Special Weather Statement, NWS Louisville, KY

Area Forecast Discussion
National Weather Service Louisville KY
327 PM EDT Thu Jul 15 2021

.Short Term...(This evening through Friday)
Issued at 310 PM EDT Thu Jul 15 2021

Regional radar mosaic shows very isolated showers popping up across
the region as sfc temperatures exceed convective temperatures. KY
Mesonet obs show temps mostly in the upper 80s, and the SDF heat
island in full effect with 91F so far. Model soundings seem to have
a good handle on current conditions compared to latest AMDAR
sounding data from SDF, which continues to show a strong 600mb
inversion overhead. Expect this mid-level warm layer to persist
though this afternoon and evening, but should eventually erode by
the overnight hours.

For the rest of this afternoon, expect to continue to see isolated
shallow showers. Will keep a low chance PoP in before 00z for the
entire CWA, but most folks will stay dry. Could have a few rumbles
of thunder mixed in, but the inversion should be enough to cap tall
vertical cloud growth.

For tonight, upper shortwave trough currently across Kansas will
shift eastward across Missouri, resulting in the southeastern US
ridge to weaken and push further east. A secondary sfc low will
develop across Missouri by tomorrow morning and track to the NE
along the I-70 corridor. As a result, tightening low level pressure
gradient will develop a LLJ, with 850mb winds expected to be 20-
35kts. As the SW LLJ noses into our region, scattered convection
will be moving in from Illinois ahead of the slow moving sfc frontal
boundary tonight and into tomorrow.

SPC holds a Day 2 Marginal Risk across our northern half of the CWA
for tomorrow, which seems well placed. CAMs are hinting at some
possible organized convection tomorrow afternoon and evening, most
likely across souther IN under the 850mb jet core. Temperatures
should breach ConvT again, with highs primarily in the upper 80s and
low 90s. Instability could reach 1000-2000 J/kg of MLCAPE during
peak daytime heating, and effective bulk shear values between 20-
30kts. With PWATs also expected to be 2.10+", torrential rain rates
with any training or slow moving storms would create some localized
flash flooding hazards. Organized convection could also pose a
threat of damaging winds and frequent lightning.

&&

.Long Term...(Friday night through Thursday)
Issued at 240 PM EDT Thu Jul 15 2021

Friday Evening through Sunday...By Friday evening, the surface
boundary will be stretched SW-NE across central IL/IN and into the
lower Great Lakes with ongoing convection out ahead of the boundary,
affecting our area in southern Indiana and central KY. The OH
Valley's position between Atlantic ridging and the upper trough will
result in deep SW flow with PWATs around 2.00 inches. GEFS/GFS IVT
continues to advertise moisture maxima remaining to our north, but
model soundings continue to show saturated columns with tall, skinny
CAPE profiles and high RH throughout the low to mid levels. Expect
to see some efficient rainfall with this activity with localized
flooding concerns being the main hazard of concern given parallel
nature of steering flow to boundary positioning. Mitigating factors
will include dry antecedent conditions and progressive nature of
individual cells. Will just have to watch for training. And given
the weak shear and moderate to high CAPE, expect low-end severe
chances with pulse storm modes most likely. Diurnal enhancements
will result in most rainfall accumulation taking place Friday
evening and again Saturday afternoon. And as the boundary drops
south through central KY on Sunday, expect to see lower PoPs across
southern Indiana.

Monday and beyond...Models continue to show Omega Block over the
western and central CONUS, which will place the OH Valley under NW
flow. Expect mostly dry conditions throughout this period.
Thickness values slowly increase through the week so expect high
temps in the mid 80s to increase to upper 80s by Thursday.

&&

.Aviation...(18Z TAF Issuance)
Issued at 145 PM EDT Thu Jul 15 2021

Sfc obs reveal VFR conditions this afternoon as diurnal cumulus
clouds scatter the region. These should begin to dissipate around
sunset as peak heating is lost, but upper level cirrus should
remain. Other than a very isolated shower possible across south-
central Kentucky this afternoon, we look to remain dry until
tomorrow.

Convection currently stretching across northern Missouri and eastern
Kansas will slowly be working eastward tonight. This convection
should be weakening by tomorrow morning, first arriving at HNB
sometime between 06-12z tomorrow. Confidence beyond that is limited
at this time due to disagreements on timing of precip between model
guidance. For this reason, decided to include PROB30 groups to at
least mention the potential for precip.

&&

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

Short Term...CJP
Long Term...CG
Aviation...CJP

Hazardous Weather Outlook
National Weather Service Louisville KY
327 PM EDT Thu Jul 15 2021

INZ076>079-083-084-089>092-KYZ023>043-045>049-053>057-061>067-
070>078-081-082-161930-
Orange-Washington-Scott-Jefferson-Dubois-Crawford-Perry-Harrison-
Floyd-Clark-Hancock-Breckinridge-Meade-Ohio-Grayson-Hardin-Bullitt-
Oldham-Trimble-Henry-Shelby-Franklin-Spencer-Anderson-Woodford-
Fayette-Bourbon-Nicholas-Nelson-Mercer-Jessamine-Larue-Marion-Boyle-
Garrard-Madison-Butler-Edmonson-Hart-Green-Taylor-Casey-Lincoln-
Logan-Warren-Simpson-Allen-Barren-Monroe-Metcalfe-Adair-Russell-
Cumberland-Clinton-
Including the cities of Paoli, Salem, Scottsburg, Madison, Jasper,
English, Tell City, Corydon, New Albany, Jeffersonville, Lewisport,
Hawesville, Hardinsburg, Brandenburg, Hartford, Leitchfield,
Elizabethtown, Shepherdsville, Louisville, La Grange, Bedford,
Milton, New Castle, Shelbyville, Frankfort, Georgetown, Cynthiana,
Taylorsville, Lawrenceburg, Versailles, Lexington, Paris, Carlisle,
Bardstown, Springfield, Harrodsburg, Nicholasville, Winchester,
Hodgenville, Lebanon, Danville, Lancaster, Richmond, Morgantown,
Brownsville, Horse Cave, Greensburg, Campbellsville, Liberty,
Stanford, Russellville, Bowling Green, Franklin, Providence,
Scottsville, Glasgow, Tompkinsville, Edmonton, Columbia, Jamestown,
Burkesville, and Albany
327 PM EDT Thu Jul 15 2021 /227 PM CDT Thu Jul 15 2021/

This hazardous weather outlook is for portions of south central
Indiana and Central Kentucky.

.DAY ONE...Tonight.

No hazardous weather is expected at this time.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday.

Several rounds of showers and storms are possible Friday into the
weekend. Some storms may be strong with gusty winds and heavy
rainfall as the most likely hazards.

.SPOTTER INFORMATION STATEMENT...

Spotters are invited to submit reports to the National Weather
Service this weekend.

&&

More information, along with other weather, hydrological and
climate information can be found at weather.gov/louisville.

CJP/CG

Special Weather Statement
National Weather Service Louisville KY
341 PM EDT Thu Jul 15 2021

KYZ040>042-047>049-055>057-152030-
Boyle-Bourbon-Mercer-Woodford-Fayette-Jessamine-Clark-Madison-
Garrard-
341 PM EDT Thu Jul 15 2021

...A STRONG THUNDERSTORM WILL AFFECT EASTERN MERCER...SOUTHEASTERN
WOODFORD...NORTHERN GARRARD...NORTHWESTERN CLARK...JESSAMINE...
SOUTHWESTERN BOURBON...NORTHEASTERN BOYLE...NORTHWESTERN MADISON AND
FAYETTE COUNTIES...

At 341 PM EDT, a strong thunderstorm was located 8 miles northeast of
Harrodsburg, moving east at 25 mph.

Winds in excess of 30 mph are possible with this storm.

Locations impacted include...
Lexington, Nicholasville, Danville, Versailles, Harrodsburg,
Meadowthorpe, Dunbar High School, Thoroughbred Acres, Cardinal Hill
and Cadentown.

Torrential rainfall is also occurring with this storm, and may cause
localized flooding. Do not drive your vehicle through flooded
roadways.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

LAT...LON 3763 8441 3766 8485 3807 8479 3809 8421
TIME...MOT...LOC 1941Z 265DEG 23KT 3786 8475

MJ