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Next 12 Hours

Forecast data from the National Digital Forecast Database.

5 Day Forecast

• Saturday
• 
• High: 77 °
• Low: 64 °
• T-Storms

• Sunday
• 
• High: 82 °
• Low: 68 °
• Thunderstorm

• Monday
• 
• High: 88 °
• Low: 68 °
• Mostly Cloudy

• Tuesday
• 
• High: 84 °
• Low: 66 °
• Chance of T-Storms

• Wednesday
• 
• High: 82 °
• Low: 63 °
• Chance of T-Storms

area forecast discussion 
National Weather Service Louisville Kentucky 
1248 am EDT Sat may 18 2013 


..updated aviation discussion... 


Forecast update... 
issued at 905 PM EDT Fri may 17 2013 


Tweaked grids toward current obs. Still have a fairly juicy airmass 
in place with precipitable waters ranging from 1.4-1.6 inches, as 
per latest Storm Prediction Center mesonanalysis. It will not take much for some light 
rain/drizzle to come out of this airmass. Patchy fog will be an 
issue as well, though no one location received lots of rain, as was 
the case last night by this time. A look at the water vapor imagery 
indicates some drier air working its way into the region by 
daybreak. Have trimmed pops by daybreak over the west some in 
response to this drier air. Updated products will be out shortly. 


Issued at 535 PM EDT Fri may 17 2013 


Pulled thunderstorm wording from the activity tonight. Not seeing 
any lightning across our region this hour, and persistent cloud 
cover has kept US from being able to generate anything more than 
light rain showers. Areas to our north were able to warm up today, 
and thus a nice band of storms developed across central in/southwest 
Ohio. Cannot rule out additional scattered activity through the night, 
with the upper low moving right across US. Kept in patchy fog for 
the night, given that more areas received rainfall today than 
yesterday, albeit lighter totals. 


&& 


Short term (now - Saturday night)... 
issued at 321 PM EDT Fri may 17 2013 


Combination of satellite imagery and observations reveal an area of 
surface low pressure over eastern Arkansas/western Tennessee with the upper low 
spinning slowly into far western Kentucky. Out ahead of this 
system, widespread cloud cover was noted over the region with a 
large area of light to moderate rain across the southern half of 
Kentucky. Given the widespread cloud cover and precipitation, lapse 
rates are rather poor resulting in little, if any, instability. 
Therefore, not expecting much in the way of thunderstorm development 
across the region this afternoon...though can't rule out a rumble of 
thunder or two. We currently think the bulk of the thunderstorm 
development will be just to our north along a line from near cincy 
to indy and points northward. Temperatures were being modulated by 
the cloud cover and precipitation. Readings ranged from the upper 
60s to around 70 in the south with Lower-Middle 70s in the north. 


For the remainder of the afternoon, expect widespread cloudiness to 
continue. Band of widespread showers across southern Kentucky will 
continue to slowly advect northward. Temperatures will not change 
all that much over the next few hours with Lower-Middle 70s in 
southern Indiana and northern Kentucky with upper 60s to around 70 
in the south. 


For tonight, the multi-model short term consensus is in pretty good 
agreement with the upper low moving slowly across the middle Ohio 
Valley. Associated surface low pressure will likely move across 
southern Tennessee overnight with the bulk of convection occurring just 
ahead of this low. Shower activity across Kentucky and southern 
Indiana will diminish after sunset due to the loss of daytime 
heating. Isolated showers will probably continue overnight, but 
widely isolated at best. With plenty of low-level moisture around 
and winds becoming light as the upper low passes overhead, expect 
another round of patchy dense fog to develop overnight. The fog 
will be most dense in areas that received rainfall this afternoon. 
In tonight's case, the most widespread fog would probably be across 
southern Kentucky. Lows tonight will remain mild with readings in 
the 60-65 degree range. 


On Saturday, the upper low will continue to slowly pull on to the 
east. Combination of differential heating and a moist airmass will 
likely result in scattered convection redeveloping during the late 
morning and into the afternoon. At this juncture, it is difficult 
to delineate an area at more risk for convective development. It 
appears that convective coverage may be more favored over the east 
which would be in closer proximity to the upper low feature. Severe 
weather does not look likely at this point given the expected 
widespread cloud cover and generally poor low-mid level lapse 
rates. Any storm that does form will be capable of producing very 
heavy rains...gusty winds and possibly some small hail. High 
temperatures will warm into the mid-upper 70s. 


By Saturday night, the upper level low should continue to move on 
off to the east. We should see convection wane again with the loss 
of heating. Thus, will keep higher pops in the forecast for the 
evening and then let things diminish overnight. Patchy fog will be 
a possibility again with lows in the 60-65 degree range. 


Long term (sunday - friday)... 
issued at 300 PM EDT Fri may 17 2013 


The upper low that moves over our forecast area Saturday should move 
to the central Appalachians Sunday, with an upper level ridge axis 
building in across western Kentucky. The upper low will still have 
influence over eastern Kentucky, which includes portions of our 
eastern County Warning Area. Expect diurnally driven convection with afternoon 
heating. High temperatures Sunday should range from the mid and 
upper 70s in the eastern County Warning Area to low and mid 80s in the west. 


The upper ridge will strengthen over the Ohio Valley at the start of 
the new work week. This will aid in capping the environment, which 
will produce the best chance at mostly dry conditions Monday and 
most of Tuesday. Tuesday will bring a return of scattered shower and 
storm chances, but looks to be later in the day and mainly across 
our northern forecast area, as a central Continental U.S. Trough approaches. 
High temperatures Monday and Tuesday will be in the mid 80s, with 
overnight lows ranging from the mid to upper 60s. 


As the central Continental U.S. Trough slowly progresses eastward, a more 
active weather period will take place midweek. A surface low will 
track through the Great Lakes, and the trailing cold front will push 
into our County Warning Area. Numerous showers and storms will be possible ahead of 
the front from late Tuesday night through Wednesday night. With 
increasing speed shear expected with the stronger trough aloft, some 
stronger storms are possible. High temperatures Wednesday and 
Thursday will be a few degrees cooler, generally upper 70s to lower 
80s with the additional cloud cover and rain. 


Models are still having a difficult time deciding when that front 
will push through the forecast area, but it appears to pass some 
time during the day Thursday. This will keep scattered showers and 
storms in the forecast for a little longer, but dry weather should 
return Friday as the upper trough axis pushes east of the forecast 
area. Temperatures should top out in the middle 70s Friday 
afternoon. 


&& 


Aviation (06z taf issuance)... 
issued at 1248 am EDT Sat may 18 2013 


Upper low moving across the area continues to bring extensive cloud 
cover and scattered light rains to our region. A round of showers is 
currently moving through bwg, however expect Lex to be the only 
other concern for precipitation as we move toward dawn. Coverage of 
showers still remains sparse enough to only carry vcsh. The 
threat for thunder still looks isolated enough to keep out of the 
tafs this go around. Latest high-res models show a push of extra 
low-level moisture moving into kbwg early this morning, and possibly 
sdf around daybreak, so have kept in previous forecaster's thinking 
of at least IFR cigs overnight at bwg. Do have ceilings just above 
fuel alternate through the late morning as sdf. It will take some 
time to lift those bases in the morning, and expect additional 
showers to develop at the same time. Those chances should fade with 
loss of heating this afternoon/evening. 


&& 


Lmk watches/warnings/advisories... 
in...none. 
Kentucky...none. 
$$ 




Update...........rjs 
short term.......mj 
long term........mjp 
aviation.........Bjs