Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/16/18
Area Forecast Discussion
National Weather Service Denver/Boulder CO
834 PM MST Mon Jan 15 2018
.UPDATE...
Issued at 830 PM MST Mon Jan 15 2018
Current temperature and dew point readings across the area, as
well as in Wyoming has prompted me to drop minimum temperatures
across the area tonight. Some dew points in the -10 to -20 degrees
F already indicate not much moisture to hold temperatures up, as
well as the potential for the readings to drop more than forecast.
Have made most of the plains drop below zero overnight, with the
exception of the western and southwestern suburbs and foothills
where an inverted trough is expected to develop overnight to keep
just enough downslope wind to keep things mixed. Interesting that
both the HRRR and RAP have temperatures across the South Platte
Valley and south into Washington County drop as low as -15 to -24
degrees - at this point, think this is too low. Went ahead and
added northern Lincoln County to the Wind Chill Advisory with
colder min temperatures expected and with just enough wind to push
the wind chills to -18 degrees F or colder. Winds aren`t exactly
going to be strong, but the danger of exposed skin will still be
there.
A band of clouds still exists over the foothills and adjacent
plains of Boulder, Jefferson and Douglas counties, showing up well
in the GOES-East nighttime microphysics RGB channel. Believe
these should dissipate over the next few hours, though there is a
small chance that the slight easterly surface component may keep
them longer. This would keep the temperatures warmer under the
clouds. Will watch the evolution on satellite imagery.
&&
.SHORT TERM...(This evening through Tuesday)
Issued at 227 PM MST Mon Jan 15 2018
Deep northerly fetch of dry and bitter cold Arctic air on
the Pacific side of a broad Great Lakes cyclone will
continue to spread south over the forecast area during the
next 24 hours. The last of the jet induced/orographic snowfall
lingering over southern portions of the I-25 corridor and Palmer
Divide should exit to the south of the area by night fall.
Clearing skies, light winds and falling dewpoints will likely
result in some of the coldest minimum temperatures of the winter
season. Low temps in the 5 to 10 below zero range and wind speeds
around 5 kts will produce hazardous wind chills in the 15 below to
20 below zero range across the northeast corner of the CWA. A Wind
Chill Advisory has been issued for this area beginning at 11 PM
MST tonight and lasting to 9 AM MST tomorrow morning. Tuesday
high temperatures on the plains under clear/mostly clear skies as
much as 15 to 18 degs f warmer than those today. High country
temperatures will be little different under a stiff northerly
flow aloft.
.LONG TERM...(Tuesday night through Monday)
Issued at 227 PM MST Mon Jan 15 2018
Upper level ridge will build over the Great Basin to the Northern
Rockies Tuesday night and Wednesday. This will bring weak
northwest flow aloft to Colorado resulting in dry and mild
conditions. Surface high pressure will be over the region. This
will produce light winds and poor mixing, so low lying areas may
stay cooler under an inversion.
On Thursday, the ridge moves over the Central Rockies.
Temperatures are expected to climb into the upper 50s to lower
60s. This ridge shifts east of the region Friday as an upper level
trough moves onto the west coast. This will result in an
increasing southwest flow aloft. Temperatures will remain mild
Friday under this pattern. Increasing moisture in the southwest
flow aloft could bring mountain snow late Friday.
The upper level trough tracks across the Great Basin Saturday and
is centered near the Four Corners 00Z. Lift from a jet and the
upper level trough is expected to produce snow over the mountains
starting Friday night. Snow is expected to shift east across
Colorado on Saturday. There may be a brief period of rain
initially, but as the airmass cools precipitation is expected to
change to snow. Models have been very consistent with this trough
and showing snow for Saturday/Saturday night. Will increase pops
into the likely range from this system.
Northwest flow behind the exiting trough will bring cool and dry
conditions for Sunday. Light snow may linger into Sunday morning
over the eastern plains and in the mountains. Any additional snow
Sunday should be light. Ridging will quickly move across the state
Sunday/Sunday night bringing a dry period. Models have some
differences for Monday regarding flow aloft. The GFS shows a moist
westerly flow aloft, while the ECMWF indicates a dry southwest
flow aloft. Will have low pops in the mountains with temperatures
across the area near normal.
&&
.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 830 PM MST Mon Jan 15 2018
A thin line of clouds up against the foothills of Boulder,
Jefferson and Douglas counties with ceilings of 020-030 (affecting
BJC) should dissipate by 05-06Z. Otherwise, clear skies and VFR
conditions are expected for the next 24-36 hours. Light east-
southeasterly winds should be turning south- southwesterly or
drainage over the next few hours at 5-12 kts. On Tuesday, clear
to mostly clear skies can be expected with light southerly breezes
early in the morning becoming east to southeasterly by late
morning and/or early afternoon at speeds generally under 12 kts.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
Wind Chill Advisory until 9 AM MST Tuesday for COZ046-048>051.
&&
$$
UPDATE...Kriederman
SHORT TERM...Baker
LONG TERM...Meier
AVIATION...Kriederman
Area Forecast Discussion...UPDATED
National Weather Service Corpus Christi TX
954 PM CST Mon Jan 15 2018
.DISCUSSION...Arctic cold front continues to plunge southward
through central Texas, south of a College Station to Austin to
Fredericksburg line at 04Z. MSAS analysis showing 3-hourly
pressure rises of 5-6 mb behind the front from north Texas down to
the Permian Basin. Expect cold will arrive a tad earlier than
forecasted. Made adjustments to the frontal timing based upon
latest RAP model. See Marine section for adjustment to Gale
Warning timing.
No changes were made to winter weather headlines at this time.
Will need to monitor the Brush Country on Tuesday, where models
depict a little bit better isentropic lift. Hi-res models depict
more coverage in this region during Tuesday morning especially.
Timing of cold air in the morning to change over to wintry mix
should be earlier in the southern Brush Country and made minor
adjustments to weather grids.
It appears low level drying will advance into the region pretty
quickly Tuesday evening. This may shut down our precipitation
chances early. Will let next shift make decision for adjusting
expiration time of the Winter Weather Advisory.
&&
.MARINE...Cold front will reach marine zones by 10Z and surge
through coastal waters. Bumped up the beginning time of Gale
Warning to 5 AM Tuesday. No other changes were made to the marine
forecast.
&&
.PREVIOUS DISCUSSION... /Issued 602 PM CST Mon Jan 15 2018/
DISCUSSION...See Aviation section for 00Z TAFs.
AVIATION...Mid level cloud deck will hold over South Texas this
evening with ceilings ranging from 5-7 kft. MVFR ceilings are
expected to develop during the overnight hours in advance of the
arctic cold front with isolated to scattered light showers
affecting the Coastal Bend. The arctic front, surging through
North Texas west to the Permian Basin late this afternoon, will
reach the northern portions of South Texas shortly after midnight.
Expect frontal passage at VCT around 08Z, around 10Z at LRD, and
near 11Z for CRP. Ceilings will fall to IFR levels behind the
front along with an increase in coverage of showers. Strong and
gusty north winds will persist through the day with strongest
gusts to around 35 knots over the coastal plains on Tuesday.
As cold air deepens over the region, ceilings are expected to lift
to MVFR levels by 18Z Tuesday. Precipitation expected to change to
freezing rain at VCT by 15Z and 18Z for the other TAF sites, with
a mixture of freezing rain and sleet possible in the afternoon.
&&
.PRELIMINARY POINT TEMPS/POPS...
Corpus Christi 38 39 29 38 29 / 50 70 40 10 30
Victoria 33 34 25 39 26 / 70 60 20 10 30
Laredo 38 40 29 36 30 / 60 70 20 10 30
Alice 38 39 28 37 30 / 50 70 40 10 30
Rockport 37 39 29 40 31 / 50 70 40 10 30
Cotulla 34 36 28 38 29 / 70 60 20 10 30
Kingsville 41 43 29 38 29 / 40 70 50 10 30
Navy Corpus 41 43 32 40 33 / 40 70 50 10 30
&&
.CRP WATCHES/WARNINGS/ADVISORIES...
TX...Freeze Warning from noon Tuesday to 10 AM CST Wednesday For the
following zones: Aransas...Duval...Jim Wells...Kleberg...
Nueces...San Patricio...Webb.
Winter Weather Advisory from 9 AM Tuesday to 6 AM CST Wednesday
For the following zones: Aransas...Calhoun...Duval...Jim
Wells...Kleberg...Nueces...Refugio...San Patricio...Webb.
Wind Chill Advisory from 5 AM Tuesday to 6 AM CST Wednesday For
the following zones: Aransas...Duval...Jim Wells...
Kleberg...La Salle...Live Oak...McMullen...Nueces...
Refugio...San Patricio...Webb.
Freeze Warning from 9 AM Tuesday to 10 AM CST Wednesday For the
following zones: Bee...Calhoun...Goliad...La Salle...Live
Oak...McMullen...Refugio...Victoria.
Wind Advisory from 6 AM to 4 PM CST Tuesday For the following
zones: Aransas...Calhoun...Goliad...Kleberg...Nueces...
Refugio...San Patricio...Victoria.
Wind Chill Warning from noon to 6 PM CST Tuesday For the
following zones: Bee...Calhoun...Goliad...Victoria.
Wind Chill Advisory from 5 AM to noon CST Tuesday For the
following zones: Bee...Calhoun...Goliad...Victoria.
Wind Chill Advisory from 6 PM Tuesday to 6 AM CST Wednesday For
the following zones: Bee...Calhoun...Goliad...Victoria.
Winter Weather Advisory from 6 AM Tuesday to midnight CST
Tuesday night For the following zones: Bee...Goliad...La
Salle...Live Oak...McMullen.
Winter Weather Advisory from 6 AM Tuesday to 6 AM CST Wednesday
For the following zones: Victoria.
GM...Gale Warning from 5 AM to 10 PM CST Tuesday For the following
zones: Coastal waters from Baffin Bay to Port Aransas out
20 NM...Coastal waters from Port Aransas to Matagorda Ship
Channel out 20 NM...Waters from Baffin Bay to Port Aransas
from 20 to 60 NM...Waters from Port Aransas to Matagorda
Ship Channel from 20 to 60 NM.
Gale Warning from 5 AM to 4 PM CST Tuesday For the following
zones: Bays and Waterways from Baffin Bay to Port Aransas...
Bays and Waterways from Port Aransas to Port O`Connor.
&&
$$
TMT/89...SHORT TERM
Area Forecast Discussion...UPDATED
National Weather Service Fort Worth TX
653 PM CST Mon Jan 15 2018
.AVIATION...
/00z TAFs/
Concerns: Strength winds both sustained and gusts through tonight
and timing precipitation transition and cig trends. This is a very
complex forecast with regard to winter precipitation with confidence
low on EXACT timing of changeover. I do have better confidence on
cig trends and continued very gusty north winds overnight.
Currently, a strong arctic cold front was surging into Central
Texas. Strong low level cold advection and increasing mixing of
unidirectional north-northeast low of 35-40 knots below a
deepening frontal inversion were creating gusty north winds.
Sustained winds of 20-25 knots with gusts occasionally exceeding
35 knots were currently occurring, but a look up stream shows they
should soon calm down to around 15-20 knots with gusts to 25 knots
by 06z and after at all airports. Regional radar was noting
large- scale ascent increasing mostly along and south of the
I-20/30 corridors. Most of this was still -RA, but some mixing
with -PL or all over to -PL was starting occur already as far
south as KINJ.
For DFW Metro airports...
Have continued to indicate the strongest north winds this evening,
settling down overnight and into Tuesday morning. Any -RA/PL mix
should occur after 0130z with surface temps remaining above freezing
at least through 03-04z, by which time we would expect a more -PL/SN
transition, going over to all -SN before midnight. After 04z is
when accums and impacts on tarmacs could start to become problematic
as temperatures continue to plummet. Any sleet accumulations will
be well under a tenth of an inch, with snow accumulations overnight
remaining less than one inch. Low VFR cigs BLO FL035 will fluctuate
at times due to precipitation into MVFR AOA 020 through 08z...before
going VFR ABV FL040 before 12z Tuesday. Any arrival departure
rates tonight and early Tuesday will remain very limited across
the northbound semi-circle and cornerposts from Bowie to Bonham.
For Waco...
Similar trends to DFW, but more likely a slower transition on the
precipitation as the airmass behind the cold front starts out much
warmer with surface temps currently in the 50s. Transition over
to a wintry mix likely won`t begin until 03z-05z, so a -RA/PL mix
looks likely before 06z, transition to a -SN or -SN/PL mix through
10-11z, before likely seeing more flurries after daybreak Tuesday
morning. Though you can`t rule out a brief pd of -FZRA around
06z, temperatures still look to hovering around 32-34 degrees and
would expect a faster transition to -PL as the atmospheric column
cool. Accumulations of sleet should remain tenth of an inch or
less, before light snow with accumulations to between 1-2 inches
occurs toward 12z Tuesday.
05/
&&
.SHORT TERM... /Issued 343 PM CST Mon Jan 15 2018/
/Tonight through Tuesday afternoon/
I will preface this discussion by saying that there have been no
major changes to the current thinking with regards to the expected
winter weather tonight and Tuesday. Therefore, we will continue
with the Winter Storm Warning and Winter Weather Advisory and make
no changes to duration or area of these products.
The Arctic cold front was just north of the I-20 corridor as of
3 PM which is right on schedule. The front will move through the
entire region tonight and result in sharply falling temperatures
and increasing northerly winds along with development of some
light precipitation. The high-res model solutions seem to have
the best handle on the current precipitation moving into northern
Oklahoma as well as the light showers currently developing across
North Texas. However, the HRRR appears a bit too wet with the air
at the top of the frontal inversion and therefore generates quite
a bit of QPF near and just south of the Red River this evening. We
will continue to favor the slightly drier solutions of the TTU
WRF and NAM with regards to precipitation tonight as they seem to
have the best handle on the dry air moving in on the west side of
the upper low. These solutions show scattered light rain
developing early this evening with the precipitation slowly
transitioning to a wintry mix as the lowest layers of the
atmosphere cool below freezing. The period of light freezing rain
will be very brief, but since temperatures will be falling
quickly, light ice accumulations will be likely. A transition to
light sleet and light snow will follow in areas that do see
precipitation. Accumulations across the Winter Weather Advisory
area will be generally less than 1/2 inch of snow and sleet.
Farther south and southeast in the Winter Storm Warning area,
moisture will be more available and amounts will be slightly
higher, generally between 1/2 and 1 inch with some amounts up to 2
inches across the far eastern zones. The northwest zones that are
currently not in an advisory may see some light winter
precipitation as well, but right now we feel amounts will be too
light for significant impacts. However, we will continue to
monitor precipitation trends through the night.
The precipitation will end across the northern half of the region
overnight, but will linger across the south/southeast zones
through mid morning Tuesday before ending Tuesday afternoon.
Again, this setup is not one that typically brings large amounts
of winter precipitation but with the expected cold temperatures,
impacts will be high in areas that see anything. Also, since
temperatures are expected to remain below freezing until
Wednesday, any slick roads could linger for quite awhile.
79
&&
.LONG TERM... /Issued 343 PM CST Mon Jan 15 2018/
/Tuesday Night through Sunday/
The main challenge in the long term will be the extreme cold on
Tuesday Night into Wednesday morning. Thereafter, a warmup is
expected, with temperatures likely above seasonal values by the
weekend. Thereafter, there appears to be a chance for showers and
a few thunderstorms during the latter half of the weekend.
Tuesday Night into Wednesday morning should feature one of the
coldest nights thus far in 2018. Skies will gradually clear from
north to south with low level winds diminishing as surface high
pressure settles in from the northeast. The dry airmass in place
will promote ideal radiational cooling. With low temperatures
likely bottoming out into the single digits, a "hard freeze"
appears likely, mainly for areas near and north of the Highway 380
corridor. The previous configuration of the Hard Freeze Watch
looked good, but I went ahead and tacked on a few more counties
where snow/sleet cover may further enhance radiational cooling. If
RAP/HRRR snow depth outputs of 2" of snow/sleet are correct
across more of our East TX counties, it`s probable that a few of
these counties may be added as well in future forecasts. I also
won`t rule out some single digit temperatures in the sheltered
/low-lying areas south of the current Hard Freeze Watch, but for
now will abstain from any wholesale changes as most of these
areas are forecast to fall into the teens to low 20s. Freeze
Watch/Warning or not, it`ll be COLD across all of the area. While
winds will be light, the low temperatures even with the lightest
of breezes will result in single digit wind chill values on
Wednesday morning. During the day, cold conditions will continue
across most of North and Central TX as most areas will struggle to
climb above 32 degrees. Far western zones may be the
beneficiaries of east to southeasterly flow which may limit any
additional CAA.
Thursday and most Friday look to be quiet weather wise as low
level flow finally turns back to the southeast. Most areas should
climb above 32 degrees on Thursday in response to the increasing
southerly winds. There was concern about a brief chance for
winter precipitation down across Central TX, but at this time, it
appears that the track of the upper low may be too far south of
the area to result in any meaningful lift to overcome what should
be a dry airmass. We will keep a close eye on this, but for now,
I`ve pulled the mention of PoPs down here with that reasoning and
after coordination with adjacent WFO`s.
Late Friday into Saturday, there will be a potential for a few
light rain showers, mainly across far eastern zones. At this time,
I don`t have a ton of confidence in the occurrence of this and
it`s likely that this will be mainly sprinkles/drizzle given that
the initial moisture surge will be shallow. The main headline in
the extended will be the noticeable warmup after a cold start to
the week. High temperatures on Saturday will climb into the upper
60s to 70s as southwest winds yield good adiabatic compression off
of the higher terrain to the west.
The forecast becomes challenging on Sunday as model solutions
diverge with regards to the timing of the next front. The general
setup looks to feature a Pacific front/dryline feature that
develops to the west and slides eastward. The progression of this
feature will be largely dependent on the location of the upper
trough. Traditionally, digging upper troughs are not handled well
initially by the synoptic models and these features tend to sag
farther south than forecast. The ECMWF appears to be one of the
slower models with the upper trough and I`ll side with it as it
pertains to temperatures. Low level moisture will have streamed
northward by this time and with strong mid-level flow at 500mb
(in excess of 80 knots), there should be some loose-organization
to the convective mode along the front. At this time, however,
there is still too much uncertainty to advertise any strong to severe
weather potential, but we will keep an eye on this in the
extended.
24-Bain
&&
.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth 23 30 12 31 22 / 40 10 0 0 5
Waco 26 32 12 34 20 / 80 20 0 0 10
Paris 18 27 6 31 18 / 60 5 0 0 5
Denton 22 30 8 32 19 / 30 5 0 0 5
McKinney 20 29 9 32 19 / 40 5 0 0 5
Dallas 24 30 14 31 23 / 40 10 0 0 5
Terrell 22 29 11 33 19 / 60 10 0 0 5
Corsicana 24 30 12 32 21 / 80 20 0 0 5
Temple 26 33 16 35 22 / 80 30 5 0 10
Mineral Wells 22 31 9 34 19 / 30 5 0 0 5
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until noon CST Tuesday for TXZ094-095-
104>106-115>120-129>133-141.
Winter Storm Warning from midnight tonight to 6 PM CST Tuesday
for TXZ107-121>123-134-135-142>148-156>162-174-175.
Hard Freeze Watch from Tuesday evening through Wednesday morning
for TXZ091>095-100>107-115>117-123-129.
&&
$$
05/26
Area Forecast Discussion
National Weather Service Jackson MS
930 PM CST Mon Jan 15 2018
...ACCUMULATING SNOW TONIGHT INTO TUESDAY, DANGEROUS COLD THROUGH
MIDWEEK...
.UPDATE...
Updated for evening discussion.
&&
.DISCUSSION...
As of 3z, a closed cold core upper-level low was centered over
southern Wisconsin with a positively tilted trough extending
through the Central Plains. A jet max entering the trough will
help it dig through the Southern Plains and through the ArkLaMiss.
At the surface, a strong arctic front was analyzed over far
southeast Arkansas with a cold arctic airmass spilling into the
Deep South in its wake. Latest regional radar mosaics show a
precipitation shield filling in from northeast Texas through
Arkansas and into western Tennessee. This precipitation is
associated with moist southwesterly flow characteristic of
0.5-0.75" PWATs and a 290-300K low level ThetaE ridge. Sufficient
forcing for ascent aided by right entrance region jet dynamics
will continue to support expansion of the precip shield overnight.
The majority of the precip is falling as anafrontal snow with
temps well below freezing in the wake of the arctic cold front.
For the rest of tonight, the main update to the forecast was to
adjust the timing of the precip. The 00z JAN sounding revealed a
dry airmass still in place with the better moisture over portions
of Arkansas. Precip has also been slower to propagate into the
Delta and the latest hi-res guidance has latched on to the slower
timing as well. Latest surface obs also indicate that a brief mix
of snow and rain will be likely at the onset before quickly
transitioning over to all snow. Overall, QPF values have not
changed much and therefore left the snow totals and all winter
weather products unchanged. However, there have been some
indications that the highest snow totals could end up just to our
north and west where the best moisture depth is juxtaposed with
sufficient omega in a relatively deep dendritic growth zone and
snow ratios upwards of 12:1. With that behind said though, its
way too early in the event to consider adjusting any snow amounts
(up or down) and will instead pay close attention to the trends
overnight. Regardless of how much snow falls, any accumulations
will result in hazardous travel conditions with temps remaining
below freezing. /TW/
Prior discussion below:
Through Tuesday night: An Arctic front will surge southward across
the region overnight, bringing an increasingly dry and
dangerously cold airmass behind it. Ahead of the front,
temperatures have risen into the 50s in most locales, though
dewpoints were only in the 20s across most of the area. A sharp
mid/upper trough will lag behind the low level surge of cold air.
Considerable mid level moisture has already begun to surge across
the ArkLaTex and Mid South ahead of this trough, as depicted by
latest RAP PW analysis and the GOES-16 TPW product. Later on
tonight, the atmosphere will begin to saturate down through the
lower levels as well, allowing precipitation to develop across the
Delta. In the far northern part of the area, this will likely
begin as snow and remain snow throughout, but in areas farther
south across NE Louisiana/W Mississippi, there has been more of a
model trend toward a brief period of light rain at the onset this
evening. However, that should change over to snow fairly quickly
overnight as wetbulbing and CAA cool the column. Light snow will
begin to reach the Natchez Trace corridor by morning, then
southeast Mississippi during the afternoon. There may be light
rain or light sleet at the onset across South MS before a
transition to light snow.
Generally, expectations for accumulations have not changed
significantly from the previous forecast. The ensemble guidance we
have favored for snowfall amounts has remained fairly consistent,
and with this being a relatively dry snow, ratios greater than
10:1 are possible. 2-3" is still expected across the Delta, with
1-2" northwest of the Trace, and less than 1" southeast of the
Trace. For the Pine Belt, less than 1/2" is expected. With the
majority of this snow occurring with temperatures falling into the
20s, snow will begin to accumulate on roads (especially bridges
and overpasses) much more quickly, so travel impacts will be high
in spite of the (relatively) light accumulations. A Winter
Storm Warning remains in effect for the Delta, where significant
travel issues are possible, and a Winter Weather Advisory has
been posted across the remainder of the area. In an attempt to
speak to impacts, we are going to add a "significant" threat area
to the HWO/graphics for the Winter Storm Warning area to highlight
the potentially significant travel impacts related to the snow.
With this being a drier snow, utility impacts are much less likely
than they were with our December winter storm. Though they are
possible, confidence in travel impacts in the Pine Belt is lesser
than areas to the northwest. However, with light accumulations
expected and neighboring offices preferring an advisory, we
included that area for consistency/messaging sake.
In most areas, temperatures will fall during the daytime hours
tomorrow, with highs occurring in the morning. By noon, we`re
expecting low to mid 20s northwest of the Trace, with teens
already sneaking into the upper Delta. Snow will taper off in the
northwest by early afternoon, central by late afternoon, and
southeast by mid evening, followed by a night of dangerous cold.
As a result, much of that which falls tomorrow will stick around
overnight and into the day Wednesday, so even with snow ending on
Tuesday, travel issues could persist well into Wednesday. As cold
advection continues Tuesday night, snow cover may impact
temperatures. Though we are currently advertising lows in the
teens areawide, some single digit readings aren`t out of the
question in the areas that receive the most snow. This, along with
a steady northerly breeze will result in wind chills falling into
the single digits to near zero at times. A Hard Freeze Warning
and Wind Chill Advisory have been posted to address those
concerns, which are also going to be quite impactful. More details
on this below.../DL/
Wednesday through the weekend:
After a brief respite from the cold on Monday, the ArkLaMiss will
plunge back into the deep freeze yet again for a few days mid-week.
Strong arctic high pressure will barrel south into the region by
Wednesday morning, resulting in frigid conditions. Wind chills early
Wednesday will be in the single digits across most of the ArkLaMiss
region, with the worst wind chills being north of I-20. It is in
this area where we could see wind chills of zero to five degrees. A
Wind Chill Advisory is in effect through mid-morning Wednesday,
before conditions should improve, though still chilly. Hard freeze
conditions will continue through Wednesday and Wednesday night as
highs will struggle to rise above freezing across most of the
ArkLaMiss. The Pine Belt may see highs above freezing on Wednesday
but this will be very brief and temperatures will plunge back into
the teens overnight as the cold dome of high pressure settles over
the region. A Hard Freeze Warning, which will be in effect Tuesday
morning, will continue until Thursday late morning as temperatures
are expected to finally rise above freezing by then.
High pressure will dominate the weather pattern through the
remainder of the week into the early portion of the weekend. This
will leave dry conditions in place across the area. Temperatures
will slowly moderate through the rest of the week and highs will
eventually return to the 40s and 50s by Friday and southerly flow
returns.
The bright spot of the extended forecast comes this weekend as
temperatures will reach into the 60s for both Saturday and Sunday,
and some locales in the southern part of the forecast area may even
flirt with 70 degrees! This comes ahead of a developing shortwave
trough across Colorado, which will swing east into the Mid-
Mississippi Valley region by later Sunday. This will bring another
front to our region but also some rain and possibly storms as well
starting Saturday and especially for Sunday. /28/
&&
.AVIATION...
00Z TAF discussion:
VFR conditions during the early evening will give way to MVFR
conditions as a cold front moves into the area from the northwest.
The front will move through the GLH/GWO/GTR vicinities between
16/03Z and 16/05Z followed by lowering ceilings and visibilities
as areas of light snow develop. Winds will begin gusting from the
north northwest at 20 to 30 knots. The front will continue south,
advancing through JAN/HKS/MEI between 16/08Z and 16/10Z, and HBG
by 16/12Z. MVFR conditions will develop in these areas as well,
but the snow will be lighter and not as long of duration.
Conditions will begin improving from the northwest after
16/18Z./26/
&&
.PRELIMINARY POINT TEMPS/POPS...
Jackson 28 28 15 32 / 3 75 5 0
Meridian 30 32 15 33 / 1 56 28 0
Vicksburg 27 28 15 31 / 9 80 3 0
Hattiesburg 32 37 18 37 / 1 20 44 0
Natchez 28 29 16 32 / 5 73 5 0
Greenville 21 23 13 27 / 74 76 2 0
Greenwood 22 25 12 28 / 37 78 2 0
&&
.JAN WATCHES/WARNINGS/ADVISORIES...
MS...Hard Freeze Warning from 6 AM Tuesday to noon CST Thursday for
MSZ018-019-025>057-059>064.
Winter Weather Advisory until 6 PM CST Tuesday for MSZ026>033-
035>050-053-054-059-060.
Wind Chill Advisory from 6 PM Tuesday to 10 AM CST Wednesday for
MSZ018-019-025>066-072>074.
Winter Storm Warning until 3 PM CST Tuesday for MSZ018-019-025-
034.
Hard Freeze Warning from noon Tuesday to noon CST Thursday for
MSZ058-065-066-072>074.
Winter Weather Advisory from 9 AM Tuesday to midnight CST
Tuesday night for MSZ051-052-055>058-061>066-072>074.
LA...Hard Freeze Warning from 6 AM Tuesday to noon CST Thursday for
LAZ007>009-015-016-023>026.
Winter Weather Advisory until 6 PM CST Tuesday for LAZ008-009-
015-016-023>026.
Wind Chill Advisory from 6 PM Tuesday to 10 AM CST Wednesday for
LAZ007>009-015-016-023>026.
Winter Storm Warning until 3 PM CST Tuesday for LAZ007.
AR...Hard Freeze Warning from 6 AM Tuesday to noon CST Thursday for
ARZ074-075.
Wind Chill Advisory from 6 PM Tuesday to 10 AM CST Wednesday for
ARZ074-075.
Winter Storm Warning until 3 PM CST Tuesday for ARZ074-075.
&&
$$
TW/DL/26/28
Area Forecast Discussion...Updated
National Weather Service Saint Louis MO
947 PM CST Mon Jan 15 2018
.UPDATE...
Issued at 937 PM CST Mon Jan 15 2018
Made a few changes to the remainder of tonight and into Tuesday
morning. These were namely with cloud cover. High clouds remain
persistent across the southeast third or so of the CWA, while
upstream there is a lack of extensive stratocu. Upstream
clouds/stratocu are rather patchy until you get well into IA, and
the low level RH progs from the RAP really don`t show much
increase until overnight. Thus have slowed the increase in cloud
cover from the north overnight and then spread clouds -
stratus/stratocu southeast on Tuesday morning within the cyclonic
low level flow.
Wind chill advisory is right on the mark. Forecast at this time
appears right on target and dangerous wind chill levels are now
occuring in northeast MO and west central IL. The bitter cold/
dangerous wind chills will continue to spread southeast the
remainder of the night as temps fall.
Glass
&&
.SHORT TERM... (Through Late Tuesday Afternoon)
Issued at 332 PM CST Mon Jan 15 2018
(Tonight)
Area of light snow has moved to the southeast of the area with
decreasing clouds well behind the surface cold front. Story for
tonight continues to be the well below normal temperatures and
dangerous wind chills expected tonight. Northwest winds will lighten
up a bit tonight but still remain on the order of 10-15mph and that
combined with the low temperatures near zero will yield wind chill
values of -15 to -20F for much of the area. Wind chill advisory
still looks good so no changes made.
(Tuesday)
One more bitterly cold day as surface high pressure settles into the
mid-Missouri Valley. Steep low-level lapse rates and increasing
stratus from the north should yield at least a chance of flurries
across the area. Otherwise, very cold with high temperatures only in
the teens under a mostly cloudy sky.
Gosselin
.LONG TERM... (Tuesday Night through Next Monday)
Issued at 332 PM CST Mon Jan 15 2018
Despite upper level trof sliding through region Tuesday night, will
only see an increase in clouds with its passage. Otherwise, surface
ridge to build in with light and variable winds. So it will be
another cold night with lows in the zero to 10 degrees above zero
range. Winds will be light enough that wind chill indicies will
not reach advisory criteria.
On Wednesday, surface ridge to begin moving southeast out of area,
allowing southwesterly flow to return to the region with the thermal
ridge building into the area. Gradual warmup expected through the
rest of the work week and into next weekend with highs in the 50s by
Saturday and Sunday.
In the meantime, the next system to lift out of the southwestern US
towards region beginning Saturday. Will see increasing low level
moisture and some decent WAA activity pop up during the day Saturday
into Saturday night. Better chances of rain will be during the day
on Sunday and into Sunday night as deepening surface low lifts
northeast through region, dragging a strong cold front through.
Models in some agreement on timing and placement with several rounds
of rain through the last half of the weekend.
As system exits region Sunday night through Monday morning, will see
colder air spill in on back side of system with rain changing to
snow before ending. Highs by Monday will be in the mid 30s to mid
40s.
Byrd
&&
.AVIATION... (For the 00z TAFs through 00z Tuesday Evening)
Issued at 530 PM CST Mon Jan 15 2018
The cloud trends tonight are a bit unclear. The stratocu well to
the north and northwest appears to have a diurnal heating
component and this would suggest the coverage will diminish the
next few hours. With this in mind, I think the TAF sites will be
VFR tonight with mainly scattered clouds. On Tuesday morning there
should be a big increase in stratocu within the cyclonic low level
flow, resulting in MVFR to low-end VFR CIG Heights. Modest
northwest winds will continue this evening, with the highest
values and continued occasional gusts across far eastern MO into
western IL.
SPECIFICS FOR KSTL:
VFR flight conditins are expected tonight. On Tuesday morning
there should be a big increase in stratocu within the cyclonic low
level flow, resulting in high-end MVFR to low-end VFR CIG
heights. Given the uncertainty in the cig heights, I have gone
with a more optomistic approach for now. Modest northwest winds
will continue tonight with occasional gusts this evening.
Glass
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...Wind Chill Advisory until noon CST Tuesday for Audrain MO-Boone
MO-Callaway MO-Cole MO-Crawford MO-Franklin MO-Gasconade MO-
Iron MO-Jefferson MO-Knox MO-Lewis MO-Lincoln MO-Madison MO-
Marion MO-Moniteau MO-Monroe MO-Montgomery MO-Osage MO-Pike
MO-Ralls MO-Reynolds MO-Saint Charles MO-Saint Francois MO-
Saint Louis City MO-Saint Louis MO-Sainte Genevieve MO-
Shelby MO-Warren MO-Washington MO.
IL...Wind Chill Advisory until noon CST Tuesday for Adams IL-Bond IL-
Brown IL-Calhoun IL-Clinton IL-Fayette IL-Greene IL-Jersey
IL-Macoupin IL-Madison IL-Marion IL-Monroe IL-Montgomery IL-
Pike IL-Randolph IL-Saint Clair IL-Washington IL.
&&
$$
WFO LSX
Area Forecast Discussion
National Weather Service Nashville TN
934 PM CST Mon Jan 15 2018
.UPDATE...
FOR EVENING DISCUSSION.
&&
.DISCUSSION...
Latest radar imagery shows snow has spread throughout our
northwest counties with leading edge of snow approaching
Nashville - a couple hours faster than guidance had previously
suggested. Reports indicate 1 inch of snow has already fallen in
Stewart County in the past 2 hours. Latest model guidance
including the 18Z GFS, 00Z NAM, HRRR and RAP models indicate
higher snow accumulations in much of the cwa, especially the
northwest counties which will see snow for roughly another 12
hours or so. Based on this as well as coordination with
surrounding offices, have upgraded some of our northwest counties
to a Winter Storm Warning with 2 to 4 inches of snow now expected,
with possibly higher amounts. The rest of the forecast area still
falls into the 1 to 3 inch total snowfall range, where a Winter
Weather Advisory will remain in place. Grids and zones have been
updated with the new hazards and to begin snow a little faster in
the northwest, but otherwise remain on track.
&&
.AVIATION...
00Z TAF DISCUSSION.
Cold front is now through CKV and soon to pass through BNA and
MQY. -SN will continue and CKV and hold off until 06z for BNA and
MQY. HRRR has snow reaching CSV around 12z. Cigs will be MVFR or
IFR during the snow with visibilities bouncing from less 1/2 SM
to 4 SM depending on the intensity. After the snow ends MVFR
stratocu will linger through the end of the taf period. Winds at
BNA and MQY will soon veer to the NW while the wind shift at CSV
will be after 06z. Winds will be in the 8-13 kt range for the taf
period.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 6 PM CST Tuesday for Bedford-
Cannon-Coffee-Cumberland-De Kalb-Fentress-Giles-Grundy-Marshall-
Overton-Pickett-Putnam-Van Buren-Warren-White.
Winter Weather Advisory until 3 PM CST Tuesday for Cheatham-Clay-
Davidson-Dickson-Hickman-Jackson-Lawrence-Lewis-Macon-Maury-
Perry-Rutherford-Smith-Sumner-Trousdale-Wayne-Williamson-Wilson.
Winter Storm Warning until noon CST Tuesday for Houston-
Humphreys-Montgomery-Robertson-Stewart.
&&
$$
DISCUSSION......Shamburger
AVIATION........Reagan
Area Forecast Discussion
National Weather Service Spokane WA
352 PM PST Mon Jan 15 2018
.SYNOPSIS...
The weather turns unsettled for the rest of the work week. The
first frontal system arrives late tonight into Tuesday with a band
of light rain or snow. A second, wetter frontal system arrives
Wednesday night into Thursday with a rain/snow mix in the valleys
with snow in the mountains. A cooler and potentially snowy pattern
is possible for the weekend.
&&
.DISCUSSION...
Tonight through Tuesday night: The ridge of high pressure weakens
as the first of many Pacific weather systems move through the
region. High clouds are on the increase late this afternoon, while
areas of stratus and fog lurk in the Cascade valleys under the
easterly pressure gradient. These clouds will gradually raise
overnight, but models show the low level moisture remaining high
through the night. This will benefit sheltered locations and keep
overnight temperatures from radiating before the frontal band
arrives. The timing looks like precipitation will reach the
Cascades after midnight and spread eastward slowly through the
morning. Opted to favor of the mesoscale nam12 and hrrr for timing
and precipitation type, which trend max wet bulbs above zero with
most surface temperatures at or near freezing across north central
Washington for Tuesday morning. The challenge will be
precipitation type, but the trend looks to be more low elevation
rain or snow that transition to a valley rain/mountain snow by
afternoon. Pockets of of sleet or freezing rain are possible with
the onset, but should be localized. The lack of cold air damming
and mild afternoon temperatures favors this solution. The frontal
band stretches and sheers as it tracks eastward toward north Idaho
by afternoon, thanks to the remains of the upper ridge. Anticipate
light rain and mountain snow showers into the evening for the
Idaho Panhandle, before tapering off by Tuesday evening. Snowfall
amounts will range from 2 to 5 inches for the higher Cascades, to
1 to 2 inches in the northern mountains. Valley locations should
see an inch or less. Winds will veer to the south and southwest
with the boundary`s passage but not enough to scrub the low level
moisture out. Stratus and patchy fog look to return for the
Cascade and northern valleys by Tuesday evening under light winds.
/rfox.
Wednesday through Thursday...The next organized storm system to
transit the region will occur during this period as another north
Pacific closed low approaches the region. In the southwest flow
aloft ahead of this feature a weak warm front will form over the
forecast area on Wednesday. Moisture with this warm front will not
be very deep and has been trending weaker over the last few model
runs...so the warm front portion of this complex will mainly
bring increasing clouds to most of the region on
Wednesday...however the Cascades will benefit from some low level
upslope and an approach of the deeper main moisture feed just
ahead of the trailing occlusion during the day with an onset of
light snow.
The main event will occur Wednesday night as the trailing
occluded front pushes through the region with a deeper feed of
moisture. This will be a night time transit which would normally
imply more of a snow event rather than rain...however the warm
front will simply reinforce the mild air mass which has been
prevalent over the region for the last week. Thus...with the
exception of the Methow Valley and some areas immediately near the
Cascades where a cooler air mass has been trapped against the
mountains most of the basin will experience a cold rain from this
system...with northern valleys possibly starting as snow but
turning over to a low accumulation rain/snow mix maybe Wednesday
night but almost certainly on Thursday. The mountains...the
Cascades in general and the northern mountains above 3500 feet or
so...will receive moderate to locally heavy snow accumulations.
the Cascades in particular may be a good candidate for a low end
Winter Storm Warning with this system with the northeast mountains
and Okanogan Highlands zones maybe worth advisories.
By Thursday afternoon the front will be directing the moisture
feed into the Idaho Panhandle...and with models all suggesting the
offshore parent low stalling off the BC coast...this front may
simply hang up and stall providing a focusing mechanism for
continued valley rain and mountain snow into the panhandle
through Thursday night with moderate travel impacts across Lookout
Pass possible.
Friday through Monday...Models are in agreement in holding the
offshore upper low off the coast as it slowly weakens. This will
promote a southwest or westerly moist flow through the region
ahead of it...with any number of minor impulses...poorly resolved
but inferred from pattern recognition...to kick off some random
daytime valley rain and mountain snow showers and overnight minor
accumulation snow showers just about anywhere in the forecast
area...an unsettled and slightly cooler more seasonal regime than
recent days.
On or about Sunday a new offshore upper low will approach the
coast and create another organized warm front/cold front couplet
which may be the next real storm system to bring widespread
precipitation...with a better chance of accumulating snow for the
valleys and northern basin as well as the mountains since by this
time the polar storm track will reside to the south with the
forecast area on the cold side of the polar jet. This upper low
may very well eject through the region...making for a cool and
unsettled snow showery regime through Monday as well. /Fugazzi
&&
.AVIATION...
00Z TAFS: The main stratus and fog issue will continue to exist at
KEAT with easterly gradient banking stagnant moist boundary layer
air against the Cascades. Expect continued IFR and LIFR conditions
at KEAT after marginal improvement between 00Z and 02Z. All other
TAF sites should remain VFR tonight with increasing high and mid
clouds reducing the likelihood of stratus and fog developing
tonight. An occluded front will transit the region Tuesday
bringing mainly rain with MVFR conditions to most TAF sites...but
some -RASN may reduce visibilities mainly at the KGEG...KEAT and
KCOE TAF sites as precipitation begins. /MJF
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 31 39 30 38 37 40 / 0 90 10 10 90 40
Coeur d`Alene 30 39 30 39 36 39 / 0 80 10 10 90 60
Pullman 35 43 32 44 38 44 / 0 90 0 10 90 60
Lewiston 36 46 33 47 41 47 / 0 90 10 10 50 80
Colville 30 36 31 37 34 39 / 0 70 20 20 90 30
Sandpoint 30 36 30 36 34 38 / 0 50 40 20 90 60
Kellogg 33 38 29 38 34 38 / 0 50 10 10 90 80
Moses Lake 33 43 31 39 34 44 / 30 90 10 10 70 20
Wenatchee 33 39 31 34 30 37 / 50 80 10 30 90 20
Omak 32 37 29 34 32 36 / 30 80 10 50 90 30
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
Area Forecast Discussion
National Weather Service Paducah KY
630 PM CST Mon Jan 15 2018
.UPDATE...
Issued at 630 PM CST Mon Jan 15 2018
Updated Winter Weather Advisory area to a Winter Storm Warning.
Snow bands continue to develop, and snow reports of 4 inches or
more becoming more common.
&&
.SHORT TERM...(Tonight through Wednesday night)
Issued at 227 PM CST Mon Jan 15 2018
Snow bands continue to move across the southern third of our
counties, with patchy light snow across all but our far
north/northwest counties. Will be removing portions of southern
Illinois along and north of Route 13 and Perry county Missouri
from our northern advisory as of 21z. Amounts of 2 to 4 inches
are common east of the Mississippi so far, with isolated higher
amounts, with 1 to 2 1/2 inches west of the Mississippi. Expect
to see some additional minor accumulations across portions of
southeast Missouri and areas along the Ohio River for the next few
hours, with a bit more accumulation possible across southern
portions of west Kentucky into the evening. We will gradually be
chipping away at our advisories as snow tapers off. HRRR and RAP
hint at some snow lingering in our far southeast counties after
06z, but for now will keep the southern advisory ending at that
time.
Surface observations show the front through most of our counties.
Colder air is right behind, with temperature drops of 4 to 7
degrees already at several sites in our northern counties.
Overnight lows will drop into the 0 to 10 above zero range. Winds
will stay up in the 6 to 10 kt range overnight, and this puts wind
chills in the -5 to -15 range. Wind chill advisory for southwest
Indiana, most of southern Illinois and portions of northwest
Kentucky for -10 to -15 looks good and will not make any
adjustments. Conditions will remain pretty unpleasant into
Tuesday with highs only in the teens and winds chills only
"improving" to the above zero single digits.
An upper level trof will move across our area Tuesday into Tuesday
night. This may squeeze out some flurries across mainly northern
portions of the PAH forecast area Tuesday afternoon into Tuesday
evening. Lows Tuesday night will again be in the single digits,
but generally light winds will prevent wind chills from being an
issue.
Surface high pressure will move to our south on Wednesday, and a
shift to south to southwest winds late Wednesday into Wednesday
night will begin our "warm up", with highs Wednesday in the less
miserable lower to middle 20s, and lows Wednesday night in the 8
to 14 degree range.
.LONG TERM...(Thursday through Monday)
Issued at 227 PM CST Mon Jan 15 2018
The extended forecast period will start with the building upper
level ridge and blocking surface ridge across the entire Gulf Coast.
A small circulation rotating around the western side of an eastern
Pacific/Pacific Northwest U.S. trough is forecast by both the 12z
deterministic GFS and ECMWF to persist through a narrow high
amplitude ridge and develop lee side cyclogenesis as it moves
southeast into western Texas early Thursday. Numerical model
guidance has this low stalling out and closing off on Friday, as a
split zonal flow develops just to the north of it into the Plains.
A broader amplitude eastern Pacific trough (forecast west of the
previous Pacific Northwest trough on Thursday) will carve out a low
to moderate amplitude shortwave along the path of the previous Texas
low as it weakens and shears out over the southeast U.S.
The net effect of the shortwave trough as it moves from the southern
Rockies and into the southwest U.S. by Saturday will be to enhance
broad southwesterly flow (and persistent warm advection) into the
WFO PAH forecast area, while opening up a moisture channel from the
Gulf of Mexico. The initial stages of the moisture advection and
temperature advection will take place early Friday.
This transition to southwesterly flow aloft will increase
thicknesses, increasing daily minimum and maximum temperatures, with
both low and high temperatures remaining above the freezing mark
starting Friday. The ECMWF is a little more aggressive with the
rise in temperatures, by as much as three degrees, compared to
regionally blended model guidance. At this point, given the amount
of thermal energy needed to melt and evaporate snow cover and snow
melt, combined with cloud cover, plan to leave slightly cooler
temperatures in place. Regardless, temperatures 10 to 15 degrees
above normal will be expected into the weekend and early next week.
At the end of the extended forecast period, a cold front is expected
move through with more copious rainfall amounts and cooler
temperatures (not anything like last week). However, uncertainty on
rainfall amounts and timing precludes any significant focus on any
water (i.e. flooding) concerns at this time.
&&
.AVIATION...
Issued at 533 PM CST Mon Jan 15 2018
Snow bands continue south of KEVV which is resulting in low
cigs/vsbys. Expecting the snow to taper off and eventually end by
mid evening. Lower cigs/vsbys will lift and we should be left with
VFR later on this evening. Another batch of low clouds and
possible flurries/snow showers will arrive late Tuesday morning
and last through the day. Winds will remain northwesterly with
small gusts at times.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...Wind Chill Advisory from midnight tonight to 11 AM CST Tuesday
for ILZ075>078-080>091.
Winter Storm Warning until 4 AM CST Tuesday for ILZ090>094.
MO...Wind Chill Advisory from midnight tonight to 11 AM CST Tuesday
for MOZ076.
Winter Storm Warning until 4 AM CST Tuesday for MOZ107>112-114.
IN...Wind Chill Advisory from midnight tonight to 11 AM CST Tuesday
for INZ081-082-085>088.
KY...Wind Chill Advisory from midnight tonight to 11 AM CST Tuesday
for KYZ007-010-013>016-018>020.
Winter Storm Warning until 4 AM CST Tuesday for KYZ001>022.
&&
$$
UPDATE...RST
Area Forecast Discussion
National Weather Service Portland OR
250 PM PST Mon Jan 15 2018
.SYNOPSIS...East winds will remain strong and gusty through the
Columbia Gorge today. The coming week will be wet and unsettled as a
series of significant storm systems move through the Pacific
Northwest. The first decent system is expected to arrive tonight,
with another stronger system later Wednesday, and third disturbance
this weekend. Snow levels will briefly drop to near the Cascade
passes Tuesday before lowering significantly below the passes
Thursday and Friday with decent snow accumulations in the Cascades
possible. Snow levels will remain below the passes this weekend.
&&
.SHORT TERM...Today through Thursday. The holiday weekend is ending
as pleasant as it began across most of the forecast area, with
temperatures well into the 50s again today. However, the first of
several disturbances this week is about to move into the area and
will shortly bring an end to the recent dry weather. Satellite
imagery depicts the main parent low near 50N/143W with a well defined
frontal structure stretching south and east into the coastal waters.
The leading warm front is lifting north over southeastern Oregon and
is approaching Douglas County, so expect some light rain to begin
across the southern portions of the forecast area very shortly. More
significant rainfall will move onshore and inland through the evening
and overnight. Snow levels in the Cascades fall to pass elevations
late tonight and Tuesday, but the precipitation
amounts don`t look high enough to support issuing a winter weather
advisory. Precipitation will turn showery with this system Tuesday,
decreasing from the south later Tuesday and Tuesday night.
There is a bit of a break in the precipitation Tuesday night and
early Wednesday, but the next cold front slowly spreads some rain
onshore in the afternoon. The main front moves through with rather
heavy rain Wednesday night, and the latest guidance continues to
trend a little a little slower with the progress of the front. Thus,
will need to continue to monitor QPF for any potential hydrological
issues.. This system will have some wind along the coast but
strongest gusts may remain below warning criteria. Finally, large
waves over the coastal waters may produce high surf conditions along
the beaches. Snow levels will be stay above the passes until
Wednesday night and Thursday, but lower behind the cold front early
Thursday to around 2,000 feet as the colder air mass arrives and
showers continue in the post-frontal instability. This looks to be
the start of some additional snow in the Cascades - a welcome sight
given the abnormally low snowpack in the Oregon Cascades for this
point in the season.Cullen
.LONG TERM...Thursday night through Monday...The Pac NW will remain
in an active weather pattern through the end of the forecast period.
Models continue to show the upper level trough settling in over the
Pac NW later this week. This will bring cool and showery conditions
to the region Thursday night and Friday with snow levels around 2000
to 3000 ft. Models then show a series of wet frontal systems moving
across the forecast area over the weekend. These will likely bring
another round of heavy rain, strong winds, and Cascade snow to the
region. However, impacts over the weekend remain a bit fuzzy at the
moment due to distinct differences in timing, strength and location
of the various systems. Nonetheless, it is becoming increasingly
likely that the Cascades could get several inches of new snow this
weekend. In addition, we could also see sharp rises on some of our
river over the weekend. Showers look to return on Monday as the
upper level trough moves across the Pac NW. /64
&&
.AVIATION...VFR across the area early this afternoon. The LIFR
conditions that were in the South Willamette Valley this morning
dissipated by 2030Z. Mid and high-level clouds will increase
from SW to NE through the afternoon and early evening. Precipitation
expected to reach the coastal areas by and 00Z, with MVFR likely
after about 03Z Tue. Precip spreads inland after 00Z, but VFR
should hold through 12Z. The exception will be the south interior
valleys where MFVR and possibly local IFR may develop early this
evening before precip arrives and a little south surface wind
provides better mixing. Frontal boundary moves through the
interior valleys by about 07Z and to the Cascades around 10Z.
PDX AND APPROACHES...VFR to prevail through at least 16/12Z.
Cigs will continue to lower through this evening, falling to
around 040 by 04Z Tue. Some models indicate a stratus cig at 015
developing late tonight after 10z, but don`t have solid
confidence yet. Sfc wind 09025g40kt to continue near the west end
of the Columbia Gorge through at least 06Z Tue. Weishaar
&&
.MARINE...A deepening low pres area out near 50N 140W will spin
north over the next 18 to 24 hours. Wind speeds have strengthened
since this morning, with a few gale gusts already noted at buoy
089. The 12Z NAM and GFS in decent agreement depicting solid gale
force boundary layer wind through 06Z Tue. The GFS shows a swath
of 40-45 kt boundary layer wind speeds over the far outer waters
00Z Tue, which is at least 10 kt higher than the NAM. The HRRR
80m wind field valid 00Z-03Z Tue is much more similar to the NAM.
Thus, have trended toward the slightly lower wind speeds. The
strongest speeds likely to occur beyond 30 nm, with a more east
component closer to shore. There is slightly lower confidence
that gale force gusts will occur at buoys 029 and 050. Wind speeds
gradually diminish overnight and Tue, but expect small craft
advisory speeds over all waters.
Wind speeds ramp up again beginning Tue night as another deep low
develops in the NE Pac. This low is forecast to have a center around
960 mb 12Z Wed near 45N 142W. The NAM is much weaker, but the low
development is near the edge of the NAM outer boundary. By 00Z
Thu the low center moves to about 48N 135W. Expect solid gale
force wind to develop in the outer waters 12Z-18Z Wed and then
spread to the inner waters by the afternoon. The GFS indicates a
core of 45-55 kt boundary layer wind speeds over the outer waters
by 21Z Wed. Believe the GFS may be a little strong with its wind
field, therefore went with a blend of the ECMWF and GFS. Models
show more variance beyond Fri and leaned toward the ECMWF. This
implies sub gale-force wind Fri and Sat, with a potential return
to gale force wind Sunday.
Seas have been slow to respond early this afternoon, but still
expect a gradual increase to the mid to upper teens after 00Z
Tue. Seas gradually ease to the lower teens by Tuesday morning.
The biggest forecast question will be wave heights late Wed night
and Thu with the next deepening low. The latest ENP guidance has
come in a little lower with its maximum wave height core. This
latest run develops a bullseye of around 48 ft at 46N 134W 06Z
Thu. This is about 3 ft lower than its previous run. This decays
to around 30 ft over the inner waters 18Z Thu. Did not go that
robust just yet and went closer to the ECMWF guidance. Seas
diminish significantly Fri, but will remain at least 15-20 ft
into Sun. Seas likely to exceed 20 ft again Sat night and Sun.
Weishaar
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
PZ...Gale Warning until 10 PM PST this evening for Waters from Cape
Shoalwater WA to Florence OR from 10 to 60 NM.
Small Craft Advisory until 4 AM PST Tuesday for Coastal Waters
from Cape Shoalwater WA to Florence OR out 10 NM.
Small Craft Advisory for Rough Columbia River Bar until 10 PM
PST Tuesday.
&&
$$
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This discussion is for Northwest Oregon and Southwest Washington
from the Cascade crest to 60 nautical miles offshore. This area is
commonly referred to as the CWA, or forecast area.
Area Forecast Discussion
National Weather Service San Angelo TX
605 PM CST Mon Jan 15 2018
.AVIATION...
/00Z TAFS/
Look for very challenging flight weather to dominate West Central
Texas, through at least 12Z to 15Z tomorrow. A strong Arctic cold
front has just moved south of the San Angelo terminal. This front
is producing winds from the north around 25 knots, with gusts near
35 knots. Short term models continue to indicate mainly sleet or
light snow. The Abilene and San Angelo terminals will likely
receive small accumulations of one or two tenths of an inch or
less. The Sonora, Junction, and Brady terminals may receive sleet
or snow accumulations around one quarter inch. By 18Z, expect VFR
conditions at all terminals.
&&
.PREV DISCUSSION... /issued 241 PM CST Mon Jan 15 2018/
SHORT TERM...
(Tonight and Tuesday)
Arctic front has made it to I-20 as of mid afternoon, switching
winds around to the north. Coldest air lingers to the north a
little, as an area of low cloudiness shifts south across the South
Plains and Red River Valley. Temperatures are falling to freezing
across Oklahoma and are well down into the teens across Kansas so the
cold air is on schedule to arrive this evening and overnight.
Models with the best low level resolution like the NAM and HRRR
continue to show light precipitation starting across the area by mid
evening north of the front and continuing through the early morning
hours. Still appears to be a mixture of light freezing rain and
sleet. For much of the area, totals will be light and impacts will
be fairly small and consists of some icy spots on bridges and
overpasses. A little different story down across the southeast
counties from Brady and San Saba down to Mason and Junction. Wintry
precipitation looks to be more widespread, and impacts could be a
little more significant. Again, freezing rain and sleet look the
most likely based on soundings, although a changeover to a little
snow is possible after 12Z Tuesday morning. Will continue with the
Winter Storm Warning in those areas.
Skies may clear a little quicker on Tuesday afternoon from the
north, enough perhaps to see a little more sunshine. Temperatures
may actually climb above freezing across the northern Big Country,
with other areas seeing readings close to the 30 degree mark.
LONG TERM...
(Tuesday night through Monday)
Surface high pressure will build into North Texas resulting in light
winds and clearing skies across West Central Texas. Cloud cover may
linger across the Interstate 10 corridor, although most of the cloud
cover should shift south by sunrise. These factors in combination
with very dry air (dewpoint temperatures near 0 for much of the
area) will result in good radiational cooling conditions. Very cold
temperatures are forecast Wednesday morning, with most locations
dropping into the teens. A few low lying locations may drop into the
single digits. After a very cold start to the morning, afternoon
highs will warm into the mid to upper 30s for most locations. Good
radiational cooling conditions are once again forecast Thursday
morning, with most locations bottoming out in the low to mid 20s.
An upper level shortwave trough will swing across the region late
Wednesday night into Thursday morning. At this point, most of the
light precipitation associated with this feature looks to remain
south of our area, so have kept PoPs out of the forecast.
A slow warm up is expected Thursday through Saturday, with highs on
Thursday in the mid 40s to near 50 degrees and getting back into the
60s on Friday. Above normal temperatures are forecast on Saturday,
with highs in the upper 60s to lower 70s for most locations. The
next upper level storm system will approach the forecast area late
Saturday into Sunday, sending a Pacific cold front through the
region on Sunday. Isolated showers will be possible along the
front across our eastern counties, where the better moisture will
reside. Cooler temperatures are in store for Sunday and Monday,
with highs mainly in the upper 50s to lower 60s.
&&
.PRELIMINARY POINT TEMPS/POPS...
Abilene 20 31 12 37 / 30 10 0 0
San Angelo 22 30 16 39 / 40 20 5 5
Junction 22 25 17 37 / 70 40 5 5
Brownwood 21 31 13 36 / 60 20 0 0
Sweetwater 20 31 16 37 / 20 5 0 0
Ozona 23 30 19 37 / 60 30 5 5
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until noon CST Tuesday for Brown-
Callahan-Coke-Coleman-Concho-Crockett-Irion-Runnels-Schleicher-
Shackelford-Taylor-Tom Green.
Winter Storm Warning from midnight tonight to noon CST Tuesday
for Kimble-Mason-McCulloch-Menard-San Saba-Sutton.
&&
$$