Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 232000
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
300 PM EST Thu Feb 23 2017

.Short Term (Now through Friday Night)...
Issued at 245 PM EST Thu Feb 23 2017

...Record February Warmth and Severe Storms Possible Friday...

The main focus in the short term is on severe storm chances, timing,
and potential impacts Friday and Friday evening.

A surface analysis this afternoon showed a 990 mb surface low
developing in the lee of the Rockies with its stationary front /
warm front across southern Kansas, central Missouri into central
Illinois and Indiana. Across the lower Ohio Valley, visible
satellite showed scattered to broken strato-cu. South winds
continued and mid-afternoon readings were in the upper 60s to low
70s.

For tonight, the area will be deep within the warm sector as the
surface low deepens and tracks to Kansas City and west central
Illinois by Friday morning. It will be extremely mild tonight thanks
to breezy south winds keeping the boundary layer well mixed. Plan on
lows to stay in the 60s for most locations and the Louisville urban
center may stay in the mid 60s.

For Friday, a strong cold front will approach the area late in the
afternoon. Ahead of it, record breaking warm temperatures are
expected and the all-time February maximum temperature at Louisville
(78 degrees) is forecast to fall with highs in the upper 70s to
around 80. It will also be very breezy with south winds 15 to 25 mph
and gusts 30 to 35 mph from late morning through the afternoon.
These gradient wind gusts will fall short of a wind advisory but
nonetheless it`ll be very breezy.

The environment Friday afternoon and evening is forecast to have
SBCAPE of around 1000 J/kg within effective shear of 45 to 60 kts.
As a mid-level capping inversion breaks around mid afternoon,
discrete storms are forecast to develop across southern and central
Indiana and race east. Storms are likely to initiate along a pre-
frontal trough first and then again along the frontal boundary,
likely congealing into broken line segments as it moves into
southeast Indiana, north central Kentucky and the Bluegrass regions.

As for timing purposes, think generally along/west of I-65 the
greatest severe risk is 4p-8p, between I-65 and I-75 6p-10p and then
along/east of I-75 7p-1a. Given the environment and hodographs,
damaging winds will be the greatest concern but there is a large
hail threat and non-zero tornado threat initially with any discrete
storms.

The front sweeps across the entire Friday late evening and Friday
night bringing an abrupt end to our record warm February. Look for
west/northwest winds to usher in much colder air such that by
Saturday morning the area will wake up to temperatures in the mid
30s to around 40 degrees.

.Long Term (Saturday through Thursday)...
Issued at 250 PM EST Thu Feb 23 2017

Expect a blustery and dry day Saturday as high pressure drops from
the northern Plains to the mid-Mississippi River Valley. The big
story will be the 24-hour temperature change as highs stay in the
40s for the area, a 30 degree drop from Friday afternoon. On Sunday
as the high moves off the Atlantic coast, southerly return flow will
moderate temperatures back into the 50s.

Going into next week, forecast confidence drops below average. The
upper level pattern is expected to be southwesterly with periodic
impulses coming out of the southern/central Plains but the 23.12z
models struggle with the timing and evolution of potential storm
systems. For now, stayed close to a model consensus blend with
precipitation chances and above normal temperatures.

&&

.Aviation (18Z TAF Update)...
Issued at 1215 PM EST Thu Feb 23 2017

Moist low-level air mass and modest warm advection have helped keep
stratus in place over the terminals this morning. The stratus will
be extensive enough at times for a MVFR ceiling this afternoon, but
will remain above fuel-alternate.

This evening, south winds will diminish and we`ll see mid-level
ceilings as the low clouds scatter out. It`s worth noting that SDF
winds will initially lay down to 6 kt or less, but will increase
again before midnight EST, during the late-evening peak in traffic.

Winds continue to increase through the night and even more so on
Friday, with gusts kicking up to around 25 kt by mid-morning as the
gradient tightens ahead of the approaching front. Stratus ceilings
will also come back in, and it`s a close call between MVFR and VFR,
but still above fuel-alternate regardless. A line of strong T-storms
is likely to develop in Indiana late Friday afternoon, and push into
Kentucky with gusty winds. However, the timing is too close to the
end of the planning period at SDF, and solidly beyond the scope of
this TAF issuance, so will not mention it at this time.

&&

.Climate...
Issued at 240 PM EST Thu Feb 23 2016

Record temperatures for Friday. ** indicates current forecast
calls for that record to be tied or broken.

Louisville:
**Fri. Feb. 24 record warm low: 56 (1930)
**Fri. Feb. 24 record high:     71 (2000)

**All time record February high: 78 (1932, 1887, and 1883)

Lexington:
**Fri. Feb. 24 record warm low: 55 (1930)
**Fri. Feb. 24 record high:     71 (1944)

All time record February high:     80 (1996)
All time record February warm low: 59 (1890)

Bowling Green:
**Fri. Feb. 24 record warm low: 55 (1930)
**Fri. Feb. 24 record high:     74 (1875)

All time record February high:     83 (1918)
All time record February warm low: 64 (2008 and 1895)

Frankfort:
**Fri. Feb. 24 record warm low: 52 (1930)
**Fri. Feb. 24 record high:     78 (1996)

All time record February high:     80 (1932)
All time record February warm low: 61 (1954)

* means most recent occurrence, record occurred in previous years as
  well

&&

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

$$

Short Term........ZT
Long Term.........ZT
Aviation..........RAS
Climate...........RJS/ZT


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