Area Forecast Discussion
Issued by NWS Chicago, IL

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FXUS63 KLOT 311938
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
138 PM CST SAT JAN 31 2015

.UPDATE...

CURRENTLY GOING OVER THE LATEST FORECAST GUIDANCE. A FIRST LOOK
AT THE 12 UTC GFS INCREASES MY CONCERNS FOR HEAVY SNOW ACROSS MUCH
OF MY AREA TONIGHT INTO SUNDAY. HOWEVER...PRECIP TYPE ISSUES
MENTIONED IN THE PREVIOUS DISCUSSION COULD COMPLICATED THINGS
ACROSS MY FAR SOUTHERN COUNTIES...AS THE LATEST GUIDANCE SUGGESTS
THE 850 MB LOW MAY TRACK RIGHT ACROSS EAST CENTRAL ILLINOIS SUNDAY
AFTERNOON. AS A RESULT...THIS COULD IMPACT SNOW AMOUNTS ACROSS MY
FAR SOUTH.

I AM ALSO BECOMING MORE CONCERNED FOR THE POTENTIAL OF
BLIZZARD CONDITIONS SUNDAY AND SUNDAY EVENING...ESPECIALLY GIVEN
THE TREND FOR A STRONGER SYSTEM. THE 12 UTC RUN OF THE GFS
SUGGESTS WIND ADVISORY LEVEL WINDS...WITH GUSTS POTENTIALLY UP
AROUND 40 KT. IF THESE TYPE OF WINDS MATERIALIZE...WHITE OUT
CONDITIONS COULD CERTAINLY BECOME AN ISSUE. IN ANY
EVENT...CONFIDENCE IS INCREASING THAT MOST OF MY AREA WILL
EXPERIENCE A MAJOR WINTER STORM...WITH UP TO A FOOT OF SNOW
POSSIBLE.

KJB

&&

.SHORT TERM...
348 AM CST

THROUGH SUNDAY NIGHT...

SIGNIFICANT WINTER STORM STILL POISED TO AFFECT THE AREA STARTING
TONIGHT AND CONTINUING THROUGH SUNDAY EVENING.

HEADLINES...
HAVE GONE AHEAD AND UPGRADED THE ENTIRE CWA TO A WINTER STORM
WARNING FOR LATE THIS EVENING THROUGH SUNDAY EVENING. FOR SIMPLICITY
SAKE...HAVE GONE WITH SAME START AND END TIME ACROSS THE CWA...AN
ARGUMENT COULD HAVE BEEN MADE TO START LATER IN SOUTHERN CWA AND
AREAS NEAR THE LAKE COULD NEED TO BE EXTENDED A BIT IF LAKE EFFECT
IS MORE IMPRESSIVE THAN EXPECTED...BUT GENERALLY THINK THAT 03Z THIS
EVENING THROUGH 03Z SUNDAY EVENING WILL COVER THE MEAT AND POTATOES
OF THE EVENT MOST AREAS.

SYNOPTICS/MODELS ANALYSIS...
STILL LOOKING A FAIRLY COMPLEX EVOLUTION OF PATTERN THE NEXT COUPLE
OF DAYS AS VIGOROUS SHORTWAVE OVER ALBERTA IS FORECAST TO DIG
SOUTHEAST INTO THE NORTHERN AND CENTRAL ROCKIES AS STRONG CLOSED LOW
OVER THE SOUTHWEST DROPS SOUTH AND BECOMES INCREASINGLY CUT OFF FROM
BELT OF WESTERLIES. FARTHER NORTH A STRONG SHORTWAVE PIVOTING AROUND
HUDSON LOW WILL HELP DRIVE A COLD FRONT SOUTH INTO NORTHERN ILLINOIS
THIS EVENING WITH THE FRONT STALLING OUT. AS STRONG ALBERTA CLIPPER
DROPS SOUTH INTO THE ROCKIES LOOK FOR CYCLOGENESIS TO OCCUR OVER
COLORADO TODAY...THEN TRACK EAST TOWARD THE OHIO VALLEY AND
STRENGTHEN TONIGHT AND SUNDAY AS 500MB SHORTWAVE IS FORECAST TO
AMPLIFY AS IT TRACKS EAST.

THE SPREAD IN THE MODELS BETWEEN THE NAM/GFS/ECMWF HAS DECREASED
THROUGH SUNDAY NIGHT...WHICH DOES LEND TO SOME UPTICK IN CONFIDENCE.
HOWEVER...IT IS STILL A COMPLEX INTERACTION OF SEVERAL KEY FEATURES
FORECAST TO TAKE PLACE AND NUMERICAL WEATHER GUIDANCE HAS HUNG US
OUT TO DRY REPEATEDLY THIS WINTER...MAKING IT HARD TO GO RUNNING
BACK INTO ITS OPEN ARMS AND TRUSTING IT. STILL...GIVEN THE
DECREASING SPREAD IN THE MODELS THROUGH SUNDAY NIGHT IT IS A BIT
EASIER TO DEVELOP SOME MORE CONFIDENCE IN THE FORECAST EVOLUTION OF
THIS SYSTEM.

NITTY GRITTY DETAILS...
BROAD AND STRENGTHENING WARM AIR ADVECTION REGIME IS LIKELY TO
RESULT IN AN EXPANDING SHIELD OF PRECIPITATION FROM THE LOWER
MISSOURI VALLEY THIS MORNING EASTWARD INTO OUR AREA LATE THIS
AFTERNOON AND EARLY THIS EVENING. INITIALLY IT WOULD APPEAR AS
THOUGH TEMPERATURES TODAY WILL BE WARM ENOUGH FOR PRECIPITATION TO
BE ALL RAIN. WEAK FRONT IS FORECAST TO BASICALLY BISECT THE CWA AT
00Z THIS EVENING AND ONLY SLOWLY SAG SOUTH THROUGH THE NIGHT. TO THE
SOUTH OF THE WEAK FRONT LOOK FOR SOUTHERLY WINDS AND CONTINUED WARM
AIR ADVECTION TO HOLD TEMPERATURES NEAR OR PERHAPS JUST ABOVE
FREEZING SOUTH OF I-80 EARLY THIS EVENING AND PERHAPS INTO THE LATE
EVENING SOUTH OF THE ILLINOIS AND KANKAKEE RIVERS. AM CONCERNED
BECAUSE A VERY COMMON BIAS IN MODEL GUIDANCE IS TO UNDERESTIMATE THE
IMPACTS OF WARM AIR ADVECTION ON P-TYPE IN DEVELOPING CYCLONES LIKE
THIS...WHICH IF ALL THE MASS FIELDS VERIFY PERFECTLY HAS ME
CONCERNED THAT PRECIP COULD BE RAIN OR HAVE RAIN MIXED IN WELL INTO
THE EVENING HOURS INTO SOUTHERN AND POSSIBLY EVEN CENTRAL PORTIONS
OF THE CWA. GIVEN THIS CONCERN HAVE GREATLY REDUCED SNOW ACCUMS THIS
EVENING...ESPECIALLY SOUTH OF I-80 AND EVEN LOWERED RATIOS INTO
SUNDAY MORNING WHERE FORECAST MODEL 2M TEMPS NEAR 32F MAKE ME VERY
LEARY OF SEEING BIG ACCUMULATIONS OCCUR. THE AREAS SOUTH OF
KANKAKEE/ILLINOIS RIVERS SEEM TO STAND THE HIGHEST CHANCE OF A
FORECAST BUST AND IF THE ACCUMULATING SNOW STARTS LATE ENOUGH COULD
EASILY END UP BELOW 5 INCHES FOR THE 24 HOURS PERIOD.

CONFIDENCE IS LOW WHEN PRECIP WILL TURN TO ALL SNOW FAR SOUTH THOUGH
SREF GUIDANCE SUGGESTS BY 06Z...WORRIED THIS COULD BE DELAYED IF THE
TYPICAL MODEL BIAS OF UNDERESTIMATING WAA MAGNITUDE PLAYS OUT.
EVENTUALLY IT WILL TURN TO ALL SNOW AND SHOULD BEGIN TO ACCUMULATE
IF NOT LATE TONIGHT THEN CERTAINLY DURING THE DAY ON SUNDAY AS TEMPS
BEGIN TO PLUMMET. PRECIP LOOKS MORE LIKELY TO BE ALL SNOW NORTH OF
I-88/290...THOUGH THERMAL FIELDS AND FORECAST OMEGA VALUES DO NOT
SUPPORT HIGH SNOW:LIQUID RATIOS FOR THE MAJORITY OF THE EVENT. BY
SUNDAY AFTERNOON AS WE TRANSITION INTO THE DEFORMATION ZONE AND
COLUMN COOLS WILL LIKELY SEE A GRADUAL TRANSITION TO DRIER/HIGHER
RATIO SNOWS.

MODEL QPF REMAINS VERY IMPRESSIVE WITH MAJORITY OF MODELS LAYING OUT
A SWATH OF LIQUID EQUIVS OF 1" OR GREATER OVER PORTIONS OF OUR CWA.
SYSTEM WILL BEGIN TO TAP INTO THE HIGHER PWAT AIR MASS OVER THE GULF
OF MEXICO AND GFS/NAM AGREE THAT PWATS WILL CLIMB TO OVER 0.5" INTO
OUR CWA WHICH IS IN THE 90TH PERCENTILE OF PWATS FOR THIS TIME OF
YEAR. MODELS REALLY NEVER SHOW ANY INTENSE/STRONG ASCENT...BUT
RATHER A LONG DURATION OF MODEST ASCENT WHICH GIVEN THE ACCOMPANYING
UNSEASONABLY MOIST AIR MASS COULD CERTAINLY SUPPORT FORECAST QPF
VALUES. THE MILLION DOLLAR QUESTION IS HOW MUCH OF THE PRECIP WILL
FALL AS ALL SNOW AND HOW LONG WILL IT TAKE IT TO START ACCUMULATING.
THE FARTHER NORTH YOU GO INTO THE CWA THE LESSER THE CHANCE AND
SHORTER THE DURATION OF ANY MIXED SLEET OR RAIN AND THE SOONER SNOW
WILL ACCUMULATE. THIS AREA IS WHERE THE SLIGHTLY LESSER QPF VALUES
ARE...WHILE FARTHER SOUTH WITHIN THE SWATH OF FORECAST QPF >1 INCH
THERE ARE BIG QUESTIONS ABOUT DURATION OF ANY MIXED RAIN AND HOW
SOON AFTER THE TRANSITION TO SNOW THAT IT WILL START TO ACCUMULATE.
IF PRECIP STARTS AS RAIN AND TURNS TO SNOW WITH TEMPS OF 32F OR 33F
THEN IT COULD SNOW FOR A WHILE BEFORE ACCUMULATING...AND FOR THIS
REASON HAS SHOWN AT LEAST A THIRD OF AN INCH OF THE QPF FALLING AS
RAIN OR NON-ACCUMULATING SNOW.

GIVEN THE CURRENT FORECAST TRACK THE AXIS OF HEAVIEST SNOW LOOKS TO
LAY OUT SOMEWHERE IN THE I-80 OR I-88/290 CORRIDOR WHERE ACCUMS
COULD POTENTIALLY PUSH DOUBLE DIGITS BY THE TIME IT IS ALL SAID AND
DONE SUNDAY EVENING. EVEN OUTSIDE THIS SWATH SIGNIFICANT
ACCUMULATIONS OF 5-8 INCHES LOOK PRETTY LIKELY. STRENGTHENING
NORTHEAST WINDS AND COMBINED WITH GRADUALLY DECREASING SNOW DENSITY
SHOULD ALLOW FOR SOME BLOWING AND DRIFTING SNOW TO DEVELOP SUNDAY
AFTERNOON AND CONTINUED INTO SUNDAY EVENING...ESPECIALLY NORTHERN
CWA WHERE SNOW SHOULD BE LIGHTEST AND MOST BLOWABLE.

LAKE ENHANCEMENT/LAKE EFFECT...
AS DEPTH OF THE COLD AIR MASS BEGINS TO INCREASE SUNDAY AFTERNOON
AND EVENING LOOK FOR THE POTENTIAL FOR INITIALLY SOME LAKE
ENHANCEMENT PROBABLY TRANSITIONING TO PURE LAKE EFFECT SUNDAY NIGHT
AS SYSTEM SNOWS MOVE OUT. OVERALL THE LAKE EFFECT SET-UP APPEARS
MARGINAL AND DESPITE THE STRONG CONVERGENCE/LOW LEVEL ASCENT
INDICATED IN THE HIGH-RES MODELS SUSPECT THE LAKE CONTRIBUTIONS TO
THE SNOWFALL WILL NOT BE TERRIBLY SIGNIFICANT. INVERSION HEIGHTS
NEAR OR BELOW 5000FT SUGGEST CONVECTION WILL BE SHALLOW AND DESPITE
FAVORABLE TEMPS BELOW THE INVERSION FOR SNOW GROWTH...THE DEPTH OF
THE CONVECTION LOOKS TOO SHALLOW TO SUPPORT MUCH MORE THAN LIGHT
LAKE EFFECT SNOW SHOWERS. THE LOW LEVEL INSTABILITY IS ALSO PROGGED
TO BE WEAK WITH ONLY A COUPLE HUNDRED JOULES OF LAKE INDUCED CAPE
BELOW THE INVERSION. GIVEN THE CURRENT FORECAST THERMODYNAMICS
THINKING THAT THE LAKE CONTRIBUTIONS TO SNOWFALL TOTALS WILL BE
MINIMAL BUT PROBABLY ENOUGH TO KEEP LIGHT SNOW SHOWERS GOING SO HAVE
MAINTAINED THE HIGH POPS NEAR THE LAKE SUNDAY NIGHT.

LAKESHORE FLOOD THREAT...
STRONG NORTHEAST WINDS UP TO GALE FORCE WILL LIKELY RESULT IN
LARGE AND BATTERING WAVES DEVELOPING ALONG THE ILLINOIS AND
INDIANA SHORES SUNDAY AFTERNOON AND EVENING. LAKE LEVELS REMAIN
NEARLY A FOOT AND A HALF ABOVE NORMAL...THOUGH DOWN A BIT FROM
WHERE THEY WERE DURING THE HALLOWEEN STORM. ALONG THE LAKEFRONT
FRIDAY AFTERNOON I SAW A LOT OF FRAZZLE ICE HAD DEVELOPED WHICH
COULD HAVE THE EFFECT TO DAMPEN WAVES A BIT ALONG THE SHORE. NONE-
THE-LESS SOME MINOR LAKESHORE FLOODING IS POSSIBLE IF WAVES BUILD
UP TO 10 TO 14 FT AS FORECAST...THOUGH IMPACTS WILL LIKELY BE
PRETTY TRIVIAL SO NOT PLANNING ANY LAKESHORE FLOOD HEADLINES AT
THIS TIME. NOT OUT OF THE QUESTION THAT WE MAY NEED A LAKESHORE
FLOOD ADVISORY EVENTUALLY...PARTICULARLY IF WIND/WAVE FORECAST
GOES ANY HIGHER.

IZZI

&&

.LONG TERM...
200 AM CST

MONDAY THROUGH FRIDAY...

BY MONDAY MORNING...THE SYSTEM THAT IS EXPECTED TO BRING THE WEEKEND
SNOWFALL SHOULD SHIFT WELL TO THE EAST...WITH THE SFC LOW MOVING TO
THE MID ATLANTIC REGION WHILE HIGH PRESSURE BUILDS JUST WEST OF THE
MISSISSIPPI RIVER.  THE RESULTANT LONG...NORTHERLY FETCH OVER LAKE
MICHIGAN SHOULD BE CONDUCIVE TO A LAKE EFFECT BAND OF SNOW
DEVELOPING ALONG THE SPINE OF THE LAKE...AND THE SFC WIND FIELD
ADVERTISED BY MUCH OF THE GUIDANCE DOES INDICATE A SFC CONVERGENCE
BAND AS WELL.  SO...WOULD EXPECT A BAND OF LAKE EFFECT SNOW SHOWERS
POINTING INTO NWRN INDIANA MONDAY MORNING.  THE OVERALL PATTERN
SHOULD BE FAIRLY PROGRESSIVE...SO DO NOT ANTICIPATE THAT A BAND
WOULD SET UP OVER A SINGLE AREA FOR VERY LONG...WITH THE LAKE EFFECT
BAND GRADUALLY MOVING EAST THROUGH THE DAY...PERHAPS JUST CLIPPING
NERN PORTER COUNTY IN THE AFTERNOON.  FOLLOWING THE SYNOPTIC
SNOW...DO NOT ANTICIPATE THAT THIS LAKE EFFECT BAND WOULD
SIGNIFICANTLY ADD TO THE PREVIOUS SNOWFALL.  AS THE SFC HIGH
PRESSURE BUILDS EWD THROUGH THE DAY...TEMPERATURES ACROSS THE REGION
WILL LIKELY ONLY SEE A 5 TO 10 DEGREE DIURNAL RISE THROUGH THE DAY
WITH HIGHS ONLY IN THE TEENS.  BY TUESDAY...THE UPPER LEVEL PATTERN
IS EXPECTED TO BECOME MUCH MORE ZONAL...WITH A SERIES OF WEAK
SHORTWAVES RIPPLING THROUGH THE FAST UPPER LEVEL FLOW.  TIMING OF
INDIVIDUAL SHORTWAVES IN FAST ZONAL FLOW ALOFT BECOMES MORE
PROBLEMATIC WITH TIME...SO CONFIDENCE IN THE EXACT TIMING OF ANY
INDIVIDUAL SYSTEM IMPACTING THE REGION WOULD BE MODERATE AT BEST.
HOWEVER...THAT BEING SAID...THE NEXT CHANCE FOR PCPN ACROSS THE AREA
SHOULD BE MONDAY NIGHT INTO TUESDAY MORNING AS A WEAK
PACIFIC-SOURCED SHORTWAVE QUICKLY SCOOT ACROSS THE AREA...POSSIBLY
BRINGING A LITTLE LIGHT SNOW.  WITH HIGH PRESSURE EXTENDING FROM THE
UPPER OHIO VALLEY THROUGH EAST TEXAS...THERE WILL LITTLE MOISTURE
TRANSPORT FROM THE GLFMEX AND ANY ACCUMULATIONS ASSOCIATED WITH THIS
SYSTEM SHOULD BE LIGHT.  ANOTHER PACIFIC SHORTWAVE...QUICK ON THE
HEELS OF THE FIRST ONE MAY BRING SOME MORE LIGHT SNOW FOR TUESDAY
NIGHT INTO WEDNESDAY...BUT AGAIN...ANY ACCUMULATIONS SHOULD BE
LIGHT.  BY WEDNESDAY NIGHT...ARCTIC HIGH PRESSURE BUILDING OUT OF
CANADA SHOULD SPREAD ACROSS THE NRN PLAINS AND ACROSS THE GREAT
LAKES REGION BY THURSDAY MORNING.  THIS WILL BRING MUCH COLDER
AIR...WITH LOWS DROPPING BELOW 0F OVER THE NWRN PORTIONS OF THE CWA
THURSDAY MORNING...WITH THE REMAINDER OF THE AREA DROPPING INTO THE
SINGLE DIGITS ABOVE 0F. THE COLD...ARCTIC HIGH PRESSURE WILL
DOMINATE THE REGION FOR THE REMAINDER OF THE WEEK.  THE COLDEST
PERIOD SHOULD BE THURSDAY NIGHT INTO FRIDAY MORNING TEMPERATURES
BELOW 0F OVER MUCH OF THE AREA AWAY FROM THE IMMEDIATE
LAKEFRONT...AND EVEN THERE...TEMPERATURES SHOULD ONLY BE IN THE
LOWER SINGLE DIGITS ABOVE ZERO.  THERE SHOULD BE A LITTLE MODERATION
TO TEMPERATURES BY FRIDAY AS THE CENTER OF THE HIGH SLIDES TO THE
EAST AND LOW LEVEL FLOW BECOMES MORE SOUTHERLY...DRAWING SOME
SLIGHTLY WARMER AIR INTO THE REGION WITH HIGHS ON FRIDAY IN THE
UPPER TEENS TO LOWER 20S.

KREIN

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 20Z...

* NO CONCERNS THROUGH 22Z.

* CIGS QUICKLY LOWER TO MVFR WITH PRECIP ONSET ARND 00-02Z. CIGS
  THEN LOWER TO IFR CONDS ARND 5Z AND LIKELY REMAIN AT IFR THRU
  SUN MIDDAY.

* PRECIP ONSET COULD START AS A RAIN/SNOW MIX...BUT SHOULD QUICKLY
  TRANSITION TO ALL SNOW BY 03Z.

* WINDS WILL START BETWEEN 240-260 DEG AND LIGHT...THEN SLOWLY
  FLIP TO NORTH THEN NORTHEAST BY MIDNIGHT. WINDS WILL INCREASE
  SUN MORNING WITH SPEEDS ARND 16-20KT AND GUSTS APPROACHING 30KT
  BY MID-MORNING SUNDAY.

* VISIBILITIES WITH SNOW WILL FALL TO 1SM THEN FURTHER DIMINISH TO
  AROUND 1/2SM OR POSSIBLY 1/4SM SUN MORNING.

BEACHLER

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

VISIBLE IMAGERY BRIEFLY INDICATED SOME THIN CLOUD COVER OVER FAR
NORTHEAST IL/NORTHWEST IN...BUT WITH INCREASING CLOUDS JUST
SOUTHWEST THIS HAS SINCE THICKENED THE CLOUD COVER OVER THE TAF
SITES. BASES THIS AFTERNOON WILL HOVER ARND 6-8KFT AGL...BUT
UPSTREAM ACROSS WESTCENTRAL IL/NORTHEAST MO...CIGS HAVE LOWERED TO
ARND 3-5KFT AGL. EXPECT LOWER CIGS TO ARRIVE AT THE TAF SITES BY
21-22Z...WITH MVFR CONDS DEVELOPING BY 23-00Z. GUIDANCE HAS
REMAINED CONSISTENT WITH THE PRECIP ONSET BEING FOCUSED ARND
2Z...AND COULD BRIEFLY START AS A RAIN/SNOW MIX. BUT WITH SLIGHTLY
DRIER AIR AT THE SURFACE...PRECIP WILL QUICKLY TRANSITION OVER TO
ALL SNOW WITHIN AN HOUR OR TWO.

VSBYS WILL QUICKLY DIMINISH WITH THE STEADIER SNOW DEVELOPING
LATER THIS EVENING...LIKELY FALLING ARND 1 TO 1 1/2 MILES AND
CLOSER TO 1SM BY MIDNIGHT. WINDS WILL REMAIN LIGHT THROUGH THIS
EVENING...BUT STEADILY TURN NORTHWEST THEN NORTH TO NORTHEAST BY
DAYBREAK SUN. THE BULK OF THE SNOW IS EXPECTED TO OCCUR WITHIN
EARLY SUNDAY MORNING THROUGH EARLY SUNDAY AFTERNOON...WITH VSBYS
LIKELY DIMINISHING TO 1/2SM AND COULD BRIEFLY REDUCE FURTHER TO
1/4SM BY LATE MORNING SUNDAY. SIMULATANEOUSLY WINDS WILL BE
INCREASING FROM THE NORTHEAST...AS SUSTAINED WINDS INCREASE TO
NEAR 20KT AND GUSTS APPROACH 30KT BY 14-15Z SUN. IT IS POSSIBLE
GUSTS COULD BE EVEN STRONGER BY MIDDAY...AND COULD PROLONG A
PERIOD OF 1/4 TO 1/2SM VSBYS INTO SUN AFTERNOON.

LAKE EFFECT SNOW IS ALSO A CONCERN FOR SUN AFTERNOON AS NORTHEAST
WINDS INCREASE...WHICH WILL LIKELY KEEP IFR TO POSSIBLY LIFR CIGS
NEARBY INTO THE AFTERNOON HOURS.

BEACHLER

//ORD AND MDW CONFIDENCE...UPDATED 20Z...

* HIGH CONFIDENCE ALL ELEMENTS THROUGH LATE AFTERNOON.

* MEDIUM TO HIGH CONFIDENCE IN THE TIMING OF ONSET OF PCPN.

* HIGH CONFIDENCE IN AN EXTENDED PERIOD OF ACCUMULATING SNOW.

* LOW CONFIDENCE IN THE EXACT ENDING TIME.

* HIGH CONFIDENCE IN AN EXTENDED PERIOD OF IFR CIGS/VIS...BUT
  LOWER CONFIDENCE IN HOW LOW CIGS/VIS WILL GO AND THE DURATION OF
  THE LOWEST CONDITIONS.

* HIGH CONFIDENCE IN GENERAL WIND TRENDS. MEDIUM CONFIDENCE IN THE
  TIMING OF THE WIND SHIFT FROM SWLY TO NELY. THERE COULD BE A
  SHORT PERIOD OF LGT/VRBL WINDS DURG THE TIMING OF THE WIND
  SHIFT.

BEACHLER

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

SUNDAY NIGHT...SNOW AND BLOWING SNOW LIKELY THROUGH MIDNIGHT WITH
IFR CIGS/VIS. SNOW TAPERING OF DURG THE LATE NIGHT HOURS...BUT IFR
CONDITIONS STILL POSSIBLE.

MONDAY...CHANCE LINGERING SNOW SHOWERS IN THE MORNING. CHANCE OF
SNOW AGAIN AFTER MIDNIGHT. MVFR CIGS/VIS LIKELY.  IFR POSSIBLE.

TUESDAY...CHANCE SNOW. PERIODS OF MVFR CIGS/VIS LIKELY.

WEDNESDAY...SLIGHT CHANCE SNOW THROUGH EARLY EVENING. PERIODS OF
MVFR CIGS/VIS POSSIBLE.  VFR/WX NIL OVERNIGHT.

THURSDAY...VFR/WX NIL.

FRIDAY...VFR/WX NIL.

KREIN

&&

.MARINE...
243 AM CST

DISCUSSION...INCREASING NORTHEAST WINDS TONIGHT AND SUNDAY...LIKELY
REACHING GALE FORCE ACROSS SOUTHERN LAKE MICHIGAN WILL BE THE FOCUS
OF THE FORECAST. HIGH PRESSURE IS SPREAD FROM THE LOWER LAKES ACROSS
THE OHIO VALLEY AND TO THE GULF COAST THIS MORNING. WEST TO
SOUTHWEST WINDS HAVE SET UP ACROSS THE LAKE BEHIND THE HIGH. ONE AREA
OF LOW PRESSURE MOVING ACROSS NORTHERN ONTARIO WILL BRING A TROUGH
ACROSS THE LAKE INTO THE AFTERNOON TURNING WINDS NORTHWESTERLY THEN
NORTHEASTERLY LATE AS A NEW LOW DEVELOPS ACROSS THE FRONT RANGE OF
THE ROCKIES...WHICH THEN DEEPENS ACROSS KANSAS AND MISSOURI. SPEEDS
WILL STEADILY INCREASE TONIGHT AND PEAK SUNDAY AS THE LOW TRACKS
INTO CENTRAL INDIANA. WINDS WILL THEN TURN NORTHERLY SUNDAY EVENING
AS THE LOW TRACKS TO THE EAST AND HIGH PRESSURE APPROACHES FROM THE
WEST. STEADY 25-30 KT WINDS ARE LIKELY BY SUNDAY AFTERNOON WITH
GUSTS TO GALE FORCE AROUND 35 KT. THE SYSTEM HAS SHOWED A STRONGER
TREND NOW THAT THE FEATURES DRIVING IT ARE COMING TOGETHER SO 40 KT
IS NOT OUT OF THE QUESTION. WILL CONTINUE WITH THE GALE WATCH FOR
SOUTHERN LAKE MICHIGAN AND THE NEARSHORE WATERS. SOME ICE HAS FORMED
ALONG THE SHORELINE FRIDAY BUT IT LIKELY THIN AND MAY BREAK UP TODAY
THANKS TO MILDER TEMPS AND SOME SUN EARLY. IF NOTHING ELSE
INCREASING WINDS WILL LIKELY BREAK IT UP SO THERE MAY BE LITTLE
TEMPERING AFFECT ON THE WAVES AS A RESULT.

WINDS SLACKEN INTO MONDAY MORNING WITH HIGH PRESSURE PASSING SOUTH
OF THE LAKE LATER IN THE DAY. ANOTHER LOW. SEVERAL LOWS CROSS THE
REGION TUESDAY AND WEDNESDAY BRINGING A PERIOD OF MODEST SOUTHWEST
WINDS BUT A SHIFT TO NORTHWEST WILL OCCUR WEDNESDAY WITH STRONG HIGH
PRESSURE SPREADING IN WEDNESDAY NIGHT.

KREIN

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER STORM WARNING...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-ILZ010-
     ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-ILZ022-
     ILZ023-ILZ032-ILZ033-ILZ039...9 PM SATURDAY TO 9 PM SUNDAY.

IN...WINTER STORM WARNING...INZ001-INZ002-INZ010-INZ011-INZ019...9 PM
     SATURDAY TO 9 PM SUNDAY.

LM...GALE WATCH...LMZ080-LMZ671-LMZ673-LMZ675-LMZ740-LMZ741-LMZ742-
     LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-LMZ872-LMZ874-LMZ876-
     LMZ878...NOON SUNDAY TO MIDNIGHT MONDAY.

&&

$$

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