Area Forecast Discussion
Issued by NWS Chicago, IL

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348
FXUS63 KLOT 051151
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
551 AM CST FRI FEB 5 2016

.SHORT TERM...
259 AM CST

THROUGH SATURDAY NIGHT...

A FEW FLURRIES EAST OF I-39 WILL CONTINUE EAST EARLY THIS MORNING
WITH LITTLE TO NO ACCUMULATION EXPECTED. THE CLOUD COVER IS LEADING
TO WARMER THAN EXPECTED TEMPS AT MOST LOCATIONS.  THE UPPER LEVEL
TROUGH IS OVER THE CENTRAL OHIO VALLEY WITH A RIDGE OVER THE PLAINS.
THE RIDGE AND ASSOCIATED SURFACE HIGH MOVE OVER THE REGION TODAY
RESULTING IN TEMPS AT OR WARMER THAN WHAT THEY WERE THURSDAY.
THINKING IT WILL REMAIN CLOUDY TODAY. STRATUS IS SPREADING OVER THE
REGION AND THE UPPER LEVEL THERMAL TROUGH ASSOCIATED WITH THE
STRATUS REMAINS OVERHEAD. FORECAST SOUNDINGS ALSO SUGGEST THAT THE
COLUMN WILL REMAIN MOIST ENOUGH FOR CLOUD COVER.

A SHORTWAVE TROUGH AND VORT STREAMER MOVE THROUGH THE REGION LATE
TONIGHT INTO SATURDAY MORNING. THINKING THE LIFT ASSOCIATED WITH THE
VORT STREAMER WILL BE ENOUGH TO PRODUCE FLURRIES LATE TONIGHT
THROUGH SATURDAY MORNING. NO ACCUMULATION IS EXPECTED ESPECIALLY
SINCE CONFIDENCE IS LOW IN THE COVERAGE AND PERSISTENCE OF THE
FLURRIES. THE STREAMER WILL ALSO BE SCOOTING THROUGH...WHICH SHOULD
TRANSLATE TO TRANSIENT FLURRIES TOO.

SOUTH WINDS AND WARM AIR ADVECTION KICK IN SATURDAY RESULTING IN
HIGHS FROM THE MID 30S ALONG THE IL/WI STATE LINE TO LOW TO MID 40S
SOUTH OF I-80. SATURDAY AFTERNOON SHOULD BE DRY BUT CLOUDY.
OVERNIGHT LOWS WILL BE IN THE UPPER 20S.

JEE

&&

.LONG TERM...
259 AM CST

SUNDAY THROUGH THURSDAY...

THE NEXT SYSTEM MOVES OVER THE REGION MONDAY AND THE SURFACE LOW
SHOULD BE VERTICALLY ALIGNED WITH THE UPPER LEVEL LOW.  THE TRICKY
PART WILL BE IF THERE WILL BE PRECIP SUNDAY AS THE UPPER LEVEL LOW/S
VORTICITY STREAMERS ROTATE THROUGH. DECIDED TO INCLUDE LOW END
SLIGHT CHANCE TO CHANCE POPS FOR LIGHT PRECIP THROUGH THE DAY.  THE
BETTER CHANCES WILL BE ALONG THE IL/WI STATE LINE CLOSER TO THE
PARENT LOW AND FORCING. TEMPS WILL BE INCREASING TO ABOVE FREEZING
SUNDAY SO HAVE PRECIP BEGINNING AS SNOW BECOMING RAIN BY MID DAY.
THERE IS A DECENT CHANCE THAT SUNDAY MAY BE DRY...SO HAVE HIGH
CONFIDENCE IN TEMPS SUNDAY BUT LOW CONFIDENCE IN PRECIP CHANCES.

THE LOW MOVES OVER THE REGION SUNDAY NIGHT AND GUIDANCE FEATURES
SOME DIFFERENCES IN THE LOWS PATH.  EITHER WAY HAVE HIGHER
CONFIDENCE IN PRECIP SUNDAY NIGHT THROUGH MONDAY.  COLDER AIR MOVES
IN THE WITH THE LOW RESULTING IN LOWS BELOW FREEZING SUNDAY NIGHT.
AS SUCH HAVE RAIN BECOMING SNOW.  INITIAL SNOWFALL TOTALS THROUGH
SUNDAY NIGHT ARE ALL LESS THAN A HALF OF AN INCH AS FORCING LOOKS
MEAGER.

LIGHT SNOW CONTINUES THROUGH TUESDAY NIGHT ESPECIALLY OVER NORTHWEST
INDIANA WHERE LAKE EFFECT SNOW MAY PERSIST INTO WEDNESDAY. THE LOW
AND ITS TROUGH PUSH EAST TUESDAY AFTERNOON...BUT A SECOND
TROUGH/VORT STREAMER PUSHES SOUTH FROM CANADA INTO THE MIDWEST
TUESDAY NIGHT INTO WEDNESDAY. THE BIGGER STORY WITH THE SECOND
STREAMER WILL BE A PUNCH OF COLD AIR...-10 TO -20C AT 850
MB...MOVING OVER THE REGION. IT LOOKS LIKE WE WILL MISS THE COLDEST
AIR ASSOCIATED WITH THE STREAMER...BUT WIND CHILLS TUESDAY
NIGHT/WEDNESDAY MORNING WILL BE AROUND 0 OR SLIGHTLY BELOW ZERO.

HIGH PRESSURE MOVES OVER THE REGION MID TO LATE NEXT WEEK WITH LAKE
EFFECT SNOW FOCUSING EAST OF THE WARNING AREA. TEMPS WILL BE IN THE
20S WEDNESDAY AND THEN AROUND 30 THURSDAY.

JEE

&&

.AVIATION...
FOR THE 12Z TAFS...

CONCERNS FOR ORD AND MDW ARE 1000-1500 FT CIGS THIS MORNING AND
POSSIBLY INTO THE AFTERNOON...AS WELL AS THE CHANCE FOR BRIEF
FLURRIES/LIGHT SNOW LATE TONIGHT INTO EARLY SATURDAY MORNING.

PRE-DAWN SNOW SHOWERS ASSOCIATED WITH A WEAK CLIPPER SYSTEM HAVE
DEPARTED TO THE NORTHEAST...HOWEVER THIS DISTURBANCE DRAGGED IN
MVFR CIGS. THESE SHOULD LOWER QUICKLY THROUGH SUNRISE TO NEAR
1000 FT AND CONFIDENCE IS MODERATE-HIGH IN THIS. BRIEF IFR CIGS
ARE POSSIBLE AND HAVE BEEN BRIEFLY REPORTED IN THE FAR WEST
CHICAGO METRO. THE BACK EDGE OF THE CLOUDS IN WISCONSIN HAS BEEN
MOVING AT A FAIRLY STEADY PACE...ALTHOUGH SOME SLOWING OF THIS
BACK EDGE MAY OCCUR OVER NORTHEAST ILLINOIS LATE THIS MORNING.
CONFIDENCE REMAINS QUITE LOW ON THE MVFR CLOUD DEPARTURE TIME.

WINDS WILL TURN NORTHWEST EARLY THIS MORNING AND LIKELY REMAIN
BELOW 10 KT. AS A RIDGE PASSES OVER THIS EVENING THEY WILL BECOME
LIGHT AND BACK TO THE SOUTH. A WEAKER CLIPPER THAN THE ONE EARLY
THIS MORNING WILL PASS OVER LATE TONIGHT AND EARLY SATURDAY
MORNING...POSSIBLY BRINGING ENOUGH SATURATION FOR LIGHT SNOW
GRAINS. CONFIDENCE IN THIS IS LOW.

MTF

&&

.MARINE...
143 AM CST

A MORE COMMON MID-WINTER SETUP FOR THE GREAT LAKES WILL ESTABLISH
ITSELF INTO NEXT WEEK...WITH SYSTEMS FROM THE NORTHWEST AND
ASSOCIATED SURFACE COLD FRONTS MOVING ACROSS THE GENERAL REGION.
ONE SUCH WEAKER COLD FRONT IS PASSING ACROSS THE LAKE VERY EARLY
THIS MORNING TURNING WINDS NORTHWEST. THE NEXT LOW PRESSURE WILL
PASS QUICKLY NORTH OF THE GREAT LAKES VERY LATE TONIGHT INTO
SATURDAY MORNING. THIS WILL PROVIDE A TIGHTENING PRESSURE GRADIENT
OVER THE NORTHERN PART OF THE LAKE WITH LIKELY 30 KT GUSTS.

A STRONGER NORTHWEST FLOW SYSTEM WILL DROP DOWN OVER THE WESTERN
GREAT LAKES BY SUNDAY NIGHT AND INTO LOWER MICHIGAN BY MIDDAY
MONDAY. THIS LOW LOOKS TO LIKELY SLOW AS IT DOES. WINDS AHEAD OF
THIS COULD GET INTO THE 25 TO 30 KT CATEGORY OVER THE OPEN WATER
AND NEAR SMALL CRAFT CRITERIA IN THE NEARSHORE. ON THE BACKSIDE OF
THE SYSTEM...COLD ADVECTION WILL VERY LIKELY PROVIDE AT LEAST 30
KT AND POTENTIALLY GALE FORCE GUSTS FOR THE OPEN WATER WITH SMALL
CRAFT CRITERIA IN THE NEARSHORE. THIS RIGHT NOW IS MOST FAVORED
MONDAY NIGHT AND/OR TUESDAY.

MTF

&&

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

$$

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