Right For The Wrong Reasons

I like to rehash a storm after it departs, compare it to past storms and try to learn something every time something does not go according to plan. By that I mean the models were wrong, I was wrong, the NWS was wrong. But what I am seeing more and more of this year is the errors have been on timing on the heaviest precipitation more than the total amount of precipitation (QPF).

I noticed a couple of times last year and also in 16-17. Throughout the week my concern was that based on the models’ forecast that the bulk of the precip would fall Thursday afternoon until 8 am Friday. Then we would have a swift frontal passage and little more to finish on Friday. The exception was Wolf Creek where it was supposed to be more evenly distributed between the two periods.

I also talked a lot the last couple of days about energy transferring from one storm to another and yesterday talked about the weather party on the Plains. Unfortunately, it is impossible to see this as it is happening (at least for me it is). The surface maps from the NWS are always a few hours old when they post them-you would think there is a better way, but that is what we have to work with. The good news is they are all archived so I can go back to any date and check them out.

Here is 8 am Friday, at this point, we knew the first phase of the storm never materialized as forecasted, the jet streak and moisture never made it far enough north, before moving east to make an impact.

cap15z

Let me set the scene, what you see above you is the cold front and low pressure in Utah approaching Colorado, it is leaning forward, which is called a positive tilting trough. Positively tilted troughs are weakening and increasing in speed. This is opposed to a negatively tilted trough, which is deepening, slowing down and gain strength. Negatively tilted troughs look like they are leaning backward.

In NE Wyoming there is a very strong closed low-pressure system which is attached to a developing low pressure in SE Colorado, you will see the dotted line that connects the two, that is a shortwave trough. Looking back up at the NE Wyoming low you will see a circle around the low, which means it is a closed low. Then you can see outside of that circulation another closed loop of circulation, follow that out one more layer and you will see a third closed loop of circulation, notice that all three lows are enveloped in the third loop? That is the energy being absorbed from one storm to the others.

The next explanation won’t be so long now that you understand the setup. Here is 11 am.

cap18z

The SE Colorado shortwave has become a full-fledged low-pressure system, absorbing the energy from the Utah system headed towards Colorado, but wait it didn’t kill it, it left just a few leftover pieces of energy. Notice the dotted blue line in Utah? That refers to cyclogenesis which means it is trying to become its own storm. Ultimately by around 2 pm it would give up, but while it was trying to make a comeback it was sending those snow squalls our way, a few of them can really bump totals in a hurry.

Here is the 2pm surface map.

cap21z

Now we have a massive system with a double-barrel low already affect the Plains.

Jump forward to right now and you have a massive system affecting the Plains and headed into the Great Lakes.

caplive

In the end, Wolf Creek got 12 inches Purg got 7″, Telluride had 5″ and most of the mid-elevations that I heard from got 3-5″ and 1-2″ with the lower elevations, which was pretty close to what most of us were forecasting, but for the wrong reasons…

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All Storms Headed To The Weather Party on The Plains

The first part of the storm was mostly a failure with the jet streak departing to the east overnight to get involved with a developing low-pressure system which is bringing rain, snow, sleet, and ice to the plains states. We still have a weakening trough to our west progged to come through the area between 9 am and 2 pm. There are questions as to how strong it will be when it comes through. This system is going to do everything it can to get past Colorado and get absorbed into the developing system to the east.

Split flow systems like this look very enticing especially early in the modeling where they kind of lump everything together and show a perfect scenario, as time goes by they start to dissect all of the pieces and parts and highlight certain parameters. Frequent changes right before the systems are set to impact is generally a bad sign, but when you see the totals on the models come up hours before the forecasted onset of precipitation, forecasters who like snow (including myself) tend to believe what they are seeing because it is exactly what they want to see, it is a common condition I refer to as Wishcasting.

I do expect the snow to pick back up, but it will be the beginning of the end for most areas locally. Telluride and areas that favor NW Flow could see snow continuing this afternoon.

Here is a fun fact to remember, last January the last significant snow we got was on January 18th, then we were dry until February 6th. Last February we had 10 storms and set an all-time record for snow in February in most areas.

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New Advisories And My New Totals

Nearly all of the model runs today have increased amounts overall for low and mid-elevations. I am going to bump up a few totals because of this. Wolf Creek unchanged (10-18″). Purgatory unchanged (4-8″). Mayday 6-12″ Pagosa 5-10″. Telluride and Mid-Elevations 4-8″. Durango, Bayfield, Mancos and Ignacio 2-4″. I was on the fence on Telluride but they are now under an advisory so I thought I better bump them up, the models aren’t showing it, but Telluride has a history of making something out of seemingly nothing.

Here are the new and updated highlights.

SAN JUAN RIVER BASIN-
INCLUDING THE CITY OF PAGOSA SPRINGS
258 PM MST THU JAN 16 2020

..WINTER WEATHER ADVISORY IN EFFECT UNTIL NOON MST FRIDAY

* WHAT…SNOW EXPECTED. TOTAL SNOW ACCUMULATIONS OF 3 TO 6 INCHES
WITH LOCALLY HIGHER AMOUNTS IN THE FOOTHILL AREAS.

* WHERE…SAN JUAN RIVER BASIN.

* WHEN…UNTIL NOON MST FRIDAY

INCLUDING THE CITIES OF COLUMBINE, HAHNS PEAK, TOPONAS, ASPEN,
VAIL, SNOWMASS, CRESTED BUTTE, TAYLOR PARK, MARBLE, BUFORD,
TRAPPERS LAKE, TELLURIDE, OURAY, AND LAKE CITY
258 PM MST THU JAN 16 2020

…WINTER WEATHER ADVISORY IN EFFECT FROM 6 AM TO 5 PM MST
FRIDAY…

* WHAT…SNOW EXPECTED. TOTAL SNOW ACCUMULATIONS OF 4 TO 8 INCHES
WITH LOCALLY HIGHER AMOUNTS. WINDS GUSTING AS HIGH AS 50 MPH.

* WHERE…PORTIONS OF NORTHWEST, SOUTHWEST AND WEST CENTRAL
COLORADO.

* WHEN…FROM 6 AM TO 5 PM MST FRIDAY.


* IMPACTS…TRAVEL WILL BE VERY DIFFICULT. BLOWING SNOW WILL
SIGNIFICANTLY REDUCE VISIBILITY, ESPECIALLY ON RIDGE TOPS AND
OVER MOUNTAIN PASSES.

As you read, I am a bit more optimistic about Pagosa then the NWS is. The moisture is still lingering to our south, if for some reason it defies the models and doesn’t make it up here, all bets are off on these totals.

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More Questions Than Answers-Except Wolf Creek

So here we are, it’s Thursday we are supposed to have more model agreement and run to run consistency but we have not, things are flipping back and forth, timing and placement of the jet streak associated with the southern branch of the jet stream are not initializing well with the morning hi-res NAM model run. And that initial moisture surge is the key for accumulating snow west of Pagosa, the passage of the Front on Friday will just be a technicality for most of us, it will be a “was that it?” storm.

I think the only area safe for the good snow we would expect with a decent storm is Wolf Creek where the moisture will get bottled up before Friday’s frontal passage.

Below is the current surface map

Capture

You can see the jet streak and associated moisture streaming in from SE Colorado to the Baja. You also see the “storm” coming onshore in Northern California, unless something changes, that storm is going to be a brief moderate snow and high wind event that won’t stick around most areas for very long. Basically, it would have to dig deeper into the west and find some more moisture to bring with it to affect us differently. At this time the models don’t see that happening. But the models are inconsistent, so we will see.

That moisture is supposed to be streaming up and on the increase this afternoon, increasing late day and this evening before scouring out on Friday.

We have had a change to the wording for the Winter Storm Advisory, which they have upgraded to a Warning. The only thing I hate more than these 2 phase systems (split flow systems) is when the NWS issues a blanket advisory. I call it a blanket advisory because they list a couple of towns down here, then in the wording, they extend the coverage area so it is actually outside of their forecast coverage area. Here is the warning then I will explain what I mean.

INCLUDING THE CITIES OF SILVERTON, RICO, AND HESPERUS
245 AM MST THU JAN 16 2020

…WINTER STORM WARNING REMAINS IN EFFECT FROM 2 PM THIS
AFTERNOON TO 5 PM MST FRIDAY…

* WHAT…HEAVY SNOW EXPECTED. TOTAL SNOW ACCUMULATIONS OF 6 TO
12 INCHES WITH LOCALLY HIGHER AMOUNTS UP TO 18 INCHES POSSIBLE
ALONG THE EASTERN PORTION OF THE SAN JUANS. WINDS GUSTING AS
HIGH AS 60 MPH.

* WHERE…SOUTHWEST SAN JUAN MOUNTAINS.


* ADDITIONAL DETAILS…WHILE ACCUMULATING SNOW WILL FALL
THROUGHOUT THE ENTIRE SAN JUAN RANGE, THE HEAVIEST SNOW TOTALS
WILL FALL ALONG AND SOUTH OF THE US 160 CORRIDOR IN THE
SOUTHERN SAN JUAN MOUNTAINS.

* WHEN…FROM 2 PM TODAY TO 5 PM MST FRIDAY.


It is that last highlight under “Additional Details” that is a problem, how many people around here will read that and assume that since they mention Hesperus in the headlines and “the heaviest snow will fall south of the US 160 corridor in the Southern San Juan Mountains” in the additional details, that it means areas south of 160 in La Plata County?

That is not at all the case, they are referring to this area south of the 160 corridor.

ink

What they are referring to is the area of the San Juan Wilderness south of Wolf Creek and east and southeast of Pagosa, pretty much where nobody lives.

I am sure it made sense to the person who wrote it, but this is another reason that I think it is a mistake to include areas that are outside their forecast area, which it is.

As far as the rest of the Warning, it is not a big deal to pick up 6 inches of snow between Purgatory and Red Mountain, you don’t even need a storm just a little moisture and lift and you can hit the 6″ or more. The Warning portion comes in because of the wind, a couple fresh inches of snow with wind gusts to 65 mph creates a dangerous situation and if you are caught in a squall of blowing snow on 550 during the frontal passage tomorrow you are going to feel like you are in a major storm.

I am not trying to nitpick, I just want to make sure people understand what they are reading and to understand the meaning.

So where does that leave us? All of the models are expecting the majority of the snow to fall in the 18 hour period between 11 am today and 5 am tomorrow, then the snow will increase as the front goes through tomorrow and ends fairly quickly after that.

Based on what I am seeing this morning here is what I am thinking for accumulations.

Wolf Creek 10-18″. Purgatory,  Mayday, and an area from Vallecito southeast over to Pagosa 4-8″. Telluride 3-6″. Mid-elevations 2-5″. Durango, Bayfield, Aztec, Bloomfield 1-3″. Farmington, Cortez and Mancos trace to an inch. Based on what I see later today I may split up the mid-elevation areas and bump things up for the eastern portions of La Plata County.

I will be updating a couple of more times today, stay tuned.

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Advisory Issued

They are hinting at the big totals for Wolf Creek. Technically Wolf Creek is not in Grand Junction NWS’ forecast area, it belongs to Pueblo. Traditionally you don’t forecast out of your area, but one of the younger ones actually mentioned Wolf Creek in their forecast, just a little weather nerd drama.

URGENT – WINTER WEATHER MESSAGE
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
216 PM MST WED JAN 15 2020

COZ019-161300-
/O.NEW.KGJT.WS.A.0001.200116T1200Z-200118T0000Z/
SOUTHWEST SAN JUAN MOUNTAINS-
INCLUDING THE CITIES OF SILVERTON, RICO, AND HESPERUS
216 PM MST WED JAN 15 2020

…WINTER STORM WATCH IN EFFECT FROM THURSDAY MORNING THROUGH
FRIDAY AFTERNOON…

* WHAT…HEAVY SNOW POSSIBLE. TOTAL SNOW ACCUMULATIONS OF 6 TO 12
INCHES WITH LOCALLY HIGHER AMOUNTS UP TO 18 INCHES POSSIBLE
ALONG THE EASTERN PORTION OF THE SAN JUANS. WINDS COULD GUST AS
HIGH AS 60 MPH.

* WHERE…SOUTHWEST SAN JUAN MOUNTAINS.

* WHEN…FROM THURSDAY MORNING THROUGH FRIDAY AFTERNOON.

* IMPACTS…TRAVEL COULD BE VERY DIFFICULT. PATCHY BLOWING SNOW
COULD SIGNIFICANTLY REDUCE VISIBILITY

I will revisit this tomorrow.

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A Slight Delay For The Snow

How many times have we said that? It is pretty normal for the models to be too fast with the arrival of the precipitation, it is usually the last 48-24 hours before the arrival that they figure it out. So now we are looking at light snow starting a little later in the afternoon as moisture jumps a ride on a jet streak and moves north into our area.

Here is what that jet streak looks like tomorrow at 2 pm. You can see the little green area coming over the four corners

jetstreak.png

Here is the light snow over the area by 5 pm.

euro5pmth.png

Here is a zoomed-out version showing where the trough is in the west at the same time.

eurotroughth5pm.png

By 2 am Friday you can see the trough moving closer and start to nudge the moisture east.

euro2amfri.png

By 8 am Friday a piece of the initial energy from Thursday is developing into a storm on the plains and the remaining moisture has been caught up by the trough. The cold front is draped across Utah splitting the state in half.

8amfri.png

Snow should continue until late Friday then this system is going to merge into the Plains/Upper Midwest storm. The best news we could get would be another delay of 6 hours on Thursday. I don’t expect the trough to be delayed any further on Friday.

I don’t like two-phase storms like this but they sometimes leave left-overs so we could have that to look forward to. I have been vocal about these types of storms all week and don’t want to rehash everything. I think the models are finally handling this storm a little better. We still have 24 hours of model runs, anything can happen but as you can see the totals have come down, I tried cautioning everyone all week that there was a lot that had to go right to achieve some of the totals we saw in the early model runs.

Here is the GFS

gfs-deterministic-colorado-total_snow_10to1-9348800.png

Here is the Euro

ecmwf-deterministic-colorado-total_snow_10to1-9348800.png

Here is the Canadian

gem-all-colorado-total_snow_10to1-9348800.png

Tomorrow I will do a couple of Updates throughout the day so stay tuned, I still expect Wolf Creek to do a foot or better, but I will dial in the “bullseyes” around 9 am tomorrow.

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SWS from NWS

Here is how to interpret this: “We are still very uncertain how this is all going to come together, so uncertain that we normally would have issued a Winter Storm Watch by now, but the models can’t seem to agree if there will be any snow accumulation below 7,500′ until Friday. We are going to go ahead and leave it up to the next shift to determine how aggressive they want to get on the advisory or warning”


INCLUDING THE CITIES OF RANGELY, DINOSAUR, CRAIG, HAYDEN, MEEKER,
RIO BLANCO, COLUMBINE, HAHNS PEAK, TOPONAS, STEAMBOAT SPRINGS,
GRAND JUNCTION, FRUITA, PALISADE, COLLBRAN, DE BEQUE, NEW CASTLE,
MESA, PARACHUTE, RIFLE, SILT, EAGLE, EDWARDS, GLENWOOD SPRINGS,
CARBONDALE, BASALT, SKYWAY, ASPEN, VAIL, SNOWMASS, MONTROSE,
HOTCHKISS, DELTA, CRESTED BUTTE, TAYLOR PARK, MARBLE, BUFORD,
TRAPPERS LAKE, GUNNISON, CIMARRON, RIDGWAY, GLADE PARK,
TELLURIDE, OURAY, LAKE CITY, SILVERTON, RICO, HESPERUS, GATEWAY,
NUCLA, CORTEZ, DOVE CREEK, MANCOS, DURANGO, BAYFIELD, IGNACIO,
PAGOSA SPRINGS, BLANDING, BLUFF, MEXICAN HAT, MANILA, DUTCH JOHN,
VERNAL, JENSEN, BALLARD, FORT DUCHESNE, RANDLETT, MOAB,
CASTLE VALLEY, THOMPSON SPRINGS, MONTICELLO,
CANYONLANDS NATIONAL PARK, DEAD HORSE POINT STATE PARK,
AND FRY CANYON
236 AM MST WED JAN 15 2020

A STRONG STORM WILL BE MOVING ACROSS EASTERN UTAH AND WESTERN
COLORADO STARTING TOMORROW AFTERNOON AND PERSISTING THROUGH
FRIDAY EVENING. THIS FAVORABLE WEATHER PATTERN MAY BRING MODERATE
TO HEAVY SNOWFALL TO THE SAN JUAN MOUNTAINS STARTING LATE
TOMORROW. THIS SNOW WILL SPREAD TO THE REMAINING MOUNTAIN RANGES
TOMORROW NIGHT INTO FRIDAY. THE PEAK SNOWFALL RATES LOOK TO OCCUR
ON FRIDAY MORNING, WHICH COULD IMPACT TRAVEL.

SOME UNCERTAINTY REMAINS ON THE EXACT TRACK AND STRENGTH OF THE
SYSTEM, BUT EARLY INDICATIONS ARE THAT A MAJORITY OF THE MOUNTAIN
PASSES WILL BE IMPACTED, ESPECIALLY FRIDAY. IN ADDITION TO THE
HEAVY SNOW POTENTIAL WIND GUSTS COULD REACH 40-60 MPH IN THE
HIGHEST ELEVATIONS CAUSING LOW VISIBILITY AND DRIFTING SNOW.
ANYONE PLANNING TO TRAVEL ACROSS EASTERN UTAH OR WESTERN COLORADO
SHOULD MONITOR THE LATEST FORECAST AS THIS WINTER STORM MOVES INTO
THE REGION.

I will do a model update around noon, yesterday the models were putting most of their eggs in the Thursday basket, overnight they seem to have changed to a slower arrival and stronger storm Friday, it should be interesting.

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Thursday and Friday Storm Update

 

Yesterday at the end of my post I said the following: “to the extent that it is ever possible, this (upcoming) storm appears that it will be more forecastable than the difficult storm cycle of NW Flow storms we have had so far in January.” Today, that is not exactly the case.

When I first started tracking the next storm(s) It looked like we would have a trough come in from the west and merge with a subtropical plume of moisture and dump snow Thursday through late Friday. I guess it could not stay that easy. So we’re right back to a two-part storm where moisture is supposed to move into NW New Mexico and then move north over our area Thursday during the day. While that is happening a trough will march towards the area late Thursday and absorb the moisture and energy before moving into the Northern Plains late Friday.

If everything goes perfect everyone will be happy with a lot of snow. In the past, we have seen this set up go wrong in several ways. The moisture has gotten pushed further east like it did early Monday morning, or it stays further south and we never see the moisture in our area. Or just a hint of the moisture comes north for low totals and the main trough jumps us to marry up with the other system and deepen on the plains.

Lots of scenarios with only one scenario that delivers a lot of snow and that is the perfect storm scenario. The Euro and Canadian still mostly favor that solution, although they are trending towards a solution that brings the heaviest snow to the east. The latest GFS brings a slight amount of moisture over our area favoring Archuleta County and then speeds the trough through without deepening it to our west, which is classic GFS bias.

Here is the latest GFS run

gfs11412z.png

German ICON

icon11412z.png

Euro

euro11412z

Canadian

cmc11412z.png

The other thing I have not yet discussed is the temperature factor, we will be under SW flow and subtropical moisture flow, that means it is likely the low elevations will see melting during the day Thursday before the colder air filters in early Friday.

Wolf Creek should do very well again in nearly every scenario, the only question is will it be just a foot there or will it be another two feet or more. If you have not been keeping track of Wolf Creek, amazingly, they have had more snow this year than last year. They hit 220 inches yesterday, last year they were at 167 inches at the same time.

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Wolf Creek Wins

Dozens of model runs showed light snow overnight with a band of heavier snow developing and heading east leaving those “bullseyes” over Wolf Creek as it departed. Everything was going according to plan with the light snow but then the heavy band of snow set up over Wolf Creek with deep southerly flow, it missed most of us to the east.

That is the problem with smaller storms if they don’t come right over you you can get missed. I will be anxious to see how deep it gets at Wolf Creek today, a couple of hours ago they were already at 14 inches and it is still dumping.

On to the next storm, Thursday & Friday it looks like we will have a favorable setup, slightly warmer and a lot more moisture, similar to what we were getting in December. The Euro has jumped into the deep end of the pool, while the GFS and Canadian have shown some restraint since yesterday’s model runs.

Speaking of the Euro here is its latest operational run.

euro11312z.png

Here is the German model

icon11312z.png

Here is the GFS

gfs11312z.png

And last the Canadian model

cmc11312z

So over a 24 hour period, the Euro has swapped places with the Canadian model as the outlier.

We still have a couple of days, but I like the trend and to the extent that it is ever possible, this storm appears that it will be more forecastable than the difficult storm cycle of NW Flow storms we have had so far in January.

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Advisories Issued

The afternoon forecast package included advisories included a couple of Winter Weather Advisories.

SOUTHWEST SAN JUAN MOUNTAINS-
INCLUDING THE CITIES OF SILVERTON, RICO, AND HESPERUS
226 PM MST SUN JAN 12 2020

…WINTER WEATHER ADVISORY IN EFFECT FROM 6 PM THIS EVENING TO
6 PM MST MONDAY…

* WHAT…SNOW EXPECTED. TOTAL SNOW ACCUMULATIONS OF 5 TO 10 INCHES
WITH LOCALLY HIGHER AMOUNTS NEAR WOLF CREEK PASS. WINDS GUSTING
35 TO 50 MPH NEAR AND ABOVE TREELINE CREATING AREAS OF BLOWING
AND DRIFTING SNOW.

* WHERE…SOUTHWEST SAN JUAN MOUNTAINS.

* WHEN…FROM 6 PM THIS EVENING TO 6 PM MST MONDAY.

* IMPACTS…TRAVEL WILL BE DIFFICULT WITH BLOWING SNOW
SIGNIFICANTLY REDUCING VISIBILITY AT TIMES.

 

UNCOMPAHGRE PLATEAU AND DALLAS DIVIDE-
NORTHWEST SAN JUAN MOUNTAINS-LA SAL AND ABAJO MOUNTAINS-
INCLUDING THE CITIES OF RIDGWAY, GLADE PARK, TELLURIDE, OURAY,
LAKE CITY, AND MONTICELLO
226 PM MST SUN JAN 12 2020

…WINTER WEATHER ADVISORY IN EFFECT FROM 6 PM THIS EVENING TO
6 PM MST MONDAY…

* WHAT…SNOW EXPECTED. TOTAL SNOW ACCUMULATIONS OF 4 TO 8 INCHES
MAINLY ABOVE 8500 FEET WITH LOCALLY HIGHER AMOUNTS POSSIBLE.
WINDS GUSTING 35 TO 50 MPH NEAR AND ABOVE TREELINE CREATING
AREAS OF BLOWING AND DRIFTING SNOW.

* WHERE…IN UTAH, LA SAL MOUNTAINS. IN COLORADO, UNCOMPAHGRE
PLATEAU AND DALLAS DIVIDE AND NORTHWEST SAN JUAN MOUNTAINS.

* WHEN…FROM 6 PM THIS EVENING TO 6 PM MST MONDAY.

* IMPACTS…TRAVEL WILL BE DIFFICULT WITH BLOWING SNOW
SIGNIFICANTLY REDUCING VISIBILITY AT TIMES.

Good call, review my noon post if you haven’t, next Update Monday.

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