617 
fxus63 klmk 051841 
afdlmk 


Area forecast discussion 
National Weather Service Louisville Kentucky 
240 PM EDT Sat Jul 5 2008 


Short term (tonight and sunday)... 


Residual showers/storms over the east and patchy fog possible 
overnight. 


A surface low pressure center remains over the northestern County Warning Area at the 
moment...along with a weak frontal boundary over central Kentucky. These 
elements combined with heating of the day and an upper-level 
disturbance near the Ohio River are generating isolated 
showers/storms over mainly the eastern County Warning Area. Since there is limited deep 
moisture...there will not be very many cells and most areas will 
remain dry. But locations along and east of I-75 will have the best 
chance at showers/storms through sunset...with brief heavy rain and 
a few lightning strikes. Will hold onto the slt chance probability of precipitation through 
00z. 


Overnight...high pressure over the southern Great Lakes will sag 
southeastward and winds will go calm overnight. Most strato-cumulus 
should dissipate overnight...leaving good radiational cooling 
overnight. Boundary layer moisture should remain high enough that 
patchy fog is expected to develop overnight toward Sunday morning. 
Best chance would be over the east half of the County Warning Area. 


For Sunday...short-term models hint at isolated showers Sunday 
afternoon over eastern Kentucky with the lagging upper trough. But think this 
will be far enough east that we will keep Sunday dry. May beef up 
cloud cover though. Ridging will be nosing in from the west so will 
have the highest temperatures nearing 90 over our far western/southwestern County Warning Area. 


Long term (sunday night through saturday)... 


An early week warm-up followed by a middle-week potential soaking. 


Sunday night-Tuesday night... 


With ridging nosing into the area through Tuesday...we will see a 
warm up with highs back around 90 to the low 90s...and lows in the 
upper 60s to low 70s. A frontal boundary will approach the region 
from the northwest and precipitation chances will increase from slt chance 
over the north on Monday...to high chance probability of precipitation Tuesday night especially 
over the northern/northwestern County Warning Area. Operational GFS does not show much quantitative precipitation forecast until 
Wednesday. However...it is trending faster which would agree with 
the ensembles so have 50 probability of precipitation north to 30 probability of precipitation south by Tuesday 
night. 


Wednesday-Thursday... 


By Wednesday morning...this frontal boundary lays across the northern County Warning Area 
near the Ohio River. As already mentioned the new GFS is much faster 
with pushing this boundary south out of the County Warning Area...so have the 
highest probability of precipitation Wednesday-Wednesday night (up to likely pops)...and 
taper off from north to south during the day on Thursday...with slt 
chance probability of precipitation north and low chance probability of precipitation south. It is too early to tell if 
any storms will be strong...but at this time heavy rainfall looks 
like the main threat during this time frame. Lowered high temperatures on 
Wednesday and a bit on thrs from potential convection/clouds. 


Friday-Saturday... 


Once the front moves through by Thursday evening...dry conditions 
will finish out the work week. Not much if any of a cool down behind 
the frontal boundary...so still have highs in the upper 80s through 
Saturday. 


&& 


Aviation (18z tafs)... 


Ceilings have improved to MVFR across southern Indiana and central 
Kentucky. Low pressure just southeast of sdf...an upper level 
disturbance and surface heating will help generate isolated showers 
and possibly a thunderstorm or two through the afternoon 
hours...especially for Lex and to a lesser degree sdf. Think bwg 
will remain dry. Will carry just vcsh possibly in the sdf taf and 
will at least carry vcsh in the Lex taf...possibly a tempo but 
confidence is low that it will actually rain at the Airport itself. 


The low strato-cumulus field should stick around until sunset tonight 
when conditions go VFR. All surface winds will be out of the northwest 
and will go calm after midnight. Could have some MVFR visibilities 
overnight at the terminals...so will hint at this in the tafs. Surface 
winds will start to veer around to the south-southwest after 12z Sunday. 


&& 


Lmk watches/warnings/advisories... 
Kentucky...none. 
In...none. 
&& 


$$ 


Short term...Alabama 
long term....al 
aviation.....Al