Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 171308
AFDLMK

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

...Forecast Update...
Issued at 855 AM EDT Fri Mar 17 2017

Initial bands of precip have pushed across most of central Kentucky,
with another band making its way across the Bluegrass. Radar returns
and a few ground truth reports indicate there has been sleet briefly
mixing in.  However temps are above freezing in all but the deepest
and most sheltered valleys, and pavement temps are above freezing
even on bridges, so little or no impact is expected.

Overall the forecast is on track, and we`ll just hold out for
another hour or so, at which point we should be able to remove any
mixed precip mentions.

Issued at 651 AM EDT Fri Mar 17 2017

Temperatures across the Bluegrass region have warmed to at or above
freezing. Therefore the Freeze Warning has been cancelled.  A band
of mainly showers continues to move eastward across the forecast
area this morning.  A brief wintry mix is still possible with this
precipitation, but the vast majority of it will fall as plain rain.

.Short Term (Now through Saturday)...
Issued at 315 AM EDT Fri Mar 17 2017

Early morning IR imagery shows cloud cover moving eastward through
the region.  Plenty of mid-high level clouds were noted in the east,
but a solid deck of low cloudiness was noted along and west of I-65.
Temperatures across the area from ASOS and the KY Mesonet revealed a
nice gradient with readings in the east down in the teens with
readings out west in the mid-upper 40s.

In the near term, cloudiness will continue to thicken and ceilings
will likely start to lower.  Some light returns are showing up on
regional radars, but antecedent dry airmass will take some time to
saturate downward.  So we still think some light precipitation will
be possible before dawn.  A brief wintry mix will be possible across
our far northeast, but with temperatures warming from west to east
at a steady rate, impacts across SE IN and our northern Bluegrass
areas looks to remain very minimal at this time.  Freeze warning
remains in effect through 13Z.  However, with temperatures
continuing to warm from west to east, there stands a good chance
that we`ll likely be able to let it go a little earlier than its
current expiration.  Current thinking is that we may let it go,
depending on temperatures of course, around 5-6 AM.

For the rest of today, cloudy conditions are expected and
precipitation is expected to become more widespread throughout the
day.  Predominant precipitation will likely be rain showers with
some embedded thunder in the afternoon and evening as some elevated
instability will be found mainly across southern KY and into
northern TN.  Overall kinematic environment remains generally poor
and convection does not look like it will have an easy time
organizing.  High temperatures today will range from the upper 40s
across the northern Bluegrass to the lower-mid 50s in the I-65
corridor and points south and west.

For tonight, surface cold front to the west will push east-southeast
and rain showers will diminish from NW to SE overnight with most
locations going dry by dawn Saturday.  Lows tonight look to range
from the upper 30s across southern Indiana and the northern
Bluegrass to the lower-mid 40s across south-central Kentucky.

For Saturday, we`ll remain in a cool northwesterly flow with a
likely gradient of clouds and temperature.  Skies may remain mostly
cloudy through a good part of the day across SE IN and into the
Bluegrass region, with more breaks in the clouds across west KY and
southern KY.  Highs look to range from the upper 40s to around 50 in
southern Indiana and the northern Bluegrass with readings in the 53-
58 degree range along and south of the Bluegrass and Western
Kentucky Parkways.

.Long Term (Saturday Night through Thursday)...
Issued at 325 AM EDT Fri Mar 17 2017

Saturday Night through Monday Night...

Closed upper level low is expected to be dropping through SW New
England and into the Mid-Atlantic states by Saturday night.  A cool
northwest flow will remain over our region with readings falling
into the lower 30s by Sunday morning.  Upper level ridging will
build into the area on Sunday bringing partly cloudy conditions and
seasonable temperatures.  Highs Sunday look to warm into the lower-
mid 50s across southern IN and northern KY with mid-upper 50s across
the southern half of KY.  Lows Sunday night will not be as cool with
readings dropping into the upper 30s in the east with lower 40s
across the west.

The upper level flow pattern is expected to go more zonal across the
Ohio Valley early next week.  However, the flow will remain
progressive aloft and a frontal boundary will push into the region
on Monday afternoon/evening bringing a surge of milder temperatures
along with a period of showers and thunderstorms.  Current guidance
still suggests that we`ll make a run at the mid-upper 60s for highs
on Monday across southern Indiana and the northern portions of KY.
Stronger signal suggests that lower 70s will be possible down across
the southern half of KY.  Lows Monday night look to cool into the
lower 40s in the north with mid-upper 40s across the south.

Tuesday through Thursday...

Surface cold front will slowly push southward across the Ohio Valley
on Tuesday keeping skies cloudy with plenty of shower activity
around.  The front looks to get enough a northerly push to settle
down to our south on Wednesday and Wednesday night giving us a brief
period of quiet weather.  This will not last all that long as the
frontal boundary will likely lift northward late Wednesday night
into Thursday which will yield another round of precipitation as
transition back to the warm sector ahead of the next, and possibly
more significant system, that will arrive by Friday.

Highs Tuesday and Wednesday look to be seasonal with highs in the
mid 50s and overnight lows in the 30s.  Highs look to rebound a bit
on Thursday once the warm front surges through the region.  Highs
will likely range from the mid-upper 50s across southern Indiana and
northern KY with lower 60s working in across the south and down into
Tennessee.

&&

.Aviation (12Z TAF Update)...
Issued at 535 AM EDT Fri Mar 17 2017

Well...for St Patrick`s Day aviation forecast, lower clouds are here
with 4-6k stratocumulus with a rainy day ahead at all the sites.
Isentropic lift evident on radar with light echo returns in a WAA
pattern with warm front. Temps have warmed all night with winds
increasing and veering to the south. Had llws at sdf and bwg with 35
to 45 kts at 2k, but latest 88d vwp only showing 30 kts off the
deck, so will pass this time around, but maybe choppy on takeoff and
approaches.

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
should be moving in by 21z 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. One concern is some low
clouds and fog in early evening waiting for the front to sweep
frontal zone clouds southward.

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

&&

.LMK WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
IN...NONE.
&&

$$

Update.........RAS
Short Term.....MJ
Long Term......MJ
Aviation.......JDG



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