Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Fort Worth Texas
647 PM CDT sun Apr 19 2015
For the 00z tafs...VFR conditions are expected to persist through
the valid forecast period.
Breezy northwesterly winds are expected to continue through this
evening across north and central Texas. Low-level northwesterly
flow will continue to usher drier air into the region. This dry
low-level air mass is expected to keep VFR conditions at all area
airports over the next 36 hours. Breezy northwesterly winds will
subside to 5 to 10 miles per hour after midnight. Winds will slowly veer
around to the northeast tomorrow afternoon.
Previous discussion... /issued 337 PM CDT sun Apr 19 2015/
satellite loop shows the upper level low is currently tracking
eastward through Oklahoma while a cold front has pushed through
most of the County Warning Area. Convection is firing along the front just beyond
the southeastern County Warning Area border...and this activity will continue to
move east and southeast away from the region through the evening
hours. Isolated storms are still possible in Anderson and Leon
County through 7 PM and we will continue to monitor for that.
Some steep lapse rates from the surface through the upper levels
exist across the Red River counties closer to the upper level low.
This will yield a low amount of convective instability in this
region through sunset and may result in a few showers or weak
storms along the Red River. Will mention isolated activity in the
forecast through 9 PM.
Otherwise the low level dry/cold advection will continue through
the evening and overnight hours across north central Texas...with
temperatures bottoming out in the middle 40s to lower 50s for lows. Monday
will be a very nice day with mostly sunny skies...low humidity and
light winds as the surface high moves across. Highs will top out
in the low 70s. Increasing middle level clouds will occur Monday
night...but temperatures will still benefit from some radiational
cooling with lows ranging from the upper 40s to middle 50s.
As we have mentioned for the last several days...model guidance is
really struggling with the middle to late week forecast due the fast
west-southwesterly flow aloft. It is just unable to time the
subtle disturbances well enough for any consistency and it seems
every model run just yields a different rainfall forecast. There
is some continuity regarding an upper level impulse that tracks
through Oklahoma Tuesday...but the timing ranges from early
Tuesday morning per the European model (ecmwf) to late Tuesday evening on the NAM.
Either way...this system will result in fairly strong warm
advection/isentropic lift across the northwestern and northern
zones. The airmass where the isentropic lift occurs will contain
some convective instability...so elevated showers and storms would
be the result. Will show some low probability of precipitation across the northwest and
northern zones both Tuesday and Tuesday night...and if models get
a better handle on the timing...these can be raised/lowered. The
severe weather risk appears to be too low to advertise in the
public products. Otherwise Tuesday will feature increasing clouds
and southerly winds which will result in higher dewpoints and
temperatures warming into the middle 70s during the afternoon. Mostly
cloudy skies Tuesday night will keep lows much warmer and
generally near 60 degrees.
The southerly flow will continue to bring warmer and more moist
air into the region Wednesday. It is possible a dry line may be
close enough Wednesday afternoon for convection that fires along
it to impact our County Warning Area. Furthermore the European model (ecmwf) and GFS are indicating
a weak cold front sliding in from the northeast Wednesday evening.
Both of these models indicate scattered convection Wednesday night
as the front will provide a favorable zone for warm advection and
isentropic lift with elevated instability in place. Will bump probability of precipitation
up over the northeast half of the County Warning Area to 30-40 Wednesday night.
Moisture and temperatures will continue to increase Thursday and Friday
with highs in the lower 80s and lows in the middle 60s. This will
result in a moderately unstable airmass over the region. The dry
line will likely become the primary focus for thunderstorms and
the cap should be weak enough for storms to develop during the
afternoon hours. Again due to model forecast uncertainty will keep
probability of precipitation at 30 percent areawide for Thursday...but on Friday all of
the models do agree that a stronger shortwave trough will move
through the region with an associated cold front. Friday and
Friday evening should represent the best chances for rain and
storms area wide. Both Thursday and Friday look like the days we
will need to watch more closely for severe weather potential.
Behind the Friday night cold front...temperatures cool to near
normal with a dry and pleasant forecast for next weekend.
Preliminary point temps/pops...
Dallas-ft. Worth, Texas 50 72 53 74 61 / 0 0 0 10 20
Waco, Texas 48 72 50 74 62 / 0 0 0 10 10
Paris, Texas 48 70 48 73 55 / 10 0 0 20 30
Denton, Texas 48 71 50 73 59 / 5 0 5 20 20
McKinney, Texas 49 71 50 73 59 / 5 0 0 20 30
Dallas, Texas 53 73 54 75 62 / 0 0 0 10 20
Terrell, Texas 52 72 51 74 61 / 5 0 0 10 20
Corsicana, Texas 51 72 53 75 61 / 5 0 0 10 10
Temple, Texas 49 73 53 76 62 / 5 0 0 10 10
Mineral Wells, Texas 48 71 50 74 60 / 5 0 5 20 20