Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/27/17
Area Forecast Discussion
National Weather Service Wakefield VA
913 PM EST Tue Dec 26 2017
.SYNOPSIS...
A cold front will drop through the region tonight with weak low
pressure pushing off the Carolina coast Wednesday. Meanwhile,
arctic high pressure builds across the Eastern Great Lakes and
New England Wednesday and Thursday. Another weak low pressure
system develops off the Southeast coast Thursday night through
early Friday, before arctic high pressure returns for next
weekend into the new year.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
Latest MSAS has weak low pressure moving east along the Mason-
Dixon line with the trailing cold front extending sw ivof I81
corridor. Meanwhile, high pressure was located over nern NC with
another weak area of low pressure over the NC mts.
Closer to home, BKN-OVC AC deck aoa 12K ft has overspread the
region in advance of these weather features. Temps dropped quickly
after sunset but have since leveled off with the increase in
cloudiness. Waited to see the 00Z NAM, but it now agrees with
the high res models in keeping most if not all the AKQ forecast
area dry through 12Z. Any pcpn associated with the front remains
mostly aloft as the front crosses the area due to the dry low
levels. Any pcpn assctd with the developing coastal low remains
along and just south of the Albemarle sound through 12Z. Thus,
the only pcpn possible would be some very light snow/flurries
across srn Bertie NC cnty around sunrise, otw mstly cldy and
dry. Given the cloudiness, bumbed up mins a a degree or two.
Lows in the 20s.
PVC DSCN:
A dampening shortwave trough will push across the Ohio Valley
this evening, before sliding across the Carolinas on Wednesday.
This feature will interact with the aforementioned cold front,
spinning up a weak low/coastal front. 12z/26 NAM/CMC/ECMWF each
are a bit wetter with the overrunning moisture, with the GFS
lagging behind showing little or nothing. However, much of the
deep moisture and lift remains just to our SE. Our official QPF
has increased slightly over our SE sections, with precipitation
expected in the mid to late morning timeframe across far NE NC
and coastal SE VA, and pops have been increased to high end
chc/likely during this midday time period.
Thermal profiles aloft support light snow at the outset across
the entire area. However, warmer air just aloft (H8-85) could
allow for some light sleet/graupel mixing in before any mixed
precipitation turns over to rain by late morning. PoWT grids do
indicate a small chance of some freezing rain along (and mainly
S) of the Albemarle sound, and accordingly some FZRA mention
was considered. However, given very light QPF and the timing, we
have stuck with frozen dominant P-type, and hence no winter wx
headlines at this time. Should also note that precipitation
could turn back to snow briefly by early afternoon in strong CAA
before ending, again with little or no accumulation given
relatively warm ground and light QPF. Farther N, highs should
only rise into the low/mid 30s under a partly to mostly cloudy
sky. Have also allowed for a period of flurries over northern
tier, mainly north of a FVX-RIC-WAL line. Even in the dry
airmass, northern stream shortwave, ongoing strong CAA and
strong upper jetmax crossing could be enough to wring out a few
light snow showers. HRRR has begun to catch on to this
potential, for what it`s worth...so later shifts will be keeping
an eye out for this potential early tomorrow morning. Measuring
unlikely, so will hold pops out for now.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
Strong (cold) 1040+ mb arctic high pressure will build across
the Ern Great Lakes Wednesday night into Thursday and continue
to nudge into the area. This will bring a cold/dry day with
partial clearing. Have continued to undercut MOS guidance for
this period, with forecast highs only in the upper 20s N to mid
30s SE, after morning lows in the low/mid teens N to the low 20s
SE. There is the potential for wind chill values of 0-5 above
early Thursday morning over the MD Ern Shore if enough wind
persists.
12z Model guidance continues to trend drier and more suppressed
with the wave that pushes off the Southeast coast Thursday
night into early Friday. The GFS remains an outlier in handling
this system, and even it is showing little or no QPF for the
lower Mid-Atlantic at this time with the exception of some
light QPF over NE NC. Dropped POP back to slight to low end
chance for some snow showers. QPF will be light and hence any
snow accum will be minimal. Lows Thursday night range from the
upper teens/around 20F N to the upper 20s far SE under a mostly
cloudy sky.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
Long term period will be dominated by cold NW flow across the
region, as broad upper trof persists over the eastern 2/3rds of the
U.S. Models still not in synch with regard to the tangible weather
scenario in the Friday night through Monday time frame. 12Z ECMWF
continues its trend of bringing a system across the Great Lakes, and
developing a surface low off the mid Atlantic coast Sat/Sat night.
This system intensifies far enough offshore to limit any light snow
to the northern portions of the area on Saturday. GFS continues to
suppress this system in lieu of a shortwave that rotates around the
main upper trof Sunday into New Years Day. WPC has negated this
solution in favor of the ensemble solutions, and thus have mainly
used WPC blended solution for the Friday night through Monday time
period. This means a generally dry period, but quite cold, with
temperatures well below normal through the period. By day 7, next
Tuesday, all models suggest dry but continued cold weather across
the region.
Temperature-wise, it will be a cold period, with high temps most
areas not getting out of the 30s from Saturday through Tuesday.
Exception will be SE portions of the area, where temps could get to
or just above 40 degrees on Saturday. Low temps mainly in the 20s
Friday night, dropping mostly into the teens /except around 20
near the coast/ Saturday night through New Years night. Min
temps in the 20s again by next Tuesday night.
&&
.AVIATION /02Z WEDNESDAY THROUGH SUNDAY/...
VFR conditions across the region with mid and high clouds and
light wind. A dry cold front will push through the region late
tonight with the wind increasing and veering around to the N.
Weak low pressure will form just offshore of the Carolina coast
Wednesday bringing a 20-40% chc of light snow or a light
rain/snow mix to far SE VA/NE NC region.
Outlook: Strong high pressure builds N of the region late Wed/Thu.
Weak low pressure remains offshore Thursday night into early
Friday. Another cold front pushes across the area Friday night
with high pressure returning Saturday.
&&
.MARINE...
Marine conditions are pretty tranquil this afternoon. With high
pressure over the area, winds are at or below 10 kt most areas.
Shortwave trof and associated surface low moves off the coast and
begins intensifying by Wednesday afternoon, resulting in a
significant increase in winds late Wednesday afternoon through
Thursday midday/afternoon. Will be issuing a SCA during this period
with the 4 pm forecast issuance. Beyond Thursday afternoon, the next
threat for SCA conditions looks to be Saturday night into Monday, as
yet another period of cold air advection ensues.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...None.
NC...None.
VA...None.
MARINE...Small Craft Advisory from 1 PM Wednesday to 10 AM EST Thursday
for ANZ635>638.
Small Craft Advisory from 1 PM Wednesday to 1 PM EST Thursday
for ANZ630>632-634.
Small Craft Advisory from 4 PM Wednesday to 7 PM EST Thursday
for ANZ633-652-654-656-658.
Small Craft Advisory from 4 PM Wednesday to 4 PM EST Thursday
for ANZ650.
&&
$$
SYNOPSIS...MAM
NEAR TERM...MPR/MAM
SHORT TERM...AJZ/MAM
LONG TERM...WRS
AVIATION...MAM/JEF
MARINE...WRS
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1049 PM EST Tue Dec 26 2017
.SYNOPSIS...
A series of very cold and dry Arctic high pressure systems will
be the primary weather feature across the region through mid-week
next week. However, a slight chance of very light wintry precip
exists over the southern Georgia and Carolina Piedmont Wednesday
morning and a chance of light wintry precip is possible across
the entire region Sunday night into Monday.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
As of 1020 PM EST: Still fair across the region for the time
being, but our concerns about the srn fringe of the fcst area
remain unchanged. Upstream radars show light precip development
reaching up into nrn MS and moving into the nrn half of AL. It
is worth mentioning the models have a decent handle on this
development and still just skirt the nrn edge of the precip
across the Lakelands. The problem is that relatively clear sky
has allowed temps to fall below 32F in parts of that region,
specifically Greenwood, while the air mass was also dry, but
not as dry as farther north. The 21Z SREF continues to show the
potential for precip on the order of only a few hundredths, with
a favored precip type of rain, because the model suggests that
temps will actually rise a bit once thicker cloud cover moves in,
raising wet bulb temps above 32F. As of this time there is no clear
indication that precip will present a problem across that region,
so an advisory will not be issued. However, this will have to be
monitored overnight and one might still be needed if the favored
precip type becomes freezing rain.
Otherwise, water vapor imagery and initialized RAP heights show
a broad but shallow trough over the eastern U.S. early this
evening. Weak vorticity lobes embedded in the resulting westerly
flow aloft will approach the forecast area and cross the region
late tonight. Meanwhile, a 150 kt 300 mb jet streak will pass
just north of the forecast area overnight, with a brief window
of weak upper level divergence occurring around daybreak south
of the jet axis. Finally, some very transient low level upglide
may develop toward daybreak in the 900 to 850 mb layer over the
lower piedmont to complete the weak forcing picture. Moisture is
expected to be quite limited, but now all of the operational models
are bringing some low-end measurable QPF amounts to the southeast
fringe of the forecast area, and the 12Z ECMWF has become even
a bit more troubling (wetter). Surface wet bulb temperatures
will likely be right around the freezing mark across the far
southern piedmont, and perhaps closer to 30 degrees southeast of
Charlotte. Will thus feature some slight chance to chance PoPs for
sleet or light freezing rain in a 6-hour window around daybreak
Wednesday morning. Will not include any accumulations given the
dry profiles and limited model PoP and QPF, but it bears watching
in case a short fuse statement or advisory is needed should QPF
trend further upward. Will mention in the HWO.
Westerly flow will continue through Wednesday but with little
to no additional forcing. The reinforcing cold front will begin
pushing southward across the northern tier of the forecast area late
Wednesday. Improving afternoon insolation should permit at least
the southern tier to warm slightly above Tuesday max temp values.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
As of 200 PM EST Tuesday: The strong and cold high pressure centered
over the Great Lakes Region on Wednesday night will build down the
east side of the Appalachians in a cold air damming pattern on
Thursday. This will lead to well below normal highs on Thursday
generally in the lower to middle 30s. The colder air will be very
dry with dewpoints in the single digits. This overall dryness will
limit the precipitation potential in our forecast area from a weak
low off the coast. This forecast will continue the trend of reducing
precipitation and will only include a slight chance of snow/sleet
Thursday afternoon and evening in the southern portions of the
forecast area.
The cold air damming will break up by Friday allowing temperatures
to climb into the 40s outside the highest elevations. Conditions
will remain dry Friday.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
As of 230 PM EST Tuesday: The medium range forecast still carries
much greater than usual uncertainty, with poor model-to-model and
run-to-run agreement on numerous longwave features and storm
systems. The beginning of the period has become slightly less
controversial, with a strong and now dry surface high centered over
the northern plains exerting its influence on our area Friday night
through early Sunday. The GFS carries a clipper system through the
Appalachians Saturday, but the best QPF response remains just to the
north of our forecast area, and sensible weather here remains dry.
The fun begins Sunday afternoon, with the 12Z GFS depicting the
development of a cold wedge of high pressure extending down the
southern Appalachians with some moisture being shunted northward
over the wedge as a Gulf low undergoes cyclogenesis near the Big
Bend of Florida Sunday night and Monday. The 12Z ECMWF has a much
less intense low much farther to the south, with absolutely no QPF
response in our area. The drying trend from earlier this week seems
to be repeating itself once more, so opted to keep my thinking
consistent with previous shifts and keep pops to slight chance or
less outside of the mountains Sunday night through the day on
Monday, with just a few hours of chance pops in the NC/GA mountains
early Monday morning. If there is any QPF, profiles will be cold
enough to support almost entirely snow in the NC mountains, with
some light rain/snow mix possible outside of the mountains. If the
favorable drying trend continues, this system will likely be very
low or no impact.
The last area of controversy in the medium range is the temperatures
late in the weekend and early next week. The GFS is carrying a very
deep longwave troughing pattern for the eastern seaboard, and
persistent, close to record-breaking cold temperatures would be
possible if this verifies. The ECMWF is quite chilly, but not nearly
as cold as the GFS. Opted for a model blend for the public forecast,
which, though cold, is not the bone-chilling solution possible in
the highly amplified GFS. Will wait for better model agreement to
determine any possible impacts across the area from persistent cold
temperatures.
&&
.AVIATION /04Z WEDNESDAY THROUGH SUNDAY/...
At KCLT and Elsewhere: VFR through the period. Light wind direction
causing minor problems at TAF time. Opted to keep wind direction
just N of E for the first few hours, but guidance still veers the
wind to ESE during mid evening. Obs show a VFR ceiling over the
Midlands of SC, which could brush past KCLT at that time. Will
keep some sct clouds but not a ceiling around 045. Wind will come
back to NE in the early morning hours and then will strengthen from
the N midday Wednesday. Most models have very light precipitation
breaking out from Greenwood SC to Chester to Monroe NC, but staying
well southeast of all the TAF sites around daybreak. There is some
minor concern that it could reach as far N as KCLT, but the models
continue to slowly back off and it was not included.
Outlook: Dry and cool high pressure should remain the dominant
weather feature through late week and into the weekend. Another
small chance for wintry precipitation exists for the lower piedmont
late Thursday into early Friday, as coastal low pressure forms,
though confidence is low. Present indications are for a mainly
dry forecast with any wintry weather shunted to the southeast.
Confidence Table...
15-21Z 21-03Z 03-09Z 09-12Z
KCLT High 81% High 82% Med 68% Low 56%
KGSP Med 70% Med 75% High 83% Med 64%
KAVL High 94% High 85% Med 70% High 87%
KHKY High 100% High 83% Med 66% High 100%
KGMU Med 76% High 86% High 85% Med 63%
KAND Med 76% Med 65% High 90% Med 61%
The percentage reflects the number of guidance members agreeing
with the scheduled TAF issuance flight rule category. Complete hourly
experimental aviation forecast consistency tables and ensemble forecasts
are available at the following link:
www.weather.gov/gsp/aviation
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...None.
SC...None.
&&
$$
SYNOPSIS...JMP
NEAR TERM...HG/PM
SHORT TERM...SW
LONG TERM...Carroll
AVIATION...PM
Area Forecast Discussion
National Weather Service Houston/Galveston TX
857 PM CST Tue Dec 26 2017
.UPDATE...
Retooled temperature trends for obs, but with diurnal ranges this
week being so small, the changes are cosmetic. Given the strong
drizzle signature on radar and several -DZ obs around the area,
have added drizzle and made it the primary precip type along with
some light rain early on, transitioning back towards light rain
showers tomorrow. Not entirely sure we`ll make this transition
fully to showers given the structure of HRRR soundings, but will
conservatively drop the drizzle in tomorrow`s grids for now.
Luchs
&&
.PREV DISCUSSION... /ISSUED 553 PM CST Tue Dec 26 2017/
AVIATION...
Low ceilings and fog (mainly IFR) along with periods of
-RA or -DZ are expected this evening and overnight. Look
for increasing north winds overnight. Anticipating slowly
improving ceilings late tomorrow morning through tomorrow
afternoon from north to south along with a decreasing risk
of -RA/-DZ. 42
PREV DISCUSSION... /ISSUED 346 PM CST Tue Dec 26 2017/
DISCUSSION...
Low amplitude trough and associated ascent continues to shift
away from east TX this afternoon, pulling weak showers with it.
Surface low along coastal front remains off the upper TX coast
which will also likely shift e-ne before weakening this evening.
As this occurs, we will see winds become more nely across the area
which should also help lift fog over the near shore/bays. This
will also aid in shifting reinforcing cold front now moving into
central TX offshore tonight. Expect this will keep temps well in
the 40s tomorrow along with brisk northeast winds and cloudy
skies. PoPs wednesday will be less certain with general zonal flow
and potential for another subtle disturbance coming out of nrn
Mexico. Will keep chance PoPs in play for now.
Overall should see a trend towards somewhat warmer weather into
late week/early weekend before yet another cold front ushers in
return to much below normal temps to start the New Year. This
next front also brings significant uncertainty as both Euro and
GFS remain markedly different with how they handle the arctic
intrusion. GFS continues to drive significant cold air intrusion
straight down the high plains, while the Euro takes the surface
ridge more towards the southeast/mid atlantic. This leads to quite
a bit of difference in the temp forecast over southeast TX, and
leads to very low confidence in the extended forecast as a whole.
Have opted to keep a compromise for temps after the weekend front,
but should GFS verify we could be much colder.
Evans
MARINE...
Patchy fog will persist into the evening hours, but doubt there will
be any prolonged periods of vsbys less than 2nm. They should improve
overnight as northeast/north winds start increasing. Speeds will
gradually increase to advisory levels overnight and will hoist an
SCA starting at 3am.
The persistent e/ne wind has given water levels a bit of a boost and
they`re currently running 1-2 feet above normal. They`ll likely
remain above normal for several days but am not expecting levels
nearing any coastal flood impacts.
Winds will veer to more of an easterly direction later in the week
as high pressure moves away. Expect another front this weekend, but
confidence in timing/strength is quite low at this time. 47
&&
.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 38 42 36 46 39 / 40 30 30 10 10
Houston (IAH) 42 45 37 49 40 / 50 50 30 20 20
Galveston (GLS) 46 48 43 51 46 / 50 40 40 20 20
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...Small Craft Advisory from 3 AM to noon CST Wednesday for the
following zones: Coastal waters from Freeport to the
Matagorda Ship Channel out 20 NM...Coastal waters from High
Island to Freeport out 20 NM...Galveston Bay...Matagorda
Bay...Waters from Freeport to the Matagorda Ship Channel
from 20 to 60 NM...Waters from High Island to Freeport from
20 to 60 NM.
SMALL CRAFT SHOULD EXERCISE CAUTION until 3 AM CST Wednesday for
the following zones: Coastal waters from Freeport to the
Matagorda Ship Channel out 20 NM...Coastal waters from High
Island to Freeport out 20 NM...Galveston Bay...Matagorda
Bay.
&&
$$
Discussion...25
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
1040 PM EST Tue Dec 26 2017
.UPDATE...
Issued at 1040 PM EST TUE DEC 26 2017
Grids refreshed with latest observations. The forecast is still
on point with colder temperatures beginning to make their way
into the northwestern portion of the CWA. Any potential for
flurries will be in the northern part of the CWA. However,
potential is decreasing as seen in the latest HRRR run which shows
no returns in our CWA but minimal snow to the north. Left flurries
in the grids for now as they taper out through the night.
UPDATE Issued at 649 PM EST TUE DEC 26 2017
Ingested current observations to freshen up grids. No major
changes needed since forecast is on track for the onset of the
colder air coming into the CWA later tonight as well as the
ongoing potential for some snow flurries.
&&
.SHORT TERM...(This evening through Wednesday night)
Issued at 340 PM EST TUE DEC 26 2017
The latest surface map features an exiting arctic front into the
Tennessee Valley. High pressure is centered across the northern
Plains, with very cold air gradually building southeast into the
lower Ohio Valley. Aloft, broad cyclonic flow remains in control
across most of the CONUS. Another mostly cloudy day has been on
tap for eastern Kentucky, with temperatures ranging from the low
to mid 30s across the area.
Clouds and some flurries will be seen across eastern Kentucky
tonight, as another weakening impulse traverses the cyclonic flow
aloft. Some of the higher resolution models suggest a glancing
blow of measurable snowfall north of I-64, but given the dry low
levels and weakening trend to the mid-level short wave, will keep
POPs low. Temperatures will drop to around 10 degrees, or
slightly lower by dawn Wednesday morning north of I-64. A
gradient of warmer readings will be found towards the
Tennessee/Virginia border, where lower 20s will be more common.
Skies will clear out on Wednesday, with the arctic high building
in stronger. Highs will remain in the 20s for most locations.
Mostly clear skies hold on into Wednesday night, setting the stage
for single digit temperatures in the valleys by early Thursday
morning.
.LONG TERM...(Thursday through Tuesday)
Issued at 340 PM EST TUE DEC 26 2017
Good agreement in the mid/upper solutions through the first 24 to 36
hours of the extended. Models diverge thereafter leading to an
overall low confidence in the forecast. While some general, more
qualitative descriptions can be made about the pattern, differences
in the mid/upper level flow are significant enough that there is not
much point in detailing features closer to the surface.
Broad cyclonic flow across the CONUS dominates the pattern with a
couple disturbances to deal with through the extended. There seems
to be an overall trend towards a more amplified pattern by the end
of the period or perhaps just beyond. First mid level disturbance
passes through the Ohio Valley by Friday with the potential of a
more significant shortwave trough passing through the region over
the weekend. The 12Z GFS is also much slower and deeper with it`s
version of the shortwave trough, if it is even the same feature.
Consequently the GFS produces a much stronger surface wave and more
significant sensible weather at the end of the extended. Will add
that the GFS is a strong outlier with much better agreement between
the 12Z ECMWF and Canadian.
For now will stay with the blends and consensus in guidance for
sensible weather. That said, the only thing we can say with any
certainty is that we will experience well below normal temperatures
with daily highs generally running between 25 and 35 F. Overnight
lows will run mainly in the teens, though some single digits will be
possible late in the period. The aforementioned disturbances will
produce an occasional chance for some light snow over portions of
the forecast area. At this time do not see anything worth
highlighting with respect to potential snowfall accumulations.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
ISSUED AT 645 PM EST TUE DEC 26 2017
VFR conditions will prevail through the period along with some
passing mid and high cloud cover. A few flurries may be seen
tonight - mainly in the northern aviation sites; however, these
will be light enough to not cause much in the way of visibility
restrictions. Look for the clouds to thin out during the day on
Wednesday. Winds will remain around 5 kts or less, generally from
the north.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...CGAL
SHORT TERM...GEOGERIAN
LONG TERM...RAY
AVIATION...GEOGERIAN/GREIF
Area Forecast Discussion
National Weather Service Louisville KY
836 PM EST Tue Dec 26 2017
.Forecast Update...
Issued at 834 PM EST Tue Dec 26 2017
The much colder air is making its way to the south this evening.
Temperatures across portions of southern IN have fallen into the
teens and will continue to drop into the single digits tonight.
Temperatures across central KY will follow suit through the night
with lows in the single digits to teens. The radar over the last
hour or so has shown a drying trend. We could still see some
flurries or very light snow over the next couple hours across
southern IN and far north central KY, but it should have no impact.
The forecast was updated to pull the mention of snow and flurries a
bit to the north. Otherwise, only minor changes were made to temps.
&&
.Short Term...(This evening through Wednesday night)
Issued at 259 PM EST Tue Dec 26 2017
A disturbance near Kansas City this afternoon will slide eastward
and roll across the Ohio Valley this evening. NAM and GFS show
weakening upper level divergence and frontogenetical forcing as this
feature approaches, and regional radar depictions upstream have
indeed been showing decreasing dBZs. Most surface observing sites
over southern Illinois and southeastern Missouri have shown little
if any snow at the ground. However, there has also been a recent
uptick in snowfall in a band from central Indiana to southeast
Illinois. The RAP and HRRR bring higher chances of snow into
southern Indiana and far north central Kentucky this evening. So,
will still bring in a small PoP for those areas this evening. Lift
appears weak and surface dew point depressions will be on the order
of 10 to 15 degrees so any snow that does fall will be very light
and dry. Nevertheless, a light dusting will be possible on the cold
ground this evening especially north of the Ohio River.
Wednesday and Wednesday night arctic high pressure will advance from
the Missouri Valley to the Great Lakes, providing us with plenty of
sunshine during the day Wednesday but with chilly temperatures.
Morning lows will range from the single digits along and north of I-
64 to the middle teens in southern Kentucky. Afternoon highs will be
in the teens in Indiana and 20s in Kentucky. Wednesday night mid and
upper clouds will increase ahead of a weak upper trof over the
Plains, but it will still be a cold night with the heart of the cold
dome of high pressure moving through, resulting in single digits and
lower teens for lows.
Because the center of the high will miss us to the north, we will
maintain a breeze on the order of 5 to 10 mph tonight and Wednesday.
With the frigid air in place, even flow this light will still take
wind chills below zero tonight and tomorrow night in southern
Indiana and north central Kentucky.
.Long Term...(Thursday through Tuesday)
Issued at 313 PM EST Tue Dec 26 2017
After some dry, cold weather on Thursday and Friday with high
surface pressures in place, a clipper system is progged to push
through the Ohio Valley Friday night. This may drop a dusting of
snow on southern Indiana and north central Kentucky as it rolls
through.
There are significant differences in the models for this weekend`s
weather with the GFS showing a much wetter solution than the drier
ECMWF and GEM. The operational GFS is quite a bit wetter than most
of the model`s ensemble members and is wetter than the mean as well.
Based on this and the performance of the GFS`s QPF fields at long
range over the past week or two, am inclined to lean more toward the
drier EC/GEM. Looking at the EPS, most of the perturbations are
indeed dry this weekend. As a result, will stick with low PoPs in
the chance category, which also happens to be in good agreement with
the previous forecast.
Wind chills New Year`s Eve, as well as the following two nights,
will be a few degrees either side of zero, so people heading out
will need to be sure to bundle up good.
Taking a glance farther ahead...right now it looks like the cold
will hold on through about the first 6 days of January before
beginning to lose its grip during the second week of the month.
&&
.Aviation...(00Z TAF Issuance)
Issued at 614 PM EST Tue Dec 26 2017
A weak disturbance will move through the region this evening
bringing with it some light snow. The latest trends show that most
of this activity should stay to the north of the TAF sites. It now
looks like LEX may have the best chance for some flurries or very
light snow over the next few hours so will carry VCSH there.
Otherwise, will take out the mention of precipitation at SDF and
HNB. Skies will be clearing from the north late tonight into early
tomorrow morning. VFR ceilings should prevail prior to the clearing.
Winds tonight and tomorrow will be out of the north around 7-10
knots.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...None.
KY...None.
&&
$$
Update...EER
Short Term...13
Long Term...13
Aviation...EER
Area Forecast Discussion
National Weather Service Memphis TN
856 PM CST Tue Dec 26 2017
.UPDATE...
Looking at the latest KGWX radar images, light rain is pushing
into areas of North Mississippi between Charleston and Calhoun
City. Current temperatures range from the upper 30s to the lower
40s across this area. The HRRR continues to show precipitation
skirting this area from Charleston over to Aberdeen, possibly as
far north as Tupelo into the overnight hours. Concerned that
precipitation will change over to freezing rain and/or sleet as
temperatures drop to or slightly below freezing. Will update to
add rain chances for the remainder of the evening hours and change
precipitation type to rain, freezing rain or sleet after
midnight. Will hold off on any winter weather advisory at this
point, but one may be needed if precipitation does indeed change
over.
KRM
&&
.DISCUSSION... /issued 322 PM CST Tue Dec 26 2017/
Guidance has trended toward less of an impact from any wintry
precipitation both tonight and next weekend. However, it still
looks like we will continue to deal with very cold temperatures.
Some temperatures may be as much as 20-25 degrees below normal
early next week.
Overnight, WPC has removed any accumulating rain/snow/sleet/ice
from their graphics across North Mississippi. Models still show
some chance for snow or sleet. The GFS features a warm nose of
around 2-2.5 degrees F which would likely result in snow while the
NAM has a much warmer warn nose over 5-6 degrees which would
likely result in sleet. Nevertheless it looks like a short lived
event only impacting a small portion of the Midsouth along a line
from South Monroe county to South Coahoma county. Any
precipitation that develops will not likely begin until after
Midnight and should exit the Midsouth by sunrise. Will maintain
30% or less pops with no accumulation.
Today through the weekend and into early next week the pattern
essentially remains unchanged. A broad deep trough that spans most
of the country will remain in place centered roughly over the
Great Lakes. This pattern will allow a steady flow of Arctic air
to sweep across West Canada into the Northern Plains and
eventually the Ohio and Mississippi River Valleys. We probably
won`t see dew points above the low 20s any time over the next 7
days with the lowest dew points in the single digits tomorrow and
Thursday or even below zero early next week. High temperatures may
even remain in the teens early next week with low temperatures
below 10 degrees across much of the Midsouth.
The GFS is about the only model holding on to the Wintry
Precipitation next weekend. Not ready to completely remove pops
for the weekend, but lowered them considerably and reduced the
duration to only Sunday into Sunday night as a Cold front sweeps
across the area.
30
&&
.AVIATION...
An MVFR deck over SW KY/MO bootheel and parts of NW TN will move
south into KMKL/KJBR this evening and into KMEM and KTUP later
tonight. Overrunning ahead of a reinforcing cold front may result
in some light sleet at KTUP late tonight. Northeast winds will be
on the increase to 12 kts with higher gusts by morning with
conditions becoming VFR area-wide mid-morning Wednesday.
&&
&&
.MEG WATCHES/WARNINGS/ADVISORIES...
AR...None.
MO...None.
MS...None.
TN...None.
&&
$$
Area Forecast Discussion...UPDATED
National Weather Service San Angelo TX
620 PM CST Tue Dec 26 2017
.UPDATE...
After getting a few reports of light accumulations of freezing
drizzle across parts of the Big Country, and temperatures about to
fall into the 20s for the area, have elected to go ahead and
issue a Winter Weather Advisory for freezing drizzle for the Big
Country. This will mainly affect bridges and overpasses across
areas generally along and north of the I-20 corridor. With drier
air advecting south into the area later tonight, likely putting an
end to the drizzle, have the advisory in effect until 3AM. 20
&&
.PREV DISCUSSION... /issued 511 PM CST Tue Dec 26 2017/
AVIATION...
/00Z TAFS/
IFR/LIFR ceilings are occurring at all sites early this evening
and are forecast to persist through the overnight hours. In
additions, ares of fog will also result in reduced visibilities.
Patchy freezing drizzle may develop across mainly the Big Country
this evening, possibly affecting KABI. Most of the drizzle if
forecast to taper off after midnight. MVFR ceilings are forecast
to develop at all sites by late morning Wednesday, then persisting
through the afternoon hours.
PREV DISCUSSION... /issued 305 PM CST Tue Dec 26 2017/
SHORT TERM...
(Tonight and Wednesday)
.Very cold temperatures with areas of freezing drizzle across the
Big Country...Concho Valley and N. Crockett County tonight. Watch
out for icy bridges and overpasses...
Very cold air continued to move into West Central Texas. The
Texas Tech West Texas Mesonet indicated temperatures of 27 degrees
at Knox City, with 28 at Aspermont and Haskell. It was 33 and 35
degrees at Sweetwater and Abilene. Light drizzle, some freezing,
was indicated by the Dyess AFB radar.
Short range models, including the HRRR and NAM, indicate areas of
light drizzle this evening, tapering off toward midnight as
isentropic lift of warm air over cold air at the surface, weakens.
Icy bridges and overpasses will be the main concern tonight,
especially along and north of I-20, where temperatures will be in
the 20s. Freezing drizzle amounts will be mainly trace amounts,
but even these amounts could produce hazardous conditions.
With current temperatures in the teens in the Panhandle and
Western Oklahoma, sows tonight will be lower and mid 20s in the
Big Country with lows near 32 along the I-10 corridor. Went 2-3
degrees cooler than most short range MOS guidance Wednesday with
cloudy skies and strong cold advection.
LONG TERM...
(Wednesday Night through New Years Day)
Looks like mainly quiet weather across the area for mid to late
week. Temperatures will recover into the 50s for highs and lows
mainly in the 30s. The next strong cold front will move south
across West Central Texas Saturday, bringing much colder
temperatures Sunday and New Years Day as an arctic airmass settles
over the area. The GFS indicates a near 1060 MB surface high over
the Central Plains and the ECMWF has a near surface 1045
MB(probably the right value) over the upper Midwest, and a more
shallow arctic airmass over our area. For now, spitting the
guidance between the very cold GFS and much warmer ECMWF for our
area. Highs will be in the mid 30s and 40s Sunday through Tuesday
with lows in the teens and 20s New Years and Tuesday mornings.
&&
.PRELIMINARY POINT TEMPS/POPS...
Abilene 24 33 29 50 / 20 10 5 0
San Angelo 29 34 32 55 / 20 10 5 5
Junction 34 37 33 54 / 20 20 5 5
Brownwood 30 33 30 47 / 30 10 5 5
Sweetwater 23 32 29 52 / 20 10 5 0
Ozona 32 36 34 53 / 20 20 5 5
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 3 AM CST Wednesday for Callahan-
Fisher-Haskell-Jones-Nolan-Shackelford-Taylor-Throckmorton.
&&
$$