381
FXUS64 KFWD 272012
AFDFWD

Area Forecast Discussion
National Weather Service Fort Worth TX
312 PM CDT Mon May 27 2024

...New Long Term...

.SHORT TERM... /Issued 159 PM CDT Mon May 27 2024/
/Today and Tomorrow/

Highlights...
There is another threat of severe weather today, with isolated to
scattered thunderstorms expected to develop this afternoon. The
main threats will be large hail and damaging wind gusts. There is
a low (but not quite zero) tornado threat. Additional storms will
form late tonight and tomorrow. There will be a low severe risk
early in the day, but a higher risk of severe weather as
additional storms move into the area late tomorrow afternoon.

Forecast Discussion...
There are a couple boundaries in the area that we`re monitoring
for storm development today. The first, and most notable, is a
stationary front draped over the Metroplex. The boundary currently
resides from about Jack County through DFW to Tyler. We have some
shallow cumulus along the boundary now, but the updrafts have
been weak. The second boundary is evident by a dewpoint gradient
across the southern Big Country and Western Central Texas. This
boundary is harder to identify in surface observations, but there
is a cluster of cumulus that has developed in its vicinity.

Plentiful insolation will result in a deeply-mixed boundary layer
this afternoon, helping to erode the capping that was evident on
the morning FWD sounding. Recent ACARS/aircraft soundings have
shown that the cap still exists, however it is much weaker than
earlier in the day. With the combination of weak confluence or
moisture convergence near the boundaries, convective initiation
will be possible after about 2-3 PM. Moreover, this morning`s
observed sounding`s convective temperature was 97 F, which is
already being met or close to being met in/near the Metroplex as
of 1 PM. All of this to say, it looks more like than not that we
will at least see convective attempts near the Metroplex and
Western Central Texas this afternoon into the evening. The
coverage of storms today should be isolated to scattered. Although
we will have a focused source of surface ascent, negligible mid-
level ascent should preclude widespread thunderstorm development.
Since surface heating is a primary forcing mechanism, most of the
storms should dissipate after sunset with the loss of heating for
most of the night.

The atmosphere remains highly buoyant, largely thanks to very
high dewpoints across the region. DFW Airport`s dew point between
7-11 AM was 78 F...a daily record (our records go back to 1947).
It has since mixed down to 73 F, a further sign of diurnal
heating working to lift parcels near the stationary front.
Widespread dewpoints of 77-80 F remain across most of the area
south of the stalled front. This hot and humid airmass resides
underneath cool mid-levels, with "above the cap" lapse rates of
8-10 degC/km. Forecast soundings indicate ML CAPE values of
4-5000, with hail growth zone CAPE values near 1500 J/kg. The
shear isn`t great, but nearly straight hodographs will favor
splitting storms yet again. After a storm splits, it will usually
have a higher severe potential. The only way a tornado would be
able to develop is if a storm happens to move directly along a
surface boundary--either the stationary front or an outflow
boundary. This would locally enhance the low-level wind field and
possibly allow for a tornado to develop with a strong supercell.
The chance of this occurring is low, but not completely out of the
realm of possibility.

The front will remain stalled across North Texas overnight, with
the 925/850 front lingering over southern Oklahoma. A shortwave
trough will move overtop of the fronts in the early morning and
develop thunderstorms near the Red River. These storms should
move southeast through the morning, likely creating a strong cold
pool by mid-day. We are not fully confident of where and when
storms will develop...but are confident we will have storms
develop early in the day. The afternoon forecast will heavily
depend on how the morning storms evolve, so for now, we have
broad-brushed 30-60 PoPs across the region after 1PM tomorrow.
There will be a severe threat with the morning activity, mainly a
hail and wind risk. If training storms are able to develop, there
will also be a flash flood threat as well.

Heat/Temperature...
It is HOT outside. Most temperature readings are in the low to mid
90s at this time. Temperatures should peak a few degrees higher in
the next couple hours. When you combine the moisture in the air,
heat index values of 105-110 are expected across much of the
region today. Since our Heat Advisory criteria (heat index >= 105)
has a two consecutive day requirement, we have not expanded the
advisory west of I-35 or north of I-20. Tomorrow`s temperatures
will finally be closer to the seasonal normals due to the cloud
cover and increased rain chances.

Bonnette

&&

.LONG TERM... /NEW/
Update:

The forecast trends discussed below generally remain on track,
therefore no significant changes were made to the previous
forecast. The first in a series of weak shortwaves/perturbations
embedded in the W/NW flow aloft will shift over a High Plains
dryline on Tuesday. The resulting thunderstorm complex will carry
primarily a damaging wind threat as these storms progress
east/southeast into our area during the late afternoon and evening
hours on Tuesday. There will also be a threat for isolated
instances of large hail, particularly south I-20 and west of I-35.
This repetitive pattern of passing disturbances and daily storm
chances will continue through the end of the week. Multiple rounds
of heavy rainfall will likely lead to an increasing flood threat,
especially given vulnerable soils due to recent rainfall. This
unsettled pattern is likely to continue through the upcoming
weekend as the weakening upper ridge shifts to the east late week.
In its wake, a series of shortwave troughs riding around the
upper low over the Gulf of Alaska will eject across the northern
Rockies keeping our pattern somewhat amplified.

12

Previous Discussion:
/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... /Issued 159 PM CDT Mon May 27 2024/
/18Z TAFs/

VFR and southeast flow should prevail this afternoon. A weak
surface front in the area may allow for thunderstorms to develop
over D10 after about 21-22Z through 02-04Z this evening. The
chance of an isolated storm developing appears more likely than
not, however we are still not exactly sure where the first storm
will develop. For now, we only have VCTS in the TAFs...but may
need to add a TEMPO or remove VCTS as the afternoon progresses.
The chance of direct terminal impacts is about 30%.

A cluster of storms is forecast to develop over southern OK late
tonight and early tomorrow morning. It should approach the area
close to the morning push. These storms would also cause a change
to north flow for most of the day. We are not highly confident
of where and when storms will develop, so similar to today`s
storms, we will have to closely monitor new data as it comes in
and be quick to update the forecast if our thinking changes.

Bonnette

&&


.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth    72  89  70  83  70 /  30  50  60  60  30
Waco                72  89  70  82  69 /  20  50  60  60  30
Paris               67  84  66  79  64 /  30  40  50  50  30
Denton              70  86  67  81  67 /  30  50  60  60  30
McKinney            69  86  68  81  67 /  30  50  60  50  30
Dallas              71  89  71  83  69 /  30  50  60  60  30
Terrell             69  88  68  82  67 /  30  50  50  50  30
Corsicana           72  89  71  83  69 /  20  50  50  60  30
Temple              73  90  70  83  69 /  20  40  60  60  30
Mineral Wells       70  89  68  81  69 /  20  60  70  60  30

&&

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

&&

$$