Monday, August 21, 2017

Eclipse Day On

What clouds are around this morning should have either dissipated or moved south of the Eclipse path by Eclipse time.

Forecast  Cloud Cover at Noon Monday Eclipse Day

Satellite photo taken at 0800 MDT Monday August 21 2017

Sunday, August 20, 2017

Eclipse Cloud Forecast Day1

It is just 24 hours prior to the passing of the Eclipse across Southern Idaho and Wyoming.  It now seems assured that the path of the Eclipse will be only marginally affected by high clouds as a weak upper trough moves across and mainly north of Wyoming.

The latest cloud forecast from the NGM model shows as has been the case for the past couple of days a rather thin band of high cloudiness translating southeast across southeast Idaho and Wyoming during the morning,  mostly just prior to the eclipse.

NAM model of  the percentage of forecast cloud cover at noon Monday August 21 2017.

The 300 MB(30,000ft  MSL) forecast for noon shows the very weak upper trough passing across the area with the mostly high band of  clouds moving with it.

NAM 300 MB forecast for noon Monday August 21 2017
Examining the forecast model sounding for around Star Valley at noon Monday, indicates a continued  very dry air mass, marginally supportive of upper level clouds.

Vertical  forecast sounding vicinity Star Valley noon August 21 2017(green dewpoint, red temperature)

 The only other issue may be some smoke from remaining fire activity across the mountains of Idaho, however this should be lessened from a week ago as most of the fires  have been diminished by showers and fire fighting efforts.

Saturday, August 19, 2017

Friday, August 18, 2017

Day 3 Eclipse Cloud Forecast

All the models that were run this Friday morning suggest that there is still a concern that clouds could be a factor in eclipse viewing on Monday.  At this time it appears that the clouds will be primarily higher clouds and likely not completely block the sun as the Eclipse tracks across Southern Idaho and Wyoming around mid day.

The first cloud forecast for noon Monday is from the GFS  that was run this morning.

Forecast of percentage sky cover for noon Monday from the GFS Model

Fortunately skill levels in forecasting cloud cover 3 days in advance is unreliable, as the band of clouds across Southeastern Idaho and Northwest Wyoming could be an issue for ideal eclipse viewing.

The GEFS forecast which is an ensemble of 20 different model solutions each starting with slightly different initial conditions, is more optimistic. Some cloudiness would be present,but not as solid as the GFS.

GEFS forecast of percentage cloud cover for Noon Monday

A third model the NAM is similar to the GFS with a band of clouds across Southeastern Idaho and Northwest Wyoming.
NAM forecast of percentage cloud cover at Noon Monday 8/21/17

The next chart is the GFS model forecast relative humidity at the 300 MB level, or around 30.000 feet.  The band of  high humidity coincides with the cloud cover forecast at that time.

Forecast of 300 MB humidity at Noon Monday.

The next chart is the forecast relative humidity at 700 MB, or about 10,000 above sea level.  This suggest that moisture for clouds will be above 700 MB and most likely at the cirrus level.  

All these forecast suggest a concern for at least high level cirrus and possibly some clouds at mid levels. Thus there remains a concern for at least some clouds to deal with during the Eclipse, but some three days ahead, forecasting cloud cover is still very difficult

Thursday, August 17, 2017

Day 4 Eclipse Cloud Forecast

It is now just 4 days from the Eclipse. The Numerical models should be getting a better handle on the amount of clouds that will possibly interfere with Monday's Eclipse show.

Looking at the GFS model which is the primary source of longer range forecast, there is still some concern that clouds will be an issue.

Percent of cloud coverage forecast from the GFS model for noon Monday August 21 1917

Another model to evaluate is the GEFS(ensemble GFS) which is a composite solution of running the GFS model given slightly differing initial conditions. Similar to a consensus opinion.  This GEFS solution for mid day Monday provides a much more positive solution for the likelihood of interfering cloud cover.

GEFS forecast for percentage of cloud cover for noon Monday August 21 2017.

Again the forecasting of cloud cover in many ways is more difficult than precipitation 4 days ahead.  However both forecast are encouraging that cloud cover will be limited on Monday over Wyoming and Southern Idaho.

Wednesday, August 16, 2017

Cloud Cover Forecast for the Eclipse Path on Monday August 21 2017

As of mid day Wednesday, it is just 5 days before the much anticipated Total Solar Eclipse will be tracking across Wyoming.  While forecasting cloud cover is risky at best 5 days in advance most places,  the numerical models are now within range to begin having some skill to do so.

Climatology would suggest that the morning hours(time of the eclipse event) would have the best chance of minimal clouds.  Typically cumulus develop over and near the mountains by late morning, leading to the possibility of thunderstorms during the afternoon hours.

The GFS model which is the primary forecast model for the United States produces a new forecast every 6 hours which extends out for 384 hours.  Thus it produces a new cloud cover forecast for the time of the eclipse every 6 hours.

Below is the forecast cloud cover from the GFS model generated at noon Wednesday for mid day on Monday over the U.S.

Cloud Cover Total  (%) valid at Noon Monday August 21 2017

This forecast suggests that the area from Oregon into Idaho  has a good chance of favorable eclipse viewing conditions, with some concern for cloud cover over much of Wyoming.

Again this is still 5 days out, and forecasting cloud cover is little better than a crap shoot at that range.  
Below is the model forecast from 24 hours earlier for the eclipse time of noon Monday.

Cloud Cover Total  (%) Forecast valid at Noon Monday August 21 2017

Similarities exist from forecast to forecast,  In the case of Wyoming much of the eclipse path would be seeing minimal cloud cover along the path, but greater concern just to the south.

Will continue to monitor new model forecasts for cloud cover along the Eclipse path, particularly Wyoming and southeast Idaho.

Sunday, August 13, 2017

Late Summer Snake River Reservoir Levels Remain High

Water levels on the  Upper Snake River System remains well above normal as summer  enters the final weeks.  The benefit of last winters large snow pack has kept the reservoirs near full.

Palisades Reservoir which reached 100% on July 1st  and on August 13th remains at 98%.


In comparison the Palisades content this year is almost triple 2016 for the middle of August and about 50% above normal levels.

Jackson Reservoir also is still well above 90% of capacity
 and well above what would be normal levels for mid-August

The entire storage  system of the upper Snake River System is 84%

This amount is about double that which is the average for mid-August.