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Area forecast discussion
National Weather Service Lincoln Illinois
1046 am CST sun Feb 26 2017

issued at 1040 am CST sun Feb 26 2017

Breezy and cool conditions expected today as the high pressure
ridge that passed overnight moves into the Ohio River valley.
Temperatures will be more mild today as the surface winds come
around to more southerly. Forecast looks good and no updates are
anticipated at this time.


Short term...(today and tonight)
issued at 236 am CST sun Feb 26 2017

Above normal temperatures return to central and southeast Illinois
starting today. A ridge of high pressure will shift east of the
forecast area early today, with southerly low-level winds pushing
today's highs to around 50 degrees. Tonight's lows will generally be
in the 30s.

Aside from the moderating temperatures, the main weather concern
today revolves around the threat for rain as a weak short wave
tracks through the region late today into tonight. The model trend
continues to be drier for the forecast area with this feature, with
the bulk of the rainfall likely to stay south of the forecast area.
That being said, forecast soundings suggest enough moistening of the
local airmass will have taken place south of I-70 by tonight for
some rain showers to occur. In any event, the rainfall tonight does
not look significant.

Long term...(monday through saturday)
issued at 236 am CST sun Feb 26 2017

Not a lot of change in the overall upper air pattern this week.
Transition of the southern stream into more of a southwest-northeast
configuration is starting this morning, as one upper low drops
southeast from San Francisco and a second settles southward toward
northwest Washington state. This will bring a couple days of very
mild air once again, but no chance of it lingering as long as last
week, as a broadening trough tracks east across the plains during
midweek. As this moves into the Midwest later in the week, the
longer range models bring a slug of cold air into the Great Lakes,
with our area generally on the periphery of the air mass. Rapid
moderation takes place for the weekend as the flow becomes more

Main weather maker remains the Tuesday-Wednesday storm system. Some
variations on the low track among the main models, with one wave
moving across Iowa Tuesday afternoon followed by the main low
further south Tuesday night. The European model (ecmwf) is the fastest and has the
low all the way to Lake Huron by early Wednesday, while the NAM and
GFS have it somewhere in central Illinois. Favoring more of the
slower solution at the moment and thus keeping very high pop's
across most of the forecast area into Wednesday morning. Some decent
precipitable water values of over an inch are progged by the NAM and
GFS with this system Tuesday afternoon and night, favoring
especially the southeast County Warning Area where rainfall amounts of 3/4 to 1 inch
currently appear feasible. Thunder-wise, the NAM appears too
aggressive with bringing cape's as high as 2000+ j/kg late Tuesday
night, with the GFS lower but still near 1000 by late afternoon
over the southeast County Warning Area. However, 0-6km bulk shear quite impressive
at 60-80 knots, so some strong/severe storms are possible, and
latest Storm Prediction Center day3 outlook does include a slight risk from about
Jacksonville-Bloomington southeast.

As the pattern shifts, a clipper-type system will drop southeast
across the north half of the state Thursday afternoon/evening. While
starting as rain, a transition to snow is possible in the evening
before the system quickly exits.


Aviation...(for the 12z tafs through 12z Monday morning)
issued at 505 am CST sun Feb 26 2017

VFR conditions will prevail over the forecast area through the
period with the main concern being from gusty south to southwest
winds starting this morning and continuing into the afternoon
hours. Forecast soundings indicate mainly sct-bkn mid and
high level cloud cover during the day. A weather disturbance
will push across the area late tonight into Monday morning which
looks to bring low VFR cigs into our northern taf sites by 12z.
The gusty southerly winds will diminish by 00z this evening with
a light southerly breeze expected overnight, generally less than
10 kts.


Ilx watches/warnings/advisories...


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