The Weather Wire

January 2014 Volume 21 Number 01

Contents:

2013 Weather Highlights from the NWS Boulder/2013 Climate Summary for Denver (DIA)

Drought Monitor

December Summary/Statistics

January Preview

Sunrise/Sunset

Snowfall Totals

2013 Weather Highlights from the NWS Boulder

JANUARY 2013 STARTED OUT COLDER THAN NORMAL WITH THE DAILY TEMPERATURE IN DENVER 14 DEGREES BELOW AVERAGE ON THE 1ST AND 7 DEGREES BELOW AVERAGE ON BOTH THE 2nd AND 3rd OF THE MONTH. FROM THE 4th ONWARD DAILY TEMPERATURES ROSE STEADILY TO A BALMY 60 DEGREES ON THE 9th. TEMPERATURES THEN TURNED COLDER WITH THE PASSAGE OF A COLD FRONT ON THE 9th. THE ARRIVAL OF A MUCH STRONGER ARCTIC FRONT ON THE 12th SENT TEMPERATURES WELL BELOW AVERAGE WITH DAYTIME HIGHS IN THE TEENS AND OVERNIGHT LOWS WELL BELOW ZERO FOR THE NEXT FEW DAYS. TEMPERATURE DEPARTURES FROM NORMAL ON THE 12th, 13th AND 14th WERE 32 DEGREES...30 DEGREES AND 29 DEGREES BELOW AVERAGE RESPECTIVELY MAKING THIS THE COLDEST TIME PERIOD OF THE MONTH. LIGHT SNOW ALSO FELL DURING THIS COLD WAVE WITH 1.1 INCHES FALLING WITH THE COLD FRONT ON THE 14TH...0.3 INCH ON THE 12th AND A TRACE OF SNOW ON THE 13th AND 14th. BY JANUARY 15th WARMER TEMPERATURES RETURNED TO THE DENVER AREA WITH DAYTIME READINGS IN THE 40S ON THE 16th AND 17th LATER WARMING TO THE 60S ON THE 22nd, 24th AND 25th. ON THE 29th THE DENVER AREA WAS VISITED BY ANOTHER COLD FRONT WHICH SENT TEMPERATURES SEVERAL DEGREES BELOW AVERAGE AND BROUGHT 2.7 INCHES OF SNOW ON THE 28th AND 0.5 INCH OF SNOW ON THE 29th. JANUARY MEAN TEMPERATURE ENDED 0.4 DEGREE BELOW AVERAGE AND PRECIPITATION 0.10 INCH BELOW AVERAGE. SNOWFALL FOR THE MONTH TOTALED 4.6 INCHES. FEBRUARY 2013 BEGAN MILD WITH DAILY TEMPERATURES VARYING FROM 4 TO 14 DEGREES ABOVE AVERAGE FROM THE 1ST TO THE 8th OF THE MONTH. IN THE MIDST OF THIS RUN OF MILD WEATHER DENVER RECORDED A TRACE OF SNOW ON THE 6th AND 7th. TEMPERATURES TURNED COLDER ON THE 9th AND A TRACE OF SNOW FELL THAT DAY. TEMPERATURES FOR THE REMAINDER OF THE MONTH STRUGGLED TO RETURN TO AVERAGE. ONLY THE 13th, 16th AND 17th HAD DAILY TEMPERATURES ABOVE AVERAGE. DENVER RECEIVED NEARLY ALL OF ITS SNOWFALL DURING THE LAST

9 DAYS OF THE MONTH WITH 1.7 INCHES ON THE 20th 2.3 INCHES ON THE 21st 9.1 INCHES WITH A SNOW STORM ON THE 24th AND 1.0 INCH ON THE 26th. FEBRUARY 2013 ENDED 2.4 DEGREE BELOW AVERAGE IN TEMPERATURE AND 0.40 INCH ABOVE AVERAGE IN PRECIPITATION. SNOWFALL FOR THE MONTH TOTALED 14.1 INCHES. MARCH 2013 WAS A SNOWY MONTH FOR DENVER WITH A TOTAL OF SEVEN DAYS RECORDING MEASURABLE SNOWFALL AT DENVER`S INTERNATIONAL AIRPORT. TWO INCHES FELL ON THE 4th, 5.4 INCHES ON THE 9th, 3.9 INCHES ON THE 11th, 0.5 INCH ON THE 12th, 5.4 INCHES ON THE 22nd, 6.4 INCHES ON THE 23rd AND 0.1 INCH ON THE 24th. PASSAGE OF A STRONG COLD FRONT ON THE 22nd SENT TEMPERATURE READINGS DOWNWARD WITH HIGH TEMPERATURES IN THE 20S AND LOW TEMPERATURES IN THE SINGLE DIGITS ON THE 23rd, 24th AND 25th. TEMPERATURES REBOUNDED ON THE 26th AND REMAINED ABOVE AVERAGE FOR THE REMAINING DAYS OF THE MONTH. MARCH 2013 ENDED 2.7 DEGREE BELOW AVERAGE IN TEMPERATURE AND 0.55 INCH ABOVE AVERAGE IN PRECIPITATION. SNOWFALL FOR THE MONTH TOTALED 23.5 INCHES. APRIL 2013 WAS BOTH COLD AND SNOWY FOR DENVER. THE MONTH STARTED OUT WARMER THAN AVERAGE WITH HIGH TEMPERATURES RANGING FROM 60 DEGREES ON THE 3rd TO 72 DEGREES ON THE 5th. TEMPERATURES REMAINED ON THE MILD SIDE THROUGH THE 8th WITH A HIGH OF 71. ON THE 9th THE DENVER AREA SAW TEMPERATURES PLUNGE WITH THE PASSAGE OF A STRONG ARCTIC COLD FRONT THAT RESULTED IN A HIGH TEMPERATURE OF ONLY 22 DEGREES ON THE 9th AND 23 DEGREES ON THE 10th. FROM THE 9th TO THE 11th , 6.6 INCHES OF SNOW FELL AT THE DENVER INTERNATIONAL AIRPORT WITH THE BULK OF THIS SNOW FALLING ON THE 9th. ON THE 10th TEMPERATURES ROSE SIGNIFICANTLY AND REMAINED NEAR AVERAGE FOR THE NEXT FEW DAYS. FOR THE REMAINDER OF THE MONTH TEMPERATURES CONTINUED TO BOUNCE AROUND SWINGING FROM A HIGH OF ONLY 30 DEGREES ON THE 23rd TO A VERY WARM HIGH TEMPERATURE OF 80 DEGREES ON THE 29th. APRIL 2013 ENDED 5.7 DEGREE BELOW AVERAGE IN TEMPERATURE AND 0.16 INCH ABOVE AVERAGE IN PRECIPITATION. SNOWFALL FOR THE MONTH TOTALED 20.4 INCHES. MAY 2013 IN DENVER WAS MARKED BY WARMER THAN AVERAGE TEMPERATURES AND BELOW AVERAGE PRECIPITATION. SLOW TO WARM DURING THE FIRST COUPLE OF DAYS WITH THE AVERAGE DAILY TEMPERATURE RUNNING 20 DEGREES BELOW AVERAGE. TEMPERATURE READINGS STEADILY ROSE AND BY THE MIDDLE OF THE MONTH DAYTIME TEMPERATURES HAD MANAGED TO WARM TO THE LOW AND MIDDLE 80S. EXCEPT FOR SLIGHTLY BELOW AVERAGE TEMPERATURES ON 20th, 21st, 23rd, 29th, 30th AND 31st. THE DAILY TEMPERATURES FOR THE REMAINDER OF THE MONTH RANGED FROM 5 TO 9 DEGREES ABOVE AVERAGE. DENVER SAW ITS ONLY SNOWFALL ON THE FIRST TWO DAYS OF THE MONTH WITH 3.2 INCHES ON THE 1st AND 0.2 INCHES ON THE 2nd. MEASURABLE RAINFALL WAS RECORDED ON THE 7th, , 8th, 15th, 20th,22nd AND THE 29th TOTALING 0.57 INCH. MAY 2013 ENDED 0.8 DEGREE ABOVE AVERAGE IN TEMPERATURE AND 1.30 INCH BELOW AVERAGE IN PRECIPITATION. SNOWFALL FOR THE MONTH TOTALED 3.4 INCHES. JUNE 2013 STARTED OUT WITH BELOW NORMAL TEMPERATURES WITH SIX OUT OF THE FIRST SEVEN DAYS BEING BELOW NORMAL. THE LOW TEMPERATURE OF 39

DEGREES ON THE MORNING OF THE 2nd WAS THE COLDEST TEMPERATURE OF THE MONTH. UPPER LEVEL HIGH PRESSURE OVER THE ROCKY MOUNTAIN REGION AND SOUTHERN PLAINS STATES BROUGHT A STRETCH OF 90 DEGREE + WEATHER TO DENVER FROM THE 10th THROUGH THE 14th. RECORD HIGH TEMPERATURES WERE RECORDED ON THE 10th AND 11th WITH THE 100 DEGREES ON THE 11th BEING THE HOTTEST DAY OF THE MONTH. FROM THE 15th TO THE 18th THE UPPER RIDGE SHIFTED EAST WHICH ALLOWED A COUPLE WEAK COLD FRONTS AND A SLIGHT INCREASE IN MOISTURE TO MOVE INTO NORTHEASTERN COLORADO. THIS RESULTED IN COOLER TEMPERATURES; HOWEVER TEMPERATURES STILL REMAINED ABOVE NORMAL. ON THE 18th A TORNADO MOVED ACROSS THE EASTERN SIDE OF DIA. THE DIA ASOS REPORTED A WIND GUST OF 97 MPH AT 2:27 PM. DENVER EXPERIENCED HOT AND DRY WEATHER FROM THE 19th – 21st BEFORE ANOTHER WEAK COLD FRONT COOLED TEMPERATURES ON THE 22nd AND 23rd. DIA MEASURED 0.51 INCHES OF RAIN FROM A THUNDERSTORM ON THE 23rd WHICH WAS THE GREATEST DAILY PRECIPITATION FOR THE MONTH. THE MONTH ENDED WITH HOT AND DRY WEATHER FROM THE 24th – 28th WITH NEAR NORMAL TEMPERATURES THE FINAL TWO DAYS OF THE MONTH. JUNE 2013 ENDED 3.7 DEGREES ABOVE AVERAGE IN TEMPERATURE AND 1.23 INCH BELOW AVERAGE IN PRECIPITATION. JULY 2013 IN DENVER STARTED OUT WITH BELOW NORMAL TEMPERATURES WITH LIGHT PRECIPITATION ON THE FIRST. UPPER LEVEL HIGH PRESSURE THEN BUILT OVER THE ROCKY MOUNTAIN REGION WHICH RESULTED IN ABOVE NORMAL TEMPERATURES FROM THE 3rd THROUGH THE 13th. TEN OUT OF ELEVEN DAYS DURING THIS PERIOD HAD TEMPERATURES IN THE 90`S WITH THE 100 DEGREES ON THE 11th WAS THE HOTTEST DAY OF THE MONTH. FROM THE 12th THROUGH THE 16th AN UPPER LEVEL LOW TOOK A VERY UNUSUAL TRACK FROM WEST VIRGINIA TO SOUTHERN NEW MEXICO. COOLER AND VERY MOIST AIR ASSOCIATED WITH THIS SYSTEM PRODUCED OVER 3 INCHES OF RAIN IN WHEATRIDGE ON THE 14th AND 0.87 AT DIA ON THE 15th. FROM THE 17th THROUGH THE 26th THE TEMPERATURE REMAINED AT NEAR NORMAL VALUES WITH ONLY A TRACE OF PRECIPITATION MEASURED. A WEAK COLD FRONT BROUGHT COOLER TEMPERATURES AND INCREASED PRECIPITATION TO DENVER FOUR OF THE LAST 5 DAYS OF THE MONTH. JULY 2013 ENDED 0.1 DEGREE ABOVE AVERAGE IN TEMPERATURE AND -0.18 INCH BELOW AVERAGE IN PRECIPITATION. AUGUST 2013 STARTED OUT HOT AND DRY WITH ABOVE NORMAL TEMPERATURES THE FIRST TWO DAYS OF THE MONTH. A WEAK COLD FRONT COMBINED WITH AN UPPER LEVEL DISTURBANCE AND MONSOONAL MOISTURE PRODUCED HEAVY RAIN AND WIDESPREAD SEVERE WEATHER ACROSS THE FRONT RANGE URBAN CORRIDOR ON THE 3rd. SEVERE THUNDERSTORMS PRODUCED VERY HEAVY RAIN AND EXTENSIVE WIND DAMAGE ACROSS ERIE. VERY HEAVY RAIN ALSO PRODUCED FLASH FLOODING IN PARTS OF AURORA. SOME AREAS AROUND THE FRONT RANGE RECEIVED 3.5 INCHES OF RAIN WITH 0.66 INCHES OF RAIN AND A WIND GUST OF 55 MPH AT DIA DURING THE EVENT. TEMPERATURES REMAINED SLIGHTLY ABOVE NORMAL THROUGH THE 6th WITH A STRETCH OF BELOW NORMAL TEMPERATURES FROM THE 7th THROUGH THE 15th. ONLY VERY LIGHT PRECIPITATION OCCURRED DURING THAT PERIOD. ABOVE NORMAL TEMPERATURES RETURNED TO DENVER BY THE 16th AND CONTINUED THROUGH THE END OF THE MONTH AS UPPER LEVEL HIGH PRESSURE REESTABLISHED OVER THE ROCKY MOUNTAIN REGION. RECORD HIGH

TEMPERATURES OF 97 AND 99 DEGREES WERE RECORDED ON THE 17th AND 20th RESPECTIVELY. INCREASED MOISTURE BEHIND A COLD FRONT COMBINED WITH MONSOONAL MOISTURE PRODUCED SEVERE WEATHER AND HEAVY RAIN ACROSS METRO DENVER AND THE PALMER DIVIDE ON THE 22nd. DIA MEASURED 1.94 INCHES OF RAIN ALONG WITH A WIND GUST OF 53MPH. THE 1.94 INCHES OF PRECIPITATION SET A RAINFALL RECORD THE DATE. AUGUST 2013 ENDED 2.1 DEGREES ABOVE AVERAGE IN TEMPERATURE AND 1.09 INCHES ABOVE AVERAGE IN PRECIPITATION. SEPTEMBER 2013 GOT OFF TO A HOT AND DRY START AS A STRONG AND PERSISTENT UPPER LEVEL RIDGE OF HIGH PRESSURE REMAINED CENTERED OVER COLORADO. DENVER EXPERIENCED A SEVEN DAY STRETCH OF 90+ DEGREE WEATHER FROM THE 2nd THROUGH THE 8th WITH THREE DAILY HIGH TEMPERATURE RECORDS TIED OR BROKEN DURING THIS PERIOD. THIS HOT AND DRY PERIOD WOULD FINALLY END BY THE 9th AS THE UPPER RIDGE SHIFTED INTO THE CENTRAL PLAINS STATES AND A COLD FRONT MOVED INTO NORTHEASTERN COLORADO. THIS FRONT TRIGGERED STRONG THUNDERSTORMS WITH VERY HEAVY RAIN AND HAIL ACROSS THE INTERSTATE 76 CORRIDOR OF THE DENVER METRO AREA. BY THE 1Oth THE UPPER HIGH WAS CENTERED OVER THE SOUTHERN MISSISSIPPI VALLEY WITH AN UPPER LEVEL LOW PRESSURE SYSTEM CENTERED OVER SOUTHERN NEVADA. THIS PATTERN PRODUCED A DEEP SOUTHERLY FLOW OVER THE REGION WHICH PUMPED COPIOUS AMOUNTS OF MONSOONAL MOISTURE INTO COLORADO FROM THE SOUTH. IN ADDITION A WEAK STATIONARY FRONT STRETCHED ALONG THE FRONT RANGE FOOTHILLS INTO THE PALMER DIVIDE. THIS RESULTED IN VERY COOL TEMPERATURES AND MODERATE TO HEAVY RAIN ACROSS METRO DENVER, PALMER DIVIDE AND FRONT RANGE FOOTHILLS ON THE 11th. THE STATIONARY FRONT REMAINED OVER THE AREA WITH DEEP SUBTROPICAL MOISTURE CONTINUING FLOW INTO COLORADO FROM THE SOUTH. BY LATE AFTERNOON OF THE 11th A WEAK UPPER LEVEL DISTURBANCE MOVED INTO THE DENVER METRO AREA AND STALLED NEAR ERIE. HEAVY RAIN BANDS ASSOCIATED WITH THIS DISTURBANCE PRODUCED VERY HEAVY RAIN AND FLASH FLOODING ACROSS THE FOOTHILLS FROM NORTHERN JEFFERSON COUNTY TO THE WYOMING BORDER EASTWARD INTO THE ADJACENT PLAINS OF LARIMER, BOULDER AND SOUTHWESTERN WELD COUNTIES AS WELL AS PARTS OF AURORA WERE HARDEST HIT WITH 5 TO 9 INCHES OF RAINFALL RECORDED FROM LATE AFTERNOON ON THE 11th THROUGH THE MORNING OF THE 12th. ON THE 12th VERY COOL TEMPERATURES ALONG WITH AREAS OF HEAVY RAIN CONTINUED WITH AN ADDITIONAL 2 TO 6 INCHES OF RAIN ACROSS THE FOOTHILLS AND EASTERN SECTIONS OF DENVER. FLOODING BECAME MORE SEVERE AND WIDESPREAD DURING THE EVENING OF THE 12th AS THE RAIN CONTINUED WITH MANY ROADS CLOSED. RAIN DECREASED ON THE 13th , HOWEVER THE FLOOD WATERS SPREAD INTO THE PLAINS OF LARIMER AND WELD COUNTIES. MORE HEAVY RAIN DEVELOPED ACROSS METRO DENVER ON THE 14th WITH UP TO THREE INCHES OF RAIN MEASURED IN PARTS OF AURORA WITH SOME FLOODING REPORTED. ON THE 15th A WEAK COLD FRONT MOVED INTO THE REGION BRINGING VERY COOL TEMPERATURES AND MORE HEAVY RAIN TO THE AREA. ONE TO THREE INCHES OF RAIN WAS MEASURED IN MANY AREAS WITH FLOODING REPORTED FROM THE NORTHERN SUBURBS OF DENVER NORTH INTO BROOMFIELD AND SOUTHWESTERN WELD COUNTY. TOTAL RAINFALL FROM THIS EVENT RANGED FROM UNDER THREE INCHES NEAR DOWNTOWN DENVER TO OVER 17 INCHES AROUND BOULDER AND PARTS OF AURORA. WARMER AND DRIER WEATHER RETURNED TO THE FRONT RANGE OF COLORADO ON THE 16th AND

CONTINUED THROUGH THE 21st AS A DRIER SOUTHWESTERLY FLOW ALOFT DEVELOPED OVER THE REGION. UPPER LEVEL STORM SYSTEMS BROUGHT ADDITIONAL RAINFALL TO DENVER ON THE 22nd, 23rd AND THE 27th WITH THE COLD FRONT ON THE 27th BRINGING FALL LIKE TEMPERATURES TO NORTH CENTRAL AND NORTHEASTERN COLORADO. MILD AND DRY WEATHER RETURNED TO DENVER THE LAST FEW DAYS OF THE MONTH AS UPPER LEVEL HIGH PRESSURE BUILT OVER THE ROCKY MOUNTAIN REGION. SEPTEMBER 2013 ENDED 3.0 DEGREES ABOVE AVERAGE IN TEMPERATURE AND 4.65 INCHES ABOVE AVERAGE IN PRECIPITATION. OCTOBER 2013 ZONAL FLOW DOMINATED MUCH OF THE WEATHER PATTERN DURING THE BEGINNING OF THE MONTH WITH HIGH TEMPERATURES IN THE MID 70S FOR THE FIRST FEW DAYS. AROUND THE 3rd OF THE MONTH A LOW PRESSURE SYSTEM DROPPED DOWN FROM CANADA AND THE NORTHWESTERN UNITED STATES BRINGING MUCH COOLER AIR DOWN INTO COLORADO. A FRONT MOVED THROUGH THE STATE DROPPING SNOW OVER THE MOUNTAINS AND MUCH OF THE FOOTHILLS AND METRO AREA. MANY PLACES RECEIVED THEIR FIRST MEASURABLE SNOW OF THE SEASON ON THIS DAY. AS THAT LOW PRESSURE SYSTEM MOVED NORTHEAST OUT OF THE AREA IT WAS REPLACED BY EXTENSIVE RIDGING THAT WAS THE CAUSE OF A DEEPLY ROOTED HIGH PRESSURE SYSTEM OVER MUCH OF THE SOUTHWEST AND PACIFIC REGION. THIS STAYED IN PLACE FOR THE NEXT FEW DAYS BRINGING HIGH TEMPERATURES BACK INTO THE UPPER 70S FOR MUCH OF THE STATE. AROUND THE 10th OF THE MONTH ANOTHER LOW PRESSURE SYSTEM DROPPED DOWN FROM THE NORTHWEST INTO PORTIONS OF SOUTHERN NEVADA AND THE DESERT SOUTHWEST. AS THE SYSTEM MADE A SHARP TURN INTO THE COLORADO REGION IT BROUGHT COOLER TEMPERATURES AND PRECIPITATION. AS THE SYSTEM EXITED IT WAS REPLACED BY A MORE ZONAL PATTERN WITH A SURFACE HIGH PRESSURE THAT KEPT TEMPERATURES IN THE UPPER 60S. AN UPPER LEVEL TROUGH AND SURFACE FRONT MOVED IN ON THE 14th DROPPING THE TEMPERATURE 15 DEGREES AND A TENTH OF AN INCH AT THE AIRPORT. THE SURFACE LOW STAYED AROUND FOR A FEW DAYS AS THE UPPER LEVEL LOW CENTERED ITSELF OVER THE CENTRAL UNITED STATES DROPPING THE TEMPERATURE ANOTHER 10 DEGREES FOR A HIGH OF 43 ON THE 15th. OVER THE NEXT FEW DAYS A COLD CORE HIGH SET-UP FORMED WITH A TROUGH IN THE UPPER LEVELS AND A SURFACE HIGH PRESSURE OVER THE REGION BRINGING DRY CONDITIONS AND COOLER TEMPERATURES FOR THE NEXT FEW DAYS. ON THE 18th A COLD FRONT DROPPED DOWN FROM WITH A SURFACE TROUGH OVER SOUTHEASTERN PORTIONS OF THE STATE BRINGING TEMPERATURES DOWN TO THE LOWER 40S AND OUR SECOND DOSE OF MEASURABLE SNOW TO DENVER. DENVER INTERNATIONAL AIRPORT REPORTED 1.4 INCHES OF SNOW DURING THIS TIME. NORTHWEST FLOW DOMINATED OVER THE NEXT FEW DAYS KEEPING TEMPERATURES IN THE MID TO UPPER 50S AND LOWER 60S. A HIGH PRESSURE SYSTEM STARTED TO BUILD IN OVER THE WEST COAST AROUND THE 20th OF THE MONTH BRINGING WARMER TEMPERATURES AND DRY CONDITIONS TO OUR REGION WITH TEMPERATURES ONCE AGAIN REACHING INTO THE LOWER 70S. THIS PATTERN PERSISTED UNTIL THE 27th WHEN A LOW FROM THE PACIFIC MOVED EASTWARD OVER EASTERN NEVADA AND A SURFACE COLD FRONT DROPPED DOWN INTO COLORADO BRINGING A TRACE OF SNOW TO THE AIRPORT AND BELOW NORMAL TEMPERATURES. OVER THE NEXT FEW DAYS OF THE MONTH IT CONTINUED TO TRACK TO THE NORTHWEST BRINGING COOL AND CLOUDY CONDITIONS. INCREASED MOISTURE AND DROPPING TEMPERATURES ALSO BROUGHT HEAVY FOG TO THE AREA

AND HIGH WINDS ON HALLOWEEN INTO THE EVENING AS THE SYSTEM EXITED. OCTOBER 2013 ENDED 3.2 DEGREES BELOW AVERAGE IN TEMPERATURE AND 0.30 INCHES BELOW AVERAGE IN PRECIPITATION. NOVEMBER 2013 WAS AN UNEVENTFUL MONTH FOR WEATHER WITH ABOVE NORMAL TEMPERATURES AND BELOW NORMAL PRECIPITATION. TWENTY TWO OUT THE THIRTY DAYS IN THE MONTH HAD ABOVE NORMAL TEMPERATURES WITH ONLY ONE DAY HAVING MEASURABLE SNOWFALL. NOVEMBER 2013 ENDED 2.6 DEGREES ABOVE AVERAGE IN TEMPERATURE AND 0.34 INCH BELOW AVERAGE IN PRECIPITATION. DECEMBER 2013 STARTED OUT MILD AND DRY AS A WESTERLY TO NORTHWESTERLY FLOW ALOFT PRODUCED DOWNSLOPE FLOW ALONG THE LEE OF THE ROCKIES. THE HIGH TEMPERATURE DURING THE FIRST THREE DAYS OF THE MONTH AVERAGED 13.0 DEGREES ABOVE NORMAL. THE MILD AND DRY WEATHER CAME TO AN ABRUPT END AS A DEEP UPPER LEVEL TROUGH OF LOW PRESSURE ORIGINATING IN ALASKA DROPPED INTO THE WESTERN U.S. AN ARCTIC AIRMASS ASSOCIATED WITH THIS TROUGH SWEPT ACROSS NORTHEASTERN COLORADO AROUND MIDDAY ON THE 3rd

BRINGING SNOW ON MUCH COLDER TEMPERATURES TO THE FRONT RANGE OF COLORADO. THIS ARCTIC BLAST WOULD LEAVE NORTHEASTERN COLORADO IN THE DEEP FREEZE FOR SEVERAL DAYS. FROM THE 4th THROUGH THE 8th HIGH TEMPERATURES DID NOT RISE ABOVE THE TEENS WITH MAX TEMPERATURES FROM THE 5th THROUGH THE 7th ONLY IN THE SINGLE DIGITS. DURING THE COLD SNAP DENVER EXPERIENCED A SIX CONSECUTIVE DAY STRETCH (DECEMBER 4th – 9th) WITH LOW TEMPERATURES BELOW ZERO. DECEMBER OF 1972 STILL HOLDS THE RECORD OF 11 CONSECUTIVE DAYS OF MINIMUM TEMPERATURES BELOW ZERO. ON THE 9th THE COLD AIR BEGAN TO LOSE ITS GRIP ON COLORADO AS THE LARGE UPPER LOW MOVED INTO THE CENTRAL UNITED STATES. ON THE 10th THE HIGH TEMPERATURE IN DENVER FINALLY MADE IT ABOVE FREEZING. ABOVE NORMAL TEMPERATURES RETURNED TO DENVER FROM THE 12th THROUGH THE 14th. MUCH ABOVE NORMAL TEMPERATURES OCCURRED FROM THE 15th THROUGH THE 18th AS UPPER LEVEL HIGH PRESSURE DOMINATED THE WESTERN U.S AND DRY NORTHWEST FLOW ALOFT PRODUCED A WARM DOWNSLOPE FLOW ALONG THE LEE OF THE ROCKIES. AVERAGE TEMPERATURES DURING THIS FOUR DAY PERIOD AVERAGED NEARLY EIGHTEEN DEGREES ABOVE NORMAL. THE 68 DEGREES ON THE 18th SET A NEW RECORD FOR THE DATE AND WAS THE WARMEST DAY OF THE MONTH. ANOTHER UPPER LEVEL STORM SYSTEM AND ASSOCIATED COLD FRONT BROUGHT LIGHT SNOW AND COLDER TEMPERATURES TO DENVER FROM THE 19th THROUGH THE 23rd. TEMPERATURES REBOUNDED TO ABOVE NORMAL VALUES ON THE 24th, HOWEVER A COLD FRONT MOVED INTO DENVER AROUND MIDDAY BRINGING COLDER TEMPERATURES AND A FEW FLURRIES. DENVER EXPERIENCED DRY WEATHER AND NEAR NORMAL TEMPERATURES ON CHRISTMAS DAY. A WARMING TREND BEGAN ON THE 26th AND CONTINUED THROUGH THE 28th AS UPPER LEVEL HIGH PRESSURE REBUILT OVER THE ROCKY MOUNTAIN REGION. ANOTHER SURGE OF COLD AIR BROUGHT COLDER TEMPERATURES AND LIGHT SNOW TO DENVER LATE ON THE 28th THROUGH THE 29th. THE MONTH ENDED ON A MILD AND DRY NOTE. This information can be accessed at the NWS Boulder Climate page: http://www.nws.noaa.gov/climate/index.php?wfo=bou

Here are a couple pictures of the flooding that occurred in Boulder County, all images courtesy of Helen Richardson, Denver Post:

Below is the 2013 Climate Summary for Denver (DIA).

Drought Update

Drought persists over the majority of the western states with relatively drought free conditions over the eastern half of the US.

The map below shows forecasted temperature deviances for January 2014. Above normal temperatures are expected over southern CO with near normal temperatures over northeast CO.

The map below shows forecasted precipitation deviances for January 2014. Normal precipitation is forecast over Colorado with above normal precipitation over the northern Rockies.

Drought conditions are forecast to persist over southeast Colorado with areas of drought re-developing over portions of W and SW Colorado.

December Summary

December of 2014 produced a mixed bag of weather along the Front Range. Very cold temperatures during the early part of the month gave way to a warm spell during the 2nd and 3rd weeks with seesawing temperatures towards month’s end. Overall, high temperatures ended up near normal at 42.9 degrees with average lows about 3 degrees below normal. Combining the high and low temperatures resulted in a monthly mean temperature of 1.6 degrees below normal The warmest day was on the 18th and the coldest day was on the 5th with a low of -15. There were 2 low temperature records tied or broken with one new record high on the 18th. Precipitation once again came in below normal for December with only 0.25” reported at DIA, 0.10” lower than the average of 0.35”. With the lack of moisture snowfall was also well below the normal of 8.5” with 4.7” of snow measured at DIA. For the year now the snow deficit has reached 14.4” below normal with only 8.5” measured by the end of December. The winter is actually starting out a bit like last year with below normal snow through December. If you remember the February through April time frame is when most of the snow fell and that will be likely again this year.

December Stats

TEMPERATURE (IN DEGREES F)

AVERAGE MAX 42.9 NORMAL 42.8 DEPARTURE 0.1

AVERAGE MIN 14.0 NORMAL 17.1 DEPARTURE -3.1

MONTHLY MEAN 28.4 NORMAL 30.0 DEPARTURE -1.6

HIGHEST 68 on the 18th

LOWEST -15 on the 5th

DAYS WITH MAX 90 OR ABOVE 0 NORMAL 0

DAYS WITH MAX 32 OR BELOW 8 NORMAL 6

DAYS WITH MIN 32 OR BELOW 29 NORMAL 29

DAYS WITH MIN ZERO OR BELOW 6 NORMAL 2

TEMPERATURE RECORDS

New record low of -13 on the 4th. Tied record low of -15 on the 5th.

New record high of 66 on the 18th. Record high min of 40 on the 18th .

HEATING DEGREE DAYS

MONTHLY TOTAL 1128 NORMAL 1086 DEPARTURE 42

SEASONAL TOTAL 2451 NORMAL 2434 DEPARTURE -17

COOLING DEGREE DAYS

MONTHLY TOTAL 0 NORMAL 0 DEPARTURE 0

YEARLY TOTAL 999 NORMAL 769 DEPARTURE 230

PRECIPITATION (IN INCHES)

MONTHLY TOTAL 0.25 NORMAL 0.35 DEPARTURE -0.10

YEARLY TOTAL 17.60 NORMAL 14.30 DEPARTURE 3.30

GREATEST IN 24 HOURS 0.11” on 12/4

DAYS WITH MEASURABLE PRECIP. 7

SNOWFALL (IN INCHES)

MONTHLY TOTAL 4.7 NORMAL 8.5 DEPARTURE -3.8

SEASONAL TOTAL 8.1 NORMAL 22.5 DEPARTURE -14.4

GREATEST IN 24 HOURS 2.8” on the 4th

GREATEST DEPTH 2” on the 5th

WIND (IN MILES PER HOUR)

AVERAGE SPEED 9.3mph

PEAK WIND GUST 42mph from the W on 12/15

MISCELLANEOUS WEATHER

NUMBER OF DAYS WITH THUNDERSTORM 0 NORMAL 0

NUMBER OF DAYS WITH HEAVY FOG 2 NORMAL 1

NUMBER OF DAYS WITH HAIL 0

NUMBER OF SUNNY DAYS Na

NUMBER OF PARTLY CLOUDY DAYS Na

NUMBER OF CLOUDY DAYS 4na

AVERAGE RELATIVE HUMIDITY 50%

January Preview

January is the second coldest month of the year on average just slightly warmer than December with a mean temperature of 30.7 degrees. High temperatures on average are 43 degrees to start the month and 44 to end the month. Average low temperatures are 17-18 degrees. As we all know “normal” does not frequently occur along the I-25 corridor with generally higher or lower temperatures on any given day. January is the time of year where arctic air masses can make frequent visits with high temperatures below freezing and nighttime lows sub zero. The coldest temperature ever recorded in Denver was on January 9, 1875 with a low of -29 degrees. The record high is 76 degrees set back on January 27, 1888. The record high and record low combine to create a temperature spread of 105 degrees! Snowfall in January is usually dry and powdery with low water content that can typically be swept away with a broom. There are around 2-4 snow events on average producing 7.0” of snow and 0.41” of moisture. Only two storms on average produce 1” or more of snow. With 6.0” of snow already reported at DIA this month through the 7th it will not take much additional snow to reach normal and most likely many areas will end up with above normal snowfall for the first time this snow season. Temperatures are predicted to be near normal over NE Colorado with above normal temperatures for SE Colorado.

DENVER'S JANUARY CLIMATOLOGICALLY NORMAL (NORMAL PERIOD 1981-2010 DIA Data)

TEMPERATURE

AVERAGE HIGH 44.0 AVERAGE LOW 17.4 MONTHLY MEAN 30.7 DAYS WITH HIGH 90 OR ABOVE 0 DAYS WITH HIGH 32 OR BELOW 6 DAYS WITH LOW 32 OR BELOW 29 DAYS WITH LOWS ZERO OR BELOW 2

PRECIPITATION

MONTHLY MEAN 0.41”

DAYS WITH MEASURABLE PRECIPITATION 4 AVERAGE SNOWFALL IN INCHES 7.0” DAYS WITH 1.0 INCH OF SNOW OR MORE 2

MISCELLANEOUS AVERAGES

HEATING DEGREE DAYS 1063 COOLING DEGREE DAYS 0 WIND SPEED (MPH) 8.6mph WIND DIRECTION South DAYS WITH THUNDERSTORMS 0 DAYS WITH DENSE FOG 1 PERCENT OF SUNSHINE POSSIBLE 71%

EXTREMES

RECORD HIGH 76 on 1/27/1888 RECORD LOW -29 on 1/9/1875 WARMEST 40.3 in 1986 COLDEST 16.9 in 1930 WETTEST 2.35” in 1883 DRIEST 0.01” in 1933 SNOWIEST 24.3” in 1992 LEAST SNOWIEST TR in 1934, 2003

Sunrise/Sunset (July - December Denver area)

Snowfall

October 2013 to April 2014

City Oct Nov Dec Jan Feb Mar Apr Total

Aurora (Central) 3.5 3.0 5.4 11.9

Brighton 2.0 2.4 4.5 8.9

Broomfield 3.9 3.1 4.5 11.5

Castle Rock 3.7 1.9 8.3 13.9

Colo Sprgs Airport TR 3.9 2.9 6.8

Denver DIA 1.4 2.0 4.7 8.1

Denver Downtown 1.7 2.1 5.4 9.2

Golden 3.6 3.2 10.4 17.2

Fort Collins 4.1 3.0 6.3 13.4

Highlands Ranch 3.5 3.3 10.1 16.9

Lakewood 2.1 2.0 7.0 11.1

Littleton 2.5 2.2 7.9 12.6

Parker 3.2 2.7 6.4 12.3

Sedalia - Hwy 67 4.0 2.6 9.7 16.3

Thornton 2.9 2.7 6.9 12.5

Westminster 3.3 3.0 5.9 12.2

Wheat Ridge 3.0 2.3 9.2 14.5

Skyview Weather 2350 N Rocky View Rd Castle Rock, CO 80108 Phone: (303) 688-9175 Fax: (303) 380-3338 E-mail: Tim@SkyviewWeather.com On the web at www.SkyviewWeather.com

Copyright 2014 Skyview Weather