493
FXUS63 KPAH 271035
AFDPAH

Area Forecast Discussion
National Weather Service Paducah KY
535 AM CDT Tue Jun 27 2017

.SHORT TERM...(Today through Thursday night)
Issued at 322 AM CDT Tue Jun 27 2017

Main vorticity axis stretching from the closed upper low in the
eastern Great Lakes is in the process of working south of
I-70 around 08z. There will likely be one last enhancement of the
current convective activity along the southern AR/MO border before
12z (7am CDT) all of the precipitation works south of the WFO PAH
forecast area. With moisture loading the boundary layer and
radiational loss, there may also be some patchy fog develop over
Southeast Missouri before daybreak as well.

Ridging develops in the wake of the passing upper level trough
today and will persist through Wednesday afternoon. Zonal flow
developing behind the ridge will place the WFO PAH forecast area
just south of the faster flow to the north. At the same time,
weak troughing in the Lower Mississippi Valley will focus moisture
transport northward toward southern sections of the WFO PAH
forecast area, along with lift from a weak upper low progged along
the LA/TX coast by 7 am CDT Thursday.

The combination of the these two systems will create an
encroachment of a small chance of showers and thunderstorms near
the I-64 corridor of Southern Illinois/Southwest Indiana and
toward Southeast Missouri near the end of the short term forecast
period.

Overall, the short term will remain dry with temperatures moving
back toward normal values for this time of year.

.LONG TERM...(Friday through Monday)
Issued at 322 AM CDT Tue Jun 27 2017

The pre-Fourth of July weekend still looks quite stormy, though it
will not be a washout. A cold front will cross Missouri on Friday,
then lay out from west to east across the Lower Ohio Valley or
northern Tennessee as a stationary front Saturday. The front will
eventually return north as a warm front early next week. This front
will keep a prolonged period of precip chances in the forecast. As
usual for this time of year, there will likely be some locally heavy
rain in the warm/humid air mass. Specific timing of convection in
this type of pattern is always a challenge at long time ranges.

The most favorable time for an organized convective complex appears
to be Friday/Friday night, ahead of the cold front over Missouri.
Wind fields ahead of a fairly strong 500 mb shortwave approaching
the Mississippi Valley will be modestly strong for this time of
year. Saturday through Sunday, the low level flow will become light,
and the front may become difficult to locate amidst residual
convective boundaries. Convection over the weekend is likely to be
more disorganized, and areas north of the Ohio River could be mainly
dry if the front is forced south of Kentucky by convective outflows.
The front will return north of our region by late Monday. Depending
on the timing of another upstream 500 mb shortwave, organized
convection is possible again early next week.

Dew point pooling along the frontal boundary or its remnants will
result in dew points in the lower to mid 70s much of the weekend.
The moist and unstable air mass will be favorable for locally heavy
rain, but weak flow fields over the weekend should limit the
organization and areal coverage. Highs will range from the mid to
upper 80s each day, depending on the location and timing of storms.
Overnight lows will be around 70.

&&

.AVIATION...
Issued at 535 AM CDT Tue Jun 27 2017

VFR conditions will be the rule for the 12z Tuesday WFO PAH TAF
issuance as high pressure builds across the TAF locations.
Unrestricted ceilings and visibilities will the rule for most of
the forecast time period.

&&

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

$$

SHORT TERM...Smith
LONG TERM...MY
AVIATION...Smith