Traveling

I'm traveling for a couple weeks so posting will be light o rmaybe none, depending on connectivity issues.

First Big Lightning Day

The thunder season has gotten off to an early, but otherwise slow start. Up until Tuesday, there had not yet been a day with even 100 strikes state-wide. That changed big-time Tuesday as a strong trough aloft touched off more than 700 strikes, most of them in an arc from Old Crow, YT southwest to the Nulato Hills. The trough passed through Fairbanks-land mid-AM, too early to touch off thunder. There were very few early afternoon in the uplands north of the Steese Highway. This is the latest date for the first 100 strike day since 2001.

High Water Follow-up

Here's an update on the high water over the holiday weekend. At the left are Monday morning hydrographs for the upper Chena and lower Salcha Rivers. The peak stage Saturday on the Salcha was the highest stage in four years, and on the Chena the highest since 2003. The Chena at Fairbanks crested Sunday at 6.4 feet, which is notable mostly in that it's a five foot rise since last week.

It's a Soaker

 May only rarely brings soaking stratiform rains that send Interior Rivers out of their banks, but this is one of them. Here is the Saturday morning hydrograph from the Chena River near the Mile 40 Bridge. In addition to much more rain than anticipated, this rain also accelerated high elevation snowmelt. At the Munson Ridge SNOTEL, at 3100' MSL south of Chena Hot Springs, there was still a snow depth of four inches being reported Friday morning, which is now down to one inch, which is at the noise level. Fairbanks Airport set a new precipitation record Friday with 0.52 inches of rain.

Other rain amounts in the area include
Salcha River RAWS: 1.23 inches
Mile 40 Chena Hot Springs Road: 0.99 inches
Birch Lake RWIS: 0.94 inches
Woodsmoke near North Pole: 0.77 inches
Fort Knox Mine: 0.70 inches
Keystone Ridge: 0.68 inches
Aurora: 0.62 inches
Fairbanks Mid-town: 0.59 inches

Summer Rains

It's a sure sign on summer when I start posting hydrographs. Here is the plot of observed and forecast stages on the Salcha River at the Richardson Highway bridge. Water levels have been rising in response to showers the last few days, and will rise more with the steady rains today. Since late Thursday evening, rainfall amounts of a quarter to one inch of rain has been common, with the highest amounts east of Fairbanks and the lowest west of town.

Rain

After two weeks of sprinkles, most parts of Fairbanks-land received measurable rain Wednesday from showers. However, as expected in showery precipitation, amounts were highly variable. Photo from Thursday morning looking south from UAF West Ridge, courtsey of the Alaska Climate Research Center

Rainfall Wednesday included:

Keystone Ridge: 0.28 inches
UAF West Ridge: 0.20 inches
Fort Knox Mine: 0.17 inches
Goldstream Creek: 0.15 inches
Fairbanks Airport: 0.04 inches
East Farmers Loop: 0.02 inches
Aurora: 0.02 inches
Eielson AFB: 0.01 inches
North Pole: Trace

First 70 in Fairbanks

Fairbanks Airport made 70F today for the first time this year. This is exactly the average date (1930-2011) for the first 70º temperature.

Winter Hangs on

Temperatures are warming up across northern Alaska and snow cover is starting to go at low elevations even on the North Slope and Bering and Chukchi Sea coasts. Not so much yet though at higher elevations in of the Brooks Range. The photo at the right taken Sunday morning is from Ivotuk, southwest of Umiat at about 2000 feet elevation.

Warming Up

Temperatures so far this this month have been significantly below normal, as the updated standardized daily temperature anomaly chart at the left shows. Through Wednesday, the high temperature at the Fairbanks Airport for the spring has been 61º on April 16th and again on May 12th. However, that's set to change as the first really warm weather of the season is in the cards, as high pressure aloft builds and has already put an end to the daily convection. Over the past 80 years the mean date for the first 70º temperature in Fairbanks is May 21st, and this year will be very close to that date. 

Cool May Morn

Temperatures fell overnight as skies cleared and the airmass remains on the cool side. Low temperatures Monday morning were near or below freezing in much of Fairbanks-land, including

Updated...
Goldstream Creek: 22F
Eielson AFB: 28F
UAF West Ridge: 28F
Fort Wainwright: 30F
Fairbanks Airport: 30F
Keystone Ridge: 32F
Cleary Summit: 35F
 (Photo Monday morning courtesy of the Alaska Climate Research Center)

The snowpack is getting pretty dirty at Barrow, as this late morning photo  from the UAF Sea Ice groups shows. it's been a cool spring in Barrow, with the temperature the first nine days of May averaging 8 degrees below normal. On the bright side, Barrow had their last sunset of for the summer last night at 12:59am. The next time the sun goes below the horizon at Barrow will be at August first at 220am

Thunder in Fairbanks

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE FAIRBANKS AK
706 PM AKDT SAT MAY 5 2012
 ...THUNDER AT FAIRBANKS AIRPORT...
...EARLIEST IN 28 YEARS...

A 20 MINUTE THUNDERSTORM AT THE FAIRBANKS AIRPORT EARLY SATURDAY EVENING WAS THE EARLIEST THUNDERSTORM OF THE SEASON SINCE 1984...WHEN THERE WAS A THUNDERSTORM ON MAY 3RD. THUNDER IN THE FIRST HALF OF MAY IS NOT UNCOMMON OVER THE HILLS NORTH AND EAST TOWN...BUT IS QUITE UNUSUAL TO OCCUR SO EARLY IN THE SEASON IN THE FAIRBANKS BOWL. REPORTS OF UP TO ONE TENTH OF AN INCH OF RAIN AND SMALL HAIL HAVE BEEN RECEIVED FROM AREAS ON THE EAST SIDE OF TOWN. $$ RT MAY 2012

(Photo from the FAA's Ester Dome webcam looking southeast at 554pm ADT Saturday)

Chilly on the North Slope...but...

Low temperatures Saturday morning on the North Slope were nearly or a bit below zero, including zero at Barrow, 2 below at Kaktovik and 8 below at Anaktuvuk.

How unusual is this? Not at all. Over the past 50 years, the average date of the last zero temperature in the spring at Barrow is May 3rd.

Webcam photo looking northeast from the Barrow Airport, courtesy of the FAA.

Precip Type in Dry Air

Friday afternoon and evening brought convective showers to Fairbanks-land. However, with a dry and still cool-ish airmass in place, the form of the (light) precipitation that did occur was perhaps not as might be expected. There were a few reports of light rain in the Fairbanks bowl. However, snow was reported near the Chatanika River on the Elliott Highway, below 800 feet elevation. Here on Keystone ridge, it snowed between 330pm and 4pm, with temperatures no lower than 38F. Unsurprisingly, light snow was also reported on Wickersham Dome, elevation 2600 feet.

The graphic shows a plot of the 00Z May 05 Fairbanks upper sounding (heights are in geopotential meters: for practical purposes, just think of the y-axis as in meters). The freezing level was over 3000 feet above the ground. However, the elevation of the "wet-bulb zero" (the elevation that if you saturate the air the temperature would be at freezing) was only 1400 feet above the ground. In at least some of the precipitation shafts, the air was not saturated, allowing snow to fall perhaps as much as 2500 feet below the nominal freezing level.

Spring in the Brooks Range

Noontime Friday photo from Chandalar DOT Mile 239 on the Dalton Highway at 3000' elevation , courtesy of the FAA. With high temperatures below freezing, snowmelt has a long ways to go in the central Brooks Range.

Here's an update of the 2012 standardized temperature anomaly chart for here on Keystone Ridge. The mean temperature Wednesday of 21F was 2.5 standard deviations below normal, the most for any single day since the coldsnap before Thanksgiving. On Tuesday, Fairbanks Airport set a new record low max temperature of 32F.

It's a cold May morning in Interior Alaska, with most places having low temperatures in the teens and lower 20s. Here on Keystone Ridge the low 11F is the lowest temperature in 16 years of record here and probably the lowest May temperature since 1992. Other lows include: 15F at Goldstream Creek, 19F at UAF West Ridge, 19F Mile 43 Steese Highway, 21F at Fairbanks Airport and 22F at Fort Wainwright. Webcam photo from Bettles Tuesday morning, courtesy of the FAA

More on April

As Corey noted in the April summary, this was 13th warmest April of record. This was mostly due to the persistence mild weather, with the warmth mid-month being the only really outstanding daily anomaly. Here's a plot of daily high temperatures in April, normals and the daily departure from normal. From the 18th through the 29th there was hardly any daily to day change in the actual high temperature. However, because normals are rising steadily, overall the departure from normal lowered with time.

And below is a plot of the mean April temperatures in Fairbanks over the past century. The linear regression for the full period 1905-2012 (not plotted) shows an increase of about 5 degrees AND is statistically significant. However, nearly all of that trend has come since the PDO shift in 1976. There is no significant trend from 1905 to 1976.

April Summary

PUBLIC INFORMATION STATEMENT NATIONAL WEATHER SERVICE FAIRBANKS AK 451 AM AKDT TUE MAY 1 2012 ...APRIL WEATHER SUMMARY FOR FAIRBANKS... ...MILD AND DRY... FOLLOWING A COLD MARCH...APRIL CONTINUED THE TREND OF THE LAST 6 MONTHS OF ALTERNATING COLD AND WARM MONTHS AND WENT INTO THE RECORD BOOKS WITH WELL ABOVE NORMAL TEMPERATURES. THE AVERAGE TEMPERATURE OF 36.9 DEGREES WAS 4.4 DEGREES ABOVE NORMAL. IT ENDED UP AS THE 13TH WARMEST APRIL ON RECORD AT FAIRBANKS. THIS CONTINUED A RECENT TREND OF WARM APRILS. SIX OF THE WARMEST 10 APRILS HAVE BEEN OBSERVED SINCE 1990. FOR THE MONTH...THE AVERAGE HIGH TEMPERATURE AT THE AIRPORT WAS 50 AND THE AVERAGE LOW WAS 24. THE HIGH TEMPERATURE FOR THE MONTH OF 61 DEGREES WAS OBSERVED ON THE 16TH AND THE LOW FOR THE MONTH OF 8 BELOW OCCURRED ON THE MORNING OF THE 4TH. TWENTY-SIX OUT OF 30 DAYS THIS PAST APRIL HAD TEMPERATURES THAT WERE ABOVE NORMAL...WITH THE ONLY COLDER THAN NORMAL WEATHER FROM APRIL 2ND TO 4TH AND ON THE 30TH. THE WARMEST TEMPERATURE DEPARTURES FROM NORMAL OCCURRED AROUND MID MONTH...AND ON THE 16TH THE HIGH OF 61 DEGREES ESTABLISHED A NEW RECORD HIGH FOR THE DATE SURPASSING THE OLD RECORD OF 59 SET IN 1993. IT WAS ALSO THE EARLIEST 60 DEGREE TEMPERATURE AT THE AIRPORT SINCE 1997. THERE WERE 19 DAYS WITH A HIGH TEMPERATURE OF 50 DEGREES OR WARMER...WHICH WAS WELL ABOVE THE AVERAGE OF 11 DAYS. THE PERSISTENTLY MILD WEATHER COMBINED WITH PLENTY OF SUNSHINE TO MELT OUT THE SNOW PACK QUITE RAPIDLY. THERE WAS 20 INCHES OF SNOW ON THE GROUND ON THE MORNING OF THE 9TH THAT ALL MELTED AWAY BY THE 20TH. THE LAST DAY WITH AN INCH OR MORE OF SNOW ON THE GROUND WAS THE 19TH...WHICH WAS JUST 3 DAYS SHY OF THE AVERAGE DATE FOR THE LOSS OF THE WINTER SNOW PACK...WHICH IS APRIL 22ND. THERE WAS AN INCH OR MORE OF SNOW ON THE GROUND FOR A TOTAL OF 184 DAYS THIS WINTER...WHICH WAS ONLY 2 DAYS SHY OF THE LONG TERM AVERAGE. THIS PAST APRIL WAS DRY WITH ONLY 7 HUNDREDTHS OF AN INCH OF RAIN WHICH INCLUDED A TRACE OF SNOW AT THE AIRPORT. THE 7 HUNDREDTHS OF AN INCH OF RAIN WAS NEARLY A QUARTER INCH BELOW NORMAL...BUT DID NOT RANK AS ONE OF THE DRIEST APRILS ON RECORD. THERE HAVE BEEN MORE THAN 20 APRILS OVER THE YEARS WITH 5 HUNDREDTHS OF AN INCH OF LESS OF RAIN (AND MELTED SNOW). THE LACK OF PRECIPITATION WAS NOT LIMITED TO THE VALLEY AS MOST HIGH ELEVATION SITES AROUND FAIRBANKS ONLY HAD AROUND AN INCH OF SNOW THIS PAST APRIL. HIGHER ELEVATION SITES STILL HAD SIGNIFICANT SNOW ON THE GROUND AT MONTHS END...WITH 8 INCHES AT KEYSTONE RIDGE ON MURPHY DOME...AND 22 INCHES AT MUNSON RIDGE SOUTH OF CHENA HOT SPRINGS AT AN ELEVATION OF 3100 FEET. LOOKING AHEAD TO MAY...NORMAL HIGH TEMPERATURES RISE FROM 54 DEGREES ON THE FIRST TO 67 DEGREES ON THE 31ST. NORMAL LOW TEMPERATURES RISE FROM 31 ON THE 1ST TO 44 ON THE 31ST. MAY TENDS TO BE A FAIRLY DRY MONTH WITH THE LIKELIHOOD OF SHOWERS TYPICALLY INCREASING LATE IN THE MONTH. ON AVERAGE ONLY 6 TENTHS OF AN INCH OF RAIN IS OBSERVED. MOST YEARS THERE IS LITTLE OR NO SNOWFALL IN TOWN DURING THE MONTH OF MAY...BUT TWICE IN THE LAST 30 YEARS THERE HAS BEEN MORE THAN 6 INCHES OF SNOW...MOST MEMORABLE FOR LONG TIME RESIDENTS IN 1992 WHEN THERE WAS 14.1 INCHES OF SNOW. HIGHER ELEVATION SNOW ON THE HILLS AROUND FAIRBANKS IS NOT ALL THAT UNUSUAL IN MAY ABOVE 1500 FEET...ESPECIALLY DURING THE FIRST HALF OF THE MONTH. THE LAST FREEZING TEMPERATURES OF THE SPRING ON AVERAGE ARE OBSERVED AT THE AIRPORT AROUND MID-MONTH...BUT RURAL VALLEYS WILL TYPICALLY HAVE FROST ON CLEAR NIGHTS EVEN LATE IN THE MONTH. POSSIBLE SUNSHINE INCREASES FROM JUST OVER 17 HOURS ON THE 1ST TO 20 HOURS AND 29 MINUTES ON THE 31ST. SOME TWILIGHT IS VISIBLE ALONG THE NORTHERN HORIZON AT THE START OF THE MONTH...AND BY MID- MONTH THERE IS 24 HOURS OF USABLE DAYLIGHT. THE FORECAST FOR MAY FROM THE CLIMATE PREDICATION CENTER INDICATES THAT THERE ARE NO STRONG CLIMATE SIGNALS THAT WOULD INDICATE AN INCREASED CHANCE OF EITHER SIGNIFICANTLY ABOVE OR BELOW NORMAL TEMPERATURES OR PRECIPITATION. ...MONTHLY WEATHER SUMMARY FOR FAIRBANKS ALASKA... OBSERVED LAST MONTH...04/2012 OBSERVED RANK AVG MAX TEMP (F) 49.7 9TH WARMEST OF 107 YEARS AVG MIN TEMP (F) 24.1 22ND WARMEST OF 108 YEARS AVG TEMP (F) 36.9 13TH WARMEST OF 107 YEARS TOTAL PRECIP (IN) 0.07 26TH DRIEST OF 99 YEARS TOTAL SNOW (IN) T 81ST SNOWIEST OF 97 YEARS $$ CB/RT