Warmest Week of record in Fairbanks

Updated for new record: 
The week ending June 30th is the warmest week of record in Fairbanks. Here are are the top five non-overlapping weeks:

1. 75.2ºF June 24-30, 2013
2. 74.7ºF June 20-26, 1991
3. 73.5ºF July 5-11, 1975
4. 73.0ºF June 30-July 6, 1990
5. 72.7ºF June 30-July 6, 1986

Here's the NCAR/NCEP reanalysis of 500 mb heights since Solstice. It's a classic pattern for hot summer weather in Interior Alaska, with the high centered west of Great Slave Lake and ridge extending west into Alaska.

Warmest Five Days of Record in Fairbanks

For the first time ever, Fairbanks recorded five consecutive days with minimum temperatures of 65ºF or higher (June 24-28). As a result, the five day running mean temperature for this period, 77.1ºF is the highest 5-day mean temperature ever recorded in Fairbanks.

Here's a plot of the daily temperature (and 1981-2010 normals) so far this year:

Here's the daily and 5-day standardized anomalies:

So, the current hot weather is as "anomalous" as the cold weather in the spring, having now exceeded three standard deviations from the 1981-2010 normal, though the duration is not as long (thus far).

Warmest Day in the Modern Era in Fairbanks

For the first time in modern history, Fairbanks recorded a low temperature in 70s. The low Tuesday of 70ºF. The only other occurrence of a low in the 70s was on June 26, 1915. There was a thunderstorm that day that produced more than one tenth of an inch of rain, so this observation is, to say the least, questionable. 

The high Tuesday of 92ºF tied the record high for the date. The daily mean on 81ºF is the highest reliable daily mean at Fairbanks of record, exceeding the previous record of 80ºF (high 94, low 66) on July 11, 1975.

Near Record Warm Low at Farbanks

The low temperature Monday at the Fairbanks Airport was just 66ºF, thanks to a persistent breeze overnight. This is one of the warmest daily low temperatures of record for Fairbanks. The warmest WB/NWS era daily minimum temperature is 67ºF set in several days in July 1975 and again in June 1991.  The "record" of 76ºF in June 1915 is virtually certain to be in error, as there was a shower that produced more than a tenth of an inch of rain the same day.

Also, I'm back. An eventful couple of weeks I'll try to recap as time allows.

North Slope Heatwave

Temperatures soared into the 60s and 70s on the North Slope Thursday. The high of 66ºF at Barrow was one degree from the record high for June 13th. Other  near coastal sites were in the 60s, with Wainwright at 68ºF and Deadhorse at 61ºF. As you would expect, it was even warmer inland. Atqasuk and the Umiat RAWS reported a high of 75ºF and up at Anaktuvuk Pass the high was 72ºF.

Cool June Morning

We're enjoying more than 21 and one half hours of sunshine these days, but temperatures in the usual cool spots dipped to near or just below freezing Tuesday morning. Goldstream Creek and Angel Creek near Chena Hot Springs fell to 31ºF, Gilmore Creek and Mile 42 Steese had 33ºF and the Woodsmoke CWOP reported 35ºF.

I'm on the road the next two weeks so posts likely to be limited.

Really 1 Below Zero at Anaktuvuk Pass in late June?

Reader Richard asked about the veracity of the low temperature of 1 below reported on Jun 25, 1967 at Anaktuvuk Pass, and he expressed considerable doubt that this could be correct. This would be a state and, says Richard, a national record for June.

Here's the situation: Anaktuvuk is at 68.1N 2100' in the Brooks Range; the village is right on the valley floor and within one mile of the continental divide. On general principles,  it seems to me that it is (barely) within the realm of possibility that IF there was a fresh snow cover and IF an unseasonably cold airmass in place AND skies cleared late evening AND winds were light that Anaktuvuk could get this cold in late June (this would be a lot more believable if it was the first few days of June). 

There are historically very few weather observations from this part of the world, and the data quality from the coop observation at Anaktuvuk during this time have more than a few problems.  Here is the scan of the original form for June 1967:

Courtesy of NCDC

There looks to be no doubt that the value written in was -1, and there is no other evidence on this form that there is some confusion with, say, degrees C. Most of the temperatures during this month look plausible, and while there are different writing implements used, it looks to me that the hand writing is all the same person. That fact that most of the temperatures look okay makes it less likely that observer was reading the wrong end of the min temperature index, which would  make lows about 12ºF too low.

If these are really observations taken at 5pm (and differences from the scheduled time of observation are hardly ever recorded by the observer on the form), the data on the 24th looks suspect: was it really 40F at 5pm on the 23rd, fell to 17F the following morning ( itself a remarkably low temperature for so late in June), then rebounded to 60F, only to be back to 35F by 5pm on the 24th? The high temperature of 44F on the 25th looks plausible.  Notice too the remark concerning snow cover on the morning of the 27th, but nothing that would suggest snow on the ground on the morning of the 25th. 

If we look at what was happening on the broader scale, here's the NCEP/NCARR Mean Sea-Level Pressure and 850mb temperature reanalysis for Jun 25, 1967:

Courtesy of NCEP/NCAR

This does not help settle the question. There is a surface ridge across the Brooks Range and 850mb are slightly below freezing (on this rather course scale). Now 850mb temperatures a little below zero are hardly unusual over the Brooks Range in mid-summer. Cooler than normal, for sure, but nothing extra special. Also, as Richard pointed out, there is nothing of note at other northern Alaska locations around this date.

It would be nice to have some explanation of how the -1F got to recorded, but I can't think of any offhand. So, lacking any additional evidence, my vote is: beyond reasonable doubt, the low temperature was not  -1F at Anaktuvuk Pass on June 25, 1967. However, there IS a very slight chance that the all the ingredients came together and that the observation of -1F is correct.

Not Much Thunder Yet

Courtesy of AFS

The Alaska Fire Service as had some issues with the lightning detection network (both under and over reporting strikes), but there is no doubt it's been a slow start to the convective season in Interior Alaska. The plot on the right plots strikes May 25th through Saturday morning. Here on Keystone Ridge, there has been no thunder heard to date. Only once in the past 17 years have we gone past June 9th without any thunder: that was in 1998, when there was no thunder heard here until June 28th. Of course, it is not uncommon for Fairbanks airport to not have reported thunder by June 8th. The fire expansion has slowed with the wetter weather this week. The total acreage burned as of Saturday morning stands at just under 46,000 acres. More than 60% of that total is from the Doestock Creek fire south of Aniak.

Barrow Ice Still in Place

The Barrow ice cam was down for a while over the winter, but it's back and seems like to a good idea to post an image as we head into the melt season. It's not the prettiest day in Barrow, but here's the view Tuesday late afternoon. That's all ice out there.

Courtesy of the UAF Ice Group

Fire Season Takes Off

The cold spring greatly retarded the fire season: as of Friday, May 31 only 665 acres had burned. That changed over the weekend, as the season roared to life: Monday morning Alaska Fire Service was calling 32,600 acres burned. Most of that was in Southwest Alaska, where the Doestock Creek fire, south of Aniak, was over 18000 acres. There were several staff fires southeast of Tok, with the Bitter Creek fire threatening to close the Alaska Highway. Here's the AFS plot of "active fires" from Tuesday early morning, bearing in mind that active means "not declared out" and that many of these are 0.1 acres or less. The lack of fires in the northern Interior reflects the lack of lightning thus far this season.

Oh What a May It Was

Hard to know how to present all the notable events of May 2013, so when in doubt, put up a chart. Here's a plot of the daily mean temperature at Fairbanks in May.

Only six seven days the entire month were within one standard deviation of normal. On to the highlights:
In the Weather Bureau/NWS era (starting 1930)

• 10th coldest May
• Latest date (May 18th) of record with a daily high temperature below 40ºF and daily mean  below freezing
• Three daily record low temperatures and two record low max temperatures
• Winter snowpack melt-out of May 11 is the second latest of record
• 18 days with daily low temperatures of  ≤32ºF is most in May since 1964
• Green-up of West Chena Ridge as seen from UAF on May 26th is latest since observations began in 1974 and probably latest since 1964
• The 47 consecutive days with daily mean temperature below normal appears to be a record for such a streak, though it is not a record for consecutive days with departure of the same sign (53 days in a row in autumn 2002 above normal)
• Lowest April-May of record (mean temperature 31.3ºF)
• Fourth lowest March-April-May of record (mean temperature 23.2ºF)

On the warm side:

• Daily record high of 84ºF tied on the 30th
• Five days with highs in the 80s ties for second greatest such days in May (record is seven days in 2011)
• First time ever in May with five straight days of highs 82ºF or higher (thanks to reader Brian for this one)

The End of the Snowpack

Amazing what sunshine and temperatures in the 60s and 70s (and lows near 50ºF) will do to a snowpack. By Sunday evening the snow pack here on Keystone Ridge, which on Wednesday was still near 100% coverage, was reduced to patches. Of course, with the melting snow and warm temperatures came the first mosquitoes of the season, which were surprisingly pesky.  Down at Denali Park HQ, the meltout date of May 25th was one day short of the 1992 record of May 26th. 

Spring Temperature Anomalies

The cold spring over Interior Alaska is fading into the past now as "insta-summer is upon us: the high was 77ºF at Fairbanks on Saturday and snow is melting fast at higher elevations. This has pushed rivers draining the uplands well up, though so far no flooding on the Chena or Salcha.

For the spring as a whole (Mar-Apr-May), the anomalies are not especially remarkable, and will be even less so by the end of the month. Low level temperature anomalies from the NCEP/NCAR Reanalysis through May 24th, are depicted below for Alaska and vicinity, The warm anomaly over the Arctic Ocean north of Wrangel Island is much more impressive than the cold anomalies over Alaska.

Courtesy of NCEP/NCAR Reanalysis

The cold temperatures show up in this short loop of weekly temperature anomalies (ºC) since March 1st:

Fairbanks Finally Above Normal

Fairbanks topped out at 71ºF Friday, the first day the temperature has been 70 or higher since August 30th. With a morning low of 40ºF, the daily mean of 56ºF was 3 degrees above normal. Here's a plot of daily temperatures this spring.

The long streak of below normal daily means ran from April 4th until May 23, for 49 consecutive days. Using the normals that were effect at the time, the longest consecutive anomaly streak I can find is Oct 18 to Dec 10, 2002, 53 consecutive days with above normal daily means. That streak was bounded by two days that were right at normal (departures of 0ºF). That autumn there were 88 consecutive days between days with a daily average temperature below normal. This spring there were 50 days (April 3-May 23) between above normal days.

More Snow to Go

Reader Richard asked about snowmelt on Keystone Ridge. Here's a photo from Wednesday evening, May 22nd. As you can see, there is still plenty of snow yet to melt, though it's going fast now. As of Thursday evening I was calling the depth 15" and coverage at about 90%. The snow-free areas under the trees are starting to coalesce but have not spread much yet. However, with lows in the past three days in the 40s and dew points now around 30ºF, it will not take more than a few days more to reduce the snow to patches.


Denali National Park Headquarters was down to 12" of snow on the ground as of Thursday morning. The latest meltouts of the winter snowpack there is May 26, 1964 and May 25, 1992, so this year will be close.

Update: Here's a couple of photos from Friday evening, May 24th:

Tanana River at Nenana…A New Record Late Break-Up

Courtesy of the Nenana Ice Classic

At 1142pm AKST (1241pm AKDT) Monday the tripod on the Tanana River at Nenana was still standing (as seen in this photo) making this now the latest break-up of the winter ice of record (since 1917). The previous record was 1141 AKST May 20, 1964. The tripod fell three hours later, at 341pm AKDT as the ice began running.

Record Lows Saturday and Sunday

Courtesy of Pro Music

 The high temperature at Fairbanks Saturday of 35ºF is the lowest so late in the season and the latest date of record with a high in the 30s, breaking the previous record of May 17, 1964. The low of 23ºF Sunday morning was not a record for the date for Fairbanks: record for the 19th is still 20ºF in 1918. Temperatures Sunday morning were coolest in areas with snowpack, including 13ºF at Keystone Ridge and Wickersham Dome and 15ºF at Goldstream Creek, were there is still patchy snow cover.
Photo Sunday afternoon showing ice floes running in the Chena River downtown.



Here are some more records, though I've edited this NWS Fairbanks statement to correct erroneous data in the original:

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE FAIRBANKS AK
1149 AM AKDT SUN MAY 19 2013

...TEMPERATURE RECORDS CONTINUE TO FALL IN INTERIOR ALASKA...

STRONG COLD AIR FROM THE ARCTIC PUSHED TEMPERATURES DOWN ACROSS
THE INTERIOR THE LAST FEW DAYS TO RECORD LEVEL. TEMPERATURES WILL
BE ON THE RISE TODAY THOUGH A FEW RECORDS COULD FALL TODAY BEFORE
THE COLD AIR EXITS THE STATE.

RECORD MINIMUM HIGH TEMPERATURES ON SATURDAY MAY 18TH...
                                       MAX
                                   TEMPERATURE    PREVIOUS RECORD
FAIRBANKS...............................35            44 (1918)
TANANA..................................34            41 (1918)
COLLEGE OBSERVATORY AT UAF..............32            37 (1964)
BETTLES.................................27            35 (1975)
EAGLE COOPERATIVE OBSERVER..............32            40 (1992)
DELTA JUNCTION..........................29            39 (1992)
EIELSON AFB.............................34            42 (1992)
NORTHWAY................................33            38 (1992)
DENALI PARK Headquarters................36            39 (1992)
NORTH POLE (KJNP).......................35            43 (1992)
MCGRATH.................................36            52 (1993)

RECORD LOW TEMPERATURES FOR MAY 19TH...

EIELSON AFB.............................23            29 (1966)
NORTHWAY................................21            25 (1966)
TANANA..................................14            18 (1975)
BETTLES.................................10            14 (1975)
COLLEGE OBSERVATORY AT UAF..............20            26 (1983)
MCGRATH.................................19            28 (1985)
NORTH POLE (KJNP).......................21            25 (1996)
DELTA JUNCTION..........................19            30 (1999)

Updated Fairbanks Temperatures

Interior Alaska's long cold spell will come to and end this week, so here's an update on daily temperatures (through Saturday, May 18th).

As regular reader Richard pointed out, every day in Fairbanks since April 3rd has had a daily mean temperature below normal (the mean on May 11th was one degrees below normal). This appears to be the longest consecutive streak of below normal daily mean temperatures of record, regardless of the base period normals used.

Record Low Temperatures

1030am May 18th, courtesy of the Nenana Ice Classic

I will not be able to keep track of them all, but here are some low temperatures records from the Interior the past day or so:

McGrath (since 1940)
daily record low May 17th of 19ºF
low temperature of May 18th of 15ºF is (by far) coldest so late in the season

Fairbanks (since 1905)
daily record low temp May 18th of 24ºF (might go lower by midnight)

College Observatory ( since 1948)
low of 21ºF coldest so late in the season

Tanana (few gaps, since 1901)
low temp May 18th of 18ºF coldest (barely) so late in the season.

Denali National Park HQ (since 1923)

daily record low May 18th 14ºF, not the coldest so late in the season

Coldest Airmass so Late in the Season is on the Way

As previously mentioned, the coldest airmass so late in the season is moving into Fairbanks-land. This is based on the period of record for upper air soundings, which is this case is since 1948. The WB/NWS in Fairbanks has taken has upper air data since the late 1930s but I've been unable to locate the actual observations from before 1948.

There are numerous ways to assess the temperature of an airmass. In general it's best to use thickness, as this is proportional to the mean temperature through a given layer of the atmosphere. This time of year though it's simplest to use the 850mb temperature (roughly 4000' MSL), since the atmosphere is usually pretty well mixed from the ground up to that level.

For the second half of May and early June, here are the lowest 850 mb temperatures at Fairbanks after May 15th (since 1948). Notice the coldest is an estimate from the high resolution North American Regional Reanalysis as the RAOB was missed that day. 

May 17 1992 00Z: -12.5C (RAOB missed, estimated from NARR)
May 16 1992 00Z: -11.7C
May 16 1992 12Z: -10.9C
May 19 1975 12Z: -10.9C
May 18 1964 12Z: -10.9C
May 18 1964 00Z: -10.5C
Jun 04 2006 12Z: -9.4C

Here is a plot of the GFS forecasted 850mb temperature from the Friday morning run:

As you can see, the GFS is forecasteing 850mb temperatures colder than -12.5C for about 36 hours. For what it's worth, the GFS forecasted an 850mb temperature Friday afternoon at McGrath of -16.3C, and the RAOB came in with -16.7C, by far the coldest so late in the season there.

Updated:

Here's the same model forecast with the verification (through Sunday afternoon) plotted. Fairbanks (-14.3C) and Anchorage (-10.9C) both set records for lowest 850mb temps so late in the season.