Saturday, November 16, 2013
Snow continues this afternoon between the two waves before the main cold front arrives around sunset, Sharply colder temperatures and a burst of heavy snow is likely with snow continuing through the night as cold and moist northwest flow traverses the region. Likely an additional 6-12” or more by Sunday morning on the hill, with showers tapering off during the morning and ending by the afternoon as the cold air mass stabilizes.
Temperature will warm significantly on Monday and stay warm for at least Tuesday. A very weak wave traverses the northern part of our state on Wednesday leading to clouds and possibly some showers in seasonably warm air.
A stronger group of wave moves across the area around beginning Thursday afternoon and continuing through the day Friday. The European model has in the past few model runs split the jet stream which would weaken the storms in our area as most of the energy is forecast south of us, while the American model still brings these waves across in a coherent manner. Stay tuned as model differences are resolved in later forecasts.
Friday, November 15, 2013
Rain in the valleys and snow on the hill should begin by this afternoon as temperatures start to gradually cool. Probably 2-4” around mid-mountain by Saturday morning.
There may be a smal break earlier Saturday before the main event begins to affect our area by later in the day. Sharply colder air and a burst of heavy snow should cross the area around sunset, with snow continuing through the night as cold northwest flow engulfs the region. Likely an additional 6-12” by Sunday morning on the hill, with showers tapering off during the morning and ending by the afternoon as the cold air mass stabilizes.
Temperature will warm significantly on Monday and stay warm through mid-week. A very weak wave traverses the northern part of our state on Wednesday leading to clouds and possibly some showers in seasonably warm air.
A stronger group of wave moves across the area around beginning Thursday afternoon and continuing through the day Friday. This may produce significant precipitation as winds are forecast to turn to the northwest while cooling, though earlier model runs had this wave more split, so the forecast will evolve.
Wednesday, November 13, 2013
A weak wave moving over our area tonight will produce some slight cooling and possibly light precipitation by the morning. A second wave now looks to impact our area by later Friday followed by a much stronger and colder third wave Saturday night.
While all models predict some precipitation by Saturday morning, subtle differences between them create uncertainty for our area. Specifically, 1-3” is expected on the hill by Saturday morning unless the winds turn northwest behind the first wave, in which case I would expect 3-6”.
A front stalls over our area between these two waves leading to cool and showery precipitation early in the day Saturday. As the trough to our west begins to move eastward, the stalled front will begin moving south around sunset, increasing precipitation and decreasing temperatures during late afternoon and continuing through the night.
I would expect this thrid wave to bring significant precipitation by Sunday morning. The trough is expected to bring favorable mountain-top northwest flow to our area by early Sunday, enhancing snowfall rates, especially near sunrise. The storm will grow colder as it evolves from Saturday night through Sunday afternoon, so snow densities will be decreasing, increasing the snow quality. I would guess a very tentative 6-12” or more by Sunday afternoon on the hill.
Monday morning will be dry but seasonably cold, with rapidly warming conditions by Tuesday and Wednesday.
Another dry and weak storm is currently forecast later around midweek, and possibly some interesting weather by next weekend as cold air is predicted to be lurking just to our north.
Tuesday, November 12, 2013
Signficant changes in the American GFS model over the last few runs has brought the model forecast closer to the European ECMWF forecast. The end result is that light precipitation won’t begin till Friday and a possibly significant winter-like storm develops by Sunday.
The first wave I was expecting to produce precipitation by Thursday morning looks drier and weaker and will likely only produce some slight cooling over our area. The second wave originally timed for Thursday night looks to hold off for 12-24 hours creating only light precipitation by late in the day Friday or overnight.
Weather will be seasonably cool and showery during the day Saturday as a strong wave amplifies along the west coast. Originally, the American GFS model has this wave traveling over the area as a much weaker and faster system, but the last few runs now agree with the European ECMWF model that the system will be much stronger and slower.
If the storm does not dig further to our west in subsequent model runs, I would expect the storm affect our area by Saturday evening and bring signficant precipitation by Sunday morning. The trough is expected to bring favorable mountain-top northwest flow to our area sometime on Sunday, enhancing snowfall rates, expecially near sunset. The storm will grow colder as it evolves from Saturday night through Monday morning, so snow densities will be decreasing, increasing the snow quality. I would guess a very tentative 6-12” or more by Monday morning on the hill.
The trough should be east of us by Monday morning, fringing rapidly warming and dry conditions through the rest of the week.
Another storm is currently forecast for the following weekend, but there is much uncertainty in the forecast for THIS weekend, much less NEXT weekend!
Monday, November 11, 2013
It appears model differences have largely been resolved for the pattern change beginning on Thursday, with the American ‘GFS’ (Global Forecast System) model coming into line with the European ‘ECMWF’ (European Center for Medium Range Weather Forecasting) model. As a side note, I publish these models in the numerical weather prediction section found under the ‘Models’ menu item.
A wave over northwestern Canada will progress southward bringing some cold air along the Front Range around Tuesday as it travels over the western ridge. Additionally, some energy from the eastern Pacific trough will move through the ridge late Wednesday bringing light showers and seasonably cool air to our area. While moisture is not plentiful, the favorable wind direction from the northwest and cooling atmosphere should be enough to produce 2-4” on the mountain by Thursday morning.
Another wave quickly follows allowing little break between systems. This slightly stronger and colder wave should produce an additional 4-8” on the hill by Friday morning.
Temperatures should warm on Friday before additional weak and very dry waves move across by Saturday morning and again Sunday morning. There may be some showers early Sunday morning, though any accumulations should be insignificant.
Another dry wave on Tuesday will mark the end of this pattern where weak waves travel around the dominant western ridge. Models indicate the eastern Pacific trough / western ridge couplet moving eastward by the end of next week signalling another pattern change.