Saturday, September 28, 2013

Another Significant Advancement in Climate Link

The Climate link for Starvalleyweather.com has again undergone a major upgrade.  Now instead of just using the 3SE Bedford climatological station an additional 23 stations have been added by John Hart covering a good portion of Western Wyoming.

The use of the site remains as the original blog from 2012 but now applies to all the additional stations. The period of record varies but many have been active for several decades. To see the period of record for each site check out the blog at

http://starvalleywyweather.blogspot.com/2013/10/climate-stations-period-of-record.html

In review as an example, the climate section links to the 3SE Bedford climatological station.  The record for this station covers the period from 1975 until the current year.  To look at the official data of 3SE Bedford station you can go to this site:

http://www.wrcc.dri.edu/cgi-bin/cliMAIN.pl?wy0603

Following is a discussion of what information is now available at this link:

http://www.starvalleyweather.com/climate.php



The Climate data defaults to the current days information, in this example for October 25th.



In addition to the average high and low temperature, it displays warmest and coldest maximum and minimum for the day. The precipitation  section displays not only the average for the day but the maximum observed since 1975.  It is the same for the snowfall, the daily average and maximum  observed along with the year of occurrence.

Average snow depth since 1975 along with the greatest measured in the period of record and year of occurrence is also shown.

The temperature graph :


The color portion displays the average maximum and minimum for each day of the year. In addition, the record maximum and minimum temperature is plotted for each day.  As an example, the highest temperature since 1975 occurred on June 11 2001 when the thermometer hit 97.  The lowest was -38 on January 1,1979.

The precipitation graph:

displays the daily average.  Based on this graph the wettest periods are late Spring and again late November/early December.

The snow graph:

shows the average observed snow depth for each day since 1975.  Typically the greatest depth is observed late in February and early March.  This obviously varies somewhat from year to year.

One final feature of the page is the ability to see each days climate statistics just by clicking on any portion of the image.


To return  daily climate stats back to the current day......... just reload.

On another note, a correction was made to the program at the current condition link below:

http://www.starvalleyweather.com/current.php

Thus it will readily respond to scrolling the cursor across the temperature/wind/rainfall links.


Friday, September 27, 2013

Wyoming Storm Summary

Star Valley Ranch, Friday September 27 2013

Riverton Weather Office has issued a summary of rain/snow for the storm that has impacted much of Wyoming.

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE RIVERTON WY
1245 PM MDT FRI SEP 27 2013

A VERY MOIST AND POTENT STORM SYSTEM PROVIDED AN EARLY FALL RAIN AND
SNOW TO MUCH OF THE REGION WITH IMPACTS FELT ACROSS WESTERN AND 
CENTRAL WYOMING. 

HEAVY WET SNOW CAME TO THE REGION THURSDAY EVENING AND OVERNIGHT 
INTO FRIDAY MORNING. TOWNS IN THE WIND RIVER BASIN AND NEARBY AREAS 
SAW NUMEROUS TREE BRANCHES DOWN BECAUSE OF THE WEIGHT OF THE SNOW. 
SOME POWER OUTAGES HAVE OCCURRED THIS MORNING. THE SNOW WILL 
CONTINUE TO DECREASE FROM WEST TO EAST THIS AFTERNOON. CLEARING
SKIES AND LINGERING SNOW COVER WILL PROVIDE FOR SUB-FREEZING LOW
TEMPERATURES IN MANY AREAS TONIGHT. 

HERE ARE THE LATEST SNOW TOTALS AS OF 1230 PM FRIDAY. RAINFALL OVER
THE PAST 72 HOURS IS INCLUDED BELOW THE SNOW REPORTS. 

LOCATION                             SNOWFALL

BIG HORN COUNTY...
 BONE SPRINGS DIVIDE SNOTEL...       10 INCHES.
 SHELL CREEK SNOTEL...               10 INCHES.
 BALD MOUNTAIN SNOTEL...              8 INCHES.

FREMONT COUNTY...
 DEER PARK SNOTEL...                 14 INCHES.
 HOBBS PARK SNOTEL...                11 INCHES.
 COLD SPRINGS SNOTEL...              11 INCHES.
 SOUTH PASS SNOTEL...                10 INCHES.
 10 NW RIVERTON...                    8 INCHES.
 ST. LAWRENCE ALT SNOTEL...           8 INCHES.
 LITTLE WARM SNOTEL...                8 INCHES.
 ATLANTIC CITY...                     7 INCHES.
 9 SSE LANDER...                    6.8 INCHES.
 RIVERTON AIRPORT...                6.6 INCHES.
 RIVERTON...                          6 INCHES.
 JEFFREY CITY...                      6 INCHES.
 HUDSON...                            6 INCHES.
 4 W RIVERTON...                    5.5 INCHES.
 10 NE RIVERTON...                    5 INCHES.
 CASTLE CREEK SNOTEL...               4 INCHES.
 LANDER AIRPORT...                  3.7 INCHES.
 1 W LANDER...                      3.5 INCHES.
 SHOSHONI...                          3 INCHES.
 7 ESE KINNEAR...                     3 INCHES.
 DUBOIS...                            3 INCHES. 
 LANDER...                            3 INCHES.
 RIVERTON...                        2.2 INCHES.

HOT SPRINGS COUNTY...
 OWL CREEK SNOTEL...                 11 INCHES.
 THERMOPOLIS...                       4 INCHES.
 9 NE THERMOPOLIS...                3.4 INCHES.
 KIRBY...                             1 INCH.

JOHNSON COUNTY...
 BEAR TRAP MEADOW SNOTEL...          11 INCHES.
 HANSEN SAWMILL SNOTEL...            11 INCHES.
 LITTLE GOOSE SNOTEL...              11 INCHES.
 SOLDIER PARK SNOTEL...              10 INCHES.
 CLOUD PEAK RESERVOIR SNOTEL...       9 INCHES.
 4 SSW BUFFALO...                     8 INCHES.
 BUFFALO...                      2 TO 4 INCHES.
 KAYCEE...                            4 INCHES.
 17 E KAYCEE...                     1.5 INCHES.

LINCOLN COUNTY...
 5 SSE SMOOT...                       1 INCH.
 5 NNE THAYNE...                      1 INCH.
 AFTON...                           0.3 INCHES.

NATRONA COUNTY...
 GRAVE SPRING SNOTEL...               8 INCHES.
 CASPER MOUNTAIN SNOTEL...            6 INCHES.
 RENO HILL SNOTEL...                  5 INCHES.
 CASPER MOUNTAIN...                 4.5 INCHES.
 POWDER RIVER SCHOOL...               4 INCHES.
 PARADISE VALLEY...                   4 INCHES.
 4 WSW CASPER...                    3.3 INCHES.
 4 SW CASPER...                     3.2 INCHES.
 CASPER AIRPORT...                  3.2 INCHES.
 CASPER...                       1 TO 3 INCHES.
 EVANSVILLE...                        2 INCHES.
 MIDWEST...                           1 INCH.

PARK COUNTY...
 KIRWIN SNOTEL...                    11 INCHES.
 MARQUETTE SNOTEL...                 10 INCHES.
 TIMBER CREEK SNOTEL...              10 INCHES.
 EVENING STAR SNOTEL...               5 INCHES.
 3 NE SUNSHINE...                   4.2 INCHES.
 BLACKWATER SNOTEL...                 4 INCHES.
 MEETEETSE...                       2.5 INCHES.
 BEARTOOTH LAKE SNOTEL...             2 INCHES.
 PAHASKA...                         0.5 INCHES.

SUBLETTE COUNTY...
 POCKET CREEK SNOTEL...              10 INCHES.
 BIG SANDY OPENING SNOTEL...          9 INCHES.
 LARSEN CREEK SNOTEL...               5 INCHES.
 ELKHART PARK G.S. SNOTEL...          5 INCHES.
 GUNSITE PASS SNOTEL...               4 INCHES.
 14 NW PINEDALE...                    2 INCHES.
 PINEDALE...                        1.1 INCHES.
 KENDALL RANGER STATION SNOTEL...     1 INCH.
 NEW FORK LAKE SNOTEL...              1 INCH.
 BOULDER REARING STATION...           1 INCH.
 DANIEL FISH HATCHERY...            0.5 INCHES.

SWEETWATER COUNTY...
 1 W ROCK SPRINGS...                0.1 INCHES.

TETON COUNTY...
 BASE CAMP SNOTEL...                  6 INCHES.
 TOGWOTEE PASS...                     5 INCHES.
 GROS VENTRE SUMMIT SNOTEL...         2 INCHES.
 PHILLIPS BENCH SNOTEL...             2 INCHES.
 JACKSON LAKE...                      2 INCHES.
 GRAND TARGHEE SNOTEL...              1 INCH.

WASHAKIE COUNTY...
 POWDER RIVER PASS SNOTEL...         10 INCHES.
 MIDDLE POWDER SNOTEL...              8 INCHES.
 14 SSE TEN SLEEP...                  4 INCHES.
 16 SSE TEN SLEEP...                2.3 INCHES.
 5 NNW TEN SLEEP...                   2 INCHES.
 TEN SLEEP...                       1.8 INCHES.
 WINCHESTER...                      0.3 INCHES.

YELLOWSTONE NATIONAL PARK...
 PARKER PEAK SNOTEL...                5 INCHES.
 THUMB DIVIDE SNOTEL...               4 INCHES.
 OLD FAITHFUL RANGER STATION...       2 INCHES.
 CANYON SNOTEL...                     2 INCHES.
 TWO OCEAN PLATEAU SNOTEL...          2 INCHES.
 LEWIS LAKE DIVIDE SNOTEL...          2 INCHES.
 YELLOWSTONE EAST ENTRANCE...         1 INCH.
 SYLVAN ROAD SNOTEL...                1 INCH.
 BECHLER RIVER RANGER STATION...    0.6 INCHES.
 TOWER FALLS RANGER STATION...      0.5 INCHES.
 SNAKE RIVER RANGER STATION...      0.3 INCHES.

...LATEST RAINFALL REPORTS...

LOCATION                       AMOUNT    TIME/DATE                            

...ABSAROKA MOUNTAINS...
19 SSW WAPITI (6200 FT)        1.31      1200 PM 09/27                        
PAHASKA (6696 FT)              0.90      0700 AM 09/27                        
PAHASKA (6800 FT)              0.86      0900 AM 09/27                        
3 E PAHASKA (7500 FT)          0.68      1157 AM 09/27                        
PORTABLE RAWS (7137 FT)        0.57      1202 PM 09/27                        
10 N DUBOIS (8085 FT)          0.39      1157 AM 09/27                        
10 WNW CODY (8401 FT)          0.35      1140 AM 09/27                        
CHIEF JOSEPH HWY MILE MARKER 9 0.30      1112 AM 09/27                        
12 SE PAHASKA (9780 FT)        0.06      1100 AM 09/27                        

...BIGHORN MOUNTAINS WEST...
POWDER RIVER PASS (9480 FT)    0.09      1100 AM 09/27                        

...CODY FOOTHILLS...
6 SW MEETEETSE (6238 FT)       1.16      0640 AM 09/27                        
2 WSW CODY (5161 FT)           1.03      0700 AM 09/27                        
WAPITI (5400 FT)               0.90      1115 AM 09/27                        
SHOSHONE RIVER AT WILLWOOD DAM 0.51      1145 AM 09/27                        
BUFFALO BILL RESERVOIR         0.47      1145 AM 09/27                        
3 NE CLARK (4090 FT)           0.26      0800 AM 09/27                        

...EAST SWEETWATER COUNTY...
ROCK SPRINGS AIRPORT (6760 FT) 0.65      0554 AM 09/27                        

...FLAMING GORGE...
FLAMING GORGE - BUCKBOARD MARI 1.00      0745 AM 09/27                        

...GREEN MOUNTAINS AND RATTLESNAKE RANGE...
JEFFREY CITY (6320 FT)         1.39      0730 AM 09/27                        

...JACKSON HOLE...
JACKSON (6240 FT)              1.36      1145 AM 09/27                        
JACKSON - COOP (6210 FT)       1.33      0900 AM 09/27                        
1 ENE MOOSE (6496 FT)          1.14      0700 AM 09/27                        
MORAN (6800 FT)                1.12      0800 AM 09/27                        
SNAKE RIVER AT JACKSON LAKE DA 1.11      1145 AM 09/27                        
4 N MOOSE (6730 FT)            1.09      1158 AM 09/27                        
7 E MORAN JCT (7251 FT)        1.08      1152 AM 09/27                        
5 S OF SOUTH ENTRANCE YNP      0.66      1145 AM 09/27                        

...LANDER FOOTHILLS...
LANDER AIRPORT (5586 FT)       1.52      0553 AM 09/27                        
LANDER (5320 FT)               1.41      0630 AM 09/27                        

...NATRONA COUNTY LOWER ELEVATIONS...
POWDER RIVER (5695 FT)         1.10      0800 AM 09/27                        
MIDWEST (4860 FT)              0.77      0700 AM 09/27                        
CASPER AIRPORT (5320 FT)       0.69      0553 AM 09/27                        
CASPER - COOP (5100 FT)        0.10      0700 AM 09/27                        

...NORTH BIG HORN BASIN...
SHELL (4285 FT)                0.90      0551 AM 09/27                        
GREYBULL (3860 FT)             0.76      0943 AM 09/27                        
POWELL (4370 FT)               0.72      0800 AM 09/27                        
BIG HORN RIVER NEAR KANE       0.53      1115 AM 09/27                        
GREYBULL AIRPORT (3935 FT)     0.39      0500 AM 09/27                        

...NORTHEAST JOHNSON COUNTY...
BUFFALO (4635 FT)              1.18      0500 AM 09/27                        
BUFFALO AIRPORT (4970 FT)      1.10      0553 AM 09/27                        

...ROCK SPRINGS AND GREEN RIVER...
GREEN RIVER (6133 FT)          0.80      0700 AM 09/27                        

...SALT RIVER AND WYOMING RANGES...
PORTABLE RAWS (8378 FT)        0.92      1125 AM 09/27                        
SMITHS FORK NEAR BORDER        0.53      1130 AM 09/27                        
13 E COKEVILLE (7460 FT)       0.35      1130 AM 09/27                        
15 NE COKEVILLE (8470 FT)      0.34      1200 PM 09/27                        
8 NE AFTON (8450 FT)           0.08      1100 AM 09/27                        

...SOUTH LINCOLN COUNTY...
KEMMERER (6980 FT)             0.30      1200 PM 09/27                        

...SOUTHEAST BIG HORN BASIN...
WORLAND (4060 FT)              1.80      0700 AM 09/27                        
TENSLEEP (4680 FT)             1.65      0700 AM 09/27                        
WORLAND AIRPORT (4245 FT)      1.57      0553 AM 09/27                        
WILD HORSE (8150 FT)           0.95      1148 AM 09/27                        

...SOUTHEAST JOHNSON COUNTY...
KAYCEE - COOP (4660 FT)        1.16      0700 AM 09/27                        

...SOUTHWEST BIG HORN BASIN...
KIRBY (4328 FT)                1.65      0720 AM 09/27                        
THERMOPOLIS 9 NE (4280 FT)     1.42      0500 AM 09/27                        

...STAR VALLEY...
6 S ALPINE (5676 FT)           2.30      1115 AM 09/27                        
1 SE THAYNE (6086 FT)          1.26      0700 AM 09/27                        
AFTON - COOP (6245 FT)         0.91      0800 AM 09/27                        

...TETON AND GROS VENTRE MOUNTAINS...
PORTABLE RAWS (6195 FT)        1.39      1151 AM 09/27                        
ALTA (6430 FT)                 0.78      1145 AM 09/27                        
15 NNE GRAND TARGHEE (6830 FT) 0.50      1203 PM 09/27                        
TOGWOTEE PASS (9850 FT)        0.10      1100 AM 09/27                        
8 NNE MORAN JUNCTION (7030 FT) 0.09      1100 AM 09/27                        
10 N BONDURANT (6770 FT)       0.08      1100 AM 09/27                        
32 ESE JACKSON (8750 FT)       0.07      1100 AM 09/27                        
GRAND TARGHEE (9260 FT)        0.06      0500 AM 09/27                        
2 NE TETON PASS (8200 FT)      0.06      0200 AM 09/27                        

...UPPER GREEN RIVER BASIN...
BIG PINEY AIRPORT (6974 FT)    0.05      0500 AM 09/27                        

...UPPER GREEN RIVER BASIN FOOTHILLS...
2 NW BONDURANT (6726 FT)       0.89      1151 AM 09/27                        
BOULDER REARING STATION - COOP 0.82      0800 AM 09/27                        
BONDURANT (6650 FT)            0.80      1200 PM 09/27                        
DANIEL FISH HATCHERY - COOP    0.32      0800 AM 09/27                        

...UPPER WIND RIVER BASIN...
DUBOIS (6955 FT)               0.86      0600 AM 09/27                        
11 W CROWHEART (6520 FT)       0.81      1145 AM 09/27                        
6 NW DUBOIS (7189 FT)          0.73      1115 AM 09/27                        

...WIND RIVER BASIN...
BOYSEN DAM (4760 FT)           1.63      0730 AM 09/27                        
HUDSON (5090 FT)               1.59      0630 AM 09/27                        
RIVERTON (4950 FT)             1.56      0700 AM 09/27                        
RIVERTON AIRPORT (5525 FT)     1.39      0500 AM 09/27                        
RIVERTON FORECAST OFFICE       1.29      0500 AM 09/27                        

...WIND RIVER MOUNTAINS EAST...
13 W CROWHEART (9630 FT)       0.07      1100 AM 09/27                        

...WIND RIVER MOUNTAINS WEST...
BOULDER LAKE (7350 FT)         1.09      1200 PM 09/27                        
N WIND RIVER MTS (8833 FT)     1.00      1110 AM 09/27                        
PINE CREEK ABOVE FREMONT LAKE  0.70      1145 AM 09/27                        
SOUTH PASS CITY (8540 FT)      0.41      1200 PM 09/27                        
PORTABLE RAWS (8503 FT)        0.37      1155 AM 09/27                        

...YELLOWSTONE NATIONAL PARK...
EAST ENTRANCE YELLOWSTONE NP - 0.97      0730 AM 09/27                        
SNAKE RIVER RANGER STATION     0.68      0705 AM 09/27                        
SOUTH ENTRANCE YNP (6900 FT)   0.65      1145 AM 09/27                        
14 S SYLVAN PASS (8650 FT)     0.64      1208 PM 09/27                        
YELLOWSTONE LAKE (7835 FT)     0.58      0556 AM 09/27                        
TANTALUS CREEK NEAR NORRIS JUN 0.57      1130 AM 09/27                        
1 NNE LAKE (7875 FT)           0.56      1200 PM 09/27                        
OLD FAITHFUL (7320 FT)         0.56      1115 AM 09/27                        
4 W SOUTH ENTRANCE YNP         0.56      1145 AM 09/27                        
BECHLER RANGER STATION - COOP  0.52      0800 AM 09/27                        
SODA BUTTE RAWS (8160 FT)      0.48      1117 AM 09/27                        
1 SW CANYON (7900 FT)          0.46      1049 AM 09/27                        
EXTREME SW YELLOWSTONE         0.45      1149 AM 09/27                        
14 WSW MAMMOTH (7900 FT)       0.36      1149 AM 09/27                        
MAMMOTH (6300 FT)              0.28      1115 AM 09/27                        
TOWER FALLS (6266 FT)          0.25      0800 AM 09/27                        
TOWER FALLS (6266 FT)          0.24      1115 AM 09/27                        
GARDNER RIVER NR MAMMOTH       0.19      1145 AM 09/27

Thursday, September 26, 2013

Late September Storm Video

Riverton Weather Forecast Office has issued their weekly  weather video discussing the current storm affecting much of Wyoming and an outlook for the next several days.

Weekly Weather Video

Tuesday, September 24, 2013

So, How Much Snow?

The Snow word has entered  into the forecast for Star Valley and much of Western Wyoming beginning later Wednesday.  So the question arises how much snow and when.  Forecasting snow amounts is one of the more difficult challenges for meteorologist, particularly in rough terrain such as in Wyoming. An additional uncertainty, due to the fact it is still September, is rain vs snow.

The system that is going to bring the big change over the next 3 days can  be seen in the satellite photo along the Pacific Northwest coast this morning.

Infrared satellite and 50 0mb analysis Tuesday morning 09/24/13
Following is the 4-day sequence of 500 mb forecasts.

Tue am 9/24/13

Wed am 9/25/13
Thu am 9/26/13
Fri am 9/27/13
Sat am 9/28/13
About the only certainty is that it will snow in the mountains and likely in the valleys above about 5500 feet by Thursday morning.  The computer models along with the forecasters at the National Weather Service are providing some forecast guidance for snow potential.  Following are some of the products for our area.

The first is a model probability forecast of both rain and snow.which indicates that precipitation will begin in the form of rain during the day on Wednesday and turn to all snow by Wednesday night.

Green is liquid and blue is frozen probabilities with the time in GMT.
The next model forecast is the total amount of precipitation expected in the next 3 days.

The black line is the mean of many model forecasts for the same time in hundredths of an inch.
All the model solutions agree that precipitation begins Wednesday morning and continues at times through Thursday with totals ranging from one half inch to around an inch.

The next forecast is for the total amount of snow in the valley floor.

The black line is the mean of many model solutions for total snow fall  Star Valley in inches
There is quite a spread in solutions for snowfall as would be expected given the many variables such as rain vs snow etc, but the mean suggest possibly up to 4 inches snowfall by late Thursday.  The actual accumulation would be less given the warm ground conditions.

The forecasters at the Weather Prediction Center of the NWS make forecasts based on these models for the next 3 days.  The first image is the expected 3 day total of precipitation, indicating a major event for much of northern and western Wyoming.

Total precipitation  Tuesday through Thursday  Sept 24-27 2013

These forecasters also provide a probability product for chances of total snowfall reaching a certain amount over the next three days.




From these forecast graphics, Star Valley floor has about an even chance of 2 inches over the next 3 days with a near certainty in the mountains of much of western Wyoming.  Of more importance to hunters and those in the mountains of northwest Wyoming is a good chance of 8 inches and even 30 percent probability of a foot or more around YellowStone NP.

Thursday, September 19, 2013

Stormy End of September

Following is the link to the weekly Video from the Riverton Forecast Office.  In it they highlight the stormy pattern that will affect much of Wyoming the remainder of the month.


Weekly Weather Briefing from Riverton Forecast Office

First Snow

Snow fell on the higher elevations of Northwest Wyoming with the recently departed storm.

Following is a photo taken from the Cam on the Mt. Washburn lookout in Yellowstone NP this Thursday morning as well as a short video of the sunrise.




video

Wednesday, September 18, 2013

Tuesday Storm Summary

A series of thunderstorms pounded parts of Star Valley with heavy rain, lots of hail, strong winds and intense lightning Tuesday afternoon and evening.  The first round raced across the Thayne/Star Valley Ranch region around 2:30pm with the following photo taken at the intersection of Muddy String and the Thayne/Bedford Road. This storm produced wind gusts to 49 mph at Thayne ES and 46 mph at the Star Valley Ranch station.

The second storm which also produced hail up to half an inch in diameter affected much of the same area around 3:30pm.

Then the final, probably the most intense hail and wind storm hammered the south portion of Star Valley Ranch and particularly the Lost Creek Development.  The hail and wind stripped leaves and needles  from the trees and shredded the gardens.  Following are some photos taken Wednesday morning from a Lost Creek Home



Morning after hail accumulation

Squash plants stripped



Leaves stripped
Beneficial rainfall fell throughout the valley.

Star Valley Ranch                  1.15
Star Valley Ranch Vista Rd    1.03
Thayne 1SE                             .86
Afton                                       .79
Thayne ES                               .73
Smoot                                      .61
Etna 2NE                                 .59
Alpine                                       .49
CakeBread Ranch                    .48
Smoot 7S                                 .44
Double L Ranch                        .38
                                     

Tuesday, September 17, 2013

First Fall Storm to bring Thunderstorms and Freezing Temperatures

The first signs of Fall are now showing in the trees of Star Valley as the Maples and Aspens begin to turn. Right on cue the weather pattern which has been dominated by the summertime Monsoon flow of moisture much of the month of September will be replaced by the initial(first of the season) trough moving from the Pacific in the seasonal strengthening of the jet stream.

This upper trough shows up well this morning as it moves onshore in the Pacific Northwest

500 MB Analysis 6AM Tue September 17 2013
By Wednesday morning the trough will be moving across the Northern Rockies accompanied by a much cooler airmass

500 MB forecast 6AM Wed  September 18 2013

As there is still monsoon moisture across our area, the approach of the trough and its associated cold front will result in an active thunderstorm afternoon and evening, centered on Western Wyoming.

The morning water vapour imagery shows not only the moisture associated with the trough but also already convection that has formed this morning over parts of southeast Idaho and Northwest Wyoming in the monsoon moisture still in the area.

Water Vapor Imagery 8AM Tue 9/17/13
The Storm Prediction Center is forecasting a Risk of a few severe thunderstorms this afternoon and evening centered over Star Valley and Western Wyoming.

The primary threat will be for local damaging winds in excess of 60 MPH in the stronger storms that develop later this afternoon.


While tornados are not expected, there is also a potential of localized large hail.



To keep up to date on this threat of storms this afternoon which includes the possibility of a Severe Thunderstorm Watch,  check with the SPC Home Page.

Also warnings and statements would be issued by both the Pocatello Forecast Office and the Riverton Forecast Office.

The much colder air with this trough will drop temperatures a good 15 degrees for Wednesday afternoon, and as winds diminish and skies will be clear, the first frost/freezing temperatures will be experienced Thursday morning.  At this time it looks like the colder valley locations could drop into the mid and upper 20s with warmer locations such as Star Valley Ranch remaining near or just below freezing.  

The freeze threat is about on schedule.  Following is a table showing when the first freezing and below 28 degree temperatures have occurred in previous years in Star Valley.




Sunday, September 15, 2013

More on the Colorado Floods

Here is a detailed discussion on the flooding of last week in the Boulder area.  Certainly once in a lifetime event for those affected.


INSIDE THE COLORADO DELUGE

How much rain fell on the Front Range, and how historic was it?

Bob Henson | September 14, 2013  •  Even after the rains finally abated on Friday, I found myself struck by how the waterlogged air in Boulder felt oddly, almost eerily tropical. This only put an exclamation point on the weirdness of the week and its events. Four days of rainfall across Colorado’s Front Range produced massive flooding that’s marooned thousands of people, inundated many key roads, and damaged countless homes and businesses. 
Flood waters roaring along the Bear Creek bikeway
A bike/pedestrian path along Bear Creek in south Boulder—normally a placid thoroughfare—is engulfed by flood waters on Thursday afternoon, September 12. (Photo by Bob Henson, UCAR. This image is freely available for media & nonprofit use.)
Just how rare was this event? Was it a 100-year flood, or something bigger (or smaller)? As always, the answer depends on exactly what you’re looking at, and exactly where.

RAINFALL: OFF THE CHARTS 

There’s no doubt that the rains in and near my hometown were truly historic, as evidenced by data from Boulder’s official weather station.
Part of the NOAA cooperative observing program, this station has been located at the NIST/NOAA campus in south Boulder since 1990. Boulder’s weather history actually extends much further back, to 1893, including the catastrophic 1894 flood that devastated central Boulder (more on that one below).
Map of rainfall totals across eastern Colorado, Sept. 6-13, 2013
Rainfall amounts for the seven days ending at noon MDT on Friday, September 13, ranged from 5 to 10-plus inches across large swaths of the Colorado Front Range, with similar amounts eastward into northwest Kansas. (Image courtesy NOAA/NWS.)
The weather station was moved several times over that 97-year period, and observations weren’t kept as rigorously as today, so there are some missing data—though it’s unlikely an event as titanic as this week’s would have gone unobserved.
Between 00Z Thursday 9/12 (6 PM Mountain Daylight Time on Wednesday) and 00Z Friday 9/13, a total of 9.08”was measured at the official Boulder site. From 6 PM Monday 9/9 through 6 PM Friday 9/13, the grand total was a whopping 14.70”.
For perspective: 
  • Boulder’s previous record for wettest calendar day—4.80” (July 31, 1919)—was shattered.
  • The single day of rain on Thursday was also nearly twice as much as any other entire September has produced (5.50”, in 1940).
  • The full week’s rainfall easily topped the 9.59” observed in May 1995, Boulder’s wettest month up to now.
  • This week’s precipitation also exceeded the 12.96” that fell in Boulder during this entire year up to September 8. It put the city within striking distance of wettest year on record (29.93”, set in 1995), with only about 2” more needed by December 31 to break that mark.

WIDESPREAD, LONG-LASTING, LATE-SEASON

Matt Kelsch measures Boulder's record 24-hour rainfall at observing station
Matt Kelsch, a hydrometeorologist in UCAR’s Community Programs who volunteers with NOAA’s cooperative weather observing program, measures the historic daily total of 9.08 inches at Boulder’s official station on September 12. (Photo by Bob Henson, UCAR. This image is freely available for media & nonprofit use.)
Two things that helped make this rainfall historic are breadth and duration. Colorado can get much higher rainfall rates for brief periods and over small areas. One pocket of Fort Collins, Colorado, received more than 10 inches in less than six hours on July 28, 1997, leading to deadly flash floods there. However, it’s much harder to get the atmosphere to produce near-constant rain in large amounts for three-plus days across most of the semiarid High Plains and adjoining foothills of the Front Range.
Another unusual aspect is timing. Before now, the 10 heaviest single-day rains in Boulder history had all occurred between early April and early August. Interestingly, this week’s deluge followed a week-plus of record heat across much of the West that felt more like midsummer than September. Then the hot dome of upper-level high pressure shifted north and east, while a large but weak upper low set up shop across the western United States. With the main jet stream located well north into Canada, this pattern stayed in place for most of the week.
The immense amount of water that fell arrived at upper levels via a plume of deep moisture that surged northward from the tropics. At lower levels, the pattern drove moist air from the Great Plains toward the foothills, where it was forced upslope (see map). Together, these features blanketed the Front Range with the soggiest air mass ever recorded at Denver in September, as measured by radiosondes(weather balloons launched twice daily that sense the amount of water vapor through the depth of the atmosphere).
Map showing flow of moist air across Colorado during heavy rains
This map shows the amount of water vapor through the depth of the atmosphere (color legend at bottom in millimeters; 15 mm = 0.59 inches), as derived from satellite observations. The superimposed arrows show atmospheric flow at various levels, including 850 hPa (usually around 5,000 feet above sea level at this location and time of year), 700 hPa (around 10,000 feet), and 500 hPa (around 19,000 feet). (Image courtesy Sheldon Kusselson, NOAA.)
The transition from intense heat to heavy rain, and the weather features shown in the map, are similar to conditions more typical in July and August as part of theNorth American Monsoon pattern. They’re not so typical for September. 

A MILLENNIUM-SCALE EVENT?

Engineers often refer to NOAA’sAtlas 14 to find frequency estimates: how often to expect precipitation of a given intensity and duration. Russ Schumacher (Colorado State University) used the atlas to calculate frequency estimates for the rains observed in the critical 48-hour window from 6 a.m. MDT Wednesday to 6 a.m. Friday. In doing so, Schumacher found that a large chunk of Boulder County and parts of several other state counties passed the 1000-year recurrence threshold. 
This doesn’t mean that such an rainfall would literally be expected once every thousand years, like clockwork. Rather, it’s a statement of probability: a 1000-year rainfall has an 0.1% chance of occurring in any given year. Such values shouldn’t be taken as gospel—there are important caveats, including the hard-to-model behavior of the most extreme events—but they do suggest how truly noteworthy this week’s rains were.
“I think everyone who lives along the Front Range has known of the potential for a rain event that would produce ‘the next big flash flood’,” says Schumacher. “But I don't think anybody imagined that when it came it would cover such a large area and last so long.” 

FLOODING:  A WATERY RAMPAGE

As for the floods themselves, it’s a bit more complicated to discern their precise rarity. For example, changes in the built environment—how streams are channeled, where parking lots replace fields, and so forth—affect how a flood moves through a watershed. So an identical weather event a century ago might produce a much different flood than the same event today.
Graph showing water levels during flood measured at stream gauge on Boulder Creek near Broadway
A stream gauge at Boulder Creek and Broadway measured two peaks in the moderate-to-major flood range during this week’s heavy rains. (Image courtesy NOAA.)
One of the main tools for measuring flooding is river gauges that monitor streamflow height. Scientists use the long-term records from these sites, along with models of the topography, meteorology, and hydrology of the surrounding watershed, to extrapolate the potential height of worst-case floods. As with the rainfall example above, the results are probabilistic: a “100-year flood” has a 1% chance of occurring inany given year, a 25-year flood has a 4% chance, and so on.
Near downtown, Boulder Creek—as measured just west of Broadway by a U.S. Geological Survey gauge—crested at an impressive 7.78 feet on Thursday evening, with an estimated flow of about 5,000 cubic feet per second (cfs). That’s the highest water observed downtown since the record flood of May/June 1894, when flows were estimated at more than 11,000 cfs and large swaths of downtown were inundated. That 1894 event sawlower precipitation amounts than were observed in much of Boulder County this past week, but the rains were accompanied by major runoff from snowmelt. In contrast, this week’s rains fell on a parched, snow-free landscape—at least one saving grace. 
Why were some of the floodwaters in and near town apparently more extreme than those observed in downtown Boulder? Rainfall isn’t uniform across a region, so a given flood might be more extensive at one point along a river or creek, or in one part of town, than elsewhere. This week’s torrents included pulses of intense downpour embedded in steadier rain, so many smaller tributaries—engorged by these pulses—flowed into roads, homes, and yards where residents had never encountered such water before.

CLIMATE CHANGE: WHAT’S THAT?

One can’t observe an event like this without reflecting on the longer-term, larger-scale picture. As a Climate Central article notes, one of the hallmarks of recent climate change in the United States and many other regions is a shift toward rain and snow being concentrated in more intense bursts, often with longer dry spells in between.
These trends, predicted by climate models, make physical sense. A warmer atmosphere can carry more water vapor, so when conditions are ripe for heavy precipitation, there’s more to work with. Slow-moving weather features also boost the odds of a prolonged event like this one, so researchers are continuing to investigate how and whether atmospheric blocking features will change in a future climate.
Flood waters near Boulder Creek, September 12, 2013
Not the day for bench-sitting: a scene along swollen Boulder Creek on September 12. (Photo by Bob Henson, UCAR. This image is freely available for media & nonprofit use.)
This week’s amazing deluge—which has affected neighboring states as well, includingKansas and New Mexico—should serve as an excellent candidate for an attribution and detection study. Through such work, scientists can use computer models to see how often similar events occur, both with and without the presence of greenhouse gases produced by human activity. It’s then possible to estimate how much the odds of such an event have been boosted by fossil fuel use.
Even when researchers find that a given type of disaster has become more likely, a rare event is still going to be rare—and it can occur without any help from greenhouse gases. That’s why researchers have warned for decades about Colorado’s inherent vulnerability to flash floods. One of those researchers is geographer Eve Gruntfest, now at the National Science Foundation. Her landmark analysis of the Big Thompson disaster (seePDF), which killed 139 people on July 31, 1976—the evening of Colorado’s centennial day—resulted in the “climb to safety” signs now common across the region.
The late Gilbert White (University of Colorado) and his decades of research into flooding and safety are honored by a memorial marker at Boulder Creek and Broadway, showing the heights that floods of various return periods would reach. This week’s water appears to have risen above the 50-year level and topped out somewhere not too far from the 100-year mark.
When might the 500-year level be hit? It’s only a matter of time—though nobody can say exactly how much.

Saturday, September 14, 2013

Update on Colorado Flood


Now that the devastating flooding rains have lessened along the Front Range, information is now being posted as to how rare this event has been.  Following is a blog on the CoCoRaHS site that focuses in on how unusual the rains were in the Boulder area.








Saturday, September 14, 2013


A Year's Worth of Rain in One Week - Colorado Flooding

The devastating flooding along the Colorado Front Range has been headline news this week. No doubt most people have seen photos and video of the flooding and damage - they are all over social media as well as the typical news sites. If you have ever doubted the power of water the images coming out of Colorado should put those doubts to rest. The flooding extended from the Fort Collins area south to the west side of Denver.  The same rivers that bring spring meltwater out of the mountains to irrigate farms and fill community reservoirs along the Front Range are now raging torrents.

This image shows large portions U.S. 36 washed away at the mouth of the Big Thompson canyon

While a large area has been affected, Boulder, Colorado was the epicenter. Here are some climatological facts for Boulder rainfall to help place this in perspective

Boulder's annual precipitation averages 20.68 inches, with an average of 1.68 inches in September.
For September 1-13, the U.S. Cooperative Weather Station in Boulder has received 14.74 inches of rain. This nearly three times the previous monthly September record of 5.50 inches in 1940! This is also the wettest month ever on record for Boulder. The previous record was 9.59 inches in July 1995.

Much of Colorado has been in severe drought or worse for more than a year, and Boulder and much of the area was on track for another very dry year. Through the end of August, Boulder's precipitation for the year was 12.96 inches, which placed it in the top 30 percent of driest years in Boulder.

With the precipitation through September 13th, the total precipitation for the year so far is 27.70 inches, which now makes this year the second wettest on record. The wettest year on record is 1995 with 29.43 inches. There is no question that 2013 will eclipse this mark - the only questions are by how much and when.

Not only did the rainfall so far this month destroy the previous monthly record, but the 9.08 inches recorded on September 12 shattered the precious record of 4.80 inches measured on July 31, 1919..

Source:  National Weather Service Denver/Boulder

While the U.S. Cooperative station in Boulder is the official record, rainfall totals measured by CoCoRaHS observers were just as if not more impressive. Here are the rainfall totals of 10 inches or more for the period September 9-14.

Station No.Station NameTotal Precip# of Reports
 CO-BO-33Boulder 3.3 SE18.366
 CO-BO-72Boulder 1.3 NW15.456
 CO-BO-299Boulder 3.0 S15.295
 CO-BO-9Boulder 1.4 NNW15.056
 CO-BO-4Boulder 2.9 S14.796
 CO-BO-35Boulder 1.5 NW14.756
 CO-BO-14Boulder 1.6 S14.715
 CO-BO-286Boulder 3.5 S14.566
 CO-BO-321Boulder 1.7 S14.135
 CO-BO-337Boulder 1.6 NW14.065
 CO-LR-907Livermore 10.6 W13.954
 CO-BO-288Boulder 0.5 NNE13.886
 CO-BO-120Boulder 3.0 E13.804
 CO-AD-127Aurora 4.2 NNW13.746
 CO-BO-74Boulder 5 SE13.725
 CO-AD-170Aurora 4.5 NW13.135
 CO-BO-234Louisville 2.5 NW13.015
 CO-BO-282Boulder 4.4 S12.995
 CO-BO-164Boulder 3.0 NNW12.796
 CO-BO-230Boulder 6.8 WNW12.285
 CO-BO-219Riverside 2.2 NE12.153
 CO-AR-55Aurora 2.9 NW12.114
 CO-BO-349Boulder 1.2 N12.103
 CO-BO-67Boulder 4.7 E12.005
 CO-BO-243Louisville 2.6 WSW11.915
 CO-BO-202Ward 4.6 NE11.676
 CO-AR-99Aurora 4.1 S11.426
 CO-BO-135Boulder 5.4 ESE11.136
 CO-DN-183Denver 5.1 ENE11.085
 CO-JF-365Golden 2.1 SW10.996
 CO-AR-270Aurora 0.7 WSW10.806
 CO-AR-262Aurora 2.1 W10.786
 CO-LR-749Drake 4.7 SSE10.683
 CO-AR-281Aurora 2.4 SW10.625
 CO-LR-882Loveland 12.2 W10.546
 CO-BO-19Boulder 4.6 E10.455
 CO-JF-63Golden 4.8 NW10.396
 CO-JF-279Pinecliffe 3.1 ESE10.275
 CO-LR-866Estes Park 2.2 S10.056
 CO-AR-264Aurora 3.8 S10.036