Forecasters have dropped back on the snow accumulation forecast and have pushed back the timing of the warning in effect. The Winter Storm Warning is now in effect from 9 AM until 1 AM, while last night the warning was in effect from 3 AM until midnight. Radar and satellite images don’t look that impressive, and Quantitative Precipitation Forecast values were lower at 6:00 a.m. CST. The leading edge of precipitation on local radar just started to enter northwest Cook County at about 5:30 a.m. Higher accumulations are now forecast for southern and southwest regions of Chicagoland, but lake snow effect at the end of the storm could balance out the snow depth with northern areas near Lake Michigan keeping up with southwest regions. If Lake Snow doesn’t materialize, Arlington Heights snow accumulation might not hit 6 inches. Winter Storm Warning criteria is a forecast of 6 inches in 12 hours or 8 inches in 24 hours.
The HPC map has accumulation guidance for Arlington Heights at 6-8 inches at a 50 percent chance by 6 AM CST Wednesday. There is a 75 percent chance of 4-6 inches of snowfall accumulation, and only a 25 percent chance of 8-10 inches. The HPC map shows a 90 percent chance of 4-6 inches snow accumulation.
URGENT – WINTER WEATHER MESSAGE
NATIONAL WEATHER SERVICE CHICAGO IL
248 AM CST TUE MAR 5 2013
MCHENRY-LAKE IL-KANE-DUPAGE-COOK-KENDALL-GRUNDY-WILL-KANKAKEE-
LIVINGSTON-IROQUOIS-FORD-LAKE IN-PORTER-NEWTON-JASPER-BENTON-
INCLUDING THE CITIES OF…WOODSTOCK…WAUKEGAN…AURORA…
WHEATON…CHICAGO…OSWEGO…MORRIS…JOLIET…KANKAKEE…
PONTIAC…WATSEKA…PAXTON…GARY…VALPARAISO…MOROCCO…
RENSSELAER…FOWLER
248 AM CST TUE MAR 5 2013 /348 AM EST TUE MAR 5 2013/
…WINTER STORM WARNING NOW IN EFFECT FROM 9 AM CST /10 AM EST/
THIS MORNING TO MIDNIGHT CST /1 AM EST/ TONIGHT…
* TIMING…SNOW WILL INCREASE IN COVERAGE AND INTENSITY DURING THE
MID TO LATE MORNING…CONTINUING THROUGH THE AFTERNOON BEFORE
TAPERING OFF THIS EVENING.
* SNOW ACCUMULATION…4 TO 8 INCHES WITH LOCALIZED AMOUNTS UP TO
10 INCHES POSSIBLE.
* MAIN IMPACTS…ACCUMULATING SNOW SHOULD BEGIN BY MIDDAY AND
LINGER INTO THIS EVENING. SNOW COULD FALL RATHER HEAVILY AT
TIMES WITH SNOW FALL RATES AROUND AN INCH PER HOUR POSSIBLE THIS
AFTERNOON. WINDS WILL INCREASE TO 15 TO 25 MPH AND GUSTY BY THIS
EVENING WHICH COULD RESULT IN SOME BLOWING AND DRIFTING SNOW IN
OPEN AREAS. SNOW IS EXPECTED TO BE FALLING AT A GOOD CLIP
DURING THIS AFTERNOONS RUSH HOUR…SO PLAN ACCORDINGLY FOR POOR
TRAVEL CONDITIONS.
* OTHER IMPACTS…TRAVEL THROUGH O`HARE AND MIDWAY AIRPORTS WILL
LIKELY BE SIGNIFICANTLY AFFECTED BY THIS STORM.
PRECAUTIONARY/PREPAREDNESS ACTIONS…
A WINTER STORM WARNING FOR HEAVY SNOW MEANS SEVERE WINTER WEATHER
CONDITIONS ARE EXPECTED. SIGNIFICANT AMOUNTS OF SNOW ARE FORECAST
THAT WILL MAKE TRAVEL DANGEROUS. CONSIDER ONLY TRAVELING IF IN AN
EMERGENCY. IF YOU MUST TRAVEL…KEEP AN EXTRA FLASHLIGHT…
FOOD…AND WATER IN YOUR VEHICLE IN CASE OF AN EMERGENCY.
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