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ANNUAL CLIMATIC SUMMARY FOR HELENA...CORRECTION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1129 PM MST SAT JAN 1 2000 
 

ANNUAL WEATHER SUMMARY FOR HELENA, 1999
MONTH  HIGH LOW AVG   DEP  PRECIP   DEP   SNOW   DEP  HDD   CDD
                      NOR  LIQUID         FALL         
 
JAN    55   -10 26.8  +7.2  0.45    -0.18  9.0  +0.4  1176    0
FEB    58     6 32.4  +6.0  0.21    -0.20  2.9  -3.1   905    0
MAR    74    16 37.6  +4.0  0.05    -0.68   .T  -7.3   815    0
APR    74    12 40.8  -2.6  1.03    +0.04   MM         718    0
MAY    86    27 50.2  -2.3  1.67    -0.11  2.2  +0.8   451    9
JUN    86    30 58.8  -3.3  1.94    +0.07  0.0   0.0   188   10
JUL   100    39 65.3  -3.3  0.68    -0.42  0.0   0.0    85  108
AUG    96    41 68.4  +2.2  2.26    +0.97  0.0   0.0    20  127
SEP    84    23 52.9  -2.7  0.50    -0.65  0.0  -1.5   354    0
OCT    75    18 45.8  +0.7  0.39    -0.21   .T  -2.3   590    0
NOV    75    14 39.2  +7.3  0.15    -0.33   MM         767    0
DEC    51     5 28.1  +6.9  0.04    -0.55   MM        1136    0
YEAR  100   -10 45.5  +1.5  9.37    -2.24             7205  245
                                                     -1118 -141
 
THE FIRST THREE MONTHS OF THE YEAR WAS WARMER AND DRIER THEN NORMAL AS A
BROAD UPPER LEVEL RIDGE DOMINATED THE WEATHER OVER THE WESTERN UNITED
STATES.
 
FEBRUARY WAS THE 5TH WARMEST FEBRUARY ON RECORD.
 
MARCH WAS DRIER AND WARMER THAN USUAL. ALL OF THE MONTHS MEASURABLE
PRECIPITATION FELL ON THE FIRST DAY. WITH A FAIRLY PERSISTENT HIGH
PRESSURE RIDGE OVER MONTANA DURING THE MONTH...TEMPERATURES WERE 6
DEGREES ABOVE NORMAL.
COOL CONDITIONS PREVAILED DURING THE MONTH OF MAY. TEMPERATURES WERE AN
AVERAGE OF 2.3 DEGREES BELOW NORMAL.

COOL CONDITIONS WERE PREVALENT IN THE HELENA AREA DURING  JUNE.
TEMPERATURES WERE 3.3 DEGREES BELOW NORMAL FOR THE MONTH. PRECIPITATION
WAS ABOUT AVERAGE. 
COOL...DRY CONDITIONS WERE OBSERVED AT HELENA IN JULY. ONE RECORD HIGH
TEMPERATURE WAS SET ON THE 28TH...ALSO A RECORD LOW TEMPERATURE WAS SET
ON THE 16TH. ONLY 61 PERCENT OF THE NORMAL PRECIPITATION EXPECTED FOR
JULY WAS RECORDED. 
OVERALL...AUGUST TURNED OUT TO BE A LITTLE ABOVE  NORMAL IN TERMS OF
PRECIPITATION AND TEMPERATURE. ONE RECORD HIGH TEMPERATURE WAS SET ON
THE 30TH WITH AN AFTERNOON HIGH OF 96 DEGREES.

FOR SEPTEMBER...THE MONTH ALSO STARTED OFF WITH UNSEASONABLY COOL
TEMPERATURES WITH  COOL AIR PREVAILING FOR THE MONTH. HELENA HAD AN
AVERAGE MONTHLY DEPARTURE FROM NORMAL IN TEMPERATURE AT 2.7 DEGREES
BELOW NORMAL. A NOTABLE PEAK WIND OF 64 MPH WAS RECORDED ON THE 25TH.
OCTOBER WAS GENERALLY DRIER THAN NORMAL. ONLY ONE-THIRD OF AN INCH OF
PRECIPITATION FELL. ONE RECORD LOW WAS SET ON THE 3RD. THE TEMPERATURE
FELL TO 18 DEGREES. IT WAS QUITE WINDY ON THE 31ST, WITH A PEAK WIND
GUST OF 61 MPH.
A FAIRLY PERSISTENT UPPER LEVEL RIDGE OF HIGH PRESSURE DOMINATED THE
WEATHER PATTERN OVER MONTANA FOR MUCH OF NOVEMBER. THIS RESULTED IN
TEMPERATURES WELL ABOVE NORMAL FOR THE MONTH...ALONG WITH BELOW NORMAL
PRECIPITATION AMOUNTS. IN FACT...THE AVERAGE TEMPERATURE WAS ABOUT 7
DEGREES WARMER THAN NORMAL. THREE RECORD HIGH TEMPERATURES WERE SET
DURING THE MONTH...75 ON THE 12TH...AND 71 ON THE 13TH...AND 63 ON THE
30TH. THE HIGH OF 75 ON THE 12TH EXCEEDED THE ALL TIME RECORD HIGH
TEMPERATURE FOR THE MONTH OF NOVEMBER. MEASURABLE PRECIPITATION WAS ONLY
REPORTED ON THREE DAYS...THE 4TH...THE 20TH...AND THE 26TH. 

THE UPPER LEVEL RIDGE OF HIGH PRESSURE CONTINUED TO DOMINATE THE WEATHER
FOR MUCH OF DECEMBER AS WELL. THIS RESULTED IN ANOTHER MONTH OF ABOVE
NORMAL TEMPERATURES. THERE WERE SEVERAL MORNINGS WHERE VALLEY FOG
FORMED. ADDITIONALLY, IT WAS ANOTHER DRY MONTH...WITH ONLY 0.04 INCHES
OF PRECIPITATION.
 




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