Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 230720
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
320 AM EDT Sun Apr 23 2017

.SHORT TERM...(Today through Monday)
Issued at 320 AM EDT SUN APR 23 2017

06z sfc analysis shows a deep southern low passing by just to the
south of Kentucky. This low is responsible for the series of
waves - consisting of showers now - pushing across southern
Kentucky this weekend. Currently there is a lull between these
waves, even so sprinkles and drizzle are found across much of the
CWA this night. Low clouds blanket the southern half of the area
while in the far north they have actually cleared out. Winds are
from the north to northeast at 5 to 10 mph locking in the colder
air. Temperatures this night are running from near 45 degrees -
dewpoints in the upper 30s - north to the lower 50s in the far
south - dewpoints around 50.

The models remain in good agreement aloft through the short term
portion of the forecast. They all depict a developing and closing
off low moving into the Tennessee Valley and then continuing
south - rolling through the deep south. The models are quite
similar with the magnitude, placement, and timing of this low
lending a good deal of confidence to their consensus forecast.
Accordingly, have favored the CONSShort model blend for most GFE
weather elements with special attention to the high resolution
components in the short term.

Sensible weather will feature a renewed surge of moisture and
showers pushing north into the CWA towards dawn and continuing
through the bulk of the day. The heaviest showers and higher QPF
are anticipated through the areas that remain under a Flash Flood
Watch. This may be able to be cleared earlier in the afternoon in
the west, but will likely be needed through 4 pm in the eastern
part and possibly longer. For now, will hold to the current
timing for this headline and pass on to later shifts to watch for
a need to extend it later in the east. Otherwise, cloudy, rainy,
and cool weather will be the rule today and into the evening for a
good portion of the area. The exception may be locations north of
Interstate 64 where some sunshine may be seen early this morning
and then later filtered through the clouds - but still seasonably
cool. On Monday, the sfc low should be far enough east that drier
starts to make its way into the area and dry us out from northwest
to southeast - allowing temperatures to recover to a bit closer to
normal for this time of year.

Again started the grids from the CONSShort and ShortBlend guidance
set through this part of the forecast. Did not make much
adjustment to temperatures or dewpoints given the limited diurnal
range over the next 36 hours. However, did again beef up PoPs and
QPF, from the blend, across the south given the certainty for
measurable rain from yet a couple more surges of shower activity
during this time.

.LONG TERM...(Monday through Saturday)
Issued at 335 PM EDT SAT APR 22 2017

Models are in decent agreement through the extended with mid/upper
level flow. In general, the southern Appalachian region will fall
under the influence of mean southwesterly flow aloft. That would
indicate warmer weather than not, and an occasional shot at showers
and thunderstorms should any disturbances in the mean flow get close
enough to affect our area. One such disturbance does appear to skirt
just close enough to provide a chance of showers Wednesday night
into Thursday. Forecast soundings suggest instability is lacking but
considering the time of year, will maintain inherited Isold thunder
for this time frame. When compared to the ECMWF and Canadian, the
GFS is somewhat of an outlier towards the end of the extended window
with the potential of a second disturbance. The ECMWF and Canadian
swing this second disturbance through the area by late Friday into
Saturday, though the ECMWF is much more subtle with this feature.
Once again forecast soundings indicate instability is lacking, but
considering the synoptic pattern feel it would be prudent to
maintain at least a slight chance of thunder.

Sensible weather will seem closer to a summer like pattern than
spring with temperatures averaging some 5 to 10 degrees above
normal. Temperatures warm nicely through the week, with highs
climbing into the lower to mid 80s for much of the week. Lows fall
generally in the upper 50s to lower 60s each night. Outside of the
two disturbances mentioned earlier, any chance for rainfall would be
quite low based on soundings as a substantial cap appears to be in
place for most of the period.

&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
ISSUED AT 200 AM EDT SUN APR 23 2017

Main concern for aviation through the rest of the night will be
low cigs in the LIFR or IFR range but with the showers in a lull
through dawn, some cigs may briefly bounce up to MVFR. The next
surge of showers will push in from south to north during the day
Sunday with cigs bouncing between low MVRF and IFR and times of
visibility down to MVFR. SYM will have the best shot at remaining
VFR through Sunday night as the main influence of the weather
system passing by to the south wanes for locations north of a JKL
to SJS line. Winds will remain north to northeast through Sunday
night with speeds averaging around 5 kts but up to 10 kts at
times.

&&

.JKL WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch through this afternoon for KYZ079-080-083>088-
110-113-115>118-120.

&&

$$

SHORT TERM...GREIF
LONG TERM...RAY
AVIATION...GREIF



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