Area Forecast Discussion
Issued by NWS Paducah, KY

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000
FXUS63 KPAH 172356
AFDPAH

Area Forecast Discussion
National Weather Service Paducah KY
655 PM CDT Mon Jul 17 2017

.UPDATE...
Issued at 655 PM CDT Mon Jul 17 2017

Updated aviation discussion for 00Z TAFs.

&&

.SHORT TERM...(Tonight through Wednesday night)
Issued at 214 PM CDT Mon Jul 17 2017

A nearly stationary boundary in southern IL, coupled with decent
instability and moisture convergence over SEMO, will support
isolated convection this afternoon and evening across much of the
area, lowest chances down toward the TN/KY border. The activity
will slowly drift south. The models never really want to rid the
isolated chance tonight, and then southern and central sections
into Tuesday. Will keep a limited chance mention.

Tuesday night through Wednesday night, will keep chances out,
though we cannot rule out isolated convection Wednesday, mainly
the east 1/3 of the region. Confidence is much lower as mid level
heights continue to rise.

Will kick off an Excessive Heat Watch (mentioned in the long term
portion as well) Wednesday. It will extend into the long term
forecast period Thursday through Sunday. It is for at least 50
percent confidence in meeting long duration excessive heat
criteria, defined locally as, peak heat index values of 105F or
more for 4 or more consecutive days. We will be close enough to
warrant the Watch. The eventual headline may either be a Warning
or Advisory.

.LONG TERM...(Thursday through Monday)
Issued at 214 PM CDT Mon Jul 17 2017

This looks to be a decent heat wave during this period. A large
upper level ridge is forecast to remain over the center part of the
country through at least early Sunday. At that time an upper level
low, currently off the west coast of Canada, is forecast to break
down the ridge Sunday as the energy moves into the upper Midwest.

850 temperatures from Thursday into Sunday will be near 20 degrees
C. This correlates with 97 or so at the surface. Superblend is too
low and will be bumped up. Used WPC guidance for max temperatures
and blended with other offices.

CIPS analogs suggest the probability of being over 105 heat index
during at least part of the time during the period is over 80%. This
agrees well with the latest numbers. Looks like several locations
will reach the 105 mark several days in a row. Temperatures will not
reach 100, but upper 90s likely. An excessive heat watch will be
issued for the Wednesday through Sunday period.

Monday seems to be the real day in question when it comes to
precipitation. ECMWF brings the precip in on Sunday with Monday dry
while the GFS increases the clouds Sunday and brings the front
through on Tuesday.

&&

.AVIATION...
Issued at 655 PM CDT Mon Jul 17 2017

Mainly VFR conditions are forecast through Tuesday. Isolated storms
should dissipate this evening. A couple more are possible in the
heat of the day Tuesday, but coverage should be very sparse if any
develop. Patchy MVFR fog is expected after midnight, especially in
low lying areas and locations that received rainfall today. Cumulus
should be few to scattered again on Tuesday. Near calm winds tonight
will pick up from the west around 5 knots on Tuesday.

&&

.PAH WATCHES/WARNINGS/ADVISORIES...
IL...Excessive Heat Watch from Wednesday afternoon through Sunday
     evening for ILZ075>078-080>094.

MO...Excessive Heat Watch from Wednesday afternoon through Sunday
     evening for MOZ076-086-087-100-107>112-114.

IN...Excessive Heat Watch from Wednesday afternoon through Sunday
     evening for INZ081-082-085>088.

KY...Excessive Heat Watch from Wednesday afternoon through Sunday
     evening for KYZ001>022.

&&

$$

Short Term...CN
Long Term....PS
Aviation.....RJP



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