157 
fxus63 koax 212012 
afdoax 


Area forecast discussion 
National Weather Service Omaha/valley NE 
312 PM CDT sun Mar 21 2010 


Discussion... 
several weather systems to affect the local area this next week. The 
period should generally be dry through Friday night...except should the 
storm system Wednesday night into Thursday track farther north. Saturday 
and Sunday low pressure is forecast to develop over Kansas and 
should be accompanied by rain and possibly snow for our area for 
part of the weekend. 


Closed middle tropospheric low over the Gulf states and expansive 
cloud shield into Kansas and Missouri continues to pull away. 
Visbible satlt shows the snow left behind with some higher snow 
amounts in a band from around Nickerson and Lyons northeast to 
Ida Grove and Denison Iowa and another band from Falls City to 
Clarinda southward. Elsewhere...temperatures in the 40s to around 
50 have melted the snow. 


Surface high pressure will remain over the forecast area 
tonight...however return flow will begin in the northwest and will 
hinder temperatures from falling. Should see rising temperatures northwest County Warning Area Monday 
morning. Temperatures will be a concern tonight with clear skies and 
dewpoints dropping back in the teens and 20s. Wayne...to Norfolk 
and Neligh are the locations that are a concern as northwest of there the 
winds will be picking up. With such low dewpoints in place...think 
the NAM is not cool enough and went with the colder GFS temperatures in 
the upper teens to lower 20s with middle 20s northwest. 


Much warmer for Monday with h9 winds increasing to 25 to 40kts and 
increasing 850 mb temperatures ahead of a cool front. Bufkt forecast 
soundings mix down some of these stronger winds. Look for highs 
to warm into the 50s and 60s with south winds at 15 to 25 miles per hour in 
the north and 10 to 20 miles per hour in the south. 


Monday night a middle level trough of low pressure tracks across the northern 
plains and drags a cool front through the forecast area. The models 
have been going back and forth with the precipitation as there is some 
middle level frontogenesis...but may not be enough for measurable 
rain. Kept it mainly dry Tuesday with cooler highs 40s in the 
north and 50s south. 


Tuesday night into Wednesday...yet another middle level trough will 
affect the region. This weather system extends from The Rockies 
toward Baja California. By midday Wednesday...the NAM/GFS have the main part of the 
trough over The Four Corners region. With large scale lift across 
Colorado into Kansas and southern Nebraska. The low level flow 
keeps the dry fetch from the northeast in place...however the moist 
middle level flow is from the west. 


For the extended Wednesday night through Sunday. The storm system 
continues to slowly push through the plains. There are still some 
differences...with the European model (ecmwf) keeping the precipitation to the south of 
the state and the GFS closing the low off and bringing the precipitation 
into the southern quarter of the forecast area. For now left the low probability of precipitation 
in the south Wednesday through Thursday. 


The storm system for the weekend may have the best potential for 
accumulating precipitation. The GFS has a deep area of low pressure over 
the Oklahoma Panhandle with a large area of precipitation for Sat. The 
12z European model (ecmwf) is slower and has it moving through Saturday night and 
Sunday morning. The track of the storm gives both parts of 
Nebraska/Iowa/Kansas/Missouri over half an inch of precipitation. 
Thicknesses support a mix on the backside of the storm. Will 
likely need to adjust timing but did include chance probability of precipitation for Saturday 
night. 


&& 


Aviation... 
taf sites kofk/koma/klnk 


18z tafs 


VFR conditions at all taf sites through the period with light winds. 
As high pressure ridge shifts east on Monday...southerly winds will 
increase to 10 to 15 kts...with some gusts noted to about 20kts at 
kofk through 18z. 


&& 


Oax watches/warnings/advisories... 
NE...none. 
Iowa...none. 
&& 


$$ 


Zapotocny/Dewald