Area Forecast Discussion
Issued by NWS Jackson, KY

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000
FXUS63 KJKL 052000
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
300 PM EST Mon Dec 5 2016

.SHORT TERM...(This evening through Tuesday night)
Issued at 300 PM EST MON DEC 5 2016

An are of low pressure aloft is forecast to move out of the
southern Plains/western Gulf coast region this evening, and will
be our primary weather maker through tomorrow night. Most of the
latest model data is suggesting that precipitation onset will
still be a couple of hours later than the night shift forecast was
indicating. The new forecast will reflect a blend of the latest
model data with precipitation onset anticipated around 1Z this
evening in our far southern counties, or roughly two hours later
than previously forecast. Based on the expected temperature
profiles, precipitation will be in the form of all rain across
eastern Kentucky. The best chance for rain will occur from late
tonight through Tuesday afternoon. The rain should begin to taper
off Tuesday afternoon and evening, with the last rain showers
exiting the area between 9 and 10Z Wednesday. Area wide we can
expect around an inch of rain from this event.

Temperatures are expected to run at or slightly below normal
through tonight, with a non diurnal temperature progression
tonight. There will likely be a period of time tonight during
which temperatures actually begin to increase, as winds also
increase and shift more to the south and widespread precipitation
sets in. Highs on Tuesday are expected to top out in the 50s,
with lows in the 40s tonight and the 30s Tuesday night.

.LONG TERM...(Tuesday night through Sunday)
Issued at 510 AM EST MON DEC 5 2016

Models are finally showing better agreement with mid/upper level
features through the extended and have even seen some trends
towards better agreement in sensible weather elements. A broad
trough moving through the Intermountain west at the start of the
period will reach the Ohio Valley Wednesday night, passing
through during the day Thursday. The 0Z GFS and Canadian, having
been the more consistent runs, are a bit stronger with the mid
level features of this system than the 0Z ECMWF. Regardless the
boundary layer and sfc features associated with this disturbance
are quite weak. Timing is similar with all solutions now, with the
ECMWF only slightly slower. Overall trends are for lower pops and
less QPF potentials. However, this system will still usher in some
very cold air into the region, with H850 temperatures bottoming
out close to -15C. The high pressure system building in behind
this disturbance will settle down directly over the Commonwealth
Friday night, allowing temperatures to drop into the low to mid
teens by Saturday morning. Would not be surprised if morning lows
flirted with some single digits Saturday in our typically colder
valley spots.

Thereafter return flow develops rather quickly, pulling plenty of
moisture northward back through the MS valley and into the OH.
If initial indications are correct, fairly strong isentropic lift
will bring overspreading precipitation back into our area as early
as Sunday. Too early to capture details at this time, but with the
cold air in place imagine that precipitation will probably fall as
a wintry mixture at the onset early Sunday morning before
transitioning to just rain through the day.

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
ISSUED AT 1238 PM EST MON DEC 5 2016

Widespread cloud cover will persist across eastern Kentucky
through the end of the TAF period. These clouds are associated
with both a departed area of low pressure aloft and a second upper
level system that will approach from the southwest this evening
and tonight. MVFR CIGS are expected through between 5 and 7Z
tonight. After that, much lower clouds are forecast to move in,
with IFR TO LIFR CIGS of around 500 feet expected. The first rain
showers should begin moving across the TN border into eastern KY
between 1 and 2Z this evening, with the rain becoming widespread
by between 6 and 8Z area wide. SME and LOZ can expect rain to
affect their sites around 5Z, JKL by 6Z and SYM and SJS between 8
and 9Z. IFR to MVFR VSBYs will be possible with any rain showers,
with the lower VSBY associated with the more intense rain showers
we will experience late tonight.These low CIGS are expected to
persist through the end of the TAF period once they set in.

&&

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

$$

SHORT TERM...AR
LONG TERM...RAY
AVIATION...AR


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