Area Forecast Discussion
Issued by NWS Chicago, IL

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000
FXUS63 KLOT 031146
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
646 AM CDT THU SEP 3 2015

.SHORT TERM...
310 AM CDT

THROUGH FRIDAY...

PRIMARY CONCERN IN SHORT TERM IS CONVECTIVE CHANCES TODAY AND
SECONDARILY TEMPS. MCV OVER NORTHERN LAKE MICHIGAN WILL CONTINUE TO
PUSH VERY SLOWLY EAST INTO NORTHERN LOWER MICHIGAN TODAY. TRAILING
WEST-EAST LINE OF STORMS ACROSS EAST CENTRAL WISCONSIN HAS BEEN
SAGGING VERY SLOWLY SOUTHWARD AND AT ITS CURRENT PACE LOOKS TO MAKE
IT INTO THE HEART OF OUR CWA BY EARLY AFTERNOON. GIVEN RELATIVELY
WEAK CAPPING AND UNSEASONABLY WARM/HUMID AIR MASS QUITE PLAUSIBLE
THAT ISOLD TO POSSIBLY SCTD THUNDERSTORMS COULD DEVELOP ALONG THIS
BOUNDARY THIS AFTERNOON OR PERHAPS ALONG LAKE BREEZE LATE THIS
AFTERNOON AND EVENING. CONVECTIVE ALLOWING MODELS HAVE BEEN HAVING
ABSOLUTE FITS HANDLING THIS WEAKLY FORCED CONVECTION THE PAST COUPLE
DAYS WHICH LENDS ITSELF TO LOWER THAN AVERAGE CONFIDENCE IN HOW
THINGS EVOLVE TODAY. WITH SHORTWAVE MOVING EAST TONIGHT AND SOME
NOCTURNAL STABILIZATION WOULD ANTICIPATE ANY CONVECTION THAT DOES
DEVELOP TO DISSIPATE THIS EVENING.

ASSUMING CONVECTION AND CLOUD COVER ARE NOT OVERLY EXTENSIVE THROUGH
MID-AFTERNOON...WHICH WOULD APPEAR TO BE A GOOD ASSUMPTION AT THIS
POINT...THEN HIGHS TODAY WOULD LIKELY BE IN THE BALL PARK OF WHERE
THEY WERE YESTERDAY AROUND 90 DEGREES. IF CONVECTIVE OUTFLOW
ENHANCES A LAKE BREEZE THEN IT COULD TURN COOLER NEAR THE LAKE THIS
AFTERNOON...BUT THIS DOESNT APPEAR TO BE MOST LIKELY SCENARIO AT
THIS TIME SO DIDNT REFLECT THAT IN WIND/TEMP GRIDS.

WEAKNESS BETWEEN MAIN UPPER RIDGE AND WEAK RIDGE OVER QUEBEC SHOULD
RESULT IN WEAK CAPPING AT BEST FRIDAY AND A CONTINUED SLIGHT CHANCE
OF AT LEAST ISOLATED STORMS IN THE AFTERNOON AND EVENING. LAKE
BREEZE LOOKS MORE LIKELY TO KEEP LAKESHORE AREAS COOLER FRIDAY BUT
INLAND TEMPS SHOULD AGAIN WARM INTO THE UPPER 80S TO NEAR 90.

IZZI

&&

.LONG TERM...
310 AM CDT

FRIDAY NIGHT THROUGH WEDNESDAY...

UPPER RIDGE LOOKS TO FLEX A BIT MORE NORTHEAST INTO THE REGION OVER
THE WEEKEND AND WHILE ISOLATED STORMS CANNOT TOTALLY BE RULED
OUT...CHANCES LOOK SLIME WITH SATURDAY AND SUNDAY GENERALLY LOOKING
MAINLY RAIN FREE AT THIS POINT. TEMPERATURES LOOKS TO REMAIN VERY
WARM TO BORDERLINE HOT AND CONTINUED HUMID. HIGHS SHOULD EASILY
CLIMB INTO THE UPPER 80S WITH LOW 90S CERTAINLY POSSIBLE. LAKE
BREEZE IS POSSIBLE SATURDAY BUT LOOKS LESS LIKELY AT THIS POINT ON
SUNDAY.

COLD FRONT SHOULD BEGIN TO APPROACH FROM THE NORTHWEST SUNDAY NIGHT
OR MONDAY. IN GENERAL...MEDIUM RANGE GUIDANCE HAS SPED UP THE FRONT
SOME COMPARED TO RUNS 24 HOURS AGO. NOT CONVINCED IT WILL BE THIS
QUICK AND WORRIED THAT BLENDED MODEL HIGHS IN THE MID 80S MONDAY MAY
END UP BEING A BIT TOO COOL...BUT GIVEN RECENT MODEL TRENDS DIDNT
MAKE ANY CHANGES AT THIS POINT. IT DOES APPEAR AS THOUGH WE COULD
GET A BREAK FROM THE LATE RESURGENCE OF SUMMER BY THE MIDDLE OF NEXT
WEEK WITH HIGHS RETURNING INTO THE 70S AGAIN.

IZZI

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 12Z...

* TSRA/SHRA POSSIBLE LATE THIS AFTERNOON AND EVENING.

* WIND SHIFT TO MORE OF AN EASTERLY DIRECTION LATE THIS
  AFTERNOON.

RODRIGUEZ

//DISCUSSION...UPDATED 12Z...

VFR CONDITIONS AND LIGHT SOUTHERLY WINDS IN PLACE THIS
MORNING...WHILE ANY PRECIP ACROSS THE REGION IS CURRENTLY TO THE
NORTH OF ALL THE TERMINALS. THIS WILL LIKELY CONTINUE...WITH ANY
FURTHER DEVELOPMENT THIS MORNING STAYING TO THE NORTH/NORTHEAST.
INCREASING SOUTHWEST WINDS THROUGH MIDDAY/EARLY AFTERNOON WILL
LIKELY OBSERVE A WIND SHIFT TO THE EAST...OWING TO BOUNDARY/LAKE
BREEZE. LOWER CONFIDENCE WITH EXACT TIMING AS WELL AS SPEED BEHIND
THE FRONT. AT THIS TIME...THINK SPEEDS WILL STAY BELOW 10 KT.
HOWEVER...SOME GUIDANCE IS HINTING AT POSSIBLE SUSTAINED SPEEDS
ABOVE 10 KT THROUGH THIS EVENING. THIS BOUNDARY COULD ALSO SERVE
AS A FOCUS FOR PRECIP DEVELOPMENT THIS AFTERNOON INTO THE EVENING.
WITH AT LEAST SCATTERED DEVELOPMENT POSSIBLE...HAVE MAINTAINED A
VCSH IN THE TAFS. WILL NEED TO MONITOR SPEEDS BEHIND WIND SHIFT AS
WELL AS PRECIP CHANCES/COVERAGE LATER THIS AFTERNOON.

RODRIGUEZ


//ORD AND MDW CONFIDENCE...UPDATED 12Z...

* LOW CONFIDENCE WITH TSRA/SHRA CHANCES/COVERAGE THIS
  AFTERNOON/EVENING.

* MEDIUM HIGH CONFIDENCE WITH WIND SPEED/DIRECTION...LOW
  CONFIDENCE ON TIMING OF WIND SHIFT.

RODRIGUEZ

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

FRIDAY NIGHT...VFR.

SATURDAY...SLIGHT CHANCE OF TSRA.

SUNDAY...CHANCE OF TSRA LATE.

MONDAY...CHANCE OF TSRA.

TUESDAY...SLIGHT CHANCE OF TSRA.

WEDNESDAY...CHANCE OF TSRA.

RODRIGUEZ

&&

.MARINE...
428 AM CDT

AS A BOUNDARY REMAINS SITUATED ACROSS THE NORTHERN PORTIONS OF
THE LAKE THIS MORNING...A VARYING WIND FIELD IS OCCURRING ACROSS
THE LAKE. OVER THE NORTH...EAST NORTHEAST WINDS ARE OCCURRING AND
ACROSS THE SOUTH...SOUTHWEST WINDS ARE BEING OBSERVED. THIS WILL
LIKELY PERSIST FOR MOST OF TODAY...BUT WITH THE SOUTHWEST WINDS
ACROSS THE SOUTHERN PART OF LAKE TURNING MORE SOUTHEAST THIS
AFTERNOON. INCREASED WINDS OVER THE NORTH HALF TO 10 TO 20 KT FOR
THIS MORNING BUT HAVE THEM DIMINISHING IN THE AFTERNOON.
HOWEVER...DO THINK ITS POSSIBLE THAT 10 TO 20 KT WINDS COULD STILL
BE POSSIBLE IN THE AFTERNOON. WAVES SHOULD STAY CONFINED TO 1 TO 3
FEET TODAY AND TONIGHT BUT WITH THUNDERSTORMS PUSHING OVER THE
LAKE EARLY THIS MORNING...ASSOCIATED HIGHER WINDS COULD HELP TO
BRIEFLY BUILD THESE WAVES.

RODRIGUEZ

&&

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

$$

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