918
FXUS64 KFWD 260023
AFDFWD

Area Forecast Discussion
National Weather Service Fort Worth TX
723 PM CDT Sat May 25 2024

...New Aviation, Short Term...

.SHORT TERM... /NEW/
Update:

We currently have 2 supercells in our area...one along the Red
River and another south of I-20. The low-level wind field and VAD
hodographs this evening are impressive, with nearly pure cyclonic
curvature in the lowest 3 km before straightening out in the mid
levels. Moreover, a strengthening low-level jet over the next few
hours should feed/sustain the storms through the early evening. We
have observed several storm splits this afternoon, with the right
moving storms having an increased tornado potential. We don`t
expect this to change, in fact, the strengthening low-level wind
field this evening should locally enhance the tornado threat with
right-moving supercells.

This afternoon`s storms essentially split the Metroplex, resulting
in a localized area of subsidence overtop the I-20 corridor for
much of the afternoon. The dryline remains to the west of our
forecast area, with a narrow band of agitated cumulus along the
boundary. As the northern and southern storm continue to move
east, it will open the door for additional storms to develop over
Western North Texas this evening. We are starting to observe new
thunderstorms developing south of Wichita Falls that will have the
potential of quickly becoming severe. We`ll have to keep a close
eye on any storm that develops in this area as they would be most
likely to move into the Metroplex this evening.

Bonnette

Previous Discussion:
/This Weekend/

There is a chance for isolated instances of severe weather late
this afternoon and evening across North Texas. Hot and humid
weather is also expected this weekend across the region.


Heat...
Our attention has largely been on the severe weather, but a much
more widespread impact the next few days will be the heat. We have
issued a Heat Advisory for parts of Eastern Central Texas for this
afternoon. We will collaborate with neighboring offices and assess
new data over the next few hours to decide if we will extend the
advisory through tomorrow or Monday afternoon. As a reminder, our
Heat Advisory criteria is a heat index value >= 105 F (or ambient
temperature >= 103 F) for two consecutive days. Most locations
will hit this value either today or tomorrow, and most outside of
the advisory will not hit it both days.

Today`s main concern will be heat index values between 103-109
for most of the area. It will be hot, humid, and mostly sunny for
a good part of the afternoon. A dryline will move into our area
tomorrow, resulting in temperatures soaring into the upper 90s to
near 100 degrees for most locations along and west of I-35. Areas
east of the dryline will contend with another day of 105+ degree
heat index values. If you plan to spend extended periods of time
outdoors this weekend, please remember to have a plan to beat the
heat: Drink plenty of water, limit time spent outdoors in direct
sunlight, wear light- colored and breathable clothing, and be able
to recognize the symptoms of heat illness.


Severe Weather...
Yesterday`s remnant boundaries are in the process of washing out
as a low pressure center deepens to our northwest. A vigorous
shortwave trough will eject out of the Rockies this afternoon,
helping strengthen pressure falls and provide a source of large
scale ascent later today. A dryline is becoming better defined
well to our west (currently west of Childress and near Big Spring)
that will advance east this afternoon.

We`re still not 100% sure exactly where or when the first storms
of the day will take place as the CAM guidance has had modest to
poor run-to-run consistency regarding this aspect. Mesoanalysis
satellite data has already started to indicate a few modest
updraft towers going up within a shallow cumulus field between
Sterling City and Spur...or about 50 miles ahead of the dryline.
If these updrafts are able to mature into mature thunderstorms,
they would approach our forecast area between ~5-6PM this
afternoon. There is a 30% chance of this occurring. We are not
expecting any thunderstorms in our area earlier than 5PM due to a
very strong cap residing over our forecast area. Surface heating
alone should not be sufficient to break the cap without the help
of forced ascent by either the dryline or the supercell itself.

We are mainly concerned about *isolated* supercells developing
along the dryline late this afternoon to our northwest. CI is most
likely to take place where a moisture/theta-e ridge extends into
the dryline west of Wichita Falls/Abilene. Storms will develop in
a highly buoyant and well-sheared atmosphere, more than capable
of supporting supercells. Both left and right splitting storms
will also be likely this afternoon and evening. As is usually the
case...right moving supercells will have a higher potential of
large hail, damaging winds, and perhaps a tornado, while left
moving supercells will primarily have a large hail threat.

As the storms move off the boundary this evening, the storms
should remain isolated as they continue east into our forecast
area after about 7PM. The nocturnal low-level jet will strengthen
and provide sufficient inflow to maintain the storm`s intensity
several hours after sunset (particularly any right-moving storms).
Most CAM guidance only has 1 or 2 storms moving across North Texas
this evening, so while the coverage of severe weather will be
low...any storm that lives into the evening should pack a punch.
The storms should gradually weaken as they ingest more CIN
overnight, this is particularly true for areas along and east of
I-35. While an isolated storm can`t be ruled out after midnight,
most storms will end before this time.

Tomorrow morning will start precip-free, but there is a 10% chance
of isolated storms developing along a dryline over east/northeast
Texas late in the day. Near parallel flow to the boundary will
limit moisture convergence, and therefore the convective
potential. However, similar to today...any storm that develops
should be capable of producing large hail and damaging wind gusts.

Bonnette

&&

.LONG TERM... /Issued 319 PM CDT Sat May 25 2024/
/Memorial Day and Beyond/

By 00Z Monday (Sunday night), the cold front associated with the
shortwave moving across the Central Plains will still be lagging
well behind the associated surface low located near the Great
Lakes. This front, extending from the Upper Midwest into North
Texas, is projected to push south of the Red River early Monday
morning. With mid-level ascent mostly displaced well to the
northeast, forcing for ascent will generally be limited to the
surface boundary(ies). 12Z guidance continues to favor a
precipitation-free Memorial Day holiday (NBM PoPs < 10%), at least
until after dark. By the Monday evening, isentropic lift over the
shallow front in addition to ongoing warm air advection may lead
to some chances for showers and a few elevated thunderstorms. We
will also need to monitor any convection developing along the
dryline, which will likely have retreated west towards the Edwards
Plateau as moisture advection continues ahead of the boundary. We
have maintained the low (20% or less) chance for showers and
thunderstorms across Central Texas (generally south of I-20) after
midnight.

Consolidation of an expanding mid-level ridge over the
Intermountain West and the subtropical high over Mexico combined
with troughing over the Great Lakes and Appalachians will result
in northwest flow aloft across the Plains. Ridge-topping
perturbations/shortwaves embedded in the flow aloft in conjunction
with the sharpening dryline to the west and lingering frontal
boundary across Central Texas should provide sufficient forcing
for daily rain/storm chances. This pattern will support rounds of
thunderstorms developing initially over the higher terrain to our
west and northwest during the afternoon and evening tracking south
and east into North and Central Texas overnight and into the
daytime hours. The first shortwave is currently progged to arrive
Tuesday night into Wednesday with additional waves arriving
nightly through the end of the week. Forecast soundings indicate
the environment may support severe weather though the finer
details including location and specific impacts will be difficult
to define at this stage especially for later periods as the
forecast will become increasingly affected by any remnant
boundaries/outflows from previous convection.

Given recent locally heavy rainfall and the potential for
multiple additional rounds of showers and storms next week
isolated flash and urban flooding impacts are also likely,
especially over areas that recently received heavy rainfall. With
regard to the recent bout of heat, as post-frontal dewpoints drop
slightly (upper 50s/60s across North TX and low/mid 70s across
Central TX) and temperatures peak in the low to mid 90s, heat
indices on Monday should be well below Heat Advisory criteria for
all but our southern row of counties. By Wednesday, with the aid
of precipitation and increasingly cloudy skies, highs will
generally be in the 80s region wide. The active pattern looks to
keep this "cool down" in place through the end of the month.

12

&&

.AVIATION... /NEW/
/00Z TAFs/

The main impact to aviation today has been mod to severe turb
underneath supercell anvils to the north and south of D10. These
storms will continue to move east, with the southern storm
brushing by the ACT terminal between about 02-05Z. We have low
confidence the storm will last long enough to impact the airport.

Regarding D10...the thunderstorm threat is lower than it was
earlier this afternoon, but we are not out of the woods just yet.
Since our area was largely missed by earlier storms, some towers
have started to develop south of Wichita Falls that have potential
of moving into D10 this evening. The 00Z TAFs pushed back VCTS
and the on-station TS TEMPO a couple hours to account for this,
but similar to ACT...we have low confidence in this forecast.

Most to all of the storms should end between 06-08Z. There is a
10% chance of an isolated thunderstorm in the early morning hours
between 10-14Z, but the chance of this occurring was too low to
mention in the TAFs.

Breezy SSW flow is expected tomorrow, with another round of MVFR
stratus likely. Veered flow should shunt most of the ceilings into
East Texas and the eastern D10 terminals. A dryline will move into
the area late tomorrow afternoon, with a change to north flow
likely after 22-23Z.

Bonnette

&&


.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth    75  98  73  94  71 /  20   5   0   5  20
Waco                75  93  71  93  71 /  20   5   0   5  20
Paris               72  91  68  90  65 /  40  10  10   5  10
Denton              73  97  67  92  68 /  30   0   0   5  20
McKinney            74  94  68  91  68 /  30   5   0   5  20
Dallas              75  97  72  94  71 /  20   5   0   5  20
Terrell             74  91  71  91  69 /  20   5   0   5  20
Corsicana           75  93  74  93  73 /  10  10   0   5  10
Temple              74  94  72  94  71 /  10   5   0  10  20
Mineral Wells       73  98  66  94  69 /  20   0   0   0  10

&&

.FWD WATCHES/WARNINGS/ADVISORIES...
Heat Advisory until 8 PM CDT Sunday for TXZ147-148-158>162-174-
175.

&&

$$