193
CXUS55 KBOI 012351
CLMBOI
CLIMATE REPORT...UPDATED TO INCLUDE NARRATIVE
NATIONAL WEATHER SERVICE BOISE ID
550 PM MDT WED NOV 01 2023
OCTOBER BROUGHT THREE SEASONS IN ONE MONTH. OVERALL, IT WAS WARMER
AND WETTER THAN NORMAL. WITH AN AVERAGE TEMPERATURE OF 56.3 DEGREES,
IT WAS THE 12TH WARMEST OCTOBER IN 84 YEARS OF BOISE CLIMATE RECORDS.
THE LOW OR 54 ON THE 16TH TIED THE RECORD HIGH LOW FOR THE DATE SET
IN 1945.
THE LOW OF 27 ON THE 28TH WAS THE FIRST FREEZING TEMPERATURE OF THE
SEASON. THE 30-YEAR NORMAL DATE OF THE FIRST TEMPERATURE OF 32 OR
COLDER IS OCTOBER 16TH.
THE TOTAL PRECIPITATION OF 1.24 INCHES TIED WITH 1989 AS THE 18TH
WETTEST OCTOBER ON RECORD.
ON THE 1ST, AN IMPULSE ROTATING FROM THE EAST AROUND AN UPPER-LEVEL
TROUGH OVER NEVADA BROUGHT THE HEAVIEST 24-HOUR PRECIPITATION OF THE
MONTH. THE .47 OF AN INCH OF RAIN BROKE THE PREVIOUS RECORD FOR THE
DATE OF .42 OF AN INCH, SET IN 1946, AND THE HIGH OF 52 BROKE THE
PREVIOUS RECORD LOW HIGH FOR THE DATE OF 54 SET IN 1900.
AS THE NEVADA TROUGH BEGAN TO EXIT ON THE 2ND AND 3RD, HIGHS WARMED
INTO THE MID 60S UNDER NORTHWEST FLOW ALOFT.
OVER THE NEXT SEVERAL DAYS, A HIGH AMPLITUDE UPPER-LEVEL RIDGE MOVED
INLAND OVER THE INTERMOUNTAIN REGION, BRINGING THE WARMEST WEATHER
OF THE MONTH. HIGHS WERE IN THE 80S FROM THE 7TH THROUGH THE 9TH.
THE 87 ON THE 8TH, THE HIGH FOR THE MONTH, WAS 18 DEGREES ABOVE
NORMAL.
ON THE EVENING OF THE 9TH, A PACIFIC COLD FRONT MOVED THROUGH WITH
LIGHT SHOWERS. AS THE UPPER-LEVEL TROUGH FOLLOWED THE FRONT INLAND,
THE HIGH ON THE 10TH WAS 21 DEGREES COOLER THAN THE 86 ON THE 9TH.
THE TROUGH LINGERED OVER THE WESTERN U.S., KEEPING TEMPERATURES DOWN
THROUGH THE 12TH.
A BUILDING UPPER-LEVEL RIDGE STARTED A WARMING TREND ON THE 13TH,
CULMINATING IN 82 DEGREES ON THE 16TH. A TROUGH CROSSING THE PACIFIC
NORTHWEST AND NORTHERN ROCKIES ON THE 17TH WAS ACCOMPANIED BY SLIGHT
COOLING, BUT THE RIDGE QUICKLY REBUILT ON THE 18TH, AND ON THE 20TH
THE TEMPERATURES HIT 80 AGAIN, MOST LIKELY FOR THE LAST TIME UNTIL
NEXT SPRING.
ON THE 22ND AND 23RD, A TROUGH MOVING FROM THE WASHINGTON-OREGON
COAST TO NORTHERN CALIFORNIA AND NEVADA BROUGHT LIGHT RAIN AND A
COOLING TREND. THE MONTH'S ONLY THUNDERSTORM ON THE 22ND WAS
PRECEDED BY OUTFLOW WINDS OF 25 MPH, WITH GUSTS TO 35 MPH.
ON THE 24TH, TEMPERATURES WERE NEAR NORMAL UNDER THE WESTERLY FLOW
THAT FOLLOWED THE TROUGH.
NORTH OF THAT WESTERLY STREAM, A VERY COLD UPPER-LEVEL TROUGH OVER
WESTERN CANADA WAS BEARING DOWN ON OUR AREA.
LIGHT RAIN FELL DURING THE EARLY MORNING HOURS OF THE 25TH. WINDS
GUSTING TO 30 MPH FROM THE SOUTH-SOUTHEAST EARLY IN THE AFTERNOON
DIMINISHED LATER THAT AFTERNOON AS LIGHT RAIN BEGAN AGAIN JUST AHEAD
OF THE ONCOMING COLD FRONT. BETWEEN 4:00 AND 4:30 PM MDT, THE WIND
SHIFTED INTO THE NORTHWEST AS THE FRONT ROARED THROUGH, ACCOMPANIED
BY BRIEF HEAVY RAIN AND GUSTS TO NEARLY 30 MPH. BY THE TIME THE RAIN
ENDED JUST BEFORE 6:00 PM MDT, OVER A QUARTER OF AN INCH HAD FALLEN.
WITH THE TROUGH DIRECTLY OVERHEAD ON THE 26TH, UNSEASONABLY COLD
WEATHER ENSUED. THE TROUGH WAS REINFORCED BY A SECONDARY TROUGH FROM
BRITISH COLUMBIA WHICH ARRIVED OVER OUR AREA ON THE 27TH.
NORTHERLY FLOW AHEAD OF AN APPROACHING UPPER-LEVEL RIDGE BROUGHT THE
COLDEST AIR OF THE MONTH FROM THE 28TH THROUGH THE 30TH. THE LOW OF
24 ON THE 29TH WAS THE LOW FOR THE MONTH.
OUR AREA FARED BETTER THAN AREAS TO OUR NORTH, AS TRUE ARCTIC AIR
PLUNGING SOUTH OVER MONTANA WAS STALLED BY THE MOUNTAINS AND
COMPARATIVELY MILD SURFACE HIGH PRESSURE MOVING IN FROM THE
NORTHWEST. NEVERTHELESS, VERY DRY AIR, MOSTLY CLEAR SKIES, AND LIGHT
WINDS ALLOWED TEMPERATURES TO DROP INTO THE 20S EACH NIGHT FROM THE
28TH THROUGH THE 31ST.
BY THE 31ST, THE UPPER-LEVEL RIDGE HAD MOVED INLAND OVER OUR AREA.
ALTHOUGH TEMPERATURES ALOFT HAD WARMED CONSIDERABLY, THE WARMER AIR
WAS SLOW TO REACH THE SURFACE, DUE TO NIGHTTIME TEMPERATURE
INVERSIONS, STABLE LAYERS ALOFT, AND THE LOW SUN ANGLE AT THIS TIME
OF YEAR.
...............................
..THE BOISE ID CLIMATE SUMMARY FOR THE MONTH OF OCTOBER 2023
CLIMATE NORMAL PERIOD 1991 TO 2020
CLIMATE RECORD PERIOD 1875 TO 2023
WEATHER OBSERVED NORMAL DEPART LAST YEAR'S
VALUE DATE(S) VALUE FROM VALUE
NORMAL
..........................................................
TEMPERATURE (F)
HIGHEST 87 10/08
LOWEST 24 10/29
AVG. MAXIMUM 67.7 64.8 2.9
AVG. MINIMUM 44.9 41.5 3.4
MEAN 56.3 53.2 3.1
DAYS MAX >= 90 0
DAYS MAX <= 32 0
DAYS MIN <= 32 4
DAYS MIN <= 0 0
PRECIPITATION (INCHES)
RECORD
MAXIMUM 4.06 1883
TOTALS 1.24 0.81 0.43
DAYS >= .01 9
DAYS >= .10 3
DAYS >= .50 0
DAYS >= 1.00 0
GREATEST
24 HR. TOTAL 0.47 10/01 TO 10/01
SNOWFALL (INCHES)
TOTALS 0.0
SINCE 7/1 0.0
GREATEST
SNOW DEPTH 0
24 HR TOTAL MM
DEGREE DAYS
HEATING TOTAL 281 377 -96 259
SINCE 7/1 330 472 -142
COOLING TOTAL 20 10 10 11
SINCE 1/1 1342 1044 298
..........................................................
WIND (MPH)
AVERAGE WIND SPEED 6.3
HIGHEST WIND SPEED/DIRECTION 25/290 DATE 10/22
HIGHEST GUST SPEED/DIRECTION 35/300 DATE 10/22
AVERAGE RH (PERCENT) 55
- INDICATES NEGATIVE NUMBERS.
R INDICATES RECORD WAS SET OR TIED.
MM INDICATES DATA IS MISSING.
T INDICATES TRACE AMOUNT.
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