Area Forecast Discussion
Issued by NWS Paducah, KY

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000
FXUS63 KPAH 150723
AFDPAH

Area Forecast Discussion
National Weather Service Paducah KY
223 AM CDT Sat Jul 15 2017

.SHORT TERM...(Today through Monday night)
Issued at 202 AM CDT Sat Jul 15 2017

The frontal boundary is now to our south, however, dew points
still over in the lower 70s across our southern tier of counties.
The HRRR outlooks this area for isolated diurnally fueled storms
today, and we can`t disagree with a steepening gradient to model
output 0-1KM Mucapes rising toward/in excess of 2K J/KG this pm.
Cooler dew points in the mid 60s, underneath a southward sinking
surface high pressure center, will suppress any updrafts over the
northern 3/4 of the FA. Loss of diurnal heating should mean Pops
falling silent for the overnight hours.

The surface high expands its grip across the Ohio river valley
through Sunday, and drags dew points down thru the 60s for the
entirety of the FA. That should keep Pops silent thru the peak
heating hours then, too. Weekend Highs in the 80s and Lows in the
60s will be pleasant with lower humidity levels.

Sunday night, a piece of energy tops the upper ridge, to our west,
and falls down the Wabash valley, on the back side of the upper
trof, to our east. Its front/associated pcpn falls apart as it
reaches toward the Ohio valley, but some models, like the GFS,
suggest a smallish Pop for our northern counties. Since it is at
night time, and our dew points are still in the 60s, and it is
diminishing upon its fall and the surface high center circulation
is ridged across the Ohio river valley, we`re going to go silent
on Pops for that time period.

Monday-Monday night sees us still in the `tweener` upper pattern,
but note we do get a little more ridging, with H5 height rises
upwards to 30DM. Combined with a reinforcing surface high
pressure system across the Ohio river valley, we`ll stay dry, even
as Highs approach 90 again with dew points souping toward 70
again.

.LONG TERM...(Tuesday through Friday)
Issued at 202 AM CDT Sat Jul 15 2017

Medium confidence in the extended with the deterministic models
diverging with time.

The forecast was weighted more toward the ensemble runs and
deterministic ECMWF. This output would build the upper level western
high back through the plains and into the lower Ohio and mid
Mississippi River Valleys. The 00z Saturday operational GFS was the
outlier with the high remaining over the west...keeping a northwest
flow over the region. The chosen solution will place us in a very
warm scenario with highs in the 90 to 95 degree range. Also with dew
points in the lower to middle 70s it will be very uncomfortable and
likely a dangerous heat wave. It will also produce heat index
values in the 100 to 105 degree range during the afternoon hours.
The longevity of the heat wave will be the most dangerous aspect
with most all of the extended reaching these numbers each day.
Also with overnight lows in the lower to middle 70s it will be
very difficult to find relief from the heat. Otherwise there are
very low chances for storms mainly in southwest Indiana...in the
afternoon. Rain chances may return this weekend but the heat will
remain.

&&

.AVIATION...
Issued at 202 AM CDT Sat Jul 15 2017

Patchy MVFR Fog is possible early, otherwise scattered to at times
broken bases in the low VFR to upper end MVFR range are possible,
as we become increasingly under the influence of surface high
pressure sinking southward toward the Ohio river valley. That
should help diminish cloudiness overall with time.

&&

.PAH WATCHES/WARNINGS/ADVISORIES...
IL...None.
MO...None.
IN...None.
KY...None.

&&

$$



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