Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 190356 AAB
AFDJKL

AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
1056 PM EST Sat Feb 18 2017

.UPDATE...
Issued at 1055 PM EST SAT FEB 18 2017

Recent radar imagery indicates that most of the scattered light showers
have dissipated or moved to the east of the area. However, some
light drizzle or very light rain appears to be lingering
generally east of Interstate 75 while the band of steadier light
rain is sinking into the northern part of the area. Scattered pops
have been continued for the next few hours with a decrease in pops
toward dawn dawn as the upper level shortwave departs. Patchy
stratus build down fog continues to reported in some locations
generally ridgetops and as the low levels cool and saturate
further in some cases, patchy fog is expected overnight. Hourly
temperature and dewpoint grids have been updated based on recent
observation trends though no substantial changes were needed at
this time.

UPDATE Issued at 750 PM EST SAT FEB 18 2017

An upper level is moving across the OH and TN Valley Regions. This
system has brought generally light rain and showers to the area
with some of these rotating across the area at this time. Some
steadier light rain has fallen across Fleming County and areas
closer to the OH River. Rainfall has been light, generally a
tenth of an inch or less. Scattered light showers will continue
through the evening and into the overnight as the upper system
moves across the area and the band to the north of the area or
what is left of it drops into the region. Some stratus build down
is possible as the lower levels saturate and some patchy fog may
develop late this evening and into the overnight hours especially
on the ridges. Hourly grids have been freshened up based on recent
observations and trends.

&&

.SHORT TERM...(This evening through Sunday night)
Issued at 255 PM EST SAT FEB 18 2017

Current conditions across the area feature an area of rainfall
shifting northeast from the southwest as a surface low pressure
area develops over central TN shifting a northeast to east
direction. North of the low, a banded area of rainfall has
developed over northern Kentucky and will be moving eastward
setting up over locations in eastern Kentucky just north of the
Mountain Parkway. This setup should bring an end to significant
rainfall in the south and southeast as the bulk of the rainfall
will fall in the vicinity of the developed band across northern
Kentucky.

As this feature exits to the east tonight some lingering light
rainfall will provide another couple hundredths before exiting by
06Z. Despite the saturated grounds, lingering low level cloud
cover will keep from any fog development late tonight. This
feature having no real cold air push, the bulk of the moisture and
low level cloud cover will experience some difficulty getting
scoured out of the eastern Kentucky terrain and it being late
February with still a some low sun angle wont help out either. So,
will see this cloud cover stick around till late morning before
breaking up. Still though, with a more warmer flow in place, temps
will rebound to near or above 60 degrees tomorrow.

By Sunday night, with ridging becoming well entrenched over the
area, relatively mostly clear skies will be in place. With enough
saturation to the ground today and tonight, Sunday night, with
good subsidence in place and light winds will set the stage for
some fog development. If we clear out any more for tomorrow night,
the fog will be more dense in places as well as a steeper ridge to
valley temperature gradient for that matter.

.LONG TERM...(Monday through Saturday)
Issued at 310 PM EST SAT FEB 18 2017

The models are in decent agreement aloft through the mid part of the
extended forecast. They all depict a sharp ridge passing through the
area on Monday ahead of a full latitude trough extending from the
Northern Plains south to Central Mexico. This system then splits
Monday night with the northern stream part flowing into the Great
Lakes while the southern portion closes off over the western Gulf
of Mexico by midday Tuesday. The GFS and ECMWF are now closer with
this evolution, though the EC is still stronger - while the
Canadian is far off in the weakness of its trough in the southern
region. The dissipation of the northern trough will send a band of
weakening energy through Kentucky later Tuesday. Following this,
flat ridging returns to the region north of the Gulf low and south
of faster northern stream flow. Discounting the Canadian, the
models are not too far off over Kentucky through the rest of the
work week as they maintain the gentle ridge overhead for the
Bluegrass State while weak energy packets move through. Next up a
low will grind through the Upper Midwest and strengthen pumping
the ridge over our area on Friday before southwest flow kicks in
and heights drop by that evening. The core of the energy will pass
by to the north later that night - a tad quicker in the GFS than
the ECMWF. Given the agreement early and some separation later in
the period will favor a blended solution for the extended grids.

Sensible weather will feature very warm temperatures for the area
through Friday before a step back into the 40s occurs Saturday
post frontal. Rain chances arrive on Tuesday afternoon and night
as a dying cold front passes through the region. After a lull the
PoPs will pick up again on Thursday into Friday with a developing
area of low pressure over the Central Plains and a frontal
structure setting up north of the state. This will keep Kentucky
in the warm sector with convection anticipated, though thunder
chances are still too uncertain to place in the forecast - even as
the system`s cold front crosses later Friday. Some upslope flow
and wrap around moisture may trigger a few snow showers that night
into Saturday morning but amounts look to be in the trace
category - with high pressure building in on Saturday and drying
us back out.

Again made some small to moderate adjustments, early on and then
late in the week, to the temperatures at night for some ridge to
valley distinctions. As for PoPs, basically tightened them up a bit
with the weak cold front - and behind it - passing through Tuesday
night.

&&

.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
ISSUED AT 739 PM EST SAT FEB 18 2017

MVFR has developed across the southwest part of the area and as
bands of showers rotate east and northeast across the area as an
upper level system approaches. The low levels are becoming
saturated and further deterioration to MVFR is expected in all
locations through 5Z. At least patchy IFR should begin to develop
during that time with stratus build down, first south and east of
the TAF sites and then affect the far north and many of the
ridgetops by 9Z as the build down becomes more widespread. MVFR
vis is also possible in showers and in patchy light fog as the
stratus builds down. These cigs and or vis should persist through
about 15Z, before a gradual improvement to VFR by the end of the
period. Winds should remain light through the period.

&&

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

$$

UPDATE...JP
SHORT TERM...SHALLENBERGER
LONG TERM...GREIF
AVIATION...JP



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