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000
CXUS55 KBOI 041326
CLMBOI

CLIMATE REPORT
NATIONAL WEATHER SERVICE BOISE ID
625 AM MST MON FEB 4 2013

................................................................

...THE BOISE ID CLIMATE SUMMARY FOR THE MONTH OF JANUARY 2013...

WITH AN AVERAGE OF 19.6 DEGREES...11.7 DEGREES BELOW NORMAL...
JANUARY 2013 RANKED 10TH COLDEST SINCE TEMPERATURE RECORDS BEGAN IN
THE BOISE AREA. NO JANUARY HAS BEEN THAT COLD SINCE 1985...WHEN THE
JANUARY AVERAGE WAS 19.1 DEGREES. MORE RECENTLY...DECEMBER 1990 WAS
A BIT COLDER WITH 18.1 DEGREES.

DAILY MINIMUM TEMPERATURES THIS JANUARY DIDN/T COME CLOSE TO THE 25
BELOW ON DECEMBER 22 1990. THE COLDEST READING WAS A RELATIVELY
BALMY 3 BELOW ON BOTH THE 21ST AND 22ND. BUT AT THE AIRPORT THAT WAS
THE FIRST SUBZERO TEMPERATURE SINCE THE 6 BELOW ON DECEMBER 8 2009.
SINCE 1990 ONLY THREE WINTERS HAVE EXPERIENCED SUBZERO READINGS.

ANOTHER UNUSUAL FEATURE OF JANUARY 2013 WAS THE PERSISTENT COLD. THE
TEMPERATURE FAILED TO WARM ABOVE FREEZING ON 21 DAYS. FROM THE 11TH
THROUGH THE 23RD TEMPERATURES STAYED WELL BELOW FREEZING...AVERAGING
A FRIGID 11 DEGREES ABOVE ZERO. THAT/S ONLY A COUPLE OF DEGREES
HIGHER THAN THE JANUARY NORMAL AT BISMARCK AND DULUTH. COMPARE THIS
TO LAST WINTER...WHEN BOISE HIGHS WERE ABOVE FREEZING EVERY DAY.

THE SNOWFALL TOTAL OF 9.3 INCHES WAS SLIGHTLY MORE THAN THE AVERAGE
OF 7.1 INCHES. THERE WAS 1 INCH OR MORE ON THE GROUND ON ALL BUT 4
DAYS...AND A CONTINUOUS SNOW COVER FOR NEARLY 3 WEEKS...FROM THE 8TH
THROUGH THE 27TH. BUT THAT ISN/T TERRIBLY UNUSUAL. WE HAD AN EQUALLY
LONG PERIOD OF CONTINUOUS SNOW COVER IN 2008 FROM JANUARY 20 THROUGH
FEBRUARY 8...AND PERIODS EXCEEDING 2 WEEKS IN 2004 AND 2010...AS
WELL AS 22 EARLIER YEARS GOING BACK TO 1949. IN FACT PERIODS OF
CONTINUOUS SNOW COVER EXCEEDING 50 DAYS WERE COMMONPLACE DURING THE
WINTERS OF THE 1980S AND EARLY 1990S.

THE MONTH BEGAN WITH A WEEK OF SUBFREEZING TEMPERATURES...BUT THE
SIEGE OF REALLY COLD WEATHER WAS THE RESULT OF FORTUITOUS TIMING. ON
THE 8TH A PACIFIC WEATHER SYSTEM DUMPED 3 INCHES OF SNOW. ALTHOUGH
RELATIVELY MILD PACIFIC AIR REMAINED OVER THE AREA THROUGH THE
10TH...WITH A HIGHS OF 46 ON THE 9TH AND 35 ON THE 10TH...THE SNOW
FAILED TO COMPLETELY MELT. MEANWHILE MODIFIED ARCTIC AIR IN BRITISH
COLUMBIA HAD BEEN WAITING TO MOVE SOUTH...AND NORTHERLY FLOW OVER
WESTERN NORTH AMERICA PROVIDED THE OPPORTUNITY. THE CANADIAN AIR
BEGAN TO FILTER INTO SOUTHEAST OREGON AND SOUTHWEST IDAHO ON THE
11TH AND 12TH...ALONG WITH A COUPLE MORE INCHES OF POWDERY SNOW. AS
THE COLD FRONT CONTINUED SOUTH INTO THE DESERT SOUTHWEST AND
SOUTHERN CALIFORNIA...AN UPPER LEVEL RIDGE WAS BUILDING OVER THE
PACIFIC NORTHWEST...CAPPING THE COLD AIRMASS WITH MUCH WARMER AIR
...THUS CREATING A MAJOR TEMPERATURE INVERSION. CLEAR SKIES...FRESH
SNOW COVER...AND LONG WINTER NIGHTS PROVIDED IDEAL CONDITIONS FOR
RADIATIONAL COOLING...SO TEMPERATURES IN THE TREASURE VALLEY
CONTINUED TO DROP UNTIL THE 23RD...WHEN CLOUDS AHEAD OF A SERIES OF
PACIFIC WEATHER SYSTEMS STOPPED FURTHER COOLING. ON THE 24TH THE
FIRST SYSTEM PUSHED A WARM FRONT OVER THE INVERSION...BRINGING VERY
RARE FREEZING RAIN TO THE VALLEY. TEMPERATURES FINALLY RETURNED TO
NORMAL ON THE 29TH...THANKS TO A PACIFIC COLD FRONT.


CLIMATE NORMAL PERIOD 1981 TO 2010
CLIMATE RECORD PERIOD 1878 TO 2013

WEATHER         OBSERVED          NORMAL  DEPART  LAST
YEAR`S                          VALUE   DATE(S)  VALUE   FROM
VALUE
NORMAL
.............................................................TEMPERAT
URE (F)
HIGHEST            47
01/31                                         LOWEST
-3
01/22
 01/21                                         AVG. MAXIMUM
27.2              37.8   -10.6                       AVG.
MINIMUM     12.0              24.7   -12.7
MEAN             19.6              31.3
-11.7                       DAYS MAX >= 90
0                                                 DAYS MAX <= 32
21                                                 DAYS MIN <=
32     30                                                 DAYS MIN
<= 0       4

PRECIPITATION (INCHES)
RECORD
 MAXIMUM         5.29
1875                                          TOTALS
1.21              1.24   -0.03                       DAYS >=
.01        11                                                 DAYS
>= .10         7
DAYS >= .50
0                                                 DAYS >=
1.00        0
GREATEST
 24 HR. TOTAL    0.33   01/28 TO
01/29

SNOWFALL (INCHES)
TOTALS
9.3                                                 SINCE 7/1
11.8                                                 GREATEST
 SNOW DEPTH         4
01/29

01/25
 01/24                                          24 HR TOTAL
4.0   01/28 TO 01/29

DEGREE_DAYS
HEATING TOTAL    1402              1046     356
928               SINCE 7/1       3277              3361
-84                       COOLING TOTAL       0
0       0        0               SINCE 1/1
0                 0       0
..............................................................

WIND (MPH)
AVERAGE WIND SPEED              4.0
RESULTANT WIND SPEED/DIRECTION   1/271
HIGHEST WIND SPEED/DIRECTION    26/300    DATE  01/10
HIGHEST GUST SPEED/DIRECTION    33/300    DATE  01/10

SKY COVER
POSSIBLE SUNSHINE (PERCENT)
MM

AVERAGE RH (PERCENT)     80


-  INDICATES NEGATIVE NUMBERS.
R  INDICATES RECORD WAS SET OR TIED.
MM INDICATES DATA IS MISSING.
T  INDICATES TRACE AMOUNT.

$$