Area Forecast Discussion
Issued by NWS Paducah, KY

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FXUS63 KPAH 221718 AAA

1218 PM CDT Tue Apr 22 2014

Issued at 1213 PM CDT TUE APR 22 2014

Updated the aviation discussion for the 18Z TAF issuance.


.SHORT TERM...(Today through Thursday night)
Issued at 316 AM CDT TUE APR 22 2014

Latest surface analysis shows the cold front just northwest of the
PAH forecast area. Based on timing and model guidance, the cold
front and any associated isolated showers should exit southeast
portions of the fa by 16z. Clearing skies are expected through the
morning, though the cu rule implies we could see some fair weather
cu across our eastern counties this afternoon. North winds will
help bring in some cooler air, and temperatures will reach near
seasonal readings in the upper 60s to lower 70s.

Surface high pressure over the Great Lakes and an upper level
ridge over the region will keep conditions dry and seasonal into
Wednesday. Very dry air in place over the area will lead to mostly
clear skies through Wednesday. Winds will gradually shift back to
the south late Wednesday night into Thursday morning. This will
aid in increasing moisture across the area ahead of our next
weather system.

Models show a low pressure system over western Iowa by 12z Thursday.
The associated cold front will move across the middle Mississippi
and lower Ohio valleys Thursday into Thursday evening.  NAM is
drier and a little faster than GFS and ECMWF, and only produces
around a tenth or less of QPF. GFS and ECMWF produce more in the
quarter to half inch range. With fairly limited moisture return
ahead of the front, will stay on the lower end with QPF amounts.
As for precip chances, models bring precip into far west portions
of the PAH fa between 12z and 18z Thursday, and included slight to
to chance pops for portions of mainly southeast Missouri Thursday
morning. By Thursday afternoon, models show precip becoming fairly
widespread across the western two thirds of the PAH fa, and went
with slight chance pops east to likely pops west. Thursday
evening, the front should be moving across eastern portions of the
fa, and went with likely pops east to slight chance west. After
00z, kept just some slight chance pops in our far east counties.

Models are showing LIs anywhere from 0 to -5 and CAPE values of
800 to 1400 J/kg, mainly Thursday afternoon. SPC has our entire region
in a Day 3 see text. Combined with the potential for quite a bit of
sunshine/heating before clouds/precip spread across the area,
there will be some potential for a few strong to severe storms
Thursday afternoon into Thursday evening.

.LONG TERM...(Friday through Monday)
Issued at 316 AM CDT TUE APR 22 2014

Low confidence continues with respect to the evolution of an
increasingly active and somewhat amplified mid tropospheric flow
pattern in the long term. How this pattern unfolds will also
determine how far south a frontal boundary will make it before
stalling and/or wavering somewhere across the region Saturday
through Monday. The models are showing extreme run to run
inconsistencies. Yesterday, the ECMWF was farther north with the
front, more warm sector for us, while a consensus of the
GFS/GEM/UKMET were much farther south with the front. The 00z GFS
(with the trend seen in the last 4 runs) is now much farther north
with the front, and warm sector for us, a complete flip flop, while
the ECMWF shows a farther southward progression of the front,
stalling it somewhere across our region. Needless to say, this could
spell out into elevated statistical MAE`s with temps and dew points.
We used a blend of previous numbers, and the latest ECMWF values, as
it seems a compromise of solutions, would be to fall somewhere in
between the wide array of possibilities, for now.

Meanwhile, with the increasingly active mid level flow pattern and
presence of the frontal boundary, chances of convection will be in
the forecast Saturday through Monday, after a dry Friday. Pattern
recognition suggests convection is highly likely. However, to
minimize timing errors and factor in coverage uncertainty, will
continue with mid chance PoPs (40-50 percent or so max) in the
Sunday through Monday time frame, as an upper low over the central
CONUS is forecast to move toward the area. Just slight chance PoPs
for now Saturday through Saturday night, warranted by the presence
of the front, and modest moisture and instability seen in the models.


Issued at 1213 PM CDT TUE APR 22 2014

VFR conditions expected at all sites through the period. Northerly
winds at 10-12 knots gusting up to 20-22 knots will become light
and variable after 01Z, then pick back up out of the northeast aob
10 knots after 15Z.




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