Climatological Report (Monthly)
Issued by NWS Boise, ID

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CXUS55 KBOI 022213
CLMBOI

CLIMATE REPORT
NATIONAL WEATHER SERVICE BOISE ID
411 PM MDT WED MAY 2 2018

APRIL WAS CHARACTERIZED BY CHANGING WEATHER PATTERNS. MIGRATING HIGH
PRESSURE RIDGES AND LOW PRESSURE TROUGHS AT UPPER LEVELS BROUGHT
ALTERNATING PERIODS OF ABOVE AND BELOW NORMAL TEMPERATURES, BUT
OVERALL THERE WAS A GRADUAL WARMING TREND, AND THE MONTHLY AVERAGE
WAS SLIGHTLY ABOVE NORMAL.

MOST PRECIPITATION FELL DURING THE FIRST 16 DAYS OF THE MONTH, WHEN
HALF THE DAYS HAD MEASURABLE RAIN. THE FINAL 14 DAYS WERE DRY,
EXCEPT FOR A COUPLE OF TRACE EVENTS. AS A WHOLE, APRIL WAS SLIGHTLY
DRIER THAN NORMAL.

THE FIRST HALF OF THE MONTH ALSO SAW THREE STRONG WIND EVENTS. BOISE
FARED SOMEWHAT BETTER THAN THE SURROUNDING REGION, WHERE THERE WAS
LOCAL DAMAGE, AS WINDS IN THE TREASURE VALLEY WEREN`T QUITE AS
STRONG.

ON THE 2ND A RAPIDLY MOVING UPPER LEVEL TROUGH FROM THE GULF OF
ALASKA CROSSED OUR AREA. IT WAS ACCOMPANIED BY A STRONG JET STREAM,
AND A THUNDERSTORM WHICH DROPPED SMALL HAIL ON SOME PARTS OF THE
TREASURE VALLEY. SOME OF THE JET ENERGY REACHED THE SURFACE AS THE
COLD FRONT CAME THROUGH, PRODUCING A GUST OF 49 MPH AT THE AIRPORT.

ON THE 7TH ANOTHER COLD FRONT CROSSED THE BOISE AREA, PROPELLED
RAPIDLY INLAND BY AN INITIALLY STRONG UPPER LEVEL TROUGH APPROACHING
THE WASHINGTON COAST. THE FRONT TRIGGERED THUNDERSTORMS, ONE OF
WHICH GENERATED A GUST OF 55 MPH FROM THE NORTHWEST AT THE AIRPORT.
OVER A QUARTER INCH OF RAIN WAS MEASURED WITH THIS STORM. THE TROUGH
ITSELF FADED OUT AS IT PROGRESSED INLAND.

ON THE 12TH A DEEPER, COLDER TROUGH MOVED OVER OUR AREA. TWO TENTHS
OF AN INCH OF SNOW FELL AT THE AIRPORT, BUT IT MELTED QUICKLY.

ON THE 16TH AN EVEN DEEPER TROUGH PUSHED INLAND, ACCOMPANIED BY A
QUARTER INCH OF RAIN AND A TRACE OF SNOW.

THAT SYSTEM WAS FOLLOWED BY A MORE SETTLED, WARMER PERIOD, WITH
TEMPERATURES NEAR OR ABOVE NORMAL FROM THE 19TH THROUGH THE 28TH. ON
THE MORNING OF THE 18TH ANOTHER WEATHER SYSTEM WAS POISED JUST OFF
THE NORTHWEST COAST, BUT INSTEAD OF HEADING FOR BOISE, IT WENT SOUTH
TO CALIFORNIA ON THE 19TH THEN EAST OVER THE COLORADO PLATEAU ON THE
20TH.

OUR AREA WAS DOMINATED BY HIGH PRESSURE FROM THE 20TH THROUGH THE
27TH. ON THE 27TH THE TEMPERATURE MAXED OUR AT 90, TWO DEGREES SHY
OF THE RECORD.

THE EARLY TASTE OF SUMMER WAS ENDED BY A COLD FRONT ON THE 28TH,
FOLLOWED BY A SLOW MOVING UPPER LEVEL TROUGH ON THE 29TH. THE
COMBINATION OF COLD AIR ALOFT AND SURFACE HEATING IN THE TROUGH
CREATED INSTABILITY WHICH TRIGGERED CONVECTIVE SHOWERS BUT ONLY
TRACES OF RAIN AT THE AIRPORT. THE TROUGH REMAINED ON THE 30TH AND
WAS EXPECTED TO LINGER A FEW MORE DAYS.

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

...THE BOISE ID CLIMATE SUMMARY FOR THE MONTH OF APRIL 2018...

CLIMATE NORMAL PERIOD 1981 TO 2010
CLIMATE RECORD PERIOD 1875 TO 2018

WEATHER         OBSERVED          NORMAL  DEPART  LAST YEAR`S
                 VALUE   DATE(S)  VALUE   FROM    VALUE
                                          NORMAL
.............................................................
TEMPERATURE (F)
HIGHEST            90   04/27
LOWEST             29   04/03
AVG. MAXIMUM     63.9              62.3     1.6
AVG. MINIMUM     40.8              39.3     1.5
MEAN             52.3              50.8     1.5
DAYS MAX >= 90      1
DAYS MAX <= 32      0
DAYS MIN <= 32      3
DAYS MIN <= 0       0

PRECIPITATION (INCHES)
RECORD
 MAXIMUM         4.73   1869
TOTALS           1.01              1.23   -0.22
DAYS >= .01        10
DAYS >= .10         4
DAYS >= .50         0
DAYS >= 1.00        0
GREATEST
 24 HR. TOTAL    0.28   04/07 TO 04/07

SNOWFALL (INCHES)
TOTALS            0.2R
SINCE 7/1        20.1
GREATEST
 SNOW DEPTH         0   MM
 24 HR TOTAL      0.2   04/12 TO 04/12

DEGREE_DAYS
HEATING TOTAL     375               429     -54      460
 SINCE 7/1       5016              5224    -208
COOLING TOTAL       5                 3       2        0
 SINCE 1/1          5                 3       2
..............................................................

WIND (MPH)
AVERAGE WIND SPEED              9.1
RESULTANT WIND SPEED/DIRECTION   2/302
HIGHEST WIND SPEED/DIRECTION    40/300    DATE  04/07
HIGHEST GUST SPEED/DIRECTION    55/300    DATE  04/07

SKY COVER
POSSIBLE SUNSHINE (PERCENT)   MM

AVERAGE RH (PERCENT)     50


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

$$


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