Good late Monday Folks,
Quite a nice Afternoon on Monday. Winds did taper off but the breeze did mix out the Atmosphere and propelled the Temperatures in the Mid-Upper 40s and Lower 50°s in Central & Southeast WY.
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| NAM by Tuesday 11PM |
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<< Now its onto the "Next" Storm, beginning early Tuesday in Western and Northern WY. A piece of energy drops down from ID/MT and moves into WY with Cooler Air and then Precipitation. Afternoon for Central WY looks to a Mixture of Rain/Snow with very minimal Accumulations but once the Energy increases in the colder air at Night, SNOW is possible along and East of the Laramies near Cheyenne.
Not just the NAM hinted it Tonight, the GFS Model showed signs of the same impulse in Southeastern WY.
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| GFS by Tuesday 11PM |
<< Northwest Flow moves through too as a Front drops down bringing that Disturbance along I-25. Some data suggests the Moisture will run parallel along I-80 and could increase in intensity past 5PM in Southeast WY through the early Overnight Hours.
<<NOT A FORECAST, but the NAM Model shows anywhere from 1-6" is possible for Cheyenne area and near 4-8" in the Southern Laramie Range. The Iowa St. Meteogram suggested about 3-6" for Cheyenne so you can likely see Light-Moderate Snowfall Amounts on this one with heavy bursts at times of 1"/HR in the Evening.
Here's what I am going for through the Afternoon on Tuesday for right now. I do think my amount could be on the Lesser End, but we will see how the Morning Data takes the Storm into account for Southeast WY. Even the Wind River Basin could stay dry on this one, but a chance is possible for many.
Good Sunday Folks,
MUCH Drier, More Sunshine, and Not as Cold. I think much of Central and Southeastern WY dodged a bullet on this Storm; though a few spots in Lower Elevations saw some good snow like Wheatland with 10" & Torrington with 8". Casper did see the Highest (city) amount in Central WY where 4-8" fell.
* I know many are probably pointing the finger at the National Weather Service or us about not getting the Foot of Snow many expected or wanted. When we Forecast an Amount for a certain city or region we say ..." you can expect anywhere from so-so to so-so inches" Some cities are different in Elevation with different Topographical characteristics that could affect a storms progress or outcomes. Especially in Casper we have like a 300 feet difference of Elevation from the Airport on the Plain while the City is in a Bowl and a 8000ft Mountain just a few Miles South of Downtown. Riverton is in a Basin and so is Lander, but Lander is near the Wind River Range.
You can see the Previous Post of looking at the FINAL Snow Reports for Central & Western WY. As it shows, if you live in Lander: " you could have seen anywhere from 8 to 12 Inches or maybe a little more"
As you probably can tell, some spots were on the Lower End of the Forecast Amounts. I can honestly tell you this was going to be a very Difficult Forecast to predict. Moisture was there as Weather Models were very consistent each Night for tremendous Snow along the Laramies.
WHY Heavy Snow didn't develop a Long Duration??
1) Dry Air: The Dry Air was really increasing as we neared the onset of Saturday Morning through the Afternoon. I said an Arctic Air invasion will blast through the High Plains and it actually shifted a little West for much of Central WY too. Highs were only in the Lower Single-Digits. Moisture takes a very hard time to fall at an intense rate with Cold Air (which is denser) in the Winter to punch through. What it does, it eats it away.
2) Upper Air Dynamics & Lifting: I explained in a Blog Post this week about Isentropics and Upslope Flow. This was a setup for Isentropics ~ Over-Running Moisture of rising air moving over from one air mass to another. We had SO MUCH Moisture from CA feeding Northeast into WY with this storm. It was still very warm in UT and as our Cold Front stalled along I-25/Central WY, our Temperatures were cold enough for Snow once it fell. A band of moisture set up from Sweetwater/Carbon Co and streamed into Natrona County late Friday Night. RAIN was fallen in Rawlins and mixed Precip near Rock Springs but that transition to all Snow about 50-100 Miles North.
Image Below of what Isentropic Lift is Like.
What Favors our Pattern here in Central and especially Southeast WY is Upslope Flow. A deep area of Moisture a new Low can form on the Lee-side (right side) of a Mountain Range can wrap around Moisture and interacts with a High Pressure.. Its a counter-clockwise flow of Wind that can cause a Heavy-Moderate snowfall rate for Mountains and cities that are tucked in along the Foothills. THIS was a setup that was prime for Late March- April with our Snow Events here in WY.
We do our very Best to Inform you the Potential of what can occur for you and your families if a certain event poses threat. I am a Meteorologist and we use Model "Guidance" as a Tool to use while Forecasting while we check Upper Air Data and other Forecasters for insights during these events. Once it starts we Now-Cast and check Radar, Ground Truth Reports, and Water Vapor/Infrared Imagery of where the worse is occurring or could happen. If anyone wants to blame anyone, its Mother Nature. It takes experience for at least a few years to get a grasp of how certain events can evolve since each System is different than others in the Past.
I hope this Blog Reading is Informative and How atmospheric science is very unpredictable here in the Cowboy St. As we near March/April (more snowier months), its good to know how Weather can change in a drastic change..from Nothing to BIG or oppositely like this past weekend.
** KEEP IN MIND, much of WY is still in a Surplus this Fall/Winter for Moisture and Snowpack which is great for upcoming Summer **
-MS
Before I talk about our Snow Update, have to say Happy Meteorological Spring! Well, its not even warm enough to say it, but sure its COLD and Snowy. Technically we all know the Astronomical Spring that starts on March 21st.
SNOWTalk:
Many are probably bummed that the Snow hasn't performed to what we hoped or forecasted for. Bands of Snow churned in well last night at times but the Intensity couldn't last at a longer duration. Many have seen a Lull in the Activity, but the main reason are the COLD Temperatures in the Lower Single Digits and Sub-Zero Temps:
If you want Snow, you have to lots of moisture and semi-Cold Air. Our "re-inforcement" shot of Cold Arctic Air really affected the Moisture as it ate into Central/Eastern WY. High Pressure builds in and will keep us very cold Tonight.
MOISTURE still continues as we look at the Infrared Imagery in Central WY.
-- InfraRed Imagery shows the Colder cloud tops and the deeper Moisture or Light to Moderate Snowfall rates. The Boundary has pushed a little Farther Southwest than I thought along I-80 and the best Snow bands continue for Western WY where reports of 3' of snow has fallen in the Tetons.
- It has been very hard to get the snow to fall this afternoon to accumulate in Casper, but Drier Air from the High is much denser than the moist air trying to over-ride.
Thoughts: Snow wants to fill in later this evening as a new Disturbance is forecasted to move through so could see some lighter amounts. WINTER STORM WARNINGS still continue for Central, Northern, and Western WY until early Sunday. I may have over amounted, but Model Guidance trended High. I was concerned about the Deep Arctic Air that may win out and so far, it is.
LAST Post of the Evening Folks,
For the last Few Hours I have been watching the continuous plume of Moisture evolving from UT spreading Northeast in WY. Mainly its been Intense with deep rich color of Bright Blue cold cloud tops that shows lots of Moisture falling as Snow since we are well below Freezing.
-- Its beginning to Snow in Riverton and Rock Springs and sometimes a Mix intermittently since the Boundary has stalled along I-80.
The BIG LOW is just off the Coast of CA still, but still sending Moisture Eastward into the NV Basin and UT. We will begin to watch the Lows in Southern ID and UT spreading more Snow Chances for WY through the rest of Overnight and Morning Hours. Just closely watching if any Dry Air surges in off the Plains as our "re-inforcement" shot of Colder Air can cause havoc with the Snowfall. WE'LL SEE! So far, forecast looks to be on par!
With the Snow we have currently, here's how much snow is possible on top of what we already have. This is the HI-RES Hourly Model showing snowfall through 12PM SATURDAY.
Evening Folks,
It has been an Overwhelming Day of forecasting our Snowstorm. Moisture and Jet Stream Dynamics are increasing along our Stalled Boundary along I-25.
<< Over-Running Moisture from CO is streaming North along I-80 and in the I-25 Corridor as the Frontal Boundary is stalled. Moisture from CA is slowly beginning to fill in. This is why the Heavier Snows should set up perfectly for Central WY and through the Laramie Range.
<< At the Surface, here is the Radar shot at 7PM. Moisture is funneling into Central WY and that snow is beginning to fill in on Radar SW of Casper moving Northwest. Heavy bursts of snow are possible for several Hours.
TIMING OUT THIS STORM:
<< TONIGHT through Saturday Afternoon
<< SATURDAY Afternoon through Sunday
SO HOW MUCH SNOW Am I Forecasting??
Latest Hourly Weather Data shows Accumulation beginning to pick up fast late this Evening. The HI-RES Rapid Refresh (HRRR) through 7AM Saturday shows about 3-6" of Snow in the Casper area and lighter amounts elsehwhere:
Good late Evening!
Lets look at all the SNOW AMOUNTS from Various Forecast Models I use as Tools to Plot my Snowmap
Evening Run from NAM HI-RES.
<< The Snow Amount Legend is at the Top.
Evening Run from the GFS through 11PM SUNDAY
This is the Iowa St Meteogram that shows the "Range of Snow from various Models" I use this a lot in Big Snow Events. This is for CASPER (Airport). Since the City is closer to the Mountain and in a Bowl, snow Amounts can be a little Higher than this.
THIS is our In-House Model Data of the RPM. The data goes out all the way through 8AM Saturday. The Legend on the Right is in Inches.
EVENING FOLKS!
Quite a Mild and 'not as breezy' Thursday for the Laramie Range with Highs in the Mid to Upper 40°s, even a 50° in Cheyenne!
Anyone ready to get the BREAD & MILK?
** This is how many people back in my Hometown and Region react when Snow (even Light Amounts) is in the Forecast >>>THEY SAID SNOWWWWWW **
LATEST Watches and Warnings for the Upcoming Storm:
Warnings ~PINK
Watches ~ BLUE
Advisories ~ PURPLE
Latest RADAR from Thursday 8PM:
<< Snow Showers could still be falling for Southwest WY in Uinta Co through this Evening from Evanston to Lyman. Watch for Slick Spots and some blowing snow possible.
WEATHER MODEL TALK:
- 1ST Off, all Three Big Long Range Models I use to Forecast still show the Big Snow arriving Overnight Friday through early Saturday Afternoon. A Frontal Boundary stalls along I-25 as a Strong Low moves into Idaho and drops Southeast through Southwest WY. On top of that, COLD Arctic Air invades in MT and the Dakota's as High Pressure builds with Temperatures in the Lower Teens or Single Digits. The High brings an Easterly Wind Component while the Low brings South/Southwest Wind. Moisture will move over the Cold Easterly Wind and lots of Snow is "Possible" in Central WY.
- 2ND, I have been closely watching the "unpredictable" NAM Model all day today. BAD News, it Trended Wet and Moist for Central WY. I discussed Upslope and Isentropics in my Last Blog so if you are confused on them, refer back to my Wednesday's post. The Over-Running Moisture (Isentropics) is possible for Southern WY as I think parts of Central WY and Laramies may experience an Upslope Effect (Wrap-Around) Flow of a Low. But if we look at 10,000 Feet up, it shows a Southwest flow for Central WY. In other words, a very challenging forecast for a Moisture-Rich storm.
BRIEF TIMELINE for Storm System #1 as we roll into the Overnight Hours and last through Friday "Early" Evening:
** ONCE We move into Late Friday and through Saturday Morning, Hazardous Travel is very likely for a good chunk of I-25 & I-80 Corridor as Moderate-Heavy Snowfall (1-2"/HR) Rates are possible. **
FRIDAY'S Forecast:
<< Once the Cold Front drops through I-90 and into the I-25 Corridor, Temperatures will drop with Snow Showers likely. Snow Showers are possible through the late Morning and Early Afternoon so visibilities will be reduced.
THOUGHTS: As you see, I DID NOT release any Snow Amounts this Evening and in this Blog. Still a few Questions remain for me since will this Cold Air dry out any Moisture for Snow to dump in Central/Eastern WY? Plus, will the Low stay on track from CA to Idaho and slide into Southwest WY? Models slowly tend to agree with each other, but the Best thing is that we have ONE More Day on Friday to Forecast.
*MODERATE to HEAVY Snow is Still Possible where a Winter Storm Warning/Watch is Out*
-ms
