Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Fort Worth Texas
539 PM CST Sat Jan 31 2015
moderate rain band will move over taf sites during the next couple
of hours but expect intensity and coverage of rain to wane by 3z.
Then precipitation will become more convective/showery...but hi-
res guidance indicates this activity will stay north of taf sites.
Still will retain a mention of vcsh through the overnight hours
and monitor radar trends for any updates.
Otherwise MVFR ceilings prevail now and these will fall to IFR this
evening as southerly moist/warm advection increases. We may need
to drop forecast ceilings below 400 feet overnight...but confidence on
this is low. Otherwise winds will veer to the SW before daybreak
which should result in gradually improving visibility/ceilings ahead of a
cold front. Front will move through around 14-15z with MVFR ceilings
continuing a few hours in its wake. VFR with north/northwest winds at 20g30kt
will then prevail by early-middle afternoon Sunday.
Previous discussion... /issued 306 PM CST Sat Jan 31 2015/
a large upper low over northwest Mexico and California/Arizona will continue to
ease eastward toward the West Texas Big Bend tonight...then stall
as it becomes detached from stronger westerlies to the north.
In addition...a strong shortwave will continue racing southeast
from the northern rockies and over the Central Plains through
Sunday morning. Warm air advection and moisture advection at 850mb will continue
through tonight in advance of these two systems as noted by the
8-10 degree/c 850mb dew points over south Texas moving northward.
A good middle level fetch of Pacific moisture will occur between
700-500mb in advance of a dry slot noted east of the upper low
over West Texas. Light rain is expected to fall across much of
the region tonight into early Sunday. Occasional pockets of
embedded thunder and brief moderate rainfall may occur across
central Texas where the dry slot and increasing middle level
instability are expected to occur in advance of a cold front
arriving on Sunday. We have only introduced isolated thunder
south of I-20...but if the dry slot pushes further north than
expected... then the forecast may need to be amended overnight.
Lightning strikes would be the only concern with marginal elevated
instability and relatively stable low levels.
As we head through the day Sunday...a strong cold front will sweep
through much of the area bringing brisk north winds and colder
temperatures Sunday night into Monday morning. By this time...the
southwest upper low will retrograde toward western Mexico in wake
of the exiting central U.S shortwave. Rain chances are expected to
end well before freezing temperatures occur across the northwest
areas Monday morning. Highs Monday will remain on the cold side
and only in the 40s as a cold surface high settles across the
plains and Mississippi Valley.
South winds readily return once again Monday night through
Wednesday with the departure of the cold high pressure dome and
pressure falls to our west. Temperatures both Tuesday and
Wednesday mornings will not be quite as cold and mostly above
freezing...while afternoon highs moderate back into the 50s east
to the 60s west. The large scale westerly flow does amplify by middle
week and begins to open up the upper low over Mexico and track it
east toward south and central Texas on Wednesday. The broad yet
relatively weak isentropic lift from this system will creep as far
north as central Texas. Have increased rain chances slightly
across our central counties while keeping our northern counties
cool and dry. Any rainfall across central Texas will be on the
light side due to moisture quality not being very rich.
The next cold front arrives by Thursday morning in wake of the
south Texas upper trough moving east over the central Gulf Coast
states. Expect another cold and dry day on Thursday with temperatures
in the 40s once again and brisk north winds. Another surface high
settles in Thursday night with near freezing temperatures once
again by sunrise Friday morning. The cold air does not stay for long
as ridging aloft and the return of south winds bring a warm up
back into the 60s for next weekend.
Preliminary point temps/pops...
Dallas-ft. Worth, Texas 51 58 30 44 35 / 90 50 0 0 0
Waco, Texas 53 63 32 47 34 / 80 40 5 0 0
Paris, Texas 46 57 27 42 30 / 90 70 0 0 0
Denton, Texas 48 56 28 44 32 / 90 40 0 0 0
McKinney, Texas 49 56 28 43 31 / 90 60 0 0 0
Dallas, Texas 51 58 30 44 35 / 90 60 0 0 0
Terrell, Texas 49 62 29 44 32 / 90 70 5 0 0
Corsicana, Texas 54 63 31 45 34 / 80 60 5 0 0
Temple, Texas 53 63 33 48 35 / 70 40 10 0 0
Mineral Wells, Texas 49 53 28 46 33 / 80 30 0 0 0