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

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000
FXUS64 KFWD 261719
AFDFWD

Area Forecast Discussion
National Weather Service Fort Worth TX
1219 PM CDT THU MAY 26 2016

.UPDATE...

Morning convection has produced rain amounts in excess of 2 inches
over a short period of time generally across the Central Texas
counties of the forecast area. Storms should continue to
develop/back build and train over the same region through the
afternoon. Since the atmosphere is so moist and unstable we have
decided that a flash flood watch would be necessary. The watch is
essentially south of a line from Goldthwaite to Hillsboro to
Athens and begins at noon today and goes through 6 pm Friday.

We still anticipate a threat for severe storms this afternoon and
evening...beginning in the west this afternoon on the dryline.
Shear, instability and lift should all be in place for severe
storms to develop.

The only changes necessary with this update will be to add the
flash flood watch and to adjust the QPF up mainly in the watch
area.

79

&&

.AVIATION...
/ISSUED 652 AM CDT THU MAY 26 2016/
Concerns: MVFR ceilings this morning, return of MVFR/IFR cigs
Friday morning, and rain/thunder potential through the entire
period.

Showers and thunderstorms have begun to increase in coverage just
west of the TAF sites this morning. Occasional lightning strikes
from the anvil remnants of earlier convection have affected areas
west of the Metroplex sites this morning and expect that trend to
continue through the morning hours. Otherwise, new development has
intensified especially across Central TX where abundant lightning
has accompanied some strong thunderstorms which continue to
produce heavy rain and small hail. Waco has the highest potential
for thunder through the rest of the morning and have included
tempo and vc mentions to cover this potential. Only isolated showers
are likely at the Metroplex sites, at least through late morning,
which may result in some brief reductions in vsbys.

Activity should continue to increase by midday and with ample
elevated instability, thunder is likely at all TAF sites early
this afternoon. Heavy rain and small hail will accompany the more
intense activity along with frequent lightning. In addition,
south winds will increase this afternoon to 15 to 20 kts with
higher gusts possible. A brief break in convective activity may
occur later this afternoon before thunderstorms redevelop across
West TX and the Hill Country. Numerous storms are expected to
develop and move eastward affecting all TAF sites this evening and
overnight. This is the most likely time for sustained
thunderstorms at all airports and have prevailed TSRA to account
for this.

Behind the main surge of showers and storms tonight, low MVFR and
IFR conditions are expected as lingering showers continue.
Additional thunderstorm activity is likely through Friday morning
or even Friday afternoon as additional thunderstorm complexes move
in from the west, but confidence in timing and coverage is too low
to pin down in the current TAFs.

-Stalley


&&



.PREV DISCUSSION... /ISSUED 400 AM CDT THU MAY 26 2016/
A thunderstorm complex, associated with an approaching shortwave,
is currently impacting the Concho Valley. Rain (with isolated
lightning strikes) from the downstream anvil has reached the
western edge of our CWA. As the upper impulse continues to east,
showers and thunderstorms will spread across North and Central
Texas today. Despite maritime tropical dew points at the surface,
and the instability they portend, the activity this morning will
be elevated. The lapse rates aloft will not be extraordinary and
expect the morning storms will primarily pose a lightning threat.

The 00Z sounding from Fort Worth showed that a formidable cap
remained. Even in our western zones, where the sun pushed
temperatures over 90 degrees Wednesday afternoon with dew points
were in the mid 70s, the cumulus field proved that the inhibition
was as widespread as it was strong. The lift associated with the
initial shortwave today should weaken the inversion to some extent
today, but morning rainfall will likely yield a cooler boundary
layer that is equally unable to overcome it. As a result, the
showers and thunderstorms will likely remain elevated into the
afternoon hours. Short-range guidance is literally all over the
map with respect to the location of the elevated convection this
afternoon, but expect the bulk of the forcing with be in areas
east of the I-35 corridor during the latter half of the day. Some
surface-based (potentially severe) convection will be possible
this afternoon mainly west of I-35, particularly those areas that
remain largely free of precipitation this morning. SBCAPE values
in our western zones should be less than the eye-popping numbers
we saw yesterday but could still yield very strong updrafts
supportive of large hail and damaging downbursts.

With the main upper trough still upstream, it is unlikely this
passing shortwave will veer or intensify the flow beneath it. This
means that the dryline will likely remain across West Texas,
perhaps even farther west than it was Wednesday afternoon.
Regardless of its position, there should be little if any
downglide in the wake of the departing impulse, and the dryline
may again be the focus for convective initiation this afternoon.
This activity would likely maintain its intensity into the evening
hours as it approaches our western zones. These storms would pose
a significant severe threat with large hail, damaging winds, and
tornadoes. This activity may congeal into a complex that would
reach the I-35 corridor after midnight. Although the intensity may
steadily diminish overnight, there would still be a continued
hail/wind threat into the morning commute across our eastern
zones.

The main upper trough will emerge from the high terrain of the
southern Rockies on Friday, dragging its final and most intense
spoke of lift across Texas. Widespread showers and thunderstorms
will impact North and Central Texas, with primarily a heavy rain
and flooding threat. However, with considerable instability still
in place, some strong/severe storms will be possible. One of the
favored areas will be Central Texas, the convection within which
may consume the bulk of the moisture flux. Another favored area
will be our western zones, which may see enough sunshine to allow
for surface-based thunderstorms late in the day. In addition,
dryline convection may enter our northwest zones late in the
afternoon or into Friday evening.

Although oppressive humidity will remain on Saturday, North and
Central Texas may experience a rare sunny afternoon, particularly
in areas along and west of the I-35 corridor. But while you`re
at the pool, the next upper trough will be deepening on the West
Coast. Rain chances will increase late Sunday into Memorial Day,
and the unsettled pattern looks to continue throughout the
upcoming week.

25



&&


.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth    83  70  82  70  89 /  60  60  70  40  20
Waco                83  72  84  70  90 /  70  60  70  40  20
Paris               81  69  78  68  85 /  60  70  80  60  30
Denton              83  69  82  67  88 /  60  70  70  30  20
McKinney            82  70  81  67  86 /  60  60  80  40  20
Dallas              84  70  83  71  89 /  60  60  70  40  20
Terrell             83  72  82  70  88 /  60  60  80  50  20
Corsicana           82  71  81  70  88 /  60  60  80  50  30
Temple              82  72  84  71  89 /  70  60  70  40  30
Mineral Wells       82  68  85  65  89 /  60  70  70  20  10

&&

.FWD Watches/Warnings/Advisories...
Flash Flood Watch through Friday afternoon for TXZ135-142>148-
156>162-174-175.

&&

$$

90/79



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