Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Jackson Kentucky
1032 PM EDT Tuesday Oct 13 2015
issued at 1029 PM EDT Tuesday Oct 13 2015
Scattered to broken ceilings continue to cover a good portion of eastern
Kentucky...but are showing signs of erosion and eastward movement
according to the latest observation and infrared satellite imagery. Expect
these clouds to continue to erode away over the next few hours.
Temperatures are reading slightly higher than originally
forecasted due to the continued cloud cover...however expect them
to quickly drop off as the clouds begin eroding away. As
such...updated the next few hours Worth of grids to make sure the
current observations were reflected as were the faster drop offs.
Update issued at 729 PM EDT Tuesday Oct 13 2015
Forecast seems to be well on track at this time. Only needed a few
minor tweaks for the near term temperatures...dew points...winds...and
sky cover to make sure they reflected the ongoing conditions. Any
changes were published and sent to the web and ndfd. A new severe weather potential statement was
sent out simply to remove the afternoon wording in the headline.
No new zone forecast product is needed at this time.
Short term...(this evening through Wednesday night)
issued at 304 PM EDT Tuesday Oct 13 2015
Fair and cool weather will persist through the period...as high
pressure builds in from the northwest and centers itself over our
region by late Wednesday night. Stratocu will persist into
tonight...especially in our NE counties...but should largely
dissipate by Wednesday morning. This will leave very few clouds
for the remainder of the period. With drier air continuing to
arrive and good nocturnal cooling conditions...chillier
temperatures will occur each night...especially in valleys. By
Thursday morning...it is still possible that the coldest valley
locations could have a touch of frost.
Long term...(thursday through tuesday)
issued at 310 PM EDT Tuesday Oct 13 2015
Upper level wise the eastern Continental U.S. Broad trough remains in
place...while a ridge extends from Texas in the Pacific northwest. A
feature will swing southeast out of the upper Midwest through the broad
trough Thursday night into Friday bringing some height falls
across the region. This broad trough progresses east as we move
into the weekend and early next week...as the aforementioned ridge
creeps into portions of the eastern US before flattening. In terms
of models there is above average agreement overall in the upper
level pattern...perhaps more discontinuity in the upper level wave
on Thursday night into Friday.
The surface feature most prominent through the period will be high
pressure...as several highs progress across the region through the
long term period. The first of these areas of high pressure will
be nearly stationed across portions of eastern Kentucky to start the
period...then this will shift east through the day on Thursday.
After this the attention will be focused on a fairly weak cold
front that if prognosticated to move southeast out of the Midwest late Thursday
into early Friday. This is where models continue to have a lack of
Unity overall with potential for quantitative precipitation forecast. The NAM/GFS have remained
dry in most of the runs this week...while the European model (ecmwf)/Canadian has
been the wetter models. The latest 12z run of the NAM remains
dry...while the 12z GFS has introduces some light quantitative precipitation forecast in the far
north. Previous superblend did introduce some slight probability of precipitation...so
will lean toward the 12z superblend which does bring some chances
probability of precipitation across far north. This system moves southeast while a strong
high builds in from the northwest. This high will creep into the middle
Atlantic by Tuesday.
First impact of the period will be the frontal boundary by
overnight Thursday into early Friday. This will bring slight
chance to chance of showers across the north...however given dry
air represented at the surface based of forecast soundings and
time heights it seems this activity would remain quite light with
less that a tenth of an inch of rain. Next bigger impact will be
the potential for frost and freezing temperatures by the weekend...as
prior mentioned strong high pressure moves into the region.
Overall this weekend will be quite cold and below normal with
highs on Saturday and Sunday only warming into the 50s. The
widespread frost will be most likely Sunday morning...while Monday
may not be as much given high moves east by this point. Temperatures warm
up Monday into Tuesday under return flow...with highs getting back
closer to normal.
Aviation...(for the 00z tafs through 00z Wednesday evening)
issued at 744 PM EDT Tuesday Oct 13 2015
VFR conditions prevail at taf issuance as winds continue to calm.
There is currently a stratocu deck affecting much of the
area...with broken to overcast ceilings generally above 4500 feet. Expect this
cloud deck to continue through the first half of the
night...slowly scattering at the western most taf sites after 6z.
Overnight...fog will bring vlifr to the deepest valleys...but will
likely not impact taf sites. The fog will dissipate by late
morning on Wednesday...leaving mostly sunny to partly cloudy VFR
skies for the remainder of the taf period. Winds will likely
remain westerly...generally under 10 knots overnight...but
possibly increasing to the 8 to 15kt range during the afternoon