Public Information Statement
Issued by NWS Chicago, IL

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NOUS43 KLOT 080047
PNSLOT
ILZ003>006-008-010>014-019>023-032-033-039-INZ001-002-010-011-019-
081800-

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE CHICAGO IL
647 PM CST SAT FEB 7 2015 /747 PM EST SAT FEB 7 2015/

...RARE MILD AIR OVER SUCH DEEP SNOW COVER...

DEEP AND FRESH SNOW COVER CAN ACT AS A FREEZER KEEPING THE AIR AT
THE SURFACE FROM MODERATING MUCH. FOR ONE...THE SNOW PACK ITSELF
HAS A SUB FREEZING TEMPERATURE ESPECIALLY WHEN DEEP AND RECENT. IN
ADDITION...SNOW COVER HAS A HIGH ALBEDO...MEANING IT IS A VERY
GOOD REFLECTOR OF THE ENERGY FROM THE SUN...NOT ALLOWING THE
SHORT WAVE ENERGY TO BE ABSORBED BY THE GROUND AND RE-EMITTED FOR
WARMING.

ON SATURDAY FEBRUARY 7TH...CHICAGO STARTED THE DAY WITH AN
OFFICIAL SNOW DEPTH OF 14 INCHES. THE HIGH WAS 41 DEGREES. BEFORE
TODAY...CHICAGO HAD A TOTAL OF 178 DAYS SINCE 1884 WITH SNOW
COVER OF 14 OR MORE INCHES TO START THE DAY...BUT ONLY REACHED 40
DEGREES ON EIGHT OF THOSE DAYS. IN OTHER WORDS...THIS ONLY
HAPPENS FIVE PERCENT OF THE DAYS WITH SUCH DEEP SNOW COVER! ODDLY
ENOUGH ONE OF THE EIGHT PRIOR DAYS WAS LAST WINTER ON FEBRUARY
18TH 2014...WHEN THE HIGH REACHED 46 WITH A SNOW DEPTH TO START
THE DAY OF 14 INCHES.

ROCKFORD STARTED THE DAY WITH A DEPTH OF 11 INCHES AND REACHED A
HIGH OF 39 DEGREES. BEFORE TODAY...ROCKFORD HAD A TOTAL OF 254
DAYS WITH SNOW COVER OF 11 OR MORE INCHES TO START THE DAY...BUT
ONLY REACHED 39 DEGREES OR WARMER ON NINE OF THEM. THAT IS ONLY 4
PERCENT OF THE TIME WITH SUCH DEEP SNOW COVER. THE LAST TIME IT
HAPPENED WAS ALSO FEBRUARY 18TH 2014...WHEN THE HIGH REACHED 44
DEGREES WITH A SNOW DEPTH OF 13 INCHES TO BEGIN THAT DAY.

$$

MTF





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