Area Forecast Discussion
Issued by NWS Central Illinois

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335
FXUS63 KILX 301753
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
1253 PM CDT Sun Apr 30 2017

.UPDATE...
Issued at 1100 AM CDT Sun Apr 30 2017

Will continue the Flash Flood watch through tonight east of the IL
river with up to an additional 1 inch of rain expected through
this evening with locally 1.5-2 inch amounts from heavier
thunderstorms. Already have several counties still with an area
flood warning today near the IL river and from I-72 south along
with several rivers in flood. Latest radar mosaic shows next batch
of showers and a few embedded thunderstorms lifting northward
toward I-72 at late morning and to overspread areas north of I-72
into early afternoon. The warm front was starting to lift
northward and was approaching I-72 at 11 am and latest models lift
the warm front northward acorss northern CWA during the afternoon
as 997 mb surface low pressure in central KS lifts ne. SPC day1
outlook continues slight risk of severe storms across CWA this
afternoon and evening, mainly after 3 pm until midnight. Cold
front to push east across central IL during this evening and
continue severe wx and heavy rain threat. Highs today to range
from the lower 60s by Galesburg to the mid to upper 70s in
southeast IL.

&&

.SHORT TERM...(Today and tonight)
ISSUED AT 323 AM CDT Sun Apr 30 2017

Upper low deepening over the Southern High Plains this morning
driving the weather through the short term as it amplifies the
flow across the country. Stationary boundary stretching across
Central IL out ahead of the main surface low on the OK/KS border
this morning keeping a bit of convergence in the wind field and
plenty of focus for the rich moisture feeding into the region.
Heavy rainfall across the Midwest prolonging the flooding concern
for the region and no changes anticipated in the Flash Flood Watch
for ILX.

Other than flooding, and northern drift of the boundary as a warm
front making the daytime highs surge ahead of where they were
yesterday...the main concern is how much of a chance the airmass
over Central and Southeastern IL is able to recover in the breaks
in the precip this morning/midday. HRRR and NAM both coming in
with enough of a break to see the CAPE push back over 1000-1500
J/kg with max heating later this evening ahead of the low moving
NW of ILX and into the Great Lakes. Considering the rapid
intensification of the low, SPC has left most of IL in a slight
risk through today and this evening.

.LONG TERM...(Monday through Saturday)
ISSUED AT 323 AM CDT Sun Apr 30 2017

Monday will still maintain low pops, mainly in the northern half
of the state for some residual showers in cyclonic
flow/instability showers through the afternoon. Temperatures
considerably cooler again with highs in the 50s for Monday.
Westerly flow out of the warmer temps in the SW and plenty of
sunshine provides some warmer temps for Tuesday...then drop again
for Wed as another quick wave brings clouds/precip midweek
briefly. Models having a rough time with the details on the back
end of the precip Wed night/Thursday.  Temperatures start an
extremely slow warm up back to the mid 60s by the end of the week.
Pattern shift from mid week to the end of the week still a bit of
inconsistency in handling the next weather maker.

&&

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 1255 PM CDT Sun Apr 30 2017

A warm front near I-72 will lift toward the IL river by PIA during
this afternoon and spread an area of showers and a few
thunderstorms northward from I-72 to PIA and BMI. Ceilings of
200-500 ft at BMI, PIA and SPI should lift to MVFR by mid or late
afternoon as warm front lifts northward. Deepening 996 mb surface
low pressure over central KS will lift ne to central IA by 06Z/1
am tonight and deepen to 990 mb over northcentral IL by early
Monday afternoon. This will swing a cold front east over central
IL during this evening with showers/thunderstorms ending behind
the front. Some light rain showers are expected on Monday
especially at BMI and PIA with MVFR ceilings. ENE winds at PIA and
BMI will switch to the SSE during the afternoon and then SW during
tonight into Monday. Winds will gusts to 20-35 kts at times this
afternoon and again on Monday.

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch through Monday morning for ILZ029>031-037-038-
041>050-052>057-061>063-066>068-071>073.

Flash Flood Watch through Monday evening for ILZ051.

&&

$$

UPDATE...07
SHORT TERM...HJS
LONG TERM...HJS
AVIATION...07



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