Scientific Forecaster Discussion
fxus63 kilx 282010
Area forecast discussion
National Weather Service Lincoln Illinois
310 PM CDT Wed Jun 28 2017
Short term...(this evening through thursday)
issued at 300 PM CDT Wed Jun 28 2017
Not too many changes with the forecast through tonight over County Warning Area.
Mid afternoon surface map has 998 mb low pressure over west
central Minnesota with its cold front extending through eastern NE and
western Kansas. This front to push se over Iowa through Thu, getting
closer to central Illinois and increasing chances of convection with
time. Continued increasing chances of showers and thunderstorms
along and north of I-72 during tonight with best chances (likely
pops) along and NW of the Illinois River. Currently have scattered
showers and thunderstorms over northwest Illinois moving east-northeast toward Macomb,
Galesburg and Peru. Storm Prediction Center day1 outlook continues slight risk of
severe storms tonight NW of the Illinois River while enhanced risk just
NW of Knox County. A marginal risk remains as far se as I-55 for
tonight. This convection enhanced by strong SW low level jet
tonight and developing into an mesoscale convective system will weaken later Thu morning.
Then more scattered convection to develop during Thu afternoon and
get further south into central Illinois to about I-70. Breezy south-southwest winds
have brought in higher dewpoints in the low to mid 60s and will
rise into the upper 60s/lower 70s for Thu. Milder lows tonight in
the upper 60s to around 70f. A very warm and humid day Thu with
highs in the upper 80s (mid 80s by Knox and Stark counties).
Long term...(thursday night through wednesday)
issued at 300 PM CDT Wed Jun 28 2017
Storm Prediction Center day2 outlook with slight risk of severe storms north of I-70
Thu night for next mesoscale convective system system, while marginal risk expected about
a County se of I-70. Far southeast County Warning Area will likely stay dry
through Thu night with highest pops shifting into east central and
southeast Illinois on Friday. Storm Prediction Center day3 outlook has marginal risk of
severe storms across County Warning Area for Fri afternoon/evening and believe
highest risk will be se of I-55 in warm sector. Front appears to
push through southeast County Warning Area during Fri evening and toward the Ohio
River overnight Fri night. This could linger small chances of
convection in southeast Illinois on Sat, mainly southeast of
Charleston/Mattoon. Humid still on Friday with highs in the mid
80s, except lower 80s along and NW of the Illinois River. Highs in the
lower 80s on Sat over central Illinois and mid 80s in southeast Illinois and
starting to get less humid behind the front as dewpoints slip into
the low to mid 60s Sat afternoon.
A brief period of quiet wx expected across County Warning Area Sat night and
Sunday as weak high pressure settles into area and frontal
boundary moves into the Tennessee River valley. Seasonable highs on
Sunday in the mid 80s, with dewpoints in the lower 60s.
The 12z GFS and ecwmf models differ with handling wx system early
next work week going into the 4th of July period. Weak surface
high pressure will shift east of Illinois Sunday night and Monday
allowing more humid tropical air to return to area. The frontal
boundary lifting NE over MO valley on Monday to likely develop
more convection. But models differ on how quickly this convection
gets into central/se Illinois. Northern Illinois and possibly northern County Warning Area
could see chances of convection as early as Sunday night
especially after midnight, while rest of County Warning Area to see convection
chances return on Monday and continue through Wed as upper level
trof moves into Iowa/MO on Tue and into the Ohio River valley next
Wed. Seasonable highs in the low to mid 80s Mon-Wed and humid
conditions expected to prevail.
Aviation...(for the 18z tafs through 18z Thursday afternoon)
issued at 1259 PM CDT Wed Jun 28 2017
Isolated showers and thunderstorms could affect pia this afternoon
though brunt of convection should stay north and west of pia until
after sunset. Convection chances to move into pia and bmi during
mid or late evening and possibly to near cmi during overnight.
Convection should stay north of spi and Dec through 18z/1 PM Thu.
If thunderstorms occur, could see brief MVFR conditions, otherwise
VFR conditions will dominant next 24 hours across central Illinois.
Breezy south-southwest winds of 12-18 kts with gusts of 20-25 kts will occur
through this evening, then diminish some overnight then increase
again during Thu morning and veer SW. Continued low level wind shear from late
evening until around dawn/10z with 2k ft SW winds of 40-50 kts.