Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

fxus63 kilx 190924 

Area forecast discussion
National Weather Service Lincoln Illinois
424 am CDT Sat Oct 19 2019

issued at 400 am CDT Sat Oct 19 2019

A cold front over central parts of Iowa and Kansas, will weaken
as it moves east into the Illinois River valley during mid and late
afternoon and dissipates during tonight as it moves into eastern
Illinois. Clouds will increase from the west during today, with
isolated to scattered showers expected from the Illinois River
valley northwestward this afternoon. Dry weather will persist
elsewhere. A stronger storm system will approach Illinois
overnight Sunday night and Monday, bringing a better chance of
showers and thunderstorms. Seasonably mild temperatures will
prevail across the area into Monday.


Short term...(today and tonight)
issued at 400 am CDT Sat Oct 19 2019

Early morning surface map shows a cold front extending from
eastern Minnesota into central parts of Iowa/Kansas to 1002 mb low pressure
over far SW OK. A band of mid level clouds was moving east toward
I-57 early today. Radar mosaic shows a few very light rain showers
or sprinkles in NE MO, while main band of showers and isolated
thunderstorms was in western IA, far NW MO and eastern KS/OK.
Temps at 4 am ranged from mid 30s to lower 40s in eastern Illinois to
the upper 40s and lower 50s along and west of I-55.

The latest cams continue to trend slower with the weakening front
and its showers moving east into the Illinois River valley during mid
afternoon into early evening. Eastern Illinois will enjoy more sunshine
this morning with clouds increasing there this afternoon. Not as
breezy today with south winds 5-15 mph. Highs today range from the
lower 60s by Galesburg to the lower 70s near Lawrenceville, with
upper 60s over the majority of central Illinois.

The weakening front is projected to approach I-55 by 00z/7 PM and
move into NW in and far se Illinois by sunrise Sunday. A few showers
may linger over the Illinois River valley from 6-9 PM this evening,
otherwise dry conditions expected tonight with partly to mostly
cloudy skies. Lows tonight in the upper 40s/lower 50s except lower
40s by Galesburg.


Long term...(sunday through friday)
issued at 400 am CDT Sat Oct 19 2019

A nice fall day in store on Sunday as central/se Illinois to enjoy
partly to mostly sunny skies and mild temperatures with gentle se
winds less than 10 mph. Highs Sunday in the upper 60s/lower 70s,
except mid 60s by Galesburg.

A storm system moving toward the Pacific northwest will emerge
over South Dakota/NE early Sunday evening and have strong cutoff upper level
low and associated surface low eject NE into SW Minnesota by sunrise
Monday. This will bring a cold front east into eastern Iowa/MO by
12z/7 am Monday. Models continue to keep County Warning Area dry thru 06z/1 am
Sunday night, then spread showers and some thunderstorms east over
area during overnight Sunday night and continue Monday morning,
before diminishing from west to east during Mon afternoon. A few
showers could linger in far eastern Illinois early Mon evening. Storm Prediction Center
day2 outlook keeps slight to marginal risk of severe storms over
SW MO and areas SW for Sunday night and Storm Prediction Center day3 outlook has
slight to marginal risk of severe storms se of County Warning Area on Monday.
Convective available potential energy only peak near 500 j/kg on Monday though 0-6 km bulk shear
values are quite high ranging from 50-80 kts. Some thunderstorms
could produce strong gusty winds on Monday. Breezy to windy
conditions expected Mon thru Tuesday. Moderate to locally heavy
rains also possible overnight Sunday night thru Mon with 1-1.5
inches possible in se Illinois while quarter to half inch amounts over
the Illinois River valley. Highs Mon range from lower 60s by Galesburg
to near 70f in eastern IL, with temps cooling after cold front
passage during the afternoon. Lows Sunday night in the mid 50s and
drop into the mid 40s for Mon night.

Strong upper level low and surface low pressure ejects NE into
Lake Superior by midday Tue. Strong west winds bring in much
cooler air into the area with gusts of 25-35 mph possible on Tue.
Highs Tue in the mid to upper 50s in central Illinois and around 60f in
southeast Illinois. Kept forecast dry on Tue though some model members
show wrap around light showers getting as far south as central
Illinois late Mon night and Tue morning. Low pressure departs toward SW
Hudson Bay Canada on Wed while 1023 mb high pressure settles over
the southeast states. Quiet fall wx expected for central Illinois Tue
night thru Wed night. Lows Tue night around 40f, with highs Wed
moderating into the low to mid 60s with increasing SW flow.

Still some model differences with handling next wx system Thu/Fri
and followed a blend this far out. Have slight chances of showers
over NW County Warning Area by Thu afternoon and then 20-30% pops shifting se over
the area Thu night, with slight pops in southeast Illinois overnight Thu
night. Lingered 20-30% pops of showers on Friday, highest in
eastern Illinois. Highs Thu range from mid 50s by Galesburg to mid 60s
se of I-70. A cold front to push se of central Illinois Thu afternoon
and Thu night, bringing reinforcing colder air to the area Thu
night and Friday. Highs Fri only in the low to mid 50s central Illinois
and upper 50s southeast Illinois and similar highs next Saturday. Lows
Thu night in the mid to upper 30s central IL, lower 40s se Illinois and
in the 30s next Sat night.

CPC 8-14 day outlook for Oct 26-Nov 1 has 60-70% chance of below
normal temperature over Illinois with 40-45% chance of below normal


Aviation...(for the 06z tafs through 06z Saturday night)
issued at 1150 PM CDT Fri Oct 18 2019

High pressure over the eastern Great Lakes will keep winds light
through the taf valid time. A weakening cold front will approach
the region Saturday afternoon and into the evening. As the
associated mid-level wave moves northeast of Illinois, forcing for
the system rapidly diminishes. It is possible that an isolated
shower might impact kpia around sunset, but by the time the front
moves to I-55 latest sref suggests that any pcpn will quickly
dissipate leaving only the potential for broken VFR ceilings. Will
include a vcsh for a short period at kpia, but keep other sites
dry given the low pops.


Ilx watches/warnings/advisories...


National Weather Service Glossary of Abbreviations