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Area forecast discussion 
National Weather Service Norman OK 
1155 am CDT Sat Mar 20 2010 


Update... 
as the center of the middle level circulation associated with the 
current winter storm tracks across southern Oklahoma...a break in 
the action is being experienced across much of south central 
Oklahoma. Snow bands are present just east of the okc metropolitan 
area...with at least light snow persisting over northern OK. 


Snowfall associated with wraparound moisture on the back side of 
the low has moved into southwestern OK and western North Texas. We 
are expecting snow to gradually end from west to east in this area 
this afternoon as the low continues its eastward track. Greatest 
concern is still for areas of east central into northern Oklahoma 
that should see the longest duration of snowfall this afternoon 
into tonight. 


Probability of precipitation have been revised to reflect the decreasing chances in the 
west...with other aspects of the forecast changing little. 


Taylor 


&& 


Previous discussion... /issued 653 am CDT Sat Mar 20 2010/ 


Aviation... 
MVFR tempo IFR/LIFR in -sn/br and eventually some blsn once snow 
starts to accumulate. Have followed the 06z NAM which depicts 2 
main pulses of potentially heavier snow... one moving NE into 
ncentral OK this morning and a 2nd wave entering SW OK around 18z 
and moving NE to affect central/ncentral OK 21-03z. Snow ending 
kgag this afternoon and over the rest of the west OK tafs and ksps 
this evening/overnight followed by gradual breakup of the lower 
ceilings in these areas. 


Previous discussion... /issued 352 am CDT Sat Mar 20 2010/ 


Discussion... 
upper low is prognosticated to take a near-optimal track for heavy snow 
across northern-central-eastern OK as it moves from nm east-southeast-Ward 
along/near the Red River into the arklatex by Sunday morning. 
Multitude of precipitation types being reported with the initial 
transition this morning... but the changeover to snow should be 
more swift later today as dynamic cooling arrives ahead of the 
approaching upper low. We will add a few more counties in southeast OK to 
the warning... and the rest of the area not in the warning will go 
to an advisory for snow and blowing snow. The current expiration 
times are generous given that model qpfs begin shutting down the 
snow in the west/northwest by this afternoon. Later shifts will likely be 
hacking away at the warning/advisory areas as the snow tapers 
off. 


This event will likely bring okc to a new seasonal record for snow 
by the time it ends. It might have set more records than that had 
there been more cold air established over the area prior to the 
event. As it is... much of the early part of the event will be 
rain or mixed precipitation. There is also the consideration of blizzard 
or near blizzard conditions... and perhaps the need to upgrade to 
a Blizzard Warning. At this time we are not confident enough that 
wind speeds and visibilities will justify that... and since we 
have maintained emphasis on the winds and blowing snow from the 
beginning... we will stick with a Winter Storm Warning for now. 


Snow should wind down this evening over much of west OK and our Texas 
zones... and early Sunday over central OK. Snow cover will keep 
temperatures down for a while thereafter... but it typically does not 
linger very long this late in the season and so we will bring 
temperatures back up to more springlike levels again by around Tuesday. 
No signifcant changes in reasoning for middle-late week. Another 
system moves through around Wednesday-Thursday but looks weaker and with less 
cold air. 


&& 


Preliminary point temps/pops... 
Oklahoma City OK 29 27 37 27 / 100 40 20 0 
Hobart OK 32 23 40 27 / 80 10 0 0 
Wichita Falls Texas 33 28 44 30 / 80 30 0 0 
gage OK 33 24 45 20 / 70 10 0 0 
Ponca City OK 30 28 34 22 / 100 50 30 0 
Durant OK 38 31 38 31 / 100 60 40 10 


&& 


Oun watches/warnings/advisories... 
OK...Winter Storm Warning until 7 PM CDT Sunday for okz007-008-012- 
013-017>020-023>032-040>042. 


Winter Storm Warning until 7 am CDT Sunday for okz004>006- 
009>011-014>016-021-022-033>036. 


Winter Weather Advisory until 7 am CDT Sunday for okz037>039-044- 
045. 


Winter Weather Advisory until 7 PM CDT Sunday for okz046-050>052. 


Winter Storm Warning until 7 PM CDT Sunday for okz043-047-048. 


Texas...Winter Weather Advisory until 7 am CDT Sunday for txz083>090. 


&& 


$$ 


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