Climatological Report (Monthly)
Issued by NWS Boise, ID

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CXUS55 KBOI 011758
CLMBOI

CLIMATE REPORT
NATIONAL WEATHER SERVICE BOISE ID
1057 AM MST WED MAR 1 2017

FEBRUARY 2017

SPRING-LIKE WEATHER PAID BOISE AN EXTENDED VISIT IN FEBRUARY.
STARTING THE DAY AFTER GROUNDHOG DAY, TEMPERATURES WERE ABOVE NORMAL
MOST DAYS FOR ALMOST THREE WEEKS, AND ELEVEN NIGHTS HAD LOWS ABOVE
FREEZING.

BY THE 5TH THE SNOW HAD MELTED DOWN TO A TRACE, ENDING 52 DAYS OF
CONTINUOUS SNOW COVER OF AN INCH OR MORE. THIS WAS THE 5TH LONGEST
PERIOD ON RECORD, EXCEEDED ONLY DURING FOUR OF THE INFAMOUS WINTERS
OF THE 1980S.

FEBRUARY`S MILD WEATHER WAS THE RESULT OF UPPER LEVEL WINDS FROM THE
SOUTHWEST AND WEST. THIS PATTERN TRANSPORTED ENOUGH MOISTURE INLAND
FROM THE PACIFIC FOR ALMOST DAILY SHOWERS, INCLUDING 2 INCHES OF
SNOW ON THE 7TH, WHICH QUICKLY MELTED.

OFFSHORE AN UPPER LEVEL TROUGH WAS POISED TO MOVE INLAND, AND IT
FINALLY DID ON THE 11TH. IT BROUGHT COOLER AIR, BUT NO PRECIPITATION
FOR BOISE AS IT HEADED SOUTH TO CALIFORNIA AND NORTHWEST MEXICO.

FOLLOWING THIS TROUGH, AN UPPER LEVEL HIGH PRESSURE RIDGE BUILT OVER
THE NORTHWEST STATES. COOL AIR LEFT BEHIND BY THE TROUGH WAS CAPPED
BY WARMER AIR IN THE RIDGE, FORMING A SHALLOW TEMPERATURE INVERSION.
ENOUGH MOISTURE WAS PRESENT IN THE VALLEY FOR THE FORMATION OF LATE
NIGHT AND MORNING FOG FROM THE 13TH THROUGH THE 16TH.

BY THE 16TH THE RIDGE HAD MOVED EAST, LEAVING STRONG SOUTHWEST FLOW
ALOFT AHEAD OF YET ANOTHER UPPER LEVEL TROUGH. A WEAK DISTURBANCE
MOVING THROUGH THIS FLOW BROUGHT ENOUGH INSTABILITY AND WIND TO
BREAK THE INVERSION, AND BY AFTERNOON THE TEMPERATURE HAD REBOUNDED
TO ABOVE NORMAL. THE HIGH OF 58 AT THE AIRPORT THAT DAY WAS THE
WARMEST READING OF THE MONTH.

BEFORE THE TROUGH MOVED INLAND ON THE 22ND, MORE WEAK DISTURBANCES
BROUGHT DAILY SHOWERS, AND THE FIRST THUNDER SINCE OCTOBER WAS
HEARD ON THE 16TH AND 19TH.

THE TROUGH LINGERED OVER THE INTERMOUNTAIN REGION FROM THE 22ND
THROUGH THE END OF THE MONTH, KEEPING TEMPERATURES BELOW NORMAL.
HIGHS FAILED TO RISE ABOVE THE 30S FROM THE 23RD THROUGH THE 27TH,
AND SNOW FLURRIES WERE AN ALMOST DAILY OCCURRENCE. ON THE 28TH A
DISTURBANCE FROM THE GULF OF ALASKA STRENGTHENED AS IT MOVED INTO
THE TROUGH. IT GENERATED AN INCH OF SNOW WHICH COVERED THE GROUND
EARLY THAT MORNING, BUT IT WAS GONE BY THE END OF THE DAY.

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

...THE BOISE ID CLIMATE SUMMARY FOR THE MONTH OF FEBRUARY 2017...

CLIMATE NORMAL PERIOD 1981 TO 2010
CLIMATE RECORD PERIOD 1875 TO 2017

WEATHER         OBSERVED          NORMAL  DEPART  LAST YEAR`S
                 VALUE   DATE(S)  VALUE   FROM    VALUE
                                          NORMAL
.............................................................
TEMPERATURE (F)
HIGHEST            58   02/16
LOWEST             20   02/25
                        02/01
AVG. MAXIMUM     44.6              44.7    -0.1
AVG. MINIMUM     31.0              28.3     2.7
MEAN             37.8              36.5     1.3
DAYS MAX >= 90      0
DAYS MAX <= 32      2
DAYS MIN <= 32     17
DAYS MIN <= 0       0

PRECIPITATION (INCHES)
RECORD
 MAXIMUM         6.49   1872
TOTALS           1.22              0.99    0.23
DAYS >= .01        11
DAYS >= .10         4
DAYS >= .50         0
DAYS >= 1.00        0
GREATEST
 24 HR. TOTAL    0.40   02/06 TO 02/07

SNOWFALL (INCHES)
TOTALS            3.3
SINCE 7/1        38.8
GREATEST
 SNOW DEPTH         3   02/01
 24 HR TOTAL      2.1   02/07

DEGREE_DAYS
HEATING TOTAL     753               798     -45      688
 SINCE 7/1       4287              4159     128
COOLING TOTAL       0                 0       0        0
 SINCE 1/1          0                 0       0
..............................................................

WIND (MPH)
AVERAGE WIND SPEED              9.3
RESULTANT WIND SPEED/DIRECTION   4/140
HIGHEST WIND SPEED/DIRECTION    30/300    DATE  02/23
HIGHEST GUST SPEED/DIRECTION    50/160    DATE  02/16

SKY COVER
POSSIBLE SUNSHINE (PERCENT)   MM

AVERAGE RH (PERCENT)     70


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

$$



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