Can you explain what this is showing for us non weather folk? Thank you!
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The first one is from the Storm Prediction Center showing where in the US severe weather is forecasted, think thunderstorms, rain, hail and wind, are forecasted, and how likely. Ie âMarginalâ or âslightâ chance. Hereâs a link to their description for today:
The second graphic is just forecasted rain totals.
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Michael Snyder of Northwest and Ca Weather Watch posts a monthly ENSEO update. This months has fantastic detail of what it is and how it affects west coast weather. It also gives a really good explanation of model
trends and agreement.
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Well it has rained here all morning in Nevada City. Drainage ditches are running.
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Hottest July on record for California, next month snow. Every time I add DEF to my masticator it cools Earth by .000000000000001* Fahrenheit
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Middle to the end of next week looks like potential for some very low RH with warm temps. Strong thermal trough establishing and maybe bringing some critical weather??
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No adverse weather is forecasted for the Labor Day weekend and extended forecast period (thru Sept 7th). Temperatures will be monitored in the Bay Area for stress on the electrical grid, but nothing on the horizon for fire weather.
Middle to the end of next week in the models right now shows a mult-day run of temps over 100 in the valley and single digit RHâs. If the thermal low develops with single digit RH we could see a period of winds similar to the start of the Park fire.
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A weak low-pressure system is forecast to move through the territory Sunday and Labor Day with temperatures across the far interior decreasing back to near or slightly above average and into the 90s. Coastal areas and valleys should also be slightly cooler and mostly seasonable. That low pressure system may also produce scattered showers and very isolated thunderstorms over the Sierra and northern mountains Saturday and Sunday, generally away from assets. High pressure will then rebuild next week resulting in fair and warmer weather, including hot temperatures across the interior. Isolated afternoon showers and thunderstorms will also be possible again over the high Sierra by mid-week. Cooler weather is favored to return to the territory by the end of next week for the coastal and Bay regions and across the interior over the following weekend. No adverse weather is currently forecast for the Labor Day weekend and extended forecast period
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I would point out that the trough passage will bring about an offshore wind pattern that will focus the low end winds on the usual spots in NOPS. That gradient will enhance down canyon winds in the typical spots. The large scale result will be warming and drying across the region. By Wednesday temps in the valley will be above normal and remain there through the end of the week. RH will approach single digits at times. The models diverge at the end of the week with regard to the strength of the next trough, the Euro brings about more robust cooling while the GFS remains warmer with a second heat wave to follow. The ensembles( blend) tend to be more along climatology with a middle of the road approach.
What does stick out is the changing patterns. Saturday-Monday will feature some very strong winds and a Haines of 6 in the NW mountains and that has been highlighted for the Shasta Valley and areas of the Modoc. The temps there are above normal now and will remain there through Saturday mitigating any effects from the recent rain. There are slight chances of lightning from some convection but most of that seems to be confined to areas east of the Cascades.
As the trough moves inland it does appear that some strong on shore flow will accompany it as would be expected. That transition is where the adverse weather will appear. Hot temps this week, strong winds over the weekend into Monday and then a transition back to offshore flow and hot temps again by early next week. Add in the holiday effectâŚ
If you really want to dig into the details⌠a thermal trough looks to establish by Wednesday. This sinking air will enhance some downslope winds at night and can cause a very dry slot of air above the inversion to reach ground level. These scenarios help to bring about the âsecondâ burn period which occurs overnight. This has had serious impacts on existing fires.
The thermal trough can enhance downslope winds at night and in am, only to have the normal dirunal winds arrive by mid afternoon. These are not uncommon or a situation that shouts watch out⌠unless you have an established fire.
As for the end of the week⌠kind of muddy right now, but it does look like another transition to a cool down⌠more wind.
I would also state⌠I am not an IMET⌠my information is derived from NWS Medford, Sacramento, and Monterey AFDâs and the weather discussion from PDS. Attached are two graphics, one of the wind direction( 850 mb charts) and offshore gradients mid week and the other of the temps. If you would like I can add the RH and graphics showing the formation of a thermal trough.
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So why did the NWS issue a Fire Weather Watch???
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I suspect your information is coming from a utility based perspective, that observation is based on the word"assets".
There is a contrast between threat to infrastructure and critical fire weather. Not all critical weather patterns are a direct threat to infrastructure until a fire begins.
I am not sure this event will rise to a FWW but if the RH and temps last long enough it might. If it did not, it would be based on duration of event( a limiting factor).
Looking at all the models it does appear that some periods of enhanced fire weather will be present across NOPS this week. While it might not rise to a watch or warning level⌠it should be noted. Not sure I would go out on a limb and state that any product is better than the NWS⌠they are and should be the default voice on fire weather products. They spend a lot of time working with local FBANS and PDS in the respective regions when they issue a fire weather product.
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