Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/29/17
Area Forecast Discussion...UPDATED
National Weather Service Fort Worth TX
856 PM CST Thu Dec 28 2017
.UPDATE...
Regional aircraft soundings, in addition to the 00z KFWD RAOB,
indicate that the remnant frontal inversion (left over from
Tuesday`s cold front) has resaturated. This has resulted in
gradually lowering cloud heights across the region this evening,
with the lowest cloud cover along and west of the I-35 corridor
where the deepest moisture resides. The combination of cloud
ceilings of less than one thousand feet, fairly deep saturated
depths of 3-4 kft, negligible dewpoint depressions, and just a
hint of upglide all spell a potential for drizzle and fog here.
Indeed, we`ve seen surface observations indicating the development
of mist and some drizzle over the last hour slowly expanding
eastward to Bowie, Bridgeport, and Mineral Wells. Latest runs of
the RAP suggest that isentropic ascent along the 280 K theta
surface will only increase as the night wears on, which means
we`ll probably be able to squeeze moisture out of the low cloud
deck. Given all of this, I`ve gone ahead and added in a mention of
drizzle and fog initially west of US-281 this evening, expanding
to near and just west of the I-35/35W corridor towards Friday
morning.
While surface temperatures this hour are running in the mid and
upper 30s, I`m not expecting temperatures to fall all that much
more overnight given such an expansive low cloud deck and weak
warm advection. Thus, the official forecast will keep most of the
area above 32F tonight, but we`ll need to keep an eye on the far
north and western areas like Bowie, Gainesville, Graham, and
parts of Eastland County where temperatures may flirt with the
freezing mark. Given the marginal temperatures, elected to forgo
any mention of freezing drizzle at this time, but we`ll closely
monitor trends this evening and overnight.
Otherwise, bumped sky cover up through much of the day on Friday.
There are signs that we should get a decent push of drier air as
some stronger westerlies arrive just off the deck, so we may yet
get to see the sun by late tomorrow afternoon. Updated products
have been transmitted.
Carlaw
&&
.AVIATION... /Issued 559 PM CST Thu Dec 28 2017/
/00Z TAFs/
The Seattle-like weather featuring a seemingly unending stretch of
low cloud cover will continue tonight and through much of the day
on Friday. Moisture remains stubbornly wedged between an old
frontal inversion, with a base around 2 kft AGL, and a larger
subsidence inversion at around 850 mb (around 6 kft AGL). Our
presently-ascending 00z balloon corroborates recent ACARS
soundings which show this roughly four thousand foot layer is
completely saturated, indicating that earlier hopes of some
clearing appear quite unlikely. A combination of very modest
isentropic upglide and nocturnal cooling will ensure that CIGs
continue to gradually build downwards tonight. As a result, I have
favored the more pessimistic guidance and show low-MVFR CIGs
developing around 03z this evening across the western Metroplex
sites, and a few hours later to the east. Similar trends are
anticipated at the Waco TAF site as well. Winds during the
overnight period will be light at speeds under 6 knots and
eventually become easterly.
Short-term guidance indicates that very modest ascent may
materialize after midnight within the saturated lower-levels as a
large mass of warm advection passes by to our north. Since cloud
depths will be near 4 kft and bases just 1-2 kft AGL, I can`t
discount some drizzle if this lift does in fact materialize, with
the most likely time frame around 10-16z. Given the widespread
cloud cover, temperatures will not move a lot tonight, but may
briefly approach freezing across the outlying Metroplex sites
(AFW, FTW, GKY) towards daybreak on Friday.
It looks like we`ll finally get an injection of drier air on
strengthening westerlies late Friday afternoon and VFR conditions
are expected to return. This may be short-lived, however, as re-
saturation occurs Friday night and MVFR/IFR CIGs return once
again.
Carlaw
&&
.SHORT TERM... /Issued 416 PM CST Thu Dec 28 2017/
/Tonight through Friday Night/
The sharp subsidence inversion aloft has acted as a lid, keeping
enough moisture trapped to prevent much dissipation in the clouds
throughout the day today. This will be the case through the night
as well, with an improvement expected to begin Friday morning.
Given the slow thinning of cloud cover expected to happen
overnight, and light winds, temperatures will remain in the low to
mid 30s.
Additional west to east clearing is expected during the day on
Friday, with clouds sticking around in the northeast. High
temperatures on Friday will be dependent on how much, and how far
east, clouds manage to clear out. The more hours of sunshine a
location gets, the higher the temperatures will be. In the west,
temperatures will reach the mid 50s, while low to mid 40s are
expected in the northeast. Winds are expected to veer to the
south through the day, but not much warm air advection will be
associated with the southerly winds.
A weak surface low will start to develop in the Texas panhandle
overnight on Friday, allowing for a surge of moisture to stream
across the the area. Dew point temperatures will climb from the
low 30s to mid 40s across Central Texas through the night. With
weak isentropic ascent, and a saturated lower atmosphere, patchy
drizzle will be possible after midnight and across southern
portions of North Texas south of I-20. Temperatures Friday night
into Saturday morning will be in the mid 30s across the Red River
and mid 40s across Central Texas.
Hernandez
&&
.LONG TERM... /Issued 416 PM CST Thu Dec 28 2017/
/Saturday through Thursday/
Our well-advertised arctic outbreak is still on schedule to
envelop North and Central Texas beginning Saturday afternoon, and
culminating with likely some of the coldest air of the winter by
New Years Day and Tuesday.
The latest guidance is in decent agreement in bringing the
leading edge of the cold air southward through the forecast area
during the daytime hours Saturday. One challenging aspect will be the
presence of a subtle wave on the front, which the GFS and NAM
track southeastward toward Palestine/College Station by late
afternoon Saturday. Depending on how this low plays out, we could
see a bit more baroclinicity along the front, which in addition
to enhancing the temperature contrast across North Texas, may
affect the cloud and precipitation forecast for Saturday. Not a
lot of confidence on Saturday`s forecast, but suffice to say
there`ll be a significant contrast in temperatures by mid
afternoon from, say, Gainesville to Killeen and Palestine. For
now, have kept small pops across eastern North Texas for the
potential of intermittent light rain showers.
Things get a bit more straightforward, temperature-wise from
Saturday night onward. The freezing line by 12z Sunday may extend
from near Comanche to DFW to Sulphur Springs, and driving
southward. Cold air advection will start increasing Sunday as
north winds pick up. Temperatures along and north of I-20 will
have a hard time rebounding at all from their Sunday morning
readings. Farther south, some areas will be able to reach the 40s
prior to midday, before the colder air starts to invade.
By New Year`s morning, low temperatures will have dropped well
into the teens across virtually all but the southernmost counties
of the forecast area. A rebound into the lower 30s will occur
across the south, but from I-20 northward, readings will remain
entrenched in the mid to upper 20s, despite the presence of low-
angle winter sunshine.
The other big challenge remains the precipitation forecast. To cut
to the chase, held onto chance pops for generally the eastern
half of the area Saturday night, trending southward during the day
Sunday. Small pops were maintained elsewhere. Large-scale lift
associated with cyclonic vorticity advection or warm advection is
not pronounced whatsoever. However, there is a modest amount of
isentropic upglide being depicted by the models across North and
Central Texas Saturday night/early Sunday morning, well behind the
cold front. This lift may be sufficient to induce some widely
scattered LIGHT rain, or more likely, some occasional drizzle
across much of the area. There simply isn`t enough deep moisture
to suggest any significant amounts...BUT...where the liquid
precipitation coincides with temperatures below 32 degrees - we
could see some light icing, particularly on elevated road
surfaces. We may also see a few snow flurries across the northern
counties on Sunday, but again, with moisture in limited supply,
don`t expect any accumulations from this precipitation type.
The main time period to be concerned about any slick
spots would be across far North Texas early Sunday morning,
especially between I-20 and the Red River, shifting into central
Texas by early New Year`s Eve. The models are in good agreement
about drying the airmass from north to south during the day
Sunday, likely bringing an end to any precipitation in a similar
fashion.
For Tuesday onward - didn`t make any major changes to the previous
forecast. It will remain cold through the period, yet dry.
Bradshaw
&&
.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth 36 49 39 48 32 / 5 5 5 10 30
Waco 37 50 40 56 35 / 5 5 10 10 30
Paris 29 43 33 41 29 / 0 5 10 20 30
Denton 33 47 35 45 29 / 5 5 5 10 20
McKinney 32 46 36 45 31 / 0 5 5 20 30
Dallas 35 48 40 48 33 / 5 5 5 20 30
Terrell 34 47 38 48 32 / 0 5 5 20 30
Corsicana 36 48 41 52 36 / 0 5 10 20 30
Temple 38 51 42 61 39 / 5 5 10 10 20
Mineral Wells 34 51 35 48 28 / 5 5 5 10 20
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
90/58
Area Forecast Discussion
National Weather Service Hastings NE
559 PM CST Thu Dec 28 2017
.SHORT TERM...(This evening through Friday)
Issued at 258 PM CST Thu Dec 28 2017
This afternoon, high temperatures have climbed into the 20s for
most of the area under mostly clear skies. Cloud cover will
increase tonight thanks to an approaching upper level jet and low-
level moisture transport. That should keep temperatures from
falling much lower than the upper single digits.
Models have remained consistent that whatever snowfall occurs in
association with the jet streak tonight will stay just northeast
of the forecast area. That said, it will be close, so I`ve
included flurries for the far northern fringes of the area.
Also of concern tonight is low stratus and fog. Southerly flow
ahead of a surface trough will will advect in some low-level
moisture, but it is questionable whether fog will actually
develop. The RAP and HRRR visibility forecasts certainly hint at
the development of fog, and their soundings look favorable as
well. That said, several inches of snow on the ground and lows
around 10 degrees aren`t a "classic" setup for fog by any means.
Part of the reason that the HRRR and RAP are so aggressive is
likely because they are melting off too much snow cover. For now,
I`ve kept fog out of the grids, but upcoming shifts will monitor
this closely.
Either way, I do expect that skies will be mostly cloudy through
the day on Thursday, aside from maybe northern Kansas. As a
result, highs may reach the low 30s in northern Kansas, while
central Nebraska stays stuck in the teens to mid 20s.
.LONG TERM...(Friday night through Thursday)
Issued at 258 PM CST Thu Dec 28 2017
The main story for the extended forecast continues to be the
extremely cold temperatures over the weekend. Overall, model
agreement has improved on the magnitude of the cold air.
Northerly surface flow Friday night will make for lows between -5
and 5 degrees, but the noticeable cold will arrive on Saturday,
when high temperatures will remain in the single digits and
overnight lows will drop into the -5 to -15 range.
The GFS continues to back off on the snow potential on Saturday
and Saturday night, and the Euro has remained consistent that most
of the snow will stay across the NE/SD border. Nevertheless, we
still have light snow accumulations possible north of I-80, and
given the strength of the cold air advection, I wouldn`t be
surprised to see flurries across the entirety of the forecast
area.
New Year`s Eve will be the coldest day. Daytime Highs will be -5
to 5 degrees and overnight lows are expected to dip into the -10
to -20 range. The latest GFS and Euro actually take the center of
the 1050mb surface high just east of the forecast area, which
would be slightly less favorable for extreme cold. Nevertheless,
wind chills will be dangerously cold...even as light as the winds
are.
A slow warming trend is expected into the early part of next
week, and the threat for additional snow continues to look quite
low.
&&
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Friday)
Issued at 545 PM CST Thu Dec 28 2017
Ceilings will lower to MVFR on Friday as another upper system
moves through, although best lift will be northeast, so any snow
should remain northeast.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...None.
KS...None.
&&
$$
SHORT TERM...Mangels
LONG TERM...Mangels
AVIATION...Heinlein
Area Forecast Discussion
National Weather Service Grand Rapids MI
909 PM EST Thu Dec 28 2017
LATEST UPDATE...
Update
.SYNOPSIS...
Issued at 324 PM EST Thu Dec 28 2017
Several waves of low pressure will move across the Great Lakes over
the next few days generating more lake effect snow showers and
reinforcing the cold air already in place. Several inches of
snowfall are expected along the lake shore north of Muskegon
tonight and again Friday night and Saturday.
&&
.UPDATE...
Issued at 910 PM EST Thu Dec 28 2017
The primary snow band has for the most part been off shore until
very recently. As a strong upper shortwave currently over central
Wisconsin, will move across Lower Michigan during the early
morning hours of Friday. The latest runs of the HRRR, HRRRX, RAP
and NAM show strong lift and wind convergence in the 950 to 850
layer as this system moves onshore. The lake snow band has become
much better organized within the past hour or so. If fact LDM is
now reporting steady heavy snow with winds gusting to 30 mph.
It seems to me the warning counties will see two to three hours of
1 to 2 inch per hour snowfall rates as this band moves onshore. So
it makes sense to continue the headlines as is.
Once the upper jet moves through around sunrise, inversion height
crash to 5000 ft, so snow shower activity will diminish but not
end. There may be a brief break between the lake enhanced snow
showers from the current system and the snow showers from the next
system that moves in by sunset Friday.
&&
.SHORT TERM...(This evening through Saturday night)
Issued at 324 PM EST Thu Dec 28 2017
Forecast concerns deal with ongoing headlines winter weather through
the period.
We`ve been watching a strong meso vort generated band of lake effect
snow moving NNE up the lake. It`s now beginning to make landfall
north of Muskegon. Widespread 30+ DBz echos are in this band and
will no doubt result in 1-2 inch per hour snowfall along US-31 from
Muskegon to Ludington this afternoon and evening. For that reason,
we`ve kept the headlines in place. Bufkit thermal/omega profiles
reveal 30-40 microbars/sec of upward motion around 00z tonight in
the warning area. It`s expected that locations near the shore will
see 6 to 9 inches of snow from this. Additionally, a short wave
moving across Wisconsin as noted on current water vapor imagery will
provide light synoptic and lake enhanced snowfall across the cwa
this evening.
We`ll probably see a lull in the snow Friday before the next short
wave arrives Friday night. H8 temps fall from -18c to -24c over the
lake and the resulting upward motion form the short wave will
enhance the lake effect and another few inches of snow is possible
Friday night and Saturday and new headlines may be needed.
.LONG TERM...(Sunday through Thursday)
Issued at 324 PM EST Thu Dec 28 2017
The main theme in the long term period of Sunday through next
Thursday is continued cold weather. A surge of Arctic air moves in
Monday into Tuesday with 850MB temps colder than -20C moving through
the Great Lakes region. A brief period of slightly "warmer" air
moves through on Tuesday when 850MB temps rise to around -10C. This
is short lived however as near -20C air moves back in for Wednesday
and Thursday. Temperatures will remain well below normal in the
teens for highs most likely with lows in the single digits above and
below zero.
As for snow potential, we maintain a northwest flow aloft, so lake
effect snow will continue. High pressure will be the dominant
surface feature throughout the long term so not expecting
significant accumulations. Light lake effect snow will be fairly
persistent towards the lakeshore. The one synoptic snow event looks
to be late Tuesday night into Wednesday as a cold front sags south
through the Great Lakes.
Bottom line...winter will remain in full swing through the long term
with cold air and persistent light lake effect snows.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 652 PM EST Thu Dec 28 2017
This is not an easy forecast tonight as there is a rather intense
snow band just off shore of MKG and the question is does it come
inland and impact MKG or does it mostly stay just off shore this
evening and when it finally does come on shore it will have
weakened considerably (around 06z)? I went with the later version
of this.
Elsewhere and otherwise, we have a weak upper air system passing
over the southern 1/3 of Lower Michigan this evening and that
system is east of the area by 09z. That is when the system snow
should end. However we do have westerly winds with air cold enough
and moist enough for lake effect snow showers. So, I timed the
system snow through the I-94 TAF sites this evening and brought
the lake enhanced snow showers in by morning. For the most part
the snow showers during the daylight hours of Friday will be very
light. Another system comes in Friday evening bringing IFR
CIGS/VSBY by 21z or so.
&&
.MARINE...
Issued at 324 PM EST Thu Dec 28 2017
No changes to the current marine headlines. South winds ahead of the
next short wave will boost winds above 20 knots tonight and wave
will build to 3 to 6 feet.
&&
.HYDROLOGY...
Issued at 1029 AM EST Thu Dec 28 2017
Rivers are ice covered and fluctuations in river levels are being
reported. A river advisory continues at Smyrna on the Flat River,
where an ice jam is thought to have formed downriver of the site. No
flooding is expected. Temperatures will remain below 20 degrees for
at least the next week, so little change should occur in the short
term.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Winter Weather Advisory until noon EST Friday for MIZ038-044-056.
Winter Storm Warning until noon EST Friday for MIZ037-043-050.
LM...Small Craft Advisory until 7 AM EST Saturday for LMZ844>849.
&&
$$
UPDATE...WDM
SYNOPSIS...04
SHORT TERM...04
LONG TERM...Duke
AVIATION...WDM
HYDROLOGY...63
MARINE...04
Area Forecast Discussion
National Weather Service Northern Indiana
801 PM EST Thu Dec 28 2017
.SYNOPSIS...
Issued at 757 PM EST Thu Dec 28 2017
Light snow will persist early tonight and create slick spots on
roadways. Light snow accumulations of an inch or less are
expected with the greater accumulations closer to an inch across
far northern Indiana, far northwest Ohio, and southern Lower
Michigan. Localized greater accumulations are also possible
through Saturday morning closer to Lake Michigan across southwest
Lower Michigan where some lake effect snow showers are expected.
The next system will bring additional snow accumulations of 1 to
3 inches to the area late Friday afternoon through Friday evening,
with locally higher amounts once again associated with lake
effect snow showers. Arctic air will be reinforced behind the
Friday night system, with bitterly cold conditions this weekend
into the early next week. Lake effect snow showers will be likely
through much of the weekend into early next week.
&&
.UPDATE...
Issued at 756 PM EST Thu Dec 28 2017
Update to greatly increase pop for measurable per
observations/latest HRRR signals. Quick exit after midnight, save
for lingering lake effect/enhancement. Increase in qpf countered
by lowered slr per small/fine flake size/needles with deep layer
of supersaturation above shallow/3kft dgz...leaning to wetter
observed slr. Cold surface/road temps to lend lessened
effectiveness of winter road treatments.
&&
.SHORT TERM...(This Evening through Friday)
Issued at 340 PM EST Thu Dec 28 2017
Light snow overspreading much of the forecast area this evening, and
another round of accumulating snow for later Friday
afternoon/evening will continue to be the primary forecast
challenges for the short term.
A weak warm advection pattern continues across the area this
afternoon with gradually moistening low levels. Earlier 12Z RAOB
data from KILX depicted a fairly dry low level layer around 5k
feet, and much of initial lift ahead of the stronger forcing for
this evening has been spent on moistening these low levels. Should
see uptick in isentropic forcing and upper level forcing in the
23Z-03Z timeframe as eastward progression of fairly strong
upstream vort max across northern Iowa allows zone of stronger
isentropic lift to overspread the southern Great Lakes. The
duration of deeper moisture profiles appears to be fairly limited
to a 4 to 6 hour window this evening, and still expecting most of
the light snow accumulation in the 23Z-05Z timeframe. The
exception to this would be across southwest Lower Michigan where
westerly flow behind this system should add some lake effect snow
accumulation to Berrien/Cass counties. Still expecting snow
accumulations to be an inch or less for most locations with the
exception of lake effect areas where storm total amounts in the 1
to 3, localized 4 inch category appear more likely. Will hold off
on winter weather advisory headlines at this time, and indicate
potential impacts in SPS late this afternoon.
Synoptic snows will diminish late evening/overnight with attention
then turning to next highly sheared fast moving short wave working
across the Pacific Northwest this afternoon. This wave will have
fairly strong low/mid level downstream baroclinicity to work with,
and models continue to depict weak to moderate axis of low-mid level
fgen forcing affecting approximately southern two thirds of the
forecast area late Friday afternoon into Friday evening. One
difference with this system in comparison to the one this evening,
is that more favorable moisture profiles should be in closer
proximity to the area. Substantial low/mid level portion of profiles
will be in DGZ with favorable overlay with strongest forcing.
Inspection of mid level instability profiles does suggest fairly
stable conditions in mid levels however, which could hinder higher
end amounts. A swath of 1 to 3 inch snowfall appears likely from
northwest to southeast across especially southwest half of the area
late Friday afternoon into Friday evening before strongest forcing
quickly translates eastward. Another arctic intrusion behind this
system should keep lake effect snow showers going across southwest
Lower Michigan into Saturday morning, and winter weather advisory
headlines may be needed for these areas that experience the combo
synoptic/lake effect portions of this system late Friday afternoon
into Saturday morning.
In terms of temperatures, WAA this afternoon/evening and abundant
cloud cover will allow for significant moderation in temps compared
to previous few nights, with highs again by Friday afternoon back
into the mid-upper teens.
&&
.LONG TERM...(Friday Night through Thursday)
Issued at 340 PM EST Thu Dec 28 2017
Lake effect snow showers should be ongoing early Saturday, with
veering winds resulting in increasing lake effect snow chances
across favored areas in far northern Indiana. Forecast soundings do
depict rising inversion heights to around 5000 feet Saturday
morning, although deeper mid level saturation should be lost by mid
morning. As mentioned in short term discussion, may eventually
need a winter weather advisory to cover this Friday evening-
Saturday period for ongoing lake effect snow showers. Temperatures
not likely to have any recovery on Saturday due to arctic
intrusion with temps steady in upper single digits to the lower
teens.
Lake effect potential will need to be watched closely by Saturday
night through the early parts of next week with favorable north-
northwest trajectories becoming established, and lake-700 mb delta
T`s approaching 30 degrees. Lake aggregate troughing should
sharpen again by Saturday night, and guidances does indicate
better potential of deeper mid level saturation developing again
by later Saturday night/early Sunday as upper vort lobe across
western Great Lakes drops southward. Still not a good deal of
confidence in the specifics regarding timing/instability
magnitudes/wind fields as this setup could favor mesolow
generation over the open waters that will have a large impact on
placement/duration/intensity of lake effect bands. While guidance
has been consistent in general idea of mesolow formation over open
waters working southward down Lake Michigan, specifics still
difficult to resolve at this forecast distance. Potential does
exist for some significant lake effect snow Saturday night-Monday
given magnitude of air mass overspreading area and potential of
favorable trajectories.
Outside of lake effect snow potential, bitterly cold wind chills
will be in store late weekend/early next week. Wind chill advisories
will likely be needed for at least portions of this multi-day
period. Minor moderation appears possibly by middle of next week,
but synoptic setup will be prone to additional arctic intrusions
toward end of this forecast valid period.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday Evening)
Issued at 636 PM EST Thu Dec 28 2017
Warm, moist advection has allowed for snow during the overnight
hours tonight as a low pressure system passes by to the north.
This will bring snow to the region along with MVFR CIGs and IFR
VISBY especially with the smaller flakes and the low DGZ.
Attention then turns to another system that comes in later
tomorrow. There is a possibility that conditions stay MVFR most of
the day at SBN with some lake effect clouds forming, but FWA may
have a period around midday where flight conditions increase back
up to VFR, as dry air works its way in. As we get into the later
afternoon, conditions are expected to decrease back into MVFR as
the next wave provides more snow.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...Small Craft Advisory from 1 AM Friday to 7 AM EST Saturday for
LMZ043-046.
&&
$$
UPDATE...Murphy
SYNOPSIS...Murphy
SHORT TERM...Marsili
LONG TERM...Marsili
AVIATION...Roller
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Area Forecast Discussion
National Weather Service Lake Charles LA
945 PM CST Thu Dec 28 2017
.DISCUSSION...
Main changes to the grids/zones this evening was to nudge up temps
a degree or two as increasing cloud cover/nerly winds should limit
further cooling a little...this leads to readings just below
freezing as opposed to the upper 20s for the far nern zones
tonight. Elsewhere regional 88Ds show a few light returns along
the upper TX coast sw of Houston...last few HRRR runs have been
picking up on the possibility of very light showers/drizzle moving
newd into the forecast area later tonight, but confidence is
lacking at this time to insert such wording into the grids/zones
right now as most of this activity should remain over the coastal
waters.
Update out shortly.
25
&&
.PREV DISCUSSION... /issued 554 PM CST Thu Dec 28 2017/
DISCUSSION...
00Z TAFS
AVIATION...
Overcast skies tonight will remain generally MVFR with skies
gradually clearing by mid to late morning Friday. Mid to high
clouds are once again expected to build into the region Friday
night into Saturday.
High pressure centered over central Arkansas will keep winds
generally light out of the northeast tonight gradually shifting
out of the east Friday afternoon.
Jones
PREV DISCUSSION... /issued 345 PM CST Thu Dec 28 2017/
.Bitter Cold on the Way...
DISCUSSION...A long wave trough remains over most of the lower 48
today with a Canadian air mass coating most areas east of the
Rockies. The surface ridge is centered over the Great Lakes and
stretches to the gulf coast.
Friday and Saturday the ridge currently centered over the Great
Lakes will slip into the Atlantic which will produce a brief warm
up locally as the flow becomes east to southeast. Moisture will
increase with the southeast flow by Saturday returning drizzle and
showers. Also during this time another ridge will drop out of
Canada and southeast across the plains.
The strong cold front will arrive early during New Year`s Eve with
cooling ongoing through the day. Enough lift will linger behind
the front to keep light rain or drizzle lingering through New
Year`s Eve through early New Year`s Day, however while temps are
falling below freezing conditions will be drying. There may be a
very small window across the lakes and CenLA for ZR or IP, however
this will be very short lived. The bigger threat will be the cold
that will linger through the week.
The coldest stretch of weather this area has seen in a few years
will occur next week as teens and 20s will be common each morning.
Wind chills of the single digits to the 20s will also occur. A
couple of reinforcing fronts will also pass through the area
with one likely Tue and one Wed/Thu. Operational models have
trended drier with the short wave and front Monday Night/Tuesday,
however there may by a slim window for some precip to work into
Acadiana.
MARINE...High pressure will move across the region through
Saturday keeping a moderate east to southeast flow in place,
however a very strong front will move through during New Year`s
Eve. Strong offshore wins and low water conditions can be expected
early next week.
&&
.PRELIMINARY POINT TEMPS/POPS...
AEX 30 49 38 52 / 0 10 10 30
LCH 36 52 44 59 / 0 10 20 30
LFT 36 52 43 56 / 0 10 10 30
BPT 38 53 45 61 / 10 10 20 30
&&
.LCH WATCHES/WARNINGS/ADVISORIES...
LA...None.
TX...None.
GM...None.
&&
$$
PUBLIC...04
Area Forecast Discussion
National Weather Service Lubbock TX
1003 PM CST Thu Dec 28 2017
.UPDATE...
The fog that has rolled into Lubbock and Plainview has been dense
at times. Given this we have decided to hoist a freezing fog
advisory for much of the Caprock through the rest of the night.
The low clouds and freezing fog will continue to advance westward
over much of the remainder of the South Plains before winds begin to
veer to the south and southwest around and after 08Z. Our far
northwestern zones around Friona may avoid the fog as winds veer
there before the higher moisture levels can arrive. Otherwise,
much of the remainder of the locations on the Caprock will should
see the fog. There could also be some fog/freezing fog in the
Rolling Plains, though with low clouds already in place and
minimal moisture advection, widespread dense fog is less certain
there. Any fog should quickly diminish by mid to late Friday
morning as drier downslope winds spread out of New Mexico. Until
then, the freezing fog advisory is in effect for all of our
counties on the Caprock, aside from Parmer County, through 10 am
Friday.
&&
.PREV DISCUSSION... /issued 757 PM CST Thu Dec 28 2017/
UPDATE...
Minor adjustments were made to the temperature and dewpoint grids
through the remainder of the night, primarily to account for
current observations and trends. Where skies are clear
temperatures are rapidly falling and we would not be surprised to
see a few teens across the northwestern zones later tonight.
Further east, the low clouds that persisted over the eastern
Rolling Plains during the day were now advancing westward. As this
cool and moist airmass spreads back up onto the Caprock
widespread low clouds and freezing fog will quickly follow. This
was well captured by the ongoing forecast though we did add a
patchy freezing fog mention over the lower elevations too where
slight cooling and weak moisture advection may eek out some fog
development too. Given that fog density is often quite fickle, we
are holding off on any headlines at this time, though if the HRRR,
RAP and NAM are correct a freezing fog advisory may be needed for
much of the CWA. We will watch trends closely and hoist a
freezing fog advisory if it becomes warranted.
PREV DISCUSSION... /issued 532 PM CST Thu Dec 28 2017/
AVIATION...
VFR conditions at KLBB and KPVW with MVFR at KCDS at the start of
this TAF cycle. Low clouds will redevelop and push west over the
KPVW and KLBB terminals after sunset tonight and will rapidly drop
back into LIFR range with VLIFR possible in the early morning
hours. Confidence is high on this occurrence with a bit lower
confidence on when the transition will actually take place.
Temperatures will fall below freezing around midnight local time
so periods of freezing fog/drizzle will be possible through Friday
morning. Similar to today, low clouds will remain in place
through late morning with gradual improvement to VFR conditions
before mid-day Friday. West wind will increase through the day as
well at KLBB and KPVW helping to clear out skies fairly fast.
Jordan
PREV DISCUSSION... /issued 345 PM CST Thu Dec 28 2017/
DISCUSSION...
3 pm temperatures ranged from near 70 in the southwest South
Plains to only in the 30s out in the Low Rolling Plains. The low
stratus bank has retreated off the Caprock, but the latest
satellite imagery suggests that it`s eastward progress is slowing
and we expect it to soon stall, then begin to move back west this
evening. Forecast soundings suggest the threat of freezing fog
developing overnight across much of the Caprock, and perhaps some
light freezing drizzle across the far Southern Texas Panhandle
into the northern Rolling Plains.
Friday, the shallow moisture should be scoured even more readily
than today as deep-layer westerly flow increases in conjunction
with a passing shortwave. Very warm temperatures should spread
farther east, although there is still a bit of uncertainty just how
warm the lowest elevations will get, with the deeper inversion to
overcome. For now we are looking at highs mainly in the 60s on
the Caprock and 50s off. The warm and dry conditions will bring an
elevated fire danger to the western South Plains and far southwest
Texas Panhandle.
Meanwhile, a series of shortwaves rotating through broad cyclonic
flow over eastern CA and north-central US will unleash Arctic air
currently residing in northern portions of the Canadian provinces.
The leading edge of the cold air is still on track to move into
our area Saturday. With the really frigid air lagging behind to
the north, there is some question regarding temperatures
Saturday, as the shallow cold air could tend to erode across the
higher terrain out west. And we could see some light freezing
drizzle Saturday off the Caprock, but with meager amounts of
moisture in this airmass any precip will be very light.
The really cold air will come in Sunday. With just some weak
shortwave energy passing aloft, this combination could gin up
some light wintry precip., again mainly off the Caprock, but at
this time the precip. does not appear to be significant (aside
from perhaps creating some icy roadways). The main story may be
the period of bitterly cold temperatures starting Sunday. Highs
Sunday and Monday should mainly in the 20s, with lows Monday night
and Tuesday night primarily in the single digits to low teens.
And we would be surprised to see some near zero temps Monday night
across our northwest counties. Wind chill values New Years Eve
could be below zero and possibly even below -5 degrees in the
north. Wind Chill highlights are certainly a possibility during
this period.
Moderation in temperatures will be a slow slog through midweek as
continued north-northwest flow across the nation`s midsection
keeps supplying cold air, but our temps should gradually recover
as the cold airmass modifies/retreats northeast.
&&
.LUB WATCHES/WARNINGS/ADVISORIES...
Freezing Fog Advisory until 10 AM CST Friday for TXZ022>024-
027>030-033>036-039>042.
&&
$$
23/14
Area Forecast Discussion
National Weather Service Miami FL
811 PM EST Thu Dec 28 2017
.UPDATE...
Satellite imagery suggests that a surface low has formed
about 70 miles east of Cocoa Beach. This is the same surface low
that the models show developing early Friday and then moving ENE
out to sea in the Atlantic. However, the HRRR indicates that the
surface low will move slowly SSE through 06Z before slowing down.
After 12Z, it should begin moving out to sea. A broken line of
showers extends as a tail from the low southwestward to the coast
of Palm Beach County. Showers also extend to southern Collier and
Mainland Monroe. This shower activity should migrate southward
over the next few hours. A few showers may linger around South
Florida until a few hours after midnight.
Patchy dense fog is likely across portions of Glades, Hendry,
Collier, Palm Beach and inland Broward Counties between 09Z-14Z.
Elsewhere, the frontal boundary over Central Florida will slither
slowly southward during the next day or so, perhaps spreading
some cloud cover, but not rainfall, over the northernmost
portions of South Florida later on Friday. Once the weak front
passes, winds will become more northerly, allowing slightly
cooler air to filter into South Florida.
&&
.PREV DISCUSSION... /issued 642 PM EST Thu Dec 28 2017/
AVIATION...
The winds will be light and variable tonight over all of the taf
sites. There could be some showers around the KPBI taf site
through 02Z before going dry. Therefore, KPBI will have VCSH until
02Z, then dry conditions after 02Z tonight With VFR conditions.
Rest of the taf sites will remain dry tonight along with VFR
conditions.
AVIATION...54/BNB
PREV DISCUSSION... /issued 436 PM EST Thu Dec 28 2017/
DISCUSSION...
Tonight-Sunday: A lingering frontal trough over central
and northern Florida along with high pressure over the eastern U.S.
will keep NE winds and some moisture over South Florida through
tonight. Isolated showers will continue to be possible, especially
over the eastern half of South Florida, through this evening. On
Friday, a surface low strengthens east of northern Florida and moves
out to sea in the Atlantic. As the low leaves, a surface ridge over
the northern Gulf of Mexico noses its way into Florida beginning
Friday. The surface ridge will continue to have enough influence on
our weather, that it should keep South Florida dry through the
weekend. Since we will be on the east side of that surface ridge,
winds will be more northerly Friday through Sunday, which will
filter in slightly cooler air. Expect temperatures Friday night
through Sunday morning to be a few degrees cooler than they have
been during the last few days.
Sunday Night-Thursday: An unsettled weather pattern is forecast to
arrive in South Florida for the beginning of the New Year. Rain
chances start to increase Monday as a cold front heads toward
South Florida. The front should arrive in South Florida late on
Monday. The front moves through rather slowly, and moisture
lingers into Tuesday. To complicate matters, the GFS and ECMWF
now want to form a surface low along that same front over the
southeast Gulf of Mexico, which then moves near or over South
Florida mid-week. As a result, it could potentially be quite
rainy here through midweek. It is not looking quite as cold on
Tuesday into early Wednesday now, as what the models were showing
the past 2 days. However, after the low and rain finally get out
of here, models are beginning to hint at a large surge of arctic
air, that has at least some potential to make it down into Florida
for late next week. The models have been so inconsistent lately on
anything beyond 5 days. Our temperature forecast at day 7 is a
blend between the models and climatology.
MARINE...
Moderate NE winds will shift to N and then increase to 15-20 kts
on Friday for the Atlantic waters. These winds, combined with a
NNE swell of 3 to 4 feet with create hazardous seas for small
craft. Thus, a small craft advisory is in effect from 5AM Friday
to 7AM Saturday for the Atlantic waters. Seas of 6 to 8 feet are
expected Friday and Friday night. Seas will diminish on Saturday.
For the Gulf waters, waves will remain 1 to 2 feet through Sunday
night, with seas building late on New Year`s Day.
BEACH FORECAST...
The rip current risk will increase along the Atlantic beaches
Friday night into Saturday despite northerly winds, as large NNE
swells affect the coast.
AVIATION...
Few showers possible this afternoon east coast but probabilities
dont warrant mention in terminals. CIG restrictions have finally
lifted at KAPF, but expect MVFR/IFR CIGs to reappear later
tonight through Friday morning. Elsewhere, VFR conditions prevail.
NE wind 10 knots today, then calm tonight, then N around 10 KT on
Friday.
&&
.PRELIMINARY POINT TEMPS/POPS...
West Palm Beach 64 78 63 78 / 20 0 10 10
Fort Lauderdale 66 79 63 78 / 30 0 10 10
Miami 67 81 64 79 / 20 0 0 0
Naples 64 77 59 77 / 0 0 0 0
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...Small Craft Advisory from 5 AM Friday to 7 AM EST Saturday for
AMZ650-651-670-671.
GM...None.
&&
UPDATE...98/ABH
DISCUSSION...98/ABH
MARINE...98/ABH
AVIATION...54/BNB
BEACH FORECAST...98/ABH
Area Forecast Discussion
National Weather Service Newport/Morehead City NC
924 PM EST Thu Dec 28 2017
.SYNOPSIS...
Arctic high pressure will continue to extend into our region
through tonight. Low pressure is forecast to develop well south
of the area late tonight and Friday and move northeast of the
region over the weekend as very cold air spreads across the area
in its wake. Another low pressure system will lift northeast
offshore of the coast early next week.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
As of 925 PM Thursday...Temperatures continue to fall as Arctic
high builds east toward the Carolinas. Have once again lowered
temperatures a degree or two based on current readings. Expect
upper teens inland to low/mid 20s coast, with upper 20s Outer
Banks. Based on the 00Z MHX sounding, the low-levels remain
very dry, and despite some support for very light precipitation
from some of the high-resolution models such as the HRRR and 3
KM NAM, feel that it will be difficult to overcome the dry sub-
cloud layer and will keep the overnight and early morning
period dry. Expect winds to gradually subside after midnight as
axis of surface high pressure builds east of the central and
eastern Carolinas.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/...
As of 330 PM Thurs... The Arctic high pressure will remain in
place, but weaken due to an airmass modification and a low
pressure system to the south of the area. This will lead for low
level thicknesses to increase and causing temperatures to
recover back into the low/mid 40s.
&&
.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
As of 230 am Thu...Deep cyclonic flow expected to dominate
during period with southern stream moisture suppressed to south,
and reinforcing shots of cold air for Sat-Sun and again Mon-
Tue.
Precip chances through the extended a bit problematic. 00Z GFS
is dry through the entire period. The 00Z ECMWF brushes south
coast and OBX with light snow late Sunday night through midday
Monday with a surface low passing by to the south. National
guidance is higher with slight chance PoPs northwest and chance
along the south coast and southern OBX. Due to uncertainty, for
now will take a middle course and lean toward the ECMWF
solution. Large differences Wed with the ECMWF passing a strong
low just off the coast while the GFS has a weaker low far to the
southeast. With such large differences that far out in time, will
not include PoPs at this point.
Lows mainly 25-35 for Friday night, lower/mid 20s Sat night, then
colder with upper teens inland to 25-30 coast rest of period.
Highs in mid/upper 40s for Saturday and then mainly in 30s rest
of period, with guidance generally indicating temps barely
above freezing for inland sections Sun-Tue. Slightly warmer Wed,
with mid 30s west to lower/mid 40s south coast and Outer Banks.
&&
.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
Short Term /through 00Z Saturday/...
As of 645 PM Thursday...VFR conditions expected to prevail
through the next 24 hours with mostly mid/high level cloudiness
anticipated. Gusty N/NE winds should subside after midnight as
axis of high pressure ridge build east over the central and
eastern Carolinas.
Long Term /Fri through Mon/...
As of 230 am Thu...VFR/dry through the period. Surface winds NW
5 knots Fri, W 5 knots Sat, N 10 knots Sun and N 10-15 kt Mon.
&&
.MARINE...
Short Term /Through Tonight/...
As of 925 PM Thursday...Winds have subsided over the Sounds and
southern waters, with northerly winds at 15-20 knots. Gusts to
around 25 knots and 6-foot seas continue over the waters north
of Ocracoke and have extended the SCA there until 09Z Friday
morning. As the axis of Arctic high pressure builds east and
settles over the central and eastern Carolinas overnight, the
winds and seas should subside toward morning. Seas will subside
3 to 5 ft by daybreak.
Friday...N winds 10-15 knots in the morning, becoming NW 10-20
knots in the afternoon as low pressure sys deepens and causes
the gradient to tighten. Seas will remain mostly 3-4 ft.
Long Term /Fri through Mon/...
As of 230 am Thu...Winds mostly north to northwest through the
period. Wind speeds generally 15 knots or less for Friday into
Saturday, then reinforcing shot of arctic air likely to produce
another period of 15-25 knot winds Saturday night into Monday.
Wave guidance indicating seas mainly 2-4 feet Friday into Saturday.
Increasing winds will then build heights to 4-8 feet Sat night
into Monday north of Ocracoke, with 3-5 feet south.
&&
.MHX WATCHES/WARNINGS/ADVISORIES...
NC...None.
MARINE...Small Craft Advisory until 5 AM EST Friday for AMZ150-152-154.
&&
$$
SYNOPSIS...RF/BM
NEAR TERM...CTC
SHORT TERM...BM
LONG TERM...HSA
AVIATION...RF/CTC/BM
MARINE...CTC/BM
Area Forecast Discussion
National Weather Service Melbourne FL
806 PM EST Thu Dec 28 2017
.DISCUSSION...
Current-Overnight...A weak quasi-stationary frontal boundary remains
entrenched from near Melbourne west-southwest to south of Tampa this
evening. A weak, developing surface low well off of the Cape along
with fairly strong high pressure along the eastern seaboard will
provide enough influence to push the aforementioned surface trough
southward to near the Treasure Coast/Lake Okeechobee region by
around daybreak Fri morning.
On the backside of the front thick low stratus clouds with 500-
1000ft ceilings. The main forecast concerns overnight revolve around
how far south these low clouds will venture, as well as any patchy,
locally dense fog potential that may exist, especially south of
Orlando. The local HRRR and LAMP guidance continue to focus from
near central Osceola/central Brevard southward for the edge of some
potentially thicker fog extending through the remainder of our
coverage warning area; Okeechobee/Martin counties. Will update the
zones forecast for addition of patchy fog from Osceola-south Brevard
southward overnight into early Fri morning. Otherwise, MAV MOS
guidance continues way too high on precipitation potential. Will
hold onto an isolated sprinkle or light shower along the east coast
until 06Z/1AM, though this continues to be very generous on the part
of the forecaster.
The abundance of low clouds, especially northward, will keep most
areas in the M-U50s overnight, except some L60s possible along the
immediate east coast from south Brevard thru Martin County. Wind
component will remain from out of the NNW-NNE with speeds 5-10 mph.
&&
.AVIATION...Low CIGs 500-1000 ft from near KMLB northward this
evening. Expect this IFR group to prevail thru the night and early
Fri morning. This area may make it further south to across the
Treasure Coast overnight as a weak frontal boundary sags slowly
southward. Recent local short-term model guidance suggests some
visibility concerns as well southward from KISM-KMCO-KTIX late in
the night. Expect CIGs/VSBYs to improve from mid-morning on, though
IFR-MVFR CIGs may prove a nuisance at some sites into the afternoon.
&&
.MARINE...Overnight-Fri...Poor to hazardous boating conditions
increasing (from north to south) across the local coastal waters
this evening and overnight, and through the day on Fri. Some higher
northerly winds will overspread the area on Fri, though seas begin
to build out ahead of this new wind surge tonight, due to an
increasing swell. The stronger winds will initially be delayed due
to a weak low pressure system well off of the Cape, that will keep
the local pressure gradient disturbed. ISOLD-SCT light shower
activity will be possible over the area, especially the Gulf Stream.
Seas are forecast to build (by daybreak) up to 9 ft, well offshore,
north of the Cape, and generally 5-7 ft most everywhere else.
Small craft advisories begin at 00Z/7PM for the offshore waters
(Flagler Beach-Jupiter Inlet), as well as for the near shore Volusia
coastal waters. By 09Z/4AM, the SCA gets expanded areawide and
remaining thru the day on Fri.
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...Small Craft Advisory from 7 PM this evening to 10 PM EST Friday
for Flagler Beach to Volusia-Brevard County Line 0-20 nm.
Small Craft Advisory from 7 PM this evening to 5 AM EST Saturday
for Flagler Beach to Volusia-Brevard County Line 20-60 nm-
Sebastian Inlet to Jupiter Inlet 20-60 nm-Volusia-Brevard County
Line to Sebastian Inlet 20-60 nm.
Small Craft Advisory from 4 AM to 10 PM EST Friday for Sebastian
Inlet to Jupiter Inlet 0-20 nm-Volusia-Brevard County Line to
Sebastian Inlet 0-20 nm.
&&
$$
Sedlock/Volkmer
Area Forecast Discussion
National Weather Service Omaha/Valley NE
603 PM CST Thu Dec 28 2017
.SHORT TERM...(Tonight through Monday)
Issued at 316 PM CST Thu Dec 28 2017
Colder temperatures this weekend is the main weather story,
however we will see a couple chances for light snow over the next
couple of days as well.
Upper level flow pattern will remain wholly unchanged for the
central part of the country through Sunday, as jet stream rounds the
top of broad high pressure in the eastern Pacific then dives
southeast into a broad trough covering the east half of the CONUS.
Models show two distinct shortwaves riding through the flow from
southern British Columbia into the Plains, one later tonight into
Friday, and the second affecting our area Saturday into Saturday
night. Each will bring a chance for light snow and a reinforcement
of colder air in their wake.
Temperatures warmed up nicely this afternoon with most spots seeing
highs in the 20s. Could see some 20s again Friday in our south, but
cool east to northeast winds and cloud cover associated with
shortwave will keep a lid on highs for the most part. Then with
cooler air to follow, Friday night lows should again drop below zero
most of eastern Nebraska and western Iowa, especially in the north
where a new layer of snow is possible. Some mid and high level cloud
cover could keep lows a bit warmer, but airmass is cooling and a
north wind will provide cold advection. Not looking for much of a
warmup on Saturday with thickening cloud cover and continued oozing
of arctic air south. Then more reinforcing cold advection follows
second shortwave for Saturday night through Sunday night when 1054mb
arctic high pressure begins to settle into the Mid Missouri River
Valley region. Haven`t seen high pressure of that magnitude in a
while. So even with some sunshine Sunday, can`t see highs
eclipsing zero. GFS indicates center of high pressure will be over
Omaha at 12Z Monday. And given airmass combined with snowcover
and decreasing winds, strong radiational cooling regime will
likely allow lows to drop to colder than 20 below for much of our
CWA.
Wind chills are also a concern for the weekend. Even a light breeze
with expected temperatures will likely mean sub-30-below wind chills
for part of the day Sunday and for sure Sunday night into Monday
morning. We will likely see wind chill advisories needed perhaps on
Saturday, then advisories and warnings for the Sunday and Monday
timeframe.
As far as potential precipitation, the first shortwave of
consequence was noted on water vapor imagery and RAP analysis moving
onto the southern coast of British Columbia at early afternoon.
Strong 150kt upper level jet will usher it into the central and
northern Plains later tonight and Friday. Initial band of
associated forcing will arrive this evening when light snow could
develop over northeast Nebraska. Then a more pronounced area of
lift moves through South Dakota into northern Iowa overnight and
Friday morning. Model QPF and pressure deficit forecasts suggest
main band of snow will fall to the north and northeast of our CWA,
with southern edge of measurable snow likely north of an Albion
to Omaha and Red Oak line.
Precipitation should be moving into central Iowa by Friday
afternoon. Then another strong upper level jet segment is advertised
by GFS knifing through North Dakota into Minnesota Friday night. No
major affect here but right entrance region of that jet could spark
some light snow in our northern counties once again. Then second
shortwave will begin to affect our area by Saturday afternoon, and
again accompanied by strong upper jet streak. This shortwave looks
to take a little more southerly track across eastern Nebraska and
western Iowa, and subsequent forcing fields suggest more widespread
but still light snow of an inch or two. Associated precipitation
should be moving east by Sunday morning, with the much colder air to
follow.
.LONG TERM...(Monday night through Thursday)
Issued at 316 PM CST Thu Dec 28 2017
Still not much change in sight as far as temperatures are concerned
for next week. Overall pattern does shift after Saturday shortwave
passes by, going from northwest flow in the Plains to northerly.
This does not bode well for warming in much of the central CONUS.
Another cold night is expected Monday night with double-digit
negative lows are forecast. Then airmass does show some sign of
moderation as GFS 850 temps warm from the minus 20-25C range into
the minus teens. However this will only translate to highs in the
teens on average Tuesday through Thursday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 517 PM CST Thu Dec 28 2017
Radar mosaic was showing an area of -SN, associated with an upper
level disturbance, expanding SEWD out of WRN SD. Current trends
suggest the -SN will skirt very close just to the NE of KOFK and
KOMA beginning shortly after midnight into Friday morning. Thus
have included PROB30 groups to reflect this. Otherwise, MVFR cigs
will likely prevail through Friday afternoon at all terminals.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...None.
IA...None.
&&
$$
SHORT TERM...Dergan
LONG TERM...Dergan
AVIATION...DEE
Area Forecast Discussion
National Weather Service Paducah KY
527 PM CST Thu Dec 28 2017
.UPDATE...
Issued at 238 PM CST Thu Dec 28 2017
We have adjusted sky grids for now through late evening. The RAP
model 900-850mb layer RH and wind trajectory suggest the clouds
will continue to drift east. How much they hold together on the
east edge is somewhat up in the air. But the RAP is fairly
aggressive with the eastward push. Currently the line runs from
KFWC to KMWA to KPOF.
&&
.SHORT TERM...(Tonight through Saturday night)
Issued at 110 PM CST Thu Dec 28 2017
Dry weather in the short term. NW flow aloft will continue. At the
surface, high pressure will weaken and move east. This will allow
winds to veer around toward southerly into Friday ahead of an
approaching front that will bring a reinforcing shot of cold air
Friday night into the weekend. Ahead of the front on Friday, most
areas will climb above freezing by afternoon. The front is
forecast to move through during the late day hours. In the wake of
the front, colder air returns for Saturday, with highs in the
lower 20s I-64 to around 30 west KY, parts of SEMO. Just some
clouds from time to time.
.LONG TERM...(Sunday through Thursday)
Issued at 110 PM CST Thu Dec 28 2017
The main concern remains the cold. The broad deep mid level trof
pattern along and east of the Rockies will persist. New Year`s Eve
and New Year`s day will be bitterly cold as the 1045+ high settles
south through Monday night. New finalized forecast grids show we
will have wind chills colder than -10F New Year`s Eve night into
New Year`s Day morning. We trended slightly colder with temps
overall, given a strong deviation from the norm is usually not
handled well by MOS. Having said that, the raw model output is
likely too cold given no snow cover. No end to the cold in sight.
Just a slight rise in temps mid week, followed by another cold
outbreak late next week. The one light snow chance we have to
monitor, appears to be sometime from midday Wednesday to midnight
Wednesday night. A signal is more persistent across the
Evansville Tri State area for light snow chances. Have not
included in the forecast yet. But something to watch.
&&
.AVIATION...
Issued at 527 PM CST Thu Dec 28 2017
Expansive stratus deck moving eastward across the WFO PAH TAF
sites at this time. Utilized the RAP guidance to provide an
estimate of the duration of these clouds across the area. After
08z-11z, return ceilings to VFR conditions for the rest of the
forecast period.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...None.
MO...None.
IN...None.
KY...None.
&&
$$
AVIATION...Smith
Area Forecast Discussion
National Weather Service Topeka KS
505 PM CST Thu Dec 28 2017
...AVIATION UPDATE...
.SHORT TERM...(This evening through Friday)
Issued at 240 PM CST Thu Dec 28 2017
Clouds have been a little slow clearing the area today with some
dissipation seen across central Kansas early this afternoon. This
clearing will continue through the afternoon with a brief period of
mostly clear skies forecast before clouds move back into the area
later tonight. Observations indicate a weak surface front located
near the Kansas/Nebraska boarder which will move through the area
late afternoon and act to shift winds from the north for the
overnight hours. Light northerly winds along with low temperatures
in the teens tonight will bring wind chills into the single digits
by Friday morning.
On Friday, a trough located in the northern Great Lakes region will
act to push a cold front through the area Friday night. Ahead of
this feature, expect one more day of temperatures in the 30s,
although there may be a bit more wind in east central Kansas during
the afternoon making wind chills a bit colder in the afternoon.
Isentropic upglide will aid in more cloud development by tomorrow
morning and clouds are expected to stick around through the period.
The front begins to make its way through northeastern Kansas by late
afternoon which will act to drop temperatures significantly behind
this feature.
.LONG TERM...(Friday night through Thursday)
Issued at 240 PM CST Thu Dec 28 2017
Overall the main feature of this extended period will be the
severely cold temperatures this weekend and through Tuesday morning.
A cold front makes its way through the area Friday night with
noticeably colder temperatures behind it, with lows Saturday morning
reaching (once again) the single digits. Not much of a warm up
Saturday as skies stay mainly mostly cloudy with maybe only a warm
up of 3 or 4 degrees across the area. Persistent cold air advection
will bring low temperatures Sunday morning to a chilling -6 to +1
degrees. Northerly winds will bring the wind chills this morning
from -12 to -20.
Unfortunately, temperatures only continue to fall from here with New
Year`s Eve highs in the single digits. The coldest temperatures of
the period are expected to occur early Monday morning with
temperatures in the negatives up to -15 near the KS/NE boarder.
Dangerously cold wind chills will be seen on this morning ranging
from -20 in east central Kansas to -30 in northern Kansas. On New
Year`s Day, highs will be very similar to the previous day in the
single digits. By Monday evening, a 1050mb high pressure moves
overhead or just east of the area keeping cold temperatures in place
for that night. Tuesday morning, lows will be in the negatives
ranging from -1 to -7 across the area with more wind chills down to -
20 degrees in northern Kansas.
With this passing high pressure, winds finally shift from the south
aiding with a slight warm up into the 20s which looks to last
through the end of the period.
There are some very small chances for light snow Tuesday, although
the Canadian looks to be the only model picking up on this chance so
confidence is not high right now.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday)
Issued at 505 PM CST Thu Dec 28 2017
VFR conditions should prevail for the evening and much of the
overnight hours. However think MVFR CIGS will move back in after
12Z as models increase low level winds from the south southwest.
These winds should advect the low clouds over west TX and
southwest OK back into the area as the RAP and NAM suggest. Once
these clouds move in, it may be difficult to scatter them out with
forecast soundings maintaining a steep low level inversion through
the afternoon.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Heller
LONG TERM...Heller
AVIATION...Wolters
Area Forecast Discussion
National Weather Service Tulsa OK
912 PM CST Thu Dec 28 2017
.DISCUSSION...
The cloud edge across northeast Oklahoma eroded south a bit
in the past couple of hours. That process should continue
a couple of more hours, putting the edge of the clouds in the
I-44 corridor. After about 1am the clouds should expand
back north. Additionally, holes should open up in northwest
Arkansas and far southeast Oklahoma. All of this of course will
cause local ups and downs in the temps overnight. On the
average the low temperature forecast looks on track.
Radar and mPing show light precip developed this evening in
north Texas from a moist layer between 850mb and 925mb. This
precip seems loosely tied to weak isentropic upglide on the
280 K surface. Winds at 925mb are expected to become southeasterly
overnight which should keep this precip pattern away from our
southeast Oklahoma Counties. So we are not adding any precip
at this time for tonight, but we will need to watch how the
precip evolves.
&&
.PREV DISCUSSION... /Issued 611 PM CST Thu Dec 28 2017/
AVIATION...
CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM/KROG.
Animated satellite imagery indicates widespread low clouds across ern
OK and wrn AR. Areas where clouds eroded this afternoon are already
slowly filling back in. As is usually the case with shallow moist
layers trapped beneath temperature inversions in the winter,
anticipating behavior of stratus layer will continue to be
challenging. For now, we have trended 00z TAFs toward HRRR and NAM
models, which indicate higher chances of maintaining low VFR
ceilings. Ceilings may be a little more prevalent Friday, and may
begin to lower into MVFR category. Strong cold front passage expected
just beyond the end of this forecast period.
PREV DISCUSSION... /Issued 310 PM CST Thu Dec 28 2017/
DISCUSSION...
Main forecast concern continues to be winter weather potential
Saturday through Sunday in conjunction with very cold temperatures
associated with the approaching Arctic airmass.
Cloud deck currently atop eastern Oklahoma and western Arkansas
has slowly been eroding this afternoon in most areas except far
southeast Oklahoma. Some cloudiness may linger through the night
across the region, but coverage should eventually be more partly
cloudy than at present. As a result, temperatures may be closer to
the cooler side of guidance. With continued southerly winds and
less cloud cover, temperatures tomorrow will be much warmer than
the last few days, with highs closer to normal.
The initial cold front will move through the area Friday night and
into early Saturday, with the stronger push of cold and very dry
air slated for Saturday night and into Sunday. Available low level
moisture should be enough during the day Saturday to lead to some
drizzle or freezing drizzle, although some erosion of the low
level moisture from north to south should occur during the
afternoon. Any measurable precipitation with this system would
accompany the arrival of the stronger cold air push. Temperature
profiles support a transition from freezing drizzle to sleet and
snow once moisture in the dendritic growth zone increases. Any
amounts still appear to be a half inch or less at this point, but
the very cold temperatures could exacerbate the overall travel
impacts despite the light amounts.
Winds will stay up through Sunday night and into Monday, leading
to very cold wind chills to close out 2017 and open 2018. Wind
chills will be cold again Monday night/Tuesday morning, but lower
wind speeds will lead to higher values than the previous morning.
Another fast moving upper level wave will move through far
northeast Oklahoma and northwest Arkansas, with a quick burst of
snow possible Tuesday morning. Temperatures will be cold enough
that snow ratios should be higher than what we typically see here.
Right now, it looks like another half inch or so will be possible
with this system.
The well below normal temperatures will continue through the
remainder of the next work week.
&&
.TSA WATCHES/WARNINGS/ADVISORIES...
OK...None.
AR...None.
&&
$$
SHORT TERM...08