000
FXUS63 KLOT 252209
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
409 PM CST SUN JAN 25 2015

.SHORT TERM...
206 PM CST

TONIGHT THROUGH MONDAY NIGHT...

COOL AIR HAS STRUGGLED TO SLIDE SOUTH THIS AFTERNOON...HOWEVER TEMPS
ARE BEGINNING TO FALL INTO THE UPR 20S ACROSS FAR NORTHEAST IL.
ACROSS THE CENTRAL/SOUTHERN CWFA TEMPS REMAIN IN THE LOW 30S WITH
DEW POINT DEPRESSIONS NOT MUCH MORE THAN 1 TO 2 DEGREES. NORTH OF
I-80 PRECIP IS MAINLY FLURRIES...WITH A RAIN/SNOW MIX SLOWLY
CHANGING TO ALL SNOW LATER THIS AFTERNOON ACROSS THE SOUTHERN CWFA.
THE SHORTWAVE THAT BROUGHT THE LIGHT SNOW CONTINUES TO SLIDE EAST
ACROSS SOUTHERN IL...AND WILL STEADILY BRING AN END TO THE PRECIP
ACROSS THE FORECAST AREA THIS EVENING FROM NORTHWEST TO SOUTHEAST.
WINDS WILL GRADUALLY DIMINISH AS WELL AS THE PRESSURE GRADIENT
RELAXES.

SFC RIDGE CENTERED TO THE NORTH THIS AFTERNOON...WILL SAG SOUTH AND
EXPAND TO COVER A PORTION OF THE WESTERN GREAT LAKES/MISSOURI VALLEY
OVERNIGHT. WHILE SOME EROSION TO THE CLOUDS IS PROBABLE NORTH OF THE
FORECAST AREA...EXPECT SOME DECREASE IN CLOUDS CLOSER TO DAYBREAK
MON. CURRENTLY EXPECT OVERNIGHT LOWS TO DIP INTO THE MID/UPR
TEENS...HOWEVER THIS WILL LIKELY NOT OCCUR UNTIL CLOSER TO DAYBREAK
MON.

THE BRIEF BREAK IN CLOUDS MON MORNING WILL QUICKLY GIVE WAY TO THE
NEXT CLIPPER SYSTEM ARRIVING MON AFTN/EVE. GUIDANCE HAS MAINTAINED A
PROGRESSIVE LOOK TO THIS NEXT WAVE...HOWEVER OPERATIONAL SOLUTIONS
ARE EQUALLY BULLISH ON EROSION OF MOISTURE WITHIN THE LOWEST FEW
LAYERS OF THE ATMOS LATE MON NGT. HAVE SOME CONCERN ABOUT P-TYPE MON
AFTN/EVE. AT THE ONSET MOISTURE WILL QUICKLY SATURATE THRU THE -10
DEG C LAYER AND TOUCH THE FAVORED DGZ...HOWEVER THE DEPTH OF THE
MOISTURE BECOMES MORE SHALLOW MON EVE. ALONG WITH THE LACK OF GOOD
LIFT AND SHALLOW MOISTURE...IT IS LOOKING MORE LIKELY THAT PRECIP
MAY BE A MIX OF FREEZING DRIZZLE/LGT-SNOW.

A WEAK THERMAL RIDGE TRIES TO PUSH OVERHEAD MON AFTN...AS LLVL FLOW
TURNS SOUTHWESTERLY. TEMPS SHUD HOVER ARND FREEZING...HOWEVER THIS
WILL HINGE ON CLOUD COVER ARRIVAL AND DEVELOPMENT OF PRECIP. IF THIS
IS DELAYED...TEMPS COULD PUSH A FEW DEGREES WARMER MON EARLY AFTN.

HEIGHTS SLOWLY INCREASE MON NGT...WITH THE MOISTURE PEELING EAST
ALONG WITH THE WEAKENING SHORTWAVE. AT THIS TIME HAVE MAINTAINED A
MENTION OF LGT SNOW OR PATCHY FREEZING DRIZZLE MON NGT...BUT COULD
END UP WITH A DRY PERIOD.

BEACHLER

&&

.LONG TERM...
206 PM CST

TUESDAY THROUGH SUNDAY...
TOWARDS THE MIDDLE OF THE WEEK ENSEMBLES MAINTAIN A HIGH CONFIDENCE
IN THE TROUGH ALONG THE SOUTHEAST CONUS WEAKENING WITH RIDGING
EXPANDING EAST ACROSS THE CENTRAL PLAINS. THIS SHUD PLACE THE BULK
OF THE REGION INTO A WEAK SFC RIDGE TUE/WED. WED AFTN THE SFC RIDGE
QUICKLY SLIDES SOUTHEAST...WHICH COULD ALLOW SOME WARM AIR TO ADVECT
NORTHEAST INTO THE CWFA AND PUSH SFC TEMPS CLOSE TO 40 DEG.

WITH A QUASI-ZONAL SETUP WED NGT/THUR...GUIDANCE SUGGESTS A ROBUST
MID-LVL VORT WILL QUICKLY SLIDE EAST FROM THE ROCKIES TOWARDS THE
PLAINS WED EVE. GUIDANCE THEN FURTHER STRENGTHENS THIS WAVE AND
LIFTS NORTHEAST ACROSS THE FORECAST AREA THUR. SOUNDINGS SUGGESTS
THAT PRECIP COULD START AS MAINLY RAIN WITH THIS SYSTEM...THEN
DYNAMICALLY COOL OVERNIGHT INTO THUR AND TRANSITION PRECIP OVER TO
LGT SNOW.

A RELATIVELY ACTIVE PATTERN CONTINUES TOWARDS THE END OF THE WEEK
INTO EARLY NEXT WEEKEND...WITH TEMPS GENERALLY IN THE UPR 20S/LOW
30S.

BEACHLER

&&

.AVIATION...

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

* MVFR CIGS UNTIL EARLY EVENING
* STRONG/GUSTY NORTHEAST WINDS UNTIL EARLY EVENING
* LIGHT SNOW LATE MONDAY AFTERNOON

IZZI

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

LOW PRESSURE NEAR STL WILL SLOWLY TRACK EAST ACROSS THE OHIO
VALLEY THIS AFTERNOON INTO TONIGHT. AS IT DOES...LIGHT SNOW WILL
SLOWLY TAPER OFF TO FLURRIES. NORTHEAST WINDS OFF THE LAKE MAY
ALLOW SOME LIGHT SNOW SHOWERS TO CONTINUE NEAR THE LAKE BUT NOT
EXPECTING ANYTHING SIGNIFICANT. HAVE MAINTAINED MENTION OF VFR
LIGHT SNOW THROUGH EARLY EVENING THOUGH CONFIDENCE REGARDING END
TIME IS FAIRLY LOW. VISIBILITIES AND CIGS ARE SLOWLY TRENDING UP
AND THIS WILL CONTINUE THRU THE AFTERNOON WITH PREVAILING MVFR
EXPECTED. NORTHEAST WINDS WILL REMAIN STRONG AND GUSTY WITH GUSTS
INTO THE MID/UPPER 20 KT RANGE THROUGH LATE AFTERNOON WITH A SLOW
RELAXING OF THE SPEEDS/GUSTS THRU THE EVENING. A RIDGE AXIS WILL
MOVE ACROSS THE AREA TOWARD DAYBREAK WITH WINDS BECOMING LIGHT AND
VARIABLE AND THEN SWITCHING TO SOUTHERLY MID/LATE MONDAY MORNING.

A WEAK CLIPPER SYSTEM WILL MOVE SOUTHEAST ACROSS THE WESTERN LAKES
MONDAY AFTERNOON INTO MONDAY NIGHT AND WHILE THIS FEATURE HAS BEEN
CONSISTENT FOR A FEW DAYS...IT HAS LIMITED MOISTURE. HOWEVER...
THERE COULD BE A PERIOD OF LIGHT SNOW BY MID/LATE AFTERNOON ACROSS
NORTHERN IL THAT CONTINUES INTO MONDAY EVENING. THE CLOUD LAYERS
APPEAR DEEP ENOUGH FOR LIGHT SNOW BUT AS THE MID LEVELS DRY OUT IN
THE EVENING...PRECIP COULD TRANSITION TO LIGHT FREEZING DRIZZLE.
STILL SOME UNCERTAINTY HOW THIS PLAYS OUT...BUT OPTED TO INCLUDE A
PROB30 IN THE 30HR ORD TAF. CMS

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

* MEDIUM FOR LIGHT SNOW MONDAY AFTERNOON...LOW FOR ASSOCIATED
  CIGS/VIS.
* HIGH CONFIDENCE IN REMAINING FORECAST ELEMENTS

IZZI

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

MONDAY NIGHT...CHANCE LIGHT SNOW/MVFR.

TUESDAY...MVFR CIGS POSSIBLE.

WEDNESDAY...MAINLY VFR DURING THE DAY THEN CHANCE OF -RASN AND
MVFR/IFR AT NIGHT.

THURSDAY...CHANCE OF SNOW. MVFR/IFR POSSIBLE.

FRIDAY...CHANCE OF MVFR CIGS.

SATURDAY...CHANCE OF LIGHT SNOW/MVFR.

RATZER

&&

.MARINE...
131 PM CST

A QUICK MOVING CLIPPER SYSTEM...CURRENTLY CENTERED ACROSS SOUTHERN
ILLINOIS...WILL RAPIDLY SHIFT EASTWARD TOWARDS THE ATLANTIC COAST
BY MONDAY MORNING. NORTHEASTERLY WINDS OF 30-35 KT CONTINUE ACROSS
THE SOUTHERN 1/3RD OF LAKE MICHIGAN...AND THESE WINDS LOOK TO
CONTINUE FOR THE NEXT FEW HOURS...BEFORE A DIMINISHING TREND BEGINS
EARLY THIS EVENING. ANOTHER WEAKENING LOW WILL SHIFT SOUTHWARD JUST
WEST OF THE LAKE LATE MONDAY AND MONDAY NIGHT. THIS WILL RESULT IN A
PERIOD OF SOUTHERLY WINDS OVER THE LAKE DURING THIS PERIOD. LATER IN
THE WEEK ANOTHER LOW IS EXPECTED TO IMPACT THE GREAT LAKES REGION.
THIS SYSTEM STILL HAS THE POTENTIAL TO PRODUCE A PERIOD OF STRONG
SOUTHERLY WINDS LATE WEDNESDAY AND WEDNESDAY NIGHT...FOLLOWED BY A
PERIOD OF STRONG NORTHERLY WINDS THURSDAY INTO EARLY FRIDAY.

KJB

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...LMZ080-LMZ673-LMZ675-LMZ740-LMZ741-LMZ742-LMZ743-
     LMZ744-LMZ745-LMZ777-LMZ779-LMZ874-LMZ876-LMZ878 UNTIL 6 PM
     SUNDAY.

     SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 9 AM MONDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO