Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 180551

National Weather Service Jackson KY
151 AM EDT Tue Apr 18 2017

Issued at 151 AM EDT TUE APR 18 2017

A few showers could be reaching the ground in southern portions
of the CWA. Otherwise, most are dry this hour and areas near and
north of the Mountain Parkway are quite dry, with NE flow and
dewpoints in the upper 30s to lower 40s. Adjusted grids to line up
with latest obs/trends.

UPDATE Issued at 1052 PM EDT MON APR 17 2017

Some leftover light rain showers continue to hang on across
portions of the Cumberland Valley late this evening. This activity
is weakening; however, will hang onto scattered coverage another
few hours given the radar trends. Thicker high clouds have also
been more prevalent this evening, and the latest short term model
guidance suggests this will hamper the lows a bit more. As such,
have increased the lows another few degrees, with most locations
seeing middle 50s.

UPDATE Issued at 803 PM EDT MON APR 17 2017

Convection is on the wane with the loss of heating. Thunder has
stayed just to our south and will remove it through the rest of
the night. Have allowed for a longer dry period through the
overnight as instability and forcing diminish. Will maintain some
POPs toward dawn, as the leftover boundary starts to creep back
to the north. Lows will range from the lower 50s in the north to
the mid 50s in the south. Updates have been sent.


.SHORT TERM...(This evening through Tuesday night)
Issued at 339 PM EDT MON APR 17 2017

Current conditions across eastern Kentucky feature a weak boundary
slowly pushing south through the evening. Afternoon weak
convection, has made the front hard to discern and little lift.
Thus have lowered thunder chances to slight through the evening.
Though low level moisture is abundant, will keep pops across the
area for showers into tonight with lessening chances north of
I-64. Cloud cover will remain wide spread due to low level
moisture in place. Have lowered cloud cover in the north behind
the washed out front as well. Overall through tonight, enough lift
seems to be available and moisture to keep showers in the forecast
but thunder chances will drop off after 00Z from what chances were
relative in the evening.

Due to the moisture and light winds, what locations do see a break
in the clouds, some patchy fog may develop through dawn. By
Tuesday, the wash out boundary over the TN and KY border combined
with a weak upper wave moving into the TN valley from the mid MS
valley will be enough to spawn shower and thunderstorms over the
area. With increased southerly flow and the days heating,
instability will be enough for shower and thunderstorm chances
lifting north into the Bluegrass by Tuesday afternoon. Loss of the
days heating will mean thunderstorm chances will drop off Tuesday
night but the surge to the north will keep showers over eastern
Kentucky into Tuesday night. Overall, light shower activity is
expected through the short term with low thunder chances as
instability will be marginal at best through the rest of this
evening into tomorrow evening.

.LONG TERM...(Wednesday through Monday)
Issued at 339 PM EDT MON APR 17 2017

Overall model solutions seem to be in fairly decent agreement with
mid and upper level features. The pattern across the CONUS gradually
transitions from zonal to more amplified flow through the extended.
A weak, passing impulse may help kick off some shower and
thunderstorm activity across the area Wednesday. Then a more
significant wave will transit the Upper Midwest and Great Lakes
Region Thursday, dragging a cold frontal boundary through the Ohio
Valley by the end of the week. Energy moving out of the eastern
Pacific and across the CONUS will amplify the mid and upper level
pattern during the final 36 hours of the period. End result will be
a fairy deep trough over the eastern half of the nation. There are
some model differences with respect to strength and timing of this
last, most significant feature, which in turn complicates details in
our sensible weather enough that we will not stray too far form the
model blends and corresponding guidance.

For sensible weather, a weak mid level wave will be passing through
the region Wednesday, keeping a chance of showers and thunderstorms
in the forecast. It still appears that we should see a break in the
action Wednesday night. Attention then turns to a northern stream
wave tracking through the Great Lakes Thursday, along with its
associated surface low and training cold front that will bring
another round of showers and thunderstorms to our area late Thursday
into Thursday night. Despite less than favorable timing of the cold
front through our area, can not rule out the potential of seeing a
few strong storms across parts of the area Thursday night. Sfc based
CAPEs could approach 1000 J/kg, and with bulk wind shear of between
30 and 40 kts, these would be supportive of some stronger storms.

The aforementioned cold front will slide to our south and east by
Friday. However, at this time any break in the weather appears short
lived as a wave of low pressure rides northeast across the
Commonwealth through the weekend. At present and despite differences
in timing this storm system seems to all but guarantee unsettled
weather for next weekend. Bottom line, temperatures will continue to
run at seasonably warm levels, with a chance of rain just about
every day, and with short breaks between events.


.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)

VFR conditions are the story to begin the TAF period and will
remain through early this morning. It does look like MVFR ceilings
will creep north through the day today. A upper level wave will
interact with nearby boundary leading to convection through the
day. There remains some questions on how far east we will see much
in the way of instability and did opt to take thunder out of SJS
TAF. Also the far east could see some downslope flow that may
inhibit this as well. Overall winds will remain light under weak
flow, with winds from the NE to begin the period before shifting
to the SE through the day today.




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