Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 030805
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
305 AM CDT TUE MAY 3 2016

.SHORT TERM...(Today)
ISSUED AT 304 AM CDT Tue May 3 2016

Another mostly quiet day is anticipated today across central and
southeast Illinois. Main concern revolves around cloud cover and if
there will be any precipitation.

Forecast area remains under the influence of a sheared trof axis
aloft, and weakly cyclonic flow at the surface. This scenario will
change little during the day today. A piece of energy within the
sheared trof is coming through the area at the moment with little
fanfare, although there are a few very weak/spotty radar returns.
However, have not seen recent reports of any of these returns
reaching the ground. Some additional sheared energy will impact the
area later today, but it will have very little instability to work
with. So think this feature should come through dry, but have
maintained a very low PoP in extreme SE IL where the instability may
be a bit better. Ultimately, based on forecast soundings & the items
mentioned above, think most of what we will see this afternoon is an
enhanced diurnal CU field and little more than a few sprinkles.

&&

.LONG TERM...(Tonight through Monday)
ISSUED AT 304 AM CDT Tue May 3 2016

Latest models show little change in the projected upper air pattern
over the next several days. Current upper ridge already in place
with high pressure centered over southern Alberta. As the current
system over the central Plains and mid-Mississippi Valley drops
southward today, it will yield to an upper low that is now in
northwest Ontario and is projected to reach Lake Michigan on
Wednesday morning. Cooler conditions are expected for a few days as
a broad trough covers the eastern CONUS, but as the ridge shifts
eastward on Friday, significantly warmer conditions expected. Latest
blended guidance brings highs into the mid 70s over the western CWA
as early as Friday, and 80 degree readings over much of the forecast
area on Saturday.

Surface boundary associated with the Ontario system appears to be
picking up speed, and have increased PoP`s quite a bit and somewhat
faster than earlier, with likely PoP`s over areas north of Peoria as
early as late evening. Also went with a period of 60% PoP`s over
east central Illinois after midnight. The window for rain looks to
only last about a couple hours at any given location, given the
speed of this system. Some steeper mid-level lapse rates favor a few
rumbles of thunder as well. Have maintained some chance PoP`s over
the eastern half of the forecast area as well on Wednesday due to
the arrival of the upper low.

Weekend system starting to come into a little better agreement in
the longer range models. Both the GFS and ECMWF settle a quasi-
stationary front over central Illinois by Saturday afternoon,
lingering in the general area through Sunday. How fast this boundary
retreats northward is more in question, with our region caught
between the southern jet stream being steered south of the upper low
over the 4-corners region, and the northern jet stream coming
through the Great Lakes. Thus, once precipitation chances develop
through the day Saturday, chance PoP`s will remain in the forecast
into Monday.

&&

.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1124 PM CDT Mon May 2 2016

The clearing line has advanced south late this evening, with no
ceiling anymore at PIA, BMI and CMI. VFR ceilings remain at SPI
and DEC at 7-8K FT, but even those ceilings should erode shortly
after 06z as the upper shortwave shifts east of the region and
drier air continues to work in from the north. Scattered cumulus
will develop by mid morning and may periodically go broken with
bases remaining above MVFR levels through afternoon. A sprinkle or
two can not be ruled out during the flare-up of cumulus during the
day, but most areas will remain dry.

Winds will become light and variable tonight as a weak high
pressure ridge shifts into Illinois overnight. Winds tomorrow will
veer to the WNW and climb to 10-13 kts by mid-afternoon on Tuesday,
ahead of a cold front approaching from the north. Winds will
weaken below 10kt Tue eve as they back to the west-southwest.

Rain showers could develop near the northern terminals of PIA,
BMI, and CMI late in this TAF period, but the better chances will
hold off until after 06z Tuesday night.


&&

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

$$

SHORT TERM...BAK
LONG TERM...Geelhart
AVIATION...Shimon


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