Area Forecast Discussion
Issued by NWS Chicago, IL

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000
FXUS63 KLOT 260539
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1239 AM CDT WED AUG 26 2015

.SHORT TERM...

TONIGHT THROUGH THURSDAY NIGHT...

232 PM...GENERALLY QUIET WEATHER EXPECTED THRU THE PERIOD.

LOW PRESSURE OVER JAMES BAY WILL CONTINUE TO LIFT NORTHEAST TONIGHT
AS HIGH PRESSURE OVER THE PLAINS SLOWLY SPREADS EAST TONIGHT AND
WEDNESDAY. WINDS WILL TURN MORE NORTHERLY ACROSS THE LAKE LATER
TONIGHT INTO WEDNESDAY MORNING AS THE HIGH APPROACHES. WITH THE
COLDER TEMPS ALOFT...RAIN SHOWERS WILL BE LIKELY EAST OF LAKE
MICHIGAN BUT SOME OF THESE MAY MAKE IT INTO NORTHEAST PORTER COUNTY
LATE TONIGHT INTO WEDNESDAY MORNING. APPEARS MOST OF THIS WILL
REMAIN EAST OF THE CWA AND MAINTAINED A DRY FORECAST.

EDGE OF THE CLOUD COVER CONTINUES TO SLOWLY MOVE EAST AND MAY SEE
SOME DECREASE IN CLOUDS DIURNALLY THIS EVENING BUT LAKE EFFECT CLOUD
COVER IS EXPECTED TO INCREASE OVERNIGHT INTO WEDNESDAY MORNING AND
THIS COULD LINGER THROUGH MUCH OF WEDNESDAY...THOUGH DO EXPECT SOME
SCATTERING AND THINNING BY WEDNESDAY EVENING.

WHILE TEMPS SHOULD WARM INTO THE LOWER/MID 70S WEDNESDAY...WINDS
TURN NORTHEAST OFF LAKE MICHIGAN AND TEMPS COULD COOL INTO THE
LOWER/MID 60S NEAR THE LAKE BY EVENING. TEMPS WARM BACK INTO THE
UPPER 70S THURSDAY BUT EASTERLY WINDS WILL CONTINUE TO KEEP THE
LAKESHORE AREAS COOLER. CMS

&&

.LONG TERM...
329 PM CDT

FRIDAY THROUGH TUESDAY...

MORE ZONAL FLOW ALOFT RETURNING FRIDAY AS STACKED LOW MOVES CONTINUES
TO EXIT THE REGION TO THE EAST. UPPER LEVEL SHORTWAVE TROUGH
RIDING THROUGH UPPER RIDGE EJECTS EAST INTO THE PLAINS AND
APPROACHES THE AREA FRIDAY BRINGING INCREASED CLOUD COVER WITH
INCREASING POPS WEST TO EAST FRIDAY AFTERNOON AND EVENING. LOW
LEVEL WARM AIR ADVECTION/SOUTHERLY FLOW WILL HELP BOOST TEMPS WELL
INTO THE 70S APPROACHING 80 SOME LOCATIONS AHEAD OF INCREASING
CLOUDS. SOME MODEL DIFFERENCES IN TIMING AND TRACK OF THE
SHORTWAVE STILL TO BE RESOLVED IN COMING RUNS HOWEVER BEST WINDOW
FOR RAIN APPEARS TO BE LATE FRIDAY NIGHT AND SATURDAY MORNING
ACROSS THE LOCAL AREA.

THIS UPPER LEVEL SHORTWAVE MOVES OFF TO THE EAST ONLY SLOWLY SUNDAY
AS MODELS TRENDING TOWARD DEVELOPING A MORE AMPLIFIED FLOW
PATTERN AGAIN FOR EARLY NEXT WEEK. UPPER RIDGING PREVAILING ACROSS
THE AREA MONDAY AND TUESDAY POINTING TOWARD DRY WEATHER AGAIN THAT
PERIOD WITH MAX TEMPS WELL INTO THE 80S... VERY WARM HEADING INTO
THE END OF AUGUST.

ED F

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 06Z...

* HIGH END MVFR DECK PSBL THIS MORNING.

* LAKE BREEZE TURNS WINDS EAST EARLY THIS AFTN WITH SPEEDS LESS
  THAN 10 KT.

JEE

//DISCUSSION...UPDATED 06Z...

BKN TO OVC CIGS SPAN THE REGION WITH HIGH END MVFR CIGS PUSHING
SOUTH OUT OF WISCONSIN. DECIDED TO LOWER CIG HEIGHTS TO HIGH END
MVFR AND KEEP A SCATTERED GROUP FOR PSBL 025 CIGS. GUIDANCE IS NOT
HANDLING THE CIGS WELL SO MVFR CIGS MAY LIFT TO VFR BEFORE
18Z...BUT LEFT THEM IN THROUGH 18Z DUE TO A LACK OF CONFIDENCE.
LIGHT NORTH WINDS WILL BECOME EAST EARLY THIS AFTN BEHIND A LAKE
BREEZE. SOME GUIDANCE MEMBERS INDICATE THE LAKE BREEZE COULD PUSH
THROUGH AS LATE AS 20Z...BUT DECIDED TO LEAVE WELL ENOUGH ALONE
FOR NOW ESPECIALLY SINCE WIND SPEEDS WILL BE LESS THAN 10 KT
BEHIND THE LAKE BREEZE. WINDS WEAKEN EVEN MORE TONIGHT AND BECOME
VARIABLE.

JEE


//ORD AND MDW CONFIDENCE...UPDATED 06Z...

* LOW CONFIDENCE ON HOW FAR SOUTH THE HIGH END MVFR DECK WILL
  EXPAND AND HOW LONG IT WILL PERSIST.

* MEDIUM CONFIDENCE IN TIMING OF LAKE BREEZE...HIGH CONFIDENCE IN
  WIND SPEEDS LESS THAN 10 KT.

JEE

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

THURSDAY...VFR.

FRIDAY...CHANCE OF TSRA LATE.

SATURDAY...CHANCE OF TSRA.

SUNDAY...VFR.

MONDAY...VFR.

RODRIGUEZ

&&

.MARINE...
303 PM CDT

LOW PRESSURE NEAR JAMES BAY WILL MOVE ONLY SLOWLY EAST TONIGHT AND
WEDNESDAY. THIS WILL ALLOW A RIDGE OF HIGH PRESSURE OVER THE
NORTHERN PLAINS TO BUILD SLOWLY EAST INTO THE WESTERN GREAT LAKES
BY WEDNESDAY EVENING. WINDS WILL CONTINUE TO EASE AS THE LOW MOVES
AWAY AND THE RIDGE BUILDS OVER THE AREA THROUGH WEDNESDAY.

HIGH PRESSURE MOVING OVERHEAD EARLY THURSDAY WILL BRING A PERIOD
OF LIGHT AND VARIABLE WINDS DURING THAT TIME. AS THE HIGH MOVES
EAST LATER ON THURSDAY AND THURSDAY NIGHT INTO FRIDAY...
SOUTHERLY WINDS WILL SET UP ON THE BACK SIDE OF THE HIGH AND
INCREASE MODESTLY FRIDAY. WEAK LOW PRESSURE OVER THE CENTRAL
PLAINS WILL THEN LIFT NORTHEAST ON SATURDAY REACHING SOUTHERN LAKE
MICHIGAN SUNDAY... HELPING TO MAINTAIN A GENERALLY LIGHT WIND
REGIME THROUGH THE WEEKEND.

ED F

&&

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

$$

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