Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 171712

Area Forecast Discussion
National Weather Service Lincoln IL
1212 PM CDT Fri Mar 17 2017

Issued at 944 AM CDT Fri Mar 17 2017

Convection that produced the hail earlier this morning has largely
crossed into southwest Indiana, with some residual drizzle or very
light rain generally east of I-55. Main cold front is still off to
our west and is moving through eastern Iowa and northwest Missouri
late this morning. This remains on track to cross the forecast
area during the afternoon hours. Large area of clearing seen on
satellite imagery crossing the Iowa/Illinois border, but some
stratus is starting to advect southeast into central Iowa.
Currently thinking that should stay to our northwest, and will
continue with the trend of skies becoming mostly sunny during the
afternoon across central and western parts of the CWA. Scattered
showers will linger over the east and southeast areas, until the
front arrives toward mid afternoon.

Updated zones/grids issued mainly to incorporate the latest
precipitation and sky trends.


.SHORT TERM...(Today and tonight)
ISSUED AT 315 AM CDT Fri Mar 17 2017

08z/3am surface analysis shows 1009mb low over western Iowa with
warm front extending southeastward into central Illinois.  Scattered
light rain showers have developed along/north of the boundary early
this morning, primarily across the northern KILX CWA.  As warm
advection forcing increases, showers will become more widespread
between 09z and 15z, as evidenced by the NAM/HRRR/WRF-ARW solutions.
Have therefore carried likely PoPs during the morning hours, with
the higher PoPs quickly shifting into the far east and southeast by
early afternoon as a cold front pushes into the area.  MUCAPE values
ahead of the front remain paltry, so have dropped previous mention
of isolated thunder.  Despite the showers, southerly winds will help
boost temperatures several degrees higher than in previous
days...with highs ranging from around 50 degrees across the
northeast CWA near Danville to the middle 60s far southwest near
Jacksonville.  Once the front passes, a cooler/drier airmass will
arrive tonight with lows dropping into the lower to middle 30s.

.LONG TERM...(Saturday through Thursday)
ISSUED AT 315 AM CDT Fri Mar 17 2017

High pressure will provide quiet weather across central Illinois
this weekend.  High temperatures will mainly be in the 40s on
Saturday, but will climb well into the 50s by Sunday as southerly
return flow develops on the back side of the departing high.

As has been advertised for the past several days, the next
approaching storm system will come into the picture by early next
week.  00z Mar 17 models are in good agreement with the
strength/timing of this system, with a cold front slated to drop
through central Illinois late Monday.  Before the front arrives,
warm advection will trigger scattered showers and perhaps a few
thunderstorms as early as Sunday night.  GFS MUCAPE values increase
into the 600-1000J/kg range on the nose of a developing low-level
jet streak late Sunday night, prompting the inclusion of thunder in
the forecast at that time.  As southerly winds continue to transport
warm and increasingly moist air into the region, high temperatures
will soar into the 60s on Monday...with ECMWF numeric guidance
suggesting the potential for a few lower 70s across the southern
half of the CWA.  Ample moisture ahead of a slowly approaching cold
front will set the stage for scattered showers and thunderstorms
throughout the day.  The front will sag into the Ohio River Valley
by early Tuesday, resulting in a return to cooler/drier weather for
Tuesday into Wednesday.


.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1211 PM CDT Fri Mar 17 2017

Area of IFR/low MVFR ceilings covers much of central and eastern
Illinois at midday, but clearing line should be coming into
KPIA/KSPI soon and east central Illinois toward late afternoon.
Once it does, a period of VFR conditions is expected. However,
additional lower clouds currently in Minnesota will be tracking
southeast, and will be spreading into northern Illinois after
midnight. Some indications that this should reach at least as far
as the KPIA-KCMI corridor, and have added some MVFR conditions
there late tonight into Saturday morning. Further south toward
KSPI, the southern extent is a little more uncertain, and will
keep the VFR conditions there the remainder of the period.




LONG TERM...Barnes
AVIATION...Geelhart is the U.S. government's official web portal to all federal, state and local government web resources and services.