August Climate Outlook for the San Juans

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Joe with a Prescott College Snow Studies/Avalanche program back in another century.

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Joe Ramey is a recently retired NWS weather forecaster/climatologist and leads the charge for Mountain Weather Masters based in the San Juan Mountains of Colorado.

Hello Mountain Weather Masters,

July 2017 started out hot as a ridge of high pressure amplified over the Great Basin. Regional temperatures soared well above normal, and this matched the climate normals that the first half of July is the hottest time of the year. We hit 102F here in Junction on the 5th-7th & 9th and that will probably be the hottest temperatures of 2017 here. By the 10th, the ridge axis had shifted east of the Continental Divide. Clockwise rotation around the high allowed subtropical moisture from the south to work up into Colorado. So the monsoon moisture arrived in Colorado on 10 July this year.

Climate sites in the region are showing July 2017 temperatures well above normal. Through 24 July, above normal temperatures ranged from +1.5F at Montrose to +8.4F at Salt Lake City. After a dry June, July precipitation totals were still behind normal. Of the 12 sites I look at, only Meeker, Grand Junction, and Moab were above normal. Since we are in the depth of monsoonal flow right now, I would expect the month to end up wetter than normal for the region.

In the latest outlook from the CPC, you can see they expect the monsoon season to be robust with wetter-than-normal odds centered on the Four Corners for August and the Aug-Sep-Oct. In the temperature outlook, you can see that the expected widespread showers and clouds help to keep the Desert SW not as warm as the rest of the country. The climate change signal has the entire country warmer than normal for the Aug-Sep-Oct season.

Conditions in the Pacific are again not showing much change. The Nino 3.4 region along the equator is a bit warmer than normal. The best forecast is for ENSO to hover in the warm side of Neutral or perhaps a weak El Nino. Further north in the Pacific, the northern basin remains unremarkably warmer than normal.

Now going way out there, into the summer of 2018, the CPC continues to show a strong warm signal for the next 12 months especially over the Desert SW. The long-range precipitation outlook shows lots of EC (Equal Chances) or low forecast skill.

Enjoy this manna from heaven, but stay out of the slot canyons for awhile. 🙂

Best,
Joe Ramey

Monsoon arrival in the San Juans?

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The strong ridge of high pressure that has been parked over the intermountain west since June will remain to our west through tomorrow then will move east of the continental divide Monday allowing southerly flow to develop.  This will draw sub-tropical moisture northward bringing a better chance of rains to develop over mountainous terrain and possibly the higher valleys.  RH will increase during the week with cooling temperatures.  This could be the beginning of the monsoon season …  the latest 8-14 day forecast is typical mid/late-July with warm temperatures and increasing chance of active weather (showers and thunderstorms).

San Juan weather/climate conversation with Joe Ramey ~ former NWS forecaster and now headmaster at Mountain Weather Masters

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Hello MWM,

June is typically hot and dry, 2017 has been particularly so. After some measurable rain in the first week of June it has been dry. Convection the last few days have been high based producing mostly outflow winds and little rain. High based thunderstorms are expected with the Friday cool front.

Climate sites in the region are showing June 2017 temperatures well above normal, 4 to 7 degrees above which is a lot. Their precipitation totals are way behind normal on this the average driest month of the year.

No hints of the monsoon yet but conditions are developing as they should. As I have mentioned before, I believe it takes a near complete melting of the snowpack and a hot period to create regional thermal low pressure to suck in the subtropical moisture from the south. Snowpack in the San Juan, Rio Grande, and Gunnison river basins have basically melted out, while the central and northern mountains still have above normal snowpack. So we don’t know when yet but the monsoon moisture is on track to reach at least southern Colorado sometime in July.

In the latest outlook from the CPC, you can see they expect the heat to continue. There is also a dry signal for central-northern Colorado which may be due to the lingering snowpack.

Conditions in the Pacific are not changing much. The Nino 3.4 region along the equator is a bit warmer than normal. The weak forecast for a developing El Nino late this summer has changed. Now the best chances are for ENSO Neutral conditions into the fall season. ENSO Neutral are wild card seasons because there is no forecast tendency. If El Nino does develop later this year, the best forecast for now is for a weak event. Further north in the Pacific, the northern basin remains warmer than normal but well below 2014-2015-2016.

From those climate signals as well as climate change signals, you can see the CPC shows a strong warm signal for the next 12 months. The long-range precipitation outlook shows lots of EC (Equal Chances) or low forecast skill. There does seem to be a signal for a good monsoon season through the rest of the warm season. There is also a dry signal for the northern Rockies next winter, perhaps a remnant of the El Nino forecast. There is also a dry signal for the Desert SW into the Four Corners next spring.

Stay cool out there.
Practice lightning safety.

Best,
Joe Ramey

San Juan Mountains Weather Forecast ~ Thursday, March 30, 2017 @ 08:30

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Mostly Colorado blue skies will soon fade with radar on Grand Mesa showing invading clouds on the Utah border as I write this forecast at 07:30. A powerful storm system birthed in the Pacific Northwest is riding up and over the Serria today and will close off into low pressure system in the Great Basin this afternoon. As the low deepens and builds it will drop into the 4-corners bringing showers and thunder snow this afternoon into the southern San Juan Mountains with warm temps in place in the lower elevation then gradually turning to snow above 9,000′ tonight with cooling temps.

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Models are not in agreement with the forecast but do show prevalent convective storms that will precipitate with vigor wherever the convective cells/bands form but exact locations are impossible to forecast. A warm atmosphere in the lower elevations early today put rain/sleet below 8,000′ and initial snow levels above that #. This system should bring good storm totals depending on your location but we should see between 10-14″ on southwest facing terrain above 10,000′ with the potential of 2′ or more in those secret and favored locations. These pinched off 4-corner lows (happening Friday-see pressure/precip map below) can wobble around and create good precipitation rates over a long period of time.

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Three models have this storm system affecting the San Juans through Saturday with precipitation diminishing from NW to SE through the day. A brief ridge of high pressure builds Sunday then the next storm of this progressive spring pattern should arrive Monday evening and last through Tuesday then clearing beginning Wednesday.

San Juan Mountains Snow/H20 24 hr totals ~ 3/26/17 @ 09:00

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A prolonged period of very heavy snowfall in the early morning hours favoring RMP and north. Snowfall exceeded 2″/hour. This high precipitation intensity triggered multiple slides along the corridor. Snowfall has since tapered and (reportedly) will continue to do so throughout the morning. Nearby Telluride received 12″-13.5″ overnight. .

24 hour snow/water
Monument 11″/.75″
RMP 8″/.6″
Molas 3″/.25
Coal Bank 3″/.3″

San Juan Mountains Weather Forecast ~ Saturday, March 25, 2017 @ 13:20

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High cirrus have begun their invasion of the San Juans this morning announcing a series of soon to arrive spring storms beginning tonight traveling on southwest flow. By late afternoon the quick hitting open wave should bring windy conditions, rain/sleet to the lower elevations and snow above TL through Sunday morning. Not much juice with this disturbance so don’t expect more than 8-12″ of snow in the high country.

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A short lived ridge of high pressure will build tomorrow with some clearing then Monday through mid-week a more complex storm system brewing in the Pacific NW will slide into the desert southwest on Tuesday. The three models I watch all have a cutoff low forming over the 4-corners later Tuesday that should spin moisture into the central and southern mountains beginning late Tuesday/early Wednesday morning as another spring storm with up to an inch of liquid to spread in the mountainous terrain above 10,000′.

Wednesday into Friday unsettled weather prevails with NW flow remaining in the area until another spring storm moves into the area by late Thursday into Friday… Finally our unsettled spring conditions!

Tuesday’s 4-corner/cutoff low

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