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Area forecast discussion
National Weather Service Fort Worth Texas
630 PM CDT Sat Mar 23 2019

/00z tafs/

Main concern in the immediate short term will be the potential for
thunderstorms to the west to make it into the metroplex later this
evening. Impacts to westbound departures/arrivals will be likely
for at least the next several hours with the developing showers
and thunderstorms from Ranger to Jacksboro to Bowie. The coverage
of showers and storms should remain scattered but the activity
will spread east through the evening. We'll keep vcsh prevailing
for the next several hours although much of the ongoing activity
may begin to spread east by 8-9 PM. Otherwise, cigs will remain
around 3500 ft through late evening before lowering to MVFR around
midnight. Persistent southerly flow will keep moisture in place
and the lower cigs are likely to continue into midday Saturday
before scattering out in the afternoon. A weak cold front will
slide southward into the area around midnight Saturday night and
could be accompanied by additional scattered showers and

At Waco, most of the precipitation should stay to the north this
evening, although MVFR cigs are expected later tonight into midday



Short term... /issued 318 PM CDT Sat Mar 23 2019/
/through tonight/

A plume of Gulf moisture has blanketed the I-35 corridor with
clouds, and underneath it, temperatures have struggled to reach
70f, despite gusty south winds. Dew points have topped 60f within
this strip of enhanced moisture, bracketed by a sunnier but drier
boundary layer. In our western zones, the sun has pushed
temperatures into the upper 70s at peak heating, resulting in a
narrow band of MLCAPE values in excess of 1000 j/kg. Veering 700mb
flow has re-established a capping inversion, evident in the
lethargic cumulus field. Although this flow will help a dryline near
the western edge of the cumulus to make additional progress eastward,
the veered surface flow ahead of the boundary will also work
against convective initiation. Sunset at our western Frontier is
7:50 p.M. CDT so there are still a few more hours available for
development, and we will continue to monitor the cumulus field for any
enhanced bubbles. The northern extent of the dryline will have the
greatest mechanical forcing, and the cams that suggest deep
convection may occur appropriately focus this potential within our
northwest zones. These convective elements would be inclined to
move eastward and could approach the I-35 corridor, along and
north of the Dallas/Fort Worth metroplex. While these will
initially have a marginal hail/wind threat, the quality of the
surface parcels will diminish as they move east, with a resulting
downward trend in intensity. However, the updrafts will continue
to benefit from favorable lapse rates aloft and will have a
tendency to rotate, so even if they separate from the boundary
layer, the hail threat may continue deep into the evening hours.
Pops for the evening period are a combination of this potential
and any remaining warm advection showers and isolated
thunderstorms further downstream, The Union of which will be along
and north of the I-20 corridor. A reinforcing blanket of clouds
and breezy south winds will keep tonight's low temperatures 10 to
15 degrees above normal.



Long term... /issued 318 PM CDT Sat Mar 23 2019/
/tomorrow into next weekend/

There are two areas of focus for the upcoming extended period:

1) strong/severe thunderstorm potential across parts of North
Texas tomorrow into tomorrow night.

2) increasing rain/thunderstorm chances late this week into next

For tomorrow, most (if not all) of north and central Texas should
start the morning covered by a blanket of saturated air centered
around 925 mb. The shortwave impulse glancing our area today will
be departing the plains to the east, leaving behind veered low-
level flow. At first, this regime should maintain cloud cover
through mid-day in many locales, but increased mixing from the
west and downslope trajectories are expected to yield clearing
west of the I-35 corridor. Ahead of a front sagging down from
Oklahoma, temperatures will climb above normal, well into the 70s
and even some 80s in spots, enhanced by the aforementioned
clearing across western areas.

A secondary mid-level vorticity lobe will rotate around a closed
low over the Missouri Valley during the afternoon, helping to
drive the front/wind shift southward across the Red River by mid-
evening. Convergence along this front will serve to initiate
storms towards sunset and thereafter, especially across northeast
Texas (discussed more below). However, what also should be
watched is an afternoon potential for any isolated deep convection
along a possible weak trough extending south/southwest from the
front towards the Concho Valley. Forcing for ascent will be weak
to non-existent at this time, though. Additionally, dry air near
parcel lfcs and 850-700mb flow somewhat normal to this boundary
may limit residence time enough to preclude any earlier-day
convection. With that said, this conditional potential should be
watched, given effective shear of 40+ kt and sufficient mid-level
lapse rates for a hail threat.

Confidence in thunderstorm chances increases considerably
near/after 00z, when a secondary impulse grazes the Red River
valley and more earnestly drives the front southbound. The
strongest low-level convergence and deep ascent should be focused
towards the arklatex, and this is where pops are highest Sunday
night. MLCAPE values upwards of 1000 j/kg and plentiful bulk shear
could support large-hail growth in the strongest cores, but flow
parallel to the front should force more linear modes into the
early overnight, transitioning the main threat to locally
damaging gusts. The tornado potential, while non-zero, continues
to appear low, owing to the aforementioned veered flow,
unfavorable storm Mode, and slightly less-than-desirable surface
moisture. Convection is expected to gradually weaken with
southward extent by Monday morning, as cells move towards the
Brazos Valley and away from stronger ascent.

Under the influence of the Post-frontal surface ridge, temperatures
will be a little cooler during the first half of the week, and dry
conditions should prevail. Return flow then commences late
Wednesday and persists into the second half of the week as an
upstream trough organizes across the western US. Large uncertainty
remains with the evolution of synoptic and smaller-scale features
Thursday into next Saturday, thanks to a series of notable
impulses expected within the broader trough, as well as the
influence of an active northern stream. Regardless, one or more
rounds of rain and storms will be possible during this time period
as large-scale ascent and moisture amplify ahead of an approaching
surface front. At least a few strong storms would be likely, and
this potential will be monitored over the coming days. Given
spatiotemporal uncertainty with larger-scale trends, no individual
period appears worthy of more than low-end chance pops at this
time, though.



Preliminary point temps/pops...
Dallas-ft. Worth 62 82 55 72 47 / 20 20 40 5 0
Waco 61 81 58 76 48 / 10 10 30 5 5
Paris 57 75 52 69 45 / 40 40 60 5 0
Denton 60 80 52 72 45 / 30 20 30 5 0
McKinney 61 79 53 72 46 / 30 30 50 5 0
Dallas 63 82 56 73 48 / 20 20 50 5 0
Terrell 60 78 55 73 47 / 20 20 60 5 0
Corsicana 60 78 58 73 48 / 20 10 60 10 0
Temple 60 81 59 75 50 / 10 10 20 10 5
Mineral Wells 58 83 51 73 45 / 20 10 20 5 0


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