Climatological Report (Monthly)
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000
CXAK57 PAJK 041022
CLMKTN
CLIMATE REPORT
NATIONAL WEATHER SERVICE JUNEAU, AK
209 AM AKDT THU JUN 4 2020

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

...THE KETCHIKAN      ASOS CLIMATE SUMMARY FOR THE MONTH OF MAY 2020...

CLIMATE NORMAL PERIOD 1981 TO 2010
CLIMATE RECORD PERIOD 1910 TO 2020

WEATHER         OBSERVED          NORMAL  DEPART
                 VALUE   DATE(S)  VALUE   FROM
                                          NORMAL
................................................
TEMPERATURE (F)
RECORD
 HIGH              93   05/13/1912
 LOW               23   05/28/1971
HIGHEST            78   05/09        72       6
LOWEST             36   05/08        33       3
AVG. MAXIMUM     60.2              55.9     4.3
AVG. MINIMUM     43.8              41.4     2.4
MEAN             52.0              48.6     3.4
DAYS MAX >= 90      0               0.0     0.0
DAYS MAX <= 32      0               0.0     0.0
DAYS MIN <= 32      0               1.6    -1.6
DAYS MIN <= 0       0               0.0     0.0

PRECIPITATION (INCHES)
RECORD
 MAXIMUM        12.44   2001
 MINIMUM         0.68   2015
TOTALS           5.29              8.20   -2.91
DAILY AVG.       0.17              0.28   -0.11
DAYS >= .01        13              16.9    -3.9
DAYS >= .10         8              12.1    -4.1
DAYS >= .50         3               5.5    -2.5
DAYS >= 1.00        1               2.7    -1.7
GREATEST
 24 HR. TOTAL    2.86   05/23 TO 05/23

DEGREE_DAYS
HEATING TOTAL     396               507    -111
 SINCE 7/1       6408              6932    -524
COOLING TOTAL       0                 0       0
 SINCE 1/1          0                 0       0

FREEZE DATES
EARLIEST                        10/25
LATEST                          04/21
.................................................

WIND (MPH)
AVERAGE WIND SPEED              7.6
HIGHEST WIND SPEED/DIRECTION    26/130    DATE  05/23
HIGHEST GUST SPEED/DIRECTION    35/120    DATE  05/23


WEATHER CONDITIONS. NUMBER OF DAYS WITH
THUNDERSTORM              0     MIXED PRECIP               0
HEAVY RAIN                2     RAIN                       4
LIGHT RAIN               18     FREEZING RAIN              0
LT FREEZING RAIN          0     HAIL                       0
HEAVY SNOW                0     SNOW                       0
LIGHT SNOW                0     SLEET                      0
FOG                      10     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.

$$
...MAY 2020 WAS WARM BUT TOO DRY ACROSS SOUTHEAST ALASKA...

A largely unremarkable month, May will be generally regarded as
having slightly above normal temperatureS and fairly dry conditions.

The month led off with offshore flow over the panhandle. This would
serve to resist any significant impacts from any low pressure
systems approaching the region. By the end of the first week of the
month, a prolonged dry streak would begin where no measurable rain
would be recorded at any of our climate sites for nearly two weeks.
In Juneau and Sitka, the dry streak would begin after the 3rd.
Yakutat and Ketchikan would see their last measurable precip for
awhile on the 6th. It was around that this time that large scale
ridging began building over the region. This summer-like pattern
would stifle any possibility of rain for days and would also lead to
well above normal temperatures for many locations between the 8th
and the 13th. The warmest days during this stretch were the 9th and
10th when all four climate sites set daily records for one or both
days.

By the 12th of the month, a pronounced marine layer of clouds had
built up over the Gulf and would begin impacting coastal locations,
and also pushing up from the south into Chatham and Clarence
Straits. Around the same time, a weak frontal boundary was moving
south from the YT. Both of these features would serve to provide
enough cloud cover through the region to maintain temperatures at
near to slightly above normal for several more days, at most
locations. The exceptions to that would be central panhandle
locations that were not impacted by either feature. These locations
would continue to see well above normal temps. Case in point would
be the Juneau Airport where, while not a record, reached a
temperature of 71 (72-2014) on the 17th.

The dry streak would come to an end on the 18th. While some trace
amounts of precip had been noted the previous several days, the
ridge would break down enough to finally allow a frontal system to
move in on the region. Light rain would begin during the evening
hours that Monday and would continue through Tuesday and even into
Wednesday for some areas. After the front passed through into
Canada, ridging built up again over the region. Despite the clearing
for several days, cooler temperatures aloft and another marine layer
impacting coastal areas would prevent the temperature from becoming
quite as warm as earlier in the month.

For Memorial Day Weekend, a robust low would migrate north into the
Gulf and become a fairly persistent feature for several days. The
initial front associated with this low would impact the region,
sending gusty winds to the coastal areas and multiple rounds of
precipitation. The heaviest precipitation was seen on Saturday the
23rd where, notably, Ketchikan recorded 2.22" during the 24 hour
period. After the front moved through, onshore flow around the low
would allow showery activity to remain over the region for the next
few days. A brief period of ridging over the region and dissipation
of the low would give a couple of days reprieve from precip chances
during the last week of the month. Another persistent low would move
up from the south late in the month, however this low would remain
further south than it`s predecessor. This would allow offshore flow
to remain in place over most of the panhandle. This set up a
situation where the initial front and any following short waves
would mainly effect the south. This low would be the main weather
feature for the duration of the month as it would stall in position
on the 28th, begin to slowly weaken before ultimately washing out on
the final day of the month.  The actual weakening of this low would
allow the flow to turn back onshore and reintroduce precip chances
to the northern portions of the panhandle to conclude the month.

In summary, despite the temperatures reverting more toward normal
for the last half of the month, the very warm conditions at the
beginning skew the statistics to show May was a warmer than normal
month. In fact, Juneau recorded the same number of days at or above
70F as last year, possibly portending things to come this summer.
Further, despite two pervasive lows to close the month out,
conditions simply didn`t fall into place to get near normal
rainfall. Even though this time of the year is typically our drier
season, deficits of one to four inches were still noted.

-JDR

$$


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