Area Forecast Discussion
Issued by NWS Paducah, KY

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FXUS63 KPAH 250747
AFDPAH

Area Forecast Discussion
National Weather Service Paducah KY
247 AM CDT Sun Jun 25 2017

.SHORT TERM...(Today through Tuesday night)
Issued at 246 AM CDT Sun Jun 25 2017

Forecast confidence for the Monday/Monday Night weather system is
above 60 percent, with the only caveat being the timing of the
greatest coverage of precipitation across the WFO PAH forecast
area.

The signal for the entrance and passage of precipitation across
the for late Monday and Monday night remains consistent. However,
the challenge for precipitation coverage lies with the evolution
of the sharpening trough rotating around the Great Lakes low
during the aforementioned time period. The blended model guidance
initialization did generate a higher PoP (probability of
precipitation) within the WFO PAH forecast area. Given the
sharpening of the baroclinic zone ahead of the middle/upper level
trough, had to consider raising PoP chances across a broader area
Monday evening, closer to the Canadian model solution.

Regardless of the model guidance used, there does not seem to be
much of a surface reflection of the upper trough, in fact, surface
high pressure remains dominant. Instability is also a factor. Used
a blend of GFS/Canadian lifted index values from Surface to 850 mb
bases to find most unstable air. This suggests that lapse rate
changes will be focused along channeled vorticity zones with the
cyclonic flow aloft.

Given the elevated nature of the precipitation, amounts should
remain relatively light across most of the WFO PAH forecast area.

Adjusted the regionally blended model guidance for sensible
weather elements to include a little more weighting from the NAM-
WRF model families, the Canadian, and GFS guidance.

.LONG TERM...(Wednesday through Saturday)
Issued at 246 AM CDT Sun Jun 25 2017

Decreasing confidence in the extended as a very unsettled weather
pattern is starting to take shape.

We start out the extended with fairly high confidence with respect
to temperature...humidity and lack of precip. After Wednesday
however confidence decreases mainly with precip chances and duration
of precip. Amounts are still meager so medium confidence with that
parameter. By Wednesday the upper high continues to drift off the
southeast coast of the US. While the flow aloft remains near zonal
until friday and Saturday when a subtle trough aloft will rotate
through the area. This will be our best chance of significant
rainfall. There is also a surface cold front to our northwest but at
this time it does not appear to make it through the area...as it
appears to lose intensity and southward progress. However with the
Gulf wide open for business this will allow for moisture to pool
over our area late this week and through the weekend. So there will
be thunderstorms over the area at least at times. Most likely during
the heat of the day but there is elevated instability overnight as
well. Wind shear remain fairly unidirectional through the weekend
and not all that strong with strongest winds 25 knots through most
of the column Friday. They decrease but remain unidirectional
through the weekend. Capes will range from 2-3k j/kg during the
afternoon hours this weekend...but decrease to 1k in the overnight
hours. In addition PW`s range from one and half to better than 2"
inches. So they will be very efficient rain producers where ever
they form. A severe storm cant be ruled out toward weeks
end...widespread severe is not anticipated at this time. Also with
freezing levels 15k feet and higher most any hail will melt before
reaching the surface. Finally trimmed pops back to chance category
for days 6 and 7.

&&

.AVIATION...
Issued at 1150 PM CDT Sat Jun 24 2017

The forecasts are VFR for the 06Z TAF period. The primary concern
will be northwest winds gusting up to around 20kts in the
afternoon.


&&

.PAH WATCHES/WARNINGS/ADVISORIES...
IL...None.
MO...None.
IN...None.
KY...None.
&&

$$

SHORT TERM...Smith
LONG TERM...KH
AVIATION...DRS


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