Thursday, October 3, 2013

First Snow Date

Most areas of Northern and Interior Alaska have already received their first measurable snowfall this season. Even the Anchorage Bowl (except the official climate site) had a rare early season snowfall late last month. Looking back through the historical record, I decided to put together a map of average (not 'normal') first measurable snow dates.

For this analysis, a station had to have 15 complete years of snowfall data (July 1 to June 30). The 15 years were not required to be consecutive nor contemporary. It took several iterations of analysis to pin down a methodology that filtered out years with too much missing data. Even still, there are still many instances where data were not entered into the GHCN database properly. Still, the calculated data for most stations appears pretty reasonable. The map shows the results of the interpolation from the 189 stations used in the analysis. A 6-point inverse distance weighted surfacing technique was utilized to smooth out the data for the map. Below the map, is a table of all the dates (unsmoothed). To deal with leap years, I calculated the number of days after June 30th that the first measurable snowfall occurred. The table contains the average of those Julian dates and a conversion to calendar dates. For reference, September 1st is day #63, October 1st is day #93, and November 1st is day #124. (Hopefully the length of the table isn't too distracting. If it is, I will change it.



Elevation (m) Station Name Days after June 30th For First Measurable Snow Date Num of Years
5.2 ADAK 124.2 1-Nov 50
82.9 ALYESKA 119.1 27-Oct 32
39.9 ANCHORAGE FRCST OFC 113.1 21-Oct 15
36.6 ANCHORAGE INTL AP 108.8 16-Oct 60
42.1 ANCHORAGE MERRILL FLD 119.2 27-Oct 41
139.6 ANDERSON LAKE 110.0 17-Oct 27
8.5 ANGOON PWR 136.2 13-Nov 30
26.2 ANIAK AP 102.0 10-Oct 31
33.2 ANNETTE ISLAND AP 145.5 22-Nov 71
28 ANNEX CREEK 122.1 30-Oct 66
21.3 ATTU 132.7 9-Nov 15
13.4 AUKE BAY 127.9 4-Nov 47
6.1 BARANOF 130.8 7-Nov 22
9.4 BARROW POST ROGERS AP 42.5 11-Aug 85
11.9 BARTER ISLAND WSO AP 46.1 15-Aug 40
10.7 BEAVER FALLS 149.1 26-Nov 40
3 BELL ISLAND 135.2 12-Nov 19
38.7 BENS FARM 126.7 3-Nov 26
31.1 BETHEL AP 102.1 10-Oct 84
195.7 BETTLES AP 90.2 28-Sep 62
389.2 BIG DELTA AP 92.1 30-Sep 57
18.3 BIG RIVER LAKES 116.2 24-Oct 19
6.1 CALDER 142.7 19-Nov 19
25.9 CANNERY CREEK 123.5 31-Oct 26
649.8 CANTWELL 2 E 88.5 26-Sep 24
14.9 CAPE DECISION 182.9 29-Dec 15
56.4 CAPE HINCHINBROOK 128.4 5-Nov 20
13.7 CAPE LISBURNE 61.9 30-Aug 20
15.8 CAPE LISBURNE AFS 87.4 25-Sep 17
144.8 CAPE NEWENHAM 100.3 8-Oct 26
71.9 CAPE NEWENHAM AFS 103.1 11-Oct 16
132.3 CAPE ROMANZOF 93.3 1-Oct 24
53.9 CAPE SARICHEF LT STN 131.2 8-Nov 19
27.1 CAPE SPENCER 158.6 5-Dec 15
14.9 CAPE ST ELIAS 146.3 23-Nov 24
280.4 CENTRAL #2b 104.9 12-Oct 29
577.6 CHANDALAR LAKE 94.6 2-Oct 16
548.6 CHICKEN 95.2 3-Oct 15
196 CHITINA 109.6 17-Oct 15
412.7 CHULITNA RIVER 97.6 5-Oct 33
182.3 CIRCLE CITY 103.3 11-Oct 19
262.1 CIRCLE HOT SPRINGS 91.2 29-Sep 40
150.9 CLEAR 4 N 98.2 6-Oct 19
335.3 CLEARWATER 97.0 5-Oct 19
23.8 COLD BAY AP 110.6 18-Oct 62
298.1 COLLEGE 5 NW 94.7 2-Oct 34
182 COLLEGE OBSY 95.4 3-Oct 62
1.5 COLVILLE VILLAGE 72.7 10-Sep 16
153.9 COOPER LAKE PROJECT 122.7 30-Oct 40
114.3 COOPER LANDING 5 W 122.6 30-Oct 30
304.8 COPPER CTR 110.5 18-Oct 16
9.4 CORDOVA M K SMITH AP 125.7 2-Nov 85
7.6 CORDOVA NORTH 127.2 4-Nov 22
13.1 CRAIG 159.5 6-Dec 22
26.2 DILLINGHAM FAA AP 119.9 27-Oct 44
3 DUTCH HARBORb 136.9 13-Nov 44
259.1 EAGLE 100.2 8-Oct 39
151.8 EAGLE RIVER 5 SE 117.2 25-Oct 19
166.7 EIELSON FLD 92.9 30-Sep 47
173.1 EIELSON FLDb 93.4 1-Oct 21
11.6 EKLUTNA PROJECT 110.1 18-Oct 31
15.8 ELDRED ROCK 135.6 12-Nov 22
6.1 ELFIN COVE 131.7 8-Nov 32
58.5 ELMENDORF AFB 105.2 13-Oct 36
131.7 FAIRBANKS INTL AP 92.6 30-Sep 65
458.1 FAREWELL FAA AP 90.8 28-Sep 27
9.1 FIVE FINGER LT STN 165.3 12-Dec 23
99.1 FLAT 106.9 14-Oct 22
39.9 FORTMANN HATCHERY 132.2 9-Nov 18
143.3 FT RICHARDSON WTP 121.4 29-Oct 16
132 FT YUKON 95.9 3-Oct 43
46.6 GALENA AP 95.5 3-Oct 17
288 GILMORE CREEK 97.7 5-Oct 23
13.7 GLACIER BAY 136.4 13-Nov 29
671.2 GLEN ALPS 100.2 8-Oct 33
421.5 GLENNALLEN KCAM 105.2 13-Oct 28
6.1 GUARD ISLAND LIGHT STN 155.8 2-Dec 16
476.1 GULKANA AP 96.5 4-Oct 57
12.2 GUSTAVUS 131.0 8-Nov 44
249.9 HAINES 40 NW 109.3 17-Oct 23
4.6 HAINES AP 126.9 3-Nov 28
53.3 HAINES TERMINAL 150.9 27-Nov 22
304.8 HAYES RIVER 100.6 8-Oct 16
448.1 HEALY 2 NW 96.2 4-Oct 25
6.1 HOLY CROSS 107.4 15-Oct 54
345 HOMER 5 NW 107.4 15-Oct 21
329.2 HOMER 8 NW 107.0 15-Oct 32
156.1 HOMER 9 E 113.8 21-Oct 21
19.5 HOMER AP 119.6 27-Oct 61
39.6 HOONAH 140.4 17-Nov 20
54.9 HOPE 126.5 3-Nov 19
43.6 ILIAMNA AP 117.8 25-Oct 49
388.9 INDIAN MTN AFS 90.7 28-Sep 16
36.6 INTRICATE BAY 116.2 24-Oct 40
52.1 JUNEAU DWTN 151.5 28-Nov 30
15.2 JUNEAU DWTN(b) 142.3 19-Nov 28
4.9 JUNEAU INTL AP 127.7 4-Nov 64
21.3 KAKE 170.1 17-Dec 19
21.3 KASILOF 3 NW 118.4 26-Oct 48
38.4 KENAI 9N 115.2 23-Oct 16
27.7 KENAI MUNI AP 115.3 23-Oct 62
673.9 KENNECOTT 101.1 9-Oct 28
23.2 KETCHIKAN INTL AP 156.5 3-Dec 51
487.7 KEYSTONE RIDGE 86.8 24-Sep 16
19.2 KING SALMON 112.9 20-Oct 77
18.3 KITOI BAY 135.8 12-Nov 41
46 KODIAK 130.1 7-Nov 29
24.4 KODIAK AP 126.6 3-Nov 64
9.1 KOTZEBUE RALPH WEIN AP 97.3 5-Oct 72
19.5 KUPARUK 71.9 9-Sep 25
14.9 LATOUCHE 135.7 12-Nov 25
223.4 LAZY MTN 107.8 15-Oct 23
4.3 LITTLE PORT WALTER 144.4 21-Nov 60
17.4 MAIN BAY 119.9 27-Oct 23
82.9 MANLEY HOT SPRINGS 101.2 9-Oct 45
52.4 MATANUSKA EXPERIMENT FARM 116.7 24-Oct 86
381 MCCARTHY 3 SW 96.0 4-Oct 19
101.5 MCGRATH AP 95.7 3-Oct 73
630.9 MCKINLEY PARK 91.8 29-Sep 76
14 MIDDLETON ISLAND AUTO 141.9 18-Nov 15
312.4 MINCHUMINA 96.1 4-Oct 39
150 MOOSE PASS 3 NW 124.5 1-Nov 22
6.1 MOSES POINT FAA AP 97.8 5-Oct 20
890 NABESNA 94.0 2-Oct 25
109.7 NENANA MUNI AP 102.9 10-Oct 54
4 NOME MUNI AP 101.4 9-Oct 86
144.8 NORTH POLE 94.9 2-Oct 41
9.1 NORTHEAST CAPE 94.9 2-Oct 15
522.1 NORTHWAY AP 89.5 27-Sep 57
34.1 NULATO 101.9 9-Oct 16
402.3 OLD EDGERTON 98.8 6-Oct 22
67.1 PALMER 1 N 109.7 17-Oct 16
65.8 PALMER JOB CORPS 117.8 25-Oct 45
823 PAXSON(b) 84.3 22-Sep 16
3.7 PELICAN 130.6 7-Nov 24
32.6 PETERSBURG 1 135.3 12-Nov 62
20.4 PLANT MATERIALS CTR 116.9 24-Oct 16
6.1 PLATINUM 120.4/td> 28-Oct 15
6.1 POINT RETREAT LT STN 143.5 20-Nov 22
3.7 PORT ALEXANDER 145.3 22-Nov 40
79.2 PORT ALSWORTH 118.3 26-Oct 43
28 PORT HEIDEN 128.8 5-Nov 21
12.2 PORT SAN JUAN 132.3 9-Nov 25
566.3 PUNTILLA 104.8 12-Oct 40
116.1 RAMPART 95.7 3-Oct 27
157.9 SEWARD 19N 117.9 25-Oct 22
129.2 SEWARD 8 NW 107.2 15-Oct 17
6.7 SEWARD AP 131.8 8-Nov 88
694.9 SHEEP MTN CAA AP 99.7 7-Oct 20
37.2 SHEMYA USAF BASE 124.2 1-Nov 39
3 SHISHMAREF 98.6 6-Oct 17
4.3 SITKA AIRPORT 144.6 21-Nov 48
20.4 SITKA MAGNETIC OBSY 144.4 21-Nov 71
10.7 SKAGWAY 136.4 13-Nov 39
45.7 SKWENTNA 108.0 15-Oct 46
668.1 SLANA 105.9 13-Oct 34
704.7 SNOWSHOE LAKE 92.9 30-Sep 35
597.4 SOURDOUGH 1 N 94.9 2-Oct 19
481.6 SPARREVOHN 87.8 25-Sep 21
484 SPARREVOHN MTN AFS 101.3 9-Oct 16
10.7 ST PAUL ISLAND AP 106.9 14-Oct 63
734.9 SUMMIT WSO AP 83.6 21-Sep 34
167.6 SUTTON 1 W 105.3 13-Oct 29
798.6 TAHNETA PASS 91.9 29-Sep 17
106.7 TALKEETNA AP 109.9 17-Oct 76
469.7 TANACROSS 91.8 29-Sep 18
69.2 TANANA CALHOUN MEM AP 100.9 8-Oct 82
293.8 TATALINA 99.2 7-Oct 27
82 TIN CITY 81.6 19-Sep 28
495.3 TOK 95.4 3-Oct 36
481.3 TONSINA 107.0 15-Oct 35
11 TREE POINT LT STN 159.7 6-Dec 29
99.1 TRI NAL ACRES 116.7 24-Oct 16
734.9 TRIMS CAMP 85.5 23-Sep 20
81.1 UMIAT 88.4 26-Sep 28
5.5 UNALAKLEET FLD 101.3 9-Oct 48
144.8 UNIVERSITY EXP STN 103.5 11-Oct 101
29 VALDEZ WSO 109.6 17-Oct 82
7.6 WALES 96.6 4-Oct 46
152.4 WASILLA 2 NE 104.2 12-Oct 15
15.2 WASILLA 3 S 120.5 28-Oct 38
82.3 WHITES CROSSING 118.6 26-Oct 31
307.8 WHITESTONE FARMS 91.8 29-Sep 16
18.3 WHITTIER 118.6 26-Oct 40
62.5 WILLOW WEST 119.9 27-Oct 17
349.6 WISEMAN 94.1 2-Oct 29
17.1 WRANGELL AIRPORT 149.8 26-Nov 70
8.2 YAKATAGA AP 129.1 6-Nov 24
10.1 YAKUTAT STATE AP 122.3 30-Oct 86
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4 comments:

  1. NL7YOctober 3, 2013 at 11:45 PM

    Very good Brian. After 30 years to the month having land 93 miles/225 deg M SW of Fairbanks at 750 MSL, I can say that at that location the initial snow event typically precedes any reporting station within that distance. Orographics and higher elevation than the reporting stations within the circle are the key players.

    Yet another example of location specific weather with dissimilar characteristics that offers an alternative to the interpolation of established recording stations.

    Gary

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    Replies
    1. Climatologist49October 4, 2013 at 7:56 AM

      Thanks Gary. As someone with a lot of flying time, you probably have a lot of interesting observations of weather and climate from above. Looking on Google Earth, 93 miles SW of Fairbanks is almost exactly (within 1 mile) where the infamous "Magic Bus" is located.

      Delete
    2. NL7YOctober 4, 2013 at 9:49 AM

      Hi Brian. Try this mapping link for the general area I was referencing. The Bus is considerably SE of the lake:

      http://itouchmap.com/?r=googleearth&mt=iTouchMap%20Point&ml=64.4394444&mg=-150.8197222

      Zoom around the lake (750' MSL) and with the right perspective, note the weather grabbing terrain. The weather (if snow in this case) hits the terrain that's higher than the nearby reporting stations at Tanana and Nenana AK. It'll snow there, and at similar or greater elevations, well before the Tanana valley floor. Same for wind...the E>W Tanana Jet hits the surrounding hilltops then eventually descends to lower elevations. The sound the incoming winds make are audible well before they arrive.

      I expect with today's weather soundings it's feasible to forecast WX at altitudes above the sensing location. Maybe the NWS someday will send out drones to have a confirming look and gather location specific data.

      Delete
    3. Climatologist49October 7, 2013 at 8:18 PM

      Now I see where you are referring to. I wouldn't hold my breath on the drones but I think that someday all the small planes (Cessnas, Super Cubs, etc.) will be able to transmit real-time weather to forecast offices - just like large commercial aircraft.

      Delete

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