Special Weather Statement, NWS Lincoln, IL

Area Forecast Discussion
National Weather Service Lincoln IL
1215 PM CDT WED AUG 3 2016

.UPDATE...
Issued at 1000 AM CDT Wed Aug 3 2016

Remnants of morning convection to our south lingers over the far
southeast CWA, but continues to fade. Earlier fog from Decatur
northwestward has lifted, but low clouds linger, with only the
northeast edges of the CWA seeing decent amounts of sunshine so
far. Main question for the rest of the day will be whether any
lingering boundaries manage to trigger any additional convection.
HRRR mainly concentrates this potential over areas along and south
of I-72 near some very subtle boundaries, but have maintained some
slight chances to the north mainly for the afternoon hours. Little
change made to temperatures at this time, with highs mainly 85-88
degrees.

&&

.SHORT TERM...(Today and tonight)
ISSUED AT 320 AM CDT Wed Aug 3 2016

Short-wave trough evident on 07z/2am water vapor imagery over
southeast Iowa has triggered a cluster of thunderstorms along a
stationary frontal boundary across central/eastern Missouri early
this morning.  The storms are pushing eastward and are currently
crossing the Mississippi River near and north of Saint Louis.  Now
that the nocturnal convection has materialized, the HRRR seems to
have a decent handle on its evolution...tracking it eastward along
the southern periphery of the KILX CWA over the next couple of
hours, then into the SE CWA south of I-70 in a weakening state by
mid to late morning.  Have therefore confined highest PoPs to
locations along and south of a Rushville...to Decatur...to
Marshall line.  Think areas further north will likely remain dry,
but cannot rule out a stray shower as the short-wave tracks slowly
southeastward today.  As a result, have gone with just slight
chance PoPs along/north of I-74.  As has been the case for the
past several mornings, fog has developed across much of the area,
especially where rain fell yesterday.  An SPS highlighting the
fog has been issued, and will continue to monitor visby trends
over the next few hours to determine if a Dense Fog Advisory will
be needed across part of the area.

As the wave sinks further southeast, synoptic subsidence in its wake
will lead to dry conditions tonight across all but the far SE CWA
where low chance PoPs are still warranted.  With skies clearing,
winds remaining light, and plenty of boundary layer moisture in
place, think fog will develop again tonight.  Have therefore
included patchy fog across the board after midnight.

.LONG TERM...(Thursday through Tuesday)
ISSUED AT 320 AM CDT Wed Aug 3 2016

As an upper low currently over the Northern Rockies tracks eastward
along the US/Canada border, downstream ridging will lead to a hot
and dry day on Thursday.  High temperatures will reach the lower
90s, while dewpoints in the middle 70s will create afternoon heat
index values in excess of 100 degrees.  A Heat Advisory may
therefore be required for all or part of the area on Thursday,
perhaps extending into Friday south of I-70.

As the wave digs into the Great Lakes, it will push a cold front
into central Illinois on Friday.  00z Aug 3 models are in good
agreement with FROPA timing during the afternoon.  While the airmass
ahead of the front will become moderately unstable with SBCAPE
values of 2000-3000J/kg, 0-6km bulk shear will remain quite weak at
only around 20-25kt.  As a result, severe weather potential will be
low.  Good convergence along the boundary and precipitable water
values of 2.00-2.25 suggest scattered thunderstorms with locally
heavy rainfall and perhaps some gusty wind.  Have gone with high
chance PoPs accordingly.

Based on amplitude of Great Lakes upper wave noted on the GFS/ECMWF,
it now appears the front will sink further southward and stall
along/south of the Ohio River this weekend.  As a result, both
Saturday and Sunday are looking cooler and mostly dry.  As a
persistent upper high centered over the southern Plains builds
northward early next week, the boundary will lift back northward as
well.  While model consensus focuses most of the precip further
west, will carry slight chance PoPs everywhere beginning Sunday
night.  Will also have to keep an eye on potential nocturnal storm
complexes developing and tracking along the periphery of the
building ridge, as the ECMWF is showing a system for both Sunday
night and Monday night.  Exact track/evolution of these systems is
too difficult to pinpoint this far out, so will keep rain chances at
a minimum for now, but these may need to be raised as the time
approaches.  Main story next week will be a return to hot and humid
conditions as the upper ridge ridge builds into the Midwest.

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 1212 PM CDT Wed Aug 3 2016

Some lower MVFR ceilings lingering in spots at midday, but general
trend continues for cloud heights to rise and VFR conditions
should soon prevail into the evening. Overnight, have included
some MVFR visibilities in light fog at KPIA/KSPI, due to light
winds and little atmospheric changes. Included only a TEMPO period
further east for now, with a little more uncertainty as to how
fast the clouds will fade this evening.

&&

.ILX Watches/Warnings/Advisories...
NONE.
&&

UPDATE...Geelhart
SHORT TERM...Barnes
LONG TERM...Barnes
AVIATION...Geelhart

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE LINCOLN IL
1122 AM CDT WED AUG 3 2016

ILZ027>031-036>038-040>043-047>051-041100-
CASS-DE WITT-FULTON-KNOX-LOGAN-MARSHALL-MASON-MCLEAN-MENARD-
MORGAN-PEORIA-SANGAMON-SCHUYLER-SCOTT-STARK-TAZEWELL-WOODFORD-
1122 AM CDT WED AUG 3 2016

THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL ILLINOIS.

.DAY ONE...THIS AFTERNOON AND TONIGHT

ISOLATED THUNDERSTORMS ARE POSSIBLE THIS AFTERNOON...BUT THESE ARE
NOT EXPECTED TO BE SEVERE.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

DRY CONDITIONS ARE EXPECTED UNTIL LATE THURSDAY NIGHT...WHEN
THUNDERSTORM CHANCES RETURN AND LINGER INTO FRIDAY NIGHT.
A SLIGHT CHANCE FOR THUNDERSTORMS WILL CONTINUE OVER THE WEEKEND
AND INTO EARLY NEXT WEEK. THE PROBABILITY FOR ORGANIZED SEVERE
WEATHER APPEARS LOW AT THIS TIME.

HEAT INDEX VALUES WILL LIKELY REACH 102 TO 105 DEGREES ON
THURSDAY. THIS WILL INCREASE CHANCES FOR HEAT RELATED ILLNESS
DURING PROLONGED OR STRENUOUS OUTDOOR ACTIVITY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT ANTICIPATED THROUGH TONIGHT.

ILZ044>046-052>057-061>063-066>068-071>073-041100-
CHAMPAIGN-CHRISTIAN-CLARK-CLAY-COLES-CRAWFORD-CUMBERLAND-DOUGLAS-
EDGAR-EFFINGHAM-JASPER-LAWRENCE-MACON-MOULTRIE-PIATT-RICHLAND-
SHELBY-VERMILION-
1122 AM CDT WED AUG 3 2016

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

.DAY ONE...THIS AFTERNOON AND TONIGHT

SCATTERED THUNDERSTORMS WILL BE POSSIBLE THIS AFTERNOON AND
EVENING...WITH THE THREAT LINGERING OVERNIGHT SOUTH OF I-70. NO
SEVERE WEATHER IS ANTICIPATED...BUT SOME STORMS MAY PRODUCE
LOCALLY HEAVY RAIN.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

DRY CONDITIONS ARE EXPECTED THROUGH THURSDAY NIGHT...THEN
THUNDERSTORM CHANCES RETURN FRIDAY AND LINGER THROUGH FRIDAY
NIGHT. DRY CONDITIONS ARE EXPECTED OVER THE WEEKEND THEN SLIGHT
CHANCES FOR THUNDERSTORMS RESUME EARLY NEXT WEEK. THE PROBABILITY
FOR ORGANIZED SEVERE WEATHER APPEARS LOW AT THIS TIME.

HEAT INDEX VALUES WILL LIKELY REACH 97 TO 102 DEGREES ON
THURSDAY...AND 97 TO 105 FRIDAY. THIS WILL INCREASE CHANCES FOR
HEAT RELATED ILLNESS DURING PROLONGED OR STRENUOUS OUTDOOR
ACTIVITY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT ANTICIPATED THROUGH TONIGHT.

GEELHART

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE LINCOLN IL
300 PM CDT WED AUG 3 2016

ILZ041>043-048-051>053-061-032300-
SHELBY-MACON-DE WITT-SANGAMON-CHRISTIAN-MASON-MENARD-LOGAN-
300 PM CDT WED AUG 3 2016

...FUNNEL CLOUDS SIGHTED OVER MACON AND LOGAN COUNTIES...

JUST BEFORE 3 PM...FUNNEL CLOUDS WERE REPORTED BY THE PUBLIC AND
EMERGENCY MANAGEMENT OFFICIALS BETWEEN DECATUR AND LATHAM.

ATMOSPHERIC CONDITIONS EXIST ACROSS THE AREA TODAY THAT FAVOR THE
POSSIBLE FORMATION OF WEAK CIRCULATIONS...ALONG AN EXISTING BOUNDARY.
SOME OF THESE CIRCULATIONS ARE OCCURRING UNDERNEATH DEVELOPING
SHOWERS AND THUNDERSTORMS...WHERE A FUNNEL CLOUD MAY DEVELOP. ONCE THE
RAIN BEGINS...THE FUNNEL CLOUD DISSIPATES.

LOW HANGING CLOUDS CAN ALSO APPEAR TO DIP UP AND DOWN AT TIMES...BUT
THEY WILL NOT SHOW SIGNS OF ANY RAPID ROTATION. AN ACTUAL FUNNEL
CLOUD WILL EXHIBIT SPINNING IN A COUNTER CLOCKWISE DIRECTION.

IN RARE INSTANCES...THESE FUNNELS MAY BRIEFLY TOUCH DOWN. STAY
ALERT... AND BE PREPARED TO MOVE TO A SAFE SHELTER...IF A FUNNEL
CLOUD APPROACHES THE GROUND.

LAT...LON 4012 9004 4018 8879 3931 8885 3931 8914
      3935 8914 3935 8953 3952 8954 3952 8993
      3957 8993 3972 8999 4009 9000 4011 9001

GEELHART