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Area forecast discussion 
National Weather Service Jackson Kentucky
153 am EDT Wednesday may 6 2015

Update...
issued at 1015 PM EDT Tuesday may 5 2015

The stray light showers dissipated by sunset and skies are
generally clear or mostly clear across the region. High pressure
at the surface and middle levels will dominate for the remainder of the
night...with a Ridge/ Valley temperature split and patchy fog
forming again in some valley locations. Hourly temperatures have
been freshened up to account for the decoupling and faster drop in
temperatures in Eastern Valley locations so far.

Update issued at 620 PM EDT Tuesday may 5 2015

A few rather shallow showers have managed to develop from the cumulus
across locations near the Virginia border generally a few miles north of
Pine Mountain and over the northern extent of the Cumberland Plateau
into McCreary County. These should diminish before sunset as they
will experience loss of daytime heating...with cumulus also expected
to dissipate about that time. Surface high pressure should be the
dominant weather feature tonight as the area remains south of the
nearly west to east oriented frontal zone located south of the Great
Lakes. Another at least small to moderate Ridge/Valley temperature
split is anticipated tonight along with some patchy valley fog.
Temperatures for a few Eastern Valley locations have been adjusted
down a couple of degrees based on trends from recent nights.

&&

Short term...(this evening through Wednesday night)
issued at 330 PM EDT Tuesday may 5 2015

Surface high pressure centered over southeast Kentucky will
remain in place for the next few days. This will result in a
mostly dry forecast for the short term. Models continue to
indicate a few isolated showers/storms may be possible during the
afternoon/evening hours tomorrow. But if today is any
indication...showers/storms should be subdued...especially with
the lack of moisture in place. However...to be consistent...kept
slight chances of showers with isolated storms in the grids for
tomorrow afternoon.

Temperatures should generally reach the low to middle 80s tomorrow
afternoon...with highs reaching a degree or two above todays peak
temperatures. Due to strong radiational cooling...lows will dip
into the middle 50s in the valleys and near 60 on the ridges...with
similar lows on Thursday morning.

Long term...(thursday through tuesday)
issued at 220 PM EDT Tuesday may 5 2015

The models are in good agreement aloft through the bulk of the
extended forecast. They all depict a moderately strong ridge
dominating the eastern portion of the nation well into the weekend.
However...there also is an undercutting weakness off the southeast
coast of the nation at middle levels that could lead to some
interesting weather there by the weekend. The dirty ridge will likely not
be strong enough to cap all convection through east Kentucky at peak
heating each afternoon...but chances at any one location will be
rather low. Better upper support for convection will arrive late in
the weekend as the ridge starts to break down from the northwest in
response to a trough moving east into the High Plains with rogue
bits of energy breaking off and running through the Ohio Valley in
southwest flow. This trough will slip into the Mississippi Valley
region and the Midwest later Monday with height falls impacting
Kentucky while additional energy tracks over the area. The trough
does move more completely into the Ohio Valley and Great Lakes on
Tuesday with some significant height falls prognosticated...by the European model (ecmwf) in
particular...to affect east Kentucky by Tuesday evening. A general
model blend is accepted for the bulk of the long term portion of the
forecast given the agreement early on and as a means of mitigating
the uncertainty heading into the start of next week. Did side more
with the drier European model (ecmwf) for probability of precipitation each period.

Sensible weather will feature an early Summer-like pattern beneath
the upper ridge and a weak surface high. There will be no driving factor
for convection through the weekend aside from differential heating
and minor terrain enhancement. Accordingly...with rather dry air in
place beneath the surface high...will keep any small chances for
convection limited to the higher terrain in the far southeast and
only at or just after peak heating. Each night skies should clear
following the afternoon/S diurnally driven cumulus development with mild
ridge top temperatures and cooler valleys. In fact...a moderate to
large ridge to valley split in the temperatures is expected each
night in this pattern...through the weekend. By Sunday afternoon...
the middle level energy and a surface low moving into the Central Plains
may be enough for convection to move into our western zones. Monday
will also see a potential for diurnally driven convection by late
afternoon...but the best chances for more widespread convection
looks to hold off until Tuesday when the surface low moves into the Ohio
Valley and its cold front crosses Kentucky. The increase in clouds
and better precipitation chances for the start of next week will also result
in cooler temperatures than we will see for the rest of this week and into
the weekend.

The CR grid blend came in on the wet side for most periods so have
adjusted the probability of precipitation down based more on the European model (ecmwf) and the diurnal cycle
through Monday. Did also make some rather large changes to lows each
night given the terrain and anticipated strong inversions. Monday
night should see a more mixed air mass...especially in the western
parts of the County Warning Area.

&&

Aviation...(for the 06z tafs through 06z Wednesday night)
issued at 152 am EDT Wednesday may 6 2015

High pressure at the surface and aloft should bring VFR conditions
through the period. Winds should generally be light and variable
and remain below 10 kts. Areas of valley fog in some River Valley
locations are possible late tonight...but the taf sites should not
be affected. Cumulus development in the 5 to 7k feet range is possible
once more this afternoon...with some isolated light shower
chances in the far southeast portion of the state. Expect taf sites will
remain dry. Skies will clear out once more by tomorrow evening.

&&

Jkl watches/warnings/advisories...
none.
&&

$$

Update...jp
short term...jvm
long term...greif
aviation...jmw

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