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Area forecast discussion
National Weather Service Fort Worth Texas
1122 PM CDT Sat Sep 21 2019

/06z tafs/

While VFR conditions currently prevail at the taf sites, another
round of MVFR stratus is expected overnight. The onset of low cigs
should occur around 09-10z at Waco and closer to 11-12z across
the dfw area. Stratus is likely to be less widespread than the
previous couple of nights, although at least some intermittent
cigs will be possible through mid to late morning at any of the
taf sites. Cig heights will predominantly be at or above 2 kft,
although some may briefly fall into the 1-2 kft range. Conditions
should improve to VFR at all airports by late Sunday morning.
Scattered afternoon convection is expected across parts of North
Texas and southern Oklahoma, but at this time, am expecting all
activity to remain north and west of the taf sites. Will maintain
rain-free tafs for the time being, but northern
arrivals/departures may be affected. South winds are expected to
prevail, although outflow boundaries from any convection could
result in temporary wind shifts late Sunday afternoon or evening.



Update... /issued 843 PM CDT Sat Sep 21 2019/
the forecast is still on track this evening, and only minor
adjustments were needed to capture ongoing trends. Have omitted
all mentions of thunder through the overnight hours, as any
activity that would encroach on our northwestern zones later
tonight would likely consist of decaying rain showers at most.
Most of this activity will remain well north and west of the
forecast area. Dry and tranquil weather is expected for the
majority of the cwa, with lows falling into the low/mid 70s.



Long term... /issued 304 PM CDT Sat Sep 21 2019/
/Sunday night through Saturday/

By Sunday evening a quasi-stationary frontal boundary should be
draped across parts of central and southern Oklahoma. In the
vicinity of this boundary will be a pool of deep moisture content
with pws in excess of 2". A broad area of low level convergence
will be present along with strengthening westerlies aloft. A
focused area of showers and thunderstorms may be ongoing Sunday
evening across our far northern and northwestern counties into
southern Oklahoma. This area will remain the favored area of rain
chances through the upcoming week.

On Monday, a digging trough over the southwestern U.S. Will become
increasingly cut off from the polar jet stream and should set up
shop somewhere over Arizona late Monday night. Meanwhile, across
North Texas, we'll remain within an established southerly flow
regime through 700 mb. The remnant frontal boundary will still be
to our north and will serve as a focus for afternoon showers and
thunderstorms mainly across southern Oklahoma. Some of these may
impact areas along and north of I-20 through the afternoon.

On Tuesday, the upper trough to the west should remain parked
across southern Arizona, although a weaker mid and upper level
trough between 500-300 mb will spread northward along the Texas
coast. This should place most of the Southern Plains within a
region of modest height falls through the afternoon hours. With
the pool of higher moisture still draped across the Red River, we
should see at least decent coverage of afternoon showers and
thunderstorms. Similar to Monday, coverage will be highest north
of I-20.

Guidance is in fair agreement through the end of the week with the
handling of the upper trough to the west, although there are some
timing and track differences. Despite this, most of the stronger
forcing for ascent should pass well to our north through Friday.
With persistent moist southerly flow, we'll maintain some low pops
areawide Wednesday through Friday.



Short term... /issued 1245 PM CDT Sat Sep 21 2019/
/through Sunday/

Deep southerly flow across north and central Texas continues to
import Gulf moisture into the region, leading to another
unseasonably hot and humid day. Temperatures are already in the
mid 80s, and should have little difficulty making it into the low
to mid 90s this afternoon. Little in the way of convection is
expected today as upper-level ascent stays off to our west and

Tonight, another surge of Gulf stratus can be expected across
north and central Texas, with cloudy skies likely by sunrise. This
cloud cover, along with continued warm air advection, will lead to
a warm and humid night.

For Sunday, thunderstorms are expected to be ongoing over western
North Texas and western Oklahoma around daybreak. These
thunderstorms will likely work their way towards our northwestern
counties by afternoon. Right now, will only show chance pops
(30-50%) as there are some concerns about coverage. Depending on
which cam you look at, it could be anywhere from a solid line of
convection to a broken line of widely scattered cells. If later
cam runs begin converging around a solution showing a solid line,
pops will certainly need to be increased, and perhaps increased a
bit farther east as well. For this forecast, will keep pops below
15% for the Dallas/Fort Worth metropolitan area. It is Worth
mentioning however that a few models do show some isolated to
widely scattered thunderstorms in the dfw area late Sunday
afternoon. Anyone with outdoor plans for Sunday should check back
with later forecasts.

Forecast soundings from the hrrr in the vicinity of model
forecasted convection show large surface temperature/dewpoint
spreads and inverted-v profiles. Downdraft cape approaching 1,000
j/kg and steep 0-3 km lapse rates of nearly 9 c/km would allow for
efficient evaporative cooling within the precipitation core of
thunderstorms, leading to gusty outflow winds. The severe weather
threat is low overall, but some thunderstorms will be capable of
producing wind gusts in excess of 40 mph. Cloud-to-ground
lightning will be a threat with all thunderstorms. In terms of
heavy rainfall potential, precipitable water values have come down
from their levels a few days ago, but will remain above the
climatological 90th percentile value for late September. Combined
with deep warm cloud layer, thunderstorms will be efficient
rainfall producers, but unless storms remain over an area for an
extended period of time, flash flooding will likely not be a
significant concern.



Preliminary point temps/pops...
Dallas-ft. Worth 75 92 75 90 75 / 0 10 20 30 20
Waco 74 96 73 94 73 / 0 5 5 10 10
Paris 72 89 72 87 71 / 0 20 30 40 30
Denton 74 91 74 88 73 / 0 10 30 30 30
McKinney 74 92 74 89 73 / 0 10 30 30 30
Dallas 76 92 76 91 75 / 0 5 20 30 20
Terrell 74 92 74 91 74 / 0 10 20 20 20
Corsicana 73 92 72 93 72 / 0 10 10 20 10
Temple 73 94 72 93 72 / 0 10 5 10 10
Mineral Wells 72 90 71 89 71 / 0 10 30 30 30


Forward watches/warnings/advisories...

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