Area Forecast Discussion
Issued by NWS Paducah, KY

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FXUS63 KPAH 181710

Area Forecast Discussion
National Weather Service Paducah KY
1211 PM CDT Wed Oct 18 2017

Issued at 1211 PM CDT Wed Oct 18 2017

Updated aviation discussion.


.SHORT TERM...(Today through Friday night)
Issued at 134 AM CDT Wed Oct 18 2017

The short term forecast will see surface High pressure holding
strong/shifting east, and returning low level southerlies to the
FA. H5 heights, already starting to rise, will build some
additional 60 meters plus by Friday, as its ridge axis builds
across the Mississippi and Tennesse river valleys. 850 MB temps
respond with a good 4-5C increase over the course of the short
term forecast. Time/height cross sections show a predominantly dry
column save for some moisture showing up at/above 400 mb off and
on thru the period, mostly Friday. All of this adds up to us, and
neighboring offices, favoring a collaborative nudge upwards from
the blend, for High temps daily, similar to how we`ve done each of
the past couple nights.

Other weather features of note include early morning fog, esp near
water bodies, probably most pronounced this morning. In addition,
driest rh mins in the pm hours will range thru the 30s percentile,
w/the SEMO Ozarks again experiencing the lowest of these min RH`s.

.LONG TERM...(Saturday through Tuesday)
Issued at 313 AM CDT Wed Oct 18 2017

A cold front will be approaching the middle Mississippi valley on
Saturday.  ECMWF, GFS and the Canadian are in good agreement showing
the front reaching the western fringes of the PAH forecast area by
12z Sunday.  A few showers and thunderstorms may reach our far
southwest counties Saturday afternoon, with showers and
thunderstorms becoming scattered to widespread Saturday night across
all but our far east counties.  Confidence is pretty high that we
will see widespread precipitation across the entire region on Sunday
into Sunday night.

Despite the agreement in frontal position Sunday morning, all models
have been going back and forth on timing of the movement of the
front late Sunday night into Monday night.  The latest ECMWF has the
front across our region by 06z Monday, while the previous run had it
through by 00z Tuesday.  The latest GFS takes the front through by
12z Tuesday, while the previous run had it through by 12z Monday.
The inconsistency of the models leads to low confidence for Monday
and Monday night.  Went with slight to low chances Monday into
Monday night, with the best chances across our eastern counties, and
dry conditions in our west by late Monday into Monday night.  Went
with dry conditions across the entire area on Tuesday for now.

Models continue to indicate the best instability across our area
will be Saturday night into early Sunday, so this is when the best
thunderstorm chances are included.  Went with slight chances of
thunderstorms Sunday afternoon decreasing to just showers from
northwest to southeast by Sunday night.

It will remain very warm ahead of the front on Saturday into
Saturday night with breezy south winds.  Readings will drop off to
near seasonal on Sunday with the precipitation and cloud cover, near
seasonal conditions by Monday, then below seasonal by Tuesday with
breezy northwest winds.


Issued at 1211 PM CDT Wed Oct 18 2017

Few clouds will be around for the 24 hour TAF period as the flow
aloft becomes increasingly anti-cyclonic. On the backside of a
surface high lingering over eastern TN, the pressure gradient will
increase with the approach of a weakening surface trough. Thus,
sustained southerly winds around 10 knots will prevail this
afternoon, gusting above 15 knots at times mainly in the western
half of the region. Winds will be light, but not calm, tonight, then
should veer a bit and pick up again Thu morning, perhaps with
slightly less verve.




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