I have spent a fair amount of time with the models this morning and I realized I need to change things up a bit. I usually like to try to break things down bit by bit, one storm at a time etc. However, looking at the models I don’t think I have done a good enough job preparing the people who live at higher elevations for the next two storms. The dividing line between deep and mush seems to hover between 7,000 and 8,000 feet. There are a lot more people who live below 8,000 than above. When you are dealing with such a small change in elevation for the rain versus heavy snow line, more people should probably be listening in.
I have talked about this a couple of times earlier in the week but what we are up against is a strong arctic airmass to our north and northeast and an upcoming subtropical pool of moisture to our southwest. Here is a regional view of what that looks like.
This is the depiction for Saturday night between 5 pm and 11 pm. Find the thick blue line that says 540, you can follow that from where it enters southeast Colorado then it slices through the middle of the state at an angle then rests on the border of northwest Colorado and southwest Wyoming, if you wish you can track it all of the way through southern Oregon where it goes offshore. Everything to the east, northeast, and north of that solid blue line is the cold front.
Below I have zoomed in a bit on the Arctic airmass.
Behind the coldfront, you will see dotted blue lines that decline in increments of 6, starting with 534, then 528, 522, 516. You will also see 1044 with an H below it. That is Arctic source air. On the southwest side of the solid blue 540 line, you will see a solid red 546 line. The 546 line is roughly the level where snow falls at 6,500 feet. If you look south of that you can barely see the 552 line which is snow at roughly 8,000 feet.
Here is a close-up view
So, in this case, the model is expecting snow at 6,500 feet and above.
What I am getting at here is a little movement in the front can go a long way in affecting our forecast. So as much as I try to narrow things down just a little movement in that airmass could cause a lot more snow for people than I think they are anticipating.
Here is the latest Winter Storm Warning (WSW) from the NWS
NORTHWEST SAN JUAN MOUNTAINS-SOUTHWEST SAN JUAN MOUNTAINS-
INCLUDING THE CITIES OF TELLURIDE, OURAY, LAKE CITY, SILVERTON,
RICO, AND HESPERUS
415 AM MST FRI MAR 1 2019
…WINTER STORM WARNING IN EFFECT FROM MIDNIGHT TONIGHT TO NOON
* WHAT…SNOW…MODERATE TO HEAVY AT TIMES…IS EXPECTED. TOTAL
SNOW ACCUMULATIONS OF 8 TO 16 INCHES EXPECTED, WITH LOCALLY
HIGHER AMOUNTS UP TO 24 INCHES. WINDS GUSTING AS HIGH AS 40 MPH.
* WHERE…NORTHWEST SAN JUAN MOUNTAINS AND SOUTHWEST SAN JUAN
* WHEN…FROM MIDNIGHT TONIGHT TO NOON MST SUNDAY. HEAVIEST SNOW
RATES EXPECTED SATURDAY AFTERNOON AND EVENING.
* ADDITIONAL DETAILS…TRAVEL COULD BE VERY DIFFICULT, ESPECIALLY
OVER RED MOUNTAIN PASS, COAL BANK PASS AND OTHER HIGH ELEVATION
ROADS. BLOWING SNOW COULD SIGNIFICANTLY REDUCE VISIBILITY.
A WINTER STORM WARNING FOR SNOW MEANS SEVERE WINTER WEATHER
CONDITIONS WILL MAKE TRAVEL VERY HAZARDOUS OR IMPOSSIBLE. IF YOU
MUST TRAVEL, KEEP AN EXTRA FLASHLIGHT, FOOD AND WATER IN YOUR
VEHICLE IN CASE OF AN EMERGENCY.
THE LATEST ROAD CONDITIONS FOR THE STATE YOU ARE CALLING FROM CAN
BE OBTAINED BY CALLING 5 1 1.
The worst time to travel will be Saturday afternoon until Sunday morning. Late Sunday afternoon and evening travel could become difficult again. As far as these amounts go I think it is a good start, but for the most part too low. And it looks like we could do this all over again Wednesday-Friday next week.
I will update later today and we’ll see if there are any updates on snow levels, and look at some of the latest model predictions on precipitation, but I wanted to get this circulating early because I know people are traveling this weekend.