Special Weather Statement, NWS Louisville, KY

Area Forecast Discussion
National Weather Service Louisville KY
901 AM EDT Sun Jun 21 2020

.Forecast Update...
Issued at 850 AM Sun Jun 21 2020

Surface analysis this morning reveals a weak area of low pressure
and cyclonic rotation near the MO/AR/TN borders this morning in
association with a weak mid-level shortwave. Already starting to see
precipitation creep into southwestern portions of the forecast area
(near the BWG metro area). Not seeing much lightning activity with
this line of precipitation at this time, and the few strikes that
are occurring are generally south of the KY border.

While model guidance has captured the center of this low and
associated shortwave fairly well in spatial and temporal terms, they
have struggled to resolve some of the banded precipitation out ahead
of it. For example, many high-res models do not capture this initial
band of rain showers and isolated storms moving into our region
right now. Confidence remains low as to how it may evolve, though if
recent runs of the HRRR are on to anything, it should slowly begin
to dissipate over the next several hours.

This early round of rainfall and its associated cloud cover will
likely have impacts on how things evolve this afternoon. The clouds
and rain cooled air should serve to stabilize the atmosphere to a
certain degree, limiting any potential severe threat initially.
Based on current observations and trends for how things may evolve
today, think that the best threat for any strong to marginally
severe storms should be east of the I-65 corridor, closer to the I-
75 corridor, where plentiful sunshine today should aid in some
destabilization of the atmosphere. West of I-65, we may see some
clearing by mid to late afternoon, but there remains a good deal of
uncertainty if it will be enough to destabilize the atmosphere to
support any sort of severe threat.

The forecast has been updated this morning to account for the latest
trends in precipitation timing, as well as adjusting temperatures
based on where clouds and rain are likely to persist.

&&

.Short Term...(This afternoon through Monday)
Issued at 300 AM EDT Sun Jun 21 2020

Currently seeing mostly clear skies and quiet conditions across our
area as the region remains under the influence of weak ridging
aloft. This ridge axis will slowly begin to push eastward over the
next several hours while a MCV near Arkansas simultaneously advances
NE toward the region. As such, expect cloud cover to gradually ramp
up after daybreak along with chances for showers and storms. Though
latest model runs continue to show a bit of variability concerning
the exact track of the system, they do all generally agree that the
best chances for seeing widespread showers/storms will occur during
the afternoon/evening hours.

In regard to the severe potential, model soundings show a tall and
skinny profile, with CAPE values ranging between 1000-2000 J/kg,
marginal deep layer shear (25-30 kt 0-6km bulk shear), and PWATs up
to 1.8 inches. Aside from this, models also show a persistent 25-
35kt southwesterly LLJ just south of the region throughout the day,
which will help advect juicy Gulf moisture across the region. Thus,
while the environment seems more favorable for pulse storms,
wouldn't entirely rule out the possibility of seeing some organized
convection this afternoon/evening, especially if we can destabilize
enough during the daylight hours. As such, think isolated damaging
winds would be the main threat from the strongest storms, though
heavy downpours, lightning, and small hail may still occur. An
isolated flood threat also can't be ruled out, especially in areas
where training storms occur. Otherwise, expect showers/storms to
gradually diminish after sunset, with winds becoming light and
variable overnight.

.Long Term...(Monday night through Saturday)
Issued at 230 AM EDT Sun Jun 21 2020

Monday morning, we should start off with brief shortwave ridging, in
the wake of the MCV drifting northeast away from the region earlier
in the morning. Another MCV moving in from the west could be the
spark for the next round of storms later Monday afternoon, but
mesoscale details will be a big factor in how this system travels.
NMM and 3km NAM both show this feature focusing storm activity,
whereas the ARW and 12Z/20 hi-res Euro and even a signal in the
21Z/20 SREF keep these new storms southwest of our area...instead
having the ridging stay strong enough to keep the afternoon dry!
Given the available moisture in the region...it won't take much in
the way of insolation/residual boundaries to initiate new cells,
even without the MCV. Feel like the categorical range PoPs, 75%+,
from the blended models are a bit high, but likely range, 55-74, is
more reasonable. Temperatures should be around normal, given that we
should see enough cloud cover to keep us out of the 90s. That still
should give sufficient instability for a few stronger storms. Slow
moving storms will bring another threat for localized flooding.

Details continue to get muddy as we get into Tuesday, but the
broader scale pattern has a cold front moving slowly to the Ohio
River. Moisture pooling ahead of this front should bring continued
good rain chances until that front can get out of here Wed/Wed
night. Any drying looks short-lived however, as troughing aloft will
continue to bring some disturbances, perhaps as early as Thursday
night and then we get back into a diurnal pattern of storms Friday
and Saturday. Those days look to be the warmest of this period, as
we get back to having a chance for 90s again.

&&

.Aviation...(12Z TAF Issuance)
Issued at 640 AM EDT Sun Jun 21 2020

Current satellite imagery shows an expansive stratus deck just to
the west of us slowly starting to impact the region. Expect cigs to
gradually lower from W to E and approach MVFR levels as a strong
system takes aim at the Ohio Valley later today. While a few
showers/thunderstorms may develop by mid-morning, the best chances
for seeing widespread coverage with lowering cigs/vsbys will occur
during the afternoon/evening hours. Have covered this with TEMPO
groups at all TAF sites generally between 18-24z. Storms should
begin to diminish near sunset, although a few showers may still
linger into the late evening. Otherwise, expect SW winds to prevail
throughout the period.

&&

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

Update...DM
Short Term...SSC
Long Term...RJS
Aviation...SSC

Hazardous Weather Outlook
National Weather Service Louisville KY
822 AM EDT Sun Jun 21 2020

INZ076>079-083-084-089>092-KYZ023>043-045>049-053>057-061>067-
070>078-081-082-221230-
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
822 AM EDT Sun Jun 21 2020 /722 AM CDT Sun Jun 21 2020/

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

.DAY ONE...Today and Tonight.

Showers and thunderstorms will develop in the region today, with the
greatest coverage of thunderstorms expected during the afternoon.
Some of these thunderstorms could become strong to marginally severe,
and would be capable of gusty winds, heavy rainfall, and lightning.
Thunderstorms could persist through the evening and early overnight
hours before pushing east of the I-75 corridor by midnight.

.DAYS TWO THROUGH SEVEN...Monday through Saturday.

Scattered showers and thunderstorms will be possible through
Wednesday, with the strongest storms capable of producing brief
heavy downpours, lightning, small hail, and gusty winds.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not anticipated at this time.

DM

Special Weather Statement
National Weather Service Louisville KY
1234 PM EDT Sun Jun 21 2020

INZ077>079-091-092-211715-
Washington-Jefferson-Floyd-Clark-Scott-
1234 PM EDT Sun Jun 21 2020

...A LINE OF GUSTY SHOWERS WITH EMBEDDED THUNDERSTORMS WILL AFFECT
WEST CENTRAL JEFFERSON...CLARK...NORTHEASTERN FLOYD...SCOTT AND
WASHINGTON COUNTIES...

At 1234 PM EDT, radar indicated strong thunderstorms were located
along a line extending from 12 miles northeast of Carefree Town to
near Salem to 7 miles northwest of Prospect. Movement was north at 40
mph.

Winds in excess of 40 mph are possible with these storms.

Locations impacted include...
Scottsburg, Salem, Clarksville, Vienna, Charlestown, Sellersburg,
Austin, Lexington, Blue River and New Pekin.

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

LAT...LON 3880 8554 3834 8566 3844 8605 3842 8627
      3873 8626 3878 8618 3876 8613 3878 8609
      3876 8603 3877 8598 3875 8598 3875 8590
      3873 8589 3873 8587 3881 8579 3882 8575
      3883 8573 3882 8570 3883 8561
TIME...MOT...LOC 1634Z 193DEG 36KT 3840 8625 3854 8604 3840 8573

DM

Special Weather Statement
National Weather Service Louisville KY
1249 PM EDT Sun Jun 21 2020

KYZ034-035-039-211715-
Shelby-Franklin-Anderson-
1249 PM EDT Sun Jun 21 2020

...A STRONG THUNDERSTORM WILL AFFECT SOUTHEASTERN SHELBY...
NORTHWESTERN ANDERSON AND SOUTHWESTERN FRANKLIN COUNTIES...

At 1248 PM EDT, a strong thunderstorm was located 8 miles west of
Lawrenceburg, moving northeast at 25 mph.

Winds in excess of 40 mph and pea size hail are possible with this
storm.

Locations impacted include...
Frankfort, Wayside, Gee, Anderson City, Birdie, Glensboro, Farmdale,
Broadville Manor, Avenstoke and Alton.

LAT...LON 3816 8486 3797 8499 3801 8512 3802 8513
      3803 8510 3804 8510 3805 8513 3822 8506
TIME...MOT...LOC 1648Z 202DEG 21KT 3804 8505

DM

Special Weather Statement
National Weather Service Louisville KY
1255 PM EDT Sun Jun 21 2020

KYZ055-066-067-211730-
Boyle-Lincoln-Casey-
1255 PM EDT Sun Jun 21 2020

...A STRONG THUNDERSTORM WILL AFFECT NORTHWESTERN LINCOLN...CENTRAL
BOYLE AND NORTH CENTRAL CASEY COUNTIES...

At 1255 PM EDT, a strong thunderstorm was located 7 miles south of
Danville, moving northeast at 35 mph.

Wind gusts up to 50 mph and half inch hail are possible with this
storm.

Locations impacted include...
Danville, Junction City, Hustonville, Alum Springs, Caldwell Manor,
Milledgeville, Hedgeville, Faulconer, Little Needmore and Davis Hill.

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

LAT...LON 3744 8481 3750 8495 3770 8482 3772 8479
      3771 8474 3770 8474 3770 8470 3768 8470
      3769 8468 3768 8468 3766 8471 3765 8468
      3764 8469 3764 8468 3765 8466 3764 8467
      3764 8465 3762 8464 3761 8465 3760 8462
TIME...MOT...LOC 1655Z 212DEG 30KT 3754 8482

DM

Special Weather Statement
National Weather Service Louisville KY
114 PM EDT Sun Jun 21 2020

KYZ040-211730-
Woodford-
114 PM EDT Sun Jun 21 2020

...A STRONG THUNDERSTORM WILL AFFECT CENTRAL WOODFORD COUNTY...

At 114 PM EDT, a strong thunderstorm was located near Versailles,
moving northeast at 15 mph.

Winds in excess of 40 mph are possible with this storm.

Locations impacted include...
Versailles, Bonita, Firmantown, Pisgah, Mortonsville and Gaybourn.

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

LAT...LON 3794 8473 3798 8482 3811 8477 3807 8464
TIME...MOT...LOC 1714Z 206DEG 15KT 3800 8475

DM

Special Weather Statement
National Weather Service Louisville KY
120 PM EDT Sun Jun 21 2020

KYZ033>035-211745-
Shelby-Henry-Franklin-
120 PM EDT Sun Jun 21 2020

...A LINE OF STRONG THUNDERSTORMS WILL AFFECT NORTHEASTERN SHELBY...
SOUTHEASTERN HENRY AND FRANKLIN COUNTIES...

At 120 PM EDT, radar indicated strong thunderstorms were located
along a line extending from 8 miles northeast of Shelbyville to near
Frankfort. Movement was northeast at 30 mph.

Winds in excess of 40 mph are possible with these storms.

Locations impacted include...
Frankfort, Pleasureville, Slickway, North Pleasureville, Elmburg,
Harvieland, Elmville, Old Christianburg, Hatton and Defoe.

LAT...LON 3846 8495 3844 8496 3843 8496 3843 8494
      3845 8494 3844 8492 3843 8492 3842 8488
      3838 8490 3837 8487 3836 8487 3836 8484
      3834 8479 3835 8474 3823 8473 3817 8479
      3814 8486 3823 8516 3852 8509
TIME...MOT...LOC 1720Z 204DEG 27KT 3830 8511 3816 8483

DM

Special Weather Statement
National Weather Service Louisville KY
121 PM EDT Sun Jun 21 2020

KYZ067-211745-
Lincoln-
121 PM EDT Sun Jun 21 2020

...A STRONG THUNDERSTORM WILL AFFECT NORTHEASTERN LINCOLN COUNTY...

At 121 PM EDT, a strong thunderstorm was located over Stanford,
moving northeast at 20 mph.

Wind gusts up to 50 mph are possible with this storm.

Locations impacted include...
Stanford, Halls Gap, Boneyville, Walnut Flat, Maywood, Blue Lick,
Logantown, Rowland and Gilbert.

LAT...LON 3743 8462 3749 8473 3760 8465 3762 8464
      3760 8464 3760 8462 3759 8462 3754 8454
TIME...MOT...LOC 1721Z 204DEG 17KT 3750 8465

DM