Hail and Damaging Winds in Illinois, August 25, 2014

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
314 PM CDT Mon Aug 25 2014

.SHORT TERM...(This evening through Tuesday)
ISSUED AT 312 PM CDT MON AUG 25 2014

Hot and very humid conditions are the rule across central Illinois
this afternoon, with 19z/2pm temperatures in the lower to middle 90s
across the board.  Further north, clusters of thunderstorms have
developed along outflow boundaries from eastern Iowa across
northern Illinois.  This convection is generally tracking eastward,
with a slight southeastward drift.  High-res models are once again
handling the convection quite poorly, with the 2-hr HRRR forecast
completely missing the storms currently ongoing south of Chicago.
The Chicago storm complex will continue developing E/SE into
northwest Indiana over the next couple of hours.  Meanwhile, we will
have to keep an eye on additional storms just north of Moline.
These cells will likely track E/SE along an outflow boundary evident
on satellite/radar imagery and should remain just north of the KILX
CWA.  Have included a slight chance PoP along/northeast of a Henry
to Danville late this afternoon into the early evening in case they
develop a bit further southward.

A cold front currently analyzed across central Iowa will gradually
push eastward over the next 12 to 24 hours, reaching the northern
KILX CWA by Tuesday morning.  Many of the 12z models show little or
no convection with the boundary overnight, but have included low
chance PoPs along/northwest of a Rushville to Bloomington line as
the front encounters a very moist airmass.  Aside from any scattered
convection that may develop, the potential for fog will once again
be an issue overnight.  Light/variable winds along with dewpoint
pooling along the boundary will favor fog, but increased mid/high
clouds may tend to mitigate it somewhat.  Based on an unchanged
airmass and persistence from the past several nights, have included
patchy fog in the forecast after midnight.

Any fog will dissipate early Tuesday morning, followed by partly to
mostly sunny conditions across the southern half of the CWA.
Further north in closer proximity to the nearly stationary frontal
boundary, mostly cloudy skies and scattered convection will keep
temps slightly cooler than they have been recently.  High temps on
Tuesday will range from the upper 80s north to the middle 90s
along/south of I-70.  Due to the slightly cooler temps, heat index
readings across the north may not reach advisory criteria.  May need
to drop the advisory for the Peoria area northward, as heat index
values will likely remain in the 95 to 100 degree range on Tuesday.

&&

.LONG TERM...(Tuesday night through Monday)
ISSUED AT 312 PM CDT MON AUG 25 2014

A frontal boundary will become somewhat stationary over the area and
is forecast to remain there through the rest of the week and into
the weekend. This will become the focus for thunderstorms throughout
the period. Thunderstorms will not be continuous throughout the
period, but trying to time when the dry, or drier, periods is going
to be is the main forecast challenge. Due to the difficulty of
timing the precip periods and the dry periods during the medium and
long ranges of the forecast, best to just have chance pcpn through
the period over the whole area. Will have likely pops in the north
third of the CWA for Tue night, but remainder of the forecast will
just be chance across the area.

With the frontal boundary getting into the area, relatively cooler
air will advect into the area. Temperatures will gradually drop back
to around normal, which is middle to upper 80s, by the weekend.
However, with all the moisture forecasted over the area, muggy/humid
conditions will continue through the period.

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
ISSUED AT 1248 PM CDT MON AUG 25 2014

Mostly sunny skies will prevail across central Illinois today, as
convection remains along/north of the I-80 corridor. Latest
satellite imagery shows clear skies across much of the area, with
just FEW-SCT diurnal clouds developing near KBMI and KCMI. Cold
front currently analyzed across central Iowa will drop
southeastward tonight, eventually settling into north-central
Illinois by Tuesday morning. With boundary approaching, winds will
go light/variable, once again setting up the potential for fog
overnight. Forecast soundings and numeric guidance support fog
development, so have included reduced visbys of 3 to 5 miles
between 08z and 14z. Am not expecting much in the way of
thunderstorm development through 18z, although have introduced a
mid-level cloud deck at KPIA as the front arrives late tonight
into Tuesday morning.

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
EXCESSIVE HEAT WARNING until 7 PM CDT Tuesday FOR ILZ042-047>054-
056-061>063-066>068-071>073.

HEAT ADVISORY until 7 PM CDT Tuesday FOR ILZ027>031-036>038-040-
041-043>046-055-057.

&&

SHORT TERM...BARNES
LONG TERM...AUTEN
AVIATION...BARNES

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE LINCOLN IL
344 PM CDT MON AUG 25 2014

ILZ027>031-036>038-040-041-261100-
FULTON-KNOX-MARSHALL-MASON-MCLEAN-PEORIA-SCHUYLER-STARK-TAZEWELL-
WOODFORD-
344 PM CDT MON AUG 25 2014

...HEAT ADVISORY IN EFFECT UNTIL 7 PM CDT TUESDAY...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL
ILLINOIS.

.DAY ONE...TONIGHT

THUNDERSTORMS WILL TRACK ACROSS NORTH-CENTRAL ILLINOIS EARLY THIS
EVENING. A FEW OF THE STORMS COULD PRODUCE GUSTY
WINDS...HAIL...AND TORRENTIAL RAINFALL ALONG AND NORTHEAST OF
I-74.

ADDITIONAL THUNDERSTORMS WILL BE POSSIBLE LATE TONIGHT AS A COLD
FRONT APPROACHES FROM THE NORTHWEST.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

HOT AND HUMID CONDITIONS WILL CONTINUE ON TUESDAY. HIGH TEMPERATURES
WILL CLIMB INTO THE LOWER 90S, WITH PEAK HEAT INDEX VALUES BETWEEN
100 AND 105 DEGREES.

THUNDERSTORM CHANCES WILL CONTINUE TUESDAY THROUGH SUNDAY, AS THE HEAT
GRADUALLY DIMINISHES.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT ANTICIPATED.

ILZ043>046-055-057-261100-
CHAMPAIGN-DE WITT-DOUGLAS-EDGAR-PIATT-VERMILION-
344 PM CDT MON AUG 25 2014

...HEAT ADVISORY IN EFFECT UNTIL 7 PM CDT TUESDAY...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL
ILLINOIS AND EAST CENTRAL ILLINOIS.

.DAY ONE...TONIGHT

THUNDERSTORMS WILL TRACK ACROSS NORTH-CENTRAL ILLINOIS EARLY THIS
EVENING. A FEW OF THE STORMS COULD PRODUCE GUSTY
WINDS...HAIL...AND TORRENTIAL RAINFALL ALONG AND NORTHEAST OF
I-74.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

HOT AND HUMID CONDITIONS WILL CONTINUE ON TUESDAY. HIGH
TEMPERATURES WILL CLIMB INTO THE LOWER 90S, WITH PEAK HEAT INDEX
VALUES BETWEEN 100 AND 105 DEGREES.

THUNDERSTORM CHANCES WILL RETURN TUESDAY NIGHT THROUGH SUNDAY, AS
THE HEAT GRADUALLY DIMINISHES.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT ANTICIPATED.

ILZ042-047>054-056-061>063-066>068-071>073-261100-
CASS-CHRISTIAN-CLARK-CLAY-COLES-CRAWFORD-CUMBERLAND-EFFINGHAM-
JASPER-LAWRENCE-LOGAN-MACON-MENARD-MORGAN-MOULTRIE-RICHLAND-
SANGAMON-SCOTT-SHELBY-
344 PM CDT MON AUG 25 2014

...EXCESSIVE HEAT WARNING IN EFFECT UNTIL 7 PM CDT TUESDAY...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL
ILLINOIS...EAST CENTRAL ILLINOIS AND SOUTHEAST ILLINOIS.

.DAY ONE...TONIGHT

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

HOT AND HUMID CONDITIONS WILL CONTINUE ON TUESDAY. HIGH TEMPERATURES
WILL CLIMB INTO THE LOWER TO MIDDLE 90S AND PEAK HEAT INDEX VALUES
WILL RISE TO BETWEEN 105 AND 110 DEGREES.

THUNDERSTORM CHANCES WILL RETURN TUESDAY NIGHT THROUGH SUNDAY,
AS THE HEAT GRADUALLY DIMINISHES.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT ANTICIPATED.

BARNES