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Area forecast discussion 
National Weather Service Jackson Kentucky
132 PM EDT Tuesday Apr 28 2015

issued at 1147 am EDT Tuesday Apr 28 2015

Another quick update to align T and dew point hourly grids with recent
observation. Sent updated grids to ndfd and web servers.

Update issued at 915 am EDT Tuesday Apr 28 2015

Did a quick update to remove the mention of fog and frost from
the zones. Also adjusted T and dew point grids to align them with most
recent observation. Otherwise...forecast remains on track. Sent updated
grids to ndfd and web servers.

Update issued at 726 am EDT Tuesday Apr 28 2015

The forecast has been on track for the most part overnight and
early this morning. Reports of fog have been coming in this
morning from volunteer weather the fog in the grids
through 12z is on the Money. Based on temperatures seen in a
number of surface observation...some frost has also likely occurred this
morning. The zones should be able to be updated by 9 am to remove
mention of fog and frost.


Short term...(today through wednesday)
issued at 300 am EDT Tuesday Apr 28 2015

The short term portion of the forecast will start warm and
dry...with mostly sunny skies...light winds...and highs on the middle
60s on tap for today. These readings will be below normal for this
time of year...but still a very nice day to be sure. Overnight
lows will bottom out in the 40s across the area...again below
normal. Even though it does appear that the weather will be a bit
more active on Wednesday...confidence is not as high as it could
be due to uncertainty amongst the various forecast models. The
nam12...GFS...and hires arw and nmm models are all keeping eastern
Kentucky free of precipitation until late Wednesday night. This is
contrast to the European model (ecmwf) model and the latest ensemble means...which
both bring precipitation into the area late tonight into early
tomorrow a southern stream weather system moves by to
our south. There is also some disagreement as to the timing of a
northern stream system that some of the models have phasing with
the southern systems late tonight into early tomorrow. All that
being said...with a few sets of model output showing some
precipitation getting into eastern Kentucky by around dawn on
Wednesday...decided to go ahead and leave in precipitation chances
beginning at 8 or 9z on Wednesday...and lasting through the end of
the period at 0z Thursday. The new forecast will feature much
lower precipitation chances than before...along with a slower northward
progression of the precipitation shield.

Long term...(wednesday night through monday)
issued at 302 am EDT Tuesday Apr 28 2015

The models are just in fair agreement aloft at the start of the
extended portion of the forecast but then come more in line with
each other over the weekend. For Wednesday night a rather deep
trough remains in place over the eastern half of the nation with its
axis passing through Kentucky. Another strong reinforcing shortwave
will push south from the western Great Lakes and into the base of
the larger trough Wednesday night. This will lead to a closed low
taking shape over the Ohio Valley during the day Thursday. For this
the GFS is stronger...but further north than the European model (ecmwf) and the
middle of the Road Gem. The slower and deeper GFS takes this low
through the central and southern Appalachians Thursday night while
the European model (ecmwf) is already moving it offshore. By Friday night...heights
will be ticking up over eastern Kentucky in the wake of the
departing trough...with the GFS and Gem more in sync than the European model (ecmwf)
with off the East Coast. This will place east Kentucky in
the midst of northwest flow and weak waves passing by at middle levels
through the first part of the weekend. Higher heights follow for
Sunday and Monday as the pattern further flattens out...with better
model support. This is ahead of a developing wave moving into the
Southern Plains and then to the middle Mississippi it gets
picked up by the still active northern stream. A general model blend
will be favored to account for the spread between the GFS and
European model (ecmwf)...especially in the first part of the long term forecast.

Sensible weather will feature a damp and cold start to the extended
as a surface low beneath a closed middle level low will slowly slink
through eastern Kentucky. Despite the quicker movement of the upper
system in the European model (ecmwf)...and its stronger...coastal surface keeps
the quantitative precipitation forecast and low level relative humidity more robust over this area through the day
Thursday and into early Friday when compared to the GFS. At this
point prefer the wetter solution. Moderating high pressure beneath
increasing heights should keep the weather quiet and warmer through
the weekend before a cold front approaching from the northwest slows
and settles near the Ohio River on Monday... setting up closer to
our County Warning Area in the GFS than the European model (ecmwf). This boundary will need to be
watched for the potential of excessive rains well into next week...
depending on exactly where it Parks itself.

The CR grid blend came in reasonably well with some adjustments made
to lower probability of precipitation through the well as for some minor
terrain based temperature adjustments each night from Friday through


Aviation...(for the 18z tafs through 18z Wednesday afternoon)
issued at 130 PM EDT Tuesday Apr 28 2015

Mostly clear skies with light and variable winds are expected
through at least 12z tomorrow. This is when there is potential
for some clouds to move north into eastern Kentucky from a low
pressure system passing to our south. There is also a slight
chance for showers across southeast Kentucky with this system but
expect them to move in after the valid taf period...if at all.
Therefore...VFR conditions are expected throughout the period.


Jkl watches/warnings/advisories...


short term...Arkansas
long term...greif

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