Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service Fort Worth Texas
655 am CDT Wednesday Aug 20 2014
MVFR ceilings...especially at Waco this morning...then all sites
Thursday morning to be problematic. Otherwise no major concerns.
A middle level disturbance will continue weakening as it lifts
northeast of the Red River this a.M. A 30 kt+ low level jet to the east of
this feature will continue to support showers to the north of dfw
this morning and will leave vcsh out for now. MVFR ceilings streaming
north over The Hill Country and central Texas could briefly impact
Waco by middle morning and will carry a tempo group. South winds
around 10 kts this morning will become southeast around 15 kts
this afternoon and should continue through this evening.
A slightly stronger low level jet between 30-40 kts will develop late
tonight and should allow for MVFR ceilings to push into the I-20
corridor after sunrise Thursday. Have decided to not mention MVFR
at dfw area airports for Thursday morning until timing becomes
better define. I will advertise MVFR ceilings into Waco right before
sunrise. South-southeast winds 10-15 kts will continue Thursday
with gusts to 20 kts possible by afternoon.
Previous discussion... /issued 419 am CDT Wednesday Aug 20 2014/
a few light showers north of the I-20 corridor are associated with
an exiting middle-level impulse. Much of what appears on radar is middle
cloud within this area of lift...but a few sprinkles are likely
reaching the ground. This activity will gradually shift northward
into Oklahoma this morning.
While the exiting disturbance might suggest subsidence will
dominate today...synoptic scale vertical motion will be rather
neutral today. As skies clear...and the August sun heats the
surface layer...the lack of inhibition could allow for another
round of isolated/disorganized convection. However...intensifying
Lee troughing will result in southerly winds near or in excess of
15 miles per hour...which should assure any lingering outflow boundaries are
effectively obliterated. The only area of concern will be in the
far southeast...where temperatures in the middle to upper 90s will
coincide with dew points near 70f. But even with minimal
inhibition...this instability is unlikely to be realized unless
outflow from sea breeze activity upstream is able to mechanically
lift the surface layer.
By Thursday...a strengthening ridge over the southeastern states
will begin to impinge on Texas. Its influence will persist into
next week. But with the rather Ordinary Summer ridge centered well
to our east...mid-level heights will not be extraordinary for
August. Afternoon highs will still exceed normal values...climbing
into the upper 90s to near 100 degrees. Mitigating factors for the
heat will be (1) a steady southerly breeze due to persistent Lee
troughing and (2) dew points mixing out into the 50s west of I-35.
Extended guidance suggests the upper tropical trough responsible
for the unsettled weather in the northwestern Gulf of Mexico could
ride over the western periphery of the middle-level ridge this
weekend. It looks as though large-scale subsidence beneath it
should effectively stifle it...but with little else to keep US
entertained...it may bear watching. The next legitimate chance
for rain will be Monday or Tuesday when the low-level wind field
weakens and the sea breeze may be able to reactivate. For now...
only introduced hidden 10 probability of precipitation.
Preliminary point temps/pops...
Dallas-ft. Worth, Texas 98 77 99 77 99 / 5 0 0 0 0
Waco, Texas 99 76 99 76 99 / 5 5 0 0 0
Paris, Texas 97 74 97 74 97 / 10 0 0 0 0
Denton, Texas 98 76 99 76 99 / 10 0 0 0 0
McKinney, Texas 96 75 97 75 97 / 10 0 0 0 0
Dallas, Texas 97 77 98 78 98 / 5 0 0 0 0
Terrell, Texas 97 75 97 75 97 / 5 5 0 0 0
Corsicana, Texas 97 74 98 75 98 / 5 5 0 0 0
Temple, Texas 98 75 98 75 98 / 5 5 0 0 0
Mineral Wells, Texas 98 73 98 73 100 / 5 0 0 0 0