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000 
FXUS63 KJKL 160635 AAA
AFDJKL

AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
135 AM EST Mon Dec 16 2019

.UPDATE...
Issued at 135 AM EST MON DEC 16 2019

Updated the grids through the rest of the night to shift the
higher PoPs southeast and add a slight chance of thunder in the
southwest parts of the area. Did also include the latest obs and
trends for the T/Td. These updates have been sent to the NDFD and
web servers along with the issuance of a freshened set of zones
and HWO. 

UPDATE Issued at 1000 PM EST SUN DEC 15 2019

Another round of precipitation is moving across portions of
eastern Kentucky this hour. This has been rain for much of the
area, but some areas mainly along and north of I-64 have seen a
wintry mix of snow, rain, and sleet this evening. This mixing has
been evident on the WSR-88D Dual Pol CC moments where lower CC
values are occurring in the mixed precip region or even perhaps
melting snow in some cases. Little to no snow accumulations are 
expected given the marginal air temperatures and warm ground 
temperatures. However added a period of sleet in the northern 
portions of eastern Kentucky for a few hours along with the rain 
and snow that was already in the grids. After this warm nose will
push north and rain will take hold across the region around 05 to
06Z. Still a fair amount of uncertainty showing up with the 18Z 
runs on exact placement of higher rainfall amounts through 
Tuesday. This will be looked at further with the overnight shift 
and new 00Z data. Therefore no plans to make any major changes to 
the messaging of the flooding threats at this point. Updated 
thoughts have been sent to NDFD.

UPDATE Issued at 740 PM EST SUN DEC 15 2019

The initial band of precipitation has generally moved across the
area this evening. This lead band has produced some light snow
and/or rain mainly across Fleming County this evening. We still 
have some lighter returns showing up this hour and did add/keep 
some rain/snow mix in areas north of I-64 through the early 
evening. Given the warm ground temperatures and light nature would
expect little if any snow accumulations. Then a 850mb low level 
jet at around 50 knots, evident on OHX VAD around 0030Z this 
evening, will advect north and lead to warming of the low level 
layers through the night. This jet will continue rain in some 
areas and increase rain in other areas across the region through 
the evening and overnight. Updates to the forecast have been sent 
to NDFD.

&&

.SHORT TERM...(This evening through Monday night)
Issued at 341 PM EST SUN DEC 15 2019

Current conditions across the area features a boundary beginning 
to set up across the lower OH Valley and TN Valley as a ever 
present gradient sets up. This can be seen across eastern Kentucky
even this hour as some clearing has occurred in the far southeast
Kentucky area and the north remains cloudy. This is present in 
the temperatures as well with southern locations warming to around
50 and Fleming-Mason Airport still at 36 degrees. North of the 
boundary, moisture advection has begun with radar returns across 
the region showing some precip working into central Kentucky. The 
first wave will track up the boundary and into the OH Valley this 
evening with the surface low strengthening over the Mid MS Valley.
This will bring the low level jet into the area with the first 
surge of moisture moving into northern Kentucky by 00Z and 
continuing through the night. Current model trends now have this 
main axis of moisture pushing into the area through central 
eastern Kentucky and then persisting through Tuesday morning as 
the next wave deepens and moves northeast. While there has been 
some variability in the models through the last several runs, the 
mean of the tracks has kept close to the current runs low tracks. 
Thus, a Flood Watch has been issued for eastern Kentucky. The 
variability will lead less confidence to keep any counties out of 
the north and south so the entire CWA was included. 

The only other concern for the tonight period is the possibility
of snow mixing in with the rain. While northern Fleming county was
kept rather cool due to cloud cover this afternoon, the boundary
to the south is pushing northward rather quick as the low to the
west strengthens and will lead to quite a surge of warm air
through eastern Kentucky. In fact, model soundings indicate a warm
nose of 4 to 5 degrees aloft, this certainly ensure an all liquid
event. A few instances of snow mixing with rain is possible
tonight at the onset of the precip and if temps dip a degree or
two before the warm air advection surges north changing all precip
to all liquid. A surge of moisture will then ensue late tonight
and continue through the day on Monday. Southeast Kentucky will
then be in the warm sector with increased southerly flow. Later in
the day on Tuesday, the cold front will finally approach with
some instability in place. This will lead to the possibility of
thunderstorms and will increase the amount of rainfall possible.
As the boundary pushes through, the axis of heavy rainfall will
shift slightly to the southeast including some of the Cumberland 
Basin. The main impact from this rainfall will be to the Kentucky
River Basin as these areas will see rainfall totals around 2 to 3
inches. As the trough aloft deepens and begins to push through, it
will push the surface boundary through eastern Kentucky late
Monday night as temps across the area begin to plummet. With a
rather slow passage, the cold air will likely not be in time for
rain to change over to snow. Temps of 33 to 34 degrees seem to be
the lowest temperature across the area for Tuesday morning. Thus,
the only impact to the area will be rivers running high after the
rainfall ends. 

.LONG TERM...(Tuesday through Sunday)
Issued at 347 PM EST SUN DEC 15 2019

The models have maintained good agreement on a transition to more
of a progressive long wave pattern across the CONUS through the
period. The extended begins with a positively tilted trough
aligned from the upper Midwest down to the Desert Southwest. This
will gradually shift east, reaching east of the Appalachians by
late Wednesday. Short wave ridging will then will build in across
the Ohio and Tennessee valleys through Friday, before a short wave
trough cuts off somewhere near the Arklatex region by Saturday and
moves east along the northern Gulf of Mexico region through the
end of the weekend. 

Cold air advection will be ongoing across eastern Kentucky Tuesday
morning, as winds veer to the northwest behind a departing cold
front. Morning highs for most locations will range from the mid
30s to the northwest, to the mid 40s in the southeast. Rain will 
be exiting, with the models continuing to show only marginal ice 
following the front aloft. As such, have left out any snow 
mention, and any glazing potential along the higher elevations 
across southeastern Kentucky, would be limited to elevated 
surfaces, following a period of mild ground temperatures. 

High pressure will build in from the west and southwest Tuesday 
night, with temperatures dipping down into the low to mid 20s by
early Wednesday morning. Generally dry weather will be the rule
through the rest of the week, as the Gulf system looks to only
brush us from the south sometime on Saturday, although there are
decent timing differences between the ECMWF and GFS. Highs will
moderate from mid-week on, starting out in the 30s and 40s on
Wednesday, and then the upper 40s to lower 50s by the weekend. 

&&

.AVIATION...(For the 06Z TAFS through 06Z Monday night)
ISSUED AT 115 AM EST MON DEC 16 2019

A low level jet increases overhead through the night while 
moisture deepens leading to MVFR to IFR CIGs working in from north
to south with time into dawn. This jet will also lead to LLWS at 
most sites minus SYM through much of the night before relaxing 
towards dawn. This increase in moisture will also lead to periods
of light to moderate rain towards dawn and through the remainder 
of the TAF period. These periods of rain, occasionally heavy, will
also lead to MVFR to IFR, perhaps lower, VIS restrictions. The 
winds will mainly be out of the south at 5 to 10 knots through the
period.

&&

.JKL WATCHES/WARNINGS/ADVISORIES...
Flood Watch from 7 AM EST this morning through Tuesday morning 
for KYZ044-050>052-058>060-068-069-079-080-083>088-104-106>120.

&&

$$

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