Area Forecast Discussion
Issued by NWS Paducah, KY
FXUS63 KPAH 251922
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PADUCAH KY
222 PM CDT Fri Jul 25 2014
.SHORT TERM...(Tonight through Sunday night)
Issued at 221 PM CDT FRI JUL 25 2014
Although the current MCS (Mesoscale Convective System) should
rapidly decay this afternoon, there is still some concern
associated with the thunderstorm complex west of the St. Louis
area. There continues to be a feed of decent thet-a air into this
complex, so the dissipation rate of this system may be slowed slightly.
The effective location of the warm front shifted slightly further
northeast, shifting the southern limit of convection further
north on Saturday. This northern push of instability has trended
toward the removal of any precipitation within the WFO PAH CWA for
the remainder of tonight and into early Saturday. The effective
start time for convection along the I-64 corridor has shifted
beyond 21z on Saturday. There will be a sharp gradient where
capping aloft behind the warm front will negate any effective
The real challenge is balancing cloud cover and winds in advance
of an MCS on Saturday and Saturday night. This will have some
impact on heat index values during the early afternoon across
Southwest Illinois. Given the uncertainty regarding the duration
of heat index values approaching 105 degrees, plan to issue a
Special Weather Statement in lieu of a Heat Advisory. Plan to
continue highlighting higher heat indexes in the Hazardous Weather
Outlook as well.
.LONG TERM...(Monday through Friday)
Issued at 1254 PM CDT FRI JUL 25 2014
It is amazing to look at the pattern transition for next week,
considering the late July-early August time frame. The models
still develop the broad upper level troffing over the eastern
U.S., with the Low nearly cut off as it centers somewhere in the
vicinity of the mid Mississippi valley by next weekend.
The end result is going to be an abundance of pleasant weather
conditions with high confidence much below normal temps/pcpn for
the week long period.
The first half of the workweek will see surface High pressure
coming in from the north and all but keeping some flow of
northerlies reinforcing the atmosphere. This will help skies to
stay moclear with low humidity highs in the upper 70s and lower
80s and crisp lows in the upper 50s to lower 60s.
By the middle to latter part of the workweek, the surface High
shifts eastward, and we`re in a somewhat muddier easterly or
southerly lower tropospheric flow. This still means relatively low
dew points, with a move from the 50s early in the week to no more
than the lower 60s by the weeks end. But it could be just enough
return moisture to allow for a spotty shower or two to develop by
Friday, as the upper Low center drops down and introduces itself
into our FA/vicinity. Slightly moderated Highs in the lower to
middle 80s and lows in the lower 60s will remain comfortably
below climo norms.
Issued at 124 om CDT FRI JUL 25 2014
To users of the WFO PAH TAF`s, sent incorrect forecasts earlier,
but reissued corrected TAFs around 1817z.
Cirrus blowoff from convective activity upstream over West Central
Illinois and East Central Missouri will dominate VFR cloud cover
forecast for the WFO PAH TAF sites this afternoon, thinning out
this evening over KCGI/PAH. A middle level deck will likely remain
dominant over KEVV/KOWB during the evening.
Otherwise, most of the convection should remain just north of the
KEVV/KOWB TAF sites before 18z Saturday, so only mentioned a
vicinity chance for showers at this time. Most cloud cover should
remain at or above the forecast limits of the KCGI/KPAH TAF sites,
so kept unrestriced ceilings in place at this time.