Area forecast discussion
National Weather Service Lincoln Illinois
645 am CDT Wednesday Jun 19 2013
Discussion...
issued 251 am CDT Wednesday Jun 19 2013
Short term...today through Friday
Cold front that brought a few strong thunderstorms to portions of
east-central and southeast Illinois yesterday afternoon/evening
has now sagged southward to near the Ohio River. Cool/dry
northeasterly flow behind the front has spread across central
Illinois early this morning...with 07z/2am dewpoints dipping into
the upper 40s across the far northern kilx County Warning Area. This dry airmass
will lead to mostly sunny and pleasant conditions today...with
afternoon highs only reaching the lower 80s. The only potential
fly in the ointment will be further south in closer proximity to
the frontal boundary...where several iterations of the WRF model
are suggesting isolated convection along the I-64 corridor late
this afternoon. Based on strong push of dry air from the
northeast...think if any convection develops...it will remain
just S/SW of the kilx County Warning Area.
Dry weather will continue through Thursday morning...before warm
front lifting northward into the area potentially triggers isolated
showers/thunder across west-central Illinois Thursday afternoon.
Weakening upper wave approaching from the plains will provide
limited synoptic lift along the boundary...however think airmass
will be too dry to support much in the way of precipitation. Will carry
just a 20 pop along/west of the Illinois River Thursday
afternoon...and even that may be overdoing it. Any showers that
develop in advance of the front will quickly dissipate Thursday
evening as meager daytime instability is lost.
Upper ridge begins to build across the Midwest on Friday...in
response to upstream deep trough west of The Rockies. Models are
still having difficulty determining the exact strength of the
ridge and whether or not any potential mesoscale convective system activity could impact
parts of central Illinois. GFS has shown a consistent signal over
the past several runs...keeping bulk of precipitation well to the north
across the upper Midwest into the Great Lakes. Will continue to
follow this solution...which leads to a very warm/dry day on
Friday with highs well into the 80s.
Long term...Saturday through Tuesday
Hot and generally dry weather will persist over the weekend...with
upper ridging firmly in place and any significant convection
staying north of central Illinois. May see some isolated
showers/storms around the area Saturday afternoon depending on
strength of middle-level capping...but not enough to mention in the
forecast at this time. Main story for the weekend will be the
hot/humid weather...with highs in the upper 80s/lower 90s and heat
index values approaching 100 on both Saturday and Sunday. Ridge
begins to flatten early next week...gradually allowing a frontal
boundary to settle southward into central Illinois. Speed in which
this process occurs is still in question...as model solutions vary
from run to run. Bottom line with both the GFS and European model (ecmwf) is that
ridge axis will shift into The Rockies by the middle/end of next
week...resulting in a cooler northwesterly flow across the
Midwest. At this point...will bring low chance probability of precipitation into the
northern County Warning Area on Monday...however widespread precipitation will likely
hold off until Wednesday/Thursday when ridge re-positions itself
further west.
Barnes
&&
Aviation...
issued 645 am CDT Wednesday Jun 19 2013
VFR conditions are forecast to continue across the central Illinois
terminal airports next 24 hours through 12z/7 am Thursday. Fair weather due
to 1023 mb surface high pressure over Michigan and ridging SW
into MO...and to drift east into the eastern Great Lakes and
southern New England by dawn Thursday. Patchy shallow/ground fog over southeast
Illinois to lift by 13z/8 am and stay southeast of the central Illinois taf sites.
Scattered-broken middle/high clouds streaming southeast over Iowa/MO will
push southeast across the SW half of Illinois this morning and affect spi and
possibly as far NE as pia and Dec but any ceilings would stay
above 10k feet. Scattered cumulus clouds 4-5k feet to develop after
15z/10 am and continue this afternoon with broken ceilings mainly
staying south of I-72 over southeast Illinois this afternoon. Cumulus clouds to
dissipate early this evening by sunset leaving clear skies
tonight. Fog not expected tonight due to dry airmass in place. NE
winds 4-8 kts early this morning to turn east later this morning
and afternoon in 6-10 knots range...then become light east-southeast after
sunset tonight.
07
&&
Ilx watches/warnings/advisories...
none.
&&
$$
