Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Fort Worth Texas
230 PM CST Thursday Dec 18 2014
Quite a difference across the region today as far as clouds and
temperatures are concerned. Abundant sunshine over the western zones have
resulted in temperatures into the 60s whereas low clouds have hung in
tough across the rest of the region along with weak cold air
advection resulting in temperatures still in the 40s to low 50s.
Water vapor shows a shortwave trough moving across northern Mexico
this afternoon which will begin to increase the large-scale lift from
west to east starting this evening. Position of the 850 front
continues to be appear to be the best discriminator as to where
the heavier rainfall will occur. Higher res models consistent with
keeping this feature south of the I-20 corridor...as a result that
is where the higher probability of precipitation and higher rainfall totals (around one-
half to three-quarters of an inch) are expected overnight and
mainly into Friday morning. Also appears there will be enough
instability for some elevated thunderstorms over the southern
North of the 850 mb front...fairly high probability of precipitation will reside along the
I-20 corridor but with a dry layer evident on forecast soundings
between 800-700mb rainfall totals will be quite a bit lower
(around a tenth of an inch) as the precipitation will have to
overcome this dry layer before reaching the ground. Further
north towards the Red River...probability of precipitation and accompanying rainfall
totals will be even lower.
Lift from the upper level system will decrease from west to east
during the day Friday so most of the precipitation will end by afternoon
though a few light rain showers will still be possible across the
eastern zones during the early evening hours.
Cool weekend in store for North Texas as clouds will remain across
the area though no precipitation expected. Still expecting a cold front
to push through late Monday and into early Tuesday. With northwest
flow aloft...will be difficult to get enough moisture and lift to
produce much in the way of rainfall though have kept slight chance
of probability of precipitation over the eastern zones Monday night and into Tuesday.
Coldest air with this system will stay to our northeast so
generally expect a cool dry period as we head into Christmas.
/issued 1238 PM CST Thursday Dec 18 2014/
With weak December insolation...LIFR conditions have been slow to
improve. Despite the clearing line advancing to within 50 miles of
the I-35 corridor...the onset of reinforcing cold advection within
the boundary layer should halt its progress. Ceilings will
continue to lift this afternoon but will remain IFR.
Another round of precipitation will override the cool air at the
surface...advancing from southwest to northeast late tonight into
Friday morning. The bulk of the rainfall will affect central Texas
airports...but for all taf sites...the primary impact will be the
accompanying reductions to LIFR ceilings/visibility.
Preliminary point temps/pops...
Dallas-ft. Worth, Texas 44 48 39 52 40 / 40 60 10 5 5
Waco, Texas 47 52 39 54 39 / 70 70 20 5 5
Paris, Texas 42 48 36 51 36 / 30 50 30 10 10
Denton, Texas 44 48 38 52 38 / 30 50 10 5 5
McKinney, Texas 43 48 37 51 38 / 40 60 20 5 5
Dallas, Texas 44 48 39 53 40 / 40 60 20 5 5
Terrell, Texas 44 49 38 53 39 / 50 60 20 5 5
Corsicana, Texas 46 51 39 54 40 / 70 70 20 10 5
Temple, Texas 48 52 40 56 39 / 80 70 10 5 5
Mineral Wells, Texas 44 47 38 52 38 / 40 50 10 5 5