Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 200945
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
345 AM CST Thu Nov 20 2014

.SHORT TERM...(Today)
ISSUED AT 345 AM CST THU NOV 20 2014

Expansive trof aloft still dominating the weather map this
morning.  Cold front has slipped through the area and just south of
the Ohio River Valley this morning.  High pressure building into the
region at the sfc, and plenty of cold air surging back into the
region keeping the max temperatures well below normal again today,
and expected through the end of the week.  Mostly westerly winds
today will be brisk, and with the cold temps expected, the wind
chills will drop into the single digits this morning, and the teens
this afternoon.  Models in pretty good agreement through the
forecast with some minor shifts here and there, but no major changes
to the forecast with this run. Forecast issues revolve around
chances for freezing rain on Friday night, and extensive precip
through the weekend in the form of rain.


&&

.LONG TERM...(Tonight through Wednesday)
ISSUED AT 345 AM CST THU NOV 20 2014

Cold air remains anchored over the region through the end of the
week, though more southerly winds will begin to set up late Friday
in advance of a developing system to the SW. The main issue in the
forecast is the advancement of the rain while the sfc remains below
zero.  Too dry aloft for crystals to support snow, and threat for
fzra is increasing with the precip preceding the warm up at the sfc
after the sun sets Friday evening.  Struggle remains in the models
in the last few runs with regards to timing...and the sfc temps are
now warming very quickly in the GFS.  For now, am throwing out that
concept as the concern remains that it will take longer to erode the
significant cold airmass over frozen ground.  So far, little ice
accumulation is showing in the qpf...with temps struggling near
freezing that night in Central Illinois...as far south as Decatur
through midnight...lingering into the early morning hours. Models
still lacking in timing and the pop spread remains in the forecast
yet again from the slow ECMWF into Mon night/Tues.  Best chances for
the weekend is in the high chance/likely category for precip, though
the temperature profile for now is still indicating rain Saturday
through Sunday, as the low lifts right through the region. With
timing issues, am keeping the likely mention to a minimum with the
exception of the Saturday night/Sunday...which is at least
consistent with 24 hrs ago.  That being said, a gap between the
precip with the warm frontal development and the core of the storm
is developing which may provide a break within that time frame.
Either way...the weekend looks wet, with the majority of the qpf
expected on Sunday, and over an inch storm total expected through
the weekend.  Temps struggling into the 50s will give Central
Illinois a break from the cold for Sunday.


&&

.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
ISSUED AT 1143 PM CST WED NOV 19 2014

Winds have finally diminished as pressure rises slowed down and
the pressure gradient relaxed a bit, especially across the SW half
of IL. We expect west winds in the 8-10kt range for the rest of
the night.

The latest satellite imagery shows diminishing clouds to the W-NW
compared to earlier this evening. We still have a majority of
central IL with some VFR cloud cover in the 3.5k-4.5k ft layer,
but breaks are becoming more numerous with each passing hour. Forecast
soundings remain generally pessimistic with cloud cover the rest of the
night, but we continued with clearing developing at all terminal
sites before sunrise.

Once the skies clear out, we expect enough dry air mixing tomorrow
to prevent any BKN cloud decks from forming, but moisture will
remain in the 2-3k ft layer according to forecast moisture
profiles. Winds will be less gusty than today, but sustained winds
will climb back into the 10-145kt range through the day from the
west. Light winds will develop with sunset tomorrow, as winds
decouple under clear skies and weak high pressure.


&&

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

$$

SHORT TERM...HJS
LONG TERM...HJS
AVIATION...Shimon





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