Area Forecast Discussion
Issued by NWS Jackson, KY

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS63 KJKL 241835
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
235 PM EDT Mon Jul 24 2017

.UPDATE...
Issued at 235 PM EDT MON JUL 24 2017

Showers and t`storms are developing just about on schedule.
Coverage is still fairly limited, and the POP has been left at 20%
at this point.

UPDATE Issued at 1059 AM EDT MON JUL 24 2017

Have updated POP/wx grids based on latest mesoscale model runs.
They all focus the potential for convection this afternoon into
tonight along the cold front dropping south through the area. There
is uncertainty regarding coverage and how effectively a mid level
cap can be broken. MOS POPs from last night`s runs are all sub
20%. Have left the POP low at this point, but if enough
development occurs, a revision would be necessary.

UPDATE Issued at 645 AM EDT MON JUL 24 2017

Did a quick update to the grids to fine tune the sky cover and
tweak the T/Td grids per the latest obs and trends. Patchy fog has
developed along the fringes of the clouds currently bisecting the
CWA - but any dense fog has so far been fleeting per the obs and
web cams. These updated grids have been sent to the NDFD and web
servers.

&&

.SHORT TERM...(Today through Tuesday)
Issued at 340 AM EDT MON JUL 24 2017

07z sfc analysis shows weak high pressure now settling into
Kentucky with a washed out front lying over the southern parts of
the state. This boundary is keeping clouds through the southern
half of the CWA limiting the fog potential down there despite the
minimal dewpoint depression. To the north, a bit more of spread
to the temperatures and dewpoints are also serving to keep fog to
a minimum ATTM. Readings are fairly uniform through the area -
generally in the upper 60s to lower 70s with dewpoints in the
upper 60s most places while winds area light, mainly from the
southwest.

The models are in good agreement aloft in the wake of the stronger
shortwave exiting the Ohio Valley to the east early this morning.
They all depict northwest flow continuing as low heights curl
east through the eastern Great Lakes with ridging found to the
southwest. This ridging starts to build back east through Tuesday
with heights rising and any energy packets coming through the
region weaker and weaker. Given the model agreement will favor a
general blend with particular attention to the HRRR and NAM12
solutions in the near term.

Sensible weather will feature another warm day, though not quite
as humid as heat indices peak in the mid to upper 90s. The weak
front nearby will be the potential source for storm development
by mid day, but the models are not very impressive so have kept
the PoPs in the chance category. Drier air will continue to seep
into the area at all levels also limiting the storm potential and
certainly concerns for excessive rainfall. This is due to lower PW
air for most of the CWA now that the deeper moisture has pushed
off to the south. For tonight, will have to be on the lookout for
low stratus to develop along with fog, but otherwise it will be a
quiet night in a rising heights environment. Similarly, Tuesday
looks dry and warm with partly sunny conditions and minimal storm
chances as a deep cap develops while the mid level ridge spreads
northeast into the region.

Again used the CONSShort as the start for the forecast grids with
only minor point adjustments to lows and highs. Did adjust PoPs
today to better align with the front and HRRR QPF depictions.

.LONG TERM...(Tuesday night through Sunday)
Issued at 245 AM EDT MON JUL 24 2017

The extended period will start off warm and dry as a ridge of high
pressure settles over the region. Normal to slightly above normal
temperatures will accompany light and variable winds Tuesday night
through Thursday. After that, however, a slow moving frontal
boundary will invade the area from the north. This boundary will
bring chances for rain to eastern Kentucky from Thursday morning
through Saturday. The highest probability for rain will likely occur
Thursday night and Friday, as a cold front moves slowly across the
area. The rain should taper off during the day on Saturday, as the
front begins to exit the area. Isolated to scattered showers and
storms are expected to linger across our eastern and southern
counties through Sunday evening, as the front stalls out just to the
south of the area, and an wave of low pressure aloft moves across
the eastern Great Lakes region. Temperatures from Friday onward are
expected to be below normal, due to persistent cloud cover and
precipitation. Highs from Friday through Sunday will max out in the
lower 80s across the area, while max values on Wednesday and
Thursday should be in the upper 80s. Nightly low will be in the 60s,
with the warmest nights at the start of the period, and the coolest
nights from Thursday night onward.

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
ISSUED AT 235 PM EDT MON JUL 24 2017

Isolated showers and t`storms were occurring over the northern
half of the forecast area at the start of the period. Outside of
the heavier precip, conditions were VFR. The precip was occurring
near a cold front. The front and the precip will slowly sink south
through the area this afternoon and evening. Precip coverage
should remain sparse enough so that nothing more than VCSH or VCTS
is warranted in the TAFs. Even though the front will drop to our
south tonight, the influx of drier air will be relatively weak.
This will make it difficult to scour out our humid air, especially
in valleys. The end result will be fog developing in valleys. The
issue is how far it spreads in breadth and depth. The current
forecast takes most of the area to IFR or lower. The places most
likely to avoid it will be on ridges and in the far north. Fog and
low clouds will eventually dry up on Tuesday morning, with VFR
expected by the end of the period.

&&

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

$$

UPDATE...HAL
SHORT TERM...GREIF
LONG TERM...AR
AVIATION...HAL


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.