Area Forecast Discussion
Issued by NWS Chicago, IL

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000
FXUS63 KLOT 182156
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
456 PM CDT FRI APR 18 2014

.DISCUSSION...

250 PM...FORECAST CONCERNS INCLUDE WARMING TEMPS THIS WEEKEND
ALONG WITH LAKE COOLING...CHANCE OF SHOWERS MONDAY...LAKE COOLING
MID WEEK AND A CHANCE OF THUNDERSTORMS AHEAD OF A COLD FRONT
THURSDAY.

NORTHEASTERLY WINDS WILL STRENGTHEN A TAD GOING INTO THIS EVENING
AS HIGH PRESSURE DRIFTS SOUTHEAST ACROSS THE NORTHERN LAKES. WHILE
TEMPS HAVE WARMED INTO THE UPPER 50S/LOWER 60S WELL INLAND...TEMPS
WILL BEGIN TO DROP ACROSS MUCH OF THE METRO AREA AS COOLER AIR
SPREADS IN FROM THE LAKE. OTHERWISE...DRY WEATHER IS EXPECTED THIS
EVENING WITH THIN HIGH CLOUDS.

AS THE FLOW TURNS SOUTHERLY SATURDAY...TEMPERATURES WILL REBOUND
WELL INTO THE 60S WITH LOWER 70S EXPECTED ACROSS PARTS OF CENTRAL
IL UNDER MOSTLY SUNNY SKIES. SOUTHEASTERLY WINDS WILL KEEP THE
ILLINOIS SHORE MUCH COOLER HOWEVER. WINDS TURN A BIT MORE
SOUTHWESTERLY AND STRENGTHEN SOME ON SUNDAY. HIGHS SUNDAY SHOULD
REACH THE LOWER TO MID 70S EVERYWHERE...PERHAPS SOME UPPER 70S
SOUTH. FOR NOW HAVE MAINTAINED WARMER TEMPS ALL THE WAY TO THE
LAKESHORE...BUT COULD BE A WEAK LAKE BREEZE RIGHT ALONG THE SHORE
FROM DOWNTOWN NORTH. ANY ONSHORE FLOW WOULD LEAD TO SIGNIFICANTLY
LOWER TEMPS.

A FRONTAL BOUNDARY WILL MOVE ACROSS THE UPPER MIDWEST AND NORTHERN
LAKES REGION SATURDAY AND THEN VERY SLOWLY MOVE SOUTH SATURDAY
NIGHT AND SUNDAY. PRECIPITATION WITH THIS FRONT WILL REMAIN WELL
NORTH OF THE AREA THROUGH SUNDAY EVENING WHEN WEAK LOW PRESSURE
DEVELOPS OVER IOWA AND THEN SHIFTS EAST ACROSS THE AREA ON MONDAY.
HAVE SCALED BACK POPS THROUGH SUNDAY EVENING...GOING DRY AND MAY
END UP BEING DRY MUCH OF SUNDAY NIGHT UNTIL PRECIP FINALLY ARRIVES
WITH MAIN SURFACE LOW AND WHILE THERE MAY BE SOME PERIODS OF DRY
WEATHER ON MONDAY HAVE BUMPED POPS TO LOW END LIKELY. END TIME
MONDAY EVENING/MONDAY NIGHT STILL A BIT UNCERTAIN BUT MUCH OF
MONDAY NIGHT...ESPECIALLY ACROSS THE WESTERN CWA MAY END UP BEING
DRY.

AS A RIDGE OF HIGH PRESSURE PASSES TUESDAY INTO WEDNESDAY...TEMPS
WILL DROP BACK TO SEASONAL LEVELS FOR MID APRIL BUT WITH EASTERLY
FLOW...MUCH COOLER TEMPS CAN BE EXPECTED ALONG THE LAKE.

STRONGER LOW PRESSURE WILL MOVE ACROSS THE NORTHERN PLAINS
THURSDAY AND THEN ACROSS THE LAKES REGION TOWARD THE END OF THE
WEEK. HELD ONTO CHANCE POPS FROM WEDNESDAY NIGHT THROUGH FRIDAY.
HOWEVER...THERE WILL BE MANY DRY HOURS DURING THIS PERIOD AND
EXPECT THE BEST CHANCE OF SHOWERS AND THUNDERSTORMS TO BE
ALONG/AHEAD OF A COLD FRONT FROM THURSDAY AFTERNOON INTO THURSDAY
NIGHT. ADDITIONAL TIMING CAN BE ADDED AS THIS TIME PERIOD
APPROACHES BUT DID LOWER POPS ON FRIDAY AS EVEN COOLER WRAP AROUND
SHOWERS MAY ONLY BRUSH NORTHERN IL. TEMPS THEN TURN MUCH COLDER
GOING INTO NEXT WEEKEND. CMS

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 22Z...

* NONE

IZZI

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

SFC HIGH PRESSURE CENTERED TO THE NORTH OF THE REGION IS ALLOWING
NEAR CLOUDLESS SKIES THIS AFTERNOON WITH VFR CONDS AT AREA
AIRFIELDS. WINDS HAVE TURNED NORTHEASTERLY TO BETWEEN 040-070 DEG
THIS AFTN...AND SPEEDS HAVE NUDGED UP SLIGHTLY TO ARND 11-14KT.
EXPECT THE SPEEDS TO REMAIN THRU EARLY THIS EVE...THEN DIMINISH
AFT 03Z TO ARND 08KT. THEN WINDS TURN MORE EASTERLY TO 080-100
DEG. HIGH PRESSURE WILL THEN SLIDE EAST...WITH WINDS BEGINNING TO
TURN SOUTHEASTERLY. IT DOES APPEAR THAT WIND DIRECTIONS MAY HOLD
LINGER AT 110-130 THRU MUCH OF SAT MORNING...THEN BY LATE SAT AFTN
CLOUDS BEGIN TO THICKEN AND WINDS BEGIN TO TURN TO A 130-150 DEG
DIRECTION.

BEACHLER

//ORD AND MDW CONFIDENCE...UPDATED 22Z...

* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS.

BEACHLER/IZZI

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

SATURDAY NIGHT...VFR.
SUNDAY...CHANCE OF RAIN DURING THE NIGHT.
MONDAY...CHANCE OF RAIN.
TUESDAY...EAST FLOW.
WEDNESDAY...EAST FLOW. CHANCE OF RAIN.
THURSDAY...CHANCE OF T-STORMS.

MTF

&&

.MARINE...
144 PM CDT

SURFACE HIGH PRESSURE IS CURRENTLY BUILDING ACROSS ONTARIO AND THE
UPPER GREAT LAKES. THIS IS RESULTING IN MAINLY LIGHT NORTHERLY FLOW
ACROSS THE LAKE. HOWEVER...SOME ENHANCED NORTHERLY WINDS...AROUND
20KT...ARE ONGOING ACROSS THE FAR SOUTHERN SECTIONS OF THE LAKE.
THESE WINDS LOOK TO CONTINUE INTO THIS EVENING BEFORE ABATING AND
GRADUALLY SHIFTING EASTERLY. THIS NORTH-NORTHEASTERLY FETCH WILL
WILL LIKELY CONTINUE TO RESULT IN ELEVATED WAVE HEIGHTS UP AROUND
THE 4 FOOT MARK ACROSS SOUTHERN LAKE MICHIGAN...INCLUDING THE NEAR
SHORE WATERS INTO THIS EVENING. THIS IS RIGHT ON THE BOARDER LINE OF
SMALL CRAFT ADVISORY CONDITIONS. HOWEVER...IN SPITE OF THIS...I HAVE
OPTED TO CONTINUE WITHOUT A HEADLINE AND MENTION 3-5 FOOTERS INTO
THIS EVENING FOR THE NEAR SHORE FORECAST.

THE SURFACE FLOW WILL COME AROUND OUT OF THE SOUTH-SOUTHEAST DURING
THE DAY SATURDAY...THEN INCREASE UP AROUND 25 KT SATURDAY EVENING IN
RESPONSE TO AN AREA OF LOW TRACKING EASTWARD ACROSS SOUTHERN CANADA.
IT APPEARS THE STRONGEST FLOW WILL REMAIN OUT OVER THE OPEN WATERS
OF THE LAKE. A FRONTAL BOUNDARY IS EXPECTED TO SLOWLY SHIFT
SOUTHWARD DOWN THE LAKE EARLY NEXT WEEK...AS ANOTHER AREA OF LOW
PRESSURE IS EXPECTED TO DEVELOP EASTWARD ALONG THE BOUNDARY. THIS
WILL SET UP NORTHERLY FLOW AGAIN LAKE-WIDE BY TUESDAY.

KJB

&&

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

$$

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