Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/14/17
Area Forecast Discussion
National Weather Service Columbia SC
1009 PM EST Fri Jan 13 2017
.SYNOPSIS...
A backdoor front will move into the region tonight and Saturday
and provide a slight chance of showers through early next week.
A front will bring showers and possible thunderstorms late
Wednesday and Thursday.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
Surface high pressure will continue to build into the
Northeastern US overnight while a back door cold front drops
south into the area. Convergence near the front along with weak
isentropic lift over the boundary may produce light showers in
the northern Midlands. However, the HRRR keeps most of the
shower activity further north. Low stratus is expected to
develop tonight through Saturday morning. With increased
moisture along the frontal boundary and shallow, cool air
pushing into the CSRA, areas of fog are also expected to
develop tonight across the CSRA. Winds will be light.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/...
Front will continue to back door into our forecast area (FA)
Saturday, bringing some cooler temps, mainly north and central
FA, with slight chance showers mainly north and mainly early.
Temperatures Saturday will range from the lower 50s near the
NC/SC border to the upper 60s southern Midlands/CSRA. Weak low-
level wedge appears could gradually erode Sunday as another
boundary shifts SE and appears to back door either into our
region or possibly remain just to our NE. The shower chance
appears minimal with only weak isentropic lift and not much
upper energy. Followed guidance blend on most elements.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
High pressure surface and aloft appears to provide fair and
warm conditions Monday and Tuesday. Latest GFS continues to
indicate significant moisture late Wed night thru Fri, as a
series of upper disturbances roll through. Will continue mention
of slight chance thunder to accompany the shower chances with
indications of considerable low level jet and sufficient
instability.
&&
.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
The backdoor front will push through the area late tonight and
early Saturday. Nocturnal cooling and moisture convergence ahead
of the front will help support stratus and fog late. Stratus and
fog will likely persist behind the front during the rest of the
TAF period. Leaned toward the GFS LAMP for the timing of
developing MVFR and IFR conditions late tonight and early
Saturday morning. Convergence along the front may also help
support drizzle. There may be slight diurnal improvement late
in the morning and early afternoon, but uncertainty is high
because of model inconsistency. Followed the more optimistic
NAM MOS because of h85 westerly flow and forecasted IFR
conditions becoming low-end MVFR. Variable wind will become
light northeast behind the front.
EXTENDED AVIATION OUTLOOK...A stationary front near the area
Sunday and Monday will likely become a warm front and lift
north of the region Tuesday. A cold front is forecast to move
into the area Wednesday. The pattern supports possible
widespread stratus and fog especially during the early morning
hours Sunday through Tuesday. Showers associated with the cold
front may bring restrictions Wednesday.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
&&
$$
SYNOPSIS...99
NEAR TERM...99
SHORT TERM...99
LONG TERM...99
AVIATION...99
Area Forecast Discussion
National Weather Service Charleston SC
932 PM EST Fri Jan 13 2017
.SYNOPSIS...
High pressure to the north will persist through the weekend
before shifting offshore and lingering through late next week. A
weak cold front could impact the area for the middle portion of
the week.
&&
.NEAR TERM /THROUGH SATURDAY/...
As of 915 PM: Latest satellite and sfc observations indicate
that the backdoor cold front was located near of the NC/SC
state line. In fact, KLTX radar detected a fine line associated
with the front, the boundary was sliding SW at 20 kts. Based on
the observations, it appears that the front is outpacing the
HRRR by nearly two hours. At the current pace, the front would
reach Charleston and Berkeley Counties around 7Z. Recent
guidance indicates that the front will begin to stall within the
lower Savannah River Valley. I will update the forecast to
adjust sky and winds to the latest frontal timing.
As of 650 PM: Satellite and sfc observations indicated that a
backdoor cold front will located west to east across Raleigh, NC.
This front should drive southwest tonight, expected to reach
Charleston and Berkeley Counties by 9z. Forecast soundings appears
quite moist below 4 kft after the front. I will increase the sky
cover and adjust timing of BKN sky. In addition, I will adjust the
wind shift associated with the backdoor cold front to align with
latest high resolution guidance.
&&
.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
Confluence aloft will drive a back door type cold front across
SC early Saturday, sinking south of Savannah, GA by late
morning. Although cloud cover will likely increase along and
behind this feature, the column remains quite dry with PWATS
only of 0.6-0.7 inches, and thus rainfall is not expected minus
an isolated shower or sprinkle. This front will waver across GA
Saturday into Sunday as the mid-level ridge gets suppressed, but
will then wash out during Sunday thanks to increasing
diffluence and rising thicknesses the latter half of the
weekend.
The toughest portion of this forecast then involves just how far
south the front will slip, and whether the southern zones will cool
much at all. WPC favors the front pushing south of Savannah, but MOS
numbers suggest continued well above normal temps both days that far
south. While Sunday`s forecast is easier - above normal everywhere
as the front weakens, Saturday`s temps are more tricky. Will use a
blend for temps Saturday, which create temps continued well above
seasonable norms well south, despite a shift in winds to the NE.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
Deep high pressure to prevail A powerful upper ridge will remain
over the area into Wednesday before breaking down as an upper trough
and associated surface cold front approach from the west. The front
looks to weaken as it nears but it will likely lead to an increase
in rain chances toward mid week as some deeper moisture moves into
the area. Unseasonably warm temperatures will persist through
Friday.
&&
.AVIATION /02Z SATURDAY THROUGH WEDNESDAY/...
As of 650 PM: Satellite and sfc observations indicated that a
backdoor cold front will located west to east across Raleigh, NC.
This front should drive southwest tonight, expected to reach
Charleston and Berkeley Counties by 9z. The front is forecast to
pass KCHS around 11z, possibly reaching KSAV during the mid morning
hours, resulting in light NE winds. The primary forecast challenge
will be the placement and timing of restrictive stratucu behind the
front. Using CONSShort and forecast soundings, I will TEMPO MVFR
ceilings between 11Z to 15Z. KSAV is expected to remain south of the
restrictive ceiling deck. However, both terminals should see
gradually increasing ENE winds through the daylight hours, with
cloud decks near MVFR levels.
Extended Aviation Outlook: VFR conditions should generally prevail
through Tuesday, although flight restrictions will be possible each
morning at KCHS/KSAV due to low clouds and/or fog. A cold front
could bring some showers on Wednesday.
&&
.MARINE...
Light winds this afternoon and overnight will keep in only the 5
to 10 kt range, with seas of around 2 or 3 ft. Exception will be
for AMZ374, where higher swells will bump seas up into the 3 to
5 ft range.
Saturday through Wednesday:
Gusty NE winds of 10-15 kts will envelop the waters Saturday as
a back door cold front slides southward and stalls across GA.
This front will wash out during Sunday allowing the gradient to
relax, and while subtle shifts in wind direction are possible, a
predominant NE wind will persist with speeds falling to 5-10
kts. Highest seas will occur during the strongest winds the
first half of Saturday, reaching 3-4 ft, and will otherwise be
rather placid at around 2 ft.
Another tightening of the gradient is likely on Monday with an
associated increase in winds/seas but again no Advisories are
expected. A coastal trough could move in and/or set up Monday
night as high pressure to the north slides east into the
Atlantic before southerly winds and seas increase toward mid
week with the approach of a weak cold front.
&&
.TIDES/COASTAL FLOODING...
Due to the a perigean full moon tide cycle, tides may approach
7 ft MLLW along the SC coast Saturday morning potentially
requiring an advisory.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...None.
&&
$$
NEAR TERM...NED
SHORT TERM...ILM
LONG TERM...ILM
AVIATION...NED
MARINE...ILM
TIDES/COASTAL FLOODING...
Area Forecast Discussion
National Weather Service Quad Cities IA IL
931 PM CST Fri Jan 13 2017
.UPDATE...
Issued at 920 PM CST Fri Jan 13 2017
Watching expansive area of precipitation over portions of E KS and
W MO near to south of KC metro. Isentropic lift on 305K sfc
depicts this current precip well, and supports this lifting across
the far southern cwa after 07z through 12z. Have increased pops
and expanded northward to near Fairfield, IA to Princeton, IL axis
overnight. Overall the setup doesn`t look to dissimilar from a few
nights ago when we had convection streaming across these same
locations. What is different is moisture and magnitude of
transport nowhere near as impressive for much, if any thunder.
Nonetheless, still fairly steep mid level lapse rates within
strong mid level baroclinic zone for likelihood of scattered
showers with brief bursts of sleet and freezing rain potentially
leading to slick conditions over portions of southeast IA, northeast
MO into west central IL.
&&
.SYNOPSIS...
Issued at 315 PM CST Fri Jan 13 2017
18Z surface data had arctic high pressure over the western Great
Lakes with a frontal boundary from Texas into the Tennessee Valley.
Dew points were in the single digits above and below zero from the
northern and central Plains into the western Great Lakes. Dew points
in the teens and higher ran from the Great Lakes to the Gulf coast.
&&
.SHORT TERM...(This Evening through Saturday)
ISSUED AT 315 PM CST Fri Jan 13 2017
Quiet and dry conditions will be seen through sunset and into the
early evening hours. The exception will be in the highway 20
corridor which might see some isolated flurries with a passing
disturbance. Attention then turns to later tonight and Saturday.
The morning balloon data showed a large and deep layer of cold, dry
air across the area. Moisture will start surging into the area late
this evening and overnight that will slowly moisten the dry layer at
the surface.
Based on trends from the RAP model, moisture will be slow to arrive
this evening. Thus dry conditions are expected through midnight.
There will likely be returns on the radar develop this evening.
However, these returns will be clouds developing and/or virga.
After midnight, the first wave will move from Missouri into southern
Illinois. Per the RAP trends, the lower atmosphere slowly saturates.
However, there is a large area of dry air above the fairly shallow
moist layer. Additionally, the moist layer ends when temperatures
get just above freezing aloft.
Given this information, there are questions regarding the potential
for precipitation occurring late tonight and into Saturday morning.
Right now it appears that there is a low risk for a mix of sleet and
possibly freezing rain south of a line from Galesburg, IL to just
north of Memphis, MO.
The cold temperatures and the depth of the cold air at the surface
brings the possibility for the lower atmosphere to cool as
precipitation begins. If this occurs, then the precipitation could
be a mixture of sleet and snow.
If there is any ice accumulation tonight, areas south of a Macomb,
IL to Bible Grove, MO line would have the best chances of seeing a
very light glaze.
On Saturday, any lingering sleet, freezing rain, or snow in the far
southern areas will end during the morning hours followed by
temperatures climbing to around freezing. The remainder of the area
will see dry conditions.
.LONG TERM...(Saturday Night through Friday)
ISSUED AT 315 PM CST Fri Jan 13 2017
Focus remains centered on the slow moving winter storm system that
will lift through the area Monday and Tuesday. Latest model runs
demonstrate critical differences in the timing and track of the
surface low and exhibit an overall slowing trend over previous runs.
Thus forecast confidence remains low and no changes were made to the
winter storm watch headlines in place for Sunday into Monday
morning.
Overall, the ECMWF is more progressive with precipiation breaking
out in the south late Saturday night, then becomes a slower, and
more westerly outlier with the surface low tracking through central
IA Monday night into Tuesday. The GFS and Canadian are faster with
the low lifting out and also trend further east, passing over
eastern IA/NW IL Mon night, reaching into lower MI Tuesday. Will
continue with a low confidence blend for now, with the overall
signal still showing freezing rain/sleet and possible light snow at
the onset Sunday, changing the mix to all rain from south to north
with the strong warm/moist advection and passing warm sector Sunday
night through Monday morning.
Saturday night: A cold and dry low level airmass remains in place
associated with a 1034 mb plus high over southern MN/SW WI under a
weakly confluent upper flow. The ECMWF remains the most progressive
suggesting precipitation breaking out in the south by 12Z Sunday,
while the more likely scenario suggests the northward advancing
precipitation will stay to the south as the weak low level east to
northeast flow continues a feed of dry air under weak forcing. Thus
have only slight chance pops in the far south with low temperatures
in the teens to low 20s.
Little changes made to the main event Sunday and beyond with light
ice accumulations of a tenth to possibly near a quarter inch in the
far south/southwest before the changeover to all rain occurs late
Sunday night through Monday morning. Latest models suggest areas
north of I-80 may not see the mixed precipitation begin until Sunday
evening. If current model trends continue, Sunday through Sunday
evening timeframe would pose the greatest risk for ice accumulations
in the south, while the late Sunday night and Monday periods may be
at most risk for sleet and ice accumulations central and north.
This is especially true if the slower, more westerly solutions bear
out, keeping a low level feed of cold, dry air from under the
exiting ridge into the area, under the deepening warm, moist
advection aloft and stronger upper level forcing. Temperatures
climbing into the 30s and 40s from late Monday through Tuesday
should then quickly melt any accumulations.
Tuesday night and beyond looks dry with above normal temperatures
under a split flow aloft that keeps arctic air bottled up well to
the north.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday Evening)
ISSUED AT 537 PM CST Fri Jan 13 2017
Main concern tonight is the potential for pockets of lower MVFR
cigs to develop at the terminals, as 925 mb winds turn e/se and
attempt to advect pockets of low clouds and cigs 1200-1800 ft agl
into the terminals from central IL. The MVFR cigs are fairly
spotty and not widespread thus making confidence lower on
occurrence. As a result, I have kept the TAFs all VFR through the
period hinting at lower cloud potential with scattered MVFR bases
mid evening into the overnight. Any MVFR cigs would appear to be
fairly short-lived as 925 mb winds turn westerly late tonight,
which would bring in drier air and shunt any lower cigs east of
the terminals. Will continue to assess ob trends and amend if needed.
E/NE winds around 5-10 kts will turn from N/NW on Saturday as
reinforcing high pressure builds into the Upper Midwest.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...Winter Storm Watch from Sunday afternoon through Monday morning
for Benton-Buchanan-Cedar-Clinton-Delaware-Dubuque-Iowa-
Jackson-Johnson-Jones-Linn-Muscatine-Scott.
Winter Storm Watch from Sunday morning through late Sunday night
for Des Moines-Henry IA-Jefferson-Keokuk-Lee-Louisa-Van
Buren-Washington.
IL...Winter Storm Watch from Sunday afternoon through Monday morning
for Henry IL-Rock Island.
Winter Storm Watch from Sunday morning through late Sunday night
for Hancock-Henderson-McDonough-Mercer-Warren.
MO...Winter Storm Watch from Sunday morning through late Sunday night
for Clark-Scotland.
&&
$$
UPDATE...McClure
SYNOPSIS...08
SHORT TERM...08
LONG TERM...Sheets
AVIATION...McClure
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
836 PM CST Fri Jan 13 2017
.UPDATE...
The dense cold airmass over North TX continues to spill deeper into
the Northern Hill Country and Central TX, with the southernmost surge
reaching just past ABIA at 8 pm. The next several hours will be
tricky as at some point the front will be upended by the increasing
nocturnal southerlies in advance of the approaching upper low. Early
evening indications might suggest that the most aggressive NAM may be
the winning model, but have blended in some more conservative RAP
data through noon tomorrow. Main impacts to the overall forecast is
earlier cooling near the front and overnight lows about 5-8 degrees
cooler along and 20 miles inside the frontal zone. No attempts were
made to speculate on any impacts the frontal surge will have on highs
Saturday as radar velocity data shows the frontal inversion to be
very shallow.
&&
.PREV DISCUSSION... /ISSUED 558 PM CST Fri Jan 13 2017/
AVIATION... /00Z TAFS/
The slow moving shallow cold front will be the main challenge to
impact the TAF periods, especially at AUS where radar imagery
suggests the boundary entering the northern 5 mile vcnty ring.
Conditions around AUS could thus vary greatly through the next 12 to
18 hours with a slightly higher presence of light shower activity
than the other taf locations. Prevailing ifr conditions are expected
south of the front for all sites for much of the late evening and
early morning hours. Close to daybreak, skies could drop into lifr
categories, especially at AUS, with showers expected to increase
mainly from 08z to 18z. Mixing should be a gradual process, but will
continue with a slightly more optimistic than model guidance trends
for vfr skies by around 21Z. The front is expected to mix northward
to no longer impact TAF sites by 21Z, but a slightly more easterly
wind may result from the modified pressure fields. This could lead to
lower cigs and more shower activity in TAF updates, as some of the
finer resolution models show more frontal influence east of I-35.
PREV DISCUSSION... /ISSUED 331 PM CST Fri Jan 13 2017/
SHORT TERM (Tonight through Saturday Night)...
The boundary of the shallow cold front has progressed very slowly
southward this afternoon as evident off GRK radar and area surface
observations. The front is just south of a Llano to Georgetown line.
Have followed closer to the RAP and NAM12 over the next 12-18 hours
with the front, and some additional southward progression is possible
tonight before the front moves back north Saturday afternoon. High
temperatures will be tricky for northern areas Saturday, depending on
how far south the front. A continued warm night for most of the area
south of the front. Isolated to widely scattered showers will be
possible through the short term.
LONG TERM (Sunday through Friday)...
An upper level low will lift northeast out of Mexico into far West
Texas on Sunday and then north through the Panhandle and into Kansas
Sunday night and Monday. Large scale ascent will overspread the
western CWA Sunday afternoon with the approach of the low. Showers
and thunderstorms are expected to develop across the western CWA as
the ascent overspreads the area and interacts with an eastward
advancing Pacific cold front. CAPE values of around 1000 j/kg and
deep layer shear of 40-50 kts should support a strong to severe
threat as the storms develop Sunday afternoon. The severe threat
should continue east into the central CWA Sunday evening as the front
progresses east. A 40-50 kt low level jet and 0-1KM SRH values of
200-300 m^2/s^2 will support a threat for an isolated tornado risk
Sunday afternoon and night. In addition, as the upper level low
lifts more northeast to north the mean flow becomes more parallel to
the front. This in combination of PW vales up to 1.4" could support a
threat for locally heavy rainfall across central and eastern
counties Sunday night into Monday morning.
Eventually the front slides through eastern counties Monday evening.
As the upper level low opens and ejects north additional energy digs
back into the base of the trough Monday into Tuesday. This may
continue a chance for rainfall Monday night through Tuesday.
&&
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 57 72 60 74 62 / 20 30 20 50 80
Austin Bergstrom Intl Airport 60 73 61 75 62 / 20 30 20 40 80
New Braunfels Muni Airport 63 75 61 75 63 / 20 20 20 40 70
Burnet Muni Airport 51 68 58 70 58 / 30 30 20 60 90
Del Rio Intl Airport 65 74 63 74 53 / 50 30 40 60 60
Georgetown Muni Airport 51 70 58 72 60 / 30 30 20 50 90
Hondo Muni Airport 65 75 62 75 61 / 30 30 20 50 70
San Marcos Muni Airport 63 74 61 76 63 / 20 30 20 40 70
La Grange - Fayette Regional 64 76 62 75 65 / 20 20 20 30 50
San Antonio Intl Airport 65 75 62 75 62 / 20 30 20 50 70
Stinson Muni Airport 67 77 63 76 64 / 20 30 20 50 60
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Mesoscale/Aviation...Allen
Synoptic/Grids...Oaks
Public Service/Data Collection...30
Area Forecast Discussion
National Weather Service Fort Worth TX
743 PM CST Fri Jan 13 2017
.UPDATE...
The shallow cold airmass in place on the north side of an arctic
front resides below 925 mb and continues to be a challenge for
guidance. The boundary continues to sag south over Central TX and
may not begin to lift back to the north until tomorrow. The HRRR
seems to be doing a respectable job with the shallow frontal
layer, eventually stalling the boundary late this evening and
keeping it quasi-stationary along the southeast border of the CWA
through much of Saturday morning. Some changes to the temperature
forecasts were required based on the expected position of the
front.
Temperatures will be kept fairly steady overnight, with an
increasing trend beginning mid to late morning Saturday. The good
news is that even if it cools another couple of degrees tonight,
all precipitation across the CWA overnight should still remain in
liquid form. We will need to keep an eye on the northwestern-most
counties where some lower and middle 30s are being reported, but
since precip is falling through such a large warm layer, even if a
few spots dropped to 30-32 degrees there would likely only be
minor accumulations on elevated surfaces.
30
&&
.AVIATION...
/ISSUED 610 PM CST Fri Jan 13 2017/
A frontal boundary extended south of a KF44 (Athens) to KT35
(Cameron) to KGTU (Georgetown) line as of 23Z (5 PM CST). As can
be seen on the KGRK radar, this boundary is continuing to slowly
move southward. Expect north flow to prevail at all of the TAF
sites for the next 36 hours. All of the TAF sites are already IFR
and some LIFR conditions are possible overnight and Saturday
morning. Areas of fog and patchy drizzle are possible through
Saturday. Scattered showers are expected mainly during the
afternoon and evening Saturday and an isolated thunderstorm will
be possible. More widespread showers and thunderstorms are
expected Sunday.
58
&&
.PREV DISCUSSION... /ISSUED 400 PM CST Fri Jan 13 2017/
Two distinct airmasses are currently in place across Texas this
afternoon with a nearly stationary frontal boundary marking the
transition from warm and humid to cold and damp. At this hour the
front is ever so slowly continuing to slide south as indicated by
the Granger radar with the boundary located across the northern
half of Milam county. The front stretches northeast from there and
is very near Athens then extends to just south of Texarkana. North
of the front...temperatures are in the 30s and 40s with north
winds and areas of light rain and drizzle. South of the front...
temperatures are in the 70s and 80s.
The cold front is very shallow across North Texas with the 12Z
Fort Worth sounding showing a depth of only around 1000 feet.
Southerly winds are noted on both the Granger and Fort Worth VAD
wind profiles at 2000 feet. This low level warm moist advection
above the cooler surface air has resulted in an area of light to
moderate rain and drizzle which continues to move north through
the area this afternoon. This initial wave of ascent and moisture
advection will continue northward through this evening and we
should see a gradual decrease in the coverage of precipitation
through tonight. PoPs will be highest generally along and north of
I-20. Surface observations show that temperatures are in the upper
20s and lower 30s across central and southern Oklahoma with mid
30s across our northwest counties. There is some weak surface cold
advection but this should become neutral later this evening. With
strong southerly winds above the shallow front...the front itself
should become completely stationary or may begin to drift back to
the north slowly. Overnight temperatures are likely not to cool
much more...and may even rise a couple of degrees overnight.
Concerning any potential freezing rain in our area...temperatures
are unlikely to fall to or below freezing anywhere in our area
given the lack of more robust low level cold advection so no
wintry precipitation is expected.
On Saturday...the frontal boundary will continue to lift north and
will continue to be modified by warm southerly flow. Moderate
warm advection will continue although it does appear that some dry
air will impinge upon the area from the east late in the day. This
should generally keep rain chances lower than today. There will be
sufficient moisture across our northwest counties to support some
slightly higher rain chances.
By Saturday night into early Sunday morning...the powerful upper
low over the southwest will be approaching far west Texas. This
will allow a surface low to develop across west Texas and low
level flow across our area to strengthen and back to the
southeast. Large scale forcing for ascent will increase through
the day Sunday with widespread showers and a few thunderstorms
developing across west Texas. Areas west of I-35 will have the
best rain chances late Sunday with a line of showers and
thunderstorms moving across the rest of North Texas on Sunday
night. PoPs will be near 100% Sunday night into early Monday
morning across the region...with most areas picking up more than
an inch of rainfall. There will be a threat for locally heavy
rainfall in some areas...especially east of I-35 through Monday
but the overall flash flood threat appears low at this time given
that the main line of convection is expected to move through
rather quickly.
Concerning the severe weather potential... As the upper low gets
closer Sunday night...wind fields will strengthen resulting in
large curved hodographs indicative of impressive 0-1 and 0-3km
shear values across North Texas. This occurs as a strongly forced
line of convection moves through the region. The major limiting
factor to a more impressive severe weather setup is the lack of
any substantial low level instability. Forecast soundings from the
most aggressive guidance indicates MUCAPE of around 500-700 J/kg
however most of this seems to be the result of steepening lapse
rates with the approach of the upper low. Very little instability
is noted in the 0-3km layer which suggests a limited severe
weather threat at this time. So...given the strong shear
profiles...there will be an isolated tornado threat with the more
robust updrafts...but at this time a widespread severe weather
event does not appear likely. We will continue to monitor this
over the next day.
Precipitation should end from west to east during the day on
Monday with cooler temperatures filtering into the area on
Tuesday. A lingering piece of shortwave energy will spread over
the area Tuesday night with continued low rain chances.
Dunn
&&
.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth 40 60 53 67 56 / 30 30 20 40 100
Waco 44 67 57 70 59 / 30 20 20 50 100
Paris 46 61 54 68 59 / 40 30 20 20 90
Denton 39 55 51 65 52 / 40 40 20 50 100
McKinney 41 59 52 66 56 / 30 30 20 30 100
Dallas 41 61 55 68 58 / 30 30 20 40 100
Terrell 45 65 55 68 59 / 30 20 20 30 100
Corsicana 47 69 56 71 60 / 20 20 20 30 100
Temple 47 69 58 71 59 / 30 20 20 50 100
Mineral Wells 37 56 51 65 49 / 40 40 20 70 100
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
58/30
Area Forecast Discussion
National Weather Service Lincoln IL
906 PM CST Fri Jan 13 2017
.UPDATE...
Issued at 855 PM CST Fri Jan 13 2017
No major changes to going forecast and headlines this evening.
First wave of rain and freezing rain has shifted into extreme
southeast Illinois and should move out of our area over the
next hour. Our attention now turns to another band of freezing
rain that is forecast to track out of Missouri late tonight
and into our area after 08z and continue on and off through
the morning before the precip starts to get shunted to our
southeast in the afternoon. RAP/HRRR/and latest NAM showing this
wave for the early morning hours tracking further north than our
initial wave that focused in areas south of I-72 today. Model
consensus suggests a tenth to locally two tenths of an inch
may occur with this second wave, especially along a Taylorville
to Mattoon to Paris line with lighter amounts, generally less
than a tenth of an inch up to the I-74 corridor with the trend
for trace amounts further north. As mentioned above, the precip
should push out of most of the area, except the far southeast
by afternoon. By that time, it appears our surface temperatures
may be close to our just above the freezing mark which should
melt any additional ice the falls Saturday morning.
Have bumped the POPs up further north to reflect the northward
trend in models with the next wave of freezing rain. We should
have the updated ZFP out by 915 pm.
&&
.SHORT TERM...(This evening through Saturday)
ISSUED AT 258 PM CST Fri Jan 13 2017
Will change the winter storm watch over central part of CWA to a
freezing rain advisory tonight through Sunday morning. So a freezing
rain advisory will be in effect from Schuyler, Mason, Logan, DeWitt,
Champaign and Vermilion counties southward. Winter Storm watch
continues north of there from midnight Sat night thru Sunday night.
A frontal boundary over southeast TN into southern AR and central
Texas was causing overrunning of light freezing rain and sleet into
areas south of Taylorville to Paris line at mid afternoon where
temperatures were mostly 30-32F with Lawrenceville up to 33F. Colder
temperatures in the mid to upper 20s north of Lincoln. Mostly cloudy
to overcast skies over CWA at mid afternoon. Strong 1045 mb arctic
high pressure over central WI and sprawled across the Great Lakes
region was giving a ne flow of cold air into central IL.
Still some forecast model differences with handing qpf fields
through Saturday even with the short range/high resolution models.
The HRRR models has area of light freezing rain and sleet
diminishing over southeast IL by 03Z/9 pm this evening with just a
few smaller patches of light qpf thereafter as far north as Canton
and Bloomington. The RAP13 model also diminishing mixed pcpn over
southeast IL but not until late evening and then develops expanding
area of light qpf after 2 am from Peoria south. The NAM12 model
diminishing light qpf in southeast IL early this evening, and then
spreads/develops light qpf ne toward I-72 during overnight. With
stronger arctic high pressure nearby over WI, will keep northern CWA
drier tonight into Saturday. Will bring chance of light freezing
rain northward into central CWA during the evening with likely pops
in southeast IL. Models then diminish qpf from nw to se during
Saturday especially north of I-70. Light rain will also becoming
more likely in southeast IL by Saturday Saturday afternoon. Ice
accumulations up to a tenth inch from I-72 south tonight into Sat
morning (locally one to two tenths along I-70) with less amounts se
of I-70 due to milder air and also north of I-72 in drier air. Lows
tonight range from lower 20s nw of IL river, to 30-32F in southeast
IL from I-70 south. Highs Saturday range from lower 30s north of I-
72 to 35-37F in southeast IL. ENE winds will stay fairly light
during this weekend.
.LONG TERM...(Saturday night through Friday)
ISSUED AT 258 PM CST Fri Jan 13 2017
A lull in the freezing rain threat will exist at the beginning of
the forecast period across most of the forecast area, with the
better chances just to our west/south across Missouri and far
southern Illinois. Our attention to start next week turns to the
vigorous upper low that is currently spinning off the southern
California coast. This feature will eject northeast toward the area
Sunday into Monday, accompanied by a surface low and more widespread
precipitation than is in our vicinity right now.
The initial surge of precipitation associated with the southwest
system will arrive late Saturday night into Sunday. Initially, our
local surface temperatures will be cold enough for freezing rain. As
the precipitation returns, moisture depth is too shallow/warm for ice
crystals, so freezing rain is expected at the onset. Then, as deeper
moisture and cloud ice returns, a period of sleet/snow is possible.
However, the sleet and/or snow should not last long as a deeper
elevated warm layer develops. This signals a south to north return
to freezing rain on Sunday into Sunday night. However, as surface
winds turn more southerly later Sunday into Monday, temperatures
will warm enough for rain. This system does not exit the area until
later Tuesday, and rain chances will linger until the system departs.
Hazardous travel condtions are expected from time to time into
Monday with the periods of freezing rain anticipated. However, a
significant ice storm does not look likely due to the relatively low
rainfall amounts that occur with sub-freezing temperatures, as well
as the diurnal melting that could occur in many areas on trees and
power lines.
Once the current system finally leaves the area early next week, the
rest of the week should be fairly quiet weather wise with warmer than
normal temperatures.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 535 PM CST Fri Jan 13 2017
Initial wave of freezing rain was located just south of SPI and
DEC early this evening with a temporary lull in the precip further
west and south. We expect light freezing rain to develop over
central Mo after 04z and spread into parts of central IL after 08z
and be with us for about a 6 to 8 hour period before all the
precip gets shunted to the south by afternoon. We should also see
a gradual deterioration in the cigs later this evening from south
to north, although some MVFR cigs pushed into PIA and BMI earlier
today from the northeast. Further north towards I-74 there is
quite a bit of dry air in the low levels so any precip to our
south should stay to the south thru the evening with the threat
for precip shifting closer to our northern TAF sites Saturday
morning. Most areas should see IFR cigs with some lower vsbys in
fog as well as we head thru the morning on Saturday with some
improvement in cigs/vsbys during the afternoon, but still looking
like mainly MVFR conditions at that time. Winds will be northeast
to east at 8 to 15 kts tonight and then back more into a north to
northwest direction on Saturday with speeds of 5 to 10 kts.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
Freezing Rain Advisory until noon CST Sunday for ILZ040>057-
061>063-066>068-071>073.
Winter Storm Watch from late Saturday night through late Sunday
night for ILZ027>031-036>038.
&&
$$
UPDATE...Smith
SHORT TERM...07
LONG TERM...Bak
AVIATION...Smith
Area Forecast Discussion
National Weather Service Jackson MS
936 PM CST Fri Jan 13 2017
.UPDATE...
Updated for evening discussion.
&&
.DISCUSSION...
Anomalously warm weather continues across the ArkLaMiss as a 590 dam
subtropical ridge remains centered over the SE CONUS. This allowed
for two more daily record highs to fall/tie today at HBG and TVR. A
few shallow isolated showers formed this afternoon beneath a stout
mid-level inversion, but quickly dissipated. A stalled frontal
boundary remains draped across the NW portion of our CWA with current
temps as of 3z in our NW in the low 50s and even upper 40s, while the
remainder of the area remains mild with temps in the upper 50s/low
60s. For the remainder of the evening, the main forecast concern will
be the potential for areas of fog with visibilities less than 1/4
mile possible. There has been some disagreement between guidance as
to where the best fog potential will be with the HRRR and GFS hitting
the NW hard, while the NAM wants to show the best potential in the
east. Opted to go with the HRRR solution, as it is likely handling
the advection of drier air from the east the best. While some degree
of fog is still expected area wide, the best coverage will be along
the HWY 82 corridor down to TVR along the stalled frontal boundary
where moisture pooling, low dewpoint depressions, and low
condensationpressure deficit values are located. Therefore, went
ahead and issued a dense fog advisory for north and west portions of
the CWA. Right now, it appears the drier air, characteristic of low
50s/upper 40s dewpoints, will preclude greater fog coverage in the
SE, however trends in this area will be monitored and the current
dense fog advisory may have to be expanded if conditions become more
favorable for widespread fog development. Otherwise, lowered
overnight min temps, especially in the NW in the vicinity of the
stalled frontal boundary and in the east where better cooling is
expected to occur. /TW/
Prior discussion below:
Tonight through Saturday,
An anomalously warm weather pattern for the ArkLaMiss will continue
into the weekend as a strong 590 DM subtropical ridge remains
centered over the northeast Gulf of Mexico. A few showers that
developed earlier today have mostly dissipated.
The primary weather concern in the near term will be for
redevelopment of fog late tonight into Saturday morning given the
warm, moist boundary layer above the relatively cool ground. While
we are likely to see fog in most locations, there is some
uncertainty with "dense" fog development due to mixing of a shallow
surface front over the Delta region and some potential for drier air
to advect in from the east over the Pine Belt region. These
uncertainties are reflected by a variety of solutions in the high-
res near term guidance, and after coordination with surrounding
offices, have decided to hold off on a dense fog advisory. For now,
have broad brushed a limited threat for dense fog in the HWO and
will allow future shifts to better assess areas of greater dense fog
potential. Otherwise, look for any fog to burn off by late Saturday
morning with a variable amount of cloud cover to follow along with
well above normal temperatures. Slightly cooler but still above
normal temperatures associated with shallow cooler air over the
upper Delta region can be expected. /EC/
Sunday through Friday:
The remainder of the weekend should continue to be warm across the
forecast area as a low pressure system lifting northeastward out of
the High Plains strengthens warm, onshore flow across our region.
The upper-level ridge should begin to weaken slightly in advance of
the approaching upper low as we head into the new work week, but its
effects will continue to be felt with max temperatures in the mid to
upper 70s area wide on Sunday and Monday. Meanwhile a deepening
upper-level trough moving into central portions of the country, with
a series of shortwaves interacting with it through the middle of the
week. Models have continued to struggle with the finer details of
this pattern - speed and strength of the shortwaves, particularly.
Therefore confidence on how fast the overall trough axis moves
across our region remains low. A general consensus of deterministic
and ensemble guidance continues to suggest a slow moving upper
trough edging over Louisiana and Arkansas Monday night, with a cold
front slowly advancing into our western parishes counties sometime
on Tuesday.
Moisture advection ahead of this system will be concentrated along
the front, and could result in some periods of heavy rainfall for
our area. Tuesday afternoon into Tuesday night continues to look
like the favored time period for heavier rainfall somewhere in the
vicinity of the Mississippi River. Model runs today show enough slow
movement of the trough throughout the day Wednesday that any
concerns for flooding remain low. Though details are murky at this
point, models agree that the next trough will quickly move into the
western CONUs as we head into the second half of the week. Have
continued slight chance to chance POPs through the end of the
forecast to account for possible periods of showers or thunderstorms
ahead of that next trough.
&&
.AVIATION...
00Z TAF discussion:
Mostly VFR conditions are occurring this Friday evening, but GLH has
dropped to MVFR ceilings. Expect more MVFR to IFR ceilings to occur
this evening into the overnight hours. Patchy fog will again be
possible across the area with some potential for dense fog in
northern locations. Will continue to monitor and amend any TAFs if
needed, but expect the dense fog to occur closer to daybreak. /28/
&&
.PRELIMINARY POINT TEMPS/POPS...
Jackson 53 75 53 75 / 2 5 3 5
Meridian 50 75 51 75 / 1 4 3 5
Vicksburg 54 75 53 75 / 1 7 4 7
Hattiesburg 51 76 53 75 / 1 5 3 8
Natchez 56 75 55 75 / 3 6 3 10
Greenville 49 70 52 71 / 1 16 10 7
Greenwood 53 73 52 73 / 1 13 7 6
&&
.JAN WATCHES/WARNINGS/ADVISORIES...
MS...Dense Fog Advisory until 9 AM CST Saturday for MSZ018-019-
025>042-047.
LA...Dense Fog Advisory until 9 AM CST Saturday for LAZ007>009-015-
016.
AR...Dense Fog Advisory until 9 AM CST Saturday for ARZ074-075.
&&
$$
TW/NF/28/EC
AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
1005 PM EST Fri Jan 13 2017
.UPDATE...
Issued at 1005 PM EST FRI JAN 13 2017
Dense fog is setting up on the ridges of eastern Kentucky along
with development just to the southwest of the CWA - and
indications in the HRRR and CONSShort for low vis in these areas
through the night. Accordingly, have updated the forecast to
include this along with issuing an SPS in conjunction with LMK and
OHX. with this updated also fine tuned the rain chances through
the rest of the night along with a tweaking to T and Td grids per
the latest obs and trends. These have been sent to the NDFD and
web servers. Along with the SPS an update to the ZFP and HWO have
been issued.
UPDATE Issued at 745 PM EST FRI JAN 13 2017
00z sfc analysis shows the cold front through the southern portion
of the CWA with patches of rain of a scattered to numerous nature
passing through the breadth of eastern Kentucky. The amount of
moisture in the air is keeping the clouds rather low through the
night and into Saturday along with patchy fog. Currently the front
shows up quite well in the obs with temperatures varying from the
lower 50s in the far southeast to the upper 30s/low 40s north.
Dewpoints are generally within a degree or two of the dry bulb
temperatures while winds are mostly from the northeast at 5 to 10
mph. Have updated the grids through the night to reflect the
timing and placement of the PoPs across the area based on current
radar trends and consensus model guidance. Also loaded in the
latest ShortBlend temp/dewpoint guidance through 12z Saturday and
tweaked them for the current obs and trends. The updated grids -
including beefed up amounts of fog - have been sent to the NDFD
and web servers.
&&
.SHORT TERM...(This evening through Saturday night)
Issued at 316 PM EST FRI JAN 13 2017
An east to west oriented line of precipitation continues to track
across the Ohio Valley into much of central and northern Kentucky.
This will remain in the liquid phase across all of eastern Kentucky
as temperatures will hold in the mid-upper 30s across the Bluegrass
region with warmer readings farther south. This is thanks to surface
high pressure sliding across the Great Lakes and lower Canada
keeping a more substantial cold dome from building south into the
Coal Fields. Upper level features further support above freezing
surface temperatures as an upper high nudges north across the Gulf
coast into the western Atlantic with a trough traversing the St.
Lawrence Valley, allowing for today`s earlier frontal/moisture
convergence boundary to surge back north toward the Ohio River,
thus ushering warmer air back in aloft. Have gone ahead and also
inserted patchy fog into the forecast given the plethora of low
level moisture and overall light winds in place.
After a lull in the more widespread rain for a brief period tonight,
a band of precipitation will develop across the Ohio Valley early
Saturday as another upper trough skirts the western shores of Hudson
Bay, subsequently sending the frontal boundary back toward eastern
Kentucky. This will bring numerous to widespread rain showers back
in through the day. At the same time, cooler air will once again
infiltrate the Commonwealth, although temperatures near and above 40
degrees will keep only rain in the offing. In fact, temperatures
near the Tennessee border may again reach the mid 50s without a
significant southward push of colder air behind the front. Rain
chances will decrease from north to south through the evening and
overnight into Sunday morning along the front, but rain showers will
remain likely with the front in proximity to the region in
combination with a saturated airmass.
.LONG TERM...(Sunday through Friday)
Issued at 200 PM EST FRI JAN 13 2017
Very mild and damp weather will continue through next week.
To begin the period, a deep layer of low level moisture will be
in place with the frontal zone still over the region. This
will provide lots of clouds and steady temperatures from Sunday
through Monday morning. Moisture profiles are also very
supportive of a prolonged period of drizzle into Monday morning.
With this said, models continue to run too low with the rain
chances and have opted to go into the likely range for rain
chances, staying above model guidance. This is a situation, where
models are never high enough on the rain chances. Heights will
finally start to build on Monday as a sharp shortwave trough
helps to develop a strong area of low pressure across the central
plains. This will send the nagging boundary off to the north with
eastern Kentucky breaking into the warm sector. This will send
temperatures much higher into the 60s, setting up another very
warm mid January day. We could have a few spotty showers pop up
in the warm sector on Monday, most likely from the Cumberland
Plateau up across central Kentucky.
With the deep system developing out to our west, models
still showing uncertainty heading into the Tuesday and Wednesday
time period with the strength of the system likely dictating how
our weather unfolds. Either way confidence is fairly high a
frontal boundary will get pushed into the region Tuesday or
Wednesday, providing another good chance of rain. With deep
southwesterly flow in place and a frontal boundary lined up with
the flow, we will have to watch the potential for locally heavy
rain somewhere in the Ohio River Valley. Right now, models tend
to be targeting areas more in central Kentucky for heavier rain
potential, but with lots of details yet to be sorted out, this
could easily shift east or west. Certainly something to monitor
heading into next week, given the saturated ground conditions. We
may dry out Wednesday night or Thursday, but another system may
follow quickly on the heels of the midweek system. Thus, rain
chances will continue into the end of the week. One thing is for
sure, the mild weather isn`t going anywhere through the end of
next week. In fact, several more days of highs in the 60s will be
possible from Tuesday through Thursday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
ISSUED AT 700 PM EST FRI JAN 13 2017
LIFR/IFR conditions remain in place across the area, for the most
part. The band of rain across the area will continue - more off
than on - through the night and into Saturday - with more in the
way of convection expected from midday Saturday into the
afternoon. Visibilities will be variable through this time
depending on the movement and impact of the showers on each site.
Due to this, ceilings will stay IFR/LIFR through Saturday morning
and into the afternoon. Winds will be generally light from the
northeast through the period.
Note: icing concerns still look to remain north of all JKL
terminals through the weekend. Pilots flying west into the
Missouri Valley or north toward CVG/CMH need to be aware that
icing potential will greatly increase tonight into Saturday.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...GREIF
SHORT TERM...GUSEMAN
LONG TERM...KAS
AVIATION...GUSEMAN/GREIF
Area Forecast Discussion
National Weather Service Norman OK
943 PM CST Fri Jan 13 2017
.DISCUSSION...
Have made minor adjustments to temperature, rainfall/ice
accumulation, and related elements to account for the latest
observations and short-range guidance. No changes have been made
to the Warning/Advisory configuration.
The HRRR seems to be doing quite well with rainfall forecasts. As
such, it appears that the greatest rainfall in central Oklahoma
will occur around/after sunrise tomorrow, with only light amounts
overnight. Heaviest rainfall overnight and early Saturday should
occur along the wet- bulb freezing line, which will move very
little overnight, roughly from Wichita Falls to Ada to
Holdenville.
&&
.PREV DISCUSSION... /issued 559 PM CST Fri Jan 13 2017/
DISCUSSION...
AVIATION...
Freezing rain and rain will persist through Saturday over most of
Oklahoma and northern Texas. IFR conditions become common.
PREV DISCUSSION... /issued 332 PM CST Fri Jan 13 2017/
DISCUSSION...
Freezing rain and ice accumulations continue to be the questions
this forecast.
Small area of freezing rain in north central OK this afternoon
will continue to lift NE out of the area. Radars show another area
of precipitation moving into the area from Texas. This
precipitation will move into areas where temperatures are at or
near freezing leading to another round of icy weather.
Temperatures are expected to remain fairly steady tonight so areas
that are at or below freezing right now will likely remain that
way tonight. Models show another round of heavier precipitation
late tonight into Saturday morning across portions of central OK.
Where exactly this area of heavier freezing rain sets up will have
an impact on ice accumulations overnight into the morning. Right
now, the models are showing this area along or near the I-40
corridor which includes the OKC metro area. With this in mind, the
Ice Storm Warning has been extended southward and some adjustments
were made to the freezing rain advisories. Models then show
another round of heavier precipitation affecting NW/N portions of
the fa Saturday afternoon and night.
The freezing line is still expected to begin to slowly shift
northward Saturday and Saturday night so even though precipitation
chances will continue Saturday some locations will only experience
a cold rain instead of freezing rain. How soon and how quickly the
freezing line lifts could have an affect on how much ice
accumulation occurs in a location. The good news is that once
temperatures go above freezing this weekend, they will likely
remain above freezing except for maybe parts of N OK. Temperatures
are expected to warm to above freezing everywhere on Sunday.
Models show the upper low moving across the region Sunday into
Monday leading to fairly widespread rain showers and some
thunderstorms. A few strong to severe storms may also be possible
in parts of southern OK and north TX Sunday night into Monday. The
precipitation is expected to finally end on Monday. After Monday
the forecast remains dry with near or above average temperatures
next week.
&&
.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK 28 35 34 50 / 70 80 70 60
Hobart OK 27 35 34 49 / 60 80 60 80
Wichita Falls TX 30 42 40 59 / 70 70 40 80
Gage OK 25 31 29 39 / 40 90 80 80
Ponca City OK 28 33 31 46 / 50 80 80 50
Durant OK 35 47 45 62 / 50 40 30 50
&&
.OUN WATCHES/WARNINGS/ADVISORIES...
OK...Ice Storm Warning until 6 AM CST Sunday for OKZ004>020.
Freezing Rain Advisory until midnight CST tonight for OKZ032-039-
042-044-045.
Freezing Rain Advisory until 6 AM CST Saturday for OKZ031-037-
040.
Ice Storm Warning until 6 PM CST Saturday for OKZ021>030.
Freezing Rain Advisory until 6 PM CST Saturday for OKZ033>036-
038.
TX...Freezing Rain Advisory until midnight CST tonight for TXZ086>090.
Freezing Rain Advisory until 6 AM CST Saturday for TXZ083>085.
&&
$$
23/09
Area Forecast Discussion
National Weather Service Shreveport LA
950 PM CST Fri Jan 13 2017
.DISCUSSION...
At 0330z, a quasi-stationary surface front was located from
Northwest Smith County, to near Pittsburg, TX, and then generally
eastward along the Arkansas/Louisiana border. Highest rain chances
will continue to be north of Interstate 30 as precip develops
across North Texas and moves northeast. Farther south, scattered
showers have been trying to develop across Deep East Texas and
Central Louisiana in the warm sector. These showers are moving
north. These trends should continue through the overnight hours,
so no changes were made to the PoP grids. Forecast soundings
suggest the potential fog development across much of the area,
especially within the warm sector after midnight.
The HRRR appeared to have a good handle on the frontal position
and the resulting temperatures and dewpoints. Therefore, temps
were adjusted to closely follow the HRRR through the remainder of
the night.
Updated text products have been sent.
/09/
&&
.PREV DISCUSSION... /issued 922 PM CST Fri Jan 13 2017/
AVIATION...
For the 14/00Z terminal forecast period, all sites will begin with
prevailing VFR flight categories with a gradual lowering of the
bases and lowering of the visibilities to MVFR during the
overnight hours with IFR and below flight categories after
14/07Z. Parts of East and Northeast Texas and Southwest Arkansas
will be in near a frontal boundary that will aid in the
development of rain and showers. IFR/LIFR persisting through
around 14/15Z before improving to MVFR. Surface winds light East
to Southeast to prevail through the terminal forecast period with
Northeast winds 3-7 knots for Southwest and South Central Arkansas
and Western sections of East and Northeast Texas in wake of the
nearly stationary front near the Arkansas/Louisiana border to near
Gilmer texas and to the west of an Idabel Oklahoma to Tyler and
Palestine Texas line.
PREV DISCUSSION... /issued 345 PM CST Fri Jan 13 2017/
DISCUSSION...
Stalled cold front remains just along the wrn and nrn CWA
boundaries of E TX/SE OK/SW AR this afternoon. Light shwrs
continue in the warm sector, but have seen very little convection
focused along the boundary. The front is fcst to begin to move
back nwd tonight as low pressure in the plains deepens. SW flow
aloft over the top of a very unseasonably warm and moist boundary
layer will continue to allow for isold to sct shwrs through the
weekend.
Rain chances will increase into early next work week, as the upper
low off the coast of srn CA moves into W TX Monday. While this
system may pose a severe threat to areas of W and Central TX, that
threat will greatly diminish as the upper low dampens and lifts
newd over central OK. The ewd progression of the front will slow
significantly, and the loss of strong upper level support and lack
of overall instability will limit severe potential with the tstms.
Front/upper low looking a bit more progressive with this package,
which has cut down on the qpf quite a bit from earlier packages.
Rain looks to move out late Tuesday/early Wednesday, with little
to no change in airmass.
Secondary upper low will move in on the heels of the early-week
system, and will bring chances for rain back to the region for the
latter half of the work week. Models a bit inconsistent on this
feature, so stayed with conservative, low-end PoPs attm.
Unfortunately for those who enjoy seasonable January temperatures,
we will remain above normal, and in most cases well above normal,
for the entirety of the fcst pd. /12/
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 63 75 56 74 / 20 20 20 20
MLU 56 75 54 74 / 20 10 20 20
DEQ 51 64 53 67 / 50 40 30 30
TXK 52 67 54 70 / 30 30 30 20
ELD 52 70 52 71 / 30 20 20 20
TYR 55 74 57 72 / 20 20 30 20
GGG 62 74 57 72 / 20 20 30 20
LFK 63 77 59 74 / 20 10 20 20
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...None.
LA...None.
OK...None.
TX...None.
&&
$$
09/06/12
Area Forecast Discussion...UPDATED
National Weather Service SAN ANGELO TX
955 PM CST Fri Jan 13 2017
.UPDATE...
Temperatures have slowly dropped to the freezing mark at some
locations across the far north/northwest part of west central
Texas. Temperatures are expected to remain nearly steady
overnight. Radar shows the development of sattered light rain
showers across the eastern half of the Big Country, mostly east of
a Haskell to Abilene line. Movement of the showers is to the
north. The coverage of showers overnight should remain limited
enough to keep PoPs in the chance category. With these
considerations, making an update to the forecast to carry expand
the mix of light rain/light freezing rain to encompass the area
north of a Sweetwater-Albany line. May also have some patchy light
fog/drizzle or a little freezing drizzle where temperatures are at
or just below freezing. Having mentioned this, precipitation is
expected to remain light and patchy/scattered overnight. With
temperatures holding steady and not expected to drop farther
overnight, no travel problems are anticipated. But will monitor
the situation closely and update if needed. Latest update to the
forecast products will be out shortly.
&&
.PREV DISCUSSION... /issued 815 PM CST Fri Jan 13 2017/
UPDATE...
The cold front has sagged a bit farther south than previously
anticipated, and was near the southern border of Sutton and Kimble
Counties this evening. The 18Z NAM and latest HRRR indicate that
the front will stall, but will not begin to move back to the north
until around midday Saturday. Temperature, wind and dewpoint
adjustments were made to account for the farther southward
progress of the front. Also made upward adjustments to sky
cover, given the current and expected trends with widespread
cloud cover.
PREV DISCUSSION... /issued 552 PM CST Fri Jan 13 2017/
AVIATION...
/00Z TAFS/
Look for very challenging flight weather, during the next 24
hours. A weak cold front currently lies along or near a line from
Sonora to Junction. Warm and moist air, moving over colder air at
the surface, will continue to produce low ceilings and perhaps
light showers, during the next 24 hours. Models indicate little
if any potential for improvement. By 12Z tomorrow, expect IFR
ceilings to dominate all of West Central Texas.
PREV DISCUSSION... /issued 330 PM CST Fri Jan 13 2017/
SHORT TERM...
(Tonight and Saturday)
An upper level low just off the CA coast continues to move
southeast toward the northern Baja Peninsula. This low will move
into the central Baja Peninsula by Saturday afternoon, keeping
southwest flow aloft over our area, which will result in weak
shortwave energy passing over the area through tomorrow.
The cold front that moved through the Concho Valley overnight and
this morning looks to have stalled roughly along a line from
Barnhart to Menard to Mason. The front is expected to either
remain stalled tonight or continue very slowly through Saturday
morning before beginning its progress back to the north tomorrow.
For tonight, the boundary will serve as a stark delineation
between cooler overnight lows to the north and warmer lows along
the I-10 corridor. As the upper level low approaches through
tomorrow, southerly flow just off the surface will increase,
lifting moist unstable air over the top of the cold surface air.
This, along with passing weak shortwaves will allow for scattered
showers to develop during the overnight hours tonight.
On Saturday as the upper low approaches, surface pressure falls
will occur across west Texas and the desert southwest. This is
expected to turn winds to a more southeasterly direction, and
begin moving the cold front northward again. Exactly how far north
the front will make it is still uncertain, but will keep the
warmer temperatures generally south of I-20 for now. There will be
a continued chance for isolated to scattered showers through
Saturday, and with additional heating, a few thunderstorms cannot
be ruled out, although severe weather is not expected.
LONG TERM...
(Saturday night through Friday)
A cold front will be stalled across the central portions of West
Central Texas Saturday evening, then slowly begin to lift north
Sunday morning into Sunday afternoon. Highs on Sunday will generally
be in the 60s, as abundant cloud cover, scattered showers, and
isolated thunderstorms are expected, ahead of an approaching upper
level low. This upper level low will be located across far West
Texas Sunday afternoon, then swing across the Texas Panahandle
Monday morning. As this feature approaches, large scale lift will
result in increasing showers and thunderstorms across West Texas
Sunday morning, then spread east into West Central Texas Sunday
afternoon and evening. During this time frame, SBCAPE values will
increase to 500-700 J/KG while 0-6 KM Bulk Shear values increase to
50 to 70 knots. A few strong to severe thunderstorms will be
possible, with large hail and damaging winds being the main
concerns. Rain chances will decrease from west to east during the
evening hours, with most of the convection east of the area by early
Monday morning.
As the aforementioned upper level low moves toward the Central
Plains, an upper level trough will linger to the west, across the
Desert Southwest and northern Mexico. Uncertainty continues on the
exact timing and track of this feature, but any precipitation
associated with it looks to remain across are far southeast counties
and east of our area. A cold front will move through the region late
Monday or early Tuesday. Cooler temperatures are forecast behind the
front Tuesday, with highs mainly in the 50s and overnight lows in
the 30s. A slow warm up will ensue through the end of the work week.
&&
.PRELIMINARY POINT TEMPS/POPS...
Abilene 34 45 42 63 / 50 60 40 80
San Angelo 40 55 52 66 / 50 50 40 80
Junction 51 68 57 67 / 40 40 30 70
Brownwood 41 59 50 65 / 40 40 30 80
Sweetwater 33 44 42 60 / 60 60 50 80
Ozona 48 65 58 65 / 50 40 50 80
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Area Forecast Discussion
National Weather Service Topeka KS
518 PM CST Fri Jan 13 2017
...AVIATION UPDATE...
.SHORT TERM...(This evening through Saturday)
Issued at 320 PM CST Fri Jan 13 2017
Currently the upper level low pressure is located over the coast of
southern CA, while at the surface high pressure was centered over
the upper Midwest. Mid level flow out of the southwest has set the
stage for an overrunning situation. The challenge in the short term
is the chances for freezing drizzle across portions of the area this
evening and overnight. The soundings show that saturation is
relatively deep over east central KS and there may be periods of
lift. There is also a thin layer of drier air near the surface that
could potentially limit freezing drizzle from reaching the surface.
Also, a few of the models suggest enough lift for isolated to
scattered freezing rain showers tonight. The chances for this are
low and confined to locations along and south of I-35. If any
freezing rain falls tonight the amounts will generally be light, but
may cause travel issues.
Overnight the surface high pressure will be reinforced over the
northern plains and upper Midwest. This will help maintain the
northerly to northeast surface winds, which will support the sub
freezing air mass in place. A band of freezing rain is forecasted to
move over portions of southeast KS tonight and into tomorrow
morning. As the upper level low pressure tracks over northern Mexico
another surge of moisture will flow northward around the periphery
of the sub tropical high over the southeast US. That round of
precipitation is forecasted to lift into KS mid day Saturday. Models
are still in agreement that surface temperatures will be sub
freezing with warm air aloft for northeast KS. Late Saturday into
Sunday the ice accumulation is expected to increase across most of
the area depending on the actual width of the band of precipitation.
Current radar over southwest MO showed that the band of freezing
rain today was relatively narrow like 2 to 3 counties wide. If this
were to occur then icing would be highly localized. The NAM is
suggesting this could be a possibility late Saturday into Sunday,
while the GFS and ECMWF are predicting more widespread
precipitation.
.LONG TERM...(Saturday night through Friday)
Issued at 320 PM CST Fri Jan 13 2017
The more significant icing is expected to occur late Saturday into
Monday morning. On Sunday models agree that surface temperatures
will gradually warm to around or just above freezing. A few degrees
will mean the difference between rain and freezing rain.
Precipitation rates may also play a role in mixing down those warmer
temperatures from above the surface. So you could have transitions
of rain vs freezing especially across east central KS depending on
the rain intensity. Temperatures are forecasted to be slightly
cooler over northern and north central KS so Sunday into Sunday
night these areas could receive significant icing. This is when
the upper level low pressure lifts out over the plains, which
means the warm air advection will increase and will be fighting
the sub freezing temperatures. Again, a few degrees will make a
huge difference so large potential for lots of ice or not much
ice. Cooler warm nose temperatures may also cause sleet to mix
with freezing rain. From late Saturday through Monday morning most
locations should receive some ice with amounts around one quarter
to three quarters of an inch. This will likely cause travel issues
and possibly scattered to widespread power outages. Again, there
is also the possibility of much lesser ice amounts. Warmer
temperatures will definitely move into the area on Monday with
highs in the 40s and 50s. Melting will help improve the lasting
effects of any ice accumulations, although recovery time is tough
to predict and depends on many non meteorological factors.
A brief period of mixed precipitation may linger for a few hours
over north central into northeastern KS mainly along the hwy 81 and
hwy 36 corridor Monday night as the storm system departs the area
associated with some wrap around areas of precip. The rest of the
period should remain dry and rather uneventful weather wise as much
of the Central Plains remains in between a split flow pattern as a
broad upper level ridge builds over the region. Temperatures for mid
to late week will warm and be quite pleasant and once again well
above normal for this time of year into the 50s and 60s by Thursday
and Friday. A bit early to tell, but the next upper level weather
system may start to encroach on the area by late Friday with the GFS
most aggressive on the evolution of upper level features with a
closed upper low and negatively tilted trough lifting into the
region. Meanwhile, the EC keeps the system further west still over
the Southern and Central Rockies. Based on temperature profiles,
both models indicate that any precipitation would be all liquid.
But, again, this remains too far out in the forecast to have too
much degree of confidence.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 518 PM CST Fri Jan 13 2017
RAP and NAM isentropic progs show little if any vertical motion
within the stratus this evening. And there are even signs for
some weak pressure rises at the surface with possibly some dry air
advection near the surface. There may be some -FZDZ through the
evening but I don`t know if it will be widespread enough to
include a prevailing group for it. So have a Dry forecast with
CIGS between 2 and 4 KFT and will monitor radar trends for
possible freezing precip.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
Ice Storm Warning from 6 PM Saturday to midnight CST Sunday
night for KSZ024.
Ice Storm Warning until midnight CST Sunday night for KSZ026-
038>040-054-055.
Ice Storm Warning from 6 PM Saturday to noon CST Monday for
KSZ008>012-020>023-034.
Ice Storm Warning from 6 AM Saturday to midnight CST Sunday
night for KSZ035>037.
Ice Storm Warning until noon CST Sunday for KSZ056-058-059.
&&
$$
SHORT TERM...Heller/Sanders
LONG TERM...Drake/Sanders
AVIATION...Wolters
Area Forecast Discussion
National Weather Service Las Vegas NV
600 PM PST Fri Jan 13 2017
.SYNOPSIS...The storm system affecting the area will begin to wind
down overnight. The weekend will see drier conditions with ten
exception of northwest Arizona where showers may linger into Sunday.
&&
.UPDATE...Widespread rain showers over western San Bernardino will
be coming to an end over the next several hours as the upper low
west of San Diego drops further south down the west coast of the
Baja Peninsula overnight. Some of the higher rainfall amounts in the
past 24 hours occurred over southern/western San Bernardino County,
as skies clear fog formation possible.
Radar is detecting some light showers over Mohave County. HRRR
shifts this area northwest into northeast Clark/southeast Lincoln
County overnight. Have to keep an eye of Las Vegas as may not be
done with the light rain.
&&
.SHORT TERM...Tonight through Saturday Night
Primary concern for this forecast period is the current low
pressure system that brought all the rain and mountain snow to the
area over the last two days. This low continues to push south into
Mexico and will eventually push east and toward New Mexico. The
dynamics and forcing mechanisms that caused precipitation in our
area will go with it. Thus we expect to see a gradual tapering off
of rain across the area overnight tonight. Currently the main band
of precipitation is beginning to transition over to a NW-SE
orientation and weaken. This was anticipated. However, it will take
sometime before the rain ends. This is particularly true for areas
like Yucca Valley, Barstow area and locations in southern Inyo
County. Once we get into Saturday, conditions look good. Skies clear
out and precipitation ends. The exception is Mohave County where
some lingering showers may affect that area through Sunday.
.LONG TERM...Sunday through Friday.
A generally dry northerly flow will be over the region Sunday
through Tuesday as the upper low over northern Mexico slowly pulls
away and is followed by another weak low sliding down the California
coast by Sunday evening. North breezes can be expected...especially
along the Colorado River Valley Sunday and Monday but speeds do not
look particularly strong.
It looks like the wet Pacific pattern will bring another round of
widespread precipitation to California next week as another
atmospheric river is forecast to develop in the base of a broad
trough that will move inland Wednesday and Thursday. This will
likely bring snow to the southern Sierra by Wednesday
afternoon/night and spread a chance of precipitation across the
southern Great Basin and Mojave Desert Thursday. There are some
differences in the details with the medium range models but they
also forecast another fast moving trough and substantial batch of
moisture right behind it for Friday. This will lead to chances for
precipitation for most of our forecast area Wednesday night through
Friday. Little change in temperatures can be expected.
&&
.AVIATION...For McCarran...Showers are generally over for the valley
with improving conditions this evening. Sky conditions will be a bit
tricky this evening with cigs expected to remain around 6-8 feet,
but could rise to around 10-12k feet at times overnight. Cigs will
generally remain around 10-12k feet through Saturday. Winds will be
north to northeast 6-8 kts through Saturday.
For the rest of southern Nevada...northwest Arizona...and southeast
California...Scattered showers will mainly impact western San
Bernardino and southern Inyo Counties this evening with cigs down to
4-5k feet at times. Vsbys could also lower to around 3-4sm.
Conditions will improve later this evening with rising cigs and
increased vsbys in those locations. Elsewhere, sct-bkn clouds around
6-8k feet overnight and Saturday. Winds will generally be north to
northeast 5-15 kts.
&&
.SPOTTER INFORMATION STATEMENT...
Spotter are encouraged to report their snowfall or rainfall amounts
to the National Weather Service for this event.
&&
$$
Update...Pierce
Short Term: Lericos
Long Term: Morgan
Aviation: Gorelow
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