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Area forecast discussion...updated 
National Weather Service Paducah Kentucky
644 PM CDT Tuesday Aug 4 2015

Update...
issued at 644 PM CDT Tuesday Aug 4 2015

Updated the aviation discussion for the 00z taf issuance.

&&

Short term...(this evening through thursday)
issued at 307 PM CDT Tuesday Aug 4 2015

Will be issuing a Flash Flood Watch for much of southeast
Missouri...southern Illinois...southwest Indiana and northwest
Kentucky. The western area will be valid for Wednesday and
Wednesday night...while the eastern half will be valid Wednesday
night and Thursday.

Confidence is pretty high in the western half of the watch with a
lead disturbance coming eastward out of Oklahoma early
Wednesday...and then the larger disturbance coming southeast out
of the northern plains for Wednesday night into Thursday. The
12z guidance is quite varied in how these systems interact...and
especially with the surface reflection. This forecast represents
the predominant wrapped up surface solution...but if the less
amplified GFS is correct the flooding potential will be much lower
than forecast.

Long term...(thursday night through tuesday)
issued at 307 PM CDT Tuesday Aug 4 2015

There continues to be poor continuity among the models during the
long term. Recent model runs have backed off on the push of cooler
and drier air for the weekend...which had looked pretty strong at
one point. The models are in agreement that a stronger cold front
will push through our region early next week...however model
performance has been lackluster recently.

As far as the daily details...

On Friday...the remnants of the frontal boundary associated with the
middle-week system will likely be stalled across Missouri and Arkansas.
Will keep southwest Indiana and adjacent counties dry...but the
remainder of the region will be close enough to the front for a
chance of showers and storms. Highs will generally be in the middle to
upper 80s.

Friday night and Saturday still appear dry as weak high pressure
passes east across Illinois and Indiana. Temperatures may actually be a
little warmer on Saturday due to increased sunshine.

On Sunday...the models build the upper level high over the plains
slowly northeast. Low level winds will turn into the south...which
will bring temperatures and dew points up a little more. A 700 mb shortwave
will weaken as it moves east from the upper Mississippi Valley. This
shortwave may be enough to support isolated convection as far south
and east as the Ohio River.

On Monday into Tuesday...there is strong model agreement that the
500 mb trough will sharpen over the eastern states. This will be
enough to drive a cold front southeast across our region on
Monday...accompanied by a chance of storms. If the models hold
true...temperatures and dew points will drop off on Tuesday.

&&

Aviation...
issued at 644 PM CDT Tuesday Aug 4 2015

Diminishing convection affecting the kevv/kowb sites should
continue to diminish early this evening. With the approach of a
frontal boundary couple with ripples of upper level
energy...precipitation increase significantly early Wednesday
morning at kcgi/kowb and more toward middle to late morning at
kevv/kowb. Worse case scenario should be MVFR ceilings/visibilities in thunderstorms and rain.
Northeast winds at or below 5 knots becoming southeast over the latter
half of the period.

&&

Pah watches/warnings/advisories...
Illinois...Flash Flood Watch from Wednesday morning through Thursday
morning for ilz075-080-081-084-085-088.

Flash Flood Watch from Wednesday evening through Thursday
evening for ilz076>078-082-083-086-087.

MO...Flash Flood Watch from Wednesday morning through Thursday
morning for moz076-086-087-100-107.

In...Flash Flood Watch from Wednesday evening through Thursday
evening for inz081-082-085>088.

Kentucky...Flash Flood Watch from Wednesday evening through Thursday
evening for kyz014-015-018>020.

&&

$$

Short term...drs
long term...my
aviation...jp

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