Area Forecast Discussion
Issued by NWS St. Louis, MO
FXUS63 KLSX 261741
AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
1241 PM CDT Tue Aug 26 2014
Issued at 1029 AM CDT Tue Aug 26 2014
Minor update to grids and products to reflect wind shift and band
of clouds associated with an outflow boundary moving through
MO/IL. The temporary cloudiness with the outflow is not expected
to significantly change the forecast high temperatures for today.
.SHORT TERM: (Through Late This Afternoon)
Issued at 323 AM CDT Tue Aug 26 2014
Frontal boundary beginning to make its way south towards forecast
area today. Main issues today will be cloud cover, precipitation
and how this affects temperatures/heat indices. For now feel that
activity will be isolated/scattered in nature today, especially
during the afternoon hours. So there should be enough sunshine for
temperatures to rise into the mid to upper 90s once again, with
low 90s in the far north closer to the boundary. Even though
frontal boundary to eventually wash out along I-70 corridor late
this afternoon, dewpts to pool along this boundary keeping heat
indices in the 100 to 110 degree range, so headlines to remain
through 01z Wednesday.
.LONG TERM: (Tonight through Monday)
Issued at 323 AM CDT Tue Aug 26 2014
Some question tonight on low temperatures. Guidance is a bit too low
so went a few degrees above for overnight lows as dewpts remain in
the low 70s most locations. Keep pops going everywhere early this
evening as diurnal activity to linger a bit past 00z Wednesday, then
activity refocuses back to the north on nose of LLJ later tonight.
Will see a series of shortwaves slide east northeast through
region Wednesday through Friday, with best chances of storms over
northern half of cwa through Friday. Highs on Wednesday will be in
the upper 80s to mid 90s, so could see heat indices near 100 once
again. So depending on cloud cover, precipitation and dewpts, may
have to extend heat headlines a bit longer, but will leave as is
Then main weather system to slide through region beginning Friday
night with best chances of rain Saturday and Saturday night.
Temperatures to slowly lower through the rest of the forecast
period, eventually highs will only be in the 80s by the weekend and
into early next week.
.AVIATION: (For the 18z TAFs through 18z Wednesday Afternoon)
Issued at 1218 PM CDT Tue Aug 26 2014
Specifics for KCOU, KUIN: The outflow boundary which produced
brief periods of IFR-MVFR cigs earlier today has pushed south of
the terminals. VFR conditions are expected for the remainder of
the afternoon unless an isolated thunderstom develops during peak
heating. Overnight convection is possible at KUIN, but confidence
is too low to include in the TAF at this time.
Specifics for KSTL, KSUS, KCPS: VFR for most of the period. Will
continue to monitor for SH/TS development during peak heating due
to the outflow boundary near the St. Louis metro area terminals.
Overnight convection which is expected to develop north of the
terminals may sink farther south than currently anticipated.
MO...HEAT ADVISORY until 8 PM CDT this evening FOR Audrain MO-Boone
MO-Callaway MO-Cole MO-Crawford MO-Franklin MO-Gasconade MO-
Iron MO-Knox MO-Lewis MO-Madison MO-Marion MO-Moniteau MO-
Monroe MO-Montgomery MO-Osage MO-Ralls MO-Reynolds MO-
Shelby MO-St. Francois MO-Ste. Genevieve MO-Warren MO-
EXCESSIVE HEAT WARNING until 8 PM CDT this evening FOR Jefferson
MO-Lincoln MO-Pike MO-St. Charles MO-St. Louis City MO-St.
IL...HEAT ADVISORY until 8 PM CDT this evening FOR Adams IL-Brown IL.
EXCESSIVE HEAT WARNING until 8 PM CDT this evening FOR Bond IL-
Calhoun IL-Clinton IL-Fayette IL-Greene IL-Jersey IL-
Macoupin IL-Madison IL-Marion IL-Monroe IL-Montgomery IL-
Pike IL-Randolph IL-St. Clair IL-Washington IL.