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Area Forecast Discussion (AFD)

Issued by Jackson, KY (JKL)

FXUS63 KJKL 212038

National Weather Service Jackson KY
438 PM EDT Thu Mar 21 2019

.SHORT TERM...(This evening through Friday night)
Issued at 436 PM EDT THU MAR 21 2019

An upper level low is moving through Central and into Eastern KY 
this afternoon. Numerous showers have been moving across the 
area. Lapse rates are sufficiently steep that there have been a 
few thunderstorms and even a few showers some with small hail this
afternoon. Meanwhile another upper level low was centered near 
the James Bay Region. Temperatures on Black Mountain have been 
down as low as 32 degrees this afternoon on wetbulbing and most 
recently at 34. This illustrates how low the freezing levels are 
this afternoon as the upper low moves in and the associated colder
air aloft.

The upper level low will move across the region this evening
taking deeper moisture with it while the upstream upper level low
rotates into the Great Lakes region. This will keep the region in
NW to WNW flow aloft through tonight and into the day on Friday. 
This upper level low will then merge with and then gradually phase
with the preceding one. The combined upper level low should track
the Canadian Maritimes by the end of the period. Once the second 
upper level low rotates into the mid Atlantic states on Friday 
evening, height rises are expected to end the period. 

Showers and even an isolated thunderstorm or two, some with small
hail will remain possible through around 6 PM EDT. However, once
we progress further past peak heating and the upper level low
moves overhead and deeper moisture lessens, showers should
diminish. Upslope flow and some limited moisture should lead to a
few showers, possibly mixed rain and snow in the highest
elevations lingering into the evening if not the overnight in the
far southeast. Additional sprinkles or light rain showers are
possible, mainly near the WV border as the second upper level
system moves from the Great Lakes into the mid Atlantic states on
Friday. Then, as high pressure builds in late in the period,
fairly widespread frost is expected although the growing season
has in East KY.

With the northwest flow aloft followed by high pressure building
in, temperatures will be below normal on average through Friday

.LONG TERM...(Saturday through Thursday)
Issued at 352 PM EDT THU MAR 21 2019

Brief ridging aloft will be moving into place for Saturday and 
Saturday night, with mostly clear skies and quiet weather. Clouds 
and temperatures will be on the increase throughout the day Sunday 
as a cold front drops south towards the state from the north, and an 
area of low pressure approaches the state from the SW. Temperatures 
will reach the low to mid 60s for the day Sunday. These two systems 
will then combine to produce rainfall across the region, moving into 
eastern KY Sunday afternoon. Will note, however,that there is quite 
a bit of discrepancy between the models on the exact timing and 
placement as this rain moves in. Regardless, widespread rainfall 
will overspread the CWA during the day Monday. There may be enough 
lift along the boundary and near the low center to induce some 
thunder, so did add mention of thunder in grids for the day Monday 
as well. Temperatures will reach the mid 50s to near 60 for highs. 

The system will shift south of the state by Tuesday morning, with 
rain dissipating accordingly and colder air moving in. Highs on 
Tuesday will be much cooler, in the upper 40s and low 50s. Heights 
will then begin rising again as we head into Wednesday, with high 
pressure taking hold at the surface Tuesday night and Wednesday and 
an increasing temperature trend once more. Most nights throughout 
the extended will see temperatures fall to freezing or just below, 
especially in the deeper valleys. This may lead to some frost 
production. The caveat will be Sunday night into Monday morning 
where the warm air advection/southerly flow will keep temps in the 
mid and upper 40s . 


.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)

A mixture of VFR and MVFR CIGS and or vis are expected this
afternoon as showers and a few isolated thunderstorms move east
as a cold front and upper level disturbance work through the
region. Confidence in thunder affecting any terminal was not high
enough to include at this time. in addition to the showers and
storms, some gusts up to 20kt will be possible through at least
0Z. However, MVFR should return for portions of the overnight. 
West to northwest winds are expected generally at 5 to 10K through
the end of the period, although they should increase toward 10KT
with gusts around 20KT late.