Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Jackson Kentucky
647 am EDT Monday Sep 1 2014
issued at 647 am EDT Monday Sep 1 2014
Cloud cover has expanded a bit from earlier...so have adjusted the
sky cover to reflect cloudier skies through daybreak. Also adjusted
temperatures up a few degrees across the board as the clouds are
holding temperatures up mainly in the low 70s. Hrrr continues to
paint out some isolated to scattered showers and storms this
afternoon...and the 06z NAM has also now supporting a few showers and
storms. Thus it does look like some activity can be expected by the
Short term...(today through tuesday)
issued at 331 am EDT Monday Sep 1 2014
Zonal flow resides across Kentucky this morning...with a shortwave
trough pushing across the northern plains. The zonal flow for today
will mean a quieter day. However...a subtle upper level wave will
push across Central/Northeast Kentucky this afternoon and evening.
While operational guidance suggests very little if any precipitation
today...hi res models have been consistent on showing isolated to
scattered convection developing today. The model guidance doesn't
seem to match up to what the hi res models are showing. Given the
recent history of hi res models doing fairly well with
convection...have opted to go with isolated to scattered showers and
storms this afternoon with the highest corridor of probability of precipitation from south
central Kentucky...into northern and northeast Kentucky.
However...cannot rule out a few isolated showers or storms developing
on the higher terrain to the southeast. With modest precipitable waters around 1.7
and very high freezing levels (>15kft) potential may exists for some
periods of very heavy rain. Fortunately...storm movement should be
sufficient to limit any flooding concerns today.
The showers/storms today will be tied to the peak instability hours
from middle afternoon to early evening...before dying off. This will
yield a quite night across the area today. Clearing skies could yield
some patchy fog...but we may keep enough wind again to limit it to
some degree. The shortwave trough over the northern plains will send
a weak cold front into the Ohio River valley region. This will spark
scattered to numerous showers and thunderstorms to develop on
Tuesday. These will track southeast across eastern Kentucky through
the afternoon and evening hours. With modest 30-40kt bulk shear
values...the potential will exists for some linear storm segments
capable of damaging winds. Plan to continue to highlight this
potential in the severe weather potential statement. The front will wash out and stall over southern
Kentucky by the evening hours with activity dying out with the loss
of daytime heating.
Long term...(tuesday night through sunday)
issued at 410 am EDT Monday Sep 1 2014
Warm weather is expected to continue into the extended period. The
extended period of the forecast will begin with the trough in the
near term departing to the north and east...with a rather zonal
pattern to start overall. The near term cold front is expected to
be dropping or have dropped across the region at the start of the
period...from Tuesday night into early on Wednesday and bring isolated to
scattered convection. The boundary should become more ill defined and
rather washed out on Wednesday as it reaches the Tennessee Valley region.
With the boundary in the area...convection will remain possible
mainly across the south and southeast on Wednesday. Middle and upper
level ridging is then expected to briefly amplify across the
southeastern and Middle Atlantic States through Friday.
As the ridge builds and a shortwave trough or two in the zonal flow
moves from the Central Plains toward the lower Ohio Valley region and
into the middle Ohio Valley region...what is left of the boundary and
deeper moisture should also begin to retreat back into the region by
Wednesday night into Thursday. This should lead to an additional period where
convection is possible. The model consensus is for the ridge to
build in behind this shortwave for Thursday night and into early on Friday.
Overall...convection from Thursday night into Friday may have somewhat of
a diurnal flavor.
Also during this time...a series of troughs will traverse the
northern stream and send a cold front south into and gradually across
the the lower Ohio Valley region and eastern Kentucky this weekend.
This will bring period of unsettled weather...with prolonged chances
for showers and thunderstorms from Saturday into Sunday.
Temperatures are expected to average near to a few degrees above
normal from Wednesday into Saturday for daytime highs...with overnight low
having the greater departure of nearly 5 degrees on average.
Aviation...(for the 12z tafs through 12z Tuesday morning)
issued at 647 am EDT Monday Sep 1 2014
Low clouds have developed and spread across much of eastern Kentucky
this morning. For the most part...MVFR ceilings are being reported.
However...a few spots in the north may be down to IFR ceilings. We should
see gradual improvement through the morning hours before VFR
conditions return by midday. Isolated to scattered showers and storms
still look like a possibility this afternoon...but no enough coverage
or confidence to include in the tafs. VFR conditions look to continue
through tonight with only some very patchy valley fog. At this
time...this is not expected to impact the taf sites tonight.