Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 270455
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1155 PM CDT Sun Oct 26 2014

.UPDATE...
ISSUED AT 858 PM CDT SUN OCT 26 2014

Warm front approaching central Illinois from the south at this
time, to push across the region overnight. As a result, light
southeast breezes will continue overnight ahead of the front,
switching to southerly and increasing to 15 to 20 mph with gusts
up to 30 mph in the morning after frontal passage. Dewpoints will
rise fairly dramatically as well, rising from the 20s and 30s
today to around 60 Monday morning. Temperatures will also bottom
out in the next few hours then gradually warm overnight. Current
forecasts incorporate these short term trends well and no
significant updates needed this evening.

&&

.SHORT TERM...(Tonight)
ISSUED AT 239 PM CDT SUN OCT 26 2014

Ridge of high pressure extending from the western Great Lakes to the
Ohio River Valley will push off to the east tonight, allowing a
frontal boundary draped across central Missouri into western
Kentucky to lift northward into the area.  The air mass to the north
of the front is quite dry, as evidenced by 18z/1pm dew points in the
30s across central Illinois.  Meanwhile to the south of the
boundary, a much more humid air mass is in place with widespread
dew points in the 60s across central/southern Missouri.  As the front
passes and winds veer from southeast to south, this warmer/more
humid air will arrive overnight.  As a result, am expecting low
temperatures in the middle to upper 50s to be achieved by midnight,
with steady or slowly rising temps toward dawn.  Earlier runs of the
HRRR had suggested that low-level cloud cover may develop/spread
northward as the front arrives, but latest runs have backed way off
on that solution.  In addition, 12z NAM forecast soundings show only
a very shallow pinch of moisture below 950mb.  Therefore think other
than a few high/mid clouds, skies will remain mostly clear
tonight.

&&

.LONG TERM...(Monday through Sunday)
ISSUED AT 239 PM CDT SUN OCT 26 2014

One more unseasonably mild day on tap for Monday, as southwest winds
ramp up ahead of the incoming cold front. Have kept highs similar to
before, in the 80 degree vicinity which is close to the GFS MOS
guidance. BUFKIT soundings showing potential for some gusts in the
25-30 mph range or so in the afternoon across the eastern CWA.

Broad upper trough currently pushing across Idaho and southeast
British Columbia will be digging as it drops southeast overnight
into the northern Plains. As it approaches, it will enhance an area
of low pressure currently Kansas, and drive it northeast along the
developing cold front into Wisconsin by late Monday evening. Most of
the models, especially the NAM and GFS, are trying to hint at some
afternoon development. The higher-resolution ARW and NMM would
indicate this would be most likely very late afternoon, as the
forecast soundings show quite a bit of dry air below 12,000 feet
that needs to be overcome first. Best rain chances thus remain at
night, as the front starts to move in and nearby low level jet over
50 knots continues to pump moist air into the area. Overnight
instability will be somewhat limited, with MUCAPE`s only around 500
J/kg although 0-6km bulk shear does reach around 50 knots as the
front moves in, so will maintain a chance of thunder. The front
should be through the southeast forecast area by around midday
Tuesday, with the rain quickly ending behind it, and will go dry for
Tuesday afternoon.

Upper ridging builds along the west slopes of the Rockies late this
week, helping to drive much cooler air into the Midwest for late
week. High temperatures Friday and Saturday likely to only be in the
upper 40s or lower 50s. A fast moving shortwave will drop southeast
into the mid-Mississippi Valley around Thursday. The GFS and ECMWF
continue to try and generate some showers with this wave, but amount
of moisture available appears a bit limited at the moment, so will
only mention slight chances of rain at this point.

&&

.AVIATION...(For the 06Z TAFS through 06Z Monday night)
ISSUED AT 1150 PM CDT SUN OCT 26 2014

VFR conditions are expected until around 00Z Tuesday. Chances for
thunderstorms will develop in the afternoon, mainly west of a
KSPI-KBMI line, but MVFR cigs/vsbys unlikely until 00Z
Tuesday. After 00Z Tuesday, lower ceilings, likely reaching MVFR
category and isolated IFR/MVFR visibilities will spread eastward
across Illinois.

tonight, warm frontal boundary to push northeastward across
central IL, with main impact being a veering of winds toward more
southerly direction along with strong low-level jet producing low-
level wind shear at most central IL TAF sites. These 35-40kt winds
at around 2000ft will mix down to the surface Monday morning once
the nocturnal inversion is eroded, resulting in southerly winds
gusting to 25-30 kts.

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

UPDATE...Onton
SHORT TERM...Barnes
LONG TERM...Geelhart
AVIATION...Onton






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