Area Forecast Discussion
Issued by NWS Chicago, IL

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000
FXUS63 KLOT 031752
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1252 PM CDT FRI JUL 3 2015

.SHORT TERM...
313 AM CDT

THROUGH SATURDAY...

SATELLITE IMAGERY EARLY THIS MORNING SHOWS A WEAK UPPER LEVEL LOW
OVER THE MID MISSISSIPPI VALLEY PRODUCING EXTENSIVE MID-HIGH LEVEL
CLOUDINESS OVER THE REGION. REGIONAL RADAR MOSAIC DOES SHOW QUITE A
BIT OF RETURNS OVER SE IA/WESTERN ILLINOIS...HOWEVER SURFACE OBS
SUGGEST CLOUD BASES ARE QUITE HIGH AND ONLY SEEN A FEW REPORTS OF
RAIN REACHING THE GROUND. BIG CHANGE TO TODAY`S FORECAST WAS TO BUMP
UP CLOUD COVER CONSIDERABLY INTO EARLY AFTERNOON...WITH GRADUAL
CLEARING LATE IN THE DAY FROM THE NORTH AS THIS SYSTEM SLOWLY PUSHES
SE. ALSO ADDING SOME SLIGHT CHANCE POPS FOR LIGHT SHOWERS/SPRINKLES
TO SOUTHERN CWA. CLOUD COVER SHOULD HELP KEEP TEMPS A BIT COOLER
THAN PREVIOUSLY FORECAST AND HAVE NUDGED HIGHS DOWN A BIT...MAINLY
SOUTHERN HALF OF THE CWA. WINDS OFF THE LAKE SHOULD RESULT IN
ANOTHER DAY IN THE 60S AT THE BEACHES.

HEIGHTS WILL BEGIN TO RISE CONSIDERABLY TONIGHT INTO SATURDAY IN THE
WAKE OF THIS DISTURBANCE WHILE LOW LEVEL FLOW TURNS LIGHT SOUTHERLY
WITH WARM AIR ADVECTION COMMENCING. GRADIENT LOOKS TO BE TOO WEAK TO
PREVENT A LAKE BREEZE FROM FORMING SATURDAY...BUT MAGNITUDE OF LAKE
COOLING SHOULD BE FAR LESS AND WITH AMPLE SUNSHINE TEMPS WILL BE
MUCH WARMER THAN TODAY AND CLOSER TO SEASONAL NORMS.

IZZI

&&

.LONG TERM...
313 AM CDT

SATURDAY NIGHT THROUGH THURSDAY...

SUNDAY LOOKS TO BE QUITE WARM AND GUIDANCE HAS ALL TRENDED WARMER
WITH 925MB TEMPS NOW PROGGED TO BE IN THE 22-24C RANGE SUNDAY
AFTERNOON WHICH WOULD SUPPORT HIGHS IN THE UPPER 80S. ONCE AGAIN
GRADIENT MAY BE TOO WEAK TO TOTALLY SUPPRESS LAKE BREEZE...ESPECIALLY
ALONG ILLINOIS SHORE...BUT LAKE INFLUENCE SHOULD BE MUCH LESS WITH
TEMPS PROBABLY MANAGING TO HIT 80 FOR AT LEAST A TIME ALONG THE
LAKE. STRONGER SOUTHERLY WINDS EXPECTED TO PREVENT LAKE COOLING
MONDAY AHEAD OF THE APPROACHING COLD FRONT. BLENDED MODEL GUIDANCE
HAS HIGHS IN THE MID 80S MONDAY...THOUGH IF CLOUD COVER ISNT TOO
EXTENSIVE WE COULD EASILY BE PUSHING AT LEAST UPPER 80S MONDAY.

COLD FRONT LOOKS TO ARRIVE MONDAY NIGHT/TUESDAY TIME FRAME WITH
ASSOCIATED SHOWER/T-STORM CHANCES ACCOMPANYING THE FRONT. BLENDED
MODEL GUIDANCE WOULD MAINTAIN PERIOD AFTER PERIOD OF POPS TUESDAY
ONWARD...BUT ECMWF AND GFS SUGGEST FRONT CLEARS THE AREA AND SHOULD
ALLOW FOR DRY CONDITIONS TUES NIGHT THROUGH WED EVENING BEFORE FRONT
POTENTIALLY TRIES TO CREEP BACK NORTH AS A WARM FRONT LATER NEXT
WEEK WITH A RETURN OF PRECIP CHANCES.

IZZI

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 18Z...

* LIGHT EASTERLY WINDS THROUGH EARLY AFTERNOON WITH A SLIGHT
  INCREASE IN SPEED TO NEAR 10 KT MID AFTERNOON.

* LIGHT WESTERLY WINDS SATURDAY BUT POSSIBLE SHIFT TO EAST OR
  SOUTHEAST LATER SATURDAY AFTERNOON WITH LAKE BREEZE.

MDB

//DISCUSSION...UPDATED 18Z...

HIGH PRESSURE ACROSS THE REGION CONTINUES TO RESULT IN LIGHT AND
VARIABLE WINDS...WITH AN EASTERLY DIRECTION FAVORED. LAKE
INFLUENCE MAY REINFORCE EAST TO NORTHEAST WINDS AT ORD/MDW BY MID
AFTERNOON SO A SLIGHT UPTICK IN WIND SPEEDS MAY OCCUR BUT SPEEDS
LOOK TO BE UNDER 10 KT THE MAJORITY OF THE TIME. GYY SHOULD SEE A
STEADIER NORTHEAST WIND THROUGH THE AFTERNOON. WINDS WILL DIMINISH
AND TURN SOUTHEASTERLY EARLY THIS EVENING THEN TREND TO THE WEST
AND SOUTHWEST LATE TONIGHT. LIGHT WEST WINDS ARE EXPECTED SATURDAY
AND A LAKE BREEZE IS EXPECTED TO DEVELOP. THERE IS SOME
INDICATION IT MAY BE MORE OF A SOUTHEASTERLY LAKE BREEZE WHICH
WOULD HAVE A TOUGHER TIME REACHING ORD/MDW BUT WITH SUCH A WEAK
FLOW REGIME A MORE TYPICAL EASTERLY LAKE BREEZE WITH A FURTHER
INLAND PUSH MAY RESULT. WILL KEEP A LIGHT WESTERLY WIND AT ORD FOR
SATURDAY AFTERNOON FOR NOW BUT THERE IS POTENTIAL FOR AN EAST TO
SOUTHEAST SHIFT...THOUGH SPEEDS WOULD PROBABLY BE UNDER 10 KT.

MDB

//ORD AND MDW CONFIDENCE...UPDATED 18Z...

* MEDIUM-HIGH CONFIDENCE IN UPTICK IN WIND SPEEDS LATE THIS
  AFTERNOON THANKS TO LAKE INFLUENCES.

* LOW CONFIDENCE THAT LAKE BREEZE WIND SHIFT WILL ARRIVE AT
  ORD/MDW SATURDAY AFTERNOON.

MDB

//OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z...

SATURDAY NIGHT...DRY. VFR. S WINDS.
SUNDAY...DRY. VFR. S WINDS. LAKE BREEZE PSBL.
MONDAY...TSRA LIKELY LATE. SW WINDS.
TUESDAY...CHC TSRA. NW WINDS BECOMING NE.
WEDNESDAY...DRY. VFR. E WINDS.
THURSDAY...CHC TSRA. NW WINDS.

BMD

&&

.MARINE...
240 AM CDT

A RIDGE STRETCHES FROM WISCONSIN ACROSS SOUTHERN LAKE MICHIGAN
INTO MICHIGAN THIS MORNING RESULTING IN LIGHT AND VARIABLE WINDS
ACROSS THE SOUTH HALF OF THE LAKE...AND SOUTHWEST WINDS ACROSS THE
NORTH. THE NORTHERN HALF OF THE LAKE WILL SEE WINDS INCREASING
INTO THE 15 TO 25 KT RANGE THIS AFTERNOON AND EVENING AHEAD OF AN
APPROACHING FRONT. MEANWHILE...THE SOUTH HALF WILL CONTINUE TO
SEE LIGHT WINDS WITH LAKE BREEZES RESULTING IN ONSHORE FLOW THIS
AFTERNOON. THE FRONT WILL BEGIN TO SAG ACROSS THE NORTH HALF OF
LAKE MICHIGAN LATE TONIGHT...DROPPING TO AROUND MIDLAKE
SATURDAY...THEN LIFTING NORTH AGAIN. SOUTH WINDS FRESHEN UP ACROSS
THE LAKE AGAIN SUNDAY NIGHT INTO MONDAY AHEAD OF A STRONGER COLD
FRONT PROGGED TO SWEEP ACROSS THE LAKE MONDAY NIGHT.

BMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

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