388 
fxus63 klbf 062004 
afdlbf 


Area forecast discussion 
National Weather Service North Platte NE 
305 PM CDT Monday Oct 6 2008 


..forecast challenge is precipitation potential with next weekends 
system... 


Synopsis... 
active 500 mb pattern continues across the Continental U.S. Today with a broad trough 
extending along the Lee of The Rockies...from central Montana into northestern 
nm. Ridging extends from the upper Mississippi Valley into Hudson 
Bay. Further east...another trough extends northeastward from the eastern Great 
Lakes into the Canadian Maritimes. A quick look at WV imagery this 
afternoon indicates two centers of circulation. The first is over S 
central Kansas and the second over extreme northwestern ND. Strong subsidence 
noted over the nebr Panhandle...eastern Colorado and western South Dakota at this time. 


Discussion... 
near term...tonight through Thursday night...end timing of 
precipitation this evening...then temperatures and precipitation 
threat Thursday night are the main forecasting challenges in the 
near term. 


Beginning with this evening...both the NAM and GFS solutions 
indicating strong isentropic downglide and associated subsidence shifting 
quickly east across the eastern third of the forecast area this 
evening. Plan right now is to keep precipitation going in the eastern zones 
this evening. Will tweak this a bit toward issuance based on radar 
trends. 


As for temperatures...nice warmup in store for tomorrow as zonal 
flow develops across the central Continental U.S. And southwesterly flow develops on 
the back side of a weak area of high pressure. Based on 850 mb 
temperatures...generally went with the high side of guidance favoring the 
FWC numbers with 70s west and upper 60s east. On Wednesday...maximum 
temperatures will fall back into the 60s as a dry cool front passes 
across the County Warning Area. Utilized 850 mb temperatures for guidance as the mav...met and 
FWC guidance is too warm with highs in the 70s forecast. The before 
mentioned cool front will stall along the Kansas/nebr border on 
Thursday...placing the County Warning Area in cool eserly flow. Undercut mex 
guidance some due to a combination of cool upslope flow and expected 
cloudiness. 


The upper air pattern will begin to transition to meridional on Thursday 
night as a 300 mb jet streak drops south along the Pacific coast. An 
exiting downstream jet streak over the northern tier of states...will 
further enhance middle level frontogenesis and lift across the Dakotas and 
northern Nebraska Thursday night. Though moisture appears limited...middle 
and upper level forcing robust enough to warrant continuation of low 
probability of precipitation for northern areas. 


Long term...Friday through Monday...main forecasting challenge is 
how to deal with the next major weather maker this weekend. Model 
consistency continues to remain an issue after Friday and will 
continue to follow the latest National guidance on this system. This 
equates to a slower and warmer Euro solution...which dives the 500 mb 
low south into the Great Basin...lifting it north-northeastward into the northern 
plains on Sunday/Monday. With this solution...the County Warning Area is expected to 
remain dry and in the warm sector through Saturday night...with the 
best chances for precipitation coming with the frontal passage late Sat night 
and Sunday. One word of caution...this system will need to be 
monitored very closely over the next few days. If the Euro solution 
begins to trend toward the colder GFS solution...we could see the 
first snows of the year across the northwestern County Warning Area beginning Friday night. 


&& 


Aviation... 
upper low moving across Kansas at this time with deformation zone precipitation aligned 
north/S across central Nebraska. MVFR/IFR conditions are under the main 
precipitation shield...along and east of Highway 281...otherwise ceilings are at 
VFR levels or unlimited including taf sites. As upper trough moves 
eastward through the evening hours...VFR conditions should move into 
remainder of lbf County Warning Area. 


Lbf watches/warnings/advisories...none 


$$ 


Aviation...deep 
short and long term...buttler