www.nws.noaa.gov/view/prodsByState.php?state=IL&prodtype=discussion000
FXUS63 KLOT 102153
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
353 PM CST SUN NOV 10 2013
.DISCUSSION...
236 PM CST
MAIN FORECAST CONCERNS WILL BE LAKE EFFECT SNOW OVER NORTHWEST
INDIANA...AS WELL AS TEMPERATURE TRENDS THE UPCOMING WEEK WITH A BIG
COOL DOWN IN STORE.
REST OF TODAY AND TONIGHT...
HIGH PRESSURE BUILDING SOUTH OF THE FORECAST AREA WILL TRANSLATE
EAST ACROSS THE OHIO VALLEY OVERNIGHT WITH WINDS TURNING SOUTHERLY
BEHIND THE DEPARTING HIGH AND AHEAD OF A STRONG COLD FRONT DROPPING
OUT OF CANADA. WITH WINDS AND WARM ADVECTION INCREASING OVERNIGHT...
EXPECT TEMPERATURES TO BOTTOM OUT EARLY THEN HOLD STEADY OR MORE
LIKELY RISE SOME IN THE PREDAWN HOURS.
MONDAY...
A STRONG COLD FRONT IS GOING TO PUSH SOUTH ACROSS THE FORECAST AREA
MONDAY WITH ASCENT ALONG AND BEHIND THE FRONT LEADING TO SHOWERS
DEVELOPING. AHEAD OF THE FRONT...SOUNDINGS ARE PRETTY DRY IN THE LOW
LEVELS SO SUSPECT THERE WILL BE LITTLE IF ANY PRECIP AHEAD...BUT
SOUNDINGS QUICKLY COOL AND SATURATE WITH FROPA...THOUGH MAY TAKE AN
HOUR OR TWO FOR THE NEAR SURFACE WARM LAYER TO COOL ENOUGH TO ALLOW
A COMPLETE TRANSITION TO SNOW. LAPSE RATES INITIALLY RELATIVELY
STEEP THROUGH THE DGZ AND A SHALLOW WARM LAYER NEAR THE SURFACE WILL
LIMIT SNOW TO LIQUID RATIOS...AND ABOVE FREEZING SURFACE TEMPS WILL
INHIBIT ACCUMULATIONS. BEST CHANCE FOR A QUICK ACCUMULATION WILL BE
TOWARDS THE BACK END OF THE BETTER OMEGA LATE AFTERNOON/EARLY
EVENING WHEN THE DGZ DOES DEEPEN SLIGHTLY AND SFC TEMPS FINALLY FALL
BELOW FREEZING. STILL WITH SUCH A SMALL WINDOW AND DRIER AIR
STARTING TO FILTER IN BEHIND THE FRONT...WOULD EXPECT VERY LIGHT
ACCUMULATIONS OF AROUND HALF AN INCH OR SO.
MONDAY EVENING THROUGH TUESDAY...
ATTENTION TURNS TO LAKE EFFECT SNOW BEHIND THE FRONT DEVELOPING
MONDAY EVENING. WITH H85 TEMPS FALLING TO AROUND -12C...LAKE SFC TO
H85 DELTA TS WILL BE PUSHING INTO THE LOW 20C RANGE INDICATING
STRONG LAKE INDUCED INSTABILITY WILL DEVELOP. IN ADDITION...
EQUILIBRIUM HEIGHTS WILL BE PUSHING 15KFT AT TIMES SUGGESTING THERE
MIGHT BE STRONG BURSTS OF HEAVY SNOW PERHAPS EVEN THUNDERSNOW. SEEMS
QUITE POSSIBLE THERE WILL BE LOCALIZED RATES OF 2+ INCHES PER HOUR
AND THE MAIN FORECAST UNCERTAINTY AT THIS POINT IS WHERE EXACTLY THE
BAND SETS UP AND FOR HOW LONG OVER ANY GIVEN AREA. LOCAL WRF RUNS
AND HIGHER RES MODELS ALL IN DECENT AGREEMENT SHOWING CONVERGENCE
SETTING UP OVER THE SOUTH END OF THE LAKE WITH SINGLE BAND LAKE
EFFECT SNOW IMPACTING PORTER AND LA PORTE COUNTIES. EVEN LOWER RES
GUIDANCE IN AGREEMENT WITH PLACEMENT OF THE QPF AXIS RIGHT
ALONG/NEAR OUR EASTERN CWA BORDER. LOCAL WRFS SUGGESTING HALF AN
INCH OF QPF ALONG LA PORTE/PORTER COUNTY BORDER WITH HIGHER VALUES
JUST EAST OF THE COUNTY LINE. WITH SLR FOR LES EVENTS ON THE HIGHER
END OF THE SPECTRUM...DEFINITELY LOOKING AT HEADLINE CRITERIA
SNOWFALL...WITH THE MAIN UNCERTAINTY AGAIN BEING THE THE PLACEMENT
OF THE BAND. THE HIGHEST CIPS ANALOG FOR THE PERIOD VERIFYING 12Z
TUESDAY IS FROM NOV 21 2008 WHERE 8+ INCHES OF SNOW FELL WITHIN THE
SAME AREA OF CONCERN FOR THIS EVENT. WILL GO AHEAD AND ISSUE A LAKE
EFFECT SNOW WATCH THIS AFTERNOON FOR THE POSSIBILITY OF LOCALIZED
AMOUNTS OF 6+ INCHES OF SNOW MONDAY EVENING LATE TUESDAY MORNING OR
EARLY AFTERNOON. TEMPERATURES FALL SHARPLY BEHIND THE
FRONT...AND WITH TEMPERATURES CLEARING OUTSIDE OF THE LAKE EFFECT
SNOW OVERNIGHT...OVERNIGHT LOWS WILL BE IN THE TEENS OR LOW
20S...EXCEPT IN CHICAGO METRO WHICH WILL SEE MID TO UPPER 20S.
DEUBELBEISS
EXTENDED...WEDNESDAY THROUGH SATURDAY...
NORTHWEST FLOW SETS UP WEDNESDAY WITH WEAK RIDGING ALOFT. A TROUGH
DEEPENS OVER THE CENTRAL U.S. WED NIGHT THROUGH THURSDAY NIGHT
LEADING TO SW FLOW OVER THE REGION. AT THE SURFACE HIGH PRESSURE IS
CENTERED OVER MO/AR AND SPREADS OVER THE SE US WED NIGHT BEFORE
MOVING OVER THE ATLANTIC FRIDAY NIGHT. A SURFACE LOW PASSES OVER
NORTHERN QUEBEC WED NIGHT WITH ITS PSEUDO COLD FRONT/WEAK SHORT WAVE
TROUGH ALOFT MOVING OVER THE REGION THURSDAY NIGHT. FORCING IS WEAK
SO WENT WITH UP TO A CHANCE OF PRECIP WITH BETTER CHANCES TO OUR
NORTH. TEMPS WILL BE FALLING OVERNIGHT TO AROUND FREEZING SO WENT
WITH A RAIN/SNOW MIX ACROSS THE CWA. THE GFS IS FASTER WITH THE NEXT
SYSTEM SO DESPITE SLIGHT CHANCE TO CHANCE POPS DURING THE DAY ON
SATURDAY...THINKING THE MAJORITY OF RAIN WILL HOLD OFF TO SATURDAY
NIGHT.
TEMPERATURES IN THE EXTENDED HAVE A WARMING TREND. WEDNESDAY WILL BE
CHILLY WITH HIGHS IN THE UPPER 30S...BUT BY SATURDAY WE ARE LOOKING
AT 925MB TEMPS OF 8 TO 10C AND MAX TEMPS IN THE LOW 50S.
JEE
Feel sorry for the ones living by the lake.
