Area Forecast Discussion
Issued by NWS Central Illinois

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS63 KILX 280158
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
858 PM CDT WED JUL 27 2016

.UPDATE...
Issued at 849 PM CDT Wed Jul 27 2016

Updated evening forecast to add low PoPs to mainly the western
portion of the forecast area (PoPs were already in the SE). A few
showers/storms have fired in the past hour or so in the vicinity
of the IA/IL border and have slowly tracked east toward the
Illinois River Valley. Not a whole lot supporting these storms
forcing wise, although some very weak low-level convergence is
noted in VAD wind profile plots and some model guidance. This
convection also happens to be firing in an axis of higher
instability. Do not really expect this precipitation to become
widespread, and it should actually wane as instability weakens.
Better chances will arrive by later tonight as more significant
upper energy arrives.

Aside from the above mentioned PoP adjustments, only minor tweaks
were needed to the going forecast.

&&

.SHORT TERM...(This evening through Thursday)
ISSUED AT 258 PM CDT Wed Jul 27 2016

19z/2pm surface analysis continues to show stationary frontal
boundary just south of the Ohio River, while a weak bubble of high
pressure is in place over northern Illinois.  Quiet weather is
currently occurring across much of the KILX CWA, with the exception
being a cluster of thunderstorms that has developed across southern
Sangamon County into Christian County.  These storms are well north
of the synoptic frontal boundary and are likely being triggered by a
subtle short-wave trough.  Further south, scattered storms directly
tied to the front appear to be remaining just south of the CWA:
however, models continue to suggest widely scattered storms forming
further north toward the I-70 corridor as the afternoon progresses.
With no strong synoptic forcing in the vicinity, will only carry low
chance PoPs along/south of a Jacksonville to Paris line through the
evening hours.  A stronger short-wave evident on latest water vapor
imagery over central Iowa will approach from the northwest
overnight, so have introduced slight chance PoPs across the
remainder of the area after midnight.  Best rain chances will hold
off until Thursday as stronger lift associated with the upper wave
arrives.  Will carry high chance PoPs for showers/thunder across the
board with afternoon high temperatures remaining in the lower to
middle 80s.

.LONG TERM...(Thursday night through Wednesday)
ISSUED AT 258 PM CDT Wed Jul 27 2016

The upper level wave that moves into the area is forecast to stay in
the area through the end of the week and into the weekend. An
associated frontal boundary will also remain present in the area
through the same time period, so the chance of showers and storms
will continue over the CWA for Thur night through Sat. The unsettled
pattern will weaken a little but small chances of pops will continue
for the rest of the weekend and into next week.

Cloud cover and scattered storms will keep temps down through most
of the period, so looking for lower to middle 80s from the end of
the week through the weekend. However, ridging building in the
plains over the weekend will drift toward the area the beginning of
next week and bring temps back to around 90 and the lower 90s for
Tue and Wed.

&&

.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 659 PM CDT Wed Jul 27 2016

Generally VFR conditions expected across the central Illinois
terminals through the 00Z TAF valid time, along with light winds.
However, there are a couple areas of concern. The first is the
potential for fog development later tonight, and the second is the
risk for showers/storms tomorrow with the passage of an
upper=level wave and/or diurnal instability. Feel the fog will be
patchy overall tonight, as it has been in recent nights, and not
as widespread as suggested by some of the guidance. Covered this
with a MVFR tempo group for now. There will be some convection in
the area tomorrow, but confidence in the coverage/details is too
low to go above a VCSH mention. This will undoubtedly be updated
as confidence grows by tomorrow morning.


&&

.ILX Watches/Warnings/Advisories...
NONE.
&&

$$

UPDATE...Bak
SHORT TERM...Barnes
LONG TERM...Auten
AVIATION...Bak



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.