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Area forecast discussion 
National Weather Service Fort Worth Texas
1204 am CST sun Dec 28 2014

VFR will prevail over the metroplex through the period with just
middle-high level cloud cover. Strong upper level shortwave will move
through the region midday Sunday. Ahead of this system...lots of
moisture/lift will result in precipitation originating at an
unusually high level...near 22000ft. This precipitation will be falling
into dry air below mostly virga is expected in the
metroplex. However some saturation will occur which will bring
ceilings down to near 10000ft by sunrise. If precipitation intensity is
greater than expected over the metroplex...wet bulb cooling would
result in thermal profile favorable for sleet or snow. But there
is currently no model showing this much precipitation
available...which would be required to both cool and saturate
before any non-liquid precipitation reaches the ground. We will continue
to watch trends to monitor for this very remote possibility.

For Waco...MVFR ceilings may continue for the next hour or two but VFR
ceilings near 050 should prevail. More low level saturation is
expected -ra is in the taf from 10z to 16z. The thermal
profile looks too warm for any possibility of wintry precipitation at
Waco even after wet bulb cooling. Any rain will also be very
light...and thus no visibility restrictions are forecast.

Otherwise clouds will clear early-middle afternoon with light north
winds turning to the south Sunday evening.



water vapor shows an impressive shortwave trough moving through
northern Mexico toward the region. This system will not have much
low level moisture to work with...but there will be enough middle-
upper level moisture and lift for a large shield of rain to develop
late tonight across central Texas. This will spread northeast into
the southeast half of the County Warning Area late tonight and continue into Sunday
morning. Due to the drier air in the low levels...this
precipitation will succomb to evaporation/sublimation and
therefore rainfall will range from a tenth to quarter inch in the
southeast zones to just a trace from roughly Paris to Dallas to
lapmpasas. Probability of precipitation were expanded northwest Sunday morning...and
brought a mention of sprinkles into the metroplex...but again
little to no measurable rain is expected on the northwest edge of this
activity. Tr.92


Previous discussion... /issued 254 PM CST Sat Dec 27 2014/
the shortwave disturbance that created some winter precipitation
across our far northwest counties this past morning is slowly
exiting the area...though a few sleet pellets remain possible with
any lingering light rain. The surface cold front is now approaching
the Texas coast with cloudy...windy and cold conditions across
north and central Texas. Scattered areas of light rain will linger
across the far east and southeast counties tonight into
the larger scale upper trough moves east across the area on on
Sunday. Areas further north and west will continue to see drier
polar air intruding in with just brisk and cold conditions continuing
this period. We did lower high temperatures on Sunday into the 40s
to account for some lingering cloudiness and weak cold air advection associated
with the passing main upper trough.

The flow aloft becomes zonal the first half of this week heading
into the New Year. An elongated shortwave trough will dig southwest
across the Great Basin of Nevada/Utah/Arizona during this time. At
the surface...returning southerly winds will warm it up briefly on
Monday to between 55 and 65 degrees...before a shallow Arctic cold
front arrives early Tuesday. Though chilly and brisk conditions
arrive for the middle part of the week...a bulk of the better rain
chances will remain south and west of our area. The energy out
west is starting to show signs of closing off over Arizona by
Wednesday...but a lead shortwave will lift northeast over the area
and induce isentropic ascent over the shallow Arctic air by
Wednesday night into Thursday with models differing somewhat on
environmental profiles...precipitation types...and overall temperatures.
So confidence on the overall evolution of any winter weather
later in the week remains low...but appears some chance of a mix
will be there with chilly conditions continuing.

The Great Basin upper low will finally begin to eject east toward
and across north and central Texas at the end of the
another strong shortwave drops over the Pacific northwest. Medium
range models really begin diverging by Friday into Saturday as the
open trough lifts across the Southern Plains. The GFS is much
quicker and north with it...while the European slower and further
south. With the southeastern U.S upper high remaining relatively
strong over the Gulf of Mexico and Florida...the European model
solution appears more likely with gradual moderating temperatures
and chances for rain and thunderstorms Thursday night through
Saturday morning. We should know more on details of future systems
in the coming days...but until then we will just remain
conservative until they become more clear.



Preliminary point temps/pops...
Dallas-ft. Worth, Texas 33 49 33 58 33 / 10 10 0 0 0
Waco, Texas 35 50 31 61 34 / 20 20 0 0 0
Paris, Texas 33 48 31 55 31 / 20 10 0 0 0
Denton, Texas 31 49 32 57 29 / 10 5 0 0 0
McKinney, Texas 32 48 32 57 30 / 10 10 0 0 0
Dallas, Texas 34 49 34 59 34 / 10 10 0 0 0
Terrell, Texas 34 49 32 58 34 / 10 20 0 0 0
Corsicana, Texas 36 50 33 60 35 / 20 30 0 0 0
Temple, Texas 35 50 32 62 34 / 30 30 0 0 0
Mineral Wells, Texas 29 49 31 58 28 / 5 5 0 0 0


Forward watches/warnings/advisories...




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