872 
fxus63 klbf 060758 
afdlbf 


Area forecast discussion 
National Weather Service North Platte NE 
300 am CDT sun Jul 6 2008 


Discussion... 
myriad of forecast challenges this period including temperatures precipitation and 
possible Hydro issues related to convection expected the next 48 
hours or so. U/a analysis indicating northern portion of western 
ridge has successfully been flattened with moderately fast zonal 
flow across northern rockies into Dakotas in place this morning. The 
main wave responsible for Delaware-amplification of ridge is moving across 
Manitoba into Ontario at this time with the next stronger wave moving into 
b.C. Lightning and water vapor imagery would suggest numerous embedded 
waves in this flow as well. GOES dpi tpw product also interesting 
this morning with strong moisture plume in place from upper MO 
valley into central Nebraska. There also seems to be a feed from the 
desert SW where strong return is beginning to appear up the lower 
Colorado valley/Gulf of cal area. Expect this moisture to pool along 
front that is hard to pick out exact location at this time due to early 
morning convection...but looks to be draped across central sdakt 
into western sandhills...then curving across southern Panhandle into 
southeast Wyoming. Front may struggle southward for a while with low level jet 
more southerly but should end up somewhere near the Platte River 
valley by middle afternoon. Instability parameters are very favorable 
for strong to severe convection this after/evening and even shear 
parameters are looking good...with front the extra focus needed for 
rotating storm with locally backed winds. Would expect all types of 
severe will be possible and will have to focus on isolated tornados potential 
with the boundary in place. Other big concern is heavy rainfall 
potential. Ffg is fairly high at this time and with convection not too 
widespred over County Warning Area the past few days will hold off on Hydro watch. 
But precipitation water values running near and inch and half by tonight near 
the pooling moisture and this is near 2 Standard dev above normal for 
early July. BUFKIT profiles showing favorable cape profiles for 
supercells early...then elongate into heavy rain with very deep warm 
cloud depths indicated. Storm motions are also minimal possibly due 
to back building potential as low level jet increases. Strong Theta-E 
ridge in place a well with low middle level dew point depressions leading to 
favorable k index values. So for now will mention heavy rain in forecast 
and pass along concerns. Fate of the front will rely heavily on 
amount of convection tonight and confidence here is not very high 
about amount and placement of higher probability of precipitation on Monday and beyond. GFS 
had this a bit farther south than NAM by Monday afternoon. Most 
likely scenario is favored area of convection behind front to be in 
NE Colorado which will then move east/NE into at least southwest County Warning Area so 
have placed highest probability of precipitation here Monday afternoon tapered northward. 
Parameters are still in place for heavy rainfall with continued 
moisture feed along northern edge of SW upper high into Central 
Plains. Temperatures next few days will be hampered by convection and 
really used best guess with easterly flow cooling temperatures down from 
saturdays readings...should mainly be in the middle to upper 80s...but 
in convection is longer lived or starts ealier this may be too warm 
next few days. Should be somewhat of a break Tuesday night through 
end of week as stronger system moves over northern plains and pushes 
high pressure into MO valley. However northwest flow will be in place and 
all bets are off for totally quiet weather. 




&& 


Aviation... 
scattered thunderstorms across northwest NE will continue to move 
east into a more unstable environment so expect thunderstorm 
activity to resurge by 12z and push through kvtn and konl between 
12z and 18z. Ceilings will remain VFR but may lower to 6kft in the 
thunderstorms. Frontal boundary will set up across southwest 
Nebraska today with plenty of moisture and instability pooling 
around the front. This will trigger thunderstorm development this 
afternoon. The strongest storms will develop in the kiml area by 
22z and spread northeastward into the koga/klbf/kbbw areas after 
00z. Visibilities with the storms will lower to MVFR...and even 
possibly to IFR briefly...in heavy rain. Ceilings may lower to 4kft. 


&& 


Lbf watches/warnings/advisories...none. 


&& 


$$ 


13/ddb