Area Forecast Discussion
Issued by NWS Jackson, KY
FXUS63 KJKL 010054 AAA
AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
854 PM EDT Fri Sep 30 2016
Issued at 840 PM EDT FRI SEP 30 2016
An upper level low continues to spin over the OH Valley region.
However, significant breaks have developed across East TN north
into Eastern KY. This has allowed for some valley temperatures to
drop into the lower 50s. Only some minor adjustments were made
based on recent observations. The main changes were to the hourly
temperatures for valley locations over the next few hours.
.SHORT TERM...(This evening through Saturday night)
Issued at 340 PM EDT FRI SEP 30 2016
18z sfc analysis shows a broad area of low pressure through the
Ohio Valley and Southern Appalachians. Most of East Kentucky is in
the southwest quadrant of this system and pretty much dry slotted
keeping the showers and any storms west and northeast of the CWA.
Plenty of clouds and morning fog slowed the temperature rise
through eastern Kentucky today, but with more clear breaks the
sunshine is helping to send temperatures into the low and mid 60s.
Meanwhile, dewpoints are running in the low 50s for most places
with the winds light and variable.
The models are in good agreement aloft with their handling of the
fairly deep closed low wobbling over the Ohio Valley through the
weekend. They all have the low tracking slowly due north with some
minor divergence in solutions late in the short term. The GFS
moves the low to the Great Lakes a notch quicker than the others,
but strength is similar from all models. They all, also, have
ample mid level energy rotating through the low over head. Given
the agreement will favor a blended solution with the HRRR and
NAM12 leaned toward in the near term.
Sensible weather will feature another cool evening and overnight
as the clouds partially break up. This will make for varying
amounts of radiational cooling and better radiational fog
formation at times overnight. The latest CONSShort guidance keeps
the more extensive and thickest fog just to the west of the CWA
tonight. For this reason, will allow some mainly valley fog in
the grids toward midnight and through dawn with some locally dense
patches in the deeper valleys toward 12z. The next pinwheel of
energy aloft may bring some light showers to western parts of the
CWA overnight and into Saturday morning, but most of the area
should remain dry. Look for the fog to burn off Saturday morning
and a bit more sunshine should allow for temps to reach the upper
60s to low 70s most places. Similar conditions are anticipated
Saturday night with more valley centric patchy fog late. Also,
a couple stray showers may move in late Saturday into Sunday
morning as the upper low and sfc low start to move out.
Again used the CONSShort and ShortBlend as a starting point for
most grids into Saturday morning with the SuperBlend used
thereafter. Made only minor changes to the T grids based on our
terrain with the clouds around. As for PoPs - ended up on the low
side of a MOS blend through Sunday morning.
.LONG TERM...(Sunday through Friday)
Issued at 248 PM EDT FRI SEP 30 2016
The forecast for the extended should feature isolated rain showers
moving across eastern Kentucky, as an area of low pressure aloft
moves across the lower Ohio Valley region on Sunday, a period of dry
and pleasant weather, and possibly another round of rain Thursday
night into early Friday. A cold front would be the trigger for any
rain we may see toward the end of next week. Temperatures during the
period are expected to max out in the 70s each afternoon, and bottom
out in the 50s each night. A few spots may reach or slightly exceed
80 degrees Tuesday through Thursday, mainly along and south of the
Hal Rogers Parkway and Highway 80 corridor.
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
ISSUED AT 830 PM EDT FRI SEP 30 2016
An upper level low continues to meander across the Lower OH
Valley. This will lead to band of clouds through the period and
the threat of mainly diurnally driven isolated showers. The degree
of clearing remains uncertain, but at least some dense valley fog
is anticipated. However, confidence in the location and duration
of cloud cover is not high at this time. At this time, the TAF
sites are still expected to be limited to mainly MVFR vis
restrictions for a few hours between 8z and 13z. Mainly vfr
should then prevail through the end of the period with the
exception of brief mvfr possible in any isolated showers. Winds
will remain light and variable through the period.