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

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FXUS64 KFWD 241642 AAA
AFDFWD

Area Forecast Discussion...UPDATED
National Weather Service Fort Worth TX
1142 AM CDT Sat Jun 24 2017


.UPDATE...
After quite the soggy morning with widespread showers and
thunderstorms, things are finally starting to settle down across
the region late this morning. Satellite trends reveal that cloud
tops continue to rapidly warm as the incipient thunderstorms have
decayed, leaving behind a widespread swath of light to
occasionally moderate showers. We`re only seeing very occasional
lightning strikes at this time, so have limited thunder wording to
"isolated" in the updated forecast. In terms of PoPs, have
confined the highest chances to our south and western counties,
and trend them downwards through the rest of the afternoon. Given
how expansive the convective debris cloudiness is, it appears the
atmosphere will remain quite worked over--at least across the
northern portions of the CWA--limiting potential afternoon re-
development here. Across our Central Texas counties, enhanced
convergence near a stalling front may help focus additional
shower/thunderstorm development later this afternoon.

Given the widespread cloud cover, knocked a few degrees off our
high temperatures today, except across the northeastern counties
where a bit more filtered sunshine may allow temperatures to rise
into the middle 80s. This is certainly a welcome change from the
oppressive heat on Friday.

Weak isentropic ascent overnight and into Sunday atop the shallow
and cool airmass may be enough to allow some spotty
showers/storms to re-develop. As a result, we`ll maintain low PoPs
through this portion of the forecast.


Carlaw

&&


.AVIATION... /Issued 700 AM CDT Sat Jun 24 2017/
Numerous showers and thunderstorms are expected to affect the
Metroplex TAF sites this morning (through 16-17z). Afterwards,
expect the activity to shift to the south of the I-20 corridor.
Ceilings should be mostly MVFR this morning with an improvement
to VFR by 20z. Winds were variable at TAF issuance time but
should become north to northeast at 12 to 15 knots this morning as
the approaching batch of showers and thunderstorms help push the
front through the region. Winds will come around to the east by
mid afternoon (20z). Some MVFR ceilings may spread back into the
Metroplex by 11z Sunday.

Showers and thunderstorms at Waco were on-going at TAF issuance
time. Unfortunately, there was a failure at the KACT ASOS unit but
manual observations should be starting shortly. There are ongoing
showers and thunderstorms and with the next batch across North
Texas heading their way, only a brief respite is expected. Have
kept TSRA or VCTS in through 18z with SHRA in through 20z. Mostly
MVFR ceilings are expected to hold in through 20z but
ceilings/visibilities may lower to IFR in the rain/storms. VFR
conditions are expected after 20z and they should continue
through the evening. Some MVFR ceilings are expected to return by
08z Sunday.

58

&&

.DISCUSSION... /Issued 422 AM CDT Sat Jun 24 2017/
After the hottest day of the year, a cold front moved into North
Texas. Late Friday evening, thunderstorms developed along the
slowly advancing boundary, expanding in areal coverage during the
early morning hours. The activity is now largely outflow driven,
peeling up the rich nocturnal air mass across Central and East
Texas. With ample instability in the mid-levels, downstream
parcels should allow the complex to maintain its intensity past
daybreak. This will likely be inadequate for severe winds, but
a few gusts may still reach or exceed 40 mph. With extraordinary
precipitation efficiency, the primary concern will be flooding
issues that result from heavy rainfall.

Winds have returned to the south the wake of the storms, evidence
that the front is still lagging behind. It may show little
inclination to move south until the next round of precipitation
arrives later this morning. Moisture convergence along the 850mb
front resulted in widespread thunderstorm development around
midnight from the Texas Panhandle into western Oklahoma. While
elevated, these cells have managed to maintain their discrete
nature, lengthening the duration of individual updrafts. Within a
northwest-southeast oriented axis of elevated instability, these
updrafts have proven capable of half-inch hail. The northwest flow
from 500mb up to the top of the troposphere is helping to guide
this activity into the richer moisture to the southeast. This
multi-cell complex will be entering an area that was overturned
just a few hours earlier, and it will become increasingly
separated from the 850mb front. While this will result in a
gradual decrease in intensity during the daylight hours this
morning, reducing the hail threat within North Texas, the complex
will still be capable of additional heavy rainfall. Flooding will
continue to be a concern this morning, particularly where these
downpours coincide with significant rainfall earlier this morning.

The complex will dissipate around midday, and any redevelopment
this afternoon would likely be confined to Central and East Texas
where outflow/frontal forcing may linger. The longer the morning
complex survives, the less likely there will be any additional
activity late in the day. For much of the region, this afternoon
will be unseasonably cool with a northerly breeze. While
postfrontal dew points may remain in the 60s, lingering cloud
cover and wet ground should keep temperatures well below normal.
Even if the mercury reaches the low 80s in the Dallas/Fort Worth
Metroplex, it will be the coolest daytime temperatures this late
in June since rainy 2004. For some locations, today`s high
temperatures will be more than 20 degrees cooler than Friday`s.

The widespread convection will maintain a weakness in the mid-
level flow that could allow for renewed daytime shower and
thunderstorm development Sunday and Monday, particularly with
adequate sunshine. The better chances will be across the west and
south. Thereafter, ridging aloft may nose enough into the region
to limit activity during much of the upcoming workweek. However,
the northwest Gulf will remain in a col between the western ridge
and a dirtier ridge over Florida and the Greater Antilles. As a
result, inclement weather may dominate the Texas Coast. During the
afternoon hours, the northwest extent of this activity may be
within our southeast zones.

Late in the week, the tail end of a trough axis, associated with
a polar low tracking through the Canadian Prairies, may swing past
our meridian. Although its lift may remain to our north, its
passage could allow another summertime cold front to approach next
weekend. While this may imply that the summer heat will be kept at
bay, subtropical ridging and above normal temperatures look like
they will prevail during the first week of July.

25

&&

.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth    81  70  84  69  88 /  90  20  20  10  10
Waco                82  72  85  69  88 /  80  30  30  20  20
Paris               85  67  85  65  87 /  60  20  10  10  10
Denton              81  68  84  67  87 /  80  20  20  10  10
McKinney            82  67  85  67  87 /  70  20  20  10  10
Dallas              82  71  85  70  88 /  90  20  20  10  10
Terrell             82  69  85  68  88 /  80  20  20  10  10
Corsicana           83  71  85  69  87 /  80  20  30  20  20
Temple              83  71  85  69  87 /  80  30  30  30  30
Mineral Wells       79  68  83  67  86 /  80  20  30  20  20

&&

.FWD WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

90/05



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