Weather

652 
fxus63 keax 080339 
afdeax 


Area forecast discussion 
National Weather Service Kansas City/Pleasant Hill MO 
1039 PM CDT sun Sep 7 2008 




.Updated aviation discussion... 


Discussion... 


Scattered showers associated with weak middle level convergence aided 
by modest instability at the surface will continue to move from east 
central Kansas across central Missouri this evening. Do not expect 
them to amount to much. Stronger isentropic lift overspreads the 
forecast area overnight tonight ahead of the next shortwave. There 
is some elevated instability and have held on to the chance for 
thunder in the grids...however think the chance for thunder is 
minimal with little in the way of elevated instability. 


Surface low pressure continues to strengthen over the Central High 
plains tonight...helping to develop a fairly strong cold front which 
will move across the forecast area during the day Monday. Expect the 
front to be generally from Kansas City to Kirksville by midday. It 
appears there should be enough instability...especially south of the 
front during peak heating...for thunderstorms...some of which may be 
strong to severe. Think temperatures will be in the 75 to 80 range 
with dew points from 65 to 70 degrees south of the front. This gives 
surface cape in the 1500-2500 j/kg range. Other severe parameters 
indicate hail and strong winds will be the primary threats. 


Front should move through fairly quickly Monday night...with strong 
high pressure moving into northern Missouri behind it. Moist ground 
and clearing skies could lead to fog formation across the area 
Monday night. Right now northern Missouri has the best chance of 
meeting all the criteria. 


It still looks like Tuesday will be a beautiful fall day...with 
mostly clear skies...relatively light easterly winds...and 
temperatures ranging from the upper 60s in northeast Missouri...to 
the lower 70s in extreme east central Kansas and west central 
Missouri. 


Nrr 


Medium range (wed-sun) 


A high degree of uncertainty prevails in the medium range portions 
of the forecast...especially towards the end of the week with the 
possible first influences of Hurricane Ike. However...there still 
appears to be a good potential for rain Wednesday night and Thursday 
as next shortwave dives towards the region at this time. Have tapered precipitation 
chances back on Wednesday as upper trough will likely slow as it deeps 
and crosses The Rockies. With a slightly slower front have bumped up 
temperatures a hair on Wednesday and with the front in northwestern MO by 
Thursday morning...will continue to advertise a gradient from northwest-southeast over 
the County Warning Area. 


By Thursday night and Friday...model guidance remains uncertain with how 
this shortwave is going to pass through the region. A general 
consensus does exist that a piece of energy will break off the 
shortwave and dive south-southwest into the Western Plains/southern rockies. 
The remnants of the upper trough will speed through the northern 
plains and likely push the front through and south of the County Warning Area. Will 
continue to advertise a mostly dry solution for Friday with 
temperatures cooler than guidance values due to influx of cool NE 
surface flow. 


However...the big differences arrive by Friday night and into the 
weekend...with much of the forecast hinging on where Ike makes 
landfall. GFS/European model (ecmwf) both bring Ike northward into the western 
gom...which...combining the affects of the remnant upper trough now 
lifting to the NE...could lead to a very wet weekend. In 
addition...should the western trough eject eastward faster than 
expected...higher probability of precipitation may be needed on Friday. For now will try to 
play things conservatively given an incredibly amount of 
spread/uncertainty. Depending on cloud cover and precipitation 
chances...temperatures will likely continue to remain near or below 
normal through the weekend. 


Dux 


&& 


Aviation... 


For the 06z tafs...rather active the next 24 hours with much of the active 
weather after 12z Monday am. Warm front in northern okla will move north...to about 
50-75 miles south of mkc Monday morning. Strong lift north of the 
boundary will initiate showers and thunderstorms acr the terminals 
after 12z. Will not mention any thunderstorms through 14z as chances look 
too low at this time. Until then...VFR ceilings are expected with any 
rainfall. The front will begin to surge back south late Monday 
morning with strong lift north of the front producing widespread rain in 
all terminal locations. Greatest risk for thunderstorms at the 
terminals...especially kstj...will be between 14z-18z with more of a 
stratiform rain after 18z. Will confine of thunderstorms to the range 
stated above. Although confidence for thunderstorms is high...timing 
will likely have to be fine tuned later. 


Extensive precipitation along with brisk and cool northeast winds 
will gradually lead to IFR ceilings and MVFR to IFR visibilities by late 
morning. Ceilings to rapidly improve after 00z Tuesday as much drier air 
advects south into the terminals. 


Db 


&& 


Eax watches/warnings/advisories... 
MO...none. 
Kansas...none. 
$$