757 
fxus63 kind 201702 
afdind 


Area forecast discussion 
National Weather Service Indianapolis in 
1202 PM EST Thursday Nov 20 2008 


Aviation...discussion for 18z tafs. 
Will see a weak short wave move through Indiana around 0z. Forecast 
soundings/time heights showing possibility of MVFR ceilings at kind between 
6 and 12z. Guidance from FWC has some MVFR at khuf and kind after 0z 
for a few hours. All other guidance is VFR through the period. Looking at 
upstream observation indicates ceilings around 3500 feet or above. GFS shows 
sinking motion over the area after 0z which would argue against lower 
ceilings. Will stick with VFR ceilings at this time and monitor for next 
issuance. As high pressure starts to build in should see ceilings scatter out at 
least by the end of the period. Lake effect impacts should stay north and east of 
the sites. 


&& 


Previous discussion... 
main forecast problem will be the temperatures. Cold front in Ohio 
and northern Kentucky will continue to move east. This will put Indiana under a 
continuing flow of cold and unstable air. Satellite pics have SC 
moving steadly south. Should be over entire County Warning Area by shortly after sunrise. 
Strong cold air advection will continue through the day. NGM and GFS have the 
greatest with 850 mb temperatures dropping to -13. Have been lowering 
daytime highs last two runs. Will go closer to the colder NGM which 
seems to have worked fairly good last 2 days. With the cold air advection the highs 
may be during the morning with steady or falling temperatures in the 
afternoon. Good set up for lake effect snow. Will give the extreme 
NE counties a chance of snow with around 1/2 inch measurable. Over the 
rest of central and eastern sections will go with flurries. For 
tonight guidance usually wants to move clouds out too fast. Will 
slow breakup some. With strong cold air advection will go closer to the colder 
NGM/Eta model temperatures. If clouds do clear sooner cold be a little colder but 
winds 10-15 miles per hour will give enough mixing to help stop drastic drop. 
On Friday high pressure will move into area. Very little let up in 
the cold air advection. The colder NGM/Eta model temperatures look better. Will slowly end the 
lake snow NE. With high over Indiana Friday night there will be less 
cloud cover and winds will become light. This will allow for good 
radiational cooling. For some reason GFS wants to keep huf 7-9 
degrees warmer then everyone else. Will go near more consistant Eta model. 


In the later periods...strong low level cold air advection on Thursday will help to create very steep 
low level lapse rates. This in combo with upper WV should generate some 
flurry activity on Thursday and Thursday night. Low level winds become favorable 
for the potential for more organized snow shower activity off of Lake Michigan 
to move into the northestern zones by Thursday aft/night. Will hit probability of precipitation harder 
in those areas. Depending on how things eventually set up...some 
locations in the NE County Warning Area may see an inch or two accumulation. Winds 
expeceted to back by Friday...so any lingering snow shower activity in the NE 
should end by that time. 


&& 


Ind watches/warnings/advisories...none. 


&& 


$$ 


Aviation...cp 
public...Haines