Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service Fort Worth Texas
1131 PM CDT Sat Jul 23 2016
VFR conditions are expected to prevail at the taf sites through
The scattered showers and thunderstorms that developed Saturday
moved to just east of a kdua-ktyr line during the late afternoon
and evening hours before dissipating. Isolated to scattered
showers and thunderstorms are expected to develop again Sunday and
may move into areas east of a kgyi-kcrs-klhb line from mid
afternoon /21z/ through sunset /02z Monday/. This activity may
affect the eastern arrival/departure gates but is not expected to
directly affect the taf sites.
Winds of 5 to 10 knots will be generally southerly (varying
between southeast and south southwest). Expect some afternoon
cumulus and there may also be some cirrus debris from
thunderstorms to the east late afternoon into the evening hours.
main update to the forecast revolve around hourly temperature and
Isolated convection that developed across The Ark-la-tex
continues to wane this evening with the loss of daytime heating.
The remainder of the evening and into the overnight hours should
be dry across all of the forecast area, with perhaps a few
sprinkles to the southeast of Palestine. Diurnal convection is
expected to develop again tomorrow mainly across eastern zones as
the upper ridge becomes anchored to the northwest. In addition,
an outflow boundary extends near a Bonham to Greenville to
Palestine line and this may be a focus for convection Sunday
afternoon. Weak vertical wind shear should limit organized storm
structures, however, given steep sub- cloud lapse rates, a threat
for damaging downburst winds and strong convective outflows will
Otherwise, the remainder of the forecast remains in fantastic
shape and updated products have been transmitted.
Previous discussion... /issued 339 PM CDT Sat Jul 23 2016/
afternoon visible satellite imagery shows an expanding cumulus
field dotting the landscape across roughly the eastern half of our
County Warning Area. Isolated thunderstorms are popping within a zone of enhanced
pws--approaching 2 inches per recent satellite analysis--and are
barely moving as winds in the cloud-bearing layer are about 5 kts.
For the remainder of the afternoon, have continued the isolated
thunder wording (pops less than 20%) east of a roughly Bonham to
Palestine line, amidst the better low-level moisture. Given the
dry adiabatic nature of the boundary layer, it's not surprising to
see dcape values in excess of 1000 j/kg, so gusty downburst winds
are a possibility in and near any convection this afternoon.
The compact shortwave currently meandering slowly westward over
the lower Tennessee Valley will approach our region tomorrow, and
will once again be the impetus for isolated afternoon convection.
It still appears as if this activity will remain east of the
metroplex as the effects of large-scale subsidence and slightly
drier low-level air will work against convective development. Heat
index values will once again flirt with the 105-degree mark
tomorrow afternoon, before a cooling trend takes place to start
The aformentioned mid-level disturbance will move overhead on
Monday and Tuesday, which will set the stage for more widespread
shower and thunderstorm activity. Based on recent sref, ECMWF, and
gefs output, opted to give pops a nudge upwards across most of the
region on Monday and then southern portions of the County Warning Area on Tuesday.
Precipitable water values during this time frame will likely rise in excess of 2
inches, approaching 1.5 to 2 Standard deviations above our
climatological normals. As a result, we'll need to watch for the
potential for some locally heavy rainfall.
By Wednesday, the forecast becomes a little more unclear as the
main global models offer varying solutions regarding the track of
a weak TUTT feature presently just off the eastern Florida coast.
The ECMWF, along with its ensemble system, has consistently kept
this low just south of the region. The GFS on the other hand has
been Flipping back and forth with its solutions recently. Based on
the position of the deterministic European solution within its
ensemble envelope, opted to relegate 30% pops to our southernmost
zones on Wednesday with uncertainty too great to warrant anything
higher at this time.
By the end of the week, we'll be in the midst of a mid-level
weakness, with the flow becoming westerly to northwesterly. This
may allow convection firing to our north and west to slide into
our northern zones during the afternoon and evening hours. That
said, low-level wind fields appear to remain relatively weak at
this time, which should keep any large mesoscale convective system-type activity from
driving through our County Warning Area. Low-end pops confined to near the Red
River will suffice for now.
Preliminary point temps/pops...
Dallas-ft. Worth 81 100 79 97 79 / 5 10 10 40 20
Waco 79 100 78 97 76 / 5 10 10 40 20
Paris 77 98 76 94 75 / 10 20 20 50 20
Denton 77 99 76 96 75 / 5 10 10 40 20
McKinney 78 98 77 95 76 / 5 10 10 40 20
Dallas 82 100 80 96 79 / 5 10 10 40 20
Terrell 78 97 77 94 76 / 10 20 20 40 20
Corsicana 78 97 78 95 76 / 10 20 20 40 20
Temple 77 99 77 97 75 / 5 10 10 40 20
Mineral Wells 75 100 75 97 74 / 5 5 5 30 20