Area forecast discussion
National Weather Service Jackson Kentucky
319 am EDT Friday may 24 2013
Short term...(today through saturday)
issued at 257 am EDT Friday may 24 2013
Scattered showers associated with a cold front were ongoing over the
southeast part of the forecast area early this morning. They are
expected to be gone by 12z...but a pre-first period may be needed in
the zone forecast product to cover them. Otherwise...a dry period is in store.
Cool high pressure slowly building southeast into the area will bring
decreasing clouds today...and mainly clear skies tonight. Dew points
are expected to fall to the lower to middle 30s this afternoon...with
daytime mixing in the cool air mass only allowing maximum temperatures in the
middle 60s. With winds dying off tonight...temperatures should readily drop.
With full vegetation in place...a significant dew point recovery
should occur where full wind decoupling occurs in valleys. This will
set up a battle between fog and frost tonight as temperatures fall and
depress the dew points. It is climatologically very late for
frost...and do not think it will be widespread. Fog is likely to win
out in most locations. However...think that some patchy frost will
occur. With the growing season in full swing...will issue an Special Weather Statement for
patchy frost...emphasizing the need for plant protection in the
normally colder valleys.
The surface ridge of high pressure will continue to dominate our
weather Saturday. However...warm air advection will lead to precipitation
over the Midwest tonight and Saturday...with high clouds streaming
off this activity and heading southeast over our area. This will
bring an increase in middle-upper level clouds for Saturday.
Long term...(saturday night through thursday)
issued at 319 am EDT Friday may 24 2013
The models were in fair agreement at best for the beginning of the
extended period. The GFS...ECMWF...sref...and nam12 all were
producing some sort of warm frontal boundary or surface trough to
start the period. Each model produced isolated rain shower activity
Saturday night and Sunday as the aforementioned boundary moved across
the Ohio Valley region. The issue here was with the timing and
coverage differences amongst the various models. With slight chance
probability of precipitation showing up in the latest HPC and mexmos guidance...decided to go
with slight chance of rain showers from early Sunday morning through
Monday morning. With little if any instability showing up in the
model soundings and with only minimal lift along the anticipated
frontal boundary...went with general rain showers through Monday
morning. The soundings then produced a bit more instability from late
Monday morning through the end of the day on Tuesday...which would
likely be enough to spark a thunderstorm during that time. The models
then all agree that the aformentioned front boundary/trough will
move east of the area by 0z Wednesday...with high pressure settling
over the Ohio and Tennessee Valley regions for the remainder of the
week. With good model consensus on this point...decided to keep the
forecast dry from Wednesday Onward with partly cloudy skies and light
winds. Temperatures during the period will start out slightly below
normal...as a particularly cool air mass is expected to settle over
the area Friday and Saturday night. Highs on Sunday will top out in
the low 70s across the area. After that...temperatures will warm to
at or above normal values...as southerly winds become established
across the area. Highs Tuesday through Thursday will likely warm to
well above normal values...as a large ridge of high pressure settles
over the area and strengthens over time. Highs in the low to middle 80s
will be a good bet from middle week Onward.
&&
Aviation...(for the 06z tafs through 06z Friday night)
issued at 152 am EDT Friday may 24 2013
Conditions were largely MVFR region wide at the start of the
period...with scattered showers over the southeast part of the area.
The showers will continue to diminish and move southeast overnight...
and should be finished by 12z...but MVFR ceilings are expected to
persist a while longer for most locations. The ceilings should break
up during the morning...leaving VFR for the afternoon and evening.
&&
Jkl watches/warnings/advisories...
none.
&&
$$
Short term...hal
long term...Arkansas
aviation...hal
