Area Forecast Discussion
Issued by NWS Chicago, IL

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000
FXUS63 KLOT 261342
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
842 AM CDT SUN APR 26 2015

.SHORT TERM...
315 AM CDT

THROUGH MONDAY NIGHT...

REALLY QUIET WEATHER ON TAP THROUGH THE REMAINDER OF THE WEEKEND AND
THROUGH MOST OF THE UPCOMING WEEK. LOW PRESSURE HAS MOVED FROM THE
MID MISSISSIPPI VALLEY TOWARDS THIS MID ATLANTIC COAST THIS MORNING
WITH DRY NORTHEASTERLY FLOW IN PLACE ACROSS NORTHERN ILLINOIS AND
NORTHWEST INDIANA IN ADVANCE OF HIGH PRESSURE BUILDING DOWN FROM THE
CANADIAN PRAIRIES. ONSHORE FLOW AND A MODEST NORTHEAST WIND WILL BE
IN PLACE TODAY KEEPING CONDITIONS COOL ALONG THE LAKE FRONT...WHERE
LOW 50S ARE IN THE FORECAST FOR HIGHS...BUT FARTHER INLAND EXPECT
MID TO UPPER 50S THIS AFTERNOON UNDER MOSTLY SUNNY SKIES.
TEMPERATURES WILL BE A FEW DEGREES WARMER MONDAY...THOUGH SIMILAR
ALONG THE LAKE FRONT. VERY DRY COLUMN OF AIR ADVECTING OVERHEAD WILL
MIX DOWN TO THE SURFACE THIS AFTERNOON WITH DEWPOINTS FALLING INTO
THE MID TO UPPER 20S RESULTING IN RELATIVE HUMIDITY DROPPING INTO
THE 25 TO 35 PERCENT RANGE. THE DRY AIRMASS WILL HELP LEAD TO BIG
DIURNAL CURVES AROUND 30 DEGREES FOR SOME LOCATIONS. LEANED HEAVILY
ON BIAS CORRECTED GUIDANCE TO RESOLVE THE TYPICAL COLD SPOTS AS WE
SHOULD BE UNDER FAVORABLE RADIATIVE COOLING CONDITIONS NEXT COUPLE
NIGHTS...BUT ESPECIALLY MONDAY NIGHT WHEN WINDS BECOME CALM. ADDED
PATCHY FROST TONIGHT AND MONDAY NIGHT OUTSIDE THE CHICAGO METRO.
WINDS REMAIN A LITTLE MORE ELEVATED SO CONFIDENCE IS LOWER FOR
TONIGHT AS COMPARED TO MONDAY NIGHT...SO WILL HOLD OFF ON AN
ADVISORY FOR NOW BUT ONE MAY BE NEEDED.

BMD

&&

.LONG TERM...
315 AM CDT

TUESDAY THROUGH SATURDAY...

OVERALL VERY WEAK SURFACE FIELD WILL BE IN PLACE TUESDAY INTO
WEDNESDAY AS MODEST HIGH PRESSURE SPANS MUCH OF THE MID-SECTION OF
THE COUNTRY. BARELY 8MB PRESSURE DIFFERENCES BETWEEN BOTH EAST AND
WEST COASTS AND THE PLAINS WILL RESULT IN FAIRLY LIGHT WINDS
ACROSS THE MIDWEST WITH LAKE BREEZES EXPECTED EACH DAY. MODERATING
AIRMASS WILL RESULT IN A WARMING TREND TUESDAY INTO
WEDNESDAY...BUT A SHORTWAVE TROUGH DIGGING INTO THE MIDWEST WILL
BRING A GLANCING BLOW OF COLDER AIR INTO THE REGION THURSDAY.
UPPER RIDGING WILL TRY TO BUILD OVER THE AREA BY LATE IN THE WEEK
INTO THE WEEKEND AND MAY BRING TEMPS WELL INTO THE 70S.

BMD

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 14Z...

* NORTHEAST WINDS AT/ABOVE 10 KT WITH GUSTS OF 15 TO 20 KT
  THROUGH THIS AFTERNOON.

RODRIGUEZ/KJB

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

THE REGION WILL REMAIN WITHIN SOUTHERN PERIPHERY OF A SURFACE HIGH
PRESSURE RIDGE OVER UPPER MIDWEST THROUGH THE FORECAST PERIOD.
THIS WILL MAINTAIN NORTHEAST WINDS OF 10-15 KTS WITH GUSTS
POTENTIALLY NEAR 20 KT GUSTS THIS AFTERNOON. THE SURFACE PRESSURE
GRADIENT WILL WEAKEN A BIT TONIGHT ALLOWING WINDS TO DIMINISH
BELOW 10 KTS. HOWEVER...NORTH-NORTHEASTERLY WINDS COULD AGAIN
CLIMB INTO THE 10 TO 15 KT RANGE ON MONDAY. OTHERWISE EXPECT VFR
CONDITIONS...WITH MAINLY CLEAR SKIES DURING DAY.

KJB

//ORD AND MDW CONFIDENCE...UPDATED 14Z...

* HIGH FOR ALL ELEMENTS.

RODRIGUEZ/KJB

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

MONDAY NIGHT THROUGH THURSDAY...PRIMARILY VFR. NORTH-NORTHEAST
WINDS.

FRIDAY...VFR. CHANCE OF SHOWERS FRIDAY NIGHT SOUTHWEST WINDS.

SATURDAY...VFR. SOUTHWEST WINDS.

KJB

&&

.MARINE...
126 AM CDT

THE COMBINATION OF A SURFACE RIDGE OF HIGH PRESSURE OVER ONTARIO AND
THE UPPER MIDWEST AND LOWER PRESSURE OVER THE EASTERN LAKES
REGION...WILL CONTINUE TO RESULT IN A MODERATE NORTHERLY WIND UP
AROUND 25 KT TODAY THROUGH MONDAY. THIS WILL PARTICULARLY BE THE
CASE OVER THE SOUTHERN HALF OF THE LAKE. THE SURFACE GRADIENT WILL
WEAKEN CONSIDERABLE LATER MONDAY AND TUESDAY AS THE SURFACE RIDGE OF
HIGH PRESSURE SETS UP OVER THE LAKES REGION. THIS SHOULD RESULT IN A
WEAK WIND REGIME THROUGH AT LEAST MIDWEEK OVER THE LAKE.
THEREFORE...WIND SPEEDS AND DIRECTIONS WILL LIKELY BE LARGELY DRIVEN
BY LAKE AND LAND BREEZE INFLUENCES.

KJB

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 10 AM MONDAY.

&&

$$

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