Area Forecast Discussion
Issued by NWS Chicago, IL

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000
FXUS63 KLOT 302017
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
317 PM CDT TUE JUN 30 2015

.SHORT TERM...
210 PM CDT

THROUGH WEDNESDAY...

DECIDED TO REDUCE THE PRECIPITATION OUTLOOK SIGNIFICANTLY FOR THIS
AFTERNOON. THE MAIN UPPER LEVEL WAVE IS WELL TO OUR EAST OVER
EASTERN MI AND OHIO AND THICK CLOUD COVER IS NORTH OF I-80.  WAS
ORIGINALLY THINKING A FEW SHOWERS WOULD DEVELOP ALONG THE LAKE
BREEZE...BUT THE CLOUD COVER WILL LIKELY LIMIT ANY VERTICAL GROWTH
ESPECIALLY SINCE MOST PLACES HAVE NOT WARMED AS QUICKLY AS
ORIGINALLY THOUGHT.  KEPT A SLIGHT CHANCE OF THUNDERSTORMS ACROSS
SOUTHERN FORD...IROQUOIS...AND BENTON COUNTIES THIS AFTERNOON
ALTHOUGH WITHOUT ANY CLEAR FORCING...HAVE LOW CONFIDENCE IN ANY
SHOWERS OR STORMS FORMING.  THE LATEST RAP ANALYSIS DOES FEATURE
AROUND 1500 J/KG OF CAPE SOUTH OF I-80 SO IF ANY FORCING DOES
DEVELOP...STORMS ARE POSSIBLE.

EXPECTING DRY CONDITIONS THROUGH WEDNESDAY AS THE NEXT CONVECTIVE
SYSTEM WILL PASS TO OUR SOUTH OVER CENTRAL ILLINOIS.  TO PLAY IT
SAFE...PUT A SLIGHT CHANCE OF STORMS SOUTH OF A PONTIAC IL TO FOWLER
INDIANA LINE LATE WEDNESDAY AFTERNOON...BUT HAVE MEDIUM-LOW
CONFIDENCE IN STORMS GETTING THAT FAR NORTH TOMORROW.

DID NOT MAKE ANY MAJOR CHANGES TO TEMPS FOR TONIGHT AND TOMORROW.
WITH INCREASING CLOUD COVER OVERNIGHT AND DEWPOINTS IN THE MID 50S
TO LOW 60S...LOW TEMPS WILL GET INTO THE MID TO UPPER 50S. FLOW WILL
BE OFF OF THE LAKE TOMORROW RESULTING IN UNSEASONABLY COOL TEMPS
WITH HIGHS IN THE 70S. LOCATIONS ALONG THE LAKE WILL LIKELY STAY IN
THE LOW TO MID 60S.

JEE

&&

.LONG TERM...
313 PM CDT

WEDNESDAY NIGHT THROUGH TUESDAY...

MOST OF THE REMAINING FORECAST PERIOD WILL LIKELY SEE BELOW
NORMAL TEMPS AND WITH DRIER CONDITIONS. THIS WILL BE THE CASE
WEDNESDAY NIGHT AS EXPECTED SHOWERS/THUNDERSTORMS ACROSS THE
CENTRAL PLAINS LIKELY DRIFT EAST SOUTHEAST TOWARDS A MORE
MOIST/UNSTABLE AIRMASS...WHILE DRIER AIR AND LITTLE TO NO
INSTABILITY ARE PRESENT ACROSS THE CWA. DID LEAVE SLIGHT CHANCE
POPS FOR SHOWERS ACROSS THE FAR SOUTHERN CWA FOR SOME VARIABILITY
IN GUIDANCE TRYING TO INCH THIS PRECIP CLOSER TO THE CWA.
HOWEVER...A MORE LIKELY SCENARIO IS FOR THIS DEVELOPMENT TO REMAIN
TO THE SOUTH. THURSDAY AND THURSDAY NIGHT WILL LIKELY BE DRY AS
HIGH PRESSURE DOMINATES THE REGION...BUT THERE STILL IS SOME
VARIABILITY AMONG MODEL GUIDANCE HANDLING OF AN APPROACHING UPPER
LEVEL TROUGH AND ASSOCIATED SURFACE REFLECTION...AND ASSOCIATED
PRECIP ON FRIDAY. ALTHOUGH THE BEST PRECIP AXIS SHOULD REMAIN JUST
SOUTH OF THE CWA...DID LEAVE SLIGHT CHANCE OF SHOWERS FOR THE
SOUTHERN HALF OF THE CWA DUE TO THIS UNCERTAINTY. THE REMAINDER OF
THE WEEKEND IS LOOKING DRY FOR MOST AREAS BUT TOWARDS SUNDAY AND
ESPECIALLY BY EARLY NEXT WEEK...A RETURN TO SOUTHERLY FLOW WILL
ALLOW A WARMER AND MORE MOIST ENVIRONMENT TO SPREAD BACK NORTH
ACROSS THE REGION. ISOLATED TO SCATTERED SHOWER/THUNDERSTORM
DEVELOPMENT IS APPEARING MORE PROBABLE ON SUNDAY...BUT WITH
CONTINUED MOIST ADVECTION AND INCREASING FLOW ALOFT EARLY NEXT
WEEK...MORE WIDESPREAD DEVELOPMENT WILL BECOME MORE LIKELY. TIMING
AND PLACEMENT ISSUES ARE PRESENT DURING THIS TIME....BUT MORE
ORGANIZED DEVELOPMENT DOES APPEAR POSSIBLE IN THE MONDAY TO
TUESDAY TIME FRAME.

RODRIGUEZ

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 19Z...

* MVFR CEILINGS POSSIBLE THIS AFTERNOON.

* SMALL CHANCE FOR LIGHT SHOWERS THIS AFTERNOON.

* LAKE BREEZE DEVELOPMENT THIS AFTERNOON.

* LOW MVFR CEILINGS OVERNIGHT.

MM

//DISCUSSION...UPDATED 19Z...

VISIBLE SATELLITE IMAGERY INDICATES A BROKEN TO OVERCAST STRATUS
DECK APPROACHING FROM THE NORTHWEST BEHIND A PASSING COLD FRONT.
THE REDUCED SUNSHINE DUE TO THESE CLOUDS WILL LOWER THE THREAT OF
SHOWERS DEVELOPING TO ONLY 30 PERCENT...PRECLUDING MENTION IN THE
TAFS. THIS WILL ALSO ACT TO WEAKEN AND DELAY THE LAKE BREEZE
DEVELOPMENT. START TIME OF LAKE BREEZE HAS BEEN ADJUSTED PER
LATEST RADAR TRENDS. REMNANT LOW LEVEL MOISTURE WILL KEEP 1500
FOOT CEILINGS LIKELY LATE TONIGHT. ONCE THE SURFACE HIGH GETS
CLOSER WEDNESDAY MORNING...CLOUD COVER WILL SCATTER OUT.

MM

//ORD AND MDW CONFIDENCE...UPDATED 19Z...

* MEDIUM IN CIGS REMAINING ABOVE MVFR THIS AFTERNOON.

* MEDIUM HIGH THAT SHOWERS WILL NOT DEVELOP.

* MEDIUM IN LAKE BREEZE DEVELOPMENT AND TIMING.

* MEDIUM IN LOW MVFR CIGS OVERNIGHT.

MM

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

WEDNESDAY NIGHT THROUGH SUNDAY...PRIMARILY DRY AND VFR. NE/E WINDS.
MONDAY...CHC TSRA. SW WINDS.

BMD

&&

.MARINE...
259 AM CDT

A WEAK TROUGH WILL PUSH ACROSS LAKE MICHIGAN TODAY WITH NORTHWEST
TO NORTH WINDS OVERSPREADING THE LAKE THROUGH THE DAY. WINDS
FRESHEN UP TO 15 TO 20 KT ACROSS THE LAKE THIS AFTERNOON AND
EVENING AS THE LOW DEEPENS OVER THE EASTERN LAKES REGION AND HIGH
PRESSURE BUILDS SOUTH FROM MANITOBA. MODEST NORTH TO NORTHEAST
WINDS WILL REMAIN IN PLACE THROUGH WEDNESDAY NIGHT...THEN WILL
BEGIN TO DIMINISH FROM THE NORTH. A GRADIENT WILL HOLD ON ACROSS
THE FAR SOUTH END OF LAKE MICHIGAN THURSDAY AS LOW PRESSURE MOVES
ACROSS THE MID MISSISSIPPI VALLEY...BUT EXPECT WINDS TO DIMINISH
ACROSS THE SOUTH END BY THURSDAY NIGHT AS THE RIDGE CONTINUES TO
BUILD SOUTH.

BMD

&&

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

$$

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