Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/01/18
Area Forecast Discussion
National Weather Service Charleston SC
950 PM EST Sun Dec 31 2017
Arctic high pressure will build across through the rest of the
week. A disturbance is expected to move south of the region on
Wednesday, bring the potential for wintry weather, especially
along the coast.
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
Late this evening: No changes to the going forecast. The 00z
KCHS RAOB looks like as expected. A saturated layer from around
900 mb up to near 650 mb, with considerable dry air above this
layer. The top of the moist layer is at about -3 C, meaning that
it doesn`t reach into the dendritic crystal growth layer. Also,
the warm layer aloft is about 5 kft deep with temperatures
topping out just above 3 C. So, it makes sense that the favored
precipitation type will be light rain or drizzle, and where
surface temperatures can fall to freezing or below, freezing
rain or drizzle. It is notable that the sub cloud layer is quite
dry, and surface dewpoint depressions are running as high as
15-20 degrees F based on surface observations in the Tri-County.
There is better moisture from around Beaufort south into
southeast Georgia, where the potential for freezing rain/drizzle
is a bit more certain. We will just have to watch and see how
radar and surface temperature trends play out over the next few
Early this evening: The forecast through sunrise remains
complicated and low confidence. Radar imagery shows light rain
and pockets of drizzle breaking out across much of the forecast
area. Fortunately at this point, temperatures are still well
above freezing and, other than a few pellets of sleet, all
precipitation will be liquid. The issue comes mainly after
midnight when arctic air begins to rush in from the north,
coincident with areas of light precipitation and drizzle. There
is a very fine line for this event as where it ends up
precipitating it will likely occur late tonight with sub
freezing surface temperatures. The last few runs of the HRRR and
RAP have brought measurable precipitation back inland into
Coastal Colleton, Charleston, and Tidal Berkeley counties in the
2-7 am time frame. This would be enough to produce a very light
glaze of freezing rain/drizzle on elevated surfaces, possibly
including bridges and overpasses. Due to this, the Winter
Weather Advisory has been expanded into Coastal Colleton,
Charleston, and Tidal Berkeley counties. We considered a
southward expansion further into southeast Georgia, but in this
area it looks like the cold air will be chasing the rain/drizzle
out so we held off for now. We could still see some light
freezing rain/drizzle across areas further inland, but felt like
the best chances would be closer to the coast for precipitation.
No changes to the Wind Chill Advisory.
.SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY/...
Overview: Very cold conditions will persist through the period, with
the coldest temperatures of the season likely. Increasing chances
for wintry precipitation on Wednesday.
Monday and Tuesday: Arctic high pressure will build into the area
from the northwest. Monday morning will start off with wind chills
in the teens and 20s and light precipitation. Any precipitation will
likely be in the form of light freezing rain/drizzle near the coast,
mainly from Beaufort, SC southward. This light precipitation is
expected to move rapidly offshore with clearing skies by afternoon.
Otherwise, dry and cold through Tuesday with highs only in the 30s
to near 40 both days. Lows Tuesday morning will be the coldest so
far this season, in the upper teens to around 20 north and inland,
and lower 20s else where.
Wednesday: This is the most difficult period of the forecast. Models
continue to show another storm system moving well south of the
region, with differences with how much moisture/precipitation
reaches our area. A consensus of the latest runs continue show the
best chances for light precipitation to be near the coast, moving
from southeast GA in the morning, northward across our SC coast
during the afternoon. Model soundings indicate cold enough
conditions to support light sleet and/or snow. Too soon to pin down
the potential for any accumulations. Think our current surface
temperatures may be too warm, given low level northerly winds and
the potential for any light precipitation to wet-bulb the
temperatures down into the mid to upper 30s. Have indicated slight
chance/chance for light snow/sleet mainly along the coastal
counties, and will look into lowering the surface temperatures if
models continue to favor potential for snow/sleet.
Lake Winds: With the arctic high building into the area Monday,
winds could gust near 20 knots at times through Tuesday on Lake
Moultrie, but latest thinking is that conditions will remain below
Lake Wind Advisory levels.
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
Upper troughing will dominate the region into Saturday with cold
surface high pressure prevailing. There will be a small
chance of precipitation Wednesday, mainly near the coast, as a strong
upper shortwave helps develop a surface low off the FL coast which will
shift northeast well off the GA/SC coasts. Temperatures could be just cold
enough for wintry precipitation so will continue to monitor this closely.
Temperatures will remain below normal through the period with 20s
prevailing for most areas at night. Wind chills could be near 15 degrees
for most of the area each morning through Saturday. Thus, Wind Chill
Advisories may be needed, mainly for the coastal counties where the
Advisory criteria is a little higher than the inland counties.
.AVIATION /03Z MONDAY THROUGH FRIDAY/...
At KCHS: VFR ceilings will prevail through about 06z. Then
ceilings are expected to lower to MVFR and with freezing
temperatures, freezing rain/drizzle will become a concern
through at least 10z. VFR conditions should return around day
break, and skies will steadily clear out through the rest of the
morning. Winds will strengthen and become gusty after sunrise.
At KSAV: MVFR/IFR ceilings are around and will likely persist
through much of the overnight. Pockets of light rain and drizzle
will continue, transitioning to freezing rain/drizzle in the
08-09z time frame. VFR conditions should return around 13z with
clearing skies through the rest of the day. Winds will
strengthen and become gusty after sunrise.
Extended Aviation Outlook:
Monday: MVFR ceilings likely at KCHS/KSAV to start the morning, with
a chance for light rain/freezing rain, mainly KSAV.
Tuesday: VFR with strong arctic high pressure.
Wednesday: another disturbance moves by well to the south, brining
the potential for light wintry precipitation to both terminals.
Latest thinking is that any precipitation will be in the form of
Thursday and Friday: VFR.
Late evening update: A Small Craft Advisory has been issued for
Charleston Harbor that runs from 4 am to 5 pm. Frequent gusts to
at least 25 knots are expected.
Tonight: Small Craft Advisories have been raised for all waters
including Charleston Harbor. Expect winds to steadily increase
tonight as a cold front meander south and an arctic airmass
builds into the region. Winds will increase to 20-25 kt with
gusts to 30 kt. Seas will build to 3-5 ft nearshore with 5-7 ft
Monday through Friday: Models continue to indicate poor conditions
through the period as strong, arctic high pressure produces moderate
to strong north to northwest winds. Small Craft Advisory conditions
expected at least through mid week, but could linger through the
entire work week. Have also raised a Gale Watch for the offshore GA
waters for Monday morning through Tuesday afternoon.
Minor coastal flooding will be possible around the times of the
morning high tides Monday through Wednesday. On Monday, the best
chance will be along the SC coast, then the entire coast Tuesday and
Wednesday. Low level winds are expected to become offshore by
Thursday, significantly reducing the chances for coastal flooding
through the rest of the week.
Record low maximums for 1 January:
KCHS: 45/2001 and other years
Record lows for 2 January:
Record low maximums for 2 January:
Record lows for 3 January:
The temperature/dewpoint sensor on the KCHS ASOS appears to be
malfunctioning once again. Technicians have been notified. Use
data with caution. The observer is manually augmenting the
observation until the problem can be resolved.
GA...Winter Weather Advisory from 1 AM to 9 AM EST Monday for
SC...Winter Weather Advisory from 1 AM to 9 AM EST Monday for
Wind Chill Advisory from 3 AM to 9 AM EST Monday for SCZ045-
MARINE...Small Craft Advisory until 4 PM EST Tuesday for AMZ352-354.
Small Craft Advisory until 1 PM EST Tuesday for AMZ350.
Gale Watch from Monday morning through Tuesday afternoon for
Small Craft Advisory until 10 AM EST Monday for AMZ374.
Small Craft Advisory from 4 AM to 5 PM EST Monday for AMZ330.
Area Forecast Discussion
National Weather Service Cheyenne WY
435 PM MST Sun Dec 31 2017
.SHORT TERM...(Tonight through Monday)
Issued at 216 PM MST Sun Dec 31 2017
A quiet, but rather challenging end to 2017 with potential for fog
and dangerously cold wind chills through Monday. GOES-16 satellite
imagery indicates low-level cloud cover remains intact across much
of the eastern plains this afternoon. We have seen some erosion of
these clouds from the west as the arctic boundary pushed slowly to
the east w/daytime mixing, but generally not much. The persistence
of these clouds suggests significant boundary layer moisture which
is not being handled well by most guidance. That said, it is quite
possible that we will see fairly widespread freezing fog along and
east of I-25 after 00z w/ light upslope and/or upvalley flow. High
resolution guidance from the HRRR suggests dense fog potential, so
the evening shift will need to monitor for a possible Freezing Fog
Advisory at some point.
Clouds and fog may play havoc on temperatures tonight, and w/ that
said confidence in the Wind Chill Warning is low. However, areas E
of I25 in southeast WY and the western NE Panhandle are entrenched
deeply in the arctic air mass and temperatures should still easily
fall into the -15 to -20 F range over the northern Panhandle. This
should yield wind chill values close to 30 below in the Wind Chill
Warning area and around 20-30 below in the Adzy. No changes to our
headlines with frost bite and hypothermia risks heightened because
of New Years festivities occurring outdoors.
.LONG TERM...(Monday through Saturday)
Issued at 353 AM MST Sun Dec 31 2017
More mid level cloud cover is expected to move into the area
Monday and may limit temperatures from climbing too much.
However, it will be warmer than previous days. The models are in
agreement in showing a fairly distinct shortwave moving through
areas east of the Laramie Range Monday night. This shortwave does
not appear like it will have much in the way of mid and upper
level moisture, but will have some boundary layer moisture
associated with it. This in combination with cold temperatures and
a frontal boundary moving through Monday evening may serve as a
focus for some snow bands Monday evening mainly along the I-80
corridor. The rest of the week should be a bit milder as the upper
level ridge moves over the region. The next chance of snow
appears to be on track for Saturday night into Sunday as another
shortwave tracks southeast through the northern Rockies.
.AVIATION...(For the 00Z TAFS through Monday afternoon)
Low confidence forecast through tonight and early Monday morning,
mainly with the timing of the return to VFR conditions as the low
CIGS and fog eventually lift. Models are not really initializing
well, so will go with persistence and low MVFR CIGS and IFR
conditions further west for KCYS and locations near the Nebraska
border. VFR conditions expected at KRWL and KLAR tonight and early
Issued at 353 AM MST Sun Dec 31 2017
Fire weather concerns will quite minimal during the next couple of
days due to very cold temperatures, snow cover, light wind speeds
and high relative humidity values. A warm up is anticipated during
the middle of the week as an upper level ridge moves into the
area. However, fire weather concerns will continue to be limited
due to afternoon humidity values staying above 25 percent and
light wind speeds except for the higher terrain.
WY...Wind Chill Advisory until 9 AM MST Monday for WYZ101-102-107-108-
NE...Wind Chill Warning until 9 AM MST Monday for NEZ002-003-019-021-
Wind Chill Advisory until 9 AM MST Monday for NEZ020-054-055.
Area Forecast Discussion
National Weather Service El Paso Tx/Santa Teresa NM
240 PM MST Sun Dec 31 2017
Colder will push into the area tonight and highs on Monday will be
15 degrees cooler than Sunday`s highs. Also on Monday our skies
will start out cloudy, but by the late afternoon they will begin
to clear. The rest of next week will be dry with a warming trend.
We will see seasonal temperatures by midweek and be above normal
for high temperatures by the end of the week.
The cold air is poised to move into the area tonight. Currently it
is around 70 in El Paso, while two hours down the road it is 27 in
Carlsbad. Right now the cold front is hung up on the mountains to
our east, but the colder air is starting to leak through the
valleys and eventually it will push over the mountains later this
evening. As it pushes in later tonight, the associated low clouds
will also push in. We could see a few spots late tonight with
some freezing fog in parts of Hudspeth and eastern Otero counties,
so slick roads may be a problem in those locations. Further west
it should stay just low clouds. The one wrinkle is that the NAM
model has been trying to kick out some precipitation early on
Monday morning from a very weak shortwave moving across the area
from the northwest. The other models, GFS, ECMWF and HRRR keep us
dry so that is what I`m sticking with. The cold air will push west
to about the continental divide, so places like Lordsburg and
Animas will probably see high temperatures on Monday a few
degrees above normal, while the rest of us will be 5 to 10 degrees
On Tuesday, we will see an upper level ridge begin to build into
the southwest U.S., this will begin a warming trend for us. Highs
on Tuesday will bounce back to near average for most locations and
a little above average out west. On Wednesday a short wave in the
Midwest will push a reinforcing shot of cool air into the region,
so our highs on Wednesday may dip a few degrees before getting
back above average for the end of the week. The weekend looks warm
with the upper level ridge centered over New Mexico. We will see
our high temperatures next weekend running 10 degrees above
average. Both extended models (GFS and ECMWF), have an upper level
trough and associated moisture and precipitation moving into
California, but right now both models keep us dry next weekend
with the precipitation mainly staying off to our west and north.
VFR conditions look to continue at all terminals. However, clouds
will be on the increase with high clouds initially, and lower clouds
moving in overnight. Ceilings dropping to around 8000` possible
through 15Z at KELP, KDMN, and KLRU. Winds will become easterly
behind a cold front during the overnight hours and remain easterly
during the day Monday, but generally at speeds below 12 kts. Skies
will begin to clear at most terminals after 21Z.
A cold front will continue to sweep east across the region
overnight bringing cooler conditions for the next few days. Cloud
cover will increase overnight, but little if any precipitation is
expected. With shallow cold air in place, the presence of an
inversion will result in poor vent rates for the the area through at
least midweek. At the same time, the cooler temps will keep min rh
values well above any critical thresholds. At the same time, the
only wind concerns will be overnight tonight and early Monday behind
the cold front as east winds become gusty, especially along west
facing slopes. After midweek, dry and mild conditions will be the
norm for the area.
.PRELIMINARY POINT TEMPS/POPS...
El Paso 29 51 30 59 / 0 0 0 0
Sierra Blanca 21 46 25 55 / 0 0 0 0
Las Cruces 30 52 28 59 / 0 0 0 0
Alamogordo 27 49 27 57 / 0 0 0 0
Cloudcroft 32 42 27 45 / 0 0 0 0
Truth or Consequences 30 55 31 60 / 0 0 0 0
Silver City 34 58 31 60 / 0 0 0 0
Deming 30 54 27 62 / 0 0 0 0
Lordsburg 31 59 31 63 / 0 0 0 0
West El Paso Metro 31 49 31 59 / 0 0 0 0
Dell City 19 43 19 54 / 0 0 0 0
Fort Hancock 28 51 30 62 / 0 0 0 0
Loma Linda 24 45 28 54 / 0 0 0 0
Fabens 29 51 28 60 / 0 0 0 0
Santa Teresa 30 50 28 59 / 0 0 0 0
White Sands HQ 29 51 29 59 / 0 0 0 0
Jornada Range 27 53 21 58 / 0 0 0 0
Hatch 26 55 25 61 / 0 0 0 0
Columbus 32 53 28 63 / 0 0 0 0
Orogrande 27 51 28 57 / 0 0 0 0
Mayhill 22 46 25 51 / 0 0 0 0
Mescalero 28 47 23 50 / 0 0 0 0
Timberon 28 44 24 49 / 0 0 0 0
Winston 23 59 24 59 / 0 0 0 0
Hillsboro 28 58 30 61 / 0 0 0 0
Spaceport 26 53 25 59 / 0 0 0 0
Lake Roberts 19 59 20 60 / 0 0 0 0
Hurley 28 56 29 62 / 0 0 0 0
Cliff 21 63 22 65 / 0 0 0 0
Mule Creek 25 61 24 62 / 0 0 0 0
Faywood 30 56 29 62 / 0 0 0 0
Animas 34 61 31 65 / 0 0 0 0
Hachita 29 56 29 64 / 0 0 0 0
Antelope Wells 28 59 31 66 / 0 0 0 0
Cloverdale 35 65 33 64 / 0 0 0 0
Area Forecast Discussion
National Weather Service Wilmington NC
928 PM EST Sun Dec 31 2017
An arctic airmass will become entrenched into the Carolinas through
the upcoming week. Temperatures will average 15 to 20 degrees
below normal with highs less than 40 and lows in the teens most
days. A coastal low pressure will skirt the area Wednesday, and
chances are increasing for some wintry precipitation, mostly
along the coast.
.NEAR TERM /THROUGH MONDAY/...
As of 930 PM Sunday...Radar is relatively quiet at the moment
with just a patch or two of what is probably sleet and maybe
snow over the waters. The latest NAM and to some extent the
iterations of the HRRR show a chance of some redevelopment
across the area through about 06 UTC and maybe even later across
southern zones. The models appear to be picking up on linear
streamwise vorticity settling in from the north and some
moisture and forcing from a system across the Gulf of Mexico.
Will maintain the pops and advisory with this update citing
these features and guidance. Temperatures seem to have stalled
their decline for the moment and have adjusted the hourly grids
to match. Guidance is still insisting on lows in the upper teens
northwest to the lower twenties elsewhere but depending on
trends these may be need a slight upward adjustment later. This
would make wind chill values a little more "reasonable" for the
overnight hours. No other changes or updates. Previous
discussion from this afternoon follows:
Temperatures firmly locked in the 30s for
nearly all the forecast area. Here at ILM we were approaching
40 until a layer of strato-cu moved in from the Atlantic. A
consensus of guidance shows temperatures rapidly dropping below
freezing with the sunset. Minimum apparent temperatures will get
as low as the single digits for our NC counties by daybreak on
Monday. As these wind chill values will stay above the 5F
trigger for a Wind Chill Advisory, have opted to issue an SPS to
warn New Years`s Eve celebrants of the abnormally low
temperatures. A wrinkle in the forecast is the possibility of
flurries overnight along the coast. Leaning towards the dryer
GFS in this case which would make accumulating snow a very
remote possibility. However, would not be shocked to see a few
reports of snow flurries around midnight.
An ongoing strong surge of cold and dry air will mark New Years Day
as an Arctic high drops south over central CONUS. Model soundings
show ample afternoon sunshine but highs only in the lower to mid
30s. This is over 20 degrees below normal! Happy New Year!
On a completely unrelated note, I retire today after 30 years of
combined military and civilian Government service. It has been a
genuine honor to serve this country and its people in both of those
capacities and to have had the opportunity to work with such a
dedicated group of true professionals. As we said in the Navy, "Fair
Winds and Following Seas" to you all!
.SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/...
As of 300 PM Sunday...Cold, arctic air will remain entrenched across
the area through the period. Broad surface high pressure centered
over the central plains Monday night will slowly drift southeast and
weaken, and will exist as a NE-SW oriented ridge axis across the Mid-
Atlantic region by late Tuesday night. Gradient winds will keep the
airmass mixed Monday night, but temps will still plummet into a
general 14-18 degree range from north to south. This will yield wind
chill values in the low single digits after midnight Monday night,
and they likely will remain in the teens through noon Tuesday. Our
threshold for a Wind Chill Advisory is 5 degrees or lower. We
typically don`t issue advisories for third-period events, so will
give the night shift an opportunity to evaluate 00Z guidance, and
raise the advisory overnight if still deemed necessary. 850 mb cold
air advection will be weaker Tuesday, but still ongoing, so the
expected abundant sunshine won`t be enough to warm temperatures
above the mid 30s. Widespread mid teens are expected again
Tuesday night, closer to 20 along the immediate coast.
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
As of 300 PM Sunday...The first week of 2018 will feature a brutal
cold snap for the Carolinas, with a potential snow event thrown in
for good measure.
This last shift of 2017 brings an exciting but challenging forecast
for the Carolinas. Cold air in place across 2/3 of the nation will
persist and be repeatedly reinforced through the week, and 850mb
temperatures are forecast to remain below 0C locally through next
weekend. A prolonged arctic outbreak of this magnitude is rare, and
if 850mb temps to plummet to -15C or more later this week, that will
be one of only a few handfuls of times that has occurred according
to SPC sounding climatology for KCHS. The continued cold air and
longwave trough across the east will manifest as temperatures
through the extended likely not reaching 40 in many places any
day until Sunday. With highs also expected to remain below 40
Monday and Tuesday, that would give us 7 consecutive days with
highs at 40 or below, tied with January, 1918 for the second
longest streak in history at ILM (8 in Feb 1895). Regardless of
whether this comes to fruition or not, an exceedingly cold,
nearly historic, week is forecast with mins 20 or less every
night and averages running about 15-20 degrees below climo for
With cold air in place, any storm system would bring the potential
for frozen precipitation locally, and we may have that setup for
Wednesday. Guidance is coming into good agreement about a coastal
low passing well E of the Carolinas late Wednesday. Although this
system is well displaced from the local area, this keeps the cold
air in place, and as the main shortwave hangs back within the
longwave trough, an inverted trough is progged to develop to the NW
of the main surface low. This occurs in conjunction with veering
850mb winds as secondary low development occurs at this level closer
to the coast, driving increasing moisture into the column.
Examination of forecast time-heights shows moderate omega lifting
into the dendritic growth zone while subtle folding of theta-e
surfaces is also noted near and just off the coast. This all points
to increasing potential for wintry precip Wednesday aftn/evening,
exiting to the NE Wednesday night. MOS P24 numbers have come up this
aftn, and the trend is definitely more moist with nearly all GFS
ensemble members now showing some snow at ILM. After coordination
with neighbors have pushed POP westward somewhat and increased to
mid-chc along the coast.
Although a weak warm nose of +1 - 1.5C is noted initially, dynamic
cooling is expected thanks to lift above this layer promoting snow
falling through the warm nose. This suggests most of the precip will
fall as snow, with IP likely at onset as well. Although guidance
does produce accumulations, with surface air temps in the upper
30s at onset, it being D4, and guidance just beginning to ramp
up the potential, have opted to leave out any snow accum at this
time and will address this potential with later updates. Either
way, some wintry precipitation is becoming more plausible for
Wednesday, exiting to the NE Wed night.
.AVIATION /02Z MONDAY THROUGH FRIDAY/...
As of 00Z...High pressure will continue to build over the terminals
this TAF valid period. Cigs are currently 3300-4200 ft, lowest at
KMYR, highest at KFLO/KLBT. Confidence is low, but cannot rule out
cigs briefly dropping to MVFR at KMYR or KCRE this evening. Some
patchy very light -FZRA/IP is occurring east of KILM. This should
not affect the terminal, but need to monitor for the possibility of
development elsewhere through midnight. No significant accumulations
Model guidance is consistent with satellite continuity, and there is
high confidence terminals will see cigs clear out 08Z-10Z, except
around 12Z at KCRE/KMYR. Winds will continue N-NE 10 kt overnight,
with some higher gusts mainly coastal terminals by morning.
Extended Outlook...VFR with the exception of possible MVFR at
the coastal TAFS Wednesday into Thursday.
NEAR TERM /THROUGH MONDAY/...
As of 930 PM Sunday...Small craft conditions well underway
across all waters this evening. The latest forecast (and the
previous one as well) contain a little sleet and freezing rain.
No other changes. Previous discussion follows:
The Small Craft Advisory will remain in
effect through the Near Term as a strong surge of cold air
continues across the coastal waters. In general, N winds of 20
to 25 kts with gusts to 30 kts will continue through the period,
with seas ranging from 4 to 6 ft.
SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/...
As of 300 PM Sunday...Strong high pressure will build eastward
towards the Carolinas through the period. The resulting gradient
over the waters will sustain a NNE wind of 20-25 knots, although
speeds should gradually begin to diminish Monday night. The Small
Craft Advisory currently is in effect through Monday evening, and
there is a possibility that it may ultimately need to be extended a
little longer. It appears as though speeds will diminish to 10-15
knots by Tuesday afternoon before they pick up again Tuesday night
as a result of developing low pressure off the east coast of Florida.
LONG TERM /WEDNESDAY THROUGH FRIDAY/...
As of 300 PM Sunday...Gusty winds the rule this period as arctic
high pressure and a coastal low pressure impact the waters.
Wednesday begins with a coastal low developing off FL and moving NE,
to be well east of the waters Wed night before pulling away on
Thursday. This low will deepen as it heads NE, so the gradient
tightens and winds shift from NE to at 10-15 kts, to N and then NW
at 20-25 kts Wednesday night. Winds ease a bit Thursday while
maintaining the NW direction, but will surge back up to SCA
thresholds Thursday night before finally easing more significantly
on Friday. Although seas will remain below 6 ft through the period,
an SCA may be needed for an extended period of gusty winds which
will push seas to 3-5 ft late Wed and Thursday with the short fetch
being the limited wave height factor. On Friday wave heights will
drop to 2-4 ft.
Additionally, as the low pressure moves up the coast Wed/Wed night,
periods of rain and/or snow are likely to impact the coastal
SC...Winter Weather Advisory until 7 AM EST Monday for SCZ024-032-
NC...Winter Weather Advisory until 7 AM EST Monday for NCZ087-096-
MARINE...Small Craft Advisory until midnight EST Monday night for
Area Forecast Discussion
National Weather Service Louisville KY
843 PM EST Sun Dec 31 2017
Issued at 840 PM EST Sun Dec 31 2017
Satellite/radar shows main band of snow down to the Etown area and
getting into Leitchfield. Observation at FTK had 9-10 miles and
light snow but nothing worse. Webcams in that banding area also not
showing much. Had a weak return around Frankfort, and seeing some
Twitter reports of light snow there, as well as a webcam with a
light catch in a CoCoRaHS rain gauge. Issued an earlier SPS for a
heavier snow band west of Louisville, but that band since has
weakened some. Satellite also shows a thicker area of clouds over
our Bluegrass counties, so still thinking we will see some more
returns pop up over there the rest of this evening. Will have to
watch for any concentrated bands and/or reports. Will issue special
weather statements if necessary. Trended the forecast toward the
only models showing precip, the NamDNG and NAMNest models. Both of
those taper of that precip by 06Z as the focus area shifts slowly
southward. Updated products coming out shortly.
As for the Wind Chill Advisory, the coldest readings this hour are
along and north of a HNB to Shelbyville, KY line, with values around
zero or a few degrees below. We still are on track for many
locations to reach advisory criteria, -10 or colder, by daybreak.
Issued at 530 PM EST Sun Dec 31 2017
Radar has a couple of areas of light returns...one centered around
Corydon, IN and another area around CVG. Colder cloud tops are
showing on satellite in these areas. The first area should fade as
the sun sets, but the second is deeper and NAM soundings, and to a
lesser extent RAP soundings, both show some saturation in the DGZ
this evening. Have added in isolated snow shower chances, mainly
along and north of I-64, but with little accumulations.
.Short Term...(This evening through Monday night)
Issued at 247 PM EST Sun Dec 31 2017
...A Very Cold Start to 2018...
Temps are peaking in the upper teens and low 20s at this hour, and
will be starting their decline back toward the single digits for
lows tonight shortly. Still expecting the steady N surface winds
tonight around 8 to 12 mph as the ~1050 mb surface high pressure
slowly sinks into the central and northern Plains. As a result,
still anticipating wind chill values dropping into the -5 to -15
range through the overnight and New Year`s Day morning. The most
likely areas to see the -10 to -15 range will be southern IN and
northern KY. Will have to see how some lingering cloud cover in our
east affects temps, but could see wind chills down around -10 there
if cloud cover clears out quicker.
Highs only look to recover into the teens again on New Year`s Day,
but skies will be sunny. Wind chills only recover back to the single
digits above zero, so still dress warmly if you plan to be outside.
Monday night should be the coldest night from a temperature
standpoint, but wind chills will be a little "milder" given the
weaker or calm surface winds. Look for lows on either side of 0 with
the lowest wind chills mostly in the -5 to -10 range. A few southern
IN and northern KY spots are still expected to see -10 to -13. So,
plan on keeping the Wind Chill Advisory going for this time. There
is a chance we may be able to get rid of southern portions of the
Advisory before Monday night, but we may let it ride with the
.Long Term...(Tuesday through Sunday)
Issued at 247 PM EST Sun Dec 31 2017
Plan to hold onto the Wind Chill Advisory for Tuesday morning. At
this point, it still looks like southern IN and the Bluegrass region
of central KY could still see wind chill values around -10. Central
KY looks to mainly stay around -5 to -10 which is close enough to
leave the advisory as is.
Tuesday Afternoon - Saturday...
We look to stay in NW flow aloft with strong surface high pressure
in place during this time. This will keep us cold and dry. There
will be a shortwave trough that swings through the region on
Wednesday/Wednesday night which could bring some flurries to our NE.
However the bulk of the moisture, including the Lake Michigan plume
that follows, should stay out of our CWA. Will watch for
opportunities to add flurries for the mid to late week time frame,
but right now confidence is too low in moisture trajectories to add
Lows will mostly be in the single digits to around 10 above during
this stretch, still well below normal. Highs will mostly be in the
upper teens and low 20s with 2 exceptions. Wednesday and Saturday.
Highs look to be more in the upper 20s to low 30s these days.
Saturday Night - Sunday...
The surface high pressure and upper troughing slide off to the east
late in the weekend. This will likely provide the opportunity for
some temperature recovery back toward normal. Saturday night lows
should be around 20 with Sunday highs back near normal and above
freezing! There is some signal for a southern stream system
overunning the area by Sunday afternoon, but will mainly keep the
forecast dry for this period given lack of confidence/consistency in
.Aviation...(00Z TAF Issuance)
Issued at 610 PM EST Sun Dec 31 2017
In this cold airmass, any clouds have potential to generate light
snow, and there are some light snow showers along the I-64 corridor,
mainly west of SDF this hour. Thicker clouds caused some near CVG
earlier, and a few models show a thicker band near LEX later this
evening. For that location have gone deeper into MVFR range for
ceilings along with light snow. The other sites could see ceilings
right at thresholds for VFR/MVFR this evening before we dry out
overnight. Winds will stay from the north at a steady 10-15 knots
this evening before dying off a little overnight.
IN...Wind Chill Advisory until 1 PM EST /noon CST/ Tuesday for
KY...Wind Chill Advisory until 1 PM EST /noon CST/ Tuesday for
Area Forecast Discussion
National Weather Service Midland/Odessa TX
520 PM CST Sun Dec 31 2017
See 00Z Aviation Discussion below.
Sfc obs show conditions slowly improving at most terminals as
colder, drier air pushes in, slowly raising cigs. Currently, MVFR
cigs prevail everywhere except KFST, which is LIFR, and KMAF,
which is IFR. Models seem a bit optimistic in clearing things out,
but do point to improving conditions overnight. All terminals
should be VFR by sunrise Mon, if not before.
.PREV DISCUSSION... /issued 235 PM CST Sun Dec 31 2017/
DISCUSSION...As of 2:30 PM CST Sunday...as everyone knows by now
winter is definitely in the air.
The arctic airmass continues to deepen and move southwest.
Temperatures have been falling all day across the Low Rolling
Plains and the Permian Basin. Temps have also fallen in Alpine as
the airmass deepens. Even though Presidio is at a balmy
(relatively speaking) 70 degrees all indications are that the
arctic airmass will make it to the Rio Grande Valley by late
Even though there could be a few snow flurries this afternoon
across the Low Rolling Plains and Permian Basin no accumulation is
expected. Have cancelled the Winter Weather Advisory for
Reeves...Pecos...and Terrell counties for tonight since freezing
drizzle is not expected. Continued the Winter Weather Advisory for
portions of Southwest Texas and the Guadalupes for tonight. There
could be freezing drizzle or light freezing rain/sleet due to
upslope flow and an upper level speed max moving across northern
Mexico. The southwest areas are in the LFQ of the speed max so
there could be enough lift for frozen precip. Even though the
Winter Weather Advisory ends by early morning models do indicate
the possibility of frozen precip New Years morning into the
afternoon for the southern tier of counties. The GFS and NAM are
more bullish than the ECMWF or what can be gleaned from the high-
res RAP13 and HRRR models. If necessary...later shifts can extend
the Winter Weather Advisory.
However...the big story this New Years Eve will be the very cold
temperatures tonight...breezy to windy conditions...and resulting
wind chills. Have expanded the Wind Chill Advisory to our
northern tier of counties (The Low Rolling Plains and the Northern
Permian Basin) where wind chills could drop to 5 to 10 below
zero. In the Guadalupe Mtns the wind chills could drop to between
10-15 below zero. Other locations in the Permian Basin could see
wind chill readings near zero degrees.
After another very cold day on New Years Day temps will start to
moderate slightly on Tuesday as the arctic airmass moves ENE.
Ridging along the West Coast will move east into the Intermountain
West by mid-week with NW flow aloft. Temps will edge up to near
normal on Wednesday (normal for MAF is 56) and above normal
through next weekend. It will be dry from Tuesday onward. Medium
range models are hinting at the ridge breaking down out beyond the
extended...however we have seen this song and dance plenty of
times (too many times) this month to place much...if any stock in
Just to emphasize what is important for anyone traveling or being
outdoors tonight. Expect slippery roads in Southwest Texas and
the Guadalupe Mtns. Very cold wind chills are expected tonight
across the Permian Basin. Bitterly cold wind chills are possible
tonight in the in the Guadalupe Mtns and the Low Rolling
Plains/Northern Permian Basin. Make sure to bundle up if you are
outside tonight. Keep pets indoors as much as possible and take
precautions to avoid frozen water pipes.
.PRELIMINARY POINT TEMPS/POPS...
Big Spring 10 29 15 31 / 0 10 0 0
Carlsbad 18 28 17 37 / 10 10 0 0
Dryden 26 31 23 34 / 20 30 0 10
Fort Stockton 16 28 21 35 / 10 10 0 0
Guadalupe Pass 12 29 23 41 / 20 10 0 0
Hobbs 9 28 12 31 / 0 0 0 0
Marfa 22 34 22 47 / 20 10 0 0
Midland Intl Airport 11 27 15 32 / 0 10 0 0
Odessa 12 27 15 31 / 0 10 0 0
Wink 17 27 18 35 / 10 10 0 0
NM...Winter Weather Advisory until 5 AM MST Monday for Guadalupe
Mountains of Eddy County.
Wind Chill Advisory until 8 AM MST Monday for Guadalupe
Mountains of Eddy County-Northern Lea County.
TX...High Wind Warning until 5 AM MST Monday for Guadalupe Mountains.
Winter Weather Advisory until 6 AM CST /5 AM MST/ Monday for Big
Bend Area-Davis/Apache Mountains Area-Guadalupe Mountains-
Marfa Plateau-Presidio Valley-Van Horn and Highway 54
Wind Chill Advisory until 9 AM CST /8 AM MST/ Monday for Borden-