Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 270157
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
857 PM CDT Thu Mar 26 2015

.UPDATE...
ISSUED AT 856 PM CDT THU MAR 26 2015

Quiet, but continued much cooler than normal. weather is expected
across central and southeast Illinois overnight. Canadian high
pressure will gradually build into the area from the northwest.
However, an upper-level disturbance will also cross the area
overnight. This feature will come through dry, but cloud cover
associated with it will keep temperatures a little milder
overnight than they might otherwise be.

Going forecast is in good shape overall depicting the quiet
weather anticipated. Only a few tweaks to the hourly trends are
needed at this time.

&&

.SHORT TERM...(Tonight)
ISSUED AT 300 PM CDT THU MAR 26 2015

Lingering precipitation has shifted to our southeast early this
afternoon, and skies west of I-55 have been mostly sunny. The areas
east of I-55 have been a little slower to clear out, though. Upper
level trough rather prominent on water vapor satellite imagery this
afternoon, generally marking the back edge of the cloud line.
Another fast moving shortwave is dropping southward across northern
Minnesota, and this will be moving into northern Illinois overnight.
No precipitation is expected our area from this feature, but this
will help to keep some of the stratocumulus deck to our north from
scattering out quite as fast before it arrives. Thus, overnight
forecast will generally be partly cloudy across the area. Little
change made to the temperatures, with mid to upper 20s across the
entire CWA.

&&

.LONG TERM...(Friday through Thursday)
ISSUED AT 300 PM CDT THU MAR 26 2015

Morning upper air and moisture satellite loop shows digging upper
trough over upper MS valley with shortwave moving east over IL
region. Strong upper jet southeastward plunging over MT. 850mb cold
air advection into area after the cold front that has moved east of
region, with pcpn cleared area.

Models consistent in maintaining northwest upper level flow and
resulting cool conditions due to cold high pressure into Saturday.
Upper flow then flattens some and surface return flow late Saturday
into Sunday that begins warming.

Shortwave in the northwest flow progged to move from northern plains
through IL Sunday.  Appears to be enough southerly flow ahead of
wave for moisture and with lift and some moisture coming with
system, will have chance pops over most of CWA, but heaviest pcpn
over northern 1/3 of state. Timing is still an issue, as GFS is
much faster than the new EUR model. Pcpn moves off overnight, with
only a week high ridge moving in. Another week low moves north of
the region through the Great Lakes on Tuesday, and then a final
system approaches Wednesday. Again the models are in disagreement on
track with the EUR more aggressive with pops. Just went with chance
pops for that period til more agreement.

&&

.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
ISSUED AT 654 PM CDT THU MAR 26 2015

Predominantly VFR conditions are expected across the central
Illinois terminals through the 00Z TAF valid time. High pressure
will begin to push into the area at the surface, with northerly
winds prevailing through the period. An upper level disturbance
will cross the area later tonight into early Friday, but it is not
expected to be accompanied by more than VFR cigs. The bigger
question mark, suggested by some model guidance, is if MVFR cigs
will stream across at least KBMI and KCMI for a time late
tonight/early Friday as the low level flow turns just east of
north off Lake Michigan. Have included a TEMPO group for now to
cover this potential, but confidence in the details is low.


&&

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

$$

UPDATE...Bak
SHORT TERM...Geelhart
LONG TERM...Goetsch
AVIATION...Bak





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