Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 170503
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
103 AM EDT Fri Mar 17 2017

...Updated Aviation Discussion...

.Short Term (Now through Thursday)...
Issued at 255 PM EDT Thu Mar 16 2017

Low-level air mass remains cool and quite dry as high pressure has
been slow to retreat into the Appalachians, and return flow has yet
to set up. Warm front taking shape over the Plains will bring
increasing clouds and increasing moisture into the Ohio Valley
tonight, but not before a quick drop in temps after sunset. Expect
early mins, just slightly below freezing in the Bluegrass region,
followed by steady or even slowly rising temps toward daybreak.

Freeze Warning remains in effect tonight across the Bluegrass and
will be left alone, even though there is little opportunity
remaining for agricultural impact given the very cold temperatures
the last two nights. Precip chances ramp up well after midnight, and
temps could still be cold enough at onset to support a brief wintry
mix. Best opportunity for mixed precip will be limited to areas
north of I-64 and east of I-75, and even then it will be such a
brief window of opportunity that impacts will be minimal.

Likely to categorical POPs for most of the area during the day on
Friday as the cold front moves through. Steepening mid-level lapse
rates will create enough elevated instability to support slight
chances for thunder in the afternoon/evening, but low levels will
remain quite stable. High POPs will continue into Fri night
especially across south-central Kentucky, but overall this is a
quick-hitting system with average QPF around a quarter inch.

.Long Term (Thursday night through Tuesday)...
Issued at 255 PM EDT Thu Mar 16 2017

Closed upper low will make its way from the Great Lakes to the mid-
Atlantic coast Saturday and Saturday night, but the overall trof is
progressive enough that we`ll come under upper ridging even with a
1028 mb sfc high trekking across the Mississippi and Ohio Valley.
Therefore expect dry and seasonable weather across the Ohio Valley
for the weekend, although Sunday morning will be a chilly start.

Pattern will go zonal for the first part of the work week, with a
cold front bringing a good chance for rain and isolated thunder
Monday into Monday night. We`ll be quite mild on Monday with
widespread 60s and even lower 70s in south-central Kentucky, and the
broad eastern CONUS trof that develops later doesn`t pull much cold
air into the Ohio Valley, thus keeping temps near climo behind the
front.

Late in the week the pattern starts to amplify as a southern stream
system starts to crank up over the OK/TX Panhandle. Will include
solid precip chances on Thursday with the warm front lifting
through, but the more widespread precip associated with the strong
cold front is beyond the scope of this forecast by at least a day.

&&

.Aviation (06Z TAF Update)...
Issued at 1255 AM EDT Fri Mar 17 2017

Well...for St Patrick`s Day aviation, lower clouds moving in with
rainy day ahead at all the sites. VFR conditions through the
overnight period, and expect copious clouds to be on the increase
ahead of an approaching weather system.

A slow progression from VFR to MVFR ceilings is expected, at SDF and
BWG by mid morning and by early afternoon at LEX. IFR ceilings with
the possibility of sct tstms will be possible late this afternoon
and evening at BWG as cold front moves into some instability in S
KY.

Good consensus for rain showers to develop with isentropic lift late
morning with MVFR cigs and even IFR ceilings by afternoon. Looking
ahead, better chances of IFR ceilings after 00z then some gradual
improvement likely toward Saturday morning.

FROPA between 03-6z with solid CAA Saturday morning and winds gusty
Sat 10-20 from wnw.

&&

.LMK WATCHES/WARNINGS/ADVISORIES...
KY...Freeze Warning until 9 AM EDT /8 AM CDT/ this morning for KYZ036-
     037-040>043-047>049-055>057-066-067-078-082.

IN...NONE.
&&

$$

Short Term........RAS
Long Term.........RAS
Aviation..........JDG



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