Area Forecast Discussion
Issued by NWS Chicago, IL

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS63 KLOT 041904
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
204 PM CDT SAT JUL 4 2015

.SHORT TERM...
203 PM CDT

THROUGH SUNDAY AFTERNOON...

THE LAKE BREEZE BOUNDARY CONTINUES TO MOVE INLAND TOWARDS ORD/MDW
AND INTO NORTHERN LAKE AND PORTER COUNTIES IN INDIANA. STILL AN OFF
CHANCE FOR A ROGUE SHORT LIVED SHOWER OR STORM POPPING ON THE LAKE
BREEZE BOUNDARY YET THIS AFTERNOON BEFORE THE BOUNDARY WASHES OUT
EARLY THIS EVENING. CU IS MOST EXTENSIVE SOUTH OF A MDW-JOT LINE
WITH ANOTHER AREA TOWARD THE WI BORDER AT MID AFTERNOON WHICH IS
COINCIDENT WITH THE SMALL AMOUNT OF INSTABILITY THAT HAS BEEN
DEVELOPING...WITH A FEW CU IN BETWEEN THESE AREAS. OTHERWISE TEMPS
WILL BE A LITTLE SLOWER TO COOL THAN PREVIOUS EVENINGS AND LEVEL OFF
IN THE LOWER 60S FOR MOST AREAS OVERNIGHT BUT WITH MID 60S IN THE
CHICAGO METRO AREA. AN UPPER LEVEL RIDGE WILL CREST THE AREA TONIGHT
WHILE A SHORTWAVE TROUGH MOVING ACROSS THE EASTERN DAKOTAS AND
NEBRASKA THIS AFTERNOON DAMPENS OUT. DRY CONDITIONS WILL PERSIST AND
THE AIRMASS WILL MODIFY WITH H85 TEMPS WARMING SLIGHTLY TO 15-16C
AND H92 TEMPS WARMING TO 21-22C. LOCAL H85/H92 CLIMATOLOGY SUPPORTS
HIGHS IN THE MID/UPPER 80S. SOUTHERLY WINDS WILL STEADILY INCREASE
THROUGH THE AFTERNOON SO THE INCREASED MIXING MAY ALLOW A FEW SITES
TO REACH 90. THE LAKE BREEZE DETAILS WILL BE SOMEWHAT TROUBLESOME TO
PIN DOWN. FLOW WILL BE VERY LIGHT THROUGH THE MORNING WHICH WOULD
SUPPORT AN INLAND MOVING BOUNDARY ALLOWING AREAS WITHIN A FEW MILES
OF THE LAKE TO COOL INTO THE LOWER 70S AFTER AN INITIAL WARM UP IN
THE MORNING BUT THE STEADILY INCREASING WIND MAY HELP PUSH THE
BOUNDARY BACK TOWARDS THE LAKE ALLOWING MANY OF THESE SAME AREAS TO
WARM UP LATE IN THE DAY. IF THAT OCCURS AS EXPECTED LAKEFRONT AREAS
OF ILLINOIS WOULD LIKELY BE HELD TO AROUND 80 FOR HIGHS WITH
NORTHEAST LAKE COUNTY IL BEING A BIT COOLER WITH A SOUTHEAST WIND
OF THE LAKE SETTING UP THERE. NORTHWEST INDIANA LAKESHORE AREAS
SHOULD WARM TO THE MID/UPPER 80S WITH OFFSHORE FLOW TAKING OVER
DURING THE AFTERNOON.

MDB

&&

.LONG TERM...
305 AM CDT

SUNDAY NIGHT THROUGH FRIDAY...
SOUTHERLY WINDS INCREASE MONDAY IN ADVANCE OF COLD FRONT AND COULD
SET THE STAGE FOR TEMPS TO REACH 90...ESPECIALLY EASTERN/SOUTHERN
CWA. DEBRIS CLOUDINESS FROM SUNDAY`S CONVECTION IS A BIT OF A WILD
CARD...BUT IF IT ISNT TOO EXTENSIVE THEN LOWER 90S WOULD BE
ATTAINABLE. SHOWERS/STORMS COULD MAKE IT INTO OUR NW CWA BY LATER IN
THE AFTERNOON...BUT BEST CHANCE OF STORMS WITH THE FRONT APPEARS TO
BE MONDAY NIGHT SPREADING SOUTHEAST ACROSS CWA. FRONT SHOULD CLEAR
SE CWA BY EARLY-MIDDAY TUESDAY WITH SOME THREAT OF STORMS
POTENTIALLY LINGERING INTO TUESDAY...MAINLY SE CWA. SOME GUIDANCE
CONTINUES TO INDICATE THAT THE FRONT WILL HANG UP AND COULD BE CLOSE
ENOUGH TO PROVIDE SOME THREAT OF SHOWERS AND STORMS WED NIGHT
ONWARD...THOUGH TENDENCY USUALLY IS FOR THESE FRONTS TO GET SHAVED
FURTHER SOUTH THAN GUIDANCE INDICATES SO QUITE POSSIBLY COULD REMAIN
DRY FOR THE REMAINDER OF THE WEEK FOLLOWING THE MON NIGHT/TUES
FROPA. COOLER/LESS HUMID CONDITIONS EXPECTED BEHIND THE FRONT WITH A
RETURN TO BELOW AVERAGE TEMPS AND EVEN COOLER WEATHER NEAR THE LAKE.

IZZI

&&

.AVIATION...

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

* LAKE BREEZE WIND SHIFT TO EAST AND ASSOCIATED TIMING AND SPEEDS.

* SMALL CHANCE FOR LAKE BREEZE SHIFT ON SUNDAY.

RC

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

WEAK HIGH PRESSURE OVER THE AREA AND LIGHT WINDS DUE TO IT
ARE SUPPORTING STEADY INLAND PROGRESSION OF LAKE BREEZE. HAVE
MOVED UP TIMING OF EAST WINDS AT MDW TO 1830Z...BUT KEPT ORD AT
20Z FOR NOW. WILL CONTINUE TO TRACK LAKE BREEZE VIA RADAR FOR ANY
TIMING CHANGES. SPEEDS APPEAR THEY WILL REMAIN MOSTLY BELOW 10 KT
GIVEN OBS BEHIND THE LAKE BREEZE...BUT CANNOT RULE OUT A BRIEF
PERIOD OF SPEEDS AROUND 10 KT. LIGHT SOUTHERLY WINDS TONIGHT WILL
PICK UP SOME ON SUNDAY AS HIGH PRESSURE SLIDES EAST. LAKE BREEZE
SHOULD STILL PUSH INLAND INTO ILLINOIS...BUT EXPECTING DEEPER
MIXING TO TAP INTO SOUTH TO SSW WINDS CLOSE TO 10 KT SUNDAY
AFTERNOON AND PREVENT IT FROM REACHING ORD AND MDW. PREDOMINANTLY
VFR CONDITIONS ARE IN STORE THROUGH THE PERIOD...WITH POSSIBLE
MINOR EXCEPTION OF PATCHY MVFR BR IN OUTLYING AREAS LATE TONIGHT
INTO EARLY SUNDAY.

RC

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

* HIGH IN LAKE BREEZE SHIFT TO EAST WINDS...MEDIUM-HIGH IN TIMING
  AND SPEEDS REMAINING PRIMARILY BELOW 10 KT.

* MEDIUM-HIGH THAT LAKE BREEZE WILL NOT PUSH THROUGH ORD AND MDW
  ON SUNDAY.

RC

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

SUNDAY NIGHT...VFR.

MONDAY...TSRA LIKELY MONDAY NIGHT. BREEZY SOUTH WINDS.

TUESDAY...CHANCE OF MORNING TSRA.

WEDNESDAY...VFR...CHANCE SHRA/TSRA WED NIGHT.

THURSDAY...SLIGHT CHANCE TSRA.

FRIDAY...SLIGHT CHANCE TSRA.

RODRIGUEZ

&&

.MARINE...
313 AM CDT

HIGH PRESSURE SPANNING THE REGION WILL MOVE LITTLE TODAY INTO
TONIGHT...BUT WITH A WEAKENING SOUTHWARD MOVING FRONTAL BOUNDARY
EXPECTED TO PUSH INTO NORTHERN LAKE MICHIGAN THIS MORNING.
HOWEVER...THIS FRONT WILL CONTINUE TO WEAKEN AS IT MOVES OVER THE
LAKE BUT WITH THE CURRENT SOUTHERLY WINDS TURNING MORE NORTHERLY
OVER THE NORTH HALF. WINDS WILL GENERALLY STAY SOUTHERLY ACROSS
THE SOUTH HALF TODAY...WITH WINDS OVER THE ENTIRE LAKE RETURNING
TO THE SOUTH LATER TONIGHT INTO SUNDAY. SOUTHERLY SPEEDS WILL
INCREASE SUNDAY AND SUNDAY NIGHT AS A TROUGH OF LOW PRESSURE
APPROACHES FROM THE WEST. WINDS REALLY RAMP UP ON MONDAY WITH THE
ARRIVAL OF THIS SYSTEM WITH WINDS OVER THE OPEN WATERS...MAINLY
THE NORTH HALF LIKELY APPROACHING 30KT WHILE THE SOUTH HALF STAYS
IN THE 15 TO 25 KT RANGE. HAZARDOUS WINDS FOR SMALL CRAFT APPEAR
POSSIBLE BY MIDDAY MONDAY WITH SPEEDS INCREASING INTO THE
AFTERNOON...AND WITH SPEEDS POSSIBLY APPROACHING 30KT DURING THIS
TIME.

RODRIGUEZ

&&

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

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.