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Area forecast discussion...updated 
National Weather Service Jackson Kentucky
1100 am EDT Sat Aug 1 2015

Update...
issued at 1100 am EDT Sat Aug 1 2015

Grids have been touched up based on recent observations and
trends. A weak moisture starved cold front is dropping south
across the region today and have little effect other than shift
winds to more of a northwest direction behind it as another surface
high builds in. This high will also keep dewpoints in the upper
50s to lower 60s range through tonight.

Update issued at 715 am EDT Sat Aug 1 2015

Touched up the grids per the latest observation and trends. These have
been sent to the ndfd and web servers.

&&

Short term...(today through sunday)
issued at 305 am EDT Sat Aug 1 2015

06z surface analysis shows that high pressure remains in control of
east Kentucky/S weather this early morning. This high has kept
cloud cover to a minimum and is supporting a decent ridge to
valley temperature split on the order of 5 to 10 degrees. At the
same time dewpoints are running in the lower 60s. As temperatures
continue to radiate lower for the rest of the night the dewpoints
will also creep down...but in the deeper valleys probably not fast
enough to prevent the development of fog...especially near rivers
and bodies of water. Winds will be light through dawn perhaps
contributing to the locally dense fog in the more sheltered River
Valley spots.

The models are in good agreement aloft with the longwave pattern
as they all depict a slowly deepening...large trough through the
northeast portion of the continent stretching south through the
Ohio Valley over the weekend. The northwest flow associated with
this will bring minor shortwaves over Kentucky during the period
but not much in the way of mesoscale amplification until perhaps
Sunday afternoon when a healthier one passes by to the north. The
NAM continues to be on the stronger side of the model spectrum
with the larger trough and this wave late in the period.
Accordingly...have gone with more of a model blend favoring a mix
of the European model (ecmwf) and GFS outside of the near term where the hrrr and
nam12 are reasonable.

Sensible weather will feature a very pleasant middle Summer weekend
as the afternoon warmth is kept comfortable by relatively low
humidities wrought by a midday and afternoon mix down of drier
air from the middle levels. This will keep cloud cover to a minimum
through the period and also lead to another night of good
radiational cooling for Sunday morning. Similarly...patchy fog
will likely be limited to the deeper River Valley locations both
this morning and Sunday morning...though locally dense pockets
will be possible as well.

Again used the shortblend model as a starting point for the
T/TD/wind grids through the day followed by the superblend into
Sunday. Did make some significant adjustments to temperatures
this morning and tonight with respect to ridge and valley
differences once...and as...the inversion is in place. As for
probability of precipitation...kept them low and in line with the drier met guidance.

Long term...(sunday night through friday)
issued at 358 am EDT Sat Aug 1 2015

The extended period begins with the upper level pattern featuring a
ridge over the western Continental U.S. And a trough over the east and a
closed low centered just south of the Hudson Bay area. This
pattern...though with some shifting of features each
day...remains in place for just about the entire extended. To
start the extended...a weak shortwave will pass through the lower
Great Lakes region bringing a surface cold front across northern
Kentucky and the chance for some afternoon showers and
thunderstorms. By Tuesday...a surface stationary boundary sets up
across southern Ohio...in...and Illinois allowing for a focus of shower
and thunderstorm development along northern Kentucky on Monday and
Tuesday.

Through the rest of the extended...the pattern in place will be
favorable for mesoscale convective system/S in this northwest flow. This holds true
through Tuesday and Thursday period. Have kept the suggested probability of precipitation
inherited by the super blend with instability and moisture in
place...this seems likely across eastern Kentucky...especially
with the inconsistency in the GFS and Euro. By the Wednesday
evening and Wednesday night period...a better complex is seems
poised to move into the area. However...as stated earlier...the GFS
and Euro have been inconsistent with the track and timing this
late in the extended as recent runs have the upper trough pushing
further south as well as the surface gradient. Overall...the day
5...6 and 7 period seems quite active and will keep the high
chance probability of precipitation advertised by the super blend.

&&

Aviation...(for the 12z tafs through 12z Sunday morning)
issued at 735 am EDT Sat Aug 1 2015

High pressure will keep VFR conditions in the taf forecast for
all sites through the period. Outside of the official taf
sites...patchy fog again will be found in the lower elevations
towards dawn Sunday morning...perhaps becoming locally dense for
a brief time. Winds through the period will be light and variable.



&&

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

$$

Update...jp
short term...greif
long term...shallenberger
aviation...greif

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