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

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FXUS64 KFWD 170843
AFDFWD

Area Forecast Discussion
National Weather Service Fort Worth TX
343 AM CDT Tue Apr 17 2018


.SHORT TERM...
/Today and Tonight/

Breezy southerly winds have kept temperatures about 20 degrees
warmer this morning than yesterday at this time. These winds are
associated with a tightening surface pressure gradient thanks to a
deepening lee surface low. Winds near 925mb are around 50kts
where they will remain through mid-morning. Besides the warmer
temperatures, these winds have brought in some meager Gulf
moisture, and dewpoints have climbed into the 50s for most areas
overnight. This moisture is far too scant for any low stratus to
develop, but a slight increase in high cirrus streaming in from
the west can be expected across North Texas today.

There may be a brief window during the mid/late morning hours when
Wind Advisory criteria is approached as daytime mixing occurs
prior to the nocturnal LLJ weakening. However, this should be
short-lived as winds in the 925-850mb layer will decrease to
about 30 kts by midday. Winds of 15-25 mph with higher gusts will
continue through the entire day though as some of this momentum
will be transferred to the surface via mixing. Highs are expected
to be a few degrees warmer than yesterday with some 90s likely
across our western zones. RHs will fall into the 20s or upper
teens west of US 281, and elevated fire weather conditions are
expected to develop in this area during the afternoon. Winds will
decrease slightly through the evening, but it will remain breezy
overnight in advance of a cold front that will be approaching the
Red River prior to daybreak.

-Stalley

&&

.LONG TERM...
/Wednesday through Tuesday/

A cold front will swiftly sweep across the region Wednesday
morning, but the cooler air behind the front is not as strong as
the last few cold fronts we have had. Generally north winds of
15-20 mph with higher gusts will occur behind the front in the
morning hours, but wind speeds are expected to lower to 10-15 mph
in the afternoon as the surface high moves into the region. Daytime
highs on Wednesday will be pleasantly in the 70s with a few
locations in Central Texas possibly reaching 80 degrees. Have
removed the low chances for rain in our southern counties as the
moisture depth appears too limited under a decent cap for
precipitation. Although drier air will be ushering into the
region, fire weather concerns on Wednesday looks minimal as the
lowest RHs will not coincide with the strongest winds that day.

Wednesday`s front will push into the Gulf of Mexico, and a
reinforcing surface high will slide down the Plains and into the
region on Thursday. The center of the surface high will remain
anchored around the Midwest, slowly sliding east into Friday.
In this position, east surface winds will prevail across the
region, limiting our moisture return before the next upper level
system arriving this weekend. Thursday`s temperatures will average
about 1-3 degrees cooler than Wednesday in most locations behind
the reinforcing air.

On Friday, an upper level low will move into the Four Corners
area setting the stage for rain and storms on Saturday. Our
surface winds will slowly start to turn to the southeast, but the
better moisture fetch from the Gulf of Mexico will remain cut-off
from North and Central Texas. However, we will start to see
increasing moisture in the mid levels of the atmosphere as those
winds turn to the south and southwest. This is expected to result
in increasing cloud cover, and the increasing cloud cover combined
with the easterly surface winds should yield a cooler day with
highs in the upper 60s and lower 70s. However, if the cloud cover
over the eastern counties is less than expected, high temperatures
will likely need to be raised, in particular east of I-35.

Any rain on Friday is expected to be west of the region, closer to
where the better moisture return is occurring near the upper
level trough, but have left slight chance PoPs in our far western
column of counties. During the afternoon hours, a few ripples of
energy may translate ahead of the trough, sparking a few showers
or storms in areas west of our CWA that could move into these
counties.

The rain and thunderstorm activity is expected to ramp up in West
Texas Friday night as the upper level trough continues to
approach that region. In our area, southeast winds at the surface
will start to increase, and some low-level moisture return will
occur. More rapid moisture advection is expected on Saturday as
the upper level trough swings into a negative-tilt as it enters
the state, pushing a surface low and dryline east. On Friday
night, I still anticipate most of the rain will be to our west.
Convection may organize into a line that would likely move
northeast, but the speed and timing of that is yet to be
determined. Will keep a chance for rain west of Interstate 35/35W,
but even the 50 PoPs I have in our western counties may be too
generous depending on the track and timing.

Showers and thunderstorms are expected Saturday across North and
Central Texas as the upper level trough continues moving across
the Plains. As mentioned above, rapid low level moisture return
is expected during the day on Saturday, but this late return has
the potential to limit the severe weather threat. Based on the
latest model runs, this event looks like a potential low CAPE/high
shear set up. Without better moisture return, surface based
instability will likely be on the lower end. The GFS is
forecasting a narrow corridor of 1000-1500 J/kg of SBCAPE across
our region along the dryline in the afternoon hours. The ECMWF is
even less with its CAPE projections as its upper level trough
position and surface low are further south than the GFS. This
limits the better CAPE to locations south of our CWA, but what
could be concerning is the ECMWF sets up a pseudo-warm front
across the region with the surface low tracking through Central
Texas. The track of the upper level trough and surface will have
to be monitored as we approach the weekend. Deep layer shear
values of around 50-60 kts should be sufficient to support
rotating updrafts, but forecast soundings are not too keen on
elevated instability or lapse rates. All this said, we aren`t
saying there isn`t going to be a severe weather threat, but there
are concerns at this time that question how strong or widespread
the severe weather threat will be. CIPS analogs for similar
patterns still yield at least some severe weather reports with
past events. A tornado threat cannot be discounted at this time
based on low-level wind profiles and if any boundaries set up in
the area.

Regardless of the severe weather threat, beneficial rainfall is
still expected for much of the region. Several areas could receive
0.5-1.5" of rain with higher amounts possible in our eastern
counties. The rain should be moving east of the region Saturday
night and Sunday morning as the upper level trough also moves east
and a cold front sweeps across in its wake. Below normal
temperatures will start out next week, and it`s possible some
light rain occurs in the region on Monday.

JLDunn

&&


.AVIATION... /Issued 1123 PM CDT Mon Apr 16 2018/
VFR conditions are forecast to prevail at the TAF sites through
06z Wednesday. As a lee side trough continues to deepen, southerly
winds at 15 to 20 knots will increase to 20 to 25 knots by 15z
Tuesday and some gusts over 30 knots are likely. There will be a
50-55 knot southwesterly low level jet overnight but the NAM
continues to be the lone model that tries to bring some MVFR
ceilings close to and just east of KACT 12-16z Tuesday. As
decoupling is not expected to occur Tuesday evening, wind speeds
and gusts are only expected to decrease slightly after sunset
Tuesday.

Extended forecast...A cold front is forecast to cross the Red
River between 06z and 08z Wednesday and move through the
Metroplex TAF sites 10-12z. Winds will shift to the north at
15 to 20 knots with the frontal passage. Some MVFR stratus may
spread into KACT by 09z Wednesday.


58

&&

.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth    86  63  78  52  76 /   0   5   5   0   0
Waco                84  62  79  50  77 /   0   5   5   5   5
Paris               81  60  74  46  72 /   0   5  10   0   0
Denton              86  57  77  48  74 /   0   5   0   0   0
McKinney            84  59  76  47  74 /   0   5   5   0   0
Dallas              85  62  78  53  76 /   0   5   5   0   0
Terrell             83  60  78  50  75 /   0   5   5   0   0
Corsicana           83  62  77  52  75 /   0   5  10   0   5
Temple              84  61  80  52  77 /   0   5  10   5   5
Mineral Wells       91  58  78  48  76 /   0   5   0   0   5

&&

.FWD WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

82/26


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