wxgeek's weather-More snow-Update wed Oct 25

Update Thu Oct 25

In general, snowfall from Wednesday evening/night amounted to 1-3 inches around the Metro area, and 4-6 inches in the foothills and some western and southern Metro areas, so little higher in southern areas than I thought, but in general the commute wasn't too bad.

Round 2 remains on track for late this afternoon into Friday morning. Snow will move into the northern and central mountains this afternoon, and spread east into the foothills and Urban Corridor by late this afternoon and evening, and into the Plains this evening. Snow should persist into late tonight or early Friday morning most areas, then begin to dissipate, except on the far eastern Plains where snow may persist into later Friday morning. Snow amounts for round 2 look like this:

Northern and Central Mountains: 4-8 inches
Foothills and Palmer Divide: 2-6 inches, up to 8 inches southern areas
Banana Belt: 1-3 inches
Urban Corridor: 1-4 inches
Plains: 1-3 inches

Friday morning commute likely to have more snow and ice on roads due to much colder temps, but by evening roads should be mostly clear.
Mix of sun and clouds the remainder of Friday with temps well below seasonal averages, and very cold temps overnight and Friday night. General warming trend under mostly sunny skies on tap for this weekend, with temps warming back closer to seasonal norms, although still on the cool side of average.

Long range models now suggest dry and mild conditions will persist through all of next week, and likely into next weekend. Next precip chances currently look like late the following week, although that can always change.

Very interesting scenario taking shape with respect to hurricane Sandy. Sandy is now loctaed in the central Bahamas with maximum sustained winds of 105 mph, so a high end category 2 hurricane. Models now forecast Sandy to continue on a northward track parallel with the east coast of Florida through Saturday morning, and then turn slightly towards the north northeast towards the North Carolina outer banks. Models keep the eye offshore, but close enough to land to bring heavy rainfall, high winds and heavy surf to coastal areas of FL, GA, SC adn NC. Now to the "Frankenstorm" reference being used in the media. Sandy is expected to remain a hurricane over the weekend and remain just off the mid Atlantic coast. Models are now forecasting that the upper level trough we are experiencing will move towards the east coast this weekend, and literally suck Sandy northwest into the Northeast coast early next week, while combining with much colder air from the upper level trough. Scenarios like this are fairly rare, but have occured in the past in the "Perfect Storm" in 1991, and with hurricane Hazel in 1954. In this case, models intensify Sandy, have it become an "extratropical" storm and slam into the northeast coast somewhere along the NJ, NY or CT coast on next Tuesday into Wednesday, hence the halloween reference. If this scenario plays out even close to what models are currently suggesting, the Northeast would experience a Nor'easter of nearly unprecedented intensity. Winds could be 70-100 mph, waves of 20-30 ft hitting coastal araes for 12-36 hours, and 10-20 inches of rain. This could severely impact commerce over a large section of the mid Atlantic and Northeast next week. If anyone is planning travel to the East Coast, and especially the Northeast next week, keep a close eye on how this storm tracks and develops. The ripple effect on travel could be quite widespread.
_________________
"Climatology is what you expect, Weather is what you get".

"It is better to be roughly right than precisely wrong".

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After our very dry and warm start to October, winter will pay us a brief visit over the next few days. First I want to say thanks for the very kind words some of you posted yersterday, I am very humbled and touched by your kindness. The reality is that I get to discuss the weather here frequently, so my wife is really the big beneficiary, as she doesn't have to listen to my weather ramblings nearly as much Smile

First impulse from the large upper low off the WA coast has moved into the Great Basin, and will move across CO later today and tonight. An initial cold front moved south across CO overnight, which cooled temps and brought some low clouds into the Front Range and foothills. Precip band just beginning to move into northwest CO with snow level around 6000-7000 ft northern mountains, and 8000-9000 ft central mountains. Models are doing a bit of a tango the past few days, flip flopping between the two impuleses that will affect us. After looking at a variety of data, here are my conclusions (read, my guess at what will happen).

The first inpulse has a lot of dynamics associated with it, but the vast majority will remain north of CO, so WY gets the biggest impact from this first impulse that will move through today into tonight. Hence in CO, areas north of I-70 will receive the highest precip amounts from this system. The other factor is that upslope flow remains fairly shallow, only up to about 9000 ft with westerly flow above that which limits snow amounts in our foothills. Snow level over the foothills and Plains will begin around 9000 ft today and remain there through 6 pm this evening. Second surge of cold air will move south through CO after that, which will begin to lower snow levels dramatically. By midnight, snow level should be down to 5000 ft. Snow will become heavy through the afternoon and tonight across the northern and central mountains. Precip will spread east into the foothills and Plains by this evening and persist into tonight. Here are my snow forecast from 3 pm today through 9 am Thursday:

Northern and Central Mountains: 4-8 inches
Foothills north of I-70: 1-3 inches
Foothills south of I-70: trace to 1 1/2 inches
Metro Area and Plains north of I-70: trace to 2 inches
Metro Area and Plains south of I-70: trace to 1 inch

Precip should abate by Thursday morning, so the morning commute should be ok from a precip and visibility standpoint. I believe roads below 7000 ft will just be wet, some slush possible above 7000 ft and snow and ice pack above 8000-9000 ft. Just a mix of sun and clouds during the day on Thursday until the next impulse makes it's way into CO later Thursday afternoon. Snow will pick up in the mountains Thursday afternoon and move into the foothills by late afternoon and evening. Snow will spread into the Plains by evening. The second impulse now looks more significant for CO than the first, and may have some convective elements associated with it, which could add to some localized moderate snow. Heaviest snow amounts from this second system appear to be south of I-70 down to about US 50. So snow amounts from 3 pm Thursday to 9 am Friday look like this:

Northern and Central Mountains: 3-7 inches
Foothills north of I-70: 1-3 inches
Foothills south of I-70 and Palmer Divide: 2-5 inches
Urban Corridor and Plains north of I-70: 1-2 inches
Urban Corridor and Plains south of I-70: 2-4 inches

The Friday morning commute could be slick with additional snow and colder temps. Precip should abate by Friday morning, with clearing skies by afternoon. Expect much colder temps from tonight through Saturday. High temps on Thursday in the 30's for the foothills and Plains, with low temps Friday morning in the teens in the foothills, and low 20's Plains. Highs Friday in the 20's for foothills and 30's Plains. Low temps Saturday morning low teens for foothills, and low 20's for Plains. Highs in the 40's on Saturday for the foothills and low 50's Plains.

Basically a good first snowstorm across CO, providing good snow for the mountains to get the ski season going, and our first significant snow in the foothills that will help lower fire danger for a while and keep the ground nice and moist.

Long range models indicate dry and mild conditions Sunday through Wednesday of next week, then a chance for some precip next Thursday and Friday. Too early to tell how much precip at this point.

Hurricane Sandy is located just south of Kingston, Jamaica with maximum sustained winds of 80 mph making Sandy a category 1 hurricane. Sandy will move across Jamaica this afternoon and move across eastern Cuba tonight, then move into the Bahamas on Thursday. Sandy may lose some strength crossing Cuba, but will either be a cat 1 hurricane or strong tropical storm as it moves into the Bahamas. Latest track from the TPC keeps Sandy away from the US mainland, but close enough to southeast FL to bring tropical storm force winds, heavy rain and surf on Friday. After Friday the track of Sandy is in some debate, as some models keep the storm much closer to the Southeast coast, skirting the outer banks of NC, and other models swing the storm out to sea towards Bermuda. If the track remains closer to land, much of FL, GA, SC and NC could see significant rain, wind and waves, as well as parts of the mid Atlantic coast.
_________________
"Climatology is what you expect, Weather is what you get".

"It is better to be roughly right than precisely wrong".

Great update! What do you make of the possible "perfect storm" that might hit the eastern coast?

So far we had more snow from the last snowstorm but it didn't stick on the roads like this one did.

Bump for Oct 25 update

Wow, never thought I'd see a weather forecast that said it would "literally suck Sandy."