Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 281748

Area Forecast Discussion
National Weather Service Louisville KY
148 PM EDT Sat Mar 28 2020

.Forecast Update...
Issued at 148 PM EDT Sat Mar 28 2020

The forecast is largely trending as expected thus far. A cap above
800 mb is certainly playing a role suppressing convection in the
warm sector, absent the primary triggers off to our north and west.
We`ve also had a few more breaks of sun that expected, but stratocu
is quick to fill back in. Partly to mostly cloudy skies expected
through late afternoon.

Cannot rule out just a few isolated cells during the late afternoon
and early evening hours. But the main round of convection is still
expected to sweep across southern Indiana and central Kentucky from
8-9 PM EDT through 5-6 AM EDT Sunday.


.Short Term...(Today and tonight)
Issued at 258 AM EDT Sat Mar 28 2020

A warm front has drifted north of the region and will continue to
push northward today, putting us well within the warm sector of a
developing spring storm system. South winds ahead of strengthening
low pressure moving from Kansas to Iowa will gust 20-25 mph for much
of the day. Despite widespread clouds, these winds will allow
temperatures to surge into the lower 80s areawide, with a few spots
possibly briefly touching the middle 80s. Today`s record highs are
probably safe, but we won`t be far off. A few warm advection showers
can`t be entirely ruled out this afternoon west of I-65 on the
northwest edge of an upper ridge over the southeast United States,
but the main show will wait until tonight.

Tonight that Iowa low will deepen further as it proceeds into
Wisconsin, dragging its cold front into the Ohio Valley overnight.
Powerful storms erupting from the Midwest to the lower Mississippi
Valley this afternoon will move east into western Kentucky this
evening and cross Kentucky and southern Indiana overnight as a
broken line of storms. Surface dew points in the low to mid 60s will
interact with an incoming pre-frontal trough and cold front beneath
a 60kt low level jet and incoming 5H speed max. Expect a corridor of
1000-1500 J/kg MUCAPE with 200-300 m2/s2 SRH and 50-70kt of bulk
shear to support severe storms. Along with wet bulb zero heights
around 10-11k`, all severe weather modes will be possible,
especially west of I-65 in the evening with the best instability and
most likely time for surface-based storms.

.Long Term...(Sunday through Friday)
Issued at 311 AM EDT Sat Mar 28 2020

Sunday and Monday...By Sunday morning the cold front along with any
rain should be over eastern KY as high pressure and dry air begins
to fill in from the west. Tight pressure gradient continues between
the low now over the Great Lakes and high pressure over the western
Atlantic, resulting in gusty WSW surface winds in the 30-35mph range
under sunny skies. Expect highs on Sunday to continue to remain
several degrees above climo, reaching into the mid to upper 60s.
Winds gradually decrease overnight as high pressure and sunny skies
continue through Monday with lows in the mid 40s and highs in the
low to mid 60s.

Tuesday and Wednesday...Next chance of rain comes Tuesday as another
upper level shortwave makes its way along the southern stream.
Deterministic models are generally in good agreement at bringing the
surface low through the southern Gulf states with KY on the northern
periphery, which should result in mainly a rain event with possible
embedded thunder Tuesday evening across southern KY. Low level
moisture will be slow to exit and could see rain transition to light
drizzle Wednesday morning. Expect consistent temps during this
period with lows in the 40s and highs in the 50s.

Thursday and beyond...Models begin to diverge at this point as zonal
flow sets up aloft with the US caught between a slow moving closed
upper low over southern Canada and broad high pressure across
Mexico. Model blend wanted to keep chance PoPs throughout this
period, but upon collaboration with neighboring offices have decided
to go dry for now.


.Aviation...(18Z TAF Issuance)
Issued at 130 PM EDT Sat Mar 28 2020

VFR weather to continue through the afternoon and early evening
hours with BKN low to mid cloud cover and gusty SSW winds. Gusts up
to 20-25 kts will continue to be possible through late afternoon.

A broken line of thunderstorms ahead of a surface cold front will
move across the region tonight. The most likely time frame for
storms at each TAF site is included in the TAF and was tweaked only
slightly from the 12z issuance. Some of these storms could be quite
strong with gusty and possibly damaging winds, large hail, very
heavy rainfall, and lightning. Significant vsby restrictions and
lower ceilings likely in any storm. Even outside of thunderstorms,
SW winds at 2 kft will be around 45-50 kts tonight.

Clouds scatter out fairly quickly behind the cold front 09-12z
Sunday. However, it will remain quite windy on Sunday. 20 kt
sustained winds from the SW are likely after 13z or so, with gusts
up to 30-35 kts.




Short Term...13
Long Term...CG
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