482
FXUS64 KFWD 161029
AFDFWD

Area Forecast Discussion
National Weather Service Fort Worth TX
529 AM CDT Thu May 16 2024

...New Aviation, Short Term...

.SHORT TERM... /NEW/
Update:
As previously discussed, the arrival of rich low-level theta-e air
across the Big Country and western North Texas is leading to the
development of widespread convection just northwest of the
forecast area as of 530 AM. This trend will continue over the next
few hours while convective clusters grow upscale and accelerate
southeastward through North and Central Texas. Hazards for large
hail, damaging winds, and flash flooding are likely through much
of the daytime as this convection primarily impacts roughly the
southwestern 2/3rds of the CWA. No significant adjustments were
made with this morning`s update other than to refine near-term
trends. Isolated rainfall totals near 5" in Central Texas still
look plausible for reasonable high-end amounts based on overnight
high-res guidance.

-Stalley

Previous Discussion:
/Through Friday/

With this update, the Flood Watch has been expanded northwestward
to include the DFW area and additional locations to the south and
west. While the heaviest rainfall is still expected in Central
Texas with today`s event, isolated totals in the 3-4" range will
be possible near or even just north of the I-20 corridor, too.
This flooding risk will unfold within an episode of strong to
severe convection, with the greatest severe risk also across
Central Texas.

Modest ascent acting upon steep lapse rates has allowed fairly
widespread high-based shower and thunderstorm activity to develop
from Wichita Falls to Houston as of 1 AM, and this sub-severe
activity is likely to continue through the morning while
eventually moving off to the northeast. Outside of some small hail
and brief heavy rainfall, this activity will be rather
inconsequential compared to convection later this morning.

The primary round of convection will get underway around or just
after daybreak and will initially occur north and west of the CWA
along a slow-moving frontal zone associated with a deepening
surface low situated near El Paso. As intense poleward moisture
flux occurs within a strengthening low-level jet, quick
destabilization will occur as low-level moisture advection beneath
steep lapse rates results in MUCAPE values of 2000-4000 J/kg.
PWAT values will increase from 0.75-1" to 1.5-2" in the next
several hours, and as this moisture arrives, rapid development of
convection will ensue between 7 and 10 AM as it collides with
multiple sources of lift. A steady ESE progression, likely to be
accelerated by cold pooling, will send one or more convective
clusters and/or line segments through North and Central Texas by
late morning and early afternoon. This activity will be capable of
very heavy rainfall with rates perhaps near 2" per hour, as well
as large hail and damaging wind threats, the primary of which will
be dependent on eventual convective mode. The heaviest rainfall
totals and greatest flood threat are still expected in Central
Texas where isolated amounts near 5" are possible.

The aforementioned slow-moving frontal boundary (or effective
frontal boundary modified by convective outflow) will also sag
south of I-20 towards midday. Depending on the extent of
convective activity during this time window, there could be a
threat for new redevelopment along this feature which would
likely be supercellular in nature. Backed easterly winds in the
vicinity of this surface boundary and attendant increased helicity
could result in an increased tornado threat across the southern
fringes of our forecast area along a corridor from Lampasas to
Temple/Killeen to Hearne. However, this will be very much
mesoscale driven, and a scenario involving faster-than-expected
upscale growth would act to minimize this threat in short order.
Eventual upscale growth into a large convective complex is
expected by late afternoon, with this main round of thunderstorm
activity shifting southeast out of the forecast area this
evening. However, lingering shower and isolated thunderstorm
activity is possible back to the north and west as additional
ascent continues to act upon steep lapse rates in areas that may
not have been entirely worked over by convection earlier in the
day.

A relative lull in convective activity is expected overnight,
although we cannot rule out additional light rainfall, while
widespread low stratus engulfs most of the forecast area heading
into Friday morning. Since the upper trough axis will still be
upstream tomorrow, additional isolated showers and thunderstorms
could redevelop during the daylight hours as the trough passes
overhead, but this convection is unlikely to be strong, and rain
rates should be unable to cause any further flooding issues even
after widespread rainfall today.

-Stalley

&&

.LONG TERM... /Issued 330 AM CDT Thu May 16 2024/
/This Weekend Through Next Week/

Rain chances will come to an end across East Texas early Saturday
morning as our storm system finally pushes off to the east.
Ridging aloft will take its place, with positive mid-level height
anomalies prevailing into the upcoming workweek assuring above
normal temperatures. A shortwave will transit the Plains late in
the weekend, dampening the flow, but it will neither reintroduce
rain chances nor inhibit the warming trend. By Monday, nearly
every location will see afternoon highs in the 90s. The subsequent
(more potent) disturbance will take a more southerly track, which
may guide a late-season cold front and associated rain chances
into our area. While this could shave a few degrees off daytime
temperatures, the current forecast will maintain above normal
highs regionwide for day 7 (Wednesday, May 22).

25

&&

.AVIATION... /NEW/
/12z TAFs/

Scattered high-based convection rooted near 10 kft continues to
drift across southern and eastern portions of D10 early this
morning, although lightning activity has waned with these cells
over the past couple of hours. Much more widespread and stronger
convection is beginning to develop upstream across western North
Texas, and will arrive at the TAF sites around 15-16z. A few hours
of convective impacts are likely through mid afternoon before
storms eventually shift southeastward. Following the departure of
convection, MVFR/IFR cigs are expected to fill in within
northeasterly surface flow, although the timing of these cigs and
when category degradations will occur remains very uncertain. It`s
possible that a window of VFR time could exist through the late
evening hours before these cigs develop early tomorrow morning.
Additional isolated shower and thunderstorm activity is possible
overnight into Friday, although the potential is currently too
low to advertise in the TAFs.

-Stalley

&&


.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth    77  65  80  67  91 /  90  60  20  10   5
Waco                74  65  81  65  88 / 100  70  20  10   5
Paris               80  64  79  63  87 /  50  60  50  20   5
Denton              76  62  78  63  89 /  90  60  30  10   0
McKinney            78  63  79  64  88 /  70  60  30  10   5
Dallas              79  66  81  67  91 /  80  60  20  10   5
Terrell             77  64  80  65  87 /  80  60  20  10   5
Corsicana           78  67  82  67  89 / 100  60  20  10   5
Temple              75  65  81  65  89 / 100  60  10  10   5
Mineral Wells       74  62  79  63  91 / 100  70  20  10   0

&&

.FWD WATCHES/WARNINGS/ADVISORIES...
Flood Watch through Friday morning for TXZ101>104-116>122-
130>135-141>148-156>162-174-175.

&&

$$