479 
fxus63 kiwx 160041 aaa 
afdiwx 


Area forecast discussion...updated 
National Weather Service northern Indiana 
841 PM EDT Wednesday Oct 15 2008 


Update... 
quick update to freshen wording/remove thunderstorms and rain mention remainder of 
evening as cold front has pushed east of County Warning Area. Strong middle level 
deformation zone yet to slide eastward through County Warning Area coincident with 
strong i305k isent upglide. Time end of rafl late tonight a bit 
quicker based on latest RUC and upstream Sat trends. 


&& 


Previous discussion... /issued 751 PM EDT Wednesday Oct 15 2008/ 


Aviation... 
Post frontal precipitation area coincident with 7h-6h strong 
deformation/i305k isent upglide continues to expand this evening. Rafl 
continuing into mixed/moist boundary layer to likely provide a period of IFR conds 
remainder of evening at ksbn and within a couple of hours conds to 
deteriorate to IFR/fuel alt at kfwa. Despite quite hi xover temperatures do 
not expect visibilities to drop much below 3sm in light-moderate rain as well mixed 
bl to preclude denser fog formation. Strong airmass exchange to continue 
to advect toward/into northern in late tonight along with arrival of upper 
30s surface dps in northestern Iowa/southwestern WI. Precipitable water dropping below 0.50 inches by 12 
UTC at ksbn and few hours later at kfwa to provide return to VFR conds 
Thursday am. 


Short term...(tonight through Thursday night)... 
kiwx radar showing scattered showers developing along southern County Warning Area in 
vicinity of warm front while leading edge of precipitation shield covering 
much of northern Illinois now entering Northwest Indiana. Latest surface 
analysis has frontal wave over central Illinois along approaching 
cold front extending across eastern Wisconsin...through 
Illinois...and back into central Missouri. Surface wave will track 
through northern Indiana this evening with trailing cold front to 
push through most of the County Warning Area by midnight. Very little instability to 
work with this afternoon...but convective nature of precipitation 
developing along warm front at this time warrants keeping a mention of 
thunder in east/southeast portion of County Warning Area this evening. Expect quantitative precipitation forecast of half inch 
across most of the County Warning Area...but with precipitation water at or above 1.5in could see 
locally higher amounts in heavier downpours. Regional radar 
indicates substantial area of Post-frontal precipitation extending back 
into eastern Iowa so will keep likely probability of precipitation going in eastern counties 
through 09z Thursday before ending precipitation by 12z. Good northerly fetch 
Down Lake Michigan expected to keep extreme western County Warning Area in lake 
effect clouds much of the day Thursday while scattered-broken diurnal cumulus for 
the rest of the area. Significantly cooler airmass behind front will 
have temperatures Thursday a few degrees below normal...near 60f most areas 
for highs with lows dropping into upper 30s. 


Long term... 
first concern of extended period is digging trough skirting the County Warning Area Friday 
night. Pvs shift pulled probability of precipitation in this window and other than increase 
in ll moisture remainder of thinking remains the same with ridging 
in control at the surface and no indication of uvm in time heights and 
will remain dry. This moves out quickly and sets up Saturday 
morning as the coolest of the period with frost potential especially 
areas NE. 


Progressive pattern continues with ridging quickly returning and 
temperatures warming briefly back above average. At tail end of extended 
ec/GFS develop similar pattern with trough on either coast and ridge 
over central US. However sig diffs in placement and amplitude of these 
features results in decidedly diff temperature outlooks while both solutions 
leave area dry. Will side with a blend of GFS ensemble MOS and 12z 
mex guidance which warmed several degrees due to more eastward 
location of ridging and is sig warmer than 12z European model (ecmwf). 


&& 


Iwx watches/warnings/advisories... 
in...none. 
Michigan...none. 
Ohio...none. 
Lm...Small Craft Advisory from 1 am to 10 PM EDT Thursday for lmz043- 
046. 


&& 


$$ 


Short term...logsdon 
long term...Ludington 
aviation...Murphy 
update...Murphy