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Area forecast discussion 
National Weather Service Jackson Kentucky
229 PM EDT Sat Apr 25 2015

issued at 230 PM EDT Sat Apr 25 2015

Issued an update to further adjust the probability of precipitation and sky cover based
on current trends. Went a bit slower on eroding clouds in the
south with the north remaining with clouds but this will create a
heating differential boundary between northern and southern
portions. With this...expecting severe convection to move into the
area after 21z and most likely from the west. It is unlikely that
like the hrrr suggests that the storms will develop over eastern
Kentucky. Have updated the probability of precipitation to suggest this. Will still keep
the temperature differences in place as well. At this
time...warming continues in the south and convection in western Kentucky
is near or beginning convective initiation. With this
development...would expect this activity to move east with the
best environment converging over the hal Rogers Parkway and south.
A new zone forecast product has been sent out and new grids have been sent.

Update issued at 1130 am EDT Sat Apr 25 2015

Current conditions across the area feature a swath of showers
moving through to the northeast across eastern Kentucky. At this
time...the warm front is developing and slowly moving north and is
positioned just north along the Kentucky/Tennessee border. Cloud cover at this
time is quite extensive across the area...though...some peaks of
clearing are occurring to the west and a few peaks to the south.
However...ongoing convection along the Gulf Coast seems to be
keeping cloud cover streaming northward into the area this
afternoon. Have timed a bit of clearing to occur over southeast
Kentucky but if the cloud cover moving up from the south
continues...severe convection will be drastically limited into
this afternoon and evening. Later this evening...the hrrr hints at
an mesoscale convective system development and moving south southeast into the area along
with the surface low by 00z tonight. At this time...the event may
be transitioning into a Hydro event. Have updated the zone forecast product to time
the threat of severe weather this evening and the progression of
the warm front through the day. It GOES without saying that the
next few hours will say alot about what transpires later this
afternoon and into the evening.

Update issued at 13 am EDT Sat Apr 25 2015

Blended early morning observation into the forecast. No substantial
changes were made.


Short term...(today through sunday)
issued at 411 am EDT Sat Apr 25 2015

An active period is in store...with events just beginning to
unfold. An area of showers is expected to develop and move NE over
the region this morning. is behind schedule as based
on the 00z models...with a convective system over MS and Alabama
possibly foiling the outcome. The latest hrrr model suggests it
will still happen...but may be more focused on our northern

Once this will be a waiting game for additional
convection to develop during the afternoon and evening as a storm
system approaches from the west...along a frontal boundary draped
across our area. It still appears there will be large surface
based instability present in our southwest counties...with weaker
and more elevated instability further northeast. Shear will be
more than sufficient to support organized convection. Dry middle
level air is also expected in our SW. This will present a threat
of severe weather over our SW...with super cells possibly
producing large hail and high winds...and a secondary threat of
tornadoes. Excessive rainfall is also a concern with training of
cells along the frontal boundary. Where this may set up is still
uncertain. Any Hydro problems likely would not arise until this
evening...and have opted to let day shift examine the 12z run
before making a decision on a flash Flood Advisory.

The frontal boundary will move to our south as low pressure moves
east through the region tonight. Any lingering showers will end on
Sunday morning and clouds will break up during the day from northwest to
southeast as dry air moves in.

Long term...(sunday night through friday)
issued at 335 am EDT Sat Apr 25 2015

The models were in good agreement in the extended. The period is
set to begin with a large ridge of high pressure move out of the
north Central Plains and across the lower Great Lakes and Ohio and
Tennessee Valley regions Sunday night through Tuesday. The pattern
is then forecast to change Tuesday night and both
northern and southern stream weather systems make their way across
the Great Lakes and Gulf Coast regions. The southern stream system
appears to be the stronger of the two...and therefore would have
to greater influence on area weather middle week. As it stands...a
roughly 60 40 blend of the European model (ecmwf) and GFS models was used to create
the forecast from Tuesday night Onward. The southern stream
trough is prognosticated to bring moisture off the Gulf of Mexico
northward into central and eastern Kentucky Wednesday and
Wednesday night. As this occurs...the northern stream system is
forecast to dive southward and phase with the Tennessee Valley
southeastern Continental U.S. Low. The GFS does differ slightly from the
European model (ecmwf) model during this its northern stream low pushes
on eastward into New opposed to phasing with the
southern the European model (ecmwf) is depicting. That being
said...this is where the usually more consistent European model (ecmwf) model
solution was favored. There will be a chance of rain in the
forecast for the entire area from late Tuesday night through
Thursday night. However...due to the differing model
solutions...decided to stay with slight chance to chance
probability of precipitation...with 40 being the high end during the wet period. Friday
and Friday night look to be dry as the southern stream weather
system exits to our east and another ridge of high pressure builds
across the southern and southeastern Continental U.S..

Temperatures next week will likely be below normal through
Thursday...due to the influence of cloud cover and precipitation
and the fact that this weekends temperatures will also remain well
below normal due widespread cloud cover and precipitation. What
this amounts to is the atmosphere will starting off behind the
eight Ball to start the week temperature wise...making it
difficult for things to warm up as much as normal due to the short
break between weather systems. Highs on Friday should be right
around normal across the entire area.


Aviation...(for the 18z tafs through 18z Sunday afternoon)
issued at 230 PM EDT Sat Apr 25 2015

The showers that have moved through the northern half of eastern
Kentucky this morning has moved northeast out of the area but IFR
and below ceilings and visible remain and have included this in the tafs
through the evening hours. As warm front slowly nudges
north...clouds will be on the increase in the south as
thunderstorms develop and move in from the northwest. This will
result in below feild mins through the night with thunder near
each station through 06z. Afterward...low ceilings and visible will linger
through the morning hours. Winds will remain relatively light
through the period outside of thunderstorms.


Jkl watches/warnings/advisories...


short term...hal
long term...Arkansas

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