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Area forecast discussion...updated 
National Weather Service Fort Worth Texas 
1014 PM CDT Sat Mar 20 2010 


Update... 
no significant updates to the forecast tonight. Have lowered probability of precipitation 
slightly for Young and Jack counties...and increased probability of precipitation for the 
north central counties for the next several hours. Heaviest band 
of snow is now located from Gainesville to Denton to Dallas...and 
will gradually push east during the late evening and overnight 
hours. 


We have also issued a Special Weather Statement discussing the 
freezing temperatures over much of North Texas tonight. Some 
sensitive vegetation may be impacted. 


&& 


Aviation... 


For the 00z tafs...a band of snowfall is moving towards dfw taf 
sites at forecast time. Within this band visibilities may briefly 
fall below 1 mile but should generally hold around 2 miles. This 
heavier band of snow is expected to last an hour to an hour and a 
half. Behind this band...snow should taper off and visibilities 
will start to improve back towards MVFR conditions. On and off 
light snow shower activity is expected to continue through at 
least midnight...however additional bands of heavy snow are 
generally expected to remain north of the metroplex after sunset. 
Primary concerns after midnight are the winds for Sunday...as 
northwesterly winds look to once again increase to 20 to 25 miles per hour 
with gusts to 35 miles per hour. If winds come in a bit stronger this could 
create dangerous cross wind conditions for north south oriented 
runways. Winds look to diminish quickly after sunset on Sunday 
with a return to VFR conditions likely. 


Tonight...IFR conditions during periods of snow...otherwise MVFR 
ceilings. 


Sunday...low VFR or high MVFR ceilings. Strong northwesterly winds. 


Sunday night...VFR with diminishing winds. 


Cavanaugh 






&& 






Previous discussion... /issued 354 PM CDT Sat Mar 20 2010/ 
upper level low is now situated over childless and continues to 
propagate east-southeast just south of the Red River valley. 
Latest trends and model data suggest that the ongoing forecast is 
in reasonably good shape and no major changes were made with this 
forecast package. The heaviest snowfall and most significant 
impacts from this system still look to be northeast of a line from 
Gainesville to McKinney to Canton where accumulations of 2-4 
inches are possible. To the west of this line...snow should be 
lighter with accumulations between a trace and 2 inches. Temperatures 
will be close to freezing...and warm grounds mean most roads will 
remain wet...except in the heavier snow area in the northeast County Warning Area. 
One of the impacts with this system will be reduced visibilities 
from snow and blowing snow...but all in all expect a rather low 
impact event for southern parts of the advisory from Graham into 
the metroplex. 


Wrap around snow band has developed northwest of the County Warning Area and will continue 
to move eastward during the overnight hours. With the exception of 
the 12z NAM /which was discarded/...models are in good agreement 
with the track of the upper low...and all show significant 
deepening of the 500 mb height center by morning. This should 
enhance the isentropic upglide over the northeast zones where the 
more significant snow is forecast late tonight and Sunday morning. 
Snow will continue to linger across the NE into the afternoon 
before finally ending with the departing upper low. There is still 
a possibility of a Heavy Snow Warning being issued for the Paris 
region for amounts in excess of 4 inches...but the current 3-4 
inch amount forecast is in agreement with all perfect forecast data 
from global models and sref mean. Some light snow flurries may 
extend as far south as the Waco area tonight but accumulating 
snows become less likely south of I-20. 


Very gradual clearing should occur beginning late tonight in the 
SW zones and spreading northeast through the day tomorrow. As far 
as low temperatures...a light freeze appears likely over the western and 
northern zones tonight...but many locations will be saved from a 
damaging late season freeze by the clouds and winds tonight. Winds 
will remain strong all evening and the Wind Advisory may need to 
be extended into the overnight hours. Regardless...a Wind Advisory 
will be needed tomorrow when deep mixing of the boundary layer 
will occur. Some gusts to 40-45 miles per hour will be possible especially 
over the sunny southwest zones. Winds will continue at 5-15 miles per hour 
Sunday night with warming thermal profiles via subsidence. The 
weak mixing of above freezing air aloft should counter the 
radiative heat loss from clear skies...and again expect most of 
the area to be saved from a hard freeze. 


A rapid warm up will occur by Monday and especially Tuesday with 
lots of sunshine and warmer southerly winds. The next system will 
arrive on Wednesday night or Thursday...and it looks like 
moisture/lift/instability will be available for a good chance of 
showers and storms. Slightly cooler and drier weather is expected 
for Friday and Saturday. 


Tr.92 






&& 




Preliminary point temps/pops... 
Dallas-ft. Worth, Texas 32 45 34 66 43 / 60 10 0 0 0 
Waco, Texas 33 54 33 69 40 / 5 5 0 0 0 
Paris, Texas 32 38 31 56 36 / 80 90 10 0 0 
Denton, Texas 31 43 32 65 39 / 70 20 0 0 0 
McKinney, Texas 32 41 31 62 36 / 90 40 0 0 0 
Dallas, Texas 32 44 34 65 42 / 60 20 0 0 0 
Terrell, Texas 33 43 33 62 39 / 40 30 0 0 0 
Corsicana, Texas 33 45 34 66 41 / 10 10 0 0 0 
Temple, Texas 32 57 34 71 39 / 5 5 0 0 0 


&& 


Forward watches/warnings/advisories... 
Winter Weather Advisory until 7 am CDT Sunday for txz091-092- 
100>103-118-119. 


Winter Weather Advisory until 4 PM CDT Sunday for txz093>095- 
104>107-120>123. 




&& 


$$