Area Forecast Discussion
Issued by NWS Chicago, IL

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000
FXUS63 KLOT 011149
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
649 AM CDT TUE SEP 1 2015

.SHORT TERM...
311 AM CDT

THROUGH TONIGHT...

PRIMARY FORECAST CHALLENGE TODAY IS POTENTIAL FOR ISOLATED
CONVECTION OVER MAINLY SE THIRD OF CWA...POSSIBLE WEAK LAKE
BREEZE...AND HIGH TEMPS.

WATER VAPOR IMAGERY THIS MORNING SHOWS A WELL DEFINED UPPER LOW OVER
CENTRAL INDIANA WITH A NARROW PLUME OF MID-UPPER LEVEL MOISTURE
WRAPPING AROUND THE NW FLANK OF THE SMALL CIRCULATION IN OUR
SOUTHEAST CWA. GUIDANCE HAS BEEN PRETTY AGGRESSIVE IN BREAKING OUT
ISOLD-SCTD CONVECTION WITH THIS FEATURE...EVEN NOW INTO EARLY THIS
MORNING...WHICH THUS FAR HAS BEEN ABSENT. 11-3.9U GOES IMAGERY DOES
SHOW SOME ACAS BUBBLING UP OVER EAST CENTRAL ILLINOIS...BUT THUS FAR
NO PRECIP. ONE CAMP OF GUIDANCE BREAK OUT CONVECTION THIS MORNING
WITH CONTINUED DEVELOPMENT ON THE OUTFLOW FLANK FROM THIS (YET TO
DEVELOP CONVECTION) MAKING FAIRLY FAR NORTH INTO OUR CWA THIS
AFTERNOON. ANOTHER CAMP OF MODELS IS MORE AGGRESSIVE IN BREAKING OUT
AFTERNOON CONVECTION AND FOCUSING IT MAINLY IN SE CWA. MAJORITY OF
GUIDANCE HAS DEWPOINTS IN THE MID 70S THIS AFTERNOON...WHICH LEADS
TO VERY HIGH CAPE AND NO CAP. THINK MORE REALISTICALLY DEWPOINTS
WILL BE AROUND 70 TO LOW 70S WITH WEAKER CAPE AND SOME INHIBITION.
THE MEMBERS OF THE HOP-WRF ENSEMBLE WITH LOWER TDS BREAK OUT LITTLE
TO NO CONVECTION THIS AFTERNOON WHILE THE MEMBER WITH MID 70 TDS IS
CONVECTIVELY MUCH MORE ACTIVE.

WILL KEEP AN EYE ON SATELLITE TREND NEXT HOUR OR SO AND MAKE SOME
FINAL TWEAKS TO POPS BASED ON TRENDS...BUT GENERALLY THINKING OF
MAINTAINING LOW (20-30) POPS THROUGH THE DAY SE COUNTIES WITH
LESSER...THOUGH NONE ZERO CHANCES FARTHER NORTH.

EXPECT SMOKE TO BE FAIRLY PREVALENT AGAIN TODAY AND HAVE MAINTAINED
HAZE IN THE GRIDS TO COVER THE MILKY/HAZY LOOK TO THE SKY THAT IS
ANTICIPATED. EVEN WITH THE SMOKE...TEMPS STILL MANAGED TO WARM
NICELY MONDAY...SO WITH 925MB TEMPS PROGGED TO BE A COUPLE DEGREES C
WARMER TODAY THINK GOING FORECAST HIGHS IN THE UPPER 80S/AROUND 90
LOOK REASONABLE. WEAK LAKE BREEZE COULD FORM RIGHT ALONG THE
ILLINOIS SHORE...POSSIBLY LEADING TO SOME LAKE COOLING AT TIMES THIS
AFTERNOON...BUT CONFIDENCE IS NOT HIGH AND KEPT LAKEFRONT TEMPS IN
THE SAME BALLPARK AS INLAND.

IZZI

&&

.LONG TERM...
311 AM CDT

WEDNESDAY THROUGH LABOR DAY...

WEAK UPPER LOW OVER INDIANA IS PROGGED TO CONTINUE TO
WEAKEN/DISSIPATE...SO AFTER TODAY PRECIP CHANCES LOOK TO BE SLIM AT
BEST ACROSS THE AREA THROUGH THE UPCOMING HOLIDAY WEEKEND.
UNSEASONABLY STRONG UPPER RIDGE IS FORECAST TO HOLD STRONG THROUGH
THE HOLIDAY WEEKEND WITH ABNORMALLY WARM AND RATHER HUMID CONDITIONS
LIKELY TO PERSIST. DAYTIME HIGHS LOOK TO REMAIN IN THE UPPER
80S/LOWER 90S EACH DAY THROUGH THE REST OF THE WEEK AND OVER THE
HOLIDAY WEEKEND. AFTERNOON LAKE BREEZES LOOK FAIRLY LIKELY EACH
DAY...ESPECIALLY THUR-SAT...PROVIDING A BIT OF NATURAL AIR
CONDITIONING FOR LAKE ADJACENT AREAS. MEDIUM RANGE MODELS SUGGEST
A STRONGER GRADIENT BY SUNDAY AND ESPECIALLY MONDAY WHICH SHOULD
SEND THE HEAT RIGHT UP TO THE LAKEFRONT. IN FACT...IF CURRENT
MODELS END UP BEING PERFECT PROGS THEN HIGHS BY MONDAY COULD CLIMB
INTO THE MID 90S AS 925MB TEMPS REACH 27C.

IZZI

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 12Z...

* LOW POSSIBILITY FOR ISOLATED SHOWERS/THUNDERSTORMS THIS
  AFTERNOON.

RODRIGUEZ

//DISCUSSION...UPDATED 12Z...

ALTHOUGH VFR CONDITIONS IN PLACE THIS MORNING...ISOLATED SHOWERS
ARE TRYING TO DEVELOP NEAR THE TERMINALS. AN ISOLATED SHOWER MAY
BE POSSIBLE OVER THE NEXT COUPLE OF HOURS...BUT WITH THE HIGHER
CHANCES FOR DEVELOPMENT REMAINING TO THE SOUTH THIS MORNING. ANY
LINGERING FOG WILL QUICKLY DISSIPATE OVER THE NEXT HOUR...AS
SOUTH/SOUTHWEST WINDS STEADILY INCREASE THROUGH MIDDAY. SIMILAR
PRECIP TRENDS MAY OCCUR ONCE AGAIN THIS AFTERNOON...WITH HIGHER
COVERAGE OF SHOWERS/THUNDERSTORMS POSSIBLY PUSHING FURTHER NORTH
NEAR THE TERMINALS. HOWEVER...STILL THINK HIGHER CHANCES FOR
PRECIP THIS AFTERNOON WILL REMAIN TO THE SOUTH OF THE TERMINALS.

RODRIGUEZ


//ORD AND MDW CONFIDENCE...UPDATED 12Z...

* LOW CONFIDENCE WITH SHOWERS/THUNDERSTORMS THIS AFTERNOON.

* HIGH CONFIDENCE WITH WIND SPEED/DIRECTION.

RODRIGUEZ

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

WEDNESDAY NIGHT...VFR.

THURSDAY...VFR.

FRIDAY...VFR.

SATURDAY...VFR.

SUNDAY...VFR.

MONDAY...SLIGHT CHANCE OF TSRA.

RODRIGUEZ

&&

.MARINE...
218 AM CDT

HIGH PRESSURE WILL CONTINUE TO BE A DOMINATE FEATURE ACROSS THE
EASTERN THIRD OF THE COUNTRY THIS WEEK...WHILE THE BULK OF ANY
SYSTEMS CONTINUE TO STAY AWAY FROM THE REGION. SOUTHERLY FLOW WILL
CONTINUE TODAY INTO TONIGHT...WITH WINDS TURNING MORE NORTHERLY AS
A WEAK BOUNDARY PUSHES ACROSS THE NORTHERN PORTION OF THE LAKE
LATE TONIGHT INTO WEDNESDAY. DESPITE THIS TURNING WIND
FIELD...SPEEDS LOOK TO REMAIN ON THE LIGHTER SIDE. WINDS WILL
RETURN TO MORE OF A SOUTHERLY DIRECTION BY THE END OF THE WORK
WEEK. FOG IS ONCE AGAIN PRESENT OVER THE OPEN WATERS EARLY THIS
MORNING AND AFFECTING PRIMARILY THE ILLINOIS NEARSHORE
WATERS...WITH DENSE FOG LIKELY. DENSE FOG ADVISORY WILL REMAIN
THROUGH THE MORNING...BUT WILL NEED TO MONITOR POSSIBLE EXTENSION
AND EXPANSION INTO THE REMAINING AREAS OF THE NEARSHORE WATERS.

RODRIGUEZ

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...DENSE FOG ADVISORY...LMZ740-LMZ741-LMZ777-LMZ779 UNTIL 10 AM
     TUESDAY.

&&

$$

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