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000 
FXUS63 KLMK 240000
AFDLMK

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

...Updated Aviation Discussion...

.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...(00z TAF Update)
Issued at 645 PM EST Thu Feb 23 2017

Primarily VFR weather is forecast this evening and overnight. 
Evening surface analysis features a surface low over southern 
Kansas, with a warm frontal boundary extending ENE through Missouri, 
central Illinois, and central Indiana. IR satellite imagery and 
webcams feature a fair amount of clearing toward BWG, with more mid-
level clouds closer to the warm front. But BWG may see some brief 
MVFR stratus toward dawn. 

The main aviation impact during the day on Friday will be the winds. 
Winds will be lightest this evening, around 6-7 kts out of the SSE 
through 06z. The surface low is forecast to track to western 
Illinois by 12z Fri, and southerly gradient winds will increase to 
10-12 kts. The strongest winds are expected out of the southwest 
from late morning through the afternoon hours, with gusts to 25-30 
kts. As the cold front marches east late in the day, a couple broken 
lines of thunderstorms will likely push east across all TAF sites. 
The storms may be strong to severe, with heavy rain, lightning, and 
brief gusts over 50 kts.

&&

.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...
IN...None.
KY...None.
&&

$$

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