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Area forecast discussion 
National Weather Service Jackson Kentucky
357 am EDT Thursday Aug 21 2014

Short term...(today through friday)
issued at 357 am EDT Thursday Aug 21 2014

The latest surface map features high pressure across the Gulf Coast
states...with low pressure across the plains states. A stationary
boundary extends east from the plains into the Great Lakes/Ohio
Valley region. Aloft...an upper level low continues to spin across
the northern Great Lakes...with an upper level ridge centered near the
northern Gulf of Mexico...and more troughing featured across the
northern rockies. Several complexes of thunderstorms have been
generating and then riding southeast on the periphery of the upper
level ridge over the past few days.

Currently...eastern Kentucky remains quiet as only a weakening
smaller complex of thunderstorms is slowly moving through southeast
Illinois and southwest Indiana. The next more organized complex is
currently moving through Minnesota.

The model guidance has been all over the place with the timing of the
more organized convection as of late. As such...have used a general
blend of the guidance and the inherited forecast. As the upper level
ridge slowly builds into the region through Friday...it will
generally nudge the mesoscale convective system track further northeast...however since there
will be plenty of fuel for the storms and a weak synoptic pattern in
place...can not rule out outflow influence further southwest. Some
storms could approach severe limits...and isolated flash flooding
will also be a possibility...especially where storms can move
parallel to any established outflow boundaries. Will highlight these
threats in the severe weather potential statement. Probability of precipitation will generally peak in the afternoon hours
today and Friday...with lesser chances during the overnight hours.

Highs today will average in the 85 to 90 degree range...with around
90 degrees expected for most locations on Friday.

Long term...(friday night through wednesday)
issued at 357 am EDT Thursday Aug 21 2014

The extended portion of the forecast begins on Friday night with a
well developed middle level ridge centered over the middle west and
longwave trough entering the northwest with an exiting trough over
the northeast. The middle level ridge axis eventually shifts east over
the Ohio Valley by Monday as it weakens a bit with the approaching
trough over the northern plains and the trough over the northeast
exiting into the Atlantic. This pattern basically keeps the ridge over
eastern Kentucky through the rest of the extended.

With this pattern in place through Sunday...eastern Kentucky remains
in northwest flow with still a few mesoscale convective system/S likely poised to track
southeast into the area for this weekend. While models inherently
will have trouble tracking them...the first one should be moving
through Friday night with the next one possibly Saturday night. By
Sunday...the ridge axis really begins to set in and additional
strong convection may be less likely and may be more tied to diurnal
processes with a stationary boundary along the eastern portion of the
County Warning Area. By Monday and through Wednesday...the middle level ridge axis
moves over the area which should effectively cut off convection...at
least deep convection. Some afternoon showers and possibly a storm
or two may develop under the ridge. The solution of the all model
blend would suggest some uncertainty there with the best chance of
precipitation Friday night through Sunday. This is in good agreement with
the GFS and Euro as well. Overall the broad brush of probability of precipitation
through the first 3 days of the extended seems needed due to the
nature of the models having trouble depicting the complexes moving
through but did go with some diurnal characteristics.

By the end of the extended...the models seem to hint at the ridge
moving farther east as a strong shortwave and associated cold front
seems poised to move through the MS River Valley and into the Ohio
Valley. In addition...the warm and muggy weather still looks to be
on tap through the weekend with highs around 90 through Monday and
dew points around 70. The end of the extended does show some relief
from the warm and humid weather with the approach of the
aforementioned cold front.

&&

Aviation...(for the 06z tafs through 06z Thursday night)
issued at 214 am EDT Thursday Aug 21 2014

IFR or worse fog/stratus will be the main concern through the night.
Locations that saw more sustained heavy rainfall will be the most
susceptible. Some lingering high clouds and light south to southwest
winds will keep the fog at Bay for some of the broader valleys and
ridgetops through the next couple of hours...however as skies clear
out and winds likely lighten even more...expect the fog/low stratus
to build in more extensively. Once the fog Burns off between 12 and
14z...scattered to numerous convection will likely threaten once
again from 15z Onward.



&&

Jkl watches/warnings/advisories...
none.
&&

$$

Short term...geogerian
long term...shallenberger
aviation...geogerian

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