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000
FXUS63 KLMK 120153
AFDLMK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
953 PM EDT Tue Mar 11 2014

...Forecast Update...
Issued at 952 PM EDT Tue Mar 11 2014

Did go ahead and make some minor changes to the precipitation
forecast for the overnight period. Currently, light rain showers
have blossomed mainly across southern IN and north central KY along
and just south of the warm front. Expect these showers to continue
to lift off to the ENE on the nose of the the increasing LLJ and
where the best isentropic ascent is. This will keep the majority of
the activity along and north of I-64 for much of the evening, with a
relative lull across central and south central KY until the pre-dawn
hours when numerous showers and scattered t-storms arrive just ahead
of the cold front. Have reduced pops across south central KY to
isolated until this time. However, measurable pops are still likely
before sunrise.

Did also want to quickly mention that there are numerous reports of
40 mph wind gusts just behind the front upstream. Additionally, a
few of the storms are rotating just north of St. Louis at the triple
point. These storms should remain elevated when they move through our
area, although lower levels will begin to try and destabilize toward
dawn which could allow for a few stronger wind gusts. Will need to
monitor forecast overnight, and be prepared for a few stronger cells
that might warrant Special Weather Statements for stronger wind
gusts and small hail. Stay tuned.

Issued at 838 PM EDT Tue Mar 11 2014

Made a few tweaks to the ongoing forecast to account for
temperatures running a bit milder than expected at this time, and
very weak showers that have popped up. Continue to think lows will
stay quite mild overnight under WAA, cloud cover, and precip. No
real changes to the temp forecast. The showers are associated with
and uptick in the LLJ over the past couple of hours, and the
associated isentropic lift over top of a warm front now positioned
across south central IL/IN/OH. These showers are very small in
diameter and will likely only produce a brief period of spinkles or
very light rain as they pass. Nevertheless, have started small
chances for measurable rain a couple of hours earlier to account for
them. Still expect focus for best coverage and intensity of showers
(and a few rumbles of thunder) to set up along and north of the Ohio
River as we move toward Midnight and beyond. Then, a broken line of
semi-organized storms are expected to accompany the front more
toward dawn. Small hail and gusty winds to 40 mph may accompany the
later showers/storms.

.SHORT TERM (Now through Wednesday Night)...
Issued at 258 PM EDT Tue Mar 11 2014

Deepening low pressure advancing from the Ozarks to the middle Ohio
Valley tonight will bring very warm air and increased moisture
northward on brisk SSW winds.  As the system approaches showers will
break out and will become widespread, especially after midnight and
with the greatest coverage across southern Indiana and northern
Kentucky.  Scattered thunderstorms can also be expected with some
elevated instability found on sounding progs.  Wet bulb zero heights
indicate that a few of the storms could produce small hail,
especially north and east of Louisville towards morning.
Temperatures will not fall much tonight given the strong WAA in the
warm sector ahead of the low.

On Wednesday the low will exit to the ENE, reaching West Virginia by
midday.  There could be some lingering thunderstorms for a few
hours early in the morning in the Blue Grass ahead of the surface
low, with small hail in the strongest cells again possible. Cold air
will then pour in behind the low on strong and gusty northwest
winds.  The warmest readings of the day will occur early in the
morning, with the mercury dropping into the 30s in Kentucky and the
upper 20s in southern Indiana by late afternoon...a drop of 20 to 25
degrees over the course of the day.  Those northwest winds will be
in the 20 to 30 mph range with gusts to at least 40mph...resulting
in a Wind Advisory for the entire area for Wednesday.  The very
strongest winds look to be over the Blue Grass (Lexington) area.
Snowflakes will gradually mix in with the rain from northwest to
southeast in the afternoon...ending as scattered snow showers east
of Interstate 65 in the evening. Any accumulations would be very
light.

The winds will die down Wednesday night as Canadian high pressure
invades from the northwest.  Low temperatures will be in the middle
and upper teens across much of the area...lower 20s around Bowling
Green.

.LONG TERM (Thursday through Tuesday)...
Issued at 245 PM EDT Tue Mar 11 2014

The synoptic pattern at the start of the long term period will
feature an amplified trough across the eastern seaboard, with a
ridge across the central CONUS, and another trough over the western
United States.  The subtropical jet will become more active by this
weekend into early next week, allowing for more of a split-flow
regime to develop.  This expected pattern will be quite progressive,
bringing daily temperature swings and perhaps a few chances for
precipitation this weekend.

Conditions will start out dry on Thursday, as surface high pressure
slides through the Ohio Valley.  By late Thursday afternoon, this
area of high pressure will push just far enough east that SW surface
flow will develop along the backside across the western CWA.
Therefore, expect a decent gradient in high temperatures on
Thursday, with upper 40s across southern KY and mid 30s across the
Northern Bluegrass.  Lows Thursday night will remain warmer than
Wednesday night, due to southwesterly surface flow continuing.
Overnight lows will bottom out in the upper 20s and lower 30s.

Southwesterly winds will really ramp up during the day on Friday,
setting the stage for a quick warmup.  As we have seen the past
couple of days, the mid-March sun angle is really allowing things to
warm up quite nicely in the afternoons.  With southwesterly flow
aiding in deep mixing, partly cloudy skies, and dewpoints only in
the low to mid 30s, think Friday will end up being quite warm.
Therefore, have bumped up highs a few degrees from the previous
forecast, which puts them in the upper 50s to lower 60s.

Confidence in the forecast begins to decrease by the weekend, as
guidance quickly diverges.  As the subtropical jet becomes more
active, guidance is struggling with just how much moisture will be
able to return north ahead of northern stream impulses.  Overall
pattern recognition tends to favor the southern CWA in this type of
regime due to their proximity to the more moisture-laden systems of
the southern stream, thus will focus the best precipitation chances
there Friday night through Sunday.  Regardless, what does fall
appears as if it will be generally be some light rain, with no
high-impact systems expected through the long term period.
Temperatures this weekend will be in the upper 50s on Saturday,
falling into the upper 40s/lower 50s on Sunday.  Highs will be in
the upper 40s and 50s for early next week.

&&

.AVIATION (00Z TAF Update)...
Updated at 715 PM EDT Tue Mar 11 2014

Weather conditions will gradually decline later this evening, with a
big change coming Wednesday morning and through the day. Currently,
VFR conditions are in place and will remain until the pre-dawn
hours. By shortly after Midnight, a surface low currently over the
KS/OK/MO border will move into the Ohio River Valley. This
strengthening feature will then pass just north of SDF/LEX by 7 AM
EDT. Ahead of the low, expect scattered showers (and perhaps a
rumble or two of thunder) as early as just before Midnight at SDF
where VCTS is mentioned. Will keep VCSH at BWG/LEX where lesser
thunder chance is antcipated.

As we move toward dawn a strong cold front will approach the area
with ceilings dropping into the MVFR range. Additionally, winds will
gust up around 25 mph out of the southwest and a broken line of
showers and storms will likely pass from west to east just ahead of
the front. Some stronger wind gusts and better coverage of t-storms
will be possible with this semi-organized line. Some small hail will
also be possible.

Cold front quickly passes around or just after dawn with a
vengeance. Winds will be strong out of the WNW between 20-25 mph
with gusts up around 40 mph at times. Also, scattered showers behind
the front are expected to change over to snow showers by early
afternoon, before ending from west to east late Wed. afternoon early
Wed. evening. VFR conditions should return at this point with
gradually slackening winds.

&&

.LMK WATCHES/WARNINGS/ADVISORIES...
KY...WIND ADVISORY from 8 AM EDT /7 AM CDT/ to 8 PM EDT /7 PM CDT/
     Wednesday FOR KYZ023>043-045>049-053>057-061>067-070>078-
     081-082.

IN...WIND ADVISORY from 8 AM EDT /7 AM CDT/ to 8 PM EDT /7 PM CDT/
     Wednesday FOR INZ076>079-083-084-089>092.

&&

$$

Updates........BJS
Short Term.....13
Long Term......KJD
Aviation.......BJS