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fxus63 kilx 301611 
afdilx

Area forecast discussion
National Weather Service Lincoln Illinois
1111 am CDT Thu Mar 30 2017

Update...
issued at 1111 am CDT Thu Mar 30 2017

15z/10am surface analysis shows a 1000mb low just north of St.
Louis...with a secondary 1001mb low further west near Kansas City.
The primary instability axis as indicated by laps analysis is
associated with the eastern low...where current sbcapes of
500-1000j/kg exist from southwest Illinois southward into the
Ozarks. Radar imagery shows widespread showers/thunder well north
of the warm front lifting through north-central Illinois...and
another line of storms beginning to form west of St. Louis. The
Missouri storms will continue to lift east/NE and will impact parts
of the kilx County Warning Area this afternoon. Both the 12z 3km NAM and hrrr seem
to have a good handle on the convective trends this morning...and
show this line reaching the far SW County Warning Area around Winchester by about
18z/1pm. The storms will then track northeastward, generally
along/south of the I-72 corridor through the afternoon before
exiting into Indiana by early evening. Moderate instability and
wind shear will exist...with sbcapes of 1000-1500j/kg and 0-6km
bulk shear of 30-35kt across the east/southeast County Warning Area. Any storms that track
across this area this afternoon will be capable of damaging wind
gusts and marginally severe hail. Have updated hourly pops and
temps to better reflect current trends, but overall forecast
remains mostly unchanged.

&&

Short term...(today and tonight)
issued at 321 am CDT Thu Mar 30 2017

A complex weather system will slowly move across the County Warning Area today,
reaching the Pontiac area by 00z this evening. Additional rounds of
showers and thunderstorms will occur this morning, while a stronger
wave with strong to severe storms is possible this afternoon across
most of the County Warning Area. Models forecast sufficient instability across the
central and southern parts of the County Warning Area for this afternoon with MUCAPE
over 1000 j/kg and Lis of -2 to -6, thanks to rising dewpoints into
the 50s and lower 60s. Bulk shear and other wind parameters look OK
for severe storm development as well. Limiting factor today will be
continued cloud cover as the weather system moves slowly across the
area. Agree with Storm Prediction Center that details for this afternoon are murky due
to ongoing convection, but that parameters point to severe storms
being possible in southern Illinois. Would have to say that best area for
severe storms would be south of a Beardstown to Bloomington line. As
the low pressure area moves east of the state by late
afternoon/early evening, the chances of showers and storms should
dissipate across most of the area. However, lingering precip will
still occur along a deformation type zone, over northern parts of
the County Warning Area.

Temps should remain on the warm side today with warmest temps in the
upper 60s in eastern and southeastern IL, which will be south of the
front in the area of best warm air advection. The northern part of the County Warning Area will be
north of the boundary, but still looking at highs in the 50s, even
with precip and cloud cover. Overnight lows will be cooler than past
several days as cooler air advects into the region from the
northwest.

Long term...(friday through wednesday)
issued at 321 am CDT Thu Mar 30 2017

Seemingly endless parade of upper lows to continue over the next
several days.

Upper level trough currently coming onto the Pacific northwest coast
will deepen and cut off over Nevada this afternoon, with the low
slowly weakening after passing The Four Corners region. Lingering rain
from the current system will exit our area Friday morning, leaving a
dry period which will last through Saturday evening. After that,
model spread increases as the low starts to shear out. The GFS is
quicker with tracking the remnant wave across the middle and lower
Mississippi Valley on Monday, while the European model (ecmwf) keeps a vertically
stacked low in place until reaching the Tennessee Valley. The
Canadian model follows a similar path to the European model (ecmwf) with a faster
weakening. The former scenario would have dry conditions by early
Monday, while the latter models focus more on the southern half of
the County Warning Area through Monday evening. Leaned a little more toward the
southern solutions, resulting in higher chances south of I-70 into
Monday and also mostly dropping the mention of thunder through the
period.

Extended models are in somewhat better agreement at the moment
regarding the subsequent wave, which will enter the Pacific
northwest early Monday and close off over eastern Colorado on
Tuesday. The GFS solution has shifted about 150 miles north, while
the latest European model (ecmwf) has kept a similar path to its previous run. Both
suggest good chances of rain on Wednesday, but the extent of thunder
is more in question. Thus, will only mention isolated thunder at
this point.

Temperature-wise, coolest conditions will be observed on Friday
behind the current system, before rising back into the 60s in many
areas beginning on Sunday.

&&

Aviation...(for the 12z tafs through 12z Friday morning)
issued at 648 am CDT Thu Mar 30 2017

Complex aviation forecast this morning. Boundary just south of
spi/Dec/cmi is slowly lifting north, along with the sfc low across
MO. Lower clouds have moved north of these sites, resulting in mid
level cigs around 10kft. Pia and bmi cigs are much lower since
they are further north of the boundary. Am expecting current cigs
at all sites to continue until around the noon hour. Will also
keep vcsh at all sites this morning. Hrrr showing another area of
showers arriving this morning spi/Dec/cmi which will bring cigs
down, though still VFR, and have lower vis around 5sm with
showers. Then model showing an area of thunderstorms developing
and moving over spi/Dec/cmi this afternoon. Will have tempo group
to cover this with IFR or close to IFR cigs and vis with the
storms. The thunderstorms will reach pia and bmi couple of hours
after the other three sites. Once this line/area of thunderstorms
moves east and northeast low clouds and vis will continue for the
remainder of the evening and likely into the overnight hours. So
will keep IFR conditions going for all sites this evening. Winds
will be quite variable since a low pressure area will be moving
over the area. Winds will be stronger this morning but loosen
later this morning and into the afternoon as the gradient weakens.



&&

Ilx watches/warnings/advisories...
none.
&&

$$

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