Weather

997 
fxus63 kpah 081737 aaa 
afdpah 


Area forecast discussion...updated 
National Weather Service Paducah Kentucky 
1135 am CST Thursday Jan 8 2009 


Update... 


Updated for 18z aviation package. 


&& 


Discussion... /issued 1029 am CST Thursday Jan 8 2009/ 
minor adjustments to cloud cover/temperatures/dewpoints/wind 
gusts/sky cover in tabular/text/grids to account for differential 
insolation and mixing in vicinity of minor vorticity lobe rotating 
around broadening upper trough over the Great Lakes. A mention of 
light snow flurries as the predominant weather feature for midday 
over southwestern Indiana. Due to the localized nature of more prominent 
snow shower activity /reducing visibilities below 2 statute 
miles/...I decided to omit this in the grids and handle through 
any short term forecast text product as necessary. 


&& 


Previous discussion... /issued 345 am CST Thursday Jan 8 2009/ 


Discussion... 
weather pattern will remain fairly active into the weekend with a 
couple of frontal passages in the offing. The primary forecast 
concern is the chance of precipitation Friday night into Saturday. 


The first of the two aforementioned cold fronts was in the process 
of clearing the southeastern section of the forecast area early this 
morning. Temperatures have remained warmer than forecast along and 
ahead of this boundary overnight...until the cold dry air finally 
has a chance to spill in behind it. Unfortunately...most of the 
forecast guidance did not handle this very well...except for the 
ruc13. Therefore...we have modeled the morning forecast from the 
ruc13...then blended in the nam12 for the latter half of the day. 
GFS based mav guidance appears too warm given conditions upstream. 
Should see plenty of sunshine today...although would not rule out 
the development of some scattered cold air stratocumulus around 
midday...especially in the vicinity of the Wabash River Valley. 


High pressure will slide overhead tonight. Mostly clear skies and 
near calm winds this evening should allow temperatures to plummet 
into the 20s early on. As the high slides east overnight...surface 
winds should turn out of the south...albeit relatively light. In 
addition...an increase in middle and high clouds is possible. These two 
factors should keep temperatures from falling much more after 
midnight...and they may even come up a degree or two by morning. All 
in all...cooler NAM met guidance is preferred tonight. 


Friday should start off with plenty of sunshine. But as the day 
wears on...the warm advection pattern will bring more clouds this 
way by afternoon. We maintained a dry forecast for now...but some of 
the model data has been hinting at perhaps some drizzle over mainly 
southeast Missouri by late afternoon. NAM/GFS/ECMWF all bring an 
area of low pressure into the four-state region Friday night...so we 
increased rain chances to likely and categorical as a result. The 
system may not be completely east of the area by daybreak 
Saturday...so we introduced small chance probability of precipitation to central and eastern 
areas Saturday morning. Temperature profiles are cold enough for a 
brief mix with snow early Saturday...so we added a mention of rain 
or snow. Followed a non-diurnal temperature trend Friday night and 
Saturday given the passage of the low and advection patterns either 
side of it. 


The rest of the forecast remains in tact...with the next frontal 
passage slated for early next week. This front will likely introduce 
some of the coldest air of the season for the early to middle of 
next week. 


&& 


Aviation... 
initial issue will be some MVFR ceilings at kevv and kowb this 
afternoon...as an area of stratocu associated with lingering energy 
in wake of upper level trough tracks southeastward. There are a few 
snow showers 5-10 miles NE of kevv. After these clouds pass...VFR 
conditions prevail at all sites until next system approaches Friday 
evening/overnight. Winds become calm tonight as high pressure 
crosses the region...picking up from the south Friday. 


&& 


Pah watches/warnings/advisories... 
Kentucky...none. 
MO...none. 
Illinois...none. 
In...none. 
&& 


$$ 


Smith