Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 120125
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
825 PM EST Thu Jan 11 2018

.UPDATE...
Issued at 805 PM EST THU JAN 11 2018

Hourly grids have been freshened up based on recent observation,
model, and satellite trends. This led to no substantial changes at
this time. Model trends will continue to be monitored for the
upcoming event to fine tune timing and amounts. The usually better
performing 0-36 hour window of the NAM and Hi Res models like the
ARW and HRR will begin to capture the upcoming event over the next
few hours which should help to better define details with more
confidence.

&&

.SHORT TERM...(This evening through Friday night)
Issued at 349 PM EST THU JAN 11 2018

...Flood Watch tonight in the east...

With both the 12Z NAM and 12Z GFS in agreement with a band of
heavier rain setting up across far eastern KY tonight there is
concern for some local flooding. The NAM generates as much as 2.1
inches with the GFS around 1.6 inches. The 12Z ECMWF is lighter
with the heaviest amounts near 1 inch. Model generated
precipitable water in excess of 99% to record levels is possible
tonight. The 2 inch soil depth temperature at the Breathitt
County mesonet was 37 and at 4 inches was still 33 this afternoon.
Concerned that some hollows that typically don`t see any sun may
still have some frozen ground, and based on observations there is
still ice clinging to cliffs in the colder hollows. Our frost
depth earlier this week here at the office was 10 inches but it is
all thawed now, but again am concerned about hollows that may
still have mainly frozen ground so run off could be maximized.
The flood watch was issued earlier today and will continue with
the watch which is in good agreement with the watch for Charleston
WV`s area as well including their northeast KY counties.

...Winter Weather Advisory begins Friday afternoon and continues
through Friday night for entire forecast area...

A complicated forecast for Friday and Friday night with the winter
weather that will impact the area. As is typical there have been
various model differences from model to model and from run to run
with any specific model. However, ensemble blends have been more
stable. The SREF snow amounts have been remarkably stable for
several runs and our current forecast snow amounts are in good
agreement with the 15Z SREF. This results in 1 to 3 inch snow
totals with the highest amounts in the northwest part of the
forecast area and lowest amounts in the south and southeast. The
potential freezing rain amounts have been more challenging and
there has been less model agreement there. Have followed the CR
blended approach to generate precipitation types from Friday
afternoon into Friday night. This resulted in some very light ice
amounts, under 0.1 inch. Considerable collaboration occurred with
neighboring WFOs and WPC regardi the afternoon. Looking beyond
the TAF forecast period ng the headlines needed for this
event. Based on our collaborated forecast and collaborated messaging
it was determined that a winter weather advisory would best
handle the current forecast. With rapidly falling temperatures
Friday night icy roads will be the main impact, with hazardous
travel expected.

.LONG TERM...(Saturday through Thursday)
Issued at 232 PM EST THU JAN 11 2018

Cold weather looks to settle back into the region this weekend
behind the exiting storm system. Some light snow showers or
flurries could hang on well into Saturday before clouds start to
break up. High pressure will  the afternoon. Looking beyond
the TAF forecast period build in on Sunday and could set up a
cold Sunday night. Models coming into better agreement on a
clipper system for next Monday/Monday night and could bring
another round of light snow to the area. In the wake of the
clipper the cold air will be reinforced into the middle of next
week and some upslope snow showers could linger into the middle of
the week. It does look like the trough will start to lift out
later next week with a warming trend into the following weekend.

&&

.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
ISSUED AT 735 PM EST THU JAN 11 2018

Initial MVFR is expected near the VA border and in the southwest,
but guidance suggests improvement in all but the VA border
through 6Z and VA border by 9Z. Then as a cold front approaches
and moves across the area with ceilings deteriorating to MVFR and
then IFR 11Z to 17Z across the west and central and the entire
area through 20Z with reductions in vis as well. An initial wave
of low pressure should still bring showers to the eastern part of
the area through 9Z or 12Z. On Friday, winds shifting from south
and southwest to northwest 14Z to 21Z. Rain will begin changing to
snow between 18Z and 00Z from west to east with some FZRA or PL
possible during the transition.


&&

.JKL WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from 1 PM Friday to 7 AM EST Saturday
for KYZ044-050>052-058>060-068-069-079-080-083>087-104-106-108-
111-114-116.

Flood Watch through Friday morning for KYZ088-104-106-107-109-
110-112-113-115-117>120.

Winter Weather Advisory from 4 PM Friday to 7 AM EST Saturday
for KYZ088-107-109-110-112-113-115-117>120.

&&

$$

UPDATE...JP
SHORT TERM...SBH
LONG TERM...KAS
AVIATION...JP



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