Area Forecast Discussion
Issued by NWS Paducah, KY

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042
FXUS63 KPAH 300707
AFDPAH

Area Forecast Discussion
National Weather Service Paducah KY
207 AM CDT Tue May 30 2017

.SHORT TERM...(Today through Thursday night)
Issued at 200 AM CDT Tue May 30 2017

Scattered convective showers continue making their way across our
southern counties this early morning, influenced by pinwheel of
energy around base of mean long wave trof. That is just enough to
tap the couple hundred J/KG MU CAPE in the lowest 1 KM to set off
this pocket of showers/embedded isolated storms. The HRRR models
this almost perfectly, and diminishes it by 12Z, with a silent
Pops pause in the 12Z-18Z time frame. HRRR and medium range models
(GFS/NAM) then all agree that convection will reignite during the
heating hours of the pm, potentially influenced by outlflows
layed out from Plains convection. Another pinwheel of energy will
be occurring then, around the base of the mean upper long wave
trof, and combined with the differential heating of the pm hours,
will be assisted with 0-1KM MU CAPES in the 1000-2000 J/KG range.
These scattered Pops will persist into and even thru the overnight
hours, as the 70-80 KTS of upper level westerlies drives a weak
meso Low/front across the FA by 12Z Wed.

In the wake of this passage, we`ll see surface high pressure start
to work in on the backside of the primary upper vortex. Rimfire
pops notwithstanding, this will infiltrate slightly drier air to
the column, providing a (mainly) dry Wed. The center of the
surface High then shifts east of the Tn valley by 12Z Thursday,
and return flow southerlies assisted by a developing warm front
will support another intro of small pops into/thru the overnight
hours Thursday, to close out the short term forecast.

Upper 70s-lower 80s, and upper 50s-lower 60s, will generally be
the rule for Highs/Lows thru the period, which is near climo norms
for this time of year. Thursday warm sectoring will be the warmest
day, pushing toward mid 80s and mid 60s.

.LONG TERM...(Friday through Monday)
Issued at 200 AM CDT Tue May 30 2017

The primary forecast concern in the extended is the periodic chance
for showers and thunderstorms from Friday into the weekend. Forecast
confidence starts off higher than average with fairly good model
agreement, but falls off over the weekend with greater model
variability.

Starting with Friday morning, a rather weak zonal/southwesterly flow
pattern will be in place across the middle of the country with a
weak low pressure trough over the central and southern Plains. Broad
southerly flow will characterize the lower levels with high pressure
over the southeastern states and low pressure in the Plains. Gulf of
Mexico moisture will be on the increase through late week as the
Plains troughiness shifts east with time. This will result in
periodic chances for showers and thunderstorms Friday and Friday
night.

Shower and thunderstorm potential will be heightened by Saturday and
Saturday night as stronger shortwave energy and an associated low
pressure system approach from the Upper Midwest. Latest 00Z models
disagree on the timing of frontal passage late in the weekend. As a
result, the peak rain chance and subsequent return to dry weather is
still in flux. At this time, we prefer a model consensus, which
brings the cold front through the area on Sunday. Once the front
makes passage, a return to dry weather is expected by Monday as high
pressure builds south from Canada.

Temperatures through much of the extended are forecast to be near
normal during the day with highs in the 80s, and above normal at
night with lows in the mid to upper 60s owing to the humid air mass.
Behind the front, highs should cool into the 70s as lows drop back
into the 50s.

&&

.AVIATION...
Issued at 200 AM CDT Tue May 30 2017

High based Cu with mid to high level clouds atop will be featured
in this set of primarily VFR TAFs. The exception will be with
diurnally enhanced Pops, which are thus far low enough to preclude
mention or appear as vicinity. If a shower/storm impacts a
terminal this pm or evening, restrictions to VSBYS and possibly
CIGS could result, and may be included, in some form or fashion,
in the next issuance.

&&

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

&&

$$



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