Area Forecast Discussion
Issued by NWS Chicago, IL

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000
FXUS63 KLOT 312000
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
300 PM CDT SUN MAY 31 2015

.SHORT TERM...
218 PM CDT

THROUGH MONDAY...

UNSEASONABLY COLD CONDITIONS WILL CONTINUE REST OF TODAY AND
TOMORROW BEHIND A STRONG COLD FRONT THAT DROPPED ACROSS THE REGION
YESTERDAY...THOUGH A WARMING TREND IS EXPECTED THROUGH THE
UPCOMING WEEK. HIGH TEMPS TODAY IN CHICAGOLAND WOULD BE EXPECTED
IN LATE MARCH OR EARLY APRIL...AND WE`RE CLOSE TO NORMAL LOWS FOR
THIS TIME OF YEAR. FOR AREAS STILL UNDER CLOUD COVER TODAY...DO
NOT ANTICIPATE ANY RAPID CLEARING FOR REST OF TODAY OR TONIGHT
WITH MOISTURE TRAPPED UNDER A STRONG INVERSION AT THE TOP OF THE
COLD AIRMASS. NORTH CENTRAL ILLINOIS DID ALREADY CLEAR OUT
HOWEVER AND ANTICIPATE THE EDGE OF THE STRATUS DECK TO CONTINUE
TO SLOWLY ERODE THROUGH SUNSET. HIGH PRESSURE CENTERED NEAR LAKE
SUPERIOR THIS AFTERNOON WILL REMAIN QUASI-STATIONARY WITH THE
INFLUENCE OF THE RIDGE GRADUALLY EXTENDING INTO THE MIDWEST AND
MISSISSIPPI VALLEY OVERNIGHT. THIS WILL ALLOW WINDS TO DIMINISH
TONIGHT... ESPECIALLY OVER NORTH CENTRAL ILLINOIS CLOSEST TO THE
RIDGE AXIS AND UNDER MOSTLY CLEAR SKIES. TEMPERATURES ARE EXPECTED
TO RADIATE INTO THE UPPER 30S TO AROUND 40 WHERE SKIES CLEAR...BUT
SHOULD STAY PROPPED UP IN THE MID TO UPPER 40S ELSEWHERE. FOR
MONDAY...EXPECT CLOUD COVER TO CONTINUE TO SLOWLY ERODE FROM THE
NORTH WITH AREAS NORTH OF I-80 EXPECTED TO BE SUNNY BY MIDDAY.
ONSHORE FLOW THROUGH THE DAY WILL KEEP TEMPERATURES IN THE LOW TO
MID 50S WITHIN THE FIRST FEW MILES OF LAKE MICHIGAN...BUT FARTHER
INLAND EXPECT LOW TO MID 60S FOR THE FIRST DAY OF METEOROLOGICAL
SUMMER.

BMD

&&

.LONG TERM...
300 PM CDT

MONDAY NIGHT THROUGH SUNDAY...

THE WEATHER PATTERN THIS WEEK FAVORS VERY LOW CHANCES OF ANY HIGH
IMPACT WEATHER FOR THE FORECAST AREA. UPPER LEVEL WESTERLIES WILL
BE SPLIT OVER THE EASTERN HALF OF NORTH AMERICA THROUGH
THURSDAY....WITH A WEAK CUT OFF LOW ACROSS THE LOWER MISSISSIPPI
AND TENNESSEE VALLEYS. THIS PATTERN WILL FAVOR LITTLE IN WAY OF
PROGRESSIVE SYSTEMS AND PRECIPITATION CHANCES.

SURFACE RIDGING WILL REMAIN ANCHORED FROM EASTERN CANADA THROUGH THE
GREAT LAKES DURING THE FIRST HALF OF THE WEEK AND WILL BASICALLY
SLOWLY WEAKEN IN ITS PLACE THROUGH THURSDAY. EACH DAY THIS WILL
ALLOW FOR THE DEVELOPMENT OF MESOSCALE LAKE BREEZES...AIDED BY
SYNOPTIC EASTERLY FLOW ON TUESDAY AND POSSIBLY WEDNESDAY TOO. IT IS
POSSIBLE THE MIDWEEK LAKE BREEZES COULD BE PRETTY STOUT AND FAR
REACHING FOR EARLY JUNE GIVEN SOME OF THE RECENT COOLER WATERS
HAVING ADVECTED/UPWELLED INTO THE NEARSHORE AREAS /CHICAGO SHORE
TEMPERATURE HAVING DROPPED 7 DEGREES THE PAST 24 HOURS/. OVERALL
THOUGH...A SLOW MODIFICATION OF THE AIR MASS WILL ALLOW TEMPERATURES
TO INCH UP EACH DAY WITH READINGS RIGHT AROUND NORMAL BY WEDNESDAY.

SUCH AS HAS BEEN THE TREND...HAVE SLOWED A WELL-VERIFYING MODEL
BLEND OF RAIN CHANCES IN THE EXTENDED...AS SUCCESSIVE RUNS OF GLOBAL
MODELS HAVE SLOWED AND COULD SEE THAT CONTINUING WITHIN THE FORECAST
PATTERN. A WEAK NORTHERN STREAM COOL FRONT IS PRESENTLY FORECAST TO
MOVE THROUGH THE GREAT LAKES REGION ON FRIDAY OR EARLY NEXT
WEEKEND.

MTF

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 20Z...

* MVFR CEILINGS EARLY THIS AFTERNOON

* GUSTY NORTHEAST WINDS THROUGH EARLY THIS EVENING.

MM

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

REMNANT MOISTURE STREAMING ONSHORE FROM LAKE MICHIGAN HAS
TRANSITIONED FURTHER SOUTHEAST AND CONTINUES TO AFFECT GYY. OTHER
TERMINALS WILL SEE A CONTINUAL IMPROVEMENT THROUGH THIS AFTERNOON
TO BECOME LOW VFR AROUND 21-22Z. ACCELERATED IMPROVEMENTS WILL BE
SEEN FROM THAT POINT ONWARD AS SEEN IN THE RFD OBSERVATIONS.

LOW MOISTURE CONTENT WILL REMAIN FOR MONDAY...WITH JUST SCT
CLOUDS POSSIBLE. WINDS WILL BECOME LIGHTER BUT REMAIN FROM THE
NORTHEAST...RISING ABOVE 12KT IN THE MORNING HOURS. A FEW
AFTERNOON GUSTS MAY REACH INTO THE MID-TEENS ON MONDAY. THE NEXT
FEW DAYS WILL FEATURE SIGNIFICANT LAKE BREEZE PENETRATION.

MM

//ORD AND MDW CONFIDENCE...UPDATED 20Z...

* MEDIUM HIGH ON MVFR CEILINGS AND TIMING.

* HIGH ON WINDS THROUGH TONIGHT...MEDIUM ON WIND SPEEDS MONDAY.

MM

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

* MONDAY NIGHT AND TUESDAY...DRY/VFR. NORTHEAST WINDS.
* WEDNESDAY AND THURSDAY...DRY/VFR. EASTERLY WINDS.
* FRIDAY...SLIGHT CHANCE OF TSRA. SOUTHWEST WINDS.
* SATURDAY...SLIGHT CHANCE OF TSRA. NORTH WINDS.

&&

.MARINE...
218 PM CDT

A TIGHT PRESSURE GRADIENT PERSISTS THIS AFTERNOON...ESPECIALLY
ACROSS THE SOUTH END OF LAKE MICHIGAN WHICH LIES BETWEEN HIGH
PRESSURE CENTERED NEAR LAKE SUPERIOR AND LOW PRESSURE OVER THE
UPPER OHIO VALLEY. THE HIGH WILL SLOWLY EXERT ITS INFLUENCE OVER
LAKE MICHIGAN OVER THE NEXT COUPLE DAYS ALLOWING THE MODERATELY
STRONG WINDS AND LARGE WAVES CURRENTLY IN PLACE TO CONTINUE TO
DIMINISH. A SMALL CRAFT ADVISORY WILL REMAIN IN EFFECT FOR THE
INDIANA AND ILLINOIS NEARSHORE WATERS THROUGH MONDAY MORNING...AND
EXPECT WAVES TO SUBSIDE BELOW CRITERIA BY AROUND MIDDAY. TUESDAY
THROUGH THURSDAY AND PERHAPS FRIDAY...WINDS SHOULD BE RELATIVELY
LIGHT ACROSS THE LAKE ALLOWING AFTERNOON LAKE BREEZES TO FORM
WITH ONSHORE FLOW.

BMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...BEACH HAZARDS STATEMENT...ILZ006-ILZ014 UNTIL 10 PM SUNDAY.

IN...BEACH HAZARDS STATEMENT...INZ001-INZ002 UNTIL 10 PM SUNDAY.

LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 10 AM MONDAY.

&&

$$

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