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Area forecast discussion 
National Weather Service Jackson Kentucky
1021 am EDT Tuesday Jun 30 2015

issued at 1020 am EDT Tuesday Jun 30 2015

Conditions across the area feature fog over the valleys finally
dissipating and have taken it out of the forecast for this
morning. As well...lingering showers and a few storms have also
dissipated and this will remain the case based upon a weak
inversion still in place. Will ramp up probability of precipitation after noon and bring
thunder into the forecast during this time. As stated by the night
shift...this activity today still looks rather minimal...possibly
less than yesterday. The hi res models suggest this but based
upon the fact the activity yesterday took some time to
strengthen...the slight risk today seems relevant for this
afternoon. A new zone forecast product has been sent with the grids sent to the web.

Update issued at 718 am EDT Tuesday Jun 30 2015

Light rain has finally exited the southeastern portions of our
area. Have seen some low stratus and patchy dense fog form...
mainly where skies have cleared across our western and northern
most counties. Removed higher probability of precipitation in our southeast for the early
morning time frame. Also beefed up the fog in the zones and
brought grids in line with hourly observation.


Short term...(today through wednesday)
issued at 440 am EDT Tuesday Jun 30 2015

Amplified pattern remains in place with ridging across the
western Continental U.S. And troughing across the eastern Continental U.S.. short waves
continue to rotate through the base of the eastern trough...being
the main driver of our weather through the short term. Models
continue to show good agreement with overall pattern...with only
differences showing up with respect to timing and strength of
passing short waves.

Area of convection has stalled out across central and eastern Tennessee.
There has also been some persistent light rain north of the Tennessee
state line just inside our County Warning Area as well. Recent run of the hrrr
has this area of convection lifting back up to the NE this
morning...catching a portion of our County Warning Area. Radar trends appear to be
trending in that direction though not as strongly as the hrrr
would suggest. Added some higher probability of precipitation and reintroduced some isolated
thunder for the far southeast to account for this possibility.

Another in the current series of disturbances will drop into the
region later today...producing another round of showers and
thunderstorms. Based on current forecast soundings...marginal to
at best modest shear and surface based instability suggests the
potential for a few severe storms this afternoon and early this
evening...similar to Monday. In addition...Storm Prediction Center continues to carry
our area in a slight risk for severe thunderstorms today. As such
will mention the potential threat in our severe weather potential statement.

Long term...(wednesday night through monday)
issued at 344 am EDT Tuesday Jun 30 2015

Long range models are still in very good agreement starting out
Thursday with a deep longwave troughing pattern setting up across
much of the eastern Continental U.S. And remaining in place through much of the
weekend...while slowly dampening. This pull of northerly air will
keep temperatures below normal through the weekend as well.
Multiple shortwaves will traverse the longwave trough...which will
likely affect much of the Ohio River valley...bringing enhanced
areas of lift for showers and thunderstorms...and even some mesoscale convective system
potential. A strong upper level low will gain strength as it moves
south into southern Canada Sunday into Monday. This will dampen the
trough across the eastern Continental U.S....but will keep a weak northwest flow
regime across the Ohio River valley. The upper level low will then
shift eastward Monday night into Tuesday...directly impacting the
upper Great Lakes. Expect energy from this system to impact as far
south as Kentucky to end out the forecast period. Confidence remains
low...however...for this late weekend/early work week
the GFS and European model (ecmwf) are still showing some disagreement on timing and

As for sensible conditions...the northwest flow and shortwaves will produce
a series of frontal boundaries and Sparks for showers and
thunderstorms. The first of these boundaries will have moved into
the Ohio Valley region to start off the extended period...and will
oscillate north and south but remain overall rather stationary
through the first part of the weekend. Meanwhile...numerous
localized surface low pressure systems will be driven by upper level
shortwaves and generally push across southern Kentucky and Tennessee. This is
where the bulk of the moisture and mesoscale convective system potential will lie. By
Friday...the shortwave moving through will pass across the northern
portion of the state...and the local surface boundary will align
itself along the Ohio River. This time around...expect best moisture
/rain and thunder potential/ to move across the entire
state...continuing through much of the weekend but peaking during
the afternoon and early evening hours.

If the European model (ecmwf) model holds true...the strengthening upper level low
moving southeast across Canada will bring a much stronger cold front across
the northern Mississippi River valley Monday and into the Ohio River
valley and points northward Monday night into Tuesday. Confidence on
timing and the exact frontal location is still quite low
however...given the discrepancies in the GFS and European model (ecmwf) this far out
in the forecast /as mentioned above/. Stuck with a blend of these
models...which led to just a mention of chance probability of precipitation during this time
period. However...this system could bring another strong dose of
strong showers and thunderstorms /pwats 2 inches an above/...and
potentially some strong winds with 25 to 30 knots expected just
above the surface and through the middle levels according to the latest


Aviation...(for the 12z tafs through 12z Wednesday morning)
issued at 718 am EDT Tuesday Jun 30 2015

Low stratus and patchy dense fog has developed where clearing has
taken place...mainly across our north and west. As a result ksme
and ksym are seeing decent swings in visibilities...from solid VFR to IFR
categories...but more steady IFR to LIFR ceilings. Low stratus and fog
should lift over the next few hours. Thereafter cumulus will develop as
daytime heating kicks in. Showers and thunderstorms redevelop
through the day...becoming more widespread by this afternoon as
another disturbance takes aim at our area. Expect fog and low
stratus to become an issue again tonight. Winds remain light
through early morning before picking up out of the west...
southwest at 5 to 10 kts during the remainder of the day.


Jkl watches/warnings/advisories...


short term...ray
long term...jmw

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