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Area forecast discussion...updated 
National Weather Service Jackson Kentucky
155 am EDT Thursday Jul 24 2014

issued at 130 am EDT Thursday Jul 24 2014

Did an update to the grids to reflect the latest radar trends and
guidance through the morning. Kept the thunder chances at just
isolated at best into the day Thursday. Also tweaked the T and dew point
grids based on current obs/trends. This update have been sent to the
ndfd and web servers.

Update issued at 1127 PM EDT Wednesday Jul 23 2014

New convection has sparked along the I-64 corridor...where there has
been a lack of activity throughout the evening. Expect this cluster
of showers and storms to gradually spread east over the next couple
of hours...before dissipating. The main broken line has worked its
way into far southeastern Kentucky...heading into an area that had
been tapped earlier this would expect a gradual
weakening trend as well. During the overnight...still can not rule
out some scattered convection with the frontal boundary and upper
trough still upstream...however any deeper convection should be
isolated. Updates have been sent.

Update issued at 831 PM EDT Wednesday Jul 23 2014

Clusters of showers and thunderstorms have developed over the past
few hours and have slowly sagged east with time. Heavy rainfall has
been the biggest concern with these due to the slow movement of the
system and embedded training storms. Have updated the probability of precipitation
accordingly. Expect this convection to gradually weaken as it heads
further southeast...where instability has not made much of a recovery
after convection from early today had moved through the area. This
is supported by the latest hrrr...which has struggled with capturing
this system as it evolved...but in recent runs appears more


Short term...(this evening through Thursday night)
issued at 505 PM EDT Wednesday Jul 23 2014

Broad cyclonic flow aloft will sharpen up a bit over the next 12 to
18 hours. Other than a minor ripple in the flow Thursday night...
short wave ridging will begin building into the region Thursday.
Cold frontal boundary still just north of the Ohio River sliding
southward at a very slow pace...but should get a helpful kick start
through the overnight period. Boundary should push into eastern
Kentucky late tonight and be out of our forecast area by middle morning
to noon on Thursday as Canadian high pressure builds in behind. Until
then showers and thunderstorms will remain in the forecast. Thus far
there has been no real organization to convection except along
residual outflow boundaries. Based on radar and satellite trends
expect a lull in activity through the late afternoon. But expect
showers and thunderstorms will redevelop this evening and have
reflected this in the grids. Otherwise nudged grids to latest blend
of models...especially temperatures. Gusty winds and heavy rain will remain
a threat until later tonight as reflected in the severe weather potential statement.

Long term...(friday through wednesday)
issued at 257 PM EDT Wednesday Jul 23 2014

He long term portion of the forecast will feature a mean trough
over the eastern part of the country with ridging over the west.
This will result in significantly cooler than normal conditions for
our area next week as the western ridge amplifies and the eastern
trough deepens.

Surface high pressure will build into the Ohio Valley on Friday
bringing fair mild weather to end the work week. However rain
chances will return as a warm front approaches Friday night into
Saturday. The remains of a possible mesoscale convective system may approach the northwest part of
the forecast area by early Saturday morning and will introduce
slight chance rain probabilities in the northwest part of the forecast area
after 06z on Saturday. The weekend looks to be unsettled as the
remains of the returning warm front become stationary and linger in
the area...and then a cold front approaches on Sunday. This will
require shower and thunderstorm chances in the forecast through the

By late in the weekend the overall upper air flow will begin a
significant amplification with major deepening of the eastern North
American trough and amplification of the western ridge. This process
will begin as an upper low moves from south central Canada on
Saturday into the Great Lakes region by Sunday night. At the surface
this will result in a significant cold front driving south across Kentucky
late in the weekend. While exact timing of the frontal passage is
still appears at this time the front will move south
of the area by Monday morning. The best chance for strong storms
during the coming weekend looks to be from Sunday into Sunday
evening with the approach of the cold front from the northwest.

With the unusually deep trough in the east...noted by wpc to have
heights approaching 3 Standard deviations below normal in the Ohio
Valley and Appalachians...much cooler than normal conditions will
prevail into the middle of next week.


Aviation...(for the 06z tafs through 06z Thursday night)
issued at 155 am EDT Thursday Jul 24 2014

Scattered showers and the odd thunderstorm will continue to diminish
for the bulk of the forecast area through the night. However...a
couple of cells will still be possible into dawn...but probably keep
from hitting any of the actual taf sites. For the most part...
conditions will be MVFR at all the airports tonight with times of VFR
but also low visible/ceiling induced IFR weather...or lower. Have kept thunder and
even thunderstorms in the vicinity out of the tafs as the instability will be minimal
through the rest of the night into Thursday. However...the latest
hrrr and nam12 suggest that a few showers will still be possible into
the afternoon as the front makes its final push across the area.
Have continued a vcsh for this in all sites with ceilings generally around
2k feet. In the wake of the front later Thursday evening...drier air
is expected to lift the ceilings and remove the threat of showers. Winds
through the period will be mainly light and variable...though
favoring the northerly direction later Thursday.


Jkl watches/warnings/advisories...


short term...ray
long term...sbh

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