Area Forecast Discussion
Issued by NWS Dallas/Fort Worth, TX

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FXUS64 KFWD 161913 AAA

Area Forecast Discussion...UPDATED
National Weather Service Fort Worth TX
113 PM CST Fri Feb 16 2018

Lift will be on the increase over the next sever hours as a
shortwave trough approaches from the west. Light echoes on RADAR
are mostly in the for of VIRGA, so have backed off POPs for the
afternoon. Precip chances will increase tonight as stronger ascent
arrives and moisture levels increase. The rest of the forecast
is in good shape.



.AVIATION... /Issued 1152 AM CST Fri Feb 16 2018/
A shortwave trough currently near Baja California will race
eastward across Mexico overnight and into Central and North Texas
Saturday morning. Clouds will be on the increase this evening and
will likely lower into MVFR range by 12Z Saturday. A quick round
of showers will accompany the shortwave Saturday morning,
followed by drying weather and VFR conditions around midday.



.SHORT TERM... /Issued 414 AM CST Fri Feb 16 2018/
/Today and Tonight/

Patchy fog has developed across parts of Central Texas overnight.
This fog will dissipate later this morning as a cold front
approaches. The aforementioned cold front extended southeast of a
Harrison, AR (KHRO) to Ardmore, OK (KADM) to Hobbs, NM (KHOB) line
as of 3 am. The front will continue to move southeast and is
expected to extend southeast of a Paris to Cleburne to Comanche
line by daybreak. This front will sweep through the rest of the
forecast area before midday. Winds will be southwesterly at around
10 mph ahead of the front and shift to the north at 15 to 20 mph
with frontal passage and some gusts of 25 to 30 mph are likely.
Highs today are expected to be this morning in most locations as
temperatures will initially fall behind the front and then they
will likely be steady or only slowly rise for the rest of the
today. There will be a slight chance of rain this morning mainly
north of I-20 or along and east of I-45. As the front sinks
farther south this afternoon, there will be at least a slight
chance of showers area wide with slightly better chances along and
north of the I-20 corridor afternoon afternoon.

As a shortwave approaches and isentropic upglide increases across
North and Central Texas, showers will become likely along and
north of the I-20 corridor after midnight. There will be a 40 to
50 percent chance of showers farther to the south. Northeast winds
10 to 15 mph early in the evening will become north to northwest
5 to 10 mph after midnight. Lows will range from the upper 30s
northwest to the upper 40s southeast.



.LONG TERM... /Issued 414 AM CST Fri Feb 16 2018/
/Saturday through Friday/

An active weather pattern appears likely for much of North and
Central TX. I do have high confidence that there will be
opportunities for much needed rainfall across the area. As it
pertains to the severe weather risk, the picture isn`t quite clear
and the current forecast will continue to advertise a conditional
risk for strong to severe storms on Monday and possibly Tuesday.
After above normal warmth for much of next week, temperatures will
briefly fall to near or below climatological norms. This will be
short-lived as it appears that we will warm up quickly towards the
end of the week and into the last weekend of the month.

For Saturday---The first opportunity for widespread rainfall will
be early in the day on Saturday as a shortwave trough skirts the
Big Country and western North TX. The lift from this feature will
likely produce an extensive rain shield that will quickly march from
west to east across North and Central TX. Initially, best rain
chances will be for locations near and north of the I-20 corridor.
PWATs do climb into the 90th percentile, so short lived instances
of moderate rain will be possible. Given the recent dry
conditions and the fact that this rain shield should quickly
translate eastward, an appreciable flooding threat appears
unlikely to unfold. Forecast rainfall amounts should be between
half to almost three quarters of an inch for North TX. During the
afternoon hours, the best rain chances will shift towards the
east and south across Central TX and into the Brazos River Valley
as both mid- level dry air and the elevated baroclinic zone slide
southward. Rainfall totals here may climb upwards of half an inch
here. Afternoon high temperatures across the area will range
from the low to mid 60s across the Big Country to low to mid 50s
across East TX. By Saturday evening, most areas should be rain-
free with the exception being across the HWY 79 corridor where a
few sprinkles may linger.

For Sunday---the aformentioned low level baroclinic zone will
stall and lift northward through the day. Early in the morning,
lift looks a tad weak, so I`ve lowered PoPs down into the 20 to 30
percent range. If the latest NAM NEST and TTU WRF forecasts are
to verify, even these forecast PoP values thru 12 UTC Sunday may
be too high. Low level isentropic ascent on the 300 to 315K theta
surfaces increases later in the day---initially across the Hill
Country. With the best lift out west, I`ve reconfigured PoPs with
highest rain chances (around 50%) west of I-35. Despite the cloud
cover, WAA should help temperatures climb into the low 70s with
low to mid 60s elsewhere. The WAA around 850mb will allow for the
generation of some mid-level instability and I won`t rule out an
isolated storm or two in the afternoon on Sunday. Better
instability doesn`t develop, however, until the late afternoon
and evening hours. By then, the theta-e plume will turn to the
east resulting in best rain chances north of a Lampasas to Waco to
Athens line. With better theta-e transport during this time,
there should be enough instability for a few isolated storms and
I`ve kept this in the forecast. It`ll be mild Sunday night (most
areas will only fall into the upper 50s and low 60s) as southerly
winds increase thanks to a strengthening surface pressure
gradient. Sustained wind speeds across the area will climb into
the 10 to 15 MPH range with gusts close to 25 MPH.

For Monday---Monday will be even warmer and breezier with daytime
high temperatures in the 70s to almost near 80 degrees out across
the Big Country! Through the day, there could be some WAA showers
and perhaps a rumble of thunder or two, but forecast soundings
indicate some pretty decent capping. With the trough likely to
remain to the west, it doesn`t appear likely that cap will be
breached until later in the day (if at all). I`ll keep highest
PoPs to the north and northwest where there may be enough
convergence along the eastward advancing dryline. There still
remains a large degree of uncertainty as to whether or not
surface based deep moist convection will initiate on the dryline.
Even still, this convection would still need to survive an
environment that isn`t necessarily characterized by a ton of large
scale ascent. Moreover, forecast soundings indicate that the cap
is never completely eroded. If convection is able to survive,
there will be adequate deep layer shear (40 to 50 knots) along
with CAPE on the order of 500 to 1000 J/kg (though the CAPE
profile is quite skinny). This would be sufficient for some
organized convective modes and thus a potential for severe
weather. Given the uncertainties, we will just keep an eye on this
potential before making any significant weather headlines.

For Tuesday and Wednesday---The next good opportunity for
widespread rain will occur during this time period as a cold
front pushes south towards our area. There should be a
proliferation of convection as this front moves through the area.
PWAT values will remain quite high for this time of year with
values near 1.5". Given that convection will likely be a bit more
widespread (and perhaps vigorous), the potential for heavy rain
will be a bit higher. Instability and shear will be in place and
lapse rates may even be a bit steeper on Tuesday across parts of
the area. Again, the potential for some organized convective modes
and thus severe weather appears possible. Stay tuned to later
forecasts for details. There is a pretty good signal in
deterministic guidance, though the 00 UTC ECMWF has slowed things
a bit, with a complex of showers and storms along the southward
advancing front through the day on Tuesday. I`ve kept PoPs high in
the 60 to 80 percent range on Tuesday and overnight into
Wednesday morning. Highest rain chances will initially be along
the Red River and then shift towards the southeast into East TX
with time. I wouldn`t be surprised if some areas saw rainfall
amounts in the 1 to 2" range which will certainly be welcomed!
There is some uncertainty as to how quickly we clear out on
Wednesday, so I`ve gone with some of the blended guidance which
keeps some low rain chances late in the day on Wednesday across
East TX.

Tuesday will be mild by late February standards with highs in the
low 60s along the Red River to low 70s across Central TX. It`ll
be much cooler on Wednesday in the wake of the front with high
temperatures likely falling below seasonal values for much of the
area. High`s will only climb into the mid to upper 40s to the mid
50s. It will also be quite blustery behind the front as decent
pressure rises build to the north.

For Thursday and Friday---While surface high pressure will build,
it`ll be relatively short lived as high pressure quickly retreats
and low level flow becomes southerly. The ascent atop the
relatively cooler surface air should help promote the development
of showers and a few isolated thunderstorms, especially across
East TX late in the day on Thursday. On Friday, there`s a high
degree of uncertainty in the PoP forecast, so for now I`ve
broad-brushed the area with 20-30 percent chances for rain and
storms. Temperatures should rebound to near or just above seasonal
norms with most areas in the upper 50s to near 60 degrees by



Dallas-Ft. Worth    44  57  44  65  60 /  60  90  10  50  40
Waco                44  56  46  70  62 /  40  40  20  40  30
Paris               44  53  40  61  56 /  70  90  10  40  50
Denton              40  59  40  65  60 /  60  90  10  50  40
McKinney            41  56  41  63  59 /  70  90  10  40  40
Dallas              45  57  45  64  61 /  60  80  10  40  40
Terrell             44  56  43  64  61 /  60  80  10  30  40
Corsicana           45  53  46  65  61 /  50  50  10  30  30
Temple              46  56  47  70  62 /  30  50  20  40  30
Mineral Wells       39  61  41  68  60 /  50  80  10  50  30




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