Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 081740
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
1240 PM EST Thu Dec 8 2016

...Updated Aviation Discussion...

.Forecast Update...
Issued at 1135 AM EST Thu Dec 8 2016

Most clouds have cleared out late this morning, so expect mostly
sunny skies for the rest of the afternoon. A secondary stratocu deck
will try to scrape some of our southern IN counties by late
afternoon/early evening so could see a bit more sky cover up there.
Otherwise, temps will struggle today despite the sun as a steady WNW
cold advective component remains. Only looking for low to mid 30s in
most spots.

&&

.Short Term...(This afternoon through Friday evening)
Issued at 245 AM EST Thu Dec 8 2016

...The Cold Air Has Arrived...

Plenty of mid level radar signatures out there this morning
indicating that it`s likely snowing aloft but no flurries reported
at the sfc yet.  Moisture is having a difficult time pushing through
the near sfc dry layer.  Thus, took the flurry mention down to isld.
Any flurry chances should end this morning shortly after sunrise.

For the rest of the day, expect skies to become mostly sunny with
breezy WNW winds.  In the colder airmass, highs will only reach 30-
35 degrees this afternoon.  With the blustery conditions, it will
feel like temps are in the upper teens/20s today.  The only
redeeming part of the day will be the sunshine this afternoon.

For tonight, expect a vort max in the upper trough to sink into
southern IN/northern KY bringing a low stratus deck to parts of the
region. Soundings indicate that the low level moisture plume will be
thick and cold enough for sct flurries late tonight into Fri morning
mainly along I-64 and areas north.  Temps tonight will fall into the
teens and low 20s, remaining warmest in the areas with thick low
clouds for a good portion of the night.

Friday will be another chilly day with morning flurries.  Fri highs
will only reach the 29-33 degree range struggling to warm past the
freezing mark over most of the area.  Skies should become partly
cloudy during the afternoon hours.

.Long Term...(After midnight Friday night through Wednesday)
Issued at 330 AM EST Thu Dec 8 2016

Friday Night - Monday...

Friday night will be another very cold night with low temps well
below normals.  Expect lows to bottom out in the mid to upper teens
with sfc high pressure over the region resulting in good rad cooling.

Attention then turns to a weather system progged to arrive this
weekend.  An upper level shortwave and weak sfc low will move
through the Midwest late this weekend into early next week in a
fairly progressive flow pattern.  The latest 0Z suite of model
guidance has slowed down the arrival of this wave, so pulled POPs
back to start late Sat night/Sun morning with the bulk of the precip
occurring late Sun afternoon through Sun night.  While it is still
possible that precip could start out as mix of rain/snow Sat
night/Sun morning, models have trended a bit warmer and a cold rain
should be the dominant weather type with this system through Sun
night. Rainfall amounts should range from 0.25-0.75 inches Sat night
- Monday.

As for temps, generally warmed things up a bit based on the latest
model data. With the weak sfc low tracking to our NW, we should see
temps warm into the upper 30s to mid 40s Sun for highs.  Then Sun
night we`ll likely see a warm surge on the south side of the sfc low
resulting in a non-diurnal temp curve with temps warming through the
upper 30s/lower 40s during the pre-dawn hours.  Monday temps will
remain steady in the mid upper 30s - mid 40s.

Tuesday - Wednesday...

Forecast confidence drops off quite a bit for mid week as a large
spread in long range model guidance exists.  Another surge of cold
air is expected with the GFS indicating a much colder airmass than
ECMWF.  Also the GFS quickly wraps up another low pressure system
ahead of the Arctic air resulting in more precipitation in the form
of rain and snow for Tues/Tues night while the ECMWF remains fairly
dry.  Will lean toward a model consensus of 20% POPs for mid week
for now.

&&

.Aviation...(18Z TAF Issuance)
Issued at 1230 PM EST Thu Dec 8 2016

Cold W to NW low-level flow has overspread the area this morning.
There have been occasional low clouds affecting SDF and LEX, but not
much. High clouds are streaking ENE across central KY as well. For
this afternoon, VFR conditions should prevail with W or WNW surface
winds of 10-15 kts.

For tonight, an area of low clouds (generally MVFR) currently over
central IL and central IN is forecast to slide southeast and should
clip SDF and LEX after roughly 02 or 03z, and may continue into the
morning hours Friday. There is some question whether ceilings will
affect SDF or stay just north and east, but TAF does include broken
ceiling around 3 kft. Main area of clouds will stay north and east
of BWG, but could see few/scattered clouds at times at BWG late
tonight. Surface winds will be W to NW at or below 10 kts.

&&

.LMK Watches/Warnings/Advisories...
IN...None.
KY...None.
&&

$$

Update...BJS
Short Term...AMS
Long Term...AMS
Aviation...TWF


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