Your Weather

To update your location please enter your ZIP code, city, state, airport code or country in the field below. Weather by E-mail: Forecast storm alerts. Weather E-Mail Alert Sign Up »

Next 12 Hours

Forecast data from the National Digital Forecast Database.

5 Day Forecast

• Tuesday
• 
• High: 90 °
• Low: 68 °
• T-Storms

• Wednesday
• 
• High: 79 °
• Low: 63 °
• T-Storms

• Thursday
• 
• High: 75 °
• Low: 45 °
• Chance of T-Storms

• Friday
• 
• High: 72 °
• Low: 46 °
• Partly Cloudy

• Saturday
• 
• High: 79 °
• Low: 54 °
• Clear

area forecast discussion 
National Weather Service Louisville Kentucky 
645 am EDT Tuesday may 21 2013 


..updated aviation discussion... 






Short term (today - wednesday)... 
issued at 251 am EDT Tue may 21 2013 


A difficult and complicated forecast as a storm system approaches 
from the plains... 


Early this morning a long line of showers and thunderstorms 
stretched from Michigan to Oklahoma. This line will weaken 
considerably as it pushes to the southeast away from the jet energy 
that was supporting it earlier. Will have likely pops in southwest 
Indiana before dawn, and just chance pops across the area after dawn 
as the line continues to fall apart. 


We should see a break in the action for several hours before 
redevelopment takes place this afternoon. Widespread clouds and 
scattered morning showers will prevent US from destabilizing fully, 
but some strong storms could still fire in the warm and juicy 
atmosphere. It will be interesting to see where the outflow boundary 
from this morning's convection ends up, as that could serve as a 
focus for renewed convection. As for any severe weather, it looks 
like marginally severe hail is the primary threat, with marginally 
severe wind gusts a secondary threat. Tornadoes look unlikely, 
though local boundary intersections will need to be watched for the 
possibility of a brief spin-up. 


We may see another break this evening as afternoon convection 
wanes. Renewed shower and thunderstorm activity is then expected 
during the late night hours as a low level jet revs up from Memphis 
to Fort Wayne. A strong low level inversion is forecast to set up, 
so small hail would be the main threat with any stronger storms. 


On Wednesday the cold front that has been producing the rough 
weather across the nation's midsection recently will draw nearer 
still to the lmk cwa, reaching the lower Wabash and middle 
Mississippi valleys by evening. Additional shower and thunderstorm 
development can be expected on Wednesday, particularly in the 
afternoon. Once again, widespread morning clouds and scattered 
showers will prevent US from destabilizing much. A few strong 
storms will still be possible, though, with marginally severe hail 
as the primary threat...marginally severe wind gusts secondary...and 
tornadoes unlikely other than where local boundaries meet. 


Temperatures are also very challenging given the clouds and rain. 
For today will shoot for highs mostly in the middle 80s, though that 
may be generous if we don't get some sun this afternoon. Muggy lows 
tonight will be in the middle and upper 60s once again. Model data 
vary widely on how warm we will get on Wednesday. For now will go 
with highs around 80. 


Long term (wednesday night through monday)... 
issued at 245 am EDT Tue may 21 2013 


Upper air pattern at 500mb late Wednesday is forecast to become 
somewhat amplified with thin ridging across the northern plains 
sandwiched between a deep closed low off the Pacific northwest coast 
and a slow moving trough centered over the western Great Lakes. This 
Great Lakes trough will deepen, with its base swinging across the 
commonwealth by early Friday morning. Showers and thunderstorms 
Wednesday will diminish during the evening hours and overnight as 
veering mid-level winds will bring lower pwats east from Missouri. 
Pwats of 1.6 inches earlier Wednesday will diminish to under one 
inch by dawn Thursday. Still, will maintain at least a chance of 
showers and an isolated thunderstorms overnight through Thursday 
morning. 


By late Thursday, a surface trough will move southeast of the Ohio 
River, switching our winds to the northwest and eventually bringing 
in substantially cooler air. Despite less available moisture, the 
presence of the 500mb trough axis and a diffuse frontal boundary 
will not preclude scattered low topped showers and isolated thunder 
Thursday afternoon. 


High pressure of Canadian origin will build southward along the 
Mississippi Valley Friday, sliding east towards Ohio by Sunday 
morning. Distinctly cooler air with low dewpoints will arrive by 
Friday morning and continue through the entire weekend. Despite 
clearing skies, Friday will stay quite cool and refreshing, with 
highs only rising into the lower 70s at best. We can expect several 
cool nights from Friday to Monday mornings with lows initially 
around 50, rising into the upper 50s by Monday morning. Under mostly 
clear skies, highs Saturday and Sunday will remain in the 70s. 


By late Sunday, a slowly progressive 500mb wave pattern will have 
moved the Great Lakes trough eastwards over New England. Ridging 
will begin to build across the Southern Plains, with northwest flow 
developing across the lower Ohio Valley. Moisture will begin to pool 
late Sunday along and north of a warm front expected to develop 
along a line from Iowa southeast through northern Kentucky. Will 
introduce a chance for isolated to scattered convection late Sunday 
and Monday, especially across our northern counties. Humidities will 
also rise by Monday as southwesterly surface winds develop. 


&& 


Aviation (12z taf issuance)... 
issued at 644 am EDT Tue may 21 2013 


A complex and, as a result, low confidence forecast. A storm system 
approaching from the plains will throw unsettled weather at US 
throughout the taf period. 


A line of storms is advancing into central Kentucky at 1045z. Have 
used radar animations to bring this line into the taf sites over the 
next few hours. The line should be weaker by the time it gets as 
far east as the airports, and should be mostly in the form of 
showers with isolated thunderstorms and rain. Sdf stands the best chance at receiving 
the most adverse weather from this line. 


Once that clears out, we should have several quiet hours from mid 
morning through mid afternoon. The amount of destabilization we'll 
be able to realize this afternoon is in question, given the morning 
clouds and showers. Nevertheless, will forecast scattered 
thunderstorm redevelopment during the heat of the day. Winds may 
get a little gusty this afternoon as well...especially if we can get 
some decent sunshine. 


Another quiet period is expected this evening as the afternoon 
convection wanes. Then, another round of showers and storms should 
break out late tonight as the plains storm system continues its 
approach and a low level jet Cranks up from Memphis to Toledo. 


Needless to say, with all this going on, changes will certainly be 
made to the tafs over the course of the day. 


&& 


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




Short term.......13 
long term........jsd 
aviation.........13