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Area forecast discussion 
National Weather Service Lincoln Illinois
1043 am CDT Tuesday Apr 28 2015

issued at 1043 am CDT Tuesday Apr 28 2015

Skies are clear and temperatures will continue to rise the
remainder of the day as high pressure remains in control of the
weather across the area. Current forecast is on track so no
update planned at this time.


Short term...(today)
issued at 303 am CDT Tuesday Apr 28 2015

Another chilly start to the day is on tap...with middle 30s and
patchy frost to start the day north of I-74. A surface ridge axis
extending across Illinois from NE to SW will provide subsidence
and relatively dry air. The hrrr and rap continue to show slightly
higher moisture in the 850-925mb layer across our eastern
counties...which is also supported by the NAM and GFS. Fair
weather cumulus formation will be more concentrated there... but
sunshine should still be the rule for the day in most areas. High
temperatures should reach the middle 60s near Indiana and the upper 60s west
of the Illinois River. Forecast soundings show mixing heights will
peak between 11 am and 1 PM...which will coincide with our higher
wind gusts for the day. A few gusts may reach 16-17 miles per hour... but
overall winds should be less gusty than the last couple of days.

Long term...(tonight through monday)
issued at 303 am CDT Tuesday Apr 28 2015

Initial concern for this part of the forecast is with rain potential
middle week. Upper trough currently pushing through the Dakotas
northeast to Hudson Bay prognosticated by all models to carve out a
sizable clouds low over Ontario on Wednesday...dropping southward
into the Midwest by Thursday morning. GFS is a bit further east with
this projection...with general model consensus favoring a path along
the Illinois/Indiana border. Have introduced some showers into the
forecast for Wednesday cold core with the upper low
(500 mb temperatures dipping below -20c) introduces some steep lapse
rates. Also mentioned some isolated thunder as well. Have lingered
some slight chance pop's across the eastern County Warning Area into Wednesday
night. With the low settling into the Ohio Valley on Thursday...have
also mentioned some scattered showers east of I-57 closer to the low

Further out in time...upper flow shifts more zonal to start the
weekend. Both the GFS and European model (ecmwf) showing a trough moving along the
Canadian border...with the European model (ecmwf) developing more of a broadening
early next week while the GFS remains a bit more progressive and
closer to the border. Still not very good agreement with rain
potential on Saturday...and have pulled back some on the pop's.
Saturday night...have followed more of the European model (ecmwf) solution of a
potential mesoscale convective system system rolling through the area overnight into Sunday.
Rain chances persist into early next week as the broadening trough
approaches the Mississippi Valley.

The general idea for temperatures will be with warming conditions...
although a brief cooldown is expected Thursday as 850 mb
temperatures dip closer to 0c as the upper low passes. Highs should
reach into the middle 70s across the area this weekend and early next


Aviation...(for the 12z tafs through 12z Wednesday morning)
issued at 642 am CDT Tuesday Apr 28 2015

VFR conditions will continue over the next 24 hours. High
pressure centered just northeast of Illinois will keep cloud cover
at a minimum. Higher moisture content over Indiana could push a
few more clouds over cmi and Dec, while the other terminal sites
remain relatively cloud-free. Forecast soundings show northeast
winds will be less gusty today, with peak wind gusts of 15kt
generally between 16z-19z. Wind speeds will decrease to 5 kts or
less after 00z, as boundary layer winds decouple from the middle-
level winds.


Ilx watches/warnings/advisories...


short term...shimon
long term...geelhart

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