905
FXUS63 KILX 161440
AFDILX

Area Forecast Discussion...Updated
National Weather Service Lincoln IL
940 AM CDT Sun Jun 16 2024

.KEY MESSAGES...

- A cluster of thunderstorms will develop and track across
  locations along/northwest of a Macomb to Minonk line this
  afternoon.  Gusty winds and heavy downpours will be possible.

- Seasonably hot and humid weather is on tap this week. Heat index
  values will peak at or above 100 degrees both this afternoon and
  Monday afternoon before readings settle back into the middle to
  upper 90s for the remainder of the week.

&&

.UPDATE...
Issued at 940 AM CDT Sun Jun 16 2024

14z/9am satellite/radar mosaic shows a Mesoscale Convective Vortex
(MCV) over northern Missouri moving northeastward at about 30-35mph.
Based on timing tools, this feature will skirt through the NW KILX
CWA by mid to late afternoon. Most 12z CAMs suggest renewed
convective development along/ahead of this feature...primarily
along/north of a Macomb to Minonk line between 19z/2pm and
01z/8pm. As surface dewpoints climb into the upper 60s/lower 70s,
SBCAPEs will increase to around 3000J/kg this afternoon: however,
deep-layer shear will remain meager with 0-6km bulk shear values
of only around 20kt. Think severe weather risk will remain low,
with the main concerns being gusty winds and heavy downpours. Have
updated the forecast to add slight chance PoPs as far south as a
Canton to Normal line...with high chance PoPs focused from the
Peoria area northward. Elsewhere around central Illinois, it will
be a breezy and hot day. High temperatures will top out in the
lower to middle 90s as heat index values climb toward 100 degrees.
The heat will be somewhat mitigated by a southwesterly breeze at
10-15mph with gusts of 20-25mph.

Barnes

&&

.DISCUSSION...
Issued at 400 AM CDT Sun Jun 16 2024

Predawn surface map shows 1024 mb high pressure over the
Adirondack and Catskill mountains of eastern NY state while a warm
front was over northeast MO and eastern Iowa and extending to 995
mb low pressure over north central SD. A few MCS`s with clusters
of showers and thunderstorms were over northeast KS, nw MO and
central Iowa into eastern MN and central/western WI. This
convection was lifting ne and mostly staying nw of IL, though
clipping far nw Jo Daviess county. Some cirrus clouds over the IL
river valley especially nw of the IL river, while rest of CWA is
clear. Temperatures at 330 am ranged from mid 60s near the Indiana
border/Wabash river to 70-75F from highway 51 west with our
larger cities of Peoria and Springfield at 75F.

The warm front is forecast to lift ne across central IL during
this morning with SSE winds shifting south to SSW with its passage
and a tropical air mass flowing into the area today. Strong upper
level high strengthens further over the southeast states and
ridging over the eastern parts of Ohio river valley and Great
Lakes. A few of the CAM members like the HRRR and HiResW- ARW
show isolated convection slipping nw parts of Knox and Stark
counties early this morning (between 12-14Z) and continued slight
chances there. The complex of storms over ne KS and nw MO lifts ne
and the HRRR shows some of this convection affecting areas from
the IL river nw late this afternoon and early evening. Introduced
slight chance of convection nw of IL river from 4-8 pm for this
possibility. Otherwise much of CWA will be dry today with breezy
south to SSW winds bringing in a hot and humid air mass for this
afternoon. Highs 92-96F today with dewpoints 65-70F giving peak
heat indices in the upper 90s to around 100F. Airnow.gov has
orange area (unhealthy for sensitive groups) today in the Wabash
river valley). Air quality alerts are in effect east of IL over
Indiana through this evening. Muggy lows tonight in the mid 70s
with some lower 70s near the Indiana border.

A 595 dm 500 mb high drifts northward over the mid Atlantic States
on Monday with some deeper gulf moisture lifting into parts of
central and especially east central and southeast IL by Monday
afternoon. This to develop isolated showers/thunderstorms Monday
afternoon with best chances near the Wabash river valley. Breezy
south to SSW winds bring another hot and humid day with highs in
the mid 90s and afternoon heat indices of 100-105F. This will be
close to heat advisory criteria of 105F and heat headlines may
eventually be needed for Monday afternoon plus depending on
duration and intensity of this weeks heat wave. Heat watches have
been posted in Ohio, eastern Indiana and southern half of lower MI
Monday afternoon thru Friday. Isolated convection to diminish in
southeast IL after sunset Monday evening. Muggy lows in the mid
70s Monday night across the CWA.

The strong subtropical ridge builds over the mid Atlantic states
and into New England on Tuesday and continues to stream moisture
from the western gulf of Mexico into IL. Diurnally driven
isolated convection expected again Tue afternoon and looks to be a
bit more coverage over CWA on that day. More cumulus clouds Tue
keeps temps a few degrees cooler than Monday with highs in the
lower 90s and afternoon heat indices in mid to upper 90s, and near
100F nw of the IL river where more sunshine expected Tue. Lows
Tue night in the low to mid 70s, with isolated convection
dissipating around sunset.

The 500 mb high strengthens to around 600 meters near NJ and
southern New England coast by Wed/Thu while riding back into IL
with 500 mb heights rising above 594 meters over CWA on Thu.
Isolated convection chances on Wed afternoon appear to be more
focused nw of I-55 and mainly nw of the IL river. Highs Wed 90-95F
and mid 90s on Thu and Fri and peak heat indices of 95-100F and
possibly getting above 100F on Thu and Fri. The strong upper
level ridge back into IL to keep the frontal boundary nw of IL
late this week along with better chances of convection.

Extended models show the subtropical ridge still affecting central
and southeast IL on Saturday and then retreating se on Sunday as a
weak trof digs over the northern states. Still differences with
models that far out on how this evolves but consensus has 20-30%
pops arriving Sat afternoon and Sat night (highest pops northern
CWA) and 30-40% pops next Sunday and temps starting to cool a few
degrees over central IL.

07

&&

.AVIATION...  (For the 12z TAFs through 12z Monday Morning)
Issued at 555 AM CDT Sun Jun 16 2024

VFR conditions are generally expected across the central IL
airports through 12Z/7 am Monday. Isolated showers and
thunderstorms should stay nw of PIA early this morning, but could
be close to this airport late this afternoon mainly from 22-24Z
and added VCTS for a few hours late in afternoon. Broken cumulus
clouds with 5k ft ceiling along and nw of I-55 early this morning
should scatter out next few hours with few to scattered cumulus
clouds rest of today and some passing cirrus clouds. SSE to SE
winds 7-13 kts early to veer south to SSW and increase to 12-16
kts with gusts 20-25 kts by late morning. South winds to diminish
to around 10 kts at sunset with fair weather expected tonight.

07

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$