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000
CXUS55 KBOI 011617
CLMBOI

CLIMATE REPORT
NATIONAL WEATHER SERVICE BOISE ID
1012 AM MDT WED MAY 1 2013

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

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

APRIL WAS A BIT COOLER AND DRIER THAN AVERAGE...AND SEASONABLY
WINDY.

THE AVERAGE TEMPERATURE WAS ALMOST 1 DEGREE BELOW NORMAL
PLACING IT NEAR THE MIDDLE OF THE RANKINGS.

PRECIPITATION WAS ONLY ABOUT A QUARTER INCH BELOW NORMAL.

WIND SPEED AVERAGED QUITE CLOSE TO NORMAL. NO RECORDS WERE
BROKEN. HOWEVER...ON FIVE DAYS WIND GUSTS REACHED OR EXCEEDED 40
MPH...WITH A PEAK GUST OF 46 MPH FROM THE NORTHWEST ON APRIL 8.

AS IS USUAL DURING SPRING...THERE WAS MUCH TEMPERATURE FLUCTUATION.
WE OWE THAT TO A PROGRESSIVE PATTERN WHERE WARM HIGH PRESSURE RIDGES
OR MILD WESTERLY FLOW ALTERNATE WITH COLD LOW PRESSURE TROUGHS WHOSE
SOURCE AREA IS THE GULF OF ALASKA.

WHEN CONDITIONS FAVOR HIGH PRESSURE OVER THE NORTHEAST PACIFIC...AS
IS THE CASE THIS YEAR...THESE TROUGHS COMMONLY SETTLE DOWNSTREAM
OVER THE WESTERN U.S. THE INTERMOUNTAIN REGION WAS VISITED BY FOUR
SUCH TROUGHS DURING APRIL...ON THE 7TH THROUGH THE 9TH...THE 14TH
THROUGH THE 17TH...THE 22ND THROUGH THE 24TH...AND ON THE LAST DAY
OF THE MONTH. THIS RESULTED IN 16 DAYS WHEN TEMPERATURES AVERAGED
BELOW NORMAL. HOWEVER NO LOW TEMPERATURE RECORDS WERE EQUALED OR
EXCEEDED...AS PERSISTENT NORTHWEST WINDS AS WELL AS THE MOUNTAINS TO
OUR NORTH AND EAST PREVENTED COLD CANADIAN AIR FROM ENTERING THE
TREASURE VALLEY. AND THERE WAS NO SNOW COVER TO ENHANCE NIGHTTIME
COOLING.

THERE WERE TWO PERIODS IN APRIL WHEN WARM HIGH PRESSURE RIDGES WERE
ABLE TO BREAK THROUGH THE DOMINANT PATTERN AND BRING ABOVE NORMAL
TEMPERATURES WITH HIGHS IN THE 70S. THESE OCCURRED DURING THE FIRST
WEEK OF THE MONTH...AND AGAIN FROM THE 25TH THROUGH THE 29TH.

THERE WERE ONLY TWO PRECIPITATION EPISODES...ON THE 5TH THROUGH THE
7TH AND AGAIN ON THE 19TH. THE FIRST EVENT BROUGHT A TOTAL OF .62
INCH OF RAIN...ENHANCED BY THUNDERSTORMS WHICH FORMED ALONG AND
BEHIND A COLD FRONT ON THE 7TH. A FEW SPOTS IN THE VALLEY EVEN
RECEIVED SMALL HAIL. THE SECOND EVENT BROUGHT .32 INCH ON THE 19TH.



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
.............................................................
TEMPERATURE (F)
HIGHEST            78   04/27
LOWEST             25   04/18
                        04/14
AVG. MAXIMUM     62.1              62.3    -0.2
AVG. MINIMUM     37.7              39.3    -1.6
MEAN             49.9              50.8    -0.9
DAYS MAX >= 90      0
DAYS MAX <= 32      0
DAYS MIN <= 32      7
DAYS MIN <= 0       0

PRECIPITATION (INCHES)
RECORD
 MAXIMUM         4.73   1869
TOTALS           0.95              1.23   -0.28
DAYS >= .01         5
DAYS >= .10         4
DAYS >= .50         0
DAYS >= 1.00        0
GREATEST
 24 HR. TOTAL    0.32   04/19 TO 04/19
                        04/06 TO 04/07

SNOWFALL (INCHES)
TOTALS              TR
SINCE 7/1        16.0
GREATEST
 SNOW DEPTH         0   MM
 24 HR TOTAL        T   04/16 TO 04/16

DEGREE_DAYS
HEATING TOTAL     445               429      16       MM
 SINCE 7/1       5152              5224     -72
COOLING TOTAL       0                 3      -3       MM
 SINCE 1/1          0                 3      -3
..............................................................

WIND (MPH)
AVERAGE WIND SPEED              9.4
RESULTANT WIND SPEED/DIRECTION   6/315
HIGHEST WIND SPEED/DIRECTION    35/330    DATE  04/08
HIGHEST GUST SPEED/DIRECTION    46/350    DATE  04/13

SKY COVER
POSSIBLE SUNSHINE (PERCENT)   MM

AVERAGE RH (PERCENT)     46


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

$$