Climatological Report (Monthly)
Issued by NWS Portland, ME

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CLIMATE REPORT
NATIONAL WEATHER SERVICE GRAY ME
1018 AM EDT WED OCT 4 2017

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

...THE PORTLAND ME CLIMATE SUMMARY FOR THE MONTH OF SEPTEMBER 2017...

CLIMATE NORMAL PERIOD 1981 TO 2010
CLIMATE RECORD PERIOD 1941 TO 2017 /FOR TEMPERATURES/
CLIMATE RECORD PERIOD 1871 TO 2017 /FOR PRECIPITATION/
CLIMATE RECORD PERIOD 1882 TO 2017 /FOR SNOWFALL/

WEATHER         OBSERVED          NORMAL  DEPART  LAST YEAR`S
                 VALUE   DATE(S)  VALUE   FROM    VALUE  DATE(S)
                                          NORMAL
................................................................
TEMPERATURE (F)
RECORD
 HIGH              95   09/11/1983
                        09/07/1945
 LOW               23   09/30/1941
HIGHEST            86   09/24        86       0       91  09/09
LOWEST             41   09/30        37       4       39  09/26
AVG. MAXIMUM     74.3              70.0     4.3     74.0
AVG. MINIMUM     54.9              50.3     4.6     53.6
MEAN             64.6              60.1     4.5     63.8
DAYS MAX >= 90      0               0.3    -0.3        1
DAYS MAX <= 32      0               0.0     0.0        0
DAYS MIN <= 32      0               0.2    -0.2        0
DAYS MIN <= 0       0               0.0     0.0        0

PRECIPITATION (INCHES)
RECORD
 MAXIMUM        10.84   2008
 MINIMUM         0.30   1948
TOTALS           2.23              3.69   -1.46     0.86
DAILY AVG.       0.07              0.12   -0.05     0.03
DAYS >= .01         7               9.2    -2.2        7
DAYS >= .10         3               5.6    -2.6        4
DAYS >= .50         3               2.3     0.7        0
DAYS >= 1.00        0               1.1    -1.1        0
GREATEST
 24 HR. TOTAL    0.91   09/03 TO 09/03

SNOWFALL (INCHES)
RECORDS
 TOTAL              T   1992
TOTALS            0.0               0.0     0.0      0.0
SINCE 7/1         0.0               0.0     0.0      0.0
SNOWDEPTH AVG.      0
DAYS >= TRACE       0               0.0     0.0
DAYS >= 1.0         0               0.0     0.0
GREATEST
 SNOW DEPTH         0
 24 HR TOTAL      0.0

DEGREE_DAYS
HEATING TOTAL      68               176    -108       97
 SINCE 7/1        101               221    -120      111
COOLING TOTAL      65                30      35       68
 SINCE 1/1        429               358      71      553
.................................................................

WIND (MPH)
AVERAGE WIND SPEED              6.9
HIGHEST WIND SPEED/DIRECTION    24/140    DATE  09/03
HIGHEST GUST SPEED/DIRECTION    32/080    DATE  09/03

SKY COVER
AVERAGE SKY COVER           0.50

AVERAGE RH (PERCENT)     73

WEATHER CONDITIONS. NUMBER OF DAYS WITH
THUNDERSTORM              1     HEAVY RAIN                 3
RAIN                      3     LIGHT RAIN                 8
FREEZING RAIN             0     LT FREEZING RAIN           0
HEAVY SNOW                0     SNOW                       0
LIGHT SNOW                0     FOG                       12
FOG W/VIS <= 1/4 MILE     3     HAZE                       2

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

&&

SEPTEMBER BEGAN THE WAY AUGUST ENDED, WITH COOL, FALL-LIKE WEATHER
INCLUDING NIGHTTIME TEMPERATURES IN THE 40S. THAT WOULD QUICKLY
CHANGE, HOWEVER, AS A WARM, HUMID WEATHER PATTERN SET UP FOR MOST OF
THE MONTH. PORTLAND WOULD NOT SEE A TEMPERATURE IN THE 40S AGAIN FOR
NEARLY 4 WEEKS. AFTER A FEW DAYS OF RAIN INCLUDING NEARLY AN INCH ON
THE 3RD, A NEW WEATHER PATTERN BEGAN TO EMERGE. A RIDGE OF HIGH
PRESSURE BUILT OVER THE WESTERN ATLANTIC AND THE EASTERN UNITED
STATES, ALLOWING WARM, HUMID AIR TO BE CONTINUALLY TRANSPORTED
NORTHEASTWARD INTO NEW ENGLAND. THERE WERE SEVERAL TROPICAL STORMS
AND HURRICANES THAT TRACKED NORTHWARD NEAR THE EAST COAST ALONG THE
WESTERN SIDE OF THE RIDGE, BUT EACH OF THESE STORMS STAYED FAR
ENOUGH AWAY TO AVOID ANY RAINFALL IN PORTLAND. ALTHOUGH THERE WERE A
FEW COLD FRONTS WHICH MANAGED TO DROP TEMPERATURES BACK CLOSER TO
NORMAL LEVELS, THE TREND OF WARM AND HUMID CONDITIONS KEPT
RETURNING. THE WARMEST PERIOD WAS FROM THE 23RD THROUGH THE 27TH
WHEN PORTLAND SAW 5 STRAIGHT DAYS IN THE 80S. A STRONG COLD FRONT
BROUGHT COOLER WEATHER FOR THE LAST TWO DAYS OF THE MONTH, MORE
TYPICAL OF WHAT WOULD BE EXPECTED IN FALL.

THE AVERAGE TEMPERATURE FOR THE MONTH WAS 64.6 WHICH WAS 4.5 DEGREES
ABOVE NORMAL AND THE SECOND WARMEST SEPTEMBER ON RECORD. THE WARMEST
SEPTEMBER WAS JUST TWO YEARS AGO WHEN THE AVERAGE TEMPERATURE WAS
65.3 DEGREES IN 2015. THE COOLEST WAS IN 1950 WHEN IT WAS 54.5
DEGREES. OF THE TOP TEN WARMEST SEPTEMBERS, 5 HAVE OCCURRED SINCE
2010 AND 8 SINCE 1999. THE FOLLOWING TABLE LISTS THE WARMEST
SEPTEMBERS ON RECORD.

WARMEST AVERAGE TEMPERATURE FOR SEPTEMBER (SINCE 1940)...
RANK  TEMP  YEAR
1     65.3  2015
2     64.6  2017 <===
3     64.1  1961
4     63.8  2016
5     63.6  2005
6     63.4  2010
7     63.3  1999
8     63.1  2002
9     62.9  1983
10    72.8  2011

A TOTAL OF 2.23 INCHES OF RAIN FELL WHICH WAS 1.46 INCHES BELOW
NORMAL AND THE 4TH CONSECUTIVE MONTH OF BELOW NORMAL PRECIPITATION
IN PORTLAND. NEARLY ALL OF THE RAIN FELL IN THE FIRST WEEK OF THE
MONTH, WITH THE HEAVIEST FALLING ON THE 3RD WHEN 0.91 INCHES WAS
RECORDED. THE DRIEST SEPTEMBER ON RECORD WAS IN 1948 WHEN ONLY 0.30
INCHES FELL. THE WETTEST WAS IN 2008 WHEN 10.84 INCHES WAS RECORDED.

THE FOLLOWING DAILY RECORDS WERE SET OR TIED IN SEPTEMBER 2017...
DATE  RECORD                                PREVIOUS
20    65 - WARMEST LOW TEMPERATURE          64 IN 2016
27    84 - WARMEST HIGH TEMPERATURE         84 IN 2014 /TIED/
27    72 - WARMEST AVERAGE TEMPERATURE      67 IN 2014 AND OTHERS

$$

KIMBLE



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