Area Forecast Discussion
Issued by NWS Chicago, IL

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FXUS63 KLOT 262021 CCA
AFDLOT

Area Forecast Discussion...CORRECTED
National Weather Service Chicago/Romeoville, IL
221 PM CST Sun Jan 26 2020

.SHORT TERM...
208 PM CST

Through Monday night...

A small band of flurries/snow showers developed early this
afternoon and is currently pushing east across southern Cook
county and NW Indiana. Any lingering snow that falls will be
fairly brief and no accumulation is expected.

Due to the extensive cloud cover draped across much of the local
area temperatures remain in the upper 20s and low 30s. Our far
southern counties managed to see some sun this afternoon where
highs have risen into the mid 30s.

High-res guidance is hinting at patchy freezing drizzle and
flurries potential heading into the early morning hours tomorrow
associated with a subtle disturbance dropping south across the
area. The best chances remain across our northeastern zones,
mainly along and northeast of I-90. Not currently expecting
significant impacts from this, but some patchy slick spots could
develop on untreated surfaces and sidewalks. There is also an
indication of some lake effect snow flurries lingering across
northwest Indiana (mainly Porter county) during the day on Monday.
Conditions are not overly favorable for accumulation so will
maintain a mention of flurries. Highs Monday top out in the 30s
again with cloudy conditions continuing with another round of
patchy light freezing drizzle possible again late Monday night.

Petr

&&

.LONG TERM...
208 PM CST

Tuesday through Sunday...

Cloudy skies and light winds continue through the extended
keeping temperatures fairly consistent with highs in the 30s and
lows in the 20s.

Another disturbance moves across the area late Wednesday. An
associated surface low is expected to remain well south of our
area. A weaker wave to the north could bring an outside chance of
light wintry precip as it moves across the lower Great Lakes
region, but the mid-levels remain dry and models have backed off
on precip chances.

Our active weather pattern continues with another system
developing later this week into the weekend, but considerable
model differences in timing and location of the low preclude a
higher winter precip mention so will maintain slight chances at
this time. Temperatures push into the upper 30s and low 40s by
this weekend as upper level ridging builds across the western
CONUS and above normal temps continue into the first week of
February.

Petr

&&

.AVIATION...
For the 18Z TAFs...

Concerns at RFD for LIFR have us thinking an amendment may be
needed before very long based on upstream obs with OVC003 heading
that direction. So far it has been trending steadier than other
sites which saw that drop earlier so elected to keep it out at
18z issuance time. Did decide to start with IFR cigs everywhere
and tempo the MVFR cigs based on GOES Snow-Fog RGB that shows the
breaks filling in rapidly. Seeing LIFR later this afternoon at the
Chicago metro terminals is not out of the question but confidence
is even lower for those locations. One factor that seems to be
correlated to LIFR cigs is colder temperatures in the 26-28F range
while sites with better conditions are in the 30s and expected to
stay there.

Steady but relatively light westerly flow will persist through the
period.  Toward the end of the TAF period Monday afternoon and
evening there are signs that LIFR could become more widespread, so
that will need to be addressed in later issuances.

Lenning

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.
&&

$$

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