Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/08/18
Area Forecast Discussion
National Weather Service Hastings NE
538 PM CST Fri Dec 7 2018
.SHORT TERM...(This evening through Saturday)
Issued at 206 PM CST Fri Dec 7 2018
Plenty of mid/high level cloud cover streaming across portions of
Kansas this afternoon...but expect the majority of this to stay
south of the local area and for mostly clear skies to prevail. As
a result...despite temperatures climbing a few degrees above
expectations this afternoon...expect temperatures to rapidly fall
this evening...and with light winds...expect the potential for
some fog development.
The last several runs of the HRRR have consistently been trying
to develop at least patchy dense fog by midnight across portions
of the local area...becoming more widespread overnight. Because
there is the possibility for some cloud cover along with less
favorable light southwesterly winds...opted to limit reduced
visibilities to areas generally along and Northwest of a line
extending from Long Island, Kansas to Silver Creek
Nebraska...including the tri-cities for the early morning hours
Saturday...where the probabilities for mid/high cloud cover
impeding fog development will be lower.
Once any morning fog burns off across the local area tomorrow
morning...expect temperatures to rebound to near this afternoons
values...with most location topping out near freezing across the
local area. There will be an approaching upper level wave in
progressive northwesterly flow approaching the local area by
afternoon...but expect little impact on the local area tomorrow.
.LONG TERM...(Saturday night through Friday)
Issued at 206 PM CST Fri Dec 7 2018
Progressive northwesterly flow is forecast across the region to
start the extended periods with an upper level low dropping across
the local area late Saturday night...reinforcing cool temperatures
across the region through the start of the new work week. Expect
this low to track into the southeastern late Monday...allowing
for a ridge of high pressure to nudge across the local area during
the day Tuesday...with temperatures climbing back to near or
slightly above normal Tuesday afternoon. With partly sunny
skies...light winds...and seasonably warm temperatures...this will
likely be the nicest day next week.
Thereafter...progressive northwesterly flow continues...
bringing another upper level system and cold front to cross the
local area Tuesday night through Wednesday. This will result in an
increase in clouds and a small chance for precip...although
confidence in precip is not high. Expect yet another disturbance
and front fresh on the tail of the initial System...to bring
another small chance for precip late Wednesday night into
Thursday. Once again...confidence is not high with this system
either as its track will be well to our south and there is plenty
of discrepancy amongst model guidance bringing light snow to the
local area. What is more certain...however...is that seasonably
cool temperatures are expected through much of the extended
periods with no notable storms expected to have a significant
impact on the local area through at least the end of next week.
&&
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Saturday)
Issued at 526 PM CST Fri Dec 7 2018
Main impact during this TAF period will be from fog. Models
continue to show fog developing in cloud-free areas starting
around midnight. The most dense and widespread fog is expected to
occur from roughly 09-14Z. Visibility around 1 mile appear likely,
with lower visibilities possible at times.
Fog should gradually dissipate by mid morning as south winds
increase to around 10kts tomorrow.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...None.
KS...None.
&&
$$
SHORT TERM...Rossi
LONG TERM...Rossi
AVIATION...Mangels
Area Forecast Discussion
National Weather Service Huntsville AL
927 PM CST Fri Dec 7 2018
.NEAR TERM...(Tonight)
Issued at 927 PM CST Fri Dec 7 2018
Our next weather maker, a surface low forming over Deep South Texas
will continue moving to the NE over the next few days. As it further
develops, an extensive precipitation shield extending to the north
and east of this system will overspread the Tennessee Valley in the
overnight. This will bring higher chances for measurable rain across
the region, especially after midnight. The eastern "shield" of this
rain mainly extends from the Mid South, and ESE towards the Golden
Triangle. North and east of this, a mix of light rain, drizzle and
fog was occurring, making for varying flying conditions for some of
our airports.
A few complicating matters were noted however. There was a slightly
drier layer in the 600mb layer as noted via RAP and NAM soundings,
and should erode over the next few hours, as more moisture from the
system becomes more prevalent in the overnight. This was noted at the
306K isentropic region, with deeper moisture in lower (cooler)
regions.
The overall forecast for the area looks overall to be in good shape.
Will make no major changes at this time. Given that we have drizzle
locally as was forecast, it should gradually be "replaced" by more
widespread rains as the system to our SW nears. Temperatures across
all of the greater HUN area were above freezing, generally 40F and
above, even in the higher elevations where data was available.
.SHORT TERM...(Saturday through Sunday)
Issued at 249 PM CST Fri Dec 7 2018
A cold, damp, rainy day is still a near certainty for Saturday.
I295 flow backs from southwest to east-southeast in north AL, while a
southerly LLJ along this surface of 35-45kt develops across the deep
South. So a combination of ascent and strong convergence (also seen
along the 850 mb pressure surface) sets up in central MS and AL
during the day Saturday. At this point, will maintain a stratiform
steady light to moderate rain. The lift and precip rates will likely
be greatest from late Saturday afternoon into Saturday evening until
the LLJ and warm/moist conveyor belt shift east into GA by Sunday
morning. Will maintain likely PoPs Sunday morning diminishing to
chance levels (from west to east) Sunday afternoon, although a
deformation band, trowal, or combo aligns itself west-east from north
AL through the Carolinas. The 12Z NAM and ECMWF indicate strong
dynamic mid level cooling on Sunday in this band northwest of the 850
mb low track (noted in 850 mb isotherm cooling to 0C and below).
This appears to be overdone but will have to watch closely as it
could bring a conditional threat of wet snow despite surface temps
staying above freezing. If this trend continues in future model runs,
a much earlier snow forecast may be required. Will favor the more
conservative GFS handling of these dynamics for now and stay liquid
through 00Z/10 (60 hours). As for QPF, will maintain 2-2.6 inches
over our CWA which will fall over a 36 hour period, with most of it
within the 12 hour period Saturday night. This will likely bring a
few rivers to Action Stage, and possibly near Minor Flood Stage late
this weekend or on Monday.
.LONG TERM...(Sunday night through Thursday)
Issued at 249 PM CST Fri Dec 7 2018
The system that brought the heavy rain Sat/Sun will be exiting the
area to the east. We may see a break in precip Sunday night for a
period as drier air wraps in behind the departing system. However,
another system is forecast to be dropping SE out of the Rockies and
into the southern Plains Sunday night into Monday. This will act to
pull moisture back westward into the TN Valley Monday morning. Now,
the question is whether or not there will be enough cold air in place
aloft and how cool will the surface temps be able to get. The latest
NAM is probably the most concerning as it shows saturation all the
way up through the dendritic growth zone at the same time as the
better lift starts to make it in. Couple that with no warm nose aloft
and almost the entire profile is below freezing with only the
surface temps a degree or two above. This could translate into a
decent amount of snowfall for the TN Valley as both of those continue
through the late morning hours on Monday. However, the GFS/ECMWF
both show a nose of warmer air being pulled back to the west with the
moisture and could keep much of the precip in liquid form. GEFS
plumes have been on a downward trend the past few runs in terms of
both QPF and any snow amounts. So, confidence is very low and have
trended the forecast closer to the GFS/ECMWF solutions. This would
put rainfall totals as the second system moves in at less than 0.20
inches and snow amounts less than a quarter of an inch. It`s worth
pointing out that all guidance keeps temps above freezing as the
change over to snow occurs and should likely limit accumulations to
grassy and elevated surfaces. Still a good deal of uncertainty and we
will continue to monitor trends over the weekend and make adjustments
to the forecast as needed.
By midday Monday as the core of the upper level low begins to move
across the area, drier air will have filtered in helping to scour out
any lingering moisture and put an end to any wintry precip chances.
Colder air arrives Monday night into Tuesday with temps falling into
mid to upper 20s and with slight breezes, wind chills Tuesday could
be in the teens to lower 20s. Brief ridging and a surface high will
translate across the area Tuesday through Wednesday with highs around
50 degrees and overnight lows in the low to upper 30s.
Attention quickly turns to the a quick moving trough that shifts east
out of the desert SW and lifts NE across the TN Valley Thursday. The
ECMWF is not quite as deep with the trough and keeps the heavier rain
to the W/NW and have tried to stick to a blend of guidance. A
secondary and likely stronger system will move into the area on
Friday, which should result in some limited instability. Still too
far out to really dive into any specifics and there is enough model
variance to keep thunderstorms out of the forecast for now.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 552 PM CST Fri Dec 7 2018
Inclement weather will continue through TAF period. A surface low
forming across the Lower Rio Grande will move towards the NE and
reach the Mississippi Delta region by late Sat evening. Strong lift
and moisture north and east of this system will result in widespread
rain overspreading the region from west to east later tonight, with
rain continuing on Saturday. As such, have MVFR CIGs for the start of
the TAF, then reducing to IFR for much of the day Sat. Temporary
CIG/VIS reductions to LIFR or lower are possible on Sat, but did not
include it in the TAF given great uncertainty on positioning of the
heavier rain/fog/drizzle periods. NE winds around 5 kt tonight will
become ENE and increase to the 10-20 kt range during Sat afternoon,
as the surface low nears this region.
&&
.HUN WATCHES/WARNINGS/ADVISORIES...
AL...NONE.
TN...NONE.
&&
$$
NEAR TERM...RSB
SHORT TERM...17
LONG TERM...Stumpf
AVIATION...RSB
For more information please visit our website
at weather.gov/huntsville.
Area Forecast Discussion
National Weather Service North Platte NE
549 PM CST Fri Dec 7 2018
.SHORT TERM...(This evening through Saturday)
Issued at 329 PM CST Fri Dec 7 2018
Fog development looks favorable tonight across about the southeast
half of the forecast area from Springview to Thedford to Ogallala.
Both the time lagged HRRR and RAP indicate visibility falling to
perhaps lower than 1/4 quarter of a mile after midnight in these
areas. Will include areas of fog in the forecast. Otherwise mainly
clear skies are expected until the fog develops. Lows will quickly
fall again this evening with the snow cover and light winds. Single
digits are expected again the lower valleys with mid teens elsewhere.
As mentioned, with surface high pressure in place, winds will remain
light tonight.
South winds will increase to around 15 mph with higher gusts
Saturday. Windiest conditions will be across portions of north
central Nebraska. Highs will be a few degrees warmer Saturday most
areas. The warmest readings (lower 40s) will be across western
Nebraska, where the wind will turn more westerly during the
afternoon as a surface trough pushes east.
.LONG TERM...(Saturday night through Friday)
Issued at 329 PM CST Fri Dec 7 2018
Dry weather continues for the next several days. There is just a
slight chance for some precipitation as a shortwave trough digs
southeast across the northern Rockies and crosses the Plains
Wednesday night into Thursday. Models have been forecasting this
wave to become negatively tilted east/southeast of the area, with a
fairly significant storm possibly developing across the Mississippi
valley region.
Temperatures will be milder as we head into the weekend and
especially next week. A Pacific airmass will be in place, with
highs in the 30s to lower 40s. Snow cover will continue to hinder
the warm up somewhat. As the snow slowly melts next week,
increased moisture cold lead to late night and early morning fog
in spots.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 513 PM CST Fri Dec 7 2018
Clear skies currently exist overhead. The main aviation concern
centers on fog potential late tonight-tomorrow morning with the
greatest fog risk across southwest NEB into the southern Sandhills
and central NEB areas. Patchy to areas of fog are expected to
develop beginning near and after midnight with visibilities as
low as IFR or worse expected. Visibilities are expected to then
improve through early-mid morning. Winds increase tomorrow with
light breezes in the afternoon out of the south/southwest,
strongest across northern NEB. Winds will start to shift and
become westerly late tomorrow into tomorrow night attributable to
an advancing cold front.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...Taylor
LONG TERM...Taylor
AVIATION...ET
Area Forecast Discussion...UPDATED
National Weather Service Lubbock TX
954 PM CST Fri Dec 7 2018
.UPDATE...
Only some minor tweaks were made to the forecast this evening.
The center of an upper level storm system currently located
around southeastern Arizona/southwestern New Mexico was still
churning towards the region. Lightning was also observed south of
the center of the system in Mexico. Stronger upper level
diffluence located in New Mexico was about to cross into West
Texas late this evening with several areas of notable lift.
At the surface, temperatures were hovering around 32-33F but
mostly rain was reported through the region with little icing
occurring. Model RAP soundings show deeper easterly flow aloft
with a subsequent cooling of a weak warm layer aloft over the next
couple of hours on the caprock. Once this warm layer moves closer
to 0C the transition over to snow will be quick and likely
produce large dendritic snow. High res models and CAMs have
shifted highest snowfall amounts slightly to the west favoring the
southwestern and south-central South Plains. Forecast total snow
was relatively unchanged showing maximum amounts of 3-4 inches in
the aforementioned areas. An examination of the theta-es and EPV
fields indicate some weak symmetric stability. Therefore, some
snow banding is possible which could bring some locally higher
snow amounts. Taking all the above into consideration, the
current winter weather advisory for the entire FA will be left
unchanged.
&&
PREV DISCUSSION... /issued 256 PM CST Fri Dec 7 2018/
DISCUSSION...
Winter weather event still on tap for tonight and into Saturday
morning, although with some adjustments. The 12Z model suite
uniformly trended toward a more open system and a further south
swath of precipitation. Upper air analysis supports this concept
with a 150 kt 250 mb jet streak this morning moving across the
central Plains and only a small 100-120 kt jet streak along the
California coast diving into the system. As a result the best
chance for precipitation is now shifting south, mainly south of TX
Highway 114. The models are suggesting there will be a pretty
tight gradient from the precip max northward to no precip, and
that no precip zone may very well be across the northern tier of
the forecast area. The other issue today is the change of precip
phase, i.e., timing the changeover from rain/freezing rain to
snow. Previous timing of early to mid evening west and early
morning east still looks reasonable. This will leave a brief
window for ice (freezing rain or sleet) before what is expected to
be the bulk of the precipitation falling as snow. Models still
have the peak/strongest lift occurring in the dendritic growth
temperature zone, so snowfall may become heavy at times in the
swath that develops later tonight. Finally, this southward
adjustment to the precip will favor more snow across the southern
South Plains and the Rolling Plains than previously expected.
Snowfall is likely to end across even the eastern zones by
Saturday afternoon. Forecast peak snowfall amounts remain 3-4
inches but shifted southward toward Brownfield, Tahoka, Lubbock,
and Crosbyton with a secondary maximum off the Caprock toward
Jayton and Aspermont. Forecast snowfall was lessened further north
from Friona/Muleshoe to Childress/Memphis. The Winter Weather
Advisory will continue as is, but if the models are correct with
the sharp cutoff on the northern side of the system and with the
track of the system, then adjustments will need to be made later
this evening/tonight.
The remainder of the forecast period looks relatively quiet. The
forecast area should remain under at least a small amount of
cyclonic curvature through next week except for a brief
interruption Tuesday as short wave ridging quickly traverses the
region. The result will be a continuation of cooler than normal
temperatures. A short wave trough will be close on the heels of
the upper ridge and might bring a quick shot of precipitation
Thursday. Have introduced a slight mention across the northern
third of the forecast area with that wave.
&&
.LUB WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until noon CST Saturday for TXZ021>044.
&&
$$
01
Area Forecast Discussion...UPDATED
National Weather Service Norman OK
924 PM CST Fri Dec 7 2018
.UPDATE...
Increased snow amounts by one to two inches and reduced area of
freezing rain. Kept the location for the axis of greatest
snowfall and the area of the advisory the same.
&&
.DISCUSSION...
Precipitation has begun to move into north Texas and just across
the Red River. At the time of this writing, most of it remains
liquid rain, though there have been a few reports of some light
freezing rain mixed in.
Using GFS soundings as a best estimate for evolution of the warm
nose as the GFS seems to most closely match the 00Z sounding and
the few freezing rain reports we`ve received thus far. NAM keeps
the warm nose too warm and the RAP is too cool. Following the GFS
led to a more limited area of freezing rain with most everything
transitioning by 09Z.
As far as QPF and snowfall amounts, the GFS and RAP have caught
on to a feature of enhanced lift in southeastern New Mexico and
bring that up through north Texas and southern Oklahoma (ECM
shows evidence of this as well in its QPF output). This is
expected enhance QPF along its path and thus snowfall totals.
Temperature forecast has been on track thus far, so left that
alone.
Day
&&
.PREV DISCUSSION... /issued 540 PM CST Fri Dec 7 2018/
AVIATION...
CIGS will drop below MVFR overnight, along with some reduced
visbys due to precipitation in the form of rain and/or snow.
Flight conditions north of I-40 should remain unimpacted, however.
Expect at least MVFR cigs for most terminals through 15Z Sat. SPS
could experience some brief moderate to heavy precipitation by
early Sat morning. Winds will remain northerly around 5 to 15 kt.
&&
.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK 30 32 26 44 / 70 50 20 0
Hobart OK 28 34 22 46 / 80 50 10 0
Wichita Falls TX 33 35 29 46 / 90 90 10 0
Gage OK 23 34 22 47 / 0 0 0 0
Ponca City OK 27 35 22 44 / 0 0 10 0
Durant OK 36 39 32 47 / 100 90 30 10
&&
.OUN WATCHES/WARNINGS/ADVISORIES...
OK...Winter Weather Advisory until midnight CST Saturday night for
OKZ021>031-033>040-044.
TX...Winter Weather Advisory until midnight CST Saturday night for
TXZ083>088.
&&
$$
14/03