Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/15/17
Area Forecast Discussion
National Weather Service Cheyenne WY
820 PM MST Thu Dec 14 2017
.UPDATE...
Issued at 820 PM MST Thu Dec 14 2017
Quick update here this evening to upgrade southwest Platte County
(ie. Bordeaux area) to a High Wind Warning. Latest HRRR output
sends ribbon of low-level subsidence into this area overnight and
Friday. Was concerned earlier with winds from 300 degrees (less
favorable), but these have since backed to 280 (more favorable).
This in combination with 750mb flow of 45-50 knots were sufficient
indicators for confidence to be enough to issue the warning.
Otherwise, inherited forecast on track this evening.
&&
.SHORT TERM...(This evening through Saturday Night)
Issued at 232 PM MST Thu Dec 14 2017
Latest water vapor loop was showing drier air starting to filter
into southeast Wyoming behind a departing mid level shortwave.
This will continue to allow the snow showers to dissipate through
the remainder of the afternoon. Meanwhile, a band of stronger mid
level winds are expected to push through Montana late tonight into
tomorrow. As this band of stronger wind speeds move through this
region, it will cause the low level height/and pressure gradients
to tighten along the Laramie Range and Arlington late tonight into
Friday. As a result, we went ahead and upgraded the High Wind
Watches to Warnings across Arlington and the Laramie Range late
tonight into Friday. Hung on to a High Wind Watch for Bordeaux
since it appears the subsidence will be less favorable in that
region, and the surface trof tends to hang on in that region.
Later shifts will need to keep an eye on this potential.
Temperatures will be much warmer than today, due to good downslope
affects.
The next concern will be the shortwave now approaching the
Pacific northwest. This feature is expected to dive south during
the next couple of days. If this trend continues it will keep the
bulk of the snow across western Wyoming. We will have to watch
Carbon county especially Saturday and Saturday night especially if
that area ends up having a longer period of upper level
diffluence. The other concern will be the potential for deep low
level moisture developing behind the cold front. This will result
in lesser snow amounts mainly east of the Laramie Range. However,
it could be in the form or light snow/freezing drizzle which may
still cause some impacts Saturday night into Sunday morning
especially in the southern Nebraska Panhandle.
.LONG TERM...(Sunday through Thursday)
Issued at 232 PM MST Thu Dec 14 2017
Things should begin to clear out on Sunday with some upper level
ridging developing over the region early next week. This will
allow for a gradual warmup early next week, before another strong
cold front plows through the region Wednesday night into Thursday.
This front may bring some more snow along with it, but it does not
look like a significant snow maker.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 525 PM MST Thu Dec 14 2017
VFR conditions to prevail at area terminals through the period as
few-sct upper level clouds stream thru the area. More importantly
to airfield operations will be developing gusty winds after 07z at
RWL, after 10z at CYS/LAR, and after 17z at western Nebraska
sites. West wind gusts of 25-35 knots will be standard after these
times. Winds will persist thru the end of this TAF cycle before
decreasing Friday evening.
&&
.FIRE WEATHER...
Issued at 232 PM MST Thu Dec 14 2017
Elevated fire weather concerns are possible tomorrow due to strong
west winds developing. However, minimum humidites will most likely
range from 15 to 20 percent which will limit any red flag
potential. Beyond that timeframe we are looking a period of colder
conditions will some potential for snowfall this weekend.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...High Wind Warning from midnight tonight to 9 PM MST Friday for
WYZ106-110-116-117.
NE...None.
&&
$$
UPDATE...CAH
SHORT TERM...REC
LONG TERM...TJT
AVIATION...CAH
FIRE WEATHER...REC
Area Forecast Discussion
National Weather Service Grand Forks ND
955 PM CST Thu Dec 14 2017
.UPDATE...
Issued at 955 PM CST Thu Dec 14 2017
Most sites across the region have been seeing at least flurries
with -SN, and there have been reports in the Fargo/Moorhead area
of around a half an inch. This corresponds well with SPC meso
page placement of 925mb frontogenesis, which the RAP has hanging
around the area for a few hours longer. Bumped up POPs in this
band, and it should slide off to the southeast later tonight. More
snow will move in from the northwest by midday tomorrow. Flurries
elsewhere for much of the region. Accumulations could be up to a
few tenths of an inch. Continued to keep a FZDZ mention for brief
periods across eastern ND, as we could see some drying out in the
ice producing layer at times.
&&
.SHORT TERM...(This evening through Friday)
Issued at 320 PM CST Thu Dec 14 2017
Expecting it to remain cloudy through the entire short term
period. Along with that, flurries or very light snow remain
possible throughout as well. Currently think more flurries will be
around early this evening. Then models indicate a little better
chances for light snow will develop by mid evening, mainly over
the Devils Lake region and northern Red River Valley. This
activity may expand further south and east after midnight.
However, really only talking about a dusting of snow with this.
Next system still on track for Friday into Friday night. This next
system brings most of the area some light snow, but the main band
looks to be from the northern Red River Valley over toward
Bemidji, where up to 2 to 3 inches of snow are possible. Lesser
amounts are expected to the west. Wind speeds do not look very
strong, which should lessen the impacts.
.LONG TERM...(Friday night through Thursday)
Issued at 320 PM CST Thu Dec 14 2017
Friday night and Saturday...Our northerly upper flow will
transition to zonal heading into the weekend. As this occurs deep
warm air advection snowfall should set up along a northwest-
southeast oriented baroclinic zone. The swath should cover a tract
from Devils Lake through the north and central valley to west
central Minnesota with little or nothing over SE ND. Upper level
support is lacking and there is the though that vigorous WAA will
trim some of the available ice to the point of a possible mix of
pcpn types, first over Devils Lake before propagating toward the
valley later Fri night. Nevertheless, still favoring SN as main
pcpn and sticking with the inherited 1 to 3 inch amounts. Impacts
should be diminished by the lack of wind during this event.
Forcing should be over by Saturday afternoon.
Sunday through Thursday...Zonal flow will likely persist much of
the week, with a stronger system likely affecting the region later
Mon and Mon night. The cyclone will likely move across Central
Canada while the surface and upper trough swings through the
forecast area dropping small snowfall amounts. But here the wind
will be stronger behind the front, possibly creating blowing snow
impacts. It appears that we`ll go more NW flow midweek as temps
drop to near and then below average values. Then a phasing trough
could make things more interesting later in the week, with the
early money on a more southern track, but we`ll have to keep an
eye on it with time.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 644 PM CST Thu Dec 14 2017
Most areas are MVFR although a few have scattered out to VFR.
Think this will be short lived and all locations will be MVFR or
IFR by morning. Scattered snow showers moving through have brought
-SN to the central and eastern TAF sites at various times this
evening, with the snow coming in an out but remaining above 6SM
for the most part. A stronger band of snow will begin to move
into the area tomorrow morning, spreading from northwest to
southeast across the forecast area. Think the better chances for
significant snow will be at the northern TAF sites. Visibilities
in the snow band will be in the 3-5SM range early on with some
sites seeing 1-2SM late in the period. Light and variable winds
will steady out of the southeast, but remain below 12 kts.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.
&&
$$
UPDATE...JR
SHORT TERM...Godon
LONG TERM...WJB
AVIATION...JR
Area Forecast Discussion
National Weather Service Omaha/Valley NE
515 PM CST Thu Dec 14 2017
.SHORT TERM...(Tonight through Sunday)
Issued at 300 PM CST Thu Dec 14 2017
Models suggest that isolated snow and rain showers will move
through the area this evening, then push south of the area by
midnight. These are tied to an upper trough and reinforcing
surface trough across eastern SD that will settle southward
tonight. No significant accumulation expected although HRRR and
Highres ARW/NMM suggest a tenth of an inch if you happen to be
underneath one of the showers.
Much above normal temperatures return Friday into Saturday ahead
of the next cold front which arrives Saturday afternoon. Highs in
the 40s tomorrow, and in the mid 40s to upper 50s on Saturday,
depending on which side of the front.
Models do suggest that the trough currently across northwest
Mexico eventually gets shunted north Saturday night into Sunday.
the northern edge of this moisture could bring a wintry mix to
extreme southeast NE and southwest IA Sunday morning. Meanwhile,
an elongated area of Pacific moisture to our north never gets a
strong enough push into the area so no precip expected from that
feature.
.LONG TERM...(Sunday night through Thursday)
Issued at 300 PM CST Thu Dec 14 2017
Significant warming takes place Monday through Wednesday of next
week ahead of a major pattern shift that hits our area on
Thursday. Temps in the 40s Monday and Tuesday, but likely into the
lower 50s for Wednesday. That`s the last warm day though, as an
arctic front arrives on Thursday. This also could signal a shift
to a wetter pattern into the Christmas Holiday period, but then
again, that`s still 10 days away, and a lot can change. Fairly
high confidence on the colder pattern, but lower confidence on any
precip/snowfall patterns at this time.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 512 PM CST Thu Dec 14 2017
MVFR conditions at KOFK will trend toward improvement over the
next few hours, with potential for very light rain/snow in or near
the site. Kept ceilings at VFR levels at KLNK, with a scattered
MVFR mention, and also mentioned vicinity showers there for a few
more hours. At KOMA, think conditions will remain just above VFR
thresholds, and while I can`t rule out a stray sprinkle or flurry,
coverage (and chances) seemed too low to mention it. At all sites,
conditions will improve after midnight to VFR, with clouds
dissipating. Light northwest winds this evening and tonight will
become southwesterly on Friday but will remain 10kt or less.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...None.
IA...None.
&&
$$
SHORT TERM...DeWald
LONG TERM...DeWald
AVIATION...Mayes
...Update to aviation forecast discussion...
.SHORT TERM...(This evening through Friday)
Issued at 304 PM CST Thu Dec 14 2017
A weak disturbance will continue to bring light precip to the
region this afternoon and evening before exiting overnight.
Afternoon water vapor imagery showed a compact H500 wave/PV lobe
tracking southeastward through Nebraska. Enough attendant lift and
moisture was present with this feature to generate a broad but
rather patchy region of light rain and snow, though accumulations
were very light. An overall drying trend has been noted in MRMS
data over the last few hours and most model guidance support this
evolution. Did keep the mention of light sprinkles/flurries east
of Manhattan through midnight given upstream echos extending as
far as the Black Hills and recent runs of the HRRR generating
light POPs through that same time range. Broad upper level ridging
builds in the wake of this system for Friday with increasing H850
WAA aloft setting the stage for a warm start to the weekend.
.LONG TERM...(Friday night through Thursday)
Issued at 304 PM CST Thu Dec 14 2017
The long-term remains mostly quiet with the best chance of
precipitation coming on Sunday morning.
The aforementioned upper level ridge will give way to a sharp
longwave trough digging southeastward along the West Coast
Saturday morning, placing Kansas in broad WSW flow. Saturday will
feature yet another round of unseasonably warm weather with H850
temps soaring to +11 to +13 C. The NAM is a surprisingly cool
solution and places the stationary surface boundary further
southeast than the other solutions, so leaned toward the
EC/GFS/GEM consensus for highs on Saturday. Gusty southwest winds
of 15 to 25 kts combined with afternoon RH values around 25 to 30
percent will present a very high fire danger throughout northeast
Kansas given the dry state of fuels.
A sharp, negatively-tilted H300 wave lifts through Kansas between
06 and 18Z on Sunday morning with a weak 1005 mb surface cyclone
pulling off the Front Range after 06Z Sunday. The evolution of the
surface trough/low as the upper level wave outruns it during the
day on Sunday is somewhat uncertain. In either case, most guidance
have backed off on the coverage of precip Sunday morning and the
thermal profiles would support mostly rain with maybe a wintry mix
in the early morning along the NE border. The NAM is, once again,
the outlier in holding the surface trough further south and
advecting cool/moist near-surface air along the KS/NE border.
Should this solution pan out, there may be a brief window of
freezing drizzle near the NE border Sunday. However, given the
NAM`s high moisture bias and the lack of support from other
solutions with warmer and drier profiles, did not include any
mention of freezing precip in the updated forecast.
A second lobe of energy follows on the heels of this system late
Sunday night, but the sensible weather effects look to be minimal.
Broad quasi-zonal upper ridging then prevails for Tuesday and
Wednesday and will bring above average temperatures and dry
conditions. A pattern change does shape up for the end of the
week. Upper level ridging builds along the west coast with a
potent trough digging southward along the downstream flank of the
ridge for Thursday and Friday. The 12Z GFS/EC/GEM vary greatly in
the evolution of this wave and this evolution will play directly
into the region`s weather around the Christmas holiday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 520 PM CST Thu Dec 14 2017
VCSH possible at terminals through 04Z though precipitation has to
overcome dry air in the lower levels. May see a brief period of
MVFR cigs at MHK and have less confidence of a a cig at TOP and
FOE. VFR conditions expected after 05Z through the end of the
period. Winds increase from the west southwest to around 10 kts
after 18Z.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Skow
LONG TERM...Skow
AVIATION...53