Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 200303 AAA

National Weather Service Jackson KY
1103 PM EDT Tue Mar 19 2019

Issued at 1103 PM EDT TUE MAR 19 2019

Forecast lows still look reasonable at this point. The typically
cooler sites are currently reporting in the lower to mid 30s,
while broad valleys and ridgetops are in the upper 30s and lower
40s. Freshened up the hourly temperatures through the rest of the
night, with the coldest readings likely dipping into the mid 20s,
while other places bottom out in the upper 20s to lower 30s.
Updates have been sent.

UPDATE Issued at 746 PM EDT TUE MAR 19 2019

Mainly thin high clouds are advecting in from the west this
evening. This will continue through the overnight, gradually
becoming thicker and lowering somewhat with time. The more
prevalent cloud cover will occur north of the Hal Rogers Parkway
and Highway 80 corridors. The valleys have already begun
decoupling this evening, with the cooler spots already reporting
in the mid 40s. Forecast lows look reasonable thus far, as the
next few hours will be more telling if any adjustments will be
needed. For now, mainly freshened up the diurnal drop off through
this evening. Updates will be out shortly.


.SHORT TERM...(This evening through Wednesday night)
Issued at 417 PM EDT TUE MAR 19 2019

As of mid afternoon, the region was under the influence of high
pressure at the surface and aloft. Upstream of the region, an
upper level low was moving through the Central Plains region.
Another shortwave trough was moving into northwest Ontario. Mainly
a few high clouds were moving across the region at this time.
Dewpoints were generally in the upper teens to low 20s while
temperatures were in the low to mid 50s. Current RH across the
area is in the 23 to 33 percent range though winds are generally
light and variable.

The axis of the sfc high will gradually move south and east of
the area tonight into early on Wednesday. High level moisture will
increase with mid level moisture increasing late tonight and into
the day on Wednesday. At the same time, the shortwave trough
initially in the Plains will approach the mid MS Valley while the
more northern shortwave trough moves into the northern Great
Lakes. These shortwaves will interact and may begin to phase late
on Wednesday into Wednesday night. Meanwhile, a surface low will
track into the OH Valley by around sunset on Wednesday, though
another front associated with the shortwave moving through the
Great Lakes will become the primary front and approach the area
late in the period.

High pressure will remain dominant tonight and as low level winds
become more east to southeast, another potentially larger ridge/
valley temperature split is anticipated. Ridges should bottom out
near the freezing mark with valleys which decouple during the
evening bottoming out in the mid to upper 20s. As the surface
high moves east of the area Wednesday and the surface system
begins to approach winds should become more south to south
southwest by midday on Wednesday, as high as 5 to 10 mph. Some
higher gusts near 15 mph will be possible. Dewpoints at the
surface will be a bit slow to increase, ranging in the mid 20s to
lower 30s on Wednesday afternoon with temperatures peaking in the
upper 50s to near 60. This should lead to RH bottoming out as low
as 23 to 25 percent nearer to the WV border. However, as noted,
winds should generally be light.

Precipitation chances will hold off until Wednesday night.
Moisture return and forcing will be best across the west and
northwest portion of the area on Wednesday night where likely pops
were used. The highest precipitation chances across the far
southeast will be near the end of the period.

.LONG TERM...(Thursday through Tuesday)
Issued at 320 PM EDT TUE MAR 19 2019

A weak cold front will be making its way across the CWA Thursday
morning, exiting by the early afternoon. This will result in light
rain spreading across the CWA throughout the morning, and exiting as
drier air filters in during the afternoon. A fairly deep shortwave
will remain in place aloft throughout the day Thursday with
northerly flow ushering in a colder airmass into the region. A
secondary shortwave and a reinforcing cold front will pass through
on Friday, but this should be a dry front, with no impacts to the
weather. Daytime highs will be 5 to 10 degrees below normal. Skies
will clear by Thursday night, and will remain clear for Friday night
as well. With maximum radiational cooling, temperatures will fall
into the 20s for Friday night, coldest in the valleys.

The troughing in place will finally shift eastward as we head into
the weekend, with ridging taking hold. Surface high pressure will
also be in place throughout the weekend, moving east of the region
by Sunday. This will induce return flow and help boost temps into
the low to mid 60s for highs on Sunday. Southerly flow will
continue as an area of low pressure approaches from the west. This
will combine with a cold front sinking southward towards the
state as well, traversing the CWA during the day Monday. Precip
will accompany this system as well, with decent agreement between
the GFS and ECMWF on the timing and expanse of the QPF as it moves
across the CWA Monday morning and continues through the day.
Northerly winds behind this system will advect colder air into the
region, and may result in a rain/snow mix over at least the
northern portion of the CWA Monday night.


.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)

High pressure will gradually retreat off to the east through the
period, with the next weather system approaching from the west by
Wednesday night. VFR conditions will hold on through the period,
as mainly an increase in high and some mid-level clouds will occur
out ahead of the next approaching system. Winds will be light through
Wednesday morning, before becoming more southwesterly at 5 to 10
kts by the afternoon.




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