117
FXUS64 KFWD 271037
AFDFWD

Area Forecast Discussion
National Weather Service Fort Worth TX
537 AM CDT Mon May 27 2024

...New Short Term, Aviation...

.SHORT TERM... /NEW/
Update:
Only changes from the discussion below was to keep the stationary
surface front around between I-20 and the Red River as the main
initiation point, albeit a very indiscreet. Any storm development
will be quite "conditional" to say the least, as CAMs struggle
with initiation on a run to run basis. So I kept PoPs capped at
20% until this evening, when a 20-30 kt LLJ can feed up into the
Red River Region and assist in storm development.

Otherwise, no changes to the discussion below about severity of
storms in sheared and the explosively unstable airmass that will
be in place over much of the region.

05/Marty

Previous Discussion:
/Memorial Day Into Tuesday/

...More Severe Weather Returns Late Today Into This Evening...
...More Numerous Showers/Storms Tuesday With Locally Heavy
Rainfall...

After a much-needed quiet period yesterday and through much of
Memorial Day, things unfortunately become quite unstable and
volatile by this evening with unsettled weather continuing off
and on Tuesday. The highest likelihood for isolated to scattered
severe storms will be very late this afternoon and through
midnight, with lesser chances overnight. Locally heavy rain and
flooding gets added to the mix by later on Tuesday, as a very
energized northwest flow aloft regime evolves across the area.

A weak frontal boundary has stalled this evening along the I-20/30
corridors with tropical-like moisture and very light winds both
ahead and behind this feature. I expect some fog to develop
across especially eastern Central Texas where surface dew points
are pushing around 80 degrees in spots. That`s unheard of this
time of year across our region. It`s possible dense fog could
develop across the far southeast counties enough for a brief
advisory this morning, but will await development to occur. Our
weak stalled front will mix readily north across possibly all but
our northeast counties, as a strong shortwave induces pressure
falls well west of the area. Peak heating will see temperatures
soaring into the 90s with heat index values right to around 105
degrees across particularly eastern Central Texas where a Heat
Advisory remains in effect through mid evening. In addition, the
heat and rich moisture will help surface-based instability to soar
up to 5000-6000 J/KG as additional mid level energy lifts
northeast from Mexico. Combined with very steep lapse rates =>
than 8 Deg C/km, the atmosphere as noted beforehand becomes very
volatile. This should help ignite isolated to scattered severe
storms with all modes of severe weather possible, including
tornadoes by this evening with discrete storms that can develop.
The only thing missing is a surface focus, or coverage would be
higher than the 20%-40% advertised. Still, most CAMs are showing
the potential with the strong mid level impulse arriving late
today. With this still being the end of the holiday weekend, those
planning to be outdoors in this oppressive heat will need to keep
a close eye on forecast updates and radar if possible.

Though a few storms will linger near the stalled boundary across
our northeast counties just past midnight, a downward trend in
coverage and intensity of storms will occur as temperatures cool
and subsidence briefly takes over overnight and Tuesday morning.
Morning conditions will remain very humid and warm with lows in
the 70s. After the reprieve Tuesday morning, the aforementioned
evolving and energetic northwest flow regime sets up across the
Southern Plains as the shortwave ridge to our immediate west
dampens. Though more expansive cloud cover will hold high
temperatures Tuesday to the mid-80s to the lower 90s, plenty of
strong deep layer shear >40 kts, large-scale ascent, and steep
lapse rates will again result in some severe weather with the
added addition of flooding late in the day as localized heavy
rainfall from more widespread convection evolves late in the day.
Details are more murky on Tuesday regarding coverage and timing of
impacts as models struggle with these scenarios of high moisture,
instability, and energy aloft, so my advice is too stay abreast
of the forecasts early this week. It looks like May is definitely
going out like a lion versus a lamb. Wish I had better news.

05/Marty

&&

.LONG TERM... /Issued 308 AM CDT Mon May 27 2024/
/Tuesday Evening and Beyond/

An active northwest flow pattern will set up over North and
Central Texas by midweek as the region becomes sandwiched between
a developing ridge over portions of the Desert Southwest/northern
Mexico and troughing over the Great Lakes region. An initial
shortwave perturbation looks to shift over a sharpening dryline
late Tuesday afternoon/evening, initiating isolated to scattered
convection over portions of West Texas and the Big Country. This
activity will likely develop initially as supercells before
growing upscale into a cluster of cells or possibly an MCS. With a
northwesterly mean cloud-layer wind and a 25-35 southeasterly
LLJ, this complex of thunderstorms will rapidly shift southeast
toward our forecast area late Tuesday evening into the overnight.
Where the initial convection occurs will play a large part in
determining where this complex tracks Tuesday evening/night.
However, there are several signals that our western Central Texas
counties could witness the brunt of this complex`s impact.

These convective systems tend to track along instability
gradients, and most guidance right now places that SBCAPE
gradient/weak, stalled frontal boundary generally along/south of
the I-20 corridor Tuesday night. This track over western Central
Texas and the Hill Country may also be reinforced by outflow from
thunderstorms near the Red River Valley earlier in the day. Damaging
wind gusts along the leading edge of this complex and isolated
hail will be the primary hazards. Latest high-resolution guidance
currently places an area along/southwest of a Breckenridge-
Hillsboro line in the track of this potentially severe line of
storms. The portion of this complex north of the instability
gradient will likely be sub-severe with a lack of surface-based
instability present. PWATs approaching 1.9-2.1" and warm cloud
depths greater than 15,000ft will make these thunderstorms very
efficient rainfall producers and several locations beneath these
storms could pick up a quick 2-3" of rain. Continue to monitor the
forecast over the next couple of days as we further refine
location and timing details.

This active pattern will continue through the rest of the work
week with daily chances for thunderstorms over portions of North
and Central Texas through at least Saturday. Coverage Wednesday
may be more isolated, but the next chance for more widespread
rainfall looks to arrive late Thursday into Friday as another
compact shortwave progresses overhead through the northwesterly
flow aloft and the aforementioned stalled frontal boundary lifts
north toward the Red River enveloping most of the region in
moderate surface-based instability. Severe weather will be
possible at times. Additionally, multiple rounds of heavy rainfall
will increase the flooding threat, especially over already
saturated areas. Otherwise, temperatures will be slightly tempered
by clouds and precipitation with widespread afternoon highs in the
80s and low 90s and overnight lows in the mid-60s to low 70s.

Langfeld

&&

.AVIATION... /NEW/
Update:
/12Z TAFs/

Weak surface boundary still fluctuating within the DFW Metro area
with spotty IFR/MVFR BR, particularly DAL/GKY. Only other change
to the discussion below is to delay VCTS until after 00z Tuesday,
as CAMs really struggle with the boundary and any discrete TS
development in/near the D10. Confidence remains low, but bears
watching throughout the day.

05/Marty

Previous Discussion:
/06Z TAFs/

A weak FROPA made it to about I-20(I-30 out E), but has since lost
any upper support with AFW/FTW/DFW seeing light NE around 5-7 kts
with light S or VRB winds at DAL/GKY 5 kts or less.

Moisture to the south of this boundary is very tropical-like and
high and with only light S or calm winds, I can`t rule out spotty
5-6sm BR near GKY and possible DAL/FTW by 12z, but the better bet
for MVFR/IFR and possibly LIFR conditions will be at ACT between
10z-14z. Once the old boundary and ESE/SE winds pick up to between
10-15 kts, then all sites will see VFR with SCT Cu and high
clouds.

With the old surface front out of the area, scattered TSRA are
expected over the DFW D10 area by 00z Tuesday and have an added a
VCTS until almost 03z per latest CAMs. The only driver will be mid
level energy arriving at peak heating. However, with a very
unstable airmass, look for TS+ and GS/GR to occur with TSRA.

05/Marty

&&


.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth    95  72  87  71  83 /  20  30  50  60  50
Waco                93  72  89  71  83 /  20  20  40  60  50
Paris               92  67  85  66  79 /  10  20  40  40  50
Denton              93  69  84  68  81 /  20  30  50  60  50
McKinney            93  69  83  68  81 /  20  30  50  50  50
Dallas              95  73  88  71  84 /  20  30  50  60  50
Terrell             91  70  86  68  82 /  20  30  50  50  40
Corsicana           91  71  90  71  85 /  20  20  40  50  50
Temple              92  72  89  71  84 /  20  20  40  50  50
Mineral Wells       95  70  88  68  82 /  10  20  50  70  50

&&

.FWD WATCHES/WARNINGS/ADVISORIES...
Heat Advisory until 8 PM CDT this evening for TXZ135-145>148-
158>162-174-175.

&&

$$