016 
fxus63 kdmx 081129 aaa 
afddmx 


Area forecast discussion...updated 
National Weather Service Des Moines Iowa 
528 am CST Thursday Jan 8 2009 


..updated aviation discussion... 


Discussion... 
fairly quiet today albeit cold as high pressure sinks southeast 
across central Iowa. Little change from going forecast was made 
today. 


The same cannot be said for tonight through early next week. The 
models have really cranked up the moisture profile from the last 
several days..especially for late tonight north and Friday and 
Friday night central and east. I am understandably suspect of this 
major change however all the models have come on board with this in 
wetter solution. As a result probability of precipitation...quantitative precipitation forecast and snow amounts were 
increased across the north and east. The initial precipitation starts 
tonight in a band of warm advection ahead of the main system as a 
shortwave approaches. The models now strengthen the surface low as 
a strong short wave drops out of Canada. It now appears possible 
for accumulating snow in the far north and east but over several 
periods and for differing reasons. The initial warm advection band 
tonight will produce snow across the north then as warmer air moves 
into mainly the southern half of the state for Friday snow becomes 
mixed with or changes to light rain or drizzle south with a mixed 
bag of precipitation north. Where moisture profiles last night were 
showing a depth of moisture around 100 mb now we are looking at 
saturation levels of several thousand feet. There is not a lot of 
Omega but enough that any drizzle or freezing drizzle may precipitation out 
heavy enough to call it light rain/freezing rain. There is also 
enough of a warm layer for sleet between I-80 and Highway 20. 
Confidence is low ni placement and even ptype as this is a big 
change from the past couple nights. Then for Friday night...def 
zone precipitation hits central and eastern Iowa but by this time enough 
cold air becomes entrenched over central Iowa that ptype should be 
in the form of snow. 


For the weekend...the models are now hinting at another wave pushing 
across late Saturday and Sunday. Light quantitative precipitation forecast is being suggested but 
at this point it doesn't look like more than flurries. A major cold 
push still looks on tap for the first part of next week. Monday 
still looks near normal but temperatures will be plummeting in the 
afternoon and through middle week highs will be in the single digits 
and teens with lows below zero. 


&& 


Aviation...08/12z 
VFR conditions are expected to prevail during the first 12 hours of 
the taf. An Alberta clipper passing to then tonight will bring 
increasing moisture tonight...mainly over the northern sections. 
Expect some light snow to develop with greatest threat near mcw 
along with the potential for MVFR ceilings. 


&& 


Dmx watches/warnings/advisories...none. 


&& 


$$ 


Short term...Lee 
long term...MS Jan 09 
aviation...donavon