Weather

701 
fxus63 kgid 080526 
afdgid 


Area forecast discussion 
National Weather Service Hastings NE 
1226 am CDT Monday Sep 8 2008 


Aviation...06z kgri taf. Main concern for this period is the well 
advertised precipitation event moving in later tonight and lasting 
through around middle day Monday as a fast moving but potent upper 
level disturbances traverses the region. Expecting a fairly steady 
rain event lasting primarily between the 11z to 17z time 
frame...with ceilings and visibilities settling into the LIFR and 
IFR range. As the system rapidly pulls out of the area during the 
afternoon ceilings should steadily climb back into MVFR and VFR 
territory...with mainly clear skies and light winds expected by 
evening. Fog could be an issue early Tuesday morning...but this 
appears to be more of an issue after this taf valid period. 


&& 


Previous discussion... /issued 324 PM CDT sun Sep 7 2008/ 


Short term...tonight through Monday night. The upcoming rain event 
takes center stage. A westerly to northwesterly flow pattern 
aloft was in place across our region while the next wave to impact 
our weather tonight into tomorrow was beginning to emerge from The 
Rockies. The surface frontal boundary had pretty much stalled 
along the Nebraska and Kansas border while the surface low was 
deepening in west central Colorado. There are plenty of factors 
tonight to contribute to a decent...widespread rain event. 
Isentropic lift increases tonight ahead of the approaching wave as 
indicated on the 310k surface. There is an onset of Theta-E 
advection tonight and the lowlevel jet strengthens to around 
40kts...providing lift over the baroclinic zone and good 
frontogenetic forcing. Moisture pools along the boundary tonight 
and precipitable water values nearly an inch and half along/south 
of the front...and roughly a half to three quarters of an inch 
north of the front. Decent rainfall amounts are likely especially 
in our southern zones in moisture axis. Convection should initiate 
to our west later this evening/early tonight and then spread east 
across our County Warning Area after 06z aided by the strong lowlevel jet. 
Instability parameters indicate elevated instability across our 
southern zones tonight...and have thunder mention into our 
southern Nebraska counties. Cannot rule out severe weather in the 
south and will mention the potential in the severe weather potential statement. Forecast had probability of precipitation 
near 100 percent and only change was to move up timing of highest 
probability of precipitation based on quicker model trends. 


The precipitation will wind down rather quickly late Monday morning as the 
trough axis moves through temperatures will see little diurnal range 
in the cool airmass. Dry and cool weather will be common Monday 
night as the surface high settles in. 


Long term...Tuesday through Sunday. Active pattern continues over 
the area through the period. The first few days will feature a 
warming trend and dry conditions as surface high pressure moves 
east. Southerly flow on the backside of the ridge will cause temperatures 
to warm and should begin to increase moisture and instability over 
time. In the meantime a strong shortwave will deepen and dig south 
over the northern rockies through Wednesday night. This system will 
provide a decent chance of thunderstorms...some of which may be 
severe. Models suggest a surface boundary will be across the area 
from Wednesday night through Friday morning as the upper trough 
continues to be reinforced by upper level energy and remains poised 
over the northern rockies. By Friday night...this low is forecast to 
begin to earnestly move east of the area...thus chances of rain will 
diminish.Temperatures through the period are expected to be at or a 
bit below normal. 


&& 


Gid watches/warnings/advisories... 
NE...none. 
Kansas...none. 
&& 


$$ 


Aviation...pfannkuch