Area Forecast Discussion
Issued by NWS Central Illinois

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474
FXUS63 KILX 240406
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
1106 PM CDT Thu Mar 23 2017

.UPDATE...
Issued at 840 PM CDT Thu Mar 23 2017

An upper level ridge continues to build north across the Mid-
Mississippi Valley this evening shifting any rain chances well to
our north and east. A gusty southeasterly wind tonight will
gradually turn more into the south later tonight as a warm front
shifts to our north with temperatures slowly rising overnight.
Windy and warm weather slated for Friday as a storm system slowly
pulls out of the southern Plains and heads northeast towards our
area as it slowly weakens. The gusty southerly winds on Friday
will help to push afternoon temperatures into the mid 70s across
the west with a bit cooler readings east and south as some lower
clouds track north into the area by afternoon. It still appears
the better chances for showers and isolated thunderstorms across
our area will be tomorrow night and Saturday. Have adjusted the
early evening temperatures and bumped the winds up for the
remainder of the night. We should have the updated ZFP out by
900 pm.

&&

.SHORT TERM...(This evening through Friday)
ISSUED AT 306 PM CDT Thu Mar 23 2017

Showers continuing to push eastward across the forecast area this
afternoon, but have struggled to make much headway from about Peoria-
Paris where dew points remain largely in the mid-upper 20s. The
clouds and rain have been keeping temperatures down, and were still
only around 40 degrees from about Rushville to Taylorville. However,
the back edge of the cloud shield has entered far western Illinois,
and some late afternoon clearing across the western CWA should help
get temperatures to rise some before sunset.

Significant warm air advection to take place tonight as a strong low
level jet ramps up (southwest winds around 60 knots at 925 mb). Low
temperatures will be early in the evening and temps will slowly rise
through the night, with many areas in the mid 50s by sunrise. Still
looking like much of the area should reach the 70-75 degree range
Friday with the highest values along the Illinois River valley.
Precipitation-wise, high-resolution models are in good agreement
with a narrow line of showers and storms forming across eastern Iowa
into central Missouri early Friday afternoon, with the bulk of this
arriving in our area during the evening. Have slowed PoP`s a bit and
focused them along and west of the Illinois River late in the
afternoon.

.LONG TERM...(Friday night through Thursday)
ISSUED AT 306 PM CDT Thu Mar 23 2017

Major trough seen in the moisture channel satellite imagery in the
southern rockies with upper ridge building over MS valley region.
Warm frontal pcpn has been trend through day today, but dry air in
the low levels has limited the extend of pcpn amounts.

Operational models are pretty close in agreement on the slow
movement of the vertically stacked upper low through the central US
into the weekend. Showers to move into region ahead of the close
upper low on Fri night, with scattered thunder possible Fri night.
lakc of instability will keep potential for severe low ahead of the
track of the upper low, so CWA will be in mainly periods of showers
on Sat into early Sun, with scattered lightning and tstms possible.
Showers slowly move out Sun.

Second shortwave to come out of trough into midwest for Monday,
spreading showers with it, with tstms mainly over the southern half.

12z EUR and Can a little faster on the movement of the 3rd system,
bringing showers into area again on late Wed night and on Thu. Will
have to watch the timing on this, far out in the future system.
Still looks weak though at this time.

&&

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1100 PM CDT Thu Mar 23 2017

LLWS continues to be the main concern thru about 13z Friday, and
then timing of MVFR cigs from south to north later tomorrow
morning and into the afternoon hours a secondary concern. Wind
profiler at ILX showing south winds of 55 to 65 kts at around
2000 feet AGL late this evening and expect the winds to turn
more into a south-southwest (190-220 degrees) direction during
the early morning hours with speeds holding around 50 kts. As
temperatures start to warm up tomorrow morning, some of the
stronger winds may mix to the surface during the mid and late
morning hours and continue thru the afternoon. The southeast winds
of tonight at 12 to 17 kts with gusts around 23 kts at times will
veer into the south during the early morning hours and then pick
up in speed during the day on Friday with sustained winds of 15 to
20 kts with gusts to around 28 kts at times thru the mid afternoon
hours before we start to see a diminishing trend as we head towards
00z.

Timing of the MVFR cigs from south to north later tomorrow morning
into the afternoon hours is a bit more of a challenge as the
lower clouds have not yet developed to our south. They are forecast
to develop after 08z south of the Ohio River and track north and
affect areas roughly along and east of I-55 by mid afternoon.
Confidence on that scenario working out not that high at this
time so will continue with the previous forecast in bringing in at
least low VFR cigs further west and northwest to SPI and PIA by
mid afternoon, while the TAF sites to the east will see the lower
cigs move in during the early afternoon hours. Rain chances and
MVFR to occasionally IFR cigs look to hold off until after 00z
Saturday as low pressure tracks slowly towards central IL.

&&

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

$$

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



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