Special Weather Statement, NWS Jackson, KY

AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
815 PM EDT Fri Jun 18 2021

.UPDATE...
Issued at 750 PM EDT FRI JUN 18 2021

23Z sfc analysis shows low pressure and a quasi-stationary west to
east oriented front to the north with a cluster of strong to
severe storms working southeast through southern Indiana and
southwestern Ohio. A healthy pressure gradient exists between the
low to the north and higher pressure to the south. This is
supporting southwest winds through the area running at 10 to 20
mph north to the 5 mph or less in the south. Under mostly sunny
skies temperatures climbed into the mid and upper 80s for much of
the area and have only slightly cooled with 80 t0 85 degree
readings most common across eastern Kentucky. Meanwhile, dewpoints
are also rather high with upper 60s north to the the mid 60s
south. The newer CAMs guidance and radar trends suggest that the
storms to the northwest could impact northern parts of the area
later this evening - likely fading out as they drop too far south.
However, instability and shear are relatively high for locations
along and north of the Mountain Parkway - along with high PW air.
Have updated the grids to add in higher PoPs and more of a storm
threat north while also including the latest obs and trends for
the sky cover/T/Td grids. These updates have been sent to the NDFD
and web servers. A zone and SAF update will be issued shortly to
incorporate these forecast adjustments.

&&

.SHORT TERM...(This evening through Saturday night)
Issued at 515 PM EDT FRI JUN 18 2021

Late this afternoon, an upper level ridge was centered over
northern AZ/Four Corners region with an upper level ridge centered
near the Bahamas while an upper level trough trough moving across
the Ontario and the Great Lakes region. Further south a low/
potential tropical cyclone was in the northern Gulf of Mexico.
This is leading to west to northwest flow aloft across the midwest
and Great Lakes as well as the OH Valley region. At the surface,
the region is in the warm sector of an area of low pressure
tracking across the southern Great Lakes region with sfc high
pressure centered over the southern Appalachians. Locally, despite
warm temperatures and increasing moisture, the low level flow
across the southeastern portions of the area has a downslope
component off the higher terrain of SW VA and northeast TN while
the highest dewpoints and greatest instability is across the
western and northwestern portions of the area. However, the the
earlier convection/outflow having become diffuse and fizzled
there are currently no triggers and only shallow to a bit of
moderate cumulus is across the region. Much stronger convection is
located north of the OH River in OH where instability and shear
are much greater.

This evening and tonight, 500 mb height falls are anticipated as
a series of shortwave troughs or perhaps MCVS from upstream
convection move across the OH Valley region. At the surface, the
frontal zone should become quasi stationary well north of the
area across the southern Great Lakes vicinity. There is
uncertainty in the evolution of convection this evening over the
OH Valley region, but convective allowing models generally develop
one or more clusters or MCSs and then track them to the east
southeast or southeast and into the Appalachian region late this
evening into the overnight hours. This convection will probably be
weakening as it does so, with the areas north of the Mountain
Parkway and near the WV border likely having the greater chances
for convection and the southwester locations the least. Some of
this could be strong with gusty winds or small hail across
northern locations where instability and shear should be greatest
though it tapers off with southward extent into the region. Some
training is not out of the question if an outflow can become
nearly parallel to west northwest flow aloft.

Saturday and Saturday night, passing disturbances and or
convection that moves into the region overnight may linger into
Saturday morning mainly across northern locations. The sfc frontal
zone should remain well north of the OH River during this
timeframe as well. The consensus of the guidance suggests that
activity lingering into Saturday morning should wane toward
midday, though additional development may occur across the south
during peak heating. Another disturbance in west northwest flow
should move across the lower OH Valley region Saturday evening
into Saturday night when chances for convection may peak across
the north. During this time, the low in the Gulf should move into
the deep south, but moisture from that system is currently
expected to remain south and east of the southern Appalachians.

Temperatures will be above normal during the short term period
with lows tonight and Saturday night in the mid to upper 60s while
highs on Saturday should average in the mid to upper 80s.

.LONG TERM...(Sunday through Friday)
Issued at 535 PM EDT FRI JUN 18 2021

A very warm pattern will prevail on Sunday and Monday along with
the threat for a showers and thunderstorms. The rainfall threat on
Sunday will be rather isolated with the more widespread activity
occurring Monday afternoon into early Tuesday morning with a
strong cold front. A noticeably cooler and drier Canadian air
mass will build across the area from later Tuesday through
Thursday. Warming temperatures and rising humidity levels return
for later in the week, courtesy a warm front. The models are
generally in good agreement on the overall pattern, although some
differences do arise from about Wednesday onward.

Diving into the details, look for a cold front, initially located
near/north of the Ohio River on Sunday morning, to retreat back
to the north, taking any spotty showers or storms with it.
Meanwhile, a tropical system is projected to pass from the from
AL/GA to over SC/NC by 00z Monday. This trajectory should keep
eastern KY mainly dry and downsloped, outside of a possible stray
shower/storm near the VA border. Otherwise, Sunday will be partly
to mostly sunny with above normal temperatures between 85 and 90
degrees. Mainly quiescent weather will continue Sunday night with
mild lows in the mid 60s to around 70.

Well to our northwest, an unseasonably deep upper level trough
will be amplifying over north central US on Sunday, dropping
southeast and enveloping nearly all of the eastern CONUS by
Wednesday. An associated surface low will rapidly deepen and lift
from the Central Plains to northern Quebec, sweeping a strong cold
front across the Commonwealth late Monday/Monday night. GFS
soundings show effective shear values increasing to between 30 and
35 knots while MLCAPE values reach 1200-1800 J/kg -- sufficient
for organized convection. Ahead of the front, temperatures will
again be very warm, reaching 85 to 90 degrees. While some spotty
showers or storms are possible earlier, the primary window for
convection appears to be 18z Monday - 9z Tuesday. Behind the
front, chilly Canadian high pressure will build across the Ohio
Valley and Great Lakes on Tuesday. A drying, N/NW flow will send
850 mb temps tumbling into the 8-12C range by 00z Wednesday. This
will translate to highs only in the low to mid 70s for most
locations on Tuesday and in the mid to upper 70s on Wednesday. Low
temperatures in the upper 40s to mid 50s, valley to ridges, can
be expected both Tuesday and Wednesday nights. A few mid 40s are
possible in the coldest sheltered valleys either night.
Additional moderation into the lower to mid 80s is expected on
Thursday. The latest 12z ECMWF does show a weak upper level
disturbance bringing some light QPF on Wednesday, but this is not
supported by other models at this point. Therefore, once any
lingering showers depart to the east Tuesday morning, dry weather
is expected through Thursday. The next warm front approaches
Thursday night or Friday, but there is plenty of model
disagreement on the details.

&&

.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
ISSUED AT 815 PM EDT FRI JUN 18 2021

VFR conditions will prevail during the first 3 to 6 hours of the
period. Winds will be generally out of the southwest through the
night - sustained at near 10 kts across the west and northwest
with gusts up to 20 kts near and north of I-64 to start the
period. Look for these winds to slacken through about 03Z before
an area of thunderstorms will probably approach from the north
and start to affect the JKL aviation forecast area, particularly
our more northern locations. Additional strong convection could
impact the area towards dawn if the latest mesoscale models are
correct. Winds will then pick up from the southwest during the day
Saturday at around 10 kts along with scattered convection. Only
locations directly impacted by any of these storms are expected to
see conditions drop to MVFR or lower - too uncertain for inclusion
in the prevailing TAF FM groups at this time.

&&

.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

UPDATE...GREIF
SHORT TERM...JP
LONG TERM...GEERTSON
AVIATION...JP/GREIF

Hazardous Weather Outlook...UPDATED
National Weather Service Jackson KY
925 PM EDT Fri Jun 18 2021

KYZ050-058>060-104-106>112-119-120-200430-
Montgomery-Estill-Powell-Menifee-Elliott-Morgan-Johnson-Wolfe-
Magoffin-Floyd-Lee-Breathitt-Martin-Pike-
Including the cities of Camargo, Jeffersonville, Mount Sterling,
Irvine, Ravenna, Clay City, Stanton, Frenchburg, Sandy Hook,
West Liberty, Paintsville, Campton, Salyersville, Prestonsburg,
Wheelwright, Beattyville, Jackson, Inez, Coal Run, Elkhorn City,
Pikeville, and South Williamson
925 PM EDT Fri Jun 18 2021

This hazardous weather outlook is for portions of eastern Kentucky.

.DAY ONE...Tonight.

Thunderstorms are possible late this evening and tonight,
especially north of the Mountain Parkway. Some of the these could
produce strong wind gusts, locally heavy rain, and small hail.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

Thunderstorms with gusty winds are possible on Saturday, mainly
in the morning. Thunderstorms are also possible at times from
Saturday evening through Tuesday, mainly during the afternoon and
evening hours.

.SPOTTER INFORMATION STATEMENT...

Spotters are requested to report any storm damage or hail through
the night.

KYZ044-051-052-200430-
Fleming-Bath-Rowan-
Including the cities of Flemingsburg, Owingsville, and Morehead
925 PM EDT Fri Jun 18 2021

...SEVERE THUNDERSTORM WATCH 281 IN EFFECT UNTIL 3 AM EDT
SATURDAY...

This hazardous weather outlook is for portions of eastern Kentucky.

.DAY ONE...Tonight.

Strong to severe thunderstorms are expected late this evening and
into the first part of tonight. Some of the these could produce
damaging wind gusts, heavy rain, and large hail.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

Thunderstorms with gusty winds are possible on Saturday, mainly
in the morning. Thunderstorms are also possible at times from
Saturday evening through Tuesday, mainly during the afternoon and
evening hours.

.SPOTTER INFORMATION STATEMENT...

Spotters are requested to report any storm damage or hail through
the night.

KYZ068-069-079-080-083>088-113>118-200430-
Rockcastle-Jackson-Pulaski-Laurel-Wayne-McCreary-Whitley-Knox-
Bell-Harlan-Knott-Owsley-Perry-Clay-Leslie-Letcher-
Including the cities of Brodhead, Mount Vernon, McKee, Annville,
Burnside, Somerset, London, Monticello, Stearns, Whitley City,
Corbin, Williamsburg, Barbourville, Middlesboro, Pineville,
Cumberland, Harlan, Hindman, Pippa Passes, Booneville, Hazard,
Manchester, Hyden, Jenkins, and Whitesburg
925 PM EDT Fri Jun 18 2021

This hazardous weather outlook is for portions of eastern Kentucky.

.DAY ONE...Tonight.

No hazardous weather is expected at this time.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

Thunderstorms are possible at times from late Saturday afternoon
through Tuesday, mainly during the afternoon and evening hours.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not anticipated.

JP/GREIF

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