The Winter Storm Outlook

By -
Whew! This is a tough one. Normally, I would not have tried to forecast the winter storm six days in advance but there is tremendous interest due to Christmas travel. Unfortunately, there is little confidence in this forecast.

Here's why. The low pressure system that will turn into our winter storm is over the Gulf of Alaska (pink circle showing storm at 15,000 feet). While there is useful weather satellite coverage, there are no weather balloons and few aircraft sampling the atmosphere. So, the computer models have a difficult time when there is low confidence in their analysis of the current state of the atmosphere.


The storm now over the Gulf of California is forecast by the models to move over far northern Mexico Sunday night. Snow is likely in El Paso (while it is raining in Toronto)! A second storm should get close enough to the first (i.e., within 1,500 miles) that it will "kick" the first storm northeast (purple arrow). If so, there will be a major snow storm in the Plains. 
However, if the storm is not "kicked" by the second, it will take a much more southerly path (green arrow) and there will be little or no snow! Note: Snow falls to the north and northwest of an upper level low. The detour into Mexico creates a longer path for the low to cover and so causes the low to slow down a bit.

So, here is the likelihood of 6" or more of snow Saturday afternoon through Monday.
Check your local AccuWeather forecast for specific amount for your location.

Comments

Post a Comment

Popular posts from this blog

Hilary's Forecast Path Shifts West; Updated 9:20am PDT

By -
Image
The forecast path of the center of Hilary has shifted a bit to the west. This increases the threat to the Southland, especially in terms of flooding.  Rainfall Note the heavy rains are forecast for Los Angeles County. Serious flash flooding may result. Because the forecast path has shifted to the west, that increases the threat of serious flooding in Los Angeles County north into Yosemite and the southern Sierra. It lessens the threat in Utah and western Arizona. While the threat of widespread flooding in Utah and Arizona lessens, note that some thunderstorms with localized heavy rain show up on the map.  In Nevada, the more western path increases the risk of serious flooding around Mt Charleston and into the central part of the state.  Here is the updated  (9am PDT) flash flood risk map. Wind There are already about 40,000 people without power in California, mostly in the center of the state.  The maps above are the peak gusts forecasted with the storm. The highest winds, in general,
Read more

Dangerous Travel Conditions - People Reportedly Stranded

By -
Image
-- Note, more current info available. Scroll up. --- Updated Information as of 8am PDT You are risking your life if you attempt to travel through the purple area.  While the rain has not begun in coastal California, I would urge you to use this time to make any preparations. Power outages have occurred already in southeast California. Here is the latest radar as of 7:55am PDT. As of 6:40am PDT , the radar indicates moderate to heavy rain falling over desert areas of Southern California and far western Arizona (click to enlarge).  Rainfall amounts for the 24 hours ending at 7am PDT show more than two inches have already fallen. There are reports from reliable sources that roads are already washed out and that people are stranded in isolated parts of the desert.  Below is a high-resolution computer model's rainfall forecast from 5am PDT to 11pm PDT Sunday. More than a foot of additional rain is forecast to fall. This will lead to catastrophic flooding.  Here is a map of current watc
Read more

Update on Tornado and Wind Potential; 12 Noon PDT

By -
Image
There was at least one tornado and at least one funnel cloud yesterday.  --- original forecast --- Hilary (the swirly symbol) continues to move NNW paralleling the coast of Baja California, Mexico. The area outlined in red has a significant risk of tornadoe s the rest of the afternoon.  Below is a list of peak wind gusts so far.  Peak winds may increase farther north as the afternoon progresses.  Addition at 12 noon PDT: Sure enough, winds have increased.  Note: If you are in the San Diego area, I recommend not  traveling east on I-8. Heavy rains may cause flash flooding that will involve the highway. 
Read more