27 2022
Overall, fairly quiet tonight and Wednesday before a system skirts
part of the CWA Thursday, bringing a chance of precipitation. The
warmer temps today have been welcoming after the frigid conditons we
have been experiencing for the past week. The main challenge in the
short term will be how low the temps drop tonight and how warm the
temps get on Wednesday due to cloud cover expected and snow covered
ground.
During the morning hours, we saw temperatures rise in the western
part of the state as a warm front passed through the area. However,
in the James River Valley area, it does not look like we will reach
our high of 32 at ABR so I did lower them as the snow depth/cloud
cover have played a part in keeping the temps a little cooler than
what NBM suggested. The warm front continues to push east across the
CWA, ushering in the warm air advection behind it. We have
downsloping winds continuing on the eastern slopes of the Sisseton
Hills and the Coteau with an SPS issued until 6PM, due to blowing
snow reports in this area. The downsloping winds should diminish
through the evening into tonight. I used the ECAM for winds and
gusts in this area to show for this. RAP/GEFS at 500mb indicates a
ridging pattern over much of the Northern Plains becoming more
flattened as it pushes east, giving us more of a zonal pattern by
this evening. Winds will turn more southwesterly through the
overnight as an upper level trough is positioned out west. This
trough will move east through the midweek, but overall flow will
remain southwesterly. 700mb indicates a shortwave pushing in from
the west this evening through the overnight with a low skirting
across Canada/MT bringing the increase in clouds. This low will
continue to push east
HREF/RAP/ECMWF Ensemble keeps the area dry with this system tonight
through Wednesday. NBM/RAP at ABR does indicate the possibility of
patchy fog (with the Rap sounding showing this as well at the
surface) so added that into the forecast, something to watch for
during the overnight. Our attention then turns to a 1003mb low that
will push across the central parts of the midwest starting early
Thursday. The latest ECMWF/GEFS ensembles keep the precip chances
mostly in our eastern/southeastern coverage area, which is
positioned in the northern/northwest side of the low. We could start
seeing mixed precip/snow chances (15-20%)in this area early in the
morning (between midnight-6 AM) on Thursday, however, the ECMWF
sounding at Watertown indicates a dry layer between 900-700mb during
this time with saturation near the surface (as possible freezing
drizzle/rain). The sounding clearly indicates a warm nose between
900-800mb with temps in the warm nose around +8C and the surface
temps hovering around 0C early Thursday. The entire column does
becomes saturated through the day and becomes colder. I left in a
slight chance of pops given by NBM during this time frame.
925 temperatures at 12Z Wednesday will hover around 0-2C with
surface winds out of the west/southwest. I did decrease our temps a
few degrees for tonight due to the impact of the snow. Lows are
forecasted to be in the 20s-30s. Highs for Wednesday should be fairly
similar (Again, I lowered the highs a few degrees from the NBM).
Winds will be out of the west/northwest, however, cloud cover still
expected. Highs should range in the 30s to the lower 40s with
warmest in south central SD.
.LONG TERM...(Thursday through Tuesday)
Issued at 224 PM CST Tue Dec 27 2022
Latest round of deterministic/ensemble data concerning Thursday`s
system has pushed things further east and weaker compared to 24
hours ago. In fact, there are a number of ensemble members that show
barely any precip with this system. That said, the ensemble mean
approach would still bring light QPF/snow amounts to the southeast
CWA Thursday into Thursday evening, with perhaps some mixed precip
issues.
Focus then shifts to the potential storm system early next week.
GEFS/EC/CMC ensemble probs for 24-hour snowfall 3"+ at 12Z Tues
shows fairly high (50%-70%) chances across the area, although the EC
is displaced further south. Still some evidence of mixed precip
potential as well closer to wherever the warmer air sets up in our
region.
As for temperatures, it doesn`t appear we`re in line for any arctic-
type air intrusions anytime soon, with ensemble data supporting
continued high temps in the 20s and 30s mostly throughout the
period.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday Evening)
Issued at 516 PM CST Tue Dec 27 2022
Terminals KABR,KATY,KPIR,KMBG
VFR/Mostly cloudy (high cirrus) skies should persist well into
tonight, before potentially clearing off Wednesday. Short term
guidance continues indicate a chance for either some fog or low
stratus development overnight/early Wednesday morning in/around
KABR as winds go light. Additional sub-VFR cigs/visbies will be
possible in/around KATY by Wednesday afternoon. KPIR/KMBG will
remain VFR through forecast period, although some low level wind
shear potential will exist at KPIR for a few hours into this
evening.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
&&
$$
UPDATE...Dorn
SHORT TERM...MMM
LONG TERM...TMT
AVIATION...Dorn
Area Forecast Discussion
National Weather Service Corpus Christi TX
905 PM CST Tue Dec 27 2022
...New UPDATE...
.UPDATE...
Issued at 826 PM CST Tue Dec 27 2022
Boundary layer moisture is beginning to increase along the coast
as a trough develops in the lee of the Rockies. Temperatures have
fallen pretty quickly under ideal radiational cooling conditions with
light southeast winds and clear skies. Lowered temps a few
degrees for tonight as temperatures have already fallen below
forecast lows at a number of locations.
Next forecast challenge for tonight is the extent and density of
fog. Surface winds have decoupled from the low level flow and
dwpts are rising and expected to result in 100% RHs overnight.
This will likely result in patchy to areas of fog formation. SREF
probabilities indicate >40% probability of visibilities below 1
mile developing late tonight across much of the brush country and
coastal plains. NBM probs are near 30%. Thus cannot rule out
patchy dense fog overnight, but it should not become widespread or
prevailing. Will continue to monitor.
&&
.SHORT TERM...
(Tonight through Wednesday night)
Issued at 209 PM CST Tue Dec 27 2022
Key Messages:
- Warming trend continues
- Fog begins to return late tonight
A pleasant day is unfolding as high pressure passes by the region.
Temperatures have warmed into the low to mid 60s so far today under
mostly sunny skies. Winds will gradually shift around to the
southeast this evening as surface high pressure moves towards the SE
CONUS. The return of low level moisture will lead to a foggy night
across the region as winds become light overnight. Maintained the
mention of patchy fog only at this point as guidance continues to
indicate the development of a 25-30 knot LLJ which may help to fight
off any dense fog development.
A warmer day is expected tomorrow with temps topping out in the mid
to upper 70s for most of the region. Onshore flow will strengthen
through the day as low pressure deepens over the Plains. As a
result, warm and moist air will begin to flow over the cooler shelf
waters. This will likely lead to the start of a prolonged period of
sea fog through the remainder of the work week. Currently expect sea
fog to develop during the late afternoon hours Wednesday with
radiational fog develop inland as we head into Thursday morning. In
addition to the fog, it`s possible we see a few showers over the
Gulf waters Thursday morning as deeper moisture becomes embedded in
the LLJ
&&
.LONG TERM...
(Thursday through next Monday)
Issued at 209 PM CST Tue Dec 27 2022
Key Messages:
- Warming trend with fog through Thursday
- Shower and thunderstorm chances (20-40%) Thursday ahead of and
along a weak dry front
- Cold front early next week with isolated to scattered showers and
thunderstorms
Thursday a mid-level trough and attendant frontal boundary will
approach South Texas. This dry boundary still may result in a few
showers and thunderstorms, mainly east where more moisture aloft
combine with upper level dynamics and isentropic lift.
Our next front comes in early next week as another trough digs in
from the Desert Southwest. Currently, dynamics look more conducive
for thunder with higher CAPE values > 1,000 J/kg and minimal CIN
according to the GEFS Plumes. Again any storms that develop will
favor eastern portions of the CWA and the Gulf waters.
Onshore flow should increase low level moisture sufficiently for
radiation fog with light winds and dewpoint depressions around three
degrees or less Thursday morning, possibly late Thursday night and
again Sunday morning. Have also included sea fog along the coastal
waters for the same time period as warm surface temperatures and
dewpoints in the 60s override cooler sea surface temperatures. Fog
looks less likely after the front Friday and Saturday as dewpoint
depressions spread further apart making it more difficult for the
waters to cool the air above it down to the dewpoint temperature.
Temperatures during the daytime will range in the mid to upper 70s
along the coast and up to the mid 80s around the Coastal Plains and
Brush Country. After FROPA, things will cool slightly by about 5-10
degrees. Overnight lows will generally range in the 50s except
Sunday with mid 60s across much of the region.
&&
.AVIATION...
(00Z TAFS)
Issued at 531 PM CST Tue Dec 27 2022
Skies will be mostly clear through midnight with light southeast
winds. This will bring higher surface moisture back into the
region and set up for a fog event overnight. There is considerable
uncertainty on how low visibilities may get with the GFS showing
little to no fog and the NAM12 and HRRR showing a potential for
dense fog. For now have included visibilities in IFR range across
inland terminals. But will reassess as 00z models come in for the
06z TAFs. Fog should dissipate by mid Wednesday morning with
increasing southerly winds gusting to 20 knots across the coastal
plains with VFR ceilings east and mostly clear skies out west.
&&
.MARINE...
Issued at 209 PM CST Tue Dec 27 2022
A moderate to occasionally onshore flow will return tonight across
the Middle Texas coast. Winds will increase through the day tomorrow
with Small Craft Advisory conditions possible tomorrow night. Sea
fog will return tonight with another round of sea fog expected
Wednesday night into Thursday morning. Small Craft Advisory
conditions continue Thursday in response to moderate to strong
onshore flow. Then, moderate flow will switch around to the
northeast after a frontal boundary moves offshore Friday morning
and becomes weak. Saturday, moderate flow will become variable
before returning to onshore in the evening. Sufficient low level
moisture combined with the frontal boundary will result in
isolated showers and thunderstorms through early Saturday. Warm
humid air overriding cooler waters may result in sea fog Thursday
morning but should lift by the afternoon.
&&
.PRELIMINARY POINT TEMPS/POPS...
Corpus Christi 44 76 64 77 / 0 0 10 10
Victoria 41 75 63 76 / 0 0 10 40
Laredo 48 73 55 74 / 0 0 10 0
Alice 43 78 61 79 / 0 0 10 0
Rockport 50 70 63 73 / 0 0 20 30
Cotulla 44 76 54 73 / 0 0 0 0
Kingsville 46 78 63 79 / 0 0 10 0
Navy Corpus 53 71 65 72 / 0 0 10 20
&&
.CRP WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...None.
&&
$$
SHORT TERM...JM/75
LONG TERM....BF/80
AVIATION...JM
Area Forecast Discussion
National Weather Service Goodland KS
155 PM MST Tue Dec 27 2022
.SHORT TERM...(This evening through Friday)
Issued at 145 PM MST Tue Dec 27 2022
Tonight...broken to overcast high cloud cover will move across
the area tonight ahead of an approaching upper level trough. South
to southwest winds of 5 to 15 mph this evening will veer to the
northwest at 5 to 10 mph after midnight. Low temperatures are
expected to range from the middle 20s to around 30 in the
Republican river valley as well as the McCook, Norton and Hill
City areas to the lower 30s elsewhere.
Wednesday-Wednesday night...high cloud cover will remain over most
of the area during the day. An area of more favorable moisture (850-
500mb) for precipitation moves into parts of far eastern Colorado
from the northwest late in the afternoon. With a 120kt jet moving
overhead and some lift lower down current forecast of slight chance
and low chance pops look good. High temperatures are forecast to
range from the upper 40s in Yuma to around 60 from Hill City to
Leoti.
For the overnight hours, the upper trough axis reaches the
Continental Divide. The area of favorable moisture in the 850-500mb
layer splits up after about midnight with one batch of moisture
moving east of the area and another hugging the Palmer Divide and
points south (per GFS) with drier air aloft moving in. The NAM shows
a similar scenario with much less moisture while the ECMWF shows
much more moisture and widespread precip from McCook to Burlington
and Cheyenne Wells west. The current QPF forecast after midnight
mimics the ECMWF and lesser extent HRRR solutions. Given the dry air
even at the boundary layer from the GFS and NAM solutions I`m not
sure how we`ll get any freezing precipitation. Low temperatures are
generally going to be in the 20s. Currently, we`re advertising
snowfall amounts of a trace to inch or so from Trenton to Cheyenne
Wells west.
Thursday-Thursday night...broad upper level troughing is over the
area with high pressure over the eastern US and southwest US.
Current pop forecast mimics the more moist ECMWF with the
precipitation chances decreasing from southwest to northeast during
the day and dry conditions overnight. The NAM and GFS solutions are
much drier with much less QPF during the day. Any additional
snowfall appears to be 1/2 inch or less. High temperatures are
forecast to be in the upper 30s to upper 40s. Low temperatures
drop into the lower teens to lower 20s.
Friday...an upper level trough axis extends from the northern plains
south through the Tri-State area into west Texas. Dry conditions are
expected with high temperatures in the lower 40s to lower 50s.
.LONG TERM...(Friday night through Tuesday)
Issued at 1223 PM MST Tue Dec 27 2022
Above-normal temperatures continue through the first half of the
long term period. A larger trough moving into the area Sunday night
into Monday will drop temperatures for the start of the work week
and bring a chance for wintry precipitation. Extent and amount of
precipitation remains uncertain at present; however, there are some
indications portions of the area could see significant snowfall - as
such, will need to continue to closely monitor.
At the start of the long term period 00Z Saturday, an upper-level
shortwave trough axis is moving into the Tri-State Area with a
surface low over northeastern New Mexico/southeastern Colorado. Any
precipitation associated with the weak system as it progresses east-
northeastward is expected to be outside of our area. Saturday
evening into the first part of Sunday, we`ll see some brief upper-
level ridging as the next upper-level low comes ashore the west
coast and surface low pressure develops in the lee of the Rockies.
Focus will turn towards the low center`s approach and arrival in our
area and how it tracks Sunday night into Monday. Continued
variability in GFS and ECMWF solutions results in low confidence in
impacts, particularly in the precipitation forecast for this time
period. By 12Z Monday, the latest GFS places the ~540dam low center
over our eastern CO counties, having a brief shot of precipitation
mainly confined to eastern CO/parts of southwestern Nebraska while
the latest ECMWF has the low center positioned more over
southeastern CO, northeastern New Mexico, and the Texas/Oklahoma
Panhandles, allowing for more widespread, wrap-around precipitation
into our CWA. Regardless, models agree that some precipitation is
possible for at least portions of our forecast area; uncertainty is
in magnitude and extent of precipitation chances. Will need to
continue to monitor closely as at least the ECMWF solution and its
trends indicate potential for significant snowfall for the area.
Monday into Tuesday, the low center moves off towards the north-
northeast and any precipitation chances will gradually come to an
end.
High temperatures are again forecast to be in the 40s and 50s for
the weekend, dropping into the 30s and 40s Monday and Tuesday.
Morning lows will be in the upper-teens to low-20s through Monday
morning, dropping into the low-teens to low-20s by Tuesday morning.
Wind gusts reaching into the 30mph range are possible Monday
afternoon.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 145 PM MST Tue Dec 27 2022
KGLD...VFR conditions are expected through the period. A south
wind around 12kts at taf issuance will subside below 11kts by 01z
or so, veering to the southwest then northwest overnight at speeds
under 10kts. Winds become northerly around 18z, gusting to 20kts
or so from 18z-22z.
KMCK...VFR conditions are expected through the period. A light and
variable wind is expected from taf issuance through 15z. From
16z-19z, a light northwest wind is expected. From 20z through the
rest of the taf period, northwest winds increase with gusts to
25kts expected.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...99
LONG TERM...CC
AVIATION...99
Area Forecast Discussion
National Weather Service North Platte NE
518 PM CST Tue Dec 27 2022
...AVIATION UPDATE...
.SYNOPSIS...
Issued at 318 PM CST Tue Dec 27 2022
974 mb sfc low pressure near the coast of Washington state will
fill as it moves east tonight through Wednesday night tracking
along the Canadian border. The models show warm air advection
peaking near 15C at h850mb late this afternoon followed by a
steady decline in temperatures. The weakest of Pacific cold fronts
will drift through wrn and ncntl Nebraska tonight with very
modest cold air advection continuing through Wednesday night.
Key Messages:
-Confidence in the rain snow forecast Wednesday night and Thursday
is very low. Some models are dry.
-Confidence has increased in the prospect of a winter storm
affecting wrn and ncntl Nebraska Sunday and Monday.
&&
.SHORT TERM...(This evening through Wednesday night)
Issued at 318 PM CST Tue Dec 27 2022
The system coming ashore across the Pacific Northwest continues to
produce significant model differences across wrn and ncntl
Nebraska. The dispute among the models revolves are how much of
the energy moves through WY. The GEM and ECM show the system
becoming stronger and more developed across Nebraska than the NAM
and GFS. The models appear to be focusing the best forcing across
swrn and ncntl Nebraska and the prospect of snow across nwrn
Nebraska has diminished.
The ensembles of the GFS, GEM and ECM continue to show light
precipitation developing Wednesday night-after midnight. The GFS and
NAM have gone dry except for isolated showers which the GEM and ECM
continue to be bullish with the amount of forcing producing higher
QPF. Light rain mixed with freezing rain changing to snow is the
operative ptype and QPF is light, generally 1/10th of an inch or
less.
The p-type leans on the RAP model which shows temperatures at h850mb
hanging above freezing most of the night. There is reasonably good
support for ice accumulation in areas where the ground sfc remains
below freezing and the frost depth is currently a foot or more
across much of wrn and ncntl Nebraska.
The temperature forecast uses the short term model blend, the RAP
and HRRR models. This forecast is based on the expected cold air
advection pattern tonight and beyond which all models show.
.LONG TERM...(Thursday through Tuesday)
Issued at 318 PM CST Tue Dec 27 2022
WPC suggested a blend of the dry GFS/NAM with the wet ECM/GEM
models for QPF which actually resembles the ensembles of each of
those four models. Snow and rain is possible but not likely Thursday
morning and chance pops are in place for a highly uncertain
forecast. The forecast is for around an inch of snow and a few
hundreths of an inch of ice. The snowfall prediction is close to
WPC. The ice accumulation is somewhat speculative- WPC suggested
none.
This system should lift northeast through swrn and ncntl Nebraska
Thursday with dry weather Thursday night through Saturday.
There is little change in the storm system predicted to affect wrn
and ncntl Nebraska Sunday and Monday except to say confidence is
increasing and WPC suggested medium confidence in significant
snowfall across most of wrn and ncntl Nebraska. Their winter weather
outlook lines up fairly well with the GEM, ECM, GFS ensembles and,
the deterministic German Icosahedral model. It is worth noting the
operational GFS, GEM and ECM show a spread of about 200 miles with
the stripe heavy snow predicted across the cntl/nrn Plains and this
storm is currently circulating off the coast of nrn Japan.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 518 PM CST Tue Dec 27 2022
VFR is expected through Wednesday afternoon for western and north
central Nebraska terminals. Most cloud cover should be high level
(20kft agl) with ceilings gradually lowering toward 28/18z. Wind
is the main concern as low level shear conditions are present
through the overnight.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...CDC
SHORT TERM...CDC
LONG TERM...CDC
AVIATION...Snively