Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Lincoln Illinois
330 am CDT Fri Jul 11 2014
issued 330 am CDT Fri Jul 11 2014
Short term...today through Monday night
1024 mb high pressure over the central and eastern Great Lakes
region was still ridging into central/NE Illinois early this morning and
bringing another seasonably cool night with temps in the mid 50s
to lower 60s with fair skies and light to calm winds. High
pressure to drift east into New England this afternoon/evening
with return SSE flow developing over Illinois and starting to bring in
warmer and more humid air. 00z models continue to trend slower
with arrival of convection chances this afternoon/evening with
eastern Illinois likely staying dry while 20-30% chance of showers and
isolated thunderstorms over Illinois River valley this afternoon and evening.
Best chances of showers and thunderstorms appears to be after
midnight tonight especially over northern counties from mesoscale convective system with
heavy rains moving out of Iowa across northern Illinois. Storm Prediction Center keeps slight
risk area NW of Illinois tonight over NE and western Iowa. Highs today in
the low to mid 80s as skies become partly sunny with more clouds
NW over Illinois River valley and more sunshine in southeast Illinois where
mostly sunny skies prevail much of the day. Dewpoints to climb in
to the low to mid 60s this afternoon.
Convection chances will be highest over northern areas Saturday
while just isolated convection in southeast Illinois by Saturday afternoon.
Tropical airmass returns to Illinois with dewpoints back into the low to
mid 70s and highs in the mid 80s to around 90f Sat and Sunday.
Afternoon heat indices peak in mid to upper 90s this weekend which
is below heat advisory criteria. Storm Prediction Center has slight risk of severe
storms north of I-72 for mainly wind Saturday night with another
mesoscale convective system with short wave moving from Iowa across northern half of Illinois. Storm Prediction Center
has slight risk of severe storms from I-55 southeast Sunday
(mainly Sunday afternoon & early Sunday evening for wind) as cold front
pushes se thru central Illinois. Models have trended quicker with this
front from earlier runs so have cooled highs northern areas a bit
on Sunday but still mid 80s.
Best chances of showers and thunderstorms shifts into southeast Illinois
Monday and Monday night closer to frontal boundary pushing
southeast of Illinois. Highs range from 80f Illinois River valley to mid 80s in
southeast Illinois and still humid here with dewpoints in the lower 70s.
Long term...Tuesday through Friday
Extended models continue to show unseasonably strong cutoff low
digging southward from central Canada into the western Great Lakes
Monday night, and staying near the Great Lakes into middle of next week.
This to bring much cooler and less humid air into central Illinois with
highs in the low to mid 70s Tue (near 70f northern areas) and
slowly modifying thereafter. Can not rule out very isolated
afternoon showers each afternoon but chances appears less than 20%
so left them out of forecast for now. Highs to modify into upper
70s to near 80f late next work week.
issued 1132 PM CDT Thu Jul 10 2014
High clouds will spread into central Illinois from the northwest and
thicken overnight. From around 14-18z Friday, scattered cloud
cover around 4-5 kft mean sea level will develop due to increased low level
moisture. After 22-00z Saturday...chances for rain showers/thunderstorms and rain will
increase producing isolated MVFR ceiling/visibility and gusty
winds. Light east-southeast winds will gradually trend southeast to S over the next
12 hours as a storm system develops over the Central Plains and
high pressure moves off to the east.