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FXUS63 KPAH 180814

Area Forecast Discussion
National Weather Service Paducah KY
314 AM CDT Wed Oct 18 2017

.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 134 AM CDT Wed Oct 18 2017

IR Satellite pics reveal sharp contrast between warm water/cool
land and offer best areal zones for another pre dawn development 
of Fog, already showing up at some local sites if not yet at 
terminals. These could result in some short lived drops in vsbys
or low lift/cloud heights prior to/just after sunrise, similar to
Tuesday morning. High pressure controls an otherwise VFR 
forecast, but southerly return winds do pick up this pm, with some
gusts into the teens kts possible at times.



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