Area Forecast Discussion
Issued by NWS Paducah, KY
FXUS63 KPAH 010735
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PADUCAH KY
235 AM CDT Wed Oct 1 2014
.SHORT TERM...(Today through Friday night)
Issued at 235 AM CDT WED OCT 1 2014
High pressure will continue to move off to the east, with low
pressure taking shape over the southern Plains by tonight. Broad
west U.S. trof in place, with a s/wv ejecting NE from the central
Plains. Our attention is on the second wave over the Intermountain
West. Low level moisture will be on the increase today, with some
instability into SEMO, the bootheel region by late day. Went with
a slim chance of convection in this area, continuing into the
early evening. It may not happen, but enough evidence supports the
limited chance in the higher resolution data.
This initial slight chance should be followed by a bit of a lull.
Even into Thursday, chances look awful small, especially per the NAM.
But we kept with the slight chances given it would not take much to
generate a shower or isold storm through the day. Chances should
be on the increase by late afternoon. Both the NAM and GFS depict
some WAA development into the area, especially along and just east
of the Ohio, into west KY.
Aforementioned mid level wave will be over the central Plains 00z
Fri with a broad area of convection, potential squall line
approaching from the west. Chances Thursday night will be
categorical as the convective activity moves from west to east
across the area.
Rather expansive slight risk seems a bit overdone for our area,
especially east of the Mississippi River. No need to play up what
should generally be a minor event. Parameters are so-so at best
for anything more than a small number of gusts that may approach
or touch severe criteria. 0-3km bulk shear is marginal (bowing
segment potential), mid level lapse rates 5.5-6 not too
impressive. Window of opportunity for favorable instability is
near 00z mainly SEMO, so hail threat looks fairly low as well. The
rain will be nice though given the recent dry conditions. Around
1" on average for most areas.
The chance of lingering showers Friday morning will quickly come
to an end in the wake of a cold frontal passage. Dry by
afternoon, with dry and cooler weather Friday night. Will keep an
eye on one more lobe of energy that will move through Friday
afternoon. This feature could bring clouds, and maybe a spot
shower or two across SE Illinois into SW Indiana late Friday
afternoon. Some model data does not show this at all. Will hold
and monitor trends.
.LONG TERM...(Saturday through Tuesday)
Issued at 235 AM CDT WED OCT 1 2014
In the extended forecast period, the second surge of central
Canadian air moves through as another cold front over the weekend.
The Medium range guidance attempts to squeeze out light
precipitation in the cold air advection regime. The variability in
the GFS PoP and precipitation scheme from the 12z Tuesday to 00z
Wednesday runs was quite dramatic and inconsistent with earlier
model runs. For these reasons, its impact on the forecast was
minimized in comparison to the more reasonable solutions of the GEM
and ECMWF or eliminated altogether.
For now, the best chance for showers (albeit small) will be Sunday
night and Monday, along and just behind the secondary cold frontal
In addition to PoPs and Weather, manual adjustments to Max/Min
Temperatures were required to compensate for the GFS bias + or - one
Issued at 606 PM CDT TUE SEP 30 2014
High pressure at the surface and aloft will keep VFR conditions
the rule. Patchy fog will be monitored late tonight, and some
moisture will begin to increase in the profile toward the end of
the planning period.