Climatological Report (Monthly)
Issued by NWS

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CXUS55 KRIW 011011
CLMP60

CLIMATE REPORT
NATIONAL WEATHER SERVICE RIVERTON WY
254 AM MDT SUN OCT 1 2017

...PRELIMINARY MONTHLY CLIMATE SUMMARY FOR THE LAKE YELLOWSTONE FOR
THE MONTH OF SEPTEMBER 2017...

...OFFICIAL CLIMATE DATA FOR THE MONTH OF SEPTEMBER 2017 WILL BE
AVAILABLE APPROXIMATELY IN NOVEMBER 2017 FROM THE NATIONAL CENTER
FOR ENVIRONMENTAL INFORMATION (HTTP://WWW.NCEI.NOAA.GOV/OL/
CLIMATEDATA.HTML). UNOFFICIAL ASOS DAILY SUMMARIES ARE AVAILABLE ON
THE INTERNET AT HTTP://WWW.WEATHER.GOV/CLIMATE/INDEX.PHP?WFO=RIW

...LAKE YELLOWSTONE WAS COLDER AND MUCH WETTER THAN NORMAL IN
SEPTEMBER...

THE AVERAGE TEMPERATURE FOR LAKE YELLOWSTONE IN SEPTEMBER WAS 44.8
DEGREES...WHICH WAS 2.0 DEGREES BELOW NORMAL. THIS MAKES IT THE 7TH
COLDEST SEPTEMBER ON RECORD. THE WARMEST READING OF THE MONTH WAS 79
DEGREES ON THE 2ND AND 3RD...SETTING NEW RECORDS BOTH DAYS. THE HIGH
ON THE 2ND TIED THE PREVIOUS RECORD SET IN 2007. THE HIGH ON THE 3RD
BROKE THE PREVIOUS RECORD OF 78...ALSO SET IN 2007. THESE DAYS ALSO
TIED FOR THE WARMEST SEPTEMBER TEMPERATURE. SEVERAL OTHER RECORD
HIGHS OCCURRED:
NEW RECORD (DATE)                           OLD RECORD (YEAR)
74 DEGREES ON THE 8TH...                    74 DEGREES (2005)
73 DEGREES ON THE 11TH...                   71 DEGREES (2013)
75 DEGREES ON THE 12TH...                   74 DEGREES (2015)

THE COLDEST READING WAS 24 DEGREES ON THE 17TH AND THE 28TH. A NEW
RECORD LOW WAS SET ON THE 17TH...TYING THE PREVIOUS RECORD SET IN
2003. A NEW RECORD LOW OF 27 DEGREES WAS SET ON THE 16TH...TYING THE
PREVIOUS RECORD SET IN 2016.

TOTAL PRECIPITATION FOR THE MONTH WAS 3.33 INCHES...WHICH WAS 256
PERCENT OF NORMAL. THIS MAKES IT THE 2ND WETTEST SEPTEMBER ON
RECORD. THE WETTEST 24 HOUR PERIOD OF THE MONTH WAS THE 19TH...WHEN
0.92 INCHES FELL...AND SETTING A NEW RECORD. THIS BROKE THE PREVIOUS
RECORD OF 0.56...SET IN 2004. SEVERAL OTHER RECORDS WERE SET DURING
THE MONTH:
NEW RECORD (DATE)                           OLD RECORD (YEAR)
0.27 INCHES ON THE 13TH...                  0.20 INCHES (2001)
0.62 INCHES ON THE 14TH...                  0.21 INCHES (2004)
0.86 INCHES ON THE 15TH...                  0.69 INCHES (2015)
0.15 INCHES ON THE 20TH...                  0.13 INCHES (2008)

THE HIGHEST WIND GUST WAS 30 MPH ON THE 19TH.

...THE LAKE YELLOWSTONE WY CLIMATE SUMMARY FOR THE MONTH OF SEPTEMBER 2017...

CLIMATE NORMAL PERIOD 1981 TO 2010
CLIMATE RECORD PERIOD 1998 TO 2017

WEATHER         OBSERVED          NORMAL  DEPART
                 VALUE   DATE(S)  VALUE   FROM
                                          NORMAL
................................................
TEMPERATURE (F)
RECORD
 HIGH              79   09/03/2017
                        09/02/2017
                        09/02/2007
 LOW               13   09/24/2000
HIGHEST            79R  09/03
                        09/02
LOWEST             24   09/28
                        09/17
AVG. MAXIMUM     57.5
AVG. MINIMUM     32.1
MEAN             44.8              46.8    -2.0
DAYS MAX >= 90      0
DAYS MAX <= 32      0
DAYS MIN <= 32     18
DAYS MIN <= 0       0

PRECIPITATION (INCHES)
RECORD
 MAXIMUM         4.09   2013
 MINIMUM         0.25   2008
TOTALS           3.33              1.30    2.03
DAILY AVG.       0.11
DAYS >= .01        11
DAYS >= .10         6
DAYS >= .50         3
DAYS >= 1.00        0
GREATEST
 24 HR. TOTAL    0.92   09/19 TO 09/19

DEGREE_DAYS
HEATING TOTAL     597               548      49
 SINCE 7/1       1150              1135      15
COOLING TOTAL       0                 0       0
 SINCE 1/1          0                 0       0
.................................................

WIND (MPH)
AVERAGE WIND SPEED              2.2
HIGHEST WIND SPEED/DIRECTION    20/270    DATE  09/13
HIGHEST GUST SPEED/DIRECTION    30/250    DATE  09/19

SKY COVER
POSSIBLE SUNSHINE (PERCENT)   MM
AVERAGE SKY COVER           0.00
NUMBER OF DAYS FAIR           24
NUMBER OF DAYS PC              0
NUMBER OF DAYS CLOUDY          0

AVERAGE RH (PERCENT)     69

WEATHER CONDITIONS. NUMBER OF DAYS WITH
THUNDERSTORM              0     MIXED PRECIP               0
HEAVY RAIN                0     RAIN                       0
LIGHT RAIN                5     FREEZING RAIN              0
LT FREEZING RAIN          0     HAIL                       0
HEAVY SNOW                0     SNOW                       0
LIGHT SNOW                4     SLEET                      0
FOG                       0     FOG W/VIS <= 1/4 MILE      0
HAZE                      0

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

LOOKING AHEAD TO OCTOBER 2017...THE AVERAGE HIGH TEMPERATURE ON THE
FIRST OF THE MONTH IS 55 DEGREES...AND THE AVERAGE LOW TEMPERATURE
IS 27 DEGREES. THE AVERAGE HIGH TEMPERATURE BY THE END OF THE MONTH
IS 41 DEGREES...AND THE AVERAGE LOW TEMPERATURE IS 19. THE AVERAGE
MONTHLY PRECIPITATION IS 1.35 INCHES.

$$


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