Area Forecast Discussion
Issued by NWS Paducah, KY

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FXUS63 KPAH 280447
AFDPAH

Area Forecast Discussion
National Weather Service Paducah KY
1147 PM CDT Wed May 27 2020

.UPDATE...
Issued at 1147 PM CDT Wed May 27 2020

Made some minor adjustments to PoP and Weather grids to capture
the latest tstm trends. Also updated aviation discussion.

&&

.SHORT TERM...(Tonight through Friday night)
Issued at 314 PM CDT Wed May 27 2020

The nearly vertically stacked closed low poised along the Oklahoma
and Arkansas border is entraining some drier air around the
southeast quadrant of the low at this time. With minor vorticity
advection intersecting this drier air, anticipate some overturning
of parcels along the moisture gradient over southeast Missouri,
which should continue to develop isolated to scattered convection
over southeast Missouri and southwest Illinois. This will likely
advect into southeast Missouri, west Kentucky, and southwest
Indiana later this afternoon. Moisture should not been an issue
with most of the area seeing layer precipitable water values of
1.5 to 1.8 inches, some 120 to 160 percent above normal for this
time of year. Although efficient moist adiabatic parcel lift
should produce copious amounts of precipitation this afternoon and
this evening, the main limitation will be instability for strong
updraft development as we move into the late afternoon and evening
hours.

Once the upper low center begins to move and settle into southeast
Missouri Thursday afternoon, will see increasing lift generally
along and east of the Mississippi river after midnight tonight and
through the midday on Thursday. Some enhanced lift will likely
occur Thursday afternoon and evening, as the upper low begins to
shear out and lift northeast across the area. The mean trough
axis will likely move east of the area by midday Friday, bringing
an end to the precipitation from west to east.

Hourly temperatures will be somewhat tricky to address this
afternoon and again Thursday afternoon, as the degree of
insolation, low level mixing, and cloud cover will generate
larger gradients of temperature through the daytime hours.

.LONG TERM...(Saturday through Wednesday)
Issued at 314 PM CDT Wed May 27 2020

Above average confidence in the extended due to good model agreement.

The upper level pattern through the majority of the extended period
will feature northwest flow across the lower Ohio Valley. Ridging
will be primarily focused to our west across the Rockies/Plains with
downstream troughing over the eastern U.S. While we currently don`t
have any PoP chances in Saturday through Wednesday, northwest flow
is notorious for these weak disturbances rippling through. The
timing and placement of these are very challenging to depict this
far in advance. However, if we do manage to receive any
precipitation it would likely be quite light and not widespread.

The main story this weekend will be the drier airmass in place along
with a good amount of sunshine. Dew points look to only be in the
50s Saturday through Monday, providing a welcome change to our
recent humid airmass. Temperatures will also be below normal with
highs only reaching the 70s and lows dipping into the 50s through
Monday.

As the upper ridge to our west begins to shift eastward and we
develop southerly flow on the backside of surface high pressure, a
warming trend commences heading into the middle of next week. High
temperatures will jump back into the 80s by Tuesday and even warmer
upper 80s on Wednesday. An increase in humidity levels will also
occur with dew points back into the mid 60s on Wednesday. Enjoy the
break from the summer heat and humidity while it lasts!

&&

.AVIATION...
Issued at 1147 PM CDT Wed May 27 2020

Overall conditions are expected to remain VFR for most of the region
through the 06Z TAF period, with the exception of patches of MVFR
cigs in western KY and southwestern IN in shower activity near
daybreak and for a few hours afterward. Though difficult to pin
down, the best guess of timing of scattered tstm activity in general
appears to be in the afternoon, primarily for the western TAFs, with
the usual brief reductions in vsbys and lower cloud layers
associated with convection.  Light southeasterly winds will gain
more of a southerly component after daybreak.

&&

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

$$

SHORT TERM...Smith
LONG TERM...SP
AVIATION...DB


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