Area Forecast Discussion
Issued by NWS Chicago, IL

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000
FXUS63 KLOT 281929
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
229 PM CDT THU MAY 28 2015

.SHORT TERM...
225 PM CDT

THROUGH TONIGHT...

THE FORECAST AREA FINDS ITSELF BETWEEN TWO STATIONARY FRONTS
THIS AFTERNOON WITH A WEAK RIDGE OF HIGH PRESSURE SANDWICHED IN
BETWEEN DIRECTLY OVER THE AREA. THIS RIDGE HAS ALLOWED A LAKE
BREEZE WITH LAKESIDE COOLING AT THE CHICAGO SHORE ABOUT 14
DEGREES COOLER THAN INLAND AT ORD/MDW AS OF 200 PM. THE FRONT OF
INTEREST FOR OUR AREA TONIGHT WILL BE THE ONE TO THE SOUTH WHICH
WILL LIFT NORTH AS A WARM FRONT...BRINGING A RETURN TO MUGGY AIR
BY DAYBREAK...AS WELL AS KEEP NIGHTTIME TEMPERATURES MILD...EVEN
INCREASING THEM LATE TONIGHT ALONG THE LAKE SHORE AREAS.

MULTIPLE MID-LEVEL DISTURBANCES...SOME LIKELY CONVECTIVELY
ENHANCED...ARE NOTED ON WATER VAPOR AND RADAR MOSAIC IMAGERY ACROSS
THE CENTRAL PLAINS THIS AFTERNOON. ONE OF THESE JUST NORTH OF KANSAS
CITY AS OF 200 PM IS WELL ANALYZED BY THE LATEST RAP AND THIS IS
EXPECTED TO PROPAGATE INTO WISCONSIN OVERNIGHT...WITH ONE OR TWO
WEAKER IMPULSES TO ITS SOUTH APPROACHING THE AREA. WITH A 25-30 KT
LOW-LEVEL JET AHEAD OF THESE AND INCREASING MOISTURE AT THAT
HEIGHT...THERE WILL LIKELY BE SCATTERED SHOWERS OR STORMS FROM
SOUTHWEST WISCONSIN INTO NORTHWEST AND POSSIBLY NORTH CENTRAL
ILLINOIS OVERNIGHT.

MTF

&&

.LONG TERM...

TO BE ISSUED SHORTLY.

&&

.AVIATION...

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

* LAKE BREEZE WINDS VARYING FROM 080-120 AT 8-14KT THIS AFTERNOON

* -SHRA BECOMING TSRA FRIDAY AFTERNOON

MM

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

WEAK HIGH PRESSURE DRIFTING EASTWARD HAS INFLUENCED A SOUTHEAST
FLOW. LAKE MICHIGAN HAS TAKEN HOLD OF THE WINDS AT ORD/MDW/GYY
WITH WINDS NOW EASTERLY OVER 10KT. OBSERVATIONS HAVE SHOWN SOME
GUSTS TO 15KT AS WELL FROM THE EAST TO SOUTHEAST. AFTER 01Z...THE
WINDS WILL RELAX SOME TO BECOME LESS THAN 10KT. OVERALL FLOW WILL
ALSO THEN BECOME SOUTHERLY AS LOW PRESSURE APPROACHES FROM THE
WEST EARLY FRIDAY. SOME RAIN SHOWERS ARE EXPECTED AND A CANOPY OF
BKN100 CEILINGS ARE EXPECTED AT MOST SITES.

TIMED OUT BEST CHANCE FOR TSRA BASED ON INSTABILITY INCREASING IN
THE 15-19Z TIMEFRAME...ALONG WITH THE POTENTIAL FOR A WAVE TO
HELP LIFT THINGS OFF DURING THAT TIME. LOOKING FORWARD...A BETTER
CHANCE FOR WIDESPREAD PRECIPITATION EXISTS EARLY SATURDAY.

MM

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

* MEDIUM TO HIGH CONFIDENCE IN EAST WINDS THROUGH 01Z WITH MEDIUM
  CONFIDENCE IN WIND SPEEDS.

* MEDIUM CONFIDENCE IN SHRA AND TSRA OCCURRING FRIDAY...WITH LOW
  CONFIDENCE ON TIMING.

MM

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

FRIDAY NIGHT...PERIODIC SHRA/TSRA. MVFR POSSIBLE. SOUTHWEST WINDS.

SATURDAY....CHANCE SHRA EARLY. MVFR POSSIBLE. STRONG NORTH-
NORTHEAST WINDS.

SUNDAY...VFR/WX NIL. NORTHEAST WINDS.

MONDAY...VFR/WX NIL. EAST WINDS.

TUESDAY...VFR/WX NIL. SOUTHEAST WINDS.

WEDNESDAY...SLIGHT CHANCE SHRA. SOUTH WINDS.

KREIN

&&

.MARINE...
225 PM CDT

A SURFACE COLD FRONT DRAPED FROM WEST-TO-EAST ACROSS THE NORTHERN
PART OF THE LAKE WILL SHIFT NORTHWARD THIS EVENING. THIS WILL BE A
SOURCE FOR FOG ALONG IT AND THIS HAS BEEN SEEN ON VISIBLE SATELLITE
AT TIMES DURING THURSDAY. EVEN HIGHER MOISTURE WILL MOVE NORTHWARD
ACROSS THE LAKE ON FRIDAY ALLOWING FOR THE POSSIBILITY OF FOG AS
WELL...ESPECIALLY WHERE SHOWERS ARE NOT PREVALENT.

LOW PRESSURE WILL MOVE EAST INTO QUEBEC ON FRIDAY NIGHT AND STEER
A COLD FRONT SOUTHEASTWARD ACROSS THE LAKE. AS HIGH PRESSURE
BUILDS SOUTHWARD FROM ONTARIO ON SATURDAY...IT WILL DRIVE A STRONG
NORTHERLY WINDS FOR LATE MAY ACROSS THE CENTRAL AND SOUTHERN PARTS
OF THE LAKE. THIS WILL RESULT IN SMALL CRAFT ADVISORY CONDITIONS
FOR THE ILLINOIS AND INDIANA NEARSHORE AREAS SATURDAY AFTERNOON
AND NIGHT WITH LINGERING HIGH WAVES ON SUNDAY.

MTF

&&

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

$$

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